Semiconductor device and method for manufacturing a semiconductor device

Abstract

To accurately adjust the donor concentration of the semiconductor substrate, a semiconductor device is provided that includes a semiconductor substrate having an upper and lower surface and containing oxygen. [Solution] The semiconductor device 100 has an upper surface 21 and a lower surface 23, and comprises a semiconductor substrate 10 containing oxygen, a first peak 133 of hydrogen chemical concentration located on the lower side of the semiconductor substrate, and a flat portion located on the upper side of the semiconductor substrate from the first peak, containing hydrogen donors, and having a substantially (almost) flat donor concentration distribution in the depth direction of the semiconductor substrate, wherein the oxygen contribution rate, which indicates the proportion of the oxygen chemical concentration of oxygen that contributes to generating hydrogen donors, is 1 × 10⁻¹⁶ -5 The above 7 x 10 -4 The following conditions apply: In the flat portion, the oxygen concentration contributing to the generation of hydrogen donors is lower than the hydrogen chemical concentration, and the hydrogen donor concentration in the flat portion is 2 × 10 12 / cm 3 The above 5 x 10 14 / cm 3 The following applies:

Description

[Technical Field]

[0001] The present invention relates to semiconductor devices and methods for manufacturing them. [Background technology]

[0002] Conventionally, a technique is known for adjusting the substrate resistance by forming a donor by injecting hydrogen into a predetermined depth in a semiconductor substrate and allowing it to diffuse (for example, Patent Document 1). Patent Document 1: Problem to be solved in the specification of U.S. Patent Application Publication No. 2018 / 0019306

[0003] The donor concentration of the semiconductor substrate is preferably precisely controlled. (General Disclosure)

[0004] To solve the above problems, a first embodiment of the present invention provides a semiconductor device comprising a semiconductor substrate having an upper surface and a lower surface and 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 beyond the first peak, containing hydrogen donors, and having a substantially (almost) flat donor concentration distribution in the depth direction of the semiconductor substrate. The oxygen contribution rate, which indicates the proportion of the oxygen chemical concentration of oxygen that contributes to generating hydrogen donors, is 1 × 10⁻⁶. -5 The above 7 x 10 -4 The following may apply: In the flat region, the oxygen concentration contributing to hydrogen donor generation may be lower than the hydrogen chemical concentration. The hydrogen donor concentration in the flat region is 1 × 10⁻⁶ 12 / cm 3 The above 5 x 10 14 / cm 3 The following is acceptable:

[0005] The oxygen contribution rate is 5 × 10 -4 The following is acceptable:

[0006] The oxygen contribution rate is 1 × 10⁻⁶ -4 That's all.

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

[0008] The semiconductor device may include a second peak of the chemical concentration of hydrogen or helium disposed on the upper surface side of the semiconductor substrate. The flat portion may be disposed on the lower surface side of the semiconductor substrate than the second peak. The hydrogen contribution rate indicating the ratio of the hydrogen chemical concentration contributing to the generation of hydrogen donors among the hydrogen chemical concentrations may be 0.001 or more and 0.3 or less. The vacancy concentration of the flat portion is 1×10 11 / cm 3 or more and 1×10 14 / cm 3 or less.

[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 in the flat portion may be 1×10 17 atoms / cm 3 or more.

[0011] The carbon chemical concentration in the flat portion may be 1×10 13 atoms / cm 3 or more and 1×10 16 atoms / cm 3 or less.

[0012] The sum of the value obtained by multiplying the oxygen contribution rate by the oxygen chemical concentration in the flat portion and the vacancy concentration of the flat portion may be used as the first value of the hydrogen donor concentration. The difference obtained by subtracting the bulk donor concentration from the donor concentration in the flat portion may be used as the second value of the hydrogen donor concentration. The ratio of the first 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.

[0013] [[ID=A second embodiment of the present invention provides a semiconductor device comprising a semiconductor substrate having an upper and lower surface and 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 beyond the first peak, containing hydrogen donors, and having a substantially (almost) flat donor concentration distribution in the depth direction of the semiconductor substrate. The semiconductor substrate may contain bulk donors. The donor concentration in the flat portion may be higher than the bulk donor concentration. The first value of the hydrogen donor concentration may be the sum of the value obtained by multiplying the oxygen chemical concentration in the flat portion by the oxygen chemical concentration in the flat portion, which represents the proportion of the oxygen chemical concentration of oxygen that contributes to the generation of hydrogen donors, and the vacancy concentration in the flat portion. The 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 first 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.

[0014] A third embodiment of the present invention provides a semiconductor device comprising a semiconductor substrate having an upper and lower surface and containing oxygen and carbon. 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 region located on the upper surface side of the semiconductor substrate beyond the first peak, containing hydrogen donors, and having a substantially (almost) flat donor concentration distribution in the depth direction of the semiconductor substrate. The semiconductor substrate may contain bulk donors. The donor concentration in the flat region may be higher than the bulk donor concentration. A third value of hydrogen donor concentration may be the sum of the value obtained by multiplying the oxygen chemical concentration in the flat region by the oxygen chemical concentration, which represents the proportion of the oxygen chemical concentration of oxygen that contributes to the generation of hydrogen donors, multiplying the carbon chemical concentration in the flat region by the carbon chemical concentration, which represents the proportion of the carbon chemical concentration of carbon that contributes to the generation of hydrogen donors, and the vacancy concentration in the flat region. A second value of hydrogen donor concentration may be the difference obtained by subtracting the bulk donor concentration from the donor concentration in the flat region. The ratio of the third hydrogen donor concentration to the second hydrogen donor concentration may be between 0.1 and 10.

[0015] A fourth embodiment of the present invention provides a method for manufacturing a semiconductor device. The manufacturing method may include a concentration measurement step for measuring the oxygen chemical concentration of a semiconductor substrate having an upper surface and a lower surface. The manufacturing method may include a particle implantation step for implanting a charged particle beam from the lower surface of the semiconductor substrate so as to pass through more than half of the thickness of the semiconductor substrate in the depth direction. The manufacturing method may include a heat treatment step for heat treating the semiconductor substrate after implanting the charged particle beam. At least one of the implantation conditions for 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] During the concentration measurement stage, the carbon chemical concentration of the semiconductor substrate may be further measured. During the particle implantation stage, 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 in the semiconductor substrate, the concentration of hydrogen donors to be generated by the manufacturing method is set to N VOH1 The concentration of hydrogen donor actually generated is N VOH2 The vacancy concentration formed by the particle injection step is N V , the oxygen chemical concentration is C OX , carbon chemical concentration C C Let ξ be the oxygen contribution rate, which represents the proportion of the oxygen chemical concentration that contributes to the generation of hydrogen donors, and let η be the carbon contribution rate, which represents the proportion of the carbon chemical concentration that contributes to the generation of hydrogen donors. N VOH1 =N V +ξC OX +ηC C And, 0.1≦N VOH1 / N VOH2 It is acceptable for the value to be ≤10.

[0018] During the injection phase, hydrogen ions may be injected as charged particle beams.

[0019] The manufacturing method may include a hydrogen implantation step in which hydrogen ions are implanted into the underside of the semiconductor substrate prior to the heat treatment step.

[0020] The manufacturing method may include an oxygen introduction step in which oxygen is introduced into the semiconductor substrate.

[0021] The hydrogen ion implantation conditions during the hydrogen implantation stage may be adjusted based on the oxygen chemical concentration of the semiconductor substrate.

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

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

[0024] Based on the bulk donor concentration of the semiconductor substrate, at least one of the charged particle beam injection conditions in the particle injection stage and the heat treatment conditions in the heat treatment stage may be adjusted.

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

[0026] In the particle implantation stage, the implantation conditions may be adjusted for each individual semiconductor substrate. In the heat treatment stage, the heat treatment conditions may be adjusted for all semiconductor substrates in common.

[0027] The hydrogen ion implantation conditions during the hydrogen implantation stage may be adjusted based on the thickness of the semiconductor substrate.

[0028] During the substrate thickness measurement stage, the thickness of the semiconductor substrate at the edge termination structure of the semiconductor substrate may be measured.

[0029] A fifth embodiment of the present invention provides a method for manufacturing a semiconductor device. The manufacturing method may include a concentration acquisition step for acquiring the impurity concentration of a semiconductor substrate having an upper surface and a lower surface. The manufacturing method may include a particle implantation step for implanting a charged particle beam from the lower surface of the semiconductor substrate so as to pass through more than half of the thickness of the semiconductor substrate in the depth direction. The manufacturing method may include a heat treatment step for 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] During the concentration acquisition stage, at least one of the bulk donor concentration, oxygen chemical concentration, and carbon chemical concentration of the semiconductor substrate may be acquired.

[0031] During the particle injection stage, the injection depth of the charged particle beam may be adjusted based on at least one of the following: an oxygen contribution rate ξ, which represents the proportion of the oxygen chemical concentration that contributes to the generation of hydrogen donors from the total oxygen chemical concentration, and a carbon contribution rate η, which represents the proportion of the carbon chemical concentration that contributes to the generation of hydrogen donors from the total carbon chemical concentration.

[0032] It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. Furthermore, subcombinations of these features may also constitute an invention. [Brief explanation of the drawing]

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

[0034] The present invention will be described below through embodiments, but these embodiments are not intended to limit the scope of the claims. Furthermore, not all combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0035] In this specification, one side of a semiconductor substrate parallel to its depth direction is referred to as "top," and the other side as "bottom." Of the two main surfaces of a substrate, layer, or other component, one surface is referred to as the top surface, and the other surface as the bottom surface. The directions of "top" and "bottom" are not limited to the direction of gravity or the direction in which the semiconductor device is mounted.

[0036] In this specification, technical matters may be described using the Cartesian coordinate axes, the X, Y, and Z axes. The Cartesian coordinate axes merely specify the relative positions of components and do not limit any particular direction. For example, the Z axis does not limit the direction to height relative to the ground. Note that the +Z axis direction and the -Z axis direction are opposite directions. When the sign is not specified and only the Z axis direction is written, it means the direction parallel to the +Z and -Z axes.

[0037] In this specification, the orthogonal axes parallel to the top and bottom surfaces of the semiconductor substrate are defined as the X and Y axes. The axis perpendicular to the top and bottom surfaces of the semiconductor substrate is defined as the Z axis. In this specification, the direction of the Z axis may be referred to as the depth direction. In this specification, the direction parallel to the top and bottom surfaces of the semiconductor substrate, including the X and Y axes, may be referred to as the horizontal direction.

[0038] Furthermore, the region from the center of the semiconductor substrate in the depth direction to the top surface of the semiconductor substrate is sometimes referred to as the top surface. Similarly, the region from the center of the semiconductor substrate in the depth direction to the bottom surface of the semiconductor substrate is sometimes referred to as the bottom surface.

[0039] In this specification, when we refer to items as "identical" or "equal," we may include items that have errors due to manufacturing variations, etc. Such errors are, for example, within 10%.

[0040] In this specification, the conductivity type of a doped region containing impurities is described as either P-type or N-type. In this specification, impurities may specifically refer to either N-type donors or P-type acceptors, and may be referred to as dopants. In this specification, doping means introducing donors or acceptors into a semiconductor substrate to make it a semiconductor exhibiting either an N-type conductivity or a P-type conductivity.

[0041] In this specification, doping concentration means the concentration of the donor or acceptor at thermal equilibrium. In this specification, net doping concentration means the net concentration obtained by adding up the charge polarity, with the donor concentration being the concentration of positive ions and the acceptor concentration being the concentration of negative ions. As an example, the donor concentration is N D , the acceptor concentration is N A Therefore, the net doping concentration at any given position is N D -N A In this specification, net doping concentration may be simply referred to as doping concentration.

[0042] Donors have the function of supplying electrons to a semiconductor. Acceptors have the function of receiving electrons from a semiconductor. Donors and acceptors are not limited to impurities themselves. For example, VOH defects, which are formed by the bonding of vacancies (V), oxygen (O), and hydrogen (H) in a semiconductor, function as electron donors. In this specification, VOH defects may be referred to as hydrogen donors.

[0043] In this specification, when P+ type or N+ type is mentioned, it means a higher doping concentration than P type or N type, and when P- type or N- type is mentioned, it means a lower doping concentration than P type or N type. Furthermore, when P++ type or N++ type is mentioned in this specification, it means a higher doping concentration than P+ type or N+ type. Unless otherwise specified, the units used in this specification are SI units. Although units of length may be expressed in cm, calculations may be performed after converting to meters (m).

[0044] In this specification, chemical concentration refers to the atomic density of impurities measured independently of the electrical activation state. Chemical concentration can be measured, for example, by secondary ion mass spectrometry (SIMS). The net doping concentration described above can be measured by voltage-capacitance (CV) spectroscopy. Alternatively, the carrier concentration measured by broadened resistance (SR) spectroscopy may be used as the net doping concentration. The carrier concentration measured by CV or SR spectroscopy may be the value at thermal equilibrium. Furthermore, in the N-type region, since the donor concentration is sufficiently larger than the acceptor concentration, the carrier concentration in that region may be used as the donor concentration. Similarly, in the P-type region, the carrier concentration in that region may be used as the acceptor concentration. In this specification, the doping concentration in the N-type region may be referred to as the donor concentration, and the doping concentration in the P-type region may be referred to as the acceptor concentration.

[0045] Furthermore, if the concentration distribution of the donor, acceptor, or net doping has a peak, the peak value may be used as the concentration of the donor, acceptor, or net doping in that region. In cases where the concentrations of the donor, acceptor, or net doping are substantially (almost) uniform, the average value of the concentrations of the donor, acceptor, or net doping in that region may be used as the concentration of the donor, acceptor, or net doping. In this specification, concentrations per unit volume are expressed as atoms / cm³. 3 , or / cm 3 The unit used is the donor or acceptor concentration in a semiconductor substrate, or the chemical concentration. The notation "atoms" may be omitted. In addition, each concentration in this invention may be a value at room temperature. As an example, the value at room temperature may be the value at 300 K (Kelvin) (approximately 26.9°C).

[0046] The carrier concentration measured by the SR method may be lower than the donor or acceptor concentration. When measuring spreading resistance, the carrier mobility of the semiconductor substrate may be lower than the value for the crystalline state in the range where current flows. The decrease in carrier mobility occurs because carriers are scattered due to disorder in the crystal structure caused by lattice defects, etc.

[0047] The donor or acceptor concentrations calculated from carrier concentrations measured by the CV method or SR method may be lower than the chemical concentrations of the elements that act as donors or acceptors. For example, in silicon semiconductors, the donor concentrations of phosphorus or arsenic, or the acceptor concentration of boron, are approximately 99% of their respective chemical concentrations. On the other hand, the donor concentration of hydrogen, which also acts as a donor in silicon semiconductors, is approximately 0.1% to 10% of the hydrogen chemical concentration.

[0048] Figure 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] The semiconductor substrate 10 has at least one of the following elements formed on it: a transistor element such as an insulated gate bipolar transistor (IGBT) and a diode element such as a freewheeling diode (FWD). In Figure 1, the electrodes of the transistor element and the diode element, as well as the regions located inside the semiconductor substrate 10, are omitted.

[0050] In this example, the semiconductor substrate 10 has N-type bulk donors distributed throughout. Bulk donors are donors from dopants that were substantially uniformly contained within the ingot during the manufacturing of the ingot that forms the basis of the semiconductor substrate 10. In this example, the bulk donors are elements other than hydrogen. The bulk donor dopants are, for example, group V and group VI elements, such as phosphorus, antimony, arsenic, selenium, or sulfur, but are not limited to these. In this example, the bulk donor is phosphorus. Bulk donors are also contained in the P-type region. The semiconductor substrate 10 may be a wafer cut from a semiconductor ingot, or it may be a chip made by cutting a wafer into individual pieces. The semiconductor ingot may be manufactured by one of the following methods: the Czochralski method (CZ method), the magnetic field applied Czochralski method (MCZ method), or the float zone method (FZ method). In this example, the ingot is manufactured by the MCZ method.

