Semiconductor device and method for manufacturing semiconductor device

Abstract

Provided is a semiconductor device including: a buffer region of a first conductivity type disposed on a lower surface side of a semiconductor substrate and having two or more peaks of a doping concentration; a high concentration region of the first conductivity type disposed between the buffer region and an upper surface of the semiconductor substrate, having a length of 50 μm or more in a depth direction, and having a donor concentration higher than a body donor concentration; and a lower surface region of the first conductivity type or a second conductivity type disposed between the buffer region and the lower surface of the semiconductor substrate and having a doping concentration higher than that of the high concentration region, wherein a shallowest peak of the doping concentration peaks of the buffer region closest to the lower surface of the semiconductor substrate is a peak of a hydrogen donor having a higher concentration than other peaks of the doping concentration, and a ratio A / B of a peak concentration A of the shallowest peak to an average peak concentration B of the other peaks of the doping concentration is 200 or less.

Description

Technical Field

[0001] This invention relates to a semiconductor device and a method for manufacturing a semiconductor device. Background Technology

[0002] Previously, techniques for adjusting the doping concentration of semiconductor wafers by injecting hydrogen ions were known (see, for example, Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: US2015 / 0050754 Summary of the Invention

[0006] Technical issues

[0007] It is expected that hydrogen can easily diffuse into regions separate from the hydrogen injection site.

[0008] Technical solution

[0009] To address the aforementioned problems, in one aspect of the present invention, a semiconductor device comprising a semiconductor substrate having an upper surface and a lower surface, and including bulk donors, is provided. The semiconductor device may include a buffer zone of a first conductivity type, disposed on the lower surface side of the semiconductor substrate, and having two or more doping concentration peaks in the depth direction of the semiconductor substrate. The semiconductor device may include a high-concentration region of the first conductivity type, disposed between the buffer zone and the upper surface of the semiconductor substrate, having a length of 50 μm or more in the depth direction, and having a donor concentration higher than the bulk donor concentration. The semiconductor device may include a lower surface region of a first or second conductivity type, disposed between the buffer zone and the lower surface of the semiconductor substrate, and having a doping concentration higher than the high-concentration region. The shallowest doping concentration peak closest to the lower surface of the semiconductor substrate among the doping concentration peaks of the buffer zone may be a concentration peak of hydrogen donors with a higher concentration than other doping concentration peaks. The ratio A / B of the peak concentration A of the shallowest doping concentration peak to the average peak concentration B of other doping concentration peaks may be 200 or less.

[0010] Semiconductor devices may have impurity chemical concentration peaks disposed on the upper surface side of a semiconductor substrate. The impurity chemical concentration can decrease sharply compared to an upper tail where the impurity chemical concentration decreases from the peak towards the upper surface, rather than a lower tail where the impurity chemical concentration decreases from the peak towards the lower surface. The high concentration region can be set from the lightest doping concentration peak to the impurity chemical concentration peak.

[0011] The high-concentration region can extend from the shallowest doping concentration peak toward the upper surface of the semiconductor substrate with a length of more than 80 μm.

[0012] The high-concentration region can have a length that is more than 40% of the thickness in the depth direction of the semiconductor substrate.

[0013] The ratio of A to B can be 2 or higher.

[0014] The ratio of the dose C of the shallowest doping concentration peak to the total dose D of the other doping concentration peaks, C / D, can be greater than 6 and less than 100.

[0015] In a second aspect of the invention, a method for manufacturing a semiconductor device is provided. The manufacturing method may include a first implantation step of implanting hydrogen ions from the lower surface of a semiconductor substrate having an upper surface and a lower surface and containing a body donor to a first location, and implanting charged particles to a second location closer to the upper surface than the first location. The manufacturing method may include a first annealing step of annealing the semiconductor substrate to form a high-concentration region between the first and second locations where the donor concentration is higher than the body donor concentration. The manufacturing method may include a second implantation step of implanting an N-type dopant to one or more third locations between the first and second locations.

[0016] The second position can be configured on the upper surface of the semiconductor substrate, and the third position can be configured on the lower surface of the semiconductor substrate.

[0017] The manufacturing method may include a second annealing step after the second implantation step, in which the semiconductor substrate is annealed.

[0018] The annealing temperatures for both the first and second annealing steps can be above 350°C and below 400°C.

[0019] The temperature difference between the first annealing step and the second annealing step can be less than 10°C.

[0020] In the second injection step, hydrogen ions can be injected into the first position.

[0021] The second dose of hydrogen ions injected into the first position in the second injection step may be lower than the first dose of hydrogen ions injected into the first position in the first injection step.

[0022] The first dose can be 1×10 14 ions / cm 2 That's all. The second dose can be 3×10. 13 ions / cm 2 above.

[0023] It should be noted that the above description of the invention does not list all the essential features of the invention. Furthermore, sub-combinations of these feature groups can also constitute an invention. Attached Figure Description

[0024] Figure 1 This is a cross-sectional view illustrating an example of a method for manufacturing a semiconductor device 100.

[0025] Figure 2 Show Figure 1 The lattice defect density D at the location indicated by line AA in the depth direction. V Hydrogen chemical concentration C H Doping concentration D d and the chemical concentration of impurities C I The distribution of each.

[0026] Figure 3 The lattice defect density D of the comparative example is shown. V Hydrogen chemical concentration C H Doping concentration D d and the chemical concentration of impurities C I The distribution of each.

[0027] Figure 4 This shows the hydrogen chemical concentration C near buffer zone 20. H and doping concentration D d A graph showing the distribution of [something].

[0028] Figure 5A This is a flowchart illustrating an example of a method for manufacturing a semiconductor device 100.

[0029] Figure 5B This is a flowchart illustrating another example of a method for manufacturing a semiconductor device 100.

[0030] Figure 6A This is a flowchart illustrating another example of a method for manufacturing a semiconductor device 100.

[0031] Figure 6B This is a flowchart illustrating another example of a method for manufacturing a semiconductor device 100.

[0032] Figure 7 This shows the hydrogen chemical concentration C near buffer zone 20. H The distribution of examples is shown in the figure.

[0033] Figure 8 This shows the doping concentration D near buffer 20 under the condition of dose variation of hydrogen ions for the first depth position Z1. d A graph showing the changes.

[0034] Figure 9A This is a graph illustrating the relationship between the hydrogen chemical concentration peak 131-1 and the doping concentration peak 111-1.

[0035] Figure 9B This is a graph illustrating the relationship between the impurity chemical concentration peak 141 and the doping concentration peak 121.

[0036] Figure 9C This is a diagram illustrating the slope of the lower trailing edge 142.

[0037] Figure 10A This is a diagram illustrating another standardized definition of the slope of the lower trailing edge 112.

[0038] Figure 10B This is a diagram illustrating another standardized definition of the slope of the lower trailing edge 122.

[0039] Figure 11 This is a graph showing the relationship between ε' and γ as shown in Equation (12) for each β.

[0040] Figure 12 This shows the concentration of donor N in vivo. Bre A diagram illustrating one example of the preferred range.

[0041] Figure 13 This shows the bulk donor concentration N when ε' is in the range B (above 0.01 and below 0.333). Bre A diagram illustrating an example of the preferred range.

[0042] Figure 14 This shows the bulk donor concentration N when ε' is in the range C (above 0.03 and below 0.25). Bre A diagram illustrating an example of the preferred range.

[0043] Figure 15 This shows the bulk donor concentration N when ε' is in the range D (above 0.1 and below 0.2). Bre A diagram illustrating an example of the preferred range.

[0044] Figure 16 This shows the bulk donor concentration N when ε' is in the range E (above 0.001 and below 0.1). Bre A diagram illustrating one example of the preferred range.

[0045] Figure 17 This shows the bulk donor concentration N when ε' is in the range F (above 0.002 and below 0.05). Bre A diagram illustrating one example of the preferred range.

[0046] Figure 18 This shows the bulk donor concentration N when ε' is in the range G (above 0.005 and below 0.02). Bre A diagram illustrating an example of the preferred range.

[0047] Figure 19This shows the bulk donor concentration N when ε' is in the range H (0.01 ± 0.002). Bre A diagram illustrating an example of the preferred range.

[0048] Figure 20 This is an example of a top view of a semiconductor device 100.

[0049] Figure 21 yes Figure 20 An enlarged view of region A in the image.

[0050] Figure 22A It is shown Figure 21 A diagram of an example of the bb section.

[0051] Figure 22B It is shown Figure 22A The doping concentration D at the dd line d The distribution of examples is shown in the figure.

[0052] Figure 23 It is shown Figure 21 Another example of the bb section is shown in the figure.

[0053] Symbol Explanation

[0054] 10: Semiconductor substrate; 11: Well region; 12: Emitter region; 14: Base region; 15: Contact region; 16: Accumulation region; 18: Bulk donor region; 19: Drift region; 20: Buffer zone; 21: Upper surface; 22: Collector region; 23: Lower surface; 24: Collector electrode; 29: Straight portion; 30: Dummy trench portion; 31: Front end portion; 32: Dummy insulating film; 34: Dummy conductive portion; 38: Interlayer insulating film; 3 9: Straight section; 40: Gate trench section; 41: Front end section; 42: Gate insulating film; 44: Gate conductive section; 52: Emitter electrode; 54: Contact hole; 60, 61: Mesa section; 70: Transistor section; 80: Diode section; 81: Extension region; 82: Cathode region; 90: Edge termination structure section; 92: Guard ring; 100: Semiconductor device; 102: Edge; 106: Through area; 111: Doped Impurity concentration peak; 112: Lower tail; 113: Upper tail; 114: Slope; 121: Doping concentration peak; 122: Lower tail; 123: Upper tail; 124: Slope; 125: Slope; 129: Active-side gate wiring; 130: Peripheral gate wiring; 131: Hydrogen chemical concentration peak; 132: Lower tail; 133: Upper tail; 134: Slope; 141: Impurity chemical concentration peak; 14 2: Lower tail; 143: Upper tail; 144: Slope; 145: Slope; 150: High concentration region; 160: Active part; 164: Gate pad; 171: Chemical concentration peak; 181: Low concentration region; 201: Lower surface region; 211: First defect density peak; 212: Second defect density peak; 213: Defect density peak; 311: Upper limit; 312: Lower limit; 313: Upper limit; 314: Lower limit Detailed Implementation

[0055] The present invention will now be described through embodiments thereof; however, these embodiments do not limit the invention as defined in the claims. Furthermore, not all combinations of the features described in the embodiments are necessarily required for the inventive solution.

[0056] In this specification, one side parallel to the depth direction of the semiconductor substrate is referred to as "upper," and the other side as "lower." One of the two main surfaces of the substrate, layer, or other component is referred to as the upper surface, and the other as the lower surface. The directions of "upper" and "lower" are not limited to the direction of gravity or the direction when mounting the semiconductor device.

[0057] In this specification, orthogonal coordinate axes of X, Y, and Z are sometimes used to illustrate technical matters. Orthogonal coordinate axes only determine the relative positions of constituent elements and do not limit specific directions. For example, the Z-axis is not limited to representing the height direction relative to the ground. It should be noted that the +Z-axis direction and the -Z-axis direction are opposite to each other. When a direction is referred to as the Z-axis without specifying positive or negative, it refers to a direction parallel to the +Z-axis and -Z-axis.

[0058] In this specification, orthogonal axes parallel to the upper and lower surfaces of the semiconductor substrate are designated as the X-axis and Y-axis. Furthermore, an axis perpendicular to the upper and lower surfaces of the semiconductor substrate is designated as the Z-axis. In this specification, the direction of the Z-axis is sometimes referred to as the depth direction. Additionally, in this specification, the direction parallel to the upper and lower surfaces of the semiconductor substrate, including the X-axis and Y-axis, is sometimes referred to as the horizontal direction.

[0059] Furthermore, the region extending from the center of the semiconductor substrate in the depth direction to the upper surface of the semiconductor substrate is sometimes referred to as the upper surface side. Similarly, the region extending from the center of the semiconductor substrate in the depth direction to the lower surface of the semiconductor substrate is sometimes referred to as the lower surface side. In this specification, the center position in the depth direction of the semiconductor substrate is sometimes referred to as Zc.

[0060] In this specification, the terms "same" or "equal" may also include cases with errors due to manufacturing deviations, etc. Such errors are, for example, within 10%.

[0061] In this specification, the conductivity type of the doped region containing impurities is described as P-type or N-type. In this specification, impurities sometimes specifically refer to either an N-type donor or a P-type acceptor, and are sometimes referred to as dopant. In this specification, doping refers to introducing donors or acceptors into a semiconductor substrate, thereby creating a semiconductor exhibiting an N-type conductivity type or a P-type conductivity type.

[0062] In this specification, doping concentration refers to the donor or acceptor concentration under thermal equilibrium conditions. In this specification, net doping concentration refers to the actual concentration obtained by adding the donor concentration (positive ions) and acceptor concentration (negative ions), taking into account charge polarity. For example, if the donor concentration is set to N... D Set the acceptor concentration to N A Then the actual net doping concentration at any position is N. D -N A In this specification, net doping concentration is sometimes abbreviated as doping concentration.

[0063] Donors have the function of supplying electrons to semiconductors. Acceptors have the function of accepting electrons from semiconductors. Donors and acceptors are not limited to impurities themselves. For example, VOH defects, which are formed by the combination of vacancies (V), oxygen (O), and hydrogen (H) in semiconductors, function as electron-supplying donors. In this specification, VOH defects are sometimes referred to as hydrogen donors.

[0064] In this specification, when referred to as P+ or N+ type, it means that the doping concentration is higher than that of P- or N- type; when referred to as P- or N- type, it means that the doping concentration is lower than that of P- or N- type. Similarly, when referred to as P++ or N++ type, it means that the doping concentration is higher than that of P+ or N+ type. Unless otherwise stated, the unit system in this specification is SI. Although length is sometimes expressed in cm, calculations can be performed after conversion to meters (m).

[0065] In this specification, chemical concentration refers to the atomic density of impurities measured independently of the state of electroactivation. Chemical concentration (atomic density) can be measured, for example, by secondary ion mass spectrometry (SIMS). The net doping concentration described above can be determined by voltage-capacitance measurement (CV method). Alternatively, the carrier concentration measured by diffusion resistance measurement (SR method) can be used as the net doping concentration. The carrier concentration measured by CV or SR methods can be considered as the value under thermal equilibrium conditions. Furthermore, in the N-type region, the donor concentration is sufficiently greater than the acceptor concentration; therefore, 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 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.

[0066] Furthermore, when the concentration distribution of donor, acceptor, or net dopant has a peak, the peak value can be taken as the concentration of the donor, acceptor, or net dopant in that region. When the concentrations of donor, acceptor, or net dopant are approximately uniform, the average concentration of the donor, acceptor, or net dopant in that region can be taken as the concentration of the donor, acceptor, or net dopant. In this specification, atoms / cm² is sometimes used. 3 or / cm 3 This unit represents the concentration per unit volume. It indicates the donor or acceptor concentration, or chemical concentration, within a semiconductor substrate. The "atoms" designation can be omitted.

