Semiconductor device

Abstract

Provided is a semiconductor device including a first doping concentration peak farthest from a bottom surface of a semiconductor substrate, and a second doping concentration peak second farthest from the bottom surface. When the integrated concentration of Si-H donors at the first doping concentration peak is N1, the integrated concentration of CiOi-H donors between the first doping concentration peak and the second doping concentration peak is NCOH, the carbon chemical concentration of the semiconductor substrate is NC and N is defined as N=N1+NCOH, a predetermined conditional expression is satisfied.

Description

Semiconductor Devices

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

[0002] Techniques for forming semiconductor devices such as transistors on a semiconductor substrate are known (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent Document 1] International Publication No. 2016 / 204227 [Patent Document 2] Japanese Patent Application Laid-Open No. 2022-062443 General disclosure

[0003] (Problem to be Solved) In a semiconductor device, it is preferable that the variation in doping concentration in the semiconductor substrate is small.

[0004] In order to solve the above problems, a first aspect of the present invention provides a semiconductor device. The semiconductor device may include a semiconductor substrate having an upper surface and a lower surface and containing carbon. Any of the above semiconductor devices may include a plurality of hydrogen concentration peaks arranged side by side in a depth direction in the semiconductor substrate. Any of the above semiconductor devices may include a plurality of doping concentration peaks arranged corresponding to the plurality of hydrogen concentration peaks. In any of the above semiconductor devices, the plurality of doping concentration peaks may include a first doping concentration peak farthest from the lower surface and a second doping concentration peak second farthest from the lower surface. In any of the above semiconductor devices, the integrated concentration of Si—H donors at the first doping concentration peak may be set to N １ and the integral concentration of the CiOi-H donor between the first doping concentration peak and the second doping concentration peak is N ＣＯＨ and the carbon chemical concentration of the semiconductor substrate is N Ｃ Let N=N １ +N ＣＯＨ In any of the above semiconductor devices, the following conditional expression may be satisfied: N Ｃ ≦1.5×10 １５ / cm ３ In the case of N ＣＯＨ / N≦0.2×N Ｃ x10 －１５ +0.35 N Ｃ >1.5 x 10 １５ / cm ３ In the case of N ＣＯＨ / N≦0.65

[0005] In any of the above semiconductor devices, the following conditional expression may be satisfied: Ｃ ≦1.5×10 １５ / cm ３ In the case of N ＣＯＨ / N≦0.133×N Ｃ x10 －１５ +0.3 N Ｃ >1.5 x 10 １５ / cm ３ In the case of N ＣＯＨ / N≦0.5

[0006] In any of the semiconductor devices described above, the plurality of doping concentration peaks may include two doping concentration peaks that are adjacent to each other in the depth direction and have a maximum distance therebetween. In any of the semiconductor devices described above, the integral concentration of Si—H donors at the doping concentration peak that is farther from the bottom surface out of the two doping concentration peaks may be set to N １ and the integral concentration of the CiOi-H donors between the two doping concentration peaks is N ＣＯＨ Even if so, the above conditional expression may be satisfied.

[0007] In any of the above semiconductor devices, the plurality of doping concentration peaks may include a minimum doping concentration peak where the doping concentration is minimum, and a first adjacent doping concentration peak adjacent to the minimum doping concentration peak on the lower surface side. １ and the integral concentration of the CiOi-H donor between the minimum doping concentration peak and the first adjacent doping concentration peak is N ＣＯＨ Even if so, the above conditional expression may be satisfied.

[0008] In any of the above semiconductor devices, among the plurality of doping concentration peaks, each of the doping concentration peaks from the first doping concentration peak to a third doping concentration peak that is second closest to the bottom surface may be set as a target doping concentration peak. In any of the above semiconductor devices, the doping concentration peak adjacent to the target doping concentration peak on the bottom surface side may be set as a second adjacent doping concentration peak. In any of the above semiconductor devices, the integrated concentration of Si—H donors at the target doping concentration peak may be set as N １ and the integrated concentration of the CiOi-H donor between the target doping concentration peak and the second adjacent doping concentration peak is N ＣＯＨ In any of the above semiconductor devices, the conditional expression may be satisfied for all of the target doping concentration peaks.

[0009] In any of the above semiconductor devices, the distance of the first doping concentration peak from the lower surface in the depth direction may be 30% or more and 50% or less of the thickness of the semiconductor substrate in the depth direction.

[0010] In any of the above semiconductor devices, the depth direction distance between the first doping concentration peak and the second doping concentration peak may be 5% or more and 20% or less of the depth direction distance from the lower surface of the first doping concentration peak.

[0011] In any of the above semiconductor devices, the distance between the first doping concentration peak and the second doping concentration peak in the depth direction may be 1 μm or more and 20 μm or less.

[0012] In any of the above semiconductor devices, the oxygen chemical concentration of the semiconductor substrate is 1×10 １７ / cm ３ That's it, 5 x 10 １７ / cm ３ It may be the following:

[0013] In any of the above semiconductor devices, the carbon chemical concentration of the semiconductor substrate is 5×10 １５ / cm ３ It may be the following:

[0014] In any of the above semiconductor devices, the semiconductor substrate may have a first conductivity type drift region and a buffer region provided between the drift region and the lower surface and having a doping concentration higher than that of the drift region, and the first doping concentration peak may be located in the buffer region.

[0015] A second aspect of the present invention provides a semiconductor device. The semiconductor device may include a semiconductor substrate having an upper surface and a lower surface and containing carbon. Any of the semiconductor devices may include a plurality of hydrogen concentration peaks arranged in a line in a depth direction in the semiconductor substrate. Any of the semiconductor devices may include a plurality of doping concentration peaks arranged corresponding to the plurality of hydrogen concentration peaks. In any of the semiconductor devices, the plurality of doping concentration peaks may include a first doping concentration peak farthest from the lower surface and a second doping concentration peak second farthest from the lower surface. In any of the semiconductor devices, the integrated concentration of Si—H donors at the first doping concentration peak may be expressed as N １ and the integral concentration of the CiOi-H donor between the first doping concentration peak and the second doping concentration peak is N ＣＯＨ and the carbon chemical concentration of the semiconductor substrate is N Ｃ Let N=N １ +N ＣＯＨ When N is set, the following conditional expression may be satisfied. ＣＯＨ / N≦8.286E−02×ln(N Ｃ )-4.656E-01

[0016] Any of the above semiconductor devices may satisfy the following conditional expression: ＣＯＨ / N≦7.185E−02×ln(N Ｃ )-4.260E-01

[0017] A third aspect of the present invention provides a semiconductor device. The semiconductor device may include a semiconductor substrate having an upper surface and a lower surface and containing carbon and oxygen. Any of the semiconductor devices may include a plurality of hydrogen concentration peaks arranged in a line in a depth direction in the semiconductor substrate. Any of the semiconductor devices may include a plurality of doping concentration peaks arranged corresponding to the plurality of hydrogen concentration peaks. In any of the semiconductor devices, the plurality of doping concentration peaks may include a first doping concentration peak farthest from the lower surface and a second doping concentration peak second farthest from the lower surface. In any of the semiconductor devices, the integrated concentration of Si—H donors at the first doping concentration peak may be expressed as N １ and the integral concentration of the CiOi-H donor between the first doping concentration peak and the second doping concentration peak is N ＣＯＨ and the carbon chemical concentration of the semiconductor substrate is N Ｃ and the oxygen chemical concentration of the semiconductor substrate is N ＯＸ Let N=N １ +N ＣＯＨ When N is set, the following conditional expression may be satisfied. ＣＯＨ / N≦8.080E−02×ln(x)−2.926 where x=N ＯＸ ×{(N Ｃ / 1E15)×exp(N ＯＸ / 1E17)]

[0018] Any of the above semiconductor devices may satisfy the following conditional expression: ＣＯＨ / N≦6.120E−02×ln(x)−2.194

[0019] The above summary of the invention does not list all of the necessary features of the present invention. In addition, subcombinations of these features may also constitute inventions.

[0020] 1 is a top view showing an example of a semiconductor device 100 according to an embodiment of the present invention; FIG. 2 is an enlarged view of region D in FIG. 1; FIG. 3 is a view showing an example of a cross section taken along the line ff in FIG. 2; FIG. 4 is a view showing an example of a hydrogen chemical concentration distribution 220 and a doping concentration distribution 210 taken along the line ff in FIG. 3; FIG. 5 is a view explaining a method for estimating the concentrations of interstitial Si—H donors and CiOi—H donors; FIG. 6 is a view showing the results of measuring the ratio of CiOi—H donors; and FIG. 7 is a view showing the variation N of the integral value N of the hydrogen donor concentration under each implantation condition. ｍａｘ / N ｍｉｎ The graph shows the variation N of the integral value N of the hydrogen donor concentration and the CiOi-H donor ratio. ｍａｘ / N ｍｉｎ The graph shows the relationship between the CiOi-H donor ratio and the variation N of the integral value N of the hydrogen donor concentration. ｍａｘ / N ｍｉｎ 1 is a diagram showing the relationship between the variation N ｍａｘ / N ｍｉｎ is set to 1.3, the CiOi-H donor ratio at each carbon chemical concentration is plotted with hexagonal marks. ｍａｘ / N ｍｉｎ 1 is a diagram showing boundary lines corresponding to conditions for making the C0I ratio 1.7 or less, 1.5 or less, or 1.3 or less. FIG. 2 is a diagram showing curves obtained by fitting the CiOi-H donor ratio with the common logarithm of the carbon concentration for each of implantation conditions 1 to 7. FIG. 3 is a diagram showing a plot of the CiOi-H donor ratio with the substrate concentration index Ic as the horizontal axis for each of implantation conditions 1 to 7. FIG. 4 is a diagram showing an example of a doping concentration distribution in the buffer region 20 according to one embodiment of the present invention. FIG. 5 is a diagram showing an example of a doping concentration distribution in the buffer region 20 according to a reference example.

[0021] The present invention will be described below through embodiments of the invention, but the following embodiments do not limit the scope of the invention as claimed. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0022] In this specification, one side in a direction parallel to the depth direction of a semiconductor substrate is referred to as "upper" and the other side as "lower." Of the two main surfaces of a substrate, layer, or other member, one surface is referred to as the upper surface and the other surface is referred to as the lower surface. The directions of "upper" and "lower" are not limited to the direction of gravity or the directions when the semiconductor device is mounted.

