SIC semiconductor component

Abstract

A SiC semiconductor device comprising: a SiC layer of a first conductivity type having a main surface, an active region located in an inner portion of the main surface, an outer peripheral region located in a peripheral edge portion of the main surface, and a pillar region of a second conductivity type formed in the SiC layer at an interval in the horizontal direction along the main surface and having impurity regions positioned in both the active region and the outer peripheral region.

Description

Technical area

[0001] This application claims priority to Japanese Patent Application No. 2022-212615, filed on December 28, 2022, and the entire contents of that application are hereby incorporated by reference. The present disclosure relates to a SiC semiconductor device. background

[0002] Patent Literature 1 (US 2015 / 0028351 A1) discloses an electronic component having an impurity region introduced into a silicon carbide layer by a channel implantation method. Citation listPatent literature

[0003] Patent Literature 1: Publication of Patent Application in the United States No. 2015 / 0028351 Specification [Summary]

[0004] The present disclosure provides a novel SiC semiconductor device.

[0005] The present disclosure provides a semiconductor device comprising: a chip having a side surface; and a structural pattern formed in the side surface.

[0006] The present disclosure provides a SiC semiconductor device comprising: a first SiC layer of a first conductivity type having a first axial channel aligned along a lamination direction, a second SiC layer of the first conductivity type having a second axial channel aligned along the lamination direction and laminated on the first SiC layer, a first region of a second conductivity type extending along the first axial channel in the first SiC layer in cross-sectional view and extending in a first extension direction in plan view, and a second region of the second conductivity type extending along the second axial channel in the second SiC layer in cross-sectional view and extending in a second extension direction intersecting the first extension direction in plan view,so that the second area overlaps with the first area in plan view.,

[0007] The present disclosure provides a SiC semiconductor device comprising: a SiC layer of a first conductivity type having a main surface, an active region disposed in an inner portion of the main surface; an outer peripheral region disposed in a peripheral edge portion of the main surface; and a pillar region of a second conductivity type formed in the SiC layer at an interval in the horizontal direction along the main surface and having impurity regions disposed in both the active region and the outer peripheral region.

[0008] The present disclosure provides a semiconductor device comprising: a semiconductor layer of a first conductivity type having a main surface and an axial channel oriented along a thickness direction; an impurity region of a second conductivity type extending along the axial channel in the semiconductor layer; a body region of the second conductivity type formed in a region on one side of the main surface with respect to the impurity region; and a gate structure comprising a trench penetrating the body region in the main surface, an embedded electrode arranged closer to a bottom wall of the trench than to the main surface, and an embedded insulator arranged closer to the bottom wall of the trench than to the main surface and covering the embedded electrode.

[0009] The above or other objects, features and effects will be made clearer by the following description with reference to the accompanying drawings. Brief description of the drawings [ Fig. 1] Fig. 1 is a plan view of a SiC semiconductor device according to a first embodiment. [ Fig. 2A] Fig. Figure 2A is a cross-sectional view along line IIA-IIA in Fig. 1. [ Fig. 2B] Fig. Figure 2B is a cross-sectional view along line IIB-IIB in Fig. 1. [ Fig. 3A] Fig. 3A is a plan view showing a layout example of a chip (a first layer). [ Fig. 3B] Fig. Figure 3B is a top view showing a layout example of the chip (a second layer). [ Fig. 4A] Fig. 4A is a perspective view showing the chip together with a pattern according to a first configuration example. [ Fig. 4B] Fig. 4B is a perspective view showing the chip together with the structure pattern according to the first configuration example. [ Fig. 5] Fig. 5 is a perspective view of a main section illustrating the structural pattern. [ Fig. 6A] Fig. 6A is a perspective view showing the chip together with a pattern according to a second configuration example. [ Fig. 6B] Fig. 6B is a perspective view showing the chip together with a pattern according to a third configuration example. [ Fig. 6C] Fig. 6C is a perspective view showing the chip together with a pattern according to a fourth configuration example. [ Fig. 6D] Fig. 6D is a perspective view showing the chip together with a pattern according to a fifth configuration example. [ Fig. 7] Fig. 7 is a perspective cross-sectional view showing a first basic shape of a column portion. [ Fig. 8A] Fig. Figure 8A is a plan view showing a first layout example of the first basic shape. [ Fig. 8B] Fig. Figure 8B is a plan view showing a second layout example of the first basic shape. [ Fig. 9] Fig. 9 is a perspective cross-sectional view showing a second basic shape of the column portion. [ Fig. 10A] Fig. 10A is a plan view showing a first layout example of the second basic shape. [ Fig. 10B] Fig. 10B is a plan view showing a second layout example of the second basic shape. [ Fig. 11] Fig. 11 is a perspective cross-sectional view showing a third basic shape of the column portion. [ Fig. 12A] Fig. 12A is a plan view showing a first layout example of the third basic shape. [ Fig. 12B] Fig. Figure 12B is a plan view showing a second layout example of the third basic shape. [ Fig. 12C] Fig. Figure 12C is a plan view showing a third layout example of the third basic shape. [ Fig. 13A] Fig. 13A is a diagram showing an example of a concentration gradient in a second region (a first region). [ Fig. 13B] Fig. Figure 13B is a graph showing an example of the concentration gradient of the second region (the first region). [ Fig. 11C] Fig. Figure 11C is a graph showing an example of the concentration gradient of the second region (the first region). [ Fig. 13D] Fig. Figure 13D is a graph showing an example of the concentration gradient of the second region (the first region). [ Fig. 13F] Fig. Figure 13F is a graph showing an example of the concentration gradient of the second region (the first region). [ Fig. 14] Fig. 14 is a diagram showing a comparative example of the concentration gradient of the second region (the first region). [ Fig. 15] Fig. 15 is a perspective cross-sectional view showing a pillar portion according to a first configuration example. [ Fig. 16] Fig. 16 is a diagram showing an example of a concentration gradient of the Fig. 15 shows the column area. [ Fig. 17] Fig. 17 is a perspective cross-sectional view showing a pillar portion according to a second configuration example. [ Fig. 18] Fig. 18 is a diagram showing an example of a concentration gradient of the Fig. 17 shows the column area. [ Fig. 19] Fig. 19 is a perspective cross-sectional view showing a pillar portion according to a third configuration example. [ Fig. 20] Fig. 20 is a diagram showing an example of a concentration gradient of the Fig. 19 shows the column area. [ Fig. 21] Fig. 21 is a perspective cross-sectional view showing a pillar portion according to a fourth configuration example. [ Fig. 22] Fig. 22 is a diagram showing an example of a concentration gradient of the Fig. 21 shows the column area. [ Fig. 23] Fig. 23 is a perspective cross-sectional view showing a pillar portion according to a fifth configuration example. [ Fig. 24] Fig. 24 is a diagram showing an example of a concentration gradient of the Fig. 23 shows the column area. [ Fig. 25] Fig. 25 is a perspective cross-sectional view showing a pillar portion according to a sixth configuration example. [ Fig. 26] Fig. 26 is a diagram showing an example of a concentration gradient of the Fig. 25 shows the column area. [ Fig. 27] Fig. 27 is a perspective cross-sectional view showing a pillar portion according to a seventh configuration example. [ Fig. 28] Fig. 28 is a diagram showing an example of a concentration gradient of the Fig. 27 shows the column area. [ Fig. 29] Fig. 29 is a perspective cross-sectional view showing a column portion according to an eighth configuration example. [ Fig. 30] Fig. 30 is a diagram showing an example of a concentration gradient of the Fig. 29 shows the column area. [ Fig. 31] Fig. 31 is a perspective cross-sectional view showing a pillar portion according to a ninth configuration example. [ Fig. 32] Fig. 32 is a perspective cross-sectional view showing a pillar portion according to a tenth configuration example. [ Fig. 33] Fig. 33 is a perspective cross-sectional view showing a pillar portion according to an eleventh configuration example. [ Fig. 34] Fig. 34 is a perspective cross-sectional view showing a pillar portion according to a twelfth configuration example. [ Fig. 35] Fig. 35 is a plan view showing a main portion of an active area. [ Fig. 36] Fig. 36 is a perspective cross-sectional view showing a gate structure according to a first configuration example. [ Fig. 37] Fig. 37 is a perspective view showing a configuration of an outer peripheral portion. [ Fig. 38A] Fig. 38A is a cross-sectional view showing a main portion of the outer peripheral region. [ Fig. 38B] Fig. 38B is a cross-sectional view showing the main portion of the outer peripheral region. [ Fig. 39] Fig. 39 is a perspective cross-sectional view showing a gate structure according to a second configuration example. [ Fig. 40] Fig. 40 is a schematic view of a wafer used in the manufacture of a SiC semiconductor device. [ Fig. 41] Fig. 41 is a flowchart showing an example of a manufacturing method for a SiC semiconductor device. [ Fig. 42A] Fig. 42A is a perspective cross-sectional view showing the example of a manufacturing method for the SiC semiconductor device. [ Fig. 42B] Fig. 42B is a perspective cross-sectional view taken one step after that of Fig. 42A shows. [ Fig. 42C] Fig. 42C is a perspective cross-sectional view taken one step after that of Fig. 42B shows. [ Fig. 42D] Fig. 42D is a perspective cross-sectional view taken one step after that of Fig. 42C shows. [ Fig. 42E] Fig. 42E is a perspective cross-sectional view taken one step after that of Fig. 42D shows. [ Fig. 42F] Fig. 42F is a perspective cross-sectional view taken one step after that of Fig. 42E shows. [ Fig. 42G] Fig. 42G is a perspective cross-sectional view taken one step after that of Fig. 42F shows. [ Fig. 42H] Fig. 42H is a perspective cross-sectional view taken one step after that of Fig. 42G shows. [ Fig. 43A] Fig. 43A is a schematic view illustrating a measurement step for a crystal orientation. [ Fig. 43B] Fig. Figure 43B is a schematic view illustrating the crystal orientation measurement step. [ Fig. 44A] Fig. 44A is a schematic view illustrating an ion implantation step. [ Fig. 44B] Fig. 44B is a schematic view illustrating the ion implantation step. [ Fig. 45] Fig. 45 is a plan view of a SiC semiconductor device according to a second embodiment. [ Fig. 46A] Fig. 46A is a cross-sectional view taken along line XLVIA-XLVIA in Fig. 45. [ Fig. 46B] Fig. 46B is a cross-sectional view taken along line XLVIB-XLVIB in Fig. 45. [ Fig. 47A] Fig. 47A is a plan view showing a layout example of a chip (a first layer). [ Fig. 47B] Fig. 47B is a plan view showing a layout example of the chip (a second layer). [ Fig. 48] Fig. Figure 48 is a perspective view showing the layout example of the chip. [ Fig. 49] Fig. 49 is a plan view showing a main portion of an active area. [ Fig. 50] Fig. 50 is a perspective cross-sectional view showing a gate structure according to a first configuration example. [ Fig. 51] Fig. 51 is a perspective view showing a configuration of an outer peripheral portion. [ Fig. 52A] Fig. 52A is a cross-sectional view showing a main portion of the outer peripheral region. [ Fig. 52B] Fig. 52B is a cross-sectional view showing the main portion of the outer peripheral region. [ Fig. 53] Fig. 53 is a perspective cross-sectional view showing a gate structure according to a second configuration example. [ Fig. 54] Fig. 54 is a perspective cross-sectional view showing a gate structure according to a third configuration example. [ Fig. 55] Fig. 55 is a perspective cross-sectional view showing a gate structure according to a fourth configuration example. [ Fig. 56] Fig. 56 is a perspective cross-sectional view showing a gate structure according to a fifth configuration example. [ Fig. 57] Fig. 57 is a plan view of a SiC semiconductor device according to a third embodiment. [ Fig. 58A] Fig. 58A is a cross-sectional view taken along line LVIIIA-LVIIIA in Fig. 57. [ Fig. 58B] Fig. 58B is a cross-sectional view taken along line LVIIIB-LVIIIB in Fig. 57. [ Fig. 59A] Fig. 59A is a plan view showing a layout example of a chip. [ Fig. 59B] Fig. 59B is a plan view showing a layout example of the chip. [ Fig. 60] Fig. 60 is a perspective view showing the layout example of the chip. [ Fig. 61] Fig. 61 is a perspective view showing a configuration of an outer peripheral portion. [ Fig. 62] Fig. 62 is a perspective cross-sectional view showing a diode structure according to a first configuration example. [ Fig. 63] Fig. 63 is a perspective cross-sectional view showing a diode structure according to a second configuration example. [ Fig. 64] Fig. 64 is a perspective cross-sectional view showing a diode structure according to a third configuration example. [ Fig. 65] Fig. 65 is a perspective cross-sectional view showing a diode structure according to a fourth configuration example. [ Fig. 66] Fig. 66 is a perspective cross-sectional view showing a diode structure according to a fifth configuration example. [ Fig. 67] Fig. 67 is a perspective view showing the chip together with a pattern according to a first modification example. [ Fig. 68] Fig. 68 is a perspective view showing the chip together with a pattern according to a second modification example. [ Fig. 69] Fig. 69 is a perspective view showing the chip together with a pattern according to a third modification example. [ Fig. 70] Fig. 70 is a perspective view showing the chip together with a pattern according to a fourth modification example. [ Fig. 71] Fig. 71 is a perspective cross-sectional view showing a pillar portion according to a modification example. [ Fig. 72] Fig. 72 is a cross-sectional view showing a main portion of the outer peripheral region. [Detailed description]

[0010] Specific embodiments are described in detail below with reference to the accompanying drawings. All accompanying drawings are schematic representations and therefore not drawn to scale; they also do not always correspond in terms of relative positional relationships, scale ratios, proportions, angles, etc. Like reference numerals designate corresponding structures in the accompanying drawings, and repetitive descriptions of these structures are omitted or simplified. The descriptions given before the omission or simplification also apply to the structures shown in omitted or simplified form.

[0011] When the term "essentially" is used in this description, the term includes a numerical value (shape) equal to a numerical value (shape) of the comparison target, and also includes numerical errors (shape errors) within a range of ±10% based on the numerical value (shape) of the comparison target. Although the terms "first," "second," "third," etc., are used in the following description, these serve merely as labels to clarify the order of description and are not intended to limit the content of the designations of the respective structures.

[0012] In the following descriptions, the terms 'p-type' and 'n-type' are used to indicate the conductivity type of a semiconductor (dopants). 'P-type' can be referred to as the 'first conductivity type' and 'n-type' as the 'second conductivity type'. Of course, 'n-type' can also be referred to as the 'first conductivity type' and 'p-type' as the 'second conductivity type'. 'P-type' is a conductivity type caused by a trivalent element, and 'n-type' is a conductivity type caused by a pentavalent element. The trivalent element can be at least one of boron, aluminum, gallium, and indium, unless otherwise stated. The pentavalent element is at least one of nitrogen, phosphorus, arsenic, antimony, and bismuth, unless otherwise stated.

[0013] Fig. 1 is a plan view showing a SiC semiconductor device 1A according to a first embodiment. Fig. 2A is a cross section along the line IIA-IIA in Fig. 1. Fig. 2B is a cross section along the line IIB-IIB in Fig. 1. Fig. 3A is a plan view showing a layout example (arrangement) of a chip 2 (a first layer 8). Fig. 3B is a plan view showing a layout example of the chip 2 (a second layer 9). Fig. 4A is a perspective view showing the chip 2 together with a structure pattern PT according to a first configuration example. Fig. 4B is a perspective view showing the chip 2 together with the structure pattern PT according to the first configuration example.

[0014] Fig. 5 is a perspective view of a main portion illustrating the structural pattern PT. Fig. 6A is a perspective view showing the chip 2 together with the structure pattern PT according to a second configuration example. Fig. 6B is a perspective view showing the chip 2 together with the structure pattern PT according to a third configuration example. Fig. 6C is a perspective view showing the chip 2 together with the structure pattern PT according to a fourth configuration example. Fig. 7 is a perspective cross-sectional view showing a main portion of the chip 2 together with a first basic shape of a pillar region 12.

[0015] As in Fig. As shown in FIGS. 1 to 7, the SiC semiconductor device 1A includes the chip 2 comprising a SiC single crystal. The chip 2 may be referred to as a "SiC chip" or a "semiconductor chip." In this embodiment, the chip 2 is formed from a hexagonal SiC single crystal and shaped into a rectangular parallelepiped. The hexagonal SiC single crystal has a variety of polytypes, including a 2H (hexagonal) SiC single crystal, a 4H SiC single crystal, a 6H SiC single crystal, and so on. In this embodiment, an example in which the chip 2 is formed from the 4H SiC single crystal is described, but the chip 2 may also be formed from other polytypes.

[0016] The chip 2 has a first main surface 3 on one side, a second main surface 4 on the other side, and first to fourth side surfaces 5A to 5D connecting the first main surface 3 and the second main surface 4. The first main surface 3 and the second main surface 4 are each quadrangular in shape when viewed in the vertical direction Z (hereinafter simply referred to as "top view"). The vertical direction Z is also a thickness direction of the chip 2 or a normal direction of the first main surface 3 (or the second main surface 4). The first main surface 3 and the second main surface 4 may each have a square or rectangular shape when viewed in the top view.

[0017] The first main surface 3 and the second main surface 4 are preferably formed from the respective c-planes of the SiC single crystal. In this case, the first main surface 3 is preferably formed from a silicon surface (a (0001) surface) of the SiC single crystal, and the second main surface 4 is preferably formed from a carbon surface (a (000-1) surface) of the SiC single crystal.

[0018] With respect to a circumferential direction (in Fig. 1 clockwise) of the chip 2, starting from the first side surface 5A, the second side surface 5B is connected to the first side surface 5A, the third side surface 5C is connected to the second side surface 5B, and the fourth side surface 5D is connected to the first side surface 5A and the third side surface 5C. The first side surface 5A and the third side surface 5C extend in a first direction X along the first main surface 3 and oppose each other in a second direction Y that intersects the first direction X (in particular is orthogonal thereto). The second side surface 5B and the fourth side surface 5D extend in the second direction Y and oppose each other in the first direction X.

[0019] In this embodiment, the first direction X is an a-axis direction (a [11-20] direction) of the SiC single crystal, and the second direction Y is an m-axis direction (a [1-100] direction) of the SiC single crystal. That is, the first side surface 5A and the third side surface 5C are each formed from m-planes ((1-100) planes) of the SiC single crystal. The second side surface 5B and the fourth side surface 5D are also formed from a-planes ((11-20) planes) of the SiC single crystal.

[0020] The a-plane is a crystal plane orthogonal to the a-axis direction, and the m-plane is a crystal plane orthogonal to the m-axis direction. Of course, the first direction X may be the m-axis direction of the SiC single crystal, and the second direction Y may be the a-axis direction of the SiC single crystal. Each of the first to fourth side surfaces 5A to 5D may be formed from a ground surface. Each of the first to fourth side surfaces 5A to 5D may be formed from a cleavage surface.

[0021] An XY plane including the first direction X and the second direction Y forms a horizontal plane orthogonal to the vertical direction Z. Hereinafter, an axis extending in the vertical direction Z may be referred to as the "vertical axis." The first direction X and the second direction Y may also be referred to as the "horizontal direction." The horizontal direction may also be a direction extending along the first main surface 3.

[0022] As in Fig. As shown in Figure 7, the chip 2 (the first main surface 3 and the second main surface 4) has a deviation angle θoff tilted at a predetermined angle in a predetermined deviation direction Doff with respect to the c-plane of the SiC single crystal. That is, a c-axis (a (0001) axis) of the SiC single crystal is tilted by the deviation angle θoff from the vertical axis in the direction of the deviation direction Doff. The c-plane of the SiC single crystal is also tilted by the deviation angle θoff from the horizontal plane.

[0023] The deviation direction Doff is preferably the a-axis direction (i.e., the first direction X) of the SiC single crystal. The deviation angle θoff may exceed 0° and not exceed 10°. The deviation angle θoff may have a value falling within any of the following ranges: more than 0° and not exceeding 1°, not less than 1° and not exceeding 2.5°, not less than 2.5° and not exceeding 5°, not less than 5° and not exceeding 7.5°, and not less than 7.5° and not exceeding 10°.

[0024] The deviation angle θoff is preferably not more than 5°. The deviation angle θoff is more preferably not less than 2° and not more than 4.5°. The deviation angle θoff is normally set within a range of 4° ± 0.1°. Of course, this description does not exclude a shape in which the deviation angle θoff is 0° (ie, a shape in which the first main surface 3 is a flat surface with respect to the c-plane).

[0025] The chip 2 has an n-type base layer 6 formed of a SiC single crystal. The base layer 6 may be referred to as a "SiC base layer," a "base region," etc. The base layer 6 extends in a layered manner in the horizontal direction and forms the second main surface 4 and a part of each of the first to fourth side surfaces 5A to 5D. In this embodiment, the base layer 6 is formed of a substrate made of a SiC single crystal (ie, a SiC substrate). The base layer 6 has the above-described deviation direction Doff and the deviation angle θoff.

[0026] The base layer 6 has a basal axis channel CHB aligned along a lamination direction. The basal axis channel CHB is formed from regions (channels) that have a comparatively large interatomic distance (atomic interval) in the SiC single crystal forming the base layer 6 and are surrounded by atomic rows that form a crystal axis extending in the lamination direction (crystal growth direction).

[0027] That is, the basal axis channel CHB consists of regions with few atomic rows extending in the lamination direction and regions where the atomic rows (interatomic distance / atomic density) are sparse in the horizontal direction in plan view. The basal axis channel CHB is preferably formed by regions surrounded by atomic rows aligned along a low-index crystal axis among the crystal axes. A low-index crystal axis, in terms of the Miller indices (a1, a2, a3, and c), is a crystal axis expressed by the absolute values ​​of "a1," "a2," "a3," and "c" being all no more than 2 (preferably no more than 1) (the same applies to this description below).

[0028] In this embodiment, the basal axis channel CHB is formed by regions surrounded by atomic rows aligned along the c-axis (the (0001) axis) of the SiC single crystal. That is, the basal axis channel CHB extends along the c-axis and has the above-described deviation direction Doff and the deviation angle θoff. In other words, the basal axis channel CHB is inclined from the vertical axis by the deviation angle θoff in the deviation direction Doff.

[0029] The base layer 6 may have an n-type impurity concentration of not less than 1 × 10 18 cm -3 and not more than 1 × 10 21 cm -3as a peak value. The base layer 6 preferably has a substantially constant n-type impurity concentration in the thickness direction. The n-type impurity concentration of the base layer 6 is preferably adjusted by a single type of pentavalent element. The n-type impurity concentration of the base layer 6 is particularly preferably adjusted by a pentavalent element other than phosphorus. In this embodiment, the n-type impurity concentration in the base layer 6 is adjusted by nitrogen.

[0030] The base layer 6 has a base thickness TB. The base thickness TB can be not less than 5 µm and not more than 300 µm. The base thickness TB can have a value that falls within one of the following ranges: not less than 5 µm and not more than 50 µm, not less than 50 µm and not more than 100 µm, not less than 100 µm and not more than 150 µm, not less than 150 µm and not more than 200 µm, not less than 200 µm and not more than 250 µm, and not less than 250 µm and not more than 300 µm. The base thickness TB is preferably not less than 50 µm and not more than 250 µm.

[0031] The chip 2 has a laminated portion 7 laminated on the base layer 6. The laminated portion 7 may be referred to as a "semiconductor layer," "SiC layer," "SiC laminate portion," "semiconductor laminate portion," etc. The laminated portion 7 has a laminated structure in which a plurality of (two or more) semiconductor layers formed from the SiC single crystal are laminated. In this embodiment, the plurality of semiconductor layers are provided as forming layers of a superjunction structure (also referred to as a superjunction structure) SJ. The number of laminated semiconductor layers (the superjunction structure SJ) is arbitrary and is adjusted depending on the electrical properties to be achieved. Examples of electrical properties include a withstand voltage value (breakdown voltage), a resistance value, etc.

[0032] The number of laminated semiconductor layers (the super junction structure SJ) is typically no less than two and no more than five (two, three, four, or five layers). In this embodiment, the laminated portion 7 has a two-layer structure including the first n-type layer 8 made of a single crystal SiC and the second n-type layer 9 made of a single crystal SiC. The first layer 8 may be referred to as a "first SiC layer," a "first semiconductor layer," etc. The second layer 9 may be referred to as a "second SiC layer," a "second semiconductor layer," etc.

[0033] The first layer 8 is laminated on the base layer 6. The first layer 8 extends in a layered manner in the horizontal direction and forms an intermediate portion of the chip 2 and a part of each of the first to fourth side surfaces 5A to 5D. The first layer 8 is formed from an epitaxial layer (ie, a SiC epitaxial layer) that is crystallized with the base layer 6 as a starting point.

[0034] The first layer 8 has a lower end and an upper end. The lower end of the first layer 8 is a starting point of crystal growth, and the upper end of the first layer 8 is an end point of crystal growth. Since the first layer 8 is continuously crystal-grown from the base layer 6, the lower end of the first layer 8 is aligned with an upper end of the base layer 6. A boundary portion between the base layer 6 and the first layer 8 is not necessarily visible and can be indirectly evaluated and / or determined based on other configurations or elements. The first layer 8 has the deviation direction Doff and the deviation angle θoff that are substantially the same as the deviation direction Doff and the deviation angle θoff of the base layer 6.

[0035] The first layer 8 has a first axial channel CH1 aligned along the lamination direction. The first axial channel CH1 is formed from regions (channels) that have a comparatively large interatomic distance (atomic interval) in the SiC single crystal forming the first layer 8 and are surrounded by atomic rows that form a crystal axis extending in the lamination direction (crystal growth direction).

[0036] That is, the first axial channel CH1 is composed of regions where the atomic rows are sparse, extending in the lamination direction and, in plan view, forming regions where the atomic rows (interatomic distance / atomic density) are sparse in the horizontal direction. The first axial channel CH1 is preferably formed from regions surrounded by atomic rows aligned along a low-index crystal axis among the crystal axes.

[0037] In this embodiment, the first axial channel CH1 is formed from the regions surrounded by atomic rows aligned along the c-axis of the SiC single crystal. That is, the first axial channel CH1 runs along the c-axis and has the deviation direction Doff and the deviation angle θoff. In other words, the first axial channel CH1 is inclined by the deviation angle θoff from the vertical axis in the deviation direction Doff.

[0038] The n-type impurity concentration of the first layer 8 is preferably lower than the n-type impurity concentration of the base layer 6. The first layer 8 may have an n-type impurity concentration of not less than 1 × 10 15 cm -3 and not more than 1 × 10 18 cm -3as a peak value. The n-type impurity concentration of the first layer 8 may be substantially constant in the thickness direction. Of course, the n-type impurity concentration of the first layer 8 may have a concentration gradient that gradually increases and / or gradually decreases in the lamination direction (crystal growth direction).

[0039] The first layer 8 has an n-type impurity concentration that is adjusted by at least one type of pentavalent element. For example, the n-type impurity concentration in the first layer 8 can be adjusted by at least one of the elements nitrogen, phosphorus, arsenic, antimony, and bismuth. The first layer 8 preferably comprises a pentavalent element other than phosphorus.

[0040] The n-type impurity concentration of the first layer 8 is preferably adjusted by at least nitrogen. When the first layer 8 contains two or more types of pentavalent elements, the first layer 8 preferably contains nitrogen and a pentavalent element other than nitrogen. In this case, the first layer 8 preferably contains one or both of arsenic and antimony as a pentavalent element other than phosphorus and nitrogen.

[0041] The first layer 8 has a first thickness T1. The first thickness T1 is preferably less than the base thickness TB. The first thickness T1 is preferably not less than 1 µm. The first thickness T1 is preferably not more than 5 µm. The first thickness T1 may have a value falling within any of the following ranges: not less than 1 µm and not more than 1.5 µm, not less than 1.5 µm and not more than 2 µm, not less than 2 µm and not more than 2.5 µm, not less than 2.5 µm and not more than 3 µm, not less than 3 µm and not more than 3.5 µm, not less than 3.5 µm and not more than 4 µm, not less than 4 µm and not more than 4.5 µm, and not less than 4.5 µm and not more than 5 µm.

[0042] The second layer 9 is laminated on the first layer 8. The second layer 9 extends in a layered manner in the horizontal direction and forms the first main surface 3 and a part of each of the first to fourth side surfaces 5A to 5D. The second layer 9 is formed from an epitaxial layer (ie, a SiC epitaxial layer) that is crystallized with the first layer 8 as a starting point.

[0043] The second layer 9 has a lower end and an upper end. The lower end of the second layer 9 is a starting point of crystal growth, and the upper end of the second layer 9 is an end point of crystal growth. Since the second layer 9 is continuously crystal-grown from the first layer 8, the lower end of the second layer 9 is aligned with the upper end of the first layer 8. A boundary portion between the first layer 8 and the second layer 9 is not necessarily visible and can be indirectly evaluated and / or determined based on other configurations or elements. The second layer 9 has the deviation direction Doff and the deviation angle θoff that are substantially the same as the deviation direction Doff and the deviation angle θoff of the first layer 8.

[0044] The second layer 9 has a second axial channel CH2 aligned along the lamination direction. The second axial channel CH2 is formed from regions (channels) that have a comparatively large interatomic distance (atomic interval) in the SiC single crystal forming the second layer 9 and are surrounded by rows of atoms that form a crystal axis extending in the lamination direction (crystal growth direction).

[0045] That is, the second axial channel CH2 is composed of regions where the atomic rows are sparse, extending in the lamination direction and, in plan view, forming regions where the atomic rows (interatomic distance / atomic density) are sparse in the horizontal direction. The second axial channel CH2 is preferably formed from regions surrounded by atomic rows aligned along a low-index crystal axis among the crystal axes.

[0046] In this embodiment, the second axial channel CH2 is formed from the regions surrounded by atomic rows aligned along the c-axis of the SiC single crystal. That is, the second axial channel CH2 runs along the c-axis and has the deviation direction Doff and the deviation angle θoff. In other words, the second axial channel CH2 is inclined by the deviation angle θoff from the vertical axis in the deviation direction Doff.

[0047] The n-type impurity concentration of the second layer 9 is preferably lower than the n-type impurity concentration of the base layer 6. The second layer 9 may have an n-type impurity concentration of not less than 1 × 10 15 cm -3 and not more than 1 × 10 18 cm -3as a peak value. The n-type impurity concentration of the second layer 9 may be substantially constant in the thickness direction. Of course, the n-type impurity concentration of the second layer 9 may have a concentration gradient that gradually increases and / or gradually decreases in the lamination direction (crystal growth direction).

