Semiconductor Devices

Abstract

To provide a semiconductor device capable of controlling doping concentration distribution in a buffer region and the like to a prescribed shape.SOLUTION: A semiconductor device comprises: a buffer region in which a doping concentration DD is higher than a bulk donor concentration Db; a first low concentration hydrogen peak 125-1 arranged in the buffer region; a second concentration hydrogen peak 125-2 arranged in a position closer to a lower surface than the first low concentration hydrogen peak in the buffer region; high concentration hydrogen peaks 115-1 and 115-2 arranged in a position closer to the lower surface than the second low concentration peak in the buffer region and having a higher chemical concentration than the second low concentration hydrogen peak; a region 131 between the first low concentration hydrogen peak and the second low concentration hydrogen peak; and a flat region 130 including a region in which the second low concentration hydrogen peak is provided and having a higher doping concentration than a bulk donor concentration, an average value of the doping concentration being less than or equal to a minimum value of the doping concentration between the second low concentration hydrogen peak and the high concentration hydrogen peak.SELECTED DRAWING: Figure 4B

Description

[Technical Field]

[0001] The present invention relates to a semiconductor device. [Background technology]

[0002] BACKGROUND ART Conventionally, semiconductor devices that include a buffer region that functions as a field stop layer are known (see, for example, Patent Document 1). (Patent Document 1) U.S. Patent Application Publication No. 2016 / 0141399 Problem to be Solved

[0003] In a semiconductor device, it is preferable to control the distribution of doping concentration in a buffer region or the like to have a predetermined shape.

[0004] In order to solve the above problems, one aspect of the present invention provides a semiconductor device. The semiconductor device may include a semiconductor substrate having an upper surface and a lower surface and including bulk donors and oxygen. Any of the semiconductor devices may include a buffer region at least a portion of which is provided on the lower surface side of the semiconductor substrate and has a doping concentration higher than the bulk donor concentration. In any of the semiconductor devices, the buffer region may include a plurality of low-concentration hydrogen peaks in a hydrogen chemical concentration distribution. In any of the semiconductor devices, the buffer region may include a high-concentration hydrogen peak located closer to the lower surface than the plurality of low-concentration hydrogen peaks and having a higher hydrogen chemical concentration than the plurality of low-concentration hydrogen peaks. For at least one of the plurality of low-concentration hydrogen peaks of any of the semiconductor devices, the depth position of a corresponding concentration peak in the doping concentration distribution may be located closer to the lower surface than the depth position of the low-concentration hydrogen peak. For the low-concentration hydrogen peak located closest to the upper surface of the plurality of low-concentration hydrogen peaks of any of the semiconductor devices, the depth position of a corresponding concentration peak in the doping concentration distribution may be located closer to the lower surface than the depth position of the low-concentration hydrogen peak. In any of the above semiconductor devices, for all of the plurality of low-concentration hydrogen peaks, the depth position of the corresponding concentration peak of the doping concentration distribution may be located closer to the underside than the depth position of the low-concentration hydrogen peak. In any of the above semiconductor devices, the buffer region may include a region where the plurality of low-concentration hydrogen peaks are provided and a region between the plurality of low-concentration hydrogen peaks, and may further include a flat region in which, for at least one of the plurality of low-concentration hydrogen peaks, the width of the corresponding concentration peak of the doping concentration distribution is larger than the width of the low-concentration hydrogen peak. In any of the above semiconductor devices, for all of the plurality of low-concentration hydrogen peaks in the flat region, the width of the corresponding concentration peak of the doping concentration distribution may be larger than the width of the low-concentration hydrogen peak.

[0005] In any of the above semiconductor devices, the plurality of low-concentration hydrogen peaks may include a first low-concentration hydrogen peak. In any of the above semiconductor devices, the plurality of low-concentration hydrogen peaks may include a second low-concentration hydrogen peak located closer to the bottom surface than the first low-concentration hydrogen peak. In any of the above semiconductor devices, the flat region may include a region between the first low-concentration hydrogen peak and the second low-concentration hydrogen peak, and a region where the second low-concentration hydrogen peak is provided.

[0006] In any of the above semiconductor devices, the flat region may have a doping concentration higher than a bulk donor concentration.

[0007] In any of the above semiconductor devices, the flat region may have a doping concentration that varies within ±30% or less, and the rate of variation of the doping concentration may be smaller than the rate of variation of the hydrogen chemical concentration.

[0008] In any of the semiconductor devices described above, the doping concentration distribution in the depth direction of the flat region may have a concentration peak corresponding to the second low-concentration hydrogen peak, and the concentration peak may vary more gradually than the second low-concentration hydrogen peak.

[0009] In any of the above semiconductor devices, the concentration peak may be located closer to the lower surface of the semiconductor substrate than the second low concentration hydrogen peak.

[0010] In any of the above semiconductor devices, the length of the flat region in the depth direction may be equal to or greater than half the length of the buffer region.

[0011] In any of the above semiconductor devices, the average value of the doping concentration in the flat region may be 0.01% or more and 3% or less of the oxygen chemical concentration in the semiconductor substrate.

[0012] In any of the above semiconductor devices, the oxygen chemical concentration of the semiconductor substrate may be 10 times or more the hydrogen chemical concentration of the plurality of low-concentration hydrogen peaks.

[0013] In any of the above semiconductor devices, the interval (μm) between the first low-concentration hydrogen peak and the second low-concentration hydrogen peak is determined by the oxygen chemical concentration (atoms / cm) of the semiconductor substrate. 3 3 / 10 of 16 (μm / (atoms / cm 3 )) times or less.

[0014] In any of the above semiconductor devices, the hydrogen chemical concentration of the first low-concentration hydrogen peak is 1.0×10 16 atoms / cm 3 In any of the above semiconductor devices, the interval between the first low-concentration hydrogen peak and the second low-concentration hydrogen peak may be 100 μm or less.

[0015] In any of the semiconductor devices described above, the buffer region may have a lower surface region located on the lower side of a center of the buffer region and an upper surface region located on the upper side of the buffer region, and the number of low-concentration hydrogen peaks located in the upper surface region may be greater than the number of low-concentration hydrogen peaks located in the lower surface region.

[0016] In any of the above semiconductor devices, the hydrogen chemical concentration of the low-concentration hydrogen peak is 1×10 16 / cm 3 It may be the following:

[0017] In any of the above semiconductor devices, the doping concentration of the flat region may be at least twice the bulk donor concentration.

[0018] In any one of the above semiconductor devices, the doping concentration of the flat region is 0.7×10 13 / cm 3 It may be more than that.

[0019] In any of the semiconductor devices described above, each of the plurality of low-concentration hydrogen peaks may have a lower base extending from the peak toward the lower surface of the semiconductor substrate and an upper base extending from the peak toward the upper surface of the semiconductor substrate. In any of the semiconductor devices described above, the upper base may have a steeper decrease in hydrogen chemical concentration than the lower base.

[0020] In any one of the above semiconductor devices, the oxygen chemical concentration of the semiconductor substrate is 1.0×10 17 atoms / cm 3 It may be more than that.

[0021] In any one of the above semiconductor devices, the hydrogen ion dose of the first low hydrogen concentration peak is 1.0×10 12 ions / cm 2 In any of the above semiconductor devices, the hydrogen ion dose at the second low hydrogen concentration peak may be 1.0×10 or less. 12 ions / cm 2 In any of the above semiconductor devices, the average value of the doping concentration in the flat region may be equal to or less than the minimum value of the doping concentration between the second low-concentration hydrogen peak and the high-concentration hydrogen peak.

[0022] The buffer region of any of the above semiconductor devices may have a third low-concentration hydrogen peak located closer to the upper surface than the high-concentration hydrogen peak and closer to the lower surface than the second low-concentration hydrogen peak. In any of the above semiconductor devices, the flat region may include the third low-concentration hydrogen peak. In any of the above semiconductor devices, the average value of the doping concentration in the flat region may be equal to or less than the minimum value of the doping concentration between the third low-concentration hydrogen peak and the high-concentration hydrogen peak. In any of the above semiconductor devices, the flat region may have a fluctuation rate of the doping concentration equal to or less than half the fluctuation rate of the hydrogen chemical concentration. In any of the above semiconductor devices, the flat region may be formed from a center position in the depth direction of the semiconductor substrate to the upper surface side.

[0023] The above summary of the invention does not list all of the necessary features of the present invention, and subcombinations of these features may also constitute inventions. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a top view showing an example of a semiconductor device 100. FIG. [Figure 2] FIG. 2 is an enlarged view of an area D in FIG. [Figure 3] FIG. 3 is a diagram showing an example of an ee cross section in FIG. 2. [Figure 4A] 4 is a diagram showing an example of a doping concentration distribution in the depth direction at the position of the FF line in FIG. 3. FIG. [Figure 4B] 10 is a diagram showing an example of the distribution of the doping concentration DD and the hydrogen chemical concentration CH in the buffer region 20 in the depth direction. FIG. [Figure 5A] 4 is a diagram showing another example of the doping concentration distribution in the depth direction at the position of the FF line in FIG. 3. FIG. [Figure 5B] 5B is a diagram showing an example of the distribution of the doping concentration DD and the hydrogen chemical concentration CH in the depth direction in the buffer region 20 of FIG. 5A. FIG. [Figure 6] FIG. 2 is a diagram showing the doping concentration distribution of the buffer region 20 in an example and a comparative example. [Figure 7] FIG. 2 is a diagram showing the doping concentration distribution of the buffer region 20 in an example and a comparative example. [Figure 8] 4 is a diagram showing another example of the doping concentration distribution in the depth direction at the position of the FF line in FIG. 3. FIG. [Figure 9] This is an enlarged view of a plurality of adjacently arranged low-concentration hydrogen peaks 125. [Figure 10] FIG. 10 is a diagram showing another example of a plurality of low-concentration hydrogen peaks 125 arranged adjacent to each other. [Figure 11] FIG. 10 is a diagram showing another example of a plurality of low-concentration hydrogen peaks 125 arranged adjacent to each other. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention as claimed. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0026] In this specification, one side in a direction parallel to the depth direction of a semiconductor substrate is referred to as "upper" and the other side as "lower." Of the two main surfaces of a substrate, layer, or other member, one surface is referred to as the upper surface and the other surface is referred to as the lower surface. The directions of "upper" and "lower" are not limited to the direction of gravity or the directions when the semiconductor device is mounted.