[0023] In this specification, technical matters may be explained using orthogonal coordinate axes of the X-axis, Y-axis, and Z-axis. The orthogonal coordinate axes merely identify the relative positions of components and do not limit a specific direction. For example, the Z-axis does not limit the height direction relative to the ground. Note that the +Z-axis direction and the -Z-axis direction are opposite directions. When the Z-axis direction is described without specifying positive or negative, it means a direction parallel to the +Z-axis and -Z-axis.

[0024] In this specification, orthogonal axes parallel to the upper and lower surfaces of the semiconductor substrate are referred to as the X-axis and Y-axis. Furthermore, an axis perpendicular to the upper and lower surfaces of the semiconductor substrate is referred to as the Z-axis. In this specification, the direction of the Z-axis may be referred to as the depth direction. Furthermore, in this specification, the direction parallel to the upper and lower surfaces of the semiconductor substrate, including the X-axis and Y-axis, may be referred to as the horizontal direction.

[0025] The region from the center of the semiconductor substrate in the depth direction to the top surface of the semiconductor substrate may be referred to as the top surface side. Similarly, the region from the center of the semiconductor substrate in the depth direction to the bottom surface of the semiconductor substrate may be referred to as the bottom surface side.

[0026] In this specification, when we say "same" or "equal," it may also include cases where there is an error due to manufacturing variations, etc. The error is, for example, within 10%.

[0027] In this specification, the conductivity type of a doped region doped with an impurity is described as P-type or N-type. In this specification, the impurity may particularly mean either an N-type donor or a P-type acceptor, and may be referred to as a dopant. In this specification, doping means introducing a donor or an acceptor into a semiconductor substrate to form a semiconductor exhibiting an N-type conductivity or a P-type conductivity.

[0028] In this specification, the doping concentration means the concentration of donors or acceptors in a thermal equilibrium state. In this specification, the net doping concentration means the net concentration obtained by adding together the donor concentration as the concentration of positive ions and the acceptor concentration as the concentration of negative ions, taking into account the polarity of the charge. As an example, the donor concentration is N Ｄ , acceptor concentration is N Ａ Then, the net doping concentration at any position is N Ｄ -N Ａ In this specification, the net doping concentration may be simply referred to as the doping concentration.

[0029] A donor has the function of supplying electrons to a semiconductor. An acceptor has the function of receiving electrons from a semiconductor. Donors and acceptors are not limited to impurities themselves. For example, interstitial Si—H, in which interstitial silicon (Si-i) and hydrogen are bonded in a silicon semiconductor, and CiOi-H, in which interstitial carbon (Ci), interstitial oxygen (Oi), and hydrogen are bonded, function as donors that supply electrons. In this specification, CiOi-H or interstitial Si—H may be referred to as hydrogen donors.

[0030] In this specification, the semiconductor substrate has N-type bulk donors distributed throughout. The bulk donors are donors due to dopants contained substantially uniformly in the ingot that is the base of the semiconductor substrate when the ingot is manufactured. In this example, the bulk donors are elements other than hydrogen. The dopants of the bulk donors include, but are not limited to, phosphorus, antimony, arsenic, selenium, or sulfur. In this example, the bulk donors are phosphorus. The bulk donors are also contained in the P-type region. The semiconductor substrate may be a wafer cut from a semiconductor ingot, or may be a chip obtained by dividing the wafer. The semiconductor ingot may be manufactured by any of the Czochralski method (CZ method), the magnetic field-applied Czochralski method (MCZ method), and the float zone method (FZ method). The ingot in this example is manufactured by the MCZ method. The oxygen concentration contained in the substrate manufactured by the MCZ method is 1×10 １７ ~7 x 10 １７ / cm３ The oxygen concentration in the substrate manufactured by the FZ method is 1×10 １５ ~5 x 10 １６ / cm ３ The higher the oxygen concentration, the more likely it is that hydrogen donors are generated. The bulk donor concentration may be the chemical concentration of bulk donors distributed throughout the semiconductor substrate, or may be a value between 90% and 100% of the chemical concentration. Alternatively, a non-doped substrate that does not contain dopants such as phosphorus may be used as the semiconductor substrate. In this case, the bulk donor concentration (D0) of the non-doped substrate is, for example, 1×10 １０ / cm ３ That's it, 5 x 10 １２ / cm ３ The bulk donor concentration (D0) of the non-doped substrate is preferably 1×10 １１ / cm ３ The bulk donor concentration (D0) of the non-doped substrate is preferably 5×10 １２ / cm ３ The concentrations in the present invention may be values ​​at room temperature, for example, values ​​at 300 K (Kelvin) (approximately 26.9° C.).

[0031] In this specification, when P+ type or N+ type is described, it means that the doping concentration is higher than that of P type or N type, and when P- type or N- type is described, it means that the doping concentration is lower than that of P type or N type. Furthermore, when P++ type or N++ type is described in this specification, it means that the doping concentration is higher than that of P+ type or N+ type. The unit system in this specification is the SI unit system unless otherwise specified. The unit of length may be expressed in cm, but various calculations may be performed after converting to meters (m).

[0032] In this specification, chemical concentration refers to the atomic density of an impurity measured regardless of its state of electrical activation. Chemical concentration can be measured, for example, by secondary ion mass spectrometry (SIMS). The net doping concentration can be measured by voltage-capacitance measurement (CV). The carrier concentration measured by spreading resistance measurement (SR) may also be used as the net doping concentration. The carrier concentration measured by CV or SR may be used as a value in a thermal equilibrium state. In addition, since the donor concentration in an N-type region is sufficiently greater than the acceptor concentration, the carrier concentration in that region may also be used as the donor concentration. Similarly, in a P-type region, the carrier concentration in that region may also be used as the acceptor concentration. In this specification, the doping concentration in an N-type region may also be referred to as the donor concentration, and the doping concentration in a P-type region may also be referred to as the acceptor concentration.

[0033] When the concentration distribution of the donor, acceptor, or net doping has a peak, the peak value may be taken as the concentration of the donor, acceptor, or net doping in that region. In cases where the concentration of the donor, acceptor, or net doping is almost uniform, the average value of the concentration of the donor, acceptor, or net doping in that region may be taken as the concentration of the donor, acceptor, or net doping. In this specification, the concentration per unit volume is expressed in atoms / cm. ３ , or / cm ３ This unit is used for donor or acceptor concentration or chemical concentration in a semiconductor substrate. The atoms notation may be omitted.

[0034] The carrier concentration measured by the SR method may be lower than the concentration of donors or acceptors. In the range where current flows when measuring spreading resistance, the carrier mobility of the semiconductor substrate may be lower than the value in the crystalline state. The reduction in carrier mobility occurs when carriers are scattered due to disorder in the crystal structure caused by lattice defects or the like.

[0035] The donor or acceptor concentration calculated from the carrier concentration measured by the CV method or the SR method may be lower than the chemical concentration of the element representing the donor or acceptor. As an example, the donor concentration of phosphorus or arsenic, which acts as a donor in a silicon semiconductor, or the acceptor concentration of boron, which acts as an acceptor, is about 99% of the chemical concentration. On the other hand, the donor concentration of hydrogen, which acts as a donor in a silicon semiconductor, is about 0.1% to 10% of the chemical concentration of hydrogen.

[0036] Fig. 1 is a top view showing an example of a semiconductor device 100 according to an embodiment of the present invention. Fig. 1 shows the positions of each component projected onto the top surface of a semiconductor substrate 10. Fig. 1 shows only some of the components of the semiconductor device 100, and some components are omitted.

[0037] The semiconductor device 100 includes a semiconductor substrate 10. The semiconductor substrate 10 is a substrate made of a semiconductor material. As an example, the semiconductor substrate 10 is a silicon substrate. The semiconductor substrate 10 has end edges 162 in a top view. In this specification, the term "top view" simply refers to a view from the top surface side of the semiconductor substrate 10. The semiconductor substrate 10 in this example has two pairs of end edges 162 that face each other in a top view. In FIG. 1 , the X-axis and Y-axis are parallel to either of the end edges 162. The Z-axis is perpendicular to the top surface of the semiconductor substrate 10.

[0038] An active portion 160 is provided in the semiconductor substrate 10. The active portion 160 is a region through which a main current flows in the depth direction between the upper and lower surfaces of the semiconductor substrate 10 when the semiconductor device 100 is in operation. An emitter electrode is provided above the active portion 160, but is omitted from FIG. 1 . The active portion 160 may refer to a region that overlaps with the emitter electrode in a top view. The active portion 160 may also include a region sandwiched between the active portions 160 in a top view.

[0039] The active section 160 is provided with at least one of a transistor section 70 including a transistor element such as an insulated gate bipolar transistor (IGBT) and a diode section 80 including a diode element such as a free wheel diode (FWD). In the example of FIG. 1 , the transistor sections 70 and the diode sections 80 are alternately arranged along a predetermined arrangement direction (in this example, the X-axis direction) on the top surface of the semiconductor substrate 10. The semiconductor device 100 of this example is a reverse conducting IGBT (RC-IGBT).

[0040] In FIG. 1 , the region where the transistor section 70 is arranged is marked with the symbol "I," and the region where the diode section 80 is arranged is marked with the symbol "F." In this specification, the direction perpendicular to the arrangement direction in a top view may be referred to as the extension direction (the Y-axis direction in FIG. 1 ). The transistor section 70 and the diode section 80 may each have a longitudinal direction in the extension direction. In other words, the length of the transistor section 70 in the Y-axis direction is greater than the width in the X-axis direction. Similarly, the length of the diode section 80 in the Y-axis direction is greater than the width in the X-axis direction. The extension direction of the transistor section 70 and the diode section 80 may be the same as the longitudinal direction of each trench section, which will be described later.

[0041] The diode section 80 has an N+ type cathode region in a region that contacts the lower surface of the semiconductor substrate 10. In this specification, the region in which the cathode region is provided is referred to as the diode section 80. In other words, the diode section 80 is a region that overlaps with the cathode region in a top view. A P+ type collector region may be provided in a region of the lower surface of the semiconductor substrate 10 other than the cathode region. In this specification, an extension region 81 that extends the diode section 80 in the Y-axis direction to the gate wiring described below may also be included in the diode section 80. A collector region is provided on the lower surface of the extension region 81.

[0042] The transistor section 70 has a P+ type collector region in a region in contact with the lower surface of the semiconductor substrate 10. The transistor section 70 also has a gate structure, which has an N type emitter region, a P type base region, a gate conductive portion, and a gate insulating film, periodically arranged on the upper surface side of the semiconductor substrate 10.

