Semiconductor Devices

Abstract

To preferably make it easy to adjust a doping concentration over a wide range in a depth direction of a semiconductor substrate.SOLUTION: There is provided a semiconductor device that comprises a semiconductor substrate which has a top and a reverse surface and also has a bulk donor, wherein a hydrogen chemical concentration distribution in the depth direction of the semiconductor substrate has a first hydrogen concentration peak and a second hydrogen concentration peak arranged more on a reverse surface side of the semiconductor substrate than the first hydrogen concentration peak, and an intermediate donor concentration in an intermediate region between the first hydrogen concentration peak and the second hydrogen concentration peak is lower than both of a top surface-side donor concentration between the first hydrogen concentration peak and the top surface of the semiconductor substrate and a reverse surface-side donor concentration between the second hydrogen concentration peak and the reverse surface of the semiconductor substrate.SELECTED DRAWING: Figure 14

Description

[Technical Field]

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

[0002] Conventionally, a technique has been known in which hydrogen is implanted to a predetermined depth in a semiconductor substrate and diffused, whereby the hydrogen combines with lattice defects formed at the implantation depth and in the diffusion region to become donors, thereby increasing the doping concentration (see, for example, Patent Documents 1 and 2). [Prior art document] [Patent documents] [Patent Document 1] Patent No. 5374883 [Patent Document 2] WO2017 / 47285 Summary of the Invention [Problem to be solved by the invention]

[0003] It is preferable that the doping concentration can be easily adjusted over a wide range in the depth direction of the semiconductor substrate. [Means for solving the problem]

[0004] In order to solve the above problems, in a first aspect of the present invention, In the semiconductor device, a donor concentration distribution, in which the donor concentration of the semiconductor substrate in the depth direction is represented on a logarithmic axis, may include a flat portion extending over a predetermined range including a center position in the depth direction of the semiconductor substrate, a first sloped skirt continuing from an upper surface end of the flat portion, and a second sloped skirt continuing from a lower surface end of the flat portion. In any of the semiconductor devices described above, hydrogen may be present in a range including a first vertex, which is provided at an upper surface end of the first skirt and has a slope of zero, and a second vertex, which is provided at a lower surface end of the second skirt and has a slope of zero.

[0005] In any one of the above semiconductor devices, The donor concentrations at the first vertex and the second vertex may be the same.

[0006] In order to solve the above problems, in a second aspect of the present invention, there is provided a method for manufacturing a semiconductor device having an upper surface and a lower surface, A semiconductor device including a semiconductor substrate containing hydrogen is provided. In the semiconductor device, a donor concentration distribution, in which the donor concentration of the semiconductor substrate in the depth direction is represented on a logarithmic axis, may include a flat portion extending over a predetermined range including a central position in the depth direction of the semiconductor substrate, a first sloped skirt continuing from an upper surface end of the flat portion, and a second sloped skirt continuing from a lower surface end of the flat portion. In any of the semiconductor devices described above, the donor concentrations at a first vertex, which is located at an upper surface end of the first skirt and has a zero slope, and a second vertex, which is located at a lower surface end of the second skirt and has a zero slope, may be the same.

[0007] In any one of the above semiconductor devices, The flat portion may have a bulk donor concentration. In any of the above semiconductor devices, hydrogen may be present in a range including the flat portion. In any of the above semiconductor devices, the predetermined range may be at least 5 μm or more. In any of the above semiconductor devices, a first donor concentration peak on the upper surface side of the first skirt may be higher than a second donor concentration peak on the lower surface side of the second skirt.

[0008] In any one of the above semiconductor devices, The second donor concentration peak on the lower surface side of the second skirt may be higher than the first donor concentration peak on the upper surface side of the first skirt.

[0009] To solve the above problems, a third aspect of the present invention provides a semiconductor device including a semiconductor substrate having an upper surface and a lower surface. In the semiconductor device, a donor concentration distribution, in which the donor concentration of the semiconductor substrate in the depth direction is represented on a logarithmic axis, may include a flat portion extending over a predetermined range of the semiconductor substrate in the depth direction, a first sloped skirt continuing from an end of the flat portion on an upper surface side, and a second sloped skirt continuing from an end of the flat portion on a lower surface side. In any of the above semiconductor devices, a first donor concentration peak on the upper surface side of the first skirt may be higher than a second donor concentration peak on the lower surface side of the second skirt, and hydrogen may be present in a range including the first donor concentration peak and the second donor concentration peak.

[0010] In any one of the above semiconductor devices, The donor concentration distribution may include a third sloped hem that is continuous with the upper surface side of the first vertex, a fourth sloped hem that is continuous with the lower surface side of the second vertex, an upper surface-side donor distribution that is continuous with the upper surface-side end of the third hem, and a lower surface-side donor distribution that is continuous with the lower surface-side end of the fourth hem.

[0011] In any one of the above semiconductor devices, The bottom-side donor distribution may have a higher donor concentration than the top-side donor distribution.

[0012] In any one of the above semiconductor devices, The top-side donor distribution may have a higher donor concentration than the bottom-side donor distribution.

[0013] In any one of the above semiconductor devices, The donor concentration in the flat portion may be higher than the bulk donor concentration. In any of the above semiconductor devices, a distance between the first apex and the second apex in the depth direction may be equal to or less than half of a thickness of the semiconductor substrate in the depth direction.

[0014] The above summary of the invention does not list all of the necessary features of the present invention, and subcombinations of these features may also constitute inventions. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view showing an example of a semiconductor device 100. FIG. [Figure 2] The hydrogen chemical concentration distribution and donor concentration distribution in the depth direction are shown at the position indicated by the line AA in FIG. [Figure 3] FIG. 10 is a diagram illustrating a flat portion 150 in the concentration distribution. [Figure 4] 1. Another example of the hydrogen chemical concentration distribution and the donor concentration distribution in the depth direction is shown at the position indicated by the line AA in FIG. [Figure 5] 1. Another example of the hydrogen chemical concentration distribution and the donor concentration distribution in the depth direction is shown at the position indicated by the line AA in FIG. [Figure 6] 1. Another example of the hydrogen chemical concentration distribution and the donor concentration distribution in the depth direction is shown at the position indicated by the line AA in FIG. [Figure 7] 1. Another example of the hydrogen chemical concentration distribution and the donor concentration distribution in the depth direction is shown at the position indicated by the line AA in FIG. [Figure 8]1. Another example of the hydrogen chemical concentration distribution and the donor concentration distribution in the depth direction is shown at the position indicated by the line AA in FIG. [Figure 9] 1 is a top view showing an example of a semiconductor device 100. FIG. [Figure 10] FIG. 10 is an enlarged view of an area C in FIG. [Figure 11] FIG. 11 is a diagram showing an example of the bb cross section in FIG. [Figure 12] 10 is a diagram showing another example of the passage area 106-1 and the passage area 106-2. FIG. [Figure 13] FIG. 13 is a diagram showing an example of a doping concentration distribution in the DD line in FIG. 12. [Figure 14] 14 is a diagram showing an example of a hydrogen chemical concentration distribution and a donor concentration distribution in regions near the depth position Z1 and the depth position Z2 shown in FIG. 13. FIG. [Figure 15] 15A to 15C are diagrams illustrating an example of a method for manufacturing the semiconductor device 100 described with reference to FIGS. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0017] In this specification, one side in a direction parallel to the depth direction of a semiconductor substrate is referred to as "upper" and the other side as "lower." Of the two main surfaces of a substrate, layer, or other member, one surface is referred to as the upper surface and the other surface is referred to as the lower surface. The directions of "upper" and "lower" are not limited to the direction of gravity or the directions when the semiconductor device is mounted.

[0018] In this specification, technical matters may be explained using the Cartesian coordinate axes of the X-axis, Y-axis, and Z-axis. The Cartesian coordinate axes merely identify the relative positions of components and do not limit a specific direction. For example, the Z-axis does not limit the height direction relative to the ground. Note that the +Z-axis direction and the -Z-axis direction are opposite directions. When the Z-axis direction is written without specifying positive or negative, it means the direction parallel to the +Z-axis and -Z-axis.

[0019] In this specification, orthogonal axes parallel to the top and bottom surfaces of the semiconductor substrate are referred to as the X-axis and Y-axis. Furthermore, an axis perpendicular to the top and bottom surfaces of the semiconductor substrate is referred to as the Z-axis. In this specification, the direction of the Z-axis may be referred to as the depth direction. Furthermore, in this specification, the direction parallel to the top and bottom surfaces of the semiconductor substrate, including the X-axis and Y-axis, may be referred to as the horizontal direction.

[0020] In this specification, when we say "same" or "equal," it may include cases where there is an error due to manufacturing variations, etc. The error is, for example, within 10%.

[0021] In this specification, the conductivity type of a doped region doped with an impurity is described as P-type or N-type. In this specification, the impurity may particularly mean either an N-type donor or a P-type acceptor, and may be referred to as a dopant. In this specification, doping means introducing a donor or an acceptor into a semiconductor substrate to form a semiconductor exhibiting N-type conductivity or a semiconductor exhibiting P-type conductivity.

[0022] In this specification, the doping concentration refers to the concentration of donors or acceptors in a thermal equilibrium state. In this specification, the net doping concentration refers to the net concentration obtained by adding together the donor concentration as the concentration of positive ions and the acceptor concentration as the concentration of negative ions, taking into account the polarity of the charge. As an example, the donor concentration is N D , acceptor concentration N A Then, the net doping concentration at any point is N D -NA In this specification, the net doping concentration may be simply referred to as the doping concentration.

[0023] A donor has the function of supplying electrons to a semiconductor. An acceptor has the function of receiving electrons from a semiconductor. Donors and acceptors are not limited to impurities themselves. For example, a VOH defect, which is a combination of a vacancy (V), oxygen (O), and hydrogen (H) present in a semiconductor, functions as a donor that supplies electrons. In this specification, a VOH defect may be referred to as a hydrogen donor.