[0067] The carrier concentration measured by the SR method can be lower than the donor or acceptor concentration. During the measurement of diffusion resistance, within the range of current flow, the carrier mobility of the semiconductor substrate is sometimes lower than that of the crystalline state. This decrease in carrier mobility is caused by the dispersion of carriers due to the disorder (disorder) of the crystal structure caused by lattice defects, etc.

[0068] The donor or acceptor concentration calculated from the carrier concentration measured by CV or SR methods can be lower than the chemical concentration of the element representing the donor or acceptor. For example, in silicon semiconductors, the donor concentration of phosphorus or arsenic (which are donors) or the acceptor concentration of boron (which is an acceptor) is approximately 99% of their chemical concentration. On the other hand, in silicon semiconductors, the donor concentration of hydrogen (which is a donor) is approximately 0.1% to 10% of the chemical concentration of hydrogen. The concentrations in this specification can be values ​​at room temperature. For example, values ​​at room temperature can be those at 300 K (Kelvin) (approximately 26.9°C).

[0069] When charged particles such as ions or electrons are injected into a semiconductor substrate with a predetermined acceleration energy, these particles have a predetermined distribution in the depth direction. In this specification, the peak position of this distribution is sometimes referred to as the location where the particle is injected or the injection depth, etc.

[0070] Figure 1 This is a cross-sectional view illustrating an example of a manufacturing method for a semiconductor device 100. The semiconductor device 100 includes a semiconductor substrate 10. The semiconductor substrate 10 is a substrate formed of a semiconductor material. As an example, the semiconductor substrate 10 is a silicon substrate.

[0071] At least one of a transistor element such as an insulated-gate bipolar transistor (IGBT) and a diode element such as a freewheeling diode (FWD) is formed on a semiconductor substrate 10. Figure 1 In this diagram, the electrodes of the transistor and diode elements, as well as the regions disposed within the semiconductor substrate 10, are omitted. Examples of the configurations of the transistor and diode elements will be described later.

[0072] In this example, the semiconductor substrate 10 is generally distributed with N-type body donors. Body donors are donors formed by dopants that are contained substantially uniformly within the ingot during the manufacture of the raw material for the semiconductor substrate 10. In this example, the body donors are elements other than hydrogen. Dopants for body donors are, for example, phosphorus, antimony, arsenic, selenium, or sulfur, but are not limited to these. In this example, the body donor is phosphorus. Body donors are also contained within P-type regions. The semiconductor substrate 10 can be a wafer cut from a semiconductor ingot or a chip obtained by monolithizing a wafer. The semiconductor ingot can be manufactured using any one of the Czochralski process (CZ process), magnetic field applied Czochralski process (MCZ process), or floating zone melting process (FZ process). In this example, the ingot is manufactured using the MCZ process. The substrate manufactured using the MCZ process contains an oxygen concentration of 1 × 10⁻⁶. 17 ~7×10 17 / cm 3 The oxygen concentration of the substrate manufactured using the FZ method is 1×10⁻⁶. 15 ~5×10 16 / cm 3 The side with a higher oxygen concentration tends to more readily generate hydrogen donors. The bulk donor concentration can be the chemical concentration of bulk donors distributed throughout the semiconductor substrate 10, or a value between 90% and 100% of that chemical concentration. Alternatively, the semiconductor substrate 10 can be an undoped substrate that does not contain dopants such as phosphorus. In this case, the bulk donor concentration of the undoped substrate is, for example, 1 × 10⁻⁶. 10 / cm 3 Above and 5×10 12 / cm 3 The bulk donor concentration of the undoped substrate is preferably 1×10⁻⁶. 11 / cm 3 The above. The preferred bulk donor concentration for the undoped substrate is 5 × 10⁻⁶. 12 / cm 3 the following.

[0073] The semiconductor substrate 10 has an upper surface 21 and a lower surface 23. The upper surface 21 and the lower surface 23 are the two main surfaces of the semiconductor substrate 10. In this specification, the orthogonal axes in the planes parallel to the upper surface 21 and the lower surface 23 are designated as the X-axis and the Y-axis, and the axis perpendicular to the upper surface 21 and the lower surface 23 is designated as the Z-axis.

[0074] An N-type buffer 20 is provided on the lower surface 23 side of the semiconductor substrate 10 (i.e., the region between the lower surface 23 and the central position Zc in the depth direction). A lower surface region 201 is provided between the buffer 20 and the lower surface 23. The lower surface region 201 is an N-type or P-type region with a higher doping concentration than the high-concentration region 150 described later. The lower surface region 201 can be a cathode region or a collector region described later. The buffer 20 suppresses the depletion layer extending from the upper surface 21 side of the semiconductor substrate 10 from reaching the lower surface region 201 (punch through).

[0075] The buffer zone 20 has multiple doping concentration peaks 111 along the depth direction of the semiconductor substrate 10. Figure 1 In the example, doping concentration peaks 111-1, 111-2, 111-3, and 111-4 are sequentially present from the lower surface 23 side. By setting multiple doping concentration peaks 111, the extension of the depletion layer to the lower surface region 201 can be suppressed. In this specification, doping concentration peak 111-1 is sometimes referred to as the shallowest doping concentration peak. The doping concentration of doping concentration peak 111-1 is higher than that of the other doping concentration peaks 111. The buffer 20 may contain hydrogen donors.

[0076] In this manufacturing method, multiple doping concentration peaks in the buffer zone 20 are formed in two steps. In the first step S1001, charged particles are implanted from the lower surface 23 of the semiconductor substrate 10 to a second depth position Z2. The charged particles are, for example, hydrogen ions, helium ions, electrons, etc. In this example, the semiconductor substrate 10 has an impurity chemical concentration peak 141 of hydrogen or helium, etc., at the second depth position Z2. It should be noted that the second depth position Z2 can be a position higher than the upper surface 21. That is, the charged particles can be implanted in a manner that penetrates the semiconductor substrate 10.

[0077] The depth position refers to the position in the depth direction (Z-axis direction) of the semiconductor substrate 10. In this specification, the distance from the lower surface 23 to each position is sometimes referred to as the depth position of each position. For example, the second depth position Z2 is the distance Z2 measured from the lower surface 23. The second depth position Z2 can be disposed on the side of the upper surface 21 of the semiconductor substrate 10 (i.e., the region between the upper surface 21 and the central position Zc in the depth direction).

[0078] The average distance (also called range) that charged particles travel through the interior of the semiconductor substrate 10 can be controlled by the acceleration energy used to accelerate them. In this example, the acceleration energy is set such that the average range of the charged particles is the distance Z2. The average range Z2 of the charged particles can be greater than half the thickness of the semiconductor substrate 10 in the depth direction.

[0079] In this specification, the region through which the injected charged particle passes is sometimes referred to as the passage region 106. Figure 1 In the example, the region 106 extends from the lower surface 23 of the semiconductor substrate 10 to the second depth position Z2. Figure 1 In one example, charged particles are injected from the entire lower surface 23 of the semiconductor substrate 10. In other examples, charged particles may be injected only into a portion of the lower surface 23. This also allows for the local formation of a through region 106 in the XY plane.

[0080] Furthermore, in the first step S1001, protons and other hydrogen ions are implanted from the lower surface 23 of the semiconductor substrate 10 to a first depth position Z1. After the hydrogen ion implantation, the entire semiconductor substrate 10 is annealed. As a result, a doping concentration peak 111-1 based on hydrogen donors is formed at the first depth position Z1. It should be noted that during annealing, no impurity ions other than the aforementioned hydrogen ions and charged particles are locally implanted between the first depth position Z1 and the second depth position Z2.

[0081] In the semiconductor substrate 10, in the passage region 106 through which charged particles pass, lattice defects dominated by vacancies, such as single-atom vacancies (V) and diatomic vacancies (VV), are formed due to the passage of charged particles. The atoms adjacent to the vacancies have dangling bonds. Although lattice defects also include interstitial atoms and / or dislocations, and can broadly include donors and / or acceptors, in this specification, lattice defects dominated by vacancies are sometimes referred to as vacancy-type lattice defects, vacancy-type defects, or simply lattice defects. Furthermore, there are cases where a large number of lattice defects are formed by injecting charged particles into the semiconductor substrate 10, thereby severely disrupting the crystallinity of the semiconductor substrate 10. In this specification, this disruption of crystallinity is sometimes referred to as disorder.

[0082] Furthermore, oxygen is present throughout the semiconductor substrate 10. This oxygen is intentionally or unintentionally introduced during the manufacture of the semiconductor ingot. Inside the semiconductor substrate 10, hydrogen (H), vacancies (V), and oxygen (O) combine to form VOH defects. Moreover, heat treatment of the semiconductor substrate 10 causes hydrogen implanted at the first depth position Z1 to diffuse, promoting the formation of VOH defects. When the charged particles implanted at the second depth position Z2 are hydrogen ions, hydrogen also diffuses from the second depth position Z2, further promoting the formation of VOH defects.

[0083] VOH defects function as electron donors. In this specification, VOH defects are sometimes simply referred to as hydrogen donors. In this example, hydrogen donors are formed in the region 106 through which charged particles pass. The doping concentration of hydrogen donors is lower than the chemical concentration of hydrogen. If the ratio of the doping concentration of hydrogen donors to the chemical concentration of hydrogen is defined as the activation rate, the activation rate can be a value from 0.1% to 30%. In this example, the activation rate is from 1% to 5%.

[0084] By forming hydrogen donors in the passage region 106 of the semiconductor substrate 10, the donor concentration in the passage region 106 can be made higher than the bulk donor concentration. Typically, a semiconductor substrate 10 with a predetermined bulk donor concentration must be prepared, corresponding to the characteristics of the device to be formed on the semiconductor substrate 10, particularly the rated voltage or withstand voltage. In this regard, according to... Figure 1 The semiconductor device 100 shown can adjust the donor concentration of the semiconductor substrate 10 by controlling the dosage of charged particles and hydrogen ions. Therefore, the semiconductor device 100 can be manufactured using a semiconductor substrate 10 with a bulk donor concentration that does not correspond to the characteristics of the device. Although the deviation in bulk donor concentration during the manufacture of the semiconductor substrate 10 is relatively large, the dosage of charged particles and hydrogen ions can be controlled with high precision. Therefore, the concentration of lattice defects generated by the implantation of charged particles can also be controlled with high precision, and furthermore, the concentration of hydrogen bound to lattice defects can be controlled with high precision. Therefore, the donor concentration through region 106 can be controlled with high precision.

[0085] Furthermore, it is preferable that the hydrogen injected into the first depth position Z1 diffuses towards the upper surface 21 to a more distant position. This allows for an increase in the length of the region 106 in the Z-axis direction and facilitates adjustment of the doping concentration over a wide area of ​​the semiconductor substrate 10.

[0086] If impurities other than hydrogen ions and charged particles are injected between the first depth position Z1 and the second depth position Z2, a large number of lattice defects will form in the vicinity of the injection position. In the region where a large number of lattice defects are formed, the diffusion of hydrogen ions is suppressed. Therefore, if there is a region with a high density of lattice defects between the first depth position Z1 and the second depth position Z2, the diffusion of hydrogen is suppressed.

[0087] In this example, after the first step S1001, in which the hydrogen injected into the first depth position Z1 diffuses through region 106, other doping concentration peaks 111-2, 111-3, and 111-4 are formed in the second step S1002. That is, in the second step S1002, N-type dopants such as hydrogen ions are injected into one or more depth positions between the first depth position Z1 and the second depth position Z2 and annealed. As a result, doping concentration peaks 111-2, 111-3, and 111-4 are formed. Thus, by forming doping concentration peaks 111-2, 111-3, and 111-4 after the hydrogen injected into the first depth position Z1 diffuses, it is possible to both allow hydrogen to diffuse to deeper positions and set multiple doping concentration peaks 111 in the buffer zone 20.

[0088] Figure 2 Show Figure 1 The lattice defect density D at the location indicated by line AA in the depth direction. V Hydrogen chemical concentration C H Doping concentration D d and the chemical concentration of impurities C I The distribution of each component. In this example, the impurities are helium or hydrogen. Figure 2 The horizontal axis represents the depth position measured from the lower surface 23, and the vertical axis represents the chemical concentration of hydrogen, donor concentration, and impurity chemical concentration per unit volume in logarithmic form. Figure 2 The lattice defect density D in the distribution V yes Figure 1 The distribution at the start of annealing in the first step S1001 is shown. Concentrations other than lattice defects are shown. Figure 1 The distribution after annealing in the second step S1002 is shown.

[0089] Figure 2 The chemical concentrations of hydrogen and impurities in the sample are measured, for example, by the SIMS method. Figure 2 The doping concentration is the electrically activated doping concentration, measured by, for example, the CV method or SR method.

[0090] In this example, the hydrogen chemical concentration C H A hydrogen chemical concentration peak 131-1 is present at the first depth position Z1. The hydrogen chemical concentration peak 131 shows a maximum value at the first depth position Z1. Furthermore, the hydrogen chemical concentration C... H A hydrogen chemical concentration peak of 131 is observed at the third depth position Z3. Multiple third depth positions Z3 can be configured. Figure 2 In the example, third depth positions Z3-1, Z3-2, and Z3-3 are configured. Hydrogen chemical concentration peak 131 is configured at each third depth position Z3. Hydrogen chemical concentration peaks 131-2 to 131-4 are based on... Figure 1 The peak of hydrogen ions injected in the second step S1002.

[0091] In this example, the chemical concentration of the impurities is C. I An impurity chemical concentration peak 141 is present at the second depth position Z2. The impurity chemical concentration peak 141 shows a maximum value at the second depth position Z2.

[0092] Doping concentration D d It has multiple doping concentration peaks 111 and 121. In this example, doping concentration peaks 111 are arranged at the first depth position Z1 and each of the third depth positions Z3. Furthermore, the doping concentration D... d The lower surface region 201 may have a doping concentration peak. In this example, the lower surface region 201 has a P-type doping concentration peak. A P-type dopant such as boron may be implanted into the lower surface region 201. In another example, the lower surface region 201 may have an N-type doping concentration peak. In this case, an N-type dopant such as phosphorus may be implanted into the lower surface region 201.

[0093] In this example, the doping concentration peak 111 is the concentration peak of hydrogen donors (VOH defects) formed by the combination of lattice defects created by the implantation of hydrogen ions at the first depth position Z1 and the third depth position Z3. Therefore, the doping concentration peak 111 shows a maximum value at the first depth position Z1 and each of the third depth positions Z3.

[0094] The doping concentration peak 121 is the concentration peak of hydrogen donors formed by the combination of lattice defects created by the injection of charged particles at the second depth position Z2 and hydrogen diffused from the first depth position Z1. Therefore, the doping concentration peak 121 shows a maximum value at the second depth position Z2.

