Semiconductor device and method for manufacturing a semiconductor device

Abstract

To suppress unevenness in the breakdown voltage of semiconductor devices.SOLUTION: Provided is a semiconductor device comprising a semiconductor substrate having a bulk doping region, an active part, and an edge termination structural part. The edge termination structural part has a first high concentration region of a first conductive type, the donor concentration of which is higher than the doping concentration of the bulk donor, the first high concentration region having a hydrogen peak part, and a second high concentration region of the first conductive type, in which the donor concentration in at least a partial region of the edge termination structural part including a section in contact with the active part, from the depth position of the hydrogen peak part to the underside of the semiconductor substrate, is higher than the doping concentration of the bulk donor, and the doping concentration is higher than that in the bulk doping region. A guard ring of a second conductive type is provided on the upper side of the semiconductor substrate of the edge termination structural part, and a well region is provided. The second high concentration region is adjacent closer to an end part side of the semiconductor substrate than the well region or the one or more guard rings.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] This invention relates to a semiconductor device and a method for manufacturing a semiconductor device. [Background technology]

[0002] Conventionally, a structure is known in which a P-type guard ring is provided on the outer periphery of an N-type semiconductor substrate on which semiconductor elements such as IGBTs (insulated-gate bipolar transistors) are formed, thereby improving the breakdown voltage (see, for example, Patent Document 1). Patent Document 1: Japanese Patent Application Laid-Open No. 8-167715 [Overview of the project] [Problems that the invention aims to solve]

[0003] It is preferable that semiconductor devices have small variations in withstand voltage. [Means for solving the problem]

[0004] To solve the above problems, in a first embodiment of the present invention, a semiconductor substrate is provided having a bulk doping region of the first conductivity type in which a bulk donor of the first conductivity type is distributed throughout and the doping concentration is the same as the concentration of the bulk donor; an active portion is provided on the semiconductor substrate; and an edge termination structure is provided on the semiconductor substrate and is provided on the upper surface of the semiconductor substrate between the active portion and the edge of the semiconductor substrate, wherein the edge termination structure has a first high-concentration region of the first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate in which the donor concentration is higher than the doping concentration of the bulk donor; the upper surface of the first high-concentration region is located on the upper surface side of the semiconductor substrate; the lower surface of the first high-concentration region is located on the lower surface side of the semiconductor substrate; and the first high-concentration region is located on the upper surface side of the semiconductor substrate, and the hydrogen concentration distribution in the depth direction is The semiconductor device has a hydrogen peak portion where the hydrogen concentration is at its peak, and in at least a portion of the edge termination structure, including the portion in contact with the active portion, the donor concentration from the depth position of the hydrogen peak portion to the lower surface of the semiconductor substrate is higher than the doping concentration of the bulk donor, and the edge termination structure has a second high-concentration region of a first conductivity type with a doping concentration higher than that of the bulk doping region on the upper surface side of the semiconductor substrate of the bulk doping region, and the edge termination structure has a guard ring of a second conductivity type with a doping concentration higher than that of the bulk donor on the upper surface side of the semiconductor substrate of the edge termination structure, and a well region of a second conductivity type is provided between the edge termination structure and the active portion, and the second high-concentration region is adjacent to the edge of the semiconductor substrate on the side of the well region or one or more of the guard rings.

[0005] To solve the above problems, in a second aspect of the present invention, a semiconductor substrate is provided having a bulk doping region of the first conductivity type in which a bulk donor of the first conductivity type is distributed throughout and the doping concentration is the same as the concentration of the bulk donor; an active portion is provided on the semiconductor substrate; and an edge termination structure is provided on the semiconductor substrate and is provided on the upper surface of the semiconductor substrate between the active portion and the edge of the semiconductor substrate, wherein the edge termination structure has a first high-concentration region of the first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate in which the donor concentration is higher than the doping concentration of the bulk donor, and the upper surface of the first high-concentration region is located on the upper surface side of the semiconductor substrate, and the first high The lower surface of the concentration region is located on the lower surface side of the semiconductor substrate, the first high-concentration region has a flat portion in the depth direction in which the carrier concentration is uniform, the edge termination structure has a second high-concentration region of a first conductivity type with a doping concentration higher than that of the bulk-doping region on the upper surface side of the semiconductor substrate of the bulk-doping region, the edge termination structure has a guard ring of a second conductivity type with a doping concentration higher than that of the bulk donor on the upper surface side of the semiconductor substrate, the edge termination structure has a well region of a second conductivity type between the edge termination structure and the active portion, and the second high-concentration region is adjacent to the edge of the semiconductor substrate on the side of the well region or one or more of the guard rings.

[0006] In order to solve the above problems, in a third aspect of the present invention, a semiconductor substrate having a bulk donor of a first conductivity type distributed throughout and having a bulk doping region of the first conductivity type with a doping concentration being the concentration of the bulk donor, an active portion provided on the semiconductor substrate, and an edge termination structure portion provided on the semiconductor substrate and provided between the active portion and an end portion of the semiconductor substrate on an upper surface of the semiconductor substrate are provided. The edge termination structure portion has a first high-concentration region of the first conductivity type in a region between an upper surface and a lower surface of the semiconductor substrate, where a donor concentration is higher than a doping concentration of the bulk donor. An upper surface of the first high-concentration region is located on an upper surface side of the semiconductor substrate, and a lower surface of the first high-concentration region is located on a lower surface side of the semiconductor substrate. The first high-concentration region is disposed on the upper surface side of the semiconductor substrate and has a hydrogen peak portion where a hydrogen concentration shows a peak in a hydrogen concentration distribution in a depth direction. The first high-concentration region on the upper surface side of the hydrogen peak portion has a smaller width in the depth direction than the first high-concentration region on the lower surface side of the hydrogen peak portion. On an upper surface side of the semiconductor substrate of the bulk doping region of the edge termination structure portion, a second high-concentration region of the first conductivity type with a doping concentration higher than that of the bulk doping region is provided. On an upper surface side of the semiconductor substrate of the edge termination structure portion, a guard ring of the second conductivity type with a higher concentration than a doping concentration of the bulk donor is provided. A well region of the second conductivity type is provided between the edge termination structure portion and the active portion. A semiconductor device is provided in which the second high-concentration region is adjacent to an end portion side of the semiconductor substrate with respect to the well region or one or more of the guard rings.

[0007] To solve the above problems, a fourth aspect of the present invention provides a semiconductor substrate having a bulk doping region of the first conductivity type in which a bulk donor of the first conductivity type is distributed throughout and the doping concentration is the same as the concentration of the bulk donor; an active portion provided on the semiconductor substrate; and an edge termination structure provided on the semiconductor substrate and located between the active portion and the edge of the semiconductor substrate on the upper surface of the semiconductor substrate, wherein the edge termination structure has a first high-concentration region of the first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, in which the donor concentration is higher than the doping concentration of the bulk donor, the upper surface of the first high-concentration region is located on the upper surface side of the semiconductor substrate, the lower surface of the first high-concentration region is located on the lower surface side of the semiconductor substrate, and the first high-concentration region is located on the upper surface side of the semiconductor substrate, and deep The present invention provides a semiconductor device having a hydrogen peak portion in which the hydrogen concentration peaks in the hydrogen concentration distribution in a certain direction, wherein the slope of the hydrogen concentration distribution on the upper side of the hydrogen peak portion is steeper than the slope of the hydrogen concentration distribution on the lower side of the hydrogen peak portion, the edge termination structure has a second high-concentration region of a first conductivity type with a doping concentration higher than that of the bulk doping region on the upper side of the semiconductor substrate, the edge termination structure has a guard ring of a second conductivity type with a doping concentration higher than that of the bulk donor on the upper side of the semiconductor substrate, the edge termination structure has a well region of a second conductivity type between the edge termination structure and the active portion, and the second high-concentration region is adjacent to the edge of the semiconductor substrate on the side of the well region or one or more of the guard rings.

[0008] To solve the above problems, a fifth aspect of the present invention provides a semiconductor substrate having a bulk doping region of the first conductivity type in which a bulk donor of the first conductivity type is distributed throughout and the doping concentration is the same as the concentration of the bulk donor, an active portion provided on the semiconductor substrate, and an edge termination structure provided on the semiconductor substrate and between the active portion and the edge of the semiconductor substrate on the upper surface of the semiconductor substrate, wherein the edge termination structure has a first high-concentration region of the first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate in which the donor concentration is higher than the doping concentration of the bulk donor, and the upper surface of the first high-concentration region is located on the upper surface side of the semiconductor substrate, and the first high The lower surface of the concentration region is located on the lower surface side of the semiconductor substrate, the length of the first high-concentration region gradually increases in the depth direction as it moves away from the active portion, the edge termination structure has a second high-concentration region of a first conductivity type with a doping concentration higher than that of the bulk doping region on the upper surface side of the semiconductor substrate of the bulk doping region, the edge termination structure has a guard ring of a second conductivity type with a doping concentration higher than that of the bulk donor on the upper surface side of the semiconductor substrate, the edge termination structure has a well region of a second conductivity type between the edge termination structure and the active portion, and the second high-concentration region is adjacent to the edge of the semiconductor substrate on the side of the well region or one or more of the guard rings.

[0009] In order to solve the above problems, in a sixth aspect of the present invention, there are provided a semiconductor substrate in which bulk donors of a first conductivity type are distributed throughout, an active portion provided on the semiconductor substrate, and an edge termination structure portion provided on the semiconductor substrate and provided between the active portion and an end portion of the semiconductor substrate on an upper surface of the semiconductor substrate. The edge termination structure portion has a first high-concentration region of the first conductivity type, in a region between an upper surface and a lower surface of the semiconductor substrate, where a donor concentration is higher than a doping concentration of the bulk donor. An upper surface of the first high-concentration region is located on an upper surface side of the semiconductor substrate, and a lower surface of the first high-concentration region is located on a lower surface side of the semiconductor substrate. The active portion has a fourth high-concentration region of the first conductivity type, in a region between the upper surface and the lower surface of the semiconductor substrate, where a donor concentration is higher than the doping concentration of the bulk donor and at least adjacent to the first high-concentration region. An upper surface of the fourth high-concentration region is located on the upper surface side of the semiconductor substrate, and a lower surface of the fourth high-concentration region is located on the lower surface side of the semiconductor substrate. An upper end position of the fourth high-concentration region is disposed closer to the lower surface side than an upper end position of the first high-concentration region. A semiconductor device is provided.

[0010] In any of the above semiconductor devices, the semiconductor substrate has a bulk doping region of the first conductivity type having a doping concentration that is the same as the concentration of the bulk donor. On an upper surface side of the semiconductor substrate in the bulk doping region of the edge termination structure portion, there is provided a second high-concentration region of the first conductivity type having a doping concentration higher than that of the bulk doping region. On an upper surface side of the semiconductor substrate in the edge termination structure portion, there is a guard ring of the second conductivity type having a higher concentration than the doping concentration of the bulk donor. A well region of the second conductivity type is provided between the edge termination structure portion and the active portion. The second high-concentration region may be adjacent to an end portion side of the semiconductor substrate with respect to the well region or one or more of the guard rings.

[0011] In any of the above semiconductor devices, the first high-concentration region may be disposed on an upper surface side of the semiconductor substrate and have a hydrogen peak portion where a hydrogen concentration shows a peak in a hydrogen concentration distribution in a depth direction.

[0012] In any of the above-described semiconductor devices, the hydrogen peak portion may contain helium.

[0013] In any of the semiconductor devices described above, the edge termination structure may have a plurality of guard rings.

[0014] In any of the semiconductor devices described above, the second high-concentration region may be provided between two adjacent guard rings.

[0015] In any of the above semiconductor devices, the hydrogen peak portion may be located below the second high-concentration region.

[0016] In any of the semiconductor devices described above, the hydrogen peak portion may be located between the lower end of the guard ring and the lower surface of the semiconductor substrate.

[0017] In any of the above semiconductor devices, the first high-concentration region may be in contact with the guard ring.

[0018] In any of the semiconductor devices described above, the active portion has a base region of a second conductivity type located on the upper surface side of the semiconductor substrate, and the distance in the depth direction between the hydrogen peak portion and the second high-concentration region may be smaller than the maximum distance between the well region and each point of the guard ring closest to the well region.

[0019] In any of the semiconductor devices described above, the second high-concentration region includes hydrogen injected from the upper surface of the semiconductor substrate, the hydrogen peak portion includes hydrogen injected from the lower surface of the semiconductor substrate, the hydrogen concentration distribution in the depth direction of the second high-concentration region has a first peak where the hydrogen concentration is at its peak, and the first peak and the hydrogen peak portion may overlap.

[0020] In any of the semiconductor devices described above, the second high-concentration region includes hydrogen injected from the upper surface of the semiconductor substrate, the hydrogen peak portion includes hydrogen injected from the lower surface of the semiconductor substrate, the hydrogen concentration distribution in the depth direction of the second high-concentration region has a first peak where the hydrogen concentration is at its peak, and the hydrogen peak portion may be located between the first peak and the upper surface of the semiconductor substrate.

[0021] In any of the above semiconductor devices, the second high-concentration region may include a hydrogen donor.

[0022] In any of the semiconductor devices described above, the second high-density region may be provided between two adjacent guard rings, extending from a position shallower than the lower end of the guard ring to a position deeper than the lower end of the guard ring.

[0023] In any of the semiconductor devices described above, the second high-concentration region may be in contact with the upper surface of the semiconductor substrate.

[0024] In any of the above semiconductor devices, the first high-concentration region may have a hydrogen donor.

[0025] In any of the above-described semiconductor devices, the bulk donor may be phosphorus or antimony.

[0026] In any of the semiconductor devices described above, the first high-concentration region may be provided in a range that does not reach the active portion.

[0027] In any of the semiconductor devices described above, the first high-concentration region may have an inner portion and an outer portion located outside the inner portion, the outer portion having a length in the depth direction of the semiconductor substrate greater than that of the inner portion.

[0028] In any of the above semiconductor devices, the semiconductor substrate may have a second conductivity type bulk acceptor distributed throughout.

[0029] In any of the above-described semiconductor devices, the bulk acceptor may be boron.

[0030] In any of the above semiconductor devices, the dose amount of the donor in the second high-concentration region is 5 × 10 11 / cm 2 The following is acceptable:

[0031] In any of the above semiconductor devices, the dose amount of the donor in the second high-concentration region is 1 × 10⁻⁶ 11 / cm 2 That's all.

[0032] In any of the above-described semiconductor devices, the peak value of the donor concentration in the second high-concentration region may be 10 times or more the minimum value of the donor concentration in the first high-concentration region.

[0033] In any of the above semiconductor devices, the distance between the lower end of the second high-concentration region and the upper end of the first high-concentration region may be 50 μm or less.

[0034] In any of the above semiconductor devices, the distance between the lower end of the second high-concentration region and the upper end of the first high-concentration region may be 15 μm or more.

[0035] In any of the semiconductor devices described above, the depth position of the lower end of the second high-concentration region may be 2 μm or more away from the upper surface of the semiconductor substrate.

[0036] In any of the semiconductor devices described above, the active portion has a fourth high-concentration region of a first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, wherein the donor concentration is higher than the doping concentration of the bulk donor, the upper surface of the fourth high-concentration region is located on the upper side of the semiconductor substrate, the lower surface of the fourth high-concentration region is located on the lower side of the semiconductor substrate, and the donor concentration of the fourth high-concentration region may be different from the donor concentration of the first high-concentration region.

[0037] In any of the semiconductor devices described above, the active portion has a fourth high-concentration region of a first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, wherein the donor concentration is higher than the doping concentration of the bulk donor, the upper surface of the fourth high-concentration region is located on the upper surface side of the semiconductor substrate, the lower surface of the fourth high-concentration region is located on the lower surface side of the semiconductor substrate, and the upper end position of the fourth high-concentration region may be different from the upper end position of the first high-concentration region.

[0038] In the edge termination structure of any of the semiconductor devices described above, the first high-density region and the second high-density region may be provided continuously.

[0039] In any of the above semiconductor devices, the second high-concentration region may be provided between two adjacent guard rings. In any of the above semiconductor devices, the edge termination structure has a plurality of guard rings, and at least a portion of the region, including the portion in contact with the active part, may include the area below the guard ring located closest to the active part.

[0040] It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. Furthermore, subcombinations of these features may also constitute an invention. [Brief explanation of the drawing]

[0041] [Figure 1] This is a top view showing an example of a semiconductor device 100 according to one embodiment of the present invention. [Figure 2] This is a magnified view of region A in Figure 1. [Figure 3] Figure 2 shows an example of a cross-section of bb. [Figure 4] Figure 1 shows an example of a cross-section of the cc. [Figure 5] Figure 4 shows an example of the carrier concentration distribution, donor concentration distribution, and defect density distribution along the dd line. [Figure 6] This figure shows an example of an equipotential surface in the edge termination structure 90. [Figure 7] Figure 4 shows other examples of carrier concentration distribution, donor concentration distribution, and defect density distribution along the dd line. [Figure 8] This figure shows another example of a cc cross section. [Figure 9] This figure shows another example of a cc cross section. [Figure 10] Figure 9 shows an example of the hydrogen concentration distribution along the ee line. [Figure 11] Figure 9 shows another example of the hydrogen concentration distribution along the ee line. [Figure 12] This figure shows another example of a cc cross section. [Figure 13] This is a magnified cross-sectional view of the vicinity of the well area 11 and the guard ring 92. [Figure 14] This figure shows another structural example of the second high-concentration region 202. [Figure 15] This figure shows another example of the second high-concentration region 202. [Figure 16A] This is a diagram illustrating a part of the manufacturing process of semiconductor device 100. [Figure 16B] This is a diagram illustrating a part of the manufacturing process of semiconductor device 100. [Figure 17A] This is a cross-sectional view near the emitter electrode 52 and the outer gate wiring 130. [Figure 17B] This is a cross-sectional view near the emitter electrode 52 and the outer gate wiring 130. [Figure 18] This figure shows another example of a cross-section near the edge termination structure 90. [Figure 19] This figure shows another example of a cross-section near the emitter electrode 52 and the outer gate wiring 130. [Figure 20] This figure shows another example of a cc cross section. [Figure 21] This figure shows another example of a cc cross section. [Figure 22] This figure shows another example of a cc cross section. [Figure 23] This figure shows another example of a cc cross section. [Figure 24A] This figure shows another example of a cc cross section. [Figure 24B] This figure shows another example of a cc cross section. [Figure 25A] This figure shows another example of a cc cross section. [Figure 25B] This figure shows another example of a cc cross section. [Figure 26] This figure shows an example of the method for forming the first high-concentration region 304, as explained in Figure 24A. [Figure 27] This figure shows an example of a method for forming the first high-concentration region 304, as described in Figure 25A or Figure 25B. [Figure 28] This figure shows another example of a cc cross section. [Figure 29] This figure shows another example of a cc cross section. [Figure 30] This figure shows another example of a cc cross section. [Figure 31] This figure shows another example of a cc cross section. [Figure 32] This figure shows another example of a cc cross section. [Figure 33] This figure shows another example of a cc cross section. [Figure 34] This shows an example of the carrier concentration distribution along the dd line shown in Figure 4 or Figure 33. [Figure 35] Figure 33 shows the relationship between the dose amount ( / cm2) of the N-type dopant into the second high-concentration region 202 and the breakdown voltage (V) of the semiconductor device 100. [Figure 36] This figure shows another example of the relationship between the dose amount ( / cm2) of the N-type dopant and the breakdown voltage (V) of the semiconductor device 100. [Figure 37] This is a flowchart showing an example of the manufacturing process for semiconductor device 100. [Figure 38A] This figure shows an example of the first hydrogen injection stage S508. [Figure 38B] This figure shows an example of hydrogen ion implantation through a shielding member 351. [Figure 39] This figure shows another example of the first hydrogen injection stage S508. [Figure 40] This flowchart shows another example of the manufacturing process for semiconductor device 100. [Figure 41] This figure shows another example of a cc cross section. [Modes for carrying out the invention]

[0042] The present invention will be described below through embodiments, but these embodiments are not intended to limit the scope of the claims. Furthermore, not all combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0043] In this specification, one side of a semiconductor substrate parallel to its depth direction is referred to as "top," and the other side as "bottom." Of the two main surfaces of a substrate, layer, or other component, one surface is referred to as the top surface, and the other surface as the bottom surface. The directions of "top" and "bottom" are not limited to the direction of gravity or the direction in which the semiconductor device is mounted.

[0044] In this specification, technical matters may be described using the Cartesian coordinate axes, the X, Y, and Z axes. The Cartesian coordinate axes merely specify the relative positions of components and do not limit any particular direction. For example, the Z axis does not limit the direction to height relative to the ground. Note that the +Z axis direction and the -Z axis direction are opposite directions. When the sign is not specified and only the Z axis direction is written, it means the direction parallel to the +Z and -Z axes.

[0045] In this specification, the orthogonal axes parallel to the top and bottom surfaces of the semiconductor substrate are defined as the X and Y axes. The axis perpendicular to the top and bottom surfaces of the semiconductor substrate is defined as the Z axis. In this specification, the direction of the Z axis may be referred to as the depth direction. In this specification, the direction parallel to the top and bottom surfaces of the semiconductor substrate, including the X and Y axes, may be referred to as the horizontal direction.

[0046] In this specification, the terms "identical" or "equal" may include cases where there are errors due to manufacturing variations, etc. Such errors are, for example, within 10%.

[0047] In this specification, the conductivity type of a doped region containing impurities is described as either P-type or N-type. In this specification, impurities may specifically refer to either N-type donors or P-type acceptors, and may be referred to as dopants. In this specification, doping means introducing donors or acceptors into a semiconductor substrate to make it a semiconductor exhibiting either an N-type conductivity or a P-type conductivity.

