Semiconductor device and method for manufacturing the same

Abstract

To provide a semiconductor device and a manufacturing method for the semiconductor device, in which the donor concentration of a semiconductor substrate is adjusted with high accuracy.SOLUTION: A semiconductor device 100 includes a semiconductor substrate 10 having an upper surface 21 and a lower surface 23 and containing oxygen, a first peak 133 disposed on the lower surface side of the semiconductor substrate and having a hydrogen chemical concentration, and a flat part between the first peak and a second peak 141, which is disposed on the upper surface side of the semiconductor substrate relative to the first peak and contains a hydrogen donor and in which the donor concentration in a depth direction of the semiconductor substrate is substantially flat. The oxygen contribution ratio expressing the ratio of the oxygen chemical concentration contributing to the generation of the hydrogen donor to the oxygen chemical concentration of oxygen is 1×10-5 or more and 7×10-4 or less. In the flat part, the concentration of oxygen contributing to the generation of the hydrogen donor is lower than the hydrogen chemical concentration and the hydrogen donor concentration in the flat part is 2×1012 / cm3 or more and 5×1014 / cm3 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] BACKGROUND ART Conventionally, a technique is known in which hydrogen is implanted to a predetermined depth in a semiconductor substrate and diffused to form donors, thereby adjusting the substrate resistance (for example, Patent Document 1). Patent Document 1: U.S. Patent Application Publication No. 2018 / 0019306 Problem to be Solved

[0003] It is preferable that the donor concentration of the semiconductor substrate be adjusted with precision.

[0004] In order to solve the above problems, in one aspect of the present invention, A donor concentration distribution in a depth direction of a semiconductor substrate includes a first peak located on an upper surface side of the semiconductor substrate, a second peak located on a lower surface side of the semiconductor substrate in the donor concentration distribution, and a flat portion located in a predetermined region including a central depth position of the semiconductor substrate between the first peak and the second peak, the donor concentration being higher than a bulk donor concentration of the semiconductor substrate and the donor concentration distribution being flat, and an oxygen chemical concentration between the first peak and the second peak is 3×10 15 atoms / cm 3 That's it, 2 x 10 18 atoms / cm 3 The following semiconductor device is provided. In another aspect of the invention, In a donor concentration distribution in a depth direction of a semiconductor substrate, a first peak is located on an upper surface side of the semiconductor substrate, a second peak is located on a lower surface side of the semiconductor substrate in the donor concentration distribution, and a flat portion is provided in a predetermined region between the first peak and the second peak, the donor concentration is higher than a bulk donor concentration of the semiconductor substrate, and the donor concentration distribution is flat, and an oxygen chemical concentration between the first peak and the second peak is 3×10 15 atoms / cm 3 That's it, 2 x 10 18 atoms / cm 3 and the carbon chemical concentration of the flat portion is 1×10 13 atoms / cm 3 That's it, 1 x 10 16 atoms / cm 3 In another aspect of the present invention, there is provided a semiconductor device comprising: Provided is a semiconductor device having an upper surface and a lower surface, the semiconductor substrate containing oxygen. The semiconductor device may have a first peak of hydrogen chemical concentration located on the lower surface side of the semiconductor substrate. The semiconductor device may have a flat portion located on the upper surface side of the semiconductor substrate relative to the first peak, containing hydrogen donors, and having a substantially (almost) flat donor concentration distribution in the depth direction of the semiconductor substrate. An oxygen contribution ratio, which indicates the proportion of the oxygen chemical concentration that contributes to generating hydrogen donors in the oxygen chemical concentration of oxygen, is 1×10 -5 That's it, 7 x 10-4 The concentration of oxygen contributing to the generation of hydrogen donors in the flat portion may be lower than the hydrogen chemical concentration. The hydrogen donor concentration in the flat portion may be 1×10 or less. 12 / cm 3 That's it, 5 x 10 14 / cm 3 It may be the following:

[0005] Oxygen contribution is 5 x 10 -4 It may be the following:

[0006] Oxygen contribution is 1×10 -4 It may be more than that.

[0007] The semiconductor substrate may include bulk donors, and the donor concentration in the flat portion may be higher than the bulk donor concentration.

[0008] The semiconductor device may have a second peak of hydrogen or helium chemical concentration located on the upper surface side of the semiconductor substrate. The flat portion may be located on the lower surface side of the semiconductor substrate relative to the second peak. A hydrogen contribution ratio, which indicates the proportion of the hydrogen chemical concentration that contributes to generating hydrogen donors, may be 0.001 or more and 0.3 or less. The vacancy concentration in the flat portion may be 1×10 11 / cm 3 That's it, 1 x 10 14 / cm 3 It may be the following:

[0009] The hydrogen chemical concentration of the first peak may be higher than the hydrogen chemical concentration of the second peak.

[0010] The oxygen chemical concentration at the plateau is 1×10 17 atoms / cm 3 It may be more than that.

[0011] The carbon chemical concentration in the flat area is 1×10 13 atoms / cm 3 That's it, 1 x 10 16 atoms / cm 3 It may be the following:

[0012] The first hydrogen donor concentration may be the sum of the oxygen chemical concentration in the plateau portion multiplied by the oxygen contribution and the vacancy concentration in the plateau portion. The second hydrogen donor concentration may be the difference between the donor concentration in the plateau portion and the bulk donor concentration. The ratio of the first hydrogen donor concentration to the second hydrogen donor concentration may be 0.1 or more and 10 or less.

[0013] A second aspect of the present invention provides a semiconductor device including a semiconductor substrate having an upper surface and a lower surface and containing oxygen. The semiconductor device may include a first hydrogen chemical concentration peak located on the lower surface side of the semiconductor substrate. The semiconductor device may include a flat portion located on the upper surface side of the semiconductor substrate relative to the first peak, containing hydrogen donors, and having a substantially flat donor concentration distribution in the depth direction of the semiconductor substrate. The semiconductor substrate may include bulk donors. The donor concentration in the flat portion may be higher than the bulk donor concentration. A first hydrogen donor concentration value may be the sum of a value obtained by multiplying the oxygen chemical concentration in the flat portion by an oxygen contribution ratio indicating the proportion of the oxygen chemical concentration that contributes to generating hydrogen donors in the oxygen chemical concentration of oxygen and the vacancy concentration in the flat portion. A second hydrogen donor concentration value may be the difference obtained by subtracting the bulk donor concentration from the donor concentration in the flat portion. A ratio of the first hydrogen donor concentration value to the second hydrogen donor concentration value may be 0.1 or more and 10 or less.

[0014] A third aspect of the present invention provides a semiconductor device including a semiconductor substrate having an upper surface and a lower surface and containing oxygen and carbon. The semiconductor device may include a first peak of hydrogen chemical concentration located on the lower surface side of the semiconductor substrate. The semiconductor device may include a flat portion located on the upper surface side of the semiconductor substrate relative to the first peak, containing hydrogen donors, and having a substantially flat donor concentration distribution in the depth direction of the semiconductor substrate. The semiconductor substrate may include bulk donors. The donor concentration in the flat portion may be higher than the bulk donor concentration. A third value of the hydrogen donor concentration may be the sum of a value obtained by multiplying the oxygen chemical concentration in the flat portion by an oxygen contribution ratio indicating the proportion of the oxygen chemical concentration that contributes to generating hydrogen donors in the oxygen chemical concentration of oxygen, a value obtained by multiplying the carbon chemical concentration in the flat portion by a carbon contribution ratio indicating the proportion of the carbon chemical concentration that contributes to generating hydrogen donors in the carbon chemical concentration of carbon, and the vacancy concentration in the flat portion. A second value of the hydrogen donor concentration may be the difference obtained by subtracting the bulk donor concentration from the donor concentration in the flat portion. The ratio of the third value of the hydrogen donor concentration to the second value of the hydrogen donor concentration may be 0.1 or more and 10 or less.

[0015] A fourth aspect of the present invention provides a method for manufacturing a semiconductor device. The manufacturing method may include a concentration measurement step of measuring an oxygen chemical concentration of a semiconductor substrate having an upper surface and a lower surface. The manufacturing method may include a particle implantation step of implanting a charged particle beam from the lower surface of the semiconductor substrate so as to pass through at least half of the thickness of the semiconductor substrate in the depth direction. The manufacturing method may include a heat treatment step of heat treating the semiconductor substrate after implanting the charged particle beam. At least one of the injection conditions of the charged particle beam in the particle implantation step and the heat treatment conditions in the heat treatment step may be adjusted according to the oxygen chemical concentration.

[0016] In the concentration measurement step, the carbon chemical concentration of the semiconductor substrate may further be measured. In the particle implantation step, the implantation conditions of the charged particle beam may be adjusted according to the oxygen chemical concentration and the carbon chemical concentration.

[0017] At a predetermined depth position of the semiconductor substrate, the concentration of hydrogen donors to be generated by the manufacturing method is set to N VOH1, the concentration of actually generated hydrogen donors is N VOH2 , the vacancy concentration formed by the particle injection stage, N V , oxygen chemical concentration C OX , carbon chemical concentration C C , where ξ is the oxygen contribution ratio indicating the ratio of the oxygen chemical concentration that contributes to generating hydrogen donors among the oxygen chemical concentration, and η is the carbon contribution ratio indicating the ratio of the carbon chemical concentration that contributes to generating hydrogen donors among the carbon chemical concentration, N VOH1 =N V +ξC OX +ηC C and 0.1≦N VOH1 / N VOH2 It may be ≦10.

[0018] In the implantation step, hydrogen ions may be implanted as the charged particle beam.

[0019] The manufacturing method may comprise a hydrogen implantation step, prior to the heat treatment step, of implanting hydrogen ions into the underside of the semiconductor substrate.

[0020] The manufacturing method may include an oxygen introduction step of introducing oxygen into the semiconductor substrate.

[0021] The implantation conditions for the hydrogen ions in the hydrogen implantation step may be adjusted based on the oxygen chemical concentration of the semiconductor substrate.

[0022] Based on the implantation depth of the charged particle beam in the particle implantation step, the implantation conditions of the hydrogen ions in the hydrogen implantation step and the heat treatment conditions in the heat treatment step may be adjusted.

[0023] The method may include an oxygen introduction step of introducing oxygen into the semiconductor substrate.

[0024] At least one of the conditions for injecting the charged particle beam in the particle implantation step and the conditions for heat treatment in the heat treatment step may be adjusted based on the bulk donor concentration of the semiconductor substrate.

[0025] The manufacturing method may include a grinding step of grinding the semiconductor substrate. The manufacturing method may include a substrate thickness measurement step of measuring the thickness of the semiconductor substrate after grinding. At least one of the injection conditions of the charged particle beam in the particle injection step and the heat treatment conditions in the heat treatment step may be adjusted based on the thickness of the semiconductor substrate.

[0026] In the particle implantation step, implantation conditions may be adjusted for each of the plurality of semiconductor substrates, and in the heat treatment step, heat treatment conditions may be adjusted in common for the plurality of semiconductor substrates.

[0027] The implantation conditions for the hydrogen ions in the hydrogen implantation step may be adjusted based on the thickness of the semiconductor substrate.

[0028] The substrate thickness measurement step may measure the thickness of the semiconductor substrate at the edge termination structure of the semiconductor substrate.

[0029] A fifth aspect of the present invention provides a method for manufacturing a semiconductor device. The manufacturing method may include a concentration acquisition step of acquiring an impurity concentration of a semiconductor substrate having an upper surface and a lower surface. The manufacturing method may include a particle implantation step of implanting a charged particle beam from the lower surface of the semiconductor substrate so as to pass through at least half of the thickness of the semiconductor substrate in the depth direction. The manufacturing method may include a heat treatment step of heat treating the semiconductor substrate after implanting the charged particle beam. In the particle implantation step, the implantation depth of the charged particle beam may be adjusted according to the impurity concentration.

[0030] In the concentration acquisition step, at least one of a bulk donor concentration, an oxygen chemical concentration, and a carbon chemical concentration of the semiconductor substrate may be acquired.

[0031] In the particle implantation step, the implantation depth of the charged particle beam may be adjusted based on at least one of an oxygen contribution ratio ξ, which indicates the proportion of the oxygen chemical concentration that contributes to generating hydrogen donors among the oxygen chemical concentration, and a carbon contribution ratio η, which indicates the proportion of the carbon chemical concentration that contributes to generating hydrogen donors among the carbon chemical concentration.

[0032] 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]

[0033] [Figure 1] 1 is a cross-sectional view showing an example of a semiconductor device 100. FIG. [Figure 2] 1. The depth distribution of the hydrogen chemical concentration CH, oxygen chemical concentration COX, vacancy concentration NV, contributing hydrogen concentration NH, and contributing oxygen concentration NOX at the position indicated by line AA in FIG. 1 is shown. [Figure 3] 1 shows the depth distribution of the hydrogen chemical concentration CH, oxygen chemical concentration COX, contributing oxygen concentration NOX, and VOH defect concentration NVOH after heat treatment. [Figure 4] FIG. 10 is a diagram showing an example of the distribution of donor concentration DD after heat treatment. [Figure 5A] FIG. 2 is a diagram illustrating a flat portion 150. [Figure 5B] 10 shows another example of distribution of the bulk donor concentration D0, the hydrogen donor concentration Db, and the donor concentration Dd in the flat portion 150. [Figure 5C] 10 shows another example of distribution of the bulk donor concentration D0, the hydrogen donor concentration Db, and the donor concentration Dd in the flat portion 150. [Figure 6] FIG. 10 is a graph showing the relationship between the donor concentration increase amount and the oxygen chemical concentration COX. [Figure 7] FIG. 10 is a graph showing the relationship between the donor concentration increase amount and the oxygen chemical concentration COX. [Figure 8] FIG. 10 is a graph showing the relationship between the dose of hydrogen ions and the oxygen contribution ratio ξ and the vacancy concentration NV. [Figure 9] FIG. 10 is a graph showing the relationship between the dose of hydrogen ions and the oxygen contribution ratio ξ and the vacancy concentration NV. [Figure 10] 1 is a top view showing an example of a semiconductor device 100. FIG. [Figure 11] FIG. 11 is an enlarged view of an area D in FIG. [Figure 12]FIG. 12 is a diagram showing an example of an ee cross section in FIG. [Figure 13] 13 is a diagram showing an example of a carrier concentration distribution in the depth direction at the position of the FF line in FIG. 12. FIG. [Figure 14] FIG. 11 is a diagram showing an example of the gg cross section in FIG. [Figure 15] FIG. 11 is a diagram showing another example of the gg cross section in FIG. [Figure 16] 2A to 2C are diagrams illustrating an example of a method for manufacturing the semiconductor device 100. [Figure 17] 10A and 10B are diagrams illustrating another example of a method for calculating the injection amount of a charged particle beam. [Figure 18] 5A to 5C are diagrams illustrating another example of the method for manufacturing the semiconductor device 100. [Figure 19] FIG. 16 is a diagram showing an example of a device manufacturing stage S1606. [Figure 20] FIG. 16 is a diagram showing another example of the device manufacturing step S1606. [Figure 21] 10 is a diagram showing the relationship between the oxygen contribution rate ξ and the depth position Z1 at which the second peak 141 is located. FIG. [Figure 22] 10 is a diagram showing the relationship between the vacancy concentration NV and the depth position Z1 at which the second peak 141 is located. FIG. [Figure 23] 1. The graph shows the depth distribution of the hydrogen chemical concentration CH, carbon chemical concentration CC, contributing carbon concentration NC, and VOH defect concentration NVOH after heat treatment at the position indicated by line AA in FIG. [Figure 24] FIG. 10 is a diagram showing the relationship between the donor concentration increase amount and the carbon chemical concentration CC. [Figure 25] FIG. 10 is a graph showing the relationship between the donor concentration increase amount and the oxygen chemical concentration COX. [Figure 26] FIG. 10 is a diagram showing the relationship between the hydrogen ion dose at the depth position Z1 and the carbon contribution rate η. [Figure 27] FIG. 10 is a graph showing the relationship between the oxygen contribution rate ξ and the hydrogen ion dose DH in a group with a small carbon chemical concentration CC. [Figure 28]FIG. 10 is a graph showing the relationship between the vacancy concentration NV and the hydrogen ion dose DH in a group with a small carbon chemical concentration CC. [Figure 29] 2A to 2C are diagrams illustrating an example of a method for manufacturing the semiconductor device 100. [Figure 30] FIG. 10 is a diagram showing another example of the relationship between the vacancy concentration NV and the depth position Z1. [Figure 31] FIG. 10 is a diagram showing another example of the relationship between the oxygen contribution rate ξ and the depth position Z1. [Figure 32] FIG. 10 is a diagram showing the relationship between the carbon contribution rate η and the depth position Z1. [Figure 33A] 10 is a graph showing the helium ion dose dependence of vacancy concentration with respect to electrical target characteristics. [Figure 33B] 10 is a graph showing the helium ion dose dependency of the oxygen contribution rate to electrical target characteristics. [Figure 33C] 10 is a graph showing the helium ion dose dependence of the carbon contribution rate to electrical target characteristics. [Figure 34A] 10 is a graph showing the helium ion depth dependence of the reduced vacancy concentration Nv' in the electrical target characteristics. [Figure 34B] 10 is a graph showing the helium ion depth dependence of the converted oxygen contribution ratio ξ' in the electrical target characteristics. [Figure 34C] 10 is a graph showing the helium ion depth dependence of the converted carbon contribution ratio η′ in the electrical target characteristics. [Figure 35] 5A to 5C are diagrams illustrating another example of the method for manufacturing the semiconductor device 100. [Figure 36] 5A to 5C are diagrams illustrating another example of the method for manufacturing the semiconductor device 100. [Figure 37] 5A to 5C are diagrams illustrating another example of the method for manufacturing the semiconductor device 100. [Figure 38] This figure shows the relationship between bulk donor concentration and the implantation depth Z1 of charged particles. [Figure 39] 5A to 5C are diagrams illustrating another example of the method for manufacturing the semiconductor device 100. [Figure 40] 10 is a diagram showing an example of an equipotential surface 308 in an edge termination structure 90. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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%.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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).

