Semiconductor device and manufacturing method

Abstract

A semiconductor device is provided with a semiconductor substrate having a hydrogen-containing region containing hydrogen, and the hydrogen-containing region has a high-concentration region having a carrier concentration higher than a virtual carrier concentration determined on the basis of the concentration of hydrogen contained therein and the activation rate of hydrogen. The semiconductor substrate includes an N-type drift region, an N-type emitter region provided so as to be in contact with an upper surface of the semiconductor substrate and having a carrier concentration higher than that of the drift region, a P-type base region provided between the emitter region and the drift region, and a P-type collector region provided so as to be in contact with a lower surface of the semiconductor substrate. And an N-type buffer region provided between the collector region and the drift region and having a carrier concentration higher than that of the drift region. The hydrogen-containing region is included in the buffer region.

Description

[0001] This application is a divisional application of the invention patent application with application number 201980028584.4 (international application number PCT / JP2019 / 044756) filed by the applicant on November 14, 2019, and the original application invention name is “Semiconductor device and manufacturing method”, and all its contents are incorporated into this application by reference. Technical Field

[0002] The present invention relates to a semiconductor device and a manufacturing method thereof. Background Art

[0003] Conventionally, it is known to form an N-type region by implanting hydrogen into a semiconductor substrate (see, for example, Patent Document 1).

[0004] Patent Document 1: U.S. Patent Application Publication No. 2016 / 141399 Summary of the invention

[0005] Technical issues It is preferable that the carrier concentration distribution in the N-type region can be appropriately adjusted.

[0006] Technical Solution In order to solve the above-mentioned problems, in one embodiment of the present invention, a semiconductor device having a semiconductor substrate is provided. The semiconductor substrate may have a hydrogen-containing region containing hydrogen. The hydrogen-containing region may have a high-concentration region having a carrier concentration higher than a virtual carrier concentration determined by a concentration of hydrogen contained and an activation rate of hydrogen.

[0007] The carrier concentration of the high concentration region may be higher than the basic doping concentration of the semiconductor substrate.

[0008] The carrier concentration distribution in the depth direction of the hydrogen containing region may have a first peak.

[0009] The carrier concentration distribution in the depth direction of the hydrogen-containing region may have a plurality of first peaks. In the depth direction, the high concentration region may be arranged between the first peaks.

[0010] The high-concentration region may be arranged between a first peak arranged the deepest and a first peak arranged the second deepest among the first peaks.

[0011] The carrier concentration distribution of the high concentration region may have a second peak in the depth direction.

[0012] The width of the second peak of the high concentration region may be greater than the width of any first peak.

[0013] The hydrogen chemical concentration distribution in the hydrogen-containing region may have a plurality of fifth peaks. The full width at half maximum of the second peak may be greater than half of the fifth peak interval between the fifth peak disposed the deepest and the fifth peak disposed the second deepest among the fifth peaks.

[0014] The fifth peak arranged deepest and the fifth peak arranged second deepest may be included in the range of the half maximum width of the second peak.

[0015] The hydrogen-containing region may include a lifetime control region including an adjusting impurity for adjusting the lifetime of carriers. The concentration distribution of the adjusting impurity in the depth direction may include a third peak. The high concentration region may be provided at a position deeper than the third peak of the concentration distribution of the adjusting impurity.

[0016] The full width at half maximum of the third peak may be larger than the interval between the plurality of first peaks in the depth direction.

[0017] The oxygen concentration in the high concentration region can be 1×10 17 / cm 3 above.

[0018] The carbon concentration in the high concentration region can be 1×10 13 / cm 3 above.

[0019] The semiconductor substrate may have an N-type drift region. The semiconductor substrate may have an N-type emitter region that is arranged in contact with the upper surface of the semiconductor substrate and has a higher carrier concentration than the drift region. The semiconductor substrate may have a P-type base region that is arranged between the emitter region and the drift region. The semiconductor substrate may have a P-type collector region that is arranged in contact with the lower surface of the semiconductor substrate. The semiconductor substrate may have an N-type buffer region that is arranged between the collector region and the drift region and has a higher carrier concentration than the drift region. The hydrogen-containing region may be included in the buffer region.

[0020] In a second aspect of the present invention, a method for manufacturing a semiconductor device having a semiconductor substrate is provided. In the manufacturing method, hydrogen may be injected into the semiconductor substrate to form a hydrogen-containing region. In the manufacturing method, a lifetime control region for adjusting the lifetime of carriers may be formed in the hydrogen-containing region. In the manufacturing method, a high-concentration region having a carrier concentration higher than a virtual carrier concentration determined by the concentration of impurities contained and the activation rate of the impurities may be formed in the hydrogen-containing region by heat treating the semiconductor substrate.

[0021] It should be noted that the above-mentioned summary of the invention does not list all the essential features of the present invention. In addition, sub-combinations of these feature groups can also constitute other inventions. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a cross-sectional view showing an example of the semiconductor device 100 .

[0023] Figure 2 Yes means Figure 1 FIG. 5 is a diagram showing an example of the distribution of the carrier concentration and the virtual carrier concentration at the AA line.

[0024] Figure 3 It is a diagram showing carrier concentration distribution and virtual carrier concentration distribution.

[0025] Figure 4 1 is a diagram illustrating the second peak 112 of the high-concentration region 106 - 1 .

[0026] Figure 5 It is a diagram for explaining the third peak 113 in the helium concentration distribution.

[0027] Figure 6 It is a diagram showing another example of the carrier concentration distribution and the pseudo carrier concentration distribution.

[0028] Figure 7 It is a diagram showing another example of the carrier concentration distribution and the pseudo carrier concentration distribution.

[0029] Figure 8 is a diagram showing a structural example of the semiconductor device 100 .

[0030] Fig. 9 Yes means Figure 8 A diagram showing an example of the carrier concentration distribution in the depth direction at the position of the BB line.

[0031] Fig.10 The diagram shows a part of the steps in the method for manufacturing the semiconductor device 100 .

[0032] Fig.11 1 is a diagram showing an example of voltage and current waveforms during the reverse recovery operation of the semiconductor device 100 .

[0033] Explanation of symbols 10: semiconductor substrate, 12: emitter region, 14: base region, 16: storage region, 18: drift region, 20: buffer region, 21: upper surface, 22: collector region, 23: lower surface, 25: peak, 38: interlayer insulating film, 40: gate trench portion, 42: gate insulating film, 44: gate conductive portion, 52: emitter, 54: collector, 100: semiconductor device, 102: hydrogen-containing region, 104: lifetime control region, 106: high concentration region, 111: first peak, 112: second peak, 113: third peak, 114: fourth peak, 115: fifth peak, 116: valley, 117: slope, 118: slope, 119: peak DETAILED DESCRIPTION

[0034] Hereinafter, the present invention will be described by way of the embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, all combinations of features described in the embodiments are not necessarily essential to the solution of the invention.

[0035] In this specification, one side in a direction parallel to the depth direction of the semiconductor substrate is referred to as "upper", and the other side is referred to as "lower". One of the two main surfaces of a substrate, layer, or other component is referred to as an upper surface, and the other is referred to as a lower surface. The directions of "upper" and "lower" are not limited to the direction of gravity or the direction when the semiconductor device is installed.

