Semiconductor device and manufacturing method thereof

Abstract

To provide a semiconductor device and a manufacturing method thereof, capable of reducing a parasitic capacitance.SOLUTION: A semiconductor device includes a semiconductor part, first to third electrodes, and a control electrode. The first electrode is provided on a back surface of the semiconductor part. The second electrode is provided on a front surface of the semiconductor part at a side opposite to the back surface. The third electrode is located between the first electrode and the second electrode, so as to extend into the semiconductor part from the front surface side of the semiconductor part. The third electrode is electrically insulated from the semiconductor part via an insulating space formed between the semiconductor part and the third electrode. The control electrode includes a first portion extending between the semiconductor part and the third electrode from the front surface side of the semiconductor part, and a second portion that is provided between the second electrode and the third electrode and is connected to the first portion. The first portion of the control electrode faces the insulating space via the third electrode, the second portion extends between the insulating space and the second electrode.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The embodiments relate to a semiconductor device and a manufacturing method thereof. [Background technology]

[0002] Power control semiconductor devices are required to have reduced parasitic capacitance between electrodes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-162909 Summary of the Invention [Problem to be solved by the invention]

[0004] The embodiments provide a semiconductor device capable of reducing parasitic capacitance and a manufacturing method thereof. [Means for solving the problem]

[0005] The semiconductor device according to the embodiment includes a semiconductor portion, first to third electrodes, and a control electrode. The first electrode is provided on a back surface of the semiconductor portion, and the second electrode is provided on a front surface of the semiconductor portion opposite the back surface. The third electrode is located between the first electrode and the second electrode and extends from the front surface side of the semiconductor portion into the semiconductor portion. The third electrode is electrically insulated from the semiconductor portion via an insulating space between the semiconductor portion and the third electrode. The control electrode has a first portion extending from the front surface side of the semiconductor portion between the semiconductor portion and the third electrode, and a second portion provided between the second electrode and the third electrode and connected to the first portion. The first portion of the control electrode faces the insulating space via the third electrode, and the second portion extends between the insulating space and the second electrode. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic cross-sectional view showing a semiconductor device according to an embodiment; [Figure 2] 1 is a schematic plan view showing a semiconductor device according to an embodiment; [Figure 3] FIG. 10 is a schematic plan view showing a semiconductor device according to a modified example of the embodiment. [Figure 4] FIG. 10 is a schematic plan view showing a semiconductor device according to another modified example of the embodiment. [Figure 5] 5A to 5C are schematic cross-sectional views showing a manufacturing process of the semiconductor device according to the embodiment. [Figure 6] 6A to 6C are schematic cross-sectional views showing the manufacturing process following FIG. 5. [Figure 7] 7A to 7C are schematic cross-sectional views showing the manufacturing process following FIG. 6. [Figure 8] 8A to 8C are schematic cross-sectional views showing the manufacturing process following FIG. 7. [Figure 9] 9A to 9C are schematic cross-sectional views showing the manufacturing process following FIG. 8. [Figure 10] 10A to 10C are schematic cross-sectional views showing the manufacturing process following FIG. 9. [Figure 11] FIG. 10 is a schematic cross-sectional view showing a semiconductor device according to yet another modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments will be described with reference to the drawings. Identical parts in the drawings are assigned the same numbers, and detailed descriptions thereof will be omitted as appropriate, and different parts will be described. Note that the drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between parts, etc., are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be expressed differently depending on the drawing.

[0008] Furthermore, the arrangement and configuration of each part will be explained using the X-axis, Y-axis, and Z-axis shown in each figure. The X-axis, Y-axis, and Z-axis are mutually perpendicular and represent the X-direction, Y-direction, and Z-direction, respectively. In addition, the Z-direction may be explained as upward and the opposite direction as downward.

[0009] 1 is a schematic cross-sectional view showing a semiconductor device 1 according to an embodiment. The semiconductor device 1 is, for example, a trench gate MOS transistor. Fig. 1 shows the structure of the trench gate.

[0010] As shown in FIG. 1, the semiconductor device 1 includes a semiconductor portion 10, a first electrode 20, a second electrode 30, a control electrode 40, and a third electrode 50.

[0011] The semiconductor portion 10 is made of, for example, silicon. The semiconductor portion 10 is located between a first electrode 20 and a second electrode 30. The first electrode 20 is, for example, a drain electrode. The second electrode 30 is, for example, a source electrode. The first electrode 20 is provided on a back surface 10B of the semiconductor portion 10. The second electrode 30 is provided on a front surface 10F of the semiconductor portion 10 opposite the back surface 10B. The semiconductor portion 10 has a gate trench GT provided on the front surface 10F side.

