SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING

Abstract

Semiconductor device (100) comprising: a semiconductor substrate (10) having an upper surface (21) and a lower surface (23), wherein in a depth direction from the lower surface (23) to the upper surface (21) of the semiconductor substrate (10), a hydrogen concentration distribution has a hydrogen concentration peak (131), a helium concentration distribution has a helium concentration peak (141), and a donor concentration distribution has a first donor concentration peak (111) and a second donor concentration peak (121), the peak of the hydrogen concentration (131) and the first peak of the donor concentration (111) lie at a first depth, and the peak of the helium concentration (141) and the second peak of the donor concentration (121) lie at a second depth which is deeper than the first depth with respect to the lower surface (23), each concentration peak has a rising edge in which a concentration value increases from the lower surface (23) to the upper surface (21), and a value obtained by normalizing a gradient of the rising edge of the second peak of the donor concentration (121) with a gradient of the rising edge of the peak of the helium concentration (141) is smaller than a value obtained by normalizing a gradient of the rising edge of the first peak of the donor concentration (111) with a gradient of the rising edge of the peak of the hydrogen concentration (131).

Description

TECHNICAL BACKGROUND1. TECHNICAL FIELD

[0001] The present invention relates to a semiconductor device and a method for manufacturing the same. 2. STATE OF THE ART

[0002] In the prior art, it is known that hydrogen is implanted into a semiconductor substrate, which is diffused so that the hydrogen combines with crystal defects existing in a diffusion region to serve as a donor (see, for example, Patent Documents 1 to 3). Patent Document 1: Japanese translation of PCT International Application No. WO 2016-204 227 A1 Patent document 2: DE 11 2015 000 206 T5 Patent document 3: DE 112019 001 741 T5

[0003] It is preferred that a range of a donor region and a donor concentration formed by combining hydrogen with a crystal defect can be adjusted with high accuracy. GENERAL REVELATION

[0004] According to a first aspect of the present invention, there is provided a semiconductor device according to claim 1.

[0005] Each concentration peak can have a falling slope, where the concentration value decreases from the lower surface to the upper surface. For the helium concentration peak, the slope of the rising slope can be smaller than the slope of the falling slope. For the second donor concentration peak, the slope of the rising slope can be smaller than the slope of the falling slope.

[0006] The donor concentration distribution may include a flat region between the first depth and the second depth where the donor concentration is approximately constant. The length of the flat region in the depth direction may be 10% or more of the thickness of the semiconductor substrate in the depth direction.

[0007] The donor concentration distribution may include a flat region between the first depth and the second depth, where the donor concentration is approximately constant. The length of the flat region in the depth direction may be 10 µm or more.

[0008] A minimum value of the donor concentration in the shallow region may be higher than a donor concentration of the semiconductor substrate.

[0009] A minimum value of the donor concentration between the first depth and the second depth may be higher than the donor concentration of the semiconductor substrate.

[0010] A value of the concentration of the peak of the helium concentration may be smaller than a value of the concentration of the peak of the hydrogen concentration.

[0011] The semiconductor device may include an N-type drift region in the semiconductor substrate. The semiconductor device may include an emitter region in contact with the top surface of the semiconductor substrate having a higher donor concentration than a donor concentration of the drift region. The semiconductor device may include a P-type base region between the emitter region and the drift region. The semiconductor device may include a P-type collector region in contact with the bottom surface of the semiconductor substrate. The semiconductor device may include an N-type buffer region between the collector region and the drift region having one or more peaks of donor concentration whose donor concentration is higher than the donor concentration of the drift region. The first peak of the donor concentration may be the peak of the donor concentration of the buffer region.

[0012] The semiconductor device may have an accumulation region between the base region and the drift region with one or more donor concentration peaks whose donor concentration is higher than the donor concentration of the drift region. The second donor concentration peak may be the donor concentration peak of the accumulation region.

[0013] The accumulation region may have, in addition to the second peak of donor concentration, the peak of donor concentration due to a donor other than hydrogen.

[0014] The second peak of donor concentration may be located between the buffer region and the accumulation region.

[0015] The semiconductor device may include a gate trench portion disposed on the upper surface of the semiconductor substrate. The second peak of the donor concentration may be located between a lower portion of the gate trench portion and the upper surface of the semiconductor substrate.

[0016] The semiconductor device may include an active portion disposed in the semiconductor substrate. The semiconductor device may include an edge termination structure portion surrounding the active portion in a plan view of the semiconductor substrate. The semiconductor substrate may include a via region through which helium implanted at a peak helium concentration position has passed. The via region in the edge termination structure portion may be shorter in the depth direction than the via region in the active portion, or the via region may not be disposed in the edge termination structure portion.

[0017] The semiconductor device may include a transistor portion and a diode portion disposed in the semiconductor substrate. The through region in the diode portion may be shorter in the depth direction than the through region in the transistor portion, or the through region may not be disposed in the diode portion.

[0018] The through region in the transistor section may be shorter in the depth direction than the through region in the diode section, or the through region may not be arranged in the transistor section.

[0019] The first depth may be in a range of 5 µm or less from the bottom surface in the depth direction.

[0020] A donor concentration at the peak of the hydrogen concentration can be 1×10 15 / cm 3 or higher and 1×10 17 / cm 3 or lower.

[0021] According to a second aspect of the present invention, there is provided a semiconductor device according to claim 19.

[0022] The semiconductor substrate may have an impurity concentration peak between the bottom surface and the hydrogen concentration peak, and an impurity of the impurity concentration peak may be argon or fluorine.

[0023] According to a third aspect of the present invention, a method according to claim 21 for manufacturing the semiconductor device according to the first aspect is provided. Further aspects of the invention are the subject of the dependent claims, the drawings, and the description of exemplary embodiments.

[0024] In the first implantation step, hydrogen may be implanted according to a diffusion coefficient of hydrogen in the semiconductor substrate, and with a dosage greater than or equal to a minimum dosage determined by the second depth.

[0025] The semiconductor substrate may be a silicon substrate, and when the second depth from the bottom surface is set to x (µm), a dosage Q (ions / cm 2 ) of hydrogen in the first implantation step Q≥1.6×1013×e0.06x.

[0026] In the first implantation step, hydrogen can be implanted at the first depth by plasma doping.

[0027] The bottom surface of the semiconductor substrate can be ground after plasma doping.

[0028] The lower surface of the semiconductor substrate can be laser annealed after plasma doping.

[0029] The summary does not necessarily describe all necessary features of the embodiments of the present invention. The present invention may also be a subcombination of the features described above. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view showing an exemplary semiconductor device 100. Fig. Fig. 2 shows a distribution of a hydrogen concentration, a distribution of a helium concentration, a distribution of a donor concentration and a distribution of a vacancy concentration 175 in a depth direction at a position indicated by a line AA in Fig. 1 is shown. Fig. 3A is a diagram illustrating a relationship between a peak of hydrogen concentration 131 and a first peak of donor concentration 111. Fig. Figure 3B is a diagram illustrating a relationship between a peak of helium concentration 141 and a second peak of donor concentration 121. Fig. Figure 3C is a diagram illustrating a slope of a rising edge 142. Fig. 4A is a diagram illustrating another definition of normalization of a rising edge slope 112. Fig. 4B is a diagram illustrating another definition of normalization of a rising edge slope 122. Fig. Figure 5 is a diagram illustrating a flat area 150. Fig. 6 is a diagram showing an example of a semiconductor device 100. Fig. 7 is a diagram showing an example of a distribution of a carrier concentration in the depth direction at a position of the line BB in Fig. 6 illustrated. Fig. 8 is a diagram showing another example of the semiconductor device 100. Fig. 9 is a diagram showing an example of a distribution of a carrier concentration in the depth direction at a position of the line CC in Fig. 8 illustrated. Fig. Figure 10 shows the distribution of hydrogen concentration, the distribution of helium concentration and a distribution of a vacancy concentration in the depth direction at the position indicated by the line AA in Fig. 1 is shown. Fig. 11 is a diagram showing an exemplary arrangement of all elements on an upper surface 21 of a semiconductor substrate 10. Fig. 12 is a view showing an exemplary section along cc' in Fig. 11 shows. Fig. 13 is a diagram showing another exemplary arrangement of a passage area 106. Fig. 14 is a diagram showing another exemplary arrangement of the passage area 106. Fig. 15 is a diagram showing another exemplary arrangement of the passage area 106. Fig. 16A is a diagram showing another exemplary arrangement of the passage area 106. Fig. 16B is a diagram showing another exemplary arrangement of the passage region 106. Fig. 17A is a diagram showing another exemplary arrangement of the passage area 106. Fig. 17B is a diagram showing another exemplary arrangement of the passage area 106. Fig. 17C is a diagram illustrating a minimum film thickness M of a photoresist film 200 that prevents helium ions from penetrating into the semiconductor substrate 10. Fig. 18A is a diagram showing another exemplary arrangement of the passage region 106. Fig. 18B is a diagram showing another exemplary arrangement of the passage region 106. Fig. 19 is a diagram showing steps for forming a via region 106 in a method of manufacturing the semiconductor device 100. Fig. 20 is a diagram illustrating an example of a distribution of a carrier concentration in the semiconductor substrate 10 after diffusion step S1904. Fig. Figure 21 is a graph showing a relationship between a diffusion coefficient D of hydrogen and a first dosage Q. Fig. Figure 22 is a graph showing a relationship between a diffusion coefficient D of hydrogen and an annealing temperature T. Fig. Figure 23 is a graph showing a relationship between a diffusion depth of hydrogen and a first dosage. Fig. Figure 24 is a diagram showing a relationship between a diffusion coefficient D of hydrogen and a diffusion depth x. Fig. Figure 25 is a graph showing a straight line indicating a minimum dosage for each annealing temperature. Fig. Figure 26 is a graph showing a relationship between a second dosage and a minimum dosage of the first dosage. Fig. Figure 27 is a diagram illustrating an example of a first depth Z1. Fig. 28 shows other examples of the donor concentration distribution, the chemical hydrogen concentration distribution, and the chemical helium concentration distribution in the depth direction of the semiconductor substrate 10. Fig. Figure 29 is a graph showing examples of the distribution of chemical hydrogen concentration and a distribution of chemical argon concentration near the peak of hydrogen concentration 131. Fig. 30 is a diagram showing another example of the semiconductor device 100. Fig. 31 shows examples of a carrier concentration distribution, a hydrogen chemical concentration distribution and a boron chemical concentration distribution along a line DD in Fig. 30. Fig. Figure 32 shows examples of a carrier concentration distribution, a chemical hydrogen concentration distribution and a chemical phosphorus concentration distribution along a line EE in Fig. 30. Fig. 33 is a diagram showing some steps of the method for manufacturing the semiconductor device 100. Fig. 34 is a diagram showing some steps of the method for manufacturing the semiconductor device 100. Fig. 35 shows an example of a step of implanting hydrogen ions at the first depth Z1 and implanting helium ions at a second depth Z2 in a step of forming a structure on the lower surface side. Fig. 36 shows another example of the step of implanting hydrogen ions at the first depth Z1 and implanting helium ions at the second depth Z2 in the step of forming the structure on the lower surface side. DESCRIPTION OF THE EMBODIMENTS

[0030] The present invention is described below using exemplary embodiments of the invention, whereby the following exemplary embodiments do not limit the invention disclosed in the claims. Furthermore, not all combinations of features described in the exemplary embodiments are essential for achieving the object of the invention.

[0031] In this specification, one side in a direction parallel to a depth direction of a semiconductor substrate is referred to as the "upper" side, and the other side is referred to as the "lower" side. One surface of two main surfaces of a substrate, layer, or other member is referred to as an upper surface, and the other surface is referred to as a lower surface. The "lower" direction and "upper" direction are not limited to a direction of gravity or a direction in which the semiconductor device is mounted.

[0032] In this specification, technical matters may be described using orthogonal coordinate axes X, Y, and Z. The orthogonal coordinate axes merely indicate relative positions of components and are not restrictive to a specific direction. For example, the Z axis is not intended to exclusively indicate a height direction relative to the ground. A +Z direction and a -Z direction are opposite directions. In a case where the Z axis direction is described without a positive or negative sign, reference is made to a direction parallel to the +Z axis and the -Z axis.

[0033] When something is described as "same" or "equal," it may contain a defect due to a manufacturing variance. The error, for example, can be up to 10%.

[0034] A chemical concentration in the present description refers to a concentration of an impurity independent of an activation state.

[0035] The chemical concentration can be measured, for example, by secondary ion mass spectrometry (SIMS). In the present description, a concentration difference between a donor and an acceptor can refer to a majority concentration between the donor or the acceptor. The concentration difference can be measured by capacitance-voltage (CV) profiling. Furthermore, a carrier concentration measured by spreading resistance profiling (SR profiling) can be determined as the concentration of the donor or the acceptor. Furthermore, if a concentration distribution of the donor or the acceptor has a peak in a region, the value of the peak can be determined as the concentration of the donor or the acceptor.If the concentration of the donor or acceptor is approximately uniform in an area where the donor or acceptor or the like is present, an average value of the concentration of the donor or acceptor in that area can be determined as the concentration of the donor or acceptor. In this specification, the SI base unit system is used unless otherwise stated. Although a unit of length can be specified in cm, various calculations can be performed after conversion to meters (m).

[0036] Fig. 1 is a sectional view showing an exemplary semiconductor device 100. The semiconductor device 100 includes a semiconductor substrate 10. The semiconductor substrate 10 is a substrate formed of a semiconductor material. For example, the semiconductor substrate 10 is a silicon substrate. The semiconductor substrate 10 has a donor concentration determined by impurities or the like implanted during manufacturing. A conductivity type of the semiconductor substrate 10 of the present example is an N-type. In the present specification, the donor concentration in the semiconductor substrate 10 may be referred to as a substrate concentration.

[0037] The semiconductor substrate 10 has an upper surface 21 and a lower surface 23. The upper surface 21 and the lower surface 23 are two main surfaces of the semiconductor substrate 10. In the present description, orthogonal axes in a plane parallel to the upper surface 21 and the lower surface 23 are defined as the X-axis and the Y-axis, and an axis perpendicular to the upper surface 21 and the lower surface 23 is defined as the Z-axis. Although semiconductor elements such as an IGBT or a FWD are formed in the semiconductor substrate 10, these devices are Fig. 1 not shown.

[0038] Hydrogen ions and helium ions are implanted into the semiconductor substrate 10 from a lower surface 23. The hydrogen ion in the present example is a proton. The hydrogen ions are implanted to a depth Z1 in the depth direction (Z-axis direction) of the semiconductor substrate 10. The helium ions are implanted to a depth Z2. Of the two depths in the present example, the first depth Z1 is closer to the lower surface 23, and the other, which is deeper than the first depth Z1 from the perspective of the lower surface 23, is the second depth Z2. Fig. 1, the implanted hydrogen and helium are schematically shown by × marks; however, hydrogen and helium are also distributed around the implantation positions Z1, Z2.

[0039] The first depth Z1 may be from the bottom surface 23 side in the depth direction of the semiconductor substrate 10. For example, the first depth Z1 with respect to the bottom surface 23 may be in a range of half or less of the thickness of the semiconductor substrate 10, and may be in a range of 1 / 4 or less of the thickness of the semiconductor substrate 10. The second depth Z2 may be from the top surface 21 side in the depth direction of the semiconductor substrate 10. For example, the second depth Z2 with respect to the top surface 21 may be in a range of half or less of the thickness of the semiconductor substrate 10, and may be in a range of 1 / 4 or less of the thickness of the semiconductor substrate 10. The first depth Z1 and the second depth Z2 are not limited to these ranges.

[0040] The helium ions implanted at the second depth Z2 pass through a passage region 106 from the bottom surface 23 to the second depth Z2. In the passage region 106, a void of a vacancy (V), a divacancy (VV), or the like is created by the passage of the helium ion. In the present description, the vacancy includes the divacancy unless otherwise stated. A vacancy density in the passage region 106 can be adjusted by a dosage of the helium ion implanted at the second depth Z2, or the like.