[0024] In this specification, when P+ type or N+ type is described, it means that the doping concentration is higher than that of P type or N type, and when P- type or N- type is described, it means that the doping concentration is lower than that of P type or N type. Also, when P++ type or N++ type is described in this specification, it means that the doping concentration is higher than that of P+ type or N+ type.

[0025] As used herein, chemical concentration refers to the atomic density of an impurity measured regardless of its electrical activation state. Chemical concentration can be measured, for example, by secondary ion mass spectrometry (SIMS). The net doping concentration can be measured by voltage-capacitance (CV) measurement. The carrier concentration measured by spreading resistance (SR) measurement may also be used as the net doping concentration. The carrier concentration measured by CV or SR may be used as the value in a thermal equilibrium state. In addition, since the donor concentration in an N-type region is significantly greater than the acceptor concentration, the carrier concentration in that region may also be used as the donor concentration. Similarly, in a P-type region, the carrier concentration in that region may also be used as the acceptor concentration. In this specification, the doping concentration in an N-type region may also be referred to as the donor concentration, and the doping concentration in a P-type region may also be referred to as the acceptor concentration.

[0026] In addition, when the concentration distribution of the donor, acceptor, or net doping has a peak, the peak value may be taken as the donor, acceptor, or net doping concentration in the region. In cases where the donor, acceptor, or net doping concentration is approximately uniform, the average value of the donor, acceptor, or net doping concentration in the region may be taken as the donor, acceptor, or net doping concentration.

[0027] The carrier concentration measured by the SR method may be lower than the donor or acceptor concentration. In the range where current flows when measuring spreading resistance, the carrier mobility of the semiconductor substrate may be lower than the value in the crystalline state. The decrease in carrier mobility occurs when carriers are scattered due to disorder in the crystal structure caused by lattice defects, etc.

[0028] The donor or acceptor concentration calculated from the carrier concentration measured by the CV or SR method may be lower than the chemical concentration of the element that represents the donor or acceptor. As an example, the donor concentration of phosphorus or arsenic, which act as donors in silicon semiconductors, or the acceptor concentration of boron, which acts as an acceptor, is approximately 99% of the chemical concentration. On the other hand, the donor concentration of hydrogen, which acts as a donor in silicon semiconductors, is approximately 0.1% to 10% of the chemical concentration of hydrogen.

[0029] 1 is a cross-sectional view showing an example of a semiconductor device 100. The semiconductor device 100 includes a semiconductor substrate 10. The semiconductor substrate 10 is a substrate formed of a semiconductor material. As an example, the semiconductor substrate 10 is a silicon substrate.

[0030] At least one of a transistor element such as an insulated gate bipolar transistor (IGBT) and a diode element such as a free wheel diode (FWD) is formed on the semiconductor substrate 10. Electrodes of the transistor element and the diode element, and regions provided inside the semiconductor substrate 10 are omitted in Fig. 1. Configuration examples of the transistor element and the diode element will be described later.

[0031] In this example, the semiconductor substrate 10 has N-type bulk donors distributed throughout. The bulk donors are donors formed by dopants uniformly contained within the ingot from which the semiconductor substrate 10 is derived when the ingot is manufactured. In this example, the bulk donors are elements other than hydrogen. Examples of dopants for the bulk donors include, but are not limited to, phosphorus, antimony, arsenic, selenium, or sulfur. In this example, the bulk donor is phosphorus. The bulk donors are also contained within the P-type regions. The semiconductor substrate 10 may be a wafer cut from a semiconductor ingot or a chip obtained by dividing the wafer. The semiconductor ingot may be manufactured by any of the Czochralski method (CZ method), the magnetic field-applied Czochralski method (MCZ method), or the float zone method (FZ method). The ingot in this example is manufactured by the MCZ method. The bulk donor concentration may be the chemical concentration of the bulk donors distributed throughout the semiconductor substrate 10, and may be between 90% and 100% of that chemical concentration.

[0032] The semiconductor substrate 10 has an upper surface 21 and a lower surface 23. The upper surface 21 and the lower surface 23 are the two main surfaces of the semiconductor substrate 10. In this specification, orthogonal axes in planes parallel to the upper surface 21 and the lower surface 23 are defined as the X-axis and the Y-axis, and an axis perpendicular to the upper surface 21 and the lower surface 23 is defined as the Z-axis.

[0033] Hydrogen ions are implanted into the semiconductor substrate 10 from the bottom surface 23 to a depth position Z1. Hydrogen ions are also implanted into the semiconductor substrate 10 from the top surface 21 to a depth position Z2. Implanting hydrogen ions to a predetermined depth position means accelerating the hydrogen ions with an acceleration energy corresponding to the depth position and implanting them. The hydrogen ions are distributed not only at the depth position but also in the vicinity of the depth position. They may also be distributed in a passage region 106 between the implantation surface and the depth position.

[0034] The hydrogen chemical concentration distribution in the depth direction of the semiconductor substrate 10 has a first hydrogen concentration peak 101 at depth position Z1 and a second hydrogen concentration peak 102 at depth position Z2. In Fig. 1, the hydrogen concentration peaks are schematically indicated by crosses. In Fig. 1, depth position Z1 is located between the upper surface 21 and depth position Z2, but depth position Z1 may also be located between the lower surface 23 and depth position Z2.

[0035] In this specification, the region through which the implanted hydrogen ions pass may be referred to as the "passage region." In the passage region 106-1 between the lower surface 23 and the depth position Z1 and the passage region 106-2 between the upper surface 21 and the depth position Z2, vacancy-based lattice defects, such as monovacancies (V) and divacancies (VV), are formed due to the passage of hydrogen. Atoms adjacent to the vacancies have dangling bonds. Lattice defects include interstitial atoms and dislocations, and may also include donors and acceptors in a broad sense. However, in this specification, vacancy-based lattice defects may be referred to as "vacancy-type lattice defects," "vacancy-type defects," or simply "lattice defects." Furthermore, the formation of many lattice defects by hydrogen ion implantation into the semiconductor substrate 10 may severely disrupt the crystallinity of the semiconductor substrate 10. In this specification, this disruption of crystallinity may be referred to as "disorder."

[0036] The semiconductor substrate 10 contains oxygen throughout. This oxygen is introduced intentionally or unintentionally during the production of a semiconductor ingot. Within the semiconductor substrate 10, hydrogen (H), vacancies (V), and oxygen (O) combine to form VOH defects. Heat treatment of the semiconductor substrate 10 also causes hydrogen to diffuse, promoting the formation of VOH defects. VOH defects function as donors that supply electrons. In this specification, VOH defects may be simply referred to as hydrogen donors. In the semiconductor substrate 10 of this example, hydrogen donors are formed in the hydrogen ion passage region 106. The doping concentration of the hydrogen donors is lower than the chemical concentration of hydrogen. If the ratio of the doping concentration of the hydrogen donors to the chemical concentration of hydrogen is defined as the activation rate, the activation rate may be a value of 0.1% to 30%. In this example, the activation rate is 1% to 5%.

[0037] By forming hydrogen donors in the passage region 106 of the semiconductor substrate 10, the donor concentration in the passage region 106 of the semiconductor substrate 10 can be made higher than the bulk donor concentration. Typically, a semiconductor substrate 10 having a predetermined bulk donor concentration must be prepared in accordance with the characteristics of the device to be formed in the semiconductor substrate 10, particularly the rated voltage or breakdown voltage. In contrast, the semiconductor device 100 shown in FIG. 1 allows the donor concentration in a predetermined region of the semiconductor substrate 10 to be adjusted by controlling the hydrogen ion dose and implantation depth. Therefore, the semiconductor device 100 can be manufactured using a semiconductor substrate with a bulk donor concentration that does not correspond to the device characteristics, etc. Although the bulk donor concentration varies relatively widely during the manufacturing of the semiconductor substrate 10, the hydrogen ion dose can be controlled with relatively high precision. Therefore, the concentration of lattice defects generated by implanting hydrogen ions can also be controlled with high precision, allowing the donor concentration in the passage region 106 to be controlled with high precision.

[0038] Furthermore, in the semiconductor device 100, hydrogen ions are implanted from both the upper surface 21 and the lower surface 23. This allows for easy formation of a wide range of the passage region 106. In the example of FIG. 1, the passage region 106-1 and the passage region 106-2 partially overlap, allowing for the passage region 106 to be formed over the entire depth direction. It is also possible to form a passage region over the entire semiconductor substrate by implanting hydrogen ions from either the upper surface 21 or the lower surface 23 so as to penetrate the semiconductor substrate 10. In contrast, according to the semiconductor device 100, since hydrogen ions are implanted from both the upper surface 21 and the lower surface 23, the acceleration energy of the hydrogen ions can be reduced compared to when the hydrogen ions penetrate the semiconductor substrate 10. This allows for less damage to element structures such as gate insulating films.

[0039] FIG. 2 shows the hydrogen chemical concentration distribution and donor concentration distribution in the depth direction at the position indicated by line AA in FIG. 1. The horizontal axis of FIG. 2 indicates the depth position from the lower surface 23, and the vertical axis indicates the hydrogen chemical concentration and donor concentration per unit volume on a logarithmic axis. The donor concentration in FIG. 2 is measured, for example, by the CV method or the SR method. The hydrogen chemical concentration in FIG. 2 is the hydrogen concentration measured, for example, by the SIMS method. In FIG. 2, the hydrogen chemical concentration distribution is shown by a dashed line, and the donor concentration distribution is shown by a solid line. In FIG. 2, the bulk donor concentration is designated Db. The central position in the depth direction of the semiconductor substrate 10 is designated Zc.