[0012] The control electrode 40 and the third electrode 50 are located between the first electrode 20 and the second electrode 30. The control electrode 40 is, for example, a gate electrode. The third electrode 50 is a so-called field plate electrode. The third electrode 50 is electrically connected to the second electrode 30, for example, at a terminal portion (not shown).

[0013] The control electrode 40 has a first portion 40A located inside the gate trench GT and a second portion 40B located above the opening of the gate trench GT. The second portion 40B is connected to the first portion 40A.

[0014] The third electrode 50 extends in the gate trench GT in a direction from the first electrode 20 toward the second electrode 30. The second portion 40B of the control electrode 40 is located between the second electrode 30 and the third electrode 50. The first portion 40A of the control electrode 40 is located between the semiconductor portion 10 and the third electrode 50. A first distance D1 from the first electrode 20 to the third electrode 50 is shorter than a second distance D2 from the first electrode 20 to the first portion 40A of the control electrode 40.

[0015] A first insulating film 43 is provided between the semiconductor portion 10 and the first portion 40A of the control electrode 40. The first insulating film 43 is, for example, a gate insulating film, and electrically insulates the control electrode 40 from the semiconductor portion 10. The first insulating film 43 covers the lower end of the first portion 40A of the control electrode 40 and extends between the first portion 40A and the third electrode 50, and between the second portion 40B and the upper end of the third electrode 50. The first insulating film 43 electrically insulates the control electrode 40 from the third electrode 50. The first insulating film 43 is, for example, a silicon oxide film.

[0016] A second insulating film 45 is provided between the second electrode 30 and the control electrode 40. The second insulating film 45 electrically insulates the control electrode 40 from the second electrode 20. The second insulating film 45 is, for example, an interlayer insulating film. The second insulating film 45 is, for example, a silicon oxide film.

[0017] The third electrode 50 faces the semiconductor portion 10 in the gate trench GT via an insulating space IS. The insulating space IS electrically insulates the third electrode 50 from the semiconductor portion 10. The insulating space IS has, for example, a lower dielectric constant than the dielectric constant of the first insulating film 43. The insulating space IS is, for example, a cavity in the gate trench GT, a so-called air gap. The insulating space IS may also be filled with an insulating material with a low dielectric constant, for example, a low-k material.

[0018] The insulating space IS includes a first end UE1 facing the first portion 40A of the control electrode 40 and a second end UE2 facing the second portion 40B of the control electrode 40. The first end UE1 faces the first portion 40A of the control electrode 40 via a first insulating film 43. The second end UE2 faces the second portion 40B of the control electrode 40. The first insulating film 43 extends between the second portion 40B of the control electrode 40 and the second end UE2 of the insulating space IS.

[0019] The first portion 40A of the control electrode 40 faces the insulating space IS via the third electrode 50. The upper end of the third electrode 50 is located, for example, between the first portion 40A of the control electrode 40 and the second end UE2 of the insulating space IS.

[0020] An opening EC that communicates with the insulating space IS is provided between the second portion 40B of the control electrode 40 and the semiconductor portion 10. The second insulating film 45 is provided to close the opening EC. In other words, an opening EC that can be closed by the second insulating film 45 is provided between the second portion 40B and the semiconductor portion 10.

[0021] 1, the semiconductor section 10 includes a first semiconductor layer 11 of a first conductivity type, a second semiconductor layer 13 of a second conductivity type, a third semiconductor layer 15 of the first conductivity type, a fourth semiconductor layer 17 of the second conductivity type, and a fifth semiconductor layer 19 of the first conductivity type. In the following description, the first conductivity type will be referred to as n-type and the second conductivity type as p-type, but this is not intended to be limiting.

[0022] The first semiconductor layer 11 is, for example, an n-type drift layer. The first semiconductor layer 11 extends between the first electrode 20 and the second electrode 30. The gate trench GT has a depth that reaches from the surface 10F side of the semiconductor portion 10 to the first semiconductor layer 11. The first semiconductor layer 11 faces the third electrode 50 with an insulating space IS interposed therebetween.

[0023] The second semiconductor layer 13 is, for example, a p-type body layer. The second semiconductor layer 13 is provided between the first semiconductor layer 11 and the second electrode 30. The second semiconductor layer 13 faces the first portion 40A of the control electrode 40 via the first insulating film 43. The second semiconductor layer 13 also includes a portion facing the insulating space IS.

