Patent Publication Number: US-2022216056-A1

Title: Semiconductor device and manufacturing method of semiconductor device

Description:
The contents of the following Japanese patent applications are incorporated herein by reference: 
     NO. 2020-066324 filed in JP on Apr. 1, 2020, and 
     PCT/JP2021/014146 filed in WO on Apr. 1, 2021. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a semiconductor device and a manufacturing method of the semiconductor device. 
     2. Related Art 
     Conventionally, a technique of implanting hydrogen ions into a semiconductor wafer to adjust the doping concentration of the semiconductor wafer has been known (see, for example, Patent Document 1). 
     Patent Document 1: US No. 2015/0050754 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view illustrating an example of the manufacturing method of a semiconductor device  100 . 
         FIG. 2  illustrates the distributions of a lattice defect density D V , a hydrogen chemical concentration C H , a doping concentration D d , and an impurity chemical concentration C I  in a depth direction at positions illustrated by line A-A in  FIG. 1 . 
         FIG. 3  illustrates the distributions of lattice defect density D V , hydrogen chemical concentration C H , doping concentration D d , and impurity chemical concentration C I  according to a comparative example. 
         FIG. 4  is a diagram illustrating the distributions of hydrogen chemical concentration C H  and doping concentration D d  in the vicinity of a buffer region  20 . 
         FIG. 5A  is a flowchart illustrating an example of a manufacturing method of the semiconductor device  100 . 
         FIG. 5B  is a flowchart illustrating another example of the manufacturing method of the semiconductor device  100 . 
         FIG. 6A  is a flowchart illustrating another example of the manufacturing method of the semiconductor device  100 . 
         FIG. 6B  is a flowchart illustrating another example of the manufacturing method of the semiconductor device  100 . 
         FIG. 7  is a diagram illustrating an example of the distribution of hydrogen chemical concentration C H  in the vicinity of the buffer region  20 . 
         FIG. 8  is a diagram illustrating changes in the doping concentration D d  in the vicinity of the buffer region  20  when the dose amount of hydrogen ions with respect to a first depth position Z 1  is changed. 
         FIG. 9A  is a diagram for explaining the relationship between a hydrogen chemical concentration peak  131 - 1  and a doping concentration peak  111 - 1 . 
         FIG. 9B  is a diagram for explaining the relationship between an impurity chemical concentration peak  141  and a doping concentration peak  121 . 
         FIG. 9C  is a diagram for explaining the gradient of a lower tail  142 . 
         FIG. 10A  is a diagram for explaining another definition of normalization of the gradient of the lower tail  112 . 
         FIG. 10B  is a diagram for explaining another definition of normalization of the gradient of a lower tail  122 . 
         FIG. 11  is a graph illustrating the relationship between ε′ and γ indicated by Expression (12) for each β. 
         FIG. 12  is a diagram illustrating an example of a preferred range for a bulk donor concentration N Bre . 
         FIG. 13  is a diagram illustrating an example of a preferred range for the bulk donor concentration N Bre  in a case where ε′ is in Range B (0.01 or more, and 0.333 or less). 
         FIG. 14  is a diagram illustrating an example of a preferred range for the bulk donor concentration N Bre  in a case where ε′ is in Range C (0.03 or more, and 0.25 or less). 
         FIG. 15  is a diagram illustrating an example of a preferred range for the bulk donor concentration N Bre  in a case where ε′ is in Range D (0.1 or more, and 0.2 or less). 
         FIG. 16  is a diagram illustrating an example of a preferred range for the bulk donor concentration N Bre  in a case where ε′ is in Range E (0.001 or more, and 0.1 or less). 
         FIG. 17  is a diagram illustrating an example of a preferred range for the bulk donor concentration N Bre  in a case where ε′ is in Range F (0.002 or more, and 0.05 or less). 
         FIG. 18  is a diagram illustrating an example of a preferred range for the bulk donor concentration N Bre  in a case where ε′ is in Range G (0.005 or more, and 0.02 or less). 
         FIG. 19  is a diagram illustrating an example of a preferred range for the bulk donor concentration N Bre  in a case where ε′ is in Range H (0.01±0.002). 
         FIG. 20  is an example of a top view of the semiconductor device  100 . 
         FIG. 21  is an enlarged view of a region A in  FIG. 20 . 
         FIG. 22A  is a diagram illustrating an example of a cross section b-b in  FIG. 21 . 
         FIG. 22B  is a diagram illustrating an example of the distribution of the doping concentration D d  in line d-d of  FIG. 22A . 
         FIG. 23  is a diagram illustrating another example of the cross section b-b in  FIG. 21 . 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. Not all combinations of features described in the embodiments are essential to the solution of the invention. 
     As used herein, one side in a direction parallel to a depth direction of a semiconductor substrate is referred to as “upper” and the other side is referred to as “lower”. One surface of two principal surfaces of a substrate, a layer or other member is referred to as an upper surface, and the other surface is referred to as a lower surface. “Upper” and “lower” directions are not limited to a direction of gravity, or a direction in which a semiconductor device is mounted. 
     In the present specification, technical matters may be described using orthogonal coordinate axes of an X axis, a Y axis, and a Z axis. The orthogonal coordinate axes merely specify relative positions of components, and do not limit a specific direction. For example, the Z axis is not limited to indicate the height direction with respect to the ground. Note that a +Z axis direction and a −Z axis direction are directions opposite to each other. The Z axis direction described without positive or negative sign means a direction parallel to the +Z axis and the −Z axis. 
     In the present specification, orthogonal axes parallel to the upper surface and the lower surface of the semiconductor substrate are referred to as the X axis and the Y axis. Further, an axis perpendicular to the upper surface and the lower surface of the semiconductor substrate is referred to as the Z axis. In the present specification, the direction of the Z axis may be referred to as the depth direction. Further, in the present specification, a direction parallel to the upper surface and the lower surface of the semiconductor substrate may be referred to as a horizontal direction, including an X axis direction and a Y axis direction. 
     A region from the center of the semiconductor substrate in the depth direction to the upper surface of the semiconductor substrate may be referred to as an upper surface side. Similarly, a region from the center of the semiconductor substrate in the depth direction to the lower surface of the semiconductor substrate may be referred to as a lower surface side. In the present specification, the center position in the depth direction of the semiconductor substrate may be referred to as Zc. 
     In the present specification, a case where a term such as “same” or “equal” is mentioned may include a case where an error due to a variation in manufacturing or the like is included. The error is, for example, within 10%. 
     In the present specification, a conductivity type of doping region in which doping has been carried out with an impurity is described as a P type or an N type. In the present specification, the impurity may particularly mean either a donor of the N type or an acceptor of the P type, and may be described as a dopant. In the present specification, the doping means introducing the donor or the acceptor into the semiconductor substrate and turning it into a semiconductor exhibiting a conductivity type of the N type, or a semiconductor exhibiting conductivity type of the P type. 
     In the present specification, a doping concentration means a concentration of the donor or a concentration of the acceptor in a thermal equilibrium state. In the present specification, a net doping concentration means a net concentration obtained by adding the donor concentration set as a positive ion concentration to the acceptor concentration set as a negative ion concentration, taking polarities of charges into account. As an example, when the donor concentration is N D  and the acceptor concentration is defined as N A , the net doping concentration at any position is defined as N D -N A . In the present specification, the net doping concentration may be simply referred to as a doping concentration. 
     The donor has a function of supplying electrons to a semiconductor. The acceptor has a function of receiving electrons from the semiconductor. The donor and acceptor are not limited to the impurities themselves. For example, a VOH defect which is a combination of a vacancy (V), oxygen (O), and hydrogen (H) existing in the semiconductor functions as the donor that supplies electrons. In the present specification, the VOH defect may be referred to herein as a hydrogen donor. 
     In the present specification, a description of a P+ type or an N+ type means a doping concentration higher than that of the P type or the N type, and a description of a P− type or an N− type means a lower doping concentration than that of the P type or the N type. Further, in the specification, a description of a P++ type or an N++ type means a doping concentration higher than that of the P+ type or the N+ type. The unit system in the present specification is an SI unit system unless otherwise specified. The unit of length may be expressed in cm, but various calculations may be performed after conversion into meters (m). 
     A chemical concentration in the present specification refers to an atomic density of an impurity measured regardless of an electrical activation state. The chemical concentration (atomic density) can be measured by, for example, secondary ion mass spectrometry (SIMS). The above-mentioned net doping concentration described above can be measured by voltage-capacitance profiling (CV profiling). Further, a carrier concentration measured by spreading resistance profiling method (SRP method) may be set as the net doping concentration. The carrier concentration measured by the CV profiling or the SR method may be a value in a thermal equilibrium state. Further, in a region of the N type, the donor concentration is sufficiently higher than the acceptor concentration, and thus the carrier concentration in the region may be set as the donor concentration. Similarly, in a P type region, the carrier concentration in the region may be set as the acceptor concentration. In the present specification, the doping concentration of the N type region may be referred to as a donor concentration, and the doping concentration of the P type region may be referred to as an acceptor concentration. 
     When a concentration distribution of the donor, acceptor, or net doping has a peak in a region, a value of the peak may be set as the concentration of the donor, acceptor, or net doping in the region. When the concentration of the donor, acceptor or net doping is substantially uniform in a region, or the like, an average value of the concentration of the donor, acceptor or net doping in the region may be set as the concentration of the donor, acceptor or net doping. In the present specification, atoms/cm 3  or /cm 3  may be used for concentration display per unit volume. This unit is used for the donor or acceptor concentration or the chemical concentration in the semiconductor substrate. The expression of atoms may be omitted. 
     The carrier concentration measured by the SR method may be lower than the concentration of the donor or the acceptor. In a range where a current flows when a spreading resistance is measured, carrier mobility of the semiconductor substrate may be lower than a value in a crystalline state. The reduction in carrier mobility occurs when carriers are scattered due to disorder of a crystal structure caused by a lattice defect or the like. 
     The concentration of the donor or the acceptor calculated from the carrier concentration measured by the CV profiling or the SR method may be lower than a chemical concentration of an element indicating the donor or the acceptor. As an example, in a silicon semiconductor, a donor concentration of phosphorus or arsenic serving as a donor, or an acceptor concentration of boron serving as an acceptor is approximately 99% of chemical concentrations of these. On the other hand, in the silicon semiconductor, a donor concentration of hydrogen serving as a donor is approximately 0.1% to 10% of a chemical concentration of hydrogen. Each concentration in the present specification may be a value at room temperature. As the value at room temperature, a value at 300 K (Kelvin) (about 26.9° C.) may be used as an example. 
     When charged particles such as ions or electrons are implanted into a semiconductor substrate with a predetermined acceleration energy, these particles have a predetermined distribution in the depth direction. In the present specification, the peak position of the distribution may be referred to as the position where the particles are implanted, the depth at which the particles are implanted, or the like. 
       FIG. 1  is a sectional view illustrating an example of the manufacturing method 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. 
     At least one of a transistor device such as an insulated gate bipolar transistor (IGBT) and a diode device such as a freewheeling diode (FWD) is formed on the semiconductor substrate  10 . In  FIG. 1 , the respective electrodes of the transistor device and the diode device, and the respective regions provided in the semiconductor substrate  10  are omitted. Configuration examples of the transistor device and the diode device will be described later. 
     In the semiconductor substrate  10  of the present example, bulk donors of an N type are distributed throughout. The bulk donor is a dopant donor substantially uniformly contained in an ingot during the production of the ingot from which the semiconductor substrate  10  is made. The bulk donor of the present example is an element other than hydrogen. The dopant of the bulk donor is, for example, phosphorus, antimony, arsenic, selenium, or sulfur, but the invention is not limited to these. The bulk donor of the present example is phosphorus. The bulk donor is also contained in a P type region. The semiconductor substrate  10  may be a wafer cut out from a semiconductor ingot, or may be a chip obtained by dicing the wafer into individual pieces. The semiconductor ingot may be manufactured by either a Czochralski method (CZ method), a magnetic field applied Czochralski method (MCZ method), or a float zone method (FZ method). The ingot in the present example is manufactured by the MCZ method. The oxygen concentration contained in the substrate manufactured by the MCZ method is 1×10 17  to 7×10 17 /cm 3 . The oxygen concentration contained in the substrate manufactured by the FZ method is 1×10 15  to 5×10 16 /cm 3 . When the oxygen concentration is high, hydrogen donors tend to be easily generated. The bulk donor concentration may use a chemical concentration of bulk donors distributed throughout the semiconductor substrate  10 , and may be a value between 90% and 100% of the chemical concentration. As the semiconductor substrate  10 , a non-doped substrate not containing a dopant such as phosphorus may be used. In that case, the bulk donor concentration of the non-doped substrate is, for example, 1×10 10 /cm 3  or more, and 5×10 12 /cm 3  or less. The bulk donor concentration of the non-doped substrate is preferably 1×10 11 /cm 3  or more. The bulk donor concentration of the non-doped substrate is preferably 5×10 12 /cm 3  or less. 
     The semiconductor substrate  10  has an upper surface  21  and a lower surface  23 . The upper surface  21  and the lower surface  23  are two principal surfaces of the semiconductor substrate  10 . In the present specification, orthogonal axes in a plane parallel to the upper surface  21  and the lower surface  23  are defined as an X axis and a Y axis, and an axis perpendicular to the upper surface  21  and the lower surface  23  is defined as a Z axis. 
     A buffer region  20  of an N type is provided on the lower surface  23  side of the semiconductor substrate  10  (that is, the region between the lower surface  23  and the central position Zc in the depth direction). A lower surface region  201  is provided between the buffer region  20  and the lower surface  23 . The lower surface region  201  is an N type or P type region having a doping concentration higher than a high-concentration region  150  described later. The lower surface region  201  may be a cathode region or a collector region described later. The buffer region  20  suppresses a depletion layer spreading from the upper surface  21  side of the semiconductor substrate  10  from reaching the lower surface region  201  (punch-through). 
     The buffer region  20  has a plurality of doping concentration peaks  111  in the depth direction of the semiconductor substrate  10 . In the example of  FIG. 1 , doping concentration peaks  111 - 1 ,  111 - 2 ,  111 - 3 , and  111 - 4  are provided in order from the lower surface  23  side. Providing the plurality of doping concentration peaks  111  can prevent the above-mentioned depletion layer from spreading to the lower surface region  201 . In the present specification, the doping concentration peak  111 - 1  may be referred to as the shallowest doping concentration peak. The doping concentration peak  111 - 1  has a doping concentration higher than other doping concentration peaks  111 . The buffer region  20  may contain a hydrogen donor. 
     In the manufacturing method of the present example, the plurality of doping concentration peaks in the buffer region  20  are formed in two stages. In a first step S 1001 , charged particles are implanted from the lower surface  23  of the semiconductor substrate  10  to a second depth position Z 2 . The charged particles are, for example, hydrogen ions, helium ions, or electrons. The semiconductor substrate  10  of the present example has an impurity chemical concentration peak  141  such as hydrogen or helium at the second depth position Z 2 . Note that the second depth position Z 2  may be a position above the upper surface  21 . That is, the charged particles may be implanted so as to penetrate the semiconductor substrate  10 . 
     The depth position is a position in the depth direction (Z axis direction) of the semiconductor substrate  10 . In the present specification, the distance from the lower surface  23  to each position may be referred to as the depth position of each position. For example, the second depth position Z 2  indicates that the distance from the lower surface  23  is Z 2 . The second depth position Z 2  may be disposed on the upper surface  21  side of the semiconductor substrate  10  (that is, the region between the upper surface  21  and the central position Zc in the depth direction). 
     An average distance (also referred to as a range) over which the charged particles pass through the inside of the semiconductor substrate  10  can be controlled by acceleration energy for accelerating the charged particles. In the present example, the acceleration energy is set so that the average range of the charged particles is the distance Z 2 . The average range Z 2  of the charged particles may be larger than half the thickness of the semiconductor substrate  10  in the depth direction. 
     In the present specification, a region through which the implanted charged particles have passed may be referred to as the passed-through region  106 . In the example of  FIG. 1 , a region from the lower surface  23  of the semiconductor substrate  10  to the second depth position Z 2  is the passed-through region  106 . In the example of  FIG. 1 , the charged particles are implanted from the entire lower surface  23  of the semiconductor substrate  10 . In another example, the charged particles may be implanted into only a partial region of the lower surface  23 . As a result, the passed-through region  106  can be locally formed on the XY plane. 