[0048] In this specification, doping concentration means the concentration of the donor or acceptor at thermal equilibrium. In this specification, net doping concentration means the net concentration obtained by adding up the charge polarity, with the donor concentration being the concentration of positive ions and the acceptor concentration being the concentration of negative ions. As an example, the donor concentration is N D , the acceptor concentration is N A Therefore, the net doping concentration at any given position is N D -N A This is the result.

[0049] Donors have the function of supplying electrons to a semiconductor. Acceptors have the function of receiving electrons from a semiconductor. Donors and acceptors are not limited to impurities themselves. For example, VOH defects, which are composed of vacancies (V), oxygen (O), and hydrogen (H) present in a semiconductor, function as electron donors.

[0050] In this specification, when P+ or N+ is mentioned, it means a higher doping concentration than P or N, and when P- or N- is mentioned, it means a lower doping concentration than P or N. Furthermore, when P++ or N++ is mentioned in this specification, it means a higher doping concentration than P+ or N+.

[0051] In this specification, chemical concentration refers to the atomic density of impurities measured independently of the electrical activation state. Chemical concentration can be measured, for example, by secondary ion mass spectrometry (SIMS). The net doping concentration described above can be measured by voltage-capacitance (CV) spectroscopy. Alternatively, the carrier concentration measured by broadening resistance (SR) spectroscopy may be used as the net doping concentration. The carrier concentration measured by CV or SR spectroscopy may be the value at thermal equilibrium. Furthermore, in the N-type region, since the donor concentration is sufficiently larger than the acceptor concentration, the carrier concentration in that region may be used as the donor concentration. Similarly, in the P-type region, the carrier concentration in that region may be used as the acceptor concentration.

[0052] Furthermore, if the concentration distribution of donor, acceptor, or net doping has a peak, the peak value may be used as the concentration of donor, acceptor, or net doping in that region. In cases where the concentrations of donor, acceptor, or net doping are nearly uniform, the average value of the concentrations of donor, acceptor, or net doping in that region may be used as the concentration of donor, acceptor, or net doping.

[0053] The carrier concentration measured by the SR method may be lower than the donor or acceptor concentration. When measuring spreading resistance, the carrier mobility of the semiconductor substrate may be lower than the value for the crystalline state in the range where current flows. The decrease in carrier mobility occurs because carriers are scattered due to disorder in the crystal structure caused by lattice defects, etc.

[0054] The donor or acceptor concentrations calculated from carrier concentrations measured by the CV method or SR method may be lower than the chemical concentrations of the elements that act as donors or acceptors. For example, in silicon semiconductors, the donor concentrations of phosphorus or arsenic, or the acceptor concentration of boron, are approximately 99% of their respective chemical concentrations. On the other hand, the donor concentration of hydrogen, which also acts as a donor in silicon semiconductors, is approximately 0.1% to 10% of the hydrogen chemical concentration.

[0055] Figure 1 is a top view showing an example of a semiconductor device 100 according to one embodiment of the present invention. In Figure 1, the positions of each component projected onto the upper surface of the semiconductor substrate 10 are shown. In Figure 1, only some components of the semiconductor device 100 are shown, and some components are omitted.

[0056] The semiconductor device 100 comprises a semiconductor substrate 10. The semiconductor substrate 10 has edges 102 when viewed from above. In this specification, "view from above" simply means viewing from the top side of the semiconductor substrate 10. In this example, the semiconductor substrate 10 has two pairs of edges 102 that face each other when viewed from above. In Figure 1, the X and Y axes are parallel to either edge 102. The Z axis is perpendicular to the top surface of the semiconductor substrate 10.

[0057] The semiconductor substrate 10 is provided with an active section 160. The active section 160 is a region in which the main current flows in the depth direction between the upper and lower surfaces of the semiconductor substrate 100 when the semiconductor device 100 is operating. An emitter electrode is provided above the active section 160, but it is omitted in Figure 1.

[0058] The active section 160 is provided with at least one of a transistor section 70 including a transistor element such as an IGBT, and a diode section 80 including a diode element such as a freewheeling diode (FWD). In the example shown in Figure 1, the transistor section 70 and the diode section 80 are arranged alternately along a predetermined arrangement direction (in this example, the X-axis direction) on the upper surface of the semiconductor substrate 10. In other examples, the active section 160 may be provided with only one of the transistor section 70 and the diode section 80.

[0059] In Figure 1, the region where the transistor section 70 is located is denoted by the symbol "I," and the region where the diode section 80 is located is denoted by the symbol "F." In this specification, the direction perpendicular to the arrangement direction in a top view may be referred to as the extension direction (Y-axis direction in Figure 1). The transistor section 70 and the diode section 80 may each have their longitudinal length in the extension direction. That is, the length of the transistor section 70 in the Y-axis direction is greater than its width in the X-axis direction. Similarly, the length of the diode section 80 in the Y-axis direction is greater than its width in the X-axis direction. The extension direction of the transistor section 70 and the diode section 80 may be the same as the longitudinal direction of each trench section described later.

[0060] The diode section 80 has an N+ type cathode region in the area in contact with the lower surface of the semiconductor substrate 10. In this specification, the region in which the cathode region is provided is referred to as the diode section 80. In other words, the diode section 80 is the region that overlaps with the cathode region when viewed from above. A P+ type collector region may be provided on the lower surface of the semiconductor substrate 10 in areas other than the cathode region. In this specification, an extension region 81, which is an extension of the diode section 80 in the Y-axis direction to the gate wiring described later, may also be included in the diode section 80. A collector region is provided on the lower surface of the extension region 81.

[0061] The transistor section 70 has a P+ type collector region in the area in contact with the lower surface of the semiconductor substrate 10. Furthermore, the transistor section 70 has a gate structure periodically arranged on the upper surface side of the semiconductor substrate 10, which includes an N type emitter region, a P type base region, a gate conductive portion, and a gate insulating film.

[0062] The semiconductor device 100 may have one or more pads on the semiconductor substrate 10. In this example, the semiconductor device 100 has a gate pad 112. The semiconductor device 100 may also have pads such as an anode pad, a cathode pad, and a current sensing pad. Each pad is located near the edge 102. The vicinity of the edge 102 refers to the area between the edge 102 and the emitter electrode in a top view. When the semiconductor device 100 is mounted, each pad may be connected to an external circuit via wiring such as wires.

[0063] A gate potential is applied to the gate pad 112. The gate pad 112 is electrically connected to the conductive portion of the gate trench of the active portion 160. The semiconductor device 100 is provided with gate wiring that connects the gate pad 112 to the gate trench. In Figure 1, the gate wiring is hatched with diagonal lines.

[0064] The gate wiring in this example has an outer perimeter gate wiring 130 and an active-side gate wiring 131. The outer perimeter gate wiring 130 is positioned between the active portion 160 and the edge 102 of the semiconductor substrate 10 in a top view. In this example, the outer perimeter gate wiring 130 surrounds the active portion 160 in a top view. The area surrounded by the outer perimeter gate wiring 130 in a top view may be considered the active portion 160. The outer perimeter gate wiring 130 is also connected to the gate pad 112. The outer perimeter gate wiring 130 is positioned above the semiconductor substrate 10. The outer perimeter gate wiring 130 may be a metal wiring containing aluminum or the like.

[0065] The active gate wiring 131 is provided in the active section 160. By providing the active gate wiring 131 in the active section 160, variations in the wiring length from the gate pad 112 can be reduced for each region of the semiconductor substrate 10.

[0066] The active gate wiring 131 is connected to the gate trench portion of the active section 160. The active gate wiring 131 is positioned above the semiconductor substrate 10. The active gate wiring 131 may be wiring formed of a semiconductor such as polysilicon doped with impurities.

[0067] The active gate wiring 131 may be connected to the outer gate wiring 130. In this example, the active gate wiring 131 extends in the X-axis direction, crossing the active section 160 from one outer gate wiring 130 to the other outer gate wiring 130 approximately in the center in the Y-axis direction. When the active section 160 is divided by the active gate wiring 131, the transistor section 70 and the diode section 80 may be arranged alternately in the X-axis direction in each divided region.

[0068] Furthermore, the semiconductor device 100 may also include a temperature sensing unit (not shown) which is a PN junction diode made of polysilicon or the like, and a current detection unit (not shown) which simulates the operation of a transistor unit provided in the active unit 160.

[0069] The semiconductor device 100 in this example includes an edge termination structure 90 between the active portion 160 and the edge 102. The edge termination structure 90 in this example is located between the outer peripheral gate wiring 130 and the edge 102. The edge termination structure 90 mitigates electric field concentration on the upper surface side of the semiconductor substrate 10. The edge termination structure 90 has a plurality of guard rings 92. The guard rings 92 are P-shaped regions in contact with the upper surface of the semiconductor substrate 10. The guard rings 92 may surround the active portion 160 when viewed from above. The plurality of guard rings 92 are arranged at predetermined intervals between the outer peripheral gate wiring 130 and the edge 102. An outer guard ring 92 may surround a guard ring 92 located one position inward. "Outer" refers to the side closer to the edge 102, and "inner" refers to the side closer to the outer peripheral gate wiring 130. By providing multiple guard rings 92, the depletion layer on the upper surface of the active portion 160 can be extended outward, thereby improving the voltage resistance of the semiconductor device 100. The edge termination structure 90 may further include at least one of a field plate and a resurf, which are provided in an annular shape surrounding the active portion 160.

[0070] Figure 2 is an enlarged view of region A in Figure 1. Region A is the region including the transistor section 70, the diode section 80, and the active-side gate wiring 131. The semiconductor device 100 in this example includes a gate trench section 40, a dummy trench section 30, a well section 11, an emitter section 12, a base section 14, and a contact section 15, which are provided inside the upper surface of the semiconductor substrate 10. The gate trench section 40 and the dummy trench section 30 are examples of trench sections. The semiconductor device 100 in this example also includes an emitter electrode 52 and an active-side gate wiring 131, which are provided above the upper surface of the semiconductor substrate 10. The emitter electrode 52 and the active-side gate wiring 131 are provided separately from each other.

[0071] An interlayer insulating film is provided between the emitter electrode 52 and the active gate wiring 131 and the upper surface of the semiconductor substrate 10, but this is omitted in Figure 1. In this example, contact holes 54 are provided in the interlayer insulating film, penetrating the film. In Figure 2, each contact hole 54 is hatched with diagonal lines.

[0072] The emitter electrode 52 is provided above the gate trench 40, dummy trench 30, well region 11, emitter region 12, base region 14, and contact region 15. The emitter electrode 52 contacts the emitter region 12, contact region 15, and base region 14 on the upper surface of the semiconductor substrate 10 through a contact hole 54. The emitter electrode 52 is also connected to a dummy conductive portion in the dummy trench 30 through a contact hole provided in the interlayer insulating film. The emitter electrode 52 may also be connected to a dummy conductive portion of the dummy trench 30 at its tip in the Y-axis direction.

[0073] The active gate wiring 131 connects to the gate trench portion 40 through a contact hole provided in the interlayer insulating film. The active gate wiring 131 may be connected to the gate conductive portion of the gate trench portion 40 at the tip portion 41 of the gate trench portion 40 in the Y-axis direction. The active gate wiring 131 is not connected to the dummy conductive portion in the dummy trench portion 30.

[0074] The emitter electrode 52 is formed from a material containing metal. Figure 2 shows the area in which the emitter electrode 52 is provided. For example, at least a portion of the emitter electrode 52 is formed from aluminum or an aluminum-silicon alloy, such as AlSi or AlSiCu. The emitter electrode 52 may have a barrier metal formed from titanium or a titanium compound in the layer below the region formed from aluminum or the like. Furthermore, it may have a plug formed by embedding tungsten or the like in the contact hole so as to be in contact with the barrier metal and the aluminum or the like.

[0075] The well region 11 is provided overlapping with the active gate wiring 131. The well region 11 also extends to a predetermined width in an area that does not overlap with the active gate wiring 131. In this example, the well region 11 is provided away from the Y-axis end of the contact hole 54 towards the active gate wiring 131. The well region 11 is a second conductivity type region with a higher doping concentration than the base region 14. In this example, the base region 14 is P-type, and the well region 11 is P+ type.

[0076] Each of the transistor section 70 and the diode section 80 has multiple trench sections arranged in the direction of arrangement. In this example, the transistor section 70 has one or more gate trench sections 40 and one or more dummy trench sections 30 alternately provided along the direction of arrangement. In this example, the diode section 80 has multiple dummy trench sections 30 provided along the direction of arrangement. In this example, the diode section 80 does not have gate trench sections 40.

[0077] The gate trench portion 40 in this example may have two linear portions 39 (the trench portion which is linear along the extension direction) that extend along the extension direction perpendicular to the alignment direction, and a tip portion 41 that connects the two linear portions 39. In Figure 2, the extension direction is the Y-axis direction.

[0078] Preferably, at least a portion of the tip portion 41 is provided in a curved shape when viewed from above. By connecting the ends of the two straight portions 39 in the Y-axis direction with the tip portion 41, electric field concentration at the ends of the straight portions 39 can be mitigated.

[0079] In the transistor section 70, the dummy trench section 30 is provided between each of the straight sections 39 of the gate trench section 40. There may be one dummy trench section 30 between each of the straight sections 39, or there may be multiple dummy trench sections 30. The dummy trench section 30 may have a straight shape extending in the extension direction, and like the gate trench section 40, it may have a straight section 29 and a tip section 31. The semiconductor device 100 shown in Figure 2 includes both a dummy trench section 30 with a straight shape without a tip section 31 and a dummy trench section 30 with a tip section 31.

[0080] The diffusion depth of the well region 11 may be deeper than the depth of the gate trench portion 40 and the dummy trench portion 30. The Y-axis ends of the gate trench portion 40 and the dummy trench portion 30 are located in the well region 11 when viewed from above. In other words, at the Y-axis end of each trench portion, the bottom in the depth direction of each trench portion is covered by the well region 11. This makes it possible to mitigate electric field concentration at the bottom of each trench portion.

[0081] In the arrangement direction, mesa portions are provided between each trench portion. A mesa portion refers to a region within the semiconductor substrate 10 that is sandwiched between trench portions. For example, the upper end of a mesa portion is the upper surface of the semiconductor substrate 10. The depth position of the lower end of a mesa portion is the same as the depth position of the lower end of a trench portion. In this example, the mesa portion is provided on the upper surface of the semiconductor substrate 10, extending along the trench in the extension direction (Y-axis direction). In this example, a mesa portion 60 is provided in the transistor portion 70, and a mesa portion 61 is provided in the diode portion 80. In this specification, when simply referred to as a mesa portion, it refers to mesa portion 60 and mesa portion 61, respectively.

[0082] Each mesa portion is provided with a base region 14. Of the base regions 14 exposed on the upper surface of the semiconductor substrate 10 in the mesa portion, the region closest to the active gate wiring 131 is defined as base region 14-e. Figure 2 shows the base region 14-e located at one end of each mesa portion in the extending direction, but a base region 14-e is also located at the other end of each mesa portion. In each mesa portion, at least one of a first conductivity type emitter region 12 and a second conductivity type contact region 15 may be provided in the region sandwiched between the base regions 14-e in a top view. In this example, the emitter region 12 is N+ type and the contact region 15 is P+ type. The emitter region 12 and the contact region 15 may be provided in the depth direction between the base region 14 and the upper surface of the semiconductor substrate 10.

[0083] The mesa portion 60 of the transistor portion 70 has an emitter region 12 exposed on the upper surface of the semiconductor substrate 10. The emitter region 12 is provided in contact with the gate trench portion 40. The mesa portion 60 in contact with the gate trench portion 40 may have a contact region 15 exposed on the upper surface of the semiconductor substrate 10.

[0084] Each of the contact region 15 and emitter region 12 in the mesa portion 60 extends from one trench portion to the other in the X-axis direction. As an example, the contact region 15 and emitter region 12 of the mesa portion 60 are arranged alternately along the extension direction (Y-axis direction) of the trench portion.

[0085] In other examples, the contact region 15 and emitter region 12 of the mesa portion 60 may be arranged in a stripe pattern along the extension direction (Y-axis direction) of the trench portion. For example, the emitter region 12 may be provided in the region in contact with the trench portion, and the contact region 15 may be provided in the region sandwiched between the emitter regions 12.

[0086] The mesa portion 61 of the diode portion 80 does not have an emitter region 12. A base region 14 and a contact region 15 may be provided on the upper surface of the mesa portion 61. In the region on the upper surface of the mesa portion 61 sandwiched between the base regions 14-e, a contact region 15 may be provided in contact with each base region 14-e. In the region on the upper surface of the mesa portion 61 sandwiched between the contact regions 15, a base region 14 may be provided. The base region 14 may be arranged in the entire region sandwiched between the contact regions 15.

[0087] A contact hole 54 is provided above each mesa portion. The contact holes 54 are located in the region sandwiched between the base region 14-e. In this example, the contact holes 54 are provided above the contact region 15, the base region 14, and the emitter region 12. The contact holes 54 are not provided in the region corresponding to the base region 14-e and the well region 11. The contact holes 54 may be located in the center of the mesa portion 60 in the alignment direction (X-axis direction).

[0088] In the diode section 80, an N+ type cathode region 82 is provided in the region adjacent to the lower surface of the semiconductor substrate 10. In the region on the lower surface of the semiconductor substrate 10 where the cathode region 82 is not provided, a P+ type collector region 22 may be provided. In Figure 2, the boundary between the cathode region 82 and the collector region 22 is shown by a dotted line.

[0089] The cathode region 82 is positioned away from the well region 11 in the Y-axis direction. This ensures a distance between the cathode region 82 and the P-type region (well region 11), which has a relatively high doping concentration and is formed to a deep position, thereby improving pressure resistance. In this example, the Y-axis end of the cathode region 82 is positioned further from the well region 11 than the Y-axis end of the contact hole 54. In other examples, the Y-axis end of the cathode region 82 may be positioned between the well region 11 and the contact hole 54.

[0090] Figure 3 shows an example of the bb cross-section in Figure 2. The bb cross-section is the XZ plane passing through the emitter region 12 and the cathode region 82. The semiconductor device 100 in this example has a semiconductor substrate 10, an interlayer insulating film 38, an emitter electrode 52, and a collector electrode 24 in this cross-section. The interlayer insulating film 38 is provided on the upper surface of the semiconductor substrate 10. The interlayer insulating film 38 is a film that includes at least one layer of insulating film such as silicate glass with impurities such as boron or phosphorus added, a thermal oxide film, and other insulating films. The interlayer insulating film 38 is provided with contact holes 54 as described in Figure 2.

[0091] The emitter electrode 52 is located above the interlayer insulating film 38. The emitter electrode 52 is in contact with the upper surface 21 of the semiconductor substrate 10 through a contact hole 54 in the interlayer insulating film 38. The collector electrode 24 is located on the lower surface 23 of the semiconductor substrate 10. The emitter electrode 52 and the collector electrode 24 are made of a metallic material such as aluminum. In this specification, the direction connecting the emitter electrode 52 and the collector electrode 24 (Z-axis direction) is referred to as the depth direction.

[0092] The semiconductor substrate 10 has an N-type bulk doping region 18. The bulk doping region 18 is a region in which the doping concentration of the bulk doping region 18 matches the donor concentration of the bulk donor. The bulk donor will be described later. The bulk doping region 18 is provided in both the transistor section 70 and the diode section 80.

[0093] In the mesa portion 60 of the transistor portion 70, an N+ type emitter region 12 and a P- type base region 14 are provided in order from the upper surface 21 side of the semiconductor substrate 10. A bulk doping region 18 is provided below the base region 14. An N+ type storage region 16 may also be provided in the mesa portion 60. The storage region 16 is located between the base region 14 and the bulk doping region 18.

[0094] The emitter region 12 is exposed on the upper surface 21 of the semiconductor substrate 10 and is provided in contact with the gate trench portion 40. The emitter region 12 may be in contact with the trench portions on both sides of the mesa portion 60. The doping concentration in the emitter region 12 is higher than that in the bulk doping region 18.

[0095] The base region 14 is located below the emitter region 12. In this example, the base region 14 is located in contact with the emitter region 12. The base region 14 may be in contact with the trenches on both sides of the mesa region 60.

[0096] The accumulation region 16 is located below the base region 14. The accumulation region 16 is an N+ type region with a higher doping concentration than the bulk doping region 18. By providing a high-concentration accumulation region 16 between the bulk doping region 18 and the base region 14, the carrier injection promotion effect (IE effect) can be enhanced and the on-voltage can be reduced. The accumulation region 16 may be provided so as to cover the entire lower surface of the base region 14 in each mesa portion 60.

[0097] A P-type base region 14 is provided in the mesa portion 61 of the diode portion 80, in contact with the upper surface 21 of the semiconductor substrate 10. A bulk doping region 18 is provided below the base region 14. A storage region 16 may also be provided below the base region 14 in the mesa portion 61.

[0098] In each of the transistor section 70 and the diode section 80, an N+ type buffer section 20 may be provided below the bulk doping section 18. The doping concentration of the buffer section 20 is higher than that of the bulk doping section 18. The buffer section 20 has one or more donor concentration peaks with higher donor concentrations than the bulk doping section 18. The multiple donor concentration peaks are located at different positions in the depth direction of the semiconductor substrate 10. The donor concentration peaks of the buffer section 20 may be, for example, hydrogen (proton) or phosphorus concentration peaks. The buffer section 20 may function as a field stop layer that prevents the depletion layer extending from the lower end of the base section 14 from reaching the P+ type collector section 22 and the N+ type cathode section 82.