[0027] In this specification, technical matters may be explained using the Cartesian coordinate axes of the X-axis, Y-axis, and Z-axis. The Cartesian coordinate axes merely identify the relative positions of components and do not limit a specific direction. For example, the Z-axis does not limit the height direction relative to the ground. Note that the +Z-axis direction and the -Z-axis direction are opposite directions. When the Z-axis direction is written without specifying positive or negative, it means the direction parallel to the +Z-axis and -Z-axis.

[0028] In this specification, orthogonal axes parallel to the top and bottom surfaces of the semiconductor substrate are referred to as the X-axis and Y-axis. Furthermore, an axis perpendicular to the top and bottom surfaces of the semiconductor substrate is referred to as the Z-axis. In this specification, the direction of the Z-axis may be referred to as the depth direction. Furthermore, in this specification, the direction parallel to the top and bottom surfaces of the semiconductor substrate, including the X-axis and Y-axis, may be referred to as the horizontal direction.

[0029] The region from the center of the semiconductor substrate in the depth direction to the top surface of the semiconductor substrate may be referred to as the top surface side. Similarly, the region from the center of the semiconductor substrate in the depth direction to the bottom surface of the semiconductor substrate may be referred to as the bottom surface side.

[0030] In this specification, when we say "same" or "equal," it may also include cases where there is an error due to manufacturing variations, etc. The error is, for example, within 10%.

[0031] In this specification, the conductivity type of a doped region doped with an impurity is described as P-type or N-type. In this specification, the impurity may particularly mean either an N-type donor or a P-type acceptor, and may be referred to as a dopant. In this specification, doping means introducing a donor or an acceptor into a semiconductor substrate to form a semiconductor exhibiting N-type conductivity or a semiconductor exhibiting P-type conductivity.

[0032] In this specification, the doping concentration refers to the concentration of donors or acceptors in a thermal equilibrium state. In this specification, the net doping concentration refers to the net concentration obtained by adding together the donor concentration as the concentration of positive ions and the acceptor concentration as the concentration of negative ions, taking into account the polarity of the charge. As an example, the donor concentration is N D , acceptor concentration N A Then, the net doping concentration at any point is N D -N A In this specification, the net doping concentration may be simply referred to as the doping concentration.

[0033] A donor has the function of supplying electrons to a semiconductor. An acceptor has the function of receiving electrons from a semiconductor. Donors and acceptors are not limited to impurities themselves. For example, a VOH defect, which is a combination of a vacancy (V), oxygen (O), and hydrogen (H) present in a semiconductor, functions as a donor that supplies electrons. In this specification, a VOH defect may be referred to as a hydrogen donor.

[0034] In this specification, the semiconductor substrate has N-type bulk donors distributed throughout. The bulk donors are donors due to dopants that are uniformly contained in the ingot that is the base of the semiconductor substrate when it is manufactured. In this example, the bulk donors are elements other than hydrogen. The dopants of the bulk donors are, for example, phosphorus, antimony, arsenic, selenium, or sulfur, but are not limited to these. In this example, the bulk donor is phosphorus. The bulk donors are also contained in the P-type region. The semiconductor substrate may be a wafer cut from a semiconductor ingot, or may be a chip obtained by dividing the wafer. The semiconductor ingot may be manufactured by any of the Czochralski method (CZ method), the magnetic field-applied Czochralski method (MCZ method), or the float zone method (FZ method). The ingot in this example is manufactured by the MCZ method. The oxygen concentration in the substrate manufactured by the MCZ method is, for example, 1×10 17 ~7×10 17 / cm 3 The oxygen concentration in the substrate manufactured by the FZ method is, for example, 1×10 15 ~5×10 16 / cm 3 The higher the oxygen concentration, the easier it is to generate hydrogen donors. The bulk donor concentration may be the chemical concentration of bulk donors distributed throughout the semiconductor substrate, and may be between 90% and 100% of that chemical concentration. Alternatively, a non-doped substrate that does not contain dopants such as phosphorus may be used as the semiconductor substrate. In this case, the bulk donor concentration (D b ) is, for example, 1×10 10 / cm 3 That's it, 5 x 10 12 / cm 3 The bulk donor concentration (D b ) is preferably 1 × 10 11 / cm 3 The bulk donor concentration (D b ) is preferably 5 × 10 12 / cm 3The concentrations in the present invention may be values at room temperature, for example, values at 300 K (Kelvin) (approximately 26.9° C.).

[0035] In this specification, when P+ type or N+ type is used, it means that the doping concentration is higher than that of P type or N type, and when P- type or N- type is used, it means that the doping concentration is lower than that of P type or N type. Furthermore, when P++ type or N++ type is used in this specification, it means that the doping concentration is higher than that of P+ type or N+ type. The unit system used in this specification is the SI unit system unless otherwise specified. The unit of length may be expressed in cm, but various calculations may be performed after converting to meters (m).

[0036] As used herein, chemical concentration refers to the atomic density of an impurity measured regardless of its electrical activation state. Chemical concentration can be measured, for example, by secondary ion mass spectrometry (SIMS). The net doping concentration can be measured by voltage-capacitance (CV) measurement. The carrier concentration measured by spreading resistance (SR) measurement may also be used as the net doping concentration. The carrier concentration measured by CV or SR may be used as the value in a thermal equilibrium state. In addition, since the donor concentration in an N-type region is significantly greater than the acceptor concentration, the carrier concentration in that region may also be used as the donor concentration. Similarly, in a P-type region, the carrier concentration in that region may also be used as the acceptor concentration. In this specification, the doping concentration in an N-type region may also be referred to as the donor concentration, and the doping concentration in a P-type region may also be referred to as the acceptor concentration.

[0037] In addition, when the concentration distribution of the donor, acceptor, or net doping has a peak, the peak value may be taken as the concentration of the donor, acceptor, or net doping in that region. In cases where the concentration of the donor, acceptor, or net doping is almost uniform, the average value of the concentration of the donor, acceptor, or net doping in that region may be taken as the concentration of the donor, acceptor, or net doping. In this specification, the concentration per unit volume is expressed in atoms / cm. 3 , or / cm 3 This unit is used for donor or acceptor concentration or chemical concentration in a semiconductor substrate. The atom notation may be omitted.

[0038] The carrier concentration measured by the SR method may be lower than the donor or acceptor concentration. In the range where current flows when measuring spreading resistance, the carrier mobility of the semiconductor substrate may be lower than the value in the crystalline state. The decrease in carrier mobility occurs when carriers are scattered due to disorder in the crystal structure caused by lattice defects, etc.

[0039] The donor or acceptor concentration calculated from the carrier concentration measured by the CV or SR method may be lower than the chemical concentration of the element that represents the donor or acceptor. As an example, the donor concentration of phosphorus or arsenic, which act as donors in silicon semiconductors, or the acceptor concentration of boron, which acts as an acceptor, is approximately 99% of the chemical concentration. On the other hand, the donor concentration of hydrogen, which acts as a donor in silicon semiconductors, is approximately 0.1% to 10% of the chemical concentration of hydrogen.

[0040] Fig. 1 is a top view showing an example of a semiconductor device 100. Fig. 1 shows the positions of each component projected onto the top surface of a semiconductor substrate 10. Fig. 1 shows only some of the components of the semiconductor device 100, and some components are omitted.

[0041] The semiconductor device 100 includes a semiconductor substrate 10. The semiconductor substrate 10 is a substrate formed of a semiconductor material. As an example, the semiconductor substrate 10 is a silicon substrate, but the material of the semiconductor substrate 10 is not limited to silicon.

[0042] The semiconductor substrate 10 has end sides 162 in a top view. In this specification, the term "top view" simply refers to a view from the top surface side of the semiconductor substrate 10. The semiconductor substrate 10 of this example has two pairs of end sides 162 that face each other in a top view. In FIG. 1, the X-axis and Y-axis are parallel to either of the end sides 162. The Z-axis is perpendicular to the top surface of the semiconductor substrate 10.

[0043] An active portion 160 is provided on the semiconductor substrate 10. The active portion 160 is a region through which a main current flows in the depth direction between the upper and lower surfaces of the semiconductor substrate 10 when the semiconductor device 100 is in operation. An emitter electrode is provided above the active portion 160, but is not shown in FIG.

[0044] 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 free wheel diode (FWD). In the example of Fig. 1, the transistor sections 70 and the diode sections 80 are alternately arranged along a predetermined arrangement direction (the X-axis direction in this example) on the upper surface of the semiconductor substrate 10. In another example, the active section 160 may be provided with only one of the transistor section 70 and the diode section 80.

[0045] In FIG. 1, the region where the transistor section 70 is arranged is marked with the symbol "I," and the region where the diode section 80 is arranged is marked with 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 (the Y-axis direction in FIG. 1). The transistor section 70 and the diode section 80 may each have a longitudinal direction in the extension direction. In other words, the length of the transistor section 70 in the Y-axis direction is greater than the width in the X-axis direction. Similarly, the length of the diode section 80 in the Y-axis direction is greater than the 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, which will be described later.

[0046] The diode section 80 has an N+ type cathode region in a region 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 a region that overlaps with the cathode region in a top view. A P+ type collector region may be provided in a region of the lower surface of the semiconductor substrate 10 other than the cathode region. In this specification, an extension region 81 in which the diode section 80 is extended in the Y-axis direction to a 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.

[0047] The transistor section 70 has a P+ type collector region in a region in contact with the lower surface of the semiconductor substrate 10. In addition, the transistor section 70 has a gate structure periodically arranged on the upper surface side of the semiconductor substrate 10, the gate structure having an N type emitter region, a P type base region, a gate conductive portion, and a gate insulating film.

[0048] The semiconductor device 100 may have one or more pads above the semiconductor substrate 10. The semiconductor device 100 of this example has a gate pad 164. The semiconductor device 100 may also have pads such as an anode pad, a cathode pad, and a current detection pad. Each pad is disposed near an edge 162. The vicinity of the edge 162 refers to the region between the edge 162 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 a wire.

[0049] A gate potential is applied to the gate pad 164. The gate pad 164 is electrically connected to a conductive portion of the gate trench portion of the active portion 160. The semiconductor device 100 includes a gate wiring that connects the gate pad 164 and the gate trench portion. In FIG. 1, the gate wiring is indicated by diagonal hatching.