     In the first step S 1001 , hydrogen ions such as protons are implanted from the lower surface  23  of the semiconductor substrate  10  to a first depth position Z 1 . After implanting hydrogen ions, the entire semiconductor substrate  10  is annealed. As a result, the doping concentration peak  111 - 1  caused by the hydrogen donor is formed at the first depth position Z 1 . Note that, at the time of annealing, no impurity ions are locally implanted between the first depth position Z 1  and the second depth position Z 2  other than the above-mentioned hydrogen ions and charged particles. 
     In the passed-through region  106  through which the charged particles have passed in the semiconductor substrate  10 , lattice defects mainly including vacancies such as monovacancies (V) and divacancies (VV) are formed by the charged particles passing therethrough. Atoms adjacent to the vacancies have dangling bonds. Lattice defects include interstitial atoms, dislocations, and the like, and may include donors and acceptors in a broad sense. However, in the present specification, lattice defects mainly including vacancies may be referred to as vacancy-type lattice defects, vacancy-type defects, or simply lattice defects. Since many lattice defects are formed by implanting of charged particles into the semiconductor substrate  10 , the crystallinity of the semiconductor substrate  10  may be strongly disturbed. In the present specification, this disturbance of crystallinity may be referred to as disorder. 
     Oxygen is contained in the entire semiconductor substrate  10 . The oxygen is introduced intentionally or unintentionally at the time of manufacturing a semiconductor ingot. In the semiconductor substrate  10 , a hydrogen (H), a vacancy (V), and an oxygen (O) are bound to form a VOH defect. The heat treatment of the semiconductor substrate  10  makes hydrogen, which has been implanted into the first depth position Z 1 , diffuse to promote the formation of VOH defects. When the charged particles implanted into the second depth position Z 2  are hydrogen ions, hydrogen also diffuses from the second depth position Z 2 , and further promotes the formation of VOH defects. 
     The VOH defect functions as a donor that supplies electrons. In the present specification, the VOH defect may be referred to simply as a hydrogen donor. In the present example, a hydrogen donor is formed in the passed-through region  106  of the charged particles. The doping concentration of the hydrogen donor is lower than the chemical concentration of hydrogen. When the ratio of the doping concentration of the hydrogen donor to the chemical concentration of hydrogen is defined as an activation rate, the activation rate may be a value of 0.1% to 30%. In the present example, the activation rate is 1% to 5%. 
     Forming a hydrogen donor in the passed-through region  106  of the semiconductor substrate  10  can make the donor concentration in the passed-through region  106  higher than the bulk donor concentration. Usually, it is necessary to prepare the semiconductor substrate  10  having a predetermined bulk donor concentration in accordance with characteristics of an element to be formed on the semiconductor substrate  10 , particularly a rated voltage or a breakdown voltage. On the other hand, according to the semiconductor device  100  illustrated in  FIG. 1 , the donor concentration of the semiconductor substrate  10  can be adjusted by controlling the dose amounts of the charged particles and the hydrogen ions. Therefore, the semiconductor device  100  can be manufactured using a semiconductor substrate  10  having a bulk donor concentration that does not correspond to the characteristics and the like of the device. The variation in the bulk donor concentration at the time of manufacturing the semiconductor substrate  10  is relatively large, but the dose amounts of the charged particles and the hydrogen ions can be controlled with relatively high accuracy. Therefore, the concentration of lattice defects generated by implanting the charged particles can be controlled with high accuracy, and the concentration of hydrogen bound to lattice defects can also be controlled with high accuracy. Therefore, the donor concentration in the passed-through region  106  can be controlled with high accuracy. 
     Further, it is preferable that the hydrogen implanted into the first depth position Z 1  diffuses toward the upper surface  21  to a position farther away. As a result, the length of the passed-through region  106  in the Z axis direction can be increased, and the doping concentration can be easily adjusted over a wide region of the semiconductor substrate  10 . 
     If impurities other than the above-mentioned hydrogen ions and charged particles are implanted between the first depth position Z 1  and the second depth position Z 2 , many lattice defects are formed in the vicinity of the implantation position. The diffusion of hydrogen ions is suppressed in the region where many lattice defects are formed. Therefore, if a region having a high-density lattice defect exists between the first depth position Z 1  and the second depth position Z 2 , the diffusion of hydrogen is suppressed. 
     In the present example, after the first step S 1001  in which hydrogen implanted into the first depth position Z 1  is diffused into the passed-through region  106 , the other doping concentration peaks  111 - 2 ,  111 - 3 , and  111 - 4  are formed in a second step S 1002 . That is, in the second step S 1002 , an N type dopant such as a hydrogen ion is implanted and annealed at one or more depth positions between the first depth position Z 1  and the second depth position Z 2 . As a result, the doping concentration peaks  111 - 2 ,  111 - 3 , and  111 - 4  are formed. In this way, after the hydrogen implanted into the first depth position Z 1  is diffused, the doping concentration peaks  111 - 2 ,  111 - 3 , and  111 - 4  are formed, so that diffusing the hydrogen to a deeper position and providing the plurality of doping concentration peaks  111  in the buffer region  20  both can be accomplished. 
       FIG. 2  illustrates the distributions of a lattice defect density D v , a hydrogen chemical concentration C H , a doping concentration D d , and an impurity chemical concentration C I  in the depth direction at the positions illustrated by line A-A in  FIG. 1 . The impurities in the present example are helium or hydrogen. The horizontal axis of  FIG. 2  represents the depth position from the lower surface  23 , and the vertical axis illustrates the hydrogen chemical concentration, the donor concentration and the impurity chemical concentration per unit volume on a logarithmic axis. In the distributions in  FIG. 2 , the lattice defect density D V  is a distribution at the start of annealing of the first step S 1001  illustrated  FIG. 1 . Concentrations other than lattice defects show a distribution of the second step S 1002  illustrate in  FIG. 1  after annealing. 
     The hydrogen chemical concentration and the impurity chemical concentration in  FIG. 2  are measured by, for example, the SIMS method. The doping concentration in  FIG. 2  is an electrically activated doping concentration measured by, for example, the CV method or the SR method. 
     The hydrogen chemical concentration C H  of the present example has a hydrogen chemical concentration peak  131 - 1  at the first depth position Z 1 . The hydrogen chemical concentration peak  131  shows a local maximum value at the first depth position Z 1 . Further, the hydrogen chemical concentration C H  has a hydrogen chemical concentration peak  131  at a third depth position Z 3 . A plurality of third depth positions Z 3  may be disposed. In the example of  FIG. 2 , the third depth positions Z 3 - 1 , Z 3 - 2 , and Z 3 - 3  are disposed. The hydrogen chemical concentration peak  131  is located at each third depth position Z 3 . The hydrogen chemical concentration peaks  131 - 2  to  131 - 4  are the peaks caused by the hydrogen ions implanted in the second step S 1002  in  FIG. 1 . 
     The impurity chemical concentration C I  of the present example has an impurity chemical concentration peak  141  at the second depth position Z 2 . The impurity chemical concentration peak  141  shows a local maximum value at the second depth position Z 2 . 
     The doping concentration D d  has the plurality of doping concentration peaks  111  and the doping concentration peak  121 . In the present example, the doping concentration peak  111  is disposed at the first depth position Z 1  and each third depth position Z 3 . The doping concentration D d  may have a doping concentration peak in the lower surface region  201 . The lower surface region  201  of the present example has a P type doping concentration peak. A P type dopant such as boron may be implanted into the lower surface region  201 . In another example, the lower surface region  201  may have an N type doping concentration peak. In this case, an N type dopant such as phosphorus may be implanted into the lower surface region  201 . 
     The doping concentration peak  111  of the present example is a concentration peak of a hydrogen donor (VOH defect) in which the lattice defect caused by the implantation of hydrogen ions into the first depth position Z 1  and the third depth position Z 3 , and hydrogen are bound. Therefore, the doping concentration peak  111  shows a local maximum value at the first depth position Z 1  and each third depth position Z 3 . 
     The doping concentration peak  121  is a concentration peak of a hydrogen donor in which a lattice defect caused by implantation of charged particles into the second depth position Z 2  and hydrogen diffused from the first depth position Z 1  are bound. Therefore, the doping concentration peak  121  shows a local maximum value at the second depth position Z 2 . 
     Note that the position where the doping concentration peak  111 - 1  shows the local maximum value may not exactly coincide with the first depth position Z 1 . For example, if the position showing that the doping concentration peak  111 - 1  is the local maximum value is within the range of a full width at half maximum of the first hydrogen chemical concentration peak  131  with respect to the first depth position Z 1 , the doping concentration peak  111 - 1  may be assumed to be disposed substantially at the first depth position Z 1 . Similarly, if the position showing that the doping concentration peak  121  is the local maximum value is within the range of a full width at half maximum of the impurity chemical concentration peak  141  with respect to the second depth position Z 2 , the doping concentration peak  121  may be assumed to be disposed substantially at the second depth position Z 2 . Similarly, if the position showing that the doping concentration peak  111  is the local maximum value is within the range of a full width at half maximum of the hydrogen chemical concentration peak  131  with respect to the third depth position Z 3 , the doping concentration peak  111  may be assumed to be disposed substantially at the third depth position Z 3 . 
     When the doping concentration peak  111 - 1  overlaps with the doping concentration peak of the lower surface region  201  and it is difficult to distinguish the doping concentration peak  111 - 1 , the doping concentration at the depth position Z 1  of the local maximum of the hydrogen chemical concentration peak  131 - 1  may be set as the doping concentration peak  111 - 1 . 
     Each concentration peak has a lower tail in which the concentration decreases from the local maximum toward the lower surface  23  and an upper tail in which the concentration decreases from the local maximum toward the upper surface  21 . In the present example, the hydrogen chemical concentration peak  131  has a lower tail  132  and an upper tail  133 . The impurity chemical concentration peak  141  has a lower tail  142  and an upper tail  143 . The doping concentration peak  111  has a lower tail  112  and an upper tail  113 . The doping concentration peak  121  has a lower tail  122  and an upper tail  123 . 
     Since hydrogen ions are implanted from the lower surface  23  into the first depth position Z 1  and the third depth position Z 3 , a relatively large amount of hydrogen exists between the first depth position Z 1  and the lower surface  23  and also between the third depth position Z 3  and the lower surface  23 . Similarly, there are many impurities implanted as charged particles between the second depth position Z 2  and the lower surface  23 . Therefore, at each concentration peak in each chemical concentration distribution, the concentration may decrease more steeply in the upper tail than in the lower tail. Since the doping concentration depends on the hydrogen chemical concentration or the impurity chemical concentration, the concentration may decrease more steeply in the upper tail than in the lower tail at each doping concentration peak. 
     At the start of annealing in the first step S 1001 , a relatively large number of lattice defects are formed by the implantation of hydrogen ions or charged particles in the vicinity of the first depth position Z 1  and the second depth position Z 2 . Therefore, the lattice defect density D V  has a first defect density peak  211  at the first depth position Z 1  and a second defect density peak  212  at the second depth position Z 2 . In the passed-through region  106  from the second depth position Z 2  to the lower surface  23  (see  FIG. 1 ), the lattice defects generated by the passing-through of the charged particles are formed at a substantially uniform density except the vicinity of the first depth position Z 1  and the second depth position Z 2 . As illustrated by the dotted line in the distribution diagram of the lattice defect density D V  of  FIG. 2 , the lattice defect density D V  may gradually increase toward the peak  212  within a range not exceeding the peak  212 . Even when the lattice defect density D V  increases toward the peak  212  in this way, the lattice defects generated by the passing-through of the charged particles may be formed at a substantially uniform density. 
     The hydrogen implanted into the first depth position Z 1  diffuses toward the upper surface  21  by annealing processing. At the start of annealing in the first step S 1001 , hydrogen ions are not implanted into the third depth position Z 3 . Therefore, there are no defect density peaks other than the first defect density peak  211  and the second defect density peak  212  between the first depth position Z 1  and the second depth position Z 2 . Therefore, hydrogen is likely to diffuse from the first depth position Z 1  to the second depth position Z 2 . A VOH defect (hydrogen donor) is formed in the region where hydrogen having a concentration equal to or more than a certain concentration is diffused in the passed-through region  106 , and the high-concentration region  150  containing a hydrogen donor is formed. The high-concentration region  150  is a region where the donor concentration is higher than the bulk donor concentration D b . The high-concentration region  150  is disposed between the buffer region  20  and the upper surface  21  of the semiconductor substrate  10 . 
     The high-concentration region  150  may be a region having a substantially uniform doping concentration in the depth direction. The substantially uniform doping concentration in the depth direction may indicate, for example, a state where a region in which the difference between the maximum value and the minimum value of the doping concentration is within 50% of the maximum value of the doping concentration is continuous in the depth direction. The difference may be 30% or less, or 10% or less, of the maximum value of the doping concentration in the region. 
     Alternatively, with respect to the average concentration of the doping concentration distribution in a predetermined range in the depth direction, the value of the doping concentration distribution may be within ±50%, within ±30%, or within ±10% of the average concentration of the doping concentration distribution. A predetermined range W in the depth direction may be as follows as an example. That is, when the length from the first depth position Z 1  to the second depth position Z 2  is set to Z L , a section with a length of 0.5Z L  between two points separated by 0.25Z L  from the center Z12c between Z 1  and Z 2 , toward the first depth position Z 1  side and the second depth position Z 2  side, may be set as the range. Depending on the length of the high-concentration region  150 , the length of the predetermined range may be set as 0.75Z L , 0.3Z L , or 0.9Z L . The end position on the upper surface  21  side of the buffer region  20  may be a depth position where the substantially uniform doping concentration in the high-concentration region  150  begins to monotonically increase toward the doping concentration peak  111 - 1 . 
     At the start of annealing in the first step S 1001 , it is preferable that there are no doping concentration peaks other than the doping concentration peak  111 - 1  and the doping concentration peak  121  between the first depth position Z 1  and the second depth position Z 2 . It is preferable that there are no chemical concentration peaks other than the hydrogen chemical concentration peak  131 - 1  and the impurity chemical concentration peak  141  between the first depth position Z 1  and the second depth position Z 2 . As a result, the hydrogen is likely to diffuse from the first depth position Z 1  to the second depth position Z 2 . 
     Facilitating the diffusion of hydrogen allows the high-concentration region  150  to be formed easily long in the depth direction. The high-concentration region  150  may be continuously provided from the position in contact with the doping concentration peak  111 - 1  to the impurity chemical concentration peak  141 . The high-concentration region  150  may be continuously provided from the upper end of the buffer region  20  to the second depth position Z 2 . 
     The length of the high-concentration region  150  in the depth direction may be 40% or more, 50% or more, 60% or more, 70% or more, or 80% or more of the thickness of the semiconductor substrate  10  in the depth direction. The length of the high-concentration region  150  may be a length L 1  from the upper end of the buffer region  20  to the upper end of the high-concentration region  150 , or may be a length L 2  from the position Z 1  of the doping concentration peak  111 - 1  to the upper end of the high-concentration region  150 . The upper end of the high-concentration region  150  may be at the depth position Z 2 . The length of the high-concentration region  150  in the depth direction may be 50 μm or more, 60 μm or more, 70 μm or more, 80 μm or more, 90 μm or more, or may be 100 μm or more. In the present example, hydrogen is easily diffused to the second depth position Z 2 , so that the range in which the high-concentration region  150  is formed is easily defined by the second depth position Z 2 . 
     The minimum value of the donor concentration of the high-concentration region  150  is higher than the bulk donor concentration D b  of the semiconductor substrate  10 . That is, the donor concentration (or doping concentration) of the high-concentration region  150  is higher than the bulk donor concentration D b  over the entire high-concentration region  150 . The donor concentration of the high-concentration region  150  is determined by the sum of the bulk donor concentration and the hydrogen donor concentration (VOH defect concentration). The hydrogen donor concentration can be accurately controlled by the dose amount of the charged particles with respect to the second depth position Z 2  and the dose amount of the hydrogen ions with respect to the first depth position Z 1 . Therefore, by making the hydrogen donor concentration sufficiently higher than the bulk donor concentration, it is possible to reduce the variation in the donor concentration of the high-concentration region  150  even when the bulk donor concentration varies. The donor concentration of the high-concentration region  150  may be 2 times or more, 5 times or more, or 10 times or more of the bulk donor concentration D b . 
