Semiconductor Device

Abstract

To provide a semiconductor device having an IGBT and a body diode with an improved recovery loss.SOLUTION: A semiconductor device comprises a semiconductor substrate, a gate insulation film, a gate, and a first polysilicon film. The semiconductor substrate includes a first principal surface and a second principal surface, which is an opposite surface of the first principal surface. The semiconductor substrate also includes a first portion an a second portion. In addition, the semiconductor substrate includes a collector region arranged on a second principal surface located in the first portion, a cathode region arranged on a second principal surface located in the second portion, a drift region arranged on the collector region and the cathode region, an emitter region arranged on a first principal surface located in the first portion, a base region arranged between the emitter region and the collector region, and an anode region arranged on a first principal surface located in the second portion.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] The semiconductor device described in JP 2021-093556 A (Patent Document 1) has a reverse conducting insulated gate bipolar transistor (RC-IGBT). The semiconductor device described in Patent Document 1 has a semiconductor substrate, a gate insulating film, and a gate.

[0003] The semiconductor substrate has a first main surface and a second main surface. The second main surface is opposite to the first main surface. The semiconductor substrate has a collector region, a cathode region, a buffer region, a drift region, a collector region, a base region, and a contact region.

[0004] The collector region is disposed on the second main surface. However, a cathode region is disposed partially in place of the collector region. The buffer region is disposed on the collector region and on the cathode region. The drift region is disposed on the buffer region. The collector region is disposed on the first main surface. The base region is disposed between the drift region and the emitter region. The contact region is disposed in the base region. The cathode region, the buffer region, the drift region and the emitter region have an n-type conductivity. The collector region, the base region and the contact region have a p-type conductivity. The dopant concentration in the contact region is higher than the dopant concentration in the base region.

[0005] A gate trench is formed in the first main surface. The gate trench extends from the first main surface toward the second main surface. The emitter region, the base region, and the drift region are exposed from the side surfaces of the gate trench.

[0006] A gate is buried in the gate trench. A gate insulating film is disposed between the side and bottom surfaces of the gate trench and the gate. Therefore, a portion of the base region sandwiched between the emitter region and the drift region faces the gate with the gate insulating film interposed therebetween.

[0007] The emitter region, the base region, the drift region, the buffer region, the collector region, the gate insulating film, and the gate constitute an IGBT (Gate Insulated Bipolar Transistor). The contact region, the base region, the drift region, the buffer region, and the cathode region constitute a body diode. The contact region and the base region constitute the anode of the body diode. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 2021-093556 Summary of the Invention [Problem to be solved by the invention]

[0009] However, since the dopant concentration in the contact region is higher than that in the base region, the body diode has a high hole injection efficiency from the anode, resulting in a large recovery loss. In addition, since the contact region has a function of suppressing the operation of the parasitic npn bipolar transistor composed of the emitter region, base region, and drift region, it is difficult to reduce the dopant concentration.

[0010] The present disclosure provides a semiconductor device having an IGBT and a body diode with improved recovery loss.

[0011] Other objects and novel features will become apparent from the description of this specification and the accompanying drawings. [Means for solving the problem]

[0012] A semiconductor device according to an embodiment includes a semiconductor substrate, a gate insulating film, a gate, and a first polysilicon film. The semiconductor substrate has a first main surface and a second main surface opposite to the first main surface. The semiconductor substrate has a first portion and a second portion. The semiconductor substrate has a collector region disposed on the second main surface located in the first portion, a cathode region disposed on the second main surface located in the second portion, a drift region disposed on the collector region and the cathode region, an emitter region disposed on the first main surface located in the first portion, a base region disposed between the emitter region and the collector region, and an anode region disposed on the first main surface located in the second portion. The gate is disposed so as to face a portion of the base region sandwiched between the emitter region and the drift region with the gate insulating film interposed therebetween. The first polysilicon film is disposed on the anode region. The emitter region, the emitter region, and the cathode region have n-type conductivity. The conductivity type of the collector region, the base region, the anode region and the first polysilicon film is p-type. Effect of the Invention