[0099] In the transistor section 70, a P+ type collector region 22 is provided below the buffer region 20. The acceptor concentration of the collector region 22 is higher than that of the base region 14. The collector region 22 may contain the same acceptors as the base region 14, or it may contain different acceptors. The acceptors of the collector region 22 are, for example, boron.

[0100] In the diode section 80, an N+ type cathode region 82 is provided below the buffer region 20. The donor concentration in the cathode region 82 is higher than that of the bulk doping region 18. The donor in the cathode region 82 is, for example, hydrogen or phosphorus. Note that the elements that serve as donors and acceptors in each region are not limited to the examples described above. The collector region 22 and the cathode region 82 are exposed on the lower surface 23 of the semiconductor substrate 10 and are connected to the collector electrode 24. The collector electrode 24 may be in contact with the entire lower surface 23 of the semiconductor substrate 10. The emitter electrode 52 and the collector electrode 24 are made of a metallic material such as aluminum.

[0101] One or more gate trenches 40 and one or more dummy trenches 30 are provided on the upper surface 21 of the semiconductor substrate 10. Each trench extends from the upper surface 21 of the semiconductor substrate 10, through the base region 14, and reaches the bulk doping region 18. In regions where at least one of the emitter region 12, contact region 15, and storage region 16 is provided, each trench also extends through these doping regions to reach the bulk doping region 18. The statement that a trench penetrates a doping region is not limited to manufacturing in the order of forming the doping region before forming the trenches. Even when doping regions are formed between trenches after the trenches have been formed, the trenches are still considered to penetrate the doping region.

[0102] As described above, the transistor section 70 is provided with a gate trench section 40 and a dummy trench section 30. The diode section 80 is provided with a dummy trench section 30, but not with a gate trench section 40. In this example, the boundary between the diode section 80 and the transistor section 70 in the X-axis direction is the boundary between the cathode region 82 and the collector region 22.

[0103] The gate trench portion 40 has a gate trench provided on the upper surface 21 of the semiconductor substrate 10, a gate insulating film 42, and a gate conductive portion 44. The gate insulating film 42 is provided covering the inner wall of the gate trench. The gate insulating film 42 may be formed by oxidizing or nitriding the semiconductor on the inner wall of the gate trench. The gate conductive portion 44 is provided inside the gate trench, on the inside of the gate insulating film 42. In other words, the gate insulating film 42 insulates the gate conductive portion 44 from the semiconductor substrate 10. The gate conductive portion 44 is formed of a conductive material such as polysilicon.

[0104] The gate conductive portion 44 may be longer than the base region 14 in the depth direction. The gate trench portion 40 in this cross-section is covered by an interlayer insulating film 38 on the upper surface 21 of the semiconductor substrate 10. The gate conductive portion 44 is electrically connected to the gate wiring. When a predetermined gate voltage is applied to the gate conductive portion 44, a channel formed by an electron inversion layer is formed on the surface layer of the interface of the base region 14 that is in contact with the gate trench portion 40.

[0105] The dummy trench portion 30 may have the same structure as the gate trench portion 40 in its cross-section. The dummy trench portion 30 includes a dummy trench, a dummy insulating film 32, and a dummy conductive portion 34 provided on the upper surface 21 of the semiconductor substrate 10. The dummy conductive portion 34 may be connected to an electrode different from the gate pad. For example, the dummy conductive portion 34 may be connected to a dummy pad (not shown) that is connected to an external circuit different from the gate pad, and different control may be performed from that of the gate conductive portion 44. Alternatively, the dummy conductive portion 34 may be electrically connected to the emitter electrode 52. The dummy insulating film 32 is provided covering the inner wall of the dummy trench. The dummy conductive portion 34 is provided inside the dummy trench and is located inside the dummy insulating film 32. The dummy insulating film 32 insulates the dummy conductive portion 34 from the semiconductor substrate 10. The dummy conductive portion 34 may be formed from the same material as the gate conductive portion 44. For example, the dummy conductive part 34 is formed of a conductive material such as polysilicon. The dummy conductive part 34 may have the same length as the gate conductive part 44 in the depth direction.

[0106] In this example, the gate trench portion 40 and the dummy trench portion 30 are covered by an interlayer insulating film 38 on the upper surface 21 of the semiconductor substrate 10. The bottom portions of the dummy trench portion 30 and the gate trench portion 40 may be curved (curved in cross-section) with a downward convex shape.

[0107] The semiconductor substrate 10 has a first conductivity type (N-type) bulk donor distributed throughout. The bulk donor is a donor due to a dopant that was contained substantially uniformly within the ingot during the manufacturing of the ingot that forms the basis of the semiconductor substrate 10. In this example, the bulk donor is an element other than hydrogen. The bulk donor dopant is, for example, phosphorus or antimony, but is not limited to these. In this example, the bulk donor is phosphorus. The bulk donor is also contained in the P-type region. The semiconductor substrate 10 may be a wafer cut from a semiconductor ingot, or it may be a chip made by cutting a wafer into individual pieces. The semiconductor ingot may be manufactured by one of the following methods: the Czochralski method (CZ method), the magnetic field applied Czochralski method (MCZ method), or the float zone method (FZ method). In this example, the ingot is manufactured by the MCZ method. The bulk doping region 18 is the region where the doping concentration in the bulk doping region 18 matches the donor concentration of the bulk donor. For example, the donor concentration of the bulk donor may be between 90% and 100% of the chemical concentration of the bulk donor's dopant.

[0108] The semiconductor substrate 10 is positioned on the upper surface 21 side and has a hydrogen peak portion 302 where the hydrogen concentration shows a peak in the hydrogen concentration distribution in the depth direction of the semiconductor substrate 10. The upper surface 21 side of the semiconductor substrate 10 is the region from the central position in the depth direction of the semiconductor substrate 10 to the upper surface 21. The lower surface 23 side is the region from the central position in the depth direction of the semiconductor substrate 10 to the lower surface 23. The hydrogen peak portion 302 may have a donor concentration distribution that reflects the peak shape of the hydrogen concentration distribution. The donor concentration in the peak portion of the hydrogen peak portion 302 is higher than the donor concentration of the bulk donor.

[0109] Hydrogen ions, such as protons, are implanted into the hydrogen peak region 302 from the lower surface 23 of the semiconductor substrate 10. In the passage region through which the hydrogen ions pass, lattice defects mainly consisting of vacancies, such as monatomic vacancies (V) and doubleatomic vacancies (VV), are formed. Atoms adjacent to vacancies have dangling bonds. Lattice defects also include interstitial atoms and dislocations, and in a broad sense, may also include donors and acceptors, but in this specification, lattice defects mainly consisting of vacancies may be referred to as vacancy-type lattice defects, vacancy-type defects, or simply lattice defects. Furthermore, the implantation of hydrogen ions into the semiconductor substrate 10 can lead to the formation of many lattice defects, which can strongly disrupt the crystallinity of the semiconductor substrate 10. In this specification, this disruption of crystallinity may be referred to as disorder. In addition, as the hydrogen implanted into the hydrogen peak region 302 diffuses, vacancies (V) and oxygen (O) in the passage region combine with hydrogen (H), forming VOH defects. VOH defects function as electron donors. As a result, a first high-concentration N-type region 304 is formed in the region between the hydrogen peak region 302 and the lower surface 23 of the semiconductor substrate 10, where the donor concentration is higher than the bulk donor doping concentration. In this specification, VOH defects are sometimes simply referred to as hydrogen donors. The first high-concentration region 304 in this example contains hydrogen donors. The bulk doping region 18 and the first high-concentration region 304 together are sometimes referred to as the drift region 19. The drift region 19 may be a region where the depletion layer expands when a voltage is applied to the semiconductor device 100, supporting more than half of the applied voltage.

[0110] The first high-concentration region 304 has its upper surface or upper end located on the upper surface 21 side of the semiconductor substrate 10, and its lower surface or lower end located on the lower surface 23 side of the semiconductor substrate 10. The first high-concentration region 304 includes the hydrogen peak portion 302. The first high-concentration region 304 may be provided continuously from the hydrogen peak portion 302 to the lower surface 23. However, the first high-concentration region 304 does not need to be provided in the region from the hydrogen peak portion 302 to the lower surface 23 where the buffer region 20, collector region 22, or cathode region 82 is provided. In this example, the first high-concentration region 304 is provided in the region from the hydrogen peak portion 302 to the buffer region 20.

[0111] Furthermore, a first high-concentration region 304 may be provided above the hydrogen peak portion 302. The hydrogen concentration peak has a predetermined full width at half maximum in the depth direction. Therefore, hydrogen is injected above the hydrogen peak portion 302 where the hydrogen concentration is at its maximum value, and vacancy-type defects are formed. For this reason, a first high-concentration region 304 is also formed above the hydrogen peak portion 302. However, the first high-concentration region 304 above the hydrogen peak portion 302 has a smaller width in the Z-axis direction compared to the first high-concentration region 304 below the hydrogen peak portion 302.

[0112] The hydrogen peak region 302 may have a lifetime adjustment function. That is, the carrier lifetime may show a minimum value in the vicinity of the hydrogen peak region 302. If the density of vacancy defects formed in the vicinity of the hydrogen peak region 302 is sufficiently higher than the oxygen concentration present in the vicinity of the hydrogen peak region 302, the density of vacancy defects that remain without becoming hydrogen donors will increase. The carrier lifetime is shortened as the remaining vacancy defects recombine with carriers. The hydrogen peak region 302 may have a lifetime adjustment function. Also, if the density of vacancy defects formed in the hydrogen peak region 302 is not sufficiently higher than the oxygen concentration present in the hydrogen peak region 302, most of the vacancy defects will become hydrogen donors. The hydrogen peak region 302 may function as a donor region with a high donor concentration without having a lifetime adjustment function.

[0113] Figure 4 shows an example of a cross-section of the cc in Figure 1. The cc cross-section is the XZ plane passing through the edge termination structure 90, the transistor section 70, and the diode section 80. The structures of the transistor section 70 and the diode section 80 are the same as those described in Figures 2 and 3. In Figure 4, the structures of the gate trench section 40 and the dummy trench section 30 are shown in a simplified manner.

[0114] In the semiconductor substrate 10, a well region 11 is provided between the edge termination structure 90 and the transistor portion 70. The well region 11 is a P+ type region in contact with the upper surface 21 of the semiconductor substrate 10. The well region 11 may extend to a position deeper than the lower ends of the gate trench portion 40 and the dummy trench portion 30. Parts of the gate trench portion 40 and the dummy trench portion 30 may be located inside the well region 11.

[0115] An interlayer insulating film 38 covering the well region 11 may be provided on the upper surface 21 of the semiconductor substrate 10. Above the interlayer insulating film 38, electrodes and wiring such as an emitter electrode 52 and an outer peripheral gate wiring 130 are provided. The emitter electrode 52 extends from above the active portion 160 to above the well region 11. The emitter electrode 52 may be connected to the well region 11 via a contact hole provided in the interlayer insulating film 38.

[0116] The outer gate wiring 130 is positioned between the emitter electrode 52 and the edge termination structure 90. Although the emitter electrode 52 and the outer gate wiring 130 are positioned separately from each other, the gap between the emitter electrode 52 and the outer gate wiring 130 is omitted in Figure 4. The outer gate wiring 130 is electrically insulated from the well region 11 by the interlayer insulating film 38.

[0117] The edge termination structure 90 is provided with a plurality of guard rings 92, a plurality of second high-concentration regions 202, a plurality of field plates 94, and a channel stopper 174. In addition, the hydrogen peak portion 302 and the first high-concentration region 304 described in Figure 3 are also provided in at least a part of the edge termination structure 90. The first high-concentration region 304 may be provided below the guard rings 92. The hydrogen peak portion 302 and the first high-concentration region 304 of the edge termination structure 90 may be provided in continuity with the hydrogen peak portion 302 and the first high-concentration region 304 of the transistor portion 70 and the diode portion 80. The hydrogen peak portion 302 and the first high-concentration region 304 may be provided along the entire X-axis direction of the edge termination structure 90.

[0118] In this example, the hydrogen peak portion 302 is located below the second high-concentration region 202 (i.e., at a position deeper than the second high-concentration region 202 when viewed from the upper surface 21). The hydrogen peak portion 302 may be located at a position deeper than the lower end of the guard ring 92. In other words, the hydrogen peak portion 302 may be located between the lower end of the guard ring 92 and the lower surface 23 of the semiconductor substrate 10. The hydrogen peak portion 302 may be located at a position deeper than the lower end of the well region 11. The hydrogen peak portion 302 may be located at a position deeper than the lower end of the trench portion.

[0119] The first high-concentration region 304 shown in Figure 4 is not in contact with the guard ring 92, but the first high-concentration region 304 may be in contact with the lower end of the guard ring 92. The first high-concentration region 304 may extend to the space between the two guard rings 92. The first high-concentration region 304 may or may not be in contact with the well region 11. The first high-concentration region 304 may or may not be in contact with the trench region. The first high-concentration region 304 may be located below the second high-concentration region 202.

[0120] The first high-concentration region 304 may be in contact with the well region 11. The first high-concentration region 304 may be in contact with the trench region. The first high-concentration region 304 may not be in contact with any of the emitter region 12, base region 14, or storage region 16. In other examples, the first high-concentration region 304 may be in contact with the storage region 16. The first high-concentration region 304 may be in contact with the base region 14. The first high-concentration region 304 may or may not be in contact with the channel stopper 174.

[0121] The first high-concentration region 304 may have the same or different lengths in the depth direction throughout the entire edge-terminal structure 90. The first high-concentration region 304 may have the same or different lengths in the depth direction between the edge-terminal structure 90 and the active portion 160.

[0122] In the edge termination structure 90, a collector region 22 may be provided in the region in contact with the lower surface 23. Each guard ring 92 may be provided on the upper surface 21 so as to surround the active portion 160. Multiple guard rings 92 may have the function of spreading the depletion layer generated in the active portion 160 to the outside of the semiconductor substrate 10. This prevents electric field concentration inside the semiconductor substrate 10 and improves the breakdown voltage of the semiconductor device 100.

[0123] The guard ring 92 in this example is a P+ type semiconductor region formed near the upper surface 21 by ion implantation. The guard ring 92 can be formed by selectively implanting a P-type dopant such as boron from the upper surface 21 of the semiconductor substrate 10 and then heat-treating it. The depth of the bottom of the guard ring 92 may be deeper than the depth of the bottom of the gate trench 40 and the dummy trench 30. The depth of the bottom of the guard ring 92 may be the same as or different from the depth of the bottom of the well region 11.

[0124] The upper surface of the guard ring 92 is covered by an interlayer insulating film 38. The field plate 94 is made of a metal such as aluminum or a conductive material such as polysilicon. The field plate 94 may be made of an aluminum-silicon alloy, such as AlSi or AlSiCu. The field plate 94 may be made of the same material as the outer gate wiring 130 or the emitter electrode 52. The field plate 94 is provided on the interlayer insulating film 38. In this example, the field plate 94 is connected to the guard ring 92 through through holes provided in the interlayer insulating film 38.

[0125] The channel stopper 174 is provided exposed on the upper surface 21 and side wall near the edge 102 of the semiconductor substrate 10. The channel stopper 174 is an N-type region with a higher doping concentration than the bulk doping region 18. The channel stopper 174 has the function of terminating the depletion layer generated in the active region 160 near the edge 102 of the semiconductor substrate 10. At least a portion of the field plate 94, the outer gate wiring 130, and the emitter electrode 52 are covered with a protective film such as polyimide or nitride film, but the protective film may be omitted in the drawings of this specification.

[0126] The second high-concentration region 202 is an N-type region where the donor concentration is higher than the bulk donor doping concentration. The second high-concentration region 202 is located between two adjacent guard rings 92. The second high-concentration region 202 may be in contact with the upper surface 21 of the semiconductor substrate 10. In this example, the second high-concentration region 202 is located in a range from the upper surface 21 to a depth below the lower end of the guard ring 92. In other examples, the second high-concentration region 202 may extend to a position deeper than the lower end of the guard ring 92. The second high-concentration region 202 may also be located between the well region 11 and the guard ring 92.

[0127] The second high-concentration region 202 may be formed by injecting a donor from the upper surface 21 of the semiconductor substrate 10 using the field plate 94 as a mask, and then heat-treating it. In this case, at least a portion of the second high-concentration region 202 is formed in an area not covered by the field plate 94. At least a portion of the second high-concentration region 202 in this example does not overlap with the field plate 94 in the Z-axis direction. The donor injected into the second high-concentration region 202 may be phosphorus, hydrogen, or other donors. When forming the second high-concentration region 202 to a greater depth, the acceleration energy of the donor may be varied to inject the donor at multiple depth positions.

[0128] In other examples, the second high-concentration region 202 may be formed by injecting a donor from the upper surface 21 of the semiconductor substrate 10 and heat-treating it, without using the field plate 94 as a mask. In this case, boron is selectively ion-implanted as a P-type dopant, and a guard ring is formed by heat treatment. Subsequently, phosphorus is ion-implanted as an N-type dopant, and the second high-concentration region 202 is formed by heat treatment. The heat treatment temperature after implanting the P-type dopant is higher than the heat treatment temperature after implanting the N-type dopant. The dose amount for ion implantation of the N-type dopant may be lower than the dose amount for the P-type dopant. In this case, ion implantation of the N-type dopant may be performed in the region where the guard ring is formed, or it may be performed selectively so as to avoid the region where the guard ring is formed.

[0129] In the example shown in Figure 4, the second high-concentration region 202 and the first high-concentration region 304 are separated in the Z-axis direction. A region with the same donor concentration as the bulk donor concentration may be provided between the second high-concentration region 202 and the first high-concentration region 304. The first high-concentration region 304 may extend to the upper surface 21.

[0130] Furthermore, if high-temperature, long-duration heat treatment is performed after hydrogen injection, the hydrogen donor will disappear, or the lifetime adjustment function in the hydrogen peak section 302 will be lost. For this reason, it is preferable to perform the hydrogen injection and heat treatment process towards the end of the manufacturing process of the semiconductor device 100. For example, the disappearance of the hydrogen donor can be suppressed by injecting hydrogen after forming a protective film on top of the field plate 94 or the like.

[0131] If the doping concentration on the upper surface 21 side of the edge termination structure 90 varies, the extent of the depletion layer on the edge termination structure 90 will also vary. If the second high-concentration region 202 and the first high-concentration region 304 are not provided, the bulk doping region 18 of the bulk donor concentration occupies a large area on the upper surface 21 side of the edge termination structure 90. The bulk donor concentration is the concentration of donors that have been present in the semiconductor substrate 10 since its manufacture, so it is relatively prone to variation.

[0132] In contrast, the second high-concentration region 202 and the first high-concentration region 304 are formed by ion implantation or the like. Since the concentration of ion implantation is relatively easy to control, the variation in the donor concentration of the second high-concentration region 202 and the first high-concentration region 304 is relatively small. Therefore, by providing the second high-concentration region 202 and the first high-concentration region 304, the variation in the spreading of the depletion layer extending from below the well region 11 to the edge termination structure portion 90 in the X-axis direction can be reduced, and the variation in the breakdown voltage of the semiconductor device 100 can also be reduced. Further, by providing the second high-concentration region 202 and the first high-concentration region 304, it is possible to suppress the depletion layer from spreading too much in the X-axis direction in the edge termination structure portion 90.

[0133] FIG. 5 shows an example of the carrier concentration distribution, the donor concentration distribution, and the defect density distribution in the d-d line shown in FIG. 4. The d-d line passes through the second high-concentration region 202, the bulk doping region 18, the first high-concentration region 304, the buffer region 20, and the collector region 22 in the edge termination structure portion 90. The carrier concentration distribution may be the same as the net doping concentration distribution as described above.

[0134] In this example, the bulk donor is phosphorus. Further, the second high-concentration region 202 is formed by implanting phosphorus from the upper surface 21 of the semiconductor substrate 10. The upper part of FIG. 5 shows the carrier concentration distribution, and the lower part of FIG. 5 shows the phosphorus concentration distribution in the second high-concentration region 202, the hydrogen concentration distribution in the first high-concentration region 304, and the VOH defect density distribution. In this example, the bulk donor concentration is N B is used. The bulk donor concentration is substantially uniform over the entire depth direction. The bulk donor concentration may use the minimum value of the concentration of donors distributed throughout the semiconductor substrate 10. For example, when phosphorus is distributed throughout the semiconductor substrate 10, the bulk donor concentration may be the minimum value of the phosphorus concentration in the semiconductor substrate 10.

[0135] The phosphorus concentration distribution in the second high-concentration region 202 has a first peak 318 where the phosphorus concentration reaches a maximum value. The depth position of the first peak 318 corresponds to the phosphorus injection position. The hydrogen concentration distribution in the first high-concentration region 304 reaches a maximum value at the hydrogen peak portion 302. Since hydrogen is injected from the lower surface 23 of the semiconductor substrate 10, the slope 322 of the hydrogen concentration distribution on the upper surface 21 side of the hydrogen peak portion 302 is steeper than the slope 320 of the hydrogen concentration distribution on the lower surface 23 side of the hydrogen peak portion 302. In this example, the phosphorus concentration and hydrogen concentration are the chemical concentrations of phosphorus and hydrogen.

[0136] The VOH defect density distribution may reflect the hydrogen concentration distribution or have a distribution similar in shape to the hydrogen concentration distribution. For example, the inflection points such as maxima, maxima, and kinks of each distribution may be located at approximately the same depth. Approximately the same depth means, for example, that there may be an error smaller than the full width at half maximum of the peak of the hydrogen concentration distribution. The VOH defect density distribution may have a flat region 323 with a substantially uniform density below the hydrogen peak region 302 on the lower surface 23 side. The VOH defect density distribution may coincide with the distribution of the first high-concentration region 304. For example, the concentration of the VOH defect density distribution may be the same as that of the first high-concentration region 304.