[0024] The third semiconductor layer 15 is, for example, an n-type source layer. The third semiconductor layer 15 is partially provided on the second semiconductor layer 13, between the second semiconductor layer 13 and the second electrode 30. The third semiconductor layer 15 includes a portion in contact with the first insulating film 43 and another portion facing the insulating space IS. An opening EC communicating with the insulating space IS is provided between the other portion of the third semiconductor layer 15 and the second portion 40B of the control electrode 40. The third semiconductor layer 15 is provided so as to overlap an end of the second portion 40B in a direction from the first electrode 20 toward the second electrode 30, for example, in the Z direction.

[0025] The fourth semiconductor layer 17 is, for example, a p-type contact layer. The fourth semiconductor layer 17 is provided partially on the second semiconductor layer 13 between the second semiconductor layer 13 and the second electrode 30. The fourth semiconductor layer 17 contains a higher concentration of second conductivity type impurities than the concentration of second conductivity type impurities in the second semiconductor layer 13. The fourth semiconductor layer 17 is provided, for example, between a portion of the third semiconductor layer 15 facing the first insulating film 43 and another portion facing the insulating space IS.

[0026] The second electrode 30 is in contact with and electrically connected to the third semiconductor layer 15 and the fourth semiconductor layer 17. The second electrode 30 is electrically connected to the second semiconductor layer 13 via the fourth semiconductor layer 17.

[0027] The fifth semiconductor layer 19 is, for example, an n-type drain layer. The fifth semiconductor layer 19 is provided between the first semiconductor layer 11 and the first electrode 20. The fifth semiconductor layer 19 contains a first conductivity type impurity at a concentration higher than the concentration of the first conductivity type impurity in the first semiconductor layer. The first electrode 20 is in contact with and electrically connected to the fifth semiconductor layer 19. The first electrode 20 is electrically connected to the first semiconductor layer 11 via the fifth semiconductor layer 19.

[0028] In the semiconductor device 1, by providing an insulating space IS in the gate trench GT, the parasitic capacitance (source-drain capacitance) between the first electrode 20 and the third electrode 50 can be reduced. Furthermore, by arranging the control electrode 40 on only one side of the third electrode 50, the parasitic capacitance between the control electrode 40 and the third electrode 50 and between the second electrode 30 and the control electrode 40, i.e., the so-called gate capacitance, can be reduced. Furthermore, the width of the gate trench GT in the X direction can be narrowed while maintaining the parasitic capacitance between the first electrode 20 and the third electrode 50 at a predetermined value or less. This makes it possible to increase the density of the gate trenches GT on the surface 10F of the semiconductor portion 10. As a result, the effective gate width can be widened, thereby reducing the on-resistance.

[0029] Figures 2(a) and (b) are schematic plan views showing the semiconductor device 1 according to the embodiment. Figure 2(a) is a plan view showing the AA cross section shown in Figure 1. Figure 2(b) is a plan view showing the BB cross section shown in Figure 1. Note that Figure 1 shows a cross section taken along line CC shown in Figure 2(a).

[0030] 2(a), the second portions 40B of the control electrodes 40 extend, for example, at equal intervals in the Y direction. The first portions of the control electrodes 40 indicated by dashed lines in the figure also extend in the Y direction. The multiple control electrodes 40 are aligned in the X direction.

[0031] 2(b), the gate trench GT extends in the Y direction, and the insulating space IS also extends in the Y direction. The third electrode 50 is located between the first portion 40A of the control electrode 40 and the insulating space IS.

[0032] Figures 3(a) and (b) are schematic plan views showing a semiconductor device 1 according to a modified example of the embodiment. Figure 3(a) is a plan view showing the AA cross section shown in Figure 1. Figure 3(b) is a plan view showing the BB cross section shown in Figure 1. Note that Figure 1 shows a cross section taken along line DD shown in Figure 3(a).

[0033] 3(a) and 3(b), the control electrode 40 includes a plurality of first portions 40A. The plurality of first portions 40A are arranged at intervals in the extension direction of the gate trench GT, for example, in the Y direction.

[0034] 3(a), the second portion 40B of the control electrode 40 includes a main portion 40BM extending in the Y direction and a plurality of extension portions 40BP protruding in the X direction and the opposite direction. The main portion 40BM is provided on the third electrode 50.

[0035] As shown in FIG. 3(b), the first portions 40A of the control electrode 40 are arranged on both sides of the third electrode 50. An insulating space IS is provided between adjacent first portions 40A in the Y direction. Each of the multiple first portions 40A is provided to face the insulating space IS via the third electrode 50 in the X direction or the opposite direction. An extension 40BP of the second portion 40B (see FIG. 3(a)) covers the insulating space IS between adjacent first portions 40A in the Y direction.