[0095] It should be noted that the location where the doping concentration peak 111-1 exhibits a maximum value does not necessarily coincide strictly with the first depth position Z1. For example, as long as the location where the doping concentration peak 111-1 exhibits a maximum value is included within the full width at half maximum (FWHM) of the first hydrogen chemical concentration peak 131 relative to the first depth position Z1, the doping concentration peak 111-1 can be considered substantially located at the first depth position Z1. Similarly, as long as the location where the doping concentration peak 121 exhibits a maximum value is included within the full FWHM of the impurity chemical concentration peak 141 relative to the second depth position Z2, the doping concentration peak 121 can be considered substantially located at the second depth position Z2. Likewise, as long as the location where the doping concentration peak 111 exhibits a maximum value is included within the full FWHM of the hydrogen chemical concentration peak 131 relative to the third depth position Z3, the doping concentration peak 111 can be considered substantially located at the third depth position Z3.

[0096] Furthermore, when the doping concentration peak 111-1 overlaps with the doping concentration peak of the lower surface region 201 and it is difficult to distinguish the doping concentration peak 111-1, the doping concentration at the depth position Z1 of the vertex of the hydrogen chemical concentration peak 131-1 can be taken as the doping concentration peak 111-1.

[0097] Each concentration peak has a lower tail indicating that the concentration decreases from the apex towards the lower surface 23, and an upper tail indicating that the concentration decreases from the apex towards the upper surface 21. In this example, the hydrogen chemical concentration peak 131 has a lower tail 132 and an upper tail 133. The impurity chemical concentration peak 141 has a lower tail 142 and an upper tail 143. The doping concentration peak 111 has a lower tail 112 and an upper tail 113. The doping concentration peak 121 has a lower tail 122 and an upper tail 123.

[0098] Because hydrogen ions are injected from the lower surface 23 into the first depth position Z1 and the third depth position Z3, a relatively large amount of hydrogen is present between the first depth position Z1 and the lower surface 23, and between the third depth position Z3 and the lower surface 23. Similarly, a large amount of impurities injected as charged particles are present between the second depth position Z2 and the lower surface 23. Therefore, in each concentration peak of each chemical concentration distribution, the concentration of the upper tail can decrease sharply compared to the concentration of the lower tail. Furthermore, since the doping concentration depends on the hydrogen chemical concentration or the impurity chemical concentration, the concentration of the upper tail in each doping concentration peak can also decrease sharply compared to the concentration of the lower tail.

[0099] At the start of the annealing process in the first step S1001, a relatively large number of lattice defects are formed near the first depth position Z1 and the second depth position Z2 due to the implantation of hydrogen ions or charged particles. Therefore, the lattice defect density D... V A first defect density peak 211 is present at the first depth position Z1, and a second defect density peak 212 is present at the second depth position Z2. Furthermore, in the passage region 106 from the second depth position Z2 to the lower surface 23 (see reference...) Figure 1 In the region, except near the first depth position Z1 and the second depth position Z2, lattice defects caused by the passage of charged particles form at a substantially uniform density. Figure 2 Lattice defect density D V The distribution diagram is shown by the dashed line, representing the lattice defect density D. V The density can be gradually increased towards peak 212 within a range not exceeding peak 212. In this way, the lattice defect density D... V The increase towards peak 212 can also be attributed to lattice defects formed at a roughly uniform density due to the passage of charged particles.

[0100] Hydrogen injected into the first depth position Z1 diffuses toward the upper surface 21 through annealing. During the annealing at the beginning of the first step S1001, hydrogen ions were not injected into the third depth position Z3. Therefore, there are no defect density peaks other than the first defect density peak 211 and the second defect density peak 212 between the first depth position Z1 and the second depth position Z2. Therefore, hydrogen easily diffuses from the first depth position Z1 to the second depth position Z2. In the region 106, VOH defects (hydrogen donors) are formed in the area where hydrogen has diffused to a certain concentration or higher, and a high-concentration region 150 containing hydrogen donors is formed. The high-concentration region 150 has a donor concentration higher than the bulk donor concentration D. b High concentration region. The high concentration region 150 is disposed between the buffer zone 20 and the upper surface 21 of the semiconductor substrate 10.

[0101] The high-concentration region 150 can be a region where the doping concentration is approximately uniform in the depth direction. Approximately uniform doping concentration in the depth direction can mean, for example, that the difference between the maximum and minimum doping concentration values ​​is within 50% of the maximum doping concentration value, and the region is continuous in the depth direction. This difference can be less than 30% of the maximum doping concentration value in the region, or it can be less than 10% of the maximum doping concentration value in the region.

[0102] Alternatively, the value of the doping concentration distribution, relative to the average concentration of the doping concentration distribution within a predetermined range in the depth direction, can be within ±50%, ±30%, or ±10% of the average concentration of the doping concentration distribution. As an example, the predetermined range W in the depth direction can be as follows: that is, the length from the first depth position Z1 to the second depth position Z2 can be set as Z. L And from the center Z between Z1 and Z2 12 c moves 0.25Z away from both the first depth position Z1 and the second depth position Z2. L The length between the two points is 0.5Z. L The interval is set to this range. Based on the length of the high-concentration region 150, the length of the predetermined range can be set to 0.75Z. L It can also be set to 0.3Z L It can also be set to 0.9Z L The end position of the upper surface 21 side of the buffer 20 can be the depth position where the approximately uniform doping concentration in the high concentration region 150 begins to monotonically increase toward the doping concentration peak 111-1.

[0103] Furthermore, when starting the annealing in the first step S1001, it is preferable that there are no doping concentration peaks other than doping concentration peaks 111-1 and 121 between the first depth position Z1 and the second depth position Z2. Furthermore, it is preferable that there are no chemical concentration peaks other than hydrogen chemical concentration peak 131-1 and impurity chemical concentration peak 141 between the first depth position Z1 and the second depth position Z2. As a result, hydrogen can easily diffuse from the first depth position Z1 to the second depth position Z2.

[0104] By facilitating hydrogen diffusion, the high-concentration region 150 can be formed longer in the depth direction. The high-concentration region 150 can be continuously set from the position in contact with the doping concentration peak 111-1 to the impurity chemical concentration peak 141. The high-concentration region 150 can be continuously set from the upper end of the buffer zone 20 to the second depth position Z2.

[0105] The length of the high-concentration region 150 in the depth direction can be 40% or more of the thickness of the semiconductor substrate 10 in the depth direction, 50% or more of the thickness of the semiconductor substrate 10 in the depth direction, 60% or more of the thickness of the semiconductor substrate 10 in the depth direction, 70% or more of the thickness of the semiconductor substrate 10 in the depth direction, or 80% or more of the thickness of the semiconductor substrate 10 in the depth direction. The length of the high-concentration region 150 can be a length L1 from the upper end of the buffer zone 20 to the upper end of the high-concentration region 150, or a length L2 from the position Z1 of the doping concentration peak 111-1 to the upper end of the high-concentration region 150. The upper end of the high-concentration region 150 can be the depth position Z2. Furthermore, the length of the high-concentration region 150 in the depth direction can be 50 μm or more, 60 μm or more, 70 μm or more, 80 μm or more, 90 μm or more, or 100 μm or more. In this example, since hydrogen can easily diffuse to the second depth position Z2, the area where the high concentration region 150 is formed can be easily defined by the second depth position Z2.

[0106] The minimum donor concentration in the high-concentration region 150 is greater than the bulk donor concentration D of the semiconductor substrate 10. b High. That is, the donor concentration (or doping concentration) in the high-concentration region 150 is higher than the bulk donor concentration D throughout the entire high-concentration region 150. bThe donor concentration in the high-concentration region 150 is determined by the sum of the bulk donor concentration and the hydrogen donor concentration (VOH defect concentration). The hydrogen donor concentration can be precisely controlled using the dose of charged particles at the second depth position Z2 and the dose of hydrogen ions at the first depth position Z1. Therefore, by making the hydrogen donor concentration sufficiently higher than the bulk donor concentration, even if there is a deviation in the bulk donor concentration, the deviation of the donor concentration in the high-concentration region 150 can be reduced. The donor concentration in the high-concentration region 150 can be the bulk donor concentration D. b More than twice that of the donor concentration D b More than 5 times the concentration of donor D can also be used for body donor concentration. b More than 10 times.

[0107] Figure 3 The lattice defect density D of the comparative example is shown. V Hydrogen chemical concentration C H Doping concentration D d and the chemical concentration of impurities C I The distribution of each. In the comparative example, after hydrogen ions are injected into the first depth position Z1 and each of the third depth positions Z3, the semiconductor substrate 10 is annealed to diffuse the hydrogen injected into the first depth position Z1.

[0108] The lattice defect density D in this example V At the start of the annealing process that allows hydrogen ion diffusion, defect density peaks 213 are present at each of the third depth positions Z3. That is, more than one defect density peak 213 is present between the first depth position Z1 and the second depth position Z2. Therefore, the diffusion of hydrogen injected into the first depth position Z1 is hindered by the defect density peaks 213. For example, hydrogen may bind to lattice defects, or the presence of lattice defects may impede the movement of hydrogen.

[0109] Therefore, in Figure 3 In this example, hydrogen did not diffuse sufficiently to the second depth position Z2. In this case, the high-concentration region 150 did not form to the second depth position Z2, leaving behind a low-concentration region 181 with low donor concentration. The donor concentration of the low-concentration region 181 can be compared with the bulk donor concentration D. b The concentrations are similar. Furthermore, even with a large number of lattice defects remaining in the low-concentration region 181, the carrier concentration in the low-concentration region 181 is higher than the bulk donor concentration D. b In the low-concentration region 181, since almost no hydrogen donors are formed, the influence of the bulk donor concentration on the donor concentration becomes greater. Therefore, the deviation in donor concentration in the low-concentration region 181 becomes larger. Furthermore, since valley-like portions are formed in the doping concentration distribution, this sometimes affects the characteristics of the semiconductor device 100. In contrast, according to... Figure 2The semiconductor device 100 shown can form a wide high-concentration region 150, so it can suppress deviations in doping concentration. In addition, the characteristics of the semiconductor device 100 can be adjusted with good precision.

[0110] It should be noted that in buffer zone 20, the hydrogen chemical concentration peak 131-4 closest to the upper surface 21 is also considered to be of high concentration. This makes it easier for hydrogen to diffuse to positions close to the upper surface 21. However, if the hydrogen chemical concentration peak 131-4 close to the upper surface 21 is set to a high concentration, the depletion layer may sometimes reach a high doping concentration peak 111-4 under a relatively high emitter-collector voltage, leading to a decrease in avalanche tolerance. According to... Figure 2 In the example shown, a high concentration doping peak 111-1 can be positioned near the lower surface 23 to suppress the decrease in avalanche tolerance, and a high concentration region 150 can be formed near the upper surface 21. The distance between the first depth position Z1 and the lower surface 23 can be less than 5 μm or less than 3 μm.

[0111] Figure 4 This shows the hydrogen chemical concentration C near buffer zone 20. H and doping concentration D d The distribution diagram is shown. In this example, the peak concentration of doping concentration peak 111-1 is designated as A, the peak concentration of doping concentration peak 111-2 as B2, the peak concentration of doping concentration peak 111-3 as B3, and the peak concentration of doping concentration peak 111-4 as B4. Furthermore, the peak concentration of hydrogen chemical concentration peak 131-1 is designated as H1-1, the peak concentration of hydrogen chemical concentration peak 131-2 as H1-2, the peak concentration of hydrogen chemical concentration peak 131-3 as H1-3, and the peak concentration of hydrogen chemical concentration peak 131-4 as H1-4.

[0112] The ratio A / B of the peak concentration A of doped peak 111-1 and the average peak concentration B of other doped peak 111 (in this example, (B2+B3+B4) / 3) is less than 200. Alternatively, the average peak concentration B can be set to... In the semiconductor device 100, hydrogen injected into the first depth position Z1 readily diffuses towards the upper surface 21. Therefore, even with a reduced peak concentration A, a high-concentration region 150 can be formed over a long range. Furthermore, by reducing the peak concentration A, back-side avalanche when the depletion layer from the upper surface 21 reaches the doping concentration peak 111-1 can be suppressed. The ratio A / B can be 100 or less, 30 or less, 20 or less, 10 or less, 8 or less, or 5 or less. However, if the peak concentration A of the doping concentration peak 111-1 is too low, hydrogen may not diffuse sufficiently. The ratio A / B can be 2 or more, 3 or more, 5 or more, or 10 or more. The peak concentration A can be 1 × 10⁻⁶.16 / cm 3 The following can be 5×10 15 / cm 3 The following can also be 1×10 15 / cm 3 the following.

[0113] Furthermore, the ratio (H1-1) / HA of the peak concentration H1-1 of hydrogen chemical concentration peak 131-1 and the average peak concentration HA of other hydrogen chemical concentration peaks 131 (in this example, [(H1-2)+(H1-3)+(H1-4)] / 3) can also be less than 200. The ratio (H1-1) / HA can be less than 100, less than 30, less than 20, less than 10, less than 8, or less than 5. The ratio (H1-1) / HA can be greater than 2, greater than 3, greater than 5, or greater than 10.

[0114] In addition, the dose (ions / cm) of hydrogen ions at the first depth position Z1 will be... 2 Let C be the dose of hydrogen ions directed to each third depth position Z3, and let D be the total dose of hydrogen ions directed to each Z3. Dose C corresponds to the doping concentration peak 111-1, and dose D corresponds to the doses of other doping concentration peaks 111. The doses corresponding to each doping concentration peak 111 can be used to adjust the hydrogen chemistry concentration C over the full width at half maximum (FWHM) of each doping concentration peak 111. H The value obtained by integration.

[0115] The ratio of dose C to total dose D, C / D, can be 6 or higher and 100 or lower. This ensures a high concentration zone length of 150 and easily suppresses back avalanches. The ratio C / D can also be 10 or higher. Alternatively, the ratio C / D can be 30 or lower.

[0116] Figure 5A This is a flowchart illustrating an example of a method for manufacturing a semiconductor device 100. First, in the upper surface-side structure formation step S500, a structure is formed on the upper surface 21 side of the semiconductor substrate 10. The structure on the upper surface 21 side includes at least a portion of the gate trench, dummy trench, emitter region, base region, accumulation region, interlayer insulating film, emitter electrode, and gate wiring, which will be described later. All of these structures may also be formed in the upper surface-side structure formation step S500.

[0117] Next, in the polishing step S502, the thickness of the semiconductor substrate 10 is adjusted by polishing the lower surface 23 side of the semiconductor substrate 10. In the polishing step S502, the thickness of the semiconductor substrate 10 can be adjusted according to the voltage withstand capability that the semiconductor device 100 should have.

[0118] Next, in the step S504 of forming the lower surface region, a lower surface region 201 is formed in the region that contacts the lower surface 23 of the semiconductor substrate 10. In the step S504 of forming the lower surface region, the lower surface region 201 can be formed by implanting an N-type dopant or a P-type dopant from the lower surface 23 and by performing local annealing on the vicinity of the lower surface 23 using a laser or the like.