[0048] The n-type impurity concentration of the second layer 9 is preferably substantially equal to the n-type impurity concentration of the first layer 8. Of course, the n-type impurity concentration in the second layer 9 may be different from the n-type impurity concentration in the first layer 8. In this case, the n-type impurity concentration (the peak value) of the second layer 9 may be higher than the n-type impurity concentration (the peak value) of the first layer 8 or lower than the n-type impurity concentration (the peak value) of the first layer 8.

[0049] The second layer 9 has an n-type impurity concentration adjusted by at least one type of pentavalent element. For example, the n-type impurity concentration in the second layer 9 can be adjusted by at least one of the elements nitrogen, phosphorus, arsenic, antimony, and bismuth. The second layer 9 preferably comprises a pentavalent element other than phosphorus.

[0050] The n-type impurity concentration of the second layer 9 is preferably adjusted by at least nitrogen. When the second layer 9 contains two or more types of pentavalent elements, the second layer 9 preferably contains nitrogen and a pentavalent element other than nitrogen. In this case, the second layer 9 preferably contains one or both of arsenic and antimony as a pentavalent element other than phosphorus and nitrogen.

[0051] The second layer 9 has a second thickness T2. The second thickness T2 is preferably less than the base thickness TB. The second thickness T2 may be substantially equal to the first thickness T1 or different from the first thickness T1. The second thickness T2 may be greater than the first thickness T1 or less than the first thickness T1.

[0052] The second thickness T2 is preferably not less than 1 µm. The second thickness T2 is preferably not more than 5 µm. The second thickness T2 may have a value that falls within any of the following ranges: not less than 1 µm and not more than 1.5 µm, not less than 1.5 µm and not more than 2 µm, not less than 2 µm and not more than 2.5 µm, not less than 2.5 µm and not more than 3 µm, not less than 3 µm and not more than 3.5 µm, not less than 3.5 µm and not more than 4 µm, not less than 4 µm and not more than 4.5 µm, and not less than 4.5 µm and not more than 5 µm.

[0053] The SiC semiconductor device 1A includes an active region 10 formed in the chip 2. The active region 10 is arranged in an inner portion of the chip 2 at intervals from the peripheral edges (the first to fourth side surfaces 5A to 5D) of the chip 2 in plan view. The active region 10 has a polygonal shape (a quadrangular shape in this embodiment) with four sides parallel to the peripheral edges of the chip 2 in plan view. A flat area of ​​the active region 10 is preferably not less than 50% and not more than 90% of the flat area of ​​the first main surface 3.

[0054] The SiC semiconductor device 1A has an outer peripheral region 11 located outside the active region 10 at the chip 2. The outer peripheral region 11 is located in a region between the peripheral edges of the chip 2 and the active region 10 in plan view. The outer peripheral region 11 extends as a band along the active region 10 in plan view and is arranged in a polygonal ring shape (a quadrangular ring shape in this embodiment) around the active region 10.

[0055] As in Fig. 4A, Fig. 4B and Fig. As shown in Figure 5, the SiC semiconductor device 1A has the structural pattern PT according to a first configuration example formed in at least one of the first to fourth side surfaces 5A to 5D. The structural pattern PT facilitates identification or estimation of a configuration inside the device based on the external appearance of the chip 2, discrimination between proprietary products and third-party products, etc., and enhances the handling of the SiC semiconductor device 1A. The structural pattern PT can be identified, for example, by non-destructive testing (visual inspection) of the chip 2.

[0056] In this embodiment, the structural pattern PT has at least one first marking Mk1 (in this embodiment, a plurality of first markings Mk1) and at least one second marking Mk2 (in this embodiment, a plurality of second markings Mk2). The structural pattern PT does not necessarily have to have the first marking Mk1 and the second marking Mk2 simultaneously, but can also have only one of the two markings Mk1 and Mk2.

[0057] The plurality of first marks Mk1 are formed in at least one of the first to fourth side surfaces 5A to 5D. In this embodiment, the plurality of first marks Mk1 are formed in one or both (in this embodiment, both) of the first side surface 5A and the third side surface 5C extending in the first direction X. A configuration on the third side surface 5C is obtained by replacing the "first side surface 5A" with the "third side surface 5C" in the following description.

[0058] In this embodiment, each of the plurality of first marks Mk1 is formed from a p-type impurity region exposed on the first side surface 5A. Each of the plurality of first marks Mk1 is formed in a portion of the first side surface 5A formed from the laminated portion 7. Specifically, the plurality of first marks Mk1 are formed in a region on the side of the laminated portion 7 with respect to the base layer 6 and expose the base layer 6 from the first side surface 5A.

[0059] The plurality of first marks Mk1 are formed in the first side surface 5A so as to be unevenly distributed in a lower region of the laminated portion 7 on a lower side in a thickness direction with respect to an upper region of the laminated portion 7 on an upper side in the thickness direction. In a case where the upper region is defined as the first thickness region, the lower region is defined as the second thickness region. In a case where the lower region is defined as the first thickness region, the upper region is defined as the second thickness region. The upper region is a portion of each of the first to fourth side surfaces 5A to 5D formed by the second layer 9, and the lower region is a portion of each of the first to fourth side surfaces 5A to 5D formed by the first layer 8.

[0060] In this embodiment, the plurality of first marks Mk1 are arranged at intervals in the first direction X in the lower region and define a plurality of n-type first spaces Sp1, each formed from a part of the laminated portion 7. That is, each of the plurality of first marks Mk1 is formed in a portion of the first side surface 5A formed from the first layer 8, and each of the plurality of first spaces Sp1 is formed from a part of the first layer 8. The plurality of first marks Mk1 form pn junction portions with the plurality of first spaces Sp1.

[0061] The plurality of first markers Mk1 have electrical properties (impurities = a trivalent element) that differ from the electrical properties (impurities = a pentavalent element) of the plurality of first spaces Sp1. Therefore, the plurality of first markers Mk1 and the plurality of first spaces Sp1 are identified by measuring the electrical properties (impurities, concentrations, resistance values, etc.) of the plurality of first markers Mk1 and the plurality of first spaces Sp1. For example, the plurality of first markers Mk1 and the plurality of first spaces Sp1 can be identified using an electron microscope such as an SEM (scanning electron microscope) or a TEM (transmission electron microscope), etc., and / or an EBIC (electron beam induced current) analysis, etc.

[0062] The plurality of first marks Mk1 are formed in a region on the first layer 8 side (lower region) with respect to the second layer 9 (upper region). Therefore, the plurality of first marks Mk1 expose the portions in the first side surface 5A formed from the second layer 9 and facing the first main surface 3 via the second layer 9. The plurality of first marks Mk1 expose the entire area of ​​the portions of the first side surface 5A formed from the second layer 9. That is, the plurality of first marks Mk1 are not formed in the second layer 9. On the other hand, the plurality of first spaces Sp1 are connected to the portions of the first side surface 5A formed from the second layer 9.

[0063] The plurality of first marks Mk1 individually extend in a vertically long columnar shape along the lamination direction and form strip marks in the first side surface 5A, extending in the lamination direction together with the plurality of first gaps Sp1. The plurality of first marks Mk1 extend along the first axis channel CH1 in a surface layer portion of the first side surface 5A.

[0064] Each of the plurality of first marks Mk1 has a lower end portion on the lower end side of the first layer 8 and an upper end portion on the upper end side of the first layer 8. The lower end portion of each of the plurality of first marks Mk1 is located in a region on the lower end side of the first layer 8 with respect to a middle thickness region (thickness region-intermediate portion) of the first layer 8, and the upper end portion of each of the plurality of first marks Mk1 is located in a region on the upper end side of the first layer 8 with respect to the middle thickness region of the first layer 8. That is, the plurality of first marks Mk1 are each formed of a single impurity region having a thickness (a depth) that traverses an intermediate portion of the first layer 8 along the thickness direction.

[0065] The lower end portions of the plurality of first marks Mk1 may be formed at intervals from the lower end to the upper end side of the first layer 8 and may oppose the base layer 6 across a part (the lower end portion) of the first layer 8. That is, the plurality of first marks Mk1 may expose the entire area of ​​the portions of the first side surface 5A formed from the base layer 6. The lower end portions of the plurality of first marks Mk1 may substantially coincide with the lower end of the first layer 8 and be connected to the base layer 6.

[0066] Each of the lower end portions of the plurality of first marks Mk1 may have an extension portion that crosses a boundary portion between the base layer 6 and the first layer 8 and is disposed in the base layer 6. In this case, it is preferable that the extension portions of the plurality of first marks Mk1 are positioned in a surface layer portion on the upper end side of the base layer 6 and expose substantially the entire area of ​​the portions in the first side surface 5A formed by the base layer 6. Preferably, the extension portions of the plurality of first marks Mk1 are formed closer to the laminated portion 7 than a middle thickness portion of the base layer 6.

[0067] The upper end portion of the first mark Mk1 may be formed at a distance from the upper end (ie, the second layer 9) toward the lower end side of the first layer 8, and may oppose the upper end of the first layer 8 across a part (the upper end portion) of the first layer 8. The upper end portion of the first mark Mk1 may substantially coincide with the upper end of the first layer 8 and be connected to the second layer 9.

[0068] The plurality of second marks Mk2 are formed in at least one side surface of the first to fourth side surfaces 5A to 5D, which is different from the side surface in which the plurality of first marks Mk1 are formed. In this embodiment, the plurality of second marks Mk2 are formed in one or both (in this embodiment, both) of the second side surface 5B and the fourth side surface 5D, which extend in the second direction Y. Since a configuration on the fourth side surface 5D is identical to a configuration on the second side surface 5B, only the configuration on the second side surface 5B will be described below. The configuration on the fourth side surface 5D is arrived at by replacing the "second side surface 5B" with the "fourth side surface 5D" in the following description.

[0069] In this embodiment, each of the plurality of second marks Mk2 is formed from a p-type impurity region exposed on the second side surface 5B. Each of the plurality of second marks Mk2 is formed in a portion of the first side surface 5B formed from the laminated portion 7. Specifically, the plurality of second marks Mk2 are formed in a region on the laminated portion 7 side with respect to the base layer 6 and expose the base layer 6 from the second side surface 5B.

[0070] The plurality of second marks Mk2 are formed so as to be unevenly distributed in the upper region relative to the lower region of the second side surface 5B. In this embodiment, the plurality of second marks Mk2 are arranged at intervals in the second direction Y in the upper region and define a plurality of n-type second spaces Sp2, each formed from a part of the laminated portion 7. That is, each of the plurality of second marks Mk2 is formed in a portion of the second side surface 5B formed from the second layer 9, and each of the plurality of second spaces Sp2 is formed from a part of the second layer 9. The plurality of second marks Mk2 form pn junction portions with the plurality of second spaces Sp2.

[0071] The plurality of second marks Mk2 are formed in an arrangement direction different from the arrangement direction of the plurality of first marks Mk1, in a thickness range different from the thickness range of the plurality of first marks Mk1. The plurality of second spaces Sp2 are formed in an arrangement direction different from the arrangement direction of the plurality of first spaces Sp1, in a thickness range different from the thickness range of the plurality of first spaces Sp1.

[0072] The plurality of second markers Mk2 have electrical properties (impurities = a trivalent element) that differ from the electrical properties (impurities = a pentavalent element) of the plurality of second spaces Sp2. Therefore, the plurality of second markers Mk2 and the plurality of second spaces Sp2 are identified by measuring the electrical properties (impurities, concentrations, resistance values, etc.) of the plurality of second markers Mk2 and the plurality of second spaces Sp2. The plurality of second markers Mk2 and the plurality of second spaces Sp2 can be identified, for example, using an electron microscope such as an SEM or TEM, etc., and / or EBIC analysis, etc.

[0073] The plurality of second marks Mk2 are formed in a region on the second layer 9 side (upper region) with respect to the first layer 8 (lower region) and face the base layer 6 via the first layer 8. The plurality of second marks Mk2 expose portions of the second side surface 5B formed from the first layer 8. The plurality of second spaces Sp2 are respectively connected to the portions of the second side surface 5B formed from the first layer 8.

[0074] The plurality of second marks Mk2 individually extend in a vertically long columnar shape along the lamination direction, forming stripe marks in the second side surface 5B that extend in the lamination direction along with the plurality of second gaps Sp2. The plurality of second marks Mk2 extend along the second axis channel CH2 in a surface layer portion of the second side surface 5B.

[0075] Each of the plurality of second marks Mk2 has a lower end portion on the lower end side of the second layer 9 and an upper end portion on the upper end side of the second layer 9. The lower end portion of each of the plurality of second marks Mk2 is positioned in a region on the lower end side of the second layer 9 with respect to a middle thickness region of the second layer 9, and the upper end portion of each of the plurality of second marks Mk2 is positioned in a region on the upper end side of the second layer 9 with respect to the middle thickness region of the second layer 9. That is, the plurality of second marks Mk2 are each formed of a single impurity region having a thickness (a depth) that traverses an intermediate portion of the second layer 9 along the thickness direction.

[0076] The lower end portion of the second mark Mk2 may be formed at an interval from the lower end to the upper end side of the second layer 9 and may oppose the first layer 8 across a part (the lower end portion) of the second layer 9. That is, the plurality of second marks Mk2 may expose the entire area of ​​the portions of the second side surface 5B formed of the first layer 8. The lower end portion of the second mark Mk2 may substantially coincide with the lower end of the first layer 8 and be connected to the first layer 8.

[0077] Each of the lower end portions of the second marks Mk2 may have an extension portion that crosses the boundary portion between the first layer 8 and the second layer 9 and is disposed in the first layer 8. In this case, it is preferable that the extension portions of the plurality of second marks Mk2 are positioned in a surface layer portion on the upper end side of the first layer 8 and expose substantially the entire area of ​​the portions in the second side surface 5B formed by the first layer 8.

[0078] The upper end portion of the second mark Mk2 may be formed at an interval from the upper end (ie, the first main surface 3) toward the lower end side of the second layer 9, and may be opposed to the upper end of the second layer 9 via a part (the upper end portion) of the second layer 9. The upper end portion of the second mark Mk2 may be exposed from the upper end (ie, the first main surface 3) of the second layer 9.

[0079] As in Fig. As shown in Figure 6A, the SiC semiconductor device 1A may include the pattern PT according to a second configuration example formed in at least one of the first to fourth side surfaces 5A to 5D. The pattern PT according to the second configuration example includes a first differential mark Md1 in addition to the configuration according to the first configuration example.

[0080] The first differential mark Md1 is formed in a different thickness range than the first marks Mk1 and with a different layout than the first marks Mk1 in the first side surface 5A or the third side surface 5C or in both. Fig. 6A shows an example in which the first differential mark Md1 is formed in the first side surface 5A. A configuration on the third side surface 5C is obtained by replacing the "first side surface 5A" with the "third side surface 5C" in the following description.

[0081] In this embodiment, the first differential mark Md1 is formed from the p-type impurity region exposed on the first side surface 5A. The first differential mark Md1 is formed in a portion of the first side surface 5A formed from the laminated portion 7. Specifically, the first differential mark Md1 is formed in a region on the side of the laminated portion 7 with respect to the base layer 6, exposing the base layer 6 from the first side surface 5A.

[0082] More specifically, the first differential mark Md1 is formed in the upper region relative to the lower region and overlaps at least one of the first marks Mk1 in the thickness direction. In this embodiment, the first differential mark Md1 extends as a band in the first direction X in the upper region and overlaps the plurality of first marks Mk1 in the thickness direction.

[0083] In this embodiment, the first differential mark Md1 extends from a corner portion on one side of the first side surface 5A to a corner portion on the other side of the first side surface 5A in the first direction X, and is exposed from the corner portion on one side and the corner portion on the other side of the first side surface 5A. That is, the first differential mark Md1 overlaps all the first marks Mk1 in the thickness direction.

[0084] The first differential mark Md1 has a portion exposed from the corner portion of the second side surface 5B and a corner portion of the fourth side surface 5D. The first differential mark Md1 is formed on the corner portion of the second side surface 5B (the fourth side surface 5D) at an interval in the second direction Y from the outermost second mark Mk2 and opposes the outermost second mark Mk2 in the second direction Y. The first differential mark Md1 is formed in a portion of the first side surface 5A formed of the second layer 9, and defines the plurality of first spaces Sp1 together with the plurality of first marks Mk1.

[0085] The first differential mark Md1 has electrical properties (impurities = a trivalent element) that differ from the electrical properties (impurities = a pentavalent element) of the plurality of first spaces Sp1. Therefore, the plurality of first differential marks Md1 and the plurality of first spaces Sp1 are identified by measuring the electrical properties (impurities, concentrations, resistance values, etc.) of the first differential mark Md1 and the plurality of first spaces Sp1. For example, the first differential mark Md1 and the plurality of first spaces Sp1 can be identified using an electron microscope such as an SEM or TEM, etc., and / or EBIC analysis, etc.

[0086] The first differential mark Md1 has a lower end portion on the lower end side of the second layer 9 and an upper end portion on the upper end side of the second layer 9. The lower end portion of the first differential mark Md1 is located in a region on the lower end side of the second layer 9 with respect to the middle thickness region of the second layer 9, and the upper end portion of the first differential mark Md1 is located in a region on the upper end side of the second layer 9 with respect to the middle thickness region of the second layer 9. That is, the first differential mark Md1 is formed of a single impurity region having a thickness (depth) that crosses the intermediate portion of the second layer 9 in the thickness direction.

[0087] The lower end portion of the first differential mark Md1 may be formed at an interval from the plurality of first marks Mk1 to the upper end side (the first main surface 3) of the second layer 9, and may oppose the plurality of first marks Mk1 (the plurality of first spaces Sp1) over a part (the lower end portion) of the second layer 9. The lower end portion of the first differential mark Md1 may substantially coincide with the lower end of the first layer 8.

[0088] In this case, the lower end portion of the first differential mark Md1 may be formed at a distance from the upper end portions of the plurality of first marks Mk1 toward the upper end side of the second layer 9, and may oppose the plurality of first marks Mk1 across a part (the lower end portion) of the second layer 9. Of course, the lower end portion of the plurality of first differential marks Md1 may be connected to the upper end portions of the plurality of first marks Mk1 (the plurality of first spaces Sp1).

[0089] The lower end portion of the first differential mark Md1 may have an extension portion that crosses the boundary portion between the first layer 8 and the second layer 9 and is positioned in the first layer 8. In this case, the lower end portion (the extension portion) of the first differential mark Md1 may be connected to the plurality of first marks Mk1 in the first layer 8. Of course, the lower end portion (the extension portion) of the first differential mark Md1 may be formed at an interval from the plurality of first marks Mk1 to the upper end side of the second layer 9.

[0090] The upper end portion of the first differential mark Md1 may be formed at a distance from the upper end (ie, the first main surface 3) toward the lower end side of the second layer 9, and may oppose the upper end of the second layer 9 via a part (the upper end portion) of the second layer 9. The upper end portion of the first differential mark Md1 may be exposed from the upper end (ie, the first main surface 3) of the second layer 9.

[0091] As in Fig. As shown in Figure 6B, the SiC semiconductor device 1A may include the structural pattern PT according to a third configuration example formed in at least one of the first to fourth side surfaces 5A to 5D. The structural pattern PT according to the third configuration example includes a second differential mark Md2 in addition to the configuration according to the first configuration example.

[0092] The second differential mark Md2 is formed in a different thickness range than the second mark Mk2 and with a different layout than the second mark Mk2 in the second side surface 5B or the fourth side surface 5D. Fig. 6B shows an example in which the second differential mark Md2 is formed in the second side surface 5B. The configuration on the fourth side surface 5D is obtained by replacing the "second side surface 5B" with the "fourth side surface 5D" in the following description.

[0093] In this embodiment, the second differential mark Md2 is formed from the p-type impurity region exposed on the second side surface 5B. The second differential mark Md2 is formed in a portion of the second side surface 5B formed from the laminated portion 7. Specifically, the second differential mark Md2 is formed in a region on the side of the laminated portion 7 with respect to the base layer 6, exposing the base layer 6 from the second side surface 5B.

[0094] More specifically, the second differential mark Md2 is formed in the lower region relative to the upper region and overlaps at least one of the second marks Mk2 in the thickness direction. In this embodiment, the second differential mark Md2 extends as a band in the second direction Y in the lower region and overlaps the plurality of second marks Mk2 in the thickness direction.

[0095] In this embodiment, the second differential mark Md2 extends from a corner portion on one side of the second side surface 5B to a corner portion on the other side of the second side surface 5B in the second direction Y, and is exposed from the corner portion on one side and the corner portion on the other side of the second side surface 5B. That is, the second differential mark Md2 overlaps all the second marks Mk2 in the thickness direction.

[0096] The second differential mark Md2 has a portion exposed from the corner portion of the first side surface 5A and a corner portion of the third side surface 5C. The second differential mark Md2 is formed on the corner portion of the first side surface 5A (the third side surface 5C) at an interval in the first direction X from the outermost first mark Mk1 and opposes the outermost first mark Mk1 in the first direction X. The second differential mark Md2 is formed in a portion of the second side surface 5B formed of the first layer 8, and defines the plurality of second spaces Sp2 together with the plurality of second marks Mk2.

[0097] The second differential mark Md2 has electrical properties (impurities = a trivalent element) that differ from the electrical properties (impurities = a pentavalent element) of the plurality of second spaces Sp2. Therefore, the plurality of second differential marks Md2 and the plurality of second spaces Sp2 are identified by measuring the electrical properties (impurities, concentrations, resistance values, etc.) of the second differential mark Md2 and the plurality of second spaces Sp2. The second differential mark Md2 and the plurality of second spaces Sp2 can be identified, for example, using an electron microscope such as an SEM or a TEM, etc., and / or EBIC analysis, etc.

[0098] The second differential mark Md2 has a lower end portion on the lower end side of the first layer 8 and an upper end portion on the upper end side of the first layer 8. The lower end portion of the second differential mark Md2 is located in a region on the lower end side of the first layer 8 with respect to the middle thickness range of the first layer 8, and the upper end portion of the second differential mark Md2 is located in a region on the upper end side of the first layer 8 with respect to the middle thickness range of the first layer 8. That is, the second differential mark Md2 is formed of a single impurity region with a thickness (depth) that traverses the intermediate portion of the first layer 8 along the first axis channel CH1.

[0099] The lower end portion of the second differential mark Md2 may be formed at a distance from the lower end (i.e., the base layer 6) of the first layer 8 to the upper end side (the second layer 9) of the first layer 8, and may oppose the base layer 6 via a part (the lower end portion) of the first layer 8. The lower end portion of the second differential mark Md2 may substantially coincide with the lower end of the first layer 8 and be connected to the base layer 6. The lower end portion of the second differential mark Md2 may have an extension portion that crosses the boundary portion between the base layer 6 and the first layer 8 and is disposed in the base layer 6.

[0100] The upper end portion of the second differential mark Md2 may be formed at a distance from the upper end (ie, the second layer 9) to the lower end side of the first layer 8, and may oppose the plurality of second marks Mk2 via a part (the upper end portion) of the first layer 8. The upper end portion of the second differential mark Md2 may be exposed from the upper end (ie, the first main surface 3) of the first layer 8.

[0101] In this case, the upper end portion of the second differential mark Md2 may be connected to the lower end portions of the plurality of second marks Mk2. Of course, the upper end portion of the second differential mark Md2 may be formed at an interval from the lower end portions of the plurality of second marks Mk2 to the lower end side of the first layer 8, and may oppose the plurality of second marks Mk2 across a part (the lower end portion) of the first layer 8.

[0102] As in Fig. As shown in FIG. 6C, the SiC semiconductor device 1A may include the structural pattern PT according to a fourth configuration example formed in at least one of the first to fourth side surfaces 5A to 5D. The structural pattern PT according to the fourth configuration example includes, in addition to the configuration according to the first configuration example, the first differential mark Md1 according to the second configuration example and the second differential mark Md2 according to the third configuration example. The second differential mark Md2 extends in an extension direction different from the extension direction of the first differential mark Md1, in a thickness range different from the thickness range of the first differential mark Md1.

[0103] As in Fig. 6D, the SiC semiconductor device 1A may include the pattern PT according to a fifth configuration example formed in at least one of the first to fourth side surfaces 5A to 5D. The pattern PT according to the fifth configuration example has a configuration in which a positional relationship between the plurality of first marks Mk1 and the plurality of second marks Mk2 is reversed.

[0104] Specifically, the plurality of first marks Mk1 are arranged at intervals in the second direction Y in the lower region of the second side surface 5B and define the plurality of n-type first spaces Sp1, each formed from a part of the laminated portion 7. Each of the plurality of first marks Mk1 is formed in a portion of the second side surface 5B formed from the first layer 8, and each of the plurality of first spaces Sp1 is formed from a part of the first layer 8. Furthermore, the configuration of the first marks Mk1 (the first spaces Sp1) according to the fifth configuration example is identical to the configuration of the first marks Mk1 (the first spaces Sp1) according to the first configuration example, except that the first marks Mk1 (the first spaces Sp1) are formed in the second side surface 5B.

[0105] On the other hand, the plurality of second marks Mk2 are arranged at intervals in the first direction X in the upper region of the first side surface 5A and define the plurality of p-type second spaces Sp2, each formed from a part of the laminated portion 7. Each of the plurality of second marks Mk2 is formed in a portion of the first side surface 5A formed from the second layer 9, and each of the plurality of second spaces Sp2 is formed from a part of the second layer 9. Moreover, the configuration of the second marks Mk2 (the second spaces Sp2) according to the fifth configuration example is identical to the configuration of the second marks Mk2 (the second spaces Sp2) according to the first configuration example, except that the second marks Mk2 (the second spaces Sp2) are formed in the first side surface 5A.

[0106] Of course, the above-described configurations of the structural patterns PT according to the second to fourth configuration examples can also be applied to the structural pattern PT according to the fifth configuration example. In this case, the above-described first differential mark Md1 is formed in the upper region of the second side surface 5B. The above-described second differential mark Md2 is also formed in the lower region of the first side surface 5B.

[0107] As in Fig.As shown in FIGS. 2 to 7, the SiC semiconductor device 1A includes the p-type pillar region 12 formed at least in the laminated portion 7 in the active region 10. The pillar region 12 may be referred to as a "pillar layer," "pillar layer (region)," "p-type layer (region)," "p-type region," etc. The pillar region 12 is formed in a three-dimensional lattice shape in the laminated portion 7 and defines a three-dimensional lattice-shaped n-type drift region 13 formed from a part of the laminated portion 7.

[0108] The pillar region 12 is formed in at least one semiconductor layer among the plurality of semiconductor layers constituting the laminated portion 7, and forms a super junction structure SJ with the drift region 13 in the laminated portion 7. In this embodiment, the pillar region 12 has a laminated structure including a plurality of first p-type regions 14 and a plurality of second p-type regions 15.

[0109] The plurality of first regions 14 are arranged at intervals in the horizontal direction in the first layer 8 and define a plurality of first n-type drift regions 16, each formed from a portion of the first layer 8. The plurality of first regions 14, together with the plurality of first drift regions 16, form a plurality of first pn junction regions having charge balance.

[0110] That is, the plurality of first regions 14 form a first super junction structure SJ1 with the plurality of first drift regions 16. The charge-balanced state means a state in which, with respect to the plurality of first regions 14 adjacent to each other, a depletion layer extending from one first pn junction part and a depletion layer extending from the other first pn junction part are connected in the plurality of first drift regions 16.

[0111] The plurality of first regions 14 are arranged at intervals in a first arrangement direction Da1 in the first layer 8 and are each formed as a band extending in a first extension direction De1. The first extension direction De1 is a direction that intersects or is orthogonal to the first arrangement direction Da1. That is, the plurality of first regions 14 are formed as stripes extending in the first extension direction De1, and the plurality of first drift regions 16 are formed as stripes extending in the first extension direction De1.

[0112] In this embodiment, the plurality of first regions 14 are guided from the active region 10 to the outer peripheral region 11 (see Fig. 3A). That is, the plurality of first regions 14 extend from a portion of the first layer 8 located in the active region 10 to a portion of the first layer 8 located in the outer peripheral region 11. The plurality of first regions 14 are also arranged at intervals in the first arrangement direction Da1 in the outer peripheral region 11 and are each formed as a band extending in the first extension direction De1.

[0113] Furthermore, the plurality of first regions 14 extend from the outer peripheral region 11 toward one or both (in this embodiment, both) of the first side surface 5A and the third side surface 5C, and each has portions exposed from one or both (in this embodiment, both) of the first side surface 5A and the third side surface 5C.

[0114] The portions of the plurality of first regions 14 exposed from the first side surface 5A form the plurality of first marks Mk1 in the first side surface 5A, and the portions of the plurality of first regions 14 exposed from the third side surface 5C form the plurality of first marks Mk1 in the third side surface 5C. That is, the plurality of first regions 14 have one or both of the plurality of first marks Mk1 as exposed portions exposed from the first side surface 5A and the plurality of first marks Mk1 as exposed portions exposed from the third side surface 5C.

[0115] In other words, each of the plurality of first marks Mk1 is formed using a part (an exposed portion) of each of the plurality of first regions 14. The layout (exposed locations or the arrangement direction) of the plurality of first marks Mk1 with respect to the first side surface 5A (the third side surface 5C) is adjusted accordingly by the layout (the first arrangement direction Da1 or the first extension direction De1) of the plurality of first regions 14.

[0116] The plurality of first marks Mk1 are not necessarily formed continuously from main body portions of the plurality of first regions 14 and may be formed as separate portions separated from the main body portions of the plurality of first regions 14. In this case, the plurality of first marks Mk1 are preferably separated from the main body portions of the plurality of first regions 14 in the outer peripheral region 11. The description for the first regions 14 also applies to the first marks Mk1 (portions of the first regions 14 exposed from the first side surface 5A / the third side surface 5C).

[0117] The plurality of first regions 14 are formed from channeling regions (first channeling regions) extending, in a cross-sectional view, along the first axial channel CH1 in the first layer 8. That is, the first region 14 is an impurity region introduced parallel or substantially parallel to the regions (the first axial channel CH1) surrounded by atomic rows aligned along the low-index crystal axis in the first layer 8, and extending inclined with respect to the first main surface 3.

[0118] Therefore, each of the plurality of first regions 14 has the deviation direction Doff and the deviation angle θoff that substantially coincide with the deviation direction Doff and the deviation angle θoff of the first axis channel CH1. In other words, each of the plurality of first regions 14 is inclined by the deviation angle θoff from the vertical axis in the direction of the deviation direction Doff.