[0013] According to the semiconductor device of the embodiment, the recovery loss of the body diode can be improved. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a cross-sectional view of the semiconductor device DEV1. [Diagram 2] 1A to 1C are process diagrams showing a manufacturing method of the semiconductor device DEV1. [Diagram 3] FIG. 2 is a cross-sectional view illustrating a preparation step S1. [Figure 4] FIG. 11 is a cross-sectional view illustrating a gate trench forming step S2. [Diagram 5] FIG. 11 is a cross-sectional view illustrating a gate insulating film forming step S3. [Figure 6] FIG. 11 is a cross-sectional view illustrating a gate forming step S4. [Figure 7] FIG. 11 is a cross-sectional view illustrating an insulating film forming step S5. [Figure 8] FIG. 11 is a cross-sectional view illustrating a polysilicon film forming step S6. [Figure 9] FIG. 11 is a cross-sectional view illustrating a first ion implantation step S7. [Figure 10] FIG. 11 is a cross-sectional view illustrating a second ion implantation step S8. [Figure 11] FIG. 11 is a cross-sectional view illustrating an interlayer insulating film forming step S9. [Figure 12] FIG. 11 is a cross-sectional view illustrating a third ion implantation step S10. [Figure 13] 11 is a cross-sectional view illustrating a contact plug forming step S11. [Figure 14] FIG. 11 is a cross-sectional view illustrating a wiring forming step S12. [Figure 15] FIG. 11 is a cross-sectional view illustrating a polishing step S13. [Figure 16] FIG. 11 is a cross-sectional view illustrating a fourth ion implantation step S14. [Figure 17] FIG. 11 is a cross-sectional view illustrating a fifth ion implantation step S15. [Figure 18] FIG. 11 is a cross-sectional view illustrating a sixth ion implantation step S16. [Figure 19] FIG. 2 is a cross-sectional view of the semiconductor device DEV2. [Figure 20] FIG. 13 is a cross-sectional view of the semiconductor device DEV3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The details of the embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and redundant description will not be repeated.

[0016] (First embodiment) A description will be given of a semiconductor device according to a first embodiment. The semiconductor device according to the first embodiment is referred to as a semiconductor device DEV1.

[0017] <Configuration of semiconductor device DEV1> The configuration of the semiconductor device DEV1 will be described below.

[0018] Fig. 1 is a cross-sectional view of a semiconductor device DEV1. As shown in Fig. 1, the semiconductor device DEV1 includes a semiconductor substrate SUB, a gate insulating film GI, a gate G, an insulating film IF1, polysilicon films PSF1 and PSF2, an interlayer insulating film ILD, contact plugs CP1 and CP2, a wiring WL1, and an electrode EL.

[0019] The semiconductor substrate SUB has a first main surface MS1 and a second main surface MS2. The first main surface MS1 and the second main surface MS2 are end surfaces of the semiconductor substrate SUB in the thickness direction. The second main surface MS2 is the opposite surface to the first main surface MS1. The thickness direction of the semiconductor substrate SUB is defined as a first direction D1. The semiconductor substrate SUB is formed of, for example, single crystal silicon (Si).

[0020] The semiconductor substrate SUB has a first portion SUBa, a second portion SUBb, and a third portion SUBc. The first portion SUBa and the second portion SUBb are adjacent to each other in the second direction D2. The second direction D2 is a direction perpendicular to the first direction D1. The number of the first portions SUBa and the second portions SUBb may be more than one. The multiple first portions SUBa and second portions SUBb are alternately arranged in the second direction D2. The third portion SUBc is adjacent to the second portion SUBb from the side opposite to the first portion SUBa in the second direction D2, for example.