[0051] The oxygen chemical concentration in substrates manufactured by the MCZ method is, for example, 1 × 10⁻⁶. 17 ~7×10 17 atoms / cm 3 For example, the oxygen chemical concentration in a substrate manufactured by the FZ method is 1 × 10⁻⁶. 15 ~5×10 16 atoms / cm 3 The bulk donor concentration may be the chemical concentration of the bulk donor distributed throughout the semiconductor substrate 10, and may be a value between 90% and 100% of that chemical concentration. In a semiconductor substrate doped with group V and group VI dopants such as phosphorus, the bulk donor concentration is 1 × 10⁻⁶. 11 / cm 3 The above is 3 x 10 13 / cm 3 The following may apply: The bulk donor concentration of the semiconductor substrate doped with group V and group VI dopants is preferably 1 × 10⁻⁶. 12 / cm 3 The above is 1 x 10 13 / cm 3 The following applies. Furthermore, the semiconductor substrate 10 may be a non-doped substrate that does not contain dopants such as phosphorus. In that case, the bulk donor concentration (N) of the non-doped substrate should be... B0 ) is for example 1 × 1010 / cm 3 The above 5 x 10 12 / cm 3 The following applies: Bulk donor concentration (N) of non-doped substrates. B0 ) preferably 1 × 10 11 / cm 3 That concludes the explanation. Bulk donor concentration (N) of non-doped substrates. B0 ) preferably 5 × 10 12 / cm 3 The following applies:

[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, the orthogonal axes on the planes parallel to the upper surface 21 and the lower surface 23 are defined as the X and Y axes, and the axis perpendicular to the upper surface 21 and the lower surface 23 is defined as the Z axis.

[0053] A charged particle beam is injected into the semiconductor substrate 10 from the bottom surface 23 at a predetermined depth 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 the position where the distance in the Z-axis direction from the bottom surface 23 is Z1. 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 through the interior of the semiconductor substrate 10 is Z1. The charged particles are accelerated with acceleration energy corresponding to the predetermined depth position Z1 and introduced into the interior of the semiconductor substrate 10.

[0054] The region through which the charged particles pass through the semiconductor substrate 10 is defined as the passing region 106. In the example shown in Figure 1, the passing region 106 extends from the bottom surface 23 of the semiconductor substrate 10 to a depth position Z1. The charged particles are particles capable of forming lattice defects in the passing region 106. The charged particles are, for example, hydrogen ions, helium ions, or electrons. The charged particles may be injected across the entire surface of the semiconductor substrate 10 in the XY plane, or they may be injected only in a portion of the surface.

[0055] The semiconductor substrate 10 has a second peak 141 of charged particle concentration at depth Z1. In this example, the charged particle is hydrogen. That is, the semiconductor substrate 10 in this example has a second peak 141 of hydrogen chemical concentration at depth 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 lattice defects mainly consisting of vacancies, such as single-atom vacancies (V) and double-atom vacancies (VV), as a result of the passage of the charged particles. Atoms adjacent to vacancies have dangling bonds. Lattice defects also include interstitial atoms and dislocations, and in a broad sense, may also include donors and acceptors, but in this specification, lattice defects mainly consisting of vacancies may be referred to as vacancy-type lattice defects, vacancy-type defects, or simply lattice defects. Furthermore, the formation of many lattice defects by the implantation of charged particles into the semiconductor substrate 10 may cause a strong disorder in the crystallinity of the semiconductor substrate 10. In this specification, this disorder in crystallinity may be referred to as disorder.

[0057] Furthermore, the entire semiconductor substrate 10 contains oxygen. This oxygen is introduced intentionally or unintentionally during the manufacturing of the semiconductor ingot. In addition, at least a portion of the passing region 106 contains hydrogen. This hydrogen may be intentionally injected into the interior of the semiconductor substrate 10.

[0058] In this example, hydrogen ions are implanted at depth Z2 from the bottom surface 23. 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 Z2. In Figure 1, the second peak 141 and the first peak 133 are schematically shown by dashed lines. Depth Z2 may be included in the pass-through region 106. In this example, depth Z2 is located on the bottom surface 23 side of the semiconductor substrate 10. Note that hydrogen implanted at depth Z1 may diffuse into the pass-through region 106, or hydrogen may be introduced into the pass-through region 106 by other means. In these cases, hydrogen ions do not need to be implanted at depth Z2.

[0059] After a through 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 inside the semiconductor substrate 10 to form VOH defects. Furthermore, heat treatment of the semiconductor substrate 10 causes hydrogen to diffuse, promoting the formation of VOH defects. In addition, by heat treatment after the formation of the through region 106, hydrogen can combine with vacancies, thus suppressing the release of hydrogen to the outside of the semiconductor substrate 10.

[0060] VOH defects function as electron donors. In this specification, VOH defects may sometimes be simply referred to as hydrogen donors. In the semiconductor substrate 10 of this example, hydrogen donors are formed in the through region 106. The doping concentration of hydrogen donors at each location is lower than the chemical concentration of hydrogen at each location. The hydrogen contribution rate is defined as the ratio of the chemical concentration of hydrogen that contributes to the doping concentration of hydrogen donors (VOH defects) to the chemical concentration of hydrogen. The hydrogen contribution rate can be considered as the ratio of the concentration of hydrogen atoms constituting the VOH defect to the total concentration of hydrogen atoms in a given region (e.g., at a depth from the bottom or top surface). The hydrogen contribution rate 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 rate is 1% to 5%. Unless otherwise specified, in this specification, VOH defects having a distribution similar to the chemical concentration distribution of hydrogen, and VOH defects having a distribution similar to the vacancy defect distribution in the through region 106, are both referred to as hydrogen donors or hydrogen as donors.

[0061] By forming hydrogen donors in the pass-through region 106 of the semiconductor substrate 10, the donor concentration in the pass-through region 106 can be made higher than the bulk donor concentration. Normally, a semiconductor substrate 10 with a predetermined bulk donor concentration must be prepared to correspond to the characteristics of the element to be formed on the semiconductor substrate 10, particularly the rated voltage or withstand voltage. In contrast, according to the semiconductor device 100 shown in Figure 1, the donor concentration of the semiconductor substrate 10 can be adjusted by controlling the dose amount 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 characteristics of the element. Although the variation in bulk donor concentration during the manufacturing of the semiconductor substrate 10 is relatively large, the dose amount of charged particles can be controlled with relatively high precision. Therefore, the concentration of lattice defects caused by the injection of charged particles can also be controlled with high precision, and the donor concentration in the pass-through region can be controlled with high precision.

[0062] The depth position Z1 may be located within a range of half the thickness of the semiconductor substrate 10, or within a range of one-quarter the thickness of the semiconductor substrate 10, with respect to the top surface 21. The depth position Z2 may be located within a range of half the thickness of the semiconductor substrate 10, or within a range of one-quarter the thickness of the semiconductor substrate 10, with respect to the bottom surface 23. However, the 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 This shows the distribution in the depth direction. Figure 2 shows the distribution immediately after implanting charged particles and hydrogen ions. In other words, Figure 2 shows the distribution after implanting charged particles and hydrogen ions into the semiconductor substrate 10, but before heat treatment at a temperature higher than room temperature (25°C).

[0064] In Figure 2, the horizontal axis shows the depth position from the bottom surface 23, and the vertical axis shows the concentration per unit volume on a logarithmic scale. The chemical concentrations in Figure 2 are measured, for example, by the SIMS method. In Figure 2, the bulk donor concentration N B0 This is indicated by a dashed line. Bulk donor concentration N B0 This can be uniform throughout the semiconductor substrate 10. Furthermore, let Zc be the central depth position in the depth direction of the semiconductor substrate 10.

[0065] Hydrogen chemical concentration C H The distribution has a second peak 141 at depth Z1 and a first peak 133 at depth Z2. Hydrogen chemical concentration C H The hydrogen chemical concentration C shows maximum values ​​at depth positions Z1 and Z2, respectively. H The second peak 141 and the first peak 133 are hydrogen chemistry concentrations C. H It is more than 1000 times larger than the minimum value. The first peak 133 may be larger than the second peak 141. The first peak 133 may be more than 10 times the second peak 141, and may also be more than 100 times.

[0066] Hydrogen chemical concentration C H The distribution shows that the hydrogen chemical concentration C is distributed from the second peak 141 towards the upper surface 21. H The upper tail 143 decreases, and the hydrogen chemical concentration C decreases from the second peak 141 towards the lower surface 23. H It has a lower hem 142 that decreases in value. When hydrogen ions are injected from the lower surface 23, the lower hem 142 is gentler than the upper hem 143. In this specification, a gentle hem means that the position at which the half value of the corresponding peak value is located is further away from the corresponding peak position.

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

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

[0069] Oxygen is often introduced during the production of the ingot and often has a uniform distribution inside the semiconductor substrate 10. The chemical oxygen concentration C OX may be uniform throughout the semiconductor substrate 10. In other examples, the chemical oxygen concentration C OX may increase monotonically or decrease monotonically from the lower surface 23 to the upper surface 21 of the semiconductor substrate 10. Also, 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. The chemical oxygen concentration C OX may decrease monotonically toward the upper surface 21 and the lower surface 23 in the vicinity of 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 a distance of 1 μm from the upper surface 21 or the lower surface 23, but is not limited thereto. Outside the vicinity of the upper surface 21 and the lower surface 23, the chemical oxygen concentration C OX may be uniform as described above, or may increase or decrease monotonically.

[0070] Chemical oxygen concentration C OX is 3×10 15 atoms / cm 3 or more and 2×10 18 atoms / cm 3 or less. When the chemical oxygen concentration C OX of the semiconductor substrate 10 is defined in this specification, unless otherwise specified, the entire region between the second peak 141 and the first peak 133 satisfies the definition of the oxygen concentration. The entire region between the second peak 141 and the lower surface 23 may satisfy the definition of the oxygen concentration, or the entire semiconductor substrate 10 may satisfy the definition of the oxygen concentration. The chemical oxygen concentration C OXmay be 1×10 16 atoms / cm 3 or more, and may also be 1×10 17 atoms / cm 3 or more. The chemical oxygen concentration C OX may be 1×10 18 atoms / cm 3 or less, and may also be 1×10 17 atoms / cm 3 or less.

[0071] The contributing oxygen concentration N OX refers to the concentration of oxygen that forms VOH defects. Since VOH defects contain vacancies and hydrogen in addition to oxygen, the contributing oxygen concentration N OX may change depending on the concentrations of vacancies and hydrogen. In this specification, the ratio of the contributing oxygen concentration N OX to the chemical oxygen concentration C OX is defined as the oxygen contribution rate ξ. That is, ξ = N OX / C OX . The oxygen contribution rate ξ may be considered as the ratio of the concentration of oxygen atoms that constitute VOH defects among the concentrations of all oxygen atoms in a predetermined region (e.g., the depth position from the bottom surface or the top surface). ξ is 0 or more and 1 or less. The unit of the oxygen contribution rate is a dimensionless quantity.

[0072] [[ID=…]] The distribution of the contributing oxygen concentration N OX may be similar to the distribution of the chemical oxygen concentration C OX . For example, 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] The vacancy concentration N V has a vacancy peak 171 at the depth position Zd. The depth position Zd may be the same as the depth position Z1, or may be arranged slightly closer to the bottom surface 23 side than the depth position Z1. The contributing hydrogen concentration N H is related to the vacancy concentration N VIt may have a first contributing concentration peak 161 at the same depth position as the first contributing concentration peak 161.

[0074] When charged particles are injected into the semiconductor substrate 10, damage is introduced in the region from the injection surface of the semiconductor substrate 10 to the range of the charged particles. Damage refers to disorder in the crystal lattice, and can include vacancies, dislocations, and amorphous states. Vacancy concentration N V The peak may also be present at depth Z2. (Vacancy concentration N) V The voltage between the two peaks may be substantially (almost) uniform, monotonically increasing, or monotonically decreasing. If the charged particle is an electron, the vacancy concentration N V The vacancy concentration N may be substantially (almost) uniform from the top to the bottom surface of the semiconductor substrate 10, may increase monotonically, may decrease monotonically, or may have a gentle distribution with a peak at a predetermined depth. V This can be calculated using software known as TRIM (Transport of Ions in Matter), for example (see, for example, http: / / www.srim.org / ; the TRIM manual is disclosed at http: / / srim.org / SRIM / SRIM%2008.pdf and http: / / srim.org / SRIM / SRIM%2009.pdf. Part 2 of the manual describes how to calculate the vacancy concentration). Before heat treatment, it is assumed that most 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 This shows the distribution in the depth direction. Heat treatment causes hydrogen to diffuse from the second peak 141 and the first peak 133 towards the upper surface 21 and the lower surface 23. Even after heat treatment, the relative magnitudes, ratios, and values ​​of the concentrations of each peak, as well as the oxygen chemical concentration, can be the same as before heat treatment as shown in Figure 2. This allows for the hydrogen chemical concentration C between the second peak 141 and the first peak 133. HThe hydrogen concentration increases. In this example, a first peak 133 with a high concentration is provided, so more hydrogen diffuses from the first peak 133. Therefore, in the region from depth position Z2 to depth position Z1, the hydrogen chemical concentration C increases over more than half of the length. H It is decreasing monotonically. Hydrogen chemical concentration C H The depth may decrease monotonically from depth position Z2 to the upper surface 21 side beyond depth position Zc.

[0076] Heat treatment terminates dangling bonds in vacancies with hydrogen. As a result, donors for VOH defects (terminating dangling bonds) are formed. VOH defect concentration N VOH The contributing hydrogen concentration N H , contributing oxygen concentration N OX , vacancy concentration N V It depends on the VOH defect concentration N in this example. VOH The sample has a first VOH peak 191 near depth Z1 and a second VOH peak 181 near depth Z2. The first VOH peak 191 may be located at depth Zd. In this example, the second VOH peak 181 is at a higher concentration than the first VOH peak 191.

[0077] Furthermore, the semiconductor substrate 10 has a flat portion 150 between depth positions Z1 and Z2. The flat portion 150 has a VOH defect concentration N VOH This is a region where the distribution is substantially (almost) flat. The flat portion 150 may be provided over more than half the length between depth position Z1 and depth position Z2, or it may be provided over more than 75% of the length.

[0078] In the flat section 150, the contributing oxygen concentration N OX is the hydrogen chemical concentration C OX It is smaller than this. In this case, the hydrogen chemical concentration C OX The minimum value in the flat section 150 may be used. Contributing oxygen concentration N OX is the hydrogen chemical concentration C OX It may be 10% or less.

[0079] Figure 4 shows the donor concentration D after heat treatment. DThis figure shows an example of the distribution. In Figure 4, the hydrogen chemical concentration C H , oxygen chemical concentration C OX Bulk donor concentration N B0 The combined values ​​are shown. Hydrogen chemical concentration C H and oxygen chemical concentration C OX This is the same as the example in Figure 3. Bulk donor concentration N B0 This is identical to the example in Figure 2.

[0080] In this example, donor concentration D D This is the bulk donor concentration N B0 VOH defect concentration N VOH This is the concentration after adding the other components. Donor concentration N B0 The first donor peak 121 is located at depth Zd, and the second donor peak 111 is located at depth Z2. In this example, the second donor peak 111 has a higher concentration than the first donor peak 121. Also, in the flat section 150, the donor concentration D D It is substantially (almost) flat. Donor concentration D in the flat section 150 D This is the bulk donor concentration N B0 It's higher than that.

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

[0082] Alternatively, with respect to the average concentration of the donor concentration distribution in a predetermined range in the depth direction, the value of the donor concentration distribution may be within ±50%, ±30%, or ±10% of the average concentration of the donor concentration distribution. As described above, the VOH defect concentration N in the flat portion 150 VOH Also, donor concentration D D It is essentially (almost) flat, similar to [another example].

[0083] Figure 5B shows another example of the distribution of bulk donor concentration D0, hydrogen donor concentration Db, and donor concentration Dd in the flat section 150. It differs from the example in Figure 5A in that the flat section 150 has a slope 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 the depth from 20 μm to 80 μm from the hydrogen ion implantation surface. This predetermined region is the area where hydrogen ions penetrate and where there is no localized 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 × 10⁻⁶ 13 / cm 3 This 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 obtained by drawing a straight line connecting the concentrations at both ends of a given region may be called a linear approximation distribution. The linear approximation distribution may also be a straight line obtained by fitting a linear function to the concentrations in the given region. Alternatively, the linear approximation distribution may also be a straight line obtained by fitting a linear function to the distribution obtained by removing the local peaks of each concentration distribution. Furthermore, a band-shaped range centered on the linear approximation distribution and having a width of 30% of the values ​​of the linear approximation distribution is called a band-shaped range. A concentration distribution in a given region is said to increase or decrease monotonically if the concentration values ​​at both ends of the given region are different, and the concentration distribution is included in the band-shaped range described above. The band-shaped range may have a width of 20% or 10% of the values ​​of the linear approximation distribution.