[0036] Figures 4(a) and (b) are schematic plan views showing a semiconductor device 1 according to another modified example of the embodiment. Figure 4(a) is a plan view showing the AA cross section shown in Figure 1. Figure 4(b) is a plan view showing the BB cross section shown in Figure 1. Note that Figure 1 shows a cross section taken along the EE line shown in Figure 4(a).

[0037] In this example as well, the control electrode 40 includes a plurality of first portions 40 A. The plurality of first portions 40 A are arranged at intervals from each other in the extension direction of the gate trench GT, for example, in the Y direction.

[0038] 4(a), the second portion 40B of the control electrode 40 includes a main portion 40BM extending in the Y direction and a plurality of extension portions 40BP protruding in the X direction and the opposite direction. The main portion 40BM is provided on the third electrode 50.

[0039] As shown in FIG. 4(b), the first portions 40A of the control electrode 40 are arranged on both sides of the third electrode 50. An insulating space IS is provided between adjacent first portions 40A in the Y direction. The insulating space IS is provided to face the first portion 40A in the X direction or the opposite direction, with the third electrode 50 interposed therebetween. The extension portion 40BP of the second portion 40B (see FIG. 4(a)) covers the insulating space IS between adjacent first portions 40A in the Y direction.

[0040] In this example, the length 40L in the Y direction of the first portion 40A of the control electrode 40 is longer than the interval 40S between the first portions 40A adjacent to each other in the Y direction, thereby making it possible to increase the width of the gate channel.

[0041] Next, a method for manufacturing the semiconductor device 1 will be described with reference to Figures 5(a) to 10(b). Figures 5(a) to 10(b) are schematic cross-sectional views showing the manufacturing process of the semiconductor device 1 according to the embodiment.

[0042] As shown in FIG. 5(a), a gate trench GT is formed on the front surface 100F side of the semiconductor wafer 100. The semiconductor wafer 100 is, for example, an n-type silicon wafer. The semiconductor wafer 100 contains, for example, a second conductivity type impurity at the same concentration as the first conductivity type impurity in the first semiconductor layer 11. The gate trench GT is formed by selectively etching the semiconductor wafer 100 by anisotropic reactive ion etching (RIE), for example, using an etching mask (not shown).

[0043] As shown in FIG. 5(b), a sacrificial film 103 is formed inside the gate trench GT, leaving a first space SP1 therein and covering the inner surface thereof. The sacrificial film 103 covers, for example, the front surface 100F of the semiconductor wafer 100. The sacrificial film 103 is, for example, a silicon nitride film. The sacrificial film 103 is formed by, for example, CVD (Chemical Vapor Deposition).

[0044] 5(c), a conductive film 105 is formed to fill the first space SP1 in the gate trench GT. The conductive film 105 is, for example, polysilicon having conductivity. The conductive film 105 is formed on the sacrificial film 103 by, for example, using CVD.

[0045] 6(a), the conductive film 105 is removed, leaving a portion located inside the gate trench GT. The conductive film 105 is removed by, for example, isotropic dry etching. The conductive film 105 left inside the gate trench GT becomes the third electrode 50.

[0046] 6(b), the sacrificial film 103 formed on the front surface 100F of the semiconductor wafer 100 is removed, leaving a portion formed inside the gate trench GT. The sacrificial film 103 is removed by, for example, CMP (Chemical Mechanical Polishing).

[0047] As shown in FIG. 6(c), a portion of the sacrificial film 103 in the gate trench GT is removed. The sacrificial film 103 is selectively removed using, for example, an etching mask EM1. As a result, a second space SP2 is formed on the opening side of the gate trench GT. The second space SP2 is provided on one side of the upper end of the third electrode 50. The second space SP2 faces the portion of the sacrificial film 103 protected by the etching mask EM1, via the upper end of the third electrode 50. The etching mask EM1 is, for example, photoresist.

[0048] As shown in FIG. 7(a), a first insulating film 43 is formed to cover the front surface 100F of the semiconductor wafer 100. The first insulating film 43 covers the inner surface of the second space SP2 in the gate trench GT. The first insulating film 43 is formed using, for example, CVD. The first insulating film 43 may have a two-layer structure including, for example, an initial film formed by thermally oxidizing the exposed surface of the semiconductor wafer 100 and a CVD film deposited thereon.