[0119] Each of the plurality of first regions 14 has a first lower end portion 14a at a lower end side of the first layer 8 and a first upper end portion 14b at an upper end side of the first layer 8. The first lower end portion 14a is located in a region at the lower end side of the first layer 8 with respect to a middle thickness range of the first layer 8, and the first upper end portion 14b is located in a region at the upper end side of the first layer 8 with respect to the middle thickness range of the first layer 8. That is, the plurality of first regions 14 are each composed of a single impurity region having a thickness (a depth) that traverses an intermediate portion of the first layer 8 along the first axis channel CH1.

[0120] The first lower end portion 14a may be formed at an interval from the lower end to the upper end side of the first layer 8 and may oppose the base layer 6 via a part (a lower end portion) of the first layer 8. The first lower end portion 14a may substantially coincide with the lower end of the first layer 8 and be connected to the base layer 6.

[0121] A distance between the lower end of the first layer 8 and the first lower end portion 14a may be not less than 0 µm and not more than 2 µm. The distance between the lower end of the first layer 8 and the first lower end portion 14a may have a value that falls within one of the following ranges: not less than 0 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 1 µm, not less than 1 µm and not more than 1.5 µm, and not less than 1.5 µm and not more than 2 µm.

[0122] The first lower end portion 14a may have an extension portion that crosses the boundary portion between the base layer 6 and the first layer 8 and is disposed in the base layer 6. In this case, the thickness of the extension portion of the first lower end portion 14a may be more than 0 µm and not more than 2 µm based on the upper end of the base layer 6. The thickness of the extension portion of the first lower end portion 14a may have a value falling within any one of the following ranges: more than 0 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 1 µm, not less than 1 µm and not more than 1.5 µm, and not less than 1.5 µm and not more than 2 µm.

[0123] The first upper end portion 14b may be formed at an interval from the upper end (ie, the second layer 9) toward the lower end side of the first layer 8, and may oppose the upper end of the first layer 8 via a part (an upper end portion) of the first layer 8. The first upper end portion 14b may substantially coincide with the upper end of the first layer 8 and be connected to the second layer 9.

[0124] A distance between the upper end of the first layer 8 and the first upper end portion 14b may be not less than 0 µm and not more than 1 µm. The distance between the upper end of the first layer 8 and the first upper end portion 14b may have a value that falls within one of the following ranges: not less than 0 µm and not more than 0.25 µm, not less than 0.25 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 0.75 µm, and not less than 0.75 µm and not more than 1 µm.

[0125] The plurality of first regions 14 may have a p-type impurity concentration of not less than 1 × 10 15 cm -3 and not more than 1 × 10 18 cm -3as a peak value. The p-type impurity concentration of the first region 14 is preferably adjusted by at least one type of trivalent element. The p-type impurity concentration of the first region 14 is particularly preferably adjusted by a trivalent element belonging to the heavy elements heavier than carbon. That is, the first region 14 preferably includes a trivalent element other than boron (at least one of aluminum, gallium, and indium). In this embodiment, the p-type impurity concentration of the first region 14 is adjusted by aluminum.

[0126] Each of the plurality of first regions 14 has a first width W1. The first width W1 is a width along the first arrangement direction Da1 of the first regions 14. The first width W1 is preferably smaller than the first thickness T1 of the first layer 8. Of course, the first width W1 may also be no smaller than the first thickness T1. The first width W1 is preferably smaller than the second thickness T2 of the second layer 9. Of course, the first width W1 may also be no smaller than the second thickness T2.

[0127] The first width W1 may not be less than 0.1 µm and not more than 5 µm. The first width W1 may have a value that falls within one of the following ranges: not less than 0.1 µm and not more than 0.25 µm, not less than 0.25 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 0.75 µm, not less than 0.75 µm and not more than 1 µm, not less than 1 µm and not more than 1.5 µm, not less than 1.5 µm and not more than 2 µm, not less than 2 µm and not more than 2.5 µm, not less than 2.5 µm and not more than 3 µm, not less than 3 µm and not more than 3.5 µm, not less than 3.5 µm and not more than 4 µm, not less than 4 µm and not more than 4.5 µm, and not less than 4.5 µm and not more than 5 µm. The first width W1 is preferably not less than 0.5 µm and not more than 1.5 µm.

[0128] Each of the plurality of first regions 14 has a first region thickness TR1 (a first region depth). The first region thickness TR1 may be less than the first thickness T1 of the first layer 8. The first region thickness TR1 may be greater than the first thickness T1. The first region thickness TR1 may be substantially equal to the first thickness T1. The first region thickness TR1 may be less than the second thickness T2 of the second layer 9. The first region thickness TR1 may be greater than the second thickness T2. The first region thickness TR1 may be substantially equal to the second thickness T2.

[0129] The first region thickness TR1 is preferably not less than 1 µm. The first region thickness TR1 is preferably not more than 5 µm. The first region thickness TR1 may have a value that falls within any of the following ranges: not less than 1 µm and not more than 1.5 µm, not less than 1.5 µm and not more than 2 µm, not less than 2 µm and not more than 2.5 µm, not less than 2.5 µm and not more than 3 µm, not less than 3 µm and not more than 3.5 µm, not less than 3.5 µm and not more than 4 µm, not less than 4 µm and not more than 4.5 µm, and not less than 4.5 µm and not more than 5 µm.

[0130] Preferably, the first width W1 is smaller than the first thickness T1 of the first layer 8, and the region thickness TR1 is greater than the first width W1. That is, each of the plurality of first regions 14 preferably has a first aspect ratio TR1 / W1 and extends in a vertically long columnar shape along the first axial channel CH1. The first aspect ratio TR1 / W1 is the ratio of the region thickness TR1 to the first width W1. In this case, the first region thickness TR1 is particularly preferably greater than the first thickness T1. For example, the first aspect ratio TR1 / W1 may be greater than 1 and at most 100.

[0131] The plurality of first regions 14 are formed at intervals of a first pitch P1 (a first pitch / a first pitch) in the first arrangement direction Da1. The first pitch P1 is preferably smaller than the first thickness T1 of the first layer 8. Of course, the first pitch P1 may not be smaller than the first thickness T1. The first pitch P1 is preferably smaller than the second pitch T2 of the second layer 9. Of course, the first pitch P1 may not be smaller than the second thickness T2.

[0132] The first pitch P1 cannot be less than 0.1 µm and not more than 5 µm. The first pitch P1 can have a value that falls within one of the following ranges: not less than 0.1 µm and not more than 0.25 µm, not less than 0.25 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 0.75 µm, not less than 0.75 µm and not more than 1 µm, not less than 1 µm and not more than 1.5 µm, not less than 1.5 µm and not more than 2 µm, not less than 2 µm and not more than 2.5 µm, not less than 2.5 µm and not more than 3 µm, not less than 3 µm and not more than 3.5 µm, not less than 3.5 µm and not more than 4 µm, not less than 4 µm and not more than 4.5 µm, and not less than 4.5 µm and not more than 5 µm. The first pitch P1 is preferably not less than 0.5 µm and not more than 1.5 µm.

[0133] The plurality of second regions 15 are formed at intervals in the horizontal direction in the second layer 9 and define a plurality of second n-type drift regions 17, each formed from a portion of the second layer 9. The plurality of second regions 15, together with the plurality of second drift regions 17, form a plurality of second pn junction regions having charge balance.

[0134] That is, the plurality of second regions 15 form a second super junction structure SJ2 with the second layer 9. The charge-balanced state means a state in which, with respect to the plurality of second regions 15 adjacent to each other, a depletion layer extending from one second pn junction portion and a depletion layer extending from the other second pn junction portion are connected in the plurality of second drift regions 17.

[0135] The plurality of second regions 15 are formed in the second layer 9 so as to overlap the plurality of first regions 14 in the lamination direction. Specifically, the plurality of second regions 15 are arranged at intervals in a second arrangement direction Da2 different from the first arrangement direction Da1 in the second layer 9, and are each formed as a band extending in a second extension direction De2 different from the first extension direction De1.

[0136] The second arrangement direction Da2 is a direction that intersects the first arrangement direction Da1, and the second extension direction De2 is a direction that intersects the first extension direction De1. The second extension direction De2 is a direction that intersects or is orthogonal to the second arrangement direction Da2. That is, the plurality of second regions 15 are formed as stripes extending in the second extension direction De2, and the plurality of second drift regions 17 are formed as stripes extending in the second extension direction De2.

[0137] The plurality of second drift regions 15 intersect the plurality of first drift regions 14 in plan view. That is, the plurality of second drift regions 17 are connected in a lattice shape to the plurality of first drift regions 16 at the boundary between the first layer 8 and the second layer 9, and together with the plurality of first drift regions 16, they form the single drift region 13 in a three-dimensional lattice shape. The plurality of second drift regions 17, together with the plurality of first drift regions 16, form three-dimensional lattice-shaped current paths.

[0138] In this embodiment, the plurality of second regions 15 are guided from the active region 10 to the outer peripheral region 11 (see Fig. 3B). That is, the plurality of second regions 15 extend from a portion of the second layer 9 located in the active region 10 to a portion of the second layer 9 located in the outer peripheral region 11. The plurality of second regions 15 are also arranged at intervals in the second arrangement direction Da2 in the outer peripheral region 11 and are each formed as a band extending in the second extension direction De2. That is, the plurality of second regions 15 also intersect the plurality of first regions 14 in the outer peripheral region 11.

[0139] Furthermore, the plurality of second regions 15 extend from the outer peripheral region 11 toward one or both (in this embodiment, both) of the second side surface 5B and the fourth side surface 5D, and each has portions exposed from one or both (in this embodiment, both) of the second side surface 5B and the fourth side surface 5D.

[0140] The portions of the plurality of second regions 15 exposed from the second side surface 5B form the plurality of second marks Mk2 in the second side surface 5B, and the portions of the plurality of second regions 15 exposed from the fourth side surface 5D form the plurality of second marks Mk2 in the fourth side surface 5D. That is, the plurality of second regions 15 include one or both of the plurality of second marks Mk2 as exposed portions exposed from the second side surface 5B and the plurality of second marks Mk2 as exposed portions exposed from the fourth side surface 5D.

[0141] In other words, each of the plurality of second marks Mk2 is formed using a part (an exposed portion) of each of the plurality of second regions 15. The layout (exposed locations or the arrangement direction) of the plurality of second marks Mk2 with respect to the second side surface 5B (the fourth side surface 5D) is adjusted accordingly by the layout (the second arrangement direction Da2 or the second extension direction De2) of the plurality of second regions 15.

[0142] The plurality of second marks Mk2 are not necessarily formed continuously from main body portions of the plurality of second regions 15 and may be formed as separate portions separated from the main body portions of the plurality of second regions 15. In this case, the plurality of second marks Mk2 are preferably separated from the main body portions of the plurality of second regions 15 in the outer peripheral region 11. The description for the second regions 15 also applies to the second marks Mk2 (portions of the second regions 15 exposed from the second side surface 5B / the fourth side surface 5D).

[0143] The plurality of second regions 15 are formed from channeling regions (second channeling regions) extending, in cross-sectional view, along the second axis channel CH2 in the second layer 9. That is, the second region 15 is an impurity region introduced parallel or substantially parallel to the regions (the second axis channel CH2) surrounded by atomic rows aligned along the low-index crystal axis in the second layer 9, and extending inclined with respect to the first main surface 3.

[0144] Therefore, each of the plurality of second regions 15 has the deviation direction Doff and the deviation angle θoff that substantially coincide with the deviation direction Doff and the deviation angle θoff of the second axis channel CH2. In other words, each of the plurality of second regions 15 is inclined by the deviation angle θoff from the vertical axis in the direction of the deviation direction Doff.

[0145] Each of the plurality of second regions 15 has a second lower end portion 15a at a lower end side of the second layer 9 and a second upper end portion 15b at an upper end side of the second layer 9. The second lower end portion 15a is located in a region at the lower end side of the second layer 9 with respect to a middle thickness range of the second layer 9, and the second upper end portion 15b is located in a region at the upper end side of the second layer 9 with respect to the middle thickness range of the second layer 9. That is, the plurality of second regions 15 are each formed of a single impurity region having a thickness (a depth) that traverses an intermediate portion of the second layer 9 along the second axis channel CH2.

[0146] The second lower end portion 15a may be formed at an interval from the lower end toward the upper end side of the second layer 9 and may oppose the first layer 8 (the plurality of first regions 14) across a part (a lower end portion) of the second layer 9. The second lower end portion 15a may substantially coincide with the lower end of the second layer 9 and be connected to the first layer 8.

[0147] A distance between the lower end of the second layer 9 and the second lower end portion 15a may be not less than 0 µm and not more than 2 µm. The distance between the lower end of the second layer 9 and the second lower end portion 15a may have a value that falls within any of the following ranges: not less than 0 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 1 µm, not less than 1 µm and not more than 1.5 µm, and not less than 1.5 µm and not more than 2 µm.

[0148] The second lower end portion 15a may have an extension portion that crosses the boundary portion between the first layer 8 and the second layer 9 and is disposed in the first layer 8. In this case, the thickness of the extension portion of the second lower end portion 15a with respect to the upper end of the first layer 8 may be more than 0 µm and not more than 2 µm. The thickness of the extension portion of the second lower end portion 15a may have a value that falls within any one of the following ranges: more than 0 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 1 µm, not less than 1 µm and not more than 1.5 µm, and not less than 1.5 µm and not more than 2 µm.

[0149] The second upper end portion 15b may be formed at an interval from the upper end (i.e., the first main surface 3) toward the lower end side of the second layer 9, and may oppose the upper end of the second layer 9 across a part (an upper end portion) of the second layer 9. In this case, a space between the first main surface 3 and the second upper end portion 15b in the second layer 9 may be used as a region for forming a device pattern (another impurity region, etc.). Of course, the second upper end portion 15b may be exposed from the upper end (i.e., the first main surface 3) of the second layer 9.

[0150] A distance between the upper end of the second layer 9 and the second upper end portion 15b may be not less than 0 µm and not more than 1 µm. The distance between the upper end of the second layer 9 and the second upper end portion 15b may have a value that falls within any of the following ranges: not less than 0 µm and not more than 0.25 µm, not less than 0.25 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 0.75 µm, and not less than 0.75 µm and not more than 1 µm.

[0151] The plurality of second regions 15 may have a p-type impurity concentration of not less than 1 × 10 15 cm -3 and not more than 1 × 10 18 cm -3as a peak value. The p-type impurity concentration (a peak value) of the second region 15 may not be less than the p-type impurity concentration (the peak value) of the first region 14. The p-type impurity concentration (the peak value) of the second region 15 may be less than the p-type impurity concentration (the peak value) of the first region 14. The p-type impurity concentration (the peak value) of the second region 15 may be substantially equal to the p-type impurity concentration (the peak value) of the first region 14.

[0152] The p-type impurity concentration of the second region 15 is preferably adjusted by at least one type of trivalent element. The p-type impurity concentration of the second region 15 is particularly preferably adjusted by a trivalent element belonging to the heavy elements heavier than carbon. That is, the second region 15 preferably comprises a trivalent element other than boron (at least one of aluminum, gallium, and indium). In this embodiment, the p-type impurity concentration of the second region 15 is adjusted by aluminum.

[0153] Each of the plurality of second regions 15 has a second width W2. The second width W2 is a width along the second arrangement direction Da2 of the second regions 15. The second width W2 is preferably smaller than the second thickness T2 of the second layer 9. Of course, the second width W2 may also be no smaller than the second thickness T2.

[0154] The second width W2 is preferably smaller than the first thickness T1 of the first layer 8. Of course, the second width W2 may also be not smaller than the first thickness T1. The second width W2 is preferably substantially equal to the first width W1 of the first region 14. Of course, the second width W2 may not be smaller than the first width W1, or it may be smaller than the first width W1.

[0155] The second width W2 may not be less than 0.1 µm and not more than 5 µm. The second width W2 may have a value that falls within one of the following ranges: not less than 0.1 µm and not more than 0.25 µm, not less than 0.25 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 0.75 µm, not less than 0.75 µm and not more than 1 µm, not less than 1 µm and not more than 1.5 µm, not less than 1.5 µm and not more than 2 µm, not less than 2 µm and not more than 2.5 µm, not less than 2.5 µm and not more than 3 µm, not less than 3 µm and not more than 3.5 µm, not less than 3.5 µm and not more than 4 µm, not less than 4 µm and not more than 4.5 µm, and not less than 4.5 µm and not more than 5 µm. The second width W2 is preferably not less than 0.5 µm and not more than 1.5 µm.

[0156] Each of the plurality of second regions 15 has a second region thickness TR2 (a region depth). The second region thickness TR2 may be less than the second thickness T2 of the second layer 9. The second region thickness TR2 may be greater than the second thickness T2. The second region thickness TR2 may be substantially equal to the second thickness T2.

[0157] The second region thickness TR2 may be less than the first thickness T1 of the first layer 8. The second region thickness TR2 may be greater than the thickness of the first region T1. The second region thickness TR2 may be substantially equal to the first thickness T1. The second region thickness TR2 may be less than the first region thickness TR1 of the first region 14. The second region thickness TR2 may be greater than the first region thickness TR1. The second region thickness TR2 may be substantially equal to the first region thickness TR1.

[0158] The second region thickness TR2 is preferably not less than 1 µm. The second region thickness TR2 is preferably not more than 5 µm. The second region thickness TR2 may have a value that falls within any one of the following ranges: not less than 1 µm and not more than 1.5 µm, not less than 1.5 µm and not more than 2 µm, not less than 2 µm and not more than 2.5 µm, not less than 2.5 µm and not more than 3 µm, not less than 3 µm and not more than 3.5 µm, not less than 3.5 µm and not more than 4 µm, not less than 4 µm and not more than 4.5 µm, and not less than 4.5 µm and not more than 5 µm.

[0159] Preferably, the second width W2 is smaller than the second thickness T2 of the second layer 9, and the second region thickness TR2 is greater than the second width W2. That is, each of the plurality of second regions 15 preferably has a second aspect ratio TR2 / W2 and extends in a vertically long columnar shape along the second axial channel CH2. The second aspect ratio TR2 / W2 is the ratio of the second region thickness TR2 to the second width W2. In this case, the second region thickness TR2 is particularly preferably greater than the second thickness T2. For example, the second aspect ratio TR2 / W2 may be greater than 1 and at most 100.

[0160] The plurality of second regions 15 are formed at intervals of a second pitch P2 (a second pitch / a second pitch) in the second arrangement direction Da2. The second pitch P2 is preferably smaller than the second thickness T2 of the second layer 9. Of course, the second pitch P2 cannot be smaller than the second thickness T2 of the second layer 9. The second pitch P2 is preferably smaller than the first thickness T1 of the first layer 8. Of course, the second pitch P2 cannot be smaller than the first thickness T1.

[0161] The second pitch P2 may be substantially equal to the first pitch P1 or different from the first pitch P1. The second pitch P2 may be greater than the first pitch P1 or less than the first pitch P1.

[0162] The second pitch P2 cannot be less than 0.1 µm and not more than 5 µm. The second pitch P2 may have a value that falls within one of the following ranges: not less than 0.1 µm and not more than 0.25 µm, not less than 0.25 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 0.75 µm, not less than 0.75 µm and not more than 1 µm, not less than 1 µm and not more than 1.5 µm, not less than 1.5 µm and not more than 2 µm, not less than 2 µm and not more than 2.5 µm, not less than 2.5 µm and not more than 3 µm, not less than 3 µm and not more than 3.5 µm, not less than 3.5 µm and not more than 4 µm, not less than 4 µm and not more than 4.5 µm, and not less than 4.5 µm and not more than 5 µm. The second pitch P2 is preferably not less than 0.5 µm and not more than 1.5 µm.

[0163] In this embodiment, the super junction structure SJ was described as a two-layer structure. However, a super junction structure SJ with a laminated structure of three or more layers may also be used. That is, the laminated portion 7 with the laminated structure may be formed of three or more layers, and the pillar region 12 with the laminated structure may be formed of three or more layers.

[0164] In this case, the third and subsequent semiconductor layers in the laminated portion 7 are formed to have an identical configuration to the second layer 9. A region formed in an odd-numbered semiconductor layer (2n + 1: n is a natural number not less than 1) in the pillar region 12 is formed to have a configuration identical to that of the first region 14 (the first mark Mk1), and a region formed in an even-numbered semiconductor layer (2n + 2) is formed to have a configuration identical to that of the second region 15 (the second mark Mk2). Of the pillar region 12, a region in an (n + 2)-th layer is formed in the (n + 2)-th semiconductor layer in a relationship identical to the relationship of a region in an (n + 1)-th layer to a region in an n-th layer.

[0165] Below, a layout example of the first areas 14 and the second areas 15 is shown with reference to the Fig. 7, Fig. 8A and Fig. 8B. The structural pattern PT (the plurality of first marks Mk1 and the plurality of second marks Mk2) is formed in a layout corresponding to the layout examples of the first regions 14 and the second regions 15 described below.

[0166] Fig. 8A is a plan view showing a first layout example of the column portion 12 according to the first basic shape. Fig. 8B is a plan view showing a second layout example of the column portion 12 according to the first basic shape. In Fig. 8A and Fig. 8B, the first area 14 is shown by a dashed line and the second area 15 by hatching.

[0167] As in Fig. 7, Fig. 8A and Fig. 8B, the first arrangement direction Da1 of the first regions 14 may be the a-axis direction (the first direction X), and the first extension direction De1 of the first regions 14 may be the m-axis direction (the second direction Y). In this case, since the first extension direction De1 intersects (specifically, is orthogonal to) the deviation direction Doff of the first layer 8, in cross-sectional view, the plurality of first regions 14 are inclined from an m-plane ((1-100) plane) of the SiC single crystal substantially by the deviation angle θoff from the vertical axis toward the deviation direction Doff. The m-plane of the SiC single crystal is a crystal plane orthogonal to the m-axis.

[0168] As in Fig. 7 and Fig. As shown in FIG. 8A, the plurality of second regions 15 may be orthogonal to the plurality of first regions 14 in plan view. That is, the second arrangement direction Da2 of the second regions 15 may be the m-axis direction (the second direction Y), and the second extension direction De2 of the second regions 15 may be the a-axis direction (the first direction X). In this case, the second arrangement direction Da2 coincides with the first extension direction De1 and is orthogonal to the first arrangement direction Da1. In addition, the second extension direction De2 is aligned with the first arrangement direction Da1 and is orthogonal to the first extension direction De1.

[0169] In this case, since the second extension direction De2 coincides with the deviation direction Doff of the second layer 9, the plurality of second regions 15 extend substantially in the vertical direction Z when viewed from an a-plane ((11-20) plane) of the SiC single crystal in a cross-sectional view. The a-plane of the SiC single crystal is located in a direction orthogonal to the a-axis. The plurality of second regions 15 are inclined substantially by the deviation angle θoff from the vertical axis in the direction of the deviation direction Doff when viewed from the m-plane of the SiC single crystal in a cross-sectional view.

[0170] Of course, the plurality of second regions 15 cannot intersect orthogonally with the plurality of first regions 14 in plan view (see Fig. 8B). That is, the second arrangement direction Da2 of the second regions 15 may be a direction other than the m-axis direction and the a-axis direction, and the second extension direction De2 of the second regions 15 may be a direction other than the m-axis direction and the a-axis direction. In this case, the second arrangement direction Da2 intersects both the first arrangement direction Da1 and the first extension direction De1, and the second extension direction De2 intersects both the first arrangement direction Da1 and the first extension direction De1. In addition, the second extension direction De2 intersects the deviation direction Doff of the second layer 9.

[0171] The second extension direction De2 may be inclined from the a-axis to one side (the left side of the layer surface) or to the other side (the right side of the layer surface) of the m-axis in plan view. The plurality of second regions 15 have the second extension direction De2, which forms an extension angle θa with the a-axis when the a-axis is a reference (0°).

[0172] The absolute value of the extension angle θa can be greater than 0° and less than 90°. The extension angle θa can have a value that falls within one of the following ranges: more than 0° and not more than 18°, not less than 18° and not more than 36°, not less than 36° and not more than 54°, not less than 54° and not more than 72°, and not less than 72° and less than 90°. The absolute value of the extension angle θa is generally set to a value that falls within one of the ranges 30° ± 5°, 45° ± 5°, and 60° ± 5°.

[0173] The column area 12 can Fig. 9, Fig. 10A and Fig. 10B. Fig. 9 is a perspective cross-sectional view showing a second basic shape of the column portion 12. Fig. 10A and Fig. 10B are plan views showing first and second layout examples of the column portion 12 according to the second basic shape. In Fig. 10A and Fig. 10B, the first area 14 is shown by a dashed line and the second area 15 by hatching.

[0174] As in Fig. 9, Fig. 10A and Fig. 10B, the first arrangement direction Da1 of the first regions 14 may be the m-axis direction (the first direction X), and the first extension direction De1 of the first regions 14 may be the a-axis direction (the second direction Y). In this case, since the first extension direction De1 coincides with the deviation direction Doff of the first layer 8, the plurality of first regions 14 extend substantially in the vertical direction Z when viewed from the a-plane of the SiC single crystal in a cross-sectional view. The plurality of first regions 14 are inclined substantially by the deviation angle θoff from the vertical axis in the direction of the deviation direction Doff in the cross-section through the m-plane of the SiC single crystal.

[0175] As in Fig. 9 and Fig. As shown in FIG. 10A, the plurality of second regions 15 may be orthogonal to the plurality of first regions 14 in plan view. That is, the second arrangement direction Da2 of the second regions 15 may be the a-axis direction (the second direction Y), and the second extension direction De2 of the second regions 15 may be the m-axis direction (the first direction X). In this case, the second arrangement direction Da2 coincides with the first extension direction De1 and is orthogonal to the first arrangement direction Da1. In addition, the second extension direction De2 is aligned with the first arrangement direction Da1 and is orthogonal to the first extension direction De1.

[0176] In this case, since the second extension direction De2 intersects (more precisely, is orthogonal to) the deviation direction Doff of the second layer 9, the plurality of second regions 15 are inclined substantially by the deviation angle θoff from the vertical axis in the direction of the deviation direction Doff in a cross-sectional view from the m-plane of the SiC single crystal.

[0177] Of course, the plurality of second regions 15 cannot intersect orthogonally with the plurality of first regions 14 in plan view (see Fig. 10B). That is, the second arrangement direction Da2 of the second regions 15 may be a direction other than the a-axis direction and the m-axis direction, and the second extension direction De2 of the second regions 15 may be a direction other than the a-axis direction and the m-axis direction. In this case, the second arrangement direction Da2 intersects both the first arrangement direction Da1 and the first extension direction De1, and the second extension direction De2 intersects both the first arrangement direction Da1 and the first extension direction De1. In addition, the second extension direction De2 intersects the deviation direction Doff of the second layer 9.

[0178] The second extension direction De2 may be inclined from the a-axis to one side (the left side of the layer surface) or to the other side (the right side of the layer surface) of the m-axis in plan view. The plurality of second regions 15 have the second extension direction De2, which forms an extension angle θa with the a-axis when the a-axis is a reference (0°).

[0179] The absolute value of the extension angle θa can be greater than 0° and less than 90°. The extension angle θa can have a value that falls within one of the following ranges: more than 0° and not more than 18°, not less than 18° and not more than 36°, not less than 36° and not more than 54°, not less than 54° and not more than 72°, and not less than 72° and less than 90°. The absolute value of the extension angle θa is generally set to a value that falls within one of the ranges 30° ± 5°, 45° ± 5°, and 60° ± 5°.

[0180] The column area 12 can be used in the Fig. 11, Fig. 12A, Fig. 12B and Fig. 12C. Fig. 11 is a perspective cross-sectional view showing a third basic shape of the column portion 12. Fig. 12A, Fig. 12B and Fig. 12C are plan views showing first, second, and third layout examples of the column portion 12 according to the third basic shape, respectively. Fig. 12A to 12C, the first region 14 is represented by a dashed line and the second region 15 by hatching.

[0181] As in Fig. 11 and 12A to 12C, the first arrangement direction Da1 of the first regions 14 may be a direction other than the a-axis direction (the first direction X) and the m-axis direction (the second direction Y), and the first extension direction De1 of the first regions 14 may be a direction other than the a-axis direction and the m-axis direction. That is, the plurality of first regions 14 may cross both the a-axis direction and the m-axis direction. Fig. 12A to 12C show examples in which the first regions 14 are inclined to one side (the left side of the layer surface) of the m-axis with respect to the a-axis.

[0182] In this case, since the first extension direction De1 intersects the deviation direction Doff, the plurality of first regions 14 are inclined substantially by the deviation angle θoff from the vertical axis in the direction of the deviation direction Doff in the cross-sectional view from the a-plane of the SiC single crystal and in the cross-sectional view from the m-plane of the SiC single crystal.

[0183] The first extension direction De1 forms a first extension angle θ1 with the a-axis when the a-axis is set as a reference (0°). An absolute value of the first extension angle θ1 can be greater than 0° and less than 90°. The first extension angle θ1 can have a value that falls within any of the following ranges: more than 0° and not more than 18°, not less than 18° and not more than 36°, not less than 36° and not more than 54°, not less than 54° and not more than 72°, and not less than 72° and less than 90°.

[0184] The absolute value of the extension angle θ1 is usually set to a value that falls within one of the ranges 30° ± 5°, 45° ± 5° and 60° ± 5°. Fig. 12A shows a layout example in which the absolute value of the first extension angle θ1 is substantially 45°, Fig. 12B shows a layout example in which the absolute value of the first extension angle θ1 is substantially 30°, and Fig. 12C shows a layout example in which the absolute value of the first extension angle θ1 is substantially 60°.

[0185] As in Fig. 11 and 12A to 12C, the first arrangement direction Da1 of the second regions 15 may be a direction other than the a-axis direction (the first direction X) and the m-axis direction (the second direction Y), and the first extension direction De1 of the second regions 15 may be a direction other than the a-axis direction and the m-axis direction. That is, the plurality of second regions 15 may intersect both the a-axis direction and the m-axis direction. In this example, the second regions 15 are inclined toward the other side (the right side of the layer surface) of the m-axis with respect to the a-axis.

[0186] In this case, since the second extension direction De2 intersects the deviation direction Doff, the plurality of second regions 15 are inclined substantially by the deviation angle θoff from the vertical axis in the direction of the deviation direction Doff in the cross-sectional view from the a-plane of the SiC single crystal and in the cross-sectional view from the m-plane of the SiC single crystal.

[0187] The second extension direction De2 forms a second extension angle θ2 with the a-axis when the a-axis is set as a reference (0°). In a case where the first extension angle θ1 is defined as a "positive value," the second extension angle θ2 is set to a "negative value." In a case where the first extension angle θ1 is defined as a "negative value," the second extension angle θ2 is set to a "positive value."