[0036] In this specification, orthogonal coordinate axes of the X-axis, Y-axis, and Z-axis are sometimes used to explain technical matters. Orthogonal coordinate axes are only used to determine the relative positions of components and do not limit specific directions. For example, the Z-axis is not limited to indicating the height direction relative to the ground. It should be noted that the +Z-axis direction and the -Z-axis direction are opposite directions to each other. When the positive and negative are not recorded but the Z-axis direction is recorded, it refers to the direction parallel to the +Z-axis and the -Z-axis.

[0037] In this specification, the orthogonal axes parallel to the upper surface and the lower surface of the semiconductor substrate are referred to as the X-axis and the Y-axis. In addition, the axis perpendicular to the upper surface and the lower surface of the semiconductor substrate is referred to as the Z-axis. In this specification, the direction of the Z-axis is sometimes referred to as the depth direction. In addition, in this specification, the direction parallel to the upper surface and the lower surface of the semiconductor substrate, including the X-axis and the Y-axis, is sometimes referred to as the horizontal direction.

[0038] In this specification, the term "same" or "equal" may include a case where there is an error due to manufacturing variation, etc. The error is within 10%, for example.

[0039] In this specification, the conductivity type of the doped region doped with impurities is set to P type or N type for description. In this specification, impurities sometimes refer to either N type donors or P type acceptors, and sometimes are described as dopants. In this specification, doping refers to the introduction of donors or acceptors into a semiconductor substrate to produce a semiconductor showing N type conductivity or a semiconductor showing P type conductivity.

[0040] In this specification, doping concentration refers to the concentration of donors or acceptors in thermal equilibrium. In this specification, net doping concentration refers to the net concentration obtained by adding the donor concentration as the concentration of positive ions and the acceptor concentration as the concentration of negative ions, including the polarity of the charge. As an example, if the donor concentration is N D , set the acceptor concentration to N A , then the net doping concentration at any position is N D -N A In this specification, the net doping concentration may be described simply as the doping concentration.

[0041] A donor has the function of supplying electrons to a semiconductor. An acceptor has the function of accepting electrons from a semiconductor. Donors and acceptors are not limited to the impurities themselves. For example, a VOH defect formed by a combination of vacancies (V), oxygen (O), and hydrogen (H) present in a semiconductor functions as a donor that supplies electrons. In this specification, a VOH defect is sometimes referred to as a hydrogen donor.

[0042] In this specification, when it is described as P+ type or N+ type, it means that the doping concentration is higher than that of P type or N type, and when it is described as P- type or N- type, it means that the doping concentration is lower than that of P type or N type. In addition, in this specification, when it is described as P++ type or N++ type, it means that the doping concentration is higher than that of P+ type or N+ type.

[0043] In this specification, chemical concentration refers to the concentration of impurities measured independently of the state of electrical activation. The chemical concentration can be measured, for example, by secondary ion mass spectrometry (SIMS). The above-mentioned net doping concentration can be measured by voltage-capacitance determination (CV method). In addition, the carrier concentration measured by the extended resistance determination method (SR method) can be used as the net doping concentration. The carrier concentration measured by the CV method or the SR method can adopt the value in the thermal equilibrium state. In addition, in the N-type region, the donor concentration is much greater than the acceptor concentration, so the carrier concentration in this region can be used as the donor concentration. Similarly, in the P-type region, the carrier concentration in this region can also be used as the acceptor concentration. In this specification, the doping concentration in the N-type region is sometimes referred to as the donor concentration, and the doping concentration in the P-type region is sometimes referred to as the acceptor concentration.

[0044] In addition, when the concentration distribution of the donor, acceptor or net doping has a peak, the peak value can be used as the concentration of the donor, acceptor or net doping in the region. When 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 the region can be used as the concentration of the donor, acceptor or net doping.

[0045] The carrier concentration measured by the SR method can also be lower than the concentration of donors or acceptors. In the range of current flow when measuring spreading resistance, the carrier mobility of the semiconductor substrate is sometimes lower than the value in the crystalline state. The reduction in carrier mobility is caused by carrier scattering due to crystal structure disorder (disorder) caused by lattice defects, etc.

[0046] The concentration of donors or acceptors 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 as donors in a silicon semiconductor, or the acceptor concentration of boron (boron element) as an acceptor is about 99% of their chemical concentrations. On the other hand, the donor concentration of hydrogen as a donor in a silicon semiconductor is about 0.1% to 10% of the chemical concentration of hydrogen. In this specification, the SI unit system is used. In this specification, the unit of distance and length is sometimes expressed in cm (centimeter). In this case, each calculation can be calculated by converting to m (meter). As an example, when referred to as concentration in this specification, it refers to the concentration per unit volume ( / cm 3 For example, the chemical concentration of an impurity is the number of atoms of the impurity per unit volume (atoms / cm 3 ).

[0047] Figure 1 1 is a cross-sectional view showing an example of a semiconductor device 100. The semiconductor device 100 includes a transistor element such as an insulated gate bipolar transistor (IGBT) and a diode element such as a freewheeling diode (FWD). Figure 1 The detailed contents of the structures of these components are omitted.

[0048] The semiconductor device 100 includes a semiconductor substrate 10. The semiconductor substrate 10 is a substrate formed of a semiconductor material. As an example, the semiconductor substrate 10 is a silicon substrate. The semiconductor substrate 10 contains impurities added intentionally or unintentionally when manufacturing a semiconductor ingot. The semiconductor substrate 10 has a doping concentration determined by the impurities injected during manufacturing. The conductivity type of the semiconductor substrate 10 in this example is N-type. In this specification, the doping concentration in the semiconductor substrate 10 is sometimes referred to as a basic doping concentration Db.

[0049] As an example, when the semiconductor ingot is silicon, the N-type impurities (dopants) used to set the basic doping concentration Db are phosphorus, antimony, arsenic, etc., and the P-type impurities (dopants) are boron, aluminum, etc. The basic doping concentration Db can be lower than the chemical concentration of the dopant of the semiconductor ingot. As an example, when the dopant is phosphorus or boron, the basic doping concentration Db can be more than 50% or more than 90% of the chemical concentration of the dopant. As another example, when the dopant is antimony, the basic doping concentration Db can be more than 5%, more than 10%, or more than 50% of the chemical concentration of the dopant. In addition, the semiconductor substrate 10 can contain carbon and oxygen. Carbon and oxygen can be distributed throughout the semiconductor substrate 10. As an example of a method for manufacturing a semiconductor ingot, a Czochralski (MCZ) method with a magnetic field applied is used, but other methods may also be used. As other methods, a Czochralski (CZ) method or a floating zone (FZ) method may also be used.

[0050] The semiconductor substrate 10 has an upper surface 21 and a lower surface 23. The upper surface 21 and the lower surface 23 are two main surfaces of the semiconductor substrate 10. In this specification, the orthogonal axes in the plane parallel to the upper surface 21 and the lower surface 23 are set as the X axis and the Y axis, and the axis perpendicular to the upper surface 21 and the lower surface 23 is set as the Z axis.