[0043] The semiconductor device 100 may have one or more pads above the semiconductor substrate 10. The semiconductor device 100 of this example has a gate pad 164. The semiconductor device 100 may also have pads such as an anode pad, a cathode pad, and a current detection pad. Each pad is disposed near an edge 162. The vicinity of the edge 162 refers to the region between the edge 162 and the emitter electrode in a top view. When the semiconductor device 100 is mounted, each pad may be connected to an external circuit via wiring such as a wire.

[0044] A gate potential is applied to the gate pad 164. The gate pad 164 is electrically connected to a conductive portion of the gate trench portion of the active portion 160. The semiconductor device 100 includes a gate wiring that connects the gate pad 164 and the gate trench portion. In FIG. 1, the gate wiring is hatched with diagonal lines.

[0045] The gate wiring in this example has a peripheral gate wiring 130 and an active-side gate wiring 131. The peripheral gate wiring 130 is disposed between the active portion 160 and an edge 162 of the semiconductor substrate 10 in a top view. The peripheral gate wiring 130 in this example surrounds the active portion 160 in a top view. The region surrounded by the peripheral gate wiring 130 in a top view may be the active portion 160. In addition, a well region is formed below the gate wiring. The well region is a P-type region with a higher concentration than a base region, which will be described later, and is formed from the top surface of the semiconductor substrate 10 to a position deeper than the base region. The region surrounded by the well region in a top view may be the active portion 160.

[0046] The peripheral gate wiring 130 is connected to the gate pad 164. The peripheral gate wiring 130 is disposed above the semiconductor substrate 10. The peripheral gate wiring 130 may be a metal wiring containing aluminum or the like.

[0047] The active side gate wiring 131 is provided in the active section 160. By providing the active side gate wiring 131 in the active section 160, it is possible to reduce variations in wiring length from the gate pad 164 for each region of the semiconductor substrate 10.

[0048] The peripheral gate wiring 130 and the active side gate wiring 131 are connected to the gate trench portion of the active portion 160. The peripheral gate wiring 130 and the active side gate wiring 131 are disposed above the semiconductor substrate 10. The peripheral gate wiring 130 and the active side gate wiring 131 may be wiring formed of a semiconductor such as polysilicon doped with impurities.

[0049] The active side gate wiring 131 may be connected to the peripheral gate wiring 130. In this example, the active side gate wiring 131 extends in the X axis direction from one peripheral gate wiring 130 to the other peripheral gate wiring 130 that sandwich the active section 160, crossing the active section 160 at approximately the center in the Y axis direction. When the active section 160 is divided by the active side gate wiring 131, the transistor section 70 and the diode section 80 may be arranged alternately in the X axis direction in each divided region.

[0050] The semiconductor device 100 may include a temperature sensing section (not shown) which is a PN junction diode formed of polysilicon or the like, and a current detecting section (not shown) which simulates the operation of a transistor section provided in the active section 160.

[0051] In the present example, the semiconductor device 100 includes an edge termination structure 90 between the active section 160 and the edge 162 when viewed from above. The edge termination structure 90 in the present example is disposed between the peripheral gate wiring 130 and the edge 162. The edge termination structure 90 relieves electric field concentration on the upper surface side of the semiconductor substrate 10. The edge termination structure 90 may include at least one of a guard ring, a field plate, and a resurf, which are arranged in an annular shape surrounding the active section 160.

[0052] 2 is an enlarged view of region D in FIG. 1 . Region D includes a transistor section 70, a diode section 80, and an active-side gate wiring 131. The semiconductor device 100 of this example includes a gate trench section 40, a dummy trench section 30, a well region 11, an emitter region 12, a base region 14, and a contact region 15 provided inside the upper surface side of the semiconductor substrate 10. The gate trench section 40 and the dummy trench section 30 are each an example of a trench section. The semiconductor device 100 of this example also includes an emitter electrode 52 and an active-side gate wiring 131 provided above the upper surface of the semiconductor substrate 10. The emitter electrode 52 and the active-side gate wiring 131 are provided separately from each other.

[0053] An interlayer insulating film is provided between the emitter electrode 52 and the active side gate wiring 131 and the upper surface of the semiconductor substrate 10, but is not shown in Fig. 2. In this example, contact holes 54 are provided in the interlayer insulating film so as to penetrate the interlayer insulating film. In Fig. 2, each contact hole 54 is hatched with diagonal lines.

[0054] The emitter electrode 52 is provided above the gate trench portion 40, the dummy trench portion 30, the well region 11, the emitter region 12, the base region 14, and the contact region 15. The emitter electrode 52 contacts the emitter region 12, the contact region 15, and the base region 14 on the upper surface of the semiconductor substrate 10 through a contact hole 54. The emitter electrode 52 is also connected to a dummy conductive portion in the dummy trench portion 30 through a contact hole provided in the interlayer insulating film. The emitter electrode 52 may be connected to the dummy conductive portion of the dummy trench portion 30 at the tip of the dummy trench portion 30 in the Y-axis direction. The dummy conductive portion of the dummy trench portion 30 does not need to be connected to the emitter electrode 52 and the gate conductive portion, and may be controlled to a potential different from the potential of the emitter electrode 52 and the potential of the gate conductive portion.

[0055] The active side gate wiring 131 is connected to the gate trench portion 40 through a contact hole provided in the interlayer insulating film. The active side gate wiring 131 may be connected to the gate conductive portion of the gate trench portion 40 at the tip portion 41 of the gate trench portion 40 in the Y-axis direction. The active side gate wiring 131 is not connected to the dummy conductive portion in the dummy trench portion 30.

[0056] The emitter electrode 52 is made of a material containing metal. FIG. 2 shows the area where the emitter electrode 52 is provided. For example, at least a portion of the emitter electrode 52 is made of aluminum or an aluminum-silicon alloy, such as a metal alloy such as AlSi or AlSiCu. The emitter electrode 52 may have a barrier metal made of titanium, a titanium compound, or the like below the region made of aluminum or the like. Furthermore, the contact hole may have a plug formed by embedding tungsten or the like so as to contact the barrier metal and aluminum or the like.

[0057] The well region 11 is provided so as to overlap with the active side gate wiring 131. The well region 11 is also provided so as to extend by a predetermined width into an area where it does not overlap with the active side gate wiring 131. In this example, the well region 11 is provided away from the end of the contact hole 54 in the Y-axis direction toward the active side gate wiring 131. The well region 11 is a region of a second conductivity type having a higher doping concentration than the base region 14. In this example, the base region 14 is P- type, and the well region 11 is P+ type.

[0058] Each of the transistor section 70 and the diode section 80 has a plurality of trench sections arranged in the arrangement direction. In the transistor section 70 of this example, one or more gate trench sections 40 and one or more dummy trench sections 30 are alternately provided along the arrangement direction. In the diode section 80 of this example, a plurality of dummy trench sections 30 are provided along the arrangement direction. In the diode section 80 of this example, no gate trench section 40 is provided.

[0059] The gate trench portion 40 in this example may have two straight line portions 39 (portions of the trench that are straight along the extension direction) that extend along an extension direction perpendicular to the arrangement direction, and a tip portion 41 that connects the two straight line portions 39. The extension direction in FIG. 2 is the Y-axis direction.

[0060] At least a portion of the tip portion 41 is preferably curved in a top view. By connecting the ends of the two straight portions 39 in the Y-axis direction with each other by the tip portion 41, electric field concentration at the ends of the straight portions 39 can be alleviated.

[0061] In the transistor section 70, the dummy trench section 30 is provided between each of the linear portions 39 of the gate trench section 40. One or more dummy trench sections 30 may be provided between each of the linear portions 39. The dummy trench section 30 may have a linear shape extending in the extension direction, and may have a linear section 29 and a tip section 31, similar to the gate trench section 40. The semiconductor device 100 shown in FIG. 2 includes both linear dummy trench sections 30 without tip sections 31 and dummy trench sections 30 with tip sections 31.

[0062] The diffusion depth of the well region 11 may be deeper than the depths of the gate trench portion 40 and the dummy trench portion 30. The ends of the gate trench portion 40 and the dummy trench portion 30 in the Y-axis direction are provided in the well region 11 when viewed from above. In other words, at the ends of each trench portion in the Y-axis direction, the bottom of each trench portion in the depth direction is covered by the well region 11. This makes it possible to alleviate electric field concentration at the bottom of each trench portion.

[0063] A mesa portion is provided between each trench portion in the arrangement direction. The mesa portion refers to a region inside the semiconductor substrate 10 that is sandwiched between the trench portions. As an example, the upper end of the mesa portion is the upper surface of the semiconductor substrate 10. The depth position of the lower end of the mesa portion is the same as the depth position of the lower end of the trench portion. In this example, the mesa portion is provided on the upper surface of the semiconductor substrate 10, extending in the extension direction (Y-axis direction) along the trench. In this example, the transistor portion 70 is provided with a mesa portion 60, and the diode portion 80 is provided with a mesa portion 61. In this specification, the mesa portion simply referred to as a mesa portion refers to both the mesa portion 60 and the mesa portion 61.

[0064] A base region 14 is provided in each mesa portion. Of the base regions 14 exposed on the upper surface of the semiconductor substrate 10 in the mesa portion, the region closest to the active-side gate wiring 131 is referred to as the base region 14-e. While FIG. 2 shows the base region 14-e located at one end of each mesa portion in the extension direction, a base region 14-e is also located at the other end of each mesa portion. In each mesa portion, at least one of a first-conductivity-type emitter region 12 and a second-conductivity-type contact region 15 may be provided in a region sandwiched between the base regions 14-e in a top view. In this example, the emitter region 12 is N+ type, and the contact region 15 is P+ type. The emitter region 12 and the contact region 15 may be provided between the base region 14 and the upper surface of the semiconductor substrate 10 in the depth direction.

[0065] The mesa portion 60 of the transistor portion 70 has an emitter region 12 exposed on the upper surface of the semiconductor substrate 10. The emitter region 12 is provided in contact with the gate trench portion 40. The mesa portion 60 in contact with the gate trench portion 40 may be provided with a contact region 15 exposed on the upper surface of the semiconductor substrate 10.

[0066] The contact regions 15 and the emitter regions 12 in the mesa portion 60 are each provided from one trench portion to the other trench portion in the X-axis direction. As an example, the contact regions 15 and the emitter regions 12 in the mesa portion 60 are alternately arranged along the extension direction of the trench portions (the Y-axis direction).

[0067] In another example, the contact region 15 and the emitter region 12 of the mesa portion 60 may be provided in a stripe shape along the extension direction of the trench portion (Y-axis direction). 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.