[0188] An absolute value of the second extension angle θ2 can be greater than 0° and less than 90°. The second extension angle θ2 can have a value that falls within one of the following ranges: more than 0° and not more than 18°, not less than 18° and not more than 36°, not less than 36° and not more than 54°, not less than 54° and not more than 72°, and not less than 72° and less than 90°.

[0189] The absolute value of the second extension angle θ2 is generally set to a value falling within one of the ranges of 30° ± 5°, 45° ± 5°, and 60° ± 5°. The absolute value of the second extension angle θ2 is preferably substantially equal to the absolute value of the first extension angle θ1. That is, it is preferable that the plurality of second regions 15 have a layout that is substantially axisymmetric with respect to the plurality of first regions 14 with respect to the a-axis in the plan view per unit area (ie, in the partial plan view). In other words, it is preferable that the plurality of second regions 15 have a layout that is substantially point-like with respect to the plurality of first regions 14 with respect to the vertical axis in the plan view per unit area (ie, in the partial plan view).

[0190] Fig. 12A shows the layout example in which the absolute value of the second extension angle θ2 is substantially 45° (≈ 01), Fig. 12B shows the layout example in which the absolute value of the second extension angle θ2 is substantially 30° (≈ θ1), and Fig. 12C shows the layout example where the absolute value of the second extension angle θ2 is substantially 60° (≈ 01).

[0191] That is, in the layout example of Fig. 12A, the plurality of second regions 15 extend in a direction intersecting both the a-axis direction and the m-axis direction and are orthogonal to the plurality of first regions 14. A sum of the absolute value of the first extension angle θ1 and the absolute value of the second extension angle θ2 is substantially a right angle (substantially 90°).

[0192] In contrast, in the layout example of Fig. 12B, the plurality of second regions 15 in a direction that intersects both the a-axis direction and the m-axis direction and non-orthogonally intersects the plurality of first regions 14. A sum of the absolute value of the first extension angle θ1 and the absolute value of the second extension angle θ2 is substantially an acute angle (substantially 60°). In the layout example of Fig. 12C, the plurality of second regions 15 extend in a direction that intersects both the a-axis direction and the m-axis direction and non-orthogonally intersects the plurality of first regions 14. A sum of the absolute value of the first extension angle θ1 and the absolute value of the second extension angle θ2 is substantially an obtuse angle (substantially 120°).

[0193] Of course, the absolute value of the second extension angle θ2 may be greater than the absolute value of the first extension angle θ1 or smaller than the absolute value of the first extension angle θ1. That is, the plurality of second regions 15 may have a layout that is not axisymmetric with respect to the plurality of first regions 14 with respect to the a-axis in the plan view per unit area (ie, in the partial plan view). In other words, the plurality of second regions 15 may have a layout that is not point-like with respect to the plurality of first regions 14 with respect to the vertical axis in the plan view per unit area (ie, in the partial plan view).

[0194] The following describes in more detail a concentration gradient of the p-type impurity concentration of the first region 14 and a concentration gradient of the p-type impurity concentration of the second region 15. Since the concentration gradient of the first region 14 and the concentration gradient of the second region 15 are substantially identical, the concentration gradient of the second region 15 is exemplified below.

[0195] The description of the concentration gradient of the first region 14 is obtained by replacing the "first layer 8" with the "base layer 6," the "second layer 9" with the "first layer 8," the "second region 15 (the second lower end portion 15a and the second upper end portion 15b)" with the "first region 14 (the first lower end portion 14a and the first upper end portion 14b)," and the "second axis channel CH2" with the "first axis channel CH1" as necessary in the following description. That is, a relative or absolute positional relationship of the second region 15 with respect to the first layer 8 and the second layer 9 is applied to a relative or absolute positional relationship of the first region 14 with respect to the base layer 6 and the first layer 8.

[0196] Fig. 13A to 13E are diagrams showing an example of the concentration gradient of the second region 15 (the first region 14). Fig. Figure 14 is a diagram showing a comparative example of the concentration gradient of the second region 15 (the first region 14). Fig. 13 and Fig. 14, the ordinate represents the p-type impurity concentration of the second region 15, and the abscissa represents a depth along the second axis channel CH2 based on the top end of the second layer 9 (the first main surface 3) (a zero point).

[0197] In Fig. 13A to 13E and 14 is a region having a p-type impurity concentration of not less than 1 × 10 15 cm -3as the second region 15 and graphically depicted. The numerical values ​​for the impurity concentration, thickness, etc. given below are an example of describing a basic configuration of the second region 15 based on the concentration gradient and are not intended to uniquely limit the configuration of the second region 15. The impurity concentration, thickness, etc. are set to various values ​​according to the implantation conditions of a trivalent element (dose amount, implantation temperature, implantation energy, etc.).

[0198] Fig. 13A to 13E are diagrams for cases where the second region 15 is formed by a channel implantation method. Fig. 13A to 13E show concentration gradients of the second region 15 when a predetermined trivalent element (here aluminum) is implanted into the second layer 9 parallel or substantially parallel to the second axis channel CH2 with an implantation energy of 190 KeV ( Fig. 13A), 380 KeV ( Fig. 13B), 650 KeV ( Fig. 13C), 960 KeV ( Fig. 13D) or 2000 KeV ( Fig. 13E). The second thickness T2 of the second layer 9 is about 3 µm, and the dose amount of the trivalent element is 1 × 10 13 cm -2 .

[0199] Fig. 14 is a diagram for the case where the second region 15 is formed by a random implantation method. Fig. Figure 14 shows a concentration gradient of the second region 15 when the predetermined trivalent element (here, aluminum) is introduced into the second layer 9 in a random direction with an implantation energy of 190 KeV, 380 KeV, 650 KeV, 960 KeV, or 2000 KeV. The random direction is a direction that is not parallel (substantially parallel) to the second axis channel CH2 (e.g., the vertical direction Z). The second thickness T2 of the second layer 9 is approximately 3 µm, and the dose amount of the trivalent element is 1 × 10 13 cm -2 .

[0200] As in Fig. 13A, the second region 15 (190 KeV) has the second region thickness TR2 of not less than 1.5 μm and not more than 1.8 μm, and includes the second lower end portion 15a separated from the lower end toward the upper end side of the second layer 9, and the second upper end portion 15b exposed from the upper end (the first main surface 3) of the second layer 9. A distance between the lower end of the second layer 9 and the second lower end portion 15a may be not less than 1.2 μm and not more than 1.5 μm.

[0201] The p-type impurity concentration of the second region 15 has a concentration gradient including a gradually rising portion 20, a peak portion 21, a shallow gradient portion 22, and a gradually falling portion 23 from the top to the bottom of the second layer 9. The gradually rising portion 20 is a portion constituting the second upper end portion 15b of the second region 15, and is a portion in which the p-type impurity concentration gradually increases from the second upper end portion 15b toward the bottom end side of the second layer 9 to the peak portion 21 at a relatively steep rate of increase.

[0202] The peak portion 21 is a region with a peak value P (a maximum value) of the p-type impurity concentration. The peak portion 21 may also be a main concentration transition portion, which has a projected shape including a series of concentration changes (inflection points) where the p-type impurity concentration transitions from an increase (increasing trend) to a decrease (decreasing trend). A depth position of the peak portion 21 is not less than 0.1 µm and not more than 0.5 µm.

[0203] The shallow gradient portion 22 is located in a region closer to the second lower end portion 15a than the tip portion 21, and is a portion where the impurity concentration decreases at a relatively slow rate. That is, the shallow gradient portion 22 is a portion where a constant p-type impurity concentration is maintained in a constant depth range and forms a main body portion of the second region 15. The p-type impurity concentration of the shallow gradient portion 22 decreases smoothly in a concentration range smaller than the p-type impurity concentration of the tip portion 21.

[0204] The shallow gradient section 22 is defined by a section with a concentration decrease of at most 50% in a thickness range of at least 0.5 µm. In this example, the shallow gradient section 22 has a thickness of not less than 0.7 µm and not more than 0.8 µm and has a concentration decrease of not more than 50% in this thickness range. In this example, the p-type impurity concentration of the shallow gradient section 22 is in a concentration range of not less than 4.5 × 10 16 cm -3 and not more than 9 × 10 16 cm -3 .

[0205] The gradually sloping portion 23 is a portion forming the second lower end portion 15a of the second region 15. The gradually sloping portion 23 has a larger concentration decrease rate than the concentration decrease rate in the shallow gradient portion 22 and is a portion in which the p-type impurity concentration gradually decreases from the shallow gradient portion 22 toward the lower end of the second layer 9. The concentration decrease rate per unit thickness of the gradually sloping portion 23 is higher than the concentration decrease rate per unit thickness of the shallow gradient portion 22. The p-type impurity concentration of the gradually sloping portion 23 gradually decreases from the shallow gradient portion 22 to 1 × 10 15 cm -3 away.

[0206] As in Fig. 13B, the second region 15 (380 KeV) has the second region thickness TR2 of not less than 2.2 μm and not more than 2.4 μm, and has the second lower end portion 15a separated from the lower end to the upper end side of the second layer 9, and the second upper end portion 15b separated from the upper end (the first main surface 3) to the lower end side (the first layer 8 side) of the second layer 9. A distance between the lower end of the second layer 9 and the second lower end portion 15a is not less than 0.5 μm and not more than 0.8 μm. The distance between the upper end of the second layer 9 and the second upper end portion 15b of the second region 15 is not less than 0.01 μm and not more than 0.2 μm.

[0207] As in the example in Fig. As shown in FIG. 13A, the p-type impurity concentration of the second region 15 has a concentration gradient including the gradually rising portion 20, the peak portion 21, the shallow gradient portion 22, and the gradually falling portion 23 from the top to the bottom of the second layer 9. Also in this example, the gradually rising portion 20 increases from the second top end portion 15b toward the bottom end side of the second layer 9 at a relatively steep rate of increase up to the peak portion 21. A depth position of the peak portion 21 is not less than 0.3 μm and at most 0.7 μm.

[0208] The shallow gradient section 22 has a thickness of not less than 0.8 µm and not more than 1.1 µm, and within this thickness range, the concentration decrease does not exceed 50%. In this example, the p-type impurity concentration of the shallow gradient section 22 is in a concentration range of not less than 3.5 × 10 16 cm -3 and not more than 7 × 10 16 cm -3 . The p-type impurity concentration of the gradually decreasing section 23 gradually increases from the shallow gradient section 22 to 1 × 10 15 cm -3 away.

[0209] As in Fig. 13C, the second region 15 (650 KeV) has the second region thickness TR2 of not less than 2.5 μm and not more than 2.8 μm, and has the second lower end portion 15a separated from the lower end to the upper end side of the second layer 9, and the second upper end portion 15b separated from the upper end (the first main surface 3) to the lower end side (the first layer 8 side) of the second layer 9. A distance between the lower end of the second layer 9 and the second lower end portion 15a is not less than 0.01 μm and not more than 0.1 μm. A distance between the upper end of the second layer 9 and the second upper end portion 15b of the second region 15 is not less than 0.1 μm and not more than 0.4 μm.

[0210] As in the example according to Fig. As shown in FIG. 13A, the p-type impurity concentration of the second region 15 has a concentration gradient including the gradually rising portion 20, the peak portion 21, the shallow gradient portion 22, and the gradually falling portion 23 from the second upper end portion 15b to the second lower end portion 15a. Also in this example, the gradually rising portion 20 gradually increases from the second upper end portion 15b of the second region 15 to the peak portion 21 at a relatively steep increase rate. The depth position of the peak portion 21 is not less than 0.6 μm and not more than 1 μm.

[0211] The shallow gradient section 22 has a thickness of not less than 1 µm and not more than 1.3 µm, and has a concentration decrease of not more than 50% within this thickness range. In this example, the p-type impurity concentration of the shallow gradient section 22 is in a concentration range of not less than 3 × 10 16 cm -3 and not more than 6 × 10 16 cm -3 . The p-type impurity concentration of the gradually decreasing section 23 gradually increases from the shallow gradient section 22 to 1 × 10 15 cm -3 away.

[0212] As in Fig. As shown in Figure 13D, the second region 15 (960 KeV) has the second region thickness TR2 of not less than 3.1 μm and not more than 3.3 μm, and includes the second upper end portion 15b separated from the upper end (the first main surface 3) toward the lower end side (the first layer 8 side) of the second layer 9, and the second lower end portion 15a disposed in the first layer 8. That is, the second region 15 has a second region thickness TR2 greater than the second thickness T2 (= 3 μm) of the second layer 9.

[0213] In addition, the second lower end portion 15a has an extending portion that crosses a boundary between the first layer 8 and the second layer 9 and extends in the first layer 8. The extending portion of the second lower end portion 15a has a thickness of not less than 0.4 μm and not more than 0.7 μm based on the upper end of the first layer 8. A distance between the upper end of the second layer 9 and the second upper end portion 15b of the second region 15 is not less than 0.3 μm and not more than 0.6 μm.

[0214] As in the example according to Fig. As shown in FIG. 13A, the p-type impurity concentration of the second region 15 has a concentration gradient including the gradually rising portion 20, the peak portion 21, the shallow gradient portion 22, and the gradually falling portion 23 from the second upper end portion 15b to the second lower end portion 15a. Also in this example, the gradually rising portion 20 gradually increases from the second upper end portion 15b of the second region 15 to the peak portion 21 at a relatively steep rate. A depth position of the peak portion 21 is at least 0.7 μm and at most 1.3 μm.

[0215] The shallow gradient section 22 has a thickness of not less than 1.3 µm and not more than 1.7 µm, and exhibits a concentration decrease of not more than 50% within this thickness range. In this example, the p-type impurity concentration of the shallow gradient section 22 is in a concentration range of not less than 2.2 × 10 16 cm -3 and not more than 4.5 × 10 16 cm -3 . The p-type impurity concentration of the gradually decreasing section 23 gradually increases from the shallow gradient section 22 to 1 × 10 15 cm -3 away.

[0216] As in Fig. As shown in Figure 13E, the second region 15 (2000 KeV) has the second region thickness TR2 of not less than 3.5 μm and not more than 3.8 μm, and includes the second upper end portion 15b separated from the upper end (the first main surface 3) toward the lower end side (the first layer 8 side) of the second layer 9, and the second lower end portion 15a disposed in the first layer 8. That is, the second region 15 has a second region thickness TR2 greater than the second thickness T2 (= 3 μm) of the second layer 9.

[0217] In addition, the second lower end portion 15a has an extension portion that crosses a boundary between the first layer 8 and the second layer 9 and extends in the first layer 8. The extension portion of the second lower end portion 15a has a thickness of not less than 1.4 μm and not more than 1.8 μm relative to the upper end of the first layer 8. A distance between the upper end of the second layer 9 and the second upper end portion 15b of the second region 15 is not less than 0.7 μm and not more than 1 μm.

[0218] As in the example according to Fig. As shown in FIG. 13A, the p-type impurity concentration of the second region 15 has a concentration gradient including the gradually rising portion 20, the peak portion 21, the shallow gradient portion 22, and the gradually falling portion 23 from the second upper end portion 15b to the second lower end portion 15a. Also in this example, the gradually rising portion 20 gradually increases from the second upper end portion 15b of the second region 15 to the peak portion 21 at a relatively steep rate. A depth position of the peak portion 21 is at least 1.3 μm and at most 1.9 μm.

[0219] The shallow gradient portion 22 has a thickness of not less than 1.5 µm and not more than 1.8 µm, and within this thickness range, the concentration decrease does not exceed 50%. In this example, the shallow gradient portion 22 crosses the boundary between the first layer 8 and the second layer 9 and is located within the first layer 8. That is, the extension portion of the second region 15 includes a part of the shallow gradient portion 22. In this example, the p-type impurity concentration of the shallow gradient portion 22 is in a concentration range of not less than 2 × 10 16 cm -3 and not more than 4 × 10 16 cm -3 . The p-type impurity concentration of the gradually decreasing section 23 gradually increases from the shallow gradient section 22 to 1 × 10 15 cm -3 away.

[0220] As in the Fig. As shown in FIGS. 13A to 13E, the p-type impurity concentration of the second region 15 includes the gradually rising portion 20, the peak portion 21, the shallow gradient portion 22, and the gradually falling portion 23 at any implantation energy. Also, the second region thickness TR2 (depth) of the second region 15 increases with increasing implantation energy. Furthermore, a depth position of the second upper end portion 15b of the second region 15 relative to the upper end of the second layer 9 increases as the implantation energy increases.

[0221] The thickness of the gradually rising portion 20, the thickness of the peak portion 21, the thickness of the shallow gradient portion 22, and the thickness of the gradually falling portion 23 all increase with increasing implantation energy. At the same time, the peak value P of the second region 15 decreases with increasing implantation energy. This is because the trivalent element is introduced into a deep region with increasing implantation energy, and the p-type impurity concentration in this deep region increases.

[0222] The shallow gradient portion 22 constitutes a thickness region of not less than 1 / 4 of the second region 15 (the second region thickness TR2) and is arranged in the second layer 9. Specifically, the ratio between the shallow gradient portion 22 and the second region 15 is not less than 1 / 3. The ratio between the shallow gradient portion 22 and the second region 15 is normally not more than 1 / 2 (less than 1 / 2). The ratio between the shallow gradient portion 22 and the second region 15 cannot be less than 1 / 2.

[0223] As in Fig. 14, in the case of the random implantation method, the second region 15 has the gradually rising portion 20, the peak portion 21 (the peak value P), and the gradually falling portion 23 within a range of 0.5 μm, but does not have the shallow gradient portion 22 with a thickness of not less than 0.5 μm. Also, in the random implantation method, a depth position of the peak portion 21 (the peak value P) with respect to the top end of the second layer 9 increased with increasing implantation energy, but the second region thickness TR2 of the second region 15 was less than 2 μm at each implantation energy. That is, even when the implantation energy was increased, the second region thickness TR2 did not change significantly.

[0224] This leads to the understanding that in the case of the random implantation method, it is difficult to improve the charge balance accuracy when the second layer 9 has a relatively large second thickness T2 (e.g., a second thickness T2 of not less than 1 µm) and the second region 15 is formed from a single impurity region. Unlike a Si single crystal, the SiC single crystal has physical properties that make it difficult for impurities to diffuse. Therefore, the problem described above is generally solved by a multi-epitaxy method or a multi-stage random implantation method.

[0225] In the multiple epitaxial growth process, a step of introducing a trivalent element into an epitaxial layer with a relatively thin thickness (e.g., a thickness of less than 1 µm) is repeated multiple times through a random implantation process. However, as the number of epitaxial growth steps and the number of random implantation steps increase in this step, the manufacturing process becomes more complicated.

[0226] In the multi-stage random implantation process, trivalent elements are inserted into different depth positions with a variety of implantation energies in several stages. According to the example in Fig. 14, for example, in the case where the second layer 9 is formed with a thickness of 1 µm, trivalent elements are introduced into the second layer 9 at five levels of implantation energy (190 KeV, 380 KeV, 650 KeV, and 960 KeV). In this step, the trivalent elements can be introduced to a target depth position, but the depth position at which the trivalent element can be introduced is shallow. Therefore, the number of epitaxial growth steps and the number of random implantation steps must be increased, resulting in a problem similar to that of the multiple epitaxial growth method.

[0227] On the other hand, in the channel implantation method, the second region 15, which includes the shallow gradient portion 22 with a thickness of not less than 0.5 μm and not more than 2 μm, is formed with a relatively large thickness (for example, a thickness of not less than 1 μm and not more than 5 μm) relative to the second layer 9. Therefore, the second charge-balanced region 15 is formed in fewer steps than in the case of the random implantation method.

[0228] Of course, this description does not exclude the technical idea of ​​forming the single second region 15 by introducing a plurality of second regions 15 at different depth positions in multiple steps by the channel implantation method using a variety of implantation energies. In this case, each of the second regions 15 is formed from an integrated region of a plurality of impurity regions (the second regions 15), each formed in the second layer 9 along the second axis channel CH2 so as to cross the intermediate portion of the second layer 9.

[0229] In this case, the p-type impurity concentration (concentration gradient) of each of the second regions 15 is an added value of the p-type impurity concentrations (concentration gradients) of the plurality of impurity regions (the second regions 15). For example, the p-type impurity concentrations of the respective second regions 15 have a concentration gradient (added concentration gradient) obtained by superposing at least two of the five impurity concentrations shown in the Fig. 13A to 13E.

[0230] In the examples in Fig. 13A to 13E, the upper limit of the implantation energy of the channel implantation method is 2000 KeV, but the second region 15 can also be formed with an implantation energy higher than 2000 KeV. In this case, the relatively thick second region 15 is formed at a location deeper than that shown in Fig. Concentration gradient shown in Figure 13E.

[0231] However, in a case where the implantation energy is higher than 2000 KeV, the difficulty of constructing the pillar region 12 increases because the amount of trivalent elements passing through the upper end portion of the second layer 9 increases and the area of ​​a void on that side of the upper end portion (ie, a distance between the first main surface 3 and the second region 15) becomes larger. Even in the case where the implantation energy is higher than 2000 KeV, it is considered that the implantation energy is not realistic from the perspective of cost-effectiveness (installation site or capital investment) because the size of an ion accelerator can reach several tens of meters.

[0232] Therefore, in a case where the relatively thick pillar region 12 is formed by the channel implantation method, it is preferable to limit the implantation energy to not more than 2000 KeV and to increase the number of laminated layers of the laminated portion 7 (the number of laminated layers of the super junction structure SJ).

[0233] The first to twelfth configuration examples of the column area 12 are described below with reference to the Fig. 15 to 35. The column portion 12 according to the first to third basic forms may include at least one of the features described in the first to twelfth configuration examples. The column portion 12 according to the first to third basic forms may include a feature resulting from the combination of several (two or more) features described in the first to twelfth configuration examples.

[0234] Hereinafter, the “gradually rising portion 20”, the “peak portion 21 (the peak value P)”, the “flat gradient portion 22”, and the “gradually falling portion 23” of the first region 14 are referred to as “first gradually rising portion 20A”, “first peak portion 21A (a first peak value PA)”, “first flat gradient portion 22A”, and “first gradually falling portion 23A”. In addition, hereinafter, the “gradually rising portion 20”, the “peak portion 21 (the peak value P)”, the “shallow gradient portion 22”, and the “gradually falling portion 23” of the second region 15 are referred to as a “second gradually rising portion 20B”, a “second peak portion 21B (a second peak value PB)”, a “second shallow gradient portion 22B”, and a “second gradually falling portion 23B”.

[0235] Fig. 15 is a perspective cross-sectional view showing the column portion 12 according to the first configuration example. Fig. 16 is a diagram showing an example of a concentration gradient of the Fig. 15 shows the column area 12.

[0236] As in the Fig. 15 and Fig. 16, the first region 14 has the first region thickness TR1, which is smaller than the first thickness T1 of the first layer 8, and is formed in the first layer 8 at an interval from both the lower and upper ends of the first layer 8. Specifically, the first lower end portion 14a of the first region 14 is formed at an interval from the lower end (i.e., the base layer 6) toward the upper end side of the first layer 8 and faces the base layer 6 via a part (the lower end portion) of the first layer 8.

[0237] Meanwhile, the first upper end portion 14b of the first regions 14 is formed at an interval from the upper end (i.e., the second layer 9) toward the lower end side of the first layer 8 and faces the second layer 9 via a part (the upper end portion) of the first layer 8. The first gradually rising portion 20A, the first peak portion 21A, the first gently sloping portion 22A, and the first gradually falling portion 23A of the first region 14 are located in the first layer 8.

[0238] Fig. 16 shows an example in which the first layer 8 has a first thickness T1 of 3 µm, and the first region 14 is formed in the first layer 8 with an implantation energy of 650 KeV. Of course, the first region 14 may be formed with an implantation energy of not more than 650 KeV.

[0239] The second region 15 has the second region thickness TR2, which is smaller than the second thickness T2 of the second layer 9, and is formed in the second layer 9 at an interval from both the lower end and the upper end of the second layer 9. Specifically, the second lower end portion 15a of the second region 15 is formed at an interval from the lower end (of the first layer 8) toward the upper end side of the second layer 9 and faces the first layer 8 via a part (the lower end portion) of the second layer 9.

[0240] The second upper end portion 15b of the second region 15 is formed at an interval from the upper end (i.e., the first main surface 3) toward the lower end side of the second layer 9 and faces the first main surface 3 over a part (the upper end portion) of the second layer 9. The second gradually rising portion 20B, the second peak portion 21B, the second gently sloping portion 22B, and the second gradually falling portion 23B of the second region 15 are located in the second layer 9.

[0241] Fig. 16 shows an example in which the second layer 9 has a second thickness T2 of 3 µm and the second region 15 in the second layer 9 is formed with an implantation energy of 650 KeV. Of course, the second region 15 can be formed with an implantation energy of no more than 650 KeV. The implantation energy for the second region 15 can also differ from the implantation energy for the first region 14.

[0242] That is, the second region thickness TR2 of the second region 15 may differ from the first region thickness TR1 of the first region 14. The second region thickness TR2 may be less than the first region thickness TR1 or greater than the first region thickness TR1.

[0243] Fig. 17 is a perspective cross-sectional view showing the column portion 12 according to the second configuration example. Fig. 18 is a diagram showing an example of a concentration gradient of the Fig. 17 shows the column area 12. As shown in Fig. 17 and Fig. As shown in Figure 18, the column portion 12 according to the second configuration example has a shape obtained by modifying the second portion 15 according to the first configuration example. The shape of the first portion 14 according to the second configuration example is identical to that of the first portion 14 according to the first configuration example.

[0244] The second region 15 is formed in the second layer 9 at an interval from the upper end to the lower end side of the second layer 9 and has a part positioned in the first layer 8 by crossing the boundary between the first layer 8 and the second layer 9. That is, the second lower end portion 15a of the second region 15 may have an extension portion that crosses the boundary portion between the first layer 8 and the second layer 9 and is located in the first layer 8.

[0245] Since the second axial channel CH2 is substantially aligned with the first axial channel CH1, the extending portion of the second lower end portion 15a is formed along the first axial channel CH1 in the first layer 8. The extending portion of the second lower end portion 15a is preferably located on the upper end side of the first layer 8 with respect to the middle thickness region of the first layer 8. The extending portion of the second lower end portion 15a is connected to the first region 14 (the first upper end portion 14b) in the first layer 8.

[0246] In this configuration, a part (the extension portion) of the second region 15 is provided in a space between the upper end of the first layer 8 and the first upper end portion 14b of the first region 14, and a pillar region 12 continuously extending in a three-dimensional lattice shape is formed by the first region 14 and the second region 15. This improves the accuracy of charge balancing.

[0247] In this example, the second region thickness TR2 of the second region 15 is greater than the second thickness T2 of the second layer 9. Furthermore, the second region thickness TR2 can be greater than the first thickness T1 of the first layer 8. The second region thickness TR2 can also be greater than the first region thickness TR1 of the first region 14. Of course, the second region thickness TR2 can be less than the second thickness T2. Furthermore, the second region thickness TR2 can be less than the first region thickness TR1. Furthermore, the second region thickness TR2 can be less than the first region thickness TR1.

[0248] The second gradually rising portion 20B, the second tip portion 21B, the second gently sloping portion 22B, and the second gradually sloping portion 23B of the second region 15 are located in the second layer 9. At least a part of the second gradually sloping portion 23B is located in the first layer 8. That is, the extending portion of the second lower end portion 15a includes the second gradually sloping portion 23B. Of course, a part of the second gently sloping portion 22B may be positioned in the first layer 8 (see Fig. 13E). That is, the extending portion of the second lower end portion 15a may include a part of the second flat gradient portion 22B and the second gradually sloping portion 23B.

[0249] Fig. 18 shows an example in which the second layer 9 has a first thickness T1 of 3 µm and the second region 15 is formed in the second layer 9 with an implantation energy of 960 KeV. Of course, the second region 15 can be formed with an implantation energy of not less than 960 KeV. The second thickness T2 can, for example, be more than 3 µm and at most 5 µm. In this case, the second regions 15, which are connected to the first regions 14 in the first layer 8, are formed with an implantation energy of not less than 960 KeV (see also Fig. 13F to 13E).

[0250] Fig. 19 is a perspective cross-sectional view showing the column portion 12 according to the third configuration example. Fig. 20 is a diagram showing an example of a concentration gradient of the Fig. 19 shows the column area 12. As shown in Fig. 19 and Fig. As shown in Figure 20, the column portion 12 according to the third configuration example has a shape obtained by modifying the second portion 15 according to the second configuration example. The first portion 14 according to the third configuration example has an identical shape to the first portion 14 according to the first configuration example.

[0251] The second region 15 according to the second configuration example is formed in the second layer 9, whose second thickness T2 substantially corresponds to the first thickness T1 of the first layer 8. On the other hand, the second region 15 according to the third configuration example is formed in the second layer 9 with a second thickness T2 that is less than the first thickness T1 of the first layer 8. In this example, the second region thickness TR2 of the second region 15 is greater than the second thickness T2 of the second layer 9.

[0252] Fig. 19 shows an example in which the second layer 9 has a second thickness T2 of less than 3 µm (here 2 µm) and the second region 15 is formed in the second layer 9 with an implantation energy of 650 KeV. Of course, the second region 15 can be formed with an implantation energy of no more than 650 KeV.

[0253] The second thickness T2 may, for example, be not less than 1 µm and not more than 2 µm. In this case, the second region 15, which is connected to the first region 14 in the first layer 8, is formed with an implantation energy of not less than 190 KeV (see also Fig. 13A to 13E). The second thickness T2 may, for example, be not less than 2 µm and less than 3 µm. In this case, the second region 15, which is connected to the first region 14 in the first layer 8, is formed with an implantation energy of not less than 380 KeV (see also Fig. 13B to 13E).

[0254] With this configuration, a concentration gradient formed at a connecting portion between the first region 14 and the second region 15 becomes shallow, and the accuracy of charge balancing is improved. Furthermore, the second layer 9 with the relatively small second thickness T2 enables the formation of the second region 15 connected to the first region 14 with a relatively low implantation energy. This reduces manufacturing costs.

[0255] The relatively small second thickness T2 makes it possible, for example, to form the second region 15 connected to the first region 14 in the first layer 8 while setting the first region thickness TR1 (the implantation energy) of the first region 14 and the second region thickness TR2 (the implantation energy) of the second region 15 equal. In this case, process management of the manufacturing process is easy to perform. In these cases, the second thickness T2 of the second layer 9 can be set to be less than the first thickness T1 of the first layer 8, and the second region 15 with the second region thickness TR2 greater than the second thickness T2 can be formed.