[0040] The hydrogen chemical concentration distribution has a first hydrogen concentration peak 101 and a second hydrogen concentration peak 102. The second hydrogen concentration peak 102 is located closer to the lower surface 23 of the semiconductor substrate 10 than the first hydrogen concentration peak 101. In other words, the second hydrogen concentration peak 102 is located between the first hydrogen concentration peak 101 and the lower surface 23.

[0041] The position in the depth direction of the first hydrogen concentration peak 101 is designated as Z1, and the position in the depth direction of the second hydrogen concentration peak 102 is designated as Z2. The position of the concentration peak is the position where the concentration reaches its maximum value.

[0042] The hydrogen chemical concentration distribution has a first upper surface foot S1a, a first lower surface foot S1b, a second upper surface foot S2a, and a second lower surface foot S2b. The first upper surface foot S1a is a portion of the hydrogen chemical concentration distribution where the hydrogen concentration decreases from the first hydrogen concentration peak 101 toward the upper surface 21. The first lower surface foot S1b is a portion of the hydrogen chemical concentration distribution where the hydrogen concentration decreases from the first hydrogen concentration peak 101 toward the lower surface 23. The second upper surface foot S2a is a portion of the hydrogen chemical concentration distribution where the hydrogen concentration decreases from the second hydrogen concentration peak 102 toward the upper surface 21. The second lower surface foot S2b is a portion of the hydrogen chemical concentration distribution where the hydrogen concentration decreases from the second hydrogen concentration peak 102 toward the lower surface 23.

[0043] In this example, the first hydrogen concentration peak 101 is a concentration peak due to hydrogen injected from the lower surface 23 side. When hydrogen is injected from the lower surface 23 side, hydrogen is also distributed in the passage region between the lower surface 23 and the hydrogen injection position. Therefore, the hydrogen concentration decreases more gradually at the first lower surface side skirt S1b than at the first upper surface side skirt S1a. In other words, the slope of the first lower surface side skirt S1b is smaller than the slope of the first upper surface side skirt S1a.

[0044] In this example, the second hydrogen concentration peak 102 is a concentration peak due to hydrogen injected from the upper surface 21. When hydrogen is injected from the upper surface 21, hydrogen is also distributed in the passing region between the upper surface 21 and the hydrogen injection position. Therefore, the hydrogen concentration decreases more gradually in the second upper surface-side skirt S2a than in the second lower surface-side skirt S2b. In other words, the slope of the second upper surface-side skirt S2a is smaller than the slope of the second lower surface-side skirt S2b. In this specification, the slope of the skirt of the concentration distribution may be the slope of the skirt within a predetermined distance from the concentration peak position. The predetermined distance may be 5 μm, 3 μm, or 1 μm. The predetermined distance may be half or one-quarter of the distance between the depth position Z1 and the depth position Z2. Furthermore, the slope of each skirt may be the slope of the skirt from the concentration peak position to the position where the concentration value is half the peak value.

[0045] The hydrogen concentration distribution between the first hydrogen concentration peak 101 and the second hydrogen concentration peak 102 is referred to as the intermediate hydrogen distribution 103. The hydrogen chemical concentration of the intermediate hydrogen distribution 103 is referred to as the intermediate hydrogen concentration Hc. The minimum value of the hydrogen concentration between the depth positions Z1 and Z2 may be used as the intermediate hydrogen concentration Hc, or the average value may also be used. The average concentration of a flat portion in the intermediate hydrogen distribution 103 may also be used as the intermediate hydrogen concentration Hc. A flat portion in a concentration distribution is a region where the concentration is approximately constant and continues for a predetermined length in the depth direction. Details of the flat portion will be described later.

[0046] The hydrogen concentration distribution between first hydrogen concentration peak 101 and upper surface 21 of semiconductor substrate 10 is referred to as upper surface-side hydrogen distribution 104. The hydrogen concentration in upper surface-side hydrogen distribution 104 is referred to as upper surface-side hydrogen concentration Hs1. For upper surface-side hydrogen concentration Hs1, the minimum value of the hydrogen concentration between depth position Z1 and upper surface 21 may be used, or the average value may be used. For upper surface-side hydrogen concentration Hs1, the average concentration of the flat portion of upper surface-side hydrogen distribution 104 that is closest to depth position Z1 may be used.

[0047] The hydrogen concentration distribution between the second hydrogen concentration peak 102 and the bottom surface 23 of the semiconductor substrate 10 is referred to as the bottom surface side hydrogen distribution 105. The hydrogen concentration in the bottom surface side hydrogen distribution 105 is referred to as the bottom surface side hydrogen concentration Hs2. The bottom surface side hydrogen concentration Hs2 may be the minimum value of the hydrogen concentration between the depth position Z2 and the bottom surface 23, or the average value. The bottom surface side hydrogen concentration Hs2 may be the average concentration of the flat portion of the bottom surface side hydrogen distribution 105 that is closest to the depth position Z2.

[0048] The intermediate hydrogen concentration Hc is different from both the top surface side hydrogen concentration Hs1 and the bottom surface side hydrogen concentration Hs2. In this example, both hydrogen implanted from the top surface 21 side and hydrogen implanted from the bottom surface 23 side are present in the region between depth positions Z1 and Z2. Therefore, the intermediate hydrogen concentration Hc in this example is higher than both the top surface side hydrogen concentration Hs1 and the bottom surface side hydrogen concentration Hs2. The intermediate hydrogen concentration Hc may be 1.5 times or more, 2 times or more, or 5 times or more than both the top surface side hydrogen concentration Hs1 and the bottom surface side hydrogen concentration Hs2.

[0049] The donor concentration distribution has a first donor concentration peak 111 and a second donor concentration peak 112. The second donor concentration peak 112 is located closer to the lower surface 23 of the semiconductor substrate 10 than the first donor concentration peak 111. The first donor concentration peak 111 is located at the same depth position Z1 as the first hydrogen concentration peak 101. The second donor concentration peak 112 is located at the same depth position Z2 as the second hydrogen concentration peak 102. Note that even if the half width range of one peak includes the apex of the other peak, the two peaks may be considered to be located at the same depth position.

[0050] The donor concentration distribution has a third upper surface side skirt S3a, a third lower surface side skirt S3b, a fourth upper surface side skirt S4a, and a fourth lower surface side skirt S4b. The third upper surface side skirt S3a is a portion in the donor concentration distribution where the donor concentration decreases from the first donor concentration peak 111 toward the upper surface 21. The third lower surface side skirt S3b is a portion in the donor concentration distribution where the donor concentration decreases from the first donor concentration peak 111 toward the lower surface 23. The fourth upper surface side skirt S4a is a portion in the donor concentration distribution where the donor concentration decreases from the second donor concentration peak 112 toward the upper surface 21. The fourth lower surface side skirt S4b is a portion in the donor concentration distribution where the donor concentration decreases from the second donor concentration peak 112 toward the lower surface 23.

[0051] Each donor concentration peak has a shape similar to the corresponding hydrogen concentration peak. In this example, the donor concentration decreases more gradually at the third lower-side skirt S3b than at the third upper-side skirt S3a. That is, the slope of the third lower-side skirt S3b is smaller than the slope of the third upper-side skirt S3a. Also, the donor concentration decreases more gradually at the fourth upper-side skirt S4a than at the fourth lower-side skirt S4b. That is, the slope of the fourth upper-side skirt S4a is smaller than the slope of the fourth lower-side skirt S4b.

[0052] The donor concentration distribution between the first donor concentration peak 111 and the second donor concentration peak 112 is defined as an intermediate donor distribution 113. The donor concentration in the intermediate donor distribution 113 is defined as an intermediate donor concentration Dc. The minimum value of the donor concentration between the depth positions Z1 and Z2 may be used as the intermediate donor concentration Dc, or the average value may also be used. The average concentration in the flat portion of the intermediate donor distribution 113 may also be used as the intermediate donor concentration Dc.

[0053] The donor concentration distribution between the first donor concentration peak 111 and the upper surface 21 of the semiconductor substrate 10 is referred to as the upper surface-side donor distribution 114. The donor concentration in the upper surface-side donor distribution 114 is referred to as the upper surface-side donor concentration Ds1. The upper surface-side donor concentration Ds1 may be the minimum value of the donor concentration between the depth position Z1 and the upper surface 21, or the average value. The upper surface-side donor concentration Ds1 may be the average concentration of the flat portion of the upper surface-side donor distribution 114 that is closest to the depth position Z1.

[0054] The donor concentration distribution between the second donor concentration peak 112 and the bottom surface 23 of the semiconductor substrate 10 is referred to as bottom-side donor distribution 115. The donor concentration in bottom-side donor distribution 115 is referred to as bottom-side donor concentration Ds2. For bottom-side donor concentration Ds2, the minimum value of the donor concentration between depth position Z2 and the bottom surface 23 may be used, or the average value may be used. For bottom-side donor concentration Ds2, the average concentration of the flat portion of bottom-side donor distribution 115 that is closest to depth position Z2 may be used.

[0055] The intermediate donor concentration Dc is different from both the top-side donor concentration Ds1 and the bottom-side donor concentration Ds2. In this example, the intermediate donor concentration Dc is higher than both the top-side donor concentration Ds1 and the bottom-side donor concentration Ds2. The intermediate donor concentration Dc may be 1.5 times or more, 2 times or more, or 5 times or more of either the top-side donor concentration Ds1 or the bottom-side donor concentration Ds2.

[0056] In this example, the intermediate donor concentration Dc, the top-side donor concentration Ds1, and the bottom-side donor concentration Ds2 are all higher than the bulk donor concentration Db. The intermediate donor concentration Dc is 1×10 13 / cm 3 That's it, 1 x 10 15 / cm 3 The intermediate donor concentration Dc may be 5×10 or less. 13 / cm 3 May be greater than or equal to 1 x 10 14 / cm 3 The intermediate hydrogen concentration Hc may be 10 times or more, 50 times or more, or 100 times or more the intermediate donor concentration Dc.