[0068] The mesa portion 61 of the diode section 80 does not have an emitter region 12. A base region 14 and a contact region 15 may be provided on the upper surface of the mesa portion 61. In the region sandwiched between the base regions 14-e on the upper surface of the mesa portion 61, a contact region 15 may be provided in contact with each of the base regions 14-e. In the region sandwiched between the contact regions 15 on the upper surface of the mesa portion 61, a base region 14 may be provided. The base region 14 may be disposed in the entire region sandwiched between the contact regions 15.

[0069] A contact hole 54 is provided above each mesa portion. The contact hole 54 is arranged in a region sandwiched between the base regions 14-e. In this example, the contact holes 54 are provided above the contact region 15, the base region 14, and the emitter region 12. The contact holes 54 are not provided in regions corresponding to the base region 14-e and the well region 11. The contact hole 54 may be arranged in the center of the arrangement direction (X-axis direction) of the mesa portions 60.

[0070] In the diode section 80, an N+ type cathode region 82 is provided in a region adjacent to the lower surface of the semiconductor substrate 10. A P+ type collector region 22 may be provided in a region of the lower surface of the semiconductor substrate 10 where the cathode region 82 is not provided. The cathode region 82 and the collector region 22 are provided between the lower surface 23 of the semiconductor substrate 10 and the buffer region 20. In FIG. 2 , the boundary between the cathode region 82 and the collector region 22 is indicated by a dotted line.

[0071] The cathode region 82 is disposed away from the well region 11 in the Y-axis direction. This ensures a distance between the cathode region 82 and a P-type region (well region 11) that has a relatively high doping concentration and is formed deep, thereby improving the breakdown voltage. In this example, the end of the cathode region 82 in the Y-axis direction is disposed farther from the well region 11 than the end of the contact hole 54 in the Y-axis direction. In another example, the end of the cathode region 82 in the Y-axis direction may be disposed between the well region 11 and the contact hole 54.

[0072] Fig. 3 is a diagram showing an example of the e-e cross section in Fig. 2. The e-e cross section is an XZ plane passing through the emitter region 12 and the cathode region 82. In this cross section, the semiconductor device 100 of this example has a semiconductor substrate 10, an interlayer insulating film 38, an emitter electrode 52, and a collector electrode 24.

[0073] The interlayer insulating film 38 is provided on the upper surface of the semiconductor substrate 10. The interlayer insulating film 38 is a film including at least one layer of an insulating film such as silicate glass doped with impurities such as boron or phosphorus, a thermal oxide film, and other insulating films. The interlayer insulating film 38 is provided with the contact holes 54 described with reference to FIG. 2 .

[0074] The emitter electrode 52 is provided above the interlayer insulating film 38. The emitter electrode 52 passes through a contact hole 54 in the interlayer insulating film 38 and contacts the upper surface 21 of the semiconductor substrate 10. The collector electrode 24 is provided on the lower surface 23 of the semiconductor substrate 10. The emitter electrode 52 and the collector electrode 24 are made of a metal material such as aluminum. In this specification, the direction connecting the emitter electrode 52 and the collector electrode 24 (the Z-axis direction) is referred to as the depth direction.

[0075] The semiconductor substrate 10 has an N-type or N-type drift region 18. The drift region 18 is provided in each of the transistor section 70 and the diode section 80.

[0076] In the mesa portion 60 of the transistor section 70, an N+ type emitter region 12 and a P- type base region 14 are provided in this order from the upper surface 21 side of the semiconductor substrate 10. A drift region 18 is provided below the base region 14. An N+ type accumulation region 16 may be provided in the mesa portion 60. The accumulation region 16 is disposed between the base region 14 and the drift region 18.

[0077] The emitter region 12 is exposed on the upper surface 21 of the semiconductor substrate 10 and is provided in contact with the gate trench portion 40. The emitter region 12 may be in contact with the trench portions on both sides of the mesa portion 60. The emitter region 12 has a higher doping concentration than the drift region 18.

[0078] The base region 14 is provided below the emitter region 12. In this example, the base region 14 is provided in contact with the emitter region 12. The base region 14 may be in contact with the trench portions on both sides of the mesa portion 60.

[0079] The accumulation region 16 is provided below the base region 14. The accumulation region 16 is an N+ type region with a higher doping concentration than the drift region 18. That is, the accumulation region 16 has a higher donor concentration than the drift region 18. By providing the high-concentration accumulation region 16 between the drift region 18 and the base region 14, the carrier injection enhancement effect (IE effect) can be enhanced and the on-voltage can be reduced. The accumulation region 16 may be provided so as to cover the entire lower surface of the base region 14 in each mesa portion 60.

[0080] A P-type base region 14 is provided in the mesa portion 61 of the diode section 80 in contact with the upper surface 21 of the semiconductor substrate 10. A drift region 18 is provided below the base region 14. An accumulation region 16 may be provided below the base region 14 in the mesa portion 61.

[0081] In each of the transistor section 70 and the diode section 80, an N+ type buffer region 20 may be provided below the drift region 18. The doping concentration of the buffer region 20 is higher than the doping concentration of the drift region 18. The buffer region 20 may have a concentration peak with a higher doping concentration than the drift region 18. The doping concentration of the concentration peak refers to the doping concentration at the apex of the concentration peak. Furthermore, the doping concentration of the drift region 18 may be the average value of the doping concentration in a region where the doping concentration distribution is approximately flat.

[0082] The buffer region 20 may have two or more concentration peaks in the depth direction (Z-axis direction) of the semiconductor substrate 10. The concentration peak of the buffer region 20 may be located at the same depth as the chemical concentration peak of hydrogen (protons) or phosphorus, for example. The buffer region 20 may function as a field stop layer that prevents the depletion layer extending from the lower end of the base region 14 from reaching the P+ type collector region 22 and the N+ type cathode region 82.

[0083] In the transistor section 70, a P+ type collector region 22 is provided below the buffer region 20. The acceptor concentration of the collector region 22 is higher than the acceptor concentration of the base region 14. The collector region 22 may contain the same acceptor as the base region 14, or may contain a different acceptor. The acceptor of the collector region 22 is, for example, boron.

[0084] In the diode section 80, an N+ type cathode region 82 is provided below the buffer region 20. The donor concentration of the cathode region 82 is higher than the donor concentration of the drift region 18. The donor of the cathode region 82 is, for example, hydrogen or phosphorus. Note that the elements that serve as donors and acceptors in each region are not limited to the above-mentioned examples. The collector region 22 and the cathode region 82 are exposed on the lower surface 23 of the semiconductor substrate 10 and 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.

[0085] One or more gate trenches 40 and one or more dummy trenches 30 are provided on the upper surface 21 of the semiconductor substrate 10. Each trench extends from the upper surface 21 of the semiconductor substrate 10, penetrating the base region 14, to below the base region 14. In regions where at least one of the emitter region 12, the contact region 15, and the accumulation region 16 is provided, each trench also penetrates these doped regions. The trenches penetrating the doped regions do not necessarily mean that the trenches are formed in the order of forming the doped regions and then the trenches. The trenches penetrating the doped regions also include trenches formed in the order of forming the trenches and then forming the doped regions.

[0086] As described above, the transistor section 70 is provided with the gate trench section 40 and the dummy trench section 30. The diode section 80 is provided with the dummy trench section 30, but is not provided with the gate trench section 40. In this example, the boundary between the diode section 80 and the transistor section 70 in the X-axis direction is the boundary between the cathode region 82 and the collector region 22.

[0087] The gate trench portion 40 has a gate trench provided on the upper surface 21 of the semiconductor substrate 10, a gate insulating film 42, and a gate conductive portion 44. The gate insulating film 42 is provided to cover the inner wall of the gate trench. The gate insulating film 42 may be formed by oxidizing or nitriding the semiconductor on the inner wall of the gate trench. The gate conductive portion 44 is provided inside the gate trench and further inside than the gate insulating film 42. In other words, the gate insulating film 42 insulates the gate conductive portion 44 from the semiconductor substrate 10. The gate conductive portion 44 is formed of a conductive material such as polysilicon.

[0088] The gate conductive portion 44 may be provided to be longer in the depth direction than the base region 14. The gate trench portion 40 in this cross section is covered with an interlayer insulating film 38 on the upper surface 21 of the semiconductor substrate 10. The gate conductive portion 44 is electrically connected to the gate wiring. When a predetermined gate voltage is applied to the gate conductive portion 44, a channel is formed by an electron inversion layer in the surface layer of the interface of the base region 14 that contacts the gate trench portion 40.

[0089] The dummy trench portion 30 may have the same structure as the gate trench portion 40 in the cross section. The dummy trench portion 30 includes a dummy trench, a dummy insulating film 32, and a dummy conductive portion 34 provided on the upper surface 21 of the semiconductor substrate 10. The dummy conductive portion 34 is electrically connected to the emitter electrode 52. The dummy insulating film 32 covers the inner wall of the dummy trench. The dummy conductive portion 34 is provided inside the dummy trench and is provided further inward than the dummy insulating film 32. The dummy insulating film 32 insulates the dummy conductive portion 34 from the semiconductor substrate 10. The dummy conductive portion 34 may be formed of the same material as the gate conductive portion 44. For example, the dummy conductive portion 34 is formed of a conductive material such as polysilicon. The dummy conductive portion 34 may have the same length in the depth direction as the gate conductive portion 44.

[0090] The gate trench portion 40 and the dummy trench portion 30 in this example are covered with an interlayer insulating film 38 on the upper surface 21 of the semiconductor substrate 10. The bottoms of the dummy trench portion 30 and the gate trench portion 40 may have a downwardly convex curved shape (a curved shape in cross section).

[0091] FIG. 4 shows an example of a hydrogen chemical concentration distribution 220 and a doping concentration distribution 210 along the ff line in FIG. 3. In the concentration distribution graphs in FIG. 4 and elsewhere, the carrier concentration measured by the SR method or the like is taken as the doping concentration. The vertical axis in FIG. 4 is a common logarithm (log) scale for both the hydrogen chemical concentration distribution 220 and the doping concentration distribution 210. The horizontal axis in FIG. 4 (depth position) is a linear scale. The ff line is a line parallel to the Z axis passing through the buffer region 20. The horizontal axis in FIG. 4 indicates the depth position (position in the Z axis direction) within the semiconductor substrate 10. In the concentration distribution graphs in FIG. 4 and elsewhere, the bottom end position of the buffer region 20 is taken as the reference position (0) in the Z axis direction, and the distance from the reference position is taken as the position in the Z axis direction. At the bottom end position of the buffer region 20, there is a valley in the doping concentration distribution due to the PN junction between the collector region 22 and the buffer region 20, but this valley is omitted in FIG. 4 and elsewhere.