[0137] VOH defects are defects formed by the combination of hydrogen, oxygen, and vacancy defects. Therefore, the VOH defect density distribution may be limited by the distribution of the element with the lowest concentration or density among hydrogen, oxygen, and vacancy defects. If oxygen is distributed substantially uniformly in the semiconductor substrate 10, and the vacancy concentration is relatively low, the VOH defect density distribution will have a flat portion 323. In other cases, the VOH defect density may gradually decrease toward the lower surface 23, similar to the slope 320 of the hydrogen concentration distribution. For example, if the hydrogen concentration is relatively low in areas other than the hydrogen peak portion 302, the VOH defect density distribution will reflect the hydrogen concentration distribution.

[0138] In this example, the carrier concentration distribution has a peak 312 at the same depth as the hydrogen peak 302. Furthermore, in the second high-concentration region 202, there is a peak 314 at the same depth as the first peak 318 of the phosphorus concentration distribution. When the distance D1 between peak 312 and peak 314 is sufficiently large, the bulk donor concentration N is located between peak 312 and peak 314. B Base carrier concentration N 00 A bulk doping region 18 is provided. Distance D1 is the distance between the peak of peak 312 and the peak of peak 314. Distance D1 may also be the distance between the peak of the first peak 318 and the peak of the hydrogen peak region 302. In this specification, distance D1 may be used as the distance in the Z-axis direction between the hydrogen peak region 302 and the second high-concentration region 202.

[0139] The first high-concentration region 304 may have a flat portion 313 between the peak 312 and the buffer region 20 in which the carrier concentration is substantially uniform. The carrier concentration in the flat portion 313 may fluctuate within a range of at least N0, and not exceeding twice the minimum value N0, between the peak 312 and the buffer region 20. The carrier concentration in the flat portion 313 may fluctuate within a range of at least N0, and not exceeding 1.5 times the minimum value N0, or within a range of at least N0, and not exceeding 1.2 times the minimum value N0. The length of the flat portion 313 in the Z-axis direction may be at least half the length of the first high-concentration region 304 in the Z-axis direction. Furthermore, the carrier concentration in the first high-concentration region 304 may gradually decrease from the peak 312 toward the buffer region 20.

[0140] Similarly, the VOH defect density in the flat portion 323 may fluctuate within a range of more than the minimum value of the VOH defect density between the hydrogen peak portion 302 and the buffer region 20, and less than or equal to twice that minimum value. In the flat portion 313, the VOH defect density may fluctuate within a range of more than the minimum value and less than or equal to 1.5 times that minimum value, and may fluctuate within a range of more than the minimum value and less than or equal to 1.2 times that minimum value. The length of the flat portion 323 in the Z-axis direction may be more than half the length of the first high-concentration region 304 in the Z-axis direction.

[0141] The peak carrier concentration N1 in the second high-concentration region 202 is greater than the minimum carrier concentration N0 in the first high-concentration region 304. The peak value N1 may be 2 times or more, 5 times or more, 10 times or more, or 20 times or more than the minimum value N0. The peak value N1 is equal to the base carrier concentration N 00 It may be 10 times or more, and may be 100 times or more. The base carrier concentration in this example is N 00 This is the doping concentration of the bulk donor.

[0142] Figure 6 shows an example of an equipotential surface in the edge termination structure 90. In Figure 6, the hydrogen peak portion 302 is omitted. Also, the hatching in the first high-concentration region 304 is omitted.

[0143] Figure 6 shows the equipotential surface 306 when the second high-concentration region 202 and the first high-concentration region 304 are provided, the equipotential surface 308 when the first high-concentration region 304 is provided but the second high-concentration region 202 is not provided, and the equipotential surface 310 when neither the second high-concentration region 202 nor the first high-concentration region 304 are provided. Equipotential surfaces 306, 308, and 310 are all equipotential surfaces at a predetermined potential Vo.

[0144] If the second high-concentration region 202 and the first high-concentration region 304 are not provided, the equipotential surface 310 extends in the depth direction and the outer periphery direction of the semiconductor substrate 10. The extent of the equipotential surface 310 is determined by the donor concentration of the bulk donor. Since the donor concentration of the bulk donor is set low, the extent of the equipotential surface 310 is larger in both the depth direction and the outer periphery direction of the semiconductor substrate compared to equipotential surfaces 306 and 308.

[0145] In the case where the first high-concentration region 304 is provided without the second high-concentration region 202, the donor concentration of the bulk donor is lower than the donor concentration of the first high-concentration region 304. Therefore, the curvature of the equipotential surface 308 changes at the interface between the bulk-doping region 18 and the first high-concentration region 304. As a result, the equipotential surface 308 extends outward towards the outer periphery of the semiconductor device 100 in the bulk-doping region 18 compared to the first high-concentration region 304. However, in the first high-concentration region 304, the expansion of the equipotential surface 308 in the depth direction and outward direction of the semiconductor substrate 10 is suppressed compared to the equipotential surface 310. This is because the donor concentration of the first high-concentration region 304 is higher than the bulk donor concentration. As a result, the outward expansion of the equipotential surface 308 in the bulk-doping region 18 can be made significantly narrower compared to the equipotential surface 310.

[0146] When a second high-concentration region 202 and a first high-concentration region 304 are provided, the doping concentration in the second high-concentration region 202 is higher than that in the bulk doping region 18. Therefore, the equipotential surface 306 is less likely to spread outwards towards the outer periphery of the semiconductor device 100 compared to the equipotential surface 308. As a result, the equipotential surface 306 is closer to the well region 11 than the equipotential surface 308. This prevents the depletion layer in the edge termination structure 90 from spreading too far laterally. Therefore, the length of the edge termination structure 90 in the outer periphery can be shortened, and the area of ​​the upper surface 21 of the semiconductor device 100 can be reduced.

[0147] Figure 7 shows another example of the carrier concentration distribution, donor concentration distribution, and defect density distribution along the dd line shown in Figure 4. In this example, the second high-concentration region 202 is formed by injecting hydrogen from the upper surface 21 of the semiconductor substrate 10. In other words, the second high-concentration region 202 includes hydrogen donors such as VOH defects. The distributions outside the second high-concentration region 202 are the same as in the example in Figure 5.

[0148] The hydrogen concentration distribution in the second high-concentration region 202 reaches a maximum value at the first peak 318. Since hydrogen is injected from the upper surface 21 of the semiconductor substrate 10, the slope 324 of the hydrogen concentration distribution on the lower surface 23 side of the first peak 318 is steeper than the slope 326 of the hydrogen concentration distribution on the upper surface 21 side of the first peak 318.

[0149] In the second high-concentration region 202, the VOH defect density distribution may have a distribution similar in shape to the hydrogen concentration distribution. For example, the inflection points such as maxima, maxima, and kinks of each distribution may be located at approximately the same depth. The VOH defect density distribution may have a flat region 327 with a substantially uniform density on the upper surface 21 side of the first peak 318 of the hydrogen concentration distribution. In another example, the VOH defect density in the second high-concentration region 202 may gradually decrease toward the upper surface 21 side, similar to the slope 326 of the hydrogen concentration distribution.

[0150] In this example, the carrier concentration distribution has a peak 314 at the same depth as the first peak 318 of the hydrogen concentration distribution in the second high-concentration region 202. Between peak 312 and peak 314, the bulk donor concentration N B Base carrier concentration N 00 A region having the above may be provided. The carrier concentration distribution may have a flat portion 317 between the peak 314 and the upper surface 21 where the carrier concentration is substantially uniform.

[0151] In the flat section 317, the carrier concentration may fluctuate within a range of N0 or more and twice the minimum carrier concentration between the peak 314 and the upper surface 21. In the flat section 317, the carrier concentration may fluctuate within a range of N0 or more and 1.5 times the minimum carrier concentration, and may fluctuate within a range of N0 or more and 1.2 times the minimum carrier concentration. Similarly, in the flat section 327, the VOH defect density may fluctuate within a range of N0 or more and twice the minimum VOH defect density between the first peak 318 of the hydrogen concentration distribution and the upper surface 21. In the flat section 327, the VOH defect density may fluctuate within a range of N0 or more and 1.5 times the minimum VOH defect density, and may fluctuate within a range of N0 or more and 1.2 times the minimum VOH defect density. Furthermore, in the second high-concentration region 202, the carrier concentration may gradually decrease from the peak 314 toward the upper surface 21.

[0152] The carrier concentration at peak 314 in the second high-concentration region 202 may be the same as or different from the carrier concentration at peak 312 in the first high-concentration region 304. The carrier concentration at peak 314 in the second high-concentration region 202 is greater than the minimum value N0 of the carrier concentration in the second high-concentration region 202. The carrier concentration at peak 314 may be at least twice, five times, or ten times the minimum value N0. The carrier concentration at peak 314 is equal to the base carrier concentration N 00 It may be 10 times or more, and may also be 100 times or more.

[0153] Figure 8 shows another example of the cc cross-section in Figure 1. In this example, the semiconductor device 100 differs from the example shown in Figure 4 in the depth range in which the first high-concentration region 304 is provided. The position of the hydrogen peak portion 302 in the depth direction may also differ from the example shown in Figure 4. The other structures are the same as those shown in Figure 4.

[0154] In this example, the first high-concentration region 304 is in contact with the guard ring 92. The first high-concentration region 304 is in contact with at least the lower end of the guard ring 92. The first high-concentration region 304 may also be provided between two adjacent guard rings 92. In this example, the first high-concentration region 304 is not in contact with the second high-concentration region 202. The first high-concentration region 304 may be provided on the upper surface 21 side of the bottom surface of the trench. That is, the first high-concentration region 304 may extend to the mesa portion sandwiched between adjacent trenches. A bulk doping region 18 with bulk donor concentration may be provided between the first high-concentration region 304 and the second high-concentration region 202.

[0155] In this example, the hydrogen peak portion 302 does not need to be in contact with the guard ring 92. That is, the hydrogen peak portion 302 may be located below the guard ring 92. In other examples, the hydrogen peak portion 302 may be in contact with the guard ring 92. The first high-concentration region 304 may reach the upper surface 21.

[0156] In this example, since the lower end of the guard ring 92 is covered by the first high-concentration region 304, variations in the donor concentration in regions where electric fields tend to concentrate can be reduced. Therefore, variations in withstand voltage can be further reduced.

[0157] Figure 9 shows another example of the cc cross section in Figure 1. The semiconductor device 100 in this example differs from the example shown in Figure 4 or Figure 8 in the depth range in which the second high-concentration region 202 and the first high-concentration region 304 are provided. The other structures are the same as those shown in Figure 4 or Figure 8.

[0158] In this example, a portion of the second high-concentration region 202 and a portion of the first high-concentration region 304 are located within the same region. The lower end of the second high-concentration region 202 is located within the range of the first high-concentration region 304, and the upper end of the first high-concentration region 304 is located within the range of the second high-concentration region 202. This configuration connects the second high-concentration region 202 and the first high-concentration region 304, thereby reducing the bulk donor concentration region in the edge termination structure 90. This further reduces pressure resistance variation.

[0159] The second high-concentration region 202 may be formed to a position deeper than the lower end of the guard ring 92. This allows for easy connection between the second high-concentration region 202 and the first high-concentration region 304. In other examples, the second high-concentration region 202 may be formed to a position shallower than the lower end of the guard ring 92. In this example, the hydrogen peak portion 302 is located within the second high-concentration region 202. The hydrogen peak portion 302 may be provided at a position in contact with the guard ring 92. This allows the first high-concentration region 304 to be formed close to the upper surface 21, and allows for easy connection between the second high-concentration region 202 and the first high-concentration region 304.

[0160] In the edge terminal structure 90, beyond the outermost guard ring 92, a bulk doping region 18 of bulk donor concentration may remain, or it may not remain and a second high-concentration region 202 may be provided. In this example, it does not remain. In the example in Figure 9, the second high-concentration region 202 does not cover a part of the lower end of the guard ring 92. As shown by the dashed line in Figure 9, the second high-concentration region 202 may cover the entire guard ring 92. The first high-concentration region 304 may reach the upper surface 21.

[0161] Figure 10 shows an example of the hydrogen concentration distribution along the ee line in Figure 9. Figure 10 shows the chemical concentration distribution of hydrogen. In this example, the second high-concentration region 202 is shown to be formed by a hydrogen donor, but the second high-concentration region 202 may also be formed by donors other than hydrogen, such as phosphorus.

[0162] In this example, the first peak 318 of the hydrogen concentration distribution due to hydrogen injected from the upper surface 21 and the hydrogen peak portion 302 of the hydrogen concentration distribution due to hydrogen injected from the lower surface 23 overlap. Overlapping peaks mean that the apex of one peak is included within the full width at half maximum of the other peak.

[0163] The hydrogen concentration distribution may have a single peak where the first peak 318 and the hydrogen peak portion 302 are superimposed at the position where the second high-concentration region 202 and the first high-concentration region 304 overlap. The hydrogen concentration distribution may gradually decrease from this peak to the upper surface 21, and then gradually decrease from this peak to the buffer region 20.

[0164] Furthermore, the carrier concentration distribution in this example may have a single peak at the depth position of the first peak 318 and the hydrogen peak portion 302. The carrier concentration distribution may have a flat portion 317 (see Figure 7) on the upper surface 21 side of the peak and a flat portion 313 (see Figure 7) on the lower surface 23 side of the peak.

[0165] Furthermore, the VOH defect density distribution in this example may have a single peak at the depth position of the first peak 318 and the hydrogen peak portion 302. The VOH defect density distribution may have a flat portion 327 (see Figure 7) on the upper surface 21 side of the peak and a flat portion 323 (see Figure 7) on the lower surface 23 side of the peak.

[0166] Figure 11 shows another example of the hydrogen concentration distribution along the ee line in Figure 9. Figure 11 shows the chemical concentration distribution of hydrogen. In this example, the second high-concentration region 202 is shown to be formed by a hydrogen donor, but the second high-concentration region 202 may also be formed by donors other than hydrogen, such as phosphorus.

[0167] In this example, the first peak 318 of the hydrogen concentration distribution due to hydrogen injected from the upper surface 21 and the hydrogen peak portion 302 of the hydrogen concentration distribution due to hydrogen injected from the lower surface 23 are located separately. However, the first peak 318 is located in a position that overlaps with the first high-concentration region 304, and the hydrogen peak portion 302 is located in a position that overlaps with the second high-concentration region 202. In other words, the hydrogen peak portion 302 is located between the first peak 318 and the upper surface 21 of the semiconductor substrate 10.

[0168] The slope 326 on the upper surface 21 side of the first peak 318 is gentler than the slope 324 on the lower surface 23 side. Similarly, the slope 320 on the lower surface 23 side of the hydrogen peak section 302 is gentler than the slope 322 on the upper surface 21 side. In other words, in the first peak 318 and the hydrogen peak section 302, relatively gentle slopes (slope 326 and slope 320) are positioned opposite each other.

[0169] Furthermore, the carrier concentration distribution in this example may have peaks (peaks 314 and 312 in Figure 7) at depth positions of the first peak 318 and the hydrogen peak portion 302, respectively. The carrier concentration distribution may have a flat portion 317 (see Figure 7) on the upper surface 21 side of peak 312, and a flat portion 313 (see Figure 7) on the lower surface 23 side of peak 314.

[0170] Furthermore, the VOH defect density distribution in this example may have peaks at the depth positions of the first peak 318 and the hydrogen peak portion 302, respectively. The VOH defect density distribution may have a flat portion 327 (see Figure 7) further towards the upper surface 21 than the upper surface peak, and a flat portion 323 (see Figure 7) further towards the lower surface 23 than the lower surface peak.

[0171] Figure 12 shows another example of the cc cross section in Figure 1. In this example, the semiconductor device 100 differs from the example shown in Figures 4, 8, or 9 in the arrangement of high-concentration regions in at least a portion of the region 91 of the edge termination structure 90. In region 91, a third high-concentration region 203 may be provided instead of the second high-concentration region 202. The third high-concentration region 203 is a high-concentration region formed to a deeper position than the second high-concentration region 202. Region 91 may be provided with one or more of the bulk doping region 18, the second high-concentration region 202, the first high-concentration region 304, and the third high-concentration region 203. The other structures are the same as the example shown in Figures 4, 8, or 9.

[0172] In the example shown in Figure 12, the first high-concentration region 304 is not provided in a region 91 of a predetermined width that is in contact with the edge 102 of the semiconductor substrate 10 within the edge termination structure 90. Region 91 may include one or more guard rings 92. Region 91 may be provided with a bulk doping region 18 of bulk donor concentration instead of the first high-concentration region 304. The first high-concentration region 304 does not have to be formed in the edge termination structure 90. The outer edge of the first high-concentration region 304 may be located on the inner side of the innermost guard ring 92. In other examples, region 91 may also be provided with the first high-concentration region 304. The first high-concentration region 304 of region 91 may have the same Z-axis length as, shorter than, or longer than, the first high-concentration region 304 located inside region 91.

[0173] The edge termination structure 90 inside region 91 has the same structure as the example shown in Figure 4, Figure 8, or Figure 9. The edge termination structure 90 inside region 91 includes one or more guard rings 92. As shown in Figures 4, 8, or Figure 9, the first high-concentration region 304 may be provided in a range that includes the lower end of the guard ring 92, or it may be provided in a range that does not include the lower end of the guard ring 92.

[0174] Region 91 may or may not have a second high-concentration region 202. Alternatively, instead of the second high-concentration region 202, a third N-type high-concentration region 203 with a donor concentration higher than the bulk donor concentration may be provided. The donor concentration of the third high-concentration region 203 may be the same as or different from the donor concentration of the second high-concentration region 202. The third high-concentration region 203 is provided from the upper surface 21 of the semiconductor substrate 10 to a position deeper than the lower end of the second high-concentration region 202. In this example, the third high-concentration region 203 may be provided to a position deeper than the lower end of the guard ring 92. A bulk doping region 18 is provided between the third high-concentration region 203 and the buffer region 20.

[0175] The third high-concentration region 203 may be formed by injecting a donor such as phosphorus or hydrogen from the top surface 21. The injection depth of the donor in the third high-concentration region 203 may be deeper than the injection depth of the donor in the second high-concentration region 202. Heat treatment of the second high-concentration region 202 and the third high-concentration region 203 may be performed individually or in common.

[0176] Figure 13 is an enlarged cross-sectional view of the vicinity of the well region 11 and the guard ring 92. Figure 13 shows the XZ cross-section. Also, Figure 13 shows the well region 11 and the guard ring 92, but omits the configuration of the second high-concentration region 202, bulk doping region 18, first high-concentration region 304, and hydrogen peak region 302.

[0177] In Figure 13, let D2 be the distance between point 330 in the well region 11 and point 332 in the guard ring 92-1 closest to the well region 11. Point 330 is the point in the well region 11 closest to the guard ring 92-1 on the upper surface 21 of the semiconductor substrate 10. Point 332 is the point in the guard ring 92-1 furthest from point 330. In other words, distance D2 is the maximum distance between point 330 in the well region 11 and each point in the guard ring 92-1 closest to the well region 11. Let D1 be the distance in the Z-axis direction between the hydrogen peak region 302 shown in Figure 4, etc., and the second high-concentration region 202. Distance D1 is the distance between the peak of the carrier concentration in the second high-concentration region 202 and the peak of the hydrogen peak region 302, as shown in Figures 5 and 7. Distance D1 may be smaller than distance D2. By reducing the distance D1, the bulk-donor concentration range can be narrowed, thereby suppressing variability in doping concentrations.

[0178] Let D3 be the distance between point 330 in the well region 11 and point 334 in the guard ring 92-1. Point 334 is the point on the upper surface 21 of the semiconductor substrate 10 that is furthest from the well region 11 within the guard ring 92-1. Distance D1 may be smaller than distance D3.

[0179] Let D4 be the distance between point 330 in the well region 11 and point 336 in the guard ring 92-1. Point 336 is the lowest point in the guard ring 92-1. Point 336 may also be the lower end of the guard ring 92-1 at its X-axis center. Distance D1 may be smaller than distance D4.

[0180] Let D5 be the distance between point 330 in the well region 11 and point 338 in the guard ring 92-1. Point 338 is the point on the upper surface 21 of the semiconductor substrate that is closest to the well region 11 within the guard ring 92-1. Distance D1 may be smaller than distance D5.

[0181] Figure 14 shows another example of the structure of the second high-concentration region 202. In this example, the position of the lower end of the guard ring 92 in the Z-axis direction is denoted as Z1.

[0182] The second high-density region 202 has a region located on the upper surface 21 side of position Z1 and a region located on the lower surface 23 side of position Z1. In this example, the second high-density region 202 is continuously provided from position Z0, which is in contact with the upper surface 21 of the semiconductor substrate 10, down to a depth position Z2. Position Z2 is further from the upper surface 21 than position Z1.

[0183] In this example, the second high-concentration region 202, when viewed from the lower surface 23 side of the semiconductor substrate 10, covers a portion of the guard ring 92. That is, in the Z-axis direction, a portion of the second high-concentration region 202 overlaps with a portion of the guard ring 92. The region of the second high-concentration region 202 provided from depth position Z1 to Z2 may cover a portion of the guard ring 92. This can alleviate electric field concentration near the lower end of the guard ring 92.

[0184] Figure 14 schematically shows the equipotential surface 262. As shown in Figure 14, the electric field may be concentrated near the lower region 260 of the guard ring 92. The lower region 260 may be the region where the curvature of the boundary line between the guard ring 92 and the N-type region is maximum. The lower region 260 may also be the region where the change in the slope of the boundary line between the guard ring 92 and the N-type region (i.e., the second derivative) is maximum. The lower region 260 is located near the lower end of the guard ring 92. The lower end of the guard ring 92 is the part of the guard ring 92 located at the deepest position.