[0044] 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.

[0045] 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 the region. In cases where the concentration of the donor, acceptor, or net doping is substantially (almost) uniform, the average value of the concentration of the donor, acceptor, or net doping in the 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 3This unit is used for donor or acceptor concentration or chemical concentration in a semiconductor substrate. The notation in atoms may be omitted. Note that the concentrations in the present invention may be values ​​at room temperature. As an example of the value at room temperature, the value at 300 K (Kelvin) (approximately 26.9°C) may be used.

[0046] 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.

[0047] 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.

[0048] 1 is a cross-sectional view showing an example of a semiconductor device 100. 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.

[0049] At least one of a transistor element such as an insulated gate bipolar transistor (IGBT) and a diode element such as a free wheel diode (FWD) is formed on the semiconductor substrate 10. In Fig. 1, the electrodes of the transistor element and the diode element and the regions provided inside the semiconductor substrate 10 are omitted.

[0050] In this example, the semiconductor substrate 10 has N-type bulk donors distributed throughout. The bulk donors are dopants uniformly contained within the ingot from which the semiconductor substrate 10 is formed during its manufacture. The bulk donors in this example are elements other than hydrogen. The dopants of the bulk donors are, for example, Group V or Group VI elements, such as, but not limited to, phosphorus, antimony, arsenic, selenium, or sulfur. The bulk donors in this example are phosphorus. The bulk donors are also contained within the P-type regions. The semiconductor substrate 10 may be a wafer cut from a semiconductor ingot or 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.

[0051] For example, the oxygen chemical concentration in a substrate manufactured by the MCZ method is 1×10 17 ~7×10 17 atoms / cm 3 For example, the oxygen chemical concentration in a substrate manufactured by the FZ method is 1×10 15 ~5×10 16 atoms / cm 3 The bulk donor concentration may be the chemical concentration of bulk donors distributed throughout the semiconductor substrate 10, and may be between 90% and 100% of that chemical concentration. In a semiconductor substrate doped with a group V or VI dopant such as phosphorus, the bulk donor concentration is 1×10 11 / cm 3 That's it, 3 x 10 13 / cm 3 The bulk donor concentration of the semiconductor substrate doped with group V and group VI dopants is preferably 1×10 12 / cm 3 That's it, 1 x 10 13 / cm 3 The semiconductor substrate 10 may be a non-doped substrate that does not contain dopants such as phosphorus. In this case, the bulk donor concentration (N B0 ) is, for example, 1×1010 / cm 3 That's it, 5 x 10 12 / cm 3 The bulk donor concentration of the undoped substrate (N B0 ) is preferably 1 × 10 11 / cm 3 The bulk donor concentration (N B0 ) is preferably 5 × 10 12 / cm 3 The following is the result.

[0052] The semiconductor substrate 10 has an upper surface 21 and a lower surface 23. The upper surface 21 and the lower surface 23 are the two main surfaces of the semiconductor substrate 10. In this specification, orthogonal axes in planes parallel to the upper surface 21 and the lower surface 23 are defined as the X-axis and the Y-axis, and an axis perpendicular to the upper surface 21 and the lower surface 23 is defined as the Z-axis.

[0053] A charged particle beam is implanted into the semiconductor substrate 10 from the bottom surface 23 at a predetermined depth position Z1. In this specification, the distance in the Z-axis direction from the bottom surface 23 may be referred to as the depth position. The depth position Z1 is a position at a distance Z1 in the Z-axis direction from the bottom surface 23. The depth position Z1 is located on the top surface 21 side of the semiconductor substrate 10. Injecting a charged particle beam into the depth position Z1 means that the average distance (also referred to as the range) that the charged particles travel inside the semiconductor substrate 10 is Z1. The charged particles are accelerated with acceleration energy according to the predetermined depth position Z1 and introduced into the semiconductor substrate 10.

[0054] The region through which the charged particles pass inside the semiconductor substrate 10 is defined as the passage region 106. In the example of FIG. 1, the passage region 106 extends from the lower surface 23 of the semiconductor substrate 10 to a depth position Z1. The charged particles are particles that can form lattice defects in the passage region 106. The charged particles are, for example, hydrogen ions, helium ions, or electrons. The charged particles may be implanted into the entire surface of the semiconductor substrate 10 in the XY plane, or may be implanted into only a partial region.

[0055] The semiconductor substrate 10 has a second peak 141 of charged particle concentration at depth position Z1. In this example, the charged particles are hydrogen. That is, the semiconductor substrate 10 of this example has a second peak 141 of hydrogen chemical concentration at depth position Z1. The second peak 141 is a peak in the hydrogen chemical concentration distribution in the depth direction (Z-axis direction). The second peak may also be a peak in the helium chemical concentration distribution.

[0056] In the semiconductor substrate 10, the passage region 106 through which the charged particles have passed forms vacancy-based lattice defects, such as monovacancies (V) and divacancies (VV). Atoms adjacent to the vacancies have dangling bonds. Lattice defects include interstitial atoms and dislocations, and may also include donors and acceptors in a broader 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 injection of charged particles into the semiconductor substrate 10 may severely disrupt the crystallinity of the semiconductor substrate 10. In this specification, this disruption in crystallinity may be referred to as disorder.

[0057] The entire semiconductor substrate 10 contains oxygen. This oxygen is introduced intentionally or unintentionally during the production of a semiconductor ingot. At least a portion of the passage region 106 contains hydrogen. This hydrogen may be intentionally implanted into the semiconductor substrate 10.

[0058] In this example, hydrogen ions are implanted from the lower surface 23 at depth position Z2. The hydrogen ions in this example are protons. The semiconductor substrate 10 in this example has a first peak 133 of hydrogen chemical concentration at depth position Z2. In FIG. 1, the second peak 141 and the first peak 133 are schematically shown by dashed lines. Depth position Z2 may be included in the passage region 106. In this example, depth position Z2 is located on the lower surface 23 side of the semiconductor substrate 10. Note that hydrogen implanted at depth position Z1 may diffuse into the passage region 106, or hydrogen may be introduced into the passage region 106 by another method. In these cases, hydrogen ions may not be implanted at depth position Z2.

[0059] After the passage region 106 is formed in the semiconductor substrate 10 and hydrogen ions are implanted into the semiconductor substrate 10, hydrogen (H), vacancies (V), and oxygen (O) combine to form VOH defects inside the semiconductor substrate 10. Furthermore, by heat-treating the semiconductor substrate 10, hydrogen diffuses, promoting the formation of VOH defects. Furthermore, by performing heat treatment after forming the passage region 106, hydrogen can combine with vacancies, thereby suppressing the release of hydrogen to the outside of the semiconductor substrate 10.

[0060] VOH defects function as donors that supply electrons. In this specification, VOH defects may be simply referred to as hydrogen donors. In the semiconductor substrate 10 of this example, hydrogen donors are formed in the passage region 106. The doping concentration of the hydrogen donors at each position is lower than the chemical concentration of hydrogen at each position. The hydrogen contribution is the ratio of the chemical concentration of hydrogen that contributes to the doping concentration of the hydrogen donors (VOH defects) to the chemical concentration of hydrogen. The hydrogen contribution may be considered to be the ratio of the concentration of hydrogen atoms that constitute VOH defects to the concentration of all hydrogen atoms in a given region (e.g., a depth position from the bottom or top surface). The hydrogen contribution may be a value of 0.1% to 30% (i.e., 0.001 or more and 0.3 or less). In this example, the hydrogen contribution is 1% to 5%. Unless otherwise specified, in this specification, both VOH defects having a distribution similar to the chemical concentration distribution of hydrogen and VOH defects similar to the distribution of vacancy defects in the passage region 106 are referred to as hydrogen donors or hydrogen as a donor.

[0061] By forming hydrogen donors in the passage region 106 of the semiconductor substrate 10, the donor concentration in the passage region 106 can be made higher than the bulk donor concentration. Typically, a semiconductor substrate 10 having a predetermined bulk donor concentration must be prepared in accordance with the characteristics of the device to be formed in the semiconductor substrate 10, particularly the rated voltage or breakdown voltage. In contrast, the semiconductor device 100 shown in FIG. 1 allows the donor concentration of the semiconductor substrate 10 to be adjusted by controlling the dose of charged particles. Therefore, the semiconductor device 100 can be manufactured using a semiconductor substrate with a bulk donor concentration that does not correspond to the device characteristics, etc. Although the bulk donor concentration varies relatively widely during the manufacturing of the semiconductor substrate 10, the dose of charged particles can be controlled with relatively high precision. Therefore, the concentration of lattice defects generated by the implantation of charged particles can also be controlled with high precision, allowing the donor concentration in the passage region to be controlled with high precision.

[0062] Depth position Z1 may be located within a range of less than half the thickness of semiconductor substrate 10, or may be located within a range of less than ¼ the thickness of semiconductor substrate 10, based on top surface 21. Depth position Z2 may be located within a range of less than half the thickness of semiconductor substrate 10, or may be located within a range of less than ¼ the thickness of semiconductor substrate 10, based on bottom surface 23. However, depth positions Z1 and Z2 are not limited to these ranges.

[0063] Figure 2 shows the hydrogen chemical concentration C at the position indicated by line AA in Figure 1. H , oxygen chemical concentration C OX、 Vacancy concentration N V , contributing hydrogen concentration N H , and contributing oxygen concentration N OX 2 shows the distribution of charged particles and hydrogen ions in the depth direction immediately after implantation. That is, FIG. 2 shows the distribution of charged particles and hydrogen ions after implantation into the semiconductor substrate 10 and before heat treatment at a temperature higher than room temperature (25° C.).

[0064] The horizontal axis in FIG. 2 indicates the depth position from the lower surface 23, and the vertical axis indicates the concentration per unit volume on a logarithmic scale. The chemical concentration in FIG. 2 is measured, for example, by the SIMS method. In FIG. 2, the bulk donor concentration N B0 is shown by the dashed line. The bulk donor concentration N B0 may be uniform over the entire semiconductor substrate 10. The central depth position in the depth direction of the semiconductor substrate 10 is defined as Zc.

[0065] Hydrogen chemical concentration C H The distribution of hydrogen chemical concentration C has a second peak 141 at depth Z1 and a first peak 133 at depth Z2. H The hydrogen chemical concentration C H The second peak 141 and the first peak 133 correspond to the hydrogen chemical concentration C H The first peak 133 may be 10 times or more larger than the smallest value of the second peak 141. The first peak 133 may be 10 times or more larger than the second peak 141, or may be 100 times or more larger than the second peak 141.

[0066] Hydrogen chemical concentration C H The distribution of hydrogen chemical concentration C H The hydrogen chemical concentration C H When hydrogen ions are implanted from the lower surface 23, the lower skirt 142 is gentler than the upper skirt 143. In this specification, a gentle skirt means that the position at half the corresponding peak value is farther away from the corresponding peak position.

[0067] Contributing hydrogen concentration N H is the concentration of hydrogen that forms VOH defects. VOH defects contain vacancies and oxygen in addition to hydrogen, so the contributing hydrogen concentration N H may vary depending on the concentration of vacancies and oxygen. H is the hydrogen chemical concentration C HIt may be 0.1% to 30% of the above.

[0068] Contributing hydrogen concentration N H The distribution of hydrogen chemical concentration C H The distribution is similar to that of the contributing hydrogen concentration N H has a first contribution concentration peak 161 at or near depth position Z1, and a second contribution concentration peak 151 at or near depth position Z2.

[0069] Oxygen is often introduced during the production of the ingot and is often uniformly distributed within the semiconductor substrate 10. The oxygen chemical concentration C OX may be uniform throughout the semiconductor substrate 10. In another example, the oxygen chemical concentration C OX may monotonically increase or decrease from the lower surface 23 to the upper surface 21 of the semiconductor substrate 10. In addition, oxygen near the upper surface 21 or the lower surface 23 of the semiconductor substrate 10 may be released to the outside of the semiconductor substrate 10. OX In the vicinity of the upper surface 21 and the lower surface 23, the oxygen chemical concentration C may decrease monotonically toward the upper surface 21 and the lower surface 23. The vicinity of the upper surface 21 and the lower surface 23 is, for example, a region within 1 μm from the upper surface 21 or the lower surface 23, but is not limited to this. In the area other than the vicinity of the upper surface 21 and the lower surface 23, the oxygen chemical concentration C OX may be uniform, as described above, or may be monotonically increasing or decreasing.

[0070] Oxygen chemical concentration C OX is 3 x 10 15 atoms / cm 3 That's it, 2 x 10 18 atoms / cm 3 In this specification, the oxygen chemical concentration C OX When the oxygen chemical concentration C is specified, unless otherwise specified, the entire area between the second peak 141 and the first peak 133 satisfies the specified oxygen concentration. The entire area between the second peak 141 and the lower surface 23 may also satisfy the specified oxygen concentration, and the entire semiconductor substrate 10 may also satisfy the specified oxygen concentration. OXis 1 x 10 16 atoms / cm 3 May be greater than or equal to 1 x 10 17 atoms / cm 3 The oxygen chemical concentration C OX is 1 x 10 18 atoms / cm 3 may be less than or equal to 1 x 10 17 atoms / cm 3 It may be the following:

[0071] Contributing oxygen concentration N OX indicates the concentration of oxygen that forms VOH defects. VOH defects contain vacancies and hydrogen in addition to oxygen, so the contributing oxygen concentration N OX may vary depending on the concentration of vacancies and hydrogen. In this specification, the contributing oxygen concentration N OX and oxygen chemical concentration C OX The ratio of N to N is the oxygen contribution ratio ξ. OX / C OX The oxygen contribution ratio ξ can be considered as the ratio of the concentration of oxygen atoms that make up VOH defects to the concentration of all oxygen atoms in a given region (for example, the depth position from the bottom or top surface). ξ is greater than or equal to 0 and less than or equal to 1. The unit of the oxygen contribution ratio is a dimensionless quantity.

[0072] Contributing oxygen concentration N OX The distribution of oxygen chemical concentration C OX For example, the distribution of the contributing oxygen concentration N OX may be uniform in the depth direction of the semiconductor substrate 10, or may increase or decrease monotonically. Alternatively, the contributing oxygen concentration N OX may have a concentration distribution with a peak at a predetermined depth position.

[0073] Vacancy concentration N V has a vacancy peak 171 at a depth position Zd. The depth position Zd may be the same as the depth position Z1, or may be located slightly closer to the lower surface 23 than the depth position Z1. H is the vacancy concentration N Vmay have a first contributing concentration peak 161 at the same depth position as

[0074] When charged particles are injected into the semiconductor substrate 10, damage is introduced into the region from the injection surface of the semiconductor substrate 10 to the range of the charged particles. The damage is a disorder of the crystal lattice, and may be in the form of vacancies, dislocations, or an amorphous state. The vacancy concentration N V may also have a peak at the depth position Z2. V may be substantially (almost) uniform, monotonically increasing, or monotonically decreasing between the two peaks. When the charged particles are electrons, the vacancy concentration N V may be substantially uniform from the top surface to the bottom surface of the semiconductor substrate 10, may increase monotonically, may decrease monotonically, or may have a gradual distribution with a peak at a predetermined depth. V can be calculated using software known as TRIM (Transport of Ions in Matter), for example (see, for example, http: / / www.srim.org / . TRIM manuals are disclosed at http: / / srim.org / SRIM / SRIM%2008.pdf and http: / / srim.org / SRIM / SRIM%2009.pdf. Part 2 of the manual describes a method for calculating the vacancy concentration.) Before heat treatment, it is believed that most of the vacancies are not terminated with hydrogen.

[0075] Figure 3 shows the hydrogen chemical concentration C after heat treatment. H , oxygen chemical concentration C OX , contributing oxygen concentration N OX , and VOH defect concentration N VOH 2. The heat treatment causes hydrogen to diffuse from the second peak 141 and the first peak 133 toward the upper surface 21 and the lower surface 23. Even after the heat treatment, the magnitude relationship, ratio, value, etc. of the concentrations of the peaks, as well as the oxygen chemical concentration, may be the same as those before the heat treatment shown in FIG. 2. As a result, the hydrogen chemical concentration C between the second peak 141 and the first peak 133 HIn this example, since the first peak 133 with a high concentration is provided, more hydrogen diffuses from the first peak 133. Therefore, in the region from the depth position Z2 to the depth position Z1, the hydrogen chemical concentration C H The hydrogen chemical concentration C H may decrease monotonically from the depth position Z2 to the upper surface 21 side of the depth position Zc.

[0076] The heat treatment causes hydrogen to terminate the dangling bonds in the vacancies. As a result, donors for VOH defects (terminating dangling bonds) are formed. The VOH defect concentration N VOH is the contributing hydrogen concentration N H , contributing oxygen concentration N OX , vacancy concentration N V In this example, the VOH defect concentration N VOH has a first VOH peak 191 near depth position Z1 and a second VOH peak 181 near depth position Z2. The first VOH peak 191 may be located at depth position Zd. In this example, the second VOH peak 181 is more concentrated than the first VOH peak 191.

[0077] The semiconductor substrate 10 also has a flat portion 150 between the depth position Z1 and the depth position Z2. The flat portion 150 has a VOH defect concentration N VOH The flat portion 150 may be provided over half or more of the length between the depth position Z1 and the depth position Z2, or may be provided over 75% or more of the length.