[0085] The linear approximation distribution 214 of the donor concentration Dd is a distribution in which the concentration increases as the distance from the injection surface increases. The concentration of vacancies formed in a predetermined region through which hydrogen ions penetrate is a distribution in which the concentration increases as the distance from the injection surface increases. Diffused hydrogen terminates the dangling bonds present in these formed vacancies, forming a hydrogen donor concentration distribution that follows the vacancy concentration distribution. In this example, in the predetermined region through which hydrogen ions penetrate, the donor concentration Dd fluctuates by approximately ±7% of the linear approximation distribution 214. This fluctuation in the donor concentration Dd is defined as the band-shaped range 216. In other words, the width of the band-shaped range 216 in this example is ±7% of the value of the linear approximation distribution 214. In a predetermined region with a thickness of 30% or more of the thickness of the semiconductor substrate 10, if the distribution of the donor concentration Db is within the band-shaped range 216, the distribution of the donor concentration Db may be considered a flat distribution. That is, this predetermined region may be considered a hydrogen donor flat region. Furthermore, the linear approximation distribution 214 of the donor concentration Dd may be a distribution in which the concentration decreases as the distance from the injection surface increases.

[0086] Figure 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 in Figure 5B in that the slope of the 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 as well, the thickness of the predetermined region relative to the thickness of the semiconductor substrate 10 (120 μm) is 50%, the same as in the example in Figure 5B.

[0087] The linear approximation distribution 214 of the donor concentration Dd is a distribution in which the concentration increases as the distance from the injection surface increases. However, the linear approximation distribution 214 in this example has a steeper slope of increase than the linear approximation distribution 214 in Figure 5B. In addition, in a predetermined region, the donor concentration Dd fluctuates by approximately ±17% relative to the linear approximation distribution 214. This fluctuation in the donor concentration Dd is defined as the band-shaped range 216. The width of the band-shaped range 216 is ±17% of the value of the linear approximation distribution 214. Therefore, in a predetermined region with a thickness of 30% or more of the thickness of the semiconductor substrate 10, if the distribution of the donor concentration Db is within the range of the band-shaped range 216, the distribution of the donor concentration Db may be considered a flat distribution. That is, this predetermined region may be called the 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) with respect to the depth (μm). 3 ·μm) or more, 2×10 12 / (cm 3 It may be less than or equal to μm, and 0 / (cm 3 Larger than μm, 1 × 10 12 / (cm 3 It may be less than or equal to (μm). Furthermore, the absolute value of the slope of the linear approximation distribution 214 in the hydrogen donor flat region is 1 × 10 with respect to depth (μm). 10 / (cm 3 ·μm) or more, 1×10 12 / (cm 3 It may be less than or equal to 1 × 10 10 / (cm 3 ·μm) or more, 5×10 11 / (cm 3 It may be less than or equal to 5 × 10 11 / (cm 3 (μm) is 5 × 10 15 / cm 4 It has the same slope (equivalent).

[0089] As an alternative indicator of the slope of the linear approximation distribution 214, a semi-logarithmic slope may be used. Let the position of one end of a given region be x1 (cm) and the position of the other end be x2 (cm). The concentration at x1 is N1 ( / cm²). 3 ), the concentration at x2 is N2 ( / cm³ 3 Let η = (log) be the semi-logarithmic slope η ( / cm) in a given region. 10 (N2)-log 10 (N1)) / (x2-x1) is defined. The absolute value of the semi-logarithmic slope η of the linear approximation distribution 214 in the hydrogen donor flat 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 flat 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 hydrogen ions have passed, it is thought that vacancies (V, VV, etc.) created by the passage of hydrogen are distributed at a substantially (almost) uniform concentration in the depth direction. Similarly, it is thought that oxygen (O) injected during the manufacturing of the semiconductor substrate 10 is also distributed uniformly in the depth direction. On the other hand, in the manufacturing process of the semiconductor device 100, during the high-temperature treatment process of 1100°C or higher, oxygen may diffuse from the upper surface 21 or lower surface 23 of the semiconductor substrate 10 to the outside of the semiconductor substrate 10. As a result, the oxygen concentration may decrease toward the upper surface 21 or lower surface 23 of the semiconductor substrate 10.

[0091] According to the semiconductor device 100 described in Figures 1 to 5C, the vacancy concentration N depends on the dose of charged particles. V It can be controlled, and the hydrogen chemical concentration C can be controlled by the amount of hydrogen ions. H This allows for control of the donor concentration D in the flat section 150. D This can be easily controlled. Furthermore, 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 rate ξ in the semiconductor substrate 10 will be explained. The final doping concentration at any position from depth position Z1 to depth position Z2 in the completed semiconductor device 100 is N F Let's assume that doping concentration N F This is shown by equation (1). N F =N B0 +N VOH ...Equation (1) Here, the VOH defect concentration N VOH This refers to the concentration of hydrogen-terminated vacancies and the contributing oxygen concentration N OX (i.e., ξC) OX It is assumed to be the sum of ). This is because in the flat section 150, the concentration of VOH defects is rate-limited by the concentration of hydrogen-terminated vacancies and the contributing oxygen concentration. Note that in this example, the hydrogen chemical concentration C H Since the concentration is sufficiently high, virtually all (almost) vacancies from depth Z1 to depth Z2 are terminated with hydrogen. In other words, the vacancy concentration is the hydrogen-terminated vacancy concentration N V We can assume this. Therefore, we obtain equation (2). N VOH =N V +ξC OX ...Equation (2) From equations (1) and (2), equation (3) is obtained. N F =N B0 +N V +ξC OX ...Equation (3)

[0093] Here, the conditions for hydrogen injection and heat treatment are the same, and the bulk donor concentration is N B0 They are the same, and the oxygen chemical concentration C OX We will consider the case where a semiconductor device 100 is formed using two semiconductor substrates with different properties. The final doping concentration in the first semiconductor substrate is set to N F1 The final doping concentration in the second semiconductor substrate is set to N F2 Let's assume that 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 assume that.

[0094] Since the hydrogen injection conditions are the same, the vacancy concentration N in each semiconductor substrate is... V These are identical. Therefore, the oxygen contribution rate ξ is also assumed to be the same in both 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) Here, N F2 >N F1 Let's assume that.

[0095] The difference in final doping concentrations is due to the VOH defect concentration N. VOH The 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 rate ξ is given, then any VOH defect concentration N VOH and oxygen chemical concentration C OX In contrast, vacancy concentration N V It can be calculated.

[0097] Figure 6 shows the increase in donor concentration and the oxygen chemical concentration C. OX This figure shows the relationship. In this example, the carrier concentrations at depth Zc were measured using the SR method for two semiconductor substrates: one before implantation of charged particles and hydrogen ions, and another after implantation of charged particles and hydrogen ions and heat treatment. The difference was defined as the increase in donor concentration. The increase in donor concentration is equal to the VOH defect concentration N. VOH This corresponds to the oxygen chemical concentration C of the semiconductor substrate in this example. OX It is uniformly distributed in the depth direction.

[0098] In Figure 6, the depth position Z1 was set to 100 μm, and hydrogen ions were implanted at depth position Z1. In this example, the dose of hydrogen ions at depth position Z1 was 3 × 10⁻¹⁶. 12 ions / cm 2 , 1 x 10 13 ions / cm 2 , 3 x 10 13 ions / cm 2 The following three types are shown. As shown in Figure 6, oxygen chemical concentration C OX The increase in donor concentration is linearly proportional to this.

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

[0100] Each line is represented by equation (8). N VOH = a × C OX +b...Formula (8) At this time, 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 Furthermore, comparing equations (2) and (8), we find that a=ξ and b=N V That is the case.

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

[0102] Figure 8 shows the hydrogen ion dose, oxygen contribution rate ξ, and vacancy concentration N. V This figure shows the relationship. Figure 8 plots a and b obtained in the example in Figure 6 and approximates them with a curve. In this example, the hydrogen ion dose D at depth position Z1 is H For comparison, the oxygen contribution rate ξ and pore concentration N V This is approximated by a power function. This is the hydrogen ion dose D H This is because, as approaches 0, the oxygen contribution rate ξ is considered to become 0. Approximating the oxygen contribution rate ξ with a logarithmic function, when the oxygen contribution rate ξ becomes 0, the hydrogen ion dose D H The value of the hydrogen ion dose D is a finite value greater than 0. H If it becomes even smaller, the oxygen contribution rate ξ will become a negative value. (Vacancy concentration N) V The same applies to this matter.

[0103] In Figure 8, the relationship between the oxygen contribution rate ξ and the hydrogen ion dose is approximated by curve 801, and the vacancy concentration N VThe relationship between the hydrogen ion dose and the hydrogen ion dose is approximated by curve 802. Curve 801 is expressed by equation (9), and 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) However, c = 3.11503 × 10 -12 d = 5.94169 × 10 -1 N V =e × (D H ) f ...Equation (10) However, e = 1.36398 × 10 6 f = 5.36782 × 10 -1

[0104] Hydrogen ion dose D H If it is too small, the VOH defect concentration N VOH The value decreases. In this case, the bulk donor concentration N B0 It becomes difficult to secure an increase in donor concentration sufficient to absorb the variability. Therefore, the hydrogen ion dose is 1 × 10 11 ions / cm 2 It is preferable that the above conditions are met. In this case, from equation (9), the oxygen contribution rate ξ is 1 × 10 -5 That's all. Also, hydrogen ion dose D H If it is too large, the vacancy concentration N will be higher than the VOH defect concentration that can be formed by the oxygen and hydrogen concentrations. V The value becomes too high. As a result, there are many vacancies that do not become VOH defects. The hydrogen ion dose is 1.2 × 10⁻⁶. 14 ions / cm 2 The following is preferable. In this case, from equation (9), the oxygen contribution rate ξ is 7 × 10 -4 The following applies: In other words, the oxygen contribution rate ξ is 1 × 10⁻⁶. -5 The above 7 x 10 -4 The following may be true: The oxygen contribution rate ξ is 1 × 10⁻⁶ -4 The above is sufficient. The oxygen contribution rate ξ is 5 × 10 -4 The following may be true. Similarly, the vacancy concentration N Vis 1 × 10 11 / cm 3 The above is 1 x 10 14 / cm 3 The following may be true: vacancy concentration N V is 1 × 10 12 / cm 3 The above is sufficient, 1 × 10 13 / cm 3 The above is sufficient. Cavity concentration N V is 3 x 10 13 / cm 3 The following may be true: vacancy concentration N V This is the VOH defect concentration N VOH And, the contributing oxygen concentration N OX The difference (N) VOH -N OX ) may be used to calculate the VOH defect concentration N. VOH This is the final doping concentration N F And, bulk donor concentration N B0 The difference (N) F -N B0 You can calculate it from ).

[0105] Oxygen chemical concentration C OX As such, we will use the typical values ​​for the MCZ substrate. That is, C OX is 1 × 10 17 ~7×10 17 / cm 3 N OX =ξ×C OX Therefore, the contributing oxygen concentration N OX is 1 × 10 12 / cm 3 ~5×10 14 / cm 3 Therefore, from equation (2), N VOH =N V +N OX That is, the VOH defect concentration N VOH is 2 × 10 12 / cm 3 The above 6 x 10 14 / cm 3 The following is acceptable: VOH defect concentration N VOH is 1 × 10 13 / cm 3 The above is sufficient. VOH defect concentration N VOHis 5 x 10 14 / cm 3 The following is acceptable:

[0106] Figure 9 shows the hydrogen ion dose, oxygen contribution rate ξ, and vacancy concentration N. V This figure shows the relationship between the oxygen contribution rate ξ and the hydrogen ion dose. Figure 9 corresponds to the example in Figure 7 (i.e., Z1 = 50 μm). In Figure 9, the relationship between the oxygen contribution rate ξ and the hydrogen ion dose is approximated by curve 901, and the vacancy concentration N V The relationship between the hydrogen ion dose and the hydrogen ion dose is approximated by curve 902. Curve 901 is expressed by equation (12), and 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) However, c = 1.53343 × 10 -12 d = 6.25800 × 10 -1 N V =e × (D H ) f ...Equation (12) However, e = 3.11098 × 10 3 f = 7.41056 × 10 -1

[0107] In this example as well, the oxygen contribution rate ξ may be within the same range as in the example in Figure 8. (Vacancy concentration N) V This range may be the same as the example in Figure 8. Contributing oxygen concentration N OX The range may also be the same as in the example in Figure 8. The VOH defect concentration may also be the same as in the example in Figure 8.

[0108] In the flat section 150, the oxygen chemical concentration C OX The maximum value O max And the minimum value O min Let ν be the ratio to ν. That is, ν = O min / O max The ratio ν may be between 0.1 and 1. When the ratio ν is small, the VOH defect concentration N VOHThe variation in the depth direction may increase, potentially degrading the breakdown voltage of the semiconductor substrate 10. The ratio ν may be 0.3 or greater, or 0.5 or greater. The ratio ν may be 0.95 or less, or 0.9 or less.

[0109] The flat portion 150 may contain carbon. The carbon chemical concentration of the flat portion 150 is 1 × 10⁻⁶. 13 atoms / cm 3 The above is 1 x 10 16 atoms / cm 3 The following is acceptable: The carbon chemical concentration is 1 × 10⁻⁶. 14 atoms / cm 3 The above is acceptable. The carbon chemical concentration is 5 × 10 15 atoms / cm 3 The following may be true: 2 × 10 15 atoms / cm 3 The following may also be used: VOH defect concentration N VOH The contribution of carbon chemical concentration to this will be discussed later.

[0110] Figure 10 is a top view showing an example of a semiconductor device 100. In Figure 10, the positions of each component projected onto the top surface of the semiconductor substrate 10 are shown. In Figure 10, only some components of the semiconductor device 100 are shown, 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 Figures 1 to 9. However, the semiconductor substrate 10 may also have other concentration peaks different from the concentration peaks described in Figures 1 to 9. In some cases, an N-type region may be formed in the semiconductor substrate 10 by implanting hydrogen ions, as in the buffer region 20 described later. In this case, the hydrogen chemical concentration distribution may have local hydrogen concentration peaks in addition to the hydrogen chemical concentration distribution described in Figure 2, etc. Also, in some cases, an N-type region may be formed in the semiconductor substrate 10 by implanting N-type impurities other than hydrogen, such as phosphorus, as in the emitter region 12 described later. In this case, the donor concentration distribution may have local donor concentration peaks in addition to the donor concentration distribution described in Figure 4, etc.

[0112] The semiconductor substrate 10 has edges 162 when viewed from above. In this specification, "viewed from above" simply means viewing the semiconductor substrate 10 from the top side. In this example, the semiconductor substrate 10 has two pairs of edges 162 that face each other when viewed from above. In Figure 10, the X and Y axes are parallel to either edge 162, and the Z axis is perpendicular to the top surface of the semiconductor substrate 10.

[0113] The semiconductor substrate 10 is provided with an active section 160. The active section 160 is a region in which the main current flows in the depth direction between the upper and lower surfaces of the semiconductor substrate 100 when the semiconductor device 100 is operating. An emitter electrode is provided above the active section 160, but it is omitted in Figure 10.

[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 freewheeling diode (FWD). In the example shown in Figure 10, the transistor section 70 and the diode section 80 are arranged alternately along a predetermined arrangement direction (in this example, the X-axis direction) on the upper surface of the semiconductor substrate 10. In other examples, the active section 160 may be provided with only one of the transistor section 70 and the diode section 80.

[0115] In Figure 10, the region where the transistor section 70 is located is denoted by the symbol "I," and the region where the diode section 80 is located is denoted by the symbol "F." In this specification, the direction perpendicular to the arrangement direction in a top view may be referred to as the extension direction (Y-axis direction in Figure 10). The transistor section 70 and the diode section 80 may each have their longitudinal length in the extension direction. That is, the length of the transistor section 70 in the Y-axis direction is greater than its width in the X-axis direction. Similarly, the length of the diode section 80 in the Y-axis direction is greater than its width in the X-axis direction. The extension direction of the transistor section 70 and the diode section 80 may be the same as the longitudinal direction of each trench section described later.

[0116] The diode section 80 has an N+ type cathode region in the area in contact with the lower surface of the semiconductor substrate 10. In this specification, the region in which the cathode region is provided is referred to as the diode section 80. In other words, the diode section 80 is the region that overlaps with the cathode region when viewed from above. A P+ type collector region may be provided on the lower surface of the semiconductor substrate 10 in areas other than the cathode region. In this specification, an extension region 81, which is an extension of the diode section 80 in the Y-axis direction to the gate wiring described later, may also be included in the diode section 80. A collector region is provided on the lower surface of the extension region 81.