[0185] The guard ring 92 may also have a lower region 260 and a lower region 261. If the cross-sectional shape of the guard ring 92 is symmetrical with respect to a center line parallel to the Z-axis, the guard ring 92 has lower regions 260 and 261 in symmetrical positions. Of the two lower regions 260, the one closer to the well region 11 is designated as lower region 261, and the one further from the well region 11 is designated as lower region 260. As shown in Figure 14, the electric field tends to concentrate in the vicinity of the lower region 260.

[0186] By providing a second high-concentration region 202, a high-concentration N-type region can be placed near the lower region 260 and the lower region 261. This makes it possible to suppress the expansion of the depletion layer while mitigating electric field concentration in the vicinity of the lower region 260 and the lower region 261. Preferably, the second high-concentration region 202 covers the lower region 260. In other words, preferably, the second high-concentration region 202 is in contact with the lower region 260. The second high-concentration region 202 may further cover the lower region 261. The cross-sectional shape of the second high-concentration region 202 may be symmetric with respect to a center line parallel to the Z-axis.

[0187] Furthermore, since the electric field is concentrated between the guard rings 92 and in the region near the lower end of the guard rings 92, variations in the donor concentration in these regions will result in variations in breakdown voltage. If the second high-concentration region 202 is not provided, a bulk-doping region 18 is formed in this region. The donor concentration in the bulk-doping region 18 is the concentration of donors that have been present since the manufacturing of the semiconductor substrate 10, so it is relatively prone to variations. In contrast, in this example, a second high-concentration region 202 is provided in this region. The second high-concentration region 202 is formed by ion implantation, etc. Since the concentration of ion implantation is relatively easy to control, the variation in the donor concentration in the second high-concentration region 202 is relatively small. For this reason, by providing the second high-concentration region 202, the breakdown voltage variation of the semiconductor device 100 can also be reduced.

[0188] The second high-concentration region 202 is provided in at least one of the regions sandwiched by the guard ring 92. The second high-concentration region 202 may be provided in all of the regions sandwiched by the guard ring 92.

[0189] Each guard ring 92 may have a region 204 that is not covered by the second high-concentration region 202 when viewed from the lower surface 23 side of the semiconductor substrate 10. Region 204 may include the lower end of the guard ring 92 in the center in the X-axis direction. Region 204 may be in contact with the bulk doping region 18. Region 204 may be in contact with the first high-concentration region 304.

[0190] The width W2 of region 204 in the X-axis direction is smaller than the width W1 of the guard ring 92 on the upper surface 21 of the semiconductor substrate 10. The width W2 may be 10% or more, 30% or more, 50% or more, or 70% or more of the width W1.

[0191] Figure 15 shows another example of the second high-concentration region 202. The structure other than the second high-concentration region 202 is the same as the example shown in Figure 14. The second high-concentration region 202 in this example has an upper portion 206 and a lower portion 208. The upper portion 206 and the lower portion 208 are provided separately from each other. In this example, a bulk doping region 18 with bulk donor concentration is provided between the upper portion 206 and the lower portion 208. Note that when an N-type dopant is injected from the upper surface 21 to the lower portion 208, donor may be formed in the region through which the N-type dopant has passed. In this case, the donor concentration gradually decreases from the lower portion 208 toward the upper surface 21. Between the lower portion 208 and the upper portion 206, the donor concentration may gradually decrease from the lower portion 208 toward the upper portion 206. For example, when hydrogen is used as an N-type dopant, a vacancy defect (V) formed in the region through which the hydrogen has passed combines with oxygen (O) contained in the semiconductor substrate 10 and hydrogen (H) diffused from the lower portion 208 to form a VOH defect. The VOH defect functions as a donor.

[0192] The upper portion 206 is provided between the two guard rings 92, in contact with the upper surface 21 of the semiconductor substrate 10. The upper portion 206 may be positioned away from the guard rings 92. This suppresses the diffusion of the highly doped donor in the upper portion 206 into the guard rings 92. In other examples, the upper portion 206 may be in contact with the guard rings 92. The upper portion 206 may have a portion that does not overlap with the field plate 94 as shown in Figure 4, etc. The upper portion 206 may be provided so as to overlap the entire gap between two adjacent field plates 94.

[0193] The lower portion 208 is provided from a position shallower than the lower end of the guard ring 92 to a position Z2 deeper than the lower end of the guard ring 92. In this example, the lower portion 208 is provided in contact with the side 93-2 of the two sides 93-1 and 93-2 of the guard ring 92, the side furthest from the well region 11. In Figure 5, side 93-1 of the guard ring 92 is the side closer to the well region 11 than the center of the guard ring 92 in the X-axis direction. Side 93-2 of the guard ring 92 is the side opposite to side 93-1. The lower portion 208 does not have to be in contact with side 93-1, but it may be. By providing the lower portion 208 in contact with side 93-2, regions where electric fields tend to concentrate can be protected. It is preferable that the lower portion 208 is in contact with the lower region 260. Also, the width W2 of region 204 in this example is greater than half the width W1 of the guard ring 92.

[0194] Let Z3 be the position of the upper end of the lower portion 208 in the Z-axis direction. The distance Z1-Z3 between positions Z1 and Z3 in the Z-axis direction may be the same as the distance Z2-Z1 between positions Z1 and Z2 in the Z-axis direction. The distance Z2-Z1 may be greater than the distance Z1-Z3. This makes it easier to protect regions where the electric field is likely to concentrate. The distance Z2-Z1 may be less than the distance Z1-Z3.

[0195] Furthermore, a second high-concentration region 202 may be formed using multiple types of N-type dopants. For example, an upper portion 206 may be formed by injecting a first dopant such as phosphorus, and a lower portion 208 may be formed by injecting a second dopant such as hydrogen. In this case, the upper portion 206 contains the first dopant (phosphorus) at a higher concentration than the second dopant (hydrogen), and the lower portion 208 contains the second dopant (hydrogen) at a higher concentration than the first dopant (phosphorus).

[0196] Furthermore, the dose of N-type dopant injected into the second high-concentration region 202 may be adjusted according to the resistivity or donor concentration of the semiconductor substrate 10 before the injection of the N-type dopant. This allows for more precise adjustment of the resistivity or donor concentration of the semiconductor substrate 10 after the formation of the second high-concentration region 202.

[0197] Figures 16A and 16B illustrate some of the manufacturing processes of the semiconductor device 100. Figures 16A and 16B show the process of forming the lower portion 208 of the second high-concentration region 202. In this example, the field plate 94, the outer gate wiring 130, and electrodes such as the emitter electrode 52 are used as masks to inject the N-type dopant into the lower portion 208. In the edge termination structure 90, the N-type dopant is injected through the gap 95 between adjacent field plates 94.

[0198] In this example, an N-type dopant is injected after forming each electrode, such as the interlayer insulating film 38 and the field plate 94. The N-type dopant is, for example, hydrogen. Alternatively, an N-type dopant may be injected into the lower portion 208 after forming the well region 11, the upper portion 206, and the guard ring 92. After injecting the N-type dopant and forming the lower portion 208, a protective film such as a polyimide or nitride film may be formed above each electrode, such as the field plate 94, the outer gate wiring 130, and the emitter electrode 52.

[0199] In this example, since the field plate 94 is used as a mask, the manufacturing process of the semiconductor device 100 can be simplified. At least a portion of the lower portion 208 in this example overlaps with the gap 95 in the Z-axis direction. In the lower portion 208, the region where the donor concentration is at its maximum may also overlap with the gap 95 in the Z-axis direction.

[0200] The field plate 94 may overlap with a portion of the lower portion 208 in the Z-axis direction. The N-type dopant injected into the lower portion 208 diffuses in the X-axis direction, forming a portion of the lower portion 208 at a position overlapping with the field plate 94. The field plate 94 may overlap with a portion or all of the upper portion 206.

[0201] Let X1 be the center position of the field plate 94 in the X-axis direction, and let X2 be the center position of the guard ring 92 in the X-axis direction. The center position X1 of the field plate 94 may be positioned closer to the well area 11 than the center position X2 of the guard ring 92. This makes it easier to form the lower portion in the lower region 260 without forming the lower portion 208 in the lower region 261 shown in Figure 15.

[0202] In this example, the position of the lower end of the well region 11 in the Z-axis direction is denoted as Z4. In Figure 16A, the position Z1 of the lower end of the guard ring 92 coincides with the position Z4 of the lower end of the well region 11. In other words, the lower portion 208 is located in a region deeper than the well region 11. On the other hand, in Figure 16B, the position Z4 of the lower end of the well region 11 is located at a deeper position than the position Z1 of the lower end of the guard ring 92. Also, in Figure 16B, the position Z2 of the lower portion 208 is located closer to the upper surface 21 than the position Z4 of the lower end of the well region 11. In other words, the lower portion 208 is located in a region shallower than the well region 11. Furthermore, in both Figure 16A and Figure 16B, the doping concentration of the lower portion 208 is lower than the doping concentration of the well region 11.

[0203] Figures 17A and 17B are cross-sectional views near the emitter electrode 52 and the outer gate wiring 130. Figure 17A corresponds to the example in Figure 16A, and Figure 17B corresponds to the example in Figure 16B. That is, the depth position Z4 of the well region 11 in Figure 17A is the same as the example shown in Figure 16A, and the depth position Z4 of the well region 11 in Figure 17B is the same as the example shown in Figure 16B. In Figures 17A and 17B, structures such as trenches are simplified, and contact holes in the interlayer insulating film 38 are omitted. A gap 95 is provided between the emitter electrode 52 and the outer gate wiring 130.

[0204] When an N-type dopant is injected using the field plate 94, the outer gate wiring 130, and the emitter electrode 52 as masks, the N-type dopant is also injected through the gap 95 between the outer gate wiring 130 and the emitter electrode 52. In Figures 17A and 17B, the region in which the N-type dopant is injected is designated as region 209. Region 209 is located at the same depth as the lower portion 208 shown in Figures 16A and 16B.

[0205] A well region 11 is formed below the gap 95. Therefore, if the well region 11 and the lower end of the guard ring 92 are aligned as shown in Figure 16A, and the lower portion 208 is positioned deeper than the well region 11, the lower portion 208 will be formed to protrude from the lower end of the well region 11 as shown in Figure 17A.

[0206] In contrast, as shown in Figure 16B, if the lower end position Z4 of the well region 11 is deeper than the lower end position Z1 of the guard ring 92, the lower portion 208 can be positioned in a region shallower than the well region 11, so that the lower portion 208 does not protrude from the lower end of the well region 11, as shown in Figure 17B. In this case, the lower end position Z4 of the well region 11 is further from the upper surface 21 of the semiconductor substrate 10 than the lower end position Z2 of the guard ring 92. In other words, the well region 11 is provided deeper than the guard ring 92. This makes it possible to form the lower portion 208 deeper than the guard ring 92 while being shallower than the well region 11. In the examples of Figures 16A and 17A, a mask that slows down or shields ions may be provided at a position covering the gap 95 above the well region 11. This also prevents the lower portion 208 from protruding from the lower end of the well region 11.

[0207] Furthermore, if the doping concentration in the lower portion 208 is higher than that in the well region 11, the conductivity type of region 209 in Figures 17A and 17B will reverse from P-type to N-type. As a result, a PN junction may be formed in an unintended location, which may cause the characteristics of the semiconductor device 100 to change.

[0208] In contrast, by making the doping concentration in the lower portion 208 lower than the doping concentration in the well region 11, it is possible to prevent the conductivity type of region 209 from becoming N-type. The doping concentration in the well region 11 may be higher than, the same as, or lower than the doping concentration of the guard ring 92. The doping concentration of the guard ring 92 is 1.0 × 10⁻⁶ 17 atoms / cm 3 The following is acceptable:

[0209] In the examples shown in Figures 16A to 17B, an example is described in which ion implantation of the lower portion 208 is performed using the field plate 94 as a mask. In other examples, a protective film such as polyimide may be formed above the field plate 94, and then ion implantation may be performed using the protective film as a mask.

[0210] Figures 18 and 19 show examples of ion implantation using the protective film 140 as a mask. Figure 18 shows another example of a cross-section near the edge termination structure 90. Figure 19 shows another example of a cross-section near the emitter electrode 52 and the outer gate wiring 130.

[0211] As shown in Figure 18, the protective film 140 has an opening 98 above the lower portion 208. The opening 98 passes through the gap 95 of the field plate 94. Neither the protective film 140 nor the field plate 94 is provided at the location where the opening 98 and the gap 95 overlap. In this example, an N-type dopant is injected into the region of the lower portion 208 through the opening 98 and the gap 95. At this time, as shown in Figure 19, by not providing an opening in the protective film 140 above the well region 11, it is also possible to prevent ion implantation into the well region 11.

[0212] Alternatively, instead of the protective film 140, a mask pattern may be formed using photoresist or the like, and N-type dopant implantation may be performed. Or, when performing ion implantation of the lower portion 208 using the gap between the field plates 94 above the guard ring 92 as a mask, the gap 95 between the field plates 94 above the well region 11 may be covered with resist. In this case, the resist can prevent ion implantation into the semiconductor substrate 10 by shielding it, or the resist can slow down the process, making the region 209 shallower and preventing it from protruding below the well region 11. Note that a depression may be used instead of the opening 98. The depression may be formed by etching the protective film 140, or it may be formed during the deposition of the protective film 140. If the protective film 140 is a nitride film or the like, a depression reflecting the presence or absence of the gap 95 between the field plates 94 may be formed during deposition.

[0213] Figure 20 shows another example of the cc cross-section in Figure 1. The semiconductor device 100 in this example differs from the semiconductor device 100 described in Figures 1 to 19 in the range in the XY plane where the first high-concentration region 304 is provided. The range in the XY plane where the hydrogen peak portion 302 is provided may also differ from the example described in Figures 1 to 19. The structure other than the first high-concentration region 304 and the hydrogen peak portion 302 may be the same as any embodiment described in Figures 1 to 19. In Figure 20, the arrangement of the first high-concentration region 304 and the hydrogen peak portion 302 is different from the example shown in Figure 4. Also, in the example shown in Figure 20, the second high-concentration region 202 is not provided compared to the example shown in Figure 4. The other structures are the same as the example shown in Figure 4.

[0214] In this example, the first high-concentration region 304 is provided in part on the edge termination structure 90 and in a range that does not reach the active region 160. The first high-concentration region 304 may be provided only on the edge termination structure 90, or it may be provided from the edge termination structure 90 to below the well region 11. In the example of Figure 20, the first high-concentration region 304 is provided from the edge of the semiconductor substrate 10 in the X-axis direction to below the well region 11. The first high-concentration region 304 may reach the upper surface 21.

[0215] Furthermore, the first high-concentration region 304b may be provided so as to include at least the active portion 160, or to include only the active portion 160. The first high-concentration region 304b may include the first high-concentration region 304 in a plan view (upper surface 21 or lower surface 23) or in the depth direction of the semiconductor substrate 10. The upper end of the first high-concentration region 304b may be located in the region between the lower end of each trench portion and the lower surface 23, may reach between each trench portion and the upper surface 21, or may reach the upper surface 21. The doping concentration of the first high-concentration region 304b may be lower than the doping concentration of the first high-concentration region 304.

[0216] In this example, since the first high-concentration region 304 is not provided in the active portion 160, it is possible to prevent characteristic changes in the active portion 160 caused by the provision of the first high-concentration region 304. Since the first high-concentration region 304 is provided in the edge termination structure 90, the expansion of the depletion layer in the edge termination structure 90 can be suppressed, and the area of ​​the edge termination structure 90 in the XY plane can be reduced.

[0217] Figure 21 shows another example of the cc cross-section in Figure 1. The semiconductor device 100 in this example differs from the example described in Figure 20 in that a second high-concentration region 202 is provided. The other structures are the same as those of the semiconductor device 100 in any embodiment described in Figure 20. In this example as well, the depletion layer expansion in the edge termination structure 90 can be suppressed while preventing characteristic fluctuations of the active portion 160. The first high-concentration region 304 may reach the upper surface 21. In this example as well, the first high-concentration region 304b may be present, similar to the example in Figure 20.

[0218] Figure 22 shows another example of the cc cross-section in Figure 1. In this example, the semiconductor device 100 differs from the example described in Figure 20 or Figure 21 in that the upper end position of the first high-concentration region 304 in the Z-axis direction and the position of the hydrogen peak portion 302 in the Z-axis direction. The other structures are the same as those described in either Figure 20 or Figure 21. In the example shown in Figure 22, a second high-concentration region 202 is provided, similar to the example in Figure 21. Also, the upper end position of the first high-concentration region 304 in the Z-axis direction and the position of the hydrogen peak portion 302 in the Z-axis direction are the same as those described in Figure 8. The first high-concentration region 304 may reach the upper surface 21. In this example as well, a first high-concentration region 304b may be present, similar to the example in Figure 20. In this example as well, the depletion layer expansion in the edge termination structure portion 90 can be suppressed while preventing characteristic fluctuations of the active portion 160.

[0219] Figure 23 shows another example of the cc cross-section in Figure 1. The semiconductor device 100 in this example differs from the example shown in Figure 22 in the structure of the second high-concentration region 202. The other structures are the same as those shown in Figure 22. The second high-concentration region 202 in this example has the same structure as the example shown in Figure 9. The first high-concentration region 304 may reach the upper surface 21. In this example as well, the first high-concentration region 304b may be present, similar to the example in Figure 20. In this example as well, the depletion layer expansion in the edge termination structure 90 can be suppressed while preventing characteristic fluctuations in the active portion 160.

[0220] Figure 24A shows another example of the cc cross-section in Figure 1. The semiconductor device 100 in this example differs from the semiconductor device 100 described in Figures 20 to 23 in that the first high-concentration region 304 has multiple regions with different lengths in the Z-axis direction. Also, the position of the hydrogen peak portion 302 in the Z-axis direction differs in each region of the first high-concentration region 304. The other structures are the same as any of the examples described in Figures 20 to 23.

[0221] The first high-concentration region 304 has an inner portion and an outer portion located outside the inner portion. The outer portion refers to the side furthest from the active portion 160 in the XY plane. The length of the outer portion in the Z-axis direction is greater than that of the inner portion. In the example of Figure 24A, the first high-concentration region 304 includes the first high-concentration region 304-1, the first high-concentration region 304-2, and the first high-concentration region 304-3. The first high-concentration region 304-2 is located outside the first high-concentration region 304-1 and is longer in the Z-axis direction than the first high-concentration region 304-1. The first high-concentration region 304-3 is located outside the first high-concentration region 304-2 and is longer in the Z-axis direction than the first high-concentration region 304-2. In other words, if the first high-concentration region 304-1 is the inner portion, then the first high-concentration regions 304-2 and 304-3 are the outer portions. Furthermore, if the first high-concentration region 304-2 is considered the inner part, then the first high-concentration region 304-3 is the outer part. In this example, the length in the Z-axis direction of each region of the first high-concentration region 304 changes in a step-like manner.

[0222] The upper end of each first high-concentration region 304 may be located within the drift region 19. In other examples, the upper end of the first high-concentration region 304-3 may be located in a position that overlaps with the guard ring 92 or the well region 11.

[0223] The hydrogen peak portion 302-2 included in the first high-concentration region 304-2 is located above the hydrogen peak portion 302-1 included in the first high-concentration region 304-1 in the Z-axis direction. The hydrogen peak portion 302-3 included in the first high-concentration region 304-3 is located above the hydrogen peak portion 302-2 included in the first high-concentration region 304-2 in the Z-axis direction. The first high-concentration region 304-3 may reach the upper surface 21. In this example as well, there may be a first high-concentration region 304b, similar to the example in Figure 20.

[0224] In the semiconductor device 100 of this example, the first high-concentration region 304 near the active portion 160 is short in the Z-axis direction, so the influence of the first high-concentration region 304 on the characteristics of the active portion 160 can be suppressed. Also, since the first high-concentration region 304 away from the active portion 160 is long in the Z-axis direction, the expansion of the depletion layer in the edge termination structure 90 can be suppressed.

[0225] Figure 24B shows another example of the cc cross section in Figure 1. Similar to the example in Figure 24A, the semiconductor device 100 in this example also has multiple regions with different lengths in the Z-axis direction within the first high-density region 304. Other structures are identical to those described in any of the examples from Figures 20 to 23.

[0226] In this example, the height of the step in the first high-concentration region 304 below the well region 11 (Z8 in this example) is greater than the height of the step in the first high-concentration region 304 in the edge termination structure 90 (0 μm in this example). The upper end position of the first high-concentration region 304 in the edge termination structure 90 may be constant. If there are multiple steps in the first high-concentration region 304 in any region, the smallest step in the first high-concentration region 304 below the well region 11 may be greater than the largest step in the first high-concentration region 304 in the edge termination structure 90.

[0227] Furthermore, if the upper end position of the first high-concentration region 304 changes continuously rather than in a step-like manner, the inclination of the upper end position of the first high-concentration region 304 below the well region 11 is greater than the inclination of the upper end position of the first high-concentration region 304 in the edge termination structure 90. If the inclination of the upper end position of the first high-concentration region 304 changes in any region, the minimum value of the inclination of the upper end position of the first high-concentration region 304 below the well region 11 may be greater than the maximum value of the inclination of the upper end position of the first high-concentration region 304 in the edge termination structure 90. Note that the inclination of the upper end position is, for example, the amount of change in the position of the upper end of the first high-concentration region 304 in the Z-axis direction with respect to a unit length in the X-axis direction. According to this example, the length in the Z-axis direction of the first high-concentration region 304 below the well region 11 and in the active portion 160 can be reduced, and the length in the Z-axis direction of the first high-concentration region 304 in the edge termination structure 90 can be increased. Therefore, avalanche yielding on the upper surface side of the semiconductor substrate 10 can be suppressed in the well region 11 and the active region 160. The first high-concentration region 304-2 may extend to the upper surface 21. In this example as well, the first high-concentration region 304b may be present, similar to the example in Figure 20.