[0057] 1, by implanting hydrogen ions so that the passage region 106-1 and the passage region 106-2 overlap, the donor concentration can be adjusted throughout the entire depth direction of the semiconductor substrate 10. Furthermore, since hydrogen ions are implanted from both the upper surface 21 and the lower surface 23, damage to insulating films and the like can be reduced. Furthermore, since the depth positions Z1 and Z2 are made different, the peak values of the hydrogen chemical concentration and the donor concentration can be prevented from becoming too large.

[0058] The hydrogen chemical concentration Hp1 of the first hydrogen concentration peak 101 and the hydrogen chemical concentration Hp2 of the second hydrogen concentration peak 102 may be the same or different. The donor concentration Dp1 of the first donor concentration peak 111 and the donor concentration Dp2 of the second donor concentration peak 112 may be the same or different.

[0059] In the example of FIG. 2, depth position Z1 is located on the upper surface 21 side of the semiconductor substrate 10. Depth position Z2 is located on the lower surface 23 side of the semiconductor substrate 10. The upper surface 21 side refers to the region between the center Zc in the depth direction of the semiconductor substrate 10 and the upper surface 21. The lower surface 23 side refers to the region between the center Zc in the depth direction of the semiconductor substrate 10 and the lower surface 23. The center position in the depth direction of the region on the lower surface 23 side of the semiconductor substrate 10 is defined as Zc2. Similarly, the center position in the depth direction of the region on the upper surface 21 side is defined as Zc1. In this example, depth position Z1 is located between depth positions Zc and Zc1. Depth position Z2 is located between depth positions Zc and Zc2. However, the locations of depth positions Z1 and Z2 are not limited to the example of FIG. 2.

[0060] 3 is a diagram illustrating a flat portion 150 in the concentration distribution. Although the flat portion 150 in the donor concentration distribution is illustrated in FIG. 3, a similar definition may be used for the flat portion in the hydrogen chemical concentration distribution. In FIG. 3, a first donor concentration peak 111 and a portion of the top surface side donor distribution 114 are enlarged.

[0061] In the passage region 106 (see FIG. 1 ) through which the hydrogen ions have passed, vacancies (V, VV, etc.) generated by the passage of hydrogen are thought to be distributed at a substantially uniform concentration in the depth direction, except near depth positions Z1 and Z2. Furthermore, oxygen (O) implanted during the manufacture of the semiconductor substrate 10 is also thought to be distributed uniformly in the depth direction. Furthermore, a sufficient amount of hydrogen is present in the passage region 106 because hydrogen at each hydrogen concentration peak diffuses. Therefore, VOH defects formed by vacancies, oxygen, and hydrogen are present substantially uniformly in the passage region 106.

[0062] Therefore, in the passing region 106 other than the vicinity of the depth positions Z1 and Z2, there is a flat portion 150 in which VOH defects functioning as donors are distributed almost uniformly. The donor concentration in the flat portion 150 is almost constant in the depth direction. The donor concentration being almost constant in the depth direction may refer, for example, to a state in which a region in which the difference between the maximum value Dmax and the minimum value Dmin of the donor concentration is within 50% of the maximum value Dmax of the donor concentration is continuous over a predetermined length or more in the depth direction. The difference may be 30% or less, or may be 10% or less, of the maximum value Dmax of the donor concentration in the region.

[0063] Alternatively, the donor concentration distribution value may be within ±50%, ±30%, or ±10% of the average concentration of the donor concentration distribution in a predetermined range in the depth direction. The predetermined length in the depth direction may be 5 μm, 10 μm, or 15 μm. In the example of FIG. 3, if the section defined by two depth positions Zs and Ze is 5 μm or longer and the difference between the maximum donor concentration Dmax and the minimum donor concentration Dmin in the section is within 50% of the maximum donor concentration Dmax, the section is considered to be flat portion 150.

[0064] 3 illustrates the flat portion 150 of the top-side donor distribution 114. The flat portion 150 may be disposed in the bottom-side donor distribution 115, or may be disposed in both the top-side donor distribution 114 and the bottom-side donor distribution 115. The flat portion 150 may also be disposed in the intermediate donor distribution 113.

[0065] 4 shows another example of the hydrogen chemical concentration distribution and donor concentration distribution in the depth direction at the position indicated by line AA in FIG. 1. In this example, depth position Z1 is located between depth position Zc1 and the upper surface 21, and depth position Z2 is located between depth position Zc2 and the lower surface 23. That is, the first hydrogen concentration peak 101 and the first donor concentration peak 111 are located between depth position Zc1 and the upper surface 21, and the second hydrogen concentration peak 102 and the second donor concentration peak 112 are located between depth position Zc2 and the lower surface 23. The other configurations are the same as those of the example shown in FIG. 2.

[0066] According to this example, the intermediate hydrogen distribution 103 and the intermediate donor distribution 113 can be formed widely. That is, a region with a relatively high donor concentration can be formed widely in the depth direction. Furthermore, it is easy to make the first donor concentration peak 111 function as at least a part of the N-type region formed on the upper surface 21 side of the semiconductor substrate 10, and make the second donor concentration peak 112 function as at least a part of the N-type region formed on the lower surface 23 side of the semiconductor substrate 10. The N-type region on the upper surface 21 side is, for example, an accumulation region, which will be described later. The N-type region on the lower surface 23 side is, for example, a buffer region, which will be described later. This makes it possible to form donors with a concentration higher than the bulk donor concentration Db throughout the entire depth direction of the semiconductor substrate 10, while preventing the formation of unnecessary donor concentration peaks.

[0067] 5 shows another example of the hydrogen chemical concentration distribution and donor concentration distribution in the depth direction at the position indicated by line AA in FIG. 1. In this example, depth position Z1 and depth position Z2 are both located on the upper surface 21 side of the semiconductor substrate 10. The other configurations are the same as those in the example shown in FIG. 2.

[0068] According to this example, it is easy to make the first donor concentration peak 111 and the second donor concentration peak 112 function as at least a part of an N-type region formed on the upper surface 21 side of the semiconductor substrate 10. The N-type region on the upper surface 21 side is, for example, an accumulation region, which will be described later.

[0069] 6 shows another example of the hydrogen chemical concentration distribution and donor concentration distribution in the depth direction at the position indicated by line AA in FIG. 1. In this example, depth position Z1 and depth position Z2 are both located on the lower surface 23 side of the semiconductor substrate 10. The other configurations are the same as those in the example shown in FIG.

[0070] According to this example, it is easy to make the first donor concentration peak 111 and the second donor concentration peak 112 function as at least a part of an N-type region formed on the lower surface 23 side of the semiconductor substrate 10. The N-type region on the lower surface 23 side is, for example, a buffer region, which will be described later.

[0071] 7 shows another example of the hydrogen chemical concentration distribution and donor concentration distribution in the depth direction at the position indicated by line AA in FIG. 1. In this example, the concentrations of each peak and each distribution are different. The depth positions of each peak are the same as those of any of the embodiments described in FIGS. 2 to 6.

[0072] In this example, the hydrogen chemical concentration Hp1 of the first hydrogen concentration peak 101 is higher than the hydrogen chemical concentration Hp2 of the second hydrogen concentration peak 102. Similarly, the donor concentration Dp1 of the first donor concentration peak 111 is higher than the donor concentration Dp2 of the second donor concentration peak 112.

[0073] In this example, the dose of hydrogen ions from the bottom surface 23 is higher than the dose of hydrogen ions from the top surface 21. Therefore, the hydrogen chemical concentration in the bottom surface-side hydrogen distribution 105 is higher than the hydrogen chemical concentration in the top surface-side hydrogen distribution 104. For example, the hydrogen chemical concentration at a position distance Zx from the first hydrogen concentration peak 101 in the bottom surface-side hydrogen distribution 105 is higher than the hydrogen chemical concentration at a position distance Zx from the second hydrogen concentration peak 102 in the top surface-side hydrogen distribution 104. The distance Zx may be any distance within the range of each distribution.

[0074] In the donor concentration distribution, the donor concentration of the bottom-side donor distribution 115 is also higher than the donor concentration of the top-side donor distribution 114. For example, in the bottom-side donor distribution 115, the donor concentration at a position that is a distance Zx away from the first donor concentration peak 111 is higher than the donor concentration at a position that is the distance Zx away from the second donor concentration peak 112 in the top-side donor distribution 114.

[0075] 8 shows another example of the hydrogen chemical concentration distribution and donor concentration distribution in the depth direction at the position indicated by line AA in FIG. 1. In this example, the concentrations of each peak and each distribution are different. The depth positions of each peak are the same as those of any of the embodiments described in FIGS. 2 to 6.

[0076] In this example, the hydrogen chemical concentration Hp2 of the second hydrogen concentration peak 102 is higher than the hydrogen chemical concentration Hp1 of the first hydrogen concentration peak 101. Similarly, the donor concentration Dp2 of the second donor concentration peak 112 is higher than the donor concentration Dp1 of the first donor concentration peak 111.

[0077] In this example, the dose of hydrogen ions from the upper surface 21 is higher than the dose of hydrogen ions from the lower surface 23. Therefore, the hydrogen chemical concentration in the upper surface-side hydrogen distribution 104 is higher than the hydrogen chemical concentration in the lower surface-side hydrogen distribution 105. For example, the hydrogen chemical concentration at a position distance Zx from the second hydrogen concentration peak 102 in the upper surface-side hydrogen distribution 104 is higher than the hydrogen chemical concentration at a position distance Zx from the first hydrogen concentration peak 101 in the lower surface-side hydrogen distribution 105.