[0119] Next, in the first implantation step S505, charged particles and hydrogen ions are implanted into the semiconductor substrate 10. The first implantation step S505 includes a charged particle implantation step S506 and a hydrogen implantation step S508. In the charged particle implantation step S506, charged particles are implanted from the lower surface 23 of the semiconductor substrate 10 to a second depth position Z2. The second depth position Z2 is a position closer to the upper surface 21 than the first depth position Z1. The charged particles can be hydrogen ions, helium ions, or electron beams. Furthermore, in the hydrogen implantation step S508, hydrogen ions are implanted from the lower surface 23 of the semiconductor substrate 10 to the first depth position Z1. In the hydrogen implantation step S508, hydrogen ions can be implanted into the first depth position Z1 in such a way that the hydrogen chemical concentration distribution in the region between the second depth position Z2 and the first depth position Z1 has a separate peak. It should be noted that when hydrogen ions are implanted into the second depth position Z2, a peak in the hydrogen chemical concentration may exist at the second depth position Z2. Either the charged particle injection step S506 or the hydrogen injection step S508 can be performed first.

[0120] Next, in the first annealing step S510, the semiconductor substrate 10 is annealed. The first implantation step S505 and the first annealing step S510 are... Figure 1 This corresponds to the first step S1001. In the first annealing step S510, the semiconductor substrate 10 is placed in an annealing furnace, and the entire semiconductor substrate 10 is annealed. Through the first annealing step S510, a high-concentration region 150 is formed between the first depth position Z1 and the second depth position Z2. The first annealing step S510 is preferably performed under conditions where the hydrogen injected into the first depth position Z1 can diffuse to the second depth position Z2. For example, the annealing temperature of the annealing step S510 is 350°C or higher and 400°C or lower. The annealing temperature can be 360°C or higher or 380°C or lower. The annealing time in the first annealing step S510 can be 30 minutes or more, 1 hour or more, or 3 hours or more. The annealing time can be 10 hours or less or 7 hours or less.

[0121] Next, in the second implantation step S512, N-type dopants such as hydrogen are implanted into the third depth position Z3. For example, in... Figure 2As described in the above, the third depth position Z3 can be arranged at more than one position in the depth direction. The first depth position Z1 and each third depth position Z3 can be arranged on the lower surface 23 side of the semiconductor substrate 10. The second depth position Z2 can be arranged on the upper surface 21 side of the semiconductor substrate 10.

[0122] Next, in the second annealing step S514, the semiconductor substrate 10 is annealed. The second implantation step S512 and the second annealing step S514 correspond to the second step S1002 in Figure 1 In the second annealing step S514, the semiconductor substrate 10 can be put into an annealing furnace and the entire semiconductor substrate 10 is annealed. Through the second annealing step S514, the N-type dopants implanted at the third depth position Z3 are activated, thereby forming more than one doping concentration peak 111. The annealing conditions in the second annealing step S514 are the same as those in the first annealing step S510. That is, the annealing temperature in the second annealing step S514 can be 350 °C or higher and 400 °C or lower. The annealing temperature can be 360 °C or higher, or can be 380 °C or lower. The annealing time in the second annealing step S514 can be 30 minutes or longer, can be 1 hour or longer, or can be 3 hours or longer. The annealing time can be 10 hours or shorter, or can be 7 hours or shorter.

[0123] The difference between the annealing temperature T2 in the second annealing step S514 and the annealing temperature T1 in the first annealing step S510 can be 10 °C or lower. The difference in annealing temperature can be 5 °C or lower, or can be 0. The annealing temperatures T1 and T2 can be T1 = T2, can be T2 < T1, or can be T2 > T1 under the condition that the difference in annealing temperature satisfies the above content. In this example, T1 = T2. In addition, the difference between the annealing time in the second annealing step S514 and the annealing time in the first annealing step S510 can be 10% or less of the annealing time of the larger one, can be 5% or less of the annealing time of the larger one, or can be 0. By setting the second annealing step S514 to have the same annealing conditions as the first annealing step S510, the disappearance of the hydrogen donors formed in the first annealing step S510 can be suppressed.

[0124] In the lower surface side electrode forming step S520, a metal electrode is formed on the lower surface 23 of the semiconductor substrate 10. This metal electrode can be a collector electrode described later. In addition, a lifetime control body forming step S516 and a third annealing step S518 can be included between the second annealing step S514 and the lower surface side electrode forming step S520.

[0125] In the lifetime control body formation step S516, lattice defects are locally formed by injecting impurities such as helium into the semiconductor substrate 10. These impurities can be injected onto the upper surface 21 side or the lower surface 23 side of the semiconductor substrate 10. These impurities can be injected into the diode section (described later). These impurities can also be injected into the transistor section (described later). In the third annealing step S518, the density of lattice defects is adjusted by annealing the semiconductor substrate 10. The annealing temperature T3 in the third annealing step S518 can be lower than or equal to the annealing temperature T1 in the first annealing step S510. Alternatively, the annealing temperature T3 in the third annealing step S518 can be lower than or equal to the annealing temperature T2 in the second annealing step S510.

[0126] Figure 5B This is a flowchart illustrating another example of a method for manufacturing a semiconductor device 100. (Compared to...) Figure 5A In the example shown, the manufacturing method reverses the order of the charged particle implantation step S506 and the hydrogen implantation step S508. That is, in this example, the charged particle implantation step S506 is performed after the hydrogen implantation step S508. After the charged particle implantation step S506, the first annealing step S510 is performed. Other steps can be performed in conjunction with... Figure 5A The example shown is the same. Based on this example, it is also possible to form a longer high-concentration region 150 in the depth direction.

[0127] Figure 6A This is a flowchart illustrating another example of a method for manufacturing a semiconductor device 100. The second implantation step S512 of this example's manufacturing method is... Figure 5A The example shown is different. Other processes can be compared with... Figure 5A The example shown is the same.

[0128] In the second injection step S512 of this example, hydrogen ions are injected into the first depth position Z1 in addition to the third depth position Z3. That is, hydrogen ions are injected into the first depth position Z1 through the first injection step S505 and the second injection step S512.

[0129] By injecting hydrogen ions into the third depth position Z3, lattice defects are formed at a high density near the third depth position Z3. In the second annealing step S514, the hydrogen injected into the third depth position Z3 diffuses and combines with these lattice defects. However, because the amount of hydrogen injected into the third depth position Z3 is relatively low, sometimes a large number of lattice defects remain. To address this, by also injecting hydrogen ions into the first depth position Z1 in the second injection step S512, the hydrogen injected into the first depth position Z1 combines with the lattice defects near the third depth position Z3, thereby reducing the lattice defect density.

[0130] Figure 6BThis is a flowchart illustrating another example of a method for manufacturing a semiconductor device 100. (Compared to...) Figure 6A In the example shown, the manufacturing method reverses the order of the charged particle implantation step S506 and the hydrogen implantation step S508. That is, in this example, the charged particle implantation step S506 is performed after the hydrogen implantation step S508. After the charged particle implantation step S506, the first annealing step S510 is performed. Other steps can be performed in conjunction with... Figure 6A The example shown is the same. Based on this example, it is also possible to form a longer high-concentration region 150 in the depth direction.

[0131] Figure 7 This shows the hydrogen chemical concentration C near buffer zone 20. H The distribution of examples is shown in the figure. Figure 7 hydrogen chemical concentration C H The distribution is the distribution after the second annealing step S514. Let C be the hydrogen chemical concentration based on the hydrogen injected through the first injection step S505. H0 The hydrogen diffuses to the upper surface 21 side through the first annealing step S510. The hydrogen chemical concentration C after the first annealing step S510 is... H0 The peak value is set to H1-0.

[0132] Next, in the second implantation step S512, hydrogen ions are implanted into the first depth position Z1 and each of the third depth positions Z3. At the third depth position Z3, an N-type dopant such as phosphorus can also be implanted instead of hydrogen ions. Through the second annealing step S514, the additional hydrogen implanted into the first depth position Z1 diffuses into the vicinity of each of the third depth positions Z3. This reduces the lattice defect density near each of the third depth positions Z3. The hydrogen chemical concentration C after the second annealing step S514 is... H The peak value is set to H1-1.

[0133] It should be noted that N-type dopants such as phosphorus can be injected into buffer 20. Figure 7 In the diagram, the phosphorus chemical concentration C is indicated by a single-dot dashed line. P Distribution example. Phosphorus chemical concentration C P A chemical concentration peak 171 may exist between the lower surface 23 and the depth position Z1. The concentration of peak 171 may be greater or less than the peak value H1-1. The concentration of peak 171 may be greater or less than the peak value H1-0.

[0134] The peak value H1-0 can be larger than any of the hydrogen chemical concentration peaks 131-2, 131-3, and 131-4. By increasing the concentration of hydrogen ions injected in the first injection step S505, hydrogen can diffuse to deeper locations. The dose of hydrogen ions injected into the first depth position Z1 in the first injection step S505 can be greater than the total dose of hydrogen ions injected into each of the third depth positions Z3 in the second injection step S512.

[0135] The difference between peak value H1-1 and peak value H1-0 can be smaller than peak value H1-0. That is, the second dose of hydrogen ions implanted into the first depth position Z1 in the second implantation step S512 can be lower than the first dose of hydrogen ions implanted into the first depth position Z1 in the first implantation step S505. In the second implantation step S512, since it is only necessary to seal the lattice defects near the third depth position Z3, the dose of hydrogen ions can be small. The second dose can be less than half of the first dose. The first dose can be 1×10⁻⁶. 14 ions / cm 2 That's all. The first dose can be 2×10. 14 ions / cm 2 The above can also be 5×10 14 ions / cm 2 That's all. The second dose can be 5 × 10. 13 ions / cm 2 The above can also be 1×10 14 ions / cm 2 above.

[0136] Figure 8 This shows the doping concentration D near buffer 20 under the condition of dose variation of hydrogen ions for the first depth position Z1. d The graph shows the changes. In this example, during the second injection step S512, no hydrogen ions are injected into the first depth position Z1. Furthermore, the dosage of hydrogen ions for each of the third depth positions Z3 remains unchanged.

[0137] Doping concentration D d1 The dose of hydrogen ions at the first depth position Z1 is 1×10⁻⁶. 14 / cm 2 The doping concentration under the given conditions. Doping concentration D d2 The dose of hydrogen ions at the first depth position Z1 is 3 × 10⁻⁶. 13 / cm 2 The doping concentration under the given conditions. Doping concentration D d3 The dose of hydrogen ions at the first depth position Z1 is 1×10⁻⁶. 13 / cm 2The doping concentration is as follows. It should be noted that the hydrogen ion dose at the third depth position Z3, which is closest to the first depth position Z1, is 1 × 10⁻⁶. 13 / cm 2 .

[0138] Regardless of the dose, the doping concentration distribution on the upper surface 21 side of doping concentration peak 111-2 does not change significantly. In contrast, the doping concentration between doping concentration peaks 111-1 and 111-2 varies considerably depending on the dose applied to the first depth position Z1. It should be noted that even when the dose applied to the first depth position Z1 is 1×10... 14 / cm 2 The doping concentration is also large, and the doping concentration between doping concentration peak 111-1 and doping concentration peak 111-2 is almost unchanged.

[0139] Therefore, it can be assumed that if the dose for the first depth position Z1 is small, the lattice defects between the doping concentration peaks 111-1 and 111-2 are not sufficiently combined with hydrogen. The hydrogen ion dose for the first depth position Z1 can be 3 × 10⁻⁶. 13 / cm 2 The above can also be 1×10 14 / cm 2 The dosage of hydrogen ions at the first depth position Z1 can be more than three times the dosage of hydrogen ions at the third depth position Z3, which is closest to the first depth position Z1, or more than ten times the dosage of hydrogen ions at the third depth position Z3, which is closest to the first depth position Z1. Furthermore, the doping concentration of doping concentration peak 111-1 can be more than three times the doping concentration of doping concentration peak 111-2, or more than ten times the doping concentration of doping concentration peak 111-2.

[0140] Figure 9A This is a graph illustrating the relationship between the hydrogen chemical concentration peak 131-1 and the doping concentration peak 111-1. In this example, the slope 114 of the lower tail 112 of the doping concentration peak 111-1 is normalized using the slope 134 of the lower tail 132 of the hydrogen chemical concentration peak 131-1. Normalization, as an example, involves dividing the slope 114 by the slope 134.

[0141] The slope of the lower tail can be the slope between the location where the concentration shows a maximum value and the location where the concentration is at a predetermined ratio relative to the maximum value. The predetermined ratio can be 80%, 50%, 10%, 1%, or other ratios. Furthermore, for the hydrogen chemical concentration peak 131-1 and the doping concentration peak 111-1, the slope of the concentration distribution between the first depth location Z1 and the lower surface 23 of the semiconductor substrate 10 can be used.

[0142] exist Figure 9A In the example shown, the slope 134 of the hydrogen chemical concentration peak 131-1 is given by (H1-aH1) / (Z1-Z4), and the slope 114 of the doping concentration peak 111-1 is given by (D1-aD1) / (Z1-Z5). H1 is the hydrogen chemical concentration at the first depth position Z1, D1 is the doping concentration at the first depth position Z1, 'a' is a pre-defined ratio, Z4 is the depth at which the hydrogen concentration tails 132 below the hydrogen chemical concentration peak 131-1 to become aH1, and Z5 is the depth at which the doping concentration tails 112 below the doping concentration peak 111-1 to become aD1. For example, if the slope 114 is normalized using the slope 134, it becomes (D1-aD1)(Z1-Z4) / [(H1-aH1)(Z1-Z5)]. The slope obtained by normalizing the slope 114 using the slope 134 is set as α.

[0143] Figure 9B This is a graph illustrating the relationship between the impurity chemical concentration peak 141 and the doping concentration peak 121. In this example, hydrogen ions are implanted as charged particles at the second depth position Z2. In this example, the slope 144 of the lower tail 142 of the impurity chemical concentration peak 141 is normalized to the slope 124 of the lower tail of the doping concentration peak 121.

[0144] exist Figure 9B In the example shown, the slope 144 of the impurity chemical concentration peak 141 is given by (H2-aH2) / (Z2-Z6), and the slope 124 of the doping concentration peak 121 is given by (D2-aD2) / (Z2-Z7). H2 is the hydrogen chemical concentration at the second depth position Z2, D2 is the doping concentration at the second depth position Z2, a is a pre-defined ratio, Z6 is the depth at which the hydrogen chemical concentration tails 142 below the impurity chemical concentration peak 141 to become aH2, and Z7 is the depth at which the doping concentration tails 122 below the doping concentration peak 121 to become aD2. The ratio a used to normalize the slope of the doping concentration peak 121 can be the same as or different from the ratio a used to normalize the slope of the doping concentration peak 111-1. For example, if the slope 124 is normalized using the slope 144, it becomes (D2-aD2)(Z2-Z6) / [(Z2-Z7)(H2-aH2)]. Let β be the slope obtained by standardizing slope 124 using slope 144.