[0049] 7(b), a conductive film 107 is formed on the first insulating film 43. The conductive film 107 is, for example, polysilicon having conductivity. The conductive film 107 is formed using, for example, CVD so as to fill the second space SP2.

[0050] As shown in Fig. 7(c), an etching mask EM2 is formed on the conductive film 107. The etching mask EM2 has the same planar shape as the planar shape of the second portion 40B of the control electrode 40 (see Figs. 2(a), 3(a), and 4(a)). The etching mask EM2 is, for example, a photoresist.

[0051] As shown in FIG. 8(a), the conductive film 107 is selectively removed using an etching mask EM2. The conductive film 107 is removed by, for example, isotropic dry etching or wet etching. The conductive film 107 remaining on the opening side of the gate trench GT becomes the control electrode 40. It is preferable that one end of the conductive film 107 is located within the gate trench GT and the other end is located above, for example, the front surface 100F of the semiconductor wafer 100.

[0052] As shown in FIG. 8(b), after removing the etching mask EM2, the second semiconductor layer 13 and the third semiconductor layer 15 are formed in this order. The second semiconductor layer 13 is formed by ion-implanting a second conductivity type impurity, for example, boron (B), into the front surface 100F side of the semiconductor wafer 100. The ion-implanted second conductivity type impurity is activated by heat treatment and diffused to a predetermined depth. The third semiconductor layer 15 is formed by ion-implanting a first conductivity type impurity, for example, phosphorus (P) or arsenic (As), into the front surface 100F side of the semiconductor wafer 100. The ion-implanted first conductivity type impurity is activated by heat treatment.

[0053] 8(c), the first insulating film 43 is selectively removed using an etching mask EM3. The etching mask EM3 is formed so as to cover the first portion 40A of the control electrode 40. The etching mask EM3 is, for example, a photoresist.

[0054] The first insulating film 43 is removed by, for example, wet etching. The first insulating film 43 is also partially removed by side etching under the etching mask EM3 and the second portion 40B of the control electrode 40. As a result, an opening EC communicating with the sacrificial film 103 is formed between the third semiconductor layer 13 and the second portion 40B of the control electrode 40. The opening width of the opening EC in the Z direction is the same as the film thickness of the first insulating film 43 in the Z direction. The opening width of the opening EC is, for example, 50 to 100 nm.

[0055] As shown in FIG. 9(a), the sacrificial film 103 inside the gate trench GT is removed to form an insulating space IS. The sacrificial film 103 is removed by an etching solution or etching gas supplied through the opening EC. The third electrode 50 in the gate trench GT is held by the control electrode 40 via the first insulating film 43. A cavity that becomes the insulating space IS is formed inside the gate trench GT.

[0056] 9(b), a second insulating film 45 is formed on the front surface side of the semiconductor wafer 100. The second insulating film 45 is formed by using, for example, CVD. The second insulating film 45 is, for example, a silicon oxide film.

[0057] In this example, the opening width of the opening EC communicating with the insulating space IS is the same as the film thickness of the first insulating film 43, so the opening EC can be easily closed by the second insulating film 45. In other words, the insulating space IS is sealed by the second insulating film 45.

[0058] 10(a), the second insulating film 45 is selectively removed using an etching mask EM4 to form a contact hole CH. The contact hole CH communicates with the third semiconductor layer 15. That is, the third semiconductor layer 15 is exposed at the bottom of the contact hole CH.

[0059] 10(b), a second conductivity type impurity, for example, boron (B), is ion-implanted into the front surface 100F side of the semiconductor wafer 100 through the contact hole CH (see FIG. 10(a)) to form a fourth semiconductor layer 17. At this time, a sufficient dose of the second conductivity type impurity is ion-implanted to partially invert the third semiconductor layer 15 to the second conductivity type.

[0060] Furthermore, the ion-implanted second conductivity type impurities are activated by heat treatment to form fourth semiconductor layer 17, and then second insulating film 45 is etched to expand the width of the contact hole in the X direction and expose third semiconductor layer 15.

[0061] Next, a second electrode 30 is formed on the front surface 100F side of the semiconductor wafer 100. The second electrode 30 is a metal film formed by, for example, sputtering. The second electrode 30 covers the control electrode 40 via a second insulating film 45. The second electrode 30 also contacts and is electrically connected to the third semiconductor layer 15 and the fourth semiconductor layer 17 at the bottom surfaces of the contact holes CH.