[0117] The transistor section 70 has a P+ type collector region in the area in contact with the lower surface of the semiconductor substrate 10. Furthermore, the transistor section 70 has a gate structure periodically arranged on the upper surface side of the semiconductor substrate 10, which includes an N type emitter region, a P type base region, a gate conductive portion, and a gate insulating film.

[0118] The semiconductor device 100 may have one or more pads on the semiconductor substrate 10. In this example, the semiconductor device 100 has a gate pad 164. The semiconductor device 100 may also have pads such as an anode pad, a cathode pad, and a current sensing pad. Each pad is located near the edge 162. The vicinity of the edge 162 refers to the area 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 wires.

[0119] A gate potential is applied to the gate pad 164. The gate pad 164 is electrically connected to the conductive portion of the gate trench of the active portion 160. The semiconductor device 100 is provided with gate wiring that connects the gate pad 164 to the gate trench. In Figure 10, the gate wiring is hatched with diagonal lines.

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

[0121] The active gate wiring 131 is provided in the active section 160. By providing the active gate wiring 131 in the active section 160, variations in the wiring length from the gate pad 164 can be reduced for each region of the semiconductor substrate 10.

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

[0123] The active gate wiring 131 may be connected to the outer gate wiring 130. In this example, the active gate wiring 131 extends in the X-axis direction, crossing the active section 160 from one outer gate wiring 130 to the other outer gate wiring 130 approximately in the center in the Y-axis direction. When the active section 160 is divided by the active gate wiring 131, the transistor section 70 and the diode section 80 may be arranged alternately in the X-axis direction in each divided region.

[0124] Furthermore, the semiconductor device 100 may also include a temperature sensing unit (not shown) which is a PN junction diode made of polysilicon or the like, and a current detection unit (not shown) which simulates the operation of a transistor unit provided in the active unit 160.

[0125] In this example, the semiconductor device 100 includes an edge termination structure 90 between the active portion 160 and the edge 162 when viewed from above. In this example, the edge termination structure 90 is positioned between the outer peripheral gate wiring 130 and the edge 162. The edge termination structure 90 mitigates electric field concentration on the upper surface side of the semiconductor substrate 10. The edge termination structure 90 may include at least one of a guard ring, a field plate, and a resurf, which are provided in an annular shape surrounding the active portion 160.

[0126] Figure 11 is an enlarged view of region D in Figure 10. Region D is the region including the transistor section 70, the diode section 80, and the active gate wiring 131. The semiconductor device 100 in this example includes a gate trench section 40, a dummy trench section 30, a well section 11, an emitter section 12, a base section 14, and a contact section 15, which are provided inside the upper surface of the semiconductor substrate 10. The gate trench section 40 and the dummy trench section 30 are examples of trench sections. The semiconductor device 100 in this example also includes an emitter electrode 52 and an active gate wiring 131, which are provided above the upper surface of the semiconductor substrate 10. The emitter electrode 52 and the active gate wiring 131 are provided separately from each other.

[0127] An interlayer insulating film is provided between the emitter electrode 52 and the active gate wiring 131 and the upper surface of the semiconductor substrate 10, but this is omitted in Figure 11. Contact holes 54 are provided in the interlayer insulating film in this example, penetrating the film. In Figure 11, each contact hole 54 is hatched with diagonal lines.

[0128] The emitter electrode 52 is provided above the gate trench 40, dummy trench 30, well region 11, emitter region 12, base region 14, and contact region 15. The emitter electrode 52 contacts the emitter region 12, contact region 15, and base region 14 on the upper surface of the semiconductor substrate 10 through a contact hole 54. The emitter electrode 52 is also connected to a dummy conductive portion in the dummy trench 30 through a contact hole provided in the interlayer insulating film. The emitter electrode 52 may also be connected to a dummy conductive portion of the dummy trench 30 at its tip in the Y-axis direction.

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

[0130] The emitter electrode 52 is formed from a material containing metal. Figure 11 shows the area in which the emitter electrode 52 is provided. For example, at least a portion of the emitter electrode 52 is formed from aluminum or an aluminum-silicon alloy, such as AlSi or AlSiCu. The emitter electrode 52 may have a barrier metal formed from titanium or a titanium compound in the layer below the region formed from aluminum or the like. Furthermore, it may have a plug formed by embedding tungsten or the like in the contact hole so as to be in contact with the barrier metal and the aluminum or the like.

[0131] The well region 11 is provided overlapping with the active gate wiring 131. The well region 11 also extends to a predetermined width in an area that does not overlap with the active gate wiring 131. In this example, the well region 11 is provided away from the Y-axis end of the contact hole 54 towards the active gate wiring 131. The well region 11 is a second conductivity type region with a higher doping concentration than the base region 14. In this example, the base region 14 is P-type, and the well region 11 is P+ type.

[0132] Each of the transistor section 70 and the diode section 80 has multiple trench sections arranged in the direction of arrangement. In this example, the transistor section 70 has one or more gate trench sections 40 and one or more dummy trench sections 30 alternately provided along the direction of arrangement. In this example, the diode section 80 has multiple dummy trench sections 30 provided along the direction of arrangement. In this example, the diode section 80 does not have gate trench sections 40.

[0133] The gate trench portion 40 in this example may have two linear portions 39 (the trench portion which is linear along the extension direction) that extend along the extension direction perpendicular to the alignment direction, and a tip portion 41 that connects the two linear portions 39. In Figure 11, the extension direction is the Y-axis direction.

[0134] Preferably, at least a portion of the tip portion 41 is provided in a curved shape when viewed from above. By connecting the ends of the two straight portions 39 in the Y-axis direction with the tip portion 41, electric field concentration at the ends of the straight portions 39 can be mitigated.

[0135] In the transistor section 70, the dummy trench section 30 is provided between each of the straight sections 39 of the gate trench section 40. There may be one dummy trench section 30 between each of the straight sections 39, or there may be multiple dummy trench sections 30. The dummy trench section 30 may have a straight shape extending in the extension direction, and like the gate trench section 40, it may have a straight section 29 and a tip section 31. The semiconductor device 100 shown in Figure 11 includes both a dummy trench section 30 with a straight shape without a tip section 31 and a dummy trench section 30 with a tip section 31.

[0136] The diffusion depth of the well region 11 may be deeper than the depth of the gate trench portion 40 and the dummy trench portion 30. The Y-axis ends of the gate trench portion 40 and the dummy trench portion 30 are located in the well region 11 when viewed from above. In other words, at the Y-axis end of each trench portion, the bottom in the depth direction of each trench portion is covered by the well region 11. This makes it possible to mitigate electric field concentration at the bottom of each trench portion.

[0137] In the arrangement direction, mesa portions are provided between each trench portion. A mesa portion refers to a region within the semiconductor substrate 10 that is sandwiched between trench portions. For example, the upper end of a mesa portion is the upper surface of the semiconductor substrate 10. The depth position of the lower end of a mesa portion is the same as the depth position of the lower end of a trench portion. In this example, the mesa portion is provided on the upper surface of the semiconductor substrate 10, extending along the trench in the extension direction (Y-axis direction). In this example, a mesa portion 60 is provided in the transistor portion 70, and a mesa portion 61 is provided in the diode portion 80. In this specification, when simply referred to as a mesa portion, it refers to mesa portion 60 and mesa portion 61, respectively.

[0138] Each mesa portion is provided with a base region 14. Of the base regions 14 exposed on the upper surface of the semiconductor substrate 10 in the mesa portion, the region closest to the active gate wiring 131 is defined as base region 14-e. Figure 11 shows the base region 14-e located at one end of each mesa portion in the extending direction, but a base region 14-e is also located at the other end of each mesa portion. In each mesa portion, at least one of a first conductivity type emitter region 12 and a second conductivity type contact region 15 may be provided in the region sandwiched between the base regions 14-e in a top view. In this example, the emitter region 12 is N+ type and the contact region 15 is P+ type. The emitter region 12 and the contact region 15 may be provided in the depth direction between the base region 14 and the upper surface of the semiconductor substrate 10.

[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 have a contact region 15 exposed on the upper surface of the semiconductor substrate 10.

[0140] Each of the contact region 15 and emitter region 12 in the mesa portion 60 extends from one trench portion to the other in the X-axis direction. As an example, the contact region 15 and emitter region 12 of the mesa portion 60 are arranged alternately along the extension direction (Y-axis direction) of the trench portion.

[0141] In other examples, the contact region 15 and emitter region 12 of the mesa portion 60 may be arranged in a stripe pattern along the extension direction (Y-axis direction) of the trench portion. For example, the emitter region 12 may be provided in the region in contact with the trench portion, and the contact region 15 may be provided in the region sandwiched between the emitter regions 12.

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

[0143] A contact hole 54 is provided above each mesa portion. The contact holes 54 are located in the region sandwiched between the base region 14-e. In this example, the contact holes 54 are provided above the contact region 15, the base region 14, and the emitter region 12. The contact holes 54 are not provided in the region corresponding to the base region 14-e and the well region 11. The contact holes 54 may be located in the center of the mesa portion 60 in the alignment direction (X-axis direction).

[0144] In the diode section 80, an N+ type cathode region 82 is provided in the region adjacent to the lower surface of the semiconductor substrate 10. In the region on the lower surface of the semiconductor substrate 10 where the cathode region 82 is not provided, a P+ type collector region 22 may be provided. 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 Figure 11, the boundary between the cathode region 82 and the collector region 22 is shown by a dotted line.

[0145] The cathode region 82 is positioned away from the well region 11 in the Y-axis direction. This ensures a distance between the cathode region 82 and the P-type region (well region 11), which has a relatively high doping concentration and is formed to a deep position, thereby improving pressure resistance. In this example, the Y-axis end of the cathode region 82 is positioned further from the well region 11 than the Y-axis end of the contact hole 54. In other examples, the Y-axis end of the cathode region 82 may be positioned between the well region 11 and the contact hole 54.

[0146] Figure 12 shows an example of the ee cross-section in Figure 11. The ee cross-section is the XZ plane passing through the emitter region 12 and the cathode region 82. In this example, the semiconductor device 100 has a semiconductor substrate 10, an interlayer insulating film 38, an emitter electrode 52, and a collector electrode 24 in this cross-section.

[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 that includes at least one layer of insulating film such as silicate glass with impurities such as boron or phosphorus added, a thermal oxide film, and other insulating films. The interlayer insulating film 38 is provided with contact holes 54 as described in Figure 11.

[0148] The emitter electrode 52 is located above the interlayer insulating film 38. The emitter electrode 52 is in contact with the upper surface 21 of the semiconductor substrate 10 through a contact hole 54 in the interlayer insulating film 38. The collector electrode 24 is located on the lower surface 23 of the semiconductor substrate 10. The emitter electrode 52 and the collector electrode 24 are made of a metallic material such as aluminum. In this specification, the direction connecting the emitter electrode 52 and the collector electrode 24 (Z-axis direction) is referred to as the depth direction.

[0149] The semiconductor substrate 10 has an N-type or N-type drift region 18. The drift region 18 is provided in both the transistor section 70 and the diode section 80.

[0150] In the mesa portion 60 of the transistor portion 70, an N+ type emitter region 12 and a P- type base region 14 are provided in order from the upper surface 21 side of the semiconductor substrate 10. A drift region 18 is provided below the base region 14. An N+ type storage region 16 may also be provided in the mesa portion 60. The storage region 16 is located between the base region 14 and the 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 doping concentration of the emitter region 12 is higher than that of the drift region 18.

[0152] The base region 14 is located below the emitter region 12. In this example, the base region 14 is located in contact with the emitter region 12. The base region 14 may be in contact with the trenches on both sides of the mesa region 60.

[0153] The storage region 16 is located below the base region 14. The storage region 16 is an N+ type region with a higher doping concentration than the drift region 18. By providing a high-concentration storage region 16 between the drift region 18 and the base region 14, the carrier injection promotion effect (IE effect) can be enhanced, and the on-voltage can be reduced. The storage 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 portion 80, in contact with the upper surface 21 of the semiconductor substrate 10. A drift region 18 is provided below the base region 14. A storage region 16 may also be provided below the base region 14 in the mesa portion 61.

[0155] In both the transistor section 70 and the diode section 80, an N+ type buffer section 20 may be provided below the drift section 18. The doping concentration in the buffer section 20 is higher than the doping concentration in the drift section 18. The buffer section 20 has a peak 25 with a higher doping concentration than the drift section 18. The doping concentration of peak 25 refers to the doping concentration at the peak of peak 25. Furthermore, the doping concentration of the drift section 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, hydrogen (proton) or phosphorus concentration peaks. The buffer region 20 may function as a field stop layer that prevents the 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 denoted as 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 that of the base region 14. The collector region 22 may contain the same acceptors as the base region 14, or it may contain different acceptors. The acceptors of the collector region 22 are, for example, boron.

[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 donors and acceptors for each region are not limited to the examples described above. The collector region 22 and the cathode region 82 are exposed to the lower surface 23 of the semiconductor substrate 10 and are connected to the collector electrode 24. The collector electrode 24 may be in contact with the entire lower surface 23 of the semiconductor substrate 10. The emitter electrode 52 and the collector electrode 24 are formed of a metallic material such as aluminum.

[0159] One or more gate trenches 40 and one or more dummy trenches 30 are provided on the upper surface 21 of the semiconductor substrate 10. Each trench extends from the upper surface 21 of the semiconductor substrate 10, through the base region 14, and reaches the drift region 18. In regions where at least one of the emitter region 12, contact region 15, and storage region 16 is provided, each trench also extends through these doping regions and reaches the drift region 18. The statement that a trench penetrates a doping region is not limited to manufacturing in the order of forming the doping region before forming the trench. Manufacturing in which doping regions are formed between the trenches after the trenches have been formed is also included in the statement that a trench penetrates a doping region.

[0160] As described above, the transistor section 70 is provided with a gate trench section 40 and a dummy trench section 30. The diode section 80 is provided with a dummy trench section 30, but not with a gate trench section 40. In this example, the boundary between the diode section 80 and the transistor section 70 in the X-axis direction is the boundary between the cathode region 82 and the collector region 22.

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

[0162] The gate conductive portion 44 may be longer than the base region 14 in the depth direction. The gate trench portion 40 in this cross-section is covered by an interlayer insulating film 38 on the upper surface 21 of the semiconductor substrate 10. The gate conductive portion 44 is electrically connected to the gate wiring. When a predetermined gate voltage is applied to the gate conductive portion 44, a channel formed by an electron inversion layer is formed on the surface layer of the interface of the base region 14 that is in contact with the gate trench portion 40.

[0163] The dummy trench portion 30 may have the same structure as the gate trench portion 40 in its cross-section. The dummy trench portion 30 includes a dummy trench, a dummy insulating film 32, and a dummy conductive portion 34 provided on the upper surface 21 of the semiconductor substrate 10. The dummy conductive portion 34 is electrically connected to the emitter electrode 52. The dummy insulating film 32 is provided covering the inner wall of the dummy trench. The dummy conductive portion 34 is provided inside the dummy trench and is located inside the dummy insulating film 32. The dummy insulating film 32 insulates the dummy conductive portion 34 from the semiconductor substrate 10. The dummy conductive portion 34 may be formed from the same material as the gate conductive portion 44. For example, the dummy conductive portion 34 may be formed from a conductive material such as polysilicon. The dummy conductive portion 34 may have the same length as the gate conductive portion 44 in the depth direction.

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

[0165] The drift region 18 may include the flat portion 150 described in Figure 4, etc. In other words, the drift region 18 has donor concentrations mainly determined by the bulk donor concentration and the hydrogen donor (VOH defect) concentration. The drift region 18 has a hydrogen chemical concentration C H A second peak, 141, may be present. Dopants are locally injected into regions other than the drift region 18. Therefore, the doping concentration in these regions is the donor concentration D as explained in Figure 4, etc. D It is different.

[0166] Figure 13 shows an example of the carrier concentration distribution in the depth direction at the location of the FF line in Figure 12. In Figure 13, the hydrogen concentration distribution C H A portion of the above is shown together. The vertical axis in Figure 13 is a logarithmic axis.

[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. Peaks 25 are donor concentration peaks. Peaks 25 may contain hydrogen as an impurity. By providing multiple peaks 25, the depletion layer reaching the collector region 22 can be further suppressed. The second donor peak 111 may function as any of the peaks 25 in the buffer region 20.

[0168] For example, the second donor peak 111 may function as the peak furthest from the bottom surface 23 of the semiconductor substrate 10 among the multiple peaks 25 of the buffer region 20. The flat portion 150 is located between the second donor peak 111 and the first donor peak 121, which are included in the buffer region 20.