[0078] In the donor concentration distribution, the donor concentration in the top-side donor distribution 114 is also higher than the donor concentration in the bottom-side donor distribution 115. For example, in the top-side donor distribution 114, the donor concentration at a position that is a distance Zx away from the second donor concentration peak 112 is higher than the donor concentration in the bottom-side donor distribution 115 at a position that is the distance Zx away from the first donor concentration peak 111. As described with reference to FIGS. 2 to 8, the donor concentration distribution inside the semiconductor substrate 10 can be appropriately adjusted by adjusting the positions and concentrations of the respective hydrogen concentration peaks.

[0079] Fig. 9 is a top view showing an example of the semiconductor device 100. Fig. 9 shows the positions of each component projected onto the top surface of the semiconductor substrate 10. Fig. 9 shows only some of the components of the semiconductor device 100, and some components are omitted.

[0080] The semiconductor device 100 includes a semiconductor substrate 10. The semiconductor substrate 10 may have any of the hydrogen chemical concentration distributions and donor concentration distributions described with reference to FIGS. 1 to 8. However, the semiconductor substrate 10 may further have other concentration peaks different from the concentration peaks described with reference to FIGS. 1 to 8. As in the buffer region 20 described below, an N-type region may be formed in the semiconductor substrate 10 by implanting hydrogen ions. In this case, the hydrogen chemical concentration distribution may have a hydrogen concentration peak in addition to the hydrogen concentration peak described with reference to FIGS. 1 to 8. Furthermore, as in the emitter region 12 described below, an N-type region may be formed in the semiconductor substrate 10 by implanting an N-type impurity other than hydrogen, such as phosphorus. In this case, the donor concentration distribution may have a donor concentration peak in addition to the donor concentration peak described with reference to FIGS. 1 to 8.

[0081] The semiconductor substrate 10 has end sides 162 in a top view. In this specification, the term "top view" simply refers to a view from the top surface side of the semiconductor substrate 10. The semiconductor substrate 10 of this example has two pairs of end sides 162 that face each other in a top view. In FIG. 9, the X-axis and Y-axis are parallel to one of the end sides 162. The Z-axis is perpendicular to the top surface of the semiconductor substrate 10.

[0082] An active portion 160 is provided on the semiconductor substrate 10. The active portion 160 is a region through which a main current flows in the depth direction between the upper and lower surfaces of the semiconductor substrate 10 when the semiconductor device 100 is in operation. An emitter electrode is provided above the active portion 160, but is not shown in FIG.

[0083] The active section 160 is provided with at least one of a transistor section 70 including a transistor element such as an IGBT, and a diode section 80 including a diode element such as a free wheel diode (FWD). In the example of Fig. 9, the transistor sections 70 and the diode sections 80 are alternately arranged along a predetermined arrangement direction (the X-axis direction in this example) on the upper surface of the semiconductor substrate 10. In another example, the active section 160 may be provided with only one of the transistor section 70 and the diode section 80.

[0084] In FIG. 9, the region where the transistor section 70 is arranged is marked with the symbol "I," and the region where the diode section 80 is arranged is marked with the symbol "F." In this specification, the direction perpendicular to the arrangement direction in a top view may be referred to as the extension direction (the Y-axis direction in FIG. 9). The transistor section 70 and the diode section 80 may each have a longitudinal direction in the extension direction. In other words, the length of the transistor section 70 in the Y-axis direction is greater than the width in the X-axis direction. Similarly, the length of the diode section 80 in the Y-axis direction is greater than the width in the X-axis direction. The extension direction of the transistor section 70 and the diode section 80 may be the same as the longitudinal direction of each trench section, which will be described later.

[0085] The diode section 80 has an N+ type cathode region in a region in contact with the lower surface of the semiconductor substrate 10. In this specification, the region in which the cathode region is provided is referred to as the diode section 80. In other words, the diode section 80 is a region that overlaps with the cathode region in a top view. A P+ type collector region may be provided in a region of the lower surface of the semiconductor substrate 10 other than the cathode region. In this specification, an extension region 81 in which the diode section 80 is extended in the Y-axis direction to a gate wiring (described later) may also be included in the diode section 80. A collector region is provided on the lower surface of the extension region 81.

[0086] The transistor section 70 has a P+ type collector region in a region in contact with the lower surface of the semiconductor substrate 10. In addition, the transistor section 70 has a gate structure periodically arranged on the upper surface side of the semiconductor substrate 10, the gate structure having an N type emitter region, a P type base region, a gate conductive portion, and a gate insulating film.

[0087] The semiconductor device 100 may have one or more pads above the semiconductor substrate 10. The semiconductor device 100 of this example has a gate pad 164. The semiconductor device 100 may also have pads such as an anode pad, a cathode pad, and a current detection pad. Each pad is disposed near an edge 162. The vicinity of the edge 162 refers to the region between the edge 162 and the emitter electrode in a top view. When the semiconductor device 100 is mounted, each pad may be connected to an external circuit via wiring such as a wire.

[0088] A gate potential is applied to the gate pad 164. The gate pad 164 is electrically connected to a conductive portion of the gate trench portion of the active portion 160. The semiconductor device 100 includes a gate wiring that connects the gate pad 164 and the gate trench portion. In FIG. 9, the gate wiring is hatched with diagonal lines.

[0089] The gate wiring in this example has a peripheral gate wiring 130 and an active side gate wiring 131. The peripheral gate wiring 130 is arranged between the active portion 160 and an edge 162 of the semiconductor substrate 10 in a top view. The peripheral gate wiring 130 in this example surrounds the active portion 160 in a top view. The area surrounded by the peripheral gate wiring 130 in a top view may also be the active portion 160. The peripheral gate wiring 130 is connected to a gate pad 164. The peripheral gate wiring 130 is arranged above the semiconductor substrate 10. The peripheral gate wiring 130 may be a metal wiring containing aluminum or the like.

[0090] The active side gate wiring 131 is provided in the active section 160. By providing the active side gate wiring 131 in the active section 160, it is possible to reduce variations in wiring length from the gate pad 164 for each region of the semiconductor substrate 10.

[0091] The active side gate wiring 131 is connected to the gate trench portion of the active section 160. The active side gate wiring 131 is disposed above the semiconductor substrate 10. The active side gate wiring 131 may be a wiring formed of a semiconductor such as polysilicon doped with impurities.

[0092] The active-side gate wiring 131 may be connected to the peripheral gate wiring 130. In this example, the active-side gate wiring 131 is provided extending in the X-axis direction from one peripheral gate wiring 130 to the other peripheral gate wiring 130 at approximately the center in the Y-axis direction, so as to cross the active section 160. When the active section 160 is divided by the active-side gate wiring 131, the transistor sections 70 and the diode sections 80 may be arranged alternately in the X-axis direction in each divided region.

[0093] The semiconductor device 100 may also include a temperature sensing section (not shown) which is a PN junction diode formed of polysilicon or the like, and a current detecting section (not shown) which simulates the operation of a transistor section provided in the active section 160.

[0094] In the present example, semiconductor device 100 includes an edge termination structure 90 between active section 160 and edge 162 when viewed from above. Edge termination structure 90 in the present example is disposed between peripheral gate wiring 130 and edge 162. Edge termination structure 90 alleviates electric field concentration on the top surface side of semiconductor substrate 10. Edge termination structure 90 may include at least one of a guard ring, a field plate, and a resurf, which are arranged in an annular shape surrounding active section 160.

[0095] FIG. 10 is an enlarged view of region C in FIG. 9. Region C is a region including a transistor section 70, a diode section 80, and an active-side gate wiring 131. The semiconductor device 100 of this example includes a gate trench section 40, a dummy trench section 30, a well region 11, an emitter region 12, a base region 14, and a contact region 15 provided inside the upper surface side of a semiconductor substrate 10. The gate trench section 40 and the dummy trench section 30 are each an example of a trench section. The semiconductor device 100 of this example also includes an emitter electrode 52 and an active-side gate wiring 131 provided above the upper surface of the semiconductor substrate 10. The emitter electrode 52 and the active-side gate wiring 131 are provided separately from each other.

[0096] An interlayer insulating film is provided between the emitter electrode 52 and the active-side gate wiring 131 and the upper surface of the semiconductor substrate 10, but is not shown in Fig. 10. In this example, contact holes 54 are provided in the interlayer insulating film so as to penetrate the interlayer insulating film. In Fig. 10, each contact hole 54 is hatched with diagonal lines.

[0097] The emitter electrode 52 is provided above the gate trench portion 40, the dummy trench portion 30, the well region 11, the emitter region 12, the base region 14, and the contact region 15. The emitter electrode 52 contacts the emitter region 12, the contact region 15, and the base region 14 on the upper surface of the semiconductor substrate 10 through a contact hole 54. The emitter electrode 52 is also connected to a dummy conductive portion in the dummy trench portion 30 through a contact hole provided in the interlayer insulating film. The emitter electrode 52 may be connected to the dummy conductive portion of the dummy trench portion 30 at the tip of the dummy trench portion 30 in the Y-axis direction.

[0098] The active side gate wiring 131 is connected to the gate trench portion 40 through a contact hole provided in the interlayer insulating film. The active side gate wiring 131 may be connected to the gate conductive portion of the gate trench portion 40 at the tip portion 41 of the gate trench portion 40 in the Y-axis direction. The active side gate wiring 131 is not connected to the dummy conductive portion in the dummy trench portion 30.

[0099] The emitter electrode 52 is formed of a material containing metal. FIG. 10 shows the area where the emitter electrode 52 is provided. For example, at least a portion of the emitter electrode 52 is formed of aluminum or an aluminum-silicon alloy, such as a metal alloy such as AlSi or AlSiCu. The emitter electrode 52 may have a barrier metal formed of titanium, a titanium compound, or the like below the region formed of aluminum or the like. Furthermore, the contact hole may have a plug formed by embedding tungsten or the like so as to contact the barrier metal and aluminum or the like.