[0041] By implanting the hydrogen ions at the first depth Z1 and subsequently heat-treating the semiconductor substrate 10, the hydrogen implanted at the first depth Z1 is diffused in the through-hole region 106. A VOH defect is formed by bonds of a vacancy (V) and oxygen (O) with hydrogen (H) present in the through-hole region 106.

[0042] The VOH defect acts as a donor that provides an electron. This allows a donor concentration of the via region 106 to be higher than a donor concentration Db (or a specific resistance or a base doping concentration) during the fabrication of a semiconductor ingot that is a base of the semiconductor substrate 10. Accordingly, the donor concentration of the semiconductor substrate 10 can be easily adjusted depending on the properties that an element formed in the semiconductor substrate 10 should have. Note that, unless otherwise stated in the present specification, the VOH defect with a distribution similar to a chemical hydrogen concentration distribution and the VOH defect with a distribution similar to a vacancy distribution in the via region 106 are both referred to as a hydrogen donor or hydrogen as a donor.

[0043] A dopant for adjusting the base doping concentration Db is a dopant added during the manufacturing of the semiconductor ingot. For example, when the semiconductor ingot is silicon, phosphorus, antimony, or arsenic can be used in the case of an N-type, and boron, aluminum, or the like can be used in the case of a P-type. In the case of a compound semiconductor other than silicon and an oxide semiconductor, respective dopants can also be used. In addition, a manufacturing method of the semiconductor ingot can be a float zone method (FZ method), a Czochralski method (CZ method), or a magnetic field applied Czochralski method (MCZ method).

[0044] Normally, the semiconductor substrate 10 with the base doping concentration Db should be such that it corresponds to the properties of the element to be formed in the semiconductor substrate 10, in particular with regard to a rated voltage or a withstand voltage. In contrast, in the case of the Fig. In the semiconductor device 100 shown in FIG. 1, by controlling the dosages and implantation depths of the hydrogen ions and helium ions, the donor concentration of the semiconductor substrate 10 and the bandwidth of the through region 106 at the time of completion of the semiconductor device 100 can be partially higher than the base doping concentration Db. Thus, an element having characteristics of a preferred rated voltage or withstand voltage can be formed even if the semiconductor substrate 10 having a different base doping concentration is used. Although the fluctuation in the donor concentration during the manufacture of the semiconductor substrate 10 is relatively large, the dosages of the hydrogen ions and the helium ions can be controlled with relatively high precision.Therefore, the concentration of the vacancy (V) generated by the implantation of the helium ion can be controlled with high precision, and the donor concentration of the passage region 106 can be controlled with high precision.

[0045] Fig. Fig. 2 shows a distribution of a hydrogen concentration, a distribution of a helium concentration, a distribution of a donor concentration and a distribution of a vacancy concentration 175 in a depth direction at a position indicated by a line AA in Fig. 1 is shown. In Fig. 2, a horizontal axis shows a depth position from the bottom surface 23, and a vertical axis shows a hydrogen concentration, a helium concentration, a donor concentration, and a vacancy concentration per unit volume on a logarithmic axis. Note that the vacancy concentration distribution 175 is a distribution immediately after the ion implantation of the hydrogen ions and the helium ions. When the semiconductor device 100 is completed, the vacancies are reduced or annihilated compared to immediately after the ion implantation, and it is a different concentration distribution than in Fig. 2. The hydrogen concentration and the helium concentration in Fig. 2 are chemical concentrations that are measured, for example, using the SIMS method. The donor concentration in Fig. 2 is an electrically activated doping concentration, which is measured, for example, by CV profiling or SR profiling. In Fig. 2, the hydrogen concentration distribution, the helium concentration distribution and the vacancy concentration distribution 175 are shown by dashed lines and the donor concentration distribution is shown by a solid line.

[0046] The hydrogen concentration distribution exhibits a peak of hydrogen concentration 131. The helium concentration distribution exhibits a peak of helium concentration 141. The peak of hydrogen concentration 131 has a local maximum value at the first depth Z1. The peak of helium concentration 141 has a local maximum value at the second depth Z2.

[0047] The donor concentration distribution includes a first peak of donor concentration 111 and a second peak of donor concentration 121. The first peak of donor concentration 111 has a local maximum at the first depth Z1. The second peak of donor concentration 121 has a local maximum at the second depth Z2. Note that the position at which the first peak of donor concentration 111 has the local maximum may not exactly correspond to the first depth. For example, as long as the position at which the first peak of donor concentration 111 has the local maximum lies within a full width at half maximum of the hydrogen concentration peak 131 with respect to the first depth Z1, the first peak of donor concentration 111 can be considered to be substantially located at the first depth Z1.Similarly, as long as the position at which the second peak of the donor concentration 121 has the local maximum value lies within a range of full width at half maximum of the peak of the helium concentration 141 with respect to the second depth Z2, it can be assumed that the second peak of the donor concentration 121 is substantially located at the second depth Z2.

[0048] The vacancy concentration distribution 175 has a first vacancy concentration peak corresponding to the hydrogen concentration peak 131 and a second vacancy concentration peak (a vacancy concentration peak 171) corresponding to the helium concentration peak 141. Note that the first vacancy concentration peak is omitted. The vacancy concentration peak 171 has a local maximum value at the second depth Z2.

[0049] Each concentration peak has a rising edge in which a value of the concentration increases from the lower surface 23 to the upper surface 21 of the semiconductor substrate 10, and a falling edge in which the value of the concentration decreases from the lower surface 23 to the upper surface 21 of the semiconductor substrate 10. In the present example, the hydrogen concentration peak 131 has a rising edge 132 and a falling edge 133. The helium concentration peak 141 has a rising edge 142 and a falling edge 143. The first donor concentration peak 111 has a rising edge 112 and a falling edge 113. The second donor concentration peak 121 has a rising edge 122 and a falling edge 123. The vacancy concentration peak 171 has a rising edge 172 and a falling edge 173.

[0050] The donor of the semiconductor substrate 10 includes a donor that existed both before and after the implantation of the hydrogen ion in the semiconductor substrate 10, that is, a donor related to the base doping concentration (the concentration Db), a donor obtained by activating the implanted hydrogen, and the VOH defect described above. For example, a ratio at which hydrogen is activated as a donor is approximately 1%. In the via region 106, in a region spaced apart from the first depth Z1 and the second depth Z2 to a certain extent, a donor due to a VOH defect corresponding to a vacancy concentration has a higher ratio than a donor due to a VOH defect corresponding to a chemical hydrogen concentration, and a ratio of the donor concentration is controlled by the vacancy concentration.The VOH defect corresponding to the chemical hydrogen concentration indicates a VOH defect for which the chemical hydrogen concentration is more dominant than the vacancy concentration. The VOH defect corresponding to the vacancy concentration indicates a VOH defect for which the vacancy concentration is more dominant than the chemical hydrogen concentration.

[0051] The VOH defect, for which the chemical hydrogen concentration is dominant, has the following meaning here. In a case where a vacancy, oxygen, and hydrogen cluster to form a VOH defect, since the chemical hydrogen concentration is sufficiently higher than the vacancy concentration, it is found that the donor concentration distribution due to the VOH defect is similar to the chemical hydrogen concentration distribution. For example, it can be said that when the chemical hydrogen concentration is higher than the vacancy concentration at a certain depth and a depth near it, the donor concentration distribution of the VOH defect occurs where the chemical hydrogen concentration distribution is dominant.

[0052] On the other hand, the VOH defect, where the 175 vacancy concentration distribution dominates, shows that the donor concentration distribution due to the VOH defect is similar to the vacancy concentration distribution because the vacancy concentration is sufficiently higher than the chemical hydrogen concentration. For example, it can be said that when the vacancy concentration is higher than the chemical hydrogen concentration at a certain depth and a depth close to it, the donor concentration distribution of the VOH defect occurs where the 175 vacancy concentration distribution is dominant.

[0053] It is assumed that in the passage region 106, except for the vicinity of the first depth Z1 and the vicinity of the second depth Z2, the vacancies (V, VV and the like) generated by the passage of hydrogen are distributed with an approximately uniform concentration in the depth direction as shown in Fig. 2. Furthermore, it is assumed that oxygen (O), which is implanted during the manufacture of the semiconductor substrate 10 or the like, also has a nearly uniform distribution in the depth direction. Furthermore, a sufficient amount of hydrogen is present in the through region 106 because hydrogen diffuses at the peak of the hydrogen concentration 131. This forms a flat donor distribution for the VOH defect.

[0054] Therefore, in a region other than the vicinity of the first depth Z1 and the vicinity of the second depth Z2 in the through region 106, there is a shallow region 150 in which the VOH defects acting as donors have an approximately uniform distribution. A distribution of the donor concentration in the shallow region 150 is approximately constant in the depth direction. For example, stating that the donor concentration is approximately constant in the depth direction may indicate a state in which a region in which a difference between a maximum value and a minimum value of the donor concentration is within 50% of the maximum value of the donor concentration is continuous in the depth direction. The difference may be 30% or less or 10% or less of the maximum value of the donor concentration in the region.

[0055] Alternatively, with respect to an average concentration of the donor concentration distribution in a predetermined range in the depth direction, a value of the donor concentration distribution may be within ±50%, within ±30%, or within ±10% of the average concentration of the donor concentration distribution. The predetermined range in the depth direction may be described, for example, as follows. That is, assuming that a length from the first depth Z1 to the second depth Z2 Z L a zone with a length of 0.5 Z L between two points, each 0.25Z away from the center Zc, between Z1 and Z2, on one side of the first depth Z1 and one side of the second depth Z2 can be defined as a range. Depending on a length of the shallow area 150, a length of the preferred area can be 0.75Z L , 0.3Z L or 0.9Z L be.

[0056] The area in which the flat region 150 is located can be controlled by a position of the helium concentration peak 141. The flat region 150 is located between the hydrogen concentration peak 131 and the helium concentration peak 141. Furthermore, a donor concentration of the flat region 150 can be controlled by a helium ion dosage at the helium concentration peak 141. Increasing the helium ion dosage increases the number of vacancies (V) created in the passage region 106 and increases the donor concentration.

[0057] Note that if the helium ion is implanted at a position lower than the peak hydrogen concentration 131, the acceleration energy of the helium ion can be set to a high value, approximately equal to the value at which the helium ion penetrates (passes through) the semiconductor substrate 10. Therefore, the peak helium concentration 141 may not remain within the semiconductor substrate 10. This also makes it possible to increase the vacancy concentration. On the other hand, if the acceleration energy is too large, the substrate may be excessively damaged during ion implantation, and a flat distribution of vacancies in the passage region 106 cannot be maintained. Therefore, the peak helium concentration 141 may be within the semiconductor substrate 10.

[0058] The peak of helium concentration 141 is located at a position lower than the peak of hydrogen concentration 131, and therefore, a spread of the peak of helium concentration 141 is likely to be larger than that of the peak of hydrogen concentration 131. Therefore, a peak spread of the second peak of donor concentration 121 is likely to be larger than that of the first peak of donor concentration 111. This means that the second peak of donor concentration 121 is likely to be a slightly steeper peak than the first peak of donor concentration 111.

[0059] Furthermore, in the present example, a concentration value of the peak of the hydrogen concentration 131 is greater than a concentration value of the peak of the helium concentration 141. The concentration value of the peak of the hydrogen concentration 131 may be 10 times or more or 100 times or more greater than the concentration value of the peak of the helium concentration 141. In another example, the concentration value of the peak of the hydrogen concentration 131 may be less than or equal to the concentration value of the peak of the helium concentration 141.

[0060] In the present example, an amount of hydrogen activated as a donor at the hydrogen concentration peak 131 is relatively large because the concentration value of the hydrogen concentration peak 131 is high. This means that a ratio of the donor of the VOH defect for which the chemical hydrogen concentration distribution is dominant over the vacancy concentration distribution 175 is high.

[0061] In this case, the shape of the first peak of donor concentration 111 is similar to a shape of the peak of hydrogen concentration 131.

[0062] On the other hand, the amount of hydrogen activated as a donor at the helium concentration peak 141 is relatively small because the helium concentration peak 141 is far away from the hydrogen concentration peak 131. That is, the donor of the VOH defect, where the vacancy concentration distribution 175 dominates, has a relatively higher ratio than the donor of the VOH defect, where the chemical hydrogen concentration distribution dominates. In this case, the similarity between the shape of the second donor concentration peak 121 and the shape of the helium concentration peak 141 is lower than the similarity between the shape of the first donor concentration peak 111 and the shape of the hydrogen concentration peak 131.Since the VOH defects are assumed to have a roughly uniform distribution throughout most of the through-pass region 106, the second donor concentration peak 121 has an even less steep shape. The similarity of the peak shape can be an index showing that the greater the difference in slope of the corresponding flanks between the hydrogen concentration peak or the helium concentration peak and the donor concentration peak, the smaller the similarity value.

[0063] In such a structure, the flat region 150 may be located between the first depth Z1 and the second depth Z2. The depth-direction length of the flat region 150 may be 10% or more, 30% or more, or 50% or more of the depth-direction thickness of the semiconductor substrate 10. Furthermore, the depth-direction length of the flat region 150 may be 10 µm or more, 30 µm or more, 50 µm or more, or 100 µm or more.

[0064] A minimum value of the donor concentration in the shallow region 150 may be higher than the base doping concentration Db of the semiconductor substrate 10. That is, the donor concentration in the shallow region 150 may be higher than the base doping concentration Db over the entire shallow region 150. A difference between the donor concentration of the shallow region 150 and the base doping concentration Db of the semiconductor substrate 10 can be adjusted, for example, by dosing helium at the peak of the helium concentration 141.

[0065] A minimum value of the donor concentration between the first depth Z1 and the second depth Z2 may be higher than the base doping concentration of the semiconductor substrate 10. An N-type region may be continuously arranged between the peak hydrogen concentration 131 and the peak helium concentration 141. Furthermore, a minimum value of the donor concentration between the second depth Z2 and the bottom surface 23 of the semiconductor substrate 10 may be greater than the donor concentration of the semiconductor substrate 10.

[0066] Fig. 3A is a graph illustrating a relationship between a hydrogen concentration peak 131 and a first donor concentration peak 111. In the present example, a slope 134 of the rising edge 132 of the hydrogen concentration peak 131 is used to normalize a slope 114 of the rising edge of the first donor concentration peak 111. The normalization is, for example, a process of dividing the slope 114 by the slope 134. Note that in the present description, a slope may be used to express an absolute value of the slope.

[0067] The slope of the rising edge may be a slope between a position where a concentration assumes a local minimum value and a position where a concentration assumes a predetermined ratio to the local maximum value. The preferred ratio may be 80%, 50%, 10%, or 1%, and other ratios may be used. Furthermore, in the peak of the hydrogen concentration 131 and the first peak of the donor concentration 111, a slope of a concentration distribution between the first depth Z1 and the bottom surface 23 of the semiconductor substrate 10 may be used. In the Fig. In the example shown in FIG. 3A, the slope 134 of the hydrogen concentration peak 131 is given as (H1-aH1) / (Z1-Z3), and the slope 114 of the first donor concentration peak 111 is given as (D1-aD1) / (Z1-Z4). H1 is a hydrogen concentration at the first depth Z1, D1 is a donor concentration at the first depth Z1, a is a predetermined ratio, Z3 is a depth at which the hydrogen concentration in the rising edge 132 of the hydrogen concentration peak 131 is aH1, and Z4 is a depth at which the donor concentration in the rising edge 112 of the first donor concentration peak 111 is aD1. For example, slope 114 is normalized by slope 134 to (D1-aD1)(Z1-Z3) / {(H1-aH1)(Z1-Z4)}. A slope obtained by normalizing slope 114 by slope 134 is determined as α.

[0068] Fig. 3B is a graph illustrating a relationship between a peak of helium concentration 141 and a second peak of donor concentration 121. In the present example, a slope 144 of the rising edge 142 of the peak of helium concentration 141 is used to normalize a slope 124 of the rising edge of the second peak of donor concentration 121.