[0078] In the flat portion 150, the contributing oxygen concentration N OX is the hydrogen chemical concentration C OX In this case, the hydrogen chemical concentration C OX The minimum value in the plateau 150 may be used as the contributing oxygen concentration N OX is the hydrogen chemical concentration C OX It may be 10% or less of the above.

[0079] Figure 4 shows the donor concentration D D4 is a diagram showing an example of the distribution of hydrogen chemical concentration C H , oxygen chemical concentration C OX , bulk donor concentration N B0 The hydrogen chemical concentration C H and oxygen chemical concentration C OX is identical to the example in Figure 3. Bulk donor concentration N B0 is the same as the example in Figure 2.

[0080] In this example, the donor concentration D D is the bulk donor concentration N B0 , VOH defect concentration N VOH The donor concentration N B0 has a first donor peak 121 at a depth position Zd and a second donor peak 111 at a depth position Z2. In this example, the second donor peak 111 has a higher concentration than the first donor peak 121. In addition, in the flat portion 150, the donor concentration D D is substantially (almost) flat. The donor concentration D D is the bulk donor concentration N B0 Higher than.

[0081] 5A is a diagram illustrating a flat portion 150. The flat portion 150 is a portion where the donor concentration D D The region where the donor concentration is between a predetermined maximum value max and a predetermined minimum value min is continuous in the depth direction. The maximum value max may be the maximum value of the donor concentration in the region. The minimum value min may be 50%, 70%, or 90% of the maximum value max.

[0082] Alternatively, the value of the donor concentration distribution may be within ±50%, ±30%, or ±10% of the average concentration of the donor concentration distribution in a predetermined range in the depth direction. VOH Also, donor concentration D D is substantially (almost) flat.

[0083] FIG. 5B shows another example of the distribution of the bulk donor concentration D0, hydrogen donor concentration Db, and donor concentration Dd in the flat portion 150. This example differs from the example in FIG. 5A in that the flat portion 150 has a gradient in the depth direction. The thickness of the semiconductor substrate 10 in this example is 120 μm. The vertical axis of this figure is a linear scale. The predetermined region is defined as a region from 20 μm to 80 μm deep from the hydrogen ion implantation surface. The predetermined region is a region through which the hydrogen ions penetrate and in which there is no local peak in the donor concentration Dd. The thickness of the predetermined region in this example is 50% of the thickness of the semiconductor substrate 10. The bulk donor concentration D0 in this example is 3.1×10 13 / cm 3 which corresponds to 150 Ωcm. The sum of the bulk donor concentration D0 and the hydrogen donor Db at each depth is the donor concentration Dd.

[0084] A distribution in which the densities at both ends of a predetermined region are connected by a straight line may be referred to as a linear approximation distribution. The linear approximation distribution may be a line obtained by fitting the densities in a predetermined region with a linear function. Furthermore, the linear approximation distribution may be a line obtained by fitting a distribution excluding local peaks of each density distribution with a linear function. Furthermore, a band-like range having a width of 30% of the value of the linear approximation distribution centered on the linear approximation distribution is referred to as a band-like range. A monotonically increasing or decreasing density distribution in a predetermined region refers to a state in which the density values ​​at both ends of the predetermined region are different and the density distribution is included in the above-mentioned band-like range. The band-like range may have a width of 20% or 10% of the value of the linear approximation distribution.

[0085] The linear approximation distribution 214 of the donor concentration Dd is a distribution in which the concentration increases with increasing distance from the implantation surface. The concentration of vacancies formed in a predetermined region penetrated by hydrogen ions is a distribution in which the concentration increases with increasing distance from the implantation surface. The dangling bonds present in the formed vacancies are terminated by diffused hydrogen, resulting in a hydrogen donor concentration distribution that follows the vacancy concentration distribution. In this example, in the predetermined region penetrated by hydrogen ions, the donor concentration Dd varies by approximately ±7% from the linear approximation distribution 214. This variation in the donor concentration Dd is referred to as a band-like range 216. That is, the width of the band-like range 216 in this example is ±7% of the value of the linear approximation distribution 214. In a predetermined region having a thickness equal to or greater than 30% of the thickness of the semiconductor substrate 10, the distribution of the donor concentration Db may be considered to be a flat distribution if it is within the band-like range 216. That is, this predetermined region may be considered a hydrogen donor flat region. The linear approximation distribution 214 of the donor concentration Dd may be a distribution in which the concentration decreases as the distance from the implantation surface increases.

[0086] FIG. 5C shows another example of the distribution of bulk donor concentration D0, hydrogen donor concentration Db, and donor concentration Dd. This example differs from the example of FIG. 5B in that the slope of flat portion 150 is even steeper. In this example, the predetermined region is defined as a depth from 10 μm to 70 μm from the hydrogen ion implantation surface. In this example, the thickness of the predetermined region relative to the thickness (120 μm) of semiconductor substrate 10 is 50%, the same as in the example of FIG. 5B.

[0087] The linear approximation distribution 214 of the donor concentration Dd is a distribution in which the concentration increases with increasing distance from the implantation surface. However, the linear approximation distribution 214 of this example has a steeper increase slope than the linear approximation distribution 214 of FIG. 5B. Furthermore, in a predetermined region, the donor concentration Dd varies by approximately ±17% from the linear approximation distribution 214. This variation in the donor concentration Dd is defined as a belt-like range 216. The width of the belt-like range 216 is ±17% of the value of the linear approximation distribution 214. Therefore, in a predetermined region having a thickness equal to or greater than 30% of the thickness of the semiconductor substrate 10, if the distribution of the donor concentration Db is within the belt-like range 216, the distribution of the donor concentration Db may be considered to be a flat distribution. In other words, this predetermined region may be considered a hydrogen donor flat region.

[0088] The hydrogen donor flat region may be provided in a range of 20% to 80% of the thickness of the semiconductor substrate. The absolute value of the slope of the linear approximation distribution 214 in the hydrogen donor flat region is 0 / (cm 3 ·μm) or more, 2×10 12 / (cm 3 ·μm) or less, and 3 μm), 1×10 12 / (cm 3 Furthermore, the absolute value of the slope of the linear approximation distribution 214 in the hydrogen donor plateau region may be 1×10 10 / (cm 3 ·μm) or more, 1×10 12 / (cm 3 1×10 μm or less, 10 / (cm 3 ·μm) or more, 5×10 11 / (cm 3 5×10 μm or less. 11 / (cm 3 μm) is 5×10 15 / cm 4 It has the same slope (equivalent).

[0089] A semi-logarithmic slope may be used as another index of the slope of the linear approximation distribution 214. The position of one end of a predetermined region is defined as x1 (cm) and the position of the other end as x2 (cm). The concentration at x1 is defined as N1 ( / cm 3 ), and the concentration at x2 is N2 ( / cm 3 ) The semi-logarithmic slope η ( / cm) in a given area is defined as η = (log 10 (N2)-log 10 The absolute value of the semi-logarithmic slope η of the linear approximation distribution 214 in the hydrogen donor plateau region may be 0 / cm or more and 50 / cm or less, or 0 / cm or more and 30 / cm or less. Furthermore, the absolute value of the semi-logarithmic slope η of the linear approximation distribution 214 in the hydrogen donor plateau region may be 0 / cm or more and 20 / cm or less, or 0 / cm or more and 10 / cm or less.

[0090] In the region through which the hydrogen ions have passed, vacancies (V, VV, etc.) generated by the passage of hydrogen are thought to be distributed at a substantially (almost) uniform concentration in the depth direction. Furthermore, oxygen (O) implanted during the manufacturing process of the semiconductor substrate 10 is also thought to be distributed uniformly in the depth direction. Meanwhile, in the manufacturing process of the semiconductor device 100, oxygen may diffuse from the upper surface 21 or the lower surface 23 of the semiconductor substrate 10 to the outside of the semiconductor substrate 10 during high-temperature processing at 1100°C or higher. As a result, the oxygen concentration may decrease toward the upper surface 21 or the lower surface 23 of the semiconductor substrate 10.

[0091] According to the semiconductor device 100 described with reference to FIGS. 1 to 5C, the vacancy concentration N V can be controlled, and the hydrogen chemical concentration C H Therefore, the donor concentration D D Moreover, by adjusting the injection position Z1 of the charged particles, the range in which the flat portion 150 is formed can be easily controlled.

[0092] Next, the range of the oxygen contribution ratio ξ in the semiconductor substrate 10 will be described. When the semiconductor device 100 is completed, the final doping concentration at any position between the depth position Z1 and the depth position Z2 is set to N F Let the doping concentration N F is shown in equation (1). N F =N B0 +N VOH ...Equation (1) where VOH defect concentration N VOH is the concentration of hydrogen-terminated vacancies and the contributing oxygen concentration N OX (i.e., ξC OX ) is the sum of the hydrogen chemical concentration C. In the flat portion 150, the concentration of VOH defects is determined by the concentration of vacancies terminated with hydrogen and the concentration of contributing oxygen. H is sufficiently high, so that substantially (almost) all vacancies from the depth position Z1 to the depth position Z2 are terminated with hydrogen. In other words, the vacancy concentration is the hydrogen-terminated vacancy concentration N V Therefore, we obtain equation (2). N VOH =N V +ξC OX ...Equation (2) Equation (3) is obtained from equations (1) and (2). N F =N B0 +N V +ξC OX ...Equation (3)

[0093] Here, the bulk donor concentration N B0 is the same and the oxygen chemical concentration C OX Let us consider a case where a semiconductor device 100 is formed using two semiconductor substrates with different doping concentrations. F1 , the final doping concentration in the second semiconductor substrate is N F2 The oxygen chemical concentration in the first semiconductor substrate is C OX1 , the oxygen chemical concentration in the second semiconductor substrate is C OX2 Let's say.

[0094] Since the hydrogen implantation conditions are the same, the vacancy concentration N V Therefore, the oxygen contribution ratio ξ is also assumed to be the same for the two semiconductor substrates. Equations (4) and (5) are obtained from equation (3). N F1 =N B0 +N V +ξC OX1 ...Equation (4) N F2 =N B0 +N V +ξC OX2 ...Equation (5) where N F2 >N F1 Let's say.

[0095] The difference in final doping concentration is the VOH defect concentration N VOH Difference ΔN VOH Therefore, equation (6) can be obtained from equations (4) and (5). N F2 -N F1 =ΔN VOH =ξ(C OX2 -C OX1 ) ξ=ΔN VOH / (C OX2 -C OX1 )...Equation (6)

[0096] Furthermore, equation (7) can be obtained from equations (2) and (6). N V =N VOH -ξC OX =N VOH -(ΔN VOH / (C OX2 -C OX1 ))C OX ...Equation (7) From equation (7), if the oxygen contribution ratio ξ is given, then any VOH defect concentration N VOH and oxygen chemical concentration C OX For vacancy concentration N V can be calculated.

[0097] Figure 6 shows the relationship between the donor concentration increase and the oxygen chemical concentration C OX In this example, the carrier concentrations at the depth position Zc were measured by the SR method for two substrates, one before implanting charged particles and hydrogen ions, and the other after implanting charged particles and hydrogen ions and heat treatment, and the difference between them was taken as the donor concentration increase. The donor concentration increase was calculated by the VOH defect concentration N VOH In addition, the oxygen chemical concentration C OX is distributed uniformly in the depth direction.

[0098] In FIG. 6, the depth position Z1 is set to 100 μm, and hydrogen ions are implanted at the depth position Z1. In this example, the dose of hydrogen ions at the depth position Z1 is 3×10 12 ions / cm 2 , 1×10 13 ions / cm 2 , 3×10 13 ions / cm 2 As shown in Figure 6, the oxygen chemical concentration C OX The donor concentration increase is linearly proportional to the

[0099] In the example of Figure 6, the oxygen chemical concentration C OX and the donor concentration increase (i.e., N VOH ) is calculated as an approximate equation that approximates the relationship with the dose of hydrogen ions. 13 ions / cm 2 The example is approximated by a straight line 601, and the dose of hydrogen ions is 1×10 13 ions / cm 2 The example is approximated by a straight line 602, and the dose of hydrogen ions is 3 × 10 12 ions / cm 2 The example is approximated by a straight line 603.

[0100] Each line is expressed by equation (8). N VOH = a × C OX +b...Formula (8) In this case, by fitting using the least squares method, the slope a and intercept b of each line are as follows: Straight line 601:a=2.96303×10 -4 , b=2.18399×10 13 Straight line 602: a=1.87895×10 -4 , b=1.47920×10 13 Straight line 603: a=7.58824×10 -5 , b=6.38380×10 12 Comparing equation (2) and equation (8), a=ξ, b=N V is.

[0101] Figure 7 shows the relationship between the donor concentration increase and the oxygen chemical concentration C OX In this example, the depth position Z1 is set to 50 μm. Other conditions are the same as those in FIG. 6. In this example, the oxygen chemical concentration C OX The donor concentration increase is linearly proportional to the

[0102] Figure 8 shows the relationship between the hydrogen ion dose, oxygen contribution ratio ξ, and vacancy concentration N V 8 is a graph showing the relationship between a and b obtained in the example of FIG. 6 and the hydrogen ion dose D H , the oxygen contribution ratio ξ and the vacancy concentration N V is approximated by a power function. This is because the hydrogen ion dose D H This is because it is thought that the oxygen contribution rate ξ becomes 0 when approaches 0. If the oxygen contribution rate ξ is approximated by a logarithmic function, when the oxygen contribution rate ξ becomes 0, the hydrogen ion dose D H is a finite value greater than 0. Also, the hydrogen ion dose D H If becomes even smaller, the oxygen contribution ratio ξ becomes a negative value. V The same is true for .

[0103] In FIG. 8, the relationship between the oxygen contribution ratio ξ and the hydrogen ion dose is approximated by a curve 801, and the vacancy concentration N VThe relationship between the amount of hydrogen ion and the dose is approximated by a curve 802. The curve 801 is expressed by equation (9), and the curve 802 is expressed by equation (10). In this case, by fitting using the least squares method, the coefficients c to f are as follows: ξ=c×(D H ) d ...Equation (9) where c = 3.11503 × 10 -12 , d=5.94169×10 -1 N V =e×(D H ) f ...Equation (10) where e=1.36398×10 6 , f=5.36782×10 -1

[0104] Hydrogen ion dose D H If is too small, the VOH defect concentration N VOH In this case, the bulk donor concentration N B0 Therefore, it becomes difficult to ensure an increase in donor concentration sufficient to absorb the variation in the hydrogen ion dose. 11 ions / cm 2 At this time, from the formula (9), the oxygen contribution ratio ξ is 1×10 -5 The hydrogen ion dose D H If is too large, the vacancy concentration N V As a result, there are many vacancies that do not become VOH defects. The hydrogen ion dose is 1.2 × 10 14 ions / cm 2 In this case, the oxygen contribution ratio ξ is preferably 7×10 -4 In other words, the oxygen contribution ratio ξ is 1×10 -5 That's it, 7 x 10 -4 The oxygen contribution ratio ξ may be 1×10 -4 The oxygen contribution ratio ξ may be 5×10 -4 Similarly, the vacancy concentration N Vis 1 x 10 11 / cm 3 That's it, 1 x 10 14 / cm 3 The vacancy concentration N V is 1 x 10 12 / cm 3 May be greater than or equal to 1 x 10 13 / cm 3 The vacancy concentration N V is 3 x 10 13 / cm 3 The vacancy concentration N V is the VOH defect concentration N VOH and the contributing oxygen concentration N OX Difference from (N VOH -N OX ) can be calculated from the VOH defect concentration N VOH is the final doping concentration N F and the bulk donor concentration N B0 Difference from (N F -N B0 ) may be calculated.

[0105] Oxygen chemical concentration C OX The general value for the MCZ substrate is used as C OX is 1 x 10 17 ~7×10 17 / cm 3 N OX =ξ×C OX Therefore, the contributing oxygen concentration N OX is 1 x 10 12 / cm 3 ~5×10 14 / cm 3 From equation (2), N VOH =N V +N OX That is, the VOH defect concentration N VOH is 2 x 10 12 / cm 3 That's it, 6 x 10 14 / cm 3 The VOH defect concentration N VOH is 1 x 10 13 / cm 3 The VOH defect concentration N VOHis 5 x 10 14 / cm 3 It may be the following:

[0106] Figure 9 shows the relationship between the hydrogen ion dose, oxygen contribution ratio ξ, and vacancy concentration N V 9 corresponds to the example of FIG. 7 (i.e., Z1=50 μm). In FIG. 9, the relationship between the oxygen contribution ratio ξ and the hydrogen ion dose is approximated by a curve 901, and the vacancy concentration N V The relationship between the amount of hydrogen ion and the dose is approximated by a curve 902. The curve 901 is expressed by equation (12), and the curve 902 is expressed by equation (11). In this case, by fitting using the least squares method, the coefficients c to f are as follows: ξ=c×(D H ) d ...Equation (11) where c = 1.53343 × 10 -12 , d=6.25800×10 -1 N V =e×(D H ) f ...Equation (12) where e=3.11098×10 3 , f=7.41056×10 -1

[0107] In this example, the oxygen contribution ratio ξ may be in the same range as in the example of FIG. V The contributing oxygen concentration N may be in the same range as in the example of FIG. OX The VOH defect concentration may also be in the same range as in the example of FIG.

[0108] In the flat area 150, the oxygen chemical concentration C OX The maximum value of O max and the minimum value O min Let the ratio be ν. In other words, ν=O min / O max The ratio ν may be 0.1 or more and 1 or less. When the ratio ν is small, the VOH defect concentration N VOHThe variation in the depth direction of the semiconductor substrate 10 may become large, which may result in a deterioration in the breakdown voltage of the semiconductor substrate 10. The ratio ν may be 0.3 or more, or may be 0.5 or more. The ratio ν may be 0.95 or less, or may be 0.9 or less.