[0100] The well region 11 is provided so as to overlap with the active-side gate wiring 131. The well region 11 is also provided so as to extend by a predetermined width into an area where it does not overlap with the active-side gate wiring 131. In this example, the well region 11 is provided away from the end of the contact hole 54 in the Y-axis direction toward the active-side gate wiring 131. The well region 11 is a region of a second conductivity type having a doping concentration higher than that of the base region 14. In this example, the base region 14 is P- type, and the well region 11 is P+ type.

[0101] Each of the transistor section 70 and the diode section 80 has a plurality of trench sections arranged in the arrangement direction. In the transistor section 70 of this example, one or more gate trench sections 40 and one or more dummy trench sections 30 are alternately provided along the arrangement direction. In the diode section 80 of this example, a plurality of dummy trench sections 30 are provided along the arrangement direction. In the diode section 80 of this example, no gate trench section 40 is provided.

[0102] The gate trench portion 40 in this example may have two straight line portions 39 (parts of the trench that are linear along the extension direction) that extend along an extension direction perpendicular to the arrangement direction, and a tip portion 41 that connects the two straight line portions 39. The extension direction in FIG. 10 is the Y-axis direction.

[0103] At least a part of the tip portion 41 is preferably curved in a top view. By connecting the ends of the two straight portions 39 in the Y-axis direction with each other by the tip portion 41, electric field concentration at the ends of the straight portions 39 can be alleviated.

[0104] In the transistor section 70, the dummy trench section 30 is provided between each of the linear portions 39 of the gate trench section 40. One or more dummy trench sections 30 may be provided between each of the linear portions 39. The dummy trench section 30 may have a linear shape extending in the extension direction, and may have a linear section 29 and an end portion 31, similar to the gate trench section 40. The semiconductor device 100 shown in FIG. 10 includes both linear dummy trench sections 30 without end portions 31 and dummy trench sections 30 with end portions 31.

[0105] The diffusion depth of the well region 11 may be deeper than the depths of the gate trench portion 40 and the dummy trench portion 30. The ends of the gate trench portion 40 and the dummy trench portion 30 in the Y-axis direction are provided in the well region 11 when viewed from above. In other words, at the ends of each trench portion in the Y-axis direction, the bottom of each trench portion in the depth direction is covered by the well region 11. This makes it possible to alleviate electric field concentration at the bottom of each trench portion.

[0106] A mesa portion is provided between each trench portion in the arrangement direction. The mesa portion refers to a region inside the semiconductor substrate 10 that is sandwiched between the trench portions. As an example, the upper end of the mesa portion is the upper surface of the semiconductor substrate 10. The depth position of the lower end of the mesa portion is the same as the depth position of the lower end of the trench portion. In this example, the mesa portion is provided on the upper surface of the semiconductor substrate 10, extending in the extension direction (Y-axis direction) along the trench. In this example, the transistor portion 70 is provided with a mesa portion 60, and the diode portion 80 is provided with a mesa portion 61. In this specification, the mesa portion simply referred to as a mesa portion refers to both the mesa portion 60 and the mesa portion 61.

[0107] A base region 14 is provided in each mesa portion. Of the base regions 14 exposed on the upper surface of the semiconductor substrate 10 in the mesa portion, the region closest to the active-side gate wiring 131 is referred to as the base region 14-e. While FIG. 10 shows the base region 14-e at one end of each mesa portion in the extension direction, a base region 14-e is also provided at the other end of each mesa portion. Each mesa portion may be provided with at least one of a first-conductivity-type emitter region 12 and a second-conductivity-type contact region 15 in a region sandwiched between the base regions 14-e in a top view. In this example, the emitter region 12 is N+ type, and the contact region 15 is P+ type. The emitter region 12 and the contact region 15 may be provided between the base region 14 and the upper surface of the semiconductor substrate 10 in the depth direction.

[0108] The mesa portion 60 of the transistor portion 70 has an emitter region 12 exposed on the upper surface of the semiconductor substrate 10. The emitter region 12 is provided in contact with the gate trench portion 40. The mesa portion 60 in contact with the gate trench portion 40 may be provided with a contact region 15 exposed on the upper surface of the semiconductor substrate 10.

[0109] The contact regions 15 and the emitter regions 12 in the mesa portion 60 are each provided from one trench portion to the other trench portion in the X-axis direction. As an example, the contact regions 15 and the emitter regions 12 in the mesa portion 60 are alternately arranged along the extension direction of the trench portions (the Y-axis direction).

[0110] In another example, the contact region 15 and the emitter region 12 of the mesa portion 60 may be provided in a stripe shape along the extension direction (Y-axis direction) of the trench portion. For example, the emitter region 12 is provided in a region in contact with the trench portion, and the contact region 15 is provided in a region sandwiched between the emitter regions 12.

[0111] The mesa portion 61 of the diode portion 80 does not have an emitter region 12. A base region 14 and a contact region 15 may be provided on the upper surface of the mesa portion 61. In the region sandwiched between the base regions 14-e on the upper surface of the mesa portion 61, a contact region 15 may be provided in contact with each of the base regions 14-e. In the region sandwiched between the contact regions 15 on the upper surface of the mesa portion 61, a base region 14 may be provided. The base region 14 may be disposed in the entire region sandwiched between the contact regions 15.

[0112] A contact hole 54 is provided above each mesa portion. The contact hole 54 is arranged in a region sandwiched between the base regions 14-e. In this example, the contact holes 54 are provided above the contact region 15, the base region 14, and the emitter region 12. The contact holes 54 are not provided in regions corresponding to the base region 14-e and the well region 11. The contact hole 54 may be arranged in the center of the arrangement direction (X-axis direction) of the mesa portions 60.

[0113] In the diode section 80, an N+ type cathode region 82 is provided in a region adjacent to the lower surface of the semiconductor substrate 10. A P+ type collector region 22 may be provided in a region of the lower surface of the semiconductor substrate 10 where the cathode region 82 is not provided. The cathode region 82 and the collector region 22 are provided between the lower surface 23 of the semiconductor substrate 10 and the buffer region 20. In FIG. 10, the boundary between the cathode region 82 and the collector region 22 is indicated by a dotted line.

[0114] The cathode region 82 is disposed away from the well region 11 in the Y-axis direction. This ensures a distance between the cathode region 82 and a P-type region (well region 11) that has a relatively high doping concentration and is formed deep, thereby improving the breakdown voltage. In this example, the end of the cathode region 82 in the Y-axis direction is disposed farther from the well region 11 than the end of the contact hole 54 in the Y-axis direction. In another example, the end of the cathode region 82 in the Y-axis direction may be disposed between the well region 11 and the contact hole 54.

[0115] Fig. 11 is a diagram showing an example of the bb cross section in Fig. 10. The bb cross section is an XZ plane that passes through the emitter region 12 and the cathode region 82. In this cross section, the semiconductor device 100 of this example has a semiconductor substrate 10, an interlayer insulating film 38, an emitter electrode 52, and a collector electrode 24.

[0116] The interlayer insulating film 38 is provided on the upper surface of the semiconductor substrate 10. The interlayer insulating film 38 is a film including at least one layer of an insulating film such as silicate glass doped with impurities such as boron or phosphorus, a thermal oxide film, and other insulating films. The interlayer insulating film 38 is provided with the contact hole 54 described with reference to FIG. 10.

[0117] The emitter electrode 52 is provided above the interlayer insulating film 38. The emitter electrode 52 passes through a contact hole 54 in the interlayer insulating film 38 and contacts the upper surface 21 of the semiconductor substrate 10. The collector electrode 24 is provided on the lower surface 23 of the semiconductor substrate 10. The emitter electrode 52 and the collector electrode 24 are made of a metal material such as aluminum. In this specification, the direction connecting the emitter electrode 52 and the collector electrode 24 (the Z-axis direction) is referred to as the depth direction.

[0118] The semiconductor substrate 10 has an N-type or N-type drift region 18. The drift region 18 is provided in each of the transistor section 70 and the diode section 80.

[0119] In the mesa portion 60 of the transistor section 70, an N+ type emitter region 12 and a P- type base region 14 are provided in this order from the upper surface 21 side of the semiconductor substrate 10. A drift region 18 is provided below the base region 14. An N+ type accumulation region 16 may be provided in the mesa portion 60. The accumulation region 16 is disposed between the base region 14 and the drift region 18.

[0120] The emitter region 12 is exposed on the upper surface 21 of the semiconductor substrate 10 and is provided in contact with the gate trench portion 40. The emitter region 12 may be in contact with the trench portions on both sides of the mesa portion 60. The emitter region 12 has a higher doping concentration than the drift region 18.

[0121] The base region 14 is provided below the emitter region 12. In this example, the base region 14 is provided in contact with the emitter region 12. The base region 14 may be in contact with the trench portions on both sides of the mesa portion 60.

[0122] The accumulation region 16 is provided below the base region 14. The accumulation region 16 is an N+ type region with a higher doping concentration than the drift region 18. By providing the high-concentration accumulation region 16 between the drift region 18 and the base region 14, the carrier injection enhancement effect (IE effect) can be enhanced and the on-voltage can be reduced. The accumulation region 16 may be provided so as to cover the entire lower surface of the base region 14 in each mesa portion 60.

[0123] A P-type base region 14 is provided in the mesa portion 61 of the diode section 80 in contact with the upper surface 21 of the semiconductor substrate 10. A drift region 18 is provided below the base region 14. An accumulation region 16 may be provided below the base region 14 in the mesa portion 61.

[0124] In each of the transistor section 70 and the diode section 80, an N+ type buffer region 20 may be provided below the drift region 18. The doping concentration of the buffer region 20 is higher than that of the drift region 18. The buffer region 20 has a concentration peak 25 with a higher doping concentration than the drift region 18. The doping concentration of the concentration peak 25 refers to the doping concentration at the apex of the concentration peak 25. The doping concentration of the drift region 18 may be the average value of the doping concentration in a region where the doping concentration distribution is approximately flat. The doping concentration of the drift region 18 may be the average value of the doping concentration of the flat portion 150 described in FIG. 3.