[0062] Furthermore, the back side (not shown) of the semiconductor wafer 100 is thinned to a predetermined thickness by, for example, etching or grinding, and then the first electrode 20 (see FIG. 1) is formed. At this time, the fifth semiconductor layer 19 is formed, for example, by ion-implanting first conductivity type impurities into the back side. Alternatively, the semiconductor wafer 100 may be, for example, an epitaxial wafer having a silicon substrate containing a high concentration of first conductivity type impurities and a first semiconductor layer 11 containing a low concentration of first conductivity type impurities epitaxially grown on the substrate.

[0063] In the above manufacturing method, a low dielectric constant film (Low-k) may be used instead of the sacrificial film 103. In that case, the low dielectric constant film is not finally removed but is left inside the gate trench GT as an insulating material that fills the insulating space IS.

[0064] 11 is a schematic cross-sectional view showing a semiconductor device 2 according to yet another modified example of the embodiment, which shows a cross section corresponding to the cross section shown in FIG.

[0065] 11 , in this example, an insulating space IS is provided inside the gate trench GT. A first portion 40A of the control electrode 40 and a third electrode 50 are also provided in the gate trench GT. A second portion of the control electrode 40 is provided above the opening of the gate trench GT and is located between the second electrode 30 and the third electrode 50.

[0066] The semiconductor device 2 further includes a third insulating film 12 and a fourth insulating film 53. The third insulating film 12 is formed to cover the inner surface of the gate trench GT. The fourth insulating film 53 is provided to cover the third electrode 50. An insulating space IS is provided between the third insulating film 12 and the fourth insulating film 53.

[0067] The third insulating film 12 and the fourth insulating film 53 are formed, for example, by thermally oxidizing the inner surface of the gate trench GT and the third electrode 50 before closing the insulating space IS with the second insulating film 45. The third insulating film 12 and the fourth insulating film 53 are, for example, silicon oxide films. Alternatively, the third insulating film 12 may be formed by thermally oxidizing the semiconductor wafer 100 after the gate trench GT is formed and before the sacrificial film 103 (see FIG. 5(b)) is formed.

[0068] Forming the third insulating film 12 can stabilize the surface state on the inner surface of the gate trench GT. Furthermore, forming the fourth insulating film 53 can suppress, for example, the release of impurities from the conductive polysilicon that forms the third electrode 30. This can stabilize the characteristics of the semiconductor device 2 and improve its reliability.

[0069] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims.

[0070] (Appendix 1) A semiconductor part; a first electrode provided on a rear surface of the semiconductor portion; a second electrode provided on a surface of the semiconductor portion opposite to the back surface; a third electrode located between the first electrode and the second electrode, extending from the front surface side of the semiconductor portion into the semiconductor portion, and electrically insulated from the semiconductor portion via an insulating space between the semiconductor portion and the third electrode; a control electrode having a first portion extending from the front surface side of the semiconductor portion between the semiconductor portion and the third electrode, and a second portion provided between the second electrode and the third electrode and connected to the first portion, wherein the first portion faces the insulating space via the third electrode, and the second portion extends between the insulating space and the second electrode; A semiconductor device comprising: (Appendix 2) 2. The semiconductor device according to claim 1, wherein a first distance from the first electrode to the control electrode is longer than a second distance from the first electrode to the third electrode. (Appendix 3) 3. The semiconductor device according to claim 1, wherein the control electrode includes a plurality of the first portions spaced apart from one another. (Appendix 4) a first insulating film provided between the semiconductor portion and the control electrode, electrically insulating the control electrode from the semiconductor portion; 4. The semiconductor device according to claim 1, wherein the insulating space has a dielectric constant smaller than the dielectric constant of the first insulating film. (Appendix 5) the semiconductor portion includes a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, and a third semiconductor layer of the first conductivity type; the first semiconductor layer extends between the first electrode and the second electrode, the third electrode extends into the first semiconductor layer and faces the first semiconductor layer across the insulating space; the second semiconductor layer is provided between the first semiconductor layer and the second electrode, and faces the first portion of the control electrode via the first insulating film; 5. The semiconductor device according to claim 4, wherein the third semiconductor layer is provided between the second semiconductor layer and the second electrode so as to be in contact with the first insulating film. (Appendix 6) 6. The semiconductor device according to claim 5, wherein the second semiconductor layer includes a portion facing the insulating space. (Appendix 7) 7. The semiconductor device according to claim 4, wherein the first insulating film extends between the control electrode and the third electrode and electrically insulates the control electrode from the third electrode. (Appendix 8) 8. The semiconductor device according to claim 1, further comprising a second insulating film provided between the second electrode and the control electrode, electrically insulating the control electrode from the second electrode. (Appendix 9) the insulating space has an end portion located on the front surface side of the semiconductor portion between the semiconductor portion and an upper end of the third electrode, an upper end of the third electrode is located between the first portion of the control electrode and an end of the insulating space; 9. The semiconductor device according to claim 8, wherein the second insulating film is provided so as to close an opening between the control electrode and the semiconductor portion that communicates with the end of the insulating space. (Appendix 10) 10. The semiconductor device according to claim 9, wherein the insulating space is a cavity provided between the semiconductor portion and the third electrode. (Appendix 11) 11. The semiconductor device according to claim 9, wherein the first insulating film extends between the control electrode and the end of the insulating space. (Appendix 12) a third insulating film provided between the insulating space and the semiconductor portion; a fourth insulating film provided between the insulating space and the third electrode; 12. The semiconductor device according to claim 1, further comprising: [Explanation of symbols]