[0109] The flat portion 150 may contain carbon. The carbon chemical concentration of the flat portion 150 may be 1×10 13 atoms / cm 3 That's it, 1 x 10 16 atoms / cm 3 The carbon chemical concentration may be less than or equal to 1×10 14 atoms / cm 3 The carbon chemical concentration can be 5×10 15 atoms / cm 3 may be less than or equal to 2 x 10 15 atoms / cm 3 The VOH defect concentration N VOH The contribution of carbon chemical concentration to the

[0110] Fig. 10 is a top view showing an example of the semiconductor device 100. Fig. 10 shows the positions of each component projected onto the top surface of the semiconductor substrate 10. Fig. 10 shows only some of the components of the semiconductor device 100, and some components are omitted.

[0111] The semiconductor device 100 includes a semiconductor substrate 10. The semiconductor substrate 10 may have the concentration distributions described in FIGS. 1 to 9 . However, the semiconductor substrate 10 may further have other concentration peaks different from the concentration peaks described in FIGS. 1 to 9 . As in the buffer region 20 described below, an N-type region may be formed in the semiconductor substrate 10 by implanting hydrogen ions. In this case, the hydrogen chemical concentration distribution may have a local hydrogen concentration peak in addition to the hydrogen chemical concentration distribution described in FIG. 2 and the like. Furthermore, as in the emitter region 12 described below, an N-type region may be formed in the semiconductor substrate 10 by implanting N-type impurities other than hydrogen, such as phosphorus. In this case, the donor concentration distribution may have a local donor concentration peak in addition to the donor concentration distribution described in FIG. 4 and the like.

[0112] 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. 10 , 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.

[0113] 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.

[0114] 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. 10, 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.

[0115] In FIG. 10, 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. 10). 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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. 10, the gate wiring is indicated by diagonal hatching.

[0120] The gate wiring in this example has a peripheral gate wiring 130 and an active side gate wiring 131. The peripheral gate wiring 130 is arranged between the active portion 160 and an edge 162 of the semiconductor substrate 10 in a top view. The peripheral gate wiring 130 in this example surrounds the active portion 160 in a top view. The area surrounded by the peripheral gate wiring 130 in a top view may also be the active portion 160. The peripheral gate wiring 130 is connected to a gate pad 164. The peripheral gate wiring 130 is arranged above the semiconductor substrate 10. The peripheral gate wiring 130 may be a metal wiring containing aluminum or the like.

[0121] The active side gate wiring 131 is provided in the active section 160. By providing the active side gate wiring 131 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.

[0122] The active side gate wiring 131 is connected to the gate trench portion of the active section 160. The active side gate wiring 131 is disposed above the semiconductor substrate 10. The active side gate wiring 131 may be a wiring formed of a semiconductor such as polysilicon doped with impurities.

[0123] The active-side gate wiring 131 may be connected to the peripheral gate wiring 130. In this example, the active-side gate wiring 131 is provided extending in the X-axis direction from one peripheral gate wiring 130 to the other peripheral gate wiring 130 at approximately the center in the Y-axis direction, so as to cross the active section 160. When the active section 160 is divided by the active-side gate wiring 131, the transistor sections 70 and the diode sections 80 may be arranged alternately in the X-axis direction in each divided region.

[0124] 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.

[0125] 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 130 and edge 162. Edge termination structure 90 alleviates electric field concentration on the top 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.

[0126] FIG. 11 is an enlarged view of region D in FIG. 10. Region D is a region including a transistor section 70, a diode section 80, and an active-side gate wiring 131. 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 131 provided above the upper surface of the semiconductor substrate 10. The emitter electrode 52 and the active-side gate wiring 131 are provided separately from each other.

[0127] An interlayer insulating film is provided between the emitter electrode 52 and the active-side gate wiring 131 and the upper surface of the semiconductor substrate 10, but is not shown in Fig. 11. In this example, contact holes 54 are provided in the interlayer insulating film so as to penetrate the interlayer insulating film. In Fig. 11, each contact hole 54 is hatched with diagonal lines.

[0128] 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.

[0129] The active side gate wiring 131 is connected to the gate trench portion 40 through a contact hole provided in the interlayer insulating film. The active side gate wiring 131 may be connected to the gate conductive portion of the gate trench portion 40 at the tip portion 41 of the gate trench portion 40 in the Y-axis direction. The active side gate wiring 131 is not connected to the dummy conductive portion in the dummy trench portion 30.

[0130] The emitter electrode 52 is formed of a material containing metal. FIG. 11 shows the area where the emitter electrode 52 is provided. For example, at least a portion of the emitter electrode 52 is formed of aluminum or an aluminum-silicon alloy, such as a metal alloy such as AlSi or AlSiCu. The emitter electrode 52 may have a barrier metal formed of titanium, a titanium compound, or the like below the region formed 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.

[0131] The well region 11 is provided so as to overlap with the active-side gate wiring 131. 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 131. 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 131. 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.

[0132] 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.

[0133] 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. 11 is the Y-axis direction.

[0134] 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.

[0135] 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. 11 includes both linear dummy trench sections 30 without end portions 31 and dummy trench sections 30 with end portions 31.

[0136] 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.

[0137] 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.

[0138] 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 131 is referred to as the base region 14-e. While FIG. 11 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.

[0139] 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.

[0140] 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).

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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. 11 , the boundary between the cathode region 82 and the collector region 22 is indicated by a dotted line.

[0145] 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.

[0146] Fig. 12 is a diagram showing an example of the ee cross section in Fig. 11. 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.

[0147] 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. 11 .

[0148] 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.

[0149] 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.

[0150] 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.

[0151] 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.

[0152] 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.

[0153] 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. 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 and the on-voltage can be reduced. The accumulation region 16 may be provided so as to cover the entire lower surface of the base region 14 in each mesa portion 60.

[0154] 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.

[0155] 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 the doping concentration of the drift region 18. The buffer region 20 has a peak 25 with a doping concentration higher than that of the drift region 18. The doping concentration of the peak 25 refers to the doping concentration at the apex of the peak 25. Furthermore, 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 substantially (almost) flat.

[0156] In this example, the buffer region 20 has three or more peaks 25 in the depth direction (Z-axis direction) of the semiconductor substrate 10. The peaks 25 of the buffer region 20 are, for example, concentration peaks of hydrogen (protons) or phosphorus. The buffer region 20 may function as a field stop layer that prevents a depletion layer extending from the lower end of the base region 14 from reaching the P+ type collector region 22 and the N+ type cathode region 82. In this specification, the depth position of the upper end of the buffer region 20 is designated Zf. The depth position Zf may be a position where the doping concentration is higher than the doping concentration of the drift region 18.

[0157] 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.

[0158] 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.

[0159] 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.

[0160] 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.

[0161] 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.

[0162] 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.

[0163] 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.

[0164] In this example, the gate trench 40 and the dummy trench 30 are covered with an interlayer insulating film 38 on the upper surface 21 of the semiconductor substrate 10. The bottoms of the dummy trench 30 and the gate trench 40 may have a downwardly convex curved shape (a curved shape in cross section). In this specification, the depth position of the lower end of the gate trench 40 is defined as Zt.

[0165] The drift region 18 may include the flat portion 150 described with reference to FIG. 4 and the like. That is, the drift region 18 has a donor concentration determined mainly by the bulk donor concentration and the hydrogen donor (VOH defect) concentration. The drift region 18 has a hydrogen chemical concentration C H The dopant is locally implanted in the regions other than the drift region 18. Therefore, the doping concentration in these regions is the donor concentration D D is different.

[0166] 13 is a diagram showing an example of the carrier concentration distribution in the depth direction at the position of the FF line in FIG. 12. In FIG. 13, the hydrogen concentration distribution C H The vertical axis in Fig. 13 is a logarithmic scale.

[0167] The carrier concentration distribution in the buffer region 20 of this example has multiple peaks 25 located at different positions in the depth direction. The peaks 25 are donor concentration peaks. The peaks 25 may contain hydrogen as an impurity. By providing multiple peaks 25, it is possible to further prevent the depletion layer from reaching the collector region 22. The second donor peak 111 may function as any of the peaks 25 in the buffer region 20.

[0168] As an example, the second donor peak 111 may function as the peak farthest from the lower surface 23 of the semiconductor substrate 10 among the multiple peaks 25 in the buffer region 20. The flat portion 150 is disposed between the second donor peak 111 and the first donor peak 121 included in the buffer region 20.

[0169] The second donor peak 111 may have a higher donor concentration than the peak 25 next to the second donor peak 111 and farthest from the lower surface 23 among the multiple peaks 25 in the buffer region 20. By increasing the concentration of the second donor peak 111, it becomes easier to form the flat portion 150. Hydrogen chemical concentration distribution C H may have one or more hydrogen concentration peaks 194 between depth position Z2 and lower surface 23. Hydrogen concentration peaks 194 may be located in buffer region 20. Hydrogen concentration peaks 194 may be located at the same depth position as peak 25.

[0170] The accumulation region 16 in this example has multiple peaks 26. The peaks 26 are peaks of donor concentration. The first donor peak 121 in this example is located closer to the lower surface 23 than the accumulation region 16. A region 180 having a lower doping concentration than the flat portion 150 may be provided between the first donor peak 121 and the accumulation region 16. The doping concentration of the region 180 is set to a value less than the bulk donor concentration N B0 It may be.

[0171] The semiconductor device 100 may also use a non-doped substrate as the semiconductor substrate 10, in which the entire semiconductor ingot is not doped with a dopant such as phosphorus (P) during the manufacturing process. In this case, the base doping concentration Dn of the region 180 is set to a value equal to or greater than the bulk doping concentration N B0 The base doping concentration Dn is, for example, 1×10 10 atoms / cm 3 That's it, 5 x 10 12 atoms / cm 3 The base doping concentration Dn is 1×10 11 atoms / cm 3 The base doping concentration Dn may be 5×10 or more. 12 atoms / cm 3 It may be the following:

[0172] FIG. 14 is a diagram showing an example of the gg cross section in FIG. 10. The cross section shown in FIG. 14 is an XZ plane including edge termination structure 90 and transistor section 70. Note that peripheral gate wiring 130 is disposed above semiconductor substrate 10, between edge termination structure 90 and transistor section 70. Peripheral gate wiring 130 is provided separately from emitter electrode 52. Also, well region 11 is disposed on top surface 21 of semiconductor substrate 10, between edge termination structure 90 and transistor section 70. In this example, well region 11 is provided in a range shallower than the trench section. The structure of transistor section 70 is similar to that of transistor section 70 described with reference to FIGS. 10 to 12.

[0173] Edge termination structure 90 is provided with multiple guard rings 92, multiple field plates 94, and a channel stopper 174. In edge termination structure 90, a collector region 22 may be provided in a region that contacts bottom surface 23. Each guard ring 92 may be provided on top surface 21 to surround active portion 160. Multiple guard rings 92 may have the function of spreading a depletion layer generated in active portion 160 outward from semiconductor substrate 10. This makes it possible to prevent electric field concentration within semiconductor substrate 10, and improve the breakdown voltage of semiconductor device 100.

[0174] The guard ring 92 in this example is a P-type semiconductor region formed by ion implantation near the upper surface 21. The depth of the bottom of the guard ring 92 may be shallower than the bottoms of the gate trench portion 40 and the dummy trench portion 30.

[0175] The upper surface of the guard ring 92 is covered with the interlayer insulating film 38. The field plate 94 is made of a conductive material such as metal or polysilicon. The field plate 94 may be made of the same material as the emitter electrode 52. The field plate 94 is provided on the interlayer insulating film 38. The field plate 94 is connected to the guard ring 92 through a through-hole provided in the interlayer insulating film 38.

[0176] The channel stopper 174 is provided so as to be exposed on the top surface 21 and the side surface of the edge 162. The channel stopper 174 is an N-type region having a doping concentration higher than that of the drift region 18. The channel stopper 174 has the function of terminating the depletion layer generated in the active portion 160 at the edge 162 of the semiconductor substrate 10.

[0177] In this example, second peak 141 of the hydrogen chemical concentration is located between the bottom of well region 11 and bottom surface 23 of semiconductor substrate 10. Second peak 141 may also be provided in edge termination structure 90. Second peak 141 may also be provided between edge termination structure 90 and transistor portion 70. Second peak 141 may be provided across the entire XY plane of semiconductor substrate 10. Passage region 106 shown in FIG. 1 and other figures is formed from bottom surface 23 of semiconductor substrate 10 to second peak 141.

[0178] FIG. 15 is a diagram showing another example of the gg cross section in FIG. 10. In this example, well region 11 is provided deeper than the bottom ends of gate trench portion 40 and dummy trench portion 30. The other structure may be the same as the example of FIG. 14. In this cross section, at least one trench portion may be located inside well region 11. In the example of FIG. 15, one trench portion closest to edge termination structure portion 90 is located inside well region 11.

[0179] In this example, the second peak 141 is located between the lower end of the well region 11 and the upper surface 21 of the semiconductor substrate 10. In another example, the second peak 141 may be located between the lower end of the well region 11 and the lower surface 23 of the semiconductor substrate 10.

[0180] 16 is a diagram showing an example of a manufacturing method for the semiconductor device 100. The manufacturing method of this example includes a substrate preparation step S1600, a device manufacturing step S1606, a concentration measurement step S1602, and an implantation amount calculation step S1604.

[0181] In the substrate preparation step S1600, the semiconductor substrate 10 is prepared. The semiconductor substrate 10 is, for example, an MCZ substrate. In the concentration measurement step S1602, the oxygen chemical concentration C OX In the concentration measuring step S1602, the oxygen chemical concentration may be measured by FTIR (infrared absorption spectroscopy). In the concentration measuring step S1602, the substrate resistance value (Ω·cm) of the semiconductor substrate 10 may further be measured.

[0182] In the implantation dose calculation step S1604, the dose of the charged particle beam to be implanted at the depth position Z1 is calculated based on the oxygen chemical concentration measured in S1602. As described above, the concentration of VOH defects formed can be controlled by the dose of the charged particle beam. In the implantation dose calculation step S1604, the dose of the charged particle beam may be calculated so that the substrate resistance value of the flat portion 150 described with reference to FIG. 4 and the like becomes a predetermined target resistance value. The target resistance value may be set by the manufacturer of the semiconductor device 100. The substrate resistance value of the flat portion 150 has a one-to-one correspondence with the donor concentration of the flat portion 150. Therefore, a donor concentration increase amount is determined so that the substrate resistance value of the flat portion 150 becomes the target resistance value. The relationship between the dose of the charged particle beam, the donor concentration increase amount, and the oxygen chemical concentration can be experimentally obtained in advance, as shown in FIGS. 6 and 7. In the implantation dose calculation step S1604, the dose of the charged particle beam may be calculated based on the previously obtained relationship.

[0183] Substituting the above equations (11) and (12) into equation (2), equation (13) is obtained. N VOH =c×(D H ) d +e×(D H ) f ×C OX ...Equation (13) Furthermore, equations (1) to (13) become equation (14). N F -N B0 =c×(D H ) d +e×(D H ) f ×C OX ...Equation (14)

[0184] Final doping concentration N F is the setpoint, and the bulk donor concentration N B0 is known from measurements or semiconductor wafer specifications. OX are known from the measurement in S1602. The parameters c, d, e, and f can be experimentally obtained in advance as described above. Therefore, the variables in equation (14) are the implantation amount of charged particles (in this example, the dose D of hydrogen ions) H ) is the only parameter. By solving equation (14) numerically, the amount of injected charged particles can be calculated. The amount of injected charged particles D obtained from equation (14) is H may have a width (error) that reflects the dispersion of the values ​​of each data in the fitting of Equation (8), Equation (10), and Equation (11). That is, the injection dose D of charged particles H is within a range of, for example, ±50% of the value obtained from equation (13) or equation (14), it can be considered to be the value obtained from equation (13) or equation (14).

[0185] The device manufacturing step S1606 of this example includes a particle implantation step S1608, a hydrogen implantation step S1610, and a heat treatment step S1612. The device manufacturing step S1606 includes steps of forming each of the components described with reference to FIGS. 10 to 12, but these are omitted in FIG.

[0186] In the particle implantation step S1608, a charged particle beam is implanted from the lower surface 23 of the semiconductor substrate 10 so as to pass through more than half of the thickness of the semiconductor substrate 10 in the depth direction. In S1608, hydrogen ions such as protons may be implanted as the charged particle beam. This forms the second peak 141 shown in FIG. 2. Also, the vacancy concentration N V The dose of the charged particle beam in step S1608 is adjusted to the dose calculated in step S1604. This allows vacancies to be formed at a concentration such that the flat portion 150 has the target resistance value.

[0187] When the charged particle beam is an electron beam, the second peak 141 is not formed. Even in this case, vacancies are formed at a concentration according to the injection amount of the electron beam. Therefore, by adjusting the injection amount of the electron beam, vacancies can be formed at a concentration such that the flat portion 150 has a target resistance value.

[0188] In hydrogen implantation step S1610, hydrogen ions are implanted into the lower surface 23 of the semiconductor substrate 10. In step S1608, hydrogen ions are implanted at depth position Z2 described with reference to FIG. 1 etc. In hydrogen implantation step S1610, hydrogen ions may be implanted at a concentration sufficient to sufficiently terminate the vacancies formed in step S1608. Particle implantation step S1608 and hydrogen implantation step S1610 are performed before heat treatment step S1612.

[0189] In heat treatment step S1612, the semiconductor substrate 10 is heat-treated. The heat treatment temperature in heat treatment step S1612 may be 350° C. or higher and 380° C. or lower. By using this method, even if the oxygen chemical concentration of the semiconductor substrate 10 varies, the resistance value of the flat portion 150 can be adjusted to a target value.