[0228] Figure 25A shows another example of the cc cross-section in Figure 1. The semiconductor device 100 in this example differs from the semiconductor device 100 described in Figures 20 to 23 in that the first high-concentration region 304 has multiple regions with different lengths in the Z-axis direction. Also, the position of the hydrogen peak portion 302 in the Z-axis direction differs in each region of the first high-concentration region 304. The other structures are the same as any of the examples described in Figures 20 to 23.

[0229] The first high-concentration region 304 in this example differs from the first high-concentration region 304 in Figure 24A in that its length in the Z-axis direction gradually increases as it moves away from the active portion 160. Other structures may be the same as in the example in Figure 24A. In this example, the hydrogen peak portion 302 is located higher as it moves away from the active portion 160. In this example as well, the entire upper end of the first high-concentration region 304 may be located within the drift region 19. In other examples, a part of the upper end of the first high-concentration region 304 may be located in a position overlapping with the guard ring 92 or the well region 11. In this example as well, a first high-concentration region 304b may be present, similar to the example in Figure 20. In this example as well, the influence of the first high-concentration region 304 on the characteristics of the active portion 160 can be suppressed. Furthermore, the expansion of the depletion layer in the edge termination structure portion 90 can be suppressed.

[0230] Figure 25B shows another example of the cc cross-section in Figure 1. The semiconductor device 100 in this example differs from the example in Figure 25A in that the first high-density region 304 extends from the outer peripheral edge of the semiconductor device 100 to the inner peripheral edge by a predetermined length in a plan view, and reaches the upper surface 21. The other structures are the same as those in the example in Figure 25A.

[0231] Figure 26 shows an example of the method for forming the first high-concentration region 304 described in Figure 24A. In this example, a shielding member 350 is placed below the lower surface 23 of the semiconductor substrate 10, and hydrogen ions are irradiated from the lower surface 23 side. The shielding member 350 covers the entire active portion 160 and at least a part of the edge termination structure 90. The shielding member 350 covering the active portion 160 has a thickness sufficient to completely shield hydrogen ions and prevent them from reaching the semiconductor substrate 10.

[0232] The shielding member 350 covering the region where the first high-concentration region 304 should be formed has a thickness corresponding to the length of each first high-concentration region 304 in the Z-axis direction. In other words, the longer the region in which the first high-concentration region 304 is formed, the thinner the shielding member 350 is. By making the shielding member 350 thinner, hydrogen ions can reach deeper into the semiconductor substrate 10, making the first high-concentration region 304 longer.

[0233] In this example, the shielding member 350 becomes thinner in a stepped manner as it moves away from the active part 160. Below the first high-concentration region 304-3, the shielding member 350 may or may not be provided. In Figure 26, a collector electrode 24 is provided, but hydrogen ions may be irradiated onto the lower surface 23 before the collector electrode 24 is formed. Hydrogen ion implantation of the first high-concentration region 304b may be performed before or after the first high-concentration region 304.

[0234] Figure 27 shows an example of the method for forming the first high-concentration region 304 described in Figure 25A or Figure 25B. In this example, the shape of the shielding member 350 is different from that of the example in Figure 26. Other conditions are the same as those in the example in Figure 26.

[0235] In this example, the shielding member 350 becomes thinner linearly or curvedly as it moves away from the active part 160. Below the first high-concentration region 304-3, the shielding member 350 may or may not be provided. Hydrogen ion implantation in the first high-concentration region 304b may be performed before or after the implantation in the first high-concentration region 304.

[0236] In the configurations shown in Figures 20 to 27, the resistivity of the first high-concentration region 304 is lower than the resistivity of the drift region 19 in the active section 160 (transistor section 70 or diode section 80). The resistivity of the first high-concentration region 304 may be 1 / 1.5 or less, or 1 / 10 or more, of the resistivity of the drift region 19 of the active section 160. The resistivity of the first high-concentration region 304 may also be 1 / 2 or less of the resistivity of the drift region 19 of the active section 160. The resistivity of each region may be the median value in the Z-axis direction of each region, or the average value may be used.

[0237] In the configurations shown in Figures 20 to 27, the resistivity of the drift region 19 of the active portion 160 may have a value corresponding to the rated voltage of the semiconductor device 100. For example, when the rated voltage is 600V, the resistivity may be 20 to 80 Ωcm; when the rated voltage is 1200V, the resistivity may be 40 to 120 Ωcm; when the rated voltage is 1700V, the resistivity may be 60 to 200 Ωcm; and when the rated voltage is 3300V, the resistivity may be 150 to 450 Ωcm.

[0238] In the configurations shown in Figures 1 to 27, the semiconductor substrate 10 may have a second-type bulk acceptor distributed throughout. The bulk acceptor, like the bulk donor, is an acceptor uniformly introduced into the ingot during ingot manufacturing. The bulk acceptor may be boron. The bulk acceptor concentration may be lower than the bulk donor concentration. In other words, the ingot is N-type. As an example, the bulk acceptor concentration is 5 × 10⁻⁶. 11 ( / cm 3 )~8×10 14 ( / cm 3 ) and the bulk donor concentration is 5 × 10 12 ( / cm 3 )~1×10 15 ( / cm 3 The bulk acceptor concentration may be 1% or more, 10% or more, or 50% or more of the bulk donor concentration. The bulk acceptor concentration may be 99% or less, 95% or less, or 90% or less of the bulk donor concentration.

[0239] The presence of bulk acceptors throughout the semiconductor substrate 10 reduces the net doping concentration in the semiconductor substrate 10 before hydrogen ion implantation. This reduces the absolute value of the variation in the net doping concentration of the semiconductor substrate 10. As a result, it becomes easier to adjust the resistivity by hydrogen ion implantation.

[0240] Figure 28 shows another example of the cc cross-section in Figure 1. In the semiconductor device 100 of this example, the active portion 160 has an N-type fourth high-concentration region 404. The structure other than the fourth high-concentration region 404 is the same as that of the semiconductor device 100 of any embodiment described in Figures 1 to 27. The first high-concentration region 304 may extend to the upper surface 21.

[0241] The fourth high-concentration region 404 is provided from the upper surface 21 to the lower surface 23 of the semiconductor substrate 10, and its donor concentration is higher than the bulk donor doping concentration. The method for forming the fourth high-concentration region 404 is the same as that for the first high-concentration region 304. That is, hydrogen ions are injected from the lower surface 23 of the semiconductor substrate 10 to a predetermined depth on the upper surface 21 side of the semiconductor substrate 10. By annealing the semiconductor substrate 10 after the hydrogen ions have been injected, hydrogen donors are formed in the region through which the hydrogen ions have passed. This forms the fourth high-concentration region 404, in which the donor concentration is higher than the bulk donor concentration.

[0242] Note that the donor concentration in the fourth high-concentration region 404 is different from the donor concentration in the first high-concentration region 304. For example, the donor concentrations in these regions can be made different by varying the dose of hydrogen ions to the active portion 160 and the dose of hydrogen ions to the edge-terminal structure portion 90. Hydrogen ion implantation into the active portion 160 and the edge-terminal structure portion 90 may be performed in separate processes. Alternatively, after implanting hydrogen ions into the active portion 160 and the edge-terminal structure portion 90 with the same dose in the same process, additional hydrogen ions may be implanted into one of the active portion 160 or the edge-terminal structure portion 90.

[0243] In the example of FIG. 28, the donor concentration in the fourth high-concentration region 404 is lower than the donor concentration in the first high-concentration region 304. By making the donor concentration in the fourth high-concentration region 404 lower than the donor concentration in the first high-concentration region 304, the elongation of the electric field in the vertical direction (Z-axis direction) can be suppressed. Also, by making the donor concentration in the fourth high-concentration region 404 higher than the bulk donor concentration, for example, when the semiconductor device 100 is switched, the vibration of the voltage or current waveform can be suppressed. Further, by making the donor concentration in the first high-concentration region 304 higher than the donor concentration in the fourth high-concentration region 404, the elongation of the electric field in the lateral direction can be suppressed, and the width of the edge termination structure 90 in the lateral direction (X-axis direction and Y-axis direction) can be reduced. The donor concentration in the fourth high-concentration region 404 may be 0.9 times or less, 0.5 times or less, or even 0.1 times or less of the first high-concentration region 304.

[0244] In the depth direction, the upper end position Z4 of the first high-concentration region 304 and the upper end position Z5 of the fourth high-concentration region 404 may be at the same position or may be different. The upper end position Z5 of the fourth high-concentration region 404 may be arranged below (on the side of the lower surface 23) the upper end position Z4 of the first high-concentration region 304 or may be arranged above (on the side of the upper surface 21). The boundary in the X-axis direction between the fourth high-concentration region 404 and the first high-concentration region 304 may be arranged below the well region 11. In other examples, the boundary may be arranged in the active portion 160 or may be arranged in the edge termination structure 90.

[0245] FIG. 29 is a diagram showing another example of the c-c cross-section in FIG. 1. In the semiconductor device 100 of this example, the donor concentration in the fourth high-concentration region 404 is higher than the donor concentration in the first high-concentration region 304. Other structures are the same as those of the semiconductor device 100 described in FIG. 28. The first high-concentration region 304 may reach the upper surface 21.

[0246] According to this example, in the edge termination structure portion 90, since the donor concentration of the first high-concentration region 304 is low, the occurrence of avalanche breakdown in the vicinity of the guard ring can be suppressed. The donor concentration of the fourth high-concentration region 404 may be 1.1 times or more, 2 times or more, or even 10 times or more that of the first high-concentration region 304.

[0247] FIG. 30 is a diagram showing another example of the c-c cross section in FIG. 1. The semiconductor device 100 of this example has a first high-concentration region 304-4 and a first high-concentration region 304-5 with different donor concentrations. Other structures are the same as those of the semiconductor device 100 described in FIG. 28 or FIG. 29. The first high-concentration region 304-5 may reach the upper surface 21.

[0248] The first high-concentration region 304-4 is the same as the first high-concentration region 304 described in FIG. 28 or FIG. 29. The first high-concentration region 304-5 is disposed between the first high-concentration region 304-4 and the upper surface 21. The first high-concentration region 304-5 may be in contact with the first high-concentration region 304-4. The upper end position of the first high-concentration region 304-5 may be the same as any of the first high-concentration regions 304 described in FIGS. 1 to 27. The upper end position of the first high-concentration region 304-5 may be disposed above the upper end position Z5 of the fourth high-concentration region 404.

[0249] The donor concentration of the first high-concentration region 304-5 is lower than that of the first high-concentration region 304-4. The donor concentration of the first high-concentration region 304-5 may be higher than, the same as, or lower than the donor concentration of the fourth high-concentration region 404. For example, for the active portion 160 and the edge termination structure portion 90, a first step of implanting hydrogen ions at the same depth positions (Z5, Z6) with the same dose amount from the lower surface 23, and a second step of selectively implanting hydrogen ions from the lower surface 23 to a position closer to the upper surface 21 than the depth position Z6 for the edge termination structure portion 90 are performed, whereby the structure of this example can be formed. In the first step, at least one of the implanting depth and the dose amount of hydrogen ions for the active portion 160 and the edge termination structure portion 90 may be made different.

[0250] Figure 31 shows another example of the cc cross section in Figure 1. In this example, the semiconductor device 100 also has a first high-concentration region 304 in the active region 160. Furthermore, in the active region 160, a P-type low-concentration region 17 with a lower doping concentration than the base region 14 is provided between the base region 14 and the first high-concentration region 304. The other structures are the same as those of the semiconductor device 100 in any of the embodiments described in Figures 1 to 30. In this example, the low-concentration region 17 is located between the storage region 16 and the first high-concentration region 304 in a part of the active region 160 such as the transistor region 70, and functions as part of the drift region 19.

[0251] The semiconductor substrate 10 in this example is a P-type semiconductor substrate into which hydrogen ions are implanted to form a first high-concentration region 304, etc., and more than half of the region is inverted to an N-type. The doping concentration in the low-concentration region 17 may be the same as the bulk acceptor concentration. The hydrogen donor concentration in the first high-concentration region 304 is higher than the bulk acceptor concentration. In a part of the active region 160, hydrogen ions or phosphorus, etc., may be implanted from the upper surface 21 of the semiconductor substrate 10 to form a fifth high-concentration region 502 that is continuous with the first high-concentration region 304. The fifth high-concentration region 502 may be formed in various ways depending on the design.

[0252] Furthermore, in areas other than the active area 160, a second high-concentration area 202 may be provided between the first high-concentration area 304 and the upper surface 21 of the semiconductor substrate 10. In the edge termination structure 90, the first high-concentration area 304 and the second high-concentration area 202 may be provided continuously. The second high-concentration area 202 may be provided continuously from the upper end of the first high-concentration area 304 to the upper surface 21 of the semiconductor substrate 10. The second high-concentration area 202 can be formed by implanting hydrogen ions or phosphorus, etc., from the upper surface 21 of the semiconductor substrate 10, as explained in Figure 4, etc. When the second high-concentration area 202 is formed by implanting hydrogen ions, the hydrogen donor concentration in the second high-concentration area 202 is higher than the bulk acceptor concentration. The second high-concentration area 202 may also be provided below the well area 11. Note that the second high-concentration area 202 and the fifth high-concentration area 502 may be formed simultaneously or separately. The second high-concentration region 202 and the fifth high-concentration region 502 may overlap with the first high-concentration region 304. The second high-concentration region 202 and the first high-concentration region 304 do not have to be substantially uniform, and may be formed with locally different concentrations and boundary positions.

[0253] A fifth high-concentration region 502 may be provided on the outer periphery (+X axis direction) of the transistor section 70 between it and the well region 11. In other words, the low-concentration region 17 of the transistor section 70 may be separated from the well region 11 by the fifth high-concentration region 502. Since the low-concentration region 17 is p-type, by separating it from the well region 11 and not making contact, it becomes electrically floating.

[0254] Furthermore, a p-type bottom high-concentration region 170 with a higher concentration than the low-concentration region 17 may be provided so as to be in contact with the bottom of one or more trench sections. The bottom high-concentration region 170 may be provided continuously in the X-axis direction across multiple trench sections. The bottom high-concentration region 170 may be separate from the well region 11 and may be electrically suspended. The upper surface 21 side of the bottom high-concentration region 170 may be in contact with the accumulation region 16 or may be separate from it. The lower surface 23 side of the bottom high-concentration region 170 may be in contact with the low-concentration region 17. The X-axis end of the bottom high-concentration region 170 may be located inside the fifth high-concentration region 502, may be in contact with the fifth high-concentration region 502 or may be separate from the fifth high-concentration region 502. In this example, the X-axis end of the bottom high-concentration region 170 is located inside the fifth high-concentration region 502.

[0255] Figure 32 shows another example of the cc cross-section in Figure 1. In this example, the semiconductor device 100 has a first high-density region 304 that extends above the lower end of the guard ring in the edge termination structure 90, etc. The other structures are the same as those of the semiconductor device 100 described in Figure 31. In this example, the first high-density region 304 extends to the upper surface 21 of the semiconductor substrate 10.

[0256] In this example, hydrogen ions may be implanted in the active portion 160 and the edge termination structure portion 90 in the same process via shielding members of different thicknesses, or they may be implanted in different processes. For the edge termination structure portion 90 and a portion of the active portion 160, the acceleration energy of the hydrogen ions may be set so that the hydrogen ions penetrate the semiconductor substrate 10. Furthermore, the first high-concentration region 304 does not have to be substantially uniform, and may be formed so that the concentration and boundary position differ locally. In this example, an example without a second high-concentration region 202 has been described, but a second high-concentration region 202 may be provided.

[0257] A first high-concentration region 304 may be provided on the outer periphery (+X axis direction) of the transistor section 70 between it and the well region 11. In other words, the low-concentration region 17 of the transistor section 70 may be separated from the well region 11 by the first high-concentration region 304. Since the low-concentration region 17 is p-type, by separating it from the well region 11 and not making contact, it becomes electrically floating.

[0258] Furthermore, a p-type bottom high-concentration region 170 with a higher concentration than the low-concentration region 17 may be provided so as to be in contact with the bottom of one or more trench sections. The bottom high-concentration region 170 may be provided continuously across multiple trench sections. The bottom high-concentration region 170 may be separate from the well region 11 and may be electrically suspended. The upper surface 21 side of the bottom high-concentration region 170 may be in contact with the accumulation region 16 or may be separate from it. The lower surface 23 side of the bottom high-concentration region 170 may be in contact with the low-concentration region 17. The X-axis end of the bottom high-concentration region 170 may be located inside the first high-concentration region 304, may be in contact with the first high-concentration region 304 or may be separate from the first high-concentration region 304. In this example, the X-axis end of the bottom high-concentration region 170 is located inside the first high-concentration region 304.

[0259] Figure 33 shows another example of the cc cross-section in Figure 1. The semiconductor device 100 in this example differs from the example shown in Figure 4 in that the second high-density region 202 is also located between the channel stopper 174 and the outermost guard ring 92. The other structures are the same as those of the semiconductor device 100 described in Figure 4. The second high-density region 202 may be provided from the upper surface 21 of the semiconductor substrate 10 down to below the lower end of the channel stopper 174, or it may be provided up to above the lower end of the channel stopper 174.

[0260] Figure 34 shows an example of the carrier concentration distribution along the dd line shown in Figure 4 or Figure 33. This distribution is similar to the example shown in Figure 5. In this example, D6 is the distance in the depth direction between the lower end of the second high-concentration region 202 and the upper end of the first high-concentration region 304. The carrier concentration at the lower end of the second high-concentration region 202 and the upper end of the first high-concentration region 304 is the bulk donor concentration N.00 This is the point where the concentration begins to increase. The lower end of the second high-concentration region 202 and the upper end of the first high-concentration region 304 are where the carrier concentration is equal to the bulk donor concentration N. 00 It could also be at a position that is twice the value.

[0261] The distance D6 is preferably 50 μm or less. That is, in the edge termination structure 90, the width in the Z-axis direction of the region sandwiched between the first high-concentration region 304 and the second high-concentration region 202 is preferably 50 μm or less. If the distance D6 is too large, it becomes difficult to suppress the elongation of the depletion layer in the edge termination structure 90. As a result, the depletion layer may reach the side surface of the semiconductor substrate 10, increasing the leakage current. The distance D6 may be 40 μm or less, or 30 μm or less. The distance D6 may be 15 μm or more. If the distance D6 is too small, the breakdown voltage of the edge termination structure 90 may not be sufficient. The distance D6 may be 17 μm or more.

[0262] Let D7 be the distance in the Z-axis direction between the lower end of the second high-concentration region 202 and the upper surface 21 of the semiconductor substrate 10. The distance D7 may be 2 μm or more. The distance D7 may be 3 μm or more, or 5 μm or more. The distance D7 may be less than the length of the guard ring in the depth direction.

[0263] Figure 35 shows the dose of N-type dopant ( / cm³) to the second high-concentration region 202 shown in Figure 33. 2 This figure shows the relationship between the dopant and the breakdown voltage (V) of the semiconductor device 100. In this example, the N-type dopant is phosphorus. The breakdown voltage rating of the semiconductor device 100 is Vr. The rated voltage Vr is a voltage between 1000V and 1500V. The breakdown voltage of the semiconductor device 100 is the emitter-collector voltage at which avalanche breakdown occurs. Also, in the example of Figure 35, the surface charge amount on the upper surface of the interlayer insulating film 38 is 0, -2 × 10⁻¹⁰ 12 / cm 2 , +2 × 10 12 / cm 2 The following three cases are shown. The relationships shown in Figure 35 were measured at room temperature (25°C). In this example, the distance D7 is approximately 3 μm and the distance D6 is approximately 17 μm.

[0264] In this example, regardless of the surface charge, the dose amount in the second high-concentration region 202 is 5 × 10⁻⁶. 11 / cm 2 If the following conditions are met, the withstand voltage of semiconductor device 100 will hardly decrease and will remain above the rated value. On the other hand, if the dose amount is 5 × 10 11 / cm 2 Beyond this point, the rated voltage decreases when the surface charge is negative. Therefore, the dose in the second high-concentration region 202 is 5 × 10 11 / cm 2 The following is preferable:

[0265] Figure 36 shows the dose of N-type dopant ( / cm³). 2 This figure shows another example of the relationship between the voltage (V) of the semiconductor device 100 and the breakdown voltage (V). In this example, the semiconductor device 100 has a smaller X-axis length (edge ​​length) of the edge termination structure 90 compared to the example shown in Figure 35. All other conditions are the same as in the example in Figure 35.

[0266] In this example, the dose in the second high-concentration region 202 is 1 × 10⁻⁶. 11 / cm 2 As the size decreased, the breakdown voltage decreased in the example with a negative surface charge. Therefore, the dose amount in the second high-concentration region 202 was 1 × 10⁻⁶. 11 / cm 2 It is preferable that the above conditions are met. Also, similar to the example in Figure 35, the dose amount in the second high-concentration region 202 is 5 × 10 11 / cm 2 Beyond this point, the rated voltage decreases when the surface charge is negative. Therefore, the dose in the second high-concentration region 202 is 5 × 10 11 / cm 2 The following is preferable. The dose amount in the second high-concentration region 202 may be the integral value obtained by integrating the donor concentration distribution in the second high-concentration region 202 over a distance D7 from the upper surface 21.