[0050] The gate wiring in this example has a peripheral gate wiring 101 and an active side gate wiring 102. The peripheral gate wiring 101 is arranged between the active portion 160 and an edge 162 of the semiconductor substrate 10 in a top view. The peripheral gate wiring 101 in this example surrounds the active portion 160 in a top view. The area surrounded by the peripheral gate wiring 101 in a top view may also be the active portion 160. The peripheral gate wiring 101 is connected to a gate pad 164. The peripheral gate wiring 101 is arranged above the semiconductor substrate 10. The peripheral gate wiring 101 may be a metal wiring containing aluminum or the like.

[0051] The active side gate wiring 102 is provided in the active section 160. By providing the active side gate wiring 102 in the active section 160, it is possible to reduce variations in wiring length from the gate pad 164 for each region of the semiconductor substrate 10.

[0052] The active side gate wiring 102 is connected to the gate trench portion of the active section 160. The active side gate wiring 102 is disposed above the semiconductor substrate 10. The active side gate wiring 102 may be a wiring formed of a semiconductor such as polysilicon doped with impurities.

[0053] The active-side gate wiring 102 may be connected to the peripheral gate wiring 101. In this example, the active-side gate wiring 102 extends in the X-axis direction from one peripheral gate wiring 101 to the other peripheral gate wiring 101 at approximately the center in the Y-axis direction, crossing the active section 160. When the active section 160 is divided by the active-side gate wiring 102, the transistor sections 70 and the diode sections 80 may be arranged alternately in the X-axis direction in each divided region.

[0054] The semiconductor device 100 may also include a temperature sensing section (not shown) which is a PN junction diode formed of polysilicon or the like, and a current detecting section (not shown) which simulates the operation of a transistor section provided in the active section 160.

[0055] In the present example, semiconductor device 100 includes an edge termination structure 90 between active section 160 and edge 162 when viewed from above. Edge termination structure 90 in the present example is disposed between peripheral gate wiring 101 and edge 162. Edge termination structure 90 relieves electric field concentration on the upper surface side of semiconductor substrate 10. Edge termination structure 90 may include at least one of a guard ring, a field plate, and a resurf, which are arranged in an annular shape surrounding active section 160.

[0056] 2 is an enlarged view of region D in FIG. 1. Region D is a region including a transistor section 70, a diode section 80, and an active-side gate wiring 102. The semiconductor device 100 of this example includes a gate trench section 40, a dummy trench section 30, a well region 11, an emitter region 12, a base region 14, and a contact region 15 provided inside the upper surface side of a semiconductor substrate 10. The gate trench section 40 and the dummy trench section 30 are each an example of a trench section. The semiconductor device 100 of this example also includes an emitter electrode 52 and an active-side gate wiring 102 provided above the upper surface of the semiconductor substrate 10. The emitter electrode 52 and the active-side gate wiring 102 are provided separately from each other.

[0057] An interlayer insulating film is provided between the emitter electrode 52 and the active-side gate wiring 102 and the upper surface of the semiconductor substrate 10, but is not shown in Fig. 2. In this example, contact holes 54 are provided in the interlayer insulating film so as to penetrate the interlayer insulating film. In Fig. 2, each contact hole 54 is hatched with diagonal lines.

[0058] The emitter electrode 52 is provided above the gate trench portion 40, the dummy trench portion 30, the well region 11, the emitter region 12, the base region 14, and the contact region 15. The emitter electrode 52 contacts the emitter region 12, the contact region 15, and the 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 portion 30 through a contact hole provided in the interlayer insulating film. The emitter electrode 52 may be connected to the dummy conductive portion of the dummy trench portion 30 at the tip of the dummy trench portion 30 in the Y-axis direction.

[0059] The active side gate wiring 102 is connected to the gate trench portion 40 through a contact hole provided in the interlayer insulating film. The active side gate wiring 102 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 side gate wiring 102 is not connected to the dummy conductive portion in the dummy trench portion 30.

[0060] The emitter electrode 52 is made of a material containing metal. FIG. 2 shows the area where the emitter electrode 52 is provided. For example, at least a portion of the emitter electrode 52 is made of aluminum or an aluminum-silicon alloy, such as AlSi or AlSiCu. The emitter electrode 52 may have a barrier metal made of titanium, a titanium compound, or the like below the region made of aluminum or the like. Furthermore, the contact hole may have a plug formed by embedding tungsten or the like so as to contact the barrier metal and aluminum or the like.

[0061] The well region 11 is provided so as to overlap with the active-side gate wiring 102. The well region 11 is also provided so as to extend by a predetermined width into an area where it does not overlap with the active-side gate wiring 102. In this example, the well region 11 is provided away from the end of the contact hole 54 in the Y-axis direction toward the active-side gate wiring 102. The well region 11 is a region of a second conductivity type having a doping concentration higher than that of the base region 14. In this example, the base region 14 is P- type, and the well region 11 is P+ type.

[0062] Each of the transistor section 70 and the diode section 80 has a plurality of trench sections arranged in the arrangement direction. In the transistor section 70 of this example, one or more gate trench sections 40 and one or more dummy trench sections 30 are alternately provided along the arrangement direction. In the diode section 80 of this example, a plurality of dummy trench sections 30 are provided along the arrangement direction. In the diode section 80 of this example, no gate trench section 40 is provided.

[0063] The gate trench portion 40 in this example may have two straight line portions 39 (parts of the trench that are linear along the extension direction) that extend along an extension direction perpendicular to the arrangement direction, and a tip portion 41 that connects the two straight line portions 39. The extension direction in FIG. 2 is the Y-axis direction.

[0064] At least a part of the tip portion 41 is preferably curved in a top view. By connecting the ends of the two straight portions 39 in the Y-axis direction with each other by the tip portion 41, electric field concentration at the ends of the straight portions 39 can be alleviated.

[0065] In the transistor section 70, the dummy trench section 30 is provided between each of the linear portions 39 of the gate trench section 40. One or more dummy trench sections 30 may be provided between each of the linear portions 39. The dummy trench section 30 may have a linear shape extending in the extension direction, and may have a linear section 29 and an end portion 31, similar to the gate trench section 40. The semiconductor device 100 shown in FIG. 2 includes both linear dummy trench sections 30 without end portions 31 and dummy trench sections 30 with end portions 31.

[0066] The diffusion depth of the well region 11 may be deeper than the depths of the gate trench portion 40 and the dummy trench portion 30. The ends of the gate trench portion 40 and the dummy trench portion 30 in the Y-axis direction are provided in the well region 11 when viewed from above. In other words, at the ends of each trench portion in the Y-axis direction, the bottom of each trench portion in the depth direction is covered by the well region 11. This makes it possible to alleviate electric field concentration at the bottom of each trench portion.

[0067] A mesa portion is provided between each trench portion in the arrangement direction. The mesa portion refers to a region inside the semiconductor substrate 10 that is sandwiched between the trench portions. As an example, the upper end of the mesa portion is the upper surface of the semiconductor substrate 10. The depth position of the lower end of the mesa portion is the same as the depth position of the lower end of the trench portion. In this example, the mesa portion is provided on the upper surface of the semiconductor substrate 10, extending in the extension direction (Y-axis direction) along the trench. In this example, the transistor portion 70 is provided with a mesa portion 60, and the diode portion 80 is provided with a mesa portion 61. In this specification, the mesa portion simply referred to as a mesa portion refers to both the mesa portion 60 and the mesa portion 61.

[0068] A base region 14 is provided in each mesa portion. 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-side gate wiring 102 is referred to as the base region 14-e. While FIG. 2 shows the base region 14-e at one end of each mesa portion in the extension direction, a base region 14-e is also provided at the other end of each mesa portion. Each mesa portion may be provided with at least one of a first-conductivity-type emitter region 12 and a second-conductivity-type contact region 15 in a 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 between the base region 14 and the upper surface of the semiconductor substrate 10 in the depth direction.

[0069] 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 be provided with a contact region 15 exposed on the upper surface of the semiconductor substrate 10.

[0070] The contact regions 15 and the emitter regions 12 in the mesa portion 60 are each provided from one trench portion to the other trench portion in the X-axis direction. As an example, the contact regions 15 and the emitter regions 12 in the mesa portion 60 are alternately arranged along the extension direction of the trench portions (the Y-axis direction).

[0071] In another example, the contact region 15 and the emitter region 12 of the mesa portion 60 may be provided in a stripe shape along the extension direction (Y-axis direction) of the trench portion. For example, the emitter region 12 is provided in a region in contact with the trench portion, and the contact region 15 is provided in a region sandwiched between the emitter regions 12.

[0072] 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 sandwiched between the base regions 14-e on the upper surface of the mesa portion 61, a contact region 15 may be provided in contact with each of the base regions 14-e. In the region sandwiched between the contact regions 15 on the upper surface of the mesa portion 61, a base region 14 may be provided. The base region 14 may be disposed in the entire region sandwiched between the contact regions 15.

[0073] A contact hole 54 is provided above each mesa portion. The contact hole 54 is arranged in a region sandwiched between the base regions 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 regions corresponding to the base region 14-e and the well region 11. The contact hole 54 may be arranged in the center of the arrangement direction (X-axis direction) of the mesa portions 60.

[0074] In the diode section 80, an N+ type cathode region 82 is provided in a region adjacent to the lower surface of the semiconductor substrate 10. A P+ type collector region 22 may be provided in a region of the lower surface of the semiconductor substrate 10 where the cathode region 82 is not provided. The cathode region 82 and the collector region 22 are provided between the lower surface 23 of the semiconductor substrate 10 and the buffer region 20. In FIG. 2, the boundary between the cathode region 82 and the collector region 22 is indicated by a dotted line.

[0075] The cathode region 82 is disposed away from the well region 11 in the Y-axis direction. This ensures a distance between the cathode region 82 and a P-type region (well region 11) that has a relatively high doping concentration and is formed deep, thereby improving the breakdown voltage. In this example, the end of the cathode region 82 in the Y-axis direction is disposed farther from the well region 11 than the end of the contact hole 54 in the Y-axis direction. In another example, the end of the cathode region 82 in the Y-axis direction may be disposed between the well region 11 and the contact hole 54.

[0076] Fig. 3 is a diagram showing an example of an ee cross section in Fig. 2. The ee cross section is an XZ plane passing through the emitter region 12 and the cathode region 82. In this cross section, the semiconductor device 100 of this example has a semiconductor substrate 10, an interlayer insulating film 38, an emitter electrode 52, and a collector electrode 24.