[0190] 12, the structure on the upper surface 21 side of the semiconductor substrate 10 may be formed. The structure on the upper surface 21 side may include each trench portion, the emitter region 12, the base region 14, the accumulation region 16, the interlayer insulating film 38, and the emitter electrode 52. Furthermore, the cathode region 82 and the collector region 22 may be formed before the particle implantation step S1608. In the particle implantation step S1608, the charged particle beam may be implanted at a depth position Z1 that is closer to the lower surface 23 than the lower end of the gate trench portion 40. This makes it possible to suppress damage caused by the implantation of the charged particle beam from affecting the gate insulating film 42.

[0191] FIG. 17 is a diagram showing another example of a method for calculating the implantation dose of a charged particle beam. In this example, the charged particle beam is hydrogen ions. FIG. 17 includes an upper graph showing the relationship between the oxygen chemical concentration and the donor concentration increase amount, and a lower graph showing the relationship between the hydrogen ion dose and the reciprocal of the oxygen chemical concentration. The upper graph is an enlarged view of a portion of the graph in FIG. 6.

[0192] In the upper graph, the target value of the donor concentration increase is indicated by a dashed line. The target increase is the amount of increase required to achieve the target resistance value of the flat portion 150. From the upper graph, the oxygen chemical concentration corresponding to the target increase is obtained on lines 602 and 603. The lower graph plots the relationship between the reciprocal of the oxygen chemical concentration obtained from the upper graph and the hydrogen ion dose on lines 602 and 603. In addition, the lower graph approximates the relationship between the reciprocal of the oxygen chemical concentration and the hydrogen ion dose with a curve.

[0193] If the relationship shown in the lower graph is obtained in advance, the dose of hydrogen ions to be implanted can be calculated from the oxygen chemical concentration of the semiconductor substrate 10 used in manufacturing the semiconductor device 100. For example, if the oxygen chemical concentration of the semiconductor substrate 10 is 3.7×10 17 atoms / cm 3 In this case, the reciprocal of the oxygen chemical concentration is 2.8×10 -18 From the relationship in the lower graph, 2.8×10 -18 The corresponding hydrogen ion dose is 4.2 × 10 12 ions / cm 2 The relationship in the lower graph changes depending on the target increase in donor concentration. Therefore, if the relationship in the upper graph is obtained in advance, the hydrogen ion dose to be implanted can be calculated from the target increase in donor concentration and the oxygen chemical concentration.

[0194] Fig. 18 is a diagram showing another example of the manufacturing method of the semiconductor device 100. The manufacturing method of this example further includes an oxygen introduction step S1802 compared to the example shown in Fig. 16. The other steps are the same as those in the example of Fig. 16. The oxygen introduction step S1802 is performed before the particle injection step S1608.

[0195] In the oxygen introduction step S1802, oxygen is introduced into the semiconductor substrate 10. In the oxygen introduction step S1802, oxygen may be introduced into the semiconductor substrate 10 by heat-treating the semiconductor substrate 10 in an oxygen-containing atmosphere. In the oxygen introduction step S1802, oxygen may be introduced so that the oxygen chemical concentration of the semiconductor substrate 10 falls within a predetermined range. By introducing oxygen into the semiconductor substrate 10, it becomes easier to adjust the donor concentration of the flat portion 150. For example, even if the oxygen chemical concentration in the semiconductor substrate 10 prepared in S1600 is low and VOH defects cannot be sufficiently formed, the oxygen chemical concentration can be increased by introducing oxygen into the semiconductor substrate 10.

[0196] The oxygen chemical concentration introduced in oxygen introduction step S1802 (referred to as introduction concentration) may be higher than the oxygen chemical concentration in the semiconductor substrate 10 before oxygen introduction step S1802 (referred to as original concentration). The introduction concentration can be precisely controlled by the conditions of the heat treatment, such as the temperature, time, and oxygen concentration in the atmosphere, described above. Therefore, by making the ratio of the introduction concentration higher than the original concentration, it is possible to reduce variations in the oxygen chemical concentration in the semiconductor substrate 10. The introduction concentration may be at least two times, at least five times, or at least ten times the original concentration.

[0197] In oxygen introducing step S1802, oxygen may be introduced into the semiconductor substrate 10 in accordance with the oxygen chemical concentration measured in concentration measuring step S1602. For example, oxygen may be introduced so that the sum of the oxygen chemical concentration introduced in oxygen introducing step S1802 and the oxygen chemical concentration measured in concentration measuring step S1602 becomes a predetermined target value. In concentration measuring step S1802, the oxygen chemical concentration of the semiconductor substrate 10 after oxygen introducing step S1802 has been performed may be measured. In this case, the injection amount of the charged particle beam can be calculated with even greater accuracy.

[0198] FIG. 19 is a diagram showing an example of device manufacturing step S1606. In this example, device manufacturing step S1606 includes a top-side process S1902 and a bottom-side process S1904. The top-side process S1902 is a step for forming a structure on the top surface 21 side of the semiconductor substrate 10. The structure on the top surface 21 side includes, for example, a trench portion, an emitter region 12, a base region 14, an accumulation region 16, a well region 11, an emitter electrode 52, a gate wiring, a guard ring 92, a field plate 94, a channel stopper 174, and an interlayer insulating film 38. The bottom-side process S1904 is a step for forming a structure on the bottom surface 23 side of the semiconductor substrate 10. The structure on the bottom surface 23 side includes, for example, a cathode region 82, a collector region 22, a buffer region 20, and a collector electrode 24.

[0199] In this example, the oxygen introduction step S1802 is performed in the top surface side process S1902. The oxygen introduction step S1802 may also serve as a heat treatment step performed to form the structure on the top surface 21 side. For example, the oxygen introduction step S1802 may be a heat treatment step performed after dopants are implanted into the emitter region 12, the base region 14, or the accumulation region 16.

[0200] In this example, the bottom-side process S1904 includes a particle implantation step S1608, a hydrogen implantation step S1610, and a heat treatment step S1612. The hydrogen implantation step S1610 and the heat treatment step S1612 may be part of a process for forming the buffer region 20. That is, the hydrogen implantation step S1610 may form any of the peaks 25 of the buffer region 20. The heat treatment step S1612 may be performed after implanting hydrogen ions into the positions of the multiple peaks 25 of the buffer region 20.

[0201] FIG. 20 is a diagram showing another example of device manufacturing step S1606. Device manufacturing step S1606 of this example differs from the example of FIG. 19 in that oxygen introduction step S1802 is performed in the bottom-side process S1904. The other steps are the same as those of the example of FIG. 19. Oxygen introduction step S1802 may also serve as a heat treatment step performed to form the structure on the bottom surface 23 side. For example, oxygen introduction step S1802 may be a heat treatment step performed after dopant is implanted into the collector region 22 or the cathode region 82. In this example, oxygen introduction step S1802 is also performed before hydrogen implantation step S1610. Oxygen introduction step S1802 may be performed before charged particle implantation step S1608.

[0202] 21 is a diagram showing the relationship between the oxygen contribution rate ξ and the depth position Z1 at which the second peak 141 is located. In FIG. 21, when the hydrogen ion dose is 3×10 14 ions / cm 2 , 1×10 14 ions / cm 2 , 3×10 13 ions / cm 2 , 1×10 13 ions / cm 2 , 3×10 12 ions / cm 2 , or 1×10 12 ions / cm 2 10 shows the relationship between the oxygen contribution ratio ξ and the depth position Z1 for each of the cases.

[0203] As shown in Figures 8 and 9, the oxygen contribution ratio ξ changes depending on the depth position Z1. The points plotted as squares in Figure 8 are plotted at a depth position of Z1 = 100 μm in Figure 21. The points plotted as squares in Figure 9 are plotted at a depth position of Z1 = 50 μm in Figure 21. Furthermore, a plot at a depth position of Z1 = 150 μm is added to Figure 21. When the hydrogen ion dose is 3 × 10 14 ions / cm 2 , 1×10 14 ions / cm 2 , and 1×10 12 ions / cm2 The plots for are omitted in Fig. 21. The lines obtained by linearly approximating these plots for each hydrogen ion dose using the least squares method (horizontal axis is linear, vertical axis is common logarithm) are shown as bold lines in Fig. 21. The oxygen contribution ratio ξ may decrease exponentially with respect to the depth position Z1.

[0204] The relationship shown in FIG. 21 and the dose D of hydrogen ions relative to the depth position Z1 H The oxygen contribution ratio ξ can be detected from the depth position Z1. The depth position Z1 can be measured from the peak position in the hydrogen chemical concentration distribution of the semiconductor device 100. H can be measured by integrating the hydrogen chemical concentration in the depth direction for the mountain-shaped peak of the hydrogen chemical concentration having the apex at the depth position Z1. The integration range may be, for example, the full width at 10% of the peak value of the hydrogen chemical concentration (FW10%M). Alternatively, the dose D H may be the peak value of the hydrogen chemical concentration multiplied by the full width at half maximum (FWHM).

[0205] For example, the depth position Z1 is 120 μm, and the dose D H is 5 x 10 12 ions / cm 2 The case is shown by the black circle in Figure 21. In this case, the oxygen contribution ratio ξ is approximately ξ = 1.2 × 10 -4 Let this value be ξ1.

[0206] Figure 22 shows the vacancy concentration N V 21 is a diagram showing the relationship between the hydrogen ion dose of 3×10 14 ions / cm 2 , 1×10 14 ions / cm 2 , 3×10 13 ions / cm 2 , 1×10 13 ions / cm 2 , 3×10 12 ions / cm 2 , or 1×10 12 ions / cm2 8 and 9, the relationship between the oxygen contribution ratio ξ and the depth position Z1 is shown. V The vacancy concentration N V may decrease exponentially with respect to the depth position Z1.

[0207] The relationship shown in FIG. 22 and the dose D of hydrogen ions relative to the depth position Z1 H From the depth position Z1, the vacancy concentration N V The depth position Z1 and the dose D H can be measured from the semiconductor device 100 as described in FIG. 21. For example, when the depth position Z1 is 120 μm and the dose D H is 5 x 10 12 ions / cm 2 This case is shown by the black circle in Figure 22. In this case, the vacancy concentration N V is approximately N V =7×10 12 ions / cm 3 The value is N V Let's say it's 1.

[0208] Calculated oxygen contribution ratio ξ1 and vacancy concentration N V 1 and the oxygen chemical concentration C OX From this, the VOH defect concentration N VOH 1 (the first value of the hydrogen donor concentration) can be calculated. That is, the first value N VOH 1 is the sum of the oxygen chemical concentration in the flat portion 150 multiplied by the oxygen contribution rate and the vacancy concentration in the flat portion 150. OX For example, the oxygen chemical concentration C OX is 2 x 10 17 atoms / cm 3 In the case of VOH defect concentration N VOH 1 becomes as follows: N VOH 1=7×10 12 +1.2×10 -4x2x10 17 =3.1×10 13 (atoms / cm 3 )

[0209] On the other hand, the VOH defect concentration N VOH can be measured from the characteristics of the semiconductor device 100. For example, the VOH defect concentration N VOH is the final doping concentration N F and the bulk donor concentration N B0 Difference from (N F -N B0 ) can be measured from the final doping concentration N F and the bulk donor concentration N B0 can be measured from the semiconductor device 100. The measured VOH defect concentration N VOH N VOH 2 (the second value of the hydrogen donor concentration). That is, the second value N VOH 2 is the difference between the donor concentration in the flat portion 150 and the bulk donor concentration. For example, the final doping concentration N F is 7 x 10 13 (atoms / cm 3 ), bulk donor concentration N B0 is 2 x 10 12 (atoms / cm 3 ), VOH defect concentration N VOH 2 becomes as follows: N VOH 2=7×10 13 -2×10 12 =6.8×10 13 (atoms / cm 3 ) Calculated N VOH 1 is the actual measured value of N VOH If the calculated oxygen contribution ξ1 and vacancy concentration N V 1 is generally correct. That is, the second value of the hydrogen donor concentration, N VOH 2, the first value of the hydrogen donor concentration, N VOH Ratio of 1 to N VOH 1 / N VOH 2, 0.1≦N VOH 1 / N VOH If 2≦10, it is considered a good match. In the above example, NVOH 1 / N VOH 2=3.1×10 13 / 6.8×10 13 ≒0.46, and the calculated oxygen contribution ratio ξ1 and vacancy concentration N V 1 is correct.

[0210] Calculated N VOH 1 is the actual measured value of N VOH 2, or if the calculated oxygen contribution ratio ξ1 is within a predetermined range, it can be determined that the oxygen contribution ratio ξ of the semiconductor device 100 is within that range. VOH 1 is the actual measured value of N VOH 2, or the calculated vacancy concentration N V If 1 is within a predetermined range, the vacancy concentration N V 1 can be determined to be within the range.

[0211] 0.2≦N VOH 1 / N VOH When 2≦5, the calculated N VOH 1 is the actual measured value of N VOH It may be judged that the value is sufficiently consistent with 2. Also, 0.3≦N VOH 1 / N VOH When 2≦3, the calculated N VOH 1 is the actual measured value of N VOH It may be judged to be sufficiently consistent with 2. 0.5≦N VOH 1 / N VOH If 2≦2, the calculated N VOH 1 is the actual measured value of N VOH It may be judged to be a sufficient match to 2.

[0212] In formula (1), the contribution of oxygen to the generation of hydrogen donors (VOH defects) is taken into account. However, as will be described later, there may be cases where the contribution of carbon to the generation of hydrogen donors cannot be ignored, such as when the depth position Z1 is shallow, when the hydrogen ion dose is high, or when the carbon chemical concentration is high. The carbon contribution ratio η is the ratio of the chemical concentration of carbon that contributes to the doping concentration of hydrogen donors to the chemical concentration of carbon. The carbon contribution ratio η may be considered to be the ratio of the chemical concentration of carbon atoms that contributed to the formation of hydrogen donors to the chemical concentration of all carbon atoms in a given region (e.g., a depth position from the bottom or top surface). The carbon contribution ratio η may also be the ratio of the increase in the concentration of hydrogen donors to the increase in the chemical concentration of carbon when the carbon chemical concentration is increased. The carbon contribution ratio may be a value of 0.01% to 10% (i.e., 0.0001 or more and 0.1 or less).

[0213] Figure 23 shows the hydrogen chemical concentration C after heat treatment at the position indicated by the line AA in Figure 1. H , oxygen chemical concentration C OX , carbon chemical concentration C C , contributing oxygen concentration N OX , contributing carbon concentration N C , and VOH defect concentration N VOH The semiconductor device 100 of this example has a carbon chemical concentration C C and contributing carbon concentration N C The rest of the configuration and manufacturing method are the same as those of the semiconductor device 100 described with reference to FIGS.

[0214] Carbon is often introduced during the manufacture of the ingot and is often uniformly distributed within the semiconductor substrate 10. The carbon chemical concentration C C may be uniform throughout the semiconductor substrate 10. In another example, the carbon chemical concentration C C may monotonically increase or decrease from the lower surface 23 to the upper surface 21 of the semiconductor substrate 10. Carbon in the vicinity of the upper surface 21 or the lower surface 23 of the semiconductor substrate 10 may be released to the outside of the semiconductor substrate 10. C is the oxygen chemical concentration C OXSimilarly, in the vicinity of the upper surface 21 and the lower surface 23, the carbon chemical concentration C may decrease monotonically toward the upper surface 21 and the lower surface 23. In the vicinity of the other than the upper surface 21 and the lower surface 23, the carbon chemical concentration C C may be uniform, as described above, or may be monotonically increasing or decreasing.

[0215] Carbon chemical concentration C in the flat area 150 C is 1 x 10 13 atoms / cm 3 That's it, 1 x 10 16 atoms / cm 3 The carbon chemical concentration C C is 1 x 10 14 atoms / cm 3 The carbon chemical concentration C C is 5 x 10 15 atoms / cm 3 may be less than or equal to 2 x 10 15 atoms / cm 3 The carbon chemical concentration C may be less than or equal to C is the oxygen chemical concentration C OX The smaller the carbon chemical concentration, the better. C is the oxygen chemical concentration C OX It is to be noted that the carbon chemical concentration C of the semiconductor substrate 10 in this specification may be 1 / 100 or less, or may be 1 / 1000 or less. C is defined, unless otherwise specified, the entire area between the second peak 141 and the first peak 133 satisfies the defined carbon chemical concentration. The entire area between the second peak 141 and the lower surface 23 may also satisfy the defined carbon chemical concentration, and the entire semiconductor substrate 10 may also satisfy the defined carbon chemical concentration.

[0216] Contributing carbon concentration N C refers to the concentration of carbon that contributes to the formation of VOH defects. Carbon chemical concentration C C It has been experimentally confirmed that the concentration of VOH defects may change when the contributing carbon concentration N C and carbon chemical concentration C C The ratio of N to N is the carbon contribution ratio η.C / C C The carbon contribution ratio η is greater than or equal to 0 and less than or equal to 1. The carbon contribution ratio η is a dimensionless quantity.

[0217] Contributing carbon concentration N C The distribution of carbon chemical concentration C C For example, the distribution of the contributing carbon concentration N C may be uniform in the depth direction of the semiconductor substrate 10, or may increase or decrease monotonically. C may have a distribution with a peak at a predetermined depth position.

[0218] Next, the range of the carbon contribution ratio η in the semiconductor substrate 10 will be described. VOH Let be equation (2a). N VOH =N V +ξC OX +ηC C ...Equation (2a) The VOH defect concentration N in Eq. (2a) VOH is the VOH defect concentration N VOH , the carbon chemical concentration C C and the carbon contribution ratio η. In other words, the hydrogen donor concentration that increases due to the presence of carbon is calculated by adding the VOH defect concentration N VOH Although the hydrogen donors generated by the contribution of carbon are not limited to VOH defects, in equation (2a), the hydrogen donor concentration that increases due to the presence of carbon is added to the VOH defect concentration N VOH It is included in.