[0051] The semiconductor substrate 10 has a hydrogen-containing region 102 containing hydrogen. In this example, hydrogen ions are injected into the hydrogen-containing region 102 from the lower surface 23 side of the semiconductor substrate 10. In this example, the hydrogen ions are protons. The hydrogen ions may also be deuterons or tritium nuclei. The hydrogen-containing region 102 is a region where the chemical concentration of hydrogen is higher than the chemical concentration of any of the other N-type impurities and P-type impurities. In the hydrogen-containing region 102, the chemical concentration of hydrogen may be more than 100 times the chemical concentration of the impurity with the highest chemical concentration among the other N-type impurities and P-type impurities. The hydrogen-containing region 102 may be a region where the chemical concentration of hydrogen is more than 10 times the basic doping concentration Db. The hydrogen-containing region 102 may be a region where the chemical concentration of hydrogen is higher than the basic doping concentration Db. The hydrogen-containing region 102 may contain impurities such as helium that do not function as N-type impurities and P-type impurities. The chemical concentration of impurities such as helium in the hydrogen-containing region 102 may also be higher than the chemical concentration of hydrogen. Impurities such as helium can function as adjusting impurities for adjusting the lifetime of carriers in the semiconductor substrate 10 .

[0052] The hydrogen ions injected from the lower surface 23 of the semiconductor substrate 10 pass through the interior of the semiconductor substrate 10 to a depth corresponding to the acceleration energy. Vacancy defects such as vacancies (V) and compound vacancies (VV) are generated in the area where the hydrogen ions pass. In this specification, unless otherwise specified, vacancies also include compound vacancies. Vacancy defects can include unbonded bonds (dangling bonds) present in vacancies or compound vacancies, and can also include unpaired electrons of dangling bonds. Hydrogen is diffused by heat treating the semiconductor substrate 10 after the hydrogen ions are injected. VOH defects are formed by combining the diffused hydrogen with vacancies (V) and oxygen (O). VOH defects function as donors that supply electrons. In addition, the diffused hydrogen itself is activated and functions as a hydrogen donor. As a result, the hydrogen-containing region 102 becomes an N+ type region with a concentration higher than the base doping concentration Db.

[0053] In this specification, the ratio of the concentration of the dopant (donor or acceptor) generated by the impurity to the chemical concentration of the impurity is referred to as the activation rate of the impurity. In the case of hydrogen, the dopant generated by the impurity is a VOH defect and a hydrogen donor. In the case of other P-type impurities and N-type impurities, it is a dopant activated by the impurity itself. Generally, the doping concentration in the semiconductor substrate 10 is the concentration obtained by multiplying the concentration of the impurity contained by the activation rate of the impurity. For example, in the case where the impurity contained in the hydrogen-containing region 102 is essentially only hydrogen, it is assumed that the doping concentration in the hydrogen-containing region 102 is the value obtained by multiplying the chemical concentration of hydrogen by the activation rate of hydrogen. The activation rate of hydrogen can be in the range of 0.1% to 80%, for example, about 1%. In this specification, the concentration obtained by multiplying the chemical concentration of the impurity by the activation rate of the impurity is referred to as the virtual carrier concentration (or virtual doping concentration). The virtual carrier concentration is determined for each position of the semiconductor substrate 10 according to the chemical concentration and activation rate of the impurity.

[0054] The hydrogen-containing region 102 has a high concentration region 106. The high concentration region 106 is a region where the carrier concentration is higher than the above-mentioned virtual carrier concentration. Alternatively, the high concentration region 106 is a region where the doping concentration is higher than the above-mentioned virtual doping concentration. In this specification, carrier concentration and virtual carrier concentration are used for description, but the carrier concentration and virtual carrier concentration can be appropriately renamed as doping concentration and virtual doping concentration. As an example, the high concentration region 106 can be formed by adjusting the distribution of vacancy defects in the hydrogen-containing region 102. It can be considered that when manufacturing the semiconductor substrate 10, the vacancy defects are uniformly distributed throughout the substrate. By injecting hydrogen into the hydrogen-containing region 102, the vacancy defects are distributed according to the distribution of the injected hydrogen. By performing heat treatment after the hydrogen injection, hydrogen donors or VOH defects are generated, forming a carrier concentration distribution corresponding to the hydrogen distribution. Then, in the hydrogen-containing region 102, in addition to the vacancy defects generated by the hydrogen injection, if new vacancy defects are generated and heat treatment is performed, the hydrogen in the hydrogen-containing region 102 combines with the new vacancy defects to form new hydrogen donors or VOH defects. Due to the new VOH defects, the high concentration region 106 is formed. New vacancy defects can be formed by, for example, injecting adjustment impurities such as helium that do not function as dopants into the hydrogen-containing region 102. It should be noted that in this specification, unless otherwise specified, the term "VOH defect" is used to include hydrogen donors or donors newly formed by hydrogen ion injection.

[0055] The hydrogen-containing region 102 of this example has a lifetime control region 104. The lifetime control region 104 is a region in which the lifetime of carriers is reduced by forming a lifetime control agent that adjusts the lifetime of carriers. The lifetime control agent is a recombination center of carriers, which may be a crystal defect, or a vacancy defect such as a vacancy or a composite vacancy, a composite defect or dislocation of an element constituting the semiconductor substrate 10 or an impurity other than the element, a rare element such as helium, neon, argon, or a metal element such as platinum. In this example, vacancy defects and the like generated by injecting adjustment impurities such as helium into the semiconductor substrate 10 function as lifetime control agents.

[0056] As described above, vacancy defects can be combined with hydrogen by heat treatment to become VOH defects. However, if a large number of vacancy defects are formed, the amount of hydrogen is insufficient, and the proportion of vacancy defects that exist in the form of vacancy defects without combining with hydrogen becomes higher. The carrier lifetime in the area where vacancy defects exist in large numbers is reduced, and it becomes a lifetime control area 104. On the other hand, vacancy defects formed by irradiation with adjustment impurities such as helium are formed in large numbers near the range of the adjustment impurities, and the farther away from the range of the adjustment impurities, the less vacancy defects there are. Therefore, in the area far from the range of the adjustment impurities, hydrogen exists sufficiently relative to vacancy defects, and the proportion of vacancy defects that combine with hydrogen to become VOH defects becomes higher. The area where VOH defects are formed in large numbers functions as a high concentration area 106.

[0057] In this example, the lifetime control region 104 is formed by implanting adjustment impurities from the lower surface 23 side of the semiconductor substrate 10. The high concentration region 106 can be provided at a position separated from the lifetime control region 104 in the depth direction (Z-axis direction). The high concentration region 106 of this example is provided at a position deeper than the lifetime control region 104 with respect to the lower surface 23 as a reference.

[0058] When the adjustment impurities are injected from the lower surface 23 side with a range near the lifetime control region 104, vacancy defects and the like are formed more in the region through which the adjustment impurities pass, but in the region deeper than the range, relatively fewer vacancy defects and the like are formed. Therefore, in the region deeper than the range, the ratio of the formed vacancy defects to VOH defects becomes high, and the high concentration region 106 is easily formed. However, the relationship between the lifetime control region 104 and the high concentration region 106 is not limited to this. The high concentration region 106 can be formed at a position shallower than the lifetime control region 104.

[0059] In addition, even if the lifetime control region 104 is not provided, the high concentration region 106 can be formed. For example, by injecting a relatively low concentration of adjustment impurities near the high concentration region 106, fewer vacancy defects can be formed compared to hydrogen present in this region. Therefore, the ratio of vacancy defects to VOH defects becomes higher, and the high concentration region 106 can be formed without reducing the lifetime. In this case, the high concentration region 106 can be provided at any position without being limited by the position of the lifetime control region 104.