[0021] The semiconductor substrate SUB has a collector region CLR, a cathode region CAR, a buffer region BFR, a drift region DR, an emitter region EMR, a base region BR, a backgate region BGR, and an anode region ANR. The cathode region CAR, the buffer region BFR, the drift region DR, and the emitter region EMR have an n-type conductivity. The collector region CLR, the base region BR, the backgate region BGR, and the anode region ANR have a p-type conductivity. The dopant concentration in the cathode region CAR and the emitter region EMR is higher than that in the buffer region BFR. The dopant concentration in the buffer region BFR is higher than that in the drift region DR. The dopant concentration in the backgate region BGR is higher than that in the base region BR. The dopant concentration in the base region BR is higher than that in the anode region ANR.

[0022] The collector region CLR and the cathode region CAR are disposed in the second main surface MS2. More specifically, the collector region CLR is disposed in the second main surface MS2 located in the first portion SUBa, and the cathode region CAR is disposed in the second main surface MS2 located in the second portion SUBb and the third portion SUBc.

[0023] The buffer region BFR is disposed on the collector region CLR and the cathode region CAR. The drift region DR is disposed on the buffer region BFR. That is, the drift region DR is disposed on the collector region CLR and the cathode region CAR with the buffer region BFR interposed therebetween. The emitter region EMR is disposed in the first main surface MS1 located in the first portion SUBa. The base region BR is disposed between the emitter region EMR and the drift region DR.

[0024] The back-gate region BGR is disposed in the base region BR. The anode region ANR is disposed in the first main surface MS1 located in the second portion SUBb. The anode region ANR and the drift region DR are connected by a pn junction to form a body diode.

[0025] A gate trench TR is formed in the first main surface MS1 located in the first portion SUBa. The gate trench TR extends from the first main surface MS1 toward the second main surface MS2 along the first direction D1. The emitter region EMR, the base region BR, and the drift region DR are exposed from the side surfaces of the gate trench TR.

[0026] The gate G is buried in the gate trench TR. The gate G is formed of, for example, polysilicon containing a dopant. The gate insulating film GI is disposed between the gate G and the side and bottom surfaces of the gate trench TR. As a result, the gate G faces a portion of the base region BR sandwiched between the emitter region EMR and the drift region DR, with the gate insulating film GI interposed therebetween. The gate insulating film GI is formed of, for example, silicon oxide (SiO2). The emitter region EMR, the base region BR, the drift region DR, the buffer region BFR, and the collector region CLR constitute an IGBT.

[0027] The insulating film IF1 is disposed on the first main surface MS1. More specifically, the insulating film IF1 is disposed on a part of the first main surface MS1 located in the third portion SUBc. The insulating film IF1 is formed of, for example, silicon oxide.

[0028] The polysilicon film PSF1 is disposed on the anode region ANR. The polysilicon film PSF1 is formed of polycrystalline silicon containing a dopant. The conductivity type of the polysilicon film PSF1 is p-type. The polysilicon film PSF1 is electrically connected to the anode region ANR.

[0029] The dopant concentration in the polysilicon film PSF1 is higher than the dopant concentration in the anode region ANR. A contact region CTR is disposed in the polysilicon film PSF1. The dopant concentration in the contact region CTR is higher than the dopant concentration in the polysilicon film PSF1 other than the contact region CTR.

[0030] The polysilicon film PSF2 is disposed on the first main surface MS1 located in the third portion SUBc with the insulating film IF1 interposed therebetween. A dopant is implanted into the polysilicon film PSF2 depending on the function to be imparted. The polysilicon film PSF2 functions, for example, as a resistor or a diode (more specifically, a diode for measuring temperature).

[0031] The interlayer insulating film ILD is disposed on the first main surface MS1 so as to cover the insulating film IF1, the polysilicon film PSF1, and the polysilicon film PSF2. The interlayer insulating film ILD is made of, for example, silicon oxide.