       FIG. 3  illustrates the distributions of the lattice defect density D V , the hydrogen chemical concentration C H , the doping concentration D d , and the impurity chemical concentration C I  according to a comparative example. In the semiconductor device of the comparative example, hydrogen ions are implanted into the first depth position Z 1  and each third depth position Z 3 , and then the semiconductor substrate  10  is annealed to diffuse hydrogen implanted into the first depth position Z 1 . 
     The lattice defect density D V  of the present example has a defect density peak  213  at each third depth position Z 3  at the start of annealing to diffuse hydrogen ions. That is, one or more defect density peaks  213  are provided between the first depth position Z 1  and the second depth position Z 2 . Therefore, the diffusion of hydrogen implanted into the first depth position Z 1  is hindered by the defect density peak  213 . For example, hydrogen is bound to lattice defects, or the presence of lattice defects impedes hydrogen movement. 
     Therefore, in the example of  FIG. 3 , hydrogen is not sufficiently diffused to the second depth position Z 2 . In this case, the high-concentration region  150  is not formed up to the second depth position Z 2 , and a low-concentration region  181  having a low donor concentration remains. The donor concentration of the low-concentration region  181  may be the same degree as the bulk donor concentration D b . When many lattice defects remain in the low-concentration region  181 , the carrier concentration of the low-concentration region  181  may be lower than the bulk donor concentration D b . Since almost no hydrogen donor is formed in the low-concentration region  181 , the donor concentration of the low-concentration region  181  is greatly affected by the bulk donor concentration. Therefore, the donor concentration of the low-concentration region  181  has a relatively large variation. A valley-shaped portion is formed in the doping concentration distribution, which may affect the characteristics of the semiconductor device  100 . On the other hand, according to the semiconductor device  100  illustrate in  FIG. 2 , since the high-concentration region  150  can be formed widely, the variation in the doping concentration can be suppressed, and the characteristics of the semiconductor device  100  can be adjusted accurately. 
     Note that, in the buffer region  20 , it is conceivable to increase the concentration of the hydrogen chemical concentration peak  131 - 4  closest to the upper surface  21 . This makes it easier to diffuse hydrogen up to a position close to the upper surface  21 . However, if the hydrogen chemical concentration peak  131 - 4  near the upper surface  21  is made high, the depletion layer will reach the doping concentration peak  111 - 4  of a high concentration in a state where the emitter-collector voltage is relatively high, and avalanche withstand-capability may decrease. According to the example illustrate in  FIG. 2 , the high-concentration region  150  can be formed up to the vicinity of the upper surface  21  while suppressing the decrease in the avalanche capability by disposing the doping concentration peak  111 - 1  of a high concentration in the vicinity of the lower surface  23 . The distance between the first depth position Z 1  and the lower surface  23  may be 5 μm or less, or may be 3 μm or less. 
       FIG. 4  is a diagram illustrating the distribution of the hydrogen chemical concentration C H  and the doping concentration D d  in the vicinity of the buffer region  20 . In the present example, the peak concentration of the doping concentration peak  111 - 1  is defined as A, the peak concentration of the doping concentration peak  111 - 2  is defined as B 2 , the peak concentration of the doping concentration peak  111 - 3  is defined as B 3 , and the peak concentration of the doping concentration peak  111 - 4  is defined as B 4 . The peak concentration of the hydrogen chemical concentration peak  131 - 1  is defined as H 1 - 1 , the peak concentration of the hydrogen chemical concentration peak  131 - 2  is defined as H 1 - 2 , the peak concentration of the hydrogen chemical concentration peak  131 - 3  is defined as H 1 - 3 , and the peak concentration of the hydrogen chemical concentration peak  131 - 4  is defined as H 1 - 4 . 
     The ratio A/B between the peak concentration A of the doping concentration peak  111 - 1  and an average peak concentration B of the other doping concentration peak  111  (in the present example, (B 2 +B 3 +B 4 )/3) is 200 or less. The average peak concentration B may be set as 10 {log10(B2)+log10(B3)+log10(B4)}/3 . In the semiconductor device  100 , since the hydrogen implanted into the first depth position Z 1  easily diffuses to the upper surface  21  side, the high-concentration region  150  can be formed over a long range even if the peak concentration A is lowered. Reducing the peak concentration A can suppress the occurrence of the back surface avalanche when the depletion layer from the upper surface  21  side reaches the doping concentration peak  111 - 1 . The ratio A/B may be 100 or less, 30 or less, 20 or less, 10 or less, 8 or less, or 5 or less. However, if the peak concentration A of the doping concentration peak  111 - 1  is too low, hydrogen may not be sufficiently diffused. The ratio A/B may be 2 or more, 3 or more, 5 or more, or 10 or more. The peak concentration A may be 1×10 16 /cm 3  or less, 5×10 15 /cm 3  or less, or 1×10 15 /cm 3  or less. 
     The ratio H 1 - 1 /HA between the peak concentration H 1 - 1  of the hydrogen chemical concentration peak  131 - 1  and an average peak concentration HA of other hydrogen chemical concentration peak  131  (in the present example, (H 1 - 2 +H 1 - 3 +H 1 - 4 )/3) may also be 200 or less. The ratio H 1 - 1 /HA may be 100 or less, 30 or less, 20 or less, 10 or less, 8 or less, or 5 or less. The ratio H 1 - 1 /HA may be 2 or more, 3 or more, 5 or more, or 10 or more. 
     The dose amount of hydrogen ions (ions/cm 2 ) to the first depth position Z 1  is defined as C, and the total dose amount of hydrogen ions to each third depth position Z 3  is defined as D. The dose amount C is the dose amount corresponding to the doping concentration peak  111 - 1 , and the dose amount D is the dose amount corresponding to the other doping concentration peak  111 . As the dose amount corresponding to each doping concentration peak  111 , the value obtained by integrating the hydrogen chemical concentration C H  within the range of the full width at half maximum of each doping concentration peak  111  may be used. 
     The ratio C/D of the dose amount C to the total dose amount D may be 6 or more, and 100 or less. As a result, it becomes easy to suppress the occurrence of the back surface avalanche while securing the length of the high-concentration region  150 . The ratio C/D may be 10 or more. The ratio C/D may be 30 or less. 
       FIG. 5A  is a flowchart illustrating an example of a manufacturing method of the semiconductor device  100 . First, in an upper surface side structure forming step S 500 , the structure on the upper surface  21  side of the semiconductor substrate  10  is formed. The structure on the upper surface  21  side includes at least some of a gate trench, a dummy trench, an emitter region, a base region, an accumulation region, an interlayer dielectric film, an emitter electrode, and a gate runner, which will be described later. In the upper surface side structure forming step S 500 , all these structures may be formed. 
     Next, in a grinding step S 502 , the lower surface  23  side of the semiconductor substrate  10  is ground to adjust the thickness of the semiconductor substrate  10 . In the grinding step S 502 , the thickness of the semiconductor substrate  10  may be adjusted according to the breakdown voltage that the semiconductor device  100  should have. 
     Next, in a lower surface region forming step S 504 , the lower surface region  201  is formed in the region in contact with the lower surface  23  of the semiconductor substrate  10 . In the lower surface region forming step S 504 , the lower surface region  201  may be formed by implanting an N type dopant or a P type dopant from the lower surface  23  and locally annealing the vicinity of the lower surface  23  with a laser or the like. 
     Next, in a first implantation step S 505 , the charged particles and the hydrogen ions are implanted into the semiconductor substrate  10 . The first implantation step S 505  has a charged particle implantation step S 506  and a hydrogen implantation step S 508 . In the charged particle implantation step S 506 , the charged particles are implanted from the lower surface  23  of the semiconductor substrate  10  to the second depth position Z 2 . The second depth position Z 2  is closer to the upper surface  21  than the first depth position Z 1 . The charged particles may be, for example, hydrogen ions, helium ions, or electrons. In the hydrogen implantation step S 508 , the hydrogen ions are implanted from the lower surface  23  of the semiconductor substrate  10  to the first depth position Z 1 . In the hydrogen implantation step S 508 , the hydrogen ions may be implanted into the first depth position Z 1  such that the hydrogen chemical concentration distribution has a single peak in the region between the second depth position Z 2  and the first depth position Z 1 . Note that, when the hydrogen ions are implanted into the second depth position Z 2 , the peak of the hydrogen chemical concentration may exist at the second depth position Z 2 . Either the charged particle implantation step S 506  or the hydrogen implantation step S 508  may be performed first. 
     Next, the semiconductor substrate  10  is annealed in a first annealing step S 510 . The first implantation step S 505  and the first annealing step S 510  correspond to the first step S 1001  in  FIG. 1 . In the first annealing step S 510 , the semiconductor substrate  10  is put into an annealing furnace, and the entire semiconductor substrate  10  is annealed. By the first annealing step S 510 , the high-concentration region  150  is formed between the first depth position Z 1  and the second depth position Z 2 . The first annealing step S 510  is preferably performed under the condition that the hydrogen implanted into the first depth position Z 1  can diffuse to the second depth position Z 2 . For example, the annealing temperature of the annealing step S 510  is 350° C. or higher and 400° C. or lower. The annealing temperature may be 360° C. or higher and may be 380° C. or lower. The annealing time in the first annealing step S 510  may be 30 minutes or more, 1 hour or more, or 3 hours or more. The annealing time may be 10 hours or less, or may be 7 hours or less. 
     Next, in a second implantation step S 512 , an N type dopant such as hydrogen is implanted into the third depth position Z 3 . As described in  FIG. 2  and the like, the third depth position Z 3  may be disposed at one or more positions in the depth direction. The first depth position Z 1  and each third depth position Z 3  may be disposed on the lower surface  23  side of the semiconductor substrate  10 . The second depth position Z 2  may be disposed on the upper surface  21  side of the semiconductor substrate  10 . 
     Next, the semiconductor substrate  10  is annealed in a second annealing step S 514 . The second implantation step S 512  and the second annealing step S 514  correspond to the second step S 1002  in  FIG. 1 . In the second annealing step S 514 , the semiconductor substrate  10  may be put into an annealing furnace, and the entire semiconductor substrate  10  may be annealed. By the second annealing step S 514 , the N type dopant implanted into the third depth position Z 3  is activated to form one or more doping concentration peaks  111 . The annealing conditions in the second annealing step S 514  are the same as those in the first annealing step S 510 . That is, the annealing temperature of the second annealing step S 514  may be 350° C. or higher and 400° C. or lower. The annealing temperature may be 360° C. or higher and may be 380° C. or lower. The annealing time in the second annealing step S 514  may be 30 minutes or more, 1 hour or more, or 3 hours or more. The annealing time may be 10 hours or less, or may be 7 hours or less. 
     The difference between an annealing temperature T 2  of the second annealing step S 514  and an annealing temperature T 1  of the first annealing step S 510  may be 10° C. or less. The difference in annealing temperature may be 5° C. or less, or may be 0. The annealing temperatures T 1  and T 2  may be T 1 =T 2 , T 2 &lt;T 1 , or T 2 &gt;T 1  under the condition that the difference in annealing temperature satisfies the above. In the present example, T 1 =T 2 . The difference between the annealing times of the second annealing step S 514  and the first annealing step S 510  may be 10% or less, 5% or less, or 0 of the larger annealing time. By making the second annealing step S 514  equivalent to the annealing conditions of the first annealing step S 510 , the disappearance of the hydrogen donor formed in the first annealing step S 510  can be suppressed. 
     In a lower surface side electrode forming step S 520 , a metal electrode is formed in the lower surface  23  of the semiconductor substrate  10 . The metal electrode may be a collector electrode described later. A lifetime killer forming step S 516  and a third annealing step S 518  may be provided between the second annealing step S 514  and the lower surface side electrode forming step S 520 . 
     The lifetime killer forming step S 516  locally forms lattice defects by implanting impurities such as helium into the semiconductor substrate  10 . The impurity may be implanted into the upper surface  21  side of the semiconductor substrate  10 , or may be implanted into the lower surface  23  side. The impurity may be implanted into a diode portion described later. The impurity may also be implanted into the transistor portion described later. In the third annealing step S 518 , the semiconductor substrate  10  is annealed to adjust the density of lattice defects. An annealing temperature T 3  of the third annealing step S 518  may be equal to or lower than the annealing temperature T 1  of the first annealing step S 510 . Alternatively, the annealing temperature T 3  of the third annealing step S 518  may be equal to or lower than the annealing temperature T 2  of the second annealing step S 510 . 
       FIG. 5B  is a flowchart illustrating another example of the manufacturing method of the semiconductor device  100 . In the manufacturing method of the present example, the order of the charged particle implantation step S 506  and the hydrogen implantation step S 508  is changed with respect to the example illustrate in  FIG. 5A . That is, in the present example, the charged particle implantation step S 506  is performed after the hydrogen implantation step S 508 . The first annealing step S 510  is performed after the charged particle implantation step S 506 . Other steps may be similar to the example illustrate in  FIG. 5A . Also in the present example, the high-concentration region  150  can be formed long in the depth direction. 
       FIG. 6A  is a flowchart illustrating another example of the manufacturing method of the semiconductor device  100 . The manufacturing method of the present example differs from the example illustrate in  FIG. 5A  in the second implantation step S 512 . Other steps may be similar to the example illustrate in  FIG. 5A . 
     In the second implantation step S 512  of the present example, the hydrogen ions are implanted into the first depth position Z 1  in addition to the third depth position Z 3 . That is, the hydrogen ions are implanted into the first depth position Z 1  in two steps, the first implantation step S 505  and the second implantation step S 512 . 
     By implanting hydrogen ions into the third depth position Z 3 , lattice defects are formed at a high density in the vicinity of the third depth position Z 3 . The hydrogen implanted into the third depth position Z 3  is diffused by the second annealing step S 514 , and bound to these lattice defects. However, since the dose amount of the hydrogen implanted into the third depth position Z 3  has relatively low, many lattice defects may remain. On the other hand, by implanting hydrogen ions also into the first depth position Z 1  in the second implantation step S 512 , the hydrogen implanted into the first depth position Z 1  is bound to the lattice defects in the vicinity of the third depth position Z 3 , so that the lattice defect density can be reduced. 
       FIG. 6B  is a flowchart illustrating another example of the manufacturing method of the semiconductor device  100 . In the manufacturing method of the present example, the order of the charged particle implantation step S 506  and the hydrogen implantation step S 508  is changed with respect to the example illustrate in  FIG. 6A . That is, in the present example, the charged particle implantation step S 506  is performed after the hydrogen implantation step S 508 . The first annealing step S 510  is performed after the charged particle implantation step S 506 . Other steps may be similar to the example illustrate in  FIG. 6A . Also in the present example, the high-concentration region  150  can be formed long in the depth direction. 
       FIG. 7  is a diagram illustrating an example of the distribution of the hydrogen chemical concentration C H  in the vicinity of the buffer region  20 . The distribution of the hydrogen chemical concentration C H  in  FIG. 7  is the distribution after the second annealing step S 514 . The hydrogen chemical concentration caused by the hydrogen implanted by the first implantation step S 505  is defined as C H0 . The hydrogen is diffused to the upper surface  21  side by the first annealing step S 510 . The peak value of the hydrogen chemical concentration C H0  after the first annealing step S 510  is defined as H 1 - 0 . 
     Next, in the second implantation step S 512 , hydrogen ions are implanted into the first depth position Z 1  and each third depth position Z 3 . An N type dopant such as phosphorus may be implanted into the third depth position Z 3  instead of the hydrogen ion. The hydrogen additionally implanted into the first depth position Z 1  is diffused in the vicinity of each third depth position Z 3  by the second annealing step S 514 . As a result, it possible to reduce the lattice defect density in the vicinity of each third depth position Z 3 . The peak value of the hydrogen chemical concentration C H  after the second annealing step S 514  is defined as H 1 - 1 . 
     Note that an N type dopant such as phosphorus may be additionally implanted into the buffer region  20 . In  FIG. 7 , a chain line illustrates an example of the distribution of the phosphorus chemical concentration C P . The phosphorus chemical concentration C P  may have a chemical concentration peak  171  between the lower surface  23  and the depth position Z 1 . The concentration of the peak  171  may be larger or smaller than the peak value H 1 - 1 . The concentration of the peak  171  may be larger or smaller than the peak value H 1 - 0 . 
     The peak value H 1 - 0  may be larger than any of the hydrogen chemical concentration peaks  131 - 2 ,  131 - 3 , and  131 - 4 . By increasing the concentration of hydrogen ions implanted in the first implantation step S 505 , hydrogen can be diffused to a deeper position. The dose amount of hydrogen ions implanted into the first depth position Z 1  in the first implantation step S 505  may be larger than the total dose amount of hydrogen ions implanted into each third depth position Z 3  in the second implantation step S 512 . 