[0069] In the Fig. In the example shown in FIG. 3B, the slope 144 of the helium concentration peak 141 is given as (H2-aH2) / (Z2-Z5), and the slope 124 of the second donor concentration peak 121 is given as (D2-aD2) / (Z2-Z6). H2 is a helium concentration at the second depth Z2, D2 is a donor concentration at the second depth Z2, a is a predetermined ratio, Z5 is a depth at which the helium concentration in the rising edge 142 of the helium concentration peak 141 is aH2, and Z6 is a depth at which the donor concentration in the rising edge 122 of the second donor concentration peak 121 is aD2. A ratio a used to normalize the slope of the second peak of donor concentration 121 may be the same as or different from a ratio a used to normalize the slope of the first peak of donor concentration 111.For example, slope 124 is normalized by slope 144 to (D2-aD2)(Z2-Z5) / {(Z2-Z6)(H2-aH2)}. A slope obtained by normalizing slope 124 by slope 144 is defined as β.

[0070] The normalized slope β of the rising edge 122 of the second peak of the donor concentration 121 is smaller than the normalized slope α of the rising edge 112 of the first peak of the donor concentration 111. This means that, with respect to the concentration peak of hydrogen or helium, the second peak of the donor concentration 121 is a less steep peak than the first peak of the donor concentration 111. Implanting the hydrogen ions and helium ions to create such a second peak of the donor concentration 121 makes it possible to form the flat region 150. Furthermore, forming the second peak of the donor concentration 121 with a less steep shape makes it possible to moderate a change in the donor concentration at an edge of the flat region 150.The normalized slope β of the rising edge 122 of the second peak of the donor concentration 121 may be 1 time or less, 0.1 time or less, or 0.01 time or less of the normalized slope α of the rising edge 112 of the first peak of the donor concentration 111.

[0071] Furthermore, the slope 144 of the rising edge 142 of the helium concentration peak 141 may be smaller than a slope 145 of the falling edge 143. The concentration distribution of helium ions implanted at a deep position from the lower surface 23 may have a slight trace on the lower surface 23 side, so that by comparing the slope 144 of the rising edge 142 with the slope 145 of the falling edge 143, it can be determined whether helium of the helium concentration peak 141 was implanted from the lower surface 23 side. The slope 145 is given as (H2-aH2) / (Z7-Z2). A slope 125 is given as (D2-aD2) / (Z7-Z2). Note that in Fig. 3B, the slope 124 of the rising edge 122 of the second peak of the donor concentration 121 is greater than the slope 125 of the falling edge 123; however, similar to the peak of the helium concentration 141, the slope 124 of the rising edge 122 of the second peak of the donor concentration 121 may be smaller than the slope 125 of the falling edge 123.

[0072] Fig. 3C is a diagram illustrating a slope of a rising edge 142. The slope of the rising edge 142 can be viewed as follows. As shown in Fig. As described in Figure 3C, in the helium concentration peak 141, a width (10% of the full width) between two positions Z8, Z9 with concentrations that are 10% of a peak H2 concentration (0.1×H2) is defined as FW 10%M. The two positions Z8, Z9 are two positions closest to the peak position Z2 among points where the helium concentration is 0.1×H2, with the peak position Z2 in between. The position of the two positions Z8, Z9 that lies on the side of the hydrogen concentration peak is defined as position Z8. A slope of the donor concentration at position Z8 is approximately flat. A slope of the helium concentration at position Z8 exceeds the slope of the donor concentration at position Z8 by 100 times. For example, the slope of the helium concentration at position Z8 may be 100 times or more, or 1000 times or more, of the donor concentration at position Z8.

[0073] Fig. Figure 4A is a diagram illustrating another definition of normalizing a slope of a rising edge 112. For example, by normalizing the slope of the rising edge 112, the following index γ is introduced. In the example of Fig. 3A, position Z3 and position Z4 are different; however, in the present example, position Z3 and position Z4 are set to be the same position (Z3=Z4). Here, position Z3 is a predetermined position. Position Z3 only needs to be a position where the hydrogen concentration distribution and the donor concentration distribution have rising edges 132, 112, and which is closer to one side of the bottom surface than position Z1. At position Z3, a hydrogen concentration is set as a×H1 and a donor concentration is set as b×D1. The term c is a ratio of the hydrogen concentration at position Z3 to the concentration H1 of the peak of the hydrogen concentration 131 at position Z1. The term d is a ratio of the donor concentration at position Z3 to the concentration D1 of the first peak of the donor concentration 111 at position Z1.Here, a ratio of a slope of each of the hydrogen concentration and the donor concentration in a range from Z3 to Z1 and a slope ratio γ obtained by normalizing the slope ratio are introduced. The ratio of the slope of the hydrogen concentration in the range from Z3 to Z1 is defined as (H1 / aH1) / (Z1-Z3). Similarly, the ratio of the slope of the donor concentration in the range from Z3 to Z1 is defined as (D1 / bD1) / (Z1-Z3). Then, the slope ratio γ obtained by normalizing the ratio of the slope of the donor concentration by the ratio of the slope of the hydrogen concentration in the range from Z3 to Z1 is defined as {(D1 / bD1) / (Z1-Z3)} / {(H1 / aH1) / (Z1-Z3)}. The normalized slope ratio γ is obtained as a simple ratio a / b by calculating the expression described above.

[0074] Fig. Figure 4B is a diagram illustrating another definition of normalizing the slope of a rising edge 122. For example, by normalizing the slope of the rising edge 122, an index ε similar to the index γ is introduced. In the example of Fig. 3B, position Z5 and position Z6 are different; however, in the present example, position Z5 and position Z6 are set to be the same position (Z5=Z6). Here, position Z5 is a predetermined position. Position Z5 only needs to be a position where the helium concentration distribution and the donor concentration distribution have rising edges 142, 122, and which is closer to one side of the bottom surface than position Z2. At position Z5, a helium concentration is set as c×H2 and a donor concentration is set as d×D2. The term c is a ratio of the helium concentration at position Z5 to the concentration H2 of the helium concentration peak 141 at position Z2. The term d is a ratio of the donor concentration at position Z5 to the concentration D2 of the second donor concentration peak 121 at position Z1.Here, a ratio of a slope of each of the helium concentration and the donor concentration in a range from Z5 to Z2 and a slope ratio ε obtained by normalizing the slope ratio are introduced. The slope ratio of the helium concentration in the range from Z5 to Z2 is defined as (H2 / cH2) / (Z2-Z5). Similarly, the slope ratio of the donor concentration in the range from Z5 to Z2 is defined as (D2 / dD2) / (Z2-Z5). Then, the slope ratio ε obtained by normalizing the slope ratio of the donor concentration by the slope ratio of the helium concentration in the range from Z5 to Z2 is defined as {(D2 / dD2) / (Z2-Z5)} / {(H2 / cH2) / (Z2-Z5)}. The normalized slope ratio ε is obtained as a simple ratio c / d by calculating the expression described above.

[0075] Regarding the hydrogen concentration peak 131 and the first donor concentration peak 111, the hydrogen concentration distribution and the donor concentration distribution often have similar shapes. For example, here, a similar shape means that when the horizontal axis represents the depth and the vertical axis represents the common logarithm of the concentration, the donor concentration distribution produces a distribution that reflects the hydrogen concentration distribution. This means that the donor concentration distribution in the predetermined range from Z3 to Z1 becomes a distribution that reflects the hydrogen concentration distribution by implanting hydrogen ions and further performing thermal annealing. For example, if H1 of the hydrogen concentration peak 131 is 1×10 17 atoms / cm 3 and the hydrogen concentration aH1 at position Z3 2×1016 atoms / cm 3 then a is equal to 0.2. On the other hand, if D1 of the peak of the donor concentration 111 1×10 16 atoms / cm 3 and the donor concentration bD1 at position Z3 2×10 15 atoms / cm 3 , then b is equal to 0.2. Accordingly, the normalized slope ratio γ=a / b and thus equal to 1. That is, at the depth position Z1 near the bottom surface, the ratio a of the slope of the hydrogen concentration distribution and the ratio b of the slope of the donor concentration distribution have approximately the same value and can be said to have a similar shape.

[0076] On the other hand, with respect to the helium concentration peak 141 and the second donor concentration peak 121, the helium concentration distribution and the donor concentration distribution may have different shapes. This means that in the given range from Z5 to Z2, the donor concentration distribution may not reflect the helium concentration distribution. For example, if H2 of the hydrogen concentration peak 141 is 1×10 16 atoms / cm 3 and the hydrogen concentration cH2 at position Z5 1×10 15 atoms / cm 3 then c is equal to 0.1. On the other hand, if D2 of the peak of the donor concentration is 121 3×10 14 atoms / cm 3 and the donor concentration dD2 at position Z5 1.5×10 14 atoms / cm 3, then d is equal to 0.5. Accordingly, the normalized slope ratio ε=c / d is equal to 0.2. That is, at the depth position Z2, which is a position sufficiently deep from the bottom surface, the ratio c of the slope of the helium concentration distribution is a value 0.2 times the ratio d of the slope of the donor concentration distribution, and it can be said that the two ratios have shapes that are far from similar to each other.

[0077] Comparing the normalized inclination ratios γ and ε, γ may be close to 1 when the position of the peak of the helium concentration distribution is close to the bottom surface, and ε may be a value sufficiently smaller than 1 when the position of the peak of the helium concentration distribution is sufficiently deep from the bottom surface. That is, the normalized inclination ratio ε may be smaller than the normalized inclination ratio γ. Further, the inclination ratio ε may be 0.9 or less, 0.5 or less, or 0.2 or less. On the other hand, the inclination ratio ε may be 0.1 or less, or 0.01 or less.

[0078] As another example of the second peak of the donor concentration 121, the donor concentration calculated by the propagation resistance, i.e., a carrier concentration, may be lower than the carrier concentration at the front and rear positions at the depth position Z2 due to a decrease in carrier mobility. In such a case, the rising edge 122 has a decreasing slope, and thus d has a negative sign. That is, d is a negative number whose magnitude is greater than or equal to 1. For this reason, ε is a negative number. That is, the normalized slope ratio ε may be smaller than the normalized slope ratio γ. Further, the slope ratio ε may be 0.9 or less, 0 or less, or -1 or less. On the other hand, the slope ratio ε may be -10 or less, or -100 or less.

[0079] Note that an actual position of the helium concentration peak 141 may be different from an actual position of the second donor concentration peak 121. Furthermore, the position of the hydrogen concentration peak 131 and the position of the first donor concentration peak 11 may not exactly match. Thus, when the position of the hydrogen or helium concentration peak and the donor concentration position do not match, for convenience, the concentration at the hydrogen or helium concentration peak position can be set to the position of the donor concentration peak. For this reason, calculation of the definition described above is possible.

[0080] An important point in the above description is that the peak of helium concentration 141 exhibits the local maximum value. This means that the helium concentration distribution at depth Z2 reaches its local maximum value. Since the peak of helium concentration 141 reaches its local maximum value, it is possible to compare the normalized slope ratios described above.

[0081] Fig. 5 is a diagram illustrating a shallow region 150. As described above, a distribution of the donor concentration in the shallow region 150 is approximately constant in the depth direction. The shallow region 150 is a region in which a range where the donor concentration lies between a predetermined maximum value max and a predetermined minimum value min is continuous in the depth direction. The maximum value max can be used as a maximum value of the donor concentration in the region. The minimum value min can be a value of 50%, a value of 70%, or a value of 90% with respect to the maximum value max.

[0082] Alternatively, as described above, with respect to an average concentration of the donor concentration distribution in a predetermined range in the depth direction, a value of the donor concentration distribution may be within ±50%, within ±30%, or within ±10% of the average concentration of the donor concentration distribution. The predetermined range in the depth direction may be the same as described above.

[0083] Fig. 6 is a diagram showing an example of a semiconductor device 100. The semiconductor device 100 of the present example functions as an IGBT. The semiconductor device 100 of the present example includes the semiconductor substrate 10, an interlayer dielectric film 38, an emitter electrode 52, and a collector electrode 54. The interlayer dielectric film 38 is formed to cover at least a part of the upper surface 21 of the semiconductor substrate 10. A through hole is formed in the interlayer dielectric film 38 as a contact hole. The upper surface 21 of the semiconductor substrate 10 is exposed through the contact hole. The interlayer dielectric film 38 may be silicate glass such as PSG and BPSG, and may be an oxide film, a nitride film, or the like.

[0084] The emitter electrode 52 is formed on the upper surfaces of the semiconductor substrate 10 and the interlayer dielectric film 38. The emitter electrode 52 is also formed within the contact hole and is in contact with the upper surface 21 of the semiconductor substrate 10 exposed through the contact hole.

[0085] The collector electrode 54 is formed on the lower surface 23 of the semiconductor substrate 10. The collector electrode 54 may be in contact with the entire lower surface 23 of the semiconductor substrate 10. The emitter electrode 52 and the collector electrode 54 are formed of a metal such as aluminum.

[0086] The semiconductor substrate 10 of the present example has an N-type drift region 18, an N+ type emitter region 12, a P-type base region 14, an N+ type accumulation region 16, an N+ type buffer region 20, and a P+ type collector region 22.

[0087] The emitter region 12 is a region disposed in contact with the upper surface 21 of the semiconductor substrate 10 and having a higher donor concentration than the drift region. The emitter region 12 comprises, for example, an N-type impurity such as phosphorus.

[0088] The base region 14 is arranged between the emitter region 12 and the drift region 18. The base region 14 comprises, for example, an impurity of a type such as boron. For example, along an extension direction of a trench region (a Y-axis direction in Fig. 6) A P-type contact region (not shown) is arranged alternately with the emitter region 12. The contact region may be formed on the upper surface 21 of the base region and deeper than the emitter region 12. The contact region suppresses a latch-up effect of the IGBT at the time of turn-off.

[0089] The accumulation region 16 is located between the base region 14 and the drift region 18 and has one or more peaks of donor concentration whose donor concentration is higher than that of the drift region 18. The accumulation region 16 may include N-type impurities such as phosphorus and may include hydrogen.

[0090] The collector region 22 is arranged in contact with the bottom surface 23 of the semiconductor substrate 10. An acceptor concentration in the collector region 22 may be higher than an acceptor concentration in the base region 14. The collector region 22 may have a P-type impurity that is the same as or different from that of the base region 14.

[0091] Buffer region 20 is disposed between collector region 22 and drift region 18 and has one or more donor concentration peaks whose donor concentration is higher than that of drift region 18. Buffer region 20 includes an N-type impurity, such as hydrogen. Buffer region 20 may act as a field stop layer that prevents a depletion layer from reaching collector region 22, with the depletion layer extending from one side of the bottom surface of base region 14.

[0092] A gate trench portion 40 extends through the emitter region 12, the base region 14, and the accumulation region 16 from the upper surface 21 of the semiconductor substrate 10 to reach the drift region 18. The accumulation region 16 of the present example is disposed above a lower end of the gate trench portion 40. The accumulation region 16 may be disposed covering the entire lower surface of the base region 14. By disposing the accumulation region 16, whose concentration is higher than that of the drift region 18, between the drift region 18 and the base region 12, it is possible to enhance a carrier injection enhancement effect (IE effect) and reduce an ON voltage of the IGBT.

[0093] The gate trench portion 40 includes a gate trench, a gate dielectric film 42, and a gate conductive portion 44 formed on the upper surface side of the semiconductor substrate 10. The gate dielectric film 42 is formed to cover an inner wall of the gate trench. The gate dielectric film 42 can be formed by oxidizing or nitriding a semiconductor on the inner wall of the gate trench. The gate conductive portion 44 is formed on an inner side, further inside the gate trench than the gate dielectric film 42. That is, the gate dielectric 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.