[0077] The interlayer insulating film 38 is provided on the upper surface of the semiconductor substrate 10. The interlayer insulating film 38 is a film including at least one layer of an insulating film such as silicate glass doped with impurities such as boron or phosphorus, a thermal oxide film, and other insulating films. The interlayer insulating film 38 is provided with the contact hole 54 described with reference to FIG. 2.

[0078] The emitter electrode 52 is provided above the interlayer insulating film 38. The emitter electrode 52 passes through a contact hole 54 in the interlayer insulating film 38 and contacts the upper surface 21 of the semiconductor substrate 10. The collector electrode 24 is provided on the lower surface 23 of the semiconductor substrate 10. The emitter electrode 52 and the collector electrode 24 are made of a metal material such as aluminum. In this specification, the direction connecting the emitter electrode 52 and the collector electrode 24 (the Z-axis direction) is referred to as the depth direction.

[0079] The semiconductor substrate 10 has an N-type or N-type drift region 18. The drift region 18 is provided in each of the transistor section 70 and the diode section 80.

[0080] In the mesa portion 60 of the transistor section 70, an N+ type emitter region 12 and a P- type base region 14 are provided in this order from the upper surface 21 side of the semiconductor substrate 10. A drift region 18 is provided below the base region 14. An N+ type accumulation region 16 may be provided in the mesa portion 60. The accumulation region 16 is disposed between the base region 14 and the drift region 18.

[0081] 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 emitter region 12 has a higher doping concentration than the drift region 18.

[0082] The base region 14 is provided below the emitter region 12. In this example, the base region 14 is provided in contact with the emitter region 12. The base region 14 may be in contact with the trench portions on both sides of the mesa portion 60.

[0083] The accumulation region 16 is provided below the base region 14. The accumulation region 16 is an N+ type region with a higher doping concentration than the drift region 18. The accumulation region 16 may have a concentration peak of a donor such as a phosphorus or hydrogen donor. By providing the high-concentration accumulation region 16 between the drift region 18 and the base region 14, the carrier injection enhancement effect (IE effect) can be enhanced, thereby reducing the on-state voltage. 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.

[0084] A P-type base region 14 is provided in the mesa portion 61 of the diode section 80 in contact with the upper surface 21 of the semiconductor substrate 10. A drift region 18 is provided below the base region 14. An accumulation region 16 may be provided below the base region 14 in the mesa portion 61.

[0085] In each of the transistor section 70 and the diode section 80, an N+ type buffer region 20 may be provided below the drift region 18. The doping concentration of the buffer region 20 is higher than that of the drift region 18. The buffer region 20 may have a concentration peak with a higher doping concentration than the drift region 18. The doping concentration of the concentration peak refers to the doping concentration at the apex of the concentration peak. The doping concentration of the drift region 18 may be the average value of the doping concentration in a region where the doping concentration distribution is approximately flat.

[0086] The buffer region 20 may be formed by ion implantation of an N-type dopant such as hydrogen (protons) or phosphorus. In this example, the buffer region 20 is formed by ion implantation of hydrogen. The buffer region 20 may function as a field stop layer that prevents a depletion layer extending from the bottom end of the base region 14 from reaching the P+ type collector region 22 and the N+ type cathode region 82.

[0087] 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 the acceptor concentration of the base region 14. The collector region 22 may contain the same acceptor as the base region 14, or may contain a different acceptor. The acceptor of the collector region 22 is, for example, boron.

[0088] In the diode section 80, an N+ type cathode region 82 is provided below the buffer region 20. The donor concentration of the cathode region 82 is higher than that of the drift region 18. The donor of the cathode region 82 is, for example, hydrogen or phosphorus. Note that the elements that serve as the donor and acceptor in each region are not limited to the above-mentioned examples. The collector region 22 and the cathode region 82 are exposed on the lower surface 23 of the semiconductor substrate 10 and 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 formed of a metal material such as aluminum.

[0089] One or more gate trenches 40 and one or more dummy trenches 30 are provided on the top surface 21 of the semiconductor substrate 10. Each trench extends from the top surface 21 of the semiconductor substrate 10 through the base region 14 to reach the drift region 18. In regions where at least one of the emitter region 12, the contact region 15, and the accumulation region 16 is provided, each trench also extends through these doped regions to reach the drift region 18. The trenches extending through the doped regions do not necessarily mean that the trenches are formed after the doped regions are formed. The trenches also include those in which the doped regions are formed between the trenches after the trenches are formed.

[0090] As described above, the transistor section 70 is provided with the gate trench section 40 and the dummy trench section 30. The diode section 80 is provided with the dummy trench section 30, but is not provided with the 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.

[0091] 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 to cover 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 and on the inner side 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.

[0092] The gate conductive portion 44 may be provided to be longer in the depth direction than the base region 14. The gate trench portion 40 in this cross section is covered with 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 is formed by an electron inversion layer in the surface layer of the interface of the base region 14 that contacts the gate trench portion 40.

[0093] The dummy trench portion 30 may have the same structure as the gate trench portion 40 in the 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 is electrically connected to the emitter electrode 52. The dummy insulating film 32 covers the inner wall of the dummy trench. The dummy conductive portion 34 is provided inside the dummy trench and is provided further inward than 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 of the same material as the gate conductive portion 44. For example, the dummy conductive portion 34 is formed of a conductive material such as polysilicon. The dummy conductive portion 34 may have the same length in the depth direction as the gate conductive portion 44.

[0094] The gate trench portion 40 and the dummy trench portion 30 in this example are covered with an interlayer insulating film 38 on the upper surface 21 of the semiconductor substrate 10. The bottoms of the dummy trench portion 30 and the gate trench portion 40 may have a downwardly convex curved shape (a curved shape in cross section).

[0095] Fig. 4A is a diagram showing an example of a doping concentration distribution in the depth direction at the position of line FF in Fig. 3. The vertical axis of Fig. 4A is a logarithmic axis. In Fig. 4A, the central position in the depth direction of the semiconductor substrate 10 is set to Zc.

[0096] The emitter region 12 has a peak concentration of an N-type dopant, such as, but not limited to, phosphorus. The base region 14 has a peak concentration of a P-type dopant, such as, but not limited to, boron. The accumulation region 16 has a peak concentration of an N-type dopant, such as, but not limited to, hydrogen or phosphorus.

[0097] The drift region 18 may have a substantially constant doping concentration. The doping concentration of the drift region 18 is determined by the bulk donor concentration D b The bulk donor concentration D may be identical to b It may be higher.

[0098] The buffer region 20 has a bulk donor concentration D b The buffer region 20 is an N-type region having a higher doping concentration than the drift region 18. The buffer region 20 may have a higher doping concentration than the drift region 18. At least a portion of the buffer region 20 is provided on the lower surface 23 side of the semiconductor substrate 10. The lower surface 23 side is the region between the lower surface 23 and the central position Zc. The doping concentration distribution in the buffer region 20 of this example may have a concentration peak 25. The buffer region 20 may have multiple concentration peaks 25 provided at different positions in the depth direction.

[0099] The buffer region 20 has a flat region 130. The flat region 130 may be located between the concentration peak 25 and the drift region 18. The flat region 130 is a region where the doping concentration is approximately constant.

[0100] FIG. 4B shows the doping concentration D D and hydrogen chemical concentration C H 4B is a diagram showing an example of the distribution of bulk donors and oxygen in the depth direction. The semiconductor substrate 10 of this example contains bulk donors and oxygen. In FIG. 4B, the bulk donor concentration is represented by D b , oxygen chemical concentration C OX Let the bulk donor concentration D b may be uniform in the depth direction of the semiconductor substrate 10.OX may be uniform, monotonically increasing, or monotonically decreasing in the depth direction of the semiconductor substrate 10. OX is 1.0 x 10 17 atoms / cm 3 may be greater than or equal to 3.0 x 10 17 atoms / cm 3 may be greater than or equal to 5.0 x 10 17 atoms / cm 3 may be greater than or equal to 7.0 x 10 17 atoms / cm 3 The oxygen chemical concentration C OX is 3.0 x 10 18 atoms / cm 3 may be less than or equal to 2.0 x 10 18 atoms / cm 3 may be less than or equal to 1.0 x 10 18 atoms / cm 3 It may be the following:

[0101] Note that oxygen near the surface of the semiconductor substrate 10 may be released to the outside of the semiconductor substrate 10. Therefore, in the vicinity of the surface of the semiconductor substrate 10, the oxygen chemical concentration C OX is 1.0 x 10 17 atoms / cm 3 The oxygen chemical concentration C OX is the oxygen chemical concentration C throughout the semiconductor substrate 10 OX In another example, the average value of the oxygen chemical concentration C OX may be the oxygen chemical concentration in the buffer region 20. For example, the minimum value of the oxygen chemical concentration in the buffer region 20 may be set as the oxygen chemical concentration C OX The oxygen chemical concentration C OX For example, the minimum value of the oxygen chemical concentration in the plateau region 130 may be set as the oxygen chemical concentration C OX This can be considered.

[0102] The buffer region 20 in this example is formed by implanting hydrogen ions from the lower surface 23 of the semiconductor substrate 10. The doping concentration D of the buffer region 20D is the concentration of hydrogen donors and the bulk donor concentration D b It may be the sum of

[0103] The hydrogen ions are implanted near the apex of the concentration peak 25 and into the plateau region 130. Some of the hydrogen ions may be implanted between the plateau region 130 and the drift region 18. In this example, the hydrogen ions are implanted into the buffer region 20 at depth positions Z11, Z12, Z32, and Z31, respectively. The hydrogen chemical concentration C H The depth positions Z11, Z12, Z32, and Z31 have increasing distances from the lower surface 23 in this order.