[0145] The normalized slope β of the lower tail 122 of the doping concentration peak 121 is smaller than the normalized slope α of the lower tail 112 of the doping concentration peak 111-1. That is, compared with the doping concentration peak 111-1, the doping concentration peak 121 is a flatter peak relative to the hydrogen chemical concentration peak. By implanting hydrogen ions in a manner that forms such a doping concentration peak 121, a high-concentration region 150 with a flat concentration distribution can be formed. Furthermore, by setting the doping concentration peak 121 to a flat shape, the change in doping concentration at the leading edge of the high-concentration region 150 can also be made smoother. The normalized slope β of the lower tail 122 of the doping concentration peak 121 can be less than 1 times the normalized slope α of the lower tail of the doping concentration peak 111-1, less than 0.1 times the normalized slope α of the lower tail of the doping concentration peak 111-1, or less than 0.01 times the normalized slope α of the lower tail of the doping concentration peak 111-1.

[0146] Furthermore, the slope 144 of the lower tail 142 of the impurity chemical concentration peak 141 can be smaller than the slope 145 of the upper tail 143. The chemical concentration distribution of hydrogen injected from the lower surface 23 to a deeper location sometimes results in a gentle tail on the lower surface 23 side. Therefore, by comparing the slope 144 of the lower tail 142 with the slope 145 of the upper tail 143, it can sometimes be determined whether the hydrogen injected to the second depth position Z2 was injected from the lower surface 23 side. The slope 145 is given by (H2-aH2) / (Z8-Z2). The slope 125 is given by (D2-aD2) / (Z9-Z2). Z8 is the depth at which the hydrogen chemical concentration becomes aH2 in the upper tail 143 of the impurity chemical concentration peak 141, and Z9 is the depth at which the doping concentration becomes aD2 in the upper tail 123 of the doping concentration peak 121. It should be noted that in Figure 9B In the peak 121, the slope 124 of the lower tail 122 is greater than the slope 125 of the upper tail 123. However, similar to the impurity chemical concentration peak 141, the slope 124 of the lower tail 122 of the doping concentration peak 121 can also be smaller than the slope 125 of the upper tail 123.

[0147] Figure 9C This is a diagram illustrating the slope of the lower trailing edge 142. The slope of the lower trailing edge 142 can be considered as follows. For example... Figure 9CAs described, at the impurity chemical concentration peak 141, the width (10% full width) between the two positions Z10 and Z11, which will be 10% (0.1 × H2) of the peak concentration H2, is set as FW10%M. The two positions Z10 and Z11 are the two positions closest to the second depth position Z2, sandwiching the second depth position Z2, where the hydrogen chemical concentration is 0.1 × H2. The position on the side of the hydrogen chemical concentration peak 131-1 between the two positions Z10 and Z11 is set as Z10. The slope of the doping concentration at position Z10 is approximately flat. The slope of the hydrogen chemical concentration at position Z10 is more than 100 times the slope of the doping concentration at position Z10. For example, the slope of the hydrogen chemical concentration at position Z10 can be more than 100 times the slope of the doping concentration at position Z10, or more than 1000 times the slope of the doping concentration at position Z10.

[0148] Figure 10A This is another diagram illustrating the normalization of the slope of the lower tail 112. In the normalization of the slope of the lower tail 112, for example, the following index γ is imported. Figure 9A In the previous example, position Z4 and position Z5 were different, but in this example, position Z4 and position Z5 are set to the same position (Z4 = Z5). Position Z4 is a pre-defined position here. Position Z4 is only required to be the hydrogen chemical concentration C. H and doping concentration D d The lower tails 132 and 112 are located on the side of the lower surface 23 below the first depth position Z1. The hydrogen chemical concentration at position Z4 is defined as a × H1, and the doping concentration at position Z4 is defined as b × D1. a is the ratio of the hydrogen chemical concentration at position Z4 to the concentration H1 of the hydrogen chemical concentration peak 131-1 at the first depth position Z1. b is the ratio of the doping concentration at position Z4 to the concentration D1 of the doping concentration peak 111-1 at the first depth position Z1. Here, the ratio of the slopes of the hydrogen chemical concentration and doping concentration in the interval Z4 to Z1, and the slope ratio γ obtained by standardizing this ratio, are introduced. The ratio of the slopes of the hydrogen chemical concentration in the interval Z4 to Z1 is defined as (H1 / aH1) / (Z1-Z4). Similarly, the ratio of the slopes of the donor concentration in the interval Z4 to Z1 is defined as (D1 / bD1) / (Z1-Z4). Then, the slope ratio γ, obtained by standardizing the ratio of the slope of the doping concentration using the ratio of the slope of the hydrogen chemical concentration in the interval Z4 to Z1, is defined as [(D1 / bD1) / (Z1-Z4)] / [(H1 / aH1) / (Z1-Z4)]. By calculating the previous formula, the standardized slope ratio γ becomes the simple ratio a / b.

[0149] Figure 10BThis is another diagram illustrating the normalization of the slope of the lower tail 122. In the normalization of the slope of the lower tail 122, for example, the same index ε as index γ is introduced. Figure 9B In the previous example, position Z6 was different from position Z7, but in this example, position Z6 and position Z7 are set to the same position (Z6 = Z7). Position Z6 is a pre-defined position here. Position Z6 is simply a position where the hydrogen chemical concentration and doping concentration form a lower tail 142, 122 on the side of the lower surface 23 of the second depth position Z2. The hydrogen chemical concentration at position Z6 is set as c × H2, and the doping concentration at position Z6 is set as d × D2. c is the ratio of the hydrogen chemical concentration at position Z6 to the hydrogen chemical concentration H2 at the second depth position Z2. d is the ratio of the doping concentration at position Z6 to the concentration D2 of the doping concentration peak 121 at the second depth position Z2. Here, the ratio of the slopes of the hydrogen chemical concentration and doping concentration in the interval Z6 to Z2, and the slope ratio ε obtained by standardizing the ratio of these slopes are introduced. The ratio of the slopes of the hydrogen chemical concentration in the interval Z6 to Z2 is defined as (H2 / cH2) / (Z2-Z6). Similarly, the ratio of the slopes of the doping concentrations in the interval Z6–Z2 is defined as (D2 / dD2) / (Z2–Z6). Then, the slope ratio ε, obtained by standardizing the ratio of the slopes of the doping concentrations using the ratio of the slopes of the hydrogen chemical concentrations in the interval Z6–Z2, is defined as [(D2 / dD2) / (Z2–Z6)] / [(H2 / cH2) / (Z2–Z6)]. By calculating the previous equation, the standardized slope ratio ε becomes the simple ratio (c / d).

[0150] Regarding the hydrogen chemical concentration peak 131-1 and the doping concentration peak 111-1, the hydrogen chemical concentration distribution and the doping concentration distribution largely exhibit similar shapes. Here, "similar shapes" means that, for example, when the horizontal axis is set to depth and the vertical axis to the common logarithm of concentration, the doping concentration distribution shows a distribution that reflects the hydrogen chemical concentration distribution. That is, within a pre-defined interval Z4 to Z1, by ion implantation of hydrogen ions followed by annealing, the doping concentration distribution becomes a distribution that reflects the hydrogen chemical concentration distribution. As an example, if the H1 of the hydrogen chemical concentration peak 131-1 is 1 × 10⁻⁶... 17 atoms / cm 3 And the hydrogen chemical concentration aH1 at position Z4 is set to 2 × 10 16 atoms / cm 3 Then a becomes 0.2. On the other hand, if the D1 of the doping concentration peak 111-1 is 1×10 16 / cm 3 And the doping concentration bD1 at position Z4 is set to 2×10 15 / cm 3Therefore, b becomes 0.2. Thus, the slope ratio γ obtained by normalization is a / b, which becomes 1. That is, at the first depth position Z1 near the lower surface 23, the slope ratio a of the hydrogen chemical concentration distribution and the slope ratio b of the doping concentration distribution are approximately the same value, which can be described as similar shapes.

[0151] On the other hand, regarding the impurity chemical concentration peak 141 and the doping concentration peak 121, the hydrogen chemical concentration distribution and the doping concentration distribution may not be similar. That is, within the pre-defined interval Z6 to Z2, the doping concentration distribution may not reflect the hydrogen chemical concentration distribution. As an example, if the hydrogen chemical concentration H2 of the impurity chemical concentration peak 141 is 1 × 10⁻⁶... 16 atoms / cm 3 And the hydrogen chemical concentration cH2 at position Z6 is set to 1×10 15 atoms / cm 3 Then c becomes 0.1. On the other hand, if the concentration D2 of doping concentration peak 121 is 3 × 10 14 / cm 3 Furthermore, the doping concentration dD2 at position Z6 is set to 1.5 × 10⁻⁶. 14 / cm 3 Then d becomes 0.5. Therefore, the slope ratio ε obtained by normalization is c / d, so it becomes 0.2. That is, at a second depth position Z2 that is sufficiently deep from the lower surface 23, the slope ratio c of the hydrogen chemical concentration distribution becomes a value that is smaller than the slope ratio d of the doping concentration distribution and is 0.2 times it, which can be said to show a divergence from the similar shape.

[0152] If we compare the standardized slope ratio γ with ε, then when the peak position of the hydrogen chemical concentration distribution is close to the lower surface 23, γ is close to 1, and when the peak position of the hydrogen chemical concentration distribution is sufficiently deep from the lower surface 23, ε becomes a value sufficiently greater than 1. That is, the standardized slope ratio ε can be larger than the standardized slope ratio γ. Furthermore, the slope ratio ε can be greater than 1.1, greater than 1.5, or greater than 2. Alternatively, it can be greater than 10 or greater than 100.

[0153] It should be noted that the actual positions of the hydrogen chemical concentration peak 131-1 and the impurity chemical concentration peak 141 sometimes differ from the actual positions of the doping concentration peaks 111-1 and 121. Therefore, when the positions of the chemical concentration peaks and the doping concentration peaks are inconsistent, the positions of the chemical concentration peaks can be set to either a first depth position Z1 or a second depth position Z2, and the concentration at either the first depth position Z1 or the second depth position Z2 can be appropriately set as the peak position. This allows for calculations based on the above definitions.

[0154] Figures 11 to 19This is a diagram illustrating an example of a method for determining the preferred range of body donor concentration and donor concentration in the high-concentration region 150. In this example, even if the body donor concentration deviates, the body donor concentration and donor concentration are set in such a way that the final donor concentration (doping concentration) in the high-concentration region 150 becomes a relatively stable concentration.

[0155] In this example, the specification value for the body donor concentration is set to N. B0 And set the actual donor concentration as N Bre The specification value for bulk donor concentration refers to the specification value specified by the semiconductor wafer manufacturer. Where the specification value has a range, the median value can be used. The bulk donor concentration is given by N = 1 / qμρ, relative to the resistivity ρ determined by the concentration of bulk donors such as phosphorus. q is the elementary charge, and μ is the electron mobility in the semiconductor substrate 10.

[0156] Set the concentration of hydrogen donors (VOH defects) to N. H Hydrogen donor concentration N H The deviation is negligible compared to the deviation in bulk donor concentration. In this example, the hydrogen donor concentration N... H The deviation is set to 0.

[0157] Set the target value for the final donor concentration to N. F0 Furthermore, the actual final donor concentration is set as N. Fre The concentrations mentioned above are all concentrations per unit volume ( / cm³). 3 ).

[0158] The target value N of the final donor concentration F0 The specification value N of the donor concentration. B0 With hydrogen donor concentration N H The value obtained by adding them together is therefore given by the following formula.

[0159] N F0 =N H +N B0 …Formula (1)

[0160] On the other hand, the actual donor concentration N Fre The actual donor concentration N Bre With hydrogen donor concentration N H The value obtained by adding them together is therefore given by the following formula.

[0161] N Fre =N H +N Bre …Formula (2)

[0162] The parameter β is defined using the following formula.

[0163] β=NBre / N B0 …Formula (3)

[0164] The parameter β is the actual bulk donor concentration N. Bre With specification value N B0 The ratio, and the further away from 1, the greater the actual donor concentration N. Bre The greater the deviation from the specification value N B0 .

[0165] The parameter γ is defined using the following formula.

[0166] γ=N Fre / N F0 …Formula (4)

[0167] The parameter γ is the actual donor concentration N. Fre With the target value N F0 The ratio, and the further away from 1, the greater the actual donor concentration N. Fre The greater the deviation from the target value N F0 That is, if γ is sufficiently close to 1, it means that even at the actual bulk donor concentration N... Bre Relative to specification value N B0 When deviating from β times, the actual donor concentration N Fre It also depends almost entirely on β, and on the objective value N. F0 They are largely the same.

[0168] Here, the resistivity deviation of silicon wafers manufactured using the FZ method, which has a relatively small deviation in bulk donor concentration, is typically as follows.

[0169] • Neutron radiation FZ wafers…±8% (ratio from 0.92 to 1.08)

[0170] • Vapor-doped FZ wafers…±12% (ratio from 0.88 to 1.12)

[0171] Therefore, if γ is above 0.85 and below 1.15, then the final donor concentration N Fre The deviation is to the same extent as the bulk donor concentration of the silicon wafer produced by the FZ method described above. In this specification, the allowable value of γ is set to be 0.85 or higher and 1.15 or lower.

[0172] Actual donor concentration N Fre Subject to the actual body donor concentration N Bre The effect of the bias (β). On the other hand, the hydrogen donor concentration N H If the deviation is related to the donor concentration N Bre Compared to the deviation, it can be considered approximately 0. Therefore, by considering the target value N of the donor concentration... F0 Reduce the specification value N of the body donor concentration B0Thus, it is possible to achieve a donor concentration N Fre Reduce the proportion of deviation components.

[0173] The parameter ε' is defined using the following formula.

[0174] N B0 =ε'×N F0 …Formula (5)

[0175] Where 0 < ε' < 1. Parameter ε' is the specification value N of the bulk donor concentration. B0 relative to the target value N of the donor concentration F0 The value is set to a parameter that is as small as ε'.

[0176] We explore how much smaller than 1 ε' is set within a range that is not zero, so that γ will be independent of β and sufficiently close to 1.

[0177] The parameter ε is defined using the following formula.

[0178] ε=1 / ε'…Equation (6)

[0179] The following equation can be obtained from equations (5) and (6).

[0180] N B0 =N F0 / ε…equation (7)

[0181] Substituting equation (7) into equation (1), we get the following equation.

[0182] N F0 =N H +N F0 / ε, that is, N H =(1-1 / ε)N F0 …Formula (8)

[0183] Substituting equations (8) and (3) into equation (2), we obtain the following equation.