[0032] A contact hole CH1 and a contact hole CH2 are formed in the interlayer insulating film ILD. The contact hole CH1 penetrates the interlayer insulating film ILD along a first direction D1. The contact hole CH1 also reaches the semiconductor substrate SUB so as to expose the emitter region EMR and the back gate region BGR. The contact hole CH2 penetrates the interlayer insulating film ILD along the first direction D1. The contact hole CH2 also reaches the polysilicon film PSF1 so as to expose the contact region CTR.

[0033] The contact plug CP1 is embedded in the contact hole CH1. The lower end side of the contact plug CP1 is electrically connected to the emitter region EMR and the back gate region BGR. The contact plug CP2 is embedded in the contact hole CH2. The lower end side of the contact plug CP2 is electrically connected to the contact region CTR. The contact plug CP1 and the contact plug CP2 are formed of, for example, tungsten (W).

[0034] Although not shown, the semiconductor device DEV1 further includes a contact plug CP3, and a contact hole CH3 is further formed in the interlayer insulating film ILD. The contact hole CH3 penetrates the interlayer insulating film ILD along the first direction D1 so as to expose the gate G. The contact hole CH3 may reach the gate G. The contact plug CP3 is buried in the contact hole CH3. The contact plug CP3 is electrically connected to the gate G at its lower end side. The contact plug CP3 is formed of, for example, tungsten.

[0035] The wiring WL1 is disposed on the interlayer insulating film ILD. The wiring WL1 is electrically connected to the upper end side of the contact plug CP1 and the upper end side of the contact plug CP2. The wiring WL1 is formed of, for example, aluminum (Al) or an aluminum alloy. Although not shown, the semiconductor device DEV1 further has a wiring WL2. The wiring WL2 is disposed on the interlayer insulating film ILD and is electrically connected to the upper end side of the contact plug CP3.

[0036] The electrode EL is disposed on the second main surface MS2. The electrode EL is electrically connected to the collector region CLR and the cathode region CAR. The electrode EL is made of, for example, aluminum or an aluminum alloy.

[0037] <Manufacturing Method of Semiconductor Device DEV1> A method for manufacturing the semiconductor device DEV1 will be described below.

[0038] Fig. 2 is a process diagram showing a manufacturing method of the semiconductor device DEV1. As shown in Fig. 2, the manufacturing method of the semiconductor device DEV1 includes a preparation step S1, a gate trench formation step S2, a gate insulating film formation step S3, a gate formation step S4, an insulating film formation step S5, a polysilicon film formation step S6, a first ion implantation step S7, a second ion implantation step S8, an interlayer insulating film formation step S9, a third ion implantation step S10, a contact plug formation step S11, a wiring formation step S12, a polishing step S13, a fourth ion implantation step S14, a fifth ion implantation step S15, a sixth ion implantation step S16, and an electrode formation step S17.

[0039] Fig. 3 is a cross-sectional view illustrating the preparation step S1. As shown in Fig. 3, in the preparation step S1, a semiconductor substrate SUB is prepared. However, the thickness of the semiconductor substrate SUB prepared in the preparation step S1 is smaller than the thickness of the semiconductor substrate SUB included in the semiconductor device DEV1. The conductivity type of the semiconductor substrate SUB prepared in the preparation step S1 is n-type.

[0040] Fig. 4 is a cross-sectional view illustrating the gate trench forming step S2. In the gate trench forming step S2, a gate trench TR is formed as shown in Fig. 4. The gate trench TR is formed by, for example, etching using a hard mask disposed on the first main surface MS1.

[0041] 5 is a cross-sectional view illustrating the gate insulating film forming step S3. As shown in Fig. 5, in the gate insulating film forming step S3, a gate insulating film GI is formed. The gate insulating film GI is formed, for example, by thermally oxidizing the first main surface MS1 side of the semiconductor substrate SUB.