[0060] It should be noted that it has been confirmed through experiments that the higher the chemical concentration of carbon in the high concentration region 106, the greater the difference between the carrier concentration in the high concentration region 106 and the virtual carrier concentration. Therefore, the chemical concentration of carbon in the high concentration region 106 is preferably 1×10 13 / cm 3 The chemical concentration of carbon in the high concentration region 106 may be 1×10 14 / cm 3 Above, it can also be 1×10 15 / cm 3 In addition, the chemical concentration of carbon in the high concentration region 106 may be 1×10 16 / cm 3 Below, it can also be 5×10 15 / cm 3 Below, it can also be 1×10 15 / cm 3 The entire semiconductor substrate 10 may have the above-mentioned carbon concentration.

[0061] In addition, the higher the oxygen concentration, the easier it is to form VOH defects. The chemical concentration of oxygen in the high concentration region 106 may be 1×10 17 / cm 3 The chemical concentration of oxygen in the high concentration region 106 can be 5×10 17 / cm 3 Above, it can also be 1×10 18 / cm 3 In addition, the chemical concentration of oxygen in the high concentration region 106 can be 1×10 19 / cm 3 Below, it can also be 5×10 18 / cm 3 Below, it can also be 1×10 18 / cm 3 The entire semiconductor substrate 10 may have the above-mentioned oxygen concentration.

[0062] The above-mentioned carbon concentration and oxygen concentration can be easily achieved by manufacturing the semiconductor substrate 10 using the MCZ method. However, the semiconductor substrate 10 is not limited to the MCZ substrate manufactured using the MCZ method.

[0063] A drift region 18 may be provided in the semiconductor substrate 10. The drift region 18 is an N-type region having a lower doping concentration than the hydrogen-containing region 102. The doping concentration of the drift region 18 may be the same as the basic doping concentration Db. The drift region 18 may include a region having a doping concentration higher than the basic doping concentration Db. The doping concentration distribution of the drift region 18 may be almost the same or flat within a predetermined depth range L0. As an example, the same or flat means that within the predetermined depth range L0, the variation of the doping concentration shows a distribution of a range of values ​​of more than 80% and less than 120% of the basic doping concentration Db. The predetermined depth range L0 may be a length within 10% of the thickness W0 of the semiconductor substrate 10 (i.e., L0≤0.1W0), a length within 30% (i.e., L0≤0.3W0), a length within 50% (i.e., L0≤0.5W0), or a length within 70% (i.e., L0≤0.7W0).

[0064] Figure 2 Yes means Figure 1 FIG. 1 is a diagram showing an example of the distribution of the carrier concentration and the virtual carrier concentration at the AA line. The AA line includes the entire hydrogen-containing region 102 and a portion of the drift region 18 in the depth direction. Figure 2 , the hydrogen chemical concentration distribution and the helium concentration distribution at the AA line are shown together. Helium is an example of an adjustment impurity for forming a lifetime control agent. Figure 2 The vertical axis is a logarithmic axis representing each concentration, and the horizontal axis is a linear axis representing the depth position from the lower surface 23. It should be noted that the concentration distribution in each figure represents the distribution when the semiconductor device 100 is completed (that is, after heat treatment). In addition, Figure 2 The hydrogen chemical concentration and the helium concentration in are chemical concentrations measured by, for example, the SIMS method. Figure 2 The carrier concentration in is measured, for example, by the SR method.

[0065] In this example, the carrier concentration distribution has a first peak 111, the helium concentration distribution has a third peak 113, the virtual carrier concentration distribution has a fourth peak 114, and the hydrogen chemical concentration distribution has a fifth peak 115. Each concentration distribution may have multiple peaks. For the multiple first peaks 111, they are sequentially set to first peaks 111-1, 111-2, 111-3, and 111-4 from the peak close to the lower surface 23 of the semiconductor substrate 10. For the multiple third peaks 113, they are sequentially set to third peaks 113-1, 113-2, 113-3, and 113-4 from the peak close to the lower surface 23 of the semiconductor substrate 10. For the multiple fourth peaks 114, they are sequentially set to fourth peaks 114-1, 114-2, 114-3, and 114-4 from the peak close to the lower surface 23 of the semiconductor substrate 10. The plurality of fifth peaks 115 are sequentially designated as fifth peaks 115-1, 115-2, 115-3, and 115-4 from the peak close to the lower surface 23 of the semiconductor substrate 10. In addition, the depth positions at which the fifth peaks 115 of the hydrogen chemical concentration distribution present a maximum value are sequentially designated as PH1, PH2, PH3, and PH4 from the position close to the lower surface 23. In addition, the depth position at which the third peak 113 of the helium concentration distribution presents a maximum value is designated as PHe. In addition, the depth position at which the second peak 112 of the carrier concentration distribution in the high concentration region 106-1 presents a maximum value is designated as P2.

[0066] exist Figure 2 In the example, the positions where the first peaks 111 of the carrier concentration distribution present a maximum value are the same as the positions where the fifth peaks 115 of the hydrogen chemical concentration distribution present a maximum value, but these positions may not be strictly consistent. For example, if the position where the first peak 111 presents a maximum value is included in the range of the half-maximum full width of the fifth peak 115, it can be considered that the first peak 111 and the fifth peak 115 are arranged at substantially the same position.

[0067] The hydrogen-containing region 102 contains hydrogen. In this example, the hydrogen-containing region 102 does not substantially contain N-type impurities and P-type impurities other than hydrogen. For example, the chemical concentration of hydrogen in the hydrogen-containing region 102 is more than 100 times the chemical concentration of the N-type impurities and the P-type impurities. Figure 2 In the example, the region where the hydrogen chemical concentration is 10 times or more of the base doping concentration Db is used as the hydrogen-containing region 102. The fifth peak 115 of the hydrogen chemical concentration distribution is arranged near the range position during hydrogen ion implantation. In the case where the hydrogen-containing region 102 has a plurality of fifth peaks 115, the range can be changed to implant hydrogen ions into the hydrogen-containing region 102 multiple times. The change in the range can be a change in the acceleration energy of the hydrogen ions during ion implantation.

[0068] The virtual carrier concentration distribution is a distribution obtained by multiplying the hydrogen chemical concentration distribution by an activation rate less than 1. In other words, the virtual carrier concentration distribution has the same shape as the hydrogen chemical concentration distribution and is a distribution in which the concentration value decreases. The activation rate may use a predetermined value, or may be determined based on the hydrogen chemical concentration distribution and the carrier concentration distribution. For example, the peak value of the fifth peak 115-1 farthest from the third peak 113 of the helium concentration distribution among the multiple fifth peaks 115 of the hydrogen chemical concentration distribution is set to D5-1, and the peak value of the first peak 111-1 arranged at the same depth position as the fifth peak 115-1 among the multiple first peaks 111 of the carrier concentration distribution is set to D1-1. The ratio D1-1 / D5-1 of the peak value D1-1 of the first peak 111-1 to the peak value D5-1 of the fifth peak 115-1 can be used as the activation rate.