[0094] The conductive gate portion 44 includes a region opposite the base region 14, with the gate dielectric film 42 interposed therebetween. The gate trench portion 40 is covered with the interlayer dielectric film 38 in cross section on the upper surface of the semiconductor substrate 10; however, the conductive gate portion 44 is connected to a gate electrode in another cross section. When a predetermined gate voltage is applied to the conductive gate portion 40, a channel is formed through an inversion layer, with electrons flowing onto a surface layer in the base region 14 at an interface in contact with the gate trench portion 40.

[0095] The first peak of the donor concentration 111 may be located in the buffer region 20. The second peak of the donor concentration 121 may be located in an N-type region above the buffer region 20. The second peak of the donor concentration 121 may be located between the buffer region 20 and the accumulation region 16. The second peak of the donor concentration 121 of the present example is located in the drift region 18. The second peak of the donor concentration 121 may be located below the lower end of the gate trench section 40, may be in contact with the lower end of the gate trench section 40, and may be located above the lower end of the gate trench section 40. Furthermore, a base doping region 180, which is a region of the base doping concentration Db of the substrate, may be located between the second peak of the donor concentration 121 and the accumulation region 16.

[0096] Fig. 7 is a diagram showing an example of a distribution of a carrier concentration in the depth direction at a position of the line BB in Fig. 6 illustrated. In Fig. 7, parts of the hydrogen concentration distribution and the helium concentration distribution are shown together. The vertical axis in Fig. 7 is a logarithmic axis.

[0097] A carrier concentration distribution in the buffer region 20 of the present example includes a plurality of peaks 24 at different positions in the depth direction. Each of the peaks 24 is a donor concentration peak. The peak 24 may contain hydrogen as an impurity. By arranging the plurality of peaks 24, the depletion layer can be suppressed from reaching the collector region 22. The first donor concentration peak 111 may function as peak 24 in the buffer region 20.

[0098] For example, the first peak of donor concentration 111 may function as a peak that is farthest from the bottom surface 23 of the semiconductor substrate 10 among the plurality of peaks 24 of the buffer region 20. The flat region 150 is located between the first peak of donor concentration 111 in the buffer region 20 and the second peak of donor concentration 121.

[0099] The first peak of the donor concentration 111 may have a higher donor concentration than a peak 24 of the plurality of peaks 24 in the buffer region 20 spaced from the lower surface 23. By making the concentration of the first peak of the donor concentration 111 high, the shallow region 150 can be easily formed even if the first peak of the donor concentration 111 is at a large distance from the second peak of the donor concentration 121. The hydrogen concentration distribution may have one or more peaks of the hydrogen concentration 194 between the first depth Z1 and the lower surface 23. A peak of the hydrogen concentration 194 may be located in the Fig. 6 or the like. The hydrogen concentration peak 194 may be located at the same depth position as peak 24.

[0100] The accumulation region 16 of the present example has a plurality of peaks 25. Each of the peaks 25 is a peak of the donor concentration. The second peak of the donor concentration 121 is located closer to the bottom surface 23 side than the accumulation region 16. Between the second peak of the donor concentration 121 and the accumulation region 16, the region (the base doping region 180) of the base doping concentration Db of the substrate may be arranged. In another example, a donor concentration between the second peak of the donor concentration 121 and the accumulation region 16 may be higher than the base doping concentration Db of the semiconductor substrate.

[0101] Furthermore, the semiconductor device 100 may use a non-doped substrate in which the entire ingot has not been doped with a dopant such as phosphorus (P) during the production of the semiconductor ingot as the semiconductor substrate 10. In this case, a base doping concentration Dn of the semiconductor substrate 10 is lower than the base doping concentration Db. In the example of Fig. 7, a region in which the doping concentration is the base doping concentration Dn is defined as the non-doped region 181. The base doping concentration Dn of the non-doped region 181 is, for example, 1×10 10 atoms / cm 3 or more and 5×10 12 atoms / cm 3 or less. The base doping concentration Dn can be 1×10 11 atoms / cm 3 or higher. The base doping concentration Dn can be 5×10 12 atoms / cm 3or lower. Note that any concentration in this description may be a value at room temperature. For example, a value of 300 K (Kelvin) (approximately 26.9°C) may be used as room temperature.

[0102] Fig. Fig. 8 is a diagram showing another example of the semiconductor device 100. The semiconductor device 100 of the present example differs from that shown in Fig. 6 and Fig. 7 is that the second peak of the donor concentration 121 (and the peak of the helium concentration 141) lies in the accumulation region 16. Other structures can be compared with those of the semiconductor device 100 shown in Fig. 6 and Fig. 7 described semiconductor device 100.

[0103] Fig. 9 is a diagram showing an example of a distribution of a carrier concentration in the depth direction at a position of the line CC in Fig. 8 illustrated. In Fig. 9 parts of the hydrogen concentration distribution and the helium concentration distribution are shown together. The vertical axis in Fig. 9 is a logarithmic axis.

[0104] A carrier concentration distribution in the accumulation region 16 of the present example includes a plurality of peaks at different positions in the depth direction. Each of the peaks is a donor concentration peak. The peak in the accumulation region 16 may contain hydrogen or phosphorus as an impurity. In a structure in which a gate trench portion and a dummy trench portion are adjacent to each other (see, for example, WO 2018 / 030440 A1), it is possible to suppress a displacement current to the gate trench portion by arranging a plurality of peaks in the accumulation region 16. The dummy trench portion has a structure similar to that of the gate trench portion and is a trench portion to which an emitter potential is applied.

[0105] The second donor concentration peak 121 of the present example functions as any of the donor concentration peaks in the accumulation region 18. For example, the second donor concentration peak 121 may function as a peak farthest from the top surface 21 of the semiconductor substrate 10 among the plurality of peaks in the accumulation region 16. The flat region 150 of the present example is located between the first donor concentration peak 111 in the buffer region 20 and the second donor concentration peak 121 in the accumulation region 16.

[0106] The donor concentration of the second peak of the donor concentration 121 may be lower than, equal to, or higher than the donor concentration of the other peak 25 of the buffer region 20. If the buffer region 20 has three or more peaks, peaks 25 other than the second peak of the donor concentration 121 may have the same donor concentration. The donor concentration of the second peak of the donor concentration 121 may be determined depending on the donor concentration that the flat region 150 is intended to have.

[0107] A carrier concentration of the drift region 18 in the present example can be higher than the base doping concentration Db of the substrate across the entire depth direction. With such a structure, the overall carrier concentration of the drift region 18 can be adjusted with high accuracy.

[0108] Peak 25, which is different from the second peak of donor concentration 121, may be a peak due to a donor other than hydrogen. For example, peak 25 is a peak where phosphorus acts as a donor. By using phosphorus as a donor, the VOH defect is less likely to be generated, and the donor concentrations in peak 25 and its vicinity can be easily controlled by a phosphorus concentration. In addition, a width of the second peak of donor concentration 121 in the depth direction may be wider than a width of peak 25 in the depth direction. This allows the displacement current to the gate trench portion to be further suppressed. Furthermore, as shown in Fig. 9, there may be a valley in the donor concentration distribution between the second peak of the donor concentration 121 and the peak 25 of the accumulation region 16. Alternatively, as shown by a dotted line between the two peaks in Fig. 9, the distribution of the donor concentration of the accumulation region 16 shows a kink instead of a valley.

[0109] Fig. Figure 10 shows the distribution of hydrogen concentration, the distribution of helium concentration and a distribution of a vacancy concentration in the depth direction at the position indicated by the line AA in Fig. 1. The carrier concentration is measured by SR profiling. Near a region (Z2) of the peak helium concentration 141, slightly more defects are generated than in the through region 106. Due to a defect remaining without combining with hydrogen, a valley 151 may be generated in the carrier concentration distribution near the second depth Z2.

[0110] When the valley 151 is generated, the slope of the rising edge 122 of the second peak of the donor concentration 121 may be steep in the calculation. Therefore, it is preferable to calculate the slope of the rising edge 122 without any influence of the valley 151. For example, the slopes of the respective rising edges of the second peak of the donor concentration 121 and the peak of the helium concentration 141 may be calculated using the concentrations at the second depth Z2 and the concentrations at a depth Zc. The depth Zc may be a position closer to the bottom surface 23 side than the valley 151. The depth Zc in the present example is the central depth of the shallow region 150 in the depth direction. This allows the slope of the rising edge 122 of the second peak of the donor concentration 121 to be calculated without the influence of the valley 151.As described above, a slope of the concentration difference can be used in normalization and a slope of a ratio of the concentration can be used.

[0111] Fig. 11 is a diagram showing an exemplary arrangement of all elements on an upper surface 21 of a semiconductor substrate 10. In Fig. 11, an end portion of an outer periphery of the semiconductor substrate 10 is defined as an outer peripheral end 140.

[0112] The semiconductor device 100 includes an active portion 120 and an edge termination structure portion 90. When the semiconductor device 100 is controlled to be in an ON state, the active portion 120 is a portion where a main current flows between the upper surface 21 and the lower surface 23 of the semiconductor substrate 10. That is, the active portion 120 is a portion where a current flows in the depth direction of the semiconductor substrate 10, from the upper surface 21 to the lower surface 23 of the semiconductor substrate 10 or from the lower surface 23 to the upper surface 21.

[0113] The active section 120 of the present example includes a transistor section 70 and a diode section 80. The transistor section 70 and the diode section 80 may be arranged along the X-axis direction. In the example of Fig. 11, the transistor section 70 and the diode section 80 are alternately arranged in contact with each other in an X-axis direction. In the active section 120, the transistor sections 70 may be arranged at both ends in the X-axis direction. The emitter electrode 52 may cover the transistor section 70 and the diode section 80. The active region 120 may refer to a region covered by the emitter electrode.

[0114] The transistor section 70 of the present example comprises the IGBT (Insulated Gate Bipolar Transistor) used in Fig. 6 to Fig. 10. The diode section 80 of the present example comprises a FWD (Free Wheeling Diode). In each diode section 80, an N+ type cathode region 82 is arranged in a region that is in contact with the lower surface 23 of the semiconductor substrate 10. In Fig. In FIG. 11, the diode portion 80 indicated by the solid line is a region where the cathode region 82 is disposed on the lower surface 23 of the semiconductor substrate 10. In the semiconductor device 100 of the present example, in the region in contact with the lower surface 23 of the semiconductor substrate 10, the collector region 22 is disposed in a region different from the cathode region 82.

[0115] The diode portion 80 is a region in which the cathode region 82 is projected in the Z-axis direction. The transistor portion 70 is a region in which the collector region 22 is arranged on the lower surface 23 of the semiconductor substrate, and a unit structure including the emitter region 12 is regularly arranged on the upper surface 21 of the semiconductor substrate 10. A boundary between the diode portion 80 and the transistor portion 70 in the Y-axis direction is a boundary between the cathode region 82 and the collector region 22. The diode portion 80 may also include a portion (in Fig. 11, a portion indicated by a dashed line and showing the diode portion 80 (enlarged) formed by extending the area where the cathode region 82 is projected to an end portion of the active portion 120 or a gate runner 48 in the Y-axis direction. The extended area does not include the emitter region 12.

[0116] The semiconductor device 100 of the present example further includes a gate metal layer 50 and the gate runner 48. Furthermore, the semiconductor device 100 may have a gate pad 116, an emitter pad 118, and the like. The gate pad 116 is electrically connected to the gate metal layer 50 and the gate runner 48. The emitter pad 118 is electrically connected to the emitter electrode 52.

[0117] The gate metal layer 50 may be arranged to surround the active portion 120 in plan view. The gate pad 116 and the emitter pad 118 may be arranged in a region surrounded by the gate metal layer 50. The gate metal layer 50 may be formed from a metal material such as aluminum or an aluminum-silicon alloy. The gate metal layer 50 is insulated from the semiconductor substrate 10 by the interlayer dielectric film. Fig. 11, an illustration of the interlayer dielectric film 38 is omitted. Furthermore, the gate metal layer 50 is arranged separately from the emitter electrode 52. The gate metal layer 50 transmits a gate voltage applied to the gate pad 116 to the transistor section 70. The conductive gate section 44 of the transistor section 70 is connected directly to the gate metal layer 50 or indirectly via another conductive component to the gate metal layer 50.

[0118] The gate runner 48 connects the gate metal layer 50 and the conductive gate section 44. The gate runner 48 may be formed from a semiconductor material such as polysilicon doped with impurities. A portion of the gate runner 48 may be disposed over the active section 120. The Fig. The gate runner 48 shown in FIG. 11 is arranged across the active portion 120 in the X-axis direction. This makes it possible to suppress a decrease and delay in the gate voltage even in an inner side of the active portion 120, which is spaced from the gate metal layer 50. A part of the gate runner 48 may be arranged to surround the active portion 120 along the gate metal layer 50. The gate runner 48 may be connected to the conductive gate portion 44 at the end portion of the active portion 120.

[0119] On the upper surface 21 of the semiconductor substrate 10, the edge termination structure portion 90 is disposed between the active portion 120 and the outer peripheral end 140 of the semiconductor substrate 10. In the present example, the gate metal layer 50 is disposed between the edge termination structure portion 90 and the active portion 120. The edge termination structure portion 90 may be arranged in a loop shape to surround the active portion 120 on the upper surface 21 of the semiconductor substrate 10. The edge termination structure portion 90 of the present example is disposed along the outer peripheral end 140 of the semiconductor substrate 10. The edge termination structure portion 90 relaxes an electric field concentration on the upper surface side 21 of the semiconductor substrate 10. The edge termination structure portion 90 has, for example, a structure including a guard ring, a field plate, a RESURF, and a combination thereof.

[0120] Fig. 12 is a view showing an exemplary section along cc' in Fig. 11 shows. Fig. 12 shows an example of a structure of the Fig. 1 to Fig. 10 described passage area 106 in cross section. In Fig. 12, the passage area 106 is hatched with diagonal lines. Note that in Fig. 12 only the through region 106 in the drift region 18 is shown and a representation of the through regions 106 in the buffer region 20, collector region 20 and cathode region 82 has been omitted.

[0121] The Fig. The cross section shown in Figure 12 is an XZ plane including the edge termination structure portion 90, the transistor portion 70, and the diode portion 80. Note that although the gate metal layer 50 and the gate runner 48 are disposed between the edge termination structure portion 90 and the transistor portion, an illustration thereof in Fig. 12. The structure of the transistor section 70 is similar to that of the Fig. 6 to Fig. 10 described IGBT.

[0122] The diode section 80 includes the base region 14, the drift region 18, the cathode region 82, and a dummy trench section 30 in the semiconductor substrate 10. The base region 14 and the drift region 18 are identical to the base region 14 and the drift region 18 in the transistor section 70.

[0123] In the diode section 80, the base region 14 and a contact region 15 may be arranged in a region in contact with the upper surface 21 of the semiconductor substrate 10. The contact region 15 is a P+ type region having a higher doping concentration than the base region 14. The diode section 80 of the present example does not include the emitter region 12. Furthermore, the diode section 80 may or may not include the accumulation region 16.

[0124] The dummy trench portion 30 has the same structure as the gate trench portion 40. Note that the dummy trench portion 30 is electrically connected to the emitter electrode 52. Each dummy trench portion 30 is arranged from the top surface 21 of the semiconductor substrate 10 to the drift region 18 and passes through the base region 14. The dummy trench portion 30 may also be arranged in the transistor portion 70. In the transistor portion 70, the dummy trench portion 30 and the gate trench portion 40 are arranged at a predetermined period.

[0125] An intermediate boundary region 190 may be disposed between the transistor section 70 and the diode section 30. The intermediate boundary region 190 is a region where neither an operation of the transistor section 70 nor an operation of the diode section 80 is directly performed. For example, a region of the intermediate boundary region 190 that is in contact with the upper surface 21 may have the same structure as the upper surface side 21 of the diode section 80. Furthermore, in a region of the intermediate boundary region 190 that is not in contact with the lower surface 23 in plan view, the collector region of the transistor section 70 may be arranged in an extended manner. Fig. 12, only an example area of the intermediate boundary area 190 is shown by an arrow. In Fig. 12, the region shown as intermediate boundary region 190 also has the same structure as transistor section 70.