[0256] Fig. 21 is a perspective cross-sectional view showing the column portion 12 according to the fourth configuration example. Fig. 22 is a diagram showing an example of a concentration gradient of the Fig. 21 shows the column area 12. As shown in Fig. 21 and Fig. As shown in FIG. 22, the column portion 12 according to the fourth configuration example has a shape obtained by modifying the first portion 14 according to the second configuration example. The second portion 15 according to the fourth configuration example has a shape identical to the shape of the second portion 15 according to the second configuration example. Of course, the second portion 15 according to the fourth configuration example has a shape identical to the shape of the second portion 15 according to the third configuration example.

[0257] The first region 14 is formed in the first layer 8 at an interval from the upper end to the lower end side of the first layer 8, and has a part positioned in the base layer 6 by crossing the boundary between the base layer 6 and the first layer 8. That is, the first lower end portion 14a of the first region 14 may have an extension portion that crosses the boundary portion between the base layer 6 and the first layer 8 and is located in the base layer 6.

[0258] Since the first axial channel CH1 substantially coincides with the base axial channel CHB, the extension portion of the first lower end portion 14a is formed along the base axial channel CHB in the base layer 6. The extension portions of the first lower end portion 14a are preferably arranged on the upper end side of the base layer 6 with respect to a central thickness region of the base layer 6. The extension portion of the first lower end portion 14a is connected to this base layer 6 in the base layer 6.

[0259] In this example, the first region thickness TR1 of the first region 14 is greater than the first thickness T1 of the first layer 8. The first region thickness TR1 can also be greater than the second thickness T2 of the second layer 9. Furthermore, the first region thickness TR1 can be greater than the second region thickness TR2 of the second region 15. Of course, the first region thickness TR1 can be less than the first thickness T1. Of course, the first region thickness TR1 can be less than the thickness of the second region T2. ​​The first region thickness TR1 can also be less than the second region thickness TR2.

[0260] The first gradually rising portion 20A, the first tip portion 21A, the first gently sloping portion 22A, and the first gradually sloping portion 23A of the first region 14 are located in the first layer 8. At least a part of the first gradually sloping portion 23A is located in the base layer 6. That is, the extension portion of the first lower end portion 14a includes the first gradually sloping portion 23A. Of course, a part of the first gently sloping portion 22A may be positioned in the base layer 6 (see Fig. 13E). That is, the extending portion of the first lower end portion 14a may include a part of the first flat gradient portion 22A and the first gradually sloping portion 23A.

[0261] Fig. 22 shows an example in which the first layer 8 has a first thickness T1 of 3 µm and the first region 14 is formed in the first layer 8 with an implantation energy of 960 KeV. Of course, the first region 14 can be formed with an implantation energy of not less than 960 KeV. The first thickness T1 can, for example, be more than 3 µm and at most 5 µm. In this case, the first regions 14, which are partially positioned in the base layer 6, are formed with an implantation energy of at least 960 KeV (see also Fig. 13F to 13E).

[0262] Fig. 23 is a perspective cross-sectional view showing the column portion 12 according to the fifth configuration example. Fig. 24 is a diagram showing an example of a concentration gradient of the Fig. 23 shows the column area 12. As shown in Fig. 23 and Fig. As shown in FIG. 24, the column portion 12 according to the fifth configuration example has a shape obtained by modifying the first portion 14 according to the fourth configuration example. The second portion 15 according to the fifth configuration example has a shape identical to the shape of the second portion 15 according to the second configuration example. Of course, the second portion 15 according to the fifth configuration example has a shape identical to the shape of the second portion 15 according to the third configuration example.

[0263] In the fourth configuration example, the first layer 8 has a first thickness T1 of 3 µm, and the first region 14 is formed in the first layer 8 with an implantation energy of not less than 960 KeV. On the other hand, in the fifth configuration example, the first layer 8 has a first thickness T1 of less than 3 µm, and the first region 14 is formed in the first layer 8 with an implantation energy of not less than 650 KeV. In this example, the first region thickness TR1 of the first region 14 is greater than the first thickness T1. In this example, the first thickness T1 is less than the second thickness T2 of the second layer 9.

[0264] The first thickness T1 may, for example, be not less than 1 µm and not more than 2 µm. In this case, the first region 14, which is partially located in the base layer 6, is formed with an implantation energy of not less than 190 KeV (see also Fig. 11A to 11E). The first thickness T1 may, for example, be not less than 2 µm and less than 3 µm. In this case, the first region 14, which is partially located in the base layer 6, is formed with an implantation energy of not less than 380 KeV (see also Fig. 13B to 13E).

[0265] Fig. 25 is a perspective cross-sectional view showing the column portion 12 according to the sixth configuration example. Fig. 26 is a diagram showing an example of a concentration gradient of the Fig. 25 shows the column area 12. As shown in Fig. 25 and Fig. 26, the pillar region 12 has, in addition to the first region 14 and the second region 15, a p-type intermediate region 25 disposed between the first region 14 and the second region 15.

[0266] Of course, the first region 14 may have a shape identical to any of the shapes of the first regions 14 according to the first to fifth configuration examples. In this example, the first region 14 has a shape identical to the shape of the first region 14 according to the fourth configuration example. The second region 15 may have a shape identical to any of the shapes of the second regions 15 according to the first to fifth configuration examples. The second region 15 has a shape identical to the shape of the second region 15 according to the fourth configuration example (the second configuration example).

[0267] A plurality of intermediate regions 25 are formed in a surface layer portion of the upper end side of the first layer 8 so as to be positioned at least in a plurality of intersection areas between the plurality of first regions 14 and the plurality of second regions 15, and to overlap the corresponding first regions 14 and the corresponding second regions 15 in the lamination direction, respectively. In this embodiment, the plurality of intermediate regions 25 are arranged at intervals in the first arrangement direction Da1 so as to overlap the plurality of first regions 14 in the lamination direction in a one-to-one correspondence, and are each formed as a band extending in the first extension direction De1.

[0268] In this embodiment, the first arrangement direction Da1 is the a-axis direction (the first direction X), and the first extension direction De1 is the m-axis direction (the second direction Y). Of course, an arrangement direction and an extension direction of the plurality of intermediate regions 25 can be changed in accordance with the first arrangement direction Da1 and the first extension direction De1 of the plurality of first regions 14. Therefore, the first arrangement direction Da1 may be the m-axis direction, and the first extension direction De1 may be the a-axis direction. Furthermore, the first arrangement direction Da1 may be a direction other than the a-axis direction and the m-axis direction, and the first extension direction De1 may be a direction other than the a-axis direction and the m-axis direction.

[0269] The plurality of intermediate regions 25, together with the plurality of first regions 14, are guided from the active region 10 into the outer peripheral region 11. That is, the plurality of intermediate regions 25 are guided from a portion of the first layer 8 located in the active region 10 to a portion of the first layer 8 located in the outer peripheral region 11. The plurality of intermediate regions 25 are also arranged at intervals in the first arrangement direction Da1 in the outer peripheral region 11 and are each formed as a band extending in the first extension direction De1.

[0270] Furthermore, the plurality of intermediate regions 25 extend from the outer peripheral region 11 toward one or both (in this embodiment, both) of the first side surface 5A and the third side surface 5C, and each has portions exposed from one or both (in this embodiment, both) of the first side surface 5A and the third side surface 5C.

[0271] The portions of the plurality of intermediate regions 25 exposed from the first side surface 5A constitute the plurality of first marks Mk1 in the first side surface 5A, and the portions of the plurality of intermediate regions 25 exposed from the third side surface 5C constitute the plurality of first marks Mk1 in the third side surface 5C. That is, each of the plurality of intermediate regions 25 includes one or both of the part (the upper end portion) of each of the plurality of first marks Mk1 as a portion exposed from the first side surface 5A and the part (the upper end portion) of each of the plurality of first marks Mk1 as a portion exposed from the third side surface 5C.

[0272] In other words, the plurality of first marks Mk1 are formed using the plurality of first regions 14 and the plurality of intermediate regions 25, respectively. That is, the layout (the exposed positions or the arrangement direction) of the plurality of first marks Mk1 with respect to the first side surface 5A (the third side surface 5C) is adjusted accordingly by the layout (the first arrangement direction Da1 or the first extension direction De1) of the plurality of first regions 14 and the plurality of intermediate regions 25.

[0273] The plurality of first markings Mk1 are not necessarily formed continuously from main body portions of the plurality of intermediate regions 25 and may be formed as separate portions separated from the main body portions of the plurality of intermediate regions 25. In this case, the plurality of first markings Mk1 are preferably separated from the main body portions of the plurality of intermediate regions 25 in the outer peripheral region 11.

[0274] It goes without saying that each of the plurality of intermediate regions 25 does not necessarily form a part (the upper end portion) of each of the plurality of first marks Mk1. That is, the plurality of intermediate regions 25 may be formed in an inner portion of the first layer 8 at intervals from the first to fourth side surfaces 5A to 5D in plan view. The description for the intermediate regions 25 also applies to the first marks Mk1 (portions of the intermediate regions 25 exposed from the first side surface 5A / the third side surface 5C).

[0275] The plurality of intermediate regions 25 are formed in a region between the upper end of the first layer 8 and the first upper end portion 14b of the first region 14 in the first layer 8. The plurality of intermediate regions 25 are preferably arranged on the upper end side of the first layer 8 with respect to the middle thickness range of the first layer 8. The plurality of intermediate regions 25 may be exposed from the upper end of the first layer 8 or formed at intervals from the upper end to the lower end side of the first layer 8. Each of the intermediate regions 25 may be formed in a laterally elongated, columnar shape extending in the horizontal direction in cross-sectional view. Of course, each of the intermediate regions 25 may be formed in the shape of a vertically elongated column extending in the vertical direction Z.

[0276] The plurality of intermediate regions 25, together with the first layer 8, form a plurality of charge-balanced pn junction intermediate regions. That is, the plurality of intermediate regions 25 form part of the first super junction structure SJ1 with the plurality of first drift regions 16. The charge-balanced state means a state in which, with respect to the plurality of adjacent intermediate regions 25, a depletion layer extending from one pn junction intermediate region and a depletion layer extending from the other pn junction intermediate region are connected in the plurality of first drift regions 16.

[0277] As in Fig. 26, each of the intermediate regions 25 may comprise a single or a plurality of region elements 25a. Fig. 26 shows an example in which each of the intermediate regions 25 includes a plurality of (two) region elements 25a. In a case where each of the intermediate regions 25 is formed of a single region element 25a, the single region element 25a is formed in a region between the upper end of the first layer 8 and the first upper end portion 14b of the first region 14 and is connected to the first upper end portion 14b of the first region 14.

[0278] In a case where each of the intermediate regions 25 is formed from a plurality of region elements 25a, the plurality of region elements 25a are each formed at different depth positions in a region between the upper end of the first layer 8 and the first upper end portion 14b of the first region 14. In this case, the plurality of region elements 25a are each shaped to be connected to each other in the lamination direction. Furthermore, at least the lowermost region element 25a is connected to the first upper end portion 14b of the first region 14.

[0279] The region element 25a is formed of an irregular impurity region introduced into the surface layer portion of the first layer 8 by the random implantation method with respect to the first layer 8 (see also Fig. 14). That is, the region element 25a is not formed in the second layer 9. Furthermore, the region element 25a has a smaller thickness than the first region thickness TR1 of the first region 14 in a direction along the first axis channel CH1. Furthermore, the thickness of the region element 25a is smaller than the second region thickness TR2 of the second region 15.

[0280] Unlike the first region 14, etc., the region element 25a does not have the shallow gradient portion 22 with a thickness of not less than 0.5 μm, and has a concentration gradient including the gradually rising portion 20, the peak portion 21, and the gradually falling portion 23 within a range of 0.5 μm. When each of the intermediate regions 25 has a plurality of region elements 25a, each of the intermediate regions 25 has a plurality of peak portions 21 (peak values ​​P) corresponding to the number of the plurality of region elements 25a in the thickness direction of the first layer 8.

[0281] The region element 25a may have a p-type impurity concentration of not less than 1 × 10 15 cm -3 and not more than 1 × 10 18 cm -3 as peak value P. Fig. Fig. 26 shows an example in which the peak value P of the p-type impurity concentration of the region element 25a is not less than 1 × 10 16 cm -3 and not more than 1 × 10 17 cm -3 amounts.

[0282] The p-type impurity concentration of the intermediate region 25 is preferably adjusted by at least one type of trivalent element. The trivalent element of the intermediate region 25 may be the same type as the trivalent element of the first region 14, etc., or it may be a different type than the trivalent element of the first region 14, etc. The trivalent element of the intermediate region 25 may be at least one of boron, aluminum, gallium, and indium.

[0283] Each of the plurality of intermediate regions 25 has an intermediate width WM. The intermediate width WM is a width along the first arrangement direction Da1. The intermediate width WM is preferably less than the first thickness T1 of the first layer 8. Of course, the intermediate width WM cannot be less than the first thickness T1. The intermediate width WM is preferably less than the second thickness T2 of the second layer 9. Of course, the intermediate width WM cannot be less than the second thickness T2 either.

[0284] The intermediate width WM is preferably substantially equal to the first width W1 of the first region 14. Of course, the intermediate width WM may be no less than the first width W1, or it may be less than the first width W1. The intermediate width WM is preferably no less than 1 µm. The intermediate width WM is preferably no more than 5 µm.

[0285] The intermediate width WM can have a value that falls within one of the following ranges: not less than 1 µm and not more than 1.5 µm, not less than 1.5 µm and not more than 2 µm, not less than 2 µm and not more than 2.5 µm, not less than 2.5 µm and not more than 3 µm, not less than 3 µm and not more than 3.5 µm, not less than 3.5 µm and not more than 4 µm, not less than 4 µm and not more than 4.5 µm, and not less than 4.5 µm and not more than 5 µm.

[0286] Each of the plurality of intermediate regions 25 has an intermediate thickness TM. The intermediate thickness TM is preferably not less than a distance between the upper end of the first layer 8 and the first upper end portion 14b of the first region 14. The intermediate thickness TM may be not less than 0.1 µm and not more than 2 µm. The intermediate thickness TM may have a value that falls within any of the ranges of not less than 0.1 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 1 µm, not less than 1 µm and not more than 1.5 µm, and not less than 1.5 µm and not more than 2 µm.

[0287] The plurality of intermediate regions 25 are formed at intervals with an intermediate pitch PM in the first arrangement direction Da1. The intermediate pitch PM is preferably substantially equal to the first pitch P1 of the first region 14. Of course, the intermediate pitch PM may not be smaller than the first pitch P1 or may be smaller than the first pitch P1. Fig. 25 shows the intermediate pitch PM larger than the first pitch P1.

[0288] The intermediate pitch PM cannot be less than 0.1 µm and not more than 5 µm. The intermediate pitch PM can have a value that falls within one of the following ranges: not less than 0.1 µm and not more than 0.25 µm, not less than 0.25 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 0.75 µm, not less than 0.75 µm and not more than 1 µm, not less than 1 µm and not more than 1.5 µm, not less than 1.5 µm and not more than 2 µm, not less than 2 µm and not more than 2.5 µm, not less than 2.5 µm and not more than 3 µm, not less than 3 µm and not more than 3.5 µm, not less than 3.5 µm and not more than 4 µm, not less than 4 µm and not more than 4.5 µm, and not less than 4.5 µm and not more than 5 µm. The intermediate pitch PM is preferably not less than 0.5 µm and not more than 1.5 µm.

[0289] In such a configuration, it is advantageous for the second region 15 to have an extension section positioned in the first layer 8 and connected to the intermediate region 25 in the first layer 8. This means that the second region 15 is preferably electrically connected to the first region 14 via the intermediate region 25 in the first layer 8. In this case, the second region 15, together with the first region 14 and the intermediate region 25, forms the single drift region 13 extending continuously in the lamination direction.

[0290] Of course, the extension portion of the second region 15 may be connected to both the intermediate region 25 and the first region 14 in the first layer 8. In this configuration, in which the intermediate region 25 is provided, a concentration gradient in a region between the first region 14 and the second region 15 is mitigated by the intermediate region 25, and the accuracy of charge balancing is improved.

[0291] Fig. 27 is a perspective cross-sectional view showing the column portion 12 according to the seventh configuration example. Fig. 28 is a diagram showing an example of a concentration gradient of the Fig. 27 shows the column area 12. As shown in Fig. 27 and Fig. As shown in FIG. 28, the column portion 12 according to the seventh configuration example has a shape obtained by modifying the first portions 14 according to the first to sixth configuration examples. The second portion 15 according to the seventh configuration example may have a shape identical to any of the shapes of the second portions 15 according to the first to sixth configuration examples.

[0292] In this example, the first region 14 is exposed from the top of the first layer 8. The first region 14 does not include all or part of the first gradually rising section 20A. Fig. 28 shows an example in which the first region 14 does not include all of the first gradually rising portion 20A and the first peak portion 21A. That is, in this example, the first upper end portion 14b includes the first shallow gradient portion 22A exposed from the upper end of the first layer 8.

[0293] The first region 14 has the first peak value PA at the upper end of the first layer 8 and has a concentration gradient that gradually decreases toward the lower end of the first layer 8. Of course, the first upper end portion 14b may include a part of the first gradually rising portion 20A or a part of the first peak portion 21A, and the part of the first gradually rising portion 20A or the part of the first peak portion 21A may be exposed from the upper end of the first layer 8.

[0294] In this configuration, it is advantageous that the second region 15 has an extension portion positioned in the first layer 8 and connected to the first region 14 in the first layer 8. In this configuration, in which the first region 14 is exposed at the upper end of the first layer 8, the exposed portion of the first region 14 flattens a concentration gradient in the region between the first region 14 and the second region 15, thereby improving the accuracy of charge balancing.

[0295] Such a configuration is achieved by partially removing the upper end of the first layer 8 after the formation of the first regions 14, until the partial or entire first gradually rising portion 20A of the first region 14 disappears. For example, the upper end of the first layer 8 can be partially removed by a grinding process. The grinding process can be a mechanical polishing process and / or a chemomechanical polishing process. In this case, the upper end of the first layer 8 is formed from a ground surface, and the first region 14 is exposed from this ground surface. The second layer 9 is laminated onto the ground surface of the first layer 8.

[0296] For example, the upper end of the first layer 8 can be partially removed by an etching process. The etching process can be a wet etching process and / or a dry etching process. In this case, the upper end of the first layer 8 is formed from an etched surface, and the first region 14 is exposed from this etched surface. The second layer 9 is laminated onto the etched surface of the first layer 8.

[0297] Fig. 29 is a perspective cross-sectional view showing the column portion 12 according to the eighth configuration example. Fig. 30 is a diagram showing an example of a concentration gradient of the Fig. 29 shows the column area 12. With reference to the Fig. 29 and Fig. 30, the column portion 12 according to the eighth configuration example has a shape obtained by modifying the second portions 15 according to the first to seventh configuration examples. The first portion 14 according to the eighth configuration example may have a shape identical to any of the shapes of the first portions 14 according to the first to seventh configuration examples. Fig. 29 and Fig. 30 show the first area 14 according to the seventh configuration example.

[0298] In this example, the second region 15 is exposed from the upper end (the first main surface 3) of the second layer 9. The second region 15 does not include all or part of the second gradually rising portion 20B. Fig. 30 shows an example in which the second region 15 does not include the entire second gradually rising portion 20B and the second peak portion 21B. That is, in this example, the second upper end portion 15b includes the second shallow gradient portion 22B exposed from the upper end of the second layer 9.

[0299] The second region 15 has the second peak PB at the upper end of the second layer 9 and has a concentration gradient that gradually decreases toward the lower end side of the second layer 9. Of course, the second upper end portion 15b may include a part of the second gradually rising portion 20B or a part of the second peak portion 21B, and the part of the second gradually rising portion 20B or the part of the second peak portion 21B may be exposed from the upper end of the second layer 9.

[0300] A configuration in which the second regions 15 are exposed at the upper end of the second layer 9 is advantageous when a component structure is formed using the second layer 9 (the first main surface 3) and whose electrical properties are adapted via the second regions 15.

[0301] Such a configuration is achieved by partially removing the upper end of the second layer 9 after the formation of the second regions 15, until the partial or entire second gradually rising portion 20B of the second region 15 disappears. For example, the upper end (the first main surface 3) of the second layer 9 can be partially removed by a grinding process. The grinding process can be a mechanical polishing process and / or a chemical-mechanical polishing process. In this case, the upper end of the second layer 9 is formed from a ground surface, and the second region 15 is exposed from this ground surface.

[0302] For example, the upper end (the first main surface 3) of the second layer 9 can be partially removed by an etching process. The etching process can be a wet etching process and / or a dry etching process. In this case, the upper end of the second layer 9 is formed from an etched surface, and the second region 15 is exposed from this etched surface.

[0303] Fig. 31 is a perspective cross-sectional view showing the column portion 12 according to the ninth configuration example. Fig. 32 is a perspective cross-sectional view showing the column portion 12 according to the tenth configuration example. As shown in Fig. 31 and Fig. 32, the laminated portion 7 may have a laminated structure including a buffer layer 26, the first layer 8, and the second layer 9 laminated in this order from the side of the base layer 6. The buffer layer 26 may be referred to as a "buffer SiC layer," a "buffer region," etc.

[0304] The buffer layer 26 comprises a SiC single crystal and has an n-type conductivity. The buffer layer 26 is laminated on the base layer 6. The buffer layer 26 extends in a layered manner in the horizontal direction and forms an intermediate portion of the chip 2 and a part of each of the first to fourth side surfaces 5A to 5D. The buffer layer 26 may be formed from an epitaxial layer (ie, an SiC epitaxial layer) crystal-grown with the base layer 6 as a starting point.

[0305] The buffer layer 26 has a lower end and an upper end. The lower end of the buffer layer 26 is a starting point for crystal growth, and the upper end of the buffer layer 26 is an end point for crystal growth. Since the buffer layer 26 is continuously crystal-grown from the base layer 6, the lower end of the buffer layer 26 is aligned with an upper end of the base layer 6. A boundary portion between the base layer 6 and the buffer layer 26 is not necessarily visible and can be indirectly evaluated and / or determined based on other configurations or elements. The buffer layer 26 has the deviation direction Doff and the deviation angle θoff that substantially coincide with the deviation direction Doff and the deviation angle θoff of the base layer 6.

[0306] The buffer layer 26 has a buffer axis channel CHBu aligned along the lamination direction. The buffer axis channel CHBu is formed from regions (channels) that have a comparatively large interatomic distance (atomic interval) in the SiC single crystal forming the buffer layer 26 and are surrounded by atomic rows that form a crystal axis extending in the lamination direction (crystal growth direction).

[0307] This means that the buffer axis channel CHBu is composed of regions where the atomic rows are sparse, extending in the lamination direction and, in plan view, forming regions where the atomic rows (interatomic distance / atomic density) are sparse in the horizontal direction. The buffer axis channel CHBu is preferably formed from regions surrounded by atomic rows aligned along a low-index crystal axis below the crystal axes.

[0308] In this embodiment, the buffer axis channel CHBu is formed from the regions surrounded by atomic rows aligned along the c-axis of the SiC single crystal. That is, the buffer axis channel CHBu runs along the c-axis and has the deviation direction Doff and the deviation angle θoff. In other words, the buffer axis channel CHBu is tilted by the deviation angle θoff from the vertical axis in the deviation direction Doff.

[0309] The n-type impurity concentration of the buffer layer 26 is preferably lower than the n-type impurity concentration of the base layer 6. The buffer layer 26 may have an n-type impurity concentration of not less than 1 × 10 15 cm -3 and not more than 1 × 10 18 cm -3as a peak value. The n-type impurity concentration of the buffer layer 26 may be substantially constant in the thickness direction. Of course, the n-type impurity concentration of the buffer layer 26 may have a concentration gradient that gradually increases and / or gradually decreases in the lamination direction (crystal growth direction).

[0310] Buffer layer 26 has an n-type impurity concentration that is adjusted by at least one type of pentavalent element. For example, the n-type impurity concentration in buffer layer 26 can be adjusted by at least one of the elements nitrogen, phosphorus, arsenic, antimony, and bismuth. Buffer layer 26 preferably comprises a pentavalent element other than phosphorus.

[0311] The n-type impurity concentration of the buffer layer 26 is preferably adjusted by at least nitrogen. When the buffer layer 26 contains two or more types of pentavalent elements, the buffer layer 26 preferably includes nitrogen and a pentavalent element other than nitrogen. In this case, the buffer layer 26 preferably includes one or both of arsenic and antimony as a pentavalent element other than phosphorus and nitrogen.

[0312] The buffer layer 26 has a buffer thickness TBu. The buffer thickness TBu is preferably less than the base thickness TB. The buffer thickness TBu is preferably not less than 1 µm. The buffer thickness TBu is preferably not more than 5 µm. The buffer thickness TBu can have a value that falls within one of the following ranges: not less than 1 µm and not more than 1.5 µm, not less than 1.5 µm and not more than 2 µm, not less than 2 µm and not more than 2.5 µm, not less than 2.5 µm and not more than 3 µm, not less than 3 µm and not more than 3.5 µm, not less than 3.5 µm and not more than 4 µm, not less than 4 µm and not more than 4.5 µm, and not less than 4.5 µm and not more than 5 µm.

[0313] In this embodiment, the first layer 8 is laminated on the buffer layer 26, and the second layer 9 is laminated on the first layer 8. The first layer 8 is formed from an epitaxial layer (i.e., a SiC epitaxial layer) crystal-grown with the buffer layer 26 as a starting point and having an n-type conductivity type. Therefore, the first layer 8 has a deviation direction Doff and a deviation angle θoff that substantially coincide with the deviation direction Doff and the deviation angle θoff of the buffer layer 26. Furthermore, the first axis channel CH1 is substantially aligned with the buffer axis channel CHBu.

[0314] The first thickness T1 of the first layer 8 is preferably greater than the buffer thickness TBu. Of course, the first thickness T1 can be less than the buffer thickness TBu. Furthermore, the first thickness T1 can be substantially equal to the buffer thickness TBu. The second thickness T2 of the second layer 9 is preferably greater than the buffer thickness TBu. Of course, the second thickness T2 can be less than the buffer thickness TBu. Furthermore, the second thickness T2 can be substantially equal to the buffer thickness TBu.

[0315] The first region 14 has a shape identical to each of the shapes of the first regions 14 according to the first to eighth configuration examples and is formed in the first layer 8. The second region 15 has a shape identical to each of the shapes of the first regions 14 according to the first to eighth configuration examples and is formed in the second layer 9.

[0316] As in Fig. 31, the first lower end portion 14a of the first region 14 may be formed at an interval from the lower end to the upper end side of the first layer 8, and may oppose the buffer layer 26 via a part (the lower end portion) of the first layer 8. That is, the entire first region 14 (the first gradually rising portion 20A, the first peak portion 21A, the first gently sloping portion 22A, and the first gradually falling portion 23A) may be disposed in the first layer 8. Of course, the first lower end portion 14a may substantially coincide with the lower end of the first layer 8 and be connected to the buffer layer 26.

[0317] As in Fig. 32, the first lower end portion 14a may have an extension portion that crosses a boundary portion between the buffer layer 26 and the first layer 8 and may be positioned in the buffer layer 26. Since the first axis channel CH1 substantially coincides with the buffer axis channel CHBu, the extension portion of the first lower end portion 14a is formed along the buffer axis channel CHBu in the buffer layer 26.

[0318] The extension portion of the first lower end portion 14a is preferably located on the upper end side of the buffer layer 26 with respect to a central thickness range of the buffer layer 26. The extension portion of the first lower end portion 14a includes the first gradually sloping portion 23A. Of course, the extension portion of the first lower end portion 14a may include a part of the first shallow gradient portion 22A and the first gradually sloping portion 23A.

[0319] Fig. 33 is a perspective cross-sectional view showing the pillar portion 12 according to the eleventh configuration example. In the above-described embodiment, the descriptions assumed that the super junction structure SJ has a laminated structure of three or more layers. Fig. 33 shows, as an example, the laminated portion 7 having a three-layer structure and the column portion 12 having a three-layer structure.

[0320] Specifically, the laminated portion 7 includes a third n-type SiC single crystal layer 27 laminated on the second layer 9. The third layer 27 may be referred to as a “third SiC layer,” a “third semiconductor layer,” etc. The second layer 9 forms, for example, the intermediate portion of the chip 2 and a part of each of the first to fourth side surfaces 5A to 5D. The third layer 27 extends in a layered manner in the horizontal direction and forms the first main surface 3 and a part of each of the first to fourth side surfaces 5A to 5D. The third layer 27 is formed of an epitaxial layer (i.e., a SiC epitaxial layer) crystal-grown (crystallized) with the second layer 9 as a starting point.

[0321] The third layer 27 has a lower end and an upper end. The lower end of the third layer 27 is a starting point for crystal growth, and the upper end of the third layer 27 is an end point for crystal growth. Since the third layer 27 is continuously crystal-grown from the second layer 9, the lower end of the third layer 27 is aligned with the upper end of the second layer 9. A boundary portion between the second layer 9 and the third layer 27 is not necessarily visible and can be indirectly evaluated and / or determined based on other configurations or elements. The third layer 27 has the deviation direction Doff and the deviation angle θoff that are substantially the same as the deviation direction Doff and the deviation angle θoff of the second layer 9.

[0322] The third layer 27 has a third axial channel CH3 aligned along the lamination direction. The third axial channel CH3 is formed from regions (channels) that have a comparatively large interatomic distance (atomic interval) in the SiC single crystal forming the third layer 27 and are surrounded by atomic rows that form a crystal axis extending in the lamination direction (crystal growth direction).

[0323] That is, the third axis channel CH3 is composed of regions where the atomic rows are sparse, extending in the lamination direction and, in plan view, forming regions where the atomic rows (interatomic distance / atomic density) are sparse in the horizontal direction. The third axis channel CH3 is preferably formed from regions surrounded by atomic rows aligned along a low-index crystal axis among the crystal axes.

[0324] In this embodiment, the third-axis channel CH3 is formed from the regions surrounded by atomic rows aligned along the c-axis of the SiC single crystal. That is, the third-axis channel CH3 runs along the c-axis and has the deviation direction Doff and the deviation angle θoff. In other words, the third-axis channel CH3 is inclined by the deviation angle θoff from the vertical axis in the deviation direction Doff.

[0325] The n-type impurity concentration of the third layer 27 is preferably lower than the n-type impurity concentration of the base layer 6. The third layer 27 may have an n-type impurity concentration of not less than 1 × 10 15 cm -3 and not more than 1 × 10 18 cm -3as a peak value. The n-type impurity concentration of the third layer 27 may be substantially constant in the thickness direction. Of course, the n-type impurity concentration of the third layer 27 may have a concentration gradient that gradually increases and / or gradually decreases in the lamination direction (crystal growth direction).