[0092] The entire semiconductor substrate 10 contains bulk donors. The concentration of the bulk donors is denoted by BD. The doping concentration of the drift region 18 may be the same as or different from the bulk donor concentration BD. The buffer region 20 has a higher doping concentration than the drift region 18.

[0093] The semiconductor substrate 10 has a plurality of hydrogen concentration peaks 221 arranged in a line in the depth direction. The hydrogen concentration peaks 221 are mountain-shaped portions of the distribution 220 where the hydrogen chemical concentration shows a maximum value in the depth direction. One or more hydrogen concentration peaks 221 may be provided in the buffer region 20. At least one hydrogen concentration peak 221 may be provided closer to the upper surface 21 than the buffer region 20. In this example, all of the hydrogen concentration peaks 221 are provided in the buffer region 20.

[0094] The semiconductor substrate 10 has a plurality of doping concentration peaks 201 arranged corresponding to a plurality of hydrogen concentration peaks 221. The doping concentration peaks 201 are mountain-shaped portions of the distribution 210 where the doping concentration exhibits a maximum value in the depth direction. The number of doping concentration peaks 201 may be two or more, three or more, four or more, or five or more. In regions where the hydrogen chemical concentration is high, many hydrogen donors are formed, and therefore, doping concentration peaks 201 are formed corresponding to the hydrogen concentration peaks 221. A doping concentration peak 201 may be provided for at least one hydrogen concentration peak 221. In this example, a doping concentration peak 201 is provided for each of the hydrogen concentration peaks 221.

[0095] Of the multiple doping concentration peaks 201 corresponding to the hydrogen concentration peak 221, the peak farthest from the lower surface 23 is designated as the first doping concentration peak 201-1, and the peak second farthest from the lower surface 23 is designated as the second doping concentration peak 201-2. Similarly, the peak kth farthest from the lower surface 23 is designated as the kth doping concentration peak 201-k. The region between the kth doping concentration peak 201-k and the (k+1)th doping concentration peak 201-(k+1) is designated as the kth inter-peak region 202-k. The inter-peak region 202 may include a portion where the doping concentration exhibits a minimum value. The doping concentration in the inter-peak region 202 is also higher than the doping concentration in the drift region 18.

[0096] The correspondence between the hydrogen concentration peak 221 and the doping concentration peak 201 may mean that the apex of one concentration peak is located within the full width at half maximum of the other concentration peak. When the hydrogen concentration peak 221 and the doping concentration peak 201 correspond to each other, the distance between the apexes of the two concentration peaks may be 2 μm or less, 1 μm or less, or 0.5 μm or less.

[0097] At least one doping concentration peak 201 may be provided in the buffer region 20. A first doping concentration peak 201-1 may be located in the buffer region 20. All doping concentration peaks 201 may be located in the buffer region 20.

[0098] The buffer region 20 may or may not have a doping concentration peak other than the doping concentration peak 201. In other words, the buffer region 20 may or may not have a doping concentration peak formed by a donor other than a hydrogen donor. All doping concentration peaks in the buffer region 20 in this example are doping concentration peaks 201 formed by a hydrogen donor. In the concentration distribution examples other than that of FIG. 4 , the hydrogen chemical concentration distribution 220 is omitted, but a hydrogen concentration peak 221 is provided for all doping concentration peaks 201.

[0099] By implanting hydrogen ions into the semiconductor substrate 10, hydrogen donors are formed near the implantation position of the hydrogen ions and in the region through which the hydrogen ions have passed. In the example of FIG. 4 , hydrogen ions are implanted from the bottom surface 23 to depth positions Z1, Z2, Z3, and Z4. High concentrations of hydrogen donors are formed near depth positions Z1 to Z4, and hydrogen donors are also formed in the region through which the hydrogen ions have passed from the bottom surface 23 to depth position Z1. This forms multiple doping concentration peaks 201 and one or more inter-peak regions 202. The hydrogen ions may be implanted from the top surface 21 of the semiconductor substrate 10.

[0100] The doping concentration in each region of the semiconductor substrate 10 affects the characteristics of the semiconductor device 100. For example, the doping concentration in the buffer region 20 affects the breakdown voltage of the semiconductor device 100. For this reason, it is preferable that the concentration variation of hydrogen donors formed by implanting hydrogen ions is small. However, the concentration of hydrogen donors varies depending on the carbon concentration of the semiconductor device 100, etc. In particular, in an MCZ substrate with a high oxygen concentration, the concentration variation of hydrogen donors tends to increase due to the variation in carbon concentration.

[0101] The hydrogen donors include interstitial Si—H donors and CiOi—H donors. Because the CiOi—H donors contain carbon, the concentration of the CiOi—H donors is affected by the carbon chemical concentration of the semiconductor substrate 10. On the other hand, the concentration of the interstitial Si—H donors is relatively less affected by the carbon chemical concentration of the semiconductor substrate 10. Therefore, by making the concentration of the interstitial Si—H donors relatively high and the concentration of the CiOi—H donors relatively low, the effect of the carbon chemical concentration of the semiconductor substrate 10 is reduced, and the concentration of the hydrogen donors can be controlled with high precision.

[0102] When hydrogen ions are implanted under the same implantation conditions into semiconductor substrates 10 with different carbon chemical concentrations, the increase in doping concentration at the doping concentration peak 201 varies relatively little with the carbon chemical concentration, while the increase in doping concentration at the inter-peak region 202 varies relatively greatly with the carbon chemical concentration. The increase in doping concentration corresponds to the concentration of hydrogen donors formed by the implantation of hydrogen ions. Therefore, it is estimated that the doping concentration peak 201 is formed mainly by interstitial Si—H donors, and the inter-peak region 202 is formed mainly by C1Oi—H donors. Therefore, the concentrations of interstitial Si—H donors and C1Oi—H donors can be estimated from the increase in doping concentration at the doping concentration peak 201 and the inter-peak region 202. The increase in doping concentration may be calculated by subtracting the bulk donor concentration BD from the doping concentration at the target position, or by subtracting the doping concentration in the drift region 18 from the doping concentration at the target position.

[0103] FIG. 5 is a diagram illustrating a method for estimating the concentrations of interstitial Si—H donors and CiOi—H donors. Each vertical axis in FIG. 5 represents the doping concentration or its increase, and all vertical axes are linear scales. In this example, the concentrations of interstitial Si—H donors and CiOi—H donors in the first doping concentration peak 201-1 and the first inter-peak region 202-1 are estimated. In the upper graph of FIG. 5, the distribution of the increase in doping concentration in the first doping concentration peak 201-1, the first inter-peak region 202-1, and the second doping concentration peak 201-2 is shown by dashed lines. In this example, the increase in doping concentration is the increase in doping concentration relative to the bulk donor concentration BD. As described above, the increase in doping concentration corresponds to the concentration of hydrogen donors.

[0104] The first doping concentration peak 201-1 is fitted with a Gaussian distribution 211-1, and the second doping concentration peak 201-2 is fitted with a Gaussian distribution 211-2. Each Gaussian distribution 211 may have a predetermined half-width at half maximum. The half-width at half maximum is, for example, 2.47 μm. In another example, the full-width at half maximum of the hydrogen concentration peak 221-k corresponding to each doping concentration peak 201-k may be used as the full-width at half maximum of each Gaussian distribution 211-k. Furthermore, the full-width at half maximum of each doping concentration peak 201-k may be used as the full-width at half maximum of each Gaussian distribution 211-k. The fitting may be performed by applying the depth position and peak concentration of each doping concentration peak 201 to the Gaussian distribution 211.

[0105] The integral concentration N obtained by integrating the concentration of each Gaussian distribution 211-k in the depth direction Ｋ is the integral concentration N of the interstitial Si—H donor at each doping concentration peak 201-k. Ｋ In the example of FIG. 5, the integrated concentration of the interstitial Si—H donors included in the first doping concentration peak 201-1 corresponds to N １ and the integrated concentration of the interstitial Si—H donors contained in the second doping concentration peak 201-2 is N ２ is.

[0106] In the region from the depth position Z1 to the depth position Z2, a residual distribution 212 obtained by subtracting the Gaussian distribution 211-1 and the Gaussian distribution 211-2 from the distribution of the increase in the doping concentration corresponds to the concentration distribution of the CiOi-H donor. The integral concentration N ＣＯＨ is the integrated concentration N of the CiOi-H donor in the region from the depth position Z1 to the depth position Z2. ＣＯＨ is equivalent to

[0107] By such a process, the integrated concentration of interstitial Si—H donors and C1Oi—H donors in the region from the depth position Z1 to the depth position Z2 can be estimated. In this specification, the integrated value N of the hydrogen donor concentration in the region is expressed as N=N １ +N ＣＯＨ In addition, the ratio of the CiOi-H donor is set to N ＣＯＨ / N. In the regions from the depth position Zk to the depth position Z(k+1), the integrated concentrations of interstitial Si—H donors and C1Oi—H donors can be estimated in a similar manner.

[0108] 6 is a diagram showing the results of measuring the ratio of the CiOi-H donor. In the example of FIG. 6, the ratio N of the CiOi-H donor was measured for a plurality of types of semiconductor devices 100 in which the hydrogen ion implantation conditions and the carbon chemical concentration of the semiconductor substrate 10 were different. ＣＯＨ / N is measured. Unless otherwise specified in this specification, the ratio of the CiOi-H donor refers to the ratio in the region from depth position Z1 to depth position Z2 described above. In FIG. 6, the horizontal axis represents the carbon chemical concentration of the semiconductor substrate 10, and the vertical axis represents the CiOi-H donor ratio. Six types of hydrogen ion implantation conditions, Conditions No. 1 to No. 6, are used. Compared with implantation conditions with higher numbers, implantation conditions with lower numbers have a larger number of depth positions into which hydrogen ions are implanted and / or a larger hydrogen ion dose for each depth position. In other words, implantation conditions with lower numbers tend to have a larger number of hydrogen concentration peaks 221 and a higher peak concentration of the hydrogen concentration peaks 221.

[0109] 6, the smaller the implantation condition number, the smaller the CiOi-H donor ratio. In other words, the CiOi-H donor ratio can be controlled by the implantation conditions of hydrogen ions.

[0110] As shown in Figure 6, the higher the carbon chemical concentration of the semiconductor substrate 10, the higher the CiOi-H donor ratio. However, as shown by implantation conditions No. 2 and No. 6, the CiOi-H donor ratio tends to saturate as the carbon chemical concentration increases. Under other implantation conditions, there are no measurement results for samples showing intermediate carbon chemical concentrations, but it is assumed that these will show a similar trend to implantation conditions No. 2 and No. 6. The CiOi-H donor also contains oxygen. Therefore, the oxygen chemical concentration of the semiconductor substrate 10 can also affect the concentration of the CiOi-H donor.