[0169] The second donor peak 111 may have a higher donor concentration than the peak 25 furthest from the bottom surface 23 among the multiple peaks 25 in the buffer region 20. Increasing the concentration of the second donor peak 111 makes it easier to form the flat region 150. Hydrogen chemical concentration distribution C H The layer may have one or more hydrogen concentration peaks 194 between the depth position Z2 and the bottom surface 23. The hydrogen concentration peaks 194 may be located in the buffer region 20. The 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. Peaks 26 are peaks of donor concentration. The first donor peak 121 in this example is located on the lower surface 23 side of the accumulation region 16. Between the first donor peak 121 and the accumulation region 16, there may be a region 180 with a lower doping concentration than the flat portion 150. The doping concentration in region 180 is equal to the bulk donor concentration N B0 That's fine.

[0171] Furthermore, the semiconductor device 100 may use a non-doped substrate as the semiconductor substrate 10, in which dopants such as phosphorus (P) are not doped throughout the ingot during semiconductor ingot manufacturing. In this case, the base doping concentration Dn in region 180 is equal to the bulk doping concentration N B0 It is lower than that. The base doping concentration Dn is, for example, 1 × 10⁻⁶. 10 atoms / cm 3 The above 5 x 10 12 atoms / cm 3 The following applies: The base doping concentration Dn is 1 × 10⁻⁶ 11 atoms / cm 3 The above is acceptable. The base doping concentration Dn is 5 × 10 12 atoms / cm 3 The following is acceptable:

[0172] Figure 14 shows an example of the gg cross-section in Figure 10. The cross-section shown in Figure 14 is the XZ plane including the edge termination structure 90 and the transistor section 70. Between the edge termination structure 90 and the transistor section 70, an outer peripheral gate wiring 130 is arranged above the semiconductor substrate 10. The outer peripheral gate wiring 130 is provided separately from the emitter electrode 52. Also, between the edge termination structure 90 and the transistor section 70, a well region 11 is arranged on the upper surface 21 of the semiconductor substrate 10. In this example, the well region 11 is provided in a range shallower than the trench section. The structure of the transistor section 70 is the same as the transistor section 70 described in Figures 10 to 12.

[0173] The edge termination structure 90 is provided with a plurality of guard rings 92, a plurality of field plates 94, and a channel stopper 174. In the edge termination structure 90, a collector region 22 may be provided in the region in contact with the lower surface 23. Each guard ring 92 may be provided so as to surround the active portion 160 on the upper surface 21. The plurality of guard rings 92 may have the function of spreading the depletion layer generated in the active portion 160 to the outside of the semiconductor substrate 10. This prevents electric field concentration inside the semiconductor substrate 10 and improves the breakdown voltage of the semiconductor device 100.

[0174] In this example, the guard ring 92 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 bottom of the gate trench portion 40 and the dummy trench portion 30.

[0175] The upper surface of the guard ring 92 is covered by an 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 through holes provided in the interlayer insulating film 38.

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

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

[0178] Figure 15 shows another example of the gg section in Figure 10. In this example, the well region 11 extends deeper than the lower ends of the gate trench 40 and the dummy trench 30. Other structures may be the same as in the example in Figure 14. In this section, at least one trench may be located inside the well region 11. In the example in Figure 15, the trench closest to the edge termination structure 90 is located inside the 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 other examples, 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] Figure 16 shows an example of a manufacturing method for semiconductor device 100. The manufacturing method in this example comprises a substrate preparation step S1600, a device manufacturing step S1606, a concentration measurement step S1602, and an injection volume 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 of the semiconductor substrate 10 is measured. OX The following is measured. In the concentration measurement step S1602, the oxygen chemical concentration may be measured by FTIR (infrared absorption spectroscopy). In addition, in the concentration measurement step S1602, the substrate resistance value (Ω·cm) of the semiconductor substrate 10 may be further measured.

[0182] In the injection amount calculation step S1604, the amount of charged particle beam to be injected into 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 amount of charged particle beam injected. In the injection amount calculation step S1604, the amount of charged particle beam injected may be calculated so that the substrate resistance value of the flat section 150, as explained in Figure 4, etc., 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 section 150 corresponds one-to-one with the donor concentration of the flat section 150. Therefore, the amount of increase in donor concentration that makes the substrate resistance value of the flat section 150 become the target resistance value is determined. The relationship between the amount of charged particle beam injected, the amount of increase in donor concentration, and the oxygen chemical concentration can be experimentally obtained in advance, as shown in Figures 6 and 7. In the injection amount calculation step S1604, the amount of charged particle beam injected may be calculated based on the above relationship obtained in advance.

[0183] Substituting equations (11) and (12) above into equation (2), we obtain equation (13). N VOH = c × (D H ) d +e×(D H ) f ×C OX ...Equation (13) Furthermore, equations (1) through (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 This is the set value, and the bulk donor concentration N B0 This is known from measured values ​​or semiconductor wafer specifications. Oxygen chemical concentration C OX This is known from measurements in S1602. The parameters c, d, e, and f can be obtained experimentally beforehand as described above. Therefore, the variables in equation (14) are the amount of charged particles injected (in this example, the dose of hydrogen ions D) H ) is the only value. By numerically solving equation (14), the amount of charged particles injected can be calculated. The amount of charged particles injected D obtained from equation (14) H This may have a width (error) that reflects the variability of the values ​​of each data in the fitting of equations (8), (10), and (11). That is, the amount of charged particles injected D H If the value obtained from equation (13) or equation (14) is within a range of, for example, ±50%, then it can be considered to be the value obtained from equation (13) or equation (14).

[0185] The device manufacturing step S1606 in this example includes a particle injection step S1608, a hydrogen injection step S1610, and a heat treatment step S1612. The device manufacturing step S1606 includes steps to form each of the components described in Figures 10 to 12, but these are omitted in Figure 16.

[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 a second peak 141 as shown in Figure 2. Also, the vacancy concentration N as shown in Figure 2 V A distribution is formed. The amount of charged particle beam injected in S1608 is adjusted to the amount of injection calculated in injection amount calculation step S1604. This makes it possible to form vacancies of a concentration such that the flat portion 150 has the target resistance value.

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

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

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

[0190] Prior to the particle injection step S1608, the structure on the upper surface 21 side of the semiconductor substrate 10, as shown in Figure 12, may be formed. The structure on the upper surface 21 side may include each trench, emitter region 12, base region 14, storage region 16, interlayer insulating film 38, and emitter electrode 52. In addition, the cathode region 82 and collector region 22 may be formed prior to the particle injection step S1608. In the particle injection step S1608, the charged particle beam may be injected at a depth position Z1 on the lower surface 23 side of the lower end of the gate trench 40. This suppresses damage caused by the charged particle beam injection from affecting the gate insulating film 42.

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

[0192] In the upper graph, the target value for the donor concentration increase is shown by a dashed line. The target increase is the amount required to bring the resistance value in the flat section 150 to the target value. From the upper graph, the oxygen chemical concentration corresponding to the target increase is obtained at 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 at lines 602 and 603. In addition, the relationship between the reciprocal of the oxygen chemical concentration and the hydrogen ion dose is approximated by a curve in the lower graph.

[0193] If the relationship shown in the lower graph is obtained in advance, the amount of hydrogen ion dose to be injected can be calculated from the oxygen chemical concentration of the semiconductor substrate 10 used in the manufacture of the semiconductor device 100. For example, if the oxygen chemical concentration of the semiconductor substrate 10 is 3.7 × 10⁻⁶ 17 atoms / cm 3 In this case, the reciprocal of the oxygen chemical concentration is 2.8 × 10⁻⁶. -18 Therefore, from the relationship shown in the lower graph, 2.8 × 10 -18 The corresponding hydrogen ion dose is 4.2 × 10⁻⁶. 12 ions / cm 2 This can be calculated. 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 amount of hydrogen ion dose to be injected can be calculated from the target increase in donor concentration and oxygen chemical concentration.

[0194] Figure 18 shows another example of a method for manufacturing the semiconductor device 100. This example further includes an oxygen introduction step S1802 compared to the example shown in Figure 16. The other steps are the same as in the example in Figure 16. The oxygen introduction step S1802 is performed before the particle implantation step S1608.

[0195] The oxygen introduction step S1802 introduces oxygen 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 is within a predetermined range. Introducing oxygen into the semiconductor substrate 10 makes it easier to adjust the donor concentration in the flat portion 150. For example, even if the oxygen chemical concentration in the semiconductor substrate 10 prepared in S1600 is low and sufficient VOH defects cannot be formed, the oxygen chemical concentration can be increased by introducing oxygen into the semiconductor substrate 10.

[0196] The oxygen chemical concentration introduced in the oxygen introduction step S1802 (referred to as the introduced concentration) may be greater than the oxygen chemical concentration of the semiconductor substrate 10 before the oxygen introduction step S1802 (referred to as the original concentration). Since the introduced concentration can be precisely controlled by the above-mentioned conditions such as the temperature, time, and oxygen concentration in the atmosphere of the heat treatment, the variation in the oxygen chemical concentration of the semiconductor substrate 10 can be reduced by making the ratio of the introduced concentration greater than the original concentration. The introduced concentration may be twice or more the original concentration, five times or more, or even ten times or more.

[0197] In the oxygen introduction step S1802, oxygen may be introduced into the semiconductor substrate 10 according to the oxygen chemical concentration measured in the concentration measurement step S1602. For example, oxygen may be introduced so that the sum of the oxygen chemical concentration introduced in the oxygen introduction step S1802 and the oxygen chemical concentration measured in the concentration measurement step S1602 equals a predetermined target value. In the concentration measurement step S1802, the oxygen chemical concentration of the semiconductor substrate 10 after the oxygen introduction step S1802 may be measured. In this case, the amount of charged particle beam injected can be calculated with even greater accuracy.

[0198] Figure 19 shows an example of device manufacturing step S1606. In this example, device manufacturing step S1606 has an upper surface process S1902 and a lower surface process S1904. The upper surface process S1902 is a step in which the structure on the upper surface 21 of the semiconductor substrate 10 is formed. The structure on the upper surface 21 includes, for example, a trench, an emitter region 12, a base region 14, a storage 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 lower surface process S1904 is a step in which the structure on the lower surface 23 of the semiconductor substrate 10 is formed. The structure on the lower surface 23 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 upper surface process S1902. The oxygen introduction step S1802 may also serve as a heat treatment step to form the structure on the upper surface 21. For example, the oxygen introduction step S1802 may be a heat treatment step performed after injecting a dopant into the emitter region 12, base region 14, or storage region 16.

[0200] In this example, the lower side process S1904 includes a particle injection step S1608, a hydrogen injection step S1610, and a heat treatment step S1612. The hydrogen injection step S1610 and the heat treatment step S1612 may be part of the process that forms the buffer region 20. That is, the hydrogen injection step S1610 may form one of the peaks 25 of the buffer region 20. The heat treatment step S1612 may be performed after injecting hydrogen ions at the positions of multiple peaks 25 of the buffer region 20.

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

[0202] Figure 21 shows the relationship between the oxygen contribution rate ξ and the depth position Z1 where the second peak 141 is located. In Figure 21, the hydrogen ion dose is 3 × 10⁻⁶. 14 ions / cm 2 , 1 x 10 14 ions / cm 2 , 3 x 10 13 ions / cm 2 , 1 x 10 13 ions / cm 2 , 3 x 10 12 ions / cm 2 , or 1 × 10 12 ions / cm 2 For each of these cases, the relationship between the oxygen contribution rate ξ and the depth position Z1 is shown.

[0203] As shown in Figures 8 and 9, the oxygen contribution rate ξ changes with depth Z1. Each point plotted by a square in Figure 8 is plotted at the depth position Z1 = 100 μm in Figure 21. Similarly, each point plotted by a square in Figure 9 is plotted at the depth position Z1 = 50 μm in Figure 21. Furthermore, a plot at the depth position Z1 = 150 μm is added to Figure 21. Hydrogen ion dose is 3 × 10⁻⁶ 14 ions / cm 2 , 1 x 10 14 ions / cm 2 , and 1 × 10 12 ions / cm2 The plots for this are omitted in Figure 21. These plots are shown as thick lines in Figure 21, which are linear approximations (linear x-axis, common logarithmic x-axis) obtained by the least squares method for each hydrogen ion dose. The oxygen contribution rate ξ may decrease exponentially with respect to depth Z1.

[0204] The relationship shown in Figure 21 and the hydrogen ion dose D relative to the depth position Z1. H From the depth position Z1, the oxygen contribution rate ξ can be detected. The depth position Z1 can be measured from the position of the peak in the hydrogen chemical concentration distribution of the semiconductor device 100. Also, the dose amount D H This can be measured by integrating the hydrogen chemical concentration in the depth direction for a bell-shaped peak of hydrogen chemical concentration with its peak at depth position Z1. The integration range may, for example, be the total width at 10% of the peak value of the hydrogen chemical concentration (FW10%M). Alternatively, the dose amount D... H This value may be obtained by multiplying the peak value of the hydrogen chemical concentration by the full width at half maximum (FWHM).

[0205] For example, if the depth position Z1 is 120 μm, and the dose amount D H 5 x 10 12 ions / cm 2 This case is shown by a black circle in Figure 21. In this case, the oxygen contribution rate ξ is approximately ξ = 1.2 × 10⁻⁶. -4 This is the case. Let this value be ξ1.

[0206] Figure 22 shows the vacancy concentration N V This figure shows the relationship between the second peak 141 and the depth position Z1 where it is located. In Figure 21, the hydrogen ion dose is 3 × 10⁻⁶. 14 ions / cm 2 , 1 x 10 14 ions / cm 2 , 3 x 10 13 ions / cm 2 , 1 x 10 13 ions / cm 2 , 3 x 10 12 ions / cm 2 , or 1 × 10 12 ions / cm2 For each case, the relationship between the oxygen contribution rate ξ and the depth position Z1 is shown. As shown in Figures 8 and 9, the pore concentration N V Similar to the oxygen contribution rate ξ, this also changes with depth position Z1. The graph in Figure 22 was created in the same way as the graph in Figure 21. Vacancy concentration N V This may decrease exponentially with respect to the depth position Z1.

[0207] The relationship shown in Figure 22 and the hydrogen ion dose D relative to the depth position Z1. H And, from depth position Z1, pore concentration N V It can detect depth position Z1 and dose amount D. H This can be measured from the semiconductor device 100, as explained in Figure 21. For example, if the depth position Z1 is 120 μm and the dose amount D H 5 x 10 12 ions / cm 2 This case is shown by a black circle in Figure 22. In this case, the vacancy concentration N V It is approximately N V = 7 × 10 12 ions / cm 3 The value in question is N. V Let's set it to 1.

[0208] The calculated oxygen contribution rate ξ1 and pore concentration N V 1 and oxygen chemical concentration C OX Therefore, using equation (2), the VOH defect concentration N VOH 1 (the first value of the hydrogen donor concentration) can be calculated. In other words, the first value N VOH 1 is the sum of the value obtained by multiplying the oxygen chemical concentration in the flat section 150 by the oxygen contribution rate and the pore concentration in the flat section 150. Oxygen chemical concentration C OX This can be done by measuring the oxygen chemical concentration in the semiconductor device 100. For example, the oxygen chemical concentration C OX is 2 x 10 17 atoms / cm 3 In this case, VOH defect concentration N VOH Number 1 will be as follows. N VOH 1 = 7 × 10 12 +1.2 × 10 -4×2×10 17 = 3.1 × 10 13 (atoms / cm 3 )

[0209] On the other hand, VOH defect concentration N VOH This can be measured from the characteristics of the semiconductor device 100. For example, the VOH defect concentration N VOH This is the final doping concentration N F And, bulk donor concentration N B0 The difference (N) F -N B0 ) can be measured from. Final doping concentration N F And, bulk donor concentration N B0 This can be measured from the semiconductor device 100. The measured VOH defect concentration N VOH to N VOH Let 2 be the second value of the hydrogen donor concentration. In other words, the second value N VOH 2 is the difference obtained by subtracting the bulk donor concentration from the donor concentration in the flat section 150. For example, the final doping concentration N F 7 x 10 13 (atoms / cm 3 ), bulk donor concentration N B0 is 2 x 10 12 (atoms / cm 3 In the case of VOH defect concentration N VOH Number 2 is as follows. N VOH 2 = 7 × 10 13 -2 × 10 12 = 6.8 × 10 13 (atoms / cm 3 ) Calculated N VOH 1 is the measured value of N VOH If it matches sufficiently to 2, the calculated oxygen contribution rate ξ1 and pore concentration N V It can be determined that 1 is generally correct. That is, the second value N of the hydrogen donor concentration. VOH The first value of hydrogen donor concentration for 2 N VOH Ratio N VOH 1 / N VOH 2 is 0.1 ≤ N VOH 1 / N VOH If 2 ≤ 10, then it can be considered to be a sufficient match. In the example above, NVOH 1 / N VOH 2 = 3.1 × 10 13 / 6.8×10 13 ≈0.46, and the calculated oxygen contribution rate ξ1 and vacancy concentration N V 1 is correct.