[0125] The buffer region 20 of this example has three or more concentration peaks 25 in the depth direction (Z-axis direction) of the semiconductor substrate 10. The concentration peaks 25 of the buffer region 20 may be located at the same depth as the concentration peaks of hydrogen (protons) or phosphorus, for example. The buffer region 20 may function as a field stop layer that prevents a depletion layer extending from the lower end of the base region 14 from reaching the P+ type collector region 22 and the N+ type cathode region 82.

[0126] In the transistor section 70, a P+ type collector region 22 is provided below the buffer region 20. The acceptor concentration of the collector region 22 is higher than the acceptor concentration of the base region 14. The collector region 22 may contain the same acceptor as the base region 14, or may contain a different acceptor. The acceptor of the collector region 22 is, for example, boron.

[0127] In the diode section 80, an N+ type cathode region 82 is provided below the buffer region 20. The donor concentration of the cathode region 82 is higher than that of the drift region 18. The donor of the cathode region 82 is, for example, hydrogen or phosphorus. Note that the elements that serve as the donor and acceptor in each region are not limited to the above-mentioned examples. The collector region 22 and the cathode region 82 are exposed on the lower surface 23 of the semiconductor substrate 10 and connected to the collector electrode 24. The collector electrode 24 may be in contact with the entire lower surface 23 of the semiconductor substrate 10. The emitter electrode 52 and the collector electrode 24 are formed of a metal material such as aluminum.

[0128] One or more gate trenches 40 and one or more dummy trenches 30 are provided on the top surface 21 of the semiconductor substrate 10. Each trench extends from the top surface 21 of the semiconductor substrate 10 through the base region 14 to reach the drift region 18. In regions where at least one of the emitter region 12, the contact region 15, and the accumulation region 16 is provided, each trench also extends through these doped regions to reach the drift region 18. The trenches extending through the doped regions do not necessarily mean that the trenches are formed after the doped regions are formed. The trenches also include those in which the doped regions are formed between the trenches after the trenches are formed.

[0129] As described above, the transistor section 70 is provided with the gate trench section 40 and the dummy trench section 30. The diode section 80 is provided with the dummy trench section 30, but is not provided with the gate trench section 40. In this example, the boundary between the diode section 80 and the transistor section 70 in the X-axis direction is the boundary between the cathode region 82 and the collector region 22.

[0130] The gate trench portion 40 has a gate trench provided on the upper surface 21 of the semiconductor substrate 10, a gate insulating film 42, and a gate conductive portion 44. The gate insulating film 42 is provided to cover the inner wall of the gate trench. The gate insulating film 42 may be formed by oxidizing or nitriding the semiconductor on the inner wall of the gate trench. The gate conductive portion 44 is provided inside the gate trench and on the inner side of the gate insulating film 42. In other words, the gate insulating film 42 insulates the gate conductive portion 44 from the semiconductor substrate 10. The gate conductive portion 44 is formed of a conductive material such as polysilicon.

[0131] The gate conductive portion 44 may be provided to be longer in the depth direction than the base region 14. The gate trench portion 40 in this cross section is covered with an interlayer insulating film 38 on the upper surface 21 of the semiconductor substrate 10. The gate conductive portion 44 is electrically connected to the gate wiring. When a predetermined gate voltage is applied to the gate conductive portion 44, a channel is formed by an electron inversion layer in the surface layer of the interface of the base region 14 that contacts the gate trench portion 40.

[0132] The dummy trench portion 30 may have the same structure as the gate trench portion 40 in the cross section. The dummy trench portion 30 includes a dummy trench, a dummy insulating film 32, and a dummy conductive portion 34 provided on the upper surface 21 of the semiconductor substrate 10. The dummy conductive portion 34 is electrically connected to the emitter electrode 52. The dummy insulating film 32 covers the inner wall of the dummy trench. The dummy conductive portion 34 is provided inside the dummy trench and is provided further inward than the dummy insulating film 32. The dummy insulating film 32 insulates the dummy conductive portion 34 from the semiconductor substrate 10. The dummy conductive portion 34 may be formed of the same material as the gate conductive portion 44. For example, the dummy conductive portion 34 is formed of a conductive material such as polysilicon. The dummy conductive portion 34 may have the same length in the depth direction as the gate conductive portion 44.

[0133] The gate trench portion 40 and the dummy trench portion 30 in this example are covered with an interlayer insulating film 38 on the upper surface 21 of the semiconductor substrate 10. The bottoms of the dummy trench portion 30 and the gate trench portion 40 may have a downwardly convex curved shape (a curved shape in cross section).

[0134] As described in Figures 1 to 8, the semiconductor substrate 10 has a first hydrogen concentration peak 101 and a first donor concentration peak 111 at depth position Z1, and a second hydrogen concentration peak 102 and a second donor concentration peak 112 at depth position Z2.

[0135] Depth position Z1 may be located within the accumulation region 16, may be located between the bottom end position Zt of the trench portion and the top end position Zf of the buffer region 20, or may be located within the buffer region 20. Similarly, depth position Z2 may be located within the accumulation region 16, may be located between the bottom end position Zt of the trench portion and the top end position Zf of the buffer region 20, or may be located within the buffer region 20.

[0136] 12 is a diagram showing another example of the passage region 106-1 and the passage region 106-2. In this example, the passage region 106-1 and the passage region 106-2 do not overlap. In other words, the passage region 106-1 and the passage region 106-2 are arranged apart in the depth direction.

[0137] In this example, hydrogen ions are implanted from the upper surface 21 side of the semiconductor substrate 10 to a depth position Z1 in the semiconductor substrate 10. Furthermore, hydrogen ions are implanted from the lower surface 23 side of the semiconductor substrate 10 to a depth position Z2 that is closer to the lower surface 23 than the depth position Z1. In this example, the depth positions Z1 and Z2 are located between the lower end position Zt of the trench portion and the upper end position Zf of the buffer region 20.

[0138] Fig. 13 is a diagram showing an example of the doping concentration distribution in the DD line in Fig. 12. In this example, in addition to the donor concentration distribution due to VOH defects, the doping concentration distribution in each region is shown.

[0139] Bulk donors such as phosphorus are distributed throughout the semiconductor substrate 10. The emitter region 12 contains an N-type dopant such as phosphorus. The base region 14 contains a P-type dopant such as boron. The accumulation region 16 contains an N-type dopant such as phosphorus or hydrogen.

[0140] The drift region 18 contains hydrogen in at least a portion thereof. A first donor concentration peak 111 and a second donor concentration peak 112 are located in the drift region 18.

[0141] In this example, the buffer region 20 has a plurality of concentration peaks 25-1, 25-2, 25-3, and 25-4 in its doping concentration distribution. Each concentration peak 25 is formed by implanting hydrogen ions. The collector region 22 contains a P-type dopant such as boron.

[0142] 14 is a diagram showing an example of the hydrogen chemical concentration distribution and the donor concentration distribution in the regions near the depth positions Z1 and Z2 shown in FIG. 13. In this example, hydrogen does not pass through the region between the depth positions Z1 and Z2. Therefore, VOH defects are not formed in this region. On the other hand, VOH defects are formed in the region between the depth position Z1 and the upper surface 21 and the region between the depth position Z2 and the lower surface 23.

[0143] In this example, the intermediate donor concentration Dc in the intermediate donor distribution 113 between the depth positions Z1 and Z2 is lower than both the top-side donor concentration Ds1 in the top-side donor distribution 114 and the bottom-side donor concentration Ds2 in the bottom-side donor distribution 115. The intermediate donor concentration Dc may be the same as the bulk donor concentration Db. Both the top-side donor concentration Ds1 and the bottom-side donor concentration Ds2 are higher than the bulk donor concentration Db. The top-side donor concentration Ds1 and the bottom-side donor concentration Ds2 may be two or more times, three or more times, or five or more times the intermediate donor concentration Dc.

[0144] In this example, the depth position Z1 and the depth position Z2 may be disposed in the same manner as in the examples shown in FIGS. 2 to 8 . However, it is preferable that the depth positions Z1 and Z2 are disposed between the depth positions Zt and Zf. For example, as shown in FIG. 5 , both the first hydrogen concentration peak 101 and the second hydrogen concentration peak 102 may be disposed on the upper surface 21 side of the semiconductor substrate 10. This allows a region of the intermediate donor distribution 113, which has a relatively low donor concentration, to be disposed on the upper surface 21 side of the semiconductor substrate 10. Depending on the structure of the semiconductor device 100, an electric field may be easily concentrated on the upper surface 21 side. Even in such a case, by disposing the intermediate donor distribution 113 on the upper surface 21 side, the electric field concentration on the upper surface 21 side can be alleviated.

[0145] 1 to 14, the distance in the depth direction between depth positions Z1 and Z2 may be equal to or less than ½ of the thickness in the depth direction of semiconductor substrate 10. The distance may be equal to or less than ¼ or 1 / 10 of the thickness. In the example of Fig. 13, by reducing the distance, the donor concentration of semiconductor substrate 10 can be adjusted over a wide range in the depth direction.

[0146] 1 to 14. The manufacturing method includes a hydrogen implantation step including an upper surface implantation step of implanting hydrogen ions to a first depth position from the upper surface 21 of the semiconductor substrate 10, and a lower surface implantation step of implanting hydrogen ions to a second depth position from the lower surface 23 of the semiconductor substrate, the second depth position being different from the first depth position. In FIG. 15, the lower surface implantation step is step S1408. In FIG. 15, the upper surface implantation step is any one of steps S1412, S1413, S1414, and S1415. The first depth position is one of depth positions Z1 and Z2, and the second depth position is the other of depth positions Z1 and Z2.