[0104] In this example, the hydrogen chemical concentration C H Among these peaks, the peak where the dose of hydrogen ions is equal to or less than a predetermined value is referred to as a low-concentration hydrogen peak 125. Also, the peak where the dose of hydrogen ions is greater than the predetermined value is referred to as a high-concentration hydrogen peak 115. Also, the low-concentration hydrogen peak and the high-concentration hydrogen peak may be collectively referred to as a hydrogen peak. The above-mentioned predetermined value is 1.0×10 12 ions / cm 2 The predetermined value is 5.0×10 11 ions / cm 2 The dose of hydrogen ions at the hydrogen peak may be determined by the hydrogen chemical concentration C H The dose of hydrogen ions for the low concentration hydrogen peak 125 is 1.0 × 10 10 ions / cm 2 may be greater than or equal to 1.0 x 10 11 ions / cm 2 The dose of hydrogen ions for the low-concentration hydrogen peak 125 may be 5.0×10 12 ions / cm 2 may be less than or equal to 3.0 x 10 12 ions / cm 2 may be less than or equal to 2.0 x 10 12 ions / cm 2The oxygen chemical concentration may be, for example, 5.0×10 17 atoms / cm 3 In the above case, the dose of hydrogen ions for the low concentration hydrogen peak 125 is 3.0 × 10 12 ions / cm 2 That's it, 1.0 x 10 13 ions / cm 2 It may be the following:

[0105] Also, the hydrogen chemical concentration C H The hydrogen chemical concentration C at the peak of H The peak where the hydrogen chemical concentration C at the peak is equal to or less than a predetermined value may be defined as the low-concentration hydrogen peak 125. H A peak where the value of the hydrogen concentration is greater than the predetermined value may be determined as a high-concentration hydrogen peak 115. The predetermined value is 1.0×10 16 atoms / cm 3 The predetermined value is 5.0×10 15 atoms / cm 3 The hydrogen chemical concentration C at the top of the low-concentration hydrogen peak 125 may be H is 1.0 x 10 14 atoms / cm 3 may be greater than or equal to 1.0 x 10 15 atoms / cm 3 It may be more than that.

[0106] The buffer region 20 has a first low-concentration hydrogen peak 125-1 and a second low-concentration hydrogen peak 125-2. In this example, the first low-concentration hydrogen peak 125-1 is located at depth position Z11. In this example, the second low-concentration hydrogen peak 125-2 is located at depth position Z12. That is, the second low-concentration hydrogen peak 125-2 is located at a position in the buffer region 20 closer to the lower surface 23 than the first low-concentration hydrogen peak 125-1. In this specification, the position of the apex of each hydrogen peak is referred to as the depth position of the hydrogen peak. In this example, the position of the implantation position of the hydrogen ions and the position of the apex of the hydrogen peak are the same.

[0107] The buffer region 20 may have one or more high-concentration hydrogen peaks 115. In this example, the buffer region 20 has a first high-concentration hydrogen peak 115-1 and a second high-concentration hydrogen peak 115-2. In this example, the first high-concentration hydrogen peak 115-1 is located at depth position Z31. In this example, the second high-concentration hydrogen peak 115-2 is located at depth position Z32. In this example, the first low-concentration hydrogen peak 125-1 is the hydrogen peak formed in the buffer region 20 that is located closest to the upper surface 21. In addition, in this example, the first high-concentration hydrogen peak 115-1 is the hydrogen peak formed in the buffer region 20 that is located closest to the lower surface 23.

[0108] When hydrogen ions are implanted from the lower surface 23, hydrogen is also distributed in the region from the implantation position to the lower surface 23. Therefore, the slope of the lower surface skirt 127 from the peak of each hydrogen peak toward the lower surface 23 becomes gentler, and the slope of the upper surface skirt 126 from the peak of the hydrogen peak toward the upper surface 21 becomes steeper than the lower surface skirt 127.

[0109] When the semiconductor substrate 10 is irradiated with charged particles such as hydrogen ions, vacancy-based lattice defects, such as monovacancies (V) and divacancies (VV), are formed in the region through which the charged particles have passed. In this example, lattice defects are formed in the region from the underside 23 of the semiconductor substrate 10 to near the apex of the first low-concentration hydrogen peak 125-1. Atoms adjacent to the vacancies have dangling bonds. Lattice defects include interstitial atoms and dislocations, and may also include donors and acceptors in a broad sense. However, in this specification, vacancy-based lattice defects may be referred to as vacancy-type lattice defects, vacancy-type defects, or simply lattice defects. Furthermore, the formation of many lattice defects due to the implantation of charged particles into the semiconductor substrate 10 can severely disrupt the crystallinity of the semiconductor substrate 10. In this specification, this disruption in crystallinity may be referred to as disorder.

[0110] The entire semiconductor substrate 10 contains oxygen. The oxygen is introduced intentionally or unintentionally during the production of a semiconductor ingot. When hydrogen implanted into the buffer region 20 is diffused by heat treatment or the like, hydrogen (H), vacancies (V), and oxygen (O) combine within the semiconductor substrate 10, forming VOH defects.

[0111] The VOH defects function as donors that supply electrons. In this specification, the VOH defects may be simply referred to as hydrogen donors. By forming hydrogen donors in the semiconductor substrate 10, the buffer region 20 can be formed with a higher concentration than the drift region 18.

[0112] Since there are many hydrogen atoms and lattice defects near the hydrogen ion implantation position, many hydrogen donors are likely to be formed. D The distribution may have a concentration peak 25 near the injection location.

[0113] Forming the concentration peak 25 in the buffer region 20 can prevent the depletion layer spreading from the upper surface 21 from reaching the collector region 22, etc. On the other hand, when hydrogen ions are implanted to form hydrogen donors in the passage region, there are cases where it is not desirable to form a large concentration peak 25 near the implanted position of the hydrogen ions. For example, if a large concentration peak 25 is formed near the drift region 18, the voltage or current waveform may oscillate when the depletion layer reaches the concentration peak 25, for example, when the semiconductor device 100 is turned off.

[0114] In this example, multiple low-concentration hydrogen peaks 125 are formed in the buffer region 20. This makes it possible to form a buffer region 20 with a higher concentration than the bulk donor concentration, while preventing large concentration peaks 25 from being formed near the low-concentration hydrogen peaks 125.

[0115] The buffer region 20 of this example has a flat region 130. The flat region 130 includes a region 131 between the first low-concentration hydrogen peak 125-1 and the second low-concentration hydrogen peak 125-2, and a region where the second low-concentration hydrogen peak 125-2 is provided. The flat region 130 may further include at least a portion of the region where the first low-concentration hydrogen peak 125-1 is provided. Because the high-concentration hydrogen peak 115 is not provided in the flat region 130, no large concentration peak 25 is formed.

[0116] In this example, the first low-concentration hydrogen peak 125-1 is the low-concentration hydrogen peak that is located closest to the upper surface 21 among the multiple low-concentration hydrogen peaks 125 that are continuously arranged in the depth direction. The second low-concentration hydrogen peak 125-2 is the low-concentration hydrogen peak that is located closest to the lower surface 23 among the multiple low-concentration hydrogen peaks 125 that are continuously arranged in the depth direction. One or more low-concentration hydrogen peaks 125 may be formed between the first low-concentration hydrogen peak 125-1 and the second low-concentration hydrogen peak 125-2.

[0117] Region 131 may be a region between the full width at half maximum FWHM1 of the first low-concentration hydrogen peak 125-1 and the full width at half maximum FWHM2 of the second low-concentration hydrogen peak 125-2. Region 131 may be a region between the apex position Z11 of the first low-concentration hydrogen peak 125-1 and the apex position Z12 of the second low-concentration hydrogen peak 125-2.

[0118] The region where the second low-concentration hydrogen peak 125-2 is provided may be a region of the full width at half maximum FWHM2 of the second low-concentration hydrogen peak 125-2, or may be a region between two valleys 124 that sandwich the second low-concentration hydrogen peak 125-2 in the depth direction. H The valley 124-2 is the point where the hydrogen chemical concentration C H is the location where the first low-concentration hydrogen peak 125-1 first reaches a minimum value. The region where the first low-concentration hydrogen peak 125-1 is provided may be a region of the full width at half maximum FWHM1 of the first low-concentration hydrogen peak 125-1.

[0119] The flat region 130 has a doping concentration D D is the bulk donor concentration D b and the doping concentration D D The fluctuation of the doping concentration D in the flat region 130 is ±30% or less. D The average value of D Dave , the maximum value is D Dmax , the minimum value is D Dmin The maximum value D Dmax is the average value D Dave The minimum value D Dmin is the average value D Dave It may be 0.7 times or more.

[0120] The doping concentration profile in the depth direction of the flat region 130 may have one or more concentration peaks 128. The concentration peaks 128 may have a doping concentration D D shows a maximum value. The amplitude of the concentration peaks 128 is smaller than the amplitude of the concentration peaks 25. Each concentration peak 128 corresponds to one of the low-concentration hydrogen peaks 125. In this example, the flat region 130 has a first concentration peak 128-1 corresponding to the first low-concentration hydrogen peak 125-1 and a second concentration peak 128-2 corresponding to the second low-concentration hydrogen peak 125-2. Each concentration peak 128 may be positioned within the full width at half maximum (FWHM) range of the corresponding low-concentration hydrogen peak 125.

[0121] The flat region 130 may also have one or more minimum portions 129. The minimum portions 129 have a doping concentration D D Each minimum point 129 is a point where the hydrogen chemical concentration C H In this example, a minimum portion 129 corresponding to the valley 124-1 is located between the first concentration peak 128-1 and the second concentration peak 128-2.

[0122] The concentration peak 128 has a more gradual change in concentration in the depth direction than the corresponding low-concentration hydrogen peak 125. For example, the doping concentration D DThe gradient of the change in hydrogen chemical concentration C from the second low-concentration hydrogen peak 125-2 to the valley 124-1 is H is smaller than the slope of the change.

[0123] The average doping concentration D in the flat region 130 Dave When calculating the average value, the range of depth positions from the lower surface 23 may be defined as follows: The position of the end of the flat region 130 on the upper surface 21 side for calculating the average value is defined as R21, and the position on the lower surface 23 side is defined as R22. Position R21 may be a position on the upper surface 21 side of position Z21 where the doping concentration has the same value as the doping concentration of the minimum part 129 between the concentration peak 128-1 and the concentration peak 128-2. Position R22 may be a position where the doping concentration at the foot of the concentration peak 25-2 on the upper surface 21 side has the same value as the doping concentration at position Z22 of the concentration peak 128-2. The average value D of the doping concentration in the flat region 130 Dave may be calculated by dividing the integral of the doping concentration from the position R21 to the position R22 by the length between the position R21 and the position R22.