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

[0211] 0.2 ≤ N VOH 1 / N VOH When 2 ≤ 5, the calculated N VOH 1 is the measured value of N VOH It may be judged that it sufficiently matches 2. Also, 0.3 ≤ N VOH 1 / N VOH When 2 ≤ 3, the calculated N VOH 1 is the measured value of N VOH It may be judged that it sufficiently matches 2. 0.5≦N VOH 1 / N VOH When 2 ≤ 2, the calculated N VOH 1 is the measured value of N VOH It may be determined that it is sufficiently consistent with 2.

[0212] In equation (1), the contribution of oxygen to the formation of hydrogen donors (VOH defects) was considered. However, as will be discussed later, there may be cases where the contribution of carbon to the formation 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 rate η is defined as the ratio of the carbon chemical concentration that contributes to the hydrogen donor doping concentration to the total carbon chemical concentration. The carbon contribution rate η can be considered as the ratio of the carbon chemical concentration that contributed to the formation of hydrogen donors among the total carbon chemical concentrations in a given region (for example, at a depth position from the bottom or top surface). The carbon contribution rate η may also be defined as the ratio of the increase in hydrogen donor concentration to the increase in carbon chemical concentration when the carbon chemical concentration is increased. The carbon contribution rate may be a value between 0.01% and 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 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 This shows the distribution in the depth direction. The semiconductor device 100 in this example has a carbon chemical concentration C C and contributing carbon concentration N C Other than the configuration and manufacturing method, it is the same as that of the semiconductor device 100 described in Figures 1 to 22.

[0214] Carbon is often introduced during the manufacturing of ingots and is usually uniformly distributed within the semiconductor substrate 10. Carbon chemical concentration C C This may be uniform throughout the semiconductor substrate 10. In other examples, the carbon chemical concentration C C The carbon concentration C may increase monotonically from the lower surface 23 to the upper surface 21 of the semiconductor substrate 10, or it may decrease monotonically. Furthermore, carbon 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. C This 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. Outside the vicinity of the upper surface 21 and the lower surface 23, C As mentioned above, it may be uniform, and may be monotonically increasing or decreasing.

[0215] Carbon chemical concentration C in the flat section 150 C is 1 × 10 13 atoms / cm 3 The above is 1 x 10 16 atoms / cm 3 The following may be true: Carbon chemical concentration C C is 1 × 10 14 atoms / cm 3 The above is sufficient. Carbon chemical concentration C C is 5 x 10 15 atoms / cm 3 The following may be true: 2 × 10 15 atoms / cm 3 The following may also be used: Carbon chemical concentration C C This is the oxygen chemical concentration C OX Smaller is better. Carbon chemical concentration C C This is the oxygen chemical concentration C OX It may be 1 / 100 or less, and may also be 1 / 1000 or less. In this specification, the carbon chemical concentration C of the semiconductor substrate 10. C If this is specified, unless otherwise specified, the entire area between the second peak 141 and the first peak 133 satisfies the carbon chemical concentration requirement. The entire area between the second peak 141 and the bottom surface 23 may satisfy the carbon chemical concentration requirement, and the entire semiconductor substrate 10 may satisfy the carbon chemical concentration requirement.

[0216] Contributing carbon concentration N C This refers to the concentration of carbon that contributes to the formation of VOH defects. Carbon chemical concentration C C Experiments have confirmed that when the contributing carbon concentration N changes, the concentration of VOH defects may also change. In this specification, the contributing carbon concentration N C and carbon chemical concentration C C Let the ratio of this to be the carbon contribution rate η. That is, η = NC / C C The carbon contribution rate η is between 0 and 1. The unit of the carbon contribution rate η is dimensionless.

[0217] Contributing carbon concentration N C The distribution of carbon chemical concentration C C It may be similar in shape to the distribution of the contributing carbon concentration N. C The contributing carbon concentration N may be uniform in the depth direction of the semiconductor substrate 10 and may increase or decrease monotonically. C The distribution may have a peak at a predetermined depth.

[0218] Next, the range of the carbon contribution rate η in the semiconductor substrate 10 will be explained. VOH defect concentration N when considering the carbon contribution rate η VOH Let this be equation (2a). N VOH =N V +ξC OX +ηC C ...Equation (2a) VOH defect concentration N in equation (2a) VOH This is the VOH defect concentration N explained in equation (2). VOH carbon chemical concentration C C The product of this and the carbon contribution rate η is added. In other words, the hydrogen donor concentration that increases due to the presence of carbon is added to the VOH defect concentration N in equation (2). VOH This is added to the VOH defect concentration. Note that hydrogen donors generated by carbon contribution are not limited to VOH defects, but in equation (2a), the hydrogen donor concentration that increases due to the presence of carbon is expressed as the VOH defect concentration N VOH It is included in that.

[0219] Figure 24 shows the increase in donor concentration and the carbon chemical concentration C. C This figure shows the relationship. The method for measuring the increase in donor concentration in this example is the same as in the example in Figure 6. Also, the carbon chemical concentration C of the semiconductor substrate 10 in this example. C It is uniformly distributed in the depth direction.

[0220] In Figure 24, the depth position Z1 was set to 50 μm. In this example, the dose of hydrogen ions to depth position Z1 was 3 × 10⁻¹⁰ 12 ions / cm 2 , 1 x 10 13 ions / cm 2 , 3 x 10 13 ions / cm 2 The following three types are shown. The dose of hydrogen ions is 3 × 10 13 ions / cm 2 The sample is shown in plot 621, where the hydrogen ion dose is 1 × 10⁻⁶. 13 ions / cm 2 The sample is shown in plot 622, with a hydrogen ion dose of 3 × 10⁻⁶. 12 ions / cm 2 A sample of this is shown in plot 623. The size of each plot represents the oxygen chemical concentration C. OX This shows the size. As shown in Figure 24, the carbon chemical concentration C C In proportion to this, the increase in donor concentration is increasing substantially (almost) linearly.

[0221] In the example shown in Figure 24, the carbon chemical concentration C C An approximate formula is calculated that approximates the relationship between the amount of hydrogen ions and the increase in donor concentration with a straight line. In Figure 24, the hydrogen ion dose is 3 × 10⁻⁶. 13 ions / cm 2 This example is approximated by the straight line 611, and the dose of hydrogen ions is 1 × 10⁻⁶. 13 ions / cm 2 This example is approximated by the straight line 612, and the hydrogen ion dose is 3 × 10 12 ions / cm 2 This example is approximated by the line 613.

[0222] Each line is represented by equation (8a). N VOH = a × C C +b...Formula (8a) At this time, the slope a and intercept b of each line calculated by the least squares fitting method are as follows. Straight line 611: a=5.00851×10 -2b = 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 Figure 24, in VOH defect formation, the carbon chemical concentration C C and oxygen chemical concentration C OX There is not necessarily a strong correlation between the two. For example, carbon chemical concentration C C 6 x 10 14 atoms / cm 3 In the case of 8×10 14 atoms / cm 3 As in the case of carbon chemical concentration C C When comparing semiconductor substrates 10 of the same order, the oxygen chemical concentration C OX (Plot size) is 9 x 10 each. 15 atoms / cm 3 and 2.4 × 10 17 atoms / cm 3 This represents a difference of more than 10 times. On the other hand, carbon chemical concentration C C 2.5 × 10 15 atoms / cm 3 The semiconductor substrate 10 has a carbon chemical concentration C compared to the example above. C However, the oxygen chemical concentration C of the semiconductor substrate 10 is about three times higher. OX is 4 x 10 17 atoms / cm 3 Therefore, the oxygen chemical concentration C OX The difference is not that significant.

[0224] Figure 25 shows the increase in donor concentration and the oxygen chemical concentration C. OX This figure shows the relationship with the carbon chemical concentration C. In this example, each plot shown in Figure 24 represents the carbon chemical concentration C. C is small (1 × 10 15 atoms / cm 3 The following groups and carbon chemical concentration C CLarge (2 x 10 15 atoms / cm 3 The groups were divided as described above, and the increase in donor concentration and the oxygen chemical concentration C were measured. OX The relationship is approximated by a straight line.

[0225] In Figure 25, the hydrogen ion dose is 3 × 10⁻⁶. 13 ions / cm 2 Among the plots, the carbon chemical concentration C C The group with a large carbon chemical concentration C is shown by the line 631. C The small group is shown by the line 641. Also, the hydrogen ion dose is 1 × 10⁻⁶. 13 ions / cm 2 Among the plots, the carbon chemical concentration C C The group with a large carbon chemical concentration C is shown by the straight line 632. C The small group is shown by the line 642. Also, the hydrogen ion dose is 3 × 10 12 ions / cm 2 Among the plots, the carbon chemical concentration C C The group with a large carbon chemical concentration C is shown by the straight line 633. C The smaller group is indicated by the line 643.

[0226] When each line is represented 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 is the vacancy concentration N V These are essentially (almost) the same value. As with oxygen, as the carbon chemical concentration approaches 0, the vacancy concentration N V It is natural to assume that it converges to a constant value.

[0227] Carbon chemical concentration C C The slope of the line for the group with a large value is the carbon chemical concentration C C The slope of the line is greater than that of the smaller group. In other words, the carbon chemical concentration C C As the amount of oxygen concentration increases, the increase in donor concentration increases. Furthermore, as the dose of hydrogen ions increases, the increase in donor concentration increases. In other words, oxygen chemical concentration C OX VOH defect concentration N in relation to the increase in amount VOH The ratio of the increase (the slope of the line) is increasing.

[0228] The slope a of each line is the oxygen contribution ξ. The carbon chemical concentration C C Assume that the oxygen contribution rate ξ increases by α due to the increase in , where α ≥ 1. VOH defect concentration N VOH This is given by 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 rate η is equal to the oxygen chemical concentration C per unit carbon chemical concentration. OX / C CIt is expressed as the product of (α-1)ξ, which is the increase in ξ. In other words, the carbon contribution rate η is equal to the oxygen chemical concentration C OX And it depends on the oxygen contribution rate ξ.

[0230] As shown in Figure 25, the amount of hydrogen ions is the same, and the carbon chemical concentration C C As it increases, the oxygen chemical concentration C OX VOH defect concentration N in relation to the increase in amount VOH The ratio of the increase in the amount of the increase (slope ξ of the line) increases by α times, and the contributing carbon concentration N C =ηC C It increases. In other words, the carbon chemical concentration C C In addition to the increase in oxygen chemical concentration C OX The contributing carbon concentration N C The contributing carbon concentration increased, and the contributing carbon concentration increased. C VOH defect concentration N VOH This increases. This suggests that the donor increased by carbon contribution may be a different donor from the VOH defect. In this specification, the donor increased by carbon contribution may be referred to as the VOH-C defect.

[0231] Figure 26 shows the relationship between the hydrogen ion dose at depth Z1 and the carbon contribution rate η. Figure 26 shows the characteristics of three different semiconductor substrates 10 with depths Z1 of 50 μm, 100 μm, and 150 μm. In this example, similar to the oxygen contribution rate ξ in Figure 8, the hydrogen ion dose D at depth Z1 is shown. H For this, the carbon contribution rate η is approximated by a power function.

[0232] In Figure 26, the relationship between the hydrogen ion dose and the carbon contribution rate η when Z1 = 50 μm is approximated by curve 811, the relationship between the hydrogen ion dose and the carbon contribution rate η when Z1 = 100 μm is approximated by curve 812, and the relationship between the hydrogen ion dose and the carbon contribution rate η when Z1 = 150 μm is approximated by curve 813. Each curve 801 is expressed by equation (15). The 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 In the small group, the oxygen contribution rate ξ and the hydrogen ion dose D H This figure shows the relationship with carbon chemical concentration C. C The small group is defined as the group with a carbon chemical concentration C, as explained in Figure 25. C is 1 x 10 15 atoms / cm 3 The following groups apply. The oxygen contribution rate ξ is the value when there is no effect from carbon chemical concentration, therefore, the carbon chemical concentration C C The values ​​of the smaller group are used. In Figure 27, the characteristics of the semiconductor substrate 10 for three different depth positions Z1 of 50 μm, 100 μm, and 150 μm are shown by curves 821, 822, and 823, respectively. Each curve is an approximate curve obtained by using a power function for each plot, similar to the example in Figure 8.

[0234] Figure 28 shows the carbon chemical concentration C C In the small group, the vacancy concentration N V And, hydrogen ion dose D H This figure shows the relationship with vacancy concentration N. V This value is also for the case where there is no effect from carbon chemical concentration, therefore, carbon chemical concentration C C The values ​​of the smaller group are used. In Figure 28, the characteristics of the semiconductor substrate 10 for three different depth positions Z1 of 50 μm, 100 μm, and 150 μm are shown by curves 831, 832, and 833, respectively. Each curve is an approximate curve obtained by using a power function for each plot, similar to the example in Figure 8.

[0235] Each of the curves described in Figures 26 to 28 can be expressed as a power function. Therefore, 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, equation (1) to 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 This is the set value, and the bulk donor concentration N B0 This is known from measured values ​​or semiconductor wafer specifications. Oxygen chemical concentration C OX and carbon chemical concentration C C This is obtained by measuring each concentration in the semiconductor substrate 10 using methods such as SIMS. Parameters c, d, e, f, g, and h can be obtained experimentally in advance. Therefore, the variables in equation (14a) are the amount of charged particles injected (in this example, the dose of hydrogen ions D). H ) is the only constant, and the right-hand side of equation (14a) is a constant that does not change with respect to the injection amount.

[0237] By numerically solving equation (14a), the final doping concentration N can be determined. F The dose of charged particles to be injected into the semiconductor substrate 10 can be calculated based on the set value. The amount of charged particles to be injected D obtained from equation (14a) H This may have a range (error) that reflects the variability of the data values ​​in each fitting as explained in Figures 26 to 28. That is, the amount of charged particles injected D HIf the value obtained from equation (13a) or equation (14a) is within a range of, for example, ±50%, then it can be considered to be the value obtained from equation (13a) or equation (14a).

[0238] Figure 29 shows an example of a method for manufacturing a semiconductor device 100. The manufacturing method in this example differs from the example described in Figure 18 in the steps of the concentration measurement step S1602 and the injection volume calculation step S1604. The steps other than the concentration measurement step S1602 and the injection volume calculation step S1604 are the same as in the example in Figure 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 This differs from the concentration measurement step S1602 in Figure 18 in that it involves further measurement of the following. Other aspects are the same as the example described in relation to Figure 18. In the concentration measurement step S1602, each concentration may be measured by the FTIR method (infrared absorption spectroscopy).

[0240] In the injection amount calculation step S1604, the amount of charged particle beam to be injected into depth position Z1 is calculated based on the oxygen chemical concentration and carbon chemical concentration measured in S1602. As described above, the concentration of VOH defects formed can be controlled by the amount of charged particle beam injected. In the injection amount calculation step S1604, the injection amount may be calculated based on equation (13a) or equation (14a). In S1604, the substrate resistance value of the flat portion 150, as explained in Figure 4, is the final doping concentration N F The amount of charged particle beam injected may be calculated to match the set value.

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

[0242] The concentration of hydrogen donor to be generated should be N VOH1 From equation (2a), we get equation (16). The N shown in equation (16) VOH1 This 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 rate ξ and carbon contribution rate η can be obtained by measuring the semiconductor substrate 10. Furthermore, the concentration N of the hydrogen donor actually generated can be obtained. VOH2 This is the donor concentration N of the semiconductor substrate 10 before processing by the manufacturing method described above. B0 And the donor concentration N of the semiconductor substrate 10 after processing. F It can be obtained from the difference. The difference in donor concentration may be measured in the flat section 150. Donor concentration N of semiconductor substrate 10 B0 This can be obtained by SIMS or SR measurement. With SIMS, the donor concentration N of the semiconductor substrate 10 can also be obtained from the semiconductor substrate 10 after processing. B0 You can obtain this.