[0326] The third layer 27 has an n-type impurity concentration adjusted by at least one type of pentavalent element. For example, the n-type impurity concentration in the third layer 27 can be adjusted by at least one of the elements nitrogen, phosphorus, arsenic, antimony, and bismuth. The third layer 27 preferably comprises a pentavalent element other than phosphorus.

[0327] The n-type impurity concentration of the third layer 27 is preferably adjusted by at least nitrogen. When the third layer 27 contains two or more types of pentavalent elements, the third layer 27 preferably includes nitrogen and a pentavalent element other than nitrogen. In this case, the third layer 27 preferably includes one or both of arsenic and antimony as a pentavalent element other than phosphorus and nitrogen.

[0328] The third layer 27 has a third thickness T3. The third thickness T3 is preferably less than the base thickness TB. The third thickness T3 may be substantially equal to the second thickness T2, it may be not less than the second thickness T2, or it may be less than the second thickness T2. The third thickness T3 may be substantially equal to the first thickness T1, it may be not less than the first thickness T1, or it may be less than the first thickness T1.

[0329] The third thickness T3 is preferably not less than 1 µm. The third thickness T3 is preferably not more than 5 µm. The third thickness T3 may have a value that falls within any of the following ranges: not less than 1 µm and not more than 1.5 µm, not less than 1.5 µm and not more than 2 µm, not less than 2 µm and not more than 2.5 µm, not less than 2.5 µm and not more than 3 µm, not less than 3 µm and not more than 3.5 µm, not less than 3.5 µm and not more than 4 µm, not less than 4 µm and not more than 4.5 µm, and not less than 4.5 µm and not more than 5 µm.

[0330] The pillar region 12 includes a third region 28 formed in the third layer 27. A plurality of third regions 28 are formed at intervals in the horizontal direction in the third layer 27 and define a plurality of third n-type drift regions 29, each formed from a portion of the third layer 27. The plurality of third regions 28, together with the plurality of third drift regions 29, form a plurality of third charge-balanced pn junction regions.

[0331] That is, the plurality of third regions 28 form a third super junction structure SJ3 with the third layer 27. The charge-balanced state means a state in which, with respect to the plurality of third regions 28 adjacent to each other, a depletion layer extending from one third pn junction region and a depletion layer extending from the other third pn junction region are connected in the plurality of third drift regions 29.

[0332] The plurality of third regions 28 are formed in the third layer 27 so as to overlap the plurality of second regions 15 in the lamination direction. Specifically, the plurality of third regions 28 are arranged at intervals in a third arrangement direction Da3 different from the second arrangement direction Da2 in the third layer 27, and are each formed as a band extending in a third extension direction De3 different from the second extension direction De2. That is, the plurality of third regions 28 are formed as stripes extending in the third extension direction De3, and the plurality of third drift regions 29 are formed as stripes extending in the third extension direction De3.

[0333] The plurality of third regions 28 intersect the plurality of second regions 15 in plan view. Therefore, the plurality of third drift regions 29 are connected to the plurality of second drift regions 17 at the boundary between the second layer 9 and the third layer 27, and together with the plurality of first drift regions 16 and the plurality of second drift regions 17, form the single drift region 13 in a three-dimensional lattice shape. The plurality of third drift regions 29, together with the plurality of first drift regions 16 and the plurality of second drift regions 17, form three-dimensional lattice-shaped current paths extending in the lamination direction.

[0334] The third arrangement direction Da3 may be aligned with the first arrangement direction Da1. Furthermore, the third extension direction De3 may be aligned with the first extension direction De1. This means that the plurality of third regions 28 may extend in the same direction as the plurality of first regions 14 in plan view. In this case, the plurality of third regions 28 may be opposite the plurality of first regions 14 in a one-to-one correspondence in the lamination direction.

[0335] Of course, the plurality of third regions 28 can be arranged offset from the plurality of first regions 14 in the first arrangement direction Da1 and can be opposite one or both of the first regions 14 and the first drift region 16 in the lamination direction. Of course, the third arrangement direction Da3 can differ from the first arrangement direction Da1. The third extension direction De3 can also differ from the first extension direction De1. This means that the plurality of third regions 28 can intersect the plurality of first regions 14 in plan view (e.g., be orthogonal thereto).

[0336] In this embodiment, the first impurity region 28 is led out of the active region 10 into the outer peripheral region 11. That is, the plurality of second regions 28 are led from a portion of the second layer 27 located in the active region 10 to a portion of the second layer 27 located in the outer peripheral region 11. The plurality of third regions 28 are also arranged in the outer peripheral region 11 at intervals in the third arrangement direction Da3 and are each formed as a band extending in the third extension direction De3.

[0337] Furthermore, the plurality of third regions 28 extend from the outer peripheral region 11 toward one or both (in this embodiment, both) of the first side surface 5A and the third side surface 5C, and each has portions exposed from one or both (in this embodiment, both) of the first side surface 5A and the third side surface 5C.

[0338] The portions of the plurality of third regions 28 exposed from the first side surface 5A form the plurality of third marks (not shown) in the first side surface 5A, and the portions of the plurality of third regions 28 exposed from the third side surface 5C form the plurality of third marks in the third side surface 5C. That is, the plurality of third regions 28 include one or both of the plurality of third marks as exposed portions exposed from the first side surface 5A and the plurality of third marks as exposed portions exposed from the third side surface 5C.

[0339] In other words, each of the plurality of third marks is formed using a part (an exposed portion) of each of the plurality of third regions 28. The plurality of third marks define a plurality of third spaces in the first side surface 5A (the third side surface 5C). The plurality of third marks and the plurality of third spaces are formed in the first side surface 5A (the third side surface 5C) in a layout identical to that of the plurality of first marks Mk1 and the plurality of first spaces Sp1.

[0340] Therefore, the description of the plurality of first markings Mk1 (the plurality of first spaces Sp1) can be applied to the description of the plurality of third markings (the plurality of third spaces). The layout (the exposed locations or the arrangement direction) of the plurality of third markings with respect to the first side surface 5A (the third side surface 5C) is adjusted accordingly by the layout (the third arrangement direction Da3 or the third extension direction De3) of the plurality of third regions 28.

[0341] The plurality of third markings are not necessarily formed continuously from the main body portions of the plurality of third regions 28 and may be formed as separate portions separated from the main body portions of the plurality of third regions 28. In this case, the plurality of third markings are preferably separated from the main body portions of the plurality of third regions 28 in the outer peripheral region 11. The description for the third regions 28 also applies to the third markings (portions of the third regions 28 exposed from the first side surface 5A / the third side surface 5C).

[0342] The plurality of third regions 28 are formed from channeling regions (third channeling regions) extending along the third axis channel CH3 in the third layer 27 in the cross-sectional view. That is, the third region 28 is an impurity region introduced parallel or substantially parallel to the regions (the third axis channel CH3) surrounded by atomic rows aligned along the low-index crystal axis in the third layer 27, and extending inclined with respect to the first main surface 3.

[0343] Each of the plurality of third regions 28 has a third lower end portion 28a at a lower end side of the third layer 27 and a third upper end portion 28b at an upper end side of the third layer 27. The third lower end portion 28a is located in a region at the lower end side of the third layer 27 with respect to a middle thickness range of the third layer 27, and the third upper end portion 28b is located in a region at the upper end side of the third layer 27 with respect to the middle thickness range of the third layer 27. That is, the plurality of third regions 28 are each formed of a single impurity region having a thickness (a depth) that traverses an intermediate portion of the third layer 27 along the third axis channel CH3.

[0344] The third lower end portion 28a may be formed in an interval between the lower end and the upper end side of the third layer 27 and may oppose the second layer 9 via a part (a lower end portion) of the third layer 27. The third lower end portion 28a may substantially coincide with the lower end of the third layer 27 and be connected to the second layer 9.

[0345] A distance between the lower end of the third layer 27 and the third lower end portion 28a may be not less than 0 µm and not more than 2 µm. The distance between the lower end of the third layer 27 and the third lower end portion 28a may have a value that falls within any of the following ranges: not less than 0 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 1 µm, not less than 1 µm and not more than 1.5 µm, and not less than 1.5 µm and not more than 2 µm.

[0346] The third lower end portion 28a may have an extension portion that crosses the boundary portion between the second layer 9 and the third layer 27 and is located in the second layer 9. In this case, the thickness of the extension portion of the third lower end portion 28a may be more than 0 µm and not more than 2 µm based on the upper end of the second layer 9. The thickness of the extension portion of the third lower end portion 28a may have a value that falls within any one of the following ranges: more than 0 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 1 µm, not less than 1 µm and not more than 1.5 µm, and not less than 1.5 µm and not more than 2 µm.

[0347] The third upper end portion 28b may be formed at an interval from the upper end (ie, the first main surface 3) toward the lower end side of the third layer 27, and may oppose the upper end of the third layer 27 via a part (an upper end portion) of the third layer 27. The third upper end portion 28b may be exposed from the upper end (ie, the first main surface 3) of the third layer 27.

[0348] A distance between the upper end of the third layer 27 and the third upper end portion 28b may be not less than 0 µm and not more than 1 µm. The distance between the upper end of the third layer 27 and the third upper end portion 28b may have a value that falls within any of the following ranges: not less than 0 µm and not more than 0.25 µm, not less than 0.25 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 0.75 µm, and not less than 0.75 µm and not more than 1 µm.

[0349] The plurality of third regions 28 may have a p-type impurity concentration of not less than 1 × 10 15 cm -3 and not more than 1 × 10 18 cm -3as a peak value. The p-type impurity concentration (a peak value) of the third region 28 may not be less than the p-type impurity concentration (the peak value) of the first region 14. The p-type impurity concentration (the peak value) of the third region 28 may be less than the p-type impurity concentration (the peak value) of the first region 14. The p-type impurity concentration (the peak value) of the third region 28 may be substantially equal to the p-type impurity concentration (the peak value) of the first region 14.

[0350] The p-type impurity concentration of the third region 28 is preferably adjusted by at least one type of trivalent element. The p-type impurity concentration of the third region 28 is particularly preferably adjusted by a trivalent element belonging to the heavy elements heavier than carbon. That is, the third region 28 preferably comprises a trivalent element other than boron (at least one of aluminum, gallium, and indium). In this embodiment, the p-type impurity concentration of the third region 28 is adjusted by aluminum.

[0351] Each of the plurality of third regions 28 has a third width W3. The third width W3 is a width along the third arrangement direction Da3. The third width W3 is preferably smaller than the third thickness T3 of the third layer 27. Of course, the third width W3 cannot be smaller than the third thickness T3. The third width W3 is preferably smaller than the first thickness T1 of the first layer 8. Of course, the third width W3 cannot be smaller than the first thickness T1. The third width W3 is preferably smaller than the second thickness T2 of the second layer 9. Of course, the third width W3 cannot be smaller than the second thickness T2.

[0352] Of course, the third width W3 cannot be less than the first width W1 of the first region 14, or it can be less than the first width W1. The third width W3 is preferably substantially equal to the first width W1. Of course, the third width W3 cannot be less than the second width W2 of the second region 15, or it can be less than the second width W2. The third width W3 is preferably substantially equal to the second width W2.

[0353] The third width W3 may not be less than 0.1 µm and not more than 5 µm. The third width W3 may have a value that falls within one of the following ranges: not less than 0.1 µm and not more than 0.25 µm, not less than 0.25 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 0.75 µm, not less than 0.75 µm and not more than 1 µm, not less than 1 µm and not more than 1.5 µm, not less than 1.5 µm and not more than 2 µm, not less than 2 µm and not more than 2.5 µm, not less than 2.5 µm and not more than 3 µm, not less than 3 µm and not more than 3.5 µm, not less than 3.5 µm and not more than 4 µm, not less than 4 µm and not more than 4.5 µm, and not less than 4.5 µm and not more than 5 µm. The third width W3 is preferably not less than 0.5 µm and not more than 1.5 µm.

[0354] Each of the plurality of third regions 28 has a third region thickness TR3. The third region thickness TR3 may be less than the third thickness T3 of the third layer 27. The third region thickness TR3 may be greater than the third thickness T3. The third region thickness TR3 may be substantially equal to the third thickness T3.

[0355] The third region thickness TR3 may be smaller than the first thickness T1 of the first layer 8. The third region thickness TR3 may be greater than the first thickness T1. The third region thickness TR3 may be substantially equal to the first thickness T1. The third region thickness TR3 of the third region may be smaller than the second thickness T2 of the second layer 9. The third region thickness TR3 may be greater than the second thickness T2. The third region thickness TR3 may be substantially equal to the second thickness T2.

[0356] The third region thickness TR3 is preferably not less than 1 µm. The third region thickness TR3 is preferably not more than 5 µm. The third region thickness TR3 may have a value that falls within any of the following ranges: not less than 1 µm and not more than 1.5 µm, not less than 1.5 µm and not more than 2 µm, not less than 2 µm and not more than 2.5 µm, not less than 2.5 µm and not more than 3 µm, not less than 3 µm and not more than 3.5 µm, not less than 3.5 µm and not more than 4 µm, not less than 4 µm and not more than 4.5 µm, and not less than 4.5 µm and not more than 5 µm.

[0357] Preferably, the third width W3 is smaller than the third thickness T3 of the third layer 27, and the third region thickness TR3 is greater than the third width W3. That is, each of the plurality of third regions 28 preferably has a third aspect ratio TR3 / W3 and extends in a vertically long columnar shape along the third axis channel CH3. The third aspect ratio TR3 / W3 is the ratio between the third region thickness TR3 and the third width W3. In this case, the third region thickness TR3 is particularly preferably greater than the third thickness T3. For example, the third aspect ratio TR3 / W3 may be greater than 1 and at most 100.

[0358] The plurality of third regions 28 are formed at intervals of a third pitch P3 in the third arrangement direction Da3. The third pitch P3 is preferably smaller than the third thickness T3 of the third layer 27. Of course, the third pitch P3 cannot be smaller than the third thickness T3. The third pitch P3 is preferably smaller than the first thickness T1 of the first layer 8. Also, the third pitch P3 is preferably smaller than the second thickness T2 of the second layer 9. Of course, the third pitch P3 cannot be smaller than the first thickness T1. Of course, the third pitch P3 cannot be smaller than the second thickness T2.

[0359] The third pitch P3 can be substantially equal to the first pitch P1 or different from the first pitch P1. The third pitch P3 can be greater than the first pitch P1 or less than the first pitch P1. The third pitch P3 can be substantially equal to the second pitch P2 or different from the second pitch P2. The third pitch P3 can be greater than the second pitch P2 or less than the second pitch P2.

[0360] The third pitch P3 cannot be smaller than 0.1 µm and not larger than 5 µm. The third pitch P3 can have a value that falls within one of the following ranges: not less than 0.1 µm and not more than 0.25 µm, not less than 0.25 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 0.75 µm, not less than 0.75 µm and not more than 1 µm, not less than 1 µm and not more than 1.5 µm, not less than 1.5 µm and not more than 2 µm, not less than 2 µm and not more than 2.5 µm, not less than 2.5 µm and not more than 3 µm, not less than 3 µm and not more than 3.5 µm, not less than 3.5 µm and not more than 4 µm, not less than 4 µm and not more than 4.5 µm, and not less than 4.5 µm and not more than 5 µm. The third pitch P3 is preferably not less than 0.5 µm and not more than 1.5 µm.

[0361] In addition, the description of the concentration gradient in the Fig. 13A to 13E are applicable to the description of the concentration gradient of the third region 28. The configurations of the first regions 14 (the first layer 8) or the second regions 15 (the second layer 9) described in the first to twelfth configuration examples are also applicable to the configuration of the third region 28 (the third layer 27).

[0362] Fig. Fig. 34 is a perspective cross-sectional view showing the column portion 12 according to the twelfth configuration example. In this example (see Fig. 34), the laminated portion 7 may include an n-type upper layer 30 formed of the SiC single crystal and laminated on the second layer 9. The upper layer 30 separates the first main surface 3 from the pillar region 12. That is, the upper layer 30 is also a portion that forms at least a part of a region between the first main surface 3 and the second upper end portions 15b of the plurality of second regions 15. The upper layer 30 can be regarded as a portion that forms the upper end portion of the second layer 9.

[0363] In this example, the top layer 30 has an n-type conductivity type, but the conductivity type of the top layer 30 can be adjusted according to the characteristics of the device structure formed on the first main surface 3. Therefore, the conductivity type of the top layer 30 is not necessarily limited to the n-type and may also be the p-type.

[0364] The upper layer 30 is laminated on the second layer 9. The upper layer 30 extends in a layered manner in the horizontal direction and forms the first main surface 3 and a part of each of the first to fourth side surfaces 5A to 5D. The upper layer 30 is formed from an epitaxial layer (ie, a SiC epitaxial layer) on which the second layer 9 is crystal-grown as a starting point.

[0365] Since the upper layer 30 is crystal-grown continuously from the second layer 9, the lower end of the upper layer 30 is aligned with the upper end of the second layer 9. A boundary portion between the upper layer 30 and the second layer 9 is not necessarily visible and can be indirectly evaluated and / or determined based on other configurations or elements. The upper layer 30 has the deviation direction Doff and the deviation angle θoff that substantially coincide with the deviation direction Doff and the deviation angle θoff of the second layer 9.

[0366] The upper layer 30 has an upper axial channel (CHT) aligned along the lamination direction. The upper axial channel (CHT) is formed from regions (channels) that have a comparatively large interatomic distance (atomic interval) in the SiC single crystal that formed the upper layer 30 and are surrounded by atomic rows that form a crystal axis extending in the lamination direction (crystal growth direction).

[0367] That is, the upper axial channel (CHT) is composed of regions where the atomic rows are sparse, extending in the lamination direction and, in plan view, forming regions where the atomic rows (interatomic distance / atomic density) are sparse in the horizontal direction. The upper axial channel (CHT) is preferably formed from regions surrounded by atomic rows aligned along a low-index crystal axis below the crystal axes.

[0368] In this embodiment, the upper axis channel CHT is formed from the regions surrounded by atomic rows aligned along the c-axis of the SiC single crystal. That is, the upper axis channel CHT runs along the c-axis and has the deviation direction Doff and the deviation angle θoff. In other words, the upper axis channel CHT is inclined by the deviation angle θoff from the vertical axis in the deviation direction Doff.

[0369] The n-type impurity concentration of the upper layer 30 is preferably lower than the n-type impurity concentration of the base layer 6. The upper layer 30 may have an n-type impurity concentration of not less than 1 × 10 15 cm -3 and not more than 1 × 10 18 cm -3as a peak value. The n-type impurity concentration of the upper layer 30 may be substantially equal to the n-type impurity concentration of the first layer 8 (the second layer 9). The n-type impurity concentration of the upper layer 30 may be substantially constant in the thickness direction. Of course, the n-type impurity concentration of the upper layer 30 may have a concentration gradient that gradually increases and / or gradually decreases in the lamination direction (crystal growth direction).

[0370] The upper layer 30 has an n-type impurity concentration adjusted by at least one type of pentavalent element. For example, the n-type impurity concentration in the upper layer 30 can be adjusted by at least one of the elements nitrogen, phosphorus, arsenic, antimony, and bismuth. The upper layer 30 preferably comprises a pentavalent element other than phosphorus.

[0371] The n-type impurity concentration of the upper layer 30 is preferably adjusted by at least nitrogen. When the upper layer 30 contains two or more types of pentavalent elements, the upper layer 30 preferably includes nitrogen and a pentavalent element other than nitrogen. In this case, the upper layer 30 preferably includes one or both of arsenic and antimony as a pentavalent element other than phosphorus and nitrogen.

[0372] The upper layer 30 has an upper thickness TT. The upper thickness TT is preferably smaller than the lower thickness TB. The upper thickness TT is preferably smaller than the first thickness T1 (the second thickness T2). Of course, the upper thickness TT may also be no smaller than the first thickness T1 (the second thickness T2).

[0373] The upper thickness TT may not be less than 0.1 µm and not more than 5 µm. The upper thickness TT may have a value falling within any of the following ranges: not less than 0.1 µm and not more than 0.25 µm, not less than 0.25 µm and not more than 0.5 µm, not less than 0.5 µm and not more than 0.75 µm, not less than 0.75 µm and not more than 1 µm, not less than 1 µm and not more than 1.5 µm, not less than 1.5 µm and not more than 2 µm, not less than 2 µm and not more than 2.5 µm, not less than 2.5 µm and not more than 3 µm, not less than 3 µm and not more than 3.5 µm, not less than 3.5 µm and not more than 4 µm, not less than 4 µm and not more than 4.5 µm, and not less than 4.5 µm and not more than 5 µm.

[0374] A configuration example for a component structure formed in the active region 10 is described below. Fig. 35 is a plan view showing a main portion of the active region 10. Fig. 36 is a perspective cross-sectional view showing the gate structure 35 according to a first configuration example. Fig. 36 shows a configuration in which the column portion 12 according to the second configuration example is applied to the column portion 12 according to the first basic shape. Of course, in Fig. 36, a configuration may be applied in which any one or the plurality of columnar portions 12 according to the first to twelfth configuration examples are applied to any one of the columnar portions 12 according to the first to third basic shapes.

[0375] As in Fig. 35 and Fig. As shown in Figure 36, the SiC semiconductor device 1A in this embodiment includes an MIS (metal-insulator-semiconductor) structure 31 as an example of the device structure formed in the active region 10. The MIS structure 31 may be referred to as a "field-effect transistor structure."

[0376] Here, an example in which the MIS structure 31 is formed on the second layer 9 (the first main surface 3) will be described. In a case where the above-described upper layer 30 is formed, the MIS structure 31 is formed on the upper layer 30 (the first main surface 3). The corresponding embodiment in this case is obtained by replacing the "second layer 9" with the "upper layer 30" in the following description. Although the following configurations are described as components of the SiC semiconductor device 1A, the configurations are also components of the MIS structure 31.

[0377] The SiC semiconductor device 1A includes a plurality of p-type body regions 32 formed in the active region 10. The plurality of body regions 32 are formed in a surface layer portion of the first main surface 3 so as to overlap the plurality of second regions 15 in the lamination direction. In this embodiment, the plurality of body regions 32 are arranged at intervals in the second arrangement direction Da2 so as to overlap the plurality of second regions 15 in the lamination direction in a one-to-one correspondence, and are each formed as a band extending in the second extension direction De2.

[0378] In this example, the second arrangement direction Da2 is the m-axis direction (the second Y direction), and the second extension direction De2 is the a-axis direction (the first X direction). Of course, an arrangement direction and an extension direction of the plurality of body regions 32 can be changed according to the second arrangement direction Da2 and the second extension direction De2 of the plurality of second regions 15. Therefore, the second arrangement direction Da2 may be the a-axis direction, and the second extension direction De2 may be the m-axis direction. Also, the second arrangement direction Da2 may be a direction other than the a-axis direction and the m-axis direction, and the second extension direction De2 may be a direction other than the a-axis direction and the m-axis direction.

[0379] In a case where the plurality of second regions 15 are formed at intervals from the first main surface 3, the plurality of body regions 32 are respectively formed in regions between the first main surface 3 and the second upper end portions 15b of the plurality of second regions 15. Preferably, the plurality of body regions 32 are formed on the first main surface 3 side with respect to the middle thickness region of the second layer 9 and are exposed from the first main surface 3. Preferably, the plurality of body regions 32 are connected to the corresponding second regions 15 (the second upper end portions 15b).

[0380] The plurality of body regions 32 are each shaped to be wider than the second regions 15 located directly below the body regions 32, and are formed at intervals from the plurality of adjacent second regions 15 toward the side of the second regions 15 located directly below the body regions 32. The plurality of body regions 32 each expose a part of the second drift regions 17 from regions of the first main surface 3 between the plurality of adjacent second regions 15.

[0381] The plurality of body regions 32 are formed of irregular impurity regions introduced into a surface layer portion of the second layer 9 by the random implantation method with respect to the second layer 9 (see also Fig. 14). Therefore, the plurality of body regions 32 has a smaller thickness than the second region thickness TR2 of the second regions 15 in a direction along the second axis channel CH2. The thickness of the plurality of body regions 32 is smaller than the first region thickness TR1 of the first regions 14.

[0382] Unlike the second region 15, etc., the plurality of body regions 32 do not have the shallow gradient portion 22 with a thickness of not less than 0.5 μm, and have a concentration gradient including the gradually rising portion 20, the peak portion 21, and the gradually falling portion 23 within a range of 0.5 μm. The plurality of body regions 32 may have a p-type impurity concentration of not less than 1 × 10 15 cm -3 and not more than 1 × 10 18 cm -3 as a peak value.

[0383] The p-type impurity concentration of the plurality of body regions 32 is preferably adjusted by at least one type of trivalent element. The trivalent element of the body region 32 may be the same type as the trivalent element of the second region 15, etc., or it may be a different type than the trivalent element of the second region 15, etc. The trivalent element of the body region 32 may be at least one type among boron, aluminum, gallium, and indium.

[0384] The SiC semiconductor device 1A has one or more n-type source regions 33 formed in surface layer portions of the plurality of body regions 32 in the active region 10, respectively. In this embodiment, a plurality of (two in this embodiment) source regions 33 are formed at intervals in the surface layer portion of each of the body regions 32. The plurality of source regions 33 have a higher n-type impurity concentration than the n-type impurity concentration of the second layer 9 (the plurality of second drift regions 17). The plurality of source regions 33 may have an n-type impurity concentration of not less than 1 × 10 18 cm -3 and not more than 1 × 10 21 cm -3 as a peak value.

[0385] The plurality of source regions 33 may extend as a band in an extension direction of the corresponding body regions 32. Of course, the plurality of source regions 33 may be formed at intervals in the extension direction of the corresponding body regions 32. The plurality of source regions 33 are formed at intervals from the lower portions of the corresponding body regions 32 toward the first main surface 3 and at intervals inward from the peripheral edges of the corresponding body regions 32. The plurality of source regions 33, together with the plurality of second drift regions 17, form channels (current paths) along the first main surface 3 in the peripheral edge portions of the body regions 32.

[0386] The SiC semiconductor device 1A has one or more p-type contact regions 34, each formed in surface layer portions of the plurality of body regions 32 in the active region 10. The contact region 34 may be referred to as a "back gate region." In this embodiment, the single contact region 34 is formed in a region between the plurality of source regions 33 adjacent to each other in the surface layer portion of each of the body regions 32.

[0387] The plurality of contact regions 34 have a higher p-type impurity concentration (a peak value) than the p-type impurity concentration (the peak value) of the plurality of body regions 32. The p-type impurity concentration (the peak value) of the plurality of contact regions 34 is higher than the p-type impurity concentration (the peak value) of the plurality of second regions 15. The plurality of contact regions 34 may have a p-type impurity concentration of not less than 1 × 10 18 cm -3 and not more than 1 × 10 21 cm -3 as a peak value.

[0388] The plurality of contact regions 34 may extend as a band in the extension direction of the corresponding body regions 32. Of course, the plurality of contact regions 34 may be formed at intervals in the extension direction of the corresponding body regions 32. The plurality of contact regions 34 are formed at intervals from the bottom portions of the corresponding body regions 32 toward the first main surface 3 side and at intervals inward from the peripheral edge portions of the corresponding body regions 32.

[0389] The SiC semiconductor device 1A includes a plurality of planar electrode-type gate structures 35 arranged on the first main surface 3 in the active region 10. The gate structure 35 may be referred to as a "planar gate structure." The plurality of gate structures 35 are arranged at intervals on the first main surface 3 so as to overlap the at least one body region 32 (a channel) in the lamination direction. A gate potential is applied to the plurality of gate structures 35 as a control potential. The plurality of gate structures 35 control the inversion and non-inversion of a channel (a current path) in the body region 32 depending on the gate potential.

[0390] In this embodiment, the plurality of gate structures 35 are arranged at intervals in the second arrangement direction Da2 and each formed as a band extending in the second extension direction De2. In this example, the second arrangement direction Da2 is the m-axis direction (the second direction Y), and the second extension direction De2 is the a-axis direction (the first direction X).

[0391] Of course, an arrangement direction and an extension direction of the plurality of gate structures 35 can be changed according to the second arrangement direction Da2 and the second extension direction De2 of the plurality of second regions 15 (body regions 32). Therefore, the second arrangement direction Da2 may be the a-axis direction, and the second extension direction De2 may be the m-axis direction. Also, the second arrangement direction Da2 may be a direction other than the a-axis direction and the m-axis direction, and the second extension direction De2 may be a direction other than the a-axis direction and the m-axis direction.

[0392] The plurality of gate structures 35 are arranged offset from the plurality of second regions 15 toward the plurality of second drift regions 17 side and overlap the plurality of second drift regions 17 in the lamination direction in a one-to-one correspondence. In this embodiment, the plurality of gate structures 35 are each arranged to span two adjacent body regions 32 and respectively cover the plurality of source regions 33 arranged in one and the other body region 32.

[0393] Each of the plurality of gate structures 35 has a laminated structure including a gate insulating film 36 disposed on the first main surface 3 and a gate electrode 37 disposed on the gate insulating film 36. The gate insulating film 36 may be formed from a silicon oxide film. The gate electrode 37 may be formed from a conductive polysilicon.

[0394] The gate insulating film 36 and the gate electrode 37, or both, may be arranged to partially overlap the second region 15 in the lamination direction. Of course, the gate insulating film 36 and the gate electrode 37, or both, may be arranged so that they do not partially overlap the second region 15 in the lamination direction.

[0395] A configuration on the outer peripheral portion 11 side is described below. Fig. 37 is a perspective view showing a configuration of the outer peripheral portion 11. Fig. 38A is a cross-sectional view showing a main portion of the outer peripheral portion 11 in the first direction X. Fig. 38B is a cross-sectional view in the second direction Y showing the main portion of the outer peripheral portion 11. In Fig. 37, a representation of the column area 12 is omitted.

[0396] The SiC semiconductor device 1A includes at least one p-type field region 38 (preferably, no fewer than two and no more than twenty field regions 38) formed in the surface layer portion of the first main surface 3 in the outer peripheral region 11. The number of field regions 38 is typically no fewer than four and no more than eight. The plurality of field regions 38 are formed in an electrically floating state and attenuate (relax) an electric field within the chip 2 at the peripheral edge portion of the first main surface 3. The number, width, depth, p-type impurity concentration, etc., of the field regions 38 are arbitrary and can take various values ​​depending on the electric field to be attenuated.