[0267] FIG. 37 is a flowchart showing an example of the manufacturing process of the semiconductor device 100. Each process shown in FIG. 37 may be performed on the semiconductor substrate 10 in the state of a wafer. A plurality of semiconductor substrates 10 can be cut out from the wafer. In the wafer, bulk donors such as phosphorus are distributed throughout.

[0268] First, in the upper surface side structure formation step S502, each structure provided on the upper surface 21 side of the semiconductor substrate 10 is formed. The structures on the upper surface 21 side include at least one of an emitter region 12, a base region 14, an accumulation region 16, a well region 11, a second high-concentration region 202, each trench portion, an interlayer insulating film 38, an emitter electrode 52, a gate wiring, a guard ring 92, a field plate 94, and a channel stopper 174.

[0269] Next, in the grinding step S504, the lower surface 23 side of the semiconductor substrate 10 is ground to adjust the thickness of the semiconductor substrate 10 in the Z-axis direction. In S504, the thickness of the semiconductor substrate 10 in the Z-axis direction is determined according to the withstand voltage that the semiconductor device 100 should have. In S504, the semiconductor substrate 10 may be ground by a method such as back grinding or CMP.

[0270] Next, in the measurement step S506, the thickness of the semiconductor substrate 10 is measured. In S506, the thickness of the semiconductor substrate 10 may be measured from the distance between probes by bringing the probes into contact with both the upper surface 21 and the lower surface 23 of the semiconductor substrate 10. Also, the thickness of the semiconductor substrate 10 may be measured from the spectrum of the interference light between the reflected light on the upper surface 21 side and the reflected light on the lower surface 23 side of the semiconductor substrate 10 by irradiating the semiconductor substrate 10 with infrared rays. The method for measuring the thickness of the semiconductor substrate 10 is not limited to these.

[0271] Next, in the first hydrogen implantation step S508, hydrogen ions are implanted from the lower surface 23 of the semiconductor substrate 10 to the upper surface 21 of the semiconductor substrate 10. This forms a hydrogen peak portion 302 as described in Figure 5. In S508, the hydrogen ion implantation conditions are adjusted according to the thickness of the semiconductor substrate 10 measured in S506. The hydrogen ion implantation conditions may include the hydrogen ion implantation depth. The hydrogen ion implantation depth is the distance from the lower surface 23 of the semiconductor substrate 10 to the peak of the hydrogen peak portion 302.

[0272] When hydrogen ions are implanted at a constant implantation depth, variations in the thickness of the semiconductor substrate 10 cause the distance between the hydrogen peak portion 302 and the upper surface 21 of the semiconductor substrate 10 to fluctuate. This distance corresponds to the distance between the upper end of the first high-concentration region 304 and the upper surface 21 of the semiconductor substrate 10. The area between the upper end of the first high-concentration region 304 and the upper surface 21 of the semiconductor substrate 10 is the bulk doping region 18, and this distance is the thickness of the bulk doping region 18 in the depth direction. When this distance fluctuates, it affects how the depletion layer spreads in the edge termination structure 90. Therefore, when this distance fluctuates, the characteristics of the semiconductor device 100 fluctuate.

[0273] In S508, the hydrogen ion implantation depth may be adjusted according to the thickness of the semiconductor substrate 10 so that the distance between the hydrogen peak portion 302 and the upper surface 21 of the semiconductor substrate 10, i.e., the thickness of the bulk doping region 18, is a predetermined value. The hydrogen ion implantation depth can be adjusted, for example, by the acceleration energy of the hydrogen ions.

[0274] Let D (μm) be the target thickness of the semiconductor substrate 10, and let Z (μm) be the distance between the upper edge of the first high-concentration region 304 and the upper surface 21 of the semiconductor substrate 10. Also, the distance X (i.e., the range Rp of hydrogen ions) from the upper edge of the first high-concentration region 304 to the lower surface 23 of the semiconductor substrate 10 is given by X = DZ. When the thickness of the semiconductor substrate 10 matches the target value D, the acceleration energy E (eV) of hydrogen ions to be set in the first hydrogen injection step S508 is given by equation (1), where y = log(E) and x = log(X). y = -0.0047x 4 +0.0528x 3 -0.2211x 2 +0.9923x+5.0474...Formula (1)

[0275] Let d=DA be the difference between the measured thickness A of the semiconductor substrate 10 measured in S506 and the target value D. If the difference d is greater than 0, it means that the semiconductor substrate 10 has become thinner due to excessive grinding in S504. If the difference d is less than 0, it means that the semiconductor substrate 10 has become thicker due to insufficient grinding. Considering the difference d, the distance X' from the upper end of the first high-concentration region 304 to the lower surface 23 of the semiconductor substrate 10 is X'=Xd=DZd.

[0276] When considering the difference d, the hydrogen ion acceleration energy E (eV) to be set in the first hydrogen injection stage S508 is given by equation (2), where y1 = log(E') and x1 = log(X'). y1 = -0.0047x1 4 +0.0528x1 3 -0.2211x1 2 +0.9923x1+5.0474...Equation (2)

[0277] Furthermore, in S508, the hydrogen ion implantation depth may be adjusted by characteristics such as the thickness of the shielding member placed on the lower surface 23 of the semiconductor substrate 10 in S507. Alternatively, both the acceleration energy E of the hydrogen ions and the characteristics of the shielding member may be adjusted. For example, the implantation depth may be roughly adjusted by the thickness of the shielding member, and the implantation depth may be adjusted with higher resolution by the acceleration energy E. A lower surface shielding member formation step S507 may be included between S506 and S508. The lower surface shielding member formation step S507 will be described later.

[0278] Next, in the annealing step S510, the entire semiconductor substrate 10 is annealed. This allows the first high-concentration region 304 to be formed in the region through which hydrogen ions have passed. Since the hydrogen ion implantation depth was adjusted in S508, the upper end position of the first high-concentration region 304 in the Z-axis direction can be adjusted.

[0279] Next, in the lower surface structure formation step S512, the structure on the lower surface 23 of the semiconductor substrate 10 is formed. The structure on the lower surface 23 may include, for example, at least one of a buffer region 20, a collector region 22, a cathode region 82, and a collector electrode 24. It is preferable that the lower surface structure formation step S512 does not include a process of annealing the entire semiconductor substrate 10 at a higher temperature than the annealing step S510. When forming the collector region 22 and the cathode region 82, local annealing may be performed using a laser or the like. This reduces the thermal history after the formation of the first high-concentration region 304.

[0280] Figure 38A shows an example of the first hydrogen implantation step S508. In this example, hydrogen ions are implanted from the lower surface 23 of the semiconductor substrate 10 with a shielding member 351 formed on the lower surface 23 of the semiconductor substrate 10. The shielding member 351 in this example is, for example, a photosensitive resist material coated on the lower surface 23 of the semiconductor substrate 10.

[0281] In S507, the thickness T1 of the shielding member 351 to be placed on the lower surface 23 is calculated based on the thickness of the semiconductor substrate 10 measured in S506, and the shielding member 351 is formed to adjust the hydrogen ion implantation depth. If the measured thickness of the semiconductor substrate 10 is greater than a predetermined target value, the thickness T1 of the shielding member 351 is reduced to increase the hydrogen ion range Rp, and if the measured value is less than the target value, the thickness T1 of the shielding member 351 is increased to decrease the hydrogen ion range Rp. The amount of change in the hydrogen ion range Rp when the thickness T1 of the shielding member 351 is changed may be measured in advance.

[0282] Furthermore, in S508, the range Rp of hydrogen ions may be adjusted by the degree of hardening of the shielding member 351. The degree of hardening of the shielding member 351 can be adjusted by exposure time, etc. The amount of change in the range Rp of hydrogen ions when the hardening of the shielding member 351 is adjusted may be measured in advance.

[0283] Figure 38B shows an example of hydrogen ion implantation through a shielding member 351. The shielding member 351 is formed on the lower surface 23. If there is variation in the thickness of the semiconductor substrate 10 after grinding, the distance Z between the upper end of the first high-concentration region 304 and the upper surface 21 of the semiconductor substrate 10 will also vary. Therefore, the shielding member 351 is formed on the lower surface 23, and then hydrogen ions are implanted into the lower surface 23. When the shielding member is a resist film, the coated surface after coating the resist film can be made flat regardless of the unevenness of the lower surface 23 of the underlying semiconductor substrate 10. This reduces the influence of in-plane variation in the thickness of the semiconductor substrate 10 on the distance Z.

[0284] The measured thickness of the semiconductor substrate 10 in the measurement step S506 after grinding has a maximum value Amax. and a minimum value Amin. within the plane of the substrate. At this time, the average value Ac of the thickness after grinding is defined as Ac = (Amax. + Amin.) / 2. In Figure 38B, the average plane 25 corresponding to this average value Ac is shown by a dashed line. If the measured value A in S506 is taken as Ac, and the difference d from the target value D is d = D - Ac, then Ac = Dd. Hydrogen ion implantation in step S508 is performed through a shielding member 351 with a thickness T1 (μm). Therefore, the distance X' from the upper end of the first high-concentration region 304 to the lower surface 23 of the semiconductor substrate 10, taking into account the difference d, is X' = Ac + T1 - Z, taking into account the thickness T1 of the shielding member 351. Here, the thickness T1 of the shielding member 351 is defined as the thickness from the average plane 25 corresponding to the average value Ac of the measured values ​​to the plane on the opposite side from the average plane 25. Since Ac is Dd, X' = D - d + T1 - Z. By substituting X' into equation (2), the hydrogen ion acceleration energy E (eV) to be set in the first hydrogen injection stage S508 can be found.

[0285] Figure 39 shows another example of the first hydrogen injection step S508. In this example, hydrogen ions are injected from the lower surface 23 of the semiconductor substrate 10 with a shielding member 352 placed on the lower surface 23 side of the semiconductor substrate 10. The shielding member 352 in this example is a solid member made of a metal material such as aluminum, or another material. The shielding member 352 may be placed away from the lower surface 23.

[0286] In this example as well, the thickness T2 of the shielding member 352 placed on the lower surface 23 is adjusted based on the measured thickness of the semiconductor substrate 10. The method for adjusting the thickness T2 may be the same as the method for adjusting the thickness T1 shown in Figure 38A.

[0287] When the acceleration energy E of the hydrogen ions is fixed, the relationship between the hydrogen ion range Rp in the first hydrogen injection stage S508 is given by equation (3), where y² = log(Rp) and x² = log(E). y² = -0.0082x² 4 +0.1664x2 3 -1.0210x2 2 +2.8528x2-4.4625...Formula (3) From equation (3), the range of hydrogen ions that should be reduced by the thickness T2 of the shielding member 352 is T2 = Rp - X' = 10 y2 -D+Z+d(μm). A shielding member 351 in contact with the lower surface 23 may be formed between the lower surface 23 and the shielding member 352 in S507. This reduces the effect of thickness variations in the semiconductor substrate 10. In this case, let X'=D-d+T1-Z, then T2=Rp-X'=10 y2 Let -(D-d+T1-Z)(μm).

[0288] The acceleration energy for hydrogen ions may be set to match the case with the largest thickness among the expected variations in the thickness of the semiconductor substrate 10. The thickness of the shielding member may be reduced as the thickness of the semiconductor substrate 10 decreases. This allows the hydrogen ion implantation depth to be adjusted without changing the acceleration energy. Also, as the thickness T2 of the shielding member 352 decreases, it becomes difficult to adjust the thickness T2. For this reason, the acceleration energy for hydrogen ions may be set so that the thickness T2 of the shielding member 352 is greater than or equal to a predetermined value, even if the thickness of the semiconductor substrate 10 varies. This predetermined value is, for example, 100 μm or more.

[0289] In the first hydrogen injection step S508, the amount of hydrogen ions may be adjusted based on the thickness of the semiconductor substrate 10. If the thickness of the semiconductor substrate 10 varies, the breakdown voltage of the semiconductor device 100 may fluctuate. In contrast, the breakdown voltage of the semiconductor device 100 can be adjusted by adjusting the amount of hydrogen ions. For example, if the thickness of the semiconductor substrate 10 is smaller than a predetermined target value, the breakdown voltage may decrease. In this case, the amount of hydrogen ions may be reduced in S508. By lowering the concentration of hydrogen donors formed in the hydrogen ion passage region, the decrease in breakdown voltage can be suppressed. If the thickness of the semiconductor substrate 10 is larger than a predetermined target value, the amount of hydrogen ions may be increased. The preferred relationship between the thickness of the semiconductor substrate 10 and the amount of hydrogen ions may be measured in advance.

[0290] Furthermore, in the annealing step S510, the annealing conditions for the semiconductor substrate 10 may be adjusted based on the thickness of the semiconductor substrate 10. The annealing conditions include at least one of the annealing time and the annealing temperature. If the thickness of the semiconductor substrate 10 is greater than a predetermined target value, the annealing time or the annealing temperature may be adjusted so that the concentration of hydrogen donors formed in the hydrogen ion passage region is higher than the target value. If the thickness of the semiconductor substrate 10 is less than a predetermined target value, the annealing time or the annealing temperature may be adjusted so that the concentration of hydrogen donors formed in the hydrogen ion passage region is lower than the target value.

[0291] Figure 40 is a flowchart showing another example of the manufacturing process for semiconductor device 100. In this example, the second hydrogen injection step S509 is performed before the annealing step S510. The second hydrogen injection step S509 is performed after the measurement step S506. The steps other than the second hydrogen injection step S509 are the same as in the example in Figure 37.

[0292] In the second hydrogen injection step S509, hydrogen ions are injected from the lower surface 23 of the semiconductor substrate 10 into the region on the lower surface 23 side of the semiconductor substrate 10. In S509, hydrogen ions may be injected at any of the peak positions of the carrier concentration in the buffer region 20 shown in Figure 5. In S509, hydrogen ions may be injected at each peak position of the buffer region 20.

[0293] Hydrogen ions injected into the lower surface 23 of the semiconductor substrate 10 diffuse to the upper surface 21 of the semiconductor substrate 10 during the annealing step S510. This facilitates the formation of hydrogen donors in the first high-concentration region 304. The donor concentration in the first high-concentration region 304 can also be adjusted by the dose of hydrogen ions injected into the lower surface 23 of the semiconductor substrate 10. Furthermore, the donor concentration in the first high-concentration region 304 can also be adjusted by the depth of the hydrogen ions injected into the lower surface 23 of the semiconductor substrate 10.

[0294] In step S509 of this example, the hydrogen ion implantation conditions for the lower surface 23 are adjusted according to the measured thickness of the semiconductor substrate 10. The implantation conditions include at least one of the hydrogen ion dose and the implantation depth. This allows the breakdown voltage of the semiconductor device 100 to be adjusted by adjusting the donor concentration in the first high-concentration region 304. For example, if the thickness of the semiconductor substrate 10 is smaller than a predetermined target value, the breakdown voltage may be reduced. In this case, the hydrogen ion dose may be adjusted in S509 to suppress the decrease in breakdown voltage. The hydrogen ion implantation depth may also be adjusted. Even if the thickness of the semiconductor substrate 10 is larger than a predetermined target value, the hydrogen ion dose may be adjusted, and the hydrogen ion implantation depth may also be adjusted. The preferred relationship between the thickness of the semiconductor substrate 10 and the hydrogen ion dose or implantation depth may be measured in advance.

[0295] In step S509, the hydrogen ion implantation conditions may be adjusted for the peak with the highest hydrogen concentration among the multiple hydrogen concentration peaks in the buffer region 20. Alternatively, the hydrogen ion implantation conditions may be adjusted for the peak closest to the bottom surface 23 of the semiconductor substrate 10 among the multiple hydrogen concentration peaks in the buffer region 20.

[0296] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above embodiments. It will be clear from the claims that such modified or improved forms may also be included in the technical scope of the present invention.

[0297] For example, in order to adjust the electric field distribution between the active portion 160 and the edge termination structure portion 90, the structure may include a first high-concentration region 304, a second high-concentration region 202, and a fourth high-concentration region 404, as shown in Figure 41.

[0298] Figure 41 shows another example of the cc cross-section in Figure 1. The semiconductor device 100 in this example differs from the other configurations described herein in the arrangement of each high-concentration region. The other structures are the same as those of any of the examples described herein.

[0299] The semiconductor device 100 in this example has a first high-concentration region 304-6, a first high-concentration region 304-7, a second high-concentration region 202, and a fourth high-concentration region 404. The shape of each high-concentration region can be appropriately combined from the high-concentration regions described herein.

[0300] At least a portion of the first high-concentration region 304-6 and the first high-concentration region 304-7 is provided in the edge termination structure 90. In the example shown in Figure 41, the first high-concentration region 304-6 is the same as the first high-concentration region 304 described in Figure 25A. The first high-concentration region 304-7 has a lower doping concentration than the first high-concentration region 304-6 and is located above the first high-concentration region 304-6. The entirety of the first high-concentration region 304-6 may be located below the first high-concentration region 304-7.

[0301] Furthermore, the second high-concentration region 202 is the same as the second high-concentration region 202 described in Figure 21. However, the shapes of the first high-concentration region 304-6, the first high-concentration region 304-7, and the second high-concentration region 202 may be the shapes of other high-concentration regions described herein. As shown in Figure 41, the second high-concentration region 202 may also be provided between the channel stopper 174 and the guard ring 92 closest to the channel stopper 174. The second high-concentration region 202 may be formed by injecting phosphorus or by forming a hydrogen donor.

[0302] The fourth high-concentration region 404 is formed in the active portion 160. The fourth high-concentration region 404 may have a lower concentration than the first high-concentration region 304-6. The fourth high-concentration region 404 may have a lower concentration than the first high-concentration region 304-7. The upper end of the first high-concentration region 304-7 may be positioned on the upper surface 21 side of the upper end of the fourth high-concentration region 404. In the example of Figure 41, the upper end of the fourth high-concentration region 404 is positioned below each trench portion or well region 11. In the active portion 160, an N-type bulk doping region 18 may be provided above the fourth high-concentration region 404, and a P-type low-concentration region 17 may be provided.

[0303] The upper end of the first high-concentration region 304-7 is located above the lower end of the well region 11 or the lower end of the guard ring 92. In other examples, the upper end of the fourth high-concentration region 404 in the edge terminal structure 90 may be located below the well region 11 or the guard ring 92. The upper end of the first high-concentration region 304-7 is located below the lower end of the second high-concentration region 202. In other words, the first high-concentration region 304-7 and the second high-concentration region 202 are located apart. In this example, a bulk doping region 18 is provided between the first high-concentration region 304-7 and the second high-concentration region 202 in the edge terminal structure 90.

[0304] In the embodiments described above, examples were shown in which the first high-concentration region 304 is formed by hydrogen ion implantation, but the invention is not limited to this. For example, the first high-concentration region 304 can also be formed by generating a disorder in the substrate by helium ion implantation and diffusing hydrogen into the substrate to generate VOH defects. In this case, the hydrogen peak portion 302 contains helium. This also produces a similar effect of suppressing the lateral spread of the electric field as shown in Figure 6. Furthermore, it is also possible to form the region by diffusing and activating other impurity elements that form donor bands from the lower surface 23.

[0305] It should be noted that the execution order of operations, procedures, steps, and stages in the apparatus, systems, programs, and methods shown in the claims, specifications, and drawings is not explicitly stated as "before," "prior to," etc., and that these can be implemented in any order unless the output of a previous process is used in a later process. Even if the operation flow in the claims, specifications, and drawings is described using phrases such as "first," "next," etc. for convenience, it does not mean that it is essential to perform the operations in that order. [Explanation of Symbols]

[0306] 10...Semiconductor substrate, 11...Well region, 12...Emitter region, 14...Base region, 15...Contact region, 16...Storage region, 17...Low concentration region, 18...Bulk doping region, 19...Drift region, 20...Buffer region, 21...Top surface, 22...Collector region, 23...Bottom surface, 24...Collector electrode, 25...Average plane, 29...Straight section, 30...Dummy trench section, 31...Tip section, 32...Dummy insulation Edge film, 34...Dummy conductive part, 38...Interlayer insulating film, 39...Straight part, 40...Gate trench part, 41...Tip part, 42...Gate insulating film, 44...Gate conductive part, 52...Emitter electrode, 54...Contact hole, 60, 61...Mesa part, 70...Transistor part, 80...Diode part, 81...Extended region, 82...Cathode region, 90...Edge termination structure part, 91...Region, 92...Guard ring, 93...Side side, 9 4...Field plate, 95...Gap, 98...Opening, 100...Semiconductor device, 102...Edge, 112...Gate pad, 130...Outer periphery gate wiring, 131...Active side gate wiring, 140...Protective film, 160...Active part, 174...Channel stopper, 202...Second high-concentration region, 203...Third high-concentration region, 204...Region, 206...Upper part, 208...Lower part, 209...Region, 260...Lower region, 261... Lower region, 262... isopotential surface, 302... hydrogen peak region, 304... first high-concentration region, 306, 308, 310... isopotential surface, 312, 314... peak, 313, 317... flat region, 318... first peak, 320, 322, 324, 326... slope, 323, 327... flat region, 330, 332, 334, 336, 338... point, 350, 351, 352... shielding member, 404... fourth high-concentration region, 502... fifth high-concentration region

Claims

1. A semiconductor substrate having a bulk doping region of the first conductivity type in which a bulk donor of the first conductivity type is distributed throughout and the doping concentration is the same as that of the bulk donor, The semiconductor substrate has an active portion provided on it, An edge termination structure is provided on the semiconductor substrate, between the active portion and the edge of the semiconductor substrate on the upper surface of the semiconductor substrate. Equipped with, The edge termination structure has a first high-concentration region of a first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, where the donor concentration is higher than the doping concentration of the bulk donor. The upper surface of the first high-concentration region is located on the upper surface side of the semiconductor substrate. The lower surface of the first high-concentration region is located on the lower surface side of the semiconductor substrate. The first high-concentration region is, Displaced on the upper surface side of the semiconductor substrate, a hydrogen peak portion is provided where the hydrogen concentration shows a peak in the hydrogen concentration distribution in the depth direction, A flat portion is located on the lower surface side of the semiconductor substrate, where the carrier concentration is uniform in the depth direction and the doping concentration is higher than that of the bulk doping region, It has, The length of the flat portion in the depth direction is more than half the length of the first high-concentration region in the depth direction. In at least a portion of the edge termination structure, including the portion in contact with the active portion, the donor concentration extending from the depth position of the hydrogen peak to the lower surface of the semiconductor substrate is higher than the doping concentration of the bulk donor. The upper surface side of the bulk doping region of the edge termination structure is provided with a second high-concentration region of a first conductivity type having a doping concentration higher than that of the bulk doping region. The edge termination structure has a guard ring of a second conductivity type with a doping concentration higher than that of the bulk donor on the upper surface side of the semiconductor substrate. A second conductivity type well region is provided between the edge termination structure and the active portion, and the second high-concentration region is adjacent to the end side of the semiconductor substrate of the well region or one or more guard rings. Semiconductor equipment.