     The difference between the peak value H 1 - 1  and the peak value H 1 - 0  may be smaller than the peak value H 1 - 0 . That is, a second dose amount of hydrogen ions implanted into the first depth position Z 1  in the second implantation step S 512  may be lower than a first dose amount of hydrogen ions implanted into the first depth position Z 1  in the first implantation step S 505 . In the second implantation step S 512 , it is sufficient that the lattice defects in the vicinity of the third depth position Z 3  can be terminated, so that the dose amount of hydrogen ions may be small. The second dose amount may be less than half of the first dose amount. The first dose amount may be 1×10 14  ions/cm 2  or more. The first dose amount may be 2×10 14  ions/cm 2  or more, or may be 5×10 14  ions/cm 2  or more. The second dose amount may be 5×10 13  ions/cm 2  or more, or may be 1×10 14  ions/cm 2  or more. 
       FIG. 8  is a diagram illustrating the change in the doping concentration D d  in the vicinity of the buffer region  20  when the dose amount of hydrogen ions with respect to the first depth position Z 1  is changed. In the present example, in the second implantation step  512 , hydrogen ions are not implanted into the first depth position Z 1 . The dose amount of hydrogen ions for each third depth position Z 3  is not changed. 
     The doping concentration D d1  is a doping concentration in a case where the dose amount of hydrogen ions with respect to the first depth position Z 1  is 1×10 14 /cm 2 . The doping concentration D d2  is a doping concentration in a case where the dose amount of hydrogen ions with respect to the first depth position Z 1  is 3×10 13 /cm 2 . The doping concentration D d3  is a doping concentration in a case where the dose amount of hydrogen ions with respect to the first depth position Z 1  is 1×10 13 /cm 2 . Note that the dose amount of hydrogen ions at the third depth position Z 3 , which is the closest to the first depth position Z 1 , is 1×10 13 /cm 2 . 
     In any dose amount, the doping concentration distribution on the upper surface  21  side of the doping concentration peak  111 - 2  does not change much. On the other hand, the doping concentration between the doping concentration peak  111 - 1  and the doping concentration peak  111 - 2  changes greatly depending on the dose amount with respect to the first depth position Z 1 . Note that, even if the dose amount with respect to the first depth position Z 1  is further increased more than 1×10 14 /cm 2 , the doping concentration between the doping concentration peak  111 - 1  and the doping concentration peak  111 - 2  hardly changes. 
     Therefore, if the dose amount with respect to the first depth position Z 1  is small, it is considered that the lattice defects between the doping concentration peak  111 - 1  and the doping concentration peak  111 - 2  are not sufficiently bonded to hydrogen. The dose amount of hydrogen ions with respect to the first depth position Z 1  may be 3×10 13 /cm 2  or more, or may be 1×10 14 /cm 2  or more. The dose amount of hydrogen ion with respect to the first depth position Z 1  may be 3 times or more, or 10 times or more the dose amount of hydrogen ion with respect to the third depth position Z 3  closest to the first depth position Z 1 . The doping concentration of the doping concentration peak  111 - 1  may be 3 times or more, or 10 times or more the doping concentration of the doping concentration peak  111 - 2 . 
       FIG. 9A  is a diagram for explaining the relationship between the hydrogen chemical concentration peak  131 - 1  and the doping concentration peak  111 - 1 . In the present example, an gradient  114  of the lower tail  112  of the doping concentration peak  111 - 1  is normalized by using an gradient  134  of the lower tail  132  of the hydrogen chemical concentration peak  131 - 1 . Normalization is a process of dividing the gradient  114  by the gradient  134  as an example. 
     The gradient of the lower tail may be the gradient between the position where the concentration shows a local maximum value and the position where the concentration becomes a predetermined ratio to the local maximum value. The predetermined ratio may be 80%, 50%, 10%, or 1%, and any other ratio may be used. Further, in the hydrogen chemical concentration peak  131 - 1  and the doping concentration peak  111 - 1 , the gradient of the concentration distribution between the first depth position Z 1  and the lower surface  23  of the semiconductor substrate  10  may be used. 
     In the example illustrate in  FIG. 9A , the gradient  134  of the hydrogen chemical concentration peak  131 - 1  is given by (H 1 -aH 1 )/(Z 1 -Z 4 ), and the gradient  114  of the doping concentration peak  111 - 1  is given by (D 1 -aD 1 )/(Z 1 -Z 5 ). H 1  is the hydrogen chemical concentration at the first depth position Z 1 , D 1  is the doping concentration at the first depth position Z 1 , a is a predetermined ratio, Z 4  is the depth at which the hydrogen concentration becomes aH 1  at the lower tail  132  of the hydrogen chemical concentration peak  131 - 1 , and Z 5  is the depth at which the doping concentration becomes aD 1  at the lower tail  112  of the doping concentration peak  111 - 1 . For example, if the gradient  114  is normalized with the gradient  134 , it becomes (D 1 -aD 1 )(Z 1 -Z 4 )/{(H 1 -aH 1 )(Z 1 -Z 5 )}. The gradient obtained by normalizing the gradient  114  with the gradient  134  is defined as α. 
       FIG. 9B  is a diagram for explaining the relationship between the impurity chemical concentration peak  141  and the doping concentration peak  121 . In the present example, hydrogen ions are implanted as charged particles to the second depth position Z 2 . In the present example, an gradient  144  of the lower tail  142  of the impurity chemical concentration peak  141  is used to normalize an gradient  124  of the lower tail of the doping concentration peak  121 . 
     In the example illustrate in  FIG. 9B , the gradient  144  of the impurity chemical concentration peak  141  is given by (H 2 -aH 2 )/(Z 2 -Z 6 ), and the gradient  124  of the doping concentration peak  121  is given by (D 2 -aD 2 )/(Z 2 -Z 7 ). H 2  is the hydrogen chemical concentration at the second depth position Z 2 , D 2  is the doping concentration at the second depth position Z 2 , a is a predetermined ratio, Z 6  is the depth at which the hydrogen chemical concentration becomes aH 2  at the lower tail  142  of the impurity chemical concentration peak  141 , and Z 7  is the depth at which the doping concentration becomes aD 2  at the lower tail  122  of the doping concentration peak  121 . The ratio a used to normalize the gradient of the doping concentration peak  121  may be the same as or different from the ratio a used to normalize the gradient of the doping concentration peak  111 - 1 . For example, if the gradient  124  is normalized with the gradient  144 , it becomes (D 2 -aD 2 )(Z 2 -Z 6 )/{(Z 2 -Z 7 )(H 2 -aH 2 )}. The gradient obtained by normalizing the gradient  124  with the gradient  144  is defined as β. 
     The normalized gradient β of the lower tail  122  of the doping concentration peak  121  is smaller than the normalized gradient α of the lower tail  112  of the doping concentration peak  111 - 1 . That is, the doping concentration peak  121  is a gentler peak with respect to the peak of the hydrogen chemical concentration as compared with the doping concentration peak  111 - 1 . By implanting hydrogen ions so that such a doping concentration peak  121  is formed, the high-concentration region  150  having a flat concentration distribution can be formed. By forming the doping concentration peak  121  into a gentle shape, it is possible to moderate the change in the doping concentration at the edge of the high-concentration region  150 . The normalized gradient β of the lower tail  122  of the doping concentration peak  121  may be 1 times or less, 0.1 times or less, or 0.01 times or less than the normalized gradient a of the lower tail of the doping concentration peak  111 - 1 . 
     The gradient  144  of the lower tail  142  of the impurity chemical concentration peak  141  may be smaller than an gradient  145  of the upper tail  143 . The chemical concentration distribution of hydrogen implanted at a deep position from the lower surface  23  may draw a gentle tail toward the lower surface  23  side. Therefore, it may be possible to determine whether the hydrogen implanted into the second depth position Z 2  has been implanted from the lower surface  23  side by comparing the gradient  144  of the lower tail  142  with the gradient  145  of the upper tail  143 . The gradient  145  is given by (H 2 -aH 2 )/(Z 8 -Z 2 ). The gradient  125  is given by (D 2 -aD 2 )/(Z 9 -Z 2 ). Z 8  is the depth at which the hydrogen chemical concentration becomes aH 2  at the upper tail  143  of the impurity chemical concentration peak  141 , and Z 9  is the depth at which the doping concentration becomes aD 2  at the upper tail  123  of the doping concentration peak  121 . Note that, in  FIG. 9B , the gradient  124  of the lower tail  122  of the doping concentration peak  121  is larger than the gradient  125  of the upper tail  123 , but similarly to the impurity chemical concentration peak  141 , the gradient  124  of the lower tail  122  of the doping concentration peak  121  may be smaller than the gradient  125  of the upper tail  123 . 
       FIG. 9C  is a diagram for explaining the gradient of the lower tail  142 . The gradient of the lower tail  142  may be considered as follows. As illustrate in  FIG. 9C , at the impurity chemical concentration peak  141 , the width (10% full width) between two positions Z 10  and Z 11 , where the concentration becomes 10% (0.1×H 2 ) of the peak concentration H 2 , is defined as FW10% M. The two positions Z 10  and Z 11  are the two positions with the second depth position Z 2  sandwiched therebetween and closest to the second depth position Z 2  among the points where the hydrogen chemical concentration becomes 0.1×H 2 . One of the two positions Z 10  and Z 11  on the hydrogen chemical concentration peak  131 - 1  side is defined as Z 10 . The gradient of the doping concentration at the position Z 10  is almost flat. The gradient of the hydrogen chemical concentration at the position Z 10  is more than 100 times the gradient of the doping concentration at the position Z 10 . For example, the gradient of the hydrogen chemical concentration at the position Z 10  may be 100 times or more, or 1000 times or more the gradient of the doping concentration at the position Z 10 . 
       FIG. 10A  is a diagram for explaining another definition of normalization of the gradient of the lower tail  112 . In normalizing the gradient of the lower tail  112 , for example, the following index γ is introduced. In the example of  FIG. 9A , the position Z 4  and the position Z 5  are different, but in the present example, the position Z 4  and the position Z 5  are set to the same position (Z 4 =Z 5 ). The position Z 4  is a predetermined position here. The position Z 4  may be a position where the hydrogen chemical concentration C H  and the doping concentration D d  are at the lower tails  132  and  112  on the lower surface  23  side of the first depth position Z 1 . The hydrogen chemical concentration at the position Z 4  is defined as a×H 1 , and the doping concentration is defined as b×D 1 . a is the ratio of the hydrogen chemical concentration at the position Z 4  to the concentration H 1  of the hydrogen chemical concentration peak  131 - 1  at the first depth position Z 1 . b is the ratio of the doping concentration at the position Z 4  to the concentration D 1  of the doping concentration peak  111 - 1  at the first depth position Z 1 . Here, the ratios of the gradients of the hydrogen chemical concentration and the doping concentration in a section Z 4  to Z 1  and an gradient ratio γ obtained by normalizing the ratios of the gradients are introduced. The ratio of the gradient of the hydrogen chemical concentration in the section Z 4  to Z 1  is defined as (H 1 /aH 1 )/(Z 1 -Z 4 ). Similarly, the ratio of the gradient of the donor concentration in the section Z 4  to Z 1  is defined as (D 1 /bD 1 )/(Z 1 -Z 4 ). Then, the gradient ratio γ, which is the ratio of the gradient of the hydrogen chemical concentration in the section Z 4  to Z 1  and is obtained by normalizing the ratio of the gradient of the doping concentration, is defined as {(D 1 /bD 1 )/(Z 1 -Z 4 )}/{(H 1 /aH 1 )/(Z 1 -Z 4 )}. The normalized gradient ratio γ becomes a simple ratio a/b by calculating the above equation. 
       FIG. 10B  is a diagram for explaining another definition of normalization of the gradient of the lower tail  122 . In normalizing the gradient of the lower tail  122 , for example, an index ε similar to the index γ is introduced. In the example of  FIG. 9B , the position Z 6  and the position Z 7  are different, but in the present example, the position Z 6  and the position Z 7  are set to the same position (Z 6 =Z 7 ). The position Z 6  is a predetermined position here. The position Z 6  may be a position where the hydrogen chemical concentration and the doping concentration are at the lower tails  142  and  122  on the lower surface  23  side of the second depth position Z 2 . The hydrogen chemical concentration at the position Z 6  is defined as c×H 2 , and the doping concentration is defined as d×D 2 . c is the ratio of the hydrogen chemical concentration at the position Z 6  to the hydrogen chemical concentration H 2  at the second depth position Z 2 . d is the ratio of the doping concentration at the position Z 6  to the concentration D 2  of the doping concentration peak  121  at the second depth position Z 2 . Here, the ratios of the gradients of the hydrogen chemical concentration and the doping concentration in a section Z 6  to Z 2  and an gradient ratio ε obtained by normalizing the ratios of the gradients are introduced. The ratio of the gradient of the hydrogen chemical concentration in the section Z 6  to Z 2  is defined as (H 2 /cH 2 )/(Z 2 -Z 6 ). Similarly, the ratio of the gradient of the doping concentration in the section Z 6  to Z 2  is defined as (D 2 /dD 2 )/(Z 2 -Z 6 ). Then, the gradient ratio ε, which is the ratio of the gradient of the hydrogen chemical concentration in the section Z 6  to Z 2  and is obtained by normalizing the ratio of the gradient of the doping concentration, is defined as {(D 2 /dD 2 )/(Z 2 -Z 6 )}/{(H 2 /cH 2 )/(Z 2 -Z 6 )}. The normalized gradient ratio a becomes a simple ratio (c/d) by calculating the above equation. 
     For the hydrogen chemical concentration peak  131 - 1  and the doping concentration peak  111 - 1 , the hydrogen chemical concentration distribution and the doping concentration distribution often have similar shapes in many cases. Here, the similar shape means that the doping concentration distribution exhibits, for example, a distribution to which the hydrogen chemical concentration distribution is reflected when the horizontal axis is the depth and the vertical axis is the common logarithm of the concentration. That is, in the predetermined section Z 4  to Z 1 , hydrogen ions are implanted and further the annealing is performed, so that the doping concentration distribution becomes a distribution to which the hydrogen chemical concentration distribution is reflected. As an example, if H 1  of the hydrogen chemical concentration peak  131 - 1  is 1×10 17  atoms/cm 3  and the hydrogen chemical concentration aH 1  at the position Z 4  is 2×10 16  atoms/cm 3 , a becomes 0.2. On the other hand, if D 1  of the doping concentration peak  111 - 1  is 1×10 16 /cm 3  and the doping concentration bD 1  at the position Z 4  is 2×10 15 /cm 3 , b becomes 0.2. Therefore, the normalized gradient ratio γ becomes 1 because it is a/b. That is, at the first depth position Z 1  near the lower surface  23 , the ratio a of the gradient of the hydrogen chemical concentration distribution and the ratio b of the gradient of the doping concentration distribution become almost the same value, and it can be said that they have similar shapes. 
     On the other hand, for the impurity chemical concentration peak  141  and the doping concentration peak  121 , the hydrogen chemical concentration distribution and the doping concentration distribution may not have similar shapes. That is, in the predetermined section Z 6  to Z 2 , the doping concentration distribution may not reflect the hydrogen chemical concentration distribution. As an example, if the hydrogen chemical concentration H 2  of the impurity chemical concentration peak  141  is 1×10 16  atoms/cm 3  and the hydrogen chemical concentration cH 2  at the position Z 6  is 1×10 15  atoms/cm 3 , c becomes 0.1. On the other hand, if the concentration D 2  of the doping concentration peak  121  is 3×10 14 /cm 3  and the doping concentration dD 2  at the position Z 6  is 1.5×10 14 /cm 3 , d becomes 0.5. Therefore, the normalized gradient ratio ε becomes 0.2 because it is c/d. That is, at the second depth position Z 2  sufficiently deep from the lower surface  23 , the ratio c of the gradient of the hydrogen chemical concentration distribution becomes 0.2 times smaller than the ratio d of the gradient of the doping concentration distribution, and it can be said that they show different shapes. 
     Comparing the normalized gradient ratios γ and ε, γ becomes close to 1 when the peak position of the hydrogen chemical concentration distribution is close to the lower surface  23 , and ε may become a value sufficiently higher than 1 when the peak position of the hydrogen chemical concentration distribution is sufficiently deep from the lower surface  23 . That is, the normalized gradient ratio ε may be larger than the normalized gradient ratio γ. Further, the gradient ratio ε may be 1.1 or more, 1.5 or more, and 2 or more. Alternatively, the gradient ratio may be 10 or more, or 100 or more. 
     Note that the actual positions of the hydrogen chemical concentration peak  131 - 1  and the impurity chemical concentration peak  141  may differ from the actual positions of the doping concentration peak  111 - 1  and the doping concentration peak  121 . When the position of the chemical concentration peak and the position of the doping concentration do not match in this way, the position of the chemical concentration peak may be set to the first depth position Z 1  or the second depth position Z 2 . For the doping concentration, the concentration at the first depth position Z 1  or the second depth position Z 2  may be set as the peak position for convenience. As a result, it possible to calculate according to the above definition. 
       FIG. 11  to  FIG. 19  are diagrams for explaining an example of a method for determining a preferred range of the bulk donor concentration and the donor concentration of the high-concentration region  150 . In the present example, the bulk donor concentration and the donor concentration are set such that the final donor concentration (doping concentration) in the high-concentration region  150  becomes a relatively stable concentration even when the bulk donor concentration varies. 
     In the present example, the specification value of the bulk donor concentration is defined as N B0 , and the actual bulk donor concentration is defined as N Bre . The specification value of the bulk donor concentration is a specification value defined by a manufacturer of semiconductor wafers. In a case where the specification value has a width, a median value of the specification value may be used. The bulk donor concentration is given by N=1/qμρ with respect to a specific resistance ρ determined by the concentration of the bulk donor such as phosphorus. q is an elementary electric charge, and μ is electron mobility in the semiconductor substrate  10 . 
     The concentration of the hydrogen donor (VOH defect) is defined as N H . The variation in the hydrogen donor concentration N H  is negligibly small compared to the variation in the bulk donor concentration. In the present example, the variation in the hydrogen donor concentration N H  is set to 0. 
     The target value of the final donor concentration is defined as N F0 . The final donor concentration actually obtained is defined as N Fre . The above-mentioned concentrations are all concentrations (/cm 3 ) per unit volume. 
     The target value N F0  of the final donor concentration is obtained by adding the hydrogen donor concentration N H  to the specification value N B0  of the bulk donor concentration, and thus is given by the following Expression. 
         N   F0   =N   H   +N   B0   Expression (1)
 