[0069] The third peak 113 of the helium concentration distribution in this example is arranged in the depth direction between the depth positions PH2 and PH3 where the two fifth peaks 115 (in this example, the fifth peaks 115-2 and 115-3) of the hydrogen chemical concentration distribution show the maximum value. Similarly, the third peak 113 is arranged in the depth direction between the two first peaks 111 (in this example, the first peaks 111-2 and 111-3) of the carrier concentration distribution. For example, the depth position PHe where the third peak 113 becomes the maximum value is not included in the range of the full width at half maximum (FWHM) of any fifth peak 115. Similarly, the point where the third peak 113 becomes the maximum value is not included in the range of the full width at half maximum of any first peak 111. By making the position of the third peak 113 of the helium concentration distribution different from the fifth peak 115, the vacancy defects formed by helium irradiation can be prevented from combining with hydrogen and remaining, and the carrier lifetime can be reduced. Therefore, the lifetime control region 104 can be easily formed. When helium is injected from the lower surface 23 side, the slope of the lower surface 23 side of the third peak 113 of the helium concentration distribution tends to be smaller than the slope of the opposite side to the lower surface 23 .

[0070] The concentration value of the carrier concentration distribution in the high concentration region 106 is higher than the concentration value of the virtual carrier concentration distribution. It should be noted that the carrier concentration in the high concentration region 106 is higher than the basic doping concentration Db of the semiconductor substrate 10. The high concentration region 106 can be arranged between the first peaks 111 of the carrier concentration distribution. In this example, the high concentration region 106-1 is provided between the deepest first peak 111-4 and the second deepest first peak 111-3 in the first peak 111 of the carrier concentration distribution.

[0071] In this example, the carrier concentration distribution of the high concentration region 106-1 has a second peak 112. The depth position P2 of the second peak 112 of the high concentration region 106-1 is arranged between the depth position PH4 of the first peak 111-4 and the depth position PH3 of the first peak 111-3.

[0072] In addition, a high concentration region 106-2 is provided between the first peak 111-4 and the drift region 18. The high concentration region 106-1 and the high concentration region 106-2 may be provided continuously in a manner including the first peak 111-4. In each high concentration region 106, the maximum value of the carrier concentration may be 1.1 times or more, 1.5 times or more, or 2 times or more of the virtual carrier concentration at the depth position.

[0073] Each high concentration region 106 may contain an adjustment impurity such as helium. The concentration of the adjustment impurity contained in the high concentration region 106 may be higher than the basic doping concentration Db. The high concentration region 106 may be set at a position deeper than the third peak 113 of the helium concentration distribution with the lower surface 23 as the reference. Vacancy defects caused by helium injection are generated in the high concentration region 106. The concentration distribution of vacancy defects is Figure 5 As described separately in. Through heat treatment, the vacancy defect combines with hydrogen and oxygen to become a defect containing VOH. Since the defect containing VOH functions as a donor, the carrier concentration of the high concentration region 106 is higher than the virtual carrier concentration. Through such a structure, a carrier concentration distribution different from the virtual carrier concentration distribution can be obtained. On the other hand, since a large number of vacancy defects are formed near the third peak 113 of the helium concentration distribution, the proportion of the remaining vacancy defects becomes higher, and the carrier concentration becomes lower than the virtual carrier concentration. Thus, the lifetime control region 104 can be formed. According to this example, the high concentration region 106 can be formed in the same process as the lifetime control region 104.

[0074] In addition, in the high concentration region 106-2, the slope 117 of the carrier concentration distribution changes more gently than the slope 118 of the virtual carrier concentration. That is, the slope 117 of the carrier concentration distribution extends to a deeper position than the slope 118 of the virtual carrier concentration. Thus, for example, when the semiconductor device 100 is used as a switching element such as a transistor, the voltage and current waveforms during switching can be smoothed. The slope 118 may be such that the slope decreases as the distance from the lower surface 23 increases. That is, the slope 118 may have a shape that is convex downward. The slope 117 may be such that the slope increases as the distance from the lower surface 23 increases. That is, the slope 117 may have a shape that is convex upward.

[0075] The carrier concentration in the hydrogen-containing region 102 may be higher than the basic doping concentration Db of the semiconductor substrate 10. However, the carrier concentration in the lifetime control region 104 may also be lower than the basic doping concentration Db. The carrier concentration distribution may have a valley 116 in the lifetime control region 104. In the case where the inter-peak region between each fifth peak 115 of the hydrogen chemical concentration distribution is set as an inter-peak region, the valley 116 may be arranged in an inter-peak region that is closer to the lower surface 23 than the inter-peak region where the high concentration region 106-1 is provided. The valley 116 in this example is arranged in an inter-peak region that is adjacent to the inter-peak region where the high concentration region 106-1 is provided, separated by the fifth peak 115-3. The valley 116 may be arranged in the same inter-peak region as the third peak 113 of the helium concentration distribution.

[0076] Figure 3 It is a diagram showing carrier concentration distribution and virtual carrier concentration distribution. Figure 3 The carrier concentration distribution and virtual carrier concentration distribution in Figure 2 In this example, the maximum value in each first peak 111 of the carrier concentration distribution is set to D1, and the maximum value in each fourth peak 114 of the virtual carrier concentration distribution is set to D4. In addition, the maximum value of the carrier concentration distribution of the high concentration region 106-1 is set to D2.

[0077] The maximum value D1 of a first peak 111 in the carrier concentration distribution may be less than the virtual carrier concentration at the depth position. For example, the maximum value D1 of at least one of the two first peaks 111-2 and 111-3 arranged across the lifetime control region 104 or the valley 116 is smaller than the maximum value D4 of the corresponding fourth peaks 114-2 and 114-3. In the vicinity of the lifetime control region 104, vacancy defects do not become VOH defects and remain in large quantities, so the carrier concentration is easily reduced.

[0078] Figure 4 1 is a diagram illustrating the second peak 112 of the high-concentration region 106 - 1 . Figure 4 The carrier concentration distribution in Figure 2 The example is the same. The second peak 112 is a peak that is gentler in the depth direction than any of the two first peaks 111-3 and 111-4 that sandwich the second peak 112. The width W2 of the second peak 112 in the depth direction is larger than any of the widths W1-3 and W1-4 of the first peaks 111-3 and 111-4 in the depth direction. The width of each peak can be determined using the half-maximum full width of each peak. In the case where the half-maximum full width cannot be measured in each peak, a reference other than the half value can be used to define the width of each peak. For example, the width of the region above the concentration (0.8×D) of 80% relative to the maximum value D of each peak can be used as the width of each peak.

[0079] The width W2 of the second peak 112 may be greater than the width W1 of any first peak 111 in the hydrogen containing region 102. According to this example, the carrier concentration distribution in the region close to the drift region 18 in the hydrogen containing region 102 can be made uniform.

[0080] Figure 5 1 is a diagram illustrating the third peak 113 in the helium concentration distribution. Figure 5 1 and 2 also show a vacancy defect concentration distribution. The vacancy defect concentration distribution is a distribution of the concentration of vacancy defects generated by ion implantation of an adjustment impurity such as helium ions. The vacancy defect concentration distribution has a peak 119 . Figure 5 The carrier concentration distribution and helium concentration distribution in Figure 2 In this example, the width of the third peak 113 in the depth direction is set to Wk. The width Wk can be the full width at half maximum of the third peak 113. In addition, the width of the inter-peak region between the first peaks 111 of the carrier concentration distribution is set to L. Figure 5 In the example, the width of the inter-peak region between the first peaks 111-1 and 111-2 is set to L12, the width of the inter-peak region between the first peaks 111-2 and 111-3 is set to L23, and the width of the inter-peak region between the first peaks 111-3 and 111-4 is set to L34.