[0071] 1, 2...semiconductor device, 10...semiconductor portion, 10B...rear surface, 10F, 100F...surface, 11...first semiconductor layer, 12...third insulating film, 13...second semiconductor layer, 15...third semiconductor layer, 17...fourth semiconductor layer, 19...fifth semiconductor layer, 20...first electrode, 30...second electrode, 40...control electrode, 40A...first portion, 40B...second portion, 40BM...main portion, 40BP...extension portion, 40L...length, 40S...spacing, 43...first insulating film, 45...second insulating film, 50...third electrode, 53...fourth insulating film, 100...semiconductor wafer, 103...sacrificial film, 105...conductive film, 107...conductive film, CH...contact hole, D1...first distance, D2...second distance, EC...opening, EM1, EM2, EM3, EM4...etching mask, GT...gate trench, IS...insulating space, SP1, SP2...space, UE1...first end, UE2...second end

Claims

1. A semiconductor part; a first electrode provided on a rear surface of the semiconductor portion; a second electrode provided on a surface of the semiconductor portion opposite to the back surface; a third electrode located between the first electrode and the second electrode, extending from the front surface side of the semiconductor portion into the semiconductor portion, and electrically insulated from the semiconductor portion via an insulating space between the semiconductor portion and the third electrode; a control electrode having a first portion extending from the front surface side of the semiconductor portion between the semiconductor portion and the third electrode, and a second portion provided between the second electrode and the third electrode and connected to the first portion, wherein the first portion faces the insulating space via the third electrode, and the second portion extends between the insulating space and the second electrode; Equipped with the first portion of the control electrode is provided on one side of the third electrode in a direction perpendicular to a direction from the first electrode toward the second electrode, a distance between an upper end of a portion of the insulating space that is arranged on one side of the third electrode and the first electrode is shorter than a distance between an upper end of a portion of the insulating space that is arranged on the other side of the third electrode and the first electrode.

2. 2. The semiconductor device according to claim 1, wherein a first distance from the first electrode to the control electrode is longer than a second distance from the first electrode to the third electrode.

3. a first insulating film provided between the semiconductor portion and the control electrode, electrically insulating the control electrode from the semiconductor portion; 2. The semiconductor device according to claim 1, wherein the dielectric constant of said insulating space is smaller than the dielectric constant of said first insulating film.

4. 4. The semiconductor device according to claim 3, wherein the first insulating film extends between the control electrode and the third electrode, and electrically insulates the control electrode from the third electrode.

5. A semiconductor part; a first electrode provided on a rear surface of the semiconductor portion; a second electrode provided on a surface of the semiconductor portion opposite to the back surface; a third electrode located between the first electrode and the second electrode, extending from the front surface side of the semiconductor portion into the semiconductor portion, and electrically insulated from the semiconductor portion via an insulating space between the semiconductor portion and the third electrode; a control electrode having a first portion extending from the front surface side of the semiconductor portion between the semiconductor portion and the third electrode, and a second portion provided between the second electrode and the third electrode and connected to the first portion, wherein the first portion faces the insulating space via the third electrode, and the second portion extends between the insulating space and the second electrode; Equipped with The control electrode includes a plurality of the first portions spaced apart from one another.