     On the other hand, the actual donor concentration N Fre  is obtained by adding the hydrogen donor concentration N H  to the actual bulk donor concentration N Bre , and thus is given by the following Expression. 
         N   Fre   =N   H   +N   Bre   Expression (2)
 
     The parameter β is defined by the following Expression. 
       β= N   Bre   /N   B0   Expression (3)
 
     The parameter β is a ratio between the actual bulk donor concentration N Bre  and the specification value N B0 , and the bulk donor concentration N Bre  deviates from the specification value N B0  as the parameter is far from 1. 
     The parameter γ is defined by the following Expression. 
       γ= N   Fre   /N   F0   Expression (4)
 
     The parameter γ is a ratio between the actual donor concentration N Fre  and the target value N F0 , and the actual donor concentration N Fre  deviates from the target value N F0  as the parameter is far from 1. That is, if γ is sufficiently close to 1, even when the actual bulk donor concentration N Bre  deviates by β times from the specification value N B0 , the actual donor concentration N Fre  substantially matches the target value N F0  almost independently of β. 
     Here, the specific resistance variation of a silicon wafer manufactured by the FZ method in which the variation in the bulk donor concentration is relatively small is generally as follows.
         Neutron-irradiated FZ wafer . . . ±8% (ratio 0.92 to 1.08)   Gas-doped FZ wafer . . . ±12% (ratio 0.88 to 1.12)       

     Therefore, when γ is 0.85 or more and 1.15 or less, the variation in the final donor concentration N Fre  is substantially the same degree as the bulk donor concentration of the silicon wafer of the FZ method described above. In the present specification, the allowable value of γ is 0.85 or more and 1.15 or less. 
     The actual donor concentration N Fre  is affected by the variation (β) in the actual bulk donor concentration N Bre . On the other hand, the variation in the hydrogen donor concentration N H  can be regarded as almost 0 as compared with the variation in the bulk donor concentration N Bre . Therefore, by reducing the specification value N B0  of the bulk donor concentration with respect to the target value N F0  of the donor concentration, it is possible to reduce the ratio of components that vary in the donor concentration N Fre . 
     A parameter ε′ is defined by the following Expression. 
         N   B0   =ε′×N   F0   Expression (5)
 
     Here, 0&lt;ε′&lt;1. The parameter ε′ is a parameter that means to set the specification value N B0  of the bulk donor concentration by ε′ relative to the target value N F0  of the donor concentration. It is examined whether γ approaches sufficiently 1 regardless of β when ε′ is set to a value smaller than 1 within a range not to be 0. 
     The parameter ε is defined by the following Expression. 
       ε=1/ε′  Expression (6)
 