[0081] The width Wk of the third peak 113 in this example is greater than the width L of any inter-peak region. The width Wk of the third peak 113 may range from a plurality of first peaks 111. Figure 5 In the example of FIG. 1 , the first peaks 111 - 2 and 111 - 3 are included in the range of the width Wk. The width Wk may be 5 μ m or more, can also be 10 μ m or more. The width Wk may be smaller than the width in the depth direction of the hydrogen-containing region 102. By increasing the width Wk of the third peak 113, helium can also be distributed at a position away from the peak position PHe of the third peak 113. Therefore, VOH defects can be generated at a position away from the peak position PHe to form a high concentration region 106. In addition, it is easy to form a high concentration region 106 near the drift region 18, and the carrier concentration distribution near the drift region 18 can be changed smoothly.

[0082] The peak 119 of the vacancy defect concentration distribution may be located near the third peak 113 of the helium concentration distribution. In this example, the peak position PV of the peak 119 coincides with the peak position PHe of the third peak 113. The peak position PV of the peak 119 may also be inconsistent with the peak position PHe of the third peak 113. The vacancy defect concentration distribution may be distributed in a manner that includes the position PHe of the third peak 113 of the helium concentration distribution. The peak 119 of the vacancy defect concentration distribution is distributed narrower than the distribution width of the third peak 113 of the helium concentration distribution. The position PV of the peak 119 may be located between the peak positions of two hydrogen concentrations adjacent in the depth direction across the position PHe. The peak 119 of the vacancy defect concentration distribution of this example is distributed between the first peak 111-2 and the first peak 111-3 of the carrier concentration. The width Wv between the two concentration positions that become 10% of the peak concentration of the vacancy defect concentration distribution may be shorter than the width L23. Vacancy defects are formed inside the semiconductor substrate 10 by adjusting the ion implantation of impurities. The hydrogen present around the vacancy defect terminates the dangling bonds of the vacancy defect. Therefore, the concentration of the formed vacancy defects is reduced. In the first peak 111-2 and the first peak 111-3 where the hydrogen chemical concentration is high, the vacancy defect concentration is particularly reduced due to the high hydrogen chemical concentration. As a result, the vacancy defect concentration is distributed only between the first peak 111-2 and the first peak 111-3. That is, the recombination center caused by the vacancy defect is locally distributed between the two carrier concentration peaks, and the depth and width of the recombination center can be controlled with high precision. The slope of the concentration slope on both sides of the peak position PV of the vacancy defect concentration distribution can be greater than the slope of the concentration slope on both sides of the peak position PHe of the helium concentration distribution.

[0083] Figure 6 is a diagram showing another example of carrier concentration distribution and virtual carrier concentration distribution. Figure 2 to Figure 5 In the carrier concentration distribution described in , the maximum value D2 of the second peak 112 is smaller than any of the maximum values ​​D1-3 and D1-4 of the two first peaks 111-3 and 111-4 sandwiching the second peak 112. In contrast, the maximum value D2 of the second peak 112 can be greater than at least one of the maximum values ​​D1-3 and D1-4. In this example, the maximum value D2 of the second peak 112 is greater than any of the maximum values ​​D1-3 and D1-4. With such a configuration, the carrier concentration distribution near the drift region 18 can be made smoother.

[0084] Figure 6The carrier concentration distribution shown has a minimum (valley) between the first peak 111-3 and the second peak 112, and has a minimum (valley) between the second peak 112 and the first peak 111-4. In another example, the carrier concentration distribution may not have a minimum (valley) between the first peak 111-3 and the second peak 112, and between the second peak 112 and the first peak 111-4. The carrier concentration distribution may form a single peak between the depth positions PH3 and PH4. That is, the carrier concentration distribution between the depth positions PH3 and PH4 may not have a minimum (valley).

[0085] Figure 7 is a diagram showing another example of carrier concentration distribution and virtual carrier concentration distribution. In this example, the width W2 of the second peak 112 is greater than Figure 1 to Figure 6 For example, by adjusting the oxygen concentration of the semiconductor substrate 10, a second peak 112 with a large width W2 can be formed. The oxygen concentration of the semiconductor substrate 10 in this example can be 1×10 17 / cm 3 Above, it can also be 5×10 17 / cm 3 Above, it can also be 1×10 18 / cm 3 Or, it can be 1×10 18 / cm 3 Other components can be Figure 1 to Figure 6 The semiconductor substrate 10 may be a substrate manufactured by the MCZ method.

[0086] In this example, helium is also implanted at the depth position PHe. Thus, a high concentration region 106 can be formed. The dose of helium can be 5×10 10 / cm 2 Above, it can also be 1×10 11 / cm 2 Above, it can also be 1×10 12 / cm 2 In addition, in order to evenly distribute helium over a wide range, the range can be changed and helium can be injected at multiple depths. In this case, the total dose of helium can be 5×10 10 / cm 2 Above, it can also be 1×10 11 / cm 2 Above, it can also be 1×10 12 / cm 2 Alternatively, the acceleration energy of the helium ions may be increased to increase the full width at half maximum of the helium ions.

[0087] The full width at half maximum W2 of the second peak 112 in this example may be greater than half of the fifth peak interval W5 between the fifth peak 115-4 arranged at the deepest position and the fifth peak 115-3 arranged at the second deepest position in the fifth peak 115 of the hydrogen chemical concentration distribution. In this example, the dose for the fifth peak 115-4 at the deepest position may be 1×10 12 / cm 2 Above, it can also be 7×10 12 / cm 2 Above, it can also be 1×10 13 / cm 2 By increasing the dose of the fifth peak 115-4, the amount of hydrogen that terminates the vacancy defects can be ensured. Therefore, the second peak 112 with a large width W2 is easily formed.

[0088] It should be noted that when the carrier concentration is observed from the apex of the second peak 112 toward the drift region 18 side, the depth position at which the carrier concentration initially becomes half (D2 / 2) of the apex concentration D2 is set as Zb. The distance in the depth direction from the apex of the second peak 112 to the depth position Zb can be set as half of the half-maximum full width W2. That is, twice the distance can be set as the half-maximum full width W2. At this time, at a position closer to the lower surface 23 than the apex of the second peak 112, even if the carrier concentration does not become less than D2 / 2, the half-maximum full width W2 can be specified.

[0089] By increasing the width W2, the carrier concentration distribution in the hydrogen-containing region 102 can be made highly concentrated and flat. For example, when the hydrogen-containing region 102 is used as a buffer zone described later, the voltage waveform during the reverse recovery operation of the semiconductor device 100 can be smoothed, and soft recovery can be performed. In addition, the electric field strength on the lower surface 23 side is relaxed, and the avalanche resistance on the lower surface 23 side can be improved. The full width at half maximum W2 of the second peak 112 can be greater than the fifth peak interval W5.