[0124] The doping concentration distribution between the concentration peaks 25-1 and 25-2 has a minimum value D m1 The average value D of the flat region 130 Dave is the minimum value D m1 or less, minimum value D m1 The maximum value D of the flat region 130 Dmax is the minimum value D m1 It may be greater than or equal to the minimum value D m1 or less, minimum value D m1 It can be smaller than

[0125] The peak width of the concentration peak 128 of the doping concentration distribution in the flat region 130 may be larger than the peak width of the corresponding low-concentration hydrogen peak 125 of the hydrogen chemical concentration distribution. The peak width of the concentration peak 128 of the doping concentration distribution in the flat region 130 may be the distance between the minimum part of the concentration peak 128 on the upper surface 21 side and the minimum part on the lower surface 23 side. In the flat region 130, the maximum doping concentration D Dmaxis the minimum value D Dmin In this case, the density of the minimum portion 129 is equal to or greater than the maximum value D Dmax , and the full width at half maximum FWHM of the concentration peak 128 cannot be defined. If the full width at half maximum FWHM of the concentration peak 128 can be defined, the full width at half maximum FWHM may be used as the peak width of the concentration peak 128.

[0126] In addition, the hydrogen chemical concentration C of the low-concentration hydrogen peak 125 H The highest of these is C Hmax The hydrogen chemical concentration C in the valley 124 between the low-concentration hydrogen peaks 125 is H The lowest of these is C Hmin The hydrogen chemical concentration C Hmin hydrogen chemical concentration C Hmax Ratio C Hmax / C Hmin Similarly, the doping concentration D in the flat region 130 is D The minimum value of D Dmin Maximum value D for Dmax Ratio D Dmax / D Dmin is set as the fluctuation ratio R2. The fluctuation ratio R2 is smaller than the fluctuation ratio R1. The fluctuation ratio R2 may be equal to or less than half of the fluctuation ratio R1, or equal to or less than ¼, or equal to or less than 1 / 10.

[0127] The semiconductor substrate 10 of this example has a relatively low oxygen chemical concentration C OX In addition, the hydrogen chemical concentration is relatively low in the region where the low-concentration hydrogen peak 125 is located. Therefore, the concentration of the hydrogen donor in the region where the low-concentration hydrogen peak 125 is located is higher than the oxygen chemical concentration C OX This results in a smaller fluctuation due to the influence of the low-concentration hydrogen peak 125. b and doping concentration D D A flat region 130 with small fluctuations can be formed.

[0128] Hydrogen donor concentration N VOH is the vacancy concentration N Vand the oxygen chemical concentration C of the semiconductor substrate 10 OX , oxygen chemical concentration C OX Actually, N VOH Using the oxygen contribution ratio ξ, which is the ratio of the oxygen that contributes to the production of N VOH =N V +ξC OX ... (Formula 1) The oxygen contribution ratio ξ is 1×10 -5 That's it, 1×10 -3 The vacancy concentration N V is 1 x 10 12 ( / cm 3 ) or more 1×10 14 ( / cm 3 The oxygen contribution ratio ξ may be equal to or less than the dose D H (ions / cm 2 ), it may be expressed as the following Equation 2: ξ=aD H b ... (Formula 2) where a is 1×10 -11 That's it, 1×10 -10 b can be 4×10 -1 That's it, 6 x 10 -1 It may be the following:

[0129] The semiconductor substrate 10 of this example has a relatively low carbon chemical concentration C C The hydrogen donor concentration N VOH is the vacancy concentration N V and the oxygen chemical concentration C of the semiconductor substrate 10 OX , oxygen chemical concentration C OX Actually, N VOH the oxygen contribution ratio ξ, which is the ratio of the contribution to the generation of C , carbon chemical concentration C C Actually, N VOH This can be expressed by the following formula 2 using the carbon contribution rate η, which is the rate at which carbon contributes to the production of N VOH =N V +ξC OX +ηC C... (Formula 2) Oxygen contribution ratio ξ and vacancy concentration N V may be in the above-mentioned range. The carbon contribution rate η may be a value of 0.01% to 10% (that is, 0.0001 or more and 0.1 or less).

[0130] Each concentration peak 128 may be located closer to the lower surface 23 of the semiconductor substrate 10 than the corresponding low-concentration hydrogen peak 125. In this example, the first concentration peak 128-1 is located closer to the lower surface 23 than the first low-concentration hydrogen peak 125-1, and the second concentration peak 128-2 is located closer to the lower surface 23 than the second low-concentration hydrogen peak 125-2. The depth position of the first concentration peak 128-1 is determined by the doping concentration D D is the depth position Z21 where the doping concentration D D is the depth position Z22 where the maximum value is shown.

[0131] The doping concentration D shown in Figure 4B D The distribution of carrier concentration measured by SR method. In this example, the hydrogen chemical concentration C at the low hydrogen peak 125 HThe hydrogen ion implantation depths Z11 and Z12 are relatively dense. Therefore, many lattice defects that do not bond to hydrogen may remain near the depths Z11 and Z12. The presence of many lattice defects may result in a low carrier concentration near the depths Z11 and Z12. Furthermore, the slope of the bottom-side skirt 127 of each hydrogen peak is smaller than that of the top-side skirt 126. Therefore, more hydrogen ions are present on the bottom surface 23 side of the depths Z11 and Z12 than on the top surface 21 side. Relatively more hydrogen donors are likely to be formed on the bottom surface 23 side of the depths Z11 and Z12. Therefore, the concentration peak 128 may be located closer to the bottom surface 23 than the low-concentration hydrogen peak 125. In the flat region 130, the carrier concentration measured by the SR method may differ by approximately ±10% between adjacent measurement points, and the measured carrier concentration may appear to vary from measurement point to measurement point. In such a case, as an example, the carrier concentration at the measurement point and the carrier concentrations at the measurement points before and after that may be averaged to obtain a total of three measured values, and the average value may be used as the carrier concentration at that measurement point.Furthermore, the average value of measured values at multiple points before and after the measurement point, such as two points before and two points after the measurement point, may also be used.

[0132] In the depth direction of the semiconductor substrate 10, the length of the flat region 130 may be less than half the length of the buffer region 20, or may be more than half the length of the buffer region 20. The length of the flat region 130 can be adjusted by the number, spacing, etc. of the low-concentration hydrogen peaks 125.

[0133] The average doping concentration D of the flat region 130 Dave is the oxygen chemical concentration C of the semiconductor substrate 10 OX The average value D may be 0.01% or more and 3% or less of the above. Dave is the oxygen chemical concentration C OX The average value D may be 0.05% or more, or may be 0.1% or more. Dave is the oxygen chemical concentration C OX The average doping concentration D of the flat region 130 may be 2% or less, or may be 1% or less. Davedepends on the dose of hydrogen ions at the low hydrogen concentration peak 125. By implanting hydrogen ions so as to satisfy the above-mentioned conditions, the flat region 130 can be easily formed.

[0134] Oxygen chemical concentration C of the semiconductor substrate 10 OX may be 10 times or more the hydrogen chemical concentration of the first low-concentration hydrogen peak 125-1. In other words, the hydrogen chemical concentration of the first low-concentration hydrogen peak 125-1 is 10 times or more the oxygen chemical concentration C OX This allows the doping concentration D D Oxygen chemical concentration C OX In this example, the oxygen chemical concentration C OX The oxygen chemical concentration C of the semiconductor substrate 10 may be compared with the hydrogen chemical concentration C OX may be 20 times or more, 50 times or more, or 100 times or more the hydrogen chemical concentration of the first low-concentration hydrogen peak 125-1. The other low-concentration hydrogen peaks 125 are similar to the first low-concentration hydrogen peak 125-1.

[0135] The distance between the first low-concentration hydrogen peak 125-1 and the second low-concentration hydrogen peak 125-2, i.e., Z11-Z12 (μm), is determined by the oxygen chemical concentration C OX (atoms / cm 3 3 / 10 of 16 (μm / (atoms / cm 3 )) times or less. In this example, the interval Z11-Z12 is the interval between adjacent low-concentration hydrogen peaks 125 in the depth direction. For example, the oxygen chemical concentration C OX is 1.0×10 17 atoms / cm 3 In this case, the interval Z11-Z12 is 30 μm or less. The interval Z11-Z12 (μm) is determined by the oxygen chemical concentration C OX (atoms / cm 3 1 / 10 of 16 (μm / (atoms / cm 3 )) may be less than double, 5 / 10 17(μm / (atoms / cm 3 )) times or less.

[0136] Hydrogen chemical concentration C of the first low-concentration hydrogen peak 125-1 H is 1.0×10 16 atoms / cm 3 The hydrogen chemical concentration C of the other low-concentration hydrogen peak 125 may be less than or equal to H Also 1.0 x 10 16 atoms / cm 3 The interval Z11-Z12 may be 100 μm or less, 50 μm or less, 20 μm or less, or 10 μm or less. If the interval Z11-Z12 between adjacent low-concentration hydrogen peaks 125 is too large, the hydrogen chemical concentration C H becomes too low, resulting in a low doping concentration in the minimum portion 129. The distance Z11-Z12 may be 5 μm or more.

[0137] Doping concentration D of the flat region 130 D is the bulk donor concentration D b The doping concentration D of the flat region 130 may be two or more times greater than the D is the minimum value D Dmin Using the average value D Dave The doping concentration D of the flat region 130 may be D is the bulk donor concentration D b It may be 5 times or more, or 10 times or more.

[0138] Doping concentration D of the flat region 130 D But 0.7×10 13 / cm 3 Minimum value D Dmin Using the average value D Dave The doping concentration D of the flat region 130 may be D is 1.0 x 10 14 / cm 3 The doping concentration D of the flat region 130 may be equal to or greater than 1000 kJ / s. D is 1.0 x 10 15 / cm 3may be less than or equal to 3.0 x 10 14 / cm 3 It may be the following:

[0139] Fig. 5A is a diagram showing another example of the doping concentration distribution in the depth direction at the position of the FF line in Fig. 3. It differs from the example in Fig. 4A in that there is one concentration peak 25. The distribution in other parts is similar to the example in Fig. 4A.

[0140] FIG. 5B shows the doping concentration D in the buffer region 20 of FIG. D and hydrogen chemical concentration C H 4B is a diagram showing an example of the distribution in the depth direction. In this example, the concentration peak 25-2 in the example of FIG. 4B is the concentration peak 128-3 in the flat region 130. In this example, the second high-concentration hydrogen peak 115-2 in the example of FIG. 4B is the third low-concentration hydrogen peak 125-3. The other distributions are the same as in the example of FIG. 4B.

[0141] By setting the hydrogen chemical concentration of the third low-concentration hydrogen peak 125-3 to the same concentration as the second low-concentration hydrogen peak 125-2, the doping concentration of the concentration peak 128-3 is set to the same concentration peak 128-2. The hydrogen chemical concentration of the third low-concentration hydrogen peak 125-3 may be higher than the second low-concentration hydrogen peak 125-2 but lower than the high-concentration hydrogen peak 115-1. The doping concentration of the concentration peak 128-3 may be higher than the concentration peak 128-2 but lower than the concentration peak 128-1.