[0126] In the drift region 18 of the diode section 80, a lifetime control region 192 may be arranged closer to the top surface 21 than to the center in the depth direction. The lifetime control region 192 is a region where a recombination center of a charge carrier (an electron or a hole) is located at a higher concentration than in a periphery. The recombination center may be a vacancy, such as a vacancy or divacancy, a dislocation, an interstitial atom, a transition metal, or the like. The lifetime control region 192 may extend from the diode section 80 to the intermediate boundary region 190.

[0127] The edge termination structure portion 90 includes a plurality of guard rings 92, a plurality of field plates 94, and a channel stopper 174. In the edge termination structure portion 90, the collector region 22 may be disposed in a region in contact with the bottom surface 23. Each guard ring 92 may be disposed to encircle the active portion 120 on the top surface 21. The plurality of guard rings 92 may serve to extend the depletion layer generated in the active portion 120 to an outer side of the semiconductor substrate 10. This makes it possible to prevent the concentration of the electric field in the semiconductor substrate 10 and improve the withstand voltage of the semiconductor device 100.

[0128] The guard ring 92 of the present example is a P+ type semiconductor region formed by ion implantation near the top surface 21. A depth of a lower portion of the guard ring 92 may be deeper than depths of lower portions of the gate trench portion 40 and the dummy trench portion 30.

[0129] An upper surface of the guard ring 92 is covered with the interlayer dielectric film 38. The field plate 94 is formed of a conductive material such as metal or polysilicon. The field plate 94 may be formed of the same material as the gate metal layer 50 or the emitter electrode 52. The field plate 94 is disposed on the interlayer dielectric film 38. The field plate 94 is connected to the guard ring 92 through a through-hole in the interlayer dielectric film 38.

[0130] A protective film 182 is disposed on the upper surface 21 of the semiconductor substrate 10. The protective film 182 may cover the edge termination structure portion 90, the gate metal layer 50, a boundary portion 72, a portion of the active portion in contact with the boundary portion 72, and the like. The protective film 182 may be a dielectric film or a thin organic film. The protective film 182 of the present example is polyimide. A plating layer 184 may be disposed on the entire surface of an exposed portion of the emitter electrode 52 where no protective film 182 is formed. A surface of the plating layer 184 may be closer to the upper surface 21 side than the surface of the protective film 182. The plating layer 184 is connected to an electrode terminal of a power module on which the semiconductor device 100 is mounted.

[0131] The channel stopper 174 is disposed so as to be exposed on the upper surface 21 and a side surface of the outer peripheral end 140. The channel stopper 174 is an N-type region whose doping concentration is higher than that of the drift region 18. The channel stopper 174 functions to destroy the depletion layer generated in the active portion 120 at the outer peripheral end 140 of the semiconductor substrate 10.

[0132] The boundary portion 72 may be disposed between the transistor portion 70 and the edge termination structure portion 90. The boundary portion 72 may include the contact region 15, the base region 14, and the dummy trench portion 30 on the upper surface 21 side of the semiconductor substrate 10. The boundary portion 72 may include a P+ type well region 11 whose doping concentration is higher than that of the base region 14. The well region 11 is disposed in contact with the upper surface 21 of the semiconductor substrate 10. The gate metal layer 50 and the gate runner 48 may be disposed above the well region 11. A depth of a lower portion of the well region 11 may be the same as a depth of a lower portion of the guard ring 92. A trench portion at the boundary portion 72 may be formed in the well region 11.In the boundary section 72, the collector region 22 may be arranged in a region that is in contact with the lower surface 23.

[0133] In the present example, the peak of the helium concentration 141 lies between the lower portion of the gate trench portion 40 in the Z-axis direction and the upper surface 21 of the semiconductor substrate 10. In the example of Fig. 12, the peak of the helium concentration 141 is located at a position deeper than the accumulation region 16; however, the peak of the helium concentration 141 may be located at the same depth as the accumulation region 16, at the same depth as the base region 14, and at the same depth as the emitter region 12. Note that the accumulation region 16 may also be located in the diode section 80 as in Fig. 12 can be formed as shown by the dotted line.

[0134] The passage region 106 is formed in the range from the bottom surface 23 of the semiconductor substrate 10 to the helium concentration peak 141. In each drawing, the helium concentration peak 141 and the passage region 106 do not overlap each other; however, the passage region 106 is formed to the depth of the helium concentration peak 141.

[0135] Furthermore, the via region 106 of the present example is arranged in each of the transistor section 80, the diode section 80, the boundary section 72, and the edge termination structure section 90. The depth of the via region 106 may be the same in each of the transistor section 70, the diode section 80, the boundary section 72, and the edge termination structure section 90. The via region may be arranged throughout the semiconductor substrate 10 in plan view. With the present example, the donor concentration can be adjusted over approximately the entire depth direction of the semiconductor substrate 10. The donor concentration can be adjusted over approximately the entire semiconductor substrate 10 in plan view.

[0136] In the present example, a region where the via region 106 is not formed is specifically located in a portion in contact with the upper surface 21 of the edge termination structure portion 90. The region where this via region 106 is not formed is a region where the donor concentration is equal to the base doping concentration Db. The region where the via region 106 is not formed is located closer to the upper surface 21 side than the depth of the peak of the helium concentration 141. That is, the region where this via region 106 is not formed may be a region where the donor concentration is approximately equal to the base doping concentration Db. The region where the doping concentration is the base doping concentration Db is set as the base doping region 180.In the present example, the base doping region 180 is arranged in a portion that is in contact with the upper surface 21 and is lower than the well region 11.

[0137] Fig. 13 is a diagram showing another exemplary arrangement of a passage area 106. The passage area 106 of the present example differs from the passage area 106 in Fig. 12 in width in depth direction. A top view of the structure is identical to that of the passage area 106 in Fig. 12.

[0138] The helium concentration peak 141 of the present example is located between the lower portion of the gate trench portion 40 and the lower surface 23 of the semiconductor substrate 10. The thickness of the semiconductor substrate 10 in the depth direction is set as T1, and a distance between the helium concentration peak 141 and the lower surface 23 of the semiconductor substrate 10 is set as T2. The distance T2 corresponds to a thickness of the via region 106 in the depth direction. The distance T2 may be 40% or more and 60% or less of the thickness T1. That is, the via region 106 may be arranged from the lower surface 23 of the semiconductor substrate 10 to approximately the center of the semiconductor substrate 10 in the depth direction. Note that the distance T1 may be changed accordingly.

[0139] As described above, the base doping region 180 is located closer to the upper surface side 21 than the helium concentration peak 141. The base doping region 180 of the present example is a region from a lower surface of the trench portion to the helium concentration peak 141 and has a depth of approximately T1-T2. In a top plan view, the base doping region 180 of the present example is located on the entire surface of the semiconductor substrate 10.

[0140] Fig. 14 is a diagram showing another exemplary arrangement of the passage area 106. The passage area 106 of the present example differs from the passage area 106 in Fig. 12 in structure in plan view from above. The structure in depth direction can be compared with that of the passage area 106 in Fig. 12 be identical.

[0141] In the present example, the passage region 106 and the peak of the helium concentration 141 are not arranged in at least a partial region of the edge termination structure section 90 in plan view. Fig. 14 shows an example in which the through region 106 and the helium concentration peak 141 are not located in the entire edge termination structure portion 90 in a plan view. In another example, the through region 106 and the helium concentration peak 141 may be located in an end portion of one side in the edge termination structure portion 90 that is close to the active portion 120. That is, the through region 106 and the helium concentration peak 141 are not located in a region that is in contact with the outer peripheral end 140 of the semiconductor substrate 10. In the present example, since the helium concentration peak 141 is not located near the outer peripheral end 140, it is possible to suppress the formation of the defect near the outer peripheral end 140. Therefore, it is possible to suppress an increase in leakage at the outer peripheral end 140.

[0142] That is, the base doping region 180 of the present example is arranged in the region in contact with the outer peripheral end 140 of the semiconductor substrate 10. The base doping region 180 of the present example is arranged in at least a partial region of the edge termination structure portion 90 in plan view. Furthermore, the base doping region 180 may be arranged in the entire edge termination structure portion 90 and boundary portion 72 in plan view.

[0143] Note that a structure of the through region 106 in the boundary section 72 may be the same as that in the edge termination structure section 90, the same as that in the transistor section 70, and the same as that in the diode section 80. Fig. 14 shows an example in which no passage area 106 is arranged in the boundary section 72.

[0144] Fig. Fig. 15 is a diagram showing another exemplary arrangement of the passage area 106. The passage area 106 of the present example has the same structure in the depth direction as that shown in Fig. 13 and has the same structure in plan view as the passage area 106 in Fig. 14. That is, the edge termination structure portion 90 does not have the through region 106. Further, the transistor portion 70 and the diode portion 80 have the through region 106 from the bottom surface 23 of the semiconductor substrate 10 to near the center of the semiconductor substrate 10 in the depth direction.

[0145] The base doping region of the present example is formed from the upper surface 21 to the buffer region 20 in the boundary portion 72 and the edge termination structure portion 90. Furthermore, in the active portion, the base doping region 180 in the drift region 18 is located closer to the upper surface 21 than the helium concentration peak 141. The base doping region 180 of the present example is located closer to the upper surface 21 than the helium concentration peak 141 on the entire surface of the semiconductor substrate in plan view.

[0146] Fig. 16A is a diagram showing another exemplary arrangement of the passage area 106. The present example differs from the examples in Fig. 12 to Fig. 15 in that the passage region 106 and the peak of the helium concentration 141 in plan view are not located in at least a part of the diode section 80. The other structures are identical to those of the examples of Fig. 12 to Fig. 15.

[0147] Fig. 16A shows an example in which the through region 106 and the helium concentration peak 141 are not arranged throughout the diode section 80 in plan view. That is, the base doping region 180 is arranged throughout the entire diode section 80 in plan view. In addition, the base doping region 180 is also arranged throughout the boundary section 72 and the edge termination structure section 90. In another example, the through region 106 and the helium concentration peak 141 may be arranged in an end portion of the diode section 80 that is in contact with the transistor section 70. By differentiating the arrangement of the through region 106 between the transistor section 70 and the diode section 80, the doping concentration distributions of the diode section 80 and the transistor section 70 can be properly differentiable.

[0148] Fig. 16B is a diagram showing another exemplary arrangement of the passage region 106. Fig. Figure 16B shows an arrangement in which the through region 106 and the base doping region 180 in the active section are arranged in an opposite manner to the Fig. 16A. Forming the through region 106 in the diode section 80 suppresses expansion of a space charge region at the time of reverse recovery and suppresses waveform oscillations at the time of reverse recovery. On the other hand, when a short circuit occurs, using the transistor section 70 as the base impurity region 180, for example, allows expansion of the space charge region and injection of holes and suppresses short-circuit failure.

[0149] Fig. 17A is a diagram showing another exemplary arrangement of the passage region 106. The passage region 106 of the present example has the same structure in the depth direction as that shown in Fig. 13 and has the same structure in plan view as the passage area 106 in Fig. 16A. This means that the diode section 80 does not have the through region 106. The transistor section 70 has the through region 106 from the bottom surface 23 of the semiconductor substrate 10 to the vicinity of the center of the semiconductor substrate 10 in the depth direction. Furthermore, in the example of Fig. 17A, the peak of the helium concentration 141 is recessed from the bottom surface of the trench portion to the lower surface side 23, and the base doping region 180 is formed on the entire surface in a top plan view so as to be closer to the upper surface side 21 than the peak of the helium concentration 141.

[0150] Fig. 17B is a diagram showing another exemplary arrangement of the passage area 106. Fig. Figure 17B shows an arrangement in which the through region 106 and the base doping region 180 in the active section are arranged in an opposite manner to the Fig. 17A. In the example of the Fig. 17B also shows the similar effect as in Fig. 16B.

[0151] To Fig. 14 to Fig. 17B, the helium ions are selectively implanted in a top plan view in the second implantation step S1902 described below. For example, it is possible to selectively perform the helium ion implantation by Fig. 14 to Fig. 17B used photoresist film 200 is used.

[0152] In this case, before the second implantation step S1902, the photoresist film 200 is selectively formed with a predetermined thickness on a portion of the lower surface 23 of the semiconductor substrate 10. The thickness of the photoresist film 200 is a thickness that can block the helium ions.

[0153] After the photoresist film 200 is formed, the second implantation step S1902 is performed. In a region where the photoresist film 200 is formed, the helium ions are blocked by the photoresist film 200. Therefore, the helium ions do not penetrate into a region of the semiconductor substrate 10 covered with the photoresist film 200. In a region where the photoresist film 200 is not formed, the helium ions are implanted at the second depth position Z2 depending on an acceleration energy. Note that the photoresist film 200 in each example of the Fig. 14, Fig. 15, Fig. 16A, Fig. 16B, Fig. 17A and Fig. 17B is formed in contact with the lower surface 23 of the semiconductor substrate 10. In a step of forming the photoresist film 200, the collector electrode 54 is not disposed on the lower surface 23.

[0154] Fig. 17C is a diagram illustrating a minimum film thickness M of a photoresist film 200 that prevents helium ions from penetrating into the semiconductor substrate 10. Fig. Figure 17C shows the film thickness M with respect to a range Rp of the helium ions.

[0155] The helium ions of the present example can be implanted into the semiconductor substrate 10 by an accelerator without passing through any absorber other than the photoresist film 200. The range Rp of the helium ions is uniquely determined by the acceleration energy of the accelerator.

[0156] Furthermore, the minimum film thickness M of the photoresist film 200 that can block the helium ions is determined by the acceleration energy of the helium ions. Therefore, the minimum film thickness of the photoresist film 200 can be expressed by the range Rp of the helium ions. Fig. Figure 17C is a graph in which the relationship between the range Rp of helium ions and the film thickness M is measured at three locations and approximated by a straight line. The relationship between the film thickness M (µm) and the range Rp (µm) can be described by the following expression: M=1.76×Rp+12.32.

[0157] It is preferable that the thickness of the photoresist film 200 is greater than or equal to the minimum film thickness M represented by the above expression.

[0158] As another example, the helium ions may be implanted from the accelerator into the semiconductor substrate 10 via an absorber other than the photoresist film 200. The range Rp of the helium ions is determined by the acceleration energy of the accelerator and the thickness of the absorber along an implantation direction of the helium ions.

[0159] Fig. 18A is a diagram showing another exemplary arrangement of the via region 106. In the present example, a width T5 of the via region 106 arranged in the edge termination structure portion 90 is smaller in the depth direction than a width T4 of the via region 106 arranged in the active portion 120 (diode portion 80 in the present example).

[0160] In the diode section 80, the peak of the helium concentration 141 may be located between the lower portion of the dummy gate trench section 30 and the upper surface 21 of the semiconductor substrate 10. In the edge termination structure section 90, the peak of the helium concentration 141 may be located between the guard ring 92 and the lower surface 23 of the semiconductor substrate 10. The width T5 of the via region 106 in the edge termination structure section 90 may be greater than half the width T of the semiconductor substrate 10.

[0161] Furthermore, a width T3 of the through region 106 arranged in the transistor section 70 may be smaller in the depth direction than the width T4 of the through region 106 arranged in the diode section 80. This means that in the transistor section 70, the base doping region 180 is formed deeper than the trench section. This means that the peak of the helium concentration 141 of the transistor section 70 is closer to the lower surface side 23 than the lower surface of the trench section. In the transistor section 70, the peak of the helium concentration 141 may be between the lower section of the gate trench section 40 and the lower surface 23 of the semiconductor substrate 10. The width T3 may be equal to the width T5, greater than the width T5, and smaller than the width T5. The width T3 of the through region 106 in the transistor section 70 may be greater than half the width T of the semiconductor substrate 10.In this way, it is possible to arrange the base region 14, in which a channel is formed, in the transistor section 70 at a distance from the peak of the helium concentration 141. Therefore, it is possible to suppress an increase in defects near the channel.