     The following Expression is obtained from Expression (5) and Expression (6). 
         N   B0   =N   F0 /ε  Expression (7)
 
     The following Expression is obtained by substituting Expression (7) into Expression (1). 
         N   F0   =N   H   +N   F0 /ε, that is,  N   H =(1−1/ε)  N   F0   Expression (8)
 
     The following Expression is obtained by substituting Expression (8) and Expression (3) into Expression (2). 
         N   Fre =(1−1/ε)  N   F0   +βN   B0   Expression (9)
 
     The following Expression is obtained by substituting Expression (7) into Expression (9). 
         N   Fre =(1−1/ε) N   F0 +(β/ε) N   F0 =(1−1/ε+β/ε)  N   F0   Expression (10)
 
     The following Expression is obtained by substituting Expression (10) into Expression (4). 
       γ=1−1/ε+β/ε=1+(β−1)/ε  Expression (11)
 
     The following Expression is obtained from Expression (6) and Expression (11). 
       γ=1+ε′(β−1)  Expression (12)
 
       FIG. 11  is a graph illustrating the relationship between ε′ and γ represented by Expression (12) for each β. As described above, γ represents the ratio of the actual donor concentration N Fre  to the target value N F0 , and β  13  represents the ratio of the actual bulk donor concentration N Bre  to the specification value N B0 . The allowable value of γ is 0.85 or more and 1.15 or less. 
     For example, the specification value N B0  of the bulk donor concentration is 0.5 times or less the target value N F0  of the donor concentration, that is, ε′ is 0.5 or less. In this case, for example, even when β is 1.3, γ is 1.15 or less and falls within an allowable range. That is, even when the actual bulk donor concentration N Bre  is 30% higher than the specification value N B0 , the actual donor concentration N Fre  becomes 1.15 times or less the target value N F0 . Even when β is 0.7, if ε′ is 0.5 or less, γ falls within the allowable range. As ε′ approaches 0, γ converges to 1. For example, in the case of β=2, if ε′ is approximately 0.2 or less, γ falls within the allowable range. 
     In order to make γ fall within the above-mentioned allowable range, for example, the following ranges A to D are conceivable as preferred ranges of ε′. 
     (Range A) 
     ε′ is 0.001 or more and 0.5 or less. In a case where ε′ is 0.5, if β is within a range of 0.7 to 1.3, γ is within the allowable range. For example, in a case where the specification value N B0  of the bulk donor concentration is 1×10 14 /cm 3  and ε′ is 0.001, the target value N F0  of the donor concentration is 1×10 11 /cm 3 , corresponding to about 46000 Ωcm. 
     (Range B) 
     ε′ is 0.01 or more and 0.333 or less. In a case where ε is 0.333, if β is within a range of 0.5 to 1.5, γ is within the allowable range. For example, in a case where the specification value N B0  of the bulk donor concentration is 1×10 14 /cm 3  and ε is 0.01, the target value N F0  of the donor concentration is 1×10 12 /cm 3 , corresponding to about 4600 Ωcm. 
     (Range C) 
     ε′ is 0.03 or more and 0.25 or less. In a case where ε′ is 0.25, if β is within a range of roughly 0.4 to 1.6, γ is within the allowable range. For example, in a case where the specification value N B0  of the bulk donor concentration is 1×10 14 /cm 3  and ε′ is 0.03, the target value N F0  of the donor concentration is 3×10 12 /cm 3 , corresponding to about 1500 Ωcm. 
     (Range D) 
     ε′ is 0.1 or more and 0.2 or less. In a case where ε′ is 0.2, β is within a range of roughly 0.2 to 1.8, γ is within the allowable range. For example, in a case where the specification value N B0  of the bulk donor concentration is 1×10 14 /cm 3  and ε is 0.1, the target value N F0  of the donor concentration is 1×10 13 /cm 3 , corresponding to about 460 Ωcm. 
     Note that, since the less variation in specific resistance is suitable for practical use, ε′ is preferably 0.1 or less, and more preferably 0.02 or less. In this case, for example, the following ranges E to H can be considered. 
     (Range E) 
     ε′ is 0.001 or more and 0.1 or less. In a case where ε′ is 0.1, if β is within a range of roughly 0.05 (not illustrated) to 3.0, γ is within a sufficiently allowable range. For example, in a case where the specification value N B0  of the bulk donor concentration is 1×10 14 /cm 3  and ε′ is 0.1, the target value N F0  of the donor concentration is 1×10 13 /cm 3 , corresponding to about 460 Ωcm. 
     (Range F) 
     ε′ is 0.002 or more and 0.05 or less. In a case where ε′ is 0.05, β is within a range of roughly 0.01 (not illustrated) to 5.0, γ is within a sufficiently allowable range. For example, in a case where the specification value N B0  of the bulk donor concentration is 1×10 14 /cm 3  and ε′ is 0.05, the target value N F0  of the donor concentration is 5×10 12 /cm 3 , corresponding to about 920 Ωcm. 
     (Range G) 
     ε′ is 0.005 or more and 0.02 or less. In a case where ε′ is 0.02, β is within a range of roughly 0.01 (not illustrated) to 10.0, γ is within a sufficiently allowable range. For example, in a case where the specification value N B0  of the bulk donor concentration is 1×10 14 /cm 3  and ε′ is 0.02, the target value N F0  of the donor concentration is 2×10 12 /cm 3 , corresponding to about 2300 Ωcm. 
     (Range H) 
     In a case where ε′ has a width of 0.01±0.002 (20%). In a case where ε′ is 0.01, if β is within a range of roughly 0.01 (not illustrated) to 20.0 (not illustrated), γ is within a sufficiently allowable range. For example, in a case where the specification value N B0  of the bulk donor concentration is 1×10 14 /cm 3  and ε′ is 0.01, the target value N F0  of the donor concentration is 1×10 12 /cm 3 , corresponding to about 4600 Ωcm. 
     As described above, the actual donor concentration N Fre  corresponds to the donor concentration of the high-concentration region  150 . The breakdown voltage of the semiconductor device  100  is almost determined by the donor concentration in the high-concentration region  150 , which occupies a large region in the semiconductor substrate  10 . Therefore, a preferred range of the donor concentration N Fre  of the high-concentration region  150  is determined by the rated voltage of the semiconductor device  100 . Depending on the donor concentration N Fre , the range of the bulk donor concentration N Bre  that can stabilize the donor concentration N Fre  is determined. 
       FIG. 12  is a diagram illustrating an example of a preferred range for the bulk donor concentration N Bre . In the present example, the donor concentration N Fre  (/cm 3 ) at the center Zc of the semiconductor substrate  10  in the depth direction is (9.20245×10 15 )/x or more and (9.20245×10 16 )/x or less. Here, x is the rated voltage (V). The donor concentration N Fre  (/cm 3 ) is determined with reference to the doping concentration of the drift region in the general semiconductor substrate formed by the FZ method, but may be determined with reference to the doping concentration of the drift region of the semiconductor substrate formed by the MCZ method. In  FIG. 12 , an upper limit  311  and a lower limit  312  of the preferred range of the donor concentration N Fre  (/cm 3 ) are indicated by broken lines. 
     In  FIG. 12 , an upper limit  313  and a lower limit  314  of the preferred range of the bulk donor concentration N Bre  in the case of the above-mentioned Range A (ε is 0.001 or more, and 0.5 or less) are indicated by solid lines. The upper limit  313  of the bulk donor concentration N Bre  is a value obtained by multiplying the upper limit  311  of the donor concentration N Fre  (/cm 3 ) by an upper limit value (0.5) of ε′. The lower limit  314  of the bulk donor concentration N Bre  is a value obtained by multiplying the lower limit  312  of the donor concentration N Fre  (/cm 3 ) by a lower limit value (0.001) of ε′. The upper limit  313  and the lower limit  314  of the bulk donor concentration N Bre  are as follows. Note that the units of the upper limit  313  and the lower limit  314  in each example are (/cm 3 ). As described above, x is the rated voltage (V).
         Lower limit  314 : (9.20245×10 12 )/x   Upper limit  313 : (4.60123×10 16 )/x       

       FIG. 13  is a diagram illustrating an example of the preferred range for the bulk donor concentration N Bre  in a case where ε′ is in Range B (0.01 or more, and 0.333 or less). Note that the upper limit  311  and the lower limit  312  of the donor concentration N Fre  (/cm 3 ) are the same as those in the example of  FIG. 12 . The upper limit  313  of the bulk donor concentration N Bre  is a value obtained by multiplying the upper limit  311  of the donor concentration N Fre  (/cm 3 ) by an upper limit value (0.333) of ε′. The lower limit  314  of the bulk donor concentration N Bre  is a value obtained by multiplying the lower limit  312  of the donor concentration N Fre  (/cm 3 ) by a lower limit value (0.01) of ε′. The upper limit  313  and the lower limit  314  of the bulk donor concentration N Bre  are as follows.
         Lower limit  314 : (9.20245×10 13 )/x   Upper limit  313 : (3.06442×10 16 )/x       

       FIG. 14  is a diagram illustrating an example of the preferred range for the bulk donor concentration N Bre  in a case where ε′ is in Range C (0.03 or more, and 0.25 or less). Note that the upper limit  311  and the lower limit  312  of the donor concentration N Fre  (/cm 3 ) are the same as those in the example of  FIG. 12 . The upper limit  313  of the bulk donor concentration N Bre  is a value obtained by multiplying the upper limit  311  of the donor concentration N Fre  (/cm 3 ) by an upper limit value (0.25) of ε′. The lower limit  314  of the bulk donor concentration N Bre  is a value obtained by multiplying the lower limit  312  of the donor concentration N Fre  (/cm 3 ) by a lower limit value (0.03) of ε′. The upper limit  313  and the lower limit  314  of the bulk donor concentration N Bre  are as follows.
         Lower limit  314 : (2.76074×10 14 )/x   Upper limit  313 : (2.30061×10 16 )/x       

       FIG. 15  is a diagram illustrating an example of the preferred range for the bulk donor concentration N Bre  in a case where ε′ is in Range D (0.1 or more, and 0.2 or less). Note that the upper limit  311  and the lower limit  312  of the donor concentration N Fre  (/cm 3 ) are the same as those in the example of  FIG. 12 . The upper limit  313  of the bulk donor concentration N Bre  is a value obtained by multiplying the upper limit  311  of the donor concentration N Fre  (/cm 3 ) by an upper limit value (0.2) of ε′. The lower limit  314  of the bulk donor concentration N Bre  is a value obtained by multiplying the lower limit  312  of the donor concentration N Fre  (/cm 3 ) by a lower limit value (0.1) of ε′. The upper limit  313  and the lower limit  314  of the bulk donor concentration N Bre  are as follows.
         Lower limit  314 : (9.20245×10 14 )/x   Upper limit  313 : (1.84049×10 16 )/x       

       FIG. 16  is a diagram illustrating an example of the preferred range for the bulk donor concentration N Bre  in a case where ε′ is in Range E (0.001 or more, and 0.1 or less). Note that the upper limit  311  and the lower limit  312  of the donor concentration N Fre  (/cm 3 ) are the same as those in the example of  FIG. 12 . The upper limit  313  of the bulk donor concentration N Bre  is a value obtained by multiplying the upper limit  311  of the donor concentration N Fre  (/cm 3 ) by an upper limit value (0.1) of ε′. The lower limit  314  of the bulk donor concentration N Bre  is a value obtained by multiplying the lower limit  312  of the donor concentration N Fre  (/cm 3 ) by a lower limit value (0.001) of ε′. The upper limit  313  and the lower limit  314  of the bulk donor concentration N Bre  are as follows.
         Lower limit  314 : (9.20245×10 12 )/x   Upper limit  313 : (9.20245×10 15 )/x       

       FIG. 17  is a diagram illustrating an example of the preferred range for the bulk donor concentration N Bre  in a case where ε′ is in Range F (0.002 or more, and 0.05 or less). Note that the upper limit  311  and the lower limit  312  of the donor concentration N Fre  (/cm 3 ) are the same as those in the example of  FIG. 12 . The upper limit  313  of the bulk donor concentration N Bre  is a value obtained by multiplying the upper limit  311  of the donor concentration N Fre  (/cm 3 ) by an upper limit value (0.05) of ε′. The lower limit  314  of the bulk donor concentration N Bre  is a value obtained by multiplying the lower limit  312  of the donor concentration N Fre  (/cm 3 ) by a lower limit value (0.002) of ε′. The upper limit  313  and the lower limit  314  of the bulk donor concentration N Bre  are as follows.
         Lower limit  314 : (1.84049×10 13 )/x   Upper limit  313 : (4.60123×10 15 )/x       

       FIG. 18  is a diagram illustrating an example of the preferred range for the bulk donor concentration N Bre  in a case where ε′ is in Range G (0.005 or more, and 0.02 or less). Note that the upper limit  311  and the lower limit  312  of the donor concentration N Fre  (/cm 3 ) are the same as those in the example of  FIG. 12 . The upper limit  313  of the bulk donor concentration N Bre  is a value obtained by multiplying the upper limit  311  of the donor concentration N Fre  (/cm 3 ) by an upper limit value (0.02) of ε′. The lower limit  314  of the bulk donor concentration N Bre  is a value obtained by multiplying the lower limit  312  of the donor concentration N Fre  (/cm 3 ) by a lower limit value (0.005) of ε′. The upper limit  313  and the lower limit  314  of the bulk donor concentration N Bre  are as follows.
         Lower limit  314 : (4.60123×10 13 )/x   Upper limit  313 : (1.84049×10 15 )/x       