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

[0244] Figure 31 shows another example of the relationship between the oxygen contribution rate ξ and the depth position Z1. In Figure 31, the hydrogen ion dose is 3 × 10⁻⁶. 14 ions / cm 2 , 1 x 10 14 ions / cm 2 , 3 x 10 13 ions / cm 2 , 1 x 10 13 ions / cm 2 , 3 x 10 12 ions / cm 2 , or 1 × 10 12 ions / cm 2 The relationship between the oxygen contribution rate ξ and the depth position Z1 is shown for each case. In this example, the dependence of the oxygen contribution rate ξ on the depth position Z1 is smaller in the case with a higher hydrogen ion dose compared to the example shown in Figure 21. In other words, the slope of the straight line shown in Figure 31 is smaller. As one example, the depth position Z1 is 120 μm and the dose amount D H 5 x 10 12ions / cm 2 This case is shown by a black square in Figure 31. In this case, the oxygen contribution rate ξ is approximately ξ = 1.1 × 10⁻⁶. -4 This is the case. Let this value be ξ2. As another example, the depth position Z1 is 23 μm, and the dose amount D H 3 x 10 12 ions / cm 2 This case is shown in Figure 31 as a black diamond. In this case, the oxygen contribution rate ξ is approximately ξ = 1.0 × 10⁻⁶. -4 Therefore, let the value in question be ξ3.

[0245] Figure 32 shows the relationship between the carbon contribution rate η and the depth position Z1. Similar to the oxygen contribution rate ξ, the carbon contribution rate η decreases exponentially as the depth position Z1 increases. The carbon contribution rate η has a strong dependence on the depth position Z1. Also, the carbon contribution rate η increases with a high hydrogen ion dose. As one example, when the depth position Z1 is 120 μm and the dose is D H 5 x 10 12 ions / cm 2 This case is shown by a black square in Figure 32. In this case, the carbon contribution rate η is approximately η = 2.1 × 10⁻⁶ -4 This value is η2. Another example is when the depth position Z1 is 23 μm and the dose amount D H 3 x 10 12 ions / cm 2 This case is shown in Figure 32 as black diamond. In this case, the carbon contribution rate η is approximately η = 3.0 × 10 -3 This is the case. Let this value be η3.

[0246] As shown in Figures 30 and 32, the dependence of the carbon contribution rate η on the depth position Z1 is as follows: V The dependence on the depth position Z1 is of a similar strength. Therefore, it can be seen that carbon has a strong interaction with the vacancies. As explained in relation to equation (15) and Figure 25, the VOH defect concentration N VOH - Oxygen concentration C OXGiven that the increase in the slope of the characteristic is suggested to be due to a donor other than the VOH defect, it is presumed that the donor is formed of at least a vacancy (V), oxygen (O), hydrogen (H), and carbon (C). As mentioned above, this donor is referred to as a VOH-C defect. The VOH-C defect is an example of a hydrogen donor.

[0247] As shown in Figure 32, a large carbon contribution rate η occurs 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 (e.g., 100 μm), the carbon chemical concentration C is as explained in Figure 29. C The charged particle dose may be set based on the following. This predetermined value may be 70 μm or 50 μm. Also, the depth position Z1 is shallower than a predetermined value, and the carbon chemical concentration C C is a predetermined value (for example, 1 × 10) 13 atoms / cm 3 ) In the above cases, the carbon chemical concentration C C The charged particle dose may be set based on the following: The predetermined value is 5 × 10 13 atoms / cm 3 It is fine if it is 1 × 10 14 atoms / cm 3 That's fine.

[0248] (Example 1) Depth position Z1 is 120 μm, hydrogen ion dose D H 5 x 10 12 ions / cm 2 Let's consider an example. Also, the oxygen chemical concentration C OX is 4.0×10 17 atoms / cm 3 , carbon chemical concentration C C is 2.0 × 10 15 atoms / cm 3 Therefore, the final doping concentration N F is 7 x 10 13 / cm 3 Therefore, the bulk donor concentration N B0 is 2 x 10 12 / cm 3 That is the case.

[0249] As described above, from the relationship between the black squares and black diamonds in Figures 30, 31, and 32, and the vacancy concentration N shown in each figure, V Approximately 6 x 10 12 / cm 3 The oxygen contribution rate ξ is approximately 1.1 × 10⁻⁶. -4 The carbon contribution rate is approximately 2.1 × 10⁻⁶. -4 The relationships shown in Figures 30, 31, and 32 can be experimentally obtained in advance by measuring multiple semiconductor substrates 10.

[0250] From equation (16), N VOH1 It can be calculated as shown in the following formula. N VOH1 = 6.0 × 10 12 +1.1 × 10 -4 ×4.0×10 17 2.1 × 10 -4 ×2.0×10 15 = 5.04 × 10 13 / cm 3 Also, N VOH2 It can be calculated as shown in the following formula. N VOH2 =N F -N B0 = 7 × 10 13 -2 × 10 12 = 6.8 × 10 13 / cm 3 Therefore, N VOH1 / N VOH2 It can be calculated as shown in the following formula. N VOH1 / N VOH2 = 5.04 × 10 13 / 6.8×10 13 =0.74 As mentioned above, 0.1 ≤ N VOH1 / N VOH2 Since it is within the range of ≤10, in Example 1, N VOH1 and N VOH2 It can be determined that they are in sufficient agreement.

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

[0252] From the relationships shown in FIGS. 30, 31, and 32, the vacancy concentration N V is about 1.3×10 13 / cm 3 The oxygen contribution rate ξ is about 1.0×10 -4 The carbon contribution rate is about 3.0×10 -3 From Equation (16), N VOH1 is 3.0×10 13 / cm 3 Also, N VOH2 is 6.6×10 13 / cm 3 is as follows. Therefore, N VOH1 / N VOH2 can be calculated as follows. N VOH1 / N VOH2 =3.0×10 13 / 6.6×10 13 =0.45 Since it is within the range of 0.1≦N VOH1 / N VOH2 ≦10 in Example 2, it can be determined that N VOH1 and N[[ID=8l]] VOH2 are in good agreement.

[0253] N VOH1 / N VOH2When it is within that range, the oxygen chemical concentration C is as described in the manufacturing method in Figure 29. OX and carbon chemical concentration C C Based on the measurement results, it can be determined that the dose amount of charged particles has been set. Furthermore, N VOH1 / N VOH2 It may be 0.2 or greater, 0.3 or greater, or 0.5 or greater. VOH1 / N VOH2 It may be 5 or less, 3 or less, or 2 or less.

[0254] Furthermore, the charged particle dose considering the carbon contribution rate η can be calculated similarly even when the charged particles are not hydrogen ions. For example, if the charged particles are helium ions, the parameters c to h in equation (13b) are obtained in advance for the depth Z1 where the helium ions are implanted. He This is the helium ion dose (ions / cm³) relative to 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) This parameter may be obtained for multiple types of depth positions Z1.

[0255] Furthermore, the oxygen chemical concentration C of the semiconductor substrate 10 OX and carbon chemical concentration C C This is measured and obtained before the start of the manufacturing process. Then, the N to be generated is determined. VOH Helium ion dose D according to the set value He This is calculated from equation (13b).

[0256] Figures 33A, 33B, and 33C are graphs showing the dependence of vacancy concentration, oxygen contribution, and carbon contribution on the helium ion dose on the target electrical characteristics. Figures 33B and 33C show three examples of helium ion implantation depth Z1: Z1=a, Z1=b, and Z1=c. Equations (13), (13a), and (13b) are given by the N to be generated. VOH It can also be applied to other target characteristics. These target characteristics include, for example, the breakdown voltage (V) of the semiconductor device 100. 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, the semiconductor device may be manufactured using a flow similar to that shown in Figure 29. That is, the concentrations of oxygen and carbon are measured in advance in S1602, and the amount of helium ions to be implanted (dose) is calculated in S1604. Helium ions are then implanted in S1608 using this amount. Hydrogen ion implantation in S1610 may or may not be performed. In these cases, if the target electrical characteristic is F, then equation (13b) can be transformed as shown below. 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 obtained by multiplying the vacancy concentration Nv formed by helium ion implantation and heat treatment by the coefficient for converting to the electrical property F. The coefficient part of Cox in the second term is the oxygen contribution rate ξ´ to the target property F, and is an amount obtained by multiplying the above-mentioned oxygen contribution rate ξ by the coefficient for converting to the electrical property F. The coefficient part of Cc in the third term is the carbon contribution rate η´ to the target property F, and is an amount obtained by multiplying the above-mentioned carbon contribution rate η by the coefficient for converting to the electrical property F. Equation (15) should be prepared in advance by creating at least one of the graphs in FIGS. 33A, 33B, and 33C for two or more types of helium ion depths of 2 to 3 or more, and obtaining them. That is, the parameters c, d, e, f, g, and h can be experimentally obtained in advance. Therefore, the variable in Equation (15) is only the implantation amount of helium ions, and the right side of Equation (15) becomes a constant that does not change with respect to the implantation amount.

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

[0259] The electrical target property F can be transformed as follows for each property 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 will have different values ​​depending on the target characteristics. The units of parameters c to h may be consistent with the units of the target characteristics, the helium ion dose, the oxygen chemical concentration, and the carbon chemical concentration.

[0260] Figures 34A, 34B, and 34C are graphs showing the helium ion depth dependence of the reduced vacancy concentration Nv', the reduced oxygen contribution rate ξ', and the reduced carbon contribution rate η', respectively, in the target electrical characteristics. In each figure, the helium ion dose to depth position Z1 is D He 1, D He 2, D He 3, D He 4, D He 5, D He Six examples are shown. Using experimentally obtained parameters c, d, e, f, g, and h, the equivalent vacancy concentration Nv', equivalent oxygen contribution ξ', and equivalent carbon contribution η' can also be calculated in advance for the helium ion depth. This graph can be used to determine whether the semiconductor device was manufactured based on the flow shown in Figure 29.

[0261] The helium ion implantation depth Z1 is determined by measuring the atomic density distribution (chemical concentration distribution) of helium atoms in the semiconductor substrate 10, for example by SIMS, and defining the depth from the implantation surface as the peak value of the concentration distribution. The implantation surface may be the main surface on which the helium atom chemical concentration distribution extends deeply from the peak position. The helium ion dose may be the integral value obtained by integrating the measured helium atom chemical concentration distribution in the depth direction from the implantation surface. By interpolating the helium ion depth and dose calculated above in the graphs of Figures 34A, B, and C, the reduced vacancy concentration Nv', the reduced oxygen contribution rate ξ', and the reduced carbon contribution rate η' can be determined. The chemical concentrations of oxygen and carbon can be determined by SIMS. By substituting these values ​​into equation (15), the electrical characteristic value F1 is obtained.

[0262] On the other hand, the actual electrical characteristics F2 can be obtained by electrical measurement of the semiconductor device 100. If the ratio of the calculated value F1 to the measured value F2 is between 0.1 and 10, then the semiconductor device can be said to have been manufactured based on the flow chart in Figure 29. The first or third value mentioned above is an example of the calculated value F1, and the second value is an example of the measured value F2.

[0263] Figure 35 shows another example of a method for manufacturing the semiconductor device 100. This example differs from the example described in Figures 16 to 34C 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. The other steps are the same as those described in Figures 16 to 34C. Although the oxygen introduction step S1802 is not shown in Figure 35, this example may or may not include the oxygen introduction step S1802 described in Figure 18.

[0264] In the parameter acquisition stage S3502, parameters related to the semiconductor substrate 10 prepared in the substrate preparation stage S1600 are acquired. The concentration measurement stage S1602, as described in Figure 16, is an example of the parameter acquisition stage S3502. These parameters may include parameters such as oxygen chemical concentration or carbon chemical concentration, as described in Figures 16 to 34C. In the parameter acquisition stage 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 the parameter acquisition stage S3502, parameters that affect the hydrogen donor concentration of the semiconductor substrate 10, or parameters that affect the breakdown voltage of the semiconductor device 100, may be acquired. In the parameter acquisition stage S3502, at least one of the oxygen chemical concentration, carbon chemical concentration, oxygen contribution rate ξ, and carbon contribution rate η contained in the semiconductor substrate 10 may be acquired. These parameters can affect the hydrogen donor concentration and the breakdown voltage of the semiconductor device 100. Furthermore, in the parameter acquisition step S3502, at least one of the thickness of the semiconductor substrate 10 and the bulk donor concentration may be acquired. These parameters may affect the breakdown voltage of the semiconductor device 100.

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

[0266] For example, if the parameters obtained in the parameter acquisition step S3502 indicate a state in which hydrogen donors are less likely to be generated in the semiconductor substrate 10, then in the condition adjustment step S3503, the conditions of each step are adjusted to conditions that promote the generation of hydrogen donors in the semiconductor substrate 10. For example, if the oxygen chemical concentration of the semiconductor substrate 10 is low, VOH defects are less likely to be generated. On the other hand, increasing the dose of charged particle beams in the particle implantation step S1608, increasing the dose of hydrogen ions in the hydrogen ion implantation step S1610, increasing the heat treatment temperature in the heat treatment step S1612, and increasing the heat treatment time in the heat treatment step S1612 all promote the generation of VOH defects. The condition adjustment step S3503 may perform at least one of these processes. Similarly, if the oxygen chemical concentration of the semiconductor substrate 10 is high, VOH defects are more likely to be generated. On the other hand, lowering the dose of charged particle beams in the particle implantation stage S1608, lowering the dose of hydrogen ions in the hydrogen ion implantation stage S1610, lowering the heat treatment temperature in the heat treatment stage S1612, and shortening the heat treatment time in the heat treatment stage S1612 all suppress the generation of VOH defects. The condition adjustment stage S3503 may perform one of these treatments, or a combination of multiple treatments. Furthermore, a high carbon chemical concentration in the semiconductor substrate 10 tends to increase the likelihood of VOH defect generation, while a low carbon chemical concentration tends to decrease the likelihood of VOH defect generation. The oxygen contribution rate ξ and carbon contribution rate η are as described above. The condition adjustment stage S3503 may perform the same treatment as for the oxygen chemical concentration based on these parameters.

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

[0268] Furthermore, the bulk donor concentration N of the semiconductor substrate 10 B0 If the value is high, the doping concentration in the drift region 18 increases, and the breakdown voltage of the semiconductor device 100 decreases. Condition adjustment step S3503 is the bulk donor concentration N B0 The same processing as for the thickness of the semiconductor substrate 10 may be applied to this as well.

[0269] In the condition adjustment stage S3503, the conditions of each stage may be adjusted based on the difference or ratio between the acquired parameters and the preset reference values. The extent to which the conditions of each stage should be adjusted in relation to the difference or ratio may be determined in advance through experiments or other means. In this way, the characteristics of the semiconductor device 100 can be adjusted by adjusting the conditions of each stage based on the acquired parameters. Furthermore, the variation in the characteristics of the semiconductor device 100 can be reduced.

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

[0271] In the condition adjustment step S3503, at least one of the following is adjusted according to the oxygen chemical concentration: the injection conditions of the charged particle beam in the particle injection step S1608, the injection conditions of the hydrogen ions in the hydrogen injection step S1610, and the heat treatment conditions in the heat treatment step S1612. In the condition adjustment step S3503, the injection conditions of the charged particle beam may be adjusted as in the example shown in Figure 16.

[0272] When adjusting the hydrogen ion injection conditions in hydrogen injection step S1610, the hydrogen ion dose may be adjusted. By adjusting the hydrogen ion dose, the hydrogen concentration diffusing into the passage region 106 can be adjusted, thereby adjusting the hydrogen donor concentration generated in the passage region 106. In condition adjustment step S3503, if the oxygen chemical concentration is higher than the oxygen standard value, the hydrogen ion dose may be lowered to below the hydrogen standard value, and if the oxygen chemical concentration is lower than the oxygen standard value, the hydrogen ion dose may be higher than the hydrogen standard value. This reduces the effect of variations in oxygen chemical concentration and allows for precise adjustment of the doping concentration in the passage region 106.

[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. By adjusting the heat treatment temperature or the heat treatment time, hydrogen diffusion into the passage region 106 and the generation of hydrogen donors can be adjusted. In the condition adjustment step S3503, the heat treatment temperature may be lowered to a temperature reference value when the oxygen chemical concentration is higher than the oxygen reference value, and the heat treatment temperature may be raised to a temperature reference value when the oxygen chemical concentration is lower than the oxygen reference value. Similarly, the heat treatment time may be shortened to a time reference value when the oxygen chemical concentration is higher than the oxygen reference value, and the heat treatment time may be lengthened to a time reference value when the oxygen chemical concentration is lower than the oxygen reference value. This reduces the effect of variations in oxygen chemical concentration and allows for precise adjustment of the doping concentration in the passage region 106.