[0184] N Fre =(1-1 / ε)N F0 +βN B0 …Formula (9)

[0185] Substituting equation (7) into equation (9), we obtain the following equation.

[0186] N Fre =(1-1 / ε)N F0 +(β / ε)N F0

[0187] = (1 - 1 / ε + β / ε)N F0 …Formula (10)

[0188] Substituting equation (10) into equation (4), we get the following equation.

[0189] γ=1-1 / ε+β / ε

[0190] =1+(β-1) / ε…Equation (11)

[0191] The following equation can be obtained from equations (6) and (11).

[0192] γ=1+ε'(β-1)…Equation (12)

[0193] Figure 11 This is a graph showing the relationship between ε' and γ as shown in Equation (12) for each β. As mentioned above, γ represents the actual donor concentration N. Fre Relative to the target value N F0 The ratio, β represents the actual body donor concentration N. Bre Relative to specification value N B0 The ratio. Furthermore, the permissible value for γ is above 0.85 and below 1.15.

[0194] For example, the specification value N of the body donor concentration. B0 Let N be the target value of the donor concentration. F0 Less than 0.5 times, that is, ε' is set to less than 0.5. In this case, for example, even when β is 1.3, γ is less than 1.15, which is within the allowable range. That is, even at the actual bulk donor concentration N Bre Specification value N B0 At a 30% increase, the actual donor concentration N Fre It also becomes the target value N F0 Below 1.15 times. Furthermore, even with β = 0.7, γ is within the acceptable range as long as ε' is below 0.5. If ε' is made close to 0, γ converges to 1. For example, with β = 2, γ is within the acceptable range as long as ε' is approximately below 0.2.

[0195] In order to keep γ within the above-mentioned allowable range, the following ranges A to D can be considered as preferred ranges for ε'.

[0196] (Scope A)

[0197] ε' is between 0.001 and 0.5. When ε' is 0.5, γ is within the allowable range if β is in the range of 0.7 to 1.3. For example, the specification value N for the in vivo donor concentration. B0 1×10 14 / cm 3 When ε' is 0.001, the target value N of the donor concentration is... F0 1×10 11 / cm3 This is equivalent to approximately 46,000 Ωcm.

[0198] (Scope B)

[0199] ε' is between 0.01 and 0.333. When ε' is 0.333, γ is within the allowable range if β is in the range of 0.5 to 1.5. For example, the specification value N for the bulk donor concentration. B0 1×10 14 / cm 3 When ε' is 0.01, the target value N of the donor concentration is... F0 1×10 12 / cm 3 This is equivalent to approximately 4600 Ωcm.

[0200] (Scope C)

[0201] ε' is 0.03 or higher and 0.25 or lower. When ε' is 0.25, γ is within the acceptable range if β is approximately in the range of 0.4 to 1.6. For example, the specification value N for the in vivo donor concentration. B0 1×10 14 / cm 3 When ε' is 0.03, the target value N of the donor concentration is... F0 3×10 12 / cm 3 This is equivalent to approximately 1500 Ωcm.

[0202] (Range D)

[0203] ε' is between 0.1 and 0.2. When ε' is 0.2, γ is within the acceptable range if β is approximately in the range of 0.2 to 1.8. For example, the specification value N for the in vivo donor concentration. B0 1×10 14 / cm 3 When ε' is 0.1, the target value N of the donor concentration is... F0 1×10 13 / cm 3 This is equivalent to approximately 460 Ωcm.

[0204] It should be noted that the smaller the deviation in resistivity, the more suitable it is for practical use; therefore, ε' is preferably 0.1 or less, and more preferably 0.02 or less. In this case, the range E to H, for example, can be considered.

[0205] (Range E)

[0206] ε' is greater than or equal to 0.001 and less than or equal to 0.1. When ε' is 0.1, γ is well within the acceptable range if β is approximately in the range of 0.05 (not shown) to 3.0. For example, the specification value N for the bulk donor concentration... B0 1×10 14 / cm 3 When ε' is 0.1, the target value N of the donor concentration is... F0 1×10 13 / cm 3 This is equivalent to approximately 460 Ωcm.

[0207] (Range F)

[0208] ε' is greater than or equal to 0.002 and less than or equal to 0.05. When ε' is 0.05, γ is well within the acceptable range if β is approximately in the range of 0.01 (not shown) to 5.0. For example, the specification value N for the bulk donor concentration... B0 1×10 14 / cm 3 When ε' is 0.05, the target value N of the donor concentration is... F0 5×10 12 / cm 3 This is equivalent to approximately 920 Ωcm.

[0209] (Range G)

[0210] ε' is greater than or equal to 0.005 and less than or equal to 0.02. When ε' is 0.02, γ is well within the acceptable range if β is approximately in the range of 0.01 (not shown) to 10.0. For example, the specification value N for the bulk donor concentration... B0 1×10 14 / cm 3 When ε' is 0.02, the target value N of the donor concentration is... F0 2×10 12 / cm 3 This is equivalent to approximately 2300 Ωcm.

[0211] (Range H)

[0212] The case where ε' has a range of 0.01 ± 0.002 (20%). With ε' at 0.01, γ is sufficiently within the allowable range if β is approximately in the range of 0.01 (not shown) to 20.0 (not shown). For example, the specification value N for the bulk donor concentration. B0 1×10 14 / cm 3 When ε' is 0.01, the target value N of the donor concentration is... F0 1×10 12 / cm3 This is equivalent to approximately 4600 Ωcm.

[0213] As mentioned above, the actual donor concentration N Fre Corresponding to the donor concentration of the high-concentration region 150. Based on the donor concentration of the high-concentration region 150, which occupies a large area in the semiconductor substrate 10, the withstand voltage of the semiconductor device 100 is essentially determined. Therefore, based on the rated voltage of the semiconductor device 100, the donor concentration N of the high-concentration region 150 is determined. Fre The preferred range. Based on the donor concentration N. Fre Determine what can make the donor concentration N Fre Stable body donor concentration N Bre The range.

[0214] Figure 12 This shows the concentration of donor N in vivo. Bre A diagram illustrating an example of a preferred range. In this example, the donor concentration N at the central Zc location in the depth direction of the semiconductor substrate 10 is... Fre ( / cm 3 (9.20245×10) 15 ) / x or more and (9.20245×10 16 Below ) / x. Where x is the rated voltage (V). Donor concentration N Fre ( / cm 3 The value is determined by referring to the doping concentration of the drift region in a typical semiconductor substrate formed using the FZ method, but it can also be determined by referring to the doping concentration of the drift region in a semiconductor substrate formed using the MCZ method. Figure 12 In the diagram, the donor concentration N is shown using dashed lines. Fre ( / cm 3 The upper limit 311 and the lower limit 312 of the preferred range.

[0215] exist Figure 12 In the figure, the bulk donor concentration N in the above-mentioned range A (ε' is 0.001 or higher and 0.5 or lower) is shown by solid lines. Bre The upper limit 313 and lower limit 314 of the preferred range. Organism donor concentration N Bre The upper limit of 313 is the donor concentration N. Fre ( / cm 3 The value is obtained by multiplying the upper limit of 311 of ε' by the upper limit of ε' (0.5). The donor concentration N Bre The lower limit of 314 is the donor concentration N. Fre ( / cm 3 The value is obtained by multiplying the lower limit of 312 (ε') by the lower limit of 0.001. Organism donor concentration N BreThe upper limit 313 and lower limit 314 are as follows. It should be noted that the units for the upper limit 313 and lower limit 314 in each example are ( / cm). 3 As mentioned above, x is the rated voltage (V).

[0216] • Lower limit 314: (9.20245×10 12 ) / x

[0217] • Upper limit 313: (4.60123×10 16 ) / x

[0218] Figure 13 This shows the bulk donor concentration N when ε' is in the range B (above 0.01 and below 0.333). Bre A diagram illustrating an example of the preferred range. It should be noted that the donor concentration N... Fre ( / cm 3 The upper limit 311 and the lower limit 312 of ) are related to Figure 12 The example is the same. Donor concentration N Bre The upper limit of 313 is the donor concentration N. Fre ( / cm 3 The value is obtained by multiplying the upper limit of 311 of ε' by the upper limit of ε' (0.333). Organism donor concentration N Bre The lower limit of 314 is the donor concentration N. Fre ( / cm 3 The value is obtained by multiplying the lower limit of 312 of ε' by the lower limit of ε' (0.01). Organism donor concentration N Bre The upper limit 313 and the lower limit 314 are as follows.

[0219] • Lower limit 314: (9.20245×10 13 ) / x

[0220] • Maximum value 313: (3.06442×10 16 ) / x

[0221] Figure 14 This shows the bulk donor concentration N when ε' is in the range C (above 0.03 and below 0.25). Bre A diagram illustrating an example of the preferred range. It should be noted that the donor concentration N... Fre ( / cm 3 The upper limit 311 and the lower limit 312 of ) are related to Figure 12 The example is the same. Donor concentration N Bre The upper limit of 313 is the donor concentration N. Fre ( / cm 3 The value is obtained by multiplying the upper limit of 311 of ε' by the upper limit of ε' (0.25). Organism donor concentration N Bre The lower limit of 314 is the donor concentration N.Fre ( / cm 3 The value is obtained by multiplying the lower limit of 312 of ε' by the lower limit of ε' (0.03). Organism donor concentration N Bre The upper limit 313 and the lower limit 314 are as follows.

[0222] • Lower limit 314: (2.76074×10 14 ) / x

[0223] • Upper limit 313: (2.30061×10 16 ) / x

[0224] Figure 15 This shows the bulk donor concentration N when ε' is in the range D (above 0.1 and below 0.2). Bre A diagram illustrating an example of the preferred range. It should be noted that the donor concentration N... Fre ( / cm 3 The upper limit 311 and the lower limit 312 of ) are related to Figure 12 The example is the same. Donor concentration N Bre The upper limit of 313 is the donor concentration N. Fre ( / cm 3 The value is obtained by multiplying the upper limit of 311 of ε' by the upper limit of ε' (0.2). The donor concentration N is... Bre The lower limit of 314 is the donor concentration N. Fre ( / cm 3 The value is obtained by multiplying the lower limit of 312 of ε' by the lower limit of ε' (0.1). Organism donor concentration N Bre The upper limit 313 and the lower limit 314 are as follows.

[0225] • Lower limit 314: (9.20245×10 14 ) / x

[0226] • Upper limit 313: (1.84049×10 16 ) / x

[0227] Figure 16 This shows the bulk donor concentration N when ε' is in the range E (above 0.001 and below 0.1). Bre A diagram illustrating an example of the preferred range. It should be noted that the donor concentration N... Fre ( / cm 3 The upper limit 311 and the lower limit 312 of ) are related to Figure 12 The example is the same. Donor concentration N Bre The upper limit of 313 is the donor concentration N. Fre ( / cm 3 The value is obtained by multiplying the upper limit of 311 of ε' by the upper limit of ε' (0.1). The donor concentration N is... Bre The lower limit of 314 is the donor concentration N.Fre ( / cm 3 The value is obtained by multiplying the lower limit of 312 (ε') by the lower limit of 0.001. Organism donor concentration N Bre The upper limit 313 and the lower limit 314 are as follows.

[0228] • Lower limit 314: (9.20245×10 12 ) / x

[0229] • Maximum value 313: (9.20245×10 15 ) / x

[0230] Figure 17 This shows the bulk donor concentration N when ε' is in the range F (above 0.002 and below 0.05). Bre A diagram illustrating an example of the preferred range. It should be noted that the donor concentration N... Fre ( / cm 3 The upper limit 311 and the lower limit 312 of ) are related to Figure 12 The example is the same. Donor concentration N Bre The upper limit of 313 is the donor concentration N. Fre ( / cm 3 The value is obtained by multiplying the upper limit of 311 of ε' by the upper limit of ε' (0.05). Organism donor concentration N Bre The lower limit of 314 is the donor concentration N. Fre ( / cm 3 The value is obtained by multiplying the lower limit of 312 (ε') by the lower limit of 0.002 (ε'). Organism donor concentration N Bre The upper limit 313 and the lower limit 314 are as follows.

[0231] • Lower limit 314: (1.84049×10 13 ) / x

[0232] • Upper limit 313: (4.60123×10 15 ) / x

[0233] Figure 18 This shows the bulk donor concentration N when ε' is in the range G (above 0.005 and below 0.02). Bre A diagram illustrating an example of the preferred range. It should be noted that the donor concentration N... Fre ( / cm 3 The upper limit 311 and the lower limit 312 of ) are related to Figure 12 The example is the same. Donor concentration N Bre The upper limit of 313 is the donor concentration N. Fre ( / cm 3 The value is obtained by multiplying the upper limit of 311 of ε' by the upper limit of ε' (0.02). Organism donor concentration N BreThe lower limit of 314 is the donor concentration N. Fre ( / cm 3 The value is obtained by multiplying the lower limit of 312 (ε') by the lower limit of 0.005. Organism donor concentration N Bre The upper limit 313 and the lower limit 314 are as follows.

[0234] • Lower limit 314: (4.60123×10 13 ) / x

[0235] • Upper limit 313: (1.84049×10 15 ) / x

[0236] Figure 19 This shows the bulk donor concentration N when ε' is in the range H (0.01 ± 0.002). Bre A diagram illustrating an example of the preferred range. It should be noted that the donor concentration N... Fre ( / cm 3 The upper limit 311 and the lower limit 312 of ) are related to Figure 12 The example is the same. Donor concentration N Bre The upper limit of 313 is the donor concentration N. Fre ( / cm 3 The value is obtained by multiplying the upper limit of 311 of ε' by the upper limit of ε' (0.01). Organism donor concentration N Bre The lower limit of 314 is the donor concentration N. Fre ( / cm 3 The value is obtained by multiplying the lower limit of 312 of ε' by the lower limit of ε' (0.01). Organism donor concentration N Bre The upper limit 313 and the lower limit 314 are as follows.

[0237] • Lower limit 314: (9.20245×10 13 ) / x

[0238] • Maximum value 313: (9.20245×10 14 ) / x

[0239] It should be noted that the upper limit 313 and lower limit 314 of each range can have a range of ±20%.

[0240] like Figures 12 to 19 As shown, by adjusting the donor concentration N... Bre Let the concentration be between the upper limit 313 and the lower limit 314 in each example, so that the final donor concentration N can be represented. Fre The γ-suppression of the deviation is within the allowable range. It should be noted that the curve for the lower limit of 314 is sometimes smaller than the intrinsic carrier concentration. Here, the intrinsic carrier concentration is 1.45 × 10⁻⁶ at room temperature (e.g., 300 K). 10 / cm 3If the value of the curve at the lower limit of 314 is smaller than the intrinsic carrier concentration, the lower limit of 314 can be replaced by the intrinsic carrier concentration.

[0241] Figure 20 This is an example of a top view of a semiconductor device 100. Figure 20 The image shows the positions obtained by projecting each component onto the upper surface of the semiconductor substrate 10. Figure 20 The image shows only a portion of the components of the semiconductor device 100, and some components are omitted.