[0111] The oxygen chemical concentration of the semiconductor substrate 10 under each condition in this example is 1×10 １７ / cm ３That's it, 5 x 10 １７ / cm ３ On the other hand, the carbon chemical concentration of the semiconductor substrate 10 is 0.26×10 １５ / cm ３ That's it, 2.6 x 10 １５ / cm ３ or less. Therefore, the oxygen chemical concentration is sufficiently higher than the carbon chemical concentration. However, when the contribution rate of oxygen to the formation of the CiOi-H donor is relatively low, it is conceivable that the concentration of the CiOi-H donor is rate-limited by the oxygen chemical concentration. Similarly, it is conceivable that the concentration of the CiOi-H donor is rate-limited by the hydrogen chemical concentration. For these reasons, it is considered that the CiOi-H donor ratio tends to saturate as the carbon chemical concentration increases.

[0112] FIG. 7 shows the variation N of the integral value N of the hydrogen donor concentration under each implantation condition. ｍａｘ / N ｍｉｎ 7 shows condition No. 7 in addition to conditions No. 1 to No. 6 described in FIG. 6. The implantation conditions with smaller numbers, including condition No. 7, have at least one of a larger number of depth positions where hydrogen ions are implanted and a larger dose of hydrogen ions at each depth position than the implantation conditions with larger numbers. The maximum value of the integral value N of the hydrogen donor concentration under each implantation condition is N ｍａｘ , the minimum value is N ｍｉｎ The higher the carbon chemical concentration of the semiconductor substrate 10, the more hydrogen donors tend to be formed. In the example of FIG. 6, the integral value N of the sample with the lowest carbon chemical concentration of the semiconductor substrate 10 under each implantation condition is the minimum value N ｍｉｎ The integral value N of the sample having the maximum carbon chemical concentration in the semiconductor substrate 10 is the maximum value N ｍａｘ As shown in FIGS. 6 and 7, the lower the implantation condition of the CiOi-H donor ratio, the smaller the variation N in the integral value N of the hydrogen donor concentration. ｍａｘ / N ｍｉｎ is getting smaller.

[0113] FIG. 8 shows the relationship between the CiOi-H donor ratio and the variation N of the integral value N of the hydrogen donor concentration. ｍａｘ / N ｍｉｎ8 is a graph showing the relationship between the carbon chemical concentration of the semiconductor substrate 10 and the carbon concentration of the semiconductor substrate 10. １５ / cm ３ This shows the relationship when

[0114] FIG. 9 shows the relationship between the CiOi-H donor ratio and the variation N of the integral value N of the hydrogen donor concentration. ｍａｘ / N ｍｉｎ 9 is a graph showing the relationship between the carbon chemical concentration of the semiconductor substrate 10 and the carbon concentration of the semiconductor substrate 10. １５ / cm ３ 8 and 9 show the relationship when the type of marks in each plot indicates the implantation conditions of hydrogen ions, as in the example of FIG. 7. The variation N ｍａｘ / N ｍｉｎ The values ​​shown in FIG. 7 are used.

[0115] For conditions No. 2 and No. 6, the carbon chemical concentration was 2.6 × 10 １５ / cm ３ As there are no measurement results for the case of , an estimated value is used. As shown in Figure 6, the CiOi-H donor ratio tends to saturate as the carbon chemical concentration increases. Also, as shown in Figures 6 and 7, the variation N ｍａｘ / N ｍｉｎ decreases depending on the ratio of the CiOi-H donor. ｍａｘ / N ｍｉｎ = A-B x exp(-C x [C]) function ｍａｘ / N ｍｉｎ The estimated value was calculated by approximating the above, where A, B, and C are constants and [C] is the carbon chemical concentration.

[0116] As shown in FIG. 8, when the carbon chemical concentration of the semiconductor substrate 10 is 0.26×10 １５ / cm ３ In this case, if the CiOi-H donor ratio is set to about 42%, the variation N ｍａｘ / N ｍｉｎ Similarly, when the ratio of the CiOi-H donors is set to about 37%, the variation N ｍａｘ / N ｍｉｎ Similarly, when the ratio of the CiOi-H donors is set to about 30%, the variation N ｍａｘ / Nｍｉｎ can be reduced to 1.3.

[0117] As shown in FIG. 9, when the carbon chemical concentration of the semiconductor substrate 10 is 2.6×10 １５ / cm ３ In this case, if the CiOi-H donor ratio is set to about 65%, the variation N ｍａｘ / N ｍｉｎ Similarly, when the CiOi-H donor ratio is set to about 59%, the variation N ｍａｘ / N ｍｉｎ Similarly, when the ratio of the CiOi-H donors is set to about 50%, the variation N ｍａｘ / N ｍｉｎ In both the examples of FIG. 8 and FIG. 9, the variation N ｍａｘ / N ｍｉｎ By setting the CiOi-H donor ratio so that is smaller than 1.3, the variation N ｍａｘ / N ｍｉｎ It can be seen that the increase in

[0118] FIG. 10 shows the variation N ｍａｘ / N ｍｉｎ 8, the carbon chemical concentration of the semiconductor substrate 10 is set to 0.26×10 １５ / cm ３ If ｍａｘ / N ｍｉｎ 9, when the carbon chemical concentration of the semiconductor substrate 10 is 2.6×10 １５ / cm ３ If ｍａｘ / N ｍｉｎ The CiOi-H donor ratio that makes the ratio 1.3 is 50%.

[0119] 10 also shows an example of hydrogen ion implantation condition No. 2. Curve 311 is the plot of condition No. 2. ＣＯＨ10, the position of the hexagonal plot almost coincides with the curve 311. By making the CiOi-H donor ratio equal to or less than the value shown by the curve 311, the variation N ｍａｘ / N ｍｉｎ can be suppressed to 1.3 or less.

[0120] In this example, the carbon chemical concentration of the semiconductor substrate 10 is 5×10 １５ / cm ３ A boundary line 313 is introduced in which the CiOi-H donor ratio is slightly higher than that of the curve 311 in the entire region below. By making the CiOi-H donor ratio equal to or less than the value indicated by the boundary line 313, the variation N ｍａｘ / N ｍｉｎ The carbon chemical concentration of the semiconductor substrate 10 of the semiconductor device 100 can be suppressed to 5×10 １５ / cm ３ The carbon chemical concentration of the semiconductor substrate 10 of the semiconductor device 100 may be 4×10 or less. １５ / cm ３ may be less than or equal to 3×10 １５ / cm ３ The carbon chemical concentration of the semiconductor substrate 10 of the semiconductor device 100 may be 0.1×10 or less. １５ / cm ３ or more, and may be 0.2 × 10 １５ / cm ３ It may be more than that.

[0121] Since the CiOi-H donor ratio tends to saturate as the carbon chemical concentration increases, １５ / cm ３ In the larger region, the CiOi-H donor ratio at the boundary line 313 is constant. ＣＯＨ The condition for reducing / N is expressed by (Conditional Expression 1). (Conditional Expression 1) N Ｃ ≦1.5×10 １５ / cm ３ In the case of N ＣＯＨ / N≦0.133×N Ｃ x10 －１５ +0.3 NＣ >1.5 x 10 １５ / cm ３ In the case of N ＣＯＨ / N≦0.5, where N Ｃ is the carbon chemical concentration of the semiconductor substrate 10, and N ＣＯＨ is the integral concentration of the residual distribution 212 described in FIG. 5 (corresponding to the integral concentration of the CiOi-H donor), and N=N １ +N ＣＯＨ It is. １ is the integrated concentration of Si—H donors at the first doping concentration peak 201-1 described in FIG. Ｃ The average value of the carbon chemical concentration over the entire semiconductor substrate 10 may be used.

[0122] FIG. 11 shows the variation N ｍａｘ / N ｍｉｎ The boundary line 313 corresponds to the condition for making the variation N ｍａｘ / N ｍｉｎ The boundary line 315 indicates the condition for making the variation N ｍａｘ / N ｍｉｎ The boundary line 317 indicates the condition for making the variation N ｍａｘ / N ｍｉｎ As explained in FIG. 10 and other figures, the carbon chemical concentration is 1.5×10 １５ / cm ３ In the larger region, the CiOi-H donor ratio at each boundary line was set constant. The CiOi-H donor ratio in this region corresponds to the CiOi-H donor ratio explained in Figure 9. When the carbon chemical concentration is 1.5 x 10 １５ / cm ３ In the following regions, each region was set assuming that the CiOi-H donor ratio increases linearly with increasing carbon chemical concentration.

[0123] The CiOi-H donor ratio N ＣＯＨ By lowering / N, the variation N ｍａｘ / N ｍｉｎIn this example, the condition under which the CiOi-H donor ratio becomes lower than the boundary line 315 is expressed by (Conditional Expression 2). (Conditional Expression 2) N Ｃ ≦1.5×10 １５ / cm ３ In the case of N ＣＯＨ / N≦0.173×N Ｃ x10 －１５ +0.33 N Ｃ >1.5 x 10 １５ / cm ３ In the case of N ＣＯＨ / N≦0.59

[0124] The CiOi-H donor ratio N ＣＯＨ By lowering / N, the variation N ｍａｘ / N ｍｉｎ In this example, the condition under which the CiOi-H donor ratio is lower than the boundary line 317 is expressed by (Conditional Expression 3). (Conditional Expression 3) N Ｃ ≦1.5×10 １５ / cm ３ In the case of N ＣＯＨ / N≦0.2×N Ｃ x10 －１５ +0.35 N Ｃ >1.5 x 10 １５ / cm ３ In the case of N ＣＯＨ / N≦0.65

[0125] The semiconductor device 100 may satisfy conditional formula 3, conditional formula 2, or conditional formula 1.

[0126] 12 is a graph showing curves obtained by fitting the CiOi-H donor ratio with the common logarithm of the carbon concentration for each of implantation conditions 1 to 7. Implantation conditions 1 to 7 correspond to conditions No. 1 to No. 7 shown in FIG. 7. If the CiOi-H donor ratio can be reduced to 50% or less, the variation N ｍａｘ / N ｍｉｎ In other words, if the relationship between the CiOi-H donor ratio and the carbon chemical concentration is lower than the curve of implantation condition 4, the variation N ｍａｘ / N ｍｉｎThe condition under which the CiOi-H donor ratio is lower than the curve of condition 4 is expressed by (conditional formula 4). Note that ln is the natural logarithm with base e. (conditional formula 4) N ＣＯＨ / N≦8.286×10 －２ ×ln(N Ｃ ) +0.4656

[0127] Furthermore, if the relationship between the CiOi-H donor ratio and the carbon chemical concentration is lower than the curve of implantation condition 2, the variation N ｍａｘ / N ｍｉｎ The condition under which the CiOi-H donor ratio is lower than that of the curve under condition 2 is expressed by (Conditional formula 5). (Conditional formula 5) N ＣＯＨ / N≦7.185×10 －２ ×ln(N Ｃ )+0.4260 The semiconductor device 100 may satisfy conditional expression 4. The semiconductor device 100 may satisfy conditional expression 5.