[0142] In this example, when calculating the average value of the doping concentration in the flat region 130, the position of the end of the flat region 130 on the lower surface 23 side may be the position R22 described in FIG. 4B or may be the position R23 shown in FIG. 5B. Position R23 is the position where the doping concentration at the foot of the concentration peak 25-1 on the upper surface 21 side is the same as the doping concentration at position Z23 of the concentration peak 128-3. In this example, the position of the end of the flat region 130 on the upper surface 21 side for calculating the average value may be the same as in the example of FIG. 4B. The average value D of the doping concentration in the flat region 130 when the flat region 130 is from position R23 to position R21 is Dave2may be calculated by dividing the integral of the doping concentration from the position R21 to the position R23 by the length between the position R21 and the position R23. In another example, as in FIG. 4B , the position of the end of the flat region 130 on the lower surface 23 side is set to R22, and the average value D of the doping concentration in the flat region 130 is calculated by Dave may be calculated.

[0143] The doping concentration distribution between the concentration peak 25-1 and the concentration peak 128-3 may have a minimum value Dm1. Dave2 is the minimum value D m1 or less, minimum value D m1 The maximum value D of the flat region 130 Dmax is the minimum value D m1 or less, minimum value D m1 The minimum value D of the flat region 130 Dmin is the minimum value D m1 or less, minimum value D m1 It can be smaller than

[0144] 6 is a diagram showing the doping concentration distribution of the buffer region 20 in the example and the comparative example. The example has the same doping concentration distribution as that shown in FIG. 4B. In the example, the dose of hydrogen ions at the depth position Z11 is 1.0×10 12 ions / cm 2 The dose of hydrogen ions at the depth position Z12 is 5.0 × 10 11 ions / cm 2 The dose of hydrogen ions at the depth position Z32 is 4.0 × 10 12 ions / cm 2 The dose of hydrogen ions at the depth position Z31 is 5.0 × 10 14 ions / cm 2 In the example, no large peaks of doping concentration were observed near the depth positions Z11 and Z12.

[0145] In Comparative Example 1, the dose of hydrogen ions at the depth position Z11 is 2.0 × 10 12 ions / cm2 and the dose of hydrogen ions at the depth position Z12 is 1.0 × 10 12 ions / cm 2 The dose of hydrogen ions at the depth position Z32 is 4.0 × 10 12 ions / cm 2 The dose of hydrogen ions at the depth position Z31 is 5.0 × 10 14 ions / cm 2 In Comparative Example 1, concentration peaks 25 of the doping concentration were observed near depth positions Z11 and Z12. In particular, a relatively large concentration peak 25 was present at depth position Z11.

[0146] In Comparative Example 2, the dose of hydrogen ions at the depth position Z11 was 3.0 × 10 12 ions / cm 2 The dose of hydrogen ions at the depth position Z12 is 1.5 × 10 12 ions / cm 2 and the dose of hydrogen ions at the depth position Z32 is 1.0 × 10 13 ions / cm 2 The dose of hydrogen ions at the depth position Z31 is 3.0 × 10 14 ions / cm 2 In Comparative Example 2, a concentration peak 25 of the doping concentration was observed near the depth positions Z11 and Z12. As shown in FIG. 6, the dose of hydrogen ions was 1.0×10 12 ions / cm 2 By setting the concentration peak 25 of the doping concentration as follows, it was possible to suppress the formation of the concentration peak 25 of the doping concentration.

[0147] FIG. 7 is a diagram showing the doping concentration distribution of the buffer region 20 in the example and the comparative example. The example has the same doping concentration distribution as that shown in FIG. 6. In comparative example 3, the dose of hydrogen ions at each position is the same as that in the example. However, the implantation position of hydrogen ions in comparative example 3 is different from that in the example. Also, the oxygen chemical concentration C OX is 1.0×10 17 atoms / cm3 In contrast, the oxygen chemical concentration C of the semiconductor substrate of Comparative Example 3 OX is 1.0 x 10 16 atoms / cm 3 The semiconductor substrate of the example is an MCZ substrate, and the semiconductor substrate of Comparative Example 3 is an FZ substrate.

[0148] As shown in Figure 7, the dose of hydrogen ions was 1.0 × 10 12 ions / cm 2 However, in Comparative Example 3, in which the oxygen chemical concentration of the semiconductor substrate is low, a concentration peak 25 of the doping concentration was formed. On the other hand, in the Example, the oxygen chemical concentration C OX to 1.0 x 10 17 atoms / cm 3 By doing so, it was possible to suppress the formation of the concentration peak 25 of the doping concentration.

[0149] 8 is a diagram showing another example of the doping concentration distribution in the depth direction at the position of the FF line in FIG. 3. In this example, the hydrogen chemical concentration C H and doping concentration D D The distribution of the ions differs from that of the example in Fig. 4A. The other structures are the same as those of the example in Fig. 4A. The length of the flat region 130 in the depth direction is half or more of that of the buffer region 20.

[0150] In this example, Zcb is the central position in the depth direction of the buffer region 20. In the buffer region 20, the portion closer to the lower surface 23 than the central position Zcb is called a lower surface side region 133, and the portion closer to the upper surface 21 is called an upper surface side region 132.

[0151] The buffer region 20 has a plurality of low-concentration hydrogen peaks 125, including a first low-concentration hydrogen peak 125-1 and a second low-concentration hydrogen peak 125-2. In this example, the number of low-concentration hydrogen peaks 125 arranged in the upper surface side region 132 is greater than the number of low-concentration hydrogen peaks 125 arranged in the lower surface side region 133. In the example of FIG. 8, the first low-concentration hydrogen peak 125-1, the second low-concentration hydrogen peak 125-2, and the third low-concentration hydrogen peak 125-3 are arranged in the upper surface side region 132. No low-concentration hydrogen peak 125 may be arranged in the lower surface side region 133, and one or more low-concentration hydrogen peaks 125 may be arranged therein, as indicated by the dashed lines.

[0152] In this example, no high-concentration hydrogen peak 115 is located in the upper surface side region 132. One or more high-concentration hydrogen peaks 115 may be located in the lower surface side region 133. This configuration makes it possible to flatten the doping concentration in the upper surface side region 132. In addition, the concentration peak 25 in the lower surface side region 133 can prevent the depletion layer from reaching the collector region 22, etc.

[0153] The flat region 130 may be provided in 80% or more of the upper surface side region 132, or may be provided in the entire region. The flat region 130 may also be provided in a part of the lower surface side region 133. For example, in the lower surface side region 133, the flat region 130 may be located closer to the upper surface 21 than the concentration peak 25 located closest to the upper surface 21.

[0154] The flat region 130 may be formed beyond the central position Zc of the semiconductor substrate 10 up to a region on the upper surface 21 side. The flat region 130 may be formed up to the accumulation region 16. In this case, the low-concentration hydrogen peak 125 may be located within the accumulation region 16.

[0155] Of the regions obtained by dividing the upper surface side region 132 into two equal regions in the depth direction, the region on the upper surface 21 side is defined as a tip region 134. Two or more low-concentration hydrogen peaks 125 may be arranged in the tip region 134. By implanting hydrogen ions in a dispersed manner at multiple depth positions in the tip region 134, the doping concentration D D The distribution of hydrogen ions can be flattened. In addition, the amount of hydrogen ions passing from the lower surface 23 to the tip region 134 is secured, making it easier to form lattice defects. This allows the flat region 130 to have a high concentration. In the upper surface side region 132, the number of low-concentration hydrogen peaks 125 located in the tip region 134 may be greater than the number of low-concentration hydrogen peaks 125 located in regions other than the tip region 134.

[0156] 9 is an enlarged view of adjacently arranged low-concentration hydrogen peaks 125. The low-concentration hydrogen peaks 125 in this example may be arranged in the tip region 134, the upper surface region 132, or the buffer region 20 in FIG.

[0157] The hydrogen chemical concentrations P11, P12, and P13 at the apex of each low-concentration hydrogen peak 125 may be the same or different. In the example of Fig. 9, the hydrogen chemical concentrations P11, P12, and P13 are the same.

[0158] The intervals Z11-Z13 and Z13-Z12 between the apexes of the low-concentration hydrogen peaks 125 may be the same or different. In the example of Fig. 9, the intervals Z11-Z13 and Z13-Z12 are the same.

[0159] 10 is a diagram showing another example of adjacently arranged low-concentration hydrogen peaks 125. The low-concentration hydrogen peaks 125 in this example may be arranged in the tip region 134, the upper surface region 132, or the buffer region 20 in FIG.

[0160] In this example, the hydrogen chemical concentration P11 of the first low-concentration hydrogen peak 125-1, which is located closest to the upper surface 21, is greater than the hydrogen chemical concentrations of the other low-concentration hydrogen peaks 125. The hydrogen chemical concentration P12 of the second low-concentration hydrogen peak 125-2, which is located closest to the lower surface 23, is less than the hydrogen chemical concentrations of the other low-concentration hydrogen peaks 125. The hydrogen chemical concentration of each low-concentration hydrogen peak 125 may be greater the closer it is to the upper surface 21.

[0161] 11 is a diagram showing another example of adjacently arranged low-concentration hydrogen peaks 125. The low-concentration hydrogen peaks 125 in this example may be arranged in the tip region 134, the upper surface region 132, or the buffer region 20 in FIG.

[0162] In this example, the hydrogen chemical concentration P11 of the first low-concentration hydrogen peak 125-1, which is located closest to the upper surface 21, is smaller than the hydrogen chemical concentrations of the other low-concentration hydrogen peaks 125. The hydrogen chemical concentration P12 of the second low-concentration hydrogen peak 125-2, which is located closest to the lower surface 23, is larger than the hydrogen chemical concentrations of the other low-concentration hydrogen peaks 125. The hydrogen chemical concentration of each low-concentration hydrogen peak 125 may be smaller the closer it is to the upper surface 21.

[0163] 10 and 11, the intervals between the low-concentration hydrogen peaks 125 may be greater as they approach the top surface 21. The intervals between the low-concentration hydrogen peaks 125 may be smaller as they approach the top surface 21.