6. A semiconductor part; a first electrode provided on a rear surface of the semiconductor portion; a second electrode provided on a surface of the semiconductor portion opposite to the back surface; a third electrode located between the first electrode and the second electrode, extending from the front surface side of the semiconductor portion into the semiconductor portion, and electrically insulated from the semiconductor portion via an insulating space between the semiconductor portion and the third electrode; a control electrode having a first portion extending from the front surface side of the semiconductor portion between the semiconductor portion and the third electrode, and a second portion provided between the second electrode and the third electrode and connected to the first portion, wherein the first portion faces the insulating space via the third electrode, and the second portion extends between the insulating space and the second electrode; a first insulating film provided between the semiconductor portion and the control electrode, electrically insulating the control electrode from the semiconductor portion; Equipped with the semiconductor portion includes a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, and a third semiconductor layer of the first conductivity type; the first semiconductor layer extends between the first electrode and the second electrode, the third electrode extends into the first semiconductor layer and faces the first semiconductor layer across the insulating space; the second semiconductor layer is provided between the first semiconductor layer and the second electrode, and faces the first portion of the control electrode via the first insulating film; the third semiconductor layer is provided between the second semiconductor layer and the second electrode so as to be in contact with the first insulating film; The second semiconductor layer includes a portion facing the insulating space.

7. A semiconductor part; a first electrode provided on a rear surface of the semiconductor portion; a second electrode provided on a surface of the semiconductor portion opposite to the back surface; a third electrode located between the first electrode and the second electrode, extending from the front surface side of the semiconductor portion into the semiconductor portion, and electrically insulated from the semiconductor portion via an insulating space between the semiconductor portion and the third electrode; a control electrode having a first portion extending from the front surface side of the semiconductor portion between the semiconductor portion and the third electrode, and a second portion provided between the second electrode and the third electrode and connected to the first portion, wherein the first portion faces the insulating space via the third electrode, and the second portion extends between the insulating space and the second electrode; a first insulating film provided between the semiconductor portion and the control electrode, electrically insulating the control electrode from the semiconductor portion; a second insulating film provided between the second electrode and the control electrode, electrically insulating the control electrode from the second electrode; Equipped with the insulating space has an end portion located on the front surface side of the semiconductor portion between the semiconductor portion and an upper end of the third electrode, an upper end of the third electrode is located between the first portion of the control electrode and an end of the insulating space; The second insulating film is provided so as to close an opening between the control electrode and the semiconductor portion that communicates with the end of the insulating space.

8. 8. The semiconductor device according to claim 7, wherein the insulating space is a cavity provided between the semiconductor portion and the third electrode.

9. 8. The semiconductor device according to claim 7, wherein the first insulating film extends between the control electrode and the end of the insulating space.

10. a third insulating film provided between the insulating space and the semiconductor portion; a fourth insulating film provided between the insulating space and the third electrode; The semiconductor device according to claim 1 , further comprising:

11. A semiconductor part; a first electrode provided on a rear surface of the semiconductor portion; a second electrode provided on a surface of the semiconductor portion opposite to the back surface; a third electrode located between the first electrode and the second electrode, extending from the front surface side of the semiconductor portion into the semiconductor portion, and electrically insulated from the semiconductor portion via an insulating space between the semiconductor portion and the third electrode; a control electrode having a plurality of first portions extending from the front surface side of the semiconductor portion between the semiconductor portion and the third electrode, and a second portion provided between the second electrode and the third electrode and connected to the plurality of first portions, wherein the plurality of first portions each face the insulating space via the third electrode, and the second portion extends between the insulating space and the second electrode; Equipped with a semiconductor device in which the plurality of first portions of the control electrode are aligned in an extension direction of the third electrode along the surface of the semiconductor portion, and the second portion of the control electrode has an extension portion connected to each of the plurality of first portions.

12. The semiconductor device according to claim 11 , wherein the plurality of first portions of the control electrode are aligned in the extending direction on both sides of the third electrode.

13. A trench is formed on the front surface side of the semiconductor wafer, forming a sacrificial film covering an inner surface of the trench while leaving a first space in the trench; forming an electrode in the first space, the electrode extending from an opening side of the trench into the trench; a control electrode having a first portion extending between the semiconductor wafer and the electrode and a second portion provided on an opening side of the trench and covering the electrode and the sacrificial film, the sacrificial film having a first end located below the first portion of the control electrode and a second end facing the second portion of the control electrode, and an upper end of the electrode located between the first portion of the control electrode and the second end of the sacrificial film; a second portion of the control electrode formed on the second substrate and a second portion of the control electrode formed on the second substrate;

14. forming a first insulating film between the control electrode and the semiconductor wafer and between the control electrode and the electrode, the first insulating film electrically insulating the control electrode from the semiconductor wafer and the electrode; the first insulating film extends between the second portion of the control electrode and the second end of the sacrificial film, and also between the second portion of the control electrode and the semiconductor wafer; 14. The manufacturing method according to claim 13, wherein the opening between the second portion of the control electrode and the semiconductor wafer is formed by selectively removing the first insulating film.

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