[0162] The through region 106 in the boundary section 72 may have the same structure as the through region 106 in the edge termination structure section 90, the same structure as the through region 106 in the transistor section 70, and the same structure as the through region 106 in the diode section 80. Furthermore, in the example of the Fig. 18A, the transistor portion 70 may be provided without the via region 106. The diode portion 80 may be provided without the via region 106. The edge termination structure portion 90 may be provided without the via region 106. The boundary portion 72 may be provided without the via region 106.

[0163] Fig. 18B is a diagram showing another exemplary arrangement of the via region 106. In the present example, the width T5 of the via region 106 arranged in the edge termination structure portion 90 is smaller in the depth direction than the width T3 of the via region 106 arranged in the active portion 120 (transistor portion 70 in the present example).

[0164] In the transistor section 70, the peak of the helium concentration 141 may be located between the lower portion of the gate trench section 40 and the upper surface 21 of the semiconductor substrate 10. The structure of the via region 106 and the peak of the helium concentration 141 in the edge termination structure section 90 is similar to that of the example of the Fig. 18A.

[0165] The width T4 of the through region 106 arranged in the diode section 80 may be smaller in the depth direction than the width T3 of the through region 106 arranged in the transistor section 70. This means that in the diode section 80, the base doping region 180 is formed deeper than the trench section. This means that the peak of the helium concentration 141 of the diode section 80 is closer to the bottom surface side 23 than the bottom surface of the trench section. In the diode section 80, the peak of the helium concentration 141 may be located between the bottom portion of the dummy gate trench section 30 and the bottom surface 23 of the semiconductor substrate 10. The width T4 may be equal to the width T5, greater than the width T5, or smaller than the width T5. The width T4 of the through region 106 in the diode section 80 may be greater than half the width T of the semiconductor substrate 10.

[0166] The through region 106 in the boundary section 72 may have the same structure as the through region 106 in the edge termination structure section 90, the same structure as the through region 106 in the transistor section 70, and the same structure as the through region 106 in the diode section 80. Furthermore, in the example of the Fig. 18B, the transistor portion 70 may be provided without the via region 106. The diode portion 80 may be provided without the via region 106. The edge termination structure portion 90 may be provided without the via region 106. The boundary portion 72 may be provided without the via region 106.

[0167] As in Fig. 12 to Fig. 18B, adjusting the structure of the through region 106 allows the distribution of the donor concentration in the transistor section 70, the diode section 80, and the edge termination structure section 90 to be easily adjusted. The structure of the through region 106 is not limited to the Fig. 12 to Fig. 18B shown examples.

[0168] Fig. 19 is a diagram showing steps for forming a via region 106 in a method for manufacturing the semiconductor device 100. In the case of forming the via region 106, in the first implantation step S1900, the hydrogen ions are implanted to the first depth Z1 from the bottom surface 23 of the semiconductor substrate 10. Further, in the second implantation step S1902, the via region 106 is formed by implanting the helium ions to the second depth Z2 from the bottom surface 23 of the semiconductor substrate 10. Either the first implantation step S1900 or the second implantation step S1902 may be performed first.

[0169] Note that if the first implantation step S1900 is performed first, if the heat treatment is performed between the first implantation step S1900 and the second implantation step S1902, it may not be possible to increase the donor concentration in the via region 106. That is, if the heat treatment is performed before forming the via region 106, the hydrogen implanted in the first implantation step S1900 may escape to the outside of the semiconductor substrate 10 without binding to a crystal defect in the via region 106. Therefore, it is preferable not to perform the heat treatment between the first implantation step S1900 and the second implantation step S1902. The heat treatment is a treatment for heating the semiconductor substrate 10 to, for example, 300°C or higher.

[0170] After the first implantation step S1900 and the second implantation step S1902, the diffusion step S1904 is performed. In the diffusion step S1904, the semiconductor substrate 10 is heat-treated, and the hydrogen implanted at the first depth Z1 is diffused into the via region 106. In the diffusion step S1904, the semiconductor substrate 10 may be heated to 300°C or higher. The heating temperature may be 350°C or higher. In the diffusion step S1904, the semiconductor substrate 10 may be heated for 1 hour or longer or for 3 hours or longer.

[0171] By diffusing hydrogen in the diffusion step S1904, the crystal defect and hydrogen in the via region 106 combine to serve as a donor. This makes it possible to increase the donor concentration in the via region 106. In the diffusion step S1904, a minimum value of the donor concentration in the via region 106 is preferably higher than the donor concentration (the base doping concentration) of the semiconductor substrate 10 before the first implantation step S1900 and the second implantation step S1902. This means that the donor concentration is preferably higher than the base doping concentration over the entire via region 106.

[0172] To increase the donor concentration throughout the passage region 106, the hydrogen implanted at the first depth position Z1 is preferably diffused to the vicinity of the second depth position Z2. In the first implantation step S1900, the hydrogen can be sufficiently diffused to the vicinity of the second depth position Z2 by adjusting the dosage of the hydrogen implanted at the second depth position Z1. In the first implantation step S1900, the dosage of hydrogen is preferably set such that the minimum value of the donor concentration in the passage region 106 is higher than the base doping concentration.

[0173] In the first implantation step S1900, the hydrogen ion can be implanted near a helium ion stopping region (the range Rp). The hydrogen ion implantation in the first implantation step can be performed before or after the helium ion implantation in the second implantation step S1902. Local ion implantation damage (disorder) also exists in the vicinity of the helium ion stopping region. Numerous disordered dangling bonds occur there. By implanting hydrogen ions also near the helium ion stopping region in the first implantation step S1900, the hydrogen ion eliminates the disordered dangling bonds, thus reducing the disorder.

[0174] When peaks 24 are formed by a variety of hydrogen donors according to Fig. 9 and the like in the buffer region 20, in addition to the hydrogen ion implantation in the first implantation step S1900, multiple hydrogen ion implantations may also be performed. The multiple hydrogen ion implantations for forming the peaks 24 may be performed in the first implantation step S1900. That is, the first implantation step S1900 may be performed multiple times.

[0175] Fig. 20 to Fig. 26 are diagrams illustrating a method for determining the dosage of hydrogen ions for implantation at the first depth Z1 (referred to as the first dosage). In the first implantation step S1900 of the present example, hydrogen is implanted into the semiconductor substrate 10 according to a diffusion coefficient of hydrogen and at a dosage greater than or equal to a minimum dosage determined by the position (i.e., a distance by which the hydrogen implanted at the first depth position Z1 is to be diffused) of the second depth Z2.

[0176] Fig. Fig. 20 is a diagram illustrating an example of a carrier concentration distribution in the semiconductor substrate 10 after diffusion step S1904. The carrier concentration distribution in Fig. 20 can be detected, for example, by spread resistance profiling. In each of the Fig. 20 to Fig. 26, the bottom surface 23 of the semiconductor substrate 20 is defined as a reference position (0 µm) of a depth (µm). Furthermore, the first depth Z1 is 10 µm or less. The first depth Z1 can be assumed to be 0 µm.

[0177] Fig. 20 shows carrier concentration distributions of five types of semiconductor substrates 10. A first example 161, a second example 162, and a third example 163 are examples in which the hydrogen ions are implanted at the first depth Z1 and the helium ions are implanted at the second depth Z1. A fourth example 164 and a fifth example 165 are examples in which the helium ions are implanted at the second depth Z2 and no hydrogen ions are implanted at the first depth Z1. In each example, the dosage of the helium ions at the second depth Z2 (referred to as the second dosage) is set to 1×10 13 / cm 2Furthermore, the range of the helium ions to the second depth Z2 is set to 100 µm and the acceleration energy to 4.0 MeV. The range of the helium ions can be adjusted by the acceleration energy and can be adjusted by an aluminum absorber or similar.

[0178] In the first example 161, the second example 162, and the third example 163, the acceleration energy of the hydrogen ions to the first depth Z1 is set to 400 keV. In the first example 161, the first dosage is set to 1×10 15 / cm 2 In the second example 162 the first dosage is set to 3×10 14 / cm 2 In the third example 163 the first dosage is set to 1×10 14 / cm 2 set.

[0179] After the hydrogen ions are implanted, the semiconductor substrate 10 of each example is annealed at 370 °C for 5 hours in the same annealing furnace. Note that in the fifth example 165, no annealing is performed. Fig. Figure 20 shows a distribution of the carrier concentration after annealing. Before annealing each example, a crystal defect is formed in the through region 106 (the region from the bottom surface 23 of the semiconductor substrate 10 to the second depth position Z2). Therefore, the carrier concentration in the through region 106 is reduced.

[0180] After annealing, hydrogen bonds with the crystal defect to serve as a donor, so the carrier concentration increases. Note that in the fourth example 164, no hydrogen is implanted in the first depth Z1, so the carrier concentration hardly increases. As shown in the first example 161, the second example 162, and the third example 163, the carrier concentration in the via region 106 increases with increasing the first dosage. Furthermore, with increasing the first dosage, a region whose donor concentration is higher than the base doping concentration extends far away from the first depth Z1. That is, with increasing the first dosage, the diffusion of hydrogen from the first depth Z1 reaches a far-away region.

[0181] If the first dosage is set as Q, a diffusion depth of hydrogen from the first depth Z1 is set as x (x1, x2, x3) (cm), the diffusion coefficient of hydrogen is set as D (cm 2 / s), a diffusion time is set as t, and the base doping concentration of the semiconductor substrate 10 is set as C0 (atoms / cm3), a relationship between them is represented by the following expression (1). Expression (1) represents a value calculated by solving a diffusion equation. When the diffusion equation is solved under a boundary condition that a total amount of hydrogen is constant, the solution has a Gaussian distribution. In the resulting Gaussian distribution, x is described by expression (1) when a concentration C (x, t) corresponds to the base doping concentration C0. [Expression. 1] x=4Dt ln(QC0πDt)

[0182] Using expression (1), the diffusion coefficients D of the first example 161, the second example 162, and the third example 163 can be calculated numerically. The diffusion depth x in each example can be expressed by a profile shape in Fig. 20. For example, a distance from the first depth position Z1 to an initial inflection point in a valley section of the charge carrier concentration can be used for the diffusion depth x. Furthermore, a distance from the first depth position Z1 to a position at which the charge carrier concentration initially falls below the base doping concentration can be used for the diffusion depth x.

[0183] The crystal defects generated during hydrogen implantation at the second depth Z2 include various defects, such as point defects and dislocations. In particular, vacancies, such as vacancies or divacancies, form in the point defects. In this case, the crystal defect concentration exhibits a peak at a position slightly closer to an ion implantation surface (the bottom surface 23 of the semiconductor substrate 10) from the second depth Z2.

[0184] Fig. 21 is a diagram showing a relationship between a diffusion coefficient D of hydrogen and a first dosage Q. In Fig. 21 are each the Fig. 20. As the first dosage Q is increased, the diffusion coefficient D increases. The hydrogen implanted in the first depth Z1 diffuses to the second depth Z2 while the dangling bond is annihilated in the through region 106. A ratio of hydrogen diffusing into the region where the dangling bond is annihilated increases as the first dosage Q increases, which is thus considered as evidence that hydrogen diffusion is facilitated. The value of the diffusion coefficient D varies depending on an experimental condition or the like. An error within at least ±50% can be obtained with respect to the Fig. 21 shown diffusion coefficient D can be allowed. An error within ±100% can also be allowed.

[0185] Fig. Figure 22 is a graph showing a relationship between a diffusion coefficient D of hydrogen and an annealing temperature T. Fig. 22 is a diagram obtained by capturing the Fig. 20 and Fig. 21 for a variety of annealing temperatures T and by performing an Arrhenius diagram. In the present example 161, the first dosage is set to Q=1×10 15 / cm 2 set.

[0186] The diffusion coefficient D is given by D=D0exp (-Ea / k B T). D0 is a constant, Ea is the activation energy and k B is the Boltzmann constant. From the graph in Fig. 22 follows D0=0.19095 (cm 2 / s) and Ea=1.204 (eV). This allows the diffusion coefficient of hydrogen in the semiconductor substrate 10 to be calculated.

[0187] Fig. Figure 23 is a graph showing a relationship between a diffusion depth of hydrogen and a first dosage. In Fig. 23 are in the Fig. 20 shown first example 161, second example 162 and third example 163 are plotted with a black circle.

[0188] As in Fig. As shown in Figure 23, the first dosage for each diffusion depth x can be determined by connecting each plotted point with a straight line. This means that the straight line indicates the first minimum dosage for each diffusion depth x. In the first implantation step S1900, setting the first dosage to a higher value than the straight line allows the donor concentration of the entire through-region 106 to be greater than the base doping concentration. For example, the first dosage Q (ions / cm 2 ) satisfy the following equation when the second depth Z2 is set to the diffusion depth x (µm): Q≥1.6491×1013×e0.061619x.

[0189] As described above, the peak of the crystal defect concentration is located at a slightly shallower position than the second depth Z2 when the helium ions are implanted at the second depth Z2. The horizontal axis in Fig. 23 corresponds to a peak position of the crystal defect concentration. Therefore, in the case of forming the through region 106 with a length X0 corresponding to the horizontal axis in Fig. 23, the helium ions are implanted at the second depth Z2 by the range Rp of the following expression taking into account the compliance ΔRp in the ion implantation. Rp≥X0+ΔRp.

[0190] By setting the peak position of the crystal defect concentration (a position of length X0 from the lower surface 23) at a position closer to the upper surface 21 than the lower portion of the trench portion arranged on the upper surface 21 of the semiconductor substrate 10, it is possible to form the through region 106 in the depth direction approximately in the entire semiconductor substrate 10.

[0191] Note that the minimum dosage can be calculated using the following expression (2), which is obtained by transforming expression (1). [Expression 2] Q=C0πDt ex24Dt

[0192] The diffusion coefficient D is determined by the Fig. 22 described method. In Fig. In Figure 23, the minimum dosage calculated using expression (2) is plotted with a white circle. Note that because the diffusion coefficient D has a quadratic dimension, the diffusion coefficient D can be expressed as a function of the hydrogen diffusion depth x.

[0193] Fig. Figure 24 is a diagram showing a relationship between a diffusion coefficient D of hydrogen and a diffusion depth x. In Fig. 24 are in Fig. 20 shown first example 161, second example 162 and third example 163 are plotted. As in Fig. As shown in Figure 24, the diffusion coefficient D increases with increasing diffusion depth x.

[0194] As the diffusion depth x increases, the distance from the first depth Z1 to the peak of the crystal defect concentration increases. Therefore, the proportion of a region with a relatively small number of crystal defects in the through region 106 increases. When the number of crystal defects is small, the diffusion coefficient is large, so as the diffusion depth x increases, the average diffusion coefficient of the through region 106 also increases.

[0195] In Fig. 20 to Fig. 24 is the second dosage to 1×10 13 / cm 2set. Even if the second dosage is changed, a minimum dosage of the first dosage can be determined in a similar manner. The donor concentration in the passage region 106 can be adjusted by adjusting the second dosage. By adjusting the second dosage, the concentration of crystal defects formed in the passage region 106 can be adjusted. In addition, the annealing temperature is set to 370°C; however, even if the annealing temperature is changed, the minimum dosage can be determined by Expression (2).

[0196] Fig. Figure 25 is a diagram showing a straight line indicating a minimum dosage for each annealing temperature. In the present example, the diffusion coefficient D is constant regardless of the diffusion depth. In the first implantation step S1900, the hydrogen ions only need to be implanted at the first depth Z1 with a dosage greater than that defined by the straight line in Fig. 25 indicated minimum dosage should be implanted.

[0197] Fig. Figure 26 is a diagram showing a relationship between a second dosage and a minimum dosage of the first dosage. In this example, the relationship is shown for each diffusion depth x. In the first implantation step S1900, the hydrogen ions only need to be implanted at the first depth Z1 with a dosage greater than that defined by the straight line in Fig. 26 indicated minimum dosage should be implanted.