[0242] Semiconductor device 100 is equipped with Figures 1 to 19 The semiconductor substrate 10 described herein has end edges 102 when viewed from above. In this specification, "viewed from above" refers to the view from the top surface of the semiconductor substrate 10. In this example, the semiconductor substrate 10 has two sets of end edges 102 that are opposite each other when viewed from above. Figure 20 In this configuration, the X and Y axes are parallel to one end edge 102. Furthermore, the Z axis is perpendicular to the upper surface of the semiconductor substrate 10.

[0243] An active portion 160 is provided on the semiconductor substrate 10. The active portion 160 is a region where a main current flows along the depth direction between the upper and lower surfaces of the semiconductor substrate 10 when the semiconductor device 100 is activated. An emitter electrode is provided above the active portion 160, but... Figure 20 omitted.

[0244] The active section 160 is provided with at least one of a transistor section 70 including transistor elements such as IGBTs and a diode section 80 including diode elements such as freewheeling diodes (FWDs). Figure 20 In one example, the transistor section 70 and the diode section 80 are alternately arranged along a predetermined alignment direction (the X-axis direction in this example) on the upper surface of the semiconductor substrate 10. In other examples, only one of the transistor section 70 and the diode section 80 may be provided in the active section 160.

[0245] exist Figure 20 In this specification, the area where the transistor section 70 is arranged is marked with the symbol "I", and the area where the diode section 80 is arranged is marked with the symbol "F". In this specification, the direction perpendicular to the arrangement direction when viewed from above is sometimes referred to as the extension direction (in...). Figure 20 (The middle direction is the Y-axis direction). The transistor section 70 and the diode section 80 may each have a long side in the extending direction. That is, the length of the transistor section 70 in the Y-axis direction is greater than its width in the X-axis direction. Similarly, the length of the diode section 80 in the Y-axis direction is greater than its width in the X-axis direction. The extending directions of the transistor section 70 and the diode section 80 may be the same as the long side direction of each trench section described later.

[0246] The diode portion 80 has an N+ type cathode region in the area contacting the lower surface of the semiconductor substrate 10. In this specification, the area where the cathode region is provided is referred to as the diode portion 80. That is, the diode portion 80 is the area that overlaps with the cathode region when viewed from above. A P+ type collector region may be provided on the lower surface of the semiconductor substrate 10 in the area other than the cathode region. In this specification, sometimes an extension region 81, formed by extending the diode portion 80 along the Y-axis direction to the gate wiring described later, is also included in the diode portion 80. A collector region is provided on the lower surface of the extension region 81.

[0247] The transistor section 70 has a P+ type collector region in the region that contacts the lower surface of the semiconductor substrate 10. In addition, the transistor section 70 has an N-type emitter region, a P-type base region, and a gate structure having a gate conductive portion and a gate insulating film periodically arranged on the upper surface side of the semiconductor substrate 10.

[0248] Semiconductor device 100 may have one or more pads above semiconductor substrate 10. In this example, semiconductor device 100 has a gate pad 164. Semiconductor device 100 may also have anode pads, cathode pads, and current sensing pads, etc. Each pad is located near the edge 102. Near the edge 102 refers to the area between the edge 102 and the emitter electrode when viewed from above. When mounting semiconductor device 100, each pad can be connected to external circuitry via wiring such as wires.

[0249] A gate potential is applied to the gate pad 164. The gate pad 164 is electrically connected to the conductive portion of the gate trench portion of the active portion 160. The semiconductor device 100 includes gate wiring connecting the gate pad 164 to the gate trench portion. Figure 20 In the diagram, the gate wiring is marked with a slanted shaded line.

[0250] The gate wiring in this example includes a peripheral gate wiring 130 and an active-side gate wiring 129. The peripheral gate wiring 130 is disposed between the active portion 160 and the edge 102 of the semiconductor substrate 10 when viewed from above. In this example, the peripheral gate wiring 130 surrounds the active portion 160 when viewed from above. Alternatively, the area surrounded by the peripheral gate wiring 130 when viewed from above may also be considered as the active portion 160. Furthermore, 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 including aluminum.

[0251] Active-side gate wiring 129 is provided in the active portion 160. By providing active-side gate wiring 129 in the active portion 160, the deviation of wiring length measured from gate pad 164 in each region of the semiconductor substrate 10 can be reduced.

[0252] The active-side gate wiring 129 is connected to the gate trench portion of the active portion 160. The active-side gate wiring 129 is disposed above the semiconductor substrate 10. The active-side gate wiring 129 may be wiring formed from semiconductors such as polysilicon doped with impurities.

[0253] The active-side gate wiring 129 can be connected to the outer peripheral gate wiring 130. In this example, the active-side gate wiring 129 is configured to extend from one side of the outer peripheral gate wiring 130 to the other side of the outer peripheral gate wiring 130 in a manner that traverses the active portion 160 approximately at the center in the Y-axis direction. When the active portion 160 is divided by the active-side gate wiring 129, the transistor portion 70 and the diode portion 80 can be alternately arranged in the X-axis direction in each divided region.

[0254] In addition, the semiconductor device 100 may also include: a temperature sensing unit (not shown) that is a PN junction diode formed of polysilicon or the like, and / or a current sensing unit (not shown) that simulates the operation of a transistor unit disposed in the active unit 160.

[0255] In this example, the semiconductor device 100 has an edge termination structure 90 between the active portion 160 and the edge 102. The edge termination structure 90 is disposed between the peripheral gate wiring 130 and the edge 102. The edge termination structure 90 mitigates electric field concentration on the upper surface side of the semiconductor substrate 10. The edge termination structure 90 has multiple guard rings 92. Each guard ring 92 is a P-type region that contacts the upper surface of the semiconductor substrate 10. The guard rings 92 can surround the active portion 160 when viewed from above. The multiple guard rings 92 are arranged at predetermined intervals between the peripheral gate wiring 130 and the edge 102. An outer guard ring 92 can surround an inner guard ring 92. The outer side refers to the side closest to the edge 102, and the inner side refers to the side closest to the peripheral gate wiring 130. By providing multiple guard rings 92, the depletion layer on the upper surface side of the active portion 160 can extend outwards, and the breakdown voltage of the semiconductor device 100 can be improved. The edge terminal structure 90 may also include at least one of a field plate that surrounds the active part 160 and is configured in an annular shape, and a surface electric field reduction device.

[0256] Figure 21 yes Figure 20An enlarged view of region A is shown. Region A includes the transistor section 70, the diode section 80, and the active-side gate wiring 129. 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 disposed inside the upper surface side of the semiconductor substrate 10. The gate trench section 40 and the dummy trench section 30 are examples of trench sections. Furthermore, the semiconductor device 100 of this example includes an emitter electrode 52 and an active-side gate wiring 129 disposed above the upper surface of the semiconductor substrate 10. The emitter electrode 52 and the active-side gate wiring 129 are disposed separately from each other.

[0257] An interlayer insulating film is disposed between the emitter electrode 52 and the active-side gate wiring 129 and the upper surface of the semiconductor substrate 10, but in Figure 21 (Omitted). In this example, the interlayer insulating film has contact holes 54 that penetrate through it. Figure 21 In the diagram, each contact hole 54 is marked with a slanted shaded line.

[0258] The emitter electrode 52 is disposed 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. Furthermore, the emitter electrode 52 is connected to a dummy conductive portion within the dummy trench portion 30 through a contact hole disposed in the interlayer insulating film. The emitter electrode 52 can be connected to the dummy conductive portion of the dummy trench portion 30 at its front end in the Y-axis direction.

[0259] The active-side gate wiring 129 is connected to the gate trench portion 40 through a contact hole provided in the interlayer insulating film. The active-side gate wiring 129 can be connected to the gate conductive portion of the gate trench portion 40 at its front end 41 in the Y-axis direction. The active-side gate wiring 129 is not connected to the dummy conductive portion within the dummy trench portion 30.

[0260] The emitting electrode 52 is formed of a material containing metal. Figure 21 The diagram shows the area where the emitter electrode 52 is disposed. For example, at least a portion of the emitter electrode 52 is formed of aluminum or an aluminum-silicon alloy such as AlSi, AlSiCu, or other metal alloys. The emitter electrode 52 may have a barrier metal formed of titanium and / or titanium compounds in a lower layer beneath the region formed of aluminum or the like. Furthermore, a plug formed by embedding tungsten or the like in contact with the barrier metal and the aluminum or the like may be provided within the contact hole.

[0261] Well region 11 is configured to overlap with the active-side gate wiring 129. Well region 11 is also configured to extend with a predetermined width in areas where it does not overlap with the active-side gate wiring 129. In this example, well region 11 is configured as an end in the Y-axis direction away from the contact hole 54 towards the active-side gate wiring 129. Well region 11 is a region of a second conductivity type with a higher doping concentration than the base region 14. In this example, base region 14 is P-type, and well region 11 is P+ type.

[0262] The transistor section 70 and the diode section 80 each have a plurality of trench sections arranged along the arrangement direction. In this example, the transistor section 70 has one or more gate trench sections 40 and one or more dummy trench sections 30 alternately arranged along the arrangement direction. In this example, the diode section 80 has a plurality of dummy trench sections 30 arranged along the arrangement direction. In this example, the diode section 80 does not have a gate trench section 40.

[0263] In this example, the gate trench portion 40 may have two straight portions 39 (the portion of the trench that is straight along the extension direction) extending in an extension direction perpendicular to the arrangement direction, and a front end portion 41 connecting the two straight portions 39. Figure 21 The extension direction in the middle is the Y-axis direction.

[0264] At least a portion of the front end portion 41 is preferably curved when viewed from above. By connecting the ends of the two straight portions 39 in the Y-axis direction to each other through the front end portion 41, it is possible to mitigate the electric field concentration at the ends of the straight portions 39.

[0265] In the transistor section 70, dummy trench sections 30 are provided between each straight section 39 of the gate trench section 40. One dummy trench section 30 may be provided between each straight section 39, or multiple dummy trench sections 30 may be provided. The dummy trench section 30 may have a straight shape extending in the extending direction, or it may, like the gate trench section 40, have a straight section 29 and a front end portion 31. Figure 21 The semiconductor device 100 shown includes both a dummy trench portion 30 with a straight shape and no front end portion 31, and a dummy trench portion 30 with a front end portion 31.

[0266] The diffusion depth of the well region 11 can 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 located within the well region 11 when viewed from above. That is, 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 mitigates the electric field concentration at the bottom of each trench portion.

[0267] In the arrangement direction, mesa-shaped portions are provided between each trench portion. A mesa-shaped portion refers to the area within the semiconductor substrate 10 that is sandwiched between trench portions. For example, the upper end of the mesa-shaped portion is the upper surface of the semiconductor substrate 10. The lower end of the mesa-shaped portion has the same depth as the lower end of the trench portion. In this example, the mesa-shaped portion is configured to extend along the trench in the extension direction (Y-axis direction) along the upper surface of the semiconductor substrate 10. In this example, a mesa-shaped portion 60 is provided in the transistor portion 70, and a mesa-shaped portion 61 is provided in the diode portion 80. In this specification, when simply referred to as a mesa-shaped portion, it refers to each mesa-shaped portion 60 and mesa-shaped portion 61.

[0268] A base region 14 is provided on each mesa. The region of the base region 14 exposed on the upper surface of the semiconductor substrate 10 within the mesa, configured to be closest to the active-side gate wiring 129, is designated as base region 14-e. Figure 21 The diagram shows a base region 14-e disposed at one end of each isthmus in the extending direction, but a base region 14-e is also disposed at the other end of each isthmus. In each isthmus, the area enclosed by the base region 14-e when viewed from above can be provided with at least one of a first conductivity type emitter region 12 and a second conductivity type contact region 15. 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 can be disposed between the base region 14 and the upper surface of the semiconductor substrate 10 in the depth direction.

[0269] 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 configured to contact the gate trench portion 40. The mesa portion 60 that contacts the gate trench portion 40 may have a contact region 15 exposed on the upper surface of the semiconductor substrate 10.

[0270] The contact area 15 and the emission area 12 in the platform 60 are respectively configured as a groove portion from one side to the other side in the X-axis direction. As an example, the contact area 15 and the emission area 12 of the platform 60 are alternately arranged along the extension direction of the groove portion (Y-axis direction).

[0271] In another example, the contact area 15 and the emission area 12 of the surface 60 can be configured as stripes along the extension direction (Y-axis direction) of the groove. For example, the emission area 12 is provided in the area that contacts the groove, and the contact area 15 is provided in the area sandwiched by the emission area 12.

[0272] The emitter region 12 is not provided on the mesa 61 of the diode section 80. A base region 14 and a contact region 15 may be provided on the upper surface of the mesa 61. A contact region 15 may be provided on the upper surface of the mesa 61 in the area enclosed by the base regions 14-e, in a manner that contacts each of the base regions 14-e. A base region 14 may be provided on the upper surface of the mesa 61 in the area enclosed by the contact region 15. The base region 14 may be disposed throughout the entire area enclosed by the contact region 15.

[0273] A contact hole 54 is provided above each mesa surface. The contact hole 54 is located in the area enclosed by the base region 14-e. In this example, the contact hole 54 is located above each region of the contact region 15, the base region 14, and the emitter region 12. The contact hole 54 is not located in the region corresponding to the base region 14-e and the sink region 11. The contact hole 54 can be located at the center of the mesa surface 60 in the arrangement direction (X-axis direction).

[0274] In the diode section 80, an N+ type cathode region 82 is provided in the region adjacent to the lower surface of the semiconductor substrate 10. A P+ type collector region 22 can be provided on the lower surface of the semiconductor substrate 10 in the region where the cathode region 82 is not provided. Figure 21 In the image, the boundary between the cathode region 82 and the collector region 22 is shown by a dashed line.

[0275] The cathode region 82 is configured to be located away from the well region 11 in the Y-axis direction. This ensures a sufficient distance between the cathode region 82 and the P-type region (well region 11) with a high doping concentration and formed to a deep depth, thereby improving the breakdown voltage. In this example, the end of the cathode region 82 in the Y-axis direction is configured to be further away 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 also be configured between the well region 11 and the contact hole 54.

[0276] Figure 22A It is shown Figure 21 The diagram shows an example of a cross-section bb. The cross-section bb is the XZ plane passing through the emitter region 12 and the cathode region 82. In this example, the semiconductor device 100 has the following components in this cross-section: a semiconductor substrate 10, an interlayer insulating film 38, an emitter electrode 52, and a collector electrode 24. The interlayer insulating film 38 is disposed on the upper surface of the semiconductor substrate 10. The interlayer insulating film 38 is a film comprising at least one layer of an insulating film such as silicate glass with added impurities such as boron or phosphorus, a thermally oxidized film, or other insulating films. The interlayer insulating film 38 has a... Figure 21 Contact hole 54 as described in the text.