       FIG. 19  is a diagram illustrating an example of the preferred range for the bulk donor concentration N Bre  in a case where ε′ is in Range H (0.01±0.002). Note that the upper limit  311  and the lower limit  312  of the donor concentration N Fre  (/cm 3 ) are the same as those in the example of  FIG. 12 . The upper limit  313  of the bulk donor concentration N Bre  is a value obtained by multiplying the upper limit  311  of the donor concentration N Fre  (/cm 3 ) by an upper limit value (0.01) of ε′. The lower limit  314  of the bulk donor concentration N Bre  is a value obtained by multiplying the lower limit  312  of the donor concentration N Fre  (/cm 3 ) by a lower limit value (0.01) of ε′. The upper limit  313  and the lower limit  314  of the bulk donor concentration N Bre  are as follows.
         Lower limit  314 : (9.20245×10 13 )/x   Upper limit  313 : (9.20245×10 14 )/x       

     Note that the upper limit  313  and the lower limit  314  in each range may have a width of ±20%. 
     As illustrated in  FIG. 12  to  FIG. 19 , when the bulk donor concentration N Bre  is set to a concentration between the upper limit  313  and the lower limit  314  in each example, γ indicating the variation in the final donor concentration N Fre  can be suppressed within the allowable range. Note that the curve of the lower limit  314  may be smaller than the intrinsic carrier concentration. Here, the intrinsic carrier concentration is 1.45×10 10 /cm 3  at room temperature (for example, 300 K). When the value of the curve of the lower limit  314  is smaller than the intrinsic carrier concentration, the lower limit  314  may be replaced with the intrinsic carrier concentration. 
       FIG. 20  is an example of a top view of the semiconductor device  100 .  FIG. 20  illustrates a position where each member is projected on the upper surface of a semiconductor substrate  10 . In  FIG. 20 , only some members of the semiconductor device  100  are illustrated, and some members are omitted. 
     The semiconductor device  100  includes the semiconductor substrate  10  described with reference to  FIG. 1  to  FIG. 19 . The semiconductor substrate  10  has an end side  102  in a top view. In the present specification, when simply referred to as a top view, it means viewing from the upper surface side of the semiconductor substrate  10 . The semiconductor substrate  10  of the present example has two sets of end sides  102  facing each other in a top view. In  FIG. 20 , the X axis and the Y axis are parallel to one of the end sides  102 . The Z axis is perpendicular to the upper surface of the semiconductor substrate  10 . 
     The semiconductor substrate  10  is provided with an active portion  160 . The active portion  160  is a region through which a main current flows in the depth direction between the upper surface and the lower surface of the semiconductor substrate  10  when the semiconductor device  100  operates. An emitter electrode is provided above the active portion  160 , but is omitted in  FIG. 20 . 
     In the active portion  160 , there is provided at least one of a transistor portion  70  which includes a transistor device such as an IGBT, and a diode portion  80  which includes a diode device such as a freewheeling diode (FWD). In the example of  FIG. 20 , the transistor portion  70  and the diode portion  80  are disposed alternately along a predetermined arrangement direction (the X axis direction in the present example) in the upper surface of the semiconductor substrate  10 . In another example, only one of the transistor portion  70  and the diode portion  80  may be provided in the active portion  160 . 
     In  FIG. 20 , a region where the transistor portion  70  is disposed is denoted by a symbol “I”, and a region where the diode portion  80  is disposed is denoted by a symbol “F”. In the present specification, a direction perpendicular to the arrangement direction in a top view may be referred to as an extending direction (Y axis direction in  FIG. 20 ). Each of the transistor portion  70  and the diode portion  80  may have a longitudinal length in the extending direction. That is, the length of the transistor portion  70  in the Y axis direction is larger than the width thereof in the X axis direction. Similarly, the length of the diode portion  80  in the Y axis direction is larger than the width thereof in the X axis direction. The extending direction of the transistor portion  70  and the diode portion  80  may be the same as the longitudinal direction of each trench portion to be described later. 
     The diode portion  80  has an N+ type cathode region in a region in contact with the lower surface of the semiconductor substrate  10 . In the present specification, a region where the cathode region is provided is referred to as the diode portion  80 . That is, the diode portion  80  is a region overlapping the cathode region in a top view. On the lower surface of the semiconductor substrate  10 , a P+ type collector region may be provided in a region other than the cathode region. In the present specification, an extension region  81  obtained by extending the diode portion  80  in the Y axis direction to a gate runner to be described later may also be included in the diode portion  80 . A collector region is provided in a lower surface of the extension region  81 . 
     The transistor portion  70  has a P+ type collector region in a region in contact with the lower surface of the semiconductor substrate  10 . In the transistor portion  70 , a gate structure including an N type emitter region, a P type base region, a gate conductive portion, and a gate dielectric film is periodically disposed on the upper surface side of the semiconductor substrate  10 . 
     The semiconductor device  100  may have one or more pads above the semiconductor substrate  10 . The semiconductor device  100  of the present example includes a gate pad  164 . The semiconductor device  100  may have pads such as an anode pad, a cathode pad, and a current detection pad. Each pad is disposed in the vicinity of the end side  102 . The vicinity of the end side  102  refers to a region between the end side  102  and the emitter electrode in a top view. At the time of mounting the semiconductor device  100 , each pad may be connected to an external circuit via wiring such as a wire. 
     A gate potential is applied to the gate pad  164 . The gate pad  164  is electrically connected to the conductive portion of the gate trench portion of the active portion  160 . The semiconductor device  100  includes a gate runner that connects the gate pad  164  and the gate trench portion. In  FIG. 20 , the gate runner is hatched with oblique lines. 
     The gate runner of the present example includes an outer peripheral gate runner  130  and an active-side gate runner  129 . The outer peripheral gate runner  130  is disposed between the active portion  160  and the end side  102  of the semiconductor substrate  10  in a top view. The outer peripheral gate runner  130  of the present example surrounds the active portion  160  in a top view. A region surrounded by the outer peripheral gate runner  130  in a top view may be set as the active portion  160 . The outer peripheral gate runner  130  is connected to the gate pad  164 . The outer peripheral gate runner  130  is disposed above the semiconductor substrate  10 . The outer peripheral gate runner  130  may be a metal wiring containing aluminum or the like. 
     The active-side gate runner  129  is provided in the active portion  160 . With the provision of the active-side gate runner  129  in the active portion  160 , it is possible to reduce a variation in wiring length from the gate pad  164  in each region of the semiconductor substrate  10 . 
     The active-side gate runner  129  is connected to the gate trench portion of the active portion  160 . The active-side gate runner  129  is disposed above the semiconductor substrate  10 . The active-side gate runner  129  may be a wiring formed of a semiconductor such as polysilicon doped with impurities. 
     The active-side gate runner  129  may be connected to the outer peripheral gate runner  130 . The active-side gate runner  129  of the present example is provided to extend in the X axis direction from one outer peripheral gate runner  130  to the other outer peripheral gate runner  130  so as to cross the active portion  160  at substantially the center in the Y axis direction. In a case where the active portion  160  is divided by the active-side gate runner  129 , the transistor portion  70  and the diode portion  80  may be alternately disposed in the X axis direction in each divided region. 
     The semiconductor device  100  may be provided with a temperature sense portion (not illustrated) which is a PN junction diode formed of polysilicon or the like, and a current detection portion (not illustrated) which simulates the operation of the transistor portion provided in the active portion  160 . 
     The semiconductor device  100  of the present example includes an edge termination structure portion  90  between the active portion  160  and the end side  102 . The edge termination structure portion  90  of the present example is disposed between the outer peripheral gate runner  130  and the end side  102 . The edge termination structure portion  90  reduces electric field strength on the upper surface side of the semiconductor substrate  10 . The edge termination structure portion  90  includes a plurality of guard rings  92 . The guard ring  92  is a P type region in contact with the upper surface of the semiconductor substrate  10 . The guard ring  92  may surround the active portion  160  in a top view. The plurality of guard rings  92  are disposed at predetermined intervals between the outer peripheral gate runner  130  and the end side  102 . The guard ring  92  disposed on the outer side may surround the guard ring  92  disposed on the inner side by one. The outer side refers to a side close to the end side  102 , and the inner side refers to a side close to the outer peripheral gate runner  130 . By providing the plurality of guard rings  92 , the depletion layer on the upper surface side of the active portion  160  can be extended outward, and the breakdown voltage of the semiconductor device  100  can be improved. The edge termination structure portion  90  may further include at least one of a field plate, and a RESURF annularly provided surrounding the active portion  160 . 
       FIG. 21  is an enlarged view of a region A in  FIG. 20 . The region A is a region including the transistor portion  70 , the diode portion  80 , and the active-side gate runner  129 . The semiconductor device  100  of the present example includes a gate trench portion  40 , a dummy trench portion  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 the semiconductor substrate  10 . Each of the gate trench portion  40  and the dummy trench portion  30  is an example of the trench portion. The semiconductor device  100  of the present example includes an emitter electrode  52  and the active-side gate runner  129  provided above the upper surface of the semiconductor substrate  10 . The emitter electrode  52  and the active-side gate runner  129  are provided separately from each other. 
     An interlayer dielectric film is provided between the emitter electrode  52  and the active-side gate runner  129 , and the upper surface of the semiconductor substrate  10 , but is omitted in  FIG. 21 . In the interlayer dielectric film of the present example, a contact hole  54  is provided through the interlayer dielectric film. In  FIG. 21 , each contact hole  54  is hatched with oblique lines. 
     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  is in contact with the emitter region  12 , the contact region  15 , and the base region  14  in the upper surface of the semiconductor substrate  10  through the contact hole  54 . The emitter electrode  52  is connected to a dummy conductive portion in the dummy trench portion  30  through a contact hole provided in the interlayer dielectric film. The emitter electrode  52  may be connected to the dummy conductive portion of the dummy trench portion  30  at the edge of the dummy trench portion  30  in the Y axis direction. 
     The active-side gate runner  129  is connected to the gate trench portion  40  through a contact hole provided in the interlayer dielectric film. The active-side gate runner  129  may be connected to the gate conductive portion of the gate trench portion  40  at an edge portion  41  of the gate trench portion  40  in the Y axis direction. The active-side gate runner  129  is not connected to the dummy conductive portion in the dummy trench portion  30 . 
     The emitter electrode  52  is formed of a material containing metal.  FIG. 21  illustrates a range in which the emitter electrode  52  is provided. For example, at least a partial region of the emitter electrode  52  is formed of aluminum or an aluminum-silicon alloy, for example, 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 in a lower layer of a region formed of aluminum or the like. Further, in the contact hole, there may be provided a plug formed by embedding tungsten or the like so as to be in contact with the barrier metal and aluminum or the like. 
     The well region  11  is provided to overlap with the active-side gate runner  129 . The well region  11  is also provided to extend with a predetermined width in a range not overlapping with the active-side gate runner  129 . The well region  11  of the present example is provided away from the end of the contact hole  54  in the Y axis direction toward the active-side gate runner  129 . The well region  11  is a region of a second conductivity type having a doping concentration higher than that of the base region  14 . The base region  14  of the present example is a P− type, and the well region  11  is a P+ type. 
     Each of the transistor portion  70  and the diode portion  80  has a plurality of trench portions arranged in the arrangement direction. In the transistor portion  70  of the present example, one or more gate trench portions  40  and one or more dummy trench portions  30  are alternately provided along the arrangement direction. In the diode portion  80  of the present example, a plurality of dummy trench portions  30  are provided along the arrangement direction. The diode portion  80  of the present example is not provided with the gate trench portion  40 . 
     The gate trench portion  40  of the present example may have two straight portions  39  (portions of the trenches which are straight along the extending direction) extending along the extending direction perpendicular to the arrangement direction and the edge portion  41  connecting the two straight portions  39 . The extending direction in  FIG. 21  is the Y axis direction. 
     At least a part of the edge portion  41  is preferably provided in a curved shape in a top view. By connecting the end portions of the two straight portions  39  in the Y axis direction to each other by the edge portion  41 , electric field strength at the end portion of the straight portion  39  can be reduced. 
     In the transistor portion  70 , the dummy trench portion  30  is provided between the straight portions  39  of the gate trench portion  40 . One dummy trench portion  30  may be provided between the straight portions  39 , and a plurality of dummy trench portions  30  may be provided. The dummy trench portion  30  may have a linear shape extending in the extending direction, and may have a straight portion  29  and an edge portion  31  similar to the gate trench portion  40 . The semiconductor device  100  illustrated in  FIG. 21  includes both the linear dummy trench portion  30  not having the edge portion  31  and the dummy trench portion  30  having the edge portion  31 . 
     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 end portions of the gate trench portion  40  and the dummy trench portion  30  in the Y axis direction are provided in the well region  11  in a top view. That is, the bottom portion of each trench portion in the depth direction is covered with the well region  11  at the end portion of each trench portion in the Y axis direction. As a result, electric field strength at the bottom portion of each trench portion can be reduced. 
     A mesa portion is provided between the trench portions in the arrangement direction. The mesa portion refers to a region sandwiched between the trench portions inside the semiconductor substrate  10 . 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. The mesa portion of the present example is provided to extend in the extending direction (Y axis direction) along the trench in the upper surface of the semiconductor substrate  10 . In the present example, the transistor portion  70  is provided with a mesa portion  60 , and the diode portion  80  is provided with a mesa portion  61 . When simply referring to as a mesa portion in the present specification, the mesa portion refers to each of the mesa portion  60  and the mesa portion  61 . 
     The base region  14  is provided in each mesa portion. In the base region  14  exposed to the upper surface of the semiconductor substrate  10  in the mesa portion, a region disposed closest to the active-side gate runner  129  is defined as a base region  14 - e.  In  FIG. 21 , the base region  14 - e  disposed at one end portion of each mesa portion in the extending direction is illustrated, but the base region  14 - e  is also disposed at the other end portion of each mesa portion. In each mesa portion, at least one of the emitter region  12  of the first conductivity type and the contact region  15  of the second conductivity type may be provided in a region sandwiched between the base regions  14 - e  in a top view. The emitter region  12  of the present example is an N+ type, and the contact region  15  is a 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. 
     The mesa portion  60  of the transistor portion  70  has the emitter region  12  exposed to 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 the contact region  15  exposed to the upper surface of the semiconductor substrate  10 . 