[0219] Figure 24 shows the relationship between the donor concentration increase and the carbon chemical concentration C C The method for measuring the donor concentration increase in this example is the same as in the example of FIG. 6. Also, the carbon chemical concentration C C is distributed uniformly in the depth direction.

[0220] In FIG. 24, the depth position Z1 is set to 50 μm. In this example, the dose of hydrogen ions at the depth position Z1 is 3×10 12 ions / cm 2 , 1×10 13 ions / cm 2 , 3×10 13 ions / cm 2 The dose of hydrogen ions is 3×10 13 ions / cm 2 The sample is shown in plot 621, and the dose of hydrogen ions is 1×10 13 ions / cm 2 The sample is shown in plot 622, and the dose of hydrogen ions is 3×10 12 ions / cm 2 The sample is shown in plot 623. The size of each plot is proportional to the oxygen chemical concentration C OX As shown in Figure 24, the carbon chemical concentration C C The donor concentration increase is substantially (almost) linearly proportional to the amount of the donor.

[0221] In the example of Figure 24, the carbon chemical concentration C C In Figure 24, the dose of hydrogen ions is 3 × 10 13 ions / cm 2 The example is approximated by a line 611, and the dose of hydrogen ions is 1×10 13 ions / cm 2 The example is approximated by a line 612, and the dose of hydrogen ions is 3 × 10 12 ions / cm 2 The example is approximated by a straight line 613.

[0222] Each line is expressed by equation (8a). N VOH = a × C C +b...Formula (8a) In this case, the slope a and intercept b of each line calculated by least squares fitting are as follows: Straight line 611: a=5.00851×10 -2, b=6.46656×10 13 Straight line 612: a=2.35891×10 -2 , b=4.14509×10 13 Straight line 613:a=7.13212×10 -3 , b=2.26076×10 13

[0223] As shown in Fig. 24, the carbon chemical concentration C C and oxygen chemical concentration C OX For example, there is no strong correlation between the carbon chemical concentration C C is 6 x 10 14 atoms / cm 3 and 8×10 14 atoms / cm 3 As in the case of C When comparing semiconductor substrates 10 with the same order of oxygen chemical concentration C OX (plot size) is 9 × 10 15 atoms / cm 3 and 2.4 x 10 17 atoms / cm 3 On the other hand, the carbon chemical concentration C C is 2.5 x 10 15 atoms / cm 3 The semiconductor substrate 10 has a carbon chemical concentration C C However, the oxygen chemical concentration C OX is 4 x 10 17 atoms / cm 3 and the oxygen chemical concentration C OX The difference is not that big.

[0224] Figure 25 shows the relationship between the donor concentration increase and the oxygen chemical concentration C OX In this example, the plots shown in FIG. 24 are plotted using the carbon chemical concentration C C is small (1×10 15 atoms / cm 3 (below) group and carbon chemical concentration C Cis large (2×10 15 atoms / cm 3 The donor concentration increase and oxygen chemical concentration C OX The relationship between is approximated by a straight line.

[0225] In FIG. 25, the dose of hydrogen ions is 3×10 13 ions / cm 2 Among the plots, the carbon chemical concentration C C The group with the highest carbon chemical concentration C C The group with a small dose of hydrogen ions is shown by line 641. 13 ions / cm 2 Among the plots, the carbon chemical concentration C C The group with the highest carbon chemical concentration C C The group with a small dose of hydrogen ions is shown by line 642. 12 ions / cm 2 Among the plots, the carbon chemical concentration C C The group with the highest carbon chemical concentration is shown by line 633. C The small group is shown by line 643.

[0226] When each line is expressed by equation (8), the slope a and intercept b of each line are as follows: Straight line 631: a=3.64419×10 -4 , b=4.15739×10 13 Straight line 641: a=2.80673×10 -4 , b=4.15739×10 13 Straight line 632:a=2.04534×10 -4 , b=2.21483×10 13 Straight line 642: a=1.67965×10 -4 , b=2.21483×10 13 Straight line 633:a=8.60908×10 -5 , b=8.32518×10 13 Straight line 643:a=8.05915×10 -5 , b=8.32518×10 13 When the dose of hydrogen ions is equal, the intercept, vacancy concentration N V are essentially (almost) the same value. As in the case of oxygen, as the carbon chemical concentration approaches 0, the vacancy concentration N V It is natural to think that converges to a constant value.

[0227] Carbon chemical concentration C C The slope of the line in the group with a large carbon chemical concentration C C The slope of the line for the small group is larger than that of the line for the small group. C The donor concentration increase increases as the hydrogen ion dose increases. OX VOH defect concentration N VOH The ratio of the increase (the slope of the line) is increasing.

[0228] The slope a of each line is the oxygen contribution ratio ξ. C The oxygen contribution ratio ξ is assumed to be α times higher due to the increase in VOH defect concentration N VOH becomes equation (2b). N VOH =N V +αξC OX ...Equation (2b) Comparing equations (2a) and (2b), we obtain equation (15). ξC OX +ηC C =αξC OX η=(α-1)(C OX / C C )ξ...Equation (15)

[0229] As shown in equation (15), the carbon contribution ratio η is the oxygen chemical concentration C per unit carbon chemical concentration. OX / C Cand the increase in ξ, (α-1)ξ. In other words, the carbon contribution η is expressed as the product of the oxygen chemical concentration C OX and depends on the oxygen contribution ratio ξ.

[0230] As shown in Figure 25, the carbon chemical concentration C C As increases, the oxygen chemical concentration C OX VOH defect concentration N VOH The ratio of the increase in the amount of carbon (the slope of the line ξ) increases by a factor of α, and the contributing carbon concentration N C =ηC C increases. In other words, the carbon chemical concentration C C Not only does the increase in oxygen chemical concentration C OX The contribution of carbon concentration N C increases, and the contributing carbon concentration N C VOH defect concentration N VOH This suggests that the donor increased due to the contribution of carbon may be a different donor from the VOH defect. In this specification, the donor increased due to the contribution of carbon may be referred to as the VOH-C defect.

[0231] 26 is a diagram showing the relationship between the hydrogen ion dose at the depth position Z1 and the carbon contribution ratio η. In FIG. 26, the characteristics of three semiconductor substrates 10 with the depth position Z1 being 50 μm, 100 μm, and 150 μm are shown. In this example, the hydrogen ion dose D at the depth position Z1 is 0.01 μm, which is the same as the oxygen contribution ratio ξ in FIG. 8. H The carbon contribution rate η is approximated by a power function.

[0232] 26, the relationship between the hydrogen ion dose and the carbon contribution rate η when Z1=50 μm is approximated by a curve 811, the relationship between the hydrogen ion dose and the carbon contribution rate η when Z1=100 μm is approximated by a curve 812, and the relationship between the hydrogen ion dose and the carbon contribution rate η when Z1=150 μm is approximated by a curve 813. Each curve 801 is expressed by equation (15). In this case, coefficients g and h of each curve are as follows: η=g×(D H ) h ...Equation (15) Curve 811:g=2.57839×10 -13 , h=7.95528×10 -1 Curve 812:g=1.35314×10 -21 , h=1.38598 Curve 813:g=3.49381×10 -31 , h=2.07102

[0233] Figure 27 shows the carbon chemical concentration C C The oxygen contribution ratio ξ and hydrogen ion dose D in the small group H This is a graph showing the relationship between the carbon chemical concentration C C As explained in Figure 25, the group with a low carbon chemical concentration C C is 1×10 15 atoms / cm 3 The oxygen contribution ratio ξ is the value when there is no influence of the carbon chemical concentration, so the carbon chemical concentration C C 27, the characteristics of the semiconductor substrate 10 for three depth positions Z1 of 50 μm, 100 μm, and 150 μm are shown by curves 821, 822, and 823, respectively. Each curve is a curve obtained by approximating each plot with a power function, as in the example of FIG.

[0234] Figure 28 shows the carbon chemical concentration C C Vacancy concentration N in the small group V and hydrogen ion dose D H This is a graph showing the relationship between the vacancy concentration N V is the value when there is no influence of the carbon chemical concentration, so the carbon chemical concentration C C 28, the characteristics of three types of semiconductor substrate 10 where the depth position Z1 is 50 μm, 100 μm, and 150 μm are shown by curves 831, 832, and 833, respectively. Each curve is a curve obtained by approximating each plot with a power function, as in the example of FIG.

[0235] Each of the curves explained in Figures 26 to 28 can be expressed as a power function, so equation (2a) becomes equation (13a). N VOH =c×(D H ) d +e×(D H ) f ×C OX +g×(D H ) h ×C C ...Equation (13a) Furthermore, from equation (1), equation (13a) becomes equation (14a). N F -N B0 =c×(D H ) d +e×(D H ) f ×C OX +g×(D H ) h ×C C ...Equation (14a)

[0236] Final doping concentration N F is the setpoint, and the bulk donor concentration N B0 is known from measurements or semiconductor wafer specifications. OX and carbon chemical concentration C C can be obtained by measuring the respective concentrations in the semiconductor substrate 10 by a SIMS method or the like. The parameters c, d, e, f, g, and h can be obtained experimentally in advance. Therefore, the variables in equation (14a) are the implantation amount of charged particles (in this example, the dose D of hydrogen ions) H ), and the right side of equation (14a) is a constant that does not change with the amount of injection.

[0237] By numerically solving equation (14a), the final doping concentration N F The dose of charged particles to be implanted into the semiconductor substrate 10 can be calculated for the set value of D. H may have a width (error) that reflects the variation in the values ​​of each data in each fitting described in FIGS. 26 to 28. That is, the injection amount D Hcan be considered to be the value obtained from equation (13a) or equation (14a) if it is within a range of, for example, ±50% of the value obtained from equation (13a) or equation (14a).

[0238] Fig. 29 is a diagram showing an example of a manufacturing method for the semiconductor device 100. The manufacturing method of this example differs from the example described in Fig. 18 in the steps of concentration measurement step S1602 and injection amount calculation step S1604. The steps other than concentration measurement step S1602 and injection amount calculation step S1604 are the same as those in the example of Fig. 18.

[0239] In the concentration measurement step S1602 of this example, the oxygen chemical concentration C OX In addition, the carbon chemical concentration C of the semiconductor substrate 10 C 18 in that the concentration measurement step S1602 further measures the concentration of each of the analytes. Other points are the same as those in the example described in relation to Fig. 18. In the concentration measurement step S1602, each concentration may be measured by an FTIR method (infrared absorption spectroscopy).

[0240] In the implantation amount calculation step S1604, the implantation amount of the charged particle beam to be implanted at the depth position Z1 is calculated based on the oxygen chemical concentration and carbon chemical concentration measured in S1602. As described above, the implantation amount of the charged particle beam can control the concentration of VOH defects to be formed. In the implantation amount calculation step S1604, the implantation amount may be calculated based on the formula (13a) or the formula (14a). In S1604, the substrate resistance value of the flat portion 150 described in FIG. 4 etc. is calculated based on the final doping concentration N F The injection amount of the charged particle beam may be calculated so as to achieve the set value.

[0241] By using this method, even if there is a variation in the bulk donor concentration of the semiconductor substrate 10, the resistance value of the flat portion 150 can be adjusted to a target value. VOH1 , the concentration of actually generated hydrogen donors is N VOH2 The depth position may be included in the flat portion 150. The depth position may be the center of the semiconductor substrate 10 in the depth direction.

[0242] The concentration of hydrogen donors to be generated is N VOH1 From equation (2a) we get equation (16). N shown in equation (16) VOH1 is an example of a third value. N VOH1 =N V +ξC OX +ηC C ...Equation (16) As mentioned above, the vacancy concentration N V , oxygen chemical concentration C OX , carbon chemical concentration C C The oxygen contribution ratio ξ and the carbon contribution ratio η can be obtained by measuring the semiconductor substrate 10. In addition, the concentration N of the actually generated hydrogen donors VOH2 is the donor concentration N of the semiconductor substrate 10 before processing by the above-described manufacturing method. B0 and the donor concentration N F The difference in donor concentration may be measured at the flat portion 150. The donor concentration N B0 can be obtained by SIMS or SR measurement. If SIMS is used, the donor concentration N B0 can be obtained.

[0243] Figure 30 shows the vacancy concentration N V 30 is a diagram showing another example of the relationship between the hydrogen ion dose and the depth position Z1. 14 ions / cm 2 , 1×10 14 ions / cm 2 , 3×10 13 ions / cm 2 , 1×10 13 ions / cm 2 , 3×10 12 ions / cm 2 , or 1×10 12 ions / cm 2The relationship between the oxygen contribution ratio ξ and the depth position Z1 is shown for each of the cases. The relationship in this example is substantially (almost) the same as the relationship shown in FIG. 22. As an example, when the depth position Z1 is 120 μm and the dose D H is 5 x 10 12 ions / cm 2 The case is shown by the black square in Figure 30. In this case, the vacancy concentration N V is approximately N V =6×10 12 ions / cm 3 The value is N V As another example, the depth position Z1 is 23 μm and the dose D H is 3 x 10 12 ions / cm 2 This case is shown by the black diamond in Figure 30. In this case, the vacancy concentration N V is approximately N V =1.3×10 13 ions / cm 3 The value is N V Let's say it's 2.

[0244] 31 is a diagram showing another example of the relationship between the oxygen contribution ratio ξ and the depth position Z1. In FIG. 31, 14 ions / cm 2 , 1×10 14 ions / cm 2 , 3×10 13 ions / cm 2 , 1×10 13 ions / cm 2 , 3×10 12 ions / cm 2 , or 1×10 12 ions / cm 2 31 shows the relationship between the oxygen contribution ratio ξ and the depth position Z1 for each case. In this example, the dependency of the oxygen contribution ratio ξ on the depth position Z1 in the case where the hydrogen ion dose is high is smaller than in the example shown in FIG. 21. In other words, the slope of the straight line shown in FIG. 31 is smaller. As an example, when the depth position Z1 is 120 μm and the dose D H is 5 x 10 12ions / cm 2 The case is shown by the black square in Figure 31. In this case, the oxygen contribution ratio ξ is approximately ξ = 1.1 × 10 -4 This value is defined as ξ2. As another example, the depth position Z1 is 23 μm, and the dose D H is 3 x 10 12 ions / cm 2 This case is shown by the black diamond in Figure 31. In this case, the oxygen contribution ratio ξ is approximately ξ = 1.0 × 10 -4 Let this value be ξ3.

[0245] FIG. 32 is a diagram showing the relationship between the carbon contribution ratio η and the depth position Z1. As with the oxygen contribution ratio ξ, the carbon contribution ratio η decreases exponentially as the depth position Z1 increases. The carbon contribution ratio η is highly dependent on the depth position Z1. Furthermore, the carbon contribution ratio η increases as the hydrogen ion dose increases. As an example, when the depth position Z1 is 120 μm and the dose D H is 5 x 10 12 ions / cm 2 The case is shown by the black square in Figure 32. In this case, the carbon contribution rate η is approximately η = 2.1 × 10 -4 This value is assumed to be η2. As another example, the depth position Z1 is 23 μm, and the dose D H is 3 x 10 12 ions / cm 2 This case is shown by the black diamond in Figure 32. In this case, the carbon contribution rate η is approximately η = 3.0 × 10 -3 This value is called η3.

[0246] As shown in Fig. 30 and Fig. 32, the dependence of the carbon contribution ratio η on the depth position Z1 is V This shows that carbon has a strong interaction with vacancies. As explained in relation to Equation (15) and FIG. 25, the VOH defect concentration N VOH -Oxygen chemical concentration C OXConsidering that the increase in the slope of the characteristics is suggested to be due to donors other than VOH defects, it is speculated that the donors are composed of at least vacancies (V), oxygen (O), hydrogen (H), and carbon (C). As mentioned above, the donors are called VOH-C defects. The VOH-C defect is an example of a hydrogen donor.

[0247] 32, the carbon contribution ratio η is large when the depth position Z1 is shallow and the dose of charged particles (hydrogen ions) is high. Therefore, when the depth position Z1 is shallower than a predetermined value (for example, 100 μm), the carbon chemical concentration C C The predetermined value may be 70 μm or 50 μm. In addition, when the depth position Z1 is shallower than a predetermined value set in advance and the carbon chemical concentration C C is a predetermined value (e.g., 1×10 13 atoms / cm 3 ) or more, the carbon chemical concentration C C The charged particle dose may be set based on the predetermined value of 5×10 13 atoms / cm 3 may be 1 x 10 14 atoms / cm 3 may be.

[0248] Example 1 The depth position Z1 is 120 μm, and the hydrogen ion dose D H is 5 x 10 12 ions / cm 2 Consider the example of oxygen chemical concentration C OX is 4.0 x 10 17 atoms / cm 3 , carbon chemical concentration C C is 2.0 x 10 15 atoms / cm 3 and the final doping concentration N F is 7 x 10 13 / cm 3 is the bulk donor concentration N B0 is 2 x 10 12 / cm 3 is.

[0249] As described above, from the relationships between the black squares and black diamonds in Figures 30, 31, and 32 and the vacancy concentration N V is approximately 6 x 10 12 / cm 3 , the oxygen contribution ratio ξ is approximately 1.1×10 -4 , the carbon contribution is approximately 2.1 × 10 -4 30, 31, and 32 may be experimentally obtained in advance by measuring a plurality of semiconductor substrates 10.

[0250] From equation (16), N VOH1 can be calculated as follows: N VOH1 =6.0×10 12 +1.1×10 -4 x4.0x10 17 2.1×10 -4 x2.0x10 15 =5.04×10 13 / cm 3 Also, N VOH2 can be calculated as follows: N VOH2 =N F -N B0 =7×10 13 -2×10 12 =6.8×10 13 / cm 3 Therefore, N VOH1 / N VOH2 can be calculated as follows: N VOH1 / N VOH2 =5.04×10 13 / 6.8×10 13 =0.74 The above 0.1≦N VOH1 / N VOH2 ≦10, so in Example 1, N VOH1 and N VOH2 It can be determined that there is sufficient agreement.