[0274] In addition, in the concentration measurement step S1602, the carbon chemical concentration of the semiconductor substrate 10 may be further measured, similar to the example in Figure 29. In the condition adjustment step S3503, the conditions of each step may be further adjusted based on the carbon chemical concentration. Higher carbon chemical concentrations tend to result in higher hydrogen donor concentrations. In the condition adjustment step S3503, if the carbon chemical concentration is higher than the carbon standard value, the conditions may be adjusted to suppress hydrogen donor formation, and if the carbon chemical concentration is lower than the carbon standard value, the conditions may be adjusted to promote hydrogen donor formation.

[0275] Furthermore, in the condition adjustment 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. Depending on the implantation depth Z1 of the charged particle beam, the length of the passage region 106 changes, 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 adjustment 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 adjustment step S3503, the hydrogen ion implantation conditions or 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 multiple semiconductor devices 100, the adjustment of the injection conditions in the particle injection stage S1608 and the adjustment of the injection conditions in the hydrogen injection stage S1610 may be performed for each semiconductor substrate 10 (each semiconductor device 100). Also, the adjustment of the heat treatment conditions in the heat treatment stage S1612 may be performed in common for multiple semiconductor substrates 10. The heat treatment of multiple semiconductor substrates 10 may be performed in parallel by placing the multiple semiconductor substrates 10 into a common heat treatment furnace. The injection of charged particles or hydrogen ions into each semiconductor substrate 10 may be performed for each semiconductor substrate 10. Through such processing, adjustments to multiple semiconductor substrates 10 can be performed efficiently.

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

[0278] In concentration acquisition step S3702, information on the impurity concentration in a predetermined area of ​​the semiconductor substrate 10 is acquired. In concentration acquisition step S3702, this information may be acquired by measuring the semiconductor substrate 10, or the design value or specification value of this information of the semiconductor substrate 10 may be acquired. The predetermined area of ​​the semiconductor substrate 10 is, for example, the central position in the depth direction of the semiconductor substrate 10, but is not limited thereto. 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 at the time of completion of the semiconductor device 100 may be acquired. As an example, in concentration acquisition step S3702, the oxygen chemical concentration, carbon chemical concentration, and bulk donor concentration N B0 Obtain at least one of the following. If oxygen chemical concentration or carbon chemical concentration is obtained, the processing in the condition adjustment step S3503 may be the same as in the example in Figure 36.

[0279] In the adjustment step S3503 of this example, the bulk donor concentration N B0 Based on this, at least one of the following is adjusted: the injection conditions for charged particle beams in the particle injection stage S1608, the injection conditions for hydrogen ions in the hydrogen injection stage S1610, and the heat treatment conditions in the heat treatment stage S1612.

[0280] The final doping concentration in the drift region 18 of the semiconductor device 100 after manufacturing is complete is the bulk donor concentration N B0 Therefore, it depends on the hydrogen donor concentration. B0 If there is variation in the bulk donor concentration N, then there will also be variation in the final doping concentration. In the condition adjustment stage S3503, the bulk donor concentration N B0 Then, the conditions at each stage are adjusted to offset the deviation from the predetermined bulk reference value. In other words, in the condition adjustment stage S3503, the bulk donor concentration N B0 If the value is lower 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 the value is greater than the bulk reference value, the conditions at each stage are adjusted to reduce the amount of hydrogen donor produced. The method for adjusting the amount of hydrogen donor produced at each stage is the same as in the examples in Figures 35 and 36. This reduces the variability in the final doping concentration.

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

[0282] Furthermore, in the condition adjustment 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. This allows for more precise adjustment of the amount of hydrogen donor formation.

[0283] Figure 38 shows the relationship between the bulk donor concentration and the injection depth Z1 of charged particles. In this example, the bulk donor concentration obtained in the concentration acquisition step S3702 is N B0 , the bulk reference value is N Br , N B0 and N Br Let γ be the ratio to N. B0 =γ·N Br Furthermore, the injection depth of charged particles before condition adjustment is Z1 r The injection depth of the charged particles after adjusting the conditions is Z1, Z1 and Z1 r Let ε be the ratio of Z1 to Z1. That is, Z1 = ε·Z1 r The injection depth Z represents the distance from the lower surface 23 of the semiconductor substrate 10 to the injection position.

[0284] As shown in Figure 38, in the condition adjustment step S3503, the injection depth Z1 of charged particles is adjusted so that as γ increases, ε decreases. As γ increases, the bulk donor concentration N shown in Figure 13 increases. B0This increases the doping concentration in the drift region 18, which may reduce the breakdown voltage of the semiconductor substrate 10. To counteract this, by reducing ε and bringing it closer to the injection depth Z1 and the bottom surface 23, the length over which the high-concentration flat portion 150 is formed can be shortened, thereby reducing the integral value of the doping concentration in the drift region 18. This suppresses the breakdown voltage of the semiconductor substrate 10.

[0285] Figure 39 shows another example of a method for manufacturing a semiconductor device 100. In this example, the manufacturing method includes a substrate thickness measurement step S3902 as the parameter acquisition step S3502 in Figure 35. In addition, a grinding step S3901 is included before the substrate thickness measurement step S3902, in which the semiconductor substrate 10 is ground to adjust its thickness. The other steps are the same as in the example in Figures 35, 36, or 37.

[0286] In the grinding step S3901, the thickness of the semiconductor substrate 10 may be adjusted according to the withstand voltage that the semiconductor device 100 should have. The grinding step S3901 may be performed before the particle implantation step S1608 and 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 area of ​​the semiconductor substrate 10 is measured. In the substrate thickness measurement step S3902, the average value of thicknesses measured at multiple locations may be used. In the substrate thickness measurement step S3902, the thickness at the active portion 160 may be measured, or the thickness at the edge termination structure portion 90 may be measured.

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

[0289] If there is variation in the thickness of the semiconductor substrate 10, there may be variation in the breakdown voltage of the semiconductor device 100. In the condition adjustment step S3503, the conditions of each step are adjusted to offset the discrepancy between the thickness of the semiconductor substrate 10 and a predetermined thickness reference value. In other words, in the condition adjustment step S3503, if the thickness of the semiconductor substrate 10 is less than the thickness reference value, the conditions of each step are adjusted to increase the breakdown voltage, and if the thickness of the semiconductor substrate 10 is greater than the thickness reference value, the conditions of 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 the breakdown voltage of the semiconductor device 100 can be decreased by increasing this integral value. The integral value of the doping concentration can be adjusted by the amount of hydrogen donor formation in the drift region 18. The amount of hydrogen donor formation can be adjusted by the conditions of each step as described above.

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

[0291] Figure 40 shows an example of an equipotential surface 308 in the edge termination structure 90. The structure of the edge termination structure 90 is the same as in the example in Figure 14. Below the second peak 141, on the lower surface 23 side, a region with a higher concentration than the bulk donor concentration is formed. Therefore, the curvature of the equipotential surface 308 changes in the vicinity of the second peak 141. As a result, the equipotential surface 308 extends outward towards the outer periphery of the semiconductor device 100 in the vicinity of the upper surface 21 of the semiconductor substrate 10. Therefore, the extent to which the equipotential surface 308 extends outward towards the outer periphery of the semiconductor device 100 depends on the distance Zb between the upper surface 21 of the semiconductor substrate 10 and the second peak 141.

[0292] In the condition adjustment step S3503, the injection depth Z1 of charged particles into the edge termination structure 90 may be adjusted based on the thickness of the semiconductor substrate 10 at the edge termination structure 90. This allows for precise control of the distance Zb. This prevents the depletion layer in the edge termination structure 90 from spreading too much laterally. As a result, the length of the edge termination structure 90 in the outer peripheral direction can be shortened, and the area of ​​the upper surface 21 of the semiconductor device 100 can be reduced.

[0293] Furthermore, in the condition adjustment step S3503, the injection conditions for the edge termination structure 90 may be adjusted. This allows for precise adjustment of the doping concentration below the second peak 141, thereby further controlling the spread of the 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 or improvements can be made to the above embodiments. It will be clear from the claims that such modified or improved forms may also be included in the technical scope of the present invention.

[0295] It should be noted that the execution order of operations, procedures, steps, and stages in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not explicitly stated as "before," "prior to," etc., and that these can be performed in any order unless the output of a previous process is used in a later process. Even if the operation flow in the claims, specifications, and drawings is described using phrases such as "first," "next," etc. for convenience, this does not mean that it is mandatory to perform the operations in that order. [Explanation of symbols]

[0296] 10...Semiconductor substrate, 11...Well region, 12...Emitter region, 14...Base region, 15...Contact region, 16...Storage region, 18...Drift region, 20...Buffer region, 21...Top surface, 22...Collector region, 23...Bottom surface, 24...Collector electrode, 25...Peak, 26...Peak, 29...Linear portion, 30...Dummy trench portion, 31...Tip portion, 32...Dummy insulating film, 34...Dummy conductive portion, 38...Layer Inter-insulating film, 39...Straight section, 40...Gate trench section, 41...Tip section, 42...Gate insulating film, 44...Gate conductive section, 52...Emitter electrode, 54...Contact hole, 60, 61...Mesa section, 70...Transistor section, 80...Diode section, 81...Extended region, 82...Cathode region, 90...Edge termination structure section, 92...Guard ring, 94...Field plate, 100...Semiconductor device, 106...Passage region, 11 1...Second donor peak, 121...First donor peak, 130...Outer gate wiring, 131...Active side gate wiring, 133...First peak, 141...Second peak, 142...Lower tail, 143...Upper tail, 150...Flat section, 151...Second contributing concentration peak, 160...Active section, 161...First contributing concentration peak, 162...Edge, 164...Gate pad, 171...Vacancy peak, 174...Channel stopper, 180... • Region, 181...Second VOH peak, 191...First VOH peak, 194...Hydrogen concentration peak, 214...Linear approximate distribution, 216...Band-shaped region, 308...Equipotential surfaces, 601, 602, 603, 611, 612, 613, 631, 632, 633, 641, 642, 643...Linear lines, 621, 622, 623...Plots, 801, 802, 811, 812, 813, 821, 822, 823, 831, 832, 833, 901, 902...Curves

Claims

1. A semiconductor substrate having an upper surface and a lower surface, containing oxygen and carbon, and having a bulk donor, The first peak of hydrogen chemical concentration is located on the lower surface side of the semiconductor substrate, A second peak of the hydrogen chemical concentration, located on the upper surface side of the semiconductor substrate, is located above the first peak. A flat portion is located between the first peak and the second peak, containing a hydrogen donor, and having a substantially flat donor concentration distribution in the depth direction of the semiconductor substrate. Equipped with, In the flat portion, the oxygen contribution rate, which indicates the proportion of the oxygen chemical concentration that contributes to the generation of the hydrogen donor out of the total oxygen chemical concentration, is 1 × 10⁻⁵ or more and 7 × 10⁻⁴ or less. In the flat portion, the oxygen chemical concentration that contributes to generating the hydrogen donor is lower than the hydrogen chemical concentration. The hydrogen donor concentration in the flat portion is 2 × 10¹² / cm³ or more and 5 × 10¹⁴ / cm³ or less. Semiconductor equipment.

2. The flat portion further comprises a bulk doping region having a bulk donor concentration, which is located on the upper surface side of the flat portion. The semiconductor device according to claim 1.

3. A semiconductor substrate having an upper surface and a lower surface, containing oxygen and carbon, and having a bulk donor, The first peak of hydrogen chemical concentration is located on the lower surface side of the semiconductor substrate, A second peak of the hydrogen chemical concentration, located on the upper surface side of the semiconductor substrate, is located above the first peak. A flat portion is located between the first peak and the second peak, containing a hydrogen donor, and the donor concentration distribution in the depth direction of the semiconductor substrate is substantially flat. Equipped with, In the flat portion, The sum of the value obtained by multiplying the oxygen chemical concentration in the flat portion by the oxygen chemical concentration, which represents the proportion of the oxygen chemical concentration that contributes to the generation of the hydrogen donor, and the value of the pore concentration in the flat portion, is defined as the first value of the hydrogen donor concentration. The difference obtained by subtracting the bulk donor concentration from the donor concentration in the flat area is taken as the second value of the hydrogen donor concentration. The ratio of the first value to the second value is 0.1 or greater and 10 or less. Semiconductor equipment.

4. The flat portion further comprises a bulk doping region disposed on the upper surface side and having the bulk donor concentration, The semiconductor device according to claim 3.

5. A semiconductor substrate having an upper surface and a lower surface, containing oxygen and carbon, and having a bulk donor, The first peak of hydrogen chemical concentration is located on the lower surface side of the semiconductor substrate, A second peak of the hydrogen chemical concentration, located on the upper surface side of the semiconductor substrate, is located above the first peak. A flat portion is located between the first peak and the second peak, containing a hydrogen donor, and the donor concentration distribution in the depth direction of the semiconductor substrate is substantially flat. A bulk doping region having a bulk donor concentration is located on the upper side of the flat portion, Equipped with, In the flat portion, The difference obtained by subtracting the bulk donor concentration from the donor concentration in the flat area is taken as the second value of the hydrogen donor concentration. The contributing oxygen concentration is obtained by multiplying the oxygen chemical concentration in the flat portion by the oxygen chemical concentration, which is the proportion of the oxygen chemical concentration of the oxygen that contributes to the generation of the hydrogen donor, and the contributing oxygen concentration is obtained by multiplying the oxygen chemical concentration in the flat portion by the oxygen contribution rate. The carbon contribution rate, which is the proportion of the carbon chemical concentration that contributes to the generation of the hydrogen donor out of the total carbon chemical concentration, is multiplied by the carbon chemical concentration in the flat portion to obtain the contributing carbon concentration, The sum of the pore concentration in the flat portion and the hydrogen donor concentration is taken as the third value of the hydrogen donor concentration. The ratio of the third value to the second value is 0.1 or greater and 10 or less. Semiconductor equipment.

6. The contributing oxygen concentration is 0.1 times or less the hydrogen chemical concentration. The semiconductor device according to claim 5.

7. The semi-logarithmic slope η ( / cm) of the doping concentration in the flat portion is 0 or more and 50 or less. The semiconductor device according to any one of claims 1 to 6.

8. The oxygen contribution rate is 1 × 10⁻⁵ or more and 7 × 10⁻⁴ or less. The semiconductor device according to any one of claims 3 to 6.

9. The pore density of the flat portion is 1 × 10¹² / cm³ or more and 1 × 10¹³ / cm³ or less. The semiconductor device according to any one of claims 3 to 6.

10. In the flat portion, the ratio of the minimum value of the oxygen chemical concentration to the maximum value of the oxygen chemical concentration is 0.3 or more and 0.9 or less. The semiconductor device according to any one of claims 1 to 6.

11. The carbon contribution rate is 0.01% or more and 10% or less. The semiconductor device according to claim 5 or 6.

12. The bulk doping region is part of the drift region, The system further comprises a buffer region having a peak with a higher donor concentration than the aforementioned drift region. The flat portion is located between the bulk doping region and the buffer region. The semiconductor device according to any one of claims 2, 4, 5, and 6.

13. The hydrogen donor comprises an electron-supplying hydrogen at the location of a specific lattice defect formed in the hydrogen ion passage region. The semiconductor device according to any one of claims 1 to 6.

14. The specific lattice defect is one or more of a single-atom vacancy (V), a double-atom vacancy (VV), an interstitial atom, or a dislocation. The semiconductor device according to claim 13.

15. A particle implantation step of injecting a charged particle beam into a semiconductor substrate having an upper surface and a lower surface, A hydrogen ion implantation step in which hydrogen ions are implanted on the lower surface side of the semiconductor substrate, relative to the charged particle beam, The process includes a heat treatment step of heat-treating the semiconductor substrate, The semiconductor substrate that has undergone the heat treatment has specific lattice defects formed in the region through which the charged particle beam passes, and the hydrogen ions located at the lattice defects function as hydrogen donors capable of supplying electrons. A method for manufacturing a semiconductor device.

16. The charged particle beam is hydrogen ions. The method for manufacturing a semiconductor device according to claim 15.

17. The specific lattice defect is one or more of a single-atom vacancy (V), a double-atom vacancy (VV), an interstitial atom, or a dislocation. A method for manufacturing a semiconductor device according to claim 15 or 16.

18. Determining the hydrogen ion implantation conditions in the hydrogen ion implantation step based on the implantation conditions of the charged particle beam that forms the lattice defects. A method for manufacturing a semiconductor device according to any one of claims 15 to 17.

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