[0277] The emitter electrode 52 is disposed above the interlayer insulating film 38. The emitter electrode 52 contacts the upper surface 21 of the semiconductor substrate 10 through the contact hole 54 of the interlayer insulating film 38. The collector electrode 24 is disposed on the lower surface 23 of the semiconductor substrate 10. The emitter electrode 52 and the collector electrode 24 are formed of a metallic material such as aluminum. In this specification, the direction (Z-axis direction) connecting the emitter electrode 52 and the collector electrode 24 is referred to as the depth direction.

[0278] The semiconductor substrate 10 has an N-type drift region 19. In this example, the drift region 19 is an N-type region extending from the lower end of the accumulation region 16 to the upper end of the buffer zone 20. The drift region 19 in this example has... Figures 1 to 19 The high concentration zone 150 is described in the text. Figure 22A In the diagram, the high-concentration region 150 is marked with a shading line. The high-concentration region 150 can be located in the transistor section 70, the diode section 80, or both. The high-concentration region 150 is the area extending from the upper end of the buffer zone 20 towards the upper surface 21. An impurity chemical concentration peak 141 (see reference) is positioned at the upper portion of the high-concentration region 150. Figure 1 wait).

[0279] The drift region 19 may have an N-type body donor region 18. The body donor region 18 is a region where the doping concentration is the same as the donor concentration of the body donor. The body donor region 18 is a region disposed above the high concentration region 150. In this example, the body donor region 18 is disposed in both the transistor section 70 and the diode section 80.

[0280] On the mesa 60 of the transistor section 70, an N+ type emitter region 12 and a P- type base region 14 are sequentially disposed from the upper surface 21 side of the semiconductor substrate 10. A body donor region 18 is disposed below the base region 14. An N+ type accumulation region 16 may be disposed on the mesa 60. The accumulation region 16 is disposed between the base region 14 and the body donor region 18.

[0281] The emitter region 12 is exposed on the upper surface 21 of the semiconductor substrate 10 and is configured to contact the gate trench 40. The emitter region 12 may contact the trenches on both sides of the mesa 60. The doping concentration of the emitter region 12 is higher than that of the bulk donor region 18.

[0282] The base region 14 is located below the emitter region 12. In this example, the base region 14 is configured to contact the emitter region 12. The base region 14 may contact the groove portions on both sides of the stage surface 60.

[0283] Accumulation region 16 is disposed below base region 14. Accumulation region 16 is an N+ type region with a higher doping concentration than drift region 19. The doping concentration of accumulation region 16 can be higher than that of high-concentration region 150. By providing a high-concentration accumulation region 16 between drift region 19 and base region 14, the carrier injection enhancement effect (IE effect) can be improved, thereby reducing the turn-on voltage. Accumulation region 16 can be configured to cover the entire lower surface of base region 14 in each mesa 60.

[0284] A P-type base region 14 is provided on the mesa 61 of the diode section 80 in such a way that it contacts the upper surface 21 of the semiconductor substrate 10. A bulk donor region 18 is provided below the base region 14. An accumulation region 16 may also be provided below the base region 14 in the mesa 61.

[0285] In both the transistor section 70 and the diode section 80, an N+ type buffer zone 20 is provided on the lower surface 23 side of the high-concentration region 150. The structure of the buffer zone 20 is similar to that in... Figures 1 to 19 The buffer 20 described herein is the same. The buffer 20 can function as a field cutoff layer to prevent 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.

[0286] In the transistor section 70, a P+ type collector region 22 is provided below the buffer 20. The collector region 22 is... Figures 1 to 19 An example of the lower surface region 201 described herein. The acceptor concentration in the collector region 22 is higher than that in the base region 14. The collector region 22 may contain the same acceptors as the base region 14, or it may contain different acceptors than the base region 14. The acceptors in the collector region 22 are, for example, boron.

[0287] In the diode section 80, an N+ type cathode region 82 is provided below the buffer zone 20. The cathode region 82 is... Figures 1 to 19 An example of the lower surface region 201 described herein. The donor concentration in the cathode region 82 is higher than that in the high-concentration region 150. The donors in the cathode region 82 are, for example, hydrogen or phosphorus. It should be noted that the elements that become donors and acceptors in each region are not limited to the examples described above. The collector region 22 and the cathode region 82 are exposed on the lower surface 23 of the semiconductor substrate 10 and are connected to the collector electrode 24. The collector electrode 24 may contact the entire lower surface 23 of the semiconductor substrate 10. The emitter electrode 52 and the collector electrode 24 are formed of a metallic material such as aluminum.

[0288] One or more gate trenches 40 and one or more dummy trenches 30 are provided on the upper surface 21 side of the semiconductor substrate 10. Each trench extends from the upper surface 21 of the semiconductor substrate 10 through the base region 14 to reach the drift region 19. In regions where at least one of the emitter region 12, contact region 15, and accumulation region 16 is provided, each trench also extends through these doped regions to reach the body donor region 18. The trench extending through the doped regions is not limited to the case where the trenches are formed after the doped regions are formed. The case where doped regions are formed between the trenches after the trenches are formed is also included in the case where the trenches extend through the doped regions.

[0289] As described above, the transistor section 70 is provided with a gate trench section 40 and a dummy trench section 30. The diode section 80 is provided with a dummy trench section 30, but not with a 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.

[0290] The gate trench portion 40 has a gate trench disposed 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 configured to cover 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 disposed inside the gate trench at a position further inward 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.

[0291] The gate conductive portion 44 can be configured to be longer than the base region 14 in the depth direction. The gate trench portion 40 at this cross-section is covered by 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. If a predetermined gate voltage is applied to the gate conductive portion 44, a channel formed by an electron inversion layer is formed on the surface layer of the interface in the base region 14 that contacts the gate trench portion 40.

[0292] The dummy trench portion 30 can have the same structure as the gate trench portion 40 in this cross-section. The dummy trench portion 30 has a dummy trench disposed on the upper surface 21 of the semiconductor substrate 10, a dummy insulating film 32, and a dummy conductive portion 34. The dummy conductive portion 34 can be connected to an electrode different from the gate pad. For example, the dummy conductive portion 34 can be connected to a dummy pad (not shown) that is connected to an external circuit, different from the gate pad, and controlled differently from the gate conductive portion 44. Alternatively, the dummy conductive portion 34 can be electrically connected to the emitter electrode 52. The dummy insulating film 32 is disposed to cover the inner wall of the dummy trench. The dummy conductive portion 34 is disposed inside the dummy trench and at a position closer to the inner side 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 can be formed of the same material as the gate conductive portion 44. For example, the dummy conductive portion 34 is formed of a conductive material such as polysilicon. The dummy conductive portion 34 may have the same length as the gate conductive portion 44 in the depth direction.

[0293] In this example, the gate trench portion 40 and the dummy trench portion 30 are covered by an interlayer insulating film 38 on the upper surface 21 of the semiconductor substrate 10. It should be noted that the bottom of the dummy trench portion 30 and the gate trench portion 40 can be a downwardly convex curved surface (curved in cross-section).

[0294] Semiconductor substrate 10 has a common feature with Figures 1 to 19 The same impurity chemical concentration C is described in any example. I Hydrogen chemical concentration C H and doping concentration D d The distribution of doping concentration in the drift region 19 is thus suppressed by providing a high concentration region 150, according to the semiconductor device 100 of this example.

[0295] Figure 22B It is shown Figure 22A The doping concentration D at the dd line d The diagram shows an example of doping concentration D. The dd line is a line parallel to the Z-axis passing through collector region 22 and mesa 60. d The distribution from collector region 22 to doping concentration peak 121 is similar to Figure 2 The doping concentration D shown d The distribution is the same. In this example, the doping concentration D... d Concentration peaks are present in the accumulation region 16, the base region 14, and the emitter region 12. In this example, the semiconductor substrate 10 has a bulk donor region 18 between the accumulation region 16 and the doping concentration peak 121. The bulk donor region 18 can contact the accumulation region 16. That is, at the boundary between the bulk donor region 18 and the accumulation region 16, the doping concentration D... d From the donor concentration D bThe concentration gradually increases to the peak of the accumulation zone 16.

[0296] Figure 23 It is shown Figure 21 Another example of the bb section is shown in the figure. In the semiconductor device 100 of this example, with Figure 22A The difference in this example is that the high-concentration region 150 is set to extend throughout the entire drift region 19. Other structures can be similar. Figure 22A The examples are the same.

[0297] In this example, the high-concentration region 150 can be positioned from the upper end of the buffer zone 20 to the location contacting the accumulation region 16. The high-concentration region 150 can also be formed inside the accumulation region 16. In this case, the doping concentration peak 121 can be located in the accumulation region 16. If the semiconductor device 100 does not have an accumulation region 16, the high-concentration region 150 can be positioned to contact the base region 14. According to this example, deviations in doping concentration can be suppressed throughout the entire drift region 19.

[0298] The present invention has been described above using embodiments, but 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 or improvements can be made to the above embodiments. As can be seen from the claims, such modifications or improvements can also be included within the technical scope of the present invention.

[0299] It should be noted that the execution order of actions, sequences, steps, and stages in the apparatus, systems, programs, and methods shown in the claims, description, and drawings can be arbitrary, as long as it is not specifically stated as "before," "before," etc., and the results of previous processes are not used in subsequent processes. Even if the flow of actions in the claims, description, and drawings is described using terms such as "firstly," "next," etc. for convenience, it does not mean that they must be performed in that order.

Claims

1. A semiconductor device, characterized in that, have: A semiconductor substrate having an upper surface and a lower surface, and containing a volume donor; A buffer of the first conductivity type is disposed on the lower surface side of the semiconductor substrate and has two or more doping concentration peaks in the depth direction of the semiconductor substrate. A high-concentration region of a first conductivity type is disposed between the buffer zone and the upper surface of the semiconductor substrate, and the donor concentration is higher than the bulk donor concentration. as well as A lower surface region of a first conductivity type or a second conductivity type, disposed between the buffer zone and the lower surface of the semiconductor substrate, has a higher doping concentration than the high-concentration region. The shallowest doping concentration peak in the buffer zone that is closest to the lower surface of the semiconductor substrate is the concentration peak of hydrogen donors with a higher concentration than the other doping concentration peaks. The semiconductor device further includes impurity chemical concentration peaks, which are disposed on the upper surface side of the semiconductor substrate. The high concentration region extends from the lightest doping concentration peak to the impurity chemical concentration peak. The high-concentration region includes a homogeneous region with a roughly uniform doping concentration. Regarding the doping concentration distribution in the uniform region, the difference between the maximum and minimum doping concentrations within the first range is within 50% of the maximum doping concentration, or the doping concentration distribution value within the first range is within ±50% of the average concentration of the doping concentration distribution. Let the length in the depth direction of the high-concentration region be Z. L And the center in the depth direction between the shallowest doping concentration peak and the impurity chemical concentration peak is set as Z. 12c In the case where the first range includes the center Z 12c The length is 0.5Z L The range.

2. The semiconductor device according to claim 1, characterized in that, The impurity chemical concentration decreases sharply compared to the upper tail of the impurity chemical concentration peak decreasing from the apex of the peak toward the upper surface side and the lower tail of the peak decreasing from the apex of the peak toward the lower surface side.

3. The semiconductor device according to claim 1, characterized in that, The high-concentration region has a length of more than 50 μm in the depth direction.

4. The semiconductor device according to claim 2, characterized in that, The high-concentration region has a length of more than 50 μm in the depth direction.

5. The semiconductor device according to any one of claims 1 to 4, characterized in that, The ratio of the peak concentration A of the shallowest doping concentration peak to the average peak concentration B of the other doping concentration peaks, A / B, is less than 200.

6. The semiconductor device according to any one of claims 1 to 4, characterized in that, The high-concentration region has a length of more than 80 μm from the shallowest doping concentration peak toward the upper surface of the semiconductor substrate.

7. The semiconductor device according to any one of claims 1 to 4, characterized in that, The high-concentration region has a length that is more than 40% of the thickness of the semiconductor substrate in the depth direction.

8. The semiconductor device according to claim 5, characterized in that, The ratio A / B is 2 or higher.

9. The semiconductor device according to any one of claims 1 to 4, characterized in that, The ratio of the dose C of the shallowest doping concentration peak to the total dose D of the other doping concentration peaks, C / D, is greater than 6 and less than 100.

10. The semiconductor device according to any one of claims 1 to 4, characterized in that, The semiconductor device further includes an accumulation region disposed on the upper surface side of the semiconductor substrate, and the accumulation region has a higher doping concentration than the high-concentration region. The high-concentration zone is positioned in contact with the accumulation zone.

11. The semiconductor device according to claim 1, characterized in that, The minimum doping concentration in the high-concentration region is more than twice the bulk donor concentration.

12. A method for manufacturing a semiconductor device, characterized in that, include: In the first implantation step, hydrogen ions are implanted from the lower surface of a semiconductor substrate having an upper surface and a lower surface and containing a volume donor to a first location, and charged particles are implanted to a second location closer to the upper surface than the first location. The first annealing step involves annealing the semiconductor substrate to form a high-concentration region between the first position and the second position, where the donor concentration is higher than the bulk donor concentration. as well as The second implantation step involves implanting an N-type dopant into one or more third positions between the first and second positions.

13. The method for manufacturing a semiconductor device according to claim 12, characterized in that, The second position is disposed on the upper surface side of the semiconductor substrate, and the third position is disposed on the lower surface side of the semiconductor substrate.

14. The method for manufacturing a semiconductor device according to claim 12, characterized in that, The method for manufacturing the semiconductor device further includes a second annealing step, which anneals the semiconductor substrate after the second implantation step.

15. The method for manufacturing a semiconductor device according to claim 13, characterized in that, The method for manufacturing the semiconductor device further includes a second annealing step, which anneals the semiconductor substrate after the second implantation step.

16. The method for manufacturing a semiconductor device according to claim 14, characterized in that, The annealing temperatures for both the first and second annealing steps are above 350°C and below 400°C.

17. The method for manufacturing a semiconductor device according to claim 15, characterized in that, The annealing temperatures for both the first and second annealing steps are above 350°C and below 400°C.

18. The method for manufacturing a semiconductor device according to claim 16, characterized in that, The difference in annealing temperature between the first annealing step and the second annealing step is less than 10°C.

19. The method for manufacturing a semiconductor device according to claim 17, characterized in that, The difference in annealing temperature between the first annealing step and the second annealing step is less than 10°C.

20. A method for manufacturing a semiconductor device according to any one of claims 12 to 19, characterized in that, In the second injection step, hydrogen ions are injected into the first location.

21. The method for manufacturing a semiconductor device according to claim 20, characterized in that, The second dose of hydrogen ions injected into the first location in the second injection step is lower than the first dose of hydrogen ions injected into the first location in the first injection step.

22. The method for manufacturing a semiconductor device according to claim 21, characterized in that, The first dose is 1×10 14 ions / cm 2 above, The second dose is 3×10 13 ions / cm 2 above.

Images