[0147] In this example, in step S1400, an upper surface structure of the semiconductor device 100 is formed. The upper surface structure refers to a structure provided on the upper surface 21 side of the semiconductor substrate 10, and includes, for example, a trench portion, an emitter region 12, a base region 14, an accumulation region 16, an interlayer insulating film 38, an emitter electrode 52, a gate wiring, etc.

[0148] Next, in step S1402, the lower surface 23 side of the semiconductor substrate 10 is ground to adjust the thickness of the semiconductor substrate 10. Next, in step S1412, hydrogen ions may be implanted from the upper surface 21 side of the semiconductor substrate 10. However, the implantation of hydrogen ions from the upper surface 21 side may be performed at other timings, which will be described later. In step S1412, hydrogen ions are implanted at one of depth positions Z1 and Z2. Depth position Z2 may be located between depth position Z1 and the lower surface 23.

[0149] 1 to 8, in step S1412, hydrogen ions are implanted to a depth position Z2 from the upper surface 21. In addition, in the examples of Figures 12 to 14, hydrogen ions are implanted to a depth position Z1 from the upper surface 21 in step S1412.

[0150] Next, in step S1404, P-type dopants are implanted into the collector region 22. In step S1404, N-type dopants may also be implanted into the cathode region 82. Next, in step S1413, hydrogen ions may be implanted from the top surface 21 side of the semiconductor substrate 10. Step S1413 is similar to step S1412. If step S1413 is performed, step S1412 may not be performed.

[0151] Next, in step S1406, a laser is irradiated onto the region near the lower surface 23, thereby forming the cathode region 82 and the collector region 22. If step S1412 or step S1413 is performed before step S1406, the laser annealing in step S1406 can repair excess defects formed by the hydrogen ion implantation. In particular, if hydrogen ions are implanted from the upper surface 21 into the region toward the lower surface 23 in step S1412 or step S1413, the acceleration energy of the hydrogen ions becomes high, making it easier for excess defects to be formed. In this case, step S1406 can repair excess defects near the lower surface 23.

[0152] Next, in step S1414, hydrogen ions may be implanted from the upper surface 21 side of the semiconductor substrate 10. Step S1414 is similar to step S1412. When step S1414 is performed, steps S1412 and S1413 do not need to be performed. Next, in step S1408, hydrogen ions are implanted from the lower surface 23 side. In step S1408, hydrogen ions are implanted at one of depth positions Z1 and Z2 from the lower surface 23. As described above, the depth position at which hydrogen ions are implanted from the upper surface 21 side is different from the depth position at which hydrogen ions are implanted from the lower surface 23 side.

[0153] 1 to 8, in step S1408, hydrogen ions are implanted from the lower surface 23 to a depth position Z1. In the examples of Figures 12 to 14, hydrogen ions are implanted from the lower surface 23 to a depth position Z2 in step S1408.

[0154] Next, in step S1415, hydrogen ions may be implanted from the upper surface 21 side of the semiconductor substrate 10. Step S1415 is similar to step S1412. When step S1415 is performed, steps S1412, S1413, and S1414 do not need to be performed. By performing step S1414 or S1415 after step S1406, it is possible to prevent vacancy defects formed in step S1414 or S1415 near the lower surface 23 from being excessively restored by laser annealing. This allows the donor concentration of the semiconductor substrate 10 to be accurately controlled.

[0155] Next, in step S1410, the semiconductor substrate 10 is heat-treated. In step S1410, the entire semiconductor substrate 10 may be heat-treated in an annealing furnace. This causes hydrogen to diffuse and promotes the formation of VOH defects. The heat treatment temperature in step S1410 may be 350°C or higher and 380°C or lower. The upper limit of the heat treatment temperature may be 360°C or lower. After step S1410, structures such as the collector electrode 24 are formed. This completes the semiconductor device 100.

[0156] The heat treatment step S1410 may be performed twice: once after hydrogen is injected from one of the upper surface 21 and the lower surface 23, and once after hydrogen is injected from the other of the upper surface 21 and the lower surface 23. The step of injecting hydrogen from the upper surface 21 and the step of injecting hydrogen from the lower surface 23 may be performed with a higher hydrogen acceleration energy first. In this case, a heat treatment may be performed after each hydrogen injection. More specifically, the temperature of the first heat treatment step after the hydrogen injection step with a higher acceleration energy may be higher than the temperature of the second heat treatment step after the hydrogen injection step with a lower acceleration energy. The temperature of the first heat treatment step may be 360°C or higher and 380°C or lower. The temperature of the second heat treatment step may be lower than 360°C. Since vacancy defects are more likely to form with a higher acceleration energy, increasing the heat treatment temperature of the first heat treatment step can efficiently form VOH defects.

[0157] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0158] It should be noted that the execution order of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and that the processes can be performed in any order unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, this does not mean that the processes must be performed in this order. [Explanation of symbols]

[0159] 10 semiconductor substrate, 11 well region, 12 emitter region, 14 base region, 15 contact region, 16 accumulation region, 18 drift region, 20 buffer region, 21 upper surface, 22 collector region, 23 lower surface, 24 collector electrode, 25 peak, 29 straight portion, 30 dummy trench portion, 31 tip portion, 32 dummy insulating film, 34 dummy conductive portion, 38 interlayer insulating film, 39 straight portion, 40 gate trench portion, 41 tip portion, 42 gate insulating film, 44 gate conductive portion, 52 emitter electrode, 54 contact hole, 60, 61 mesa portion, 70 Transistor portion, 80 Diode portion, 81 Extension region, 82 Cathode region, 90 Edge termination structure portion, 100 Semiconductor device, 101 First hydrogen concentration peak, 102 Second hydrogen concentration peak, 103 Intermediate hydrogen distribution, 104 Top-side hydrogen distribution, 105 Bottom-side hydrogen distribution, 106 Passage region, 111 First donor concentration peak, 112 Second donor concentration peak, 113 Intermediate donor distribution, 114 Top-side donor distribution, 115 Bottom-side donor distribution, 130 Periphery gate wiring, 131 Active-side gate wiring, 150 Flat portion, 160 Active portion, 162 Edge, 164 Gate pad

Claims

1. 1. A semiconductor device comprising a semiconductor substrate having an upper surface and a lower surface, The donor concentration distribution in the depth direction of the semiconductor substrate, which is shown on a logarithmic axis, is a flat portion provided over a predetermined range including a central position in the depth direction of the semiconductor substrate; a first hem having an inclination, the first hem being continuous with the end of the flat portion on the upper surface side; a second hem having an inclination, the second hem being continuous with the end of the flat portion on the lower surface side; Including, hydrogen atoms are present in a range including a first vertex at an end of the first skirt on the upper surface side and having a slope of zero, and a second vertex at an end of the second skirt on the lower surface side and having a slope of zero; The flat portion has hydrogen atoms in the range including the flat portion. Semiconductor device.

2. The donor concentrations at the first vertex and the second vertex are the same. The semiconductor device according to claim 1 .

3. A semiconductor device comprising a semiconductor substrate having an upper surface and a lower surface and containing hydrogen, The donor concentration distribution in the depth direction of the semiconductor substrate, which is shown on a logarithmic axis, is a flat portion provided over a predetermined range including a central position in the depth direction of the semiconductor substrate; a first hem having an inclination, the first hem being continuous with the end of the flat portion on the upper surface side; a second hem having an inclination, the second hem being continuous with the end of the flat portion on the lower surface side; Including, a first vertex provided at an end portion on the upper surface side of the first skirt and having a slope of zero, and a second vertex provided at an end portion on the lower surface side of the second skirt and having a slope of zero, have the same donor concentration; The flat portion has hydrogen atoms in the range including the flat portion. Semiconductor device.

4. The predetermined range is at least 5 μm or more. The semiconductor device according to claim 1 .

5. A first donor concentration peak on the upper surface side of the first skirt is higher than a second donor concentration peak on the lower surface side of the second skirt. The semiconductor device according to claim 1 .

6. The second donor concentration peak on the lower surface side of the second skirt is higher than the first donor concentration peak on the upper surface side of the first skirt. The semiconductor device according to claim 1 .

7. 1. A semiconductor device comprising a semiconductor substrate having an upper surface and a lower surface, The donor concentration distribution in the depth direction of the semiconductor substrate, which is shown on a logarithmic axis, is a flat portion provided over a predetermined range of the semiconductor substrate in the depth direction; a first hem having an inclination, the first hem being continuous with the end of the flat portion on the upper surface side; a second hem having an inclination, the second hem being continuous with the end of the flat portion on the lower surface side; Including, a first donor concentration peak on the upper surface side of the first skirt is higher than a second donor concentration peak on the lower surface side of the second skirt, and hydrogen is contained in a range including the first donor concentration peak and the second donor concentration peak; The flat portion has hydrogen atoms in the range including the flat portion. Semiconductor device.

8. The donor concentration distribution is a third hem having an inclination, the third hem being continuous with the first apex on the upper surface side; a fourth hem having an inclination, the fourth hem being continuous with the second apex on a lower surface side thereof; an upper surface side donor distribution provided continuously with an upper surface side end portion of the third skirt; a lower surface side donor distribution provided continuously with the lower surface side end of the fourth skirt; Contains The semiconductor device according to claim 1 .

9. The lower surface side donor distribution has a higher donor concentration than the upper surface side donor distribution. The semiconductor device according to claim 8 .

10. The upper surface side donor distribution has a higher donor concentration than the lower surface side donor distribution. The semiconductor device according to claim 8 .

11. The donor concentration in the flat portion is greater than the bulk donor concentration. The semiconductor device according to claim 1 .

12. The distance between the first vertex and the second vertex in the depth direction is equal to or less than half of the thickness of the semiconductor substrate in the depth direction. The semiconductor device according to any one of claims 1 to 6 or 8 to 11.

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