[0397] The plurality of field regions 38 are formed at intervals in a region between the peripheral edges of the chip 2 and the active region 10. The plurality of field regions 38 are each formed as a band extending along the active region 10 in plan view. Each of the plurality of field regions 38 has a portion extending as a band in the first direction X and a portion extending as a band in the second direction Y. In this embodiment, the plurality of field regions 38 are each formed in a ring shape (specifically, a square ring shape) surrounding the active region 10 in plan view.

[0398] The plurality of field regions 38 overlap the column region 12 in the lamination direction in the outer peripheral region 11. That is, the plurality of field regions 38 are formed in regions above the plurality of intersection areas of the plurality of first regions 14 and the plurality of second regions 15. The plurality of field regions 38 intersect the plurality of second regions 15 in sections extending in the first extension direction De1 and intersect the plurality of first regions 14 in sections extending in the second extension direction De2 in plan view.

[0399] The plurality of field regions 38 are formed in the second layer 9 at intervals from the lower end of the second layer 9 toward the first main surface 3 side, and each form pn junction regions with the second layer 9. The plurality of field regions 38 preferably have lower portions located on the first main surface 3 side relative to the middle thickness range of the second layer 9. The lower portions of the plurality of field regions 38 are particularly preferably located on the first main surface 3 side relative to the middle thickness ranges of the second regions 15.

[0400] The lower portions of the plurality of field regions 38 may be positioned closer to the second lower end portion 15a of the second regions 15 than the depth positions of the second upper end portions 15b of the second regions 15. In this case, the plurality of field regions 38 may be connected to the plurality of second regions 15 in the portions extending along the second extension direction De2. Of course, the plurality of field regions 38 may be formed at intervals in the horizontal direction from the plurality of second regions 15 in the portions extending along the second extension direction De2 and may not necessarily be connected to the plurality of second regions 15.

[0401] For example, if the distance between the first main surface 3 and the second upper end portions 15b is sufficiently large, the lower portions of the plurality of field regions 38 may be positioned closer to the first main surface 3 than the depth positions of the second upper end portions 15b of the second regions 15. Of course, in a case where the upper layer 30 is formed, the lower portions of the plurality of field regions 38 may be positioned closer to the first main surface 3 than the depth positions of the second upper end portions 15b of the second regions 15.

[0402] The plurality of field regions 38 may have a thickness substantially equal to the thickness of the plurality of body regions 32. In this case, the plurality of field regions 38 may be formed simultaneously with the plurality of body regions 32. Of course, the thickness of the plurality of field regions 38 may be greater than the thickness of the plurality of body regions 32. The thickness of the plurality of field regions 38 may also be less than the thickness of the plurality of body regions 32.

[0403] The plurality of field regions 38 are formed from the irregular impurity regions introduced into the surface layer portion of the second layer 9 by the random implantation method with respect to the second layer 9 (see also Fig. 14). Therefore, the plurality of field regions 38 has a smaller thickness than the second region thickness TR2 of the second regions 15 in a direction along the second axis channel CH2. The thickness of the plurality of field regions 38 is smaller than the first region thickness TR1 of the first region 14.

[0404] Unlike the second region 15, etc., the plurality of field regions 38 do not have the shallow gradient portion 22 with a thickness of not less than 0.5 μm and have a concentration gradient including the gradually rising portion 20, the peak portion 21, and the gradually falling portion 23 within a range of 0.5 μm. The plurality of field regions 38 may have a p-type impurity concentration of not less than 1 × 10 15 cm -3 and not more than 1 × 10 18 cm -3 as a peak value.

[0405] The p-type impurity concentration of field region 38 may be substantially equal to the p-type impurity concentration of body region 32. The p-type impurity concentration of the plurality of field regions 38 may be higher than the p-type impurity concentration of the plurality of body regions 32. The p-type impurity concentration of the plurality of field regions 38 may also be lower than the p-type impurity concentration of the plurality of body regions 32.

[0406] The p-type impurity concentration of the plurality of field regions 38 is preferably adjusted by at least one type of trivalent element. The trivalent element of the field region 38 may be the same type as the trivalent element of the second region 15, etc., or it may be a different type than the trivalent element of the second region 15, etc. The trivalent element of the field region 38 may be at least one type among boron, aluminum, gallium, and indium.

[0407] Each of the plurality of field regions 38 preferably has a different width than the second width W2 of the second region 15 (the first width W1 of the first region 14). That is, the relaxation effects (attenuation effects) of the electric field achieved by the plurality of field regions 38 are preferably adjusted separately from the column region 12.

[0408] The width of each of the plurality of field regions 38 is particularly preferably greater than the second width W2 of the second region 15 (the first width W1). Of course, the width of each of the plurality of field regions 38 can also be smaller than the second width W2 (the first width W1). The width of the column region 12 can also be substantially equal to the second width W2 (the first width W1).

[0409] The plurality of field regions 38 are preferably formed with a different pitch than the second pitch P2 of the second regions 15 (the first pitch P1 of the first regions 14). The pitch of the plurality of field regions 38 is particularly preferably greater than the second pitch P2 (the first pitch P1). Of course, the pitch of the plurality of field regions 38 can also be smaller than the second pitch P2 (the first pitch P1). The pitch of the plurality of field regions 38 can also be substantially equal to the second pitch P2 (the first pitch P1).

[0410] The SiC semiconductor device 1A includes an interlayer insulating film 40 covering the first main surface 3. The interlayer insulating film 40 may also be referred to as an "insulating film," "interlayer film," "interlayer insulating film," etc. In this embodiment, the interlayer insulating film 40 has a laminated structure including a first insulating film 41 and a second insulating film 42. The first insulating film 41 may include at least one of a silicon oxide film, a silicon nitride film, and a silicon oxynitride film. The first insulating film 41 particularly preferably includes a silicon oxide film formed from an oxide of the chip 2 (the second layer 9).

[0411] The first insulating film 41 selectively covers the first main surface 3 in the active region 10 and the outer peripheral region 11. The first insulating film 41 covers an area outside the gate insulating film 36 in the active region 10 and is connected to the gate insulating film 36. In the outer peripheral region 11, the first insulating film 41 covers the plurality of field regions 38.

[0412] In this embodiment, the first insulating film 41 extends continuously to the peripheral edges (first to fourth side surfaces 5A to 5D) of the first main surface 3. Therefore, the first insulating film 41 overlaps the plurality of second marks Mk2 (the plurality of second regions 15) at the peripheral edges of the first main surface 3. Of course, the first insulating film 41 may be formed at an interval inward from the peripheral edges of the first main surface 3 and may expose the second layer 9 from the peripheral edge portions of the first main surface 3.

[0413] The second insulating film 42 is laminated on the first insulating film 41. The second insulating film 42 may comprise at least one of a silicon oxide film, a silicon nitride film, or a silicon oxynitride film. The interlayer insulating film 40 preferably comprises a silicon oxide film. The second insulating film 42 covers the first main surface 3 above the first insulating film 41 in the active region 10 and the outer peripheral region 11.

[0414] The second insulating film 42 covers the plurality of gate structures 35 in the active region 10. The second insulating film 42 covers the plurality of field regions 38 above the first insulating film 41 in the outer peripheral region 11. In this embodiment, the second insulating film 42 is continuously formed up to the peripheral edges of the first main surface 3. The second insulating film 42 may overlap the plurality of second marks Mk2 (the plurality of second regions 15) via the first insulating film 41 at the peripheral edges of the first main surface 3. Of course, the second insulating film 42 may be formed at an interval inward from the peripheral edges of the first main surface 3 and may expose the peripheral edge portions of the first main surface 3 together with the first insulating film 41.

[0415] The SiC semiconductor device 1A has a plurality of contact holes 43 formed in the interlayer insulating film 40. The plurality of contact holes 43 includes the plurality of contact holes 43 (not shown) exposing the plurality of gate structures 35 (the gate electrodes 37) and the plurality of contact holes 43 exposing the plurality of source regions 33. The plurality of contact holes 43 for the source regions 33 are formed in regions between the plurality of adjacent gate structures 35 and expose the plurality of source regions 33 and the plurality of contact regions 34.

[0416] As in Fig. As shown in FIG. 1, the SiC semiconductor device 1A includes a gate pad 45 disposed on the interlayer insulating film 40. The gate pad 45 is an electrode to which a gate potential is applied from the outside. The gate pad 45 may be referred to as a "gate pad electrode," a "first pad electrode," etc. The gate pad electrode 45 may have a laminated structure including a Ti-based metal film and an Al-based metal film laminated in this order from the interlayer insulating film 40 side.

[0417] In this embodiment, the gate pad 45 is disposed on a portion of the interlayer insulating film 40 covering the active region 10. The gate pad 45 may also be disposed at an interval from the outer peripheral region 11 to the active region 10 side. In this embodiment, the gate pad 45 is disposed at the peripheral edge portions of the active region 10 in plan view.

[0418] Fig. 1 shows an example in which the gate pad 45 is arranged in a region along a central portion of the first side surface 5A at the peripheral edge portions of the active region 10. Of course, the gate pad 45 may be arranged in a region along any central portion of the first to fourth side surfaces 5A to 5D. Of course, the gate pad 45 may be arranged at any corner portion of the active region 10 in plan view. Also, the gate pad 45 may be arranged in a central region of the active region 10 in plan view. In this embodiment, the gate pad 45 is quadrangular in shape in plan view.

[0419] The SiC semiconductor device 1A includes at least one gate wiring 46 (in this embodiment, a plurality of gate wirings 46) led out from the gate pad 45 on the interlayer insulating film 40. The gate wiring 46 may also be referred to as "wiring," "wiring electrode," etc. The plurality of gate wirings 46 may have a laminated structure including a Ti-based metal film and an Al-based metal film laminated in this order from the interlayer insulating film 40 side. In this embodiment, the plurality of gate wirings 46 includes a first gate wiring 46A and a second gate wiring 46B.

[0420] The first gate wiring 46A is led out from the gate pad 45 toward the second side surface 5B and extends linearly along the peripheral edges of the active region 10, intersecting (in particular, being orthogonal to) a part (specifically, an end portion) of each of the plurality of gate structures 35. The first gate wiring 46A penetrates the interlayer insulating film 40 through the plurality of contact holes 43 and is electrically connected to one end portions of the plurality of gate structures 35.

[0421] The second gate wiring 46B is led out from the gate pad 45 toward the fourth side surface 5D and extends linearly along the peripheral edges of the active region 10, intersecting (in particular, being orthogonal to) a part (specifically, the other end portion) of each of the plurality of gate structures 35. The second gate wiring 46B penetrates the interlayer insulating film 40 through the plurality of contact holes 43 and is electrically connected to the other end portions of the plurality of gate structures 35.

[0422] The SiC semiconductor device 1A includes a source pad 47 disposed on the interlayer insulating film 40 at an interval between the gate pad 45 and the gate wiring 46. The source pad 47 is an electrode to which a source potential is applied from the outside. The source pad 47 may be referred to as a "source pad electrode," a "second pad electrode," etc. The source pad electrode 47 may have a laminated structure including a Ti-based metal film and an Al-based metal film laminated in this order from the interlayer insulating film 40 side.

[0423] The source pad 47 is disposed on a portion of the interlayer insulating film 40 covering the active region 10. The source pad 47 may be disposed at an interval from the outer peripheral region 11 to the active region 10 side. In this embodiment, the source pad 47 has a polygonal shape with a recessed portion recessed along the gate pad 45 in plan view. Of course, the source pad 47 may be quadrangular in plan view.

[0424] The source pad 47 penetrates the interlayer insulating film 40 through the plurality of contact holes 43 and is electrically connected to the plurality of body regions 32, the plurality of source regions 33, and the plurality of contact regions 34. That is, the source pad 47 is electrically connected to the pillar region 12 via the plurality of body regions 32.

[0425] The SiC semiconductor device 1A has a drain pad 48 covering the second main surface 4. The drain pad 48 is an electrode to which a drain potential is applied from the outside. The drain pad 48 may also be referred to as a "drain pad electrode," "third pad electrode," etc. The drain pad 48 forms an ohmic contact with the base layer 6 exposed from the second main surface 4. That is, the drain pad 48 is electrically connected to the first layer 8 (the plurality of first drift regions 16) and the second layer 9 (the plurality of second drift regions 17) via the base layer 6.

[0426] The drain pad 48 may cover the entire area of ​​the second main surface 4 so that it is continuous with the peripheral edges (the first to fourth side surfaces 5A to 5D) of the chip 2. The drain pad 48 may cover the second main surface 4 at an interval inward from the peripheral edges of the chip 2, so that the peripheral edge portions of the chip 2 are exposed.

[0427] A breakdown voltage that can be applied between the source pad 47 and the drain pad 48 (between the first main surface 3 and the second main surface 4) may be not less than 500 V and not more than 3000 V. The breakdown voltage may have a value that falls within any of the following ranges: not less than 500 V and not more than 1000 V, not less than 1000 V and not more than 1500 V, not less than 1500 V and not more than 2000 V, not less than 2000 V and not more than 2500 V, and not less than 2500 V and not more than 3000 V.

[0428] In a case where the laminated portion 7 having a two-layer structure is used, the breakdown voltage is preferably set to a value falling within any one of the ranges of not less than 500 V and not more than 1000 V, not less than 1000 V and not more than 1500 V, and not less than 1500 V and not more than 2000 V. In a case where the laminated portion 7 has a three-layer structure, the breakdown voltage is preferably set to a value falling within any one of the ranges of not less than 1000 V and not more than 1500 V, not less than 1500 V and not more than 2000 V, not less than 2000 V and not more than 2500 V, and not less than 2500 V and not more than 3000 V.

[0429] Fig. 39 is a perspective cross-sectional view showing the gate structures 35 according to the second configuration example. The plurality of gate structures 35 according to the first configuration example extend in the second extension direction De2 of the plurality of second regions 15. On the other hand, the plurality of gate structures 35 according to the second configuration example extend in a direction different from the second extension direction De2, so that they intersect the plurality of second regions 15.

[0430] In this embodiment, the plurality of body regions 32 described above extend in a direction other than the second extension direction De2, so that they intersect the plurality of second regions 15 in the lamination direction. In this embodiment, the plurality of body regions 32 are arranged at intervals in the first arrangement direction Da1 of the first regions 14 and extend in the first extension direction De1 of the first regions 14. That is, the plurality of body regions 32 are orthogonal to the plurality of second regions 15. In this embodiment, the first arrangement direction Da1 is the a-axis direction (the first direction X), and the first extension direction De1 is the m-axis direction (the second direction Y).

[0431] The plurality of body regions 32 may be opposite the plurality of first regions 14 in the lamination direction in a one-to-one correspondence. Of course, the respective body regions 32 may be opposite the plurality of first regions 14 in the lamination direction. The plurality of body regions 32 may be opposite the plurality of first drift regions 16 in the lamination direction in a one-to-one correspondence.

[0432] Of course, the respective body regions 32 may be opposite the plurality of first drift regions 16 in the lamination direction. The plurality of body regions 32 may be offset from the plurality of first regions 14 in the first arrangement direction Da1 and may be opposite one or both of the first regions 14 and the first drift region 16 in the lamination direction.

[0433] Of course, an arrangement direction and an extension direction of the plurality of body regions 32 can be changed in accordance with the first arrangement direction Da1 and the first extension direction De1 of the plurality of first regions 14. Therefore, the first arrangement direction Da1 can be the m-axis direction, and the first extension direction De1 can be the a-axis direction. Furthermore, the first arrangement direction Da1 can be a direction other than the a-axis direction and the m-axis direction, and the first extension direction De1 can be a direction other than the a-axis direction and the m-axis direction.

[0434] Of course, the arrangement direction of the plurality of body regions 32 may be a direction other than the first arrangement direction Da1 and the second arrangement direction D2. The extension direction of the plurality of body regions 32 may also be a direction other than the first extension direction De1 and the second extension direction De2. That is, the plurality of body regions 32 may intersect both the plurality of first regions 14 and the plurality of second regions 15 in plan view. In this case, a shape in which the arrangement direction of the plurality of body regions 32 is one of the a-axis or m-axis directions, and the extension direction of the plurality of body regions 32 is the other of the a-axis or m-axis directions is not excluded.

[0435] For example, the angle (an absolute value) between the extension direction of the body regions 32 and the second extension direction De2 can be greater than 0° and at most 90°. The angle (the absolute value) of the body regions 32 can be in one of the following ranges: between 0° and at most 18°, between 18° and at most 36°, between 36° and at most 54°, between 54° and at most 72°, and between 72° and at most 90°. The angle (the absolute value) of the body regions 32 can be set to a value that falls within one of the ranges 30° ± 5°, 45° ± 5°, and 60° ± 5°.

[0436] The plurality of source regions 33 and the plurality of contact regions 34 described above are formed along the extending direction of the corresponding body regions 32 and respectively oppose the plurality of second regions 15 and the plurality of second drift regions 17 via parts of the corresponding body regions 32 in the lamination direction.

[0437] In this embodiment, the plurality of gate structures 35 are arranged at intervals in the first arrangement direction Da1 of the first regions 14 and extend in the first extension direction De1 of the first regions 14. That is, the plurality of gate structures 35 are orthogonal to the plurality of second regions 15. In this embodiment, the first arrangement direction Da1 is the a-axis direction (the first direction X), and the first extension direction De1 is the m-axis direction (the second direction Y).

[0438] The plurality of gate structures 35 may be disposed opposite the plurality of first regions 14 in the lamination direction in a one-to-one correspondence. Of course, the respective gate structures 35 may be disposed opposite the plurality of first regions 14 in the lamination direction. The plurality of gate structures 35 may be disposed opposite the plurality of first drift regions 16 in the lamination direction in a one-to-one correspondence.

[0439] Of course, the respective gate structures 35 may be opposite the plurality of first drift regions 16 in the lamination direction. The plurality of gate structures 35 may be arranged offset from the plurality of first regions 14 in the first arrangement direction Da1 and may be opposite one or both of the first regions 14 and the first drift region 16 in the lamination direction.

[0440] Of course, an arrangement direction and an extension direction of the plurality of gate structures 35 are changed according to the first arrangement direction Da1 and the first extension direction De1 of the plurality of first regions 14 (body regions 32). Therefore, the first arrangement direction Da1 may be the m-axis direction, and the first extension direction De1 may be the a-axis direction. Furthermore, the first arrangement direction Da1 may be a direction other than the a-axis direction and the m-axis direction, and the first extension direction De1 may be a direction other than the a-axis direction and the m-axis direction.

[0441] Of course, the arrangement direction of the plurality of gate structures 35 may be a direction other than the first arrangement direction Da1 and the second arrangement direction Da2. Also, the extension direction of the plurality of gate structures 35 may be a direction other than the first extension direction De1 and the second extension direction De2. That is, the plurality of gate structures 35 may intersect both the plurality of first regions 14 and the plurality of second regions 15 in plan view. In this case, a shape in which the arrangement direction of the plurality of gate structures 35 is one of the a-axis or m-axis directions, and the extension direction of the plurality of gate structures 35 is the other of the a-axis or m-axis directions is not excluded.

[0442] For example, the angle (an absolute value) between the extension direction of the gate structures 35 and the second extension direction De2 can be greater than 0° and at most 90°. The angle (the absolute value) of the gate structures 35 can be in one of the following ranges: between 0° and at most 18°, between 18° and at most 36°, between 36° and at most 54°, between 54° and at most 72°, and between 72° and at most 90°. The angle (the absolute value) of the gate structures 35 can be set to a value that falls within one of the ranges 30° ± 5°, 45° ± 5°, and 60° ± 5°.

[0443] In this embodiment, the plurality of gate structures 35 are each arranged to span two adjacent body regions 32 and each cover the plurality of source regions 33 arranged in one and the other body region 32. Furthermore, the plurality of gate structures 35 face the plurality of second regions 15 (second regions 15) and the plurality of second drift regions 17 in the lamination direction.

[0444] Fig. 40 is a schematic view showing a wafer 50 used in the fabrication of the SiC semiconductor device 1A. The wafer 50 is a base material of the base layer 6 and comprises a SiC single crystal. The wafer 50 has the shape of a flat disk. Of course, the wafer 50 may also be formed into a flat, rectangular parallelepiped shape. The wafer 50 has a first wafer main surface 51 on one side, a second wafer main surface 52 on the other side, and a wafer side surface 53 connecting the first wafer main surface 51 and the second wafer main surface 52.

[0445] The first wafer main surface 51 corresponds to the upper end of the base layer 6, and the second wafer main surface 52 corresponds to the lower end of the base layer 6. The first wafer main surface 51 and the second wafer main surface 52 are formed from c-planes of the SiC single crystal. The first wafer main surface 51 is formed from a silicon plane of the SiC single crystal, and the second wafer main surface 52 is formed from a carbon plane of the SiC single crystal. The wafer 50 (the first wafer main surface 51 and the second wafer main surface 52) has the above-described deviation direction Doff and the deviation angle θoff.

[0446] The wafer 50 has a marking 54 indicating a crystal orientation of the SiC single crystal on the wafer side surface 53. The marking 54 may include an orientation surface and / or an orientation notch. The orientation surface may be formed from a notched portion that is cut linearly in plan view. The orientation notch may be formed from a notched portion that is cut concavely (e.g., tapered) in plan view toward a central portion of the first wafer main surface 51.

[0447] The marking 54 may include a first orientation surface extending in the m-axis direction and a second orientation surface extending in the a-axis direction, or both. The marking 54 may include an orientation notch recessed in the m-axis direction or an orientation notch recessed in the a-axis direction, or both. Fig. 40 shows an orientation surface extending in the a-axis direction in plan view.

[0448] For example, a plurality of component regions 55 and a plurality of designated cutting lines 56 are defined on the wafer 50 by an alignment mark, etc. Each of the component regions 55 is a region corresponding to the SiC semiconductor device 1A. The plurality of component regions 55 are each arranged in a square shape in plan view.

[0449] In this embodiment, the plurality of component regions 55 are arranged in a matrix in the first direction X and the second direction Y in plan view. The plurality of component regions 55 are each arranged inwardly from the peripheral edges of the first wafer main surface 51 in plan view. The plurality of provided cutting lines 56 are arranged in a grid extending in the first direction X and the second direction Y to define the plurality of component regions 55.

[0450] Fig. 41 is a flowchart showing an example of a manufacturing method of the SiC semiconductor device 1A. Fig. 42A to 42H are perspective cross-sectional views illustrating the example of the manufacturing process for the SiC semiconductor device 1A. Fig. 43A and Fig. 43B are schematic views illustrating a measurement step for a crystal orientation. Fig. 44A and Fig. 44B are schematic views illustrating an ion implantation step. Fig. 42A to 42H show perspective cross-sectional views of a portion of the active region 10 of the single device region 55.

[0451] First, as in Fig. 42A, a preparation step for the wafer 50 described above is carried out (step S1 in Fig. 41). Next, a determination step is performed as to whether a forming step of the n-type buffer layer 26 (see Fig. 31 and Fig. 32) should be carried out or not (step S2 in Fig. 41). In a case where the buffer layer 26 is to be formed (step S2 in Fig. 41: YES), the buffer layer 26 is formed with the first wafer main surface 51 (the wafer 50) as a starting point by an epitaxial growth process (epitaxy process) (step S3 in Fig. 41). If the step of forming the buffer layer 26 is not carried out (step S2 in Fig. 41: NO), this step is omitted.

[0452] Next, as in Fig. 42B, a forming step of the first n-type layer 8 is performed (step S4 in Fig. 41). If the step of forming the buffer layer 26 is omitted, the first layer 8 is formed with the first wafer main surface 51 (the wafer 50) as a starting point by the epitaxial growth method. In a case where the buffer layer 26 is formed, the first layer 8 is formed with the buffer layer 26 as a starting point by the epitaxial growth method. In this case, the first layer 8 can be formed by continuous crystal growth from the buffer layer 26 after the buffer layer 26 forming step.

[0453] Next, a measurement of the crystal orientation of the first layer 8 is carried out (step S5 in Fig. 41). The crystal orientation of the first layer 8 includes a step of measuring the deviation angle θoff of the first layer 8. That is, this step includes a step of measuring a crystal orientation of the first axis channel CH1 of the first layer 8.

[0454] The wafer 50 is cut from an ingot (a SiC ingot), which is a crystalline lump, but there is a risk that the deviation angle θoff is incorrect due to a process error. If an error occurs in the deviation angle θoff of the wafer 50, this will also result in a process error in the deviation angle θoff of the first layer 8, which hinders the channel implantation process. Therefore, it is advantageous to acquire the data (information) of the deviation angle θoff before the channel implantation process, and to perform the channel implantation process based on the data (information) of this deviation angle θoff.

[0455] With reference to Fig. 43A, in this step, the crystal orientation of the first layer 8 is measured by an X-ray diffraction method (a so-called ω-2θ measurement method) using an X-ray diffractometer 57. The X-ray diffractometer 57 may also be referred to as an "XRD (X-ray diffraction) device."

[0456] The X-ray diffractometer 57 comprises an irradiation section 58 and a detection section 59 and performs a rocking curve measurement method. The irradiation section 58 irradiates the upper end of the first layer 8 (the first wafer main surface 51 of the wafer 50) with an incident X-ray beam L1 at a predetermined angle of incidence ω. The angle of incidence ω is defined by the angle between the incident X-ray beam L1 and the upper end of the first layer 8 (the first wafer main surface 51 of the wafer 50).

[0457] The detection section 59 is arranged at an angular position of a diffraction angle 2θ (θ is a Bragg angle) with respect to an irradiation position on the wafer 50 with the incident X-ray L1 and detects a diffracted X-ray L2. The diffraction angle 2θ is an angle between the incident direction of the incident X-ray L1 and the diffraction direction of the diffracted X-ray L2.

[0458] In the rocking curve measurement method, the angle of incidence ω is varied within a small angular range while the diffraction angle 2θ remains constant. A rocking curve is measured that represents the intensity of the diffracted X-rays L2 (i.e., the intensity profile of the radiation L2). The rocking curve shows the intensity of the diffracted X-rays L2 on the ordinate and the angle of incidence ω on the abscissa. The angle of incidence ω is determined at an angular position where the intensity of the diffracted X-rays L2 reaches a peak.

[0459] In this step, the rocking curve measurement method is performed only for one location (e.g., the central portion) of the top end of the first layer 8 (the first wafer main surface 51 of the wafer 50). In the case where an in-plane variation of the deviation angle θoff is assumed, the rocking curve measurement method may be performed at a plurality of locations (e.g., the central portion and the peripheral edge portions) of the top end of the first layer 8 (the first wafer main surface 51 of the wafer 50).

[0460] Fig. 43B shows the measurement locations in a case where the rocking curve measurement method is performed at a plurality of (here, five) locations on the upper end of the first layer 8. In this case, the deviation angle θoff of the first layer 8 is set to approximately 4°. Fig. 43B shows the first to fifth measuring points Po1 to Po5.

[0461] The first measurement point Po1 is located in the central portion of the first layer 8. The second measurement point Po2 is set on the peripheral edge portion of the first layer 8 on one side (a side opposite the mark 54) in the second direction Y at an interval from the first measurement point Po1. The third measurement point Po3 is set on the peripheral edge portion of the first layer 8 on one side (the right side with respect to the mark 54) in the first direction X at an interval from the first measurement point Po1.

[0462] The fourth measurement point Po4 is set on the peripheral edge portion of the first layer 8 on the other side (the side of the mark 54) in the second direction Y at an interval from the first measurement point Po1. The fifth measurement point Po5 is set on the peripheral edge portion of the first layer 8 on the other side (the left side with respect to the mark 54) in the first direction X at an interval from the first measurement point Po1.

[0463] The measurement results for the angles of incidence ω, the diffraction angles 2θ, and the deviation angles θoff at the first to fifth measurement points Po1 to Po5 are listed in Table 1. The deviation angle θoff is determined by a calculation formula "ω - (2θ × 1 / 2)" using the angle of incidence ω and the diffraction angle 2θ. [Table 1] Table 1 Messstelle ω (°) 2θ (°) θoff (°) Po1 21.836 35.606 4.033 Po2 21.830 35.609 4.025 Po3 21.841 35.611 4.035 Po4 21.837 35.609 4.033 Po5 21.856 35.606 4.053 Durchschnitt 4.036 Standardabweichung 0.009

[0464] As shown in Table 1, the mean value of the deviation angles θoff of the first to fifth measurement points Po1 to Po5 was 4.036°, and the standard deviation of these deviation angles θoff was 0.009° (±0.01°). This leads to the understanding that the in-plane variations of the deviation angle θoff at the top of the first layer 8 (the first wafer main surface 51 of the wafer 50) are very small and of a magnitude that does not affect the channel implantation step.

[0465] Thus, it is sufficient to specify one location as the measurement point relative to the upper end of the first layer 8 (the first wafer main surface 51 of the wafer 50). The measurement location can be, for example, any one or a plurality of (all) the first to fifth measurement points Po1 to Po5. The measurement location can, for example, be only the first measurement point Po1. By reducing the number of measurement points (number of measurements), the manufacturing process is simplified and manufacturing costs are reduced.

[0466] Of course, the deviation angle θoff may be measured at a plurality of locations at the top of the first layer 8 (the first wafer main surface 51 of the wafer 50), and an implantation angle may be determined according to the in-plane variation of the deviation angle θoff in the channel implantation step. In this case, although the number of manufacturing steps (manufacturing cost) increases, an in-plane defect (planar defect) of the first regions 14 formed in the first layer 8 is suitably prevented.

[0467] The deviation angle θoff of the first layer 8 is substantially matched to the deviation angle θoff of the wafer 50 and the deviation angle θoff of the buffer layer 26. Therefore, the crystal orientation measurement can be performed on the wafer 50 or the buffer layer 26 before the formation of the first layer 8. However, for reasons of accuracy, the crystal orientation measurement step is preferably performed directly on the first layer 8.

[0468] Next, as in Fig. 42C, a forming step of a first mask 60 with a predetermined pattern is carried out (step S6 in Fig. 41). The first mask 60 is preferably an organic mask (a resist mask). The first mask 60 is arranged at the upper end of the first layer 8 and has a plurality of first openings 61 that expose regions of the first layer 8 in which the plurality of first regions 14 are to be formed.

[0469] Specifically, the plurality of first openings 61 are formed at intervals in the first arrangement direction Da1 across the entire surface of the upper end of the first layer 8, and each is defined as a band extending in the first extension direction De1. That is, the plurality of first openings 61 intersect the plurality of component regions 55 and the plurality of designated cutting lines 56 in the first extension direction De1, exposing the plurality of component regions 55 and the plurality of designated cutting lines 56 as stripes. The plurality of first openings 61 expose, in each component region 55, both a portion of the upper end of the first layer 8 located in the active region 10 and a portion of the upper end of the first layer 8 located in the outer peripheral region 11.