2. A semiconductor substrate having a bulk doping region of the first conductivity type in which a bulk donor of the first conductivity type is distributed throughout and the doping concentration is the same as that of the bulk donor, The semiconductor substrate has an active portion provided on it, An edge termination structure is provided on the semiconductor substrate, between the active portion and the edge of the semiconductor substrate on the upper surface of the semiconductor substrate. Equipped with, The edge termination structure has a first high-concentration region of a first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, where the donor concentration is higher than the doping concentration of the bulk donor. The upper surface of the first high-concentration region is located on the upper surface side of the semiconductor substrate. The lower surface of the first high-concentration region is located on the lower surface side of the semiconductor substrate. The first high-concentration region is, A hydrogen peak portion is located on the upper surface of the semiconductor substrate and shows a peak in hydrogen concentration in the depth direction hydrogen concentration distribution. It has, In at least a portion of the edge termination structure, including the portion in contact with the active portion, the donor concentration extending from the depth position of the hydrogen peak to the lower surface of the semiconductor substrate is higher than the doping concentration of the bulk donor. The first high-concentration region has a flat area in which the carrier concentration is uniform in the depth direction. The flat portion has a higher doping concentration than the bulk doping region. The length of the flat portion in the depth direction is more than half the length of the first high-concentration region in the depth direction. The upper surface side of the bulk doping region of the edge termination structure is provided with a second high-concentration region of a first conductivity type having a doping concentration higher than that of the bulk doping region. The edge termination structure has a guard ring of a second conductivity type with a doping concentration higher than that of the bulk donor on the upper surface side of the semiconductor substrate. A second conductivity type well region is provided between the edge termination structure and the active portion, and the second high-concentration region is adjacent to the end side of the semiconductor substrate of the well region or one or more guard rings. Semiconductor equipment.

3. A semiconductor substrate having a bulk doping region of the first conductivity type in which a bulk donor of the first conductivity type is distributed throughout and the doping concentration is the same as that of the bulk donor, The semiconductor substrate has an active portion provided on it, An edge termination structure is provided on the semiconductor substrate, between the active portion and the edge of the semiconductor substrate on the upper surface of the semiconductor substrate. Equipped with, The edge termination structure has a first high-concentration region of a first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, where the donor concentration is higher than the doping concentration of the bulk donor. The upper surface of the first high-concentration region is located on the upper surface side of the semiconductor substrate. The lower surface of the first high-concentration region is located on the lower surface side of the semiconductor substrate. The first high-concentration region is, Displaced on the upper surface side of the semiconductor substrate, a hydrogen peak portion is provided where the hydrogen concentration shows a peak in the hydrogen concentration distribution in the depth direction, A flat portion is located on the lower surface side of the semiconductor substrate, where the carrier concentration is uniform in the depth direction and the doping concentration is higher than that of the bulk doping region, It has, The length of the flat portion in the depth direction is more than half the length of the first high-concentration region in the depth direction. In at least a portion of the edge termination structure, including the portion in contact with the active portion, the donor concentration extending from the depth position of the hydrogen peak to the lower surface of the semiconductor substrate is higher than the doping concentration of the bulk donor. The first high-concentration region on the upper side of the hydrogen peak portion has a smaller width in the depth direction compared to the first high-concentration region on the lower side of the hydrogen peak portion. The upper surface side of the bulk doping region of the edge termination structure is provided with a second high-concentration region of a first conductivity type having a doping concentration higher than that of the bulk doping region. The edge termination structure has a guard ring of a second conductivity type with a doping concentration higher than that of the bulk donor on the upper surface side of the semiconductor substrate. A second conductivity type well region is provided between the edge termination structure and the active portion, and the second high-concentration region is adjacent to the end side of the semiconductor substrate of the well region or one or more guard rings. Semiconductor equipment.

4. A semiconductor substrate having a bulk doping region of the first conductivity type in which a bulk donor of the first conductivity type is distributed throughout and the doping concentration is the same as that of the bulk donor, The semiconductor substrate has an active portion provided on it, An edge termination structure is provided on the semiconductor substrate, between the active portion and the edge of the semiconductor substrate on the upper surface of the semiconductor substrate. Equipped with, The edge termination structure has a first high-concentration region of a first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, where the donor concentration is higher than the doping concentration of the bulk donor. The upper surface of the first high-concentration region is located on the upper surface side of the semiconductor substrate. The lower surface of the first high-concentration region is located on the lower surface side of the semiconductor substrate. The first high-concentration region is, Displaced on the upper surface side of the semiconductor substrate, a hydrogen peak portion is provided where the hydrogen concentration shows a peak in the hydrogen concentration distribution in the depth direction, A flat portion is located on the lower surface side of the semiconductor substrate, where the carrier concentration is uniform in the depth direction and the doping concentration is higher than that of the bulk doping region, It has, The length of the flat portion in the depth direction is more than half the length of the first high-concentration region in the depth direction. In at least a portion of the edge termination structure, including the portion in contact with the active portion, the donor concentration extending from the depth position of the hydrogen peak to the lower surface of the semiconductor substrate is higher than the doping concentration of the bulk donor. The slope of the hydrogen concentration distribution on the upper side of the hydrogen peak is steeper than the slope of the hydrogen concentration distribution on the lower side of the hydrogen peak. The upper surface side of the bulk doping region of the edge termination structure is provided with a second high-concentration region of a first conductivity type having a doping concentration higher than that of the bulk doping region. The edge termination structure has a guard ring of a second conductivity type with a doping concentration higher than that of the bulk donor on the upper surface side of the semiconductor substrate. A second conductivity type well region is provided between the edge termination structure and the active portion, and the second high-concentration region is adjacent to the end side of the semiconductor substrate of the well region or one or more guard rings. Semiconductor equipment.

5. A semiconductor substrate having a bulk doping region of the first conductivity type in which a bulk donor of the first conductivity type is distributed throughout and the doping concentration is the same as that of the bulk donor, The semiconductor substrate has an active portion provided on it, An edge termination structure is provided on the semiconductor substrate, between the active portion and the edge of the semiconductor substrate on the upper surface of the semiconductor substrate. Equipped with, The edge termination structure has a first high-concentration region of a first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, where the donor concentration is higher than the doping concentration of the bulk donor. The upper surface of the first high-concentration region is located on the upper surface side of the semiconductor substrate. The lower surface of the first high-concentration region is located on the lower surface side of the semiconductor substrate. The length of the first high-concentration region gradually increases in the depth direction as it moves away from the active portion. The first high-concentration region is, A hydrogen peak portion is located on the upper surface of the semiconductor substrate and shows a peak in hydrogen concentration in the depth direction hydrogen concentration distribution. It has, In at least a portion of the edge termination structure, including the portion in contact with the active portion, the donor concentration extending from the depth position of the hydrogen peak to the lower surface of the semiconductor substrate is higher than the doping concentration of the bulk donor. The upper surface side of the bulk doping region of the edge termination structure is provided with a second high-concentration region of a first conductivity type having a doping concentration higher than that of the bulk doping region. The edge termination structure has a guard ring of a second conductivity type with a doping concentration higher than that of the bulk donor on the upper surface side of the semiconductor substrate. A second conductivity type well region is provided between the edge termination structure and the active portion, and the second high-concentration region is adjacent to the end side of the semiconductor substrate of the well region or one or more guard rings. The active portion has a fourth high-concentration region of a first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, where the donor concentration is higher than the doping concentration of the bulk donor and is in contact with at least the first high-concentration region. The upper surface of the fourth high-concentration region is located on the upper surface side of the semiconductor substrate. The lower surface of the fourth high-concentration region is located on the lower surface side of the semiconductor substrate. The upper end position of the fourth high-concentration region is located on the lower side than the upper end position of the first high-concentration region. The donor concentration in the fourth high-concentration region is different from the donor concentration in the first high-concentration region. Semiconductor equipment.

6. A semiconductor substrate having a bulk doping region of the first conductivity type in which a bulk donor of the first conductivity type is distributed throughout and the doping concentration is the same as that of the bulk donor, The semiconductor substrate has an active portion provided on it, An edge termination structure is provided on the semiconductor substrate, between the active portion and the edge of the semiconductor substrate on the upper surface of the semiconductor substrate. Equipped with, The edge termination structure has a first high-concentration region of a first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, where the donor concentration is higher than the doping concentration of the bulk donor. The upper surface of the first high-concentration region is located on the upper surface side of the semiconductor substrate. The lower surface of the first high-concentration region is located on the lower surface side of the semiconductor substrate. The first high-concentration region is, A hydrogen peak portion is located on the upper surface of the semiconductor substrate and shows a peak in hydrogen concentration in the depth direction hydrogen concentration distribution. It has, In at least a portion of the edge termination structure, including the portion in contact with the active portion, the donor concentration extending from the depth position of the hydrogen peak to the lower surface of the semiconductor substrate is higher than the doping concentration of the bulk donor. The edge termination structure is in contact with the upper surface of the semiconductor substrate and is provided on the upper surface side of the semiconductor substrate than the first high-concentration region, and comprises a second high-concentration region of a first conductivity type in which the doping concentration is higher than that of the bulk doping region. The second high-concentration region has a first peak in the hydrogen concentration distribution, located at a depth greater than the upper surface of the semiconductor substrate, where the hydrogen concentration shows a peak. The doping concentration between the hydrogen peak and the first peak is equal to or greater than the doping concentration of the bulk donor. The edge termination structure has a guard ring of a second conductivity type with a doping concentration higher than that of the bulk donor on the upper surface side of the semiconductor substrate. A second conductivity type well region is provided between the edge termination structure and the active portion, and the second high-concentration region is adjacent to the end side of the semiconductor substrate of the well region or one or more guard rings. The active portion has a fourth high-concentration region of a first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, where the donor concentration is higher than the doping concentration of the bulk donor and is in contact with at least the first high-concentration region. The upper surface of the fourth high-concentration region is located on the upper surface side of the semiconductor substrate. The lower surface of the fourth high-concentration region is located on the lower surface side of the semiconductor substrate. The upper end position of the fourth high-concentration region is located on the lower side than the upper end position of the first high-concentration region. The donor concentration in the fourth high-concentration region is different from the donor concentration in the first high-concentration region. Semiconductor equipment.

7. The bulk doping region is located between the second high-concentration region and the first high-concentration region. The semiconductor device according to claim 6.

8. The hydrogen peak portion contains helium. The semiconductor device according to any one of claims 1 to 7.

9. The edge termination structure has a plurality of guard rings. The semiconductor device according to any one of claims 1 to 8.

10. The second high-concentration region is located between two adjacent guard rings. The semiconductor device according to claim 9.

11. The hydrogen peak region is located below the second high-concentration region. The semiconductor device according to claim 10.

12. The hydrogen peak portion is located between the lower end of the guard ring and the lower surface of the semiconductor substrate. The semiconductor device according to any one of claims 9 to 11.

13. The first high-concentration region is in contact with the guard ring. The semiconductor device according to any one of claims 9 to 12.

14. The active portion is The semiconductor substrate has a second conductivity type base region located on the upper surface side, The distance in the depth direction between the hydrogen peak region and the second high-concentration region is smaller than the maximum distance between the well region and each point of the guard ring closest to the well region. The semiconductor device according to claim 10 or 11.

15. A semiconductor substrate having a bulk doping region of the first conductivity type in which a bulk donor of the first conductivity type is distributed throughout and the doping concentration is the same as the concentration of the bulk donor, The semiconductor substrate has an active portion provided on it, An edge termination structure is provided on the semiconductor substrate, between the active portion and the edge of the semiconductor substrate on the upper surface of the semiconductor substrate. Equipped with, The edge termination structure has a first high-concentration region of a first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, where the donor concentration is higher than the doping concentration of the bulk donor. The upper surface of the first high-concentration region is located on the upper surface side of the semiconductor substrate. The lower surface of the first high-concentration region is located on the lower surface side of the semiconductor substrate. The first high-concentration region is located on the upper surface side of the semiconductor substrate and has a hydrogen peak portion in which the hydrogen concentration shows a peak in the hydrogen concentration distribution in the depth direction. In at least a portion of the edge termination structure, including the portion in contact with the active portion, the donor concentration extending from the depth position of the hydrogen peak to the lower surface of the semiconductor substrate is higher than the doping concentration of the bulk donor. The edge termination structure is in contact with the upper surface of the semiconductor substrate and is provided on the upper surface side of the semiconductor substrate than the first high-concentration region, and comprises a second high-concentration region of a first conductivity type in which the doping concentration is higher than that of the bulk doping region. The second high-concentration region has a first peak in the hydrogen concentration distribution, located at a depth greater than the upper surface of the semiconductor substrate, where the hydrogen concentration shows a peak. The doping concentration between the hydrogen peak and the first peak is equal to or greater than the doping concentration of the bulk donor. The edge termination structure has a guard ring of a second conductivity type with a doping concentration higher than that of the bulk donor on the upper surface side of the semiconductor substrate. A second conductivity type well region is provided between the edge termination structure and the active portion, and the second high-concentration region is adjacent to the end side of the semiconductor substrate of the well region or one or more guard rings. The active portion has a fourth high-concentration region of a first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, where the donor concentration is higher than the doping concentration of the bulk donor and is in contact with at least the first high-concentration region. The upper surface of the fourth high-concentration region is located on the upper surface side of the semiconductor substrate. The lower surface of the fourth high-concentration region is located on the lower surface side of the semiconductor substrate. The upper end position of the fourth high-concentration region is located on the lower side than the upper end position of the first high-concentration region. The second high-concentration region contains hydrogen injected from the upper surface of the semiconductor substrate. The hydrogen peak portion includes hydrogen injected from the lower surface of the semiconductor substrate. The first peak and the hydrogen peak overlap. Semiconductor equipment.

16. A semiconductor substrate having a bulk doping region of the first conductivity type in which a bulk donor of the first conductivity type is distributed throughout and the doping concentration is the same as the concentration of the bulk donor, The semiconductor substrate has an active portion provided on it, An edge termination structure is provided on the semiconductor substrate, between the active portion and the edge of the semiconductor substrate on the upper surface of the semiconductor substrate. Equipped with, The edge termination structure has a first high-concentration region of a first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, where the donor concentration is higher than the doping concentration of the bulk donor. The upper surface of the first high-concentration region is located on the upper surface side of the semiconductor substrate. The lower surface of the first high-concentration region is located on the lower surface side of the semiconductor substrate. The first high-concentration region is located on the upper surface side of the semiconductor substrate and has a hydrogen peak portion in which the hydrogen concentration shows a peak in the hydrogen concentration distribution in the depth direction. In at least a portion of the edge termination structure, including the portion in contact with the active portion, the donor concentration extending from the depth position of the hydrogen peak to the lower surface of the semiconductor substrate is higher than the doping concentration of the bulk donor. The edge termination structure is in contact with the upper surface of the semiconductor substrate and is provided on the upper surface side of the semiconductor substrate than the first high-concentration region, and comprises a second high-concentration region of a first conductivity type in which the doping concentration is higher than that of the bulk doping region. The second high-concentration region has a first peak in the hydrogen concentration distribution, located at a depth greater than the upper surface of the semiconductor substrate, where the hydrogen concentration shows a peak. The doping concentration between the hydrogen peak and the first peak is equal to or greater than the doping concentration of the bulk donor. The edge termination structure has a guard ring of a second conductivity type with a doping concentration higher than that of the bulk donor on the upper surface side of the semiconductor substrate. A second conductivity type well region is provided between the edge termination structure and the active portion, and the second high-concentration region is adjacent to the end side of the semiconductor substrate of the well region or one or more guard rings. The active portion has a fourth high-concentration region of a first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, where the donor concentration is higher than the doping concentration of the bulk donor and is in contact with at least the first high-concentration region. The upper surface of the fourth high-concentration region is located on the upper surface side of the semiconductor substrate. The lower surface of the fourth high-concentration region is located on the lower surface side of the semiconductor substrate. The upper end position of the fourth high-concentration region is located on the lower side than the upper end position of the first high-concentration region. The second high-concentration region contains hydrogen injected from the upper surface of the semiconductor substrate. The hydrogen peak portion includes hydrogen injected from the lower surface of the semiconductor substrate. The hydrogen peak portion is located between the first peak and the upper surface of the semiconductor substrate. Semiconductor equipment.

17. The second high-concentration region includes a hydrogen donor. The semiconductor device according to any one of claims 1 to 16.

18. The second high-concentration region is provided between two adjacent guard rings, extending from a position shallower than the lower end of the guard ring to a position deeper than the lower end of the guard ring. The semiconductor device according to any one of claims 1 to 12.

19. The second high-concentration region is in contact with the upper surface of the semiconductor substrate. The semiconductor device according to claim 18.

20. The first high-concentration region has a hydrogen donor. The semiconductor device according to any one of claims 1 to 19.

21. The bulk donor is either phosphorus or antimony. The semiconductor device according to any one of claims 1 to 20.

22. The first high-concentration region is provided in a range that does not reach the active portion. The semiconductor device according to any one of claims 1 to 4.

23. The first high-concentration region is, The inner part, An outer portion provided outside the inner portion, wherein the length of the semiconductor substrate in the depth direction is greater than that of the inner portion. A semiconductor device according to any one of claims 1 to 22, having the following features.

24. The semiconductor substrate has a second conductivity type bulk acceptor distributed throughout. The semiconductor device according to any one of claims 1 to 23.

25. The bulk acceptor is boron. The semiconductor device according to claim 24.

26. The donor dose in the second high-concentration region is 5 × 10 １１ / cm ２ The following is The semiconductor device according to any one of claims 1 to 12.

27. The donor dose in the second high-concentration region is 1 × 10⁻⁶ １１ / cm ２ That's all. The semiconductor device according to claim 26.

28. The peak value of the donor concentration in the second high-concentration region is 10 times or more the minimum value of the donor concentration in the first high-concentration region. The semiconductor device according to any one of claims 1 to 12.

29. The distance between the lower end of the second high-concentration region and the upper end of the first high-concentration region is 50 μm or less. The semiconductor device according to any one of claims 26 to 28.

30. The distance between the lower end of the second high-concentration region and the upper end of the first high-concentration region is 15 μm or more. The semiconductor device according to any one of claims 26 to 29.

31. The depth position of the lower end of the second high-concentration region is 2 μm or more away from the upper surface of the semiconductor substrate. The semiconductor device according to any one of claims 26 to 30.

32. The active portion has a fourth high-concentration region of a first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, where the donor concentration is higher than the doping concentration of the bulk donor. The upper surface of the fourth high-concentration region is located on the upper surface side of the semiconductor substrate. The lower surface of the fourth high-concentration region is located on the lower surface side of the semiconductor substrate. The donor concentration in the fourth high-concentration region is different from the donor concentration in the first high-concentration region. The semiconductor device according to any one of claims 1 to 4.

33. The active portion has a fourth high-concentration region of a first conductivity type in the region between the upper and lower surfaces of the semiconductor substrate, where the donor concentration is higher than the doping concentration of the bulk donor. The upper surface of the fourth high-concentration region is located on the upper surface side of the semiconductor substrate. The lower surface of the fourth high-concentration region is located on the lower surface side of the semiconductor substrate. The upper end position of the fourth high-concentration region is different from the upper end position of the first high-concentration region. The semiconductor device according to any one of claims 1 to 4.

34. In the edge termination structure, the first high-concentration region and the second high-concentration region are provided in a continuous manner. The semiconductor device according to claim 6.

35. The edge termination structure has a plurality of guard rings, At least a portion of the region, including the portion in contact with the active part, includes the area below the guard ring located closest to the active part. The semiconductor device according to any one of claims 1 to 8.

36. The doping concentration in the fourth high-concentration region is lower than the doping concentration in the first high-concentration region. The semiconductor device according to any one of claims 5 or 6.

37. The first high-concentration region is located on the lower surface side of the semiconductor substrate, relative to the hydrogen peak portion, and has a flat portion with a uniform carrier concentration. The semiconductor device according to claim 5 or 6.

38. The length of the flat portion in the depth direction is at least half the length of the first high-concentration region in the depth direction. The semiconductor device according to claim 37.

39. The carrier concentration in the flat portion is in a range that is greater than or equal to the minimum value in the depth direction and less than or equal to twice the minimum value. The semiconductor device according to any one of claims 1, 2, 3, 4, or 38.

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