[0128] 13 is a graph plotting the C1Oi-H donor ratio with the substrate concentration index Ic on the horizontal axis for each of implantation conditions 1 to 7. The substrate concentration index Ic is the oxygen chemical concentration of the semiconductor substrate 10 in terms of N ＯＸ [ / cm ３ ], and the carbon chemical concentration of the semiconductor substrate 10 is N Ｃ [ / cm ３ ], it is defined by the following formula: Ｃ = (N ＯＸ ×[{N Ｃ / (1E15)}×exp(N ＯＸ / (1E17)) The unit of the substrate concentration index Ic defined in the above formula is [cm －３ The oxygen chemical concentration N ＯＸ may be the oxygen chemical concentration in the drift region 18. The carbon chemical concentration N Ｃ may be the carbon chemical concentration in the drift region 18. The substrate concentration index Ic may be defined by other formulas as long as they relate to at least one of the oxygen chemical concentration and the carbon chemical concentration. The substrate concentration index Ic is the oxygen chemical concentration N ＯＸ The influence of carbon chemical concentration N ＣThis is an indicator that takes into account the impact of

[0129] The concentration of the C1Oi-H donor generated in the hydrogen ion passage region is determined by the oxygen chemical concentration N ＯＸ Furthermore, the carbon chemical concentration N Ｃ In order to consider the influence of the oxygen chemical concentration N ＯＸ is multiplied by a correction factor. The correction factor is the carbon chemical concentration N Ｃ This means the effect of the carbon chemical concentration N Ｃ The effect of oxygen chemical concentration N ＯＸ In other words, a model is assumed in which the carbon chemical concentration (here, 1×10 １５ / cm ３ ) and the carbon chemical concentration N Ｃ The normalized carbon chemical concentration obtained by normalizing the above is calculated by dividing the normalized carbon chemical concentration by the predetermined oxygen chemical concentration (here, 1 × 10 １７ / cm ３ ) and the oxygen chemical concentration N ＯＸ This model allows us to analyze the effect of the correlation between the oxygen chemical concentration and the carbon chemical concentration on the C1Oi-H donor ratio.

[0130] As shown in FIG. 13, even in the substrate concentration index Ic, for example, when the substrate concentration index Ic is 5×10 １８ ( / cm ３ ) is set as the boundary value Icb, and when the substrate concentration index Ic is larger than the boundary value Icb, it can be seen that the rate of increase in the CiOi-H donor ratio becomes slow. In other words, even in the case of a substrate concentration index Ic that includes not only the carbon chemical concentration but also the oxygen chemical concentration, it can be seen that the characteristics of the CiOi-H donor ratio before and after the boundary value are similar. Therefore, the conditional expression includes the carbon chemical concentration N Ｃ The influence of the substrate concentration index Ic may be used.

[0131] As shown in FIG. 13, if the relationship between the CiOi-H donor ratio and the carbon chemical concentration is lower than the curve of implantation condition 4, the variation N ｍａｘ / N ｍｉｎThe condition under which the CiOi-H donor ratio is lower than that of the curve under condition 4 is expressed by (conditional formula 6). (conditional formula 6) N ＣＯＨ / N ≦ 8.080 × 10 －２ ×ln(I Ｃ ) -2.926

[0132] Furthermore, if the relationship between the CiOi-H donor ratio and the carbon chemical concentration is lower than the curve of implantation condition 2, the variation N ｍａｘ / N ｍｉｎ The condition under which the CiOi-H donor ratio is lower than that of the curve under condition 2 is expressed by (Conditional formula 7). (Conditional formula 7) N ＣＯＨ / N≦6.120×10 －２ ×ln(I Ｃ ) −2.194 The semiconductor device 100 may satisfy conditional expression 6 and may satisfy conditional expression 7.

[0133] The CiOi-H donor ratio N of the semiconductor device 100 ＣＯＨ As explained with reference to FIGS. 5 to 7, / N can be adjusted by the implantation conditions of hydrogen ions. For example, as shown in FIG. 5, by reducing the distance (Z1-Z2) between the first doping concentration peak 201-1 and the second doping concentration peak 201-2, the width of the inter-peak region 202 in the Z-axis direction is reduced, and the CiOi-H donor ratio is reduced. Also, by deepening the depth position Z1 of the first doping concentration peak 201-1, the first doping concentration peak 201-1 becomes gentler, the doping concentration in the inter-peak region 202 is increased, and the CiOi-H donor ratio is increased. Also, by increasing the doping concentration ( / cm ３ ), or the dose of hydrogen ions ( / cm 3 ) for forming the first doping concentration peak 201-1 ２) can also increase the concentration of Si—H donors and decrease the CiOi—H donor ratio. In addition, the degree of hydrogen diffusion inside the semiconductor substrate 10 can be adjusted by adjusting the annealing conditions after implanting hydrogen ions, thereby adjusting the CiOi—H donor ratio. For example, by increasing the annealing temperature or lengthening the annealing time, the amount of hydrogen diffusing into the inter-peak region 202 can be increased, thereby increasing the doping concentration in the inter-peak region 202 and adjusting the CiOi—H donor ratio.

[0134] 14 is a diagram showing an example of the doping concentration distribution of the buffer region 20 according to one embodiment of the present invention. The buffer region 20 in this example is formed by implanting hydrogen ions under condition No. 3. In addition, the carbon chemical concentration of the semiconductor substrate 10 is 2.6×10 １５ / cm ３ An example of this is shown by distribution 310 (dotted line), and １５ / cm ３ An example of this is shown by distribution 320 (solid line). The hydrogen ion implantation conditions for the examples of distribution 310 and distribution 320 are the same.

[0135] 15 is a diagram showing an example of the doping concentration distribution of the buffer region 20 according to a reference example. The buffer region 20 of this example is formed by implanting hydrogen ions under condition No. 5. In addition, the carbon chemical concentration of the semiconductor substrate 10 is 2.6×10 １５ / cm ３ An example of this is shown by distribution 510 (dotted line), and １５ / cm ３ An example of this is shown by distribution 520 (solid line). The hydrogen ion implantation conditions for the examples of distribution 510 and distribution 520 are the same.

[0136] 14, the distance (Z1-Z2) in the Z-axis direction between the first doping concentration peak 201-1 and the second doping concentration peak 201-2 is smaller than that in the example shown in FIG. 15. Therefore, the ratio of the C1Oi-H donors becomes relatively small. Therefore, the variation N ｍａｘ / N ｍｉｎ 11, the semiconductor device 100 under condition No. 2 can reduce the variation Nｍａｘ / N ｍｉｎ is 1.3 or less.

[0137] 15, the distance (Z1-Z2) in the Z-axis direction between the first doping concentration peak 201-1 and the second doping concentration peak 201-2 is relatively large. Therefore, the ratio of the C1Oi-H donors becomes relatively large. Therefore, the variation N ｍａｘ / N ｍｉｎ In the example of FIG. 11, the semiconductor device 100 under condition No. 5 has a variation N ｍａｘ / N ｍｉｎ is greater than 1.7.

[0138] The distance (Z1-Z2) in the depth direction between first doping concentration peak 201-1 and second doping concentration peak 201-2 may be 5% or more and 20% or less of the distance of first doping concentration peak 201-1 in the depth direction from lower surface 23. The distance (Z1-Z2) may be 15% or less, or 10% or less of the distance of first doping concentration peak 201-1 in the depth direction from lower surface 23.

[0139] The distance (Z1-Z2) may be 1 μm or more and 20 μm or less. The distance (Z1-Z2) may be 10 μm or less, 8 μm or less, or 6 μm or less. The distance (Z1-Z2) may be 10 μm or more.

[0140] The distance in the depth direction from the lower surface 23 of the first doping concentration peak 201-1 may be 30% or more and 50% or less of the thickness in the depth direction of the semiconductor substrate 10. The distance may be 35% or more of the thickness. The distance may be 45% or less of the thickness. The distance in the depth direction from the lower surface 23 of the first doping concentration peak 201-1 may be 30 μm or more and 50 μm or less. The distance may be 35 μm or more. The distance may be 45 μm or less.

[0141] The distance in the depth direction from the lower surface 23 of the second doping concentration peak 201-2 may be 20% or more, or may be 25% or more, of the thickness in the depth direction of the semiconductor substrate 10. The distance may be 20 μm or more, or may be 25 μm or more.

[0142] The doping concentrations of the first doping concentration peak 201-1 and the second doping concentration peak 201-2 are both 3×10 １４ / cm ３ The difference in doping concentration between the first doping concentration peak 201-1 and the second doping concentration peak 201-2 may be 1×10 １４ / cm ３ It may be the following:

[0143] In the above, it has been described that the CiOi-H donor ratio in the first doping concentration peak 201-1 and the first inter-peak region 202-1 satisfies any one of conditional expressions 1 to 3. For example, in the buffer region 20, the depletion layer first reaches the first doping concentration peak 201-1, which is the farthest from the lower surface 23. Therefore, if there is a large variation in the doping concentration near the first doping concentration peak 201-1, it is likely to affect the characteristics of the semiconductor device 100. In this example, by adjusting the CiOi-H donor ratio in the first doping concentration peak 201-1 and the first inter-peak region 202-1, the variation N in the region can be reduced. ｍａｘ / N ｍｉｎ Therefore, it is possible to suppress the influence on the characteristics of the semiconductor device 100. Note that the CiOi-H donor ratio may also satisfy any one of the conditional expressions 1 to 3 in the other doping concentration peaks 201-k and inter-peak regions 202-k.

[0144] The distance between adjacent doping concentration peaks 201 in the depth direction is defined as the peak-to-peak distance (Zk-Z(k+1)). Two doping concentration peaks 201 with the largest peak-to-peak distance are extracted from the multiple doping concentration peaks 201. In the example of FIG. 14, the distance (Z4-Z5) between the fourth doping concentration peak 201-4 and the fifth doping concentration peak 201-5 is the largest peak-to-peak distance.