     Each of the contact region  15  and the emitter region  12  in the mesa portion  60  is 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  of the mesa portion  60  are alternately disposed along the extending direction (Y axis direction) of the trench portion. 
     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 extending 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 . 
     The emitter region  12  is not provided in the mesa portion  61  of the diode portion  80 . The base region  14  and the contact region  15  may be provided in the upper surface of the mesa portion  61 . The contact region  15  may be provided in contact with each of the base regions  14 - e  in a region sandwiched between the base regions  14 - e  in the upper surface of the mesa portion  61 . The base region  14  may be provided in a region sandwiched between the contact regions  15  in the upper surface of the mesa portion  61 . The base region  14  may be disposed in the entire region sandwiched between the contact regions  15 . 
     The contact hole  54  is provided above each mesa portion. The contact hole  54  is disposed in a region sandwiched between the base regions  14 - e.  The contact hole  54  of the present example is provided above each region of the contact region  15 , the base region  14 , and the emitter region  12 . The contact hole  54  is not provided in a region corresponding to the base region  14 - e  and the well region  11 . The contact hole  54  may be disposed at the center in the arrangement direction (X axis direction) of the mesa portion  60 . 
     In the diode portion  80 , an N+ type cathode region  82  is provided in a region adjacent to the lower surface of the semiconductor substrate  10 . In the lower surface of the semiconductor substrate  10 , a P+ type collector region  22  may be provided in a region where the cathode region  82  is not provided. In  FIG. 21 , the boundary between the cathode region  82  and the collector region  22  is indicated by a dotted line. 
     The cathode region  82  is disposed away from the well region  11  in the Y axis direction. As a result, a distance between the P type region (well region  11 ) having a relatively high doping concentration and formed up to a deep position and the cathode region  82  is secured, and the breakdown voltage can be improved. The end portion of the cathode region  82  in the Y axis direction of the present example is disposed farther from the well region  11  than the end portion of the contact hole  54  in the Y axis direction. In another example, the end portion of the cathode region  82  in the Y axis direction may be disposed between the well region  11  and the contact hole  54 . 
       FIG. 22A  is a diagram illustrating an example of a cross section b-b in  FIG. 21 . The cross section b-b is an XZ plane passing through the emitter region  12  and the cathode region  82 . The semiconductor device  100  of the present example includes the semiconductor substrate  10 , an interlayer dielectric film  38 , the emitter electrode  52 , and a collector electrode  24  in the cross section. The interlayer dielectric film  38  is provided in the upper surface of the semiconductor substrate  10 . The interlayer dielectric film  38  is a film including at least one of a dielectric film such as silicate glass to which an impurity such as boron or phosphorus is added, a thermal oxide film, and other dielectric films. The interlayer dielectric film  38  is provided with the contact hole  54  described in  FIG. 21 . 
     The emitter electrode  52  is provided above the interlayer dielectric film  38 . The emitter electrode  52  is in contact with the upper surface  21  of the semiconductor substrate  10  through the contact hole  54  of the interlayer dielectric film  38 . The collector electrode  24  is provided in 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 the present specification, a direction (Z axis direction) connecting the emitter electrode  52  and the collector electrode  24  is referred to as a depth direction. 
     The semiconductor substrate  10  has an N type drift region  19 . The drift region  19  of the present example is an N type region from the lower end of the accumulation region  16  to the upper end of the buffer region  20 . The drift region  19  of the present example has the high-concentration region  150  described in  FIG. 1  to  FIG. 19 . In  FIG. 22A , the high-concentration region  150  is hatched with oblique lines. The high-concentration region  150  may be provided in the transistor portion  70 , may be provided in the diode portion  80 , or may be provided in both the transistor portion  70  and the diode portion  80 . The high-concentration region  150  is a region provided from the upper end of the buffer region  20  toward the upper surface  21 . The impurity chemical concentration peak  141  (see  FIG. 1  or the like) is disposed at the upper end portion of the high-concentration region  150 . 
     The drift region  19  may have an N type bulk donor region  18 . The bulk donor region  18  is a region where the doping concentration coincides with the donor concentration of the bulk donor. The bulk donor region  18  is a region disposed above the high-concentration region  150 . The bulk donor region  18  in the present example is provided in each of the transistor portion  70  and the diode portion  80 . 
     In the mesa portion  60  of the transistor portion  70 , an N+ type emitter region  12  and a P− type base region  14  are provided in order from the upper surface  21  side of the semiconductor substrate  10 . The bulk donor region  18  is provided below the base region  14 . The mesa portion  60  may be provided with an N+ type accumulation region  16 . The accumulation region  16  is disposed between the base region  14  and the bulk donor region  18 . 
     The emitter region  12  is exposed to 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 doping concentration higher than that of the bulk donor region  18 . 
     The base region  14  is provided below the emitter region  12 . The base region  14  of the present example 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 . 
     The accumulation region  16  is provided below the base region  14 . The accumulation region  16  is an N+ type region having a doping concentration higher than that of the drift region  19 . The accumulation region  16  may have a doping concentration higher than that of the high-concentration region  150 . By providing the high-concentration accumulation region  16  between the drift region  19  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 . 
     The mesa portion  61  of the diode portion  80  is provided with a P− type base region  14  in contact with the upper surface  21  of the semiconductor substrate  10 . The bulk donor region  18  is provided below the base region  14 . In the mesa portion  61 , the accumulation region  16  may be provided below the base region  14 . 
     In each of the transistor portion  70  and the diode portion  80 , an N+ type buffer region  20  is provided on the lower surface  23  side of the high-concentration region  150 . The structure of the buffer region  20  is the same as that of the buffer region  20  described in  FIG. 1  to  FIG. 19 . The buffer region  20  may function as a field stop layer that prevents a depletion layer spreading from the lower end of the base region  14  from reaching the P+ type collector region  22  and the N+ type cathode region  82 . 
     In the transistor portion  70 , the P+ type collector region  22  is provided below the buffer region  20 . The collector region  22  is an example of the lower surface region  201  described in  FIG. 1  to  FIG. 19 . 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 , and may contain a different acceptor. The acceptor of the collector region  22  is, for example, boron. 
     In the diode portion  80 , the N+ type cathode region  82  is provided below the buffer region  20 . The cathode region  82  is an example of the lower surface region  201  described in  FIG. 1  to  FIG. 19 . The donor concentration of the cathode region  82  is higher than the donor concentration of the high-concentration region  150 . The donor of the cathode region  82  is, for example, hydrogen or phosphorus. Note that elements to be donors and acceptors in each region are not limited to the examples described above. The collector region  22  and the cathode region  82  are exposed to the lower surface  23  of the semiconductor substrate  10  and are connected to the collector electrode  24 . The collector electrode  24  may be in contact with the entire lower surface  23  of the semiconductor substrate  10 . The emitter electrode  52  and the collector electrode  24  are formed of a metal material such as aluminum. 
     One or more gate trench portions  40  and one or more dummy trench portions  30  are provided on the upper surface  21  side of the semiconductor substrate  10 . Each trench portion penetrates the base region  14  from the upper surface  21  of the semiconductor substrate  10  to reach the drift region  19 . In the region where at least one of the emitter region  12 , the contact region  15 , and the accumulation region  16  is provided, each trench portion also penetrates these doping regions and reaches the bulk donor region  18 . The trench portion penetrating the doping region is not limited to those manufactured in the order of forming the doping region and then forming the trench portion. The doping region formed between the trench portions after forming the trench portions includes a doping region where the trench portion penetrates. 
     As described above, the transistor portion  70  is provided with the gate trench portion  40  and the dummy trench portion  30 . The diode portion  80  is provided with the dummy trench portion  30  and is not provided with the gate trench portion  40 . In the present example, the boundary between the diode portion  80  and the transistor portion  70  in the X axis direction is the boundary between the cathode region  82  and the collector region  22 . 
     The gate trench portion  40  includes a gate trench, a gate dielectric film  42 , and a gate conductive portion  44  provided in the upper surface  21  of the semiconductor substrate  10 . The gate dielectric film  42  is provided to cover the inner wall of the gate trench. The gate dielectric film  42  may be formed by oxidizing or nitriding the semiconductor in the inner wall of the gate trench. The gate conductive portion  44  is provided on the inner side of the gate dielectric film  42  inside the gate trench. That is, the gate dielectric film  42  insulates the gate conductive portion  44  from the semiconductor substrate  10 . The gate conductive portion  44  is formed of a conductive material such as polysilicon. 
     The gate conductive portion  44  may be provided longer than the base region  14  in the depth direction. The gate trench portion  40  in the cross section is covered with the interlayer dielectric film  38  in the upper surface  21  of the semiconductor substrate  10 . The gate conductive portion  44  is electrically connected to the gate runner. If a predetermined gate voltage is applied to the gate conductive portion  44 , a channel by an inversion layer of electrons is formed in a surface layer of the interface in contact with the gate trench portion  40  in the base region  14 . 
     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 provided in the upper surface  21  of the semiconductor substrate  10 , a dummy dielectric film  32 , and a dummy conductive portion  34 . The dummy conductive portion  34  may be connected to an electrode different from the gate pad. For example, the dummy conductive portion  34  may be connected to a dummy pad (not illustrated) connected to an external circuit different from the gate pad, and control different from that of the gate conductive portion  44  may be performed. The dummy conductive portion  34  may be electrically connected to the emitter electrode  52 . The dummy dielectric film  32  is provided to cover the inner wall of the dummy trench. The dummy conductive portion  34  is provided inside the dummy trench and is provided on the inner side of the dummy dielectric film  32 . The dummy dielectric 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 as the gate conductive portion  44  in the depth direction. 
     The gate trench portion  40  and the dummy trench portion  30  of the present example are covered with the interlayer dielectric film  38  on the upper surface  21  of the semiconductor substrate  10 . Note that the bottom portions of the dummy trench portion  30  and the gate trench portion  40  may be a curved surface shape protruding downward (a curved shape in a cross section). 
     The semiconductor substrate  10  has the same distributions of the impurity chemical concentration C I , the hydrogen chemical concentration C H , and the doping concentration D d  as in any of the examples described in  FIG. 1  to  FIG. 19 . According to the semiconductor device  100  of the present example, by providing the high-concentration region  150 , it is possible to suppress the variation in the doping concentration in the drift region  19 . 
       FIG. 22B  is a diagram illustrating an example of the distribution of the doping concentration D d  in line d-d of  FIG. 22A . The line d-d is a line parallel to the Z axis passing through the collector region  22  and the mesa portion  60 . The distribution of the doping concentration D d  in the present example is the same as the distribution of the doping concentration D d  illustrate in  FIG. 2  from the collector region  22  to the doping concentration peak  121 . The doping concentration D d  of the present example has concentration peaks in each of the accumulation region  16 , the base region  14 , and the emitter region  12 . The semiconductor substrate  10  of the present example includes the bulk donor region  18  between the accumulation region  16  and the doping concentration peak  121 . The bulk donor region  18  may be in contact with the accumulation region  16 . That is, at the boundary between the bulk donor region  18  and the accumulation region  16 , the doping concentration D d  may be continuously increased from the bulk donor concentration D b  to the local maximum of the concentration peak of the accumulation region  16 . 
       FIG. 23  is a diagram illustrating another example of the cross section b-b in  FIG. 21 . The semiconductor device  100  of the present example differs from the example of  FIG. 22A  in that the high-concentration region  150  is provided over the entire drift region  19 . Other structures may be the same as in the example of  FIG. 22A . 
     The high-concentration region  150  of the present example may be provided from the upper end of the buffer region  20  to a position in contact with the accumulation region  16 . The high-concentration region  150  may be formed up to the inside of the accumulation region  16 . In this case, the doping concentration peak  121  may be disposed in the accumulation region  16 . In a case where the semiconductor device  100  does not include the accumulation region  16 , the high-concentration region  150  may be provided up to a position in contact with the base region  14 . According to the present example, the variation in the doping concentration can be suppressed over the entire drift region  19 . 
     While the embodiments of the present invention have been described, the technical scope of the invention is not limited to the above described embodiments. It is apparent to persons skilled in the art that various alterations and improvements can be added to the above-described embodiments. It is also apparent from the scope of the claims that the embodiments added with such alterations or improvements can be included in the technical scope of the invention. 
     The operations, procedures, steps, and stages of each process performed by an apparatus, system, program, and method shown in the claims, embodiments, or diagrams can be performed in any order as long as the order is not indicated by “prior to,” “before,” or the like and as long as the output from a previous process is not used in a later process. Even if the process flow is described using phrases such as “first” or “next” in the claims, embodiments, or diagrams, it does not necessarily mean that the process must be performed in this order. 
     EXPLANATION OF REFERENCES 
       10 : semiconductor substrate;  11 : well region;  12 : emitter region;  14 : base region;  15 : contact region;  16 : accumulation region;  18 : bulk donor region;  19 : drift region;  20 : buffer region;  21 : upper surface;  22 : collector region;  23 : lower surface;  24 : collector electrode;  29 : straight portion;  30 : dummy trench portion;  31 : edge portion;  32 : dummy dielectric film;  34 : dummy conductive portion;  38 : interlayer dielectric film;  39 : straight portion;  40 : gate trench portion;  41 : edge portion;  42 : gate dielectric film;  44 : gate conductive portion;  52 : emitter electrode;  54 : contact hole;  60 ,  61 : mesa portion;  70 : transistor portion;  80 : diode portion;  81 : extension region;  82 : cathode region;  90 : edge termination structure portion;  92 : guard ring;  100 : semiconductor device;  102 : end side;  106 : passed-through region;  111 : doping concentration peak;  112 : lower tail;  113 : upper tail;  114 : gradient;  121 : doping concentration peak;  122 : lower tail;  123 : upper tail;  124 : gradient;  125 : gradient;  129 : active-side gate runner;  130 : outer peripheral gate runner;  131 : hydrogen chemical concentration peak;  132 : lower tail;  133 : upper tail;  134 : gradient;  141 : Impurity chemical concentration peak;  142 : lower tail;  143 : upper tail;  144 : gradient;  145 : gradient;  150 : high-concentration region;  160 : active portion;  164 : gate pad;  171 : chemical concentration peak;  181 : low concentration region;  201 : lower surface region;  211 : first defect density peak;  212 : second defect density peak;  213 : defect density peak;  311 : upper limit;  312 : lower limit;  313 : upper limit;  314 : lower limit