[0251] Example 2 The depth position Z1 is 23 μm, and the hydrogen ion dose D H is 3 x 10 12 ions / cm 2 Consider the example of oxygen chemical concentration C OX is 1.5 x 10 17 atoms / cm 3 , carbon chemical concentration C C is 5.1 x 10 14 atoms / cm 3 and the final doping concentration N F is 1.4 x 10 14 / cm 3 is the bulk donor concentration N B0 is 7.4 x 10 13 / cm 3 is.

[0252] From the relationships shown in Figures 30, 31, and 32, the vacancy concentration N V is approximately 1.3 x 10 13 / cm 3 , the oxygen contribution ratio ξ is approximately 1.0×10 -4 , the carbon contribution is approximately 3.0 × 10 -3 From equation (16), N VOH1 is 3.0 x 10 13 / cm 3 Also, N VOH2 is 6.6 x 10 13 / cm 3 is. Therefore, N VOH1 / N VOH2 can be calculated as follows: N VOH1 / N VOH2 =3.0×10 13 / 6.6×10 13 =0.45 The above 0.1≦N VOH1 / N VOH2 ≦10, so in Example 2, N VOH1 and N VOH2 It can be determined that there is sufficient agreement.

[0253] N VOH1 / N VOH2is within the range, as in the manufacturing method described in FIG. 29, the oxygen chemical concentration C OX and carbon chemical concentration C C Based on the measurement results of N, it may be determined that the dose of charged particles has been set. VOH1 / N VOH2 may be 0.2 or more, may be 0.3 or more, or may be 0.5 or more. VOH1 / N VOH2 may be 5 or less, may be 3 or less, or may be 2 or less.

[0254] The dose of charged particles taking into account the carbon contribution rate η can be calculated in the same way even when the charged particles are not hydrogen ions. For example, when the charged particles are helium ions, the parameters c to h in equation (13b) are obtained in advance for the depth position Z1 at which the helium ions are implanted. He is the helium ion dose (ions / cm) at the depth position Z1 2 ) N VOH =c×(D He ) d +e×(D He ) f ×C OX +g×(D He ) h ×C C ...Equation (13b) The parameters may be acquired for a plurality of different depth positions Z1.

[0255] In addition, the oxygen chemical concentration C of the semiconductor substrate 10 OX and carbon chemical concentration C C is measured and obtained before the start of the manufacturing process. VOH The helium ion dose D according to the set value He is calculated from equation (13b).

[0256] 33A, 33B, and 33C are graphs showing the helium ion dose dependence of the vacancy concentration, oxygen contribution rate, and carbon contribution rate with respect to the electrical target characteristics. In FIGS. 33B and 33C, three examples are shown in which the depth position Z1 at which helium ions are implanted is Z1=a, Z1=b, and Z1=c. Equations (13), (13a), and (13b) are used to calculate the N to be generated. VOH The target characteristic can be, for example, the breakdown voltage (V B ), IGBT on-voltage (V CE ), switching time (t off ), diode forward voltage drop (V F ), reverse recovery time (t rr ) etc.

[0257] To obtain the target characteristics, a semiconductor device may be manufactured using a flow similar to that shown in Figure 29. That is, the oxygen and carbon concentrations are measured in advance in S1602, and the amount (dose) of helium ions to be implanted is calculated in S1604. Helium ions are implanted at this implantation amount in S1608. Hydrogen ion implantation in S1610 may or may not be performed. In these cases, if the electrical target characteristics are F, then, for example, equation (13b) can be transformed into the following equation: F=Nv´+ξ´C OX +η´C C =c×(D He ) d +e×(D He ) f ×C OX +g×(D He ) h ×C C … Formula (15) The first term on the right side is Nv', which is the vacancy concentration Nv formed by helium ion implantation and heat treatment multiplied by a coefficient used to convert it to the electrical characteristic F. The coefficient part of Cox in the second term is the oxygen contribution ratio ξ' to the target characteristic F, which is the amount obtained by multiplying the oxygen contribution ratio ξ described above by a coefficient used to convert it to the electrical characteristic F. The coefficient part of Cc in the third term is the carbon contribution ratio η' to the target characteristic F, which is the amount obtained by multiplying the carbon contribution ratio η described above by a coefficient used to convert it to the electrical characteristic F. Equation (15) is calculated in advance by creating at least one of the graphs shown in Figures 33A, 33B, and 33C for two to three or more helium ion implantation depths. In other words, the parameters c, d, e, f, g, and h can be experimentally obtained in advance. Therefore, the only variable in Equation (15) is the implantation dose of helium ions, and the right side of Equation (15) is a constant that does not change with the implantation dose.

[0258] The dose of helium ions to be implanted into the semiconductor substrate 10 can be calculated by numerically solving equation (15). He may have a margin (error) reflecting the variation of the values ​​of each data in each fitting described below. That is, the implantation dose D of helium ions He is within the range of, for example, ±50% of the value obtained from equation (15), it can be considered to be the value obtained from equation (15).

[0259] The electrical target characteristic F can be transformed as shown in the following equation for each characteristic in the above example. V B =c×(D He ) d +e×(D He ) f ×C OX +g×(D He ) h ×C C V CE =c×(D He ) d +e×(D He ) f ×C OX +g×(D He ) h ×CC t off =c×(D He ) d +e×(D He ) f ×C OX +g×(D He ) h ×C C V F =c×(D He ) d +e×(D He ) f ×C OX +g×(D He ) h ×C C t rr =c×(D He ) d +e×(D He ) f ×C OX +g×(D He ) h ×C C In these equations, the parameters c to h have different values ​​depending on the target characteristics. The units of the parameters c to h may be consistent with the units of the target characteristics, the unit of the helium ion dose, the unit of the oxygen chemical concentration, and the unit of the carbon chemical concentration.

[0260] 34A, 34B, and 34C are graphs showing the helium ion depth dependence of the reduced vacancy concentration Nv', the reduced oxygen contribution ξ', and the reduced carbon contribution η' in the electrical target characteristics. In each graph, the helium ion dose at the depth position Z1 is He 1. D He 2. D He 3. D He 4. D He 5. D He 29 shows six examples of the vacancy concentration Nv', the reduced oxygen contribution ratio ξ', and the reduced carbon contribution ratio η' with respect to the helium ion depth, all calculated from the parameters c, d, e, f, g, and h experimentally obtained in advance. Using this graph, it can be determined whether the semiconductor device was manufactured based on the flow shown in FIG.

[0261] The implantation depth Z1 of helium ions is determined by measuring the atomic density distribution (chemical concentration distribution) of helium atoms in the semiconductor substrate 10, for example, by SIMS, and determining the depth from the implantation surface at which the peak of the concentration distribution is found. The implantation surface may be the principal surface on which the chemical concentration distribution of helium atoms slopes downward from its peak. The dose of helium ions may be determined by integrating the measured chemical concentration distribution of helium atoms in the depth direction from the implantation surface. By interpolating the calculated depth and dose of helium ions in the graphs of Figures 34A, 34B, and 34C, the reduced vacancy concentration Nv', the reduced oxygen contribution ratio ξ', and the reduced carbon contribution ratio η' can be determined. The chemical concentrations of oxygen and carbon can be determined by SIMS. Substituting these values ​​into equation (15) determines the electrical characteristic value F1.

[0262] On the other hand, the actual electrical characteristic F2 can be obtained by electrical measurement of the semiconductor device 100. As a result, if the ratio of the calculated value F1 to the measured value F2 is 0.1 or more and 10 or less, it can be said that the semiconductor device was manufactured based on the flow of Fig. 29. The first value or third value described above is an example of the calculated value F1, and the second value is an example of the measured value F2.

[0263] 35 is a diagram showing another example of a manufacturing method for semiconductor device 100. The manufacturing method of this example differs in that it includes a parameter acquisition step S3502 and a condition adjustment step S3503 instead of the concentration measurement step S1602 and the injection amount calculation step S1604 in the example described with reference to FIGS. 16 to 34C. The other steps are the same as those in the example described with reference to FIGS. 16 to 34C. Although FIG. 35 does not show oxygen introduction step S1802, the manufacturing method of this example may or may not include the oxygen introduction step S1802 described with reference to FIG. 18.

[0264] In parameter acquisition step S3502, parameters related to the semiconductor substrate 10 prepared in substrate preparation step S1600 are acquired. Concentration measurement step S1602 described with reference to FIG. 16 and other figures is an example of parameter acquisition step S3502. The parameters may include parameters such as the oxygen chemical concentration or the carbon chemical concentration described with reference to FIGS. 16 to 34C. In parameter acquisition step S3502, parameters related to the semiconductor substrate 10 may be measured, and specification values ​​or design values ​​of the semiconductor substrate 10 may be acquired. In parameter acquisition step S3502, parameters affecting the hydrogen donor concentration in the semiconductor substrate 10 or parameters affecting the breakdown voltage of the semiconductor device 100 may be acquired. In parameter acquisition step S3502, at least one of the oxygen chemical concentration, the carbon chemical concentration, the oxygen contribution ratio ξ, and the carbon contribution ratio η contained in the semiconductor substrate 10 may be acquired. These parameters may affect the hydrogen donor concentration and the breakdown voltage of the semiconductor device 100. In parameter acquisition step S3502, at least one of the thickness and bulk donor concentration of the semiconductor substrate 10 may be acquired. These parameters can affect the breakdown voltage of the semiconductor device 100.

[0265] In condition adjusting step S3503, one or more of the particle implantation conditions in particle implantation step S1608, the hydrogen implantation conditions in hydrogen implantation step S1610, and the heat treatment conditions in heat treatment step S1612 are adjusted based on at least one parameter acquired in parameter acquiring step S3502. In condition adjusting step S3503, these conditions may be adjusted so that the hydrogen donor concentration in the semiconductor substrate 10 or the breakdown voltage of the semiconductor device 100 approaches a predetermined target value. Implantation amount calculating step S1604 in FIG. 16 etc. is an example of condition adjusting step S3503. The particle implantation conditions include at least one of the dose amount and implantation depth Z1 of charged particles (see, for example, FIG. 2). The hydrogen implantation conditions include at least one of the dose amount and implantation depth Z2 of hydrogen ions (see, for example, FIG. 2). The heat treatment conditions include at least one of the heat treatment temperature and heat treatment time.

[0266] For example, if the parameters acquired in parameter acquisition step S3502 indicate a state in which hydrogen donors are unlikely to be generated in the semiconductor substrate 10, condition adjustment step S3503 adjusts the conditions of each step to conditions that promote the generation of hydrogen donors in the semiconductor substrate 10. For example, a low oxygen chemical concentration in the semiconductor substrate 10 reduces the likelihood of VOH defects being generated. On the other hand, increasing the dose of the charged particle beam in particle implantation step S1608, increasing the dose of hydrogen ions in hydrogen ion implantation step S1610, increasing the heat treatment temperature in heat treatment step S1612, and lengthening the heat treatment time in heat treatment step S1612 all promote the generation of VOH defects. Condition adjustment step S3503 may perform at least one of these processes. Similarly, a high oxygen chemical concentration in the semiconductor substrate 10 increases the likelihood of VOH defects being generated. On the other hand, reducing the dose of the charged particle beam in particle implantation step S1608, reducing the dose of hydrogen ions in hydrogen ion implantation step S1610, reducing the heat treatment temperature in heat treatment step S1612, and shortening the heat treatment time in heat treatment step S1612 all suppress the generation of VOH defects. Condition adjustment step S3503 may perform one of these processes or a combination of multiple processes. Furthermore, a high carbon chemical concentration in the semiconductor substrate 10 tends to increase the generation of VOH defects, while a low carbon chemical concentration tends to decrease the generation of VOH defects. The oxygen contribution ratio ξ and the carbon contribution ratio η are as described above. Condition adjustment step S3503 may perform a process similar to that for adjusting the oxygen chemical concentration based on these parameters.

[0267] Furthermore, if the parameters acquired in the parameter acquisition step S3502 indicate a state in which the breakdown voltage of the semiconductor device 100 is reduced, the conditions in each step are adjusted in the condition adjustment step S3503 to conditions that improve the breakdown voltage of the semiconductor device 100. For example, if the thickness of the semiconductor substrate 10 is small, the breakdown voltage of the semiconductor device 100 will be reduced. On the other hand, if the concentration of hydrogen donors generated in the semiconductor substrate 10 is reduced, for example, the doping concentration of the drift region 18 will be reduced. This improves the breakdown voltage of the semiconductor device 100. The concentration of hydrogen donors can be reduced by reducing the dose of charged particles or the dose of hydrogen ions. The concentration of hydrogen donors can also be reduced by lowering the heat treatment temperature or shortening the heat treatment time. Furthermore, if the length of the passage region 106 in the semiconductor substrate 10 in the Z-axis direction is reduced, the length of the high-concentration flat portion 150 (see FIG. 3) in the Z-axis direction is reduced. This improves the breakdown voltage of the semiconductor device 100. The length of the passage region 106 can be shortened by moving the injection position Z1 of the charged particles closer to the lower surface 23. Condition adjustment step S3503 may involve performing one of these processes or a combination of these processes.

[0268] Furthermore, the bulk donor concentration N B0 If the doping concentration of the drift region 18 is high, the breakdown voltage of the semiconductor device 100 is low. B0 The same processing as for the thickness of the semiconductor substrate 10 may be performed on this.

[0269] In the condition adjustment step S3503, the conditions for each stage may be adjusted based on the difference or ratio between the acquired parameters and a preset reference value. How much the conditions for each stage should be adjusted relative to the difference or ratio may be determined in advance through experiments, etc. In this way, by adjusting the conditions for each stage based on the acquired parameters, the characteristics of the semiconductor device 100 can be adjusted. Furthermore, the variation in the characteristics of the semiconductor device 100 can be reduced.

[0270] Figure 36 is a diagram showing another example of the manufacturing method of the semiconductor device 100. In the manufacturing method of this example, concentration measurement step S1602 is performed as parameter acquisition step S3502 in Figure 35. The other steps are the same as in the example of Figure 35. Also, in concentration measurement step S1602, the oxygen chemical concentration of the semiconductor substrate 10 is measured, similar to the example of Figure 16 etc.

[0271] In condition adjusting step S3503, at least one of the injected conditions of the charged particle beam in particle implanting step S1608, the injected conditions of hydrogen ions in hydrogen implanting step S1610, and the heat treatment conditions in heat treatment step S1612 is adjusted according to the oxygen chemical concentration. In condition adjusting step S3503, the injected conditions of the charged particle beam may be adjusted as in the example of FIG.

[0272] When adjusting the hydrogen ion implantation conditions in hydrogen implantation step S1610, the dose of hydrogen ions may be adjusted. By adjusting the dose of hydrogen ions, the concentration of hydrogen diffusing into the transit region 106 can be adjusted, thereby adjusting the concentration of hydrogen donors generated in the transit region 106. In condition adjustment step S3503, the dose of hydrogen ions may be set lower than the hydrogen reference value when the oxygen chemical concentration is higher than the oxygen reference value, and the dose of hydrogen ions may be set higher than the hydrogen reference value when the oxygen chemical concentration is lower than the oxygen reference value. This reduces the influence of variations in the oxygen chemical concentration, allowing the doping concentration of the transit region 106 to be adjusted with precision.

[0273] When adjusting the heat treatment conditions in the heat treatment step S1612, at least one of the heat treatment temperature and the heat treatment time may be adjusted. Adjusting the heat treatment temperature or the heat treatment time can adjust the hydrogen diffusion into the transit region 106 and the generation of hydrogen donors. In the condition adjustment step S3503, the heat treatment temperature may be lowered below the temperature reference value when the oxygen chemical concentration is higher than the oxygen reference value, and the heat treatment temperature may be higher than the temperature reference value when the oxygen chemical concentration is lower than the oxygen reference value. Similarly, the heat treatment time may be shorter than the time reference value when the oxygen chemical concentration is higher than the oxygen reference value, and the heat treatment time may be longer than the time reference value when the oxygen chemical concentration is lower than the oxygen reference value. This reduces the influence of variations in the oxygen chemical concentration, allowing the doping concentration of the transit region 106 to be adjusted with precision.

[0274] 29, the carbon chemical concentration of the semiconductor substrate 10 may be further measured in the concentration measurement step S1602. In the condition adjustment step S3503, the conditions of each step may be adjusted further based on the carbon chemical concentration. A higher carbon chemical concentration tends to result in a higher hydrogen donor concentration. In the condition adjustment step S3503, when the carbon chemical concentration is higher than the carbon reference value, the conditions may be adjusted to suppress the formation of hydrogen donors, and when the carbon chemical concentration is lower than the carbon reference value, the conditions may be adjusted to promote the formation of hydrogen donors.

[0275] Furthermore, in the condition adjusting step S3503, the hydrogen ion implantation conditions in the hydrogen implantation step S1610 and the heat treatment conditions in the heat treatment step S1612 may be adjusted based on the implantation depth Z1 of the charged particle beam in the particle implantation step S1608. The length of the passage region 106 changes depending on the implantation depth Z1 of the charged particle beam, and the total amount of lattice defects formed inside the semiconductor substrate 10 changes. The total amount of hydrogen donors formed depends on the total amount of lattice defects. Therefore, the total amount of hydrogen donors formed changes depending on the implantation depth Z1 of the charged particle beam. In the condition adjusting step S3503, at least one of the hydrogen ion implantation conditions and the heat treatment conditions may be adjusted so that the total amount of hydrogen donors formed approaches a predetermined reference value. In the condition adjusting step S3503, the hydrogen ion implantation conditions or the heat treatment conditions calculated according to the oxygen chemical concentration may be corrected based on the implantation depth Z1 of the charged particle beam.