[0145] The integral concentration of Si—H donors at the doping concentration peak 201-k, which is the one of the two extracted doping concentration peaks 201 that is located at a greater distance from the lower surface 23, is expressed as N １Furthermore, the integral concentration of the CiOi-H donor between the doping concentration peak 201-k and the doping concentration peak 201-(k+1) is defined as N ＣＯＨ In this case, any one of the conditional expressions 1 to 3 may be satisfied. According to this example, any one of the conditional expressions 1 to 3 is satisfied even in a region where the CiOi-H donor ratio is likely to be relatively high. Therefore, the variation in the concentration of hydrogen donors can be further suppressed.

[0146] In another example, a minimum doping concentration peak having the smallest doping concentration may be extracted from the plurality of doping concentration peaks 201. In the example of Fig. 14, the first doping concentration peak 201-1 is the minimum doping concentration peak. The doping concentration peak 201 adjacent to the minimum doping concentration peak on the lower surface 23 side is defined as the first adjacent doping concentration peak. In the example of Fig. 14, the second doping concentration peak 201-2 is the first adjacent doping concentration peak.

[0147] The integral concentration of Si—H donors at the minimum doping concentration peak is defined as N １ and the integral concentration of the CiOi-H donor between the minimum doping concentration peak and the first adjacent doping concentration peak is N ＣＯＨ In this case, any one of the conditional expressions 1 to 3 may be satisfied. According to this example, any one of the conditional expressions 1 to 3 is satisfied even in a region where the CiOi-H donor ratio is likely to be relatively high. Therefore, the variation in the concentration of hydrogen donors can be further suppressed.

[0148] In another example, of the multiple doping concentration peaks 201, each doping concentration peak 201 from the first doping concentration peak 201-1, which is farthest from the lower surface 23, to the third doping concentration peak 201 (sixth doping concentration peak 201-6 in the example of FIG. 14), which is second closest to the lower surface 23, is defined as a target doping concentration peak. In the example of FIG. 14, the first doping concentration peak 201-1 to the sixth doping concentration peak 201-6 are the target doping concentration peaks. For each target doping concentration peak, the doping concentration peak 201 adjacent to the lower surface 23 is defined as a second adjacent doping concentration peak. In other words, if the kth doping concentration peak 201-k is defined as the target doping concentration peak, the (k+1)th doping concentration peak 201-(k+1) is defined as the second adjacent doping concentration peak.

[0149] The integral concentration of Si—H donors at the target doping concentration peak is expressed as N １ and the integral concentration of the CiOi-H donor between the target doping concentration peak and the second adjacent doping concentration peak is N ＣＯＨ In this case, any one of the conditional expressions 1 to 3 may be satisfied for all the target doping concentration peaks. In this case, for example, the variation N ｍａｘ / N ｍｉｎ can be made smaller.

[0150] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0151] It should be noted that the order of execution of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings is not specifically stated as "before," "prior to," etc., and that the processes can be performed in any order unless the output of a previous process is used in a subsequent process. Even if the operational flow in the claims, specifications, and drawings is described using "first," "next," etc. for convenience, this does not mean that the processes must be performed in this order.

[0152] 10...Semiconductor substrate, 11...Well region, 12...Emitter region, 14...Base region, 15...Contact region, 16...Accumulation region, 18...Drift region, 20...Buffer region, 21...Upper surface, 22...Collector region, 23...Lower surface, 24...Collector electrode, 29...Straight portion, 30...Dummy trench portion, 31...Tip portion, 32...Dummy insulating film, 34...Dummy conductive portion, 38...Interlayer insulating film, 39...Straight portion, 40...Gate trench portion, 41...Tip portion, 42...Gate insulating film, 44...Gate conductive portion, 52...Emitter electrode, 54...Contact hole, 60, 61...Mesa portion , 70...Transistor portion, 80...Diode portion, 81...Extension region, 82...Cathode region, 90...Edge termination structure portion, 100...Semiconductor device, 130...Peripheral gate wiring, 131...Active side gate wiring, 160...Active portion, 162...Edge, 164...Gate pad, 201...Doping concentration peak, 202...Inter-peak region, 210...Distribution, 211...Gaussian distribution, 212...Residual distribution, 220...Distribution, 221...Hydrogen concentration peak, 310...Distribution, 311...Curve, 313...Boundary line, 315...Boundary line, 317...Boundary line, 320...Distribution, 510...Distribution, 520...Distribution

Claims

1. A semiconductor substrate having an upper surface and a lower surface and containing carbon; a plurality of hydrogen concentration peaks arranged in a line in a depth direction in the semiconductor substrate; and a plurality of doping concentration peaks arranged corresponding to the plurality of hydrogen concentration peaks, the plurality of doping concentration peaks including a first doping concentration peak farthest from the lower surface and a second doping concentration peak second farthest from the lower surface, and an integral concentration of Si-H donors at the first doping concentration peak is defined as N １ and the integral concentration of the CiOi-H donor between the first doping concentration peak and the second doping concentration peak is N ＣＯＨ The carbon chemical concentration of the semiconductor substrate is N Ｃ Let N=N １ +N ＣＯＨ If the following condition is satisfied, N Ｃ ≦1.5×10 １５ / cm ３ In the case of N ＣＯＨ / N≦0.2×N Ｃ ×10 －１５ +0.35 N Ｃ >1.5×10 １５ / cm ３ In the case of N ＣＯＨ / N≦0.65 Semiconductor device.

2. The following condition is satisfied: Ｃ ≦1.5×10 １５ / cm ３ In the case of N ＣＯＨ / N≦0.133×N Ｃ ×10 －１５ +0.3 N Ｃ >1.5×10 １５ / cm ３ In the case of N ＣＯＨ The semiconductor device according to claim 1 , wherein N≦0.

5.

3. The plurality of doping concentration peaks include two doping concentration peaks that are adjacent to each other in the depth direction and have a maximum distance therebetween, and the integral concentration of Si—H donors at the doping concentration peak that is farther from the bottom surface among the two doping concentration peaks is defined as N １ and the integral concentration of the CiOi-H donor between the two doping concentration peaks is N ＣＯＨ The semiconductor device according to claim 1 , wherein the conditional expression is satisfied even when 4. The plurality of doping concentration peaks include a minimum doping concentration peak having a minimum doping concentration and a first adjacent doping concentration peak adjacent to the minimum doping concentration peak on the lower surface side, and an integral concentration of Si—H donors at the minimum doping concentration peak is defined as N １ and the integral concentration of the CiOi-H donor between the minimum doping concentration peak and the first adjacent doping concentration peak is N ＣＯＨ The semiconductor device according to claim 1 , wherein the conditional expression is satisfied even when 5. Among the plurality of doping concentration peaks, each of the doping concentration peaks from the first doping concentration peak to the third doping concentration peak that is second closest to the lower surface is defined as a target doping concentration peak, and the doping concentration peak adjacent to the target doping concentration peak on the lower surface side is defined as a second adjacent doping concentration peak, and the integral concentration of the Si—H donor at the target doping concentration peak is defined as N １ and the integral concentration of the CiOi-H donor between the target doping concentration peak and the second adjacent doping concentration peak is N ＣＯＨ 2 . The semiconductor device according to claim 1 , wherein, when the above formula is satisfied, the conditional expression is satisfied for all of the target doping concentration peaks.

6. A semiconductor device according to any one of claims 1 to 5, wherein the distance in the depth direction from the lower surface to the first doping concentration peak is 30% or more and 50% or less of the thickness in the depth direction of the semiconductor substrate.

7. The semiconductor device according to claim 6, wherein the distance in the depth direction between the first doping concentration peak and the second doping concentration peak is 5% or more and 20% or less of the distance in the depth direction from the lower surface of the first doping concentration peak.

8. The semiconductor device according to claim 6, wherein the distance in the depth direction between the first doping concentration peak and the second doping concentration peak is 1 μm or more and 20 μm or less.

9. The oxygen chemical concentration of the semiconductor substrate is 1×10 １７ / cm ３ That's it, 5 x 10 １７ / cm ３ The semiconductor device according to claim 1 , wherein:

10. The carbon chemical concentration of the semiconductor substrate is 5×10 １５ / cm ３ The semiconductor device according to claim 1 , wherein:

11. The semiconductor device according to any one of claims 1 to 5, wherein the semiconductor substrate has: a drift region of a first conductivity type; and a buffer region provided between the drift region and the lower surface and having a doping concentration higher than that of the drift region, and the first doping concentration peak is located in the buffer region.

12. A semiconductor substrate having an upper surface and a lower surface and containing carbon; a plurality of hydrogen concentration peaks arranged in a line in a depth direction in the semiconductor substrate; and a plurality of doping concentration peaks arranged corresponding to the plurality of hydrogen concentration peaks, the plurality of doping concentration peaks including a first doping concentration peak farthest from the lower surface and a second doping concentration peak second farthest from the lower surface, and an integral concentration of Si-H donors at the first doping concentration peak is defined as N １ and the integral concentration of the CiOi-H donor between the first doping concentration peak and the second doping concentration peak is N ＣＯＨ The carbon chemical concentration of the semiconductor substrate is N Ｃ Let N=N １ +N ＣＯＨ If the following condition is satisfied, N ＣＯＨ / N≦8.286E−02×ln(N Ｃ ) +0.4656 Semiconductor device.

13. N satisfies the following condition: ＣＯＨ / N≦7.185E−02×ln(N Ｃ ) +0.4260 The semiconductor device according to claim 12.

14. A semiconductor substrate having an upper surface and a lower surface and containing carbon and oxygen; a plurality of hydrogen concentration peaks arranged in a line in a depth direction in the semiconductor substrate; and a plurality of doping concentration peaks arranged corresponding to the plurality of hydrogen concentration peaks, the plurality of doping concentration peaks including a first doping concentration peak farthest from the lower surface and a second doping concentration peak second farthest from the lower surface, and an integral concentration of Si-H donors at the first doping concentration peak is defined as N １ and the integral concentration of the CiOi-H donor between the first doping concentration peak and the second doping concentration peak is N ＣＯＨ The carbon chemical concentration of the semiconductor substrate is N Ｃ The oxygen chemical concentration of the semiconductor substrate is N ＯＸ Let N=N １ +N ＣＯＨ If the following condition is satisfied, N ＣＯＨ / N≦8.080E−02×ln(x)−2.926 where x=N ＯＸ ×{(N Ｃ / 1E15)×exp(N ＯＸ / 1E17)] semiconductor device.

15. The following condition is satisfied: ＣＯＨ The semiconductor device according to claim 14, wherein / N≦6.120E−02×ln(x)−2.194.

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