[0090] Each vertex of the fifth peak 115-4 and the fifth peak 115-3 can be arranged within the depth range of the half-maximum full width W2 of the second peak 112. In this way, the second peak 112 can be made smoother. At this time, the carrier concentration distribution can have a fourth peak 114 or a kink at depth positions PH3 and PH4, respectively. A kink refers to a point where the slope (i.e., differential value) of the distribution waveform changes discontinuously. In addition, the half-maximum full width W2 of the second peak 112 can be 5 μ m or more, can also be 10 μ m or more, and can also be 15 μ m or more.

[0091] Figure 81 is a diagram showing a structural example of a semiconductor device 100. The semiconductor device 100 of this example functions as an insulated gate bipolar transistor (IGBT). The semiconductor device 100 of this example includes a semiconductor substrate 10, an interlayer insulating film 38, an emitter 52, and a collector 54. The interlayer insulating film 38 is formed so as to cover at least a portion of the upper surface 21 of the semiconductor substrate 10. Through holes such as contact holes are formed in the interlayer insulating film 38. The upper surface 21 of the semiconductor substrate 10 is exposed through the contact holes. The interlayer insulating film 38 may be a silicate glass such as PSG or BPSG, or may be an oxide film or a nitride film.

[0092] The emitter electrode 52 is formed on the upper surface of the semiconductor substrate 10 and the interlayer insulating film 38. The emitter electrode 52 is also formed inside the contact hole and is in contact with the upper surface 21 of the semiconductor substrate 10 exposed through the contact hole.

[0093] The collector electrode 54 is formed on the lower surface 23 of the semiconductor substrate 10. The collector electrode 54 may be in contact with the entire lower surface 23 of the semiconductor substrate 10. The emitter electrode 52 and the collector electrode 54 are formed of a metal material such as aluminum.

[0094] In the semiconductor substrate 10 of this example, an N-type drift region 18, an N+ type emitter region 12, a P-type base region 14, an N+ type accumulation region 16, an N+ type buffer region 20 and a P+ type collector region 22 are provided.

[0095] The emitter region 12 is provided in contact with the upper surface 21 of the semiconductor substrate 10, and is a region having a higher donor concentration than the drift region 18. The emitter region 12 contains N-type impurities such as phosphorus, for example.

[0096] The base region 14 is provided between the emitter region 12 and the drift region 18. The base region 14 contains, for example, P-type impurities such as boron.

[0097] The accumulation region 16 is provided between the base region 14 and the drift region 18, and has one or more donor concentration peaks having a higher donor concentration than that of the drift region 18. The accumulation region 16 may contain N-type impurities such as phosphorus, or may contain hydrogen.

[0098] The collector region 22 is provided in contact with the lower surface 23 of the semiconductor substrate 10. The acceptor concentration of the collector region 22 may be higher than that of the base region 14. The collector region 22 may contain the same P-type impurities as the base region 14, or may contain different P-type impurities.

[0099] The buffer region 20 is provided between the collector region 22 and the drift region 18, and has one or more donor concentration peaks having a higher donor concentration than the drift region 18. The buffer region 20 has N-type impurities such as hydrogen. The buffer region 20 can function as a field stop layer that prevents the depletion layer extending from the lower surface side of the base region 14 from reaching the collector region 22.

[0100] Figure 1 to Figure 7 The hydrogen-containing region 102 described in the above is included in the buffer region 20. In this example, the hydrogen-containing region 102 functions as the entire buffer region 20. The buffer region 20 in this example has Figure 1 to Figure 7 The buffer zone 20 may also have a high concentration zone 106 as described above. Figure 1 to Figure 7 The lifetime control region 104 described in FIG.

[0101] By providing the high concentration region 106 in the buffer region 20, the carrier concentration distribution of the buffer region 20 can be made gentle near the drift region 18. Therefore, when the semiconductor device 100 is switched, the waveforms of the voltage and current can be changed smoothly. In addition, since the donor concentration near the drift region 18 can be increased, the extension of the depletion layer from the lower surface side of the base region 14 can be further suppressed.

[0102] The gate groove portion 40 penetrates the emitter region 12, the base region 14 and the accumulation region 16 from the upper surface 21 of the semiconductor substrate 10 to reach the drift region 18. The accumulation region 16 of this example is arranged at a position above the lower end of the gate groove portion 40. The accumulation region 16 can be provided in a manner covering the entire lower surface of the base region 14. By providing the accumulation region 16 having a higher concentration than the drift region 18 between the drift region 18 and the base region 14, the carrier injection promotion effect (IE effect, Injection-Enhancement effect) can be improved, thereby reducing the on-state voltage in the IGBT.

[0103] The gate trench portion 40 includes a gate trench formed on the upper surface side of the semiconductor substrate 10, a gate insulating film 42, and a gate conductive portion 44. The gate insulating film 42 is formed in a manner covering the inner wall of the gate trench. The gate insulating film 42 can be formed by oxidizing or nitriding the semiconductor of the inner wall of the gate trench. The gate conductive portion 44 is formed inside the gate trench at a position closer to the inner side than the gate insulating film 42. That is, 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.

[0104] The gate conductive portion 44 includes a region facing the base region 14 via a gate insulating film 42. The gate groove portion 40 in this cross section is covered by the interlayer insulating film 38 on the upper surface of the semiconductor substrate 10, but the gate conductive portion 44 is connected to the gate electrode in other cross sections. If a predetermined gate voltage is applied to the gate conductive portion 44, a channel formed by an inversion layer of electrons is formed in the surface layer of the interface in contact with the gate groove portion 40 in the base region 14.

[0105] Fig. 9 Yes means Figure 8 A diagram showing an example of the carrier concentration distribution in the depth direction at the position of the BB line. Fig. 9The vertical axis is a logarithmic axis representing the carrier concentration, and the horizontal axis is a linear axis representing the distance from the lower surface 23 .

[0106] The carrier concentration distribution in the buffer region 20 of this example has a plurality of first peaks 111 disposed at different positions in the depth direction. The buffer region 20 has a high concentration region 106 between the first peaks 111. The buffer region 20 may have a high concentration region 106 between the first peak 111 closest to the drift region 18 among the plurality of first peaks 111 and the drift region 18. By providing the high concentration region 106, it is easy to suppress the depletion layer from expanding from the upper surface 21 side.

[0107] The accumulation region 16 of this example has a plurality of peaks 25, but the accumulation region 16 may also have a single peak 25. Peak 25 is a peak of donor concentration. Peak 25 may also be formed by injecting hydrogen. In this case, a high concentration region 106 may also be provided in the accumulation region 16. The lifetime control region 104 may be provided below the accumulation region 16, and a high concentration region 106 may be provided inside the accumulation region 16. The high concentration region 106 may function as a peak 25 in the accumulation region 16. In addition, the high concentration region 106 may be formed in the entire depth direction of the accumulation region 16.

[0108] Fig.10 FIG. 1 is a diagram showing a part of the steps in the method for manufacturing the semiconductor device 100. Fig.10 , the process of forming the high concentration region 106 is shown. Fig.10 Before and after the process shown, the Figure 8 The structures shown.

[0109] In S902, hydrogen ions are implanted from the lower surface 23 of the semiconductor substrate 10. In S902, the hydrogen ions may be implanted multiple times with varying ranges. Next, in S904, the semiconductor substrate 10 is annealed. Thus, hydrogen donors and VOH defects are generated, and the hydrogen-containing region 102 is formed.