[0164] 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 and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0165] It should be noted that the order of execution of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and that the processes can be performed in any order unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, this does not mean that the processes must be performed in this order. [Explanation of symbols]

[0166] 10 semiconductor substrate, 11 well region, 12 emitter region, 14 base region, 15 contact region, 16 accumulation region, 18 drift region, 20 buffer region, 21 upper surface, 22 collector region, 23 lower surface, 24 collector electrode, 25 concentration peak, 29 straight line portion, 30 dummy trench portion, 31 tip portion, 32 dummy insulating film, 34 dummy conductive portion, 38 interlayer insulating film, 39 straight line portion, 40 gate trench portion, 41 tip portion, 42 gate insulating film, 44 gate conductive portion, 52 emitter electrode, 54 contact hole, 60, 61... mesa portion, 70... transistor portion, 80... diode portion, 81... extension region, 82... cathode region, 90... edge termination structure portion, 100... semiconductor device, 101... peripheral gate wiring, 102... active side gate wiring, 115... high-concentration hydrogen peak, 124... valley portion, 125... low-concentration hydrogen peak, 126... upper surface foot, 127... lower surface foot, 128... concentration peak, 129... minimum portion, 130... flat region, 131... region, 132... upper surface region, 133... lower surface region, 134... tip region, 160... active portion, 162... edge, 164... gate pad

Claims

1. A semiconductor substrate having an upper surface and a lower surface, the semiconductor substrate including bulk donors and oxygen; a buffer region at least partially disposed on the lower surface side of the semiconductor substrate, the buffer region having a doping concentration higher than a bulk donor concentration; The buffer area is a plurality of low-concentration hydrogen peaks in the hydrogen chemical concentration distribution; a high-concentration hydrogen peak that is located closer to the lower surface than the plurality of low-concentration hydrogen peaks and has a higher hydrogen chemical concentration than the plurality of low-concentration hydrogen peaks; Including, for at least one low-concentration hydrogen peak among the plurality of low-concentration hydrogen peaks, a depth position of a concentration peak of a corresponding doping concentration distribution is located closer to the lower surface than a depth position of the low-concentration hydrogen peak, The buffer area is the region including the plurality of low-concentration hydrogen peaks and the region between the plurality of low-concentration hydrogen peaks, and further including a flat region in which, for at least one low-concentration hydrogen peak among the plurality of low-concentration hydrogen peaks, the width of the concentration peak of the corresponding doping concentration distribution is greater than the width of the low-concentration hydrogen peak; Semiconductor device.

2. A semiconductor substrate having an upper surface and a lower surface, the semiconductor substrate including bulk donors and oxygen; a buffer region at least partially disposed on the lower surface side of the semiconductor substrate, the buffer region having a doping concentration higher than a bulk donor concentration; The buffer area is a plurality of low-concentration hydrogen peaks in the hydrogen chemical concentration distribution; a high-concentration hydrogen peak that is located closer to the lower surface than the plurality of low-concentration hydrogen peaks and has a higher hydrogen chemical concentration than the plurality of low-concentration hydrogen peaks; Including, for at least one low-concentration hydrogen peak among the plurality of low-concentration hydrogen peaks, a depth position of a concentration peak of a corresponding doping concentration distribution is located closer to the lower surface than a depth position of the low-concentration hydrogen peak, The hydrogen chemical concentration of the low-concentration hydrogen peak is 1×10 １６ / cm ３ is Semiconductor device.

3. A semiconductor substrate having an upper surface and a lower surface, the semiconductor substrate including bulk donors and oxygen; a buffer region at least partially disposed on the lower surface side of the semiconductor substrate, the buffer region having a doping concentration higher than a bulk donor concentration; The buffer area is a plurality of low-concentration hydrogen peaks in the hydrogen chemical concentration distribution; a high-concentration hydrogen peak that is located closer to the lower surface than the plurality of low-concentration hydrogen peaks and has a higher hydrogen chemical concentration than the plurality of low-concentration hydrogen peaks; Including, for at least one low-concentration hydrogen peak among the plurality of low-concentration hydrogen peaks, a depth position of a concentration peak of a corresponding doping concentration distribution is located closer to the lower surface than a depth position of the low-concentration hydrogen peak, the buffer region has a plurality of concentration peaks in the doping concentration distribution; Each of the concentration peaks corresponds to one of the low-concentration hydrogen peaks, At least two of the concentration peaks are arranged adjacent to each other. Semiconductor device.

4. Among the plurality of low-concentration hydrogen peaks, for the low-concentration hydrogen peak arranged closest to the upper surface, the depth position of the concentration peak of the corresponding doping concentration distribution is arranged closer to the lower surface than the depth position of the low-concentration hydrogen peak. The semiconductor device according to claim 1 .

5. For all of the low-concentration hydrogen peaks among the plurality of low-concentration hydrogen peaks, the depth position of the concentration peak of the corresponding doping concentration distribution is located closer to the lower surface than the depth position of the low-concentration hydrogen peak. The semiconductor device according to claim 1 .

6. The buffer area is the region including the plurality of low-concentration hydrogen peaks and the region between the plurality of low-concentration hydrogen peaks, and further including a flat region in which, for at least one low-concentration hydrogen peak among the plurality of low-concentration hydrogen peaks, the width of the concentration peak of the corresponding doping concentration distribution is greater than the width of the low-concentration hydrogen peak; 4. The semiconductor device according to claim 2.

7. For all of the low-concentration hydrogen peaks among the plurality of low-concentration hydrogen peaks in the flat region, the width of the concentration peak of the corresponding doping concentration distribution is greater than the width of the low-concentration hydrogen peak. The semiconductor device according to claim 1 .

8. The plurality of low concentration hydrogen peaks are a first low-concentration hydrogen peak; a second low-concentration hydrogen peak located closer to the lower surface than the first low-concentration hydrogen peak; Including, The flat region is a region between the first low-concentration hydrogen peak and the second low-concentration hydrogen peak; a region where the second low-concentration hydrogen peak is provided; Contains The semiconductor device according to claim 1 or 7.

9. The flat region has a doping concentration higher than the bulk donor concentration.

9. The semiconductor device according to claim 1, 7 or 8.

10. The flat region is The doping concentration varies by ±30% or less; The variation rate of the doping concentration is smaller than the variation rate of the hydrogen chemical concentration. The semiconductor device according to claim 1 or 7 to 9.

11. a doping concentration distribution in the depth direction of the flat region has a concentration peak corresponding to the second low-concentration hydrogen peak; The concentration peak changes more slowly than the second low hydrogen concentration peak. The semiconductor device according to claim 8 .

12. The concentration peak is located closer to the lower surface of the semiconductor substrate than the second low-concentration hydrogen peak. The semiconductor device according to claim 11.

13. In the depth direction, the length of the flat region is equal to or greater than half the length of the buffer region. The semiconductor device according to claim 1 or any one of claims 7 to 12.

14. The average value of the doping concentration in the flat region is 0.01% or more and 3% or less of the oxygen chemical concentration in the semiconductor substrate. The semiconductor device according to claim 1 or any one of claims 7 to 13.

15. The oxygen chemical concentration of the semiconductor substrate is 10 times or more the hydrogen chemical concentration of the plurality of low-concentration hydrogen peaks. The semiconductor device according to claim 1 .

16. The interval (μm) between the first low-concentration hydrogen peak and the second low-concentration hydrogen peak is determined based on the oxygen chemical concentration (atoms / cm ３ ) 3 / 10 １６ (μm / (atoms / cm ３ )) times less 13. The semiconductor device according to claim 8, 11 or 12.

17. The hydrogen chemical concentration of the first low-concentration hydrogen peak is 1.0×10 １６ atoms / cm ３ is as follows: The distance between the first low-concentration hydrogen peak and the second low-concentration hydrogen peak is 100 μm or less.

13. The semiconductor device according to claim 8, 11 or 12.

18. the buffer region has a lower surface region located on the lower side of the center of the buffer region and an upper surface region located on the upper side of the center of the buffer region, The number of the low-concentration hydrogen peaks arranged in the upper surface region is greater than the number of the low-concentration hydrogen peaks arranged in the lower surface region. The semiconductor device according to claim 1 .

19. The hydrogen chemical concentration of the low-concentration hydrogen peak is 1×10 16 / cm 3 or less.

4. The semiconductor device according to claim 1.

20. The doping concentration of the flat region is at least twice the bulk donor concentration. The semiconductor device according to claim 1 or any one of claims 7 to 14.

21. The doping concentration of the flat region is 0.7×10 １３ / cm ３ That's all The semiconductor device according to claim 1 or any one of claims 7 to 14.

22. each of the plurality of low-concentration hydrogen peaks has a lower base extending from the peak toward the lower surface of the semiconductor substrate and an upper base extending from the peak toward the upper surface of the semiconductor substrate; The upper tail has a steeper decrease in hydrogen chemical concentration than the lower tail.

22. The semiconductor device according to claim 1.

23. The oxygen chemical concentration of the semiconductor substrate is 1.0×10 １７ atoms / cm ３ That's all 23. The semiconductor device according to claim 1 or any one of claims 3 to 22.

24. The hydrogen ion dose of the first low-concentration hydrogen peak is 1.0×10 １２ ions / cm ２ is 13. The semiconductor device according to claim 8, 11 or 12.

25. The hydrogen ion dose of the second low hydrogen concentration peak is 1.0×10 １２ ions / cm ２ is 13. The semiconductor device according to claim 8, 11 or 12.

26. the average value of the doping concentration in the flat region is equal to or less than the minimum value of the doping concentration between the second low-concentration hydrogen peak and the high-concentration hydrogen peak; 13. The semiconductor device according to claim 8, 11 or 12.

27. the buffer region has a third low-concentration hydrogen peak located closer to the upper surface than the high-concentration hydrogen peak and closer to the lower surface than the second low-concentration hydrogen peak; the plateau region includes the third low-concentration hydrogen peak, the average value of the doping concentration in the flat region is equal to or less than the minimum value of the doping concentration between the third low-concentration hydrogen peak and the high-concentration hydrogen peak; 13. The semiconductor device according to claim 8, 11 or 12.

28. In the flat region, the fluctuation rate of the doping concentration is equal to or less than half of the fluctuation rate of the hydrogen chemical concentration. The semiconductor device according to claim 1 or any one of claims 7 to 14.

29. The flat region is formed from a central position in the depth direction of the semiconductor substrate to the upper surface side. The semiconductor device according to claim 1 or any one of claims 7 to 14.

30. The semiconductor substrate is an MCZ substrate.

30. The semiconductor device of claim 1.

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