[0276] Furthermore, when manufacturing a plurality of semiconductor devices 100, the adjustment of the implantation conditions in particle implantation step S1608 and the adjustment of the implantation conditions in hydrogen implantation step S1610 may be performed for each semiconductor substrate 10 (each semiconductor device 100). The adjustment of the heat treatment conditions in heat treatment step S1612 may be performed commonly for the plurality of semiconductor substrates 10. The heat treatment for the plurality of semiconductor substrates 10 may be performed in parallel by placing the plurality of semiconductor substrates 10 in a common heat treatment furnace. The implantation of charged particles or hydrogen ions into each semiconductor substrate 10 may be performed for each semiconductor substrate 10. By performing such processing, the adjustment for the plurality of semiconductor substrates 10 can be performed efficiently.

[0277] Fig. 37 is a diagram showing another example of the manufacturing method of the semiconductor device 100. In the manufacturing method of this example, concentration acquisition step S3702 is performed as parameter acquisition step S3502 in Fig. 35. The other steps are the same as those in the example of Fig. 35 or 36.

[0278] In concentration acquisition step S3702, information on the impurity concentration in a predetermined region of the semiconductor substrate 10 is acquired. In concentration acquisition step S3702, the information may be acquired by measuring the semiconductor substrate 10, and design values ​​or specification values ​​of the information on the semiconductor substrate 10 may be acquired. The predetermined region of the semiconductor substrate 10 may be, for example, a central position in the depth direction of the semiconductor substrate 10, but is not limited to this. The impurity concentration on the upper surface 21 or the lower surface 23 of the semiconductor substrate 10 may be acquired. In concentration acquisition step S3702, the impurity concentration that affects the doping concentration of the drift region 18 when the semiconductor device 100 is completed may be acquired. As an example, in concentration acquisition step S3702, the oxygen chemical concentration, the carbon chemical concentration, and the bulk donor concentration N B0 When the oxygen chemical concentration or the carbon chemical concentration is acquired, the process of the condition adjusting step S3503 may be the same as the example of FIG.

[0279] In this example, the condition adjustment step S3503 adjusts the bulk donor concentration N B0 Based on this, at least one of the conditions for implanting the charged particle beam in the particle implantation step S1608, the conditions for implanting the hydrogen ions in the hydrogen implantation step S1610, and the conditions for heat treatment in the heat treatment step S1612 is adjusted.

[0280] The final doping concentration of the drift region 18 upon completion of the fabrication of the semiconductor device 100 is the bulk donor concentration N B0 and depends on the hydrogen donor concentration. Therefore, the bulk donor concentration N B0 In the condition adjustment step S3503, the bulk donor concentration N B0 The conditions of each step are adjusted so as to offset the deviation from the predetermined bulk reference value. That is, in the condition adjustment step S3503, the bulk donor concentration N B0 If N is smaller than the bulk reference value, adjust the conditions at each stage to increase the amount of hydrogen donor produced, and increase the bulk donor concentration N. B0If is greater than the bulk reference value, the conditions for each stage are adjusted to reduce the amount of hydrogen donor generated. The method for adjusting the amount of hydrogen donor generated in each stage is the same as in the examples of Figures 35 and 36. This reduces the variation in the final doping concentration.

[0281] In condition adjustment step S3503, each condition may be adjusted so that the integral value of the doping concentration in drift region 18 approaches a predetermined reference value. As an example, condition adjustment step S3503 adjusts the injection depth of the charged particle beam in particle injection step S1608 based on the acquired impurity concentration. By adjusting the injection depth, the length of passage region 106 can be adjusted, and the integral value of the doping concentration in drift region 18 can be adjusted.

[0282] Furthermore, in condition adjusting step S3503, the conditions of each step may be adjusted based on at least one of the oxygen contribution rate ξ and the carbon contribution rate η, thereby enabling the amount of hydrogen donors formed to be adjusted with even greater precision.

[0283] 38 is a diagram showing the relationship between the bulk donor concentration and the implantation depth Z1 of the charged particles. In this example, the bulk donor concentration acquired in the concentration acquisition step S3702 is calculated as N B0 , bulk reference value N Br , N B0 and N Br The ratio of N to N is γ. B0 =γ N Br In addition, the injection depth of the charged particles before the condition adjustment is Z1 r , the injection depth of the charged particles after the condition adjustment is Z1, Z1 and Z1 r The ratio of Z1 to Z1 is ε. In other words, Z1 = ε Z1 r The implantation depth Z indicates the distance from the lower surface 23 of the semiconductor substrate 10 to the implantation position.

[0284] As shown in Figure 38, the condition adjustment step S3503 adjusts the implantation depth Z1 of the charged particles so that the larger γ is, the smaller ε is. The larger γ is, the smaller the bulk donor concentration N B0becomes larger. As a result, the doping concentration in the drift region 18 becomes higher, which may reduce the breakdown voltage of the semiconductor substrate 10. In response to this, by reducing ε and bringing the implantation depth Z1 closer to the lower surface 23, the length over which the high-concentration flat portion 150 is formed can be shortened, and the integral value of the doping concentration in the drift region 18 can be reduced. This makes it possible to suppress a reduction in the breakdown voltage of the semiconductor substrate 10.

[0285] 39 is a diagram showing another example of a manufacturing method for semiconductor device 100. In this manufacturing method, substrate thickness measurement step S3902 is performed as parameter acquisition step S3502 in FIG. 35. Also, a grinding step S3901 is provided before substrate thickness measurement step S3902, in which the semiconductor substrate 10 is ground to adjust its thickness. The other steps are the same as those in the example of FIG. 35, FIG. 36, or FIG. 37.

[0286] In the grinding step S3901, the thickness of the semiconductor substrate 10 may be adjusted depending on the breakdown voltage that the semiconductor device 100 should have. The grinding step S3901 may be performed before the particle implantation step S1608 or before the hydrogen implantation step S1610. In the grinding step S3901, the lower surface 23 of the semiconductor substrate 10 may be polished by CMP or the like.

[0287] In the substrate thickness measurement step S3902, the thickness of a predetermined region of the semiconductor substrate 10 is measured. In the substrate thickness measurement step S3902, an average value of thicknesses measured at multiple locations may be used. In the substrate thickness measurement step S3902, the thickness may be measured in the active portion 160 or in the edge termination structure portion 90.

[0288] In the condition adjustment step S3503, based on the measured thickness of the semiconductor substrate 10, at least one of the conditions for implanting the charged particle beam in the particle implantation step S1608, the conditions for implanting the hydrogen ions in the hydrogen implantation step S1610, and the conditions for heat treatment in the heat treatment step S1612 is adjusted.

[0289] Variations in the thickness of the semiconductor substrate 10 may result in variations in the breakdown voltage of the semiconductor device 100. In condition adjustment step S3503, the conditions for each step are adjusted to offset the deviation of the thickness of the semiconductor substrate 10 from a predetermined thickness reference value. That is, in condition adjustment step S3503, if the thickness of the semiconductor substrate 10 is smaller than the thickness reference value, the conditions for each step are adjusted to increase the breakdown voltage, and if the thickness of the semiconductor substrate 10 is larger than the thickness reference value, the conditions for each step are adjusted to decrease the breakdown voltage. The breakdown voltage of the semiconductor device 100 can be increased by reducing the integral value of the doping concentration in the drift region 18, and can be decreased by increasing the integral value. The integral value of the doping concentration can be adjusted by the amount of hydrogen donors formed in the drift region 18. As described above, the amount of hydrogen donors formed can be adjusted by the conditions for each step.

[0290] In this example, the thickness of semiconductor substrate 10 in edge termination structure 90 may be measured and the implantation conditions for edge termination structure 90 may be adjusted. The implantation conditions for charged particles and hydrogen ions may be different between active section 160 and edge termination structure 90. This allows for accurate control of the doping concentration and breakdown voltage in edge termination structure 90.

[0291] FIG. 40 is a diagram showing an example of equipotential surface 308 in edge termination structure 90. Edge termination structure 90 has the same structure as the example in FIG. 14. A region with a higher concentration than the bulk donor concentration is formed on lower surface 23 side of second peak 141. Therefore, the curvature of equipotential surface 308 changes near second peak 141. As a result, equipotential surface 308 expands toward the periphery of semiconductor device 100 near upper surface 21 of semiconductor substrate 10. Therefore, the extent to which equipotential surface 308 expands toward the periphery of semiconductor device 100 depends on distance Zb between upper surface 21 of semiconductor substrate 10 and second peak 141.

[0292] Condition adjusting step S3503 may adjust the injection depth Z1 of the charged particles into the edge termination structure 90 based on the thickness of the semiconductor substrate 10 in the edge termination structure 90. This allows for accurate control of the distance Zb. This prevents the depletion layer in the edge termination structure 90 from spreading too far laterally. This allows for a shorter circumferential length of the edge termination structure 90, and a smaller area of ​​the top surface 21 of the semiconductor device 100.

[0293] Furthermore, condition adjusting step S3503 may adjust each implantation condition for edge termination structure 90. This allows the doping concentration below second peak 141 to be adjusted with precision, thereby further controlling the extent of equipotential surface 308.

[0294] 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.

[0295] 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]

[0296] 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 peak, 26 peak, 29 straight portion, 30 dummy trench portion, 31 tip portion, 32 dummy insulating film, 34 dummy conductive portion, 38 layer Interlayer insulating film, 39... linear 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, 92... guard ring, 94... field plate, 100... semiconductor device, 106... passing region, 11 1...second donor peak, 121...first donor peak, 130...periphery gate wiring, 131...active side gate wiring, 133...first peak, 141...second peak, 142...lower side skirt, 143...upper side skirt, 150...flat portion, 151...second contributing concentration peak, 160...active portion, 161...first contributing concentration peak, 162...edge, 164...gate pad, 171...vacancy peak, 174...channel stopper, 180... Area, 181 Second VOH peak, 191 First VOH peak, 194 Hydrogen concentration peak, 214 Linear approximation distribution, 216 Strip, 308 Equipotential surface, 601, 602, 603, 611, 612, 613, 631, 632, 633, 641, 642, 643 Line, 621, 622, 623 Plot, 801, 802, 811, 812, 813, 821, 822, 823, 831, 832, 833, 901, 902 Curve

Claims

1. a first peak located on an upper surface side of the center of the semiconductor substrate in a donor concentration distribution in a depth direction of the semiconductor substrate; a second peak located on a lower surface side of the center of the semiconductor substrate in the donor concentration distribution; a flat portion that is provided in a predetermined region including a central depth position of the semiconductor substrate between the first peak and the second peak, the flat portion having a donor concentration higher than a bulk donor concentration of the semiconductor substrate and a flat donor concentration distribution; Equipped with The total oxygen chemical concentration between the first peak and the second peak is 3×10 １５ atoms / cm ３ That's it, 2 x 10 １８ atoms / cm ３ is Semiconductor device.

2. a first peak located on an upper surface side of the semiconductor substrate in a donor concentration distribution in a depth direction of the semiconductor substrate; a second peak located on the lower surface side of the semiconductor substrate in the donor concentration distribution; a flat portion that is provided in a predetermined region including a central depth position of the semiconductor substrate between the first peak and the second peak, the flat portion having a donor concentration higher than a bulk donor concentration of the semiconductor substrate and a flat donor concentration distribution; Equipped with The total oxygen chemical concentration between the first peak and the second peak is 3×10 １５ atoms / cm ３ That's it, 2 x 10 １８ atoms / cm ３ is as follows: The second peak is located in a range of ¼ or less of the thickness of the semiconductor substrate with the lower surface as a reference. Semiconductor device.

3. a first peak located on an upper surface side of the semiconductor substrate in a donor concentration distribution in a depth direction of the semiconductor substrate; a second peak located on the lower surface side of the semiconductor substrate in the donor concentration distribution; a flat portion that is provided in a predetermined region including a central depth position of the semiconductor substrate between the first peak and the second peak, the flat portion having a donor concentration higher than a bulk donor concentration of the semiconductor substrate and a flat donor concentration distribution; Equipped with The total oxygen chemical concentration between the first peak and the second peak is 3×10 １５ atoms / cm ３ That's it, 2 x 10 １８ atoms / cm ３ is as follows: The first peak is located in a range of ¼ or less of the thickness of the semiconductor substrate with the top surface as a reference. Semiconductor device.

4. The carbon chemical concentration of the flat portion is 1×10 １３ atoms / cm ３ That's it, 1 x 10 １６ atoms / cm ３ is The semiconductor device according to claim 1 .

5. The carbon chemical concentration of the flat portion is 1×10 １４ atoms / cm ３ That's it, 2 x 10 １５ atoms / cm ３ is The semiconductor device according to claim 1 .

6. a first peak located on an upper surface side of the center of the semiconductor substrate in a donor concentration distribution in a depth direction of the semiconductor substrate; a second peak located on a lower surface side of the center of the semiconductor substrate in the donor concentration distribution; a flat portion provided in a predetermined region between the first peak and the second peak, the flat portion having a donor concentration higher than a bulk donor concentration of the semiconductor substrate, and the donor concentration distribution being flat; The total oxygen chemical concentration between the first peak and the second peak is 3×10 １５ atoms / cm ３ That's it, 2 x 10 １８ atoms / cm ３ is as follows: The carbon chemical concentration of the flat portion is 1×10 １３ atoms / cm ３ That's it, 1 x 10 １６ atoms / cm ３ is Semiconductor device.

7. a first peak located on an upper surface side of the semiconductor substrate in a donor concentration distribution in a depth direction of the semiconductor substrate; a second peak located on the lower surface side of the semiconductor substrate in the donor concentration distribution; a flat portion provided in a predetermined region between the first peak and the second peak, the flat portion having a donor concentration higher than a bulk donor concentration of the semiconductor substrate, and the donor concentration distribution being flat; The total oxygen chemical concentration between the first peak and the second peak is 3×10 １５ atoms / cm ３ That's it, 2 x 10 １８ atoms / cm ３ is as follows: The carbon chemical concentration of the flat portion is 1×10 １３ atoms / cm ３ That's it, 1 x 10 １６ atoms / cm ３ is as follows: The second peak is located in a range of ¼ or less of the thickness of the semiconductor substrate with the lower surface as a reference. Semiconductor device.

8. a first peak located on an upper surface side of the semiconductor substrate in a donor concentration distribution in a depth direction of the semiconductor substrate; a second peak located on the lower surface side of the semiconductor substrate in the donor concentration distribution; a flat portion provided in a predetermined region between the first peak and the second peak, the flat portion having a donor concentration higher than a bulk donor concentration of the semiconductor substrate, and the donor concentration distribution being flat; The total oxygen chemical concentration between the first peak and the second peak is 3×10 １５ atoms / cm ３ That's it, 2 x 10 １８ atoms / cm ３ is as follows: The carbon chemical concentration of the flat portion is 1×10 １３ atoms / cm ３ That's it, 1 x 10 １６ atoms / cm ３ is as follows: The first peak is located in a range of ¼ or less of the thickness of the semiconductor substrate with the top surface as a reference. Semiconductor device.

9. The total oxygen chemical concentration between the first peak and the second peak is 1×10 １７ atoms / cm ３ That's it, 1 x 10 １８ atoms / cm ３ is The semiconductor device according to claim 1 .

10. The first peak and the second peak are located between a lower end of a trench portion provided on the upper surface side of the semiconductor substrate and a cathode region of a first conductivity type or a collector region of a second conductivity type that is in contact with the lower surface of the semiconductor substrate. The semiconductor device according to claim 1 .

11. The flat portion is provided over 75% or more of the length between the first peak and the second peak. The semiconductor device according to claim 1 .

12. The flat portion is provided in a range of 20% to 80% of the thickness of the semiconductor substrate. The semiconductor device according to claim 1 .

13. The flat portion has a donor concentration within a range of ±50% of the average concentration in the donor concentration distribution in the depth direction of the flat portion. The semiconductor device according to claim 1 .

14. The flat portion has a donor concentration within a range of ±30% of the average concentration in the donor concentration distribution in the depth direction of the flat portion. The semiconductor device according to claim 1 .

15. The flat portion has a donor concentration within a range of ±10% of the average concentration in the donor concentration distribution in the depth direction of the flat portion. The semiconductor device according to claim 1 .

16. In the donor concentration distribution, a linear approximation distribution obtained by connecting both ends of the predetermined region with a straight line indicates that the concentration increases as the distance from the lower surface increases. The semiconductor device according to claim 1 .

17. The predetermined region is a region penetrated by hydrogen ions. The semiconductor device according to claim 1 .

18. the predetermined region is a hydrogen donor flat region; A helium chemical concentration peak is provided between the bottom of the trench portion and the cathode region or the collector region. The semiconductor device according to claim 10.

19. The donor concentration in the flat portion is 2×10 １２ / cm ３ That's it, 5 x 10 １４ / cm ３ is The semiconductor device according to claim 1 .

20. The hydrogen chemical concentration in the flat portion is greater than a contributing oxygen concentration obtained by multiplying the oxygen chemical concentration in the flat portion by an oxygen contribution ratio indicating the proportion of the oxygen chemical concentration that contributes to the generation of hydrogen donors in the oxygen chemical concentration.

8. The semiconductor device according to claim 1, 2, 6, or 7.

21. The oxygen contribution rate is 1×10 −5 or more and 7×10 −4 or less. The semiconductor device according to claim 20.

22. In the flat portion, a carbon contribution ratio indicating a ratio of the carbon chemical concentration that contributes to hydrogen donor formation to the carbon chemical concentration is 0.0001 or more and 0.1 or less. The semiconductor device according to claim 6.

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