[0198] Fig. Figure 27 is a diagram illustrating an example of a first depth Z1. Fig. Figure 27 shows the distribution of the donor concentration, the distribution of the chemical hydrogen concentration, and the distribution of the chemical helium concentration in the depth direction of the semiconductor substrate 10. The distribution of the chemical hydrogen concentration and the distribution of the chemical helium concentration schematically show only the vicinity of the peak. Fig. In Figure 27, a representation of the distribution near the upper surface 21 of the semiconductor substrate 10 (a region where the distance from the lower surface 23 is greater than or equal to 100 µm) is omitted. The carrier concentration distribution in the N-type region of the semiconductor substrate 10 can be used as the donor concentration distribution.

[0199] In the present example, the first depth Z1 of the hydrogen concentration peak 131 is in a range of 5 µm or less from the bottom surface 23 of the semiconductor substrate 10 in the depth direction. In the semiconductor device 100, configurations with other first depths Z1 may be the same as those in any aspect of the Fig. 1 to Fig. 26. The donor concentration distribution of the semiconductor device 100 of the present example is similar to that of the example of Fig. 10.

[0200] Arranging the first depth Z1 near the first surface 23 allows for increasing the distance between the first depth Z1 and the second depth Z2. Therefore, the donor concentration can be adjusted with high accuracy over a larger area of the semiconductor substrate 10. The first depth Z1 can be within a range of 4 µm or less from the bottom surface 23, or within a range of 3 µm.

[0201] To diffuse hydrogen into a larger area, the dosage of hydrogen to be implanted at the first depth Z1 is preferably higher. In the present example, the dosage for implanting hydrogen at the first depth Z1 can be 1×10 15 atoms / cm 2 or more, 1×10 16 atoms / cm 2 or more, 1×10 17 atoms / cm 2 or more or 1×10 18 atoms / cm 2or more. In the first depth Z1, the first peak of the donor concentration 111 may be formed due to the hydrogen donor. The donor concentration of the first peak of the donor concentration may be 1×10 15 / cm 3 or higher and 1×10 16 / cm 3 or higher. The donor concentration of the first peak of donor concentration 111 can be 1×10 17 / cm 3 or less.

[0202] The implantation of hydrogen at the first depth Z1 can be performed using a plasma doping method. In plasma doping, a gas for plasma excitation and a source gas containing hydrogen are introduced into a container containing the semiconductor substrate 10. The excitation gas may contain an inert element such as argon. Phosphine (PH3) or the like can be used as the source gas. By generating plasma using these gases in the container and exposing the lower surface 23 of the semiconductor substrate 10 to the plasma, hydrogen can be easily implanted at a high concentration at a position that is shallow from the lower surface 2. Furthermore, by implanting hydrogen at a shallow position near the lower surface 23 using plasma doping, it is possible to suppress the formation of a crystal defect in the semiconductor substrate 10.Furthermore, due to the small number of crystal defects, the annealing temperature can be reduced and throughput in the manufacturing of the semiconductor device 100 can be improved. Note that a method for implanting hydrogen at the first depth Z1 is not limited to plasma doping.

[0203] The implantation of helium at the second depth Z2 of the helium concentration peak 141 may be performed by a method other than plasma doping. Helium may be implanted at the second depth Z2 by accelerating the helium ion by an electric field or the like. The second depth position Z2 may be spaced from the bottom surface 23 by 80 µm or more in the depth direction. The second depth position Z2 may be spaced from the bottom surface 23 by 90 µm or more, or by 100 µm or more. The distance in the depth direction between the first depth position and the second depth position may be 50% or more of a thickness of the semiconductor substrate 10 in the depth direction, or 65% or more, or 80% or more.

[0204] Fig. Figure 28 shows other examples of the donor concentration distribution, the chemical hydrogen concentration distribution, and the chemical helium concentration distribution in the depth direction of the semiconductor substrate 10. The chemical hydrogen concentration distribution and the chemical helium concentration distribution schematically show only the vicinity of the peak. The first depth Z1 of the present example is the same as that in the example of Fig. 27. Furthermore, the second depth Z2 may be located on the upper surface side 21 of the semiconductor substrate 10. The upper surface side 21 refers to a region between the center and the upper surface 21 in the depth direction of the semiconductor substrate 10.

[0205] In each example of Fig. 27 and Fig. 28, the distribution of the chemical hydrogen concentration may have one or more peaks of hydrogen concentration 194 between the first depth Z1 and the second depth Z2. The peak of hydrogen concentration 194 may be in the Fig. 6 or the like. The peak of the hydrogen concentration 131 may be located in the buffer region 20 and may be located between the buffer region 20 and the lower surface 23.

[0206] Fig. 29 is a diagram showing examples of the distribution of the chemical hydrogen concentration and a distribution of the chemical argon concentration near the peak of the hydrogen concentration 131. In this example, the peak of the hydrogen concentration 131 is a peak corresponding to the hydrogen implanted by plasma doping, and the peak of the hydrogen concentration 194 is a peak corresponding to the hydrogen implanted by a method other than plasma doping.

[0207] When hydrogen is implanted by plasma doping at the first depth position Z1, impurities other than hydrogen can be implanted near the first depth position Z1. For example, when an argon gas is used for plasma excitation, argon can be implanted near the first depth position Z1. Fig. 29 shows a peak of argon concentration 196 at depth position Z0.

[0208] The depth position Z0 can be between the lower surface 23 and the first depth position Z1. Since argon is a heavier element than hydrogen, the peak of argon concentration 196 is likely to form at a shallower position than the peak of hydrogen concentration 131.

[0209] In the present example, no peak of the chemical argon concentration is located between the first depth position Z1 and the second depth position Z2. Since the peak of the hydrogen concentration 194 between the first depth position Z1 and the second depth position Z2 is formed by a method other than plasma doping, no argon is implanted in the vicinity of the peak of the hydrogen concentration 194. The chemical argon concentration between the first depth position Z1 and the second depth position Z2 is smaller than the peak of the argon concentration 196. A maximum value of the chemical argon concentration between the first depth position and the second depth position Z2 may be less than or equal to a maximum value of the chemical argon concentration between the bottom surface 23 and the first depth position Z1.

[0210] Instead of argon, other impurities may be implanted into the semiconductor substrate 10 depending on a composition of the gas used in plasma doping. When a PH3 gas is used for plasma doping, a phosphorus concentration peak may be located between the bottom surface 23 and the first depth position Z1. When a BF3 gas is used for plasma doping, a fluorine concentration peak and a boron concentration peak may be located between the bottom surface 23 and the first depth position Z1. The concentration value of the argon, phosphorus, fluorine, or boron concentration peak may be smaller than the concentration value of the hydrogen concentration peak 131. The concentration value of the argon, phosphorus, fluorine, or boron concentration peak may be half or smaller, or 1 / 10 or smaller than the concentration value of the hydrogen concentration peak 131.

[0211] Fig. 30 is a diagram showing another example of the semiconductor device 100. The semiconductor device 100 of the present example includes a transistor section 70 and a diode section 80 similar to the example shown in Fig. 11. A structure of the transistor section 70 is identical to that of the Fig. 6. The transistor section 70 and the diode section 80 are arranged side by side along the X-axis direction.

[0212] The diode section 80 of the present example has a different structure than the transistor section 70, because the diode section 80 includes the dummy gate trench section 30 instead of the gate trench section 40, the cathode region 82 instead of the cathode region 22, and no emitter region 12. Other structures are similar to that of the transistor section 70.

[0213] The dummy trench portion 30 may have the same structure as the gate trench portion 40. The dummy trench portion 30 includes a dummy dielectric film 32 and a dummy conductive portion 34. The dummy dielectric film 32 and the dummy conductive portion 34 may have the same structure and material as the gate dielectric film 42 and the conductive gate portion 44. Note that the conductive gate portion 44 is electrically connected to the gate electrode, while the dummy conductive portion 34 is electrically connected to the emitter electrode 52. Note that the dummy trench portion 30 may also be disposed in the transistor portion 70. That is, a gate trench portion 40 in the transistor portion 70 may be replaced by the dummy trench portion 30.

[0214] The cathode region 82 is exposed on the bottom surface 23 of the semiconductor substrate 10, similar to the collector region 22. The cathode region 82 is connected to the collector electrode 54 on the bottom surface 23. The cathode region 82 is an N+ type region doped with an N-type impurity, such as phosphorus. The buffer region 20 may be disposed between the cathode region 82 and the drift region 18.

[0215] Furthermore, in the diode section 80, the base region 14 may be exposed on the upper surface 21. The base region 14 of the diode section 80 is electrically connected to the emitter electrode 52. With such a configuration, the diode section 80 functions as a diode.

[0216] In the present example, as well as in the diode section 80, hydrogen is implanted at the first depth position Z1 and helium at the second depth position Z2. Furthermore, a similar through region is formed in the diode section 80 as in the transistor section 70. Each concentration distribution in the transistor section 70 may be the same as one in any Fig. 1 to Fig. 29. The distribution of the chemical hydrogen concentration of the diode section 80 in the depth direction may be the same as the distribution of the chemical hydrogen concentration of the transistor section 70 in the depth direction. The distribution of the chemical helium concentration of the diode section 80 in the depth direction may be the same as the distribution of the chemical helium concentration of the transistor section 70 in the depth direction.

[0217] Fig. 31 shows an example of a carrier concentration distribution, a hydrogen chemical concentration distribution and a boron chemical concentration distribution along a line DD in Fig. 30. Line DD passes through collector region 22 and a portion of buffer region 20 in transistor section 70. Collector region 22 of the present example is formed by implanting boron. Boron is implanted into collector region 22 of the present example in a different step from the step for hydrogen of the hydrogen concentration peak 131. At least a portion of the boron in collector region 22 may be implanted during plasma doping for implanting hydrogen of the hydrogen concentration peak 131.

[0218] In the example of Fig. 7 or the like, the peak of the hydrogen concentration 131 is located in the buffer region 20. The peak of the hydrogen concentration 131 in the present example is located in the cathode region 82 and the collector region 22. The doping concentrations of the cathode region 82 and the collector region 22 are very high, so arranging the peak of the hydrogen concentration 131 in the cathode region 82 and the collector region 22 makes it possible to suppress a change in the shape of the carrier concentration distribution even if a hydrogen donor with a high concentration is generated by the peak of the hydrogen concentration 131. Therefore, it is easy to suppress an influence on the characteristics of the semiconductor device 100.

[0219] The concentration of the hydrogen concentration peak 131 is adjusted so that the hydrogen donor concentration is sufficiently lower than the carrier concentration at the first depth position Z1. The hydrogen activation ratio is approximately 1%. At the first depth position Z1, the chemical hydrogen concentration can be 1% lower than the chemical boron concentration.

[0220] Furthermore, a peak position of the charge carrier concentration distribution in the collector region 22 is closer to the peak of the chemical boron concentration than the peak of the hydrogen concentration 131. In the example of Fig. 31, the peak of the chemical boron concentration lies on the lower surface 23. The peak position of the charge carrier concentration distribution in the collector region 22 can be the same as the peak position of the chemical boron concentration. The peak of the hydrogen concentration 131 can lie between the peak of the charge carrier concentration distribution in the collector region 22 and the buffer region 20. In the present example, the peak position of the charge carrier concentration distribution in the collector region 22 corresponds to the lower surface 23. In the buffer region 20, the depth position of the peak of the hydrogen concentration 131 can correspond to the depth position of the peak 24 of the charge carrier concentration distribution.

[0221] Fig. 32 shows an example of a carrier concentration distribution, a chemical hydrogen concentration distribution and a chemical phosphorus concentration distribution along a line EE in Fig. 30. Line EE passes through cathode region 82 and a portion of buffer region 20 in diode section 80. Cathode region 82 of the present example is formed by implanting phosphorus. Phosphorus is implanted into cathode region 82 in a step different from the step for hydrogen of the peak hydrogen concentration 131. At least a portion of the phosphorus in cathode region 82 may be implanted during plasma doping for implanting hydrogen of the peak hydrogen concentration 131.

[0222] The hydrogen concentration peak 131 in the present example is located in the cathode region 82 and the collector region 22. The concentration of the hydrogen concentration peak 131 is adjusted so that the hydrogen donor concentration is sufficiently lower than the charge carrier concentration at the first depth position Z1. The hydrogen activation ratio is approximately 1%. At the first depth Z1, the chemical hydrogen concentration can be 1% lower than the chemical phosphorus concentration.

[0223] Furthermore, a peak position of the charge carrier concentration distribution in the cathode region 82 is closer to the peak of the chemical phosphorus concentration than the peak of the hydrogen concentration 131. In the example of Fig. 32, the peak of the chemical phosphorus concentration lies on the lower surface 23. The peak position of the charge carrier concentration distribution in the cathode region 82 can be the same as a peak position of the chemical phosphorus concentration. The peak of the hydrogen concentration 131 can lie between the peak of the charge carrier concentration distribution in the cathode region 82 and the buffer region 20. In the present example, the peak position of the charge carrier concentration distribution in the cathode region 82 corresponds to the lower surface 23. In the buffer region 20, the depth position of the peak of the hydrogen concentration 131 can correspond to the depth position of the peak 24 of the charge carrier concentration distribution.

[0224] Fig. 33 is a diagram showing some steps of the method for manufacturing the semiconductor device 100. Before the Fig. 33, the structures of each trench portion, the emitter region 12, the base region 14, the accumulation region 16, and the like on the upper surface side 21 can be formed.

[0225] In the present example, the helium ions are implanted in the implantation step S3300 at the second depth Z2 from the lower surface 23 of the semiconductor substrate 10. The implantation step S3300 can be identical to the second implantation step S1902 in the example of Fig. be 19.

[0226] Furthermore, in implantation step S3302, the hydrogen ions are implanted at the first depth Z1 from the lower surface 23 of the semiconductor substrate 10. In implantation step S3302, the hydrogen ions are implanted by plasma doping. A dosage of hydrogen in implantation step S3302 can be identical to the dosage of hydrogen in the first implantation step S1900 of the example of Fig. 19. Either implantation step S3300 or implantation step S3302 can be executed first.

[0227] After the implantation step S3300 and implantation step S3302, the diffusion step S3304 is carried out. The diffusion step S3304 is similar to the diffusion step S1904 in the example of Fig. 19. By diffusing hydrogen in the diffusion step S3304, the crystal defect and hydrogen in the through region 106 combine to serve as a donor. This makes it possible to increase the donor concentration in the through region 106.

[0228] After the diffusion step S3302, the grinding step S3306 is performed. In the grinding step S3306, the bottom surface 23 of the semiconductor substrate 10 is ground by chemical mechanical polishing (CMP) or a similar method. In the grinding step S3306, a region shallower than the first depth Z1 may be ground, or a region deeper than the first depth Z1 may be ground. This makes it possible to grind a region where hydrogen is distributed in high concentration and to reduce the amount of hydrogen near the bottom surface 23.

[0229] After the grinding step S3306, in the lower surface side structure forming step S3308, structures such as the collector region 22, the cathode region 82, and the buffer region 20 are formed on the lower surface 23. In the lower surface side structure forming step S3308, the vicinity of the lower surface 23 may be laser annealed after the dopant is implanted into the cathode region 82 and the buffer region 20. In this way, it is possible to perform heat treatment at a high temperature locally on the vicinity of the lower surface 23 of the semiconductor substrate 10. Further, a dopant such as hydrogen may be implanted into the buffer region 20 after the laser annealing. After the dopant is implanted into the buffer region 20, the entire semiconductor substrate 10 may be heat-treated in the annealing furnace.

[0230] Fig. 34 is a diagram showing some steps of the method for manufacturing the semiconductor device 100. The method for manufacturing the present example differs from the example of Fig. 33 in that it includes the laser annealing step S3307 instead of the grinding step. The other steps are identical to those of the example of Fig. 33.