[0470] Next, as in Fig. 42D, a forming step for the plurality of first regions 14 is carried out (step S7 in Fig. 41). The step of forming the plurality of first regions 14 includes a channel implantation step of a trivalent element (p-type impurity) into the first layer 8. The first layer 8 (the wafer 50) has a deviation angle θoff inclined by a predetermined angle in the predetermined deviation direction Doff with respect to the first wafer main surface 51. The channel implantation step is performed based on the data (information) of the deviation angle θoff.

[0471] As in Fig. 44A, in the random implantation method, a trivalent element is introduced into the first layer 8 with a predetermined implantation energy in a direction intersecting the first axis channel CH1 (deviation angle θoff) (see also Fig. 14). In the random implantation method, the trivalent element is implanted, for example, in the vertical direction Z perpendicular to the upper end (the first wafer main surface 51) of the first layer 8.

[0472] Since, in the random implantation method, the trivalent element is introduced in a direction in which relatively dense atomic rows are present in the plan view, the trivalent element collides with the atomic rows at a relatively shallow depth position. Thus, the atomic rows prevent the trivalent element from being introduced into a relatively deep position of the first layer 8. As a result, the first region 14 is formed without the shallow gradient section 22 (see also Fig. 14).

[0473] In contrast, as in Fig. 44B, in the channel implantation method, an implantation angle of the trivalent element with respect to the first layer 8 is controlled, and the trivalent element is introduced into the first layer 8 along the first axis channel CH1 (the c-axis of the SiC single crystal in this embodiment) with a predetermined implantation energy (see also Fig. 13A to 13E). In this case, the implantation angle of the trivalent element with respect to the first layer 8 and / or an inclination angle of the first layer 8 with respect to the implantation angle of the trivalent element is adjusted.

[0474] For example, the wafer 50 may be stored horizontally, and the trivalent element may be introduced into the first layer 8 along the first axis channel CH1. Of course, the wafer 50 may also be held in a state in which it is tilted by the deviation angle θoff from the horizontal, and the trivalent element may thus be introduced into the first layer 8 along the first axis channel CH1. The plurality of first regions 14 having a predetermined thickness are formed at a predetermined depth position by an arbitrary combination of implantation energies of the trivalent element and implantation temperatures of the trivalent element (temperatures of the wafer 50) (see also Fig. 13A to 13E).

[0475] The implantation energy of the trivalent element may be not less than 100 KeV and not more than 2000 KeV. The implantation energy may have a value that falls within any of the following ranges: not less than 100 KeV and not more than 250 KeV, not less than 250 KeV and not more than 500 KeV, not less than 500 KeV and not more than 750 KeV, not less than 750 KeV and not more than 1000 KeV, not less than 1000 KeV and not more than 1250 KeV, not less than 1250 KeV and not more than 1500 KeV, not less than 1500 KeV and not more than 1750 KeV, and not less than 1750 KeV and not more than 2000 KeV.

[0476] The implantation temperature of the trivalent element can be set within a range of not less than 0°C and not more than 1500°C. The implantation temperature can be within any of the following ranges: not less than 0°C and not more than 25°C, not less than 25°C and not more than 50°C, not less than 50°C and not more than 100°C, not less than 100°C and not more than 250°C, not less than 250°C and not more than 500°C, not less than 500°C and not more than 750°C, not less than 750°C and not more than 1000°C, not less than 1000°C and not more than 1250°C, and not less than 1250°C and not more than 1500°C.

[0477] The implantation angle of the trivalent element is preferably set within a range of ±2° based on an axis along the first axial channel CH1 (the c-axis of the SiC single crystal in this embodiment) (0°). The implantation angle of the trivalent element is particularly preferably set within a range of ±1° based on the axis along the first axial channel CH1 (the c-axis of the SiC single crystal in this embodiment) (0°).

[0478] In the channel implantation process, the trivalent element is introduced along the first axis channel CH1, where the atomic rows are relatively sparse in plan view. The trivalent element moves in the first axis channel CH1, repeatedly experiencing small-angle scattering due to a channeling effect, and reaches a relatively deep position in the first layer 8. This means that in the channel implantation process, the collision probability of the trivalent element with the atomic rows of the SiC single crystal is reduced.

[0479] In this case, a trivalent element belonging to the heavy elements heavier than carbon is preferably incorporated into the first layer 8. That is, the trivalent element is preferably a trivalent element (at least one of aluminum, gallium, and indium) excluding boron. In this embodiment, the trivalent element is aluminum.

[0480] The first extension direction De1 may be the a-axis direction or the m-axis direction. The first extension direction De1 may be a direction other than the a-axis direction and the m-axis. In a case where the first extension direction De1 coincides with the m-axis direction (see also Fig. 8A, etc.), the trivalent element is introduced into the first layer 8 through the plurality of first openings 61 while being inclined substantially by the deviation angle θoff with respect to the upper end of the first layer 8 in the cross-sectional view in the first arrangement direction Da1.

[0481] In the case where the first extension direction De1 coincides with the a-axis direction (the deviation direction Doff) (see also Fig. 10A, etc.), the trivalent element is introduced into the first layer 8 through the plurality of first openings 61 while being substantially perpendicular to the upper end of the first layer 8 in the first arrangement direction Da1 as viewed in cross-sectional view. This prevents the plurality of first regions 14 in the first layer 8 from being formed in an inclined position. Furthermore, the wall surfaces of the plurality of first openings 61 are prevented from becoming obstructing objects with respect to the incident path of the trivalent element.

[0482] In the case where the first extension direction De1 is a direction other than the a-axis direction and the m-axis (see also Fig. 12A to 12C, etc.), there is no need to strictly control the orientation deviation of the plurality of first regions 14 with respect to the crystal orientation of the SiC single crystal.

[0483] After the trivalent element implantation step, lattice defects, etc., that have formed in the first layer 8 can be repaired by an annealing process simultaneously with the electrical activation of the trivalent element. The annealing temperature for the first layer 8 can be no less than 500°C and no more than 2000°C. Consequently, a plurality of first regions 14 are formed, and the first superjunction structure SJ1 is formed simultaneously.

[0484] The plurality of first regions 14 are arranged at intervals in the first arrangement direction Da1 over the entire area of ​​the first layer 8 and are each shaped to extend as a band in the first extension direction De1. That is, the plurality of first regions 14 are formed as stripes so that they intersect the plurality of component regions 55 and the plurality of designated cutting lines 56 in the first extension direction De1. After the step of forming the plurality of first regions 14, the first mask 60 is removed.

[0485] Next, it is determined whether or not a step for adjusting the thickness of the first layer 8 should be performed (step S8 in Fig. 41). If the thickness of the first layer 8 is to be adjusted (step S8 in Fig. 41: YES), the first layer 8 is thinned from the upper end side (step S9 in Fig. 41).

[0486] The thickness adjustment step (thinning step) may include a step of partially removing the upper end portion of the first layer 8 by a grinding process. The grinding process may be a mechanical polishing process and / or a chemomechanical polishing process. The thickness adjustment step may include a step of partially removing the upper end portion of the first layer 8 by an etching process. The etching process may be a wet etching process and / or a dry etching process.

[0487] The thickness adjustment step may comprise a step of exposing the plurality of first regions 14 from the upper end of the first layer 8 (see also Fig. 27 to 30, etc.). That is, the thickness adjustment step may include a step of partially or completely removing the first gradually rising portion 20A from the plurality of first regions 14. If the thickness adjustment step is not to be performed (step S8 in Fig. 41: NO), this step is omitted.

[0488] Next, a determination step is carried out as to whether a forming step of the plurality of intermediate regions 25 (see also Fig. 25 and Fig. 26) should be carried out or not (step S10 in Fig. 41). In a case where several intermediate areas 25 are to be formed (step S10 in Fig. 41: YES), the plurality of intermediate regions 25 are formed in the surface layer portion of the first layer 8 (step S11 in Fig. 41).

[0489] The step of forming the plurality of intermediate regions 25 includes a step of disposing a mask (not shown) with a predetermined pattern on the upper end of the first layer 8. The mask (not shown) is preferably an organic mask (a resist mask). The mask (not shown) has a plurality of openings, each of which exposes regions in which the plurality of first regions 14 are formed in the first layer 8.

[0490] Specifically, the plurality of openings are formed at intervals in the first arrangement direction Da1 across the entire surface of the upper end of the first layer 8, and each is defined as a band extending in the first extension direction De1. That is, the plurality of first openings intersect the plurality of component regions 55 and the plurality of designated cutting lines 56 in the first extension direction De1, exposing the plurality of component regions 55 and the plurality of designated cutting lines 56 as stripes. The plurality of first openings, in each component region 55, expose both a portion of the upper end of the first layer 8 located in the active region 10 and a portion of the upper end of the first layer 8 located in the outer peripheral region 11.

[0491] The forming step of the plurality of intermediate regions 25 includes a step of introducing the trivalent element into the first layer 8 with a predetermined implantation energy in a direction intersecting the first axis channel CH1 (the deviation angle θoff) by a random implantation method through the mask (not shown) (see also Fig. 14). The trivalent element can be introduced into the first layer 8 once or multiple times. If the trivalent element is introduced multiple times, it can be introduced into different depth positions of the first layer 8 in several stages with a variety of implantation energies.

[0492] The plurality of intermediate regions 25 are arranged at intervals in the first arrangement direction Da1 over the entire area of ​​the first layer 8 and are each shaped to extend as a band in the first extension direction De1. That is, the plurality of intermediate regions 25 are formed as stripes so that they intersect the plurality of component regions 55 and the plurality of designated cutting lines 56 in the first extension direction De1. After the step of forming the plurality of intermediate regions 25, the mask (not shown) is removed.

[0493] In the case where the above-described thickness adjustment step of the first layer 8 is not performed, the step of forming the plurality of intermediate regions 25 may be performed seamlessly after the step of forming the plurality of first regions 14. In this case, the plurality of intermediate regions 25 may be formed using the above-described first mask 60.

[0494] Next, as in Fig. 42E, a forming step of the second layer 9 is carried out (step S12 in Fig. 41). The second layer 9 is formed with the first layer 8 as a starting point by the epitaxial method. Thereafter, a measurement step of a crystal orientation (the deviation angle θoff) of the second layer 9 can be performed by a method identical to that in step S4 according to Fig. 41 is (see also Fig. 43A and Fig. 43B).

[0495] Next, as in Fig. 42F, a forming step of a second mask 62 having a predetermined pattern is performed (step S13 in Fig. 41). The second mask 62 is preferably an organic mask (a resist mask). The second mask 62 is arranged at the upper end of the second layer 9 and has a plurality of second openings 63 that expose regions of the second layer 9 in which the plurality of second regions 15 are to be formed.

[0496] Specifically, the plurality of second openings 63 are formed at intervals in the second arrangement direction Da2, which is different from the first arrangement direction Da1, on the entire surface of the upper end of the second layer 9, and are each defined as a band extending in the second extension direction De2, which is different from the first extension direction De1. That is, the plurality of second openings 63 intersect the plurality of component regions 55 and the plurality of provided cutting lines 56 in the second extension direction De2, and expose the plurality of component regions 55 and the plurality of provided cutting lines 56 as stripes. The plurality of second openings 63 exposes, in each component region 55, both a portion of the upper end of the second layer 9 located in the active region 10 and a portion of the upper end of the second layer 9 located in the outer peripheral region 11.

[0497] Next, as in Fig. 42G, a forming step of the plurality of second regions 15 is carried out (step S14 in Fig. 41). The forming step of the plurality of second regions 15 includes a channel implantation step of a trivalent element (p-type impurity) into the second layer 9. The channel implantation step is performed based on the above-described data (information) of the deviation angle θoff.

[0498] In the channel implantation method, an implantation angle of the trivalent element with respect to the second layer 9 is controlled, and the trivalent element is introduced into the second layer 9 along the second axis channel CH2 (the c-axis of the SiC single crystal in this embodiment) with a predetermined implantation energy (see also Fig. 13A to 13E). In this case, the implantation angle of the trivalent element with respect to the second layer 9 and / or an inclination angle of the second layer 9 with respect to the implantation angle of the trivalent element are adjusted.

[0499] For example, the wafer 50 may be stored horizontally, and the trivalent element may be introduced into the second layer 9 along the second axis channel CH2. Of course, the wafer 50 may also be held in a state in which it is inclined by the deviation angle θoff from the horizontal, and the trivalent element may thus be introduced into the second layer 9 along the second axis channel CH2. The plurality of second regions 15 having a predetermined thickness are formed at a predetermined depth position by an arbitrary combination of implantation energies of the trivalent element and implantation temperatures of the trivalent element (see also Fig. 13A to 13E).

[0500] The implantation energy of the trivalent element may be not less than 100 KeV and not more than 2000 KeV. The implantation energy may have a value that falls within any of the following ranges: not less than 100 KeV and not more than 250 KeV, not less than 250 KeV and not more than 500 KeV, not less than 500 KeV and not more than 750 KeV, not less than 750 KeV and not more than 1000 KeV, not less than 1000 KeV and not more than 1250 KeV, not less than 1250 KeV and not more than 1500 KeV, not less than 1500 KeV and not more than 1750 KeV, and not less than 1750 KeV and not more than 2000 KeV.

[0501] The implantation energy related to the second regions 15 can be substantially equal to the implantation energy related to the first regions 14 or can differ from the implantation energy related to the first regions 14. The implantation energy related to the second regions 15 cannot be less than the implantation energy related to the first regions 14. The implantation energy for the second regions 15 can also be less than the implantation energy for the first regions 14.

[0502] The implantation temperature of the trivalent element can be set within a range of not less than 0°C and not more than 1500°C. The implantation temperature can be within any of the following ranges: not less than 0°C and not more than 25°C, not less than 25°C and not more than 50°C, not less than 50°C and not more than 100°C, not less than 100°C and not more than 250°C, not less than 250°C and not more than 500°C, not less than 500°C and not more than 750°C, not less than 750°C and not more than 1000°C, not less than 1000°C and not more than 1250°C, and not less than 1250°C and not more than 1500°C.

[0503] The implantation temperature for the second regions 15 may be substantially the same as the implantation temperature for the first regions 14 or may differ from the implantation temperature for the first regions 14. The implantation temperature for the second regions 15 may not be lower than the implantation temperature for the first regions 14. The implantation temperature in the second regions 15 may also be lower than the implantation temperature in the first regions 14.

[0504] The implantation angle of the trivalent element is preferably set within a range of ±2° based on an axis along the second axial channel CH2 (in this embodiment, the c-axis of the SiC single crystal) (0°). The implantation angle of the trivalent element is particularly preferably set within a range of ±1° based on an axis along the second axial channel CH2 (in this embodiment, the c-axis of the SiC single crystal) (0°).

[0505] In the channel implantation process, the trivalent element is introduced along the second axis channel CH2, where the atomic rows are relatively sparse in plan view. The trivalent element moves along the second axis channel CH2, repeatedly experiencing small-angle scattering due to a channeling effect, and reaches a relatively deep position in the second layer 9. This means that in the channel implantation process, the collision probability of the trivalent element with respect to the atomic rows of the SiC single crystal is reduced.

[0506] In this case, a trivalent element belonging to the heavy elements heavier than carbon is preferably incorporated into the second layer 9. That is, the trivalent element is preferably a trivalent element (at least one of aluminum, gallium, and indium) excluding boron. In this embodiment, the trivalent element is aluminum.

[0507] The second extension direction De2 may be the a-axis direction or the m-axis direction. The second extension direction De2 may be a direction other than the a-axis direction and the m-axis. In the case where the second extension direction De2 coincides with the a-axis direction (the deviation direction Doff) (see also Fig. 8A, etc.), the trivalent element is introduced into the second layer 9 through the plurality of second openings 63 while being substantially perpendicular to the upper end of the second layer 9 in the cross-sectional view in the second arrangement direction Da2. This prevents the plurality of second regions 15 in the second layer 9 from being formed in an inclined position. Furthermore, it prevents the wall surfaces of the plurality of second openings 63 from becoming obstructing objects with respect to the incident path of the trivalent element.

[0508] In the case where the second extension direction De2 coincides with the m-axis direction (see also Fig. 10A, etc.), the trivalent element is introduced into the second layer 9 through the plurality of second openings 63 while being inclined in the cross-sectional view in the second arrangement direction Da2 substantially by the deviation angle θoff with respect to the upper end of the second layer 9.

[0509] In the case where the second extension direction De2 is a direction other than the a-axis direction and the m-axis direction (see also Fig. 12A to 12C, etc.), there is no need to strictly control the orientation deviation of the plurality of second regions 15 with respect to the crystal orientation of the SiC single crystal.

[0510] When the first extension direction De1 of the first regions 14 is a direction other than the a-axis direction and the m-axis direction, the second extension direction De2 is also preferably a direction other than the a-axis direction and the m-axis direction. In this case, the plurality of first regions 14 have the first extension angle θ1 inclined toward one side of the m-axis with respect to the a-axis, and the plurality of second regions 15 have the second extension angle θ2 toward the other side of the m-axis with respect to the a-axis.

[0511] The absolute value of the second extension angle θ2 may be different from the absolute value of the first extension angle θ1. However, in this case, the relative implantation angle condition of the trivalent element in the second region 15 forming step differs from the relative implantation angle condition of the trivalent element in the first region 14 forming step. Therefore, the blocking area of ​​the plurality of second openings 63 with respect to the incident path of the trivalent element differs from the blocking area of ​​the plurality of first openings 61 with respect to the incident path of the trivalent element.

[0512] That is, a process error of the plurality of second regions 15 due to the shading by the plurality of second openings 63 is different from a process error of the plurality of first regions 14 due to the shading by the plurality of first openings 61. Therefore, the absolute value of the second extension angle θ2 is preferably substantially equal to the absolute value of the first extension angle θ1. In this case, the process error of the plurality of second regions 15 is substantially identical to the process error of the plurality of first regions 14. This improves the accuracy of charge balancing.

[0513] For example, the first extension angle θ1 can be +45° ± 5° and the second extension angle θ2 can be -45° ± 5° (see Fig. 12A). The first extension angle θ1 can be, for example, +30° ± 5° and the second extension angle θ2 can be -30° ± 5° (see Fig.12B). The first extension angle θ1 can be, for example, +60° ± 5° and the second extension angle θ2 can be -60° ± 5° (see Fig. 12C).

[0514] After the trivalent element implantation step, lattice defects, etc., that have formed in the second layer 9 can be repaired by an annealing process simultaneously with the electrical activation of the trivalent element. The annealing temperature for the second layer 9 can be no less than 500°C and no more than 2000°C. Consequently, a plurality of second regions 15 are formed, and the second super junction structure SJ2 is formed simultaneously.

[0515] The plurality of second regions 15 are arranged at intervals in the second arrangement direction Da2 over the entire area of ​​the second layer 9 and are each formed to extend as a band in the second extension direction De2. That is, the plurality of second regions 15 are formed as stripes so that they intersect the plurality of device regions 55 and the plurality of provided cutting lines 56 in the second extension direction De2.

[0516] The annealing process related to the plurality of second regions 15 may also serve as the above-described annealing process for the plurality of first regions 14. In this case, the annealing process for the first regions 14 prior to the forming step of the second regions 15 may be omitted.

[0517] Next, it is determined whether or not a thickness adjustment step of the second layer 9 should be performed (step S15 in Fig. 41). In a case where the thickness of the second layer 9 is to be adjusted (step S15 in Fig. 41: YES), the second layer 9 is thinned from the upper end side (step S16 in Fig. 41).

[0518] The thickness adjustment step (thinning step) may include a step of partially removing the upper end portion of the second layer 9 by a grinding process. The grinding process may be a mechanical polishing process and / or a chemomechanical polishing process. The step of thinning the second layer 9 may include a step of partially removing the upper end portion of the second layer 9 by an etching process. The etching process may be a wet etching process and / or a dry etching process.

[0519] The thickness adjustment step may include a step of exposing the plurality of second regions 15 from the upper end of the second layer 9 (see also Fig. 27 to 30, etc.). That is, the thickness adjustment step may include a step of partially or completely removing the second gradually rising portion 20B from the plurality of second regions 15. If the thickness adjustment step is not to be performed (step S8 in Fig. 41: NO), this step is omitted.

[0520] Next, it is determined whether a step for forming the further super junction structure SJ on the second layer 9 should be performed or not (step S17 in Fig. 41). For example, in a case where a formation step of the third super junction structure SJ3 (see also Fig. 33) is carried out (step S17 in Fig. 41: YES), the third layer 27 is formed on the second layer 9, and the plurality of third regions 28 are formed in the third layer 27 by steps corresponding to steps S12 to S14 in Fig. 41 are identical (step S18 in Fig. 41).

[0521] Of course, before the step of forming the further super junction structure SJ, the plurality of intermediate regions 25 may be formed in the surface layer portion of the second layer 9 by a step which is identical to step S11 in Fig. 41 is identical (see also Fig. 25 and Fig. 26). In the case where the step of forming the further super junction structure SJ is not performed (step S17 in Fig. 41: NO), this step is omitted.

[0522] Next, a determination step is carried out as to whether a forming step of the upper layer 30 (see also Fig. 34) should be carried out or not (step S19 in Fig. 41). In the case where the forming step of the upper layer 30 is to be carried out (step S19 in Fig. 41: YES), the upper layer 30 is formed with the second layer 9 as a starting point by the epitaxial process (step S20 in Fig. 41). If the forming step of the upper layer 30 is not to be carried out (step S19 in Fig. 41: NO), this step is omitted.

[0523] Thereafter, the MIS structure 31, the plurality of field regions 38, the interlayer insulating film 40, the gate pad 45, the gate wiring 46, the source pad 47, the drain pad 48, etc. are formed (step S21 in Fig. 41).

[0524] Then, the wafer 50 is cut along the plurality of provided cutting lines 56. Portions of the plurality of first regions 14 positioned on the plurality of provided cutting lines 56 are exposed from the first side surface 5A (the third side surface 5C) as the plurality of first marks Mk1. In a case where the plurality of intermediate regions 25 are formed, a part of each of the plurality of intermediate regions 25 positioned on the plurality of provided cutting lines 56 is exposed as a part (the upper end portion) of each of the plurality of first marks Mk1 from the first side surface 5A (the third side surface 5C). Portions of the plurality of second regions 15 positioned on the plurality of provided cutting lines 56 are exposed as the plurality of second marks Mk2 from the second side surface 5B (the fourth side surface 5D).

[0525] Even in a case where the intermediate portion of the second region 15 is cut along the second extension direction De2, a part of the second region 15 is exposed as the first differential mark Md1 from the first side surface 5A (the third side surface 5C). Even in a case where the intermediate portion of the first region 14 is cut along the first extension direction De1, a part of the first region 14 is exposed as the second differential mark Md2 from the second side surface 5B (the fourth side surface 5D).

[0526] A dicing step of the wafer 50 may include a processing step of the wafer 50. In this case, the wafer 50 is cut along the plurality of provided cutting lines 56 with a dicing blade. Consequently, the chip 2 is formed with the first to fourth side surfaces 5A to 5D each formed from the ground surface.

[0527] The step of cutting the wafer 50 may include a step of cleaving the wafer 50. In this case, a plurality of modified layers (damaged layers) are formed along the plurality of designated cutting lines 56 inside the wafer 50 by a laser light irradiation method, and the wafer 50 is cleaved along the plurality of designated cutting lines 56 with the plurality of modified layers as starting points. Consequently, the chip 2 having the first to fourth side surfaces 5A to 5D, each formed of a cleavage surface, is formed.

[0528] In the case of the cleaving step of the wafer 50, the plurality of modified layers are preferably formed in a thickness range of the wafer 50 (the base layer 6) relative to a thickness range of the laminated portion 7. Specifically, the plurality of modified layers are preferably formed in the wafer 50 (the base layer 6) at intervals from the thickness range of the laminated portion 7 to the second wafer main surface 52 side of the wafer 50.

[0529] In this manufacturing method, the plurality of modified layers are formed (or remain) in portions of the first to fourth side surfaces 5A to 5D after cleavage, which are formed from the base layer 6. In this way, the plurality of modified layers can be prevented from overlapping with the structural pattern PT (the plurality of first marks Mk1 and the plurality of second marks Mk2). This improves the visibility of the structural pattern PT. Furthermore, electrical influences of the plurality of modified layers on the plurality of first regions 14 and the plurality of second regions 15 through the structural pattern PT are reduced.

[0530] When the cleaving step is performed, each of the first to fourth side surfaces 5A to 5D is formed from a cleavage surface and includes the plurality of modified layers. Therefore, the plurality of modified layers can be considered as one component of the SiC semiconductor device 1A (the chip 2).

[0531] The various determination steps described above (steps S2, S8, S10, S15, S17 and S19 in Fig. 41) can be prepared in advance at a stage of the preparation step of the wafer 50 (step S1 in Fig. 41). That is, the SiC semiconductor device 1A can be manufactured on a predetermined production line. A plurality of SiC semiconductor devices 1A are manufactured from the single wafer 50 through steps including the steps described above.

[0532] Fig. 45 is a plan view showing a SiC semiconductor device 1B according to a second embodiment. Fig. 46A is a cross-sectional view taken along line XLVIA-XLVIA in Fig. 45. Fig. 46B is a cross-sectional view taken along line XLVIB-XLVIB in Fig. 45. Fig. 47A is a plan view showing a layout example of the chip 2 (the first layer 8). Fig. 47B is a plan view showing a layout example of the chip 2 (the second layer 9). Fig. 48 is a perspective view showing the layout example of chip 2.

[0533] As in Fig. 45 to 48, the SiC semiconductor device 1B comprises, as in the case of the SiC semiconductor device 1A, the chip 2, the base layer 6, the laminated portion 7 (the first layer 8 and the second layer 9), the active region 10 and the outer peripheral region 11.

[0534] In this embodiment, the SiC semiconductor device 1B has an active area 71, an outer area 72, and first to fourth connection areas 73A to 73D formed in the first main area 3. The active area 71, the outer area 72, and the first to fourth connection areas 73A to 73D form an active mesa 74 in the first main area 3.

[0535] The active area 71 may be referred to as the "first surface portion," the outer surface 72 as the "second surface portion," the first to fourth connecting surfaces 73A to 73D as "connecting surface portions," and the active mesa 74 as the "mesa portion." The active area 71, the outer surface 72, and the first to fourth connecting surfaces 73A to 73D (i.e., the active mesa 74) may ...

Claims

[1] SiC semiconductor device, comprising: a SiC layer of a first conductivity type having a main surface; an active area located in an inner portion of the main surface; an outer peripheral region located in a peripheral edge portion of the main surface; and a pillar region of a second conductivity type having impurity regions formed in the SiC layer at an interval in the horizontal direction along the main surface and positioned in both the active region and the outer peripheral region. [2] SiC semiconductor component according to claim 1, wherein the SiC layer has a laminated structure comprising a first SiC layer of the first conductivity type and a second SiC layer of the first conductivity type laminated on the first SiC layer, and the column area has: first regions as the impurity regions formed in the first SiC layer at an interval in the horizontal direction and positioned in both the active region and the outer peripheral region; and second regions as the impurity regions formed in the second SiC layer at an interval in the horizontal direction and positioned in both the active region and the outer peripheral region. [3] SiC semiconductor component according to claim 2, wherein the first SiC layer has a first axial channel aligned along a lamination direction, the second SiC layer has a second axial channel aligned along the lamination direction, the first region extends along the first axial channel in the first SiC layer, and the second region extends along the second axial channel in the second SiC layer. [4] SiC semiconductor component according to claim 3, wherein the first region is formed from a single one of the impurity regions traversing an intermediate portion of the first SiC layer along the first axial channel, and the second region is formed from a single one of the impurity regions traversing an intermediate portion of the second SiC layer along the second axial channel. [5] The SiC semiconductor device according to any one of claims 2 to 4, wherein the second region has an extension portion that crosses a boundary portion between the first SiC layer and the second SiC layer and is positioned in the first SiC layer. [6] The SiC semiconductor device according to claim 2 or 5, wherein the first region is formed at an interval from an upper end toward a lower end side of the first SiC layer. [7] SiC semiconductor component according to one of claims 2 to 6, wherein the first region has a first peak at an upper end side of the first SiC layer and a first shallow gradient portion in which an impurity concentration gradually decreases at a low decreasing rate in a region closer to a lower end of the first SiC layer than the first peak, and the second region has a second peak at an upper end side of the second SiC layer and a second shallow gradient portion in which an impurity concentration gradually decreases at a low decreasing rate in a region closer to a lower end of the second SiC layer than the second peak. [8] SiC semiconductor component according to claim 7, wherein the first flat gradient portion comprises a thickness range of not less than 1 / 4 of the first range, and the second flat gradient section has a thickness range of not less than 1 / 4 of the second range. [9] SiC semiconductor component according to one of claims 2 to 8, wherein the first region extends in a first extension direction, and the second region extends in a second extension direction which is different from the first extension direction and intersects the first region. [10] The SiC semiconductor device according to claim 9, wherein the first extending direction is an m-axis direction or an a-axis direction of a crystal orientation of SiC. [11] The SiC semiconductor device according to claim 9, wherein the first extending direction is a direction other than an m-axis direction and an a-axis direction of a crystal orientation of SiC. [12] The SiC semiconductor device according to claim 11, wherein the second extending direction is a direction other than an m-axis direction of a crystal orientation of SiC. [13] The SiC semiconductor device according to claim 9, wherein the second extension direction is orthogonal to the first extension direction. [14] The SiC semiconductor device according to claim 9, wherein the second extension direction is not orthogonal to the first extension direction. [15] SiC semiconductor component according to one of claims 2 to 8, wherein the first regions extend in a first extension direction, and the second regions extend in a second extension direction that coincides with the first extension direction, and the first regions overlap in a thickness direction of the SiC layer. [16] SiC semiconductor device according to one of claims 1 to 15, further comprising: at least one field region formed in a surface layer portion of the main surface in the outer peripheral region and overlapping the pillar region in a thickness direction of the SiC layer. [17] SiC semiconductor component according to claim 16, wherein the column region is formed in a three-dimensional lattice shape by the impurity regions, and the field region is formed in a region on one side of the main surface in the outer peripheral region with respect to the column region having the three-dimensional lattice shape. [18] SiC semiconductor component according to claim 16, wherein the column regions are formed in a stripe shape by the impurity regions, and the field region in the region on the side of the main surface in the outer peripheral region with respect to the column regions is formed with the stripe shape. [19] The SiC semiconductor device according to any one of claims 16 to 18, wherein the field region has a portion intersecting the impurity regions in plan view and a portion extending along the impurity regions in plan view. [20] A SiC semiconductor device according to any one of claims 16 to 19, wherein the field regions are formed at an interval.

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