[0110] Next, in S906, helium or other impurities for adjustment are injected into the hydrogen-containing region 102. Figure 5 As described in the above, it is preferred to inject helium in such a way that the width Wk of the third peak 113 of the helium concentration distribution is wider than the interval between the fifth peaks 115 of the hydrogen chemical concentration distribution. In S906, the third peak 113 with a large width Wk can be formed by injecting helium multiple times by changing the range. The helium concentration distribution can have multiple third peaks 113. The range of helium ions in the silicon substrate is 10 μ About m.

[0111] It should be noted that Figure 7In the embodiment of the invention, when the width W2 of the second peak 112 is widened by injecting helium ions once, the acceleration energy can be further increased. At this time, since the range of the helium ions is deeper than the predetermined position, an absorber such as aluminum of a predetermined thickness is inserted between the helium ion accelerator and the semiconductor substrate. By utilizing the absorber to absorb the energy of the helium ions, the second peak 112 of the helium ions can be adjusted to a predetermined depth from the injection surface of the semiconductor substrate. As an example, the acceleration energy of the helium ions is 24 MeV, and the full width at half maximum is 12 μ About m.

[0112] Next, in S908 , the semiconductor substrate 10 is annealed. The annealing conditions in S908 may be the same as or different from the annealing conditions in S904 . In S908 , the semiconductor substrate 10 is heat treated to form a high concentration region 106 in the hydrogen-containing region 102 .

[0113] In S902 and S906, the concentration of the implanted hydrogen or helium can be adjusted according to the carbon concentration contained in the semiconductor substrate 10. For example, the higher the carbon concentration contained in the semiconductor substrate 10, the lower the concentration of the implanted hydrogen or helium can be. Thus, regardless of the carbon concentration contained in the semiconductor substrate 10, a high concentration region 106 with a constant concentration can be formed.

[0114] Fig.11 FIG. 1 is a diagram showing an example of voltage and current waveforms during the reverse recovery operation of the semiconductor device 100. Fig.11 Shown in Figure 8 The waveform of the semiconductor device 100 of the embodiment and the waveform of the semiconductor device of the comparative example. The semiconductor device of the comparative example is different from the semiconductor device 100 in that it does not have the high concentration region 106. The other structures are the same as those of the semiconductor device 100.

[0115] like Fig.11 As shown in FIG. 1 , in the comparative example, the di / dt of the current waveform becomes larger just before the reverse recovery current disappears. Therefore, a relatively large surge in the voltage waveform is generated. In contrast, according to the embodiment, since the carrier concentration distribution of the buffer zone 20 is gentle, the current waveform can be made gentle until the end of the reverse recovery action. Therefore, the surge in the voltage waveform can be suppressed.

[0116] The present invention has been described above using the embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments. Those skilled in the art will appreciate that various changes or improvements may be made to the above embodiments. According to the claims, such changes or improvements are also included in the technical scope of the present invention.

[0117] It should be noted that the execution order of each process such as actions, sequences, steps and stages in the apparatus, system, program and method shown in the claims, specifications and drawings can be implemented in any order unless it is specifically stated "before", "in advance", etc., and the result of the previous process is not used in the post-processing. Even if the action flow in the claims, specifications and drawings is described using "first", "next", etc. for convenience, it does not mean that it must be implemented in this order.

Claims

1. A semiconductor device, characterized in that: A semiconductor substrate (10) is provided. The semiconductor substrate comprises an N-type drift region (18) and a hydrogen-containing region (102) containing hydrogen. The hydrogen-containing region has a high concentration region (106) having a carrier concentration higher than a virtual carrier concentration, wherein the virtual carrier concentration is a concentration obtained by multiplying a chemical concentration of hydrogen contained therein by an activation rate of hydrogen. The carrier concentration distribution of the hydrogen-containing region (102) in the depth direction has a plurality of first peaks (111) and slopes (117).

2. The semiconductor device according to claim 1, wherein: The slope is arranged between a first peak (111-4) closest to the drift region among a plurality of first peaks and the drift region (18).

3. The semiconductor device according to claim 1 or 2, characterized in that: The impurity concentration distribution of the drift region is flat within a predetermined depth range.

4. The semiconductor device according to any one of claims 1 to 3, characterized in that The slope is the high concentration area.

5. The semiconductor device according to any one of claims 1 to 3, characterized in that The slope has an upwardly convex shape in which the slope increases as the distance from the lower surface increases.

6. The semiconductor device according to any one of claims 1 to 5, characterized in that The slope of the carrier concentration distribution changes more gently than the slope of the virtual carrier concentration.

7. The semiconductor device according to any one of claims 1 to 6, wherein: The slope of the carrier concentration distribution extends to a deeper position than the slope of the virtual carrier concentration.

8. The semiconductor device according to claim 1, wherein: The carrier concentration of the high concentration region is higher than the basic doping concentration of the semiconductor substrate.

9. The semiconductor device according to any one of claims 1 to 8, characterized in that The carrier concentration distribution has a second peak in the depth direction.

10. The semiconductor device according to claim 9, wherein: At the depth position of the second peak, the carrier concentration is higher than the virtual carrier concentration.

11. The semiconductor device according to any one of claims 1 to 10, wherein: The hydrogen-containing region has a lifetime control region, and the lifetime control region contains an adjustment impurity for adjusting the lifetime of carriers. The chemical concentration distribution of the adjustment impurity in the depth direction has a third peak, The high concentration region is provided at a position deeper than the third peak of the chemical concentration distribution of the adjusting impurity.

12. The semiconductor device according to claim 11, wherein: The width of the third peak is greater than the width of any of the first peaks.

13. The semiconductor device according to claim 11 or 12, characterized in that: The carrier concentration at the position where the third peak is arranged is lower than the virtual carrier concentration.

14. The semiconductor device according to any one of claims 1 to 13, wherein: The oxygen chemical concentration in the high concentration region is 1×10 17 / cm 3 above.

15. The semiconductor device according to any one of claims 1 to 14, characterized in that The carbon chemical concentration in the high concentration region is 1×10 13 / cm 3 above.

16. The semiconductor device according to any one of claims 1 to 13, characterized in that The semiconductor substrate has: An N-type emitter region, which is arranged in contact with the upper surface of the semiconductor substrate and has a carrier concentration higher than that of the drift region; A P-type base region, which is arranged between the emitter region and the drift region; A P-type collector region is provided in contact with the lower surface of the semiconductor substrate; and An N-type buffer region is disposed between the collector region and the drift region, and has a carrier concentration higher than that of the drift region. The hydrogen-containing zone is contained in the buffer zone.

17. A manufacturing method, characterized in that: A method for manufacturing a semiconductor device having a semiconductor substrate including an N-type drift region, characterized in that: injecting hydrogen into the semiconductor substrate to form a hydrogen-containing region, A lifetime control region for adjusting the lifetime of carriers is formed in the hydrogen-containing region, By heat treating the semiconductor substrate, a high concentration region is formed in the hydrogen-containing region. The carrier concentration of the high concentration region is higher than the virtual carrier concentration obtained by multiplying the chemical concentration of the impurity contained by the activation rate of the impurity. The carrier concentration distribution of the hydrogen-containing region in the depth direction has multiple first peaks and slopes.

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