[0231] In the laser annealing step S3307, the lower surface 23 of the semiconductor substrate 10 is laser annealed. In the laser annealing step S3307, the vicinity of the first depth Z1 may be irradiated with a laser. In this way, at least a portion of the hydrogen in the vicinity of the first depth Z1 may be released to the outside of the semiconductor substrate 10. This allows the chemical hydrogen concentration in the vicinity of the first depth Z1 to be reduced. In the laser annealing step S3307, the laser may be irradiated such that the peak of the hydrogen concentration 131 is maintained, or the laser may be irradiated such that the peak of the hydrogen concentration 131 is not maintained. Note that even upon laser irradiation, a heavy element such as argon is likely to remain in the semiconductor substrate 10 compared to hydrogen. Therefore, even upon performing the laser annealing step S3307, the Fig. 29 shown concentration peak of the impurity such as argon may be present in the semiconductor substrate 10.

[0232] Furthermore, in laser annealing step S3307, the transistor portion 70 may be irradiated with the laser, and the diode portion 80 may not be irradiated with the laser. Even if the hydrogen donor remains at a high concentration on the bottom surface 23 of the diode portion 80, the influence on the properties is relatively small. In this case, the chemical hydrogen concentration at the first depth Z1 of the diode portion 80 is higher than the chemical hydrogen concentration at the first depth Z1 of the transistor portion 70.

[0233] In the Fig. 19, Fig. 33 and Fig. 34, the implantation of the hydrogen ions at the first depth Z1 and the implantation of the helium ions at the second depth Z2, and the heat treatment may be performed before forming the lower surface side structure and after forming the lower surface side structure and during forming the lower surface side structure.

[0234] Fig. 35 shows an example of a step of implanting hydrogen ions at the first depth Z1 and implanting helium ions at a second depth Z2 in a bottom surface structure forming step. In the present example, the implantation of hydrogen ions at the first depth Z1 and the implantation of helium ions at the second depth Z2 and the heat treatment are performed in the buffer region forming step S3504 to form the buffer region 20.

[0235] The step of forming the lower surface side structure may be performed after the step of forming the upper surface side structure S3500 for the trench portion or the like. The step of forming the lower surface side structure includes the step of forming the collector region S3502 and the step of forming the buffer region S3504. Fig. 35, illustration of steps other than the step of forming the lower surface side structure is omitted. In the present example, in the buffer region forming step S3504, the hydrogen ions are implanted at the first depth Z1 and the helium ions are implanted at the second depth Z2. In step S3504, the semiconductor substrate 10 is heat-treated, and the hydrogen ions and the helium ions are diffused after the hydrogen ions are implanted. After the lower surface side structure forming step S3506, a collector electrode forming step S3506 may be performed.

[0236] Fig. 36 shows another example of the step of implanting hydrogen ions at the first depth Z1 and the step of implanting helium ions at the second depth Z2 in the step of forming the structure on the lower surface side. In this example, the implantation of hydrogen ions at the first depth Z1 and the heat treatment are performed in the step of forming the cathode region S3503. Furthermore, the implantation of helium ions at the second depth Z2 and the heat treatment are performed in the step of forming the buffer region S3506.

[0237] The lower surface side structure forming step may be performed after the upper surface side structure forming step S3500 for the trench portion or the like. The lower surface side structure forming step in the present example includes the step of forming the cathode region S3503 and the step of forming the buffer region S3504. Fig. 36, further steps besides the step of forming the structure of the lower surface side are not shown.

[0238] The semiconductor device 100 of the present example may include the transistor portion 70 and the diode portion 80. In this case, a P-type collector region 22 may be formed in a part of the cathode region 82 by forming the cathode region 82 on the entire lower surface 23 and then selectively implanting a P-type dopant. In the step of forming the cathode region S3503, a raw material gas such as PH3 containing an N-type dopant such as phosphorus may be used. In the step of forming the cathode region S3503, the hydrogen ions are implanted to the first depth Z1 in the entire lower surface 23.

[0239] Furthermore, the cathode region 82 can be formed by selectively forming the collector region 22 on the lower surface 23 and then implanting the N-type dopant and hydrogen ions into the entire lower surface 23. In this case, a P-type dopant with a high concentration can be implanted in advance in the collector region 22 so that the conductivity type is not converted to the N-type. Through such a step, the first depth Z1 is present in the collector region 22 and the cathode region 82.

[0240] Note that when the semiconductor device 100 does not include the transistor portion 70 and includes the diode portion 80, the step of forming the collector region 22 may be omitted. Furthermore, hydrogen implantation may be performed at the second depth Z2 in the step of forming the buffer region 20. After the step of forming the lower surface side structure, a step of forming the collector electrode S3506 may be performed.

[0241] While the embodiments of the present invention have been described, the technical scope of the invention is not limited to the above-described embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above-described embodiments. It is also understood from the scope of the claims that the embodiments added with such modifications or improvements can be included within the technical scope of the invention.

[0242] The operations, procedures, steps, and stages of each process performed by an apparatus, system, program, and method illustrated in the claims, embodiments, or drawings may be performed in any order, as long as the order is not indicated by "previous," "before," or similar terms, and as long as the output of a previous process is not used in a subsequent process. Even if the process flow is described in the claims, embodiments, or drawings by terms such as "first" or "next," this does not necessarily mean that the process must be performed in that order. LIST OF REFERENCE SYMBOLS 10 semiconductor substrate, 11 Sink area, 12 emitter area, 14 basic area, 15 Contact area, 16 accumulation area, 18 Drift area, 20 buffer area, 21 Upper surface, 22 collector area, 23 Lower surface, 24, 25 Peak, 30 dummy trench sections, 32 dielectric dummy film, 34 dummy line sections, 38 dielectric interlayer film, 40 gate ditch section, 42 dielectric gate film, 44 conductive gate section, 48 gate runners, 50 gate metal layer, 52 emitter electrode, 54 collector electrode, 70 transistor section, 72 border section, 80 diode section, 82 cathode area, 90 edge finish structure section, 92 protective ring, 94 field plate, 100 semiconductor devices, 106 passage area, 111 first peak of donor concentration, 112, 122, 132, 142, 172 rising edge, 113, 123, 133, 143, 173 falling edge, 114, 124, 125, 134, 144, 145 inclination, 116 gate connection area, 118 emitter pad, 120 active section, 121 second peak of donor concentration, 131 Peak of hydrogen concentration, 140 outer peripheral end, 141 Peak of helium concentration, 150 flat area, 151 valley, 161 first example, 162 second example, 163 third example, 164 fourth example, 165 fifth example, 171 Peak of vacancy concentration, 174 sewer stoppers, 175 Distribution of vacancy concentration, 180 basic endowment range, 181 non-endowed area, 182 protective film, 184 plating layer, 190 intermediate border area, 192 Lifetime control range, 194 Peak of hydrogen concentration, 196 Peak of argon concentration, 200 photoresist film,

Claims

[1] A semiconductor device (100) comprising: a semiconductor substrate (10) having an upper surface (21) and a lower surface (23), wherein in a depth direction from the lower surface (23) to the upper surface (21) of the semiconductor substrate (10), a hydrogen concentration distribution has a hydrogen concentration peak (131), a helium concentration distribution has a helium concentration peak (141), and a donor concentration distribution has a first donor concentration peak (111) and a second donor concentration peak (121), the peak of the hydrogen concentration (131) and the first peak of the donor concentration (111) lie at a first depth, and the peak of the helium concentration (141) and the second peak of the donor concentration (121) lie at a second depth which is deeper than the first depth with respect to the lower surface (23), each concentration peak has a rising edge in which a concentration value increases from the lower surface (23) to the upper surface (21), and a value obtained by normalizing a gradient of the rising edge of the second peak of the donor concentration (121) with a gradient of the rising edge of the peak of the helium concentration (141) is smaller than a value obtained by normalizing a gradient of the rising edge of the first peak of the donor concentration (111) with a gradient of the rising edge of the peak of the hydrogen concentration (131). [2] A semiconductor device (100) according to claim 1, wherein each concentration peak has a falling edge in which a concentration value decreases from the lower surface (23) to the upper surface (21), and at the peak of the helium concentration (141) the gradient of the rising edge is smaller than a gradient of the falling edge. [3] A semiconductor device (100) according to claim 1, wherein each concentration peak has a falling edge in which a concentration value decreases from the lower surface (23) to the upper surface (21), and at the second peak of the donor concentration (121) the gradient of the rising edge is smaller than a gradient of the falling edge. [4] Semiconductor device (100) according to one of claims 1 to 3, wherein the distribution of the donor concentration between the first depth and the second depth has a flat region (150) where a donor concentration is approximately constant, a length of the flat region (150) in the depth direction is 10% or more of the thickness of the semiconductor substrate (10) in the depth direction. [5] Semiconductor device (100) according to one of claims 1 to 3, wherein the distribution of the donor concentration between the first depth and the second depth has a flat region (150) where a donor concentration is approximately constant, a length of the flat region (150) in the depth direction is 10 µm or more. [6] The semiconductor device (100) according to claim 4 or 5, wherein a minimum value of the donor concentration in the shallow region (150) is higher than a donor concentration of the semiconductor substrate (10). [7] The semiconductor device (100) of claim 6, wherein a minimum value of the donor concentration between the first depth and the second depth is higher than the donor concentration of the semiconductor substrate (10). [8] The semiconductor device (100) according to any one of claims 1 to 7, wherein a value of the concentration of the peak of the helium concentration (141) is smaller than a value of the concentration of the peak of the hydrogen concentration (131). [9] Semiconductor device (100) according to one of claims 1 to 8, further comprising: a drift region (18) of an N type in the semiconductor substrate (10); an emitter region (12) in contact with the upper surface (21) of the semiconductor substrate (10) having a higher donor concentration than a donor concentration of the drift region (18); a P-type base region (14) between the emitter region (12) and the drift region (18); a P-type collector region (22) in contact with the lower surface (23) of the semiconductor substrate (10); and an N-type buffer region (20) between the collector region and the drift region having one or more peaks of donor concentration whose donor concentration is higher than the donor concentration of the drift region, wherein the first peak of the donor concentration (111) is the peak of the donor concentration of the buffer region (20). [10] The semiconductor device (100) of claim 9, further comprising: an accumulation region (16) between the base region (14) and the drift region (18) with one or more peaks of the donor concentration whose donor concentration is higher than the donor concentration of the drift region, wherein the second peak of the donor concentration (121) is the peak of the donor concentration of the accumulation region (16). [11] The semiconductor device (100) according to claim 10, wherein the accumulation region (16) has, in addition to the second peak of the donor concentration (121), the peak of the donor concentration due to a donor other than hydrogen. [12] The semiconductor device (100) of claim 9, further comprising: an accumulation region (16) between the base region (14) and the drift region (18) with one or more peaks of the donor concentration whose donor concentration is higher than the donor concentration of the drift region, wherein the second peak of the donor concentration (121) lies between the buffer region (20) and the accumulation region (16). [13] Semiconductor device (100) according to one of claims 1 to 11, further comprising: a gate trench section (40) arranged on the upper surface (21) of the semiconductor substrate (10), wherein the second peak of the donor concentration (121) lies between a lower portion of the gate trench portion (40) and the upper surface (21) of the semiconductor substrate (10). [14] Semiconductor device (100) according to one of claims 1 to 13, further comprising: an active portion (120) disposed in the semiconductor substrate (10); and an edge termination structure portion (90) surrounding the active portion in plan view of the semiconductor substrate (10), wherein the semiconductor substrate (10) has a passage region (106) through which helium implanted at a position of the peak of the helium concentration (141) has passed, and the through-region (106) in the edge termination structure section is shorter in the depth direction than the through-region (106) in the active section (120), or the through-region (106) is not arranged in the edge termination structure section (90). [15] Semiconductor device (100) according to one of claims 1 to 14, further comprising: a transistor section (70) and a diode section (80) arranged in the semiconductor substrate (10), wherein the semiconductor substrate (10) has a passage region (106) through which helium implanted at a position of the peak of the helium concentration (141) has passed, and the passage region (106) in the diode section (80) is shorter in the depth direction than the passage region (106) in the transistor section (70), or the passage region (106) is not arranged in the diode section (80). [16] Semiconductor device (100) according to one of claims 1 to 14, further comprising: a transistor section (70) and a diode section (80) arranged in the semiconductor substrate (10), wherein the semiconductor substrate (10) has a passage region (106) through which helium implanted at a position of the peak of the helium concentration (141) has passed, and the through region (106) in the transistor section (70) is shorter in the depth direction than the through region (106) in the diode section (80), or the through region (106) is not arranged in the transistor section (70). [17] The semiconductor device (100) according to any one of claims 1 to 15, wherein the first depth is in a range of 5 µm or less from the bottom surface (23) in the depth direction. [18] A semiconductor device (100) according to claim 17, wherein a donor concentration at the peak of the hydrogen concentration (131) is 1×10 15 / cm 3 or higher and 1×10 17 / cm 3 or lower. [19] A semiconductor device (100) comprising: a semiconductor substrate (10) having an upper surface and a lower surface, wherein a distribution of a hydrogen concentration in a depth direction from the lower surface to the upper surface of the semiconductor substrate has a peak of the hydrogen concentration located in a range of 5 µm or less from the lower surface in the depth direction, wherein a distribution of the helium concentration in the depth direction of the semiconductor substrate (10) has a peak of the helium concentration located on an upper surface side with respect to a center of the semiconductor substrate (10) in the depth direction, or a peak of the helium concentration located (i) on the upper surface side and (ii) in a region spaced by 80 µm or more in the depth direction from the lower surface, and wherein a minimum value of a donor concentration between a depth where the peak of the hydrogen concentration is located and a depth where the peak of the helium concentration is located is higher than a donor concentration of the semiconductor substrate (10). [20] The semiconductor device (100) according to claim 19, wherein the semiconductor device (100) has an impurity concentration peak between the lower surface and the hydrogen concentration peak, and an impurity of the impurity concentration peak is argon or fluorine. [21] A method of manufacturing a semiconductor device (100) comprising a semiconductor substrate (10) having an upper surface (21) and a lower surface (23), the method of manufacturing comprising: a first implantation step of implanting hydrogen at a first depth from the lower surface (23) of the semiconductor substrate (10) to form a peak of hydrogen concentration (131); a second implantation step of implanting helium at a second depth from the lower surface (23) of the semiconductor substrate (10), the second depth being deeper than the first depth, to form a peak of helium concentration (141) and a passage region (106) through which the helium has passed; and a diffusion step for heat-treating the semiconductor substrate (10) to diffuse the hydrogen implanted at the first depth in the passage region so that a first peak of the donor concentration (111) is formed at the first depth and a second peak of the donor concentration (121) is formed at the second depth, wherein each concentration peak has a rising edge in which a concentration value increases from the lower surface (23) to the upper surface (21), and a value obtained by normalizing a gradient of the rising edge of the second peak of the donor concentration (121) with a gradient of the rising edge (142) of the peak of the helium concentration (141) is smaller than a value obtained by normalizing a gradient of the rising edge (112) of the first peak of the donor concentration (111) with a gradient of the rising edge (132) of the peak of the hydrogen concentration (131), and in the semiconductor substrate (10) heat-treated in the diffusion step, a dosage of hydrogen in the first implantation step is determined such that a minimum value of a donor concentration in the passage region (106) is higher than a donor concentration of the semiconductor substrate (10) into which the hydrogen is implanted. [22] A manufacturing method according to claim 21, wherein in the first implantation step, hydrogen is implanted according to a diffusion coefficient of hydrogen in the semiconductor substrate (10), and at a dosage greater than or equal to a minimum dosage determined by the second depth. [23] A manufacturing method according to claim 21 or 22, wherein the semiconductor substrate (10) is a silicon substrate, and when the second depth from the bottom surface (23) is set to x (µm), a dosage Q (ions / cm 2 ) of hydrogen in the first implantation step Q≥1.6491×10 13 ×e 0.061619x . [24] A manufacturing method according to any one of claims 21 to 23, wherein in the first implantation step, hydrogen is implanted at the first depth by plasma doping. [25] A manufacturing method according to claim 24, wherein the lower surface (23) of the semiconductor substrate (10) is ground after the plasma doping. [26] A manufacturing method according to claim 24, wherein the lower surface (23) of the semiconductor substrate (10) is laser annealed after the plasma doping.

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