[0042] 6 is a cross-sectional view illustrating the gate formation step S4. As shown in FIG. 6, in the gate formation step S4, the gate G is formed. In the gate formation step S4, first, a constituent material of the gate G is embedded in the gate trench TR, for example, by CVD (Chemical Vapor Deposition). Second, the constituent material of the gate G protruding from the gate trench TR is removed, for example, by CMP (Chemical Mechanical Polishing). The constituent material of the gate G protruding from the gate trench TR may be removed by etch-back.

[0043] FIG. 7 is a cross-sectional view for explaining the insulating film forming step S5. As shown in FIG. 7, in the insulating film forming step S5, an insulating film IF1 is formed. In the insulating film forming step S5, first, a constituent material of the insulating film IF1 is deposited on the first main surface MS1 by CVD or the like. Second, the deposited constituent material of the insulating film IF1 is etched using a resist formed by photolithography as a mask. As a result, the insulating film IF1 having an opening at a position where the polysilicon film PSF1 is to be formed is formed. After the above etching is performed, the first main surface MS1 is cleaned.

[0044] FIG. 8 is a cross-sectional view for explaining the polysilicon film forming step S6. As shown in FIG. 8, polysilicon films PSF1, PSF2, and the anode region ANR are formed. In the polysilicon film forming step S6, first, polysilicon is formed on the first main surface MS1 so as to cover the insulating film IF1. Note that this polysilicon is non-doped (does not contain dopant). Second, dopant is ion-implanted into the formed polysilicon. Third, heat treatment is performed. By this heat treatment, the dopant in the formed polysilicon is diffused into the semiconductor substrate SUB, and the anode region ANR is formed. Fourth, the formed polysilicon is etched using a resist formed by photolithography as a mask. In this manner, the polysilicon film PSF1 and the polysilicon film PSF2 are formed. Note that after the polysilicon film PSF1, the polysilicon film PSF2, and the anode region ANR are formed, the portion of the insulating film IF1 other than under the polysilicon film PSF2 is removed by etching.

[0045] Fig. 9 is a cross-sectional view illustrating the first ion implantation step S7. In the first ion implantation step S7, as shown in Fig. 9, ion implantation is performed to form a base region BR. Fig. 10 is a cross-sectional view illustrating the second ion implantation step S8. In the second ion implantation step S8, as shown in Fig. 10, ion implantation is performed to form an emitter region EMR.

[0046] FIG. 11 is a cross-sectional view for explaining the interlayer insulating film forming step S9. As shown in FIG. 11, in the interlayer insulating film forming step S9, the interlayer insulating film ILD is formed. In the interlayer insulating film forming step S9, first, a constituent material of the interlayer insulating film ILD is deposited on the first main surface MS1 so as to cover the insulating film IF1, the polysilicon film PSF1, and the polysilicon film PSF2. Second, the deposited constituent material of the interlayer insulating film ILD is planarized by, for example, CMP. Third, the interlayer insulating film ILD is etched using a resist formed by photolithography as a mask, thereby forming contact holes CH1, CH2, and CH3 (not shown). In this manner, the interlayer insulating film ILD is formed.

[0047] 12 is a cross-sectional view illustrating the third ion implantation process S10. As shown in FIG. 12, in the third ion implantation process S10, ion implantation is performed to form the back gate region BGR and the contact region CTR. This ion implantation is performed through the contact holes CH1 and CH2.

[0048] 13 is a cross-sectional view illustrating the contact plug forming step S11. As shown in FIG. 13, in the contact plug forming step S11, contact plugs CP1, CP2, and CP3 (not shown) are formed. In the contact plug forming step S11, first, the constituent material of the contact plugs (contact plugs CP1, CP2, and CP3) is filled into the contact holes CH1, CH2, and CH3 (not shown) by, for example, CVD. Second, the constituent material of the contact plugs protruding from the contact holes CH1, CH2, and CH3 is removed by, for example, CMP. In this manner, the contact plugs CP1, CP2, and CP3 are formed.

[0049] Fig. 14 is a cross-sectional view illustrating the wiring formation step S12. As shown in Fig. 14, in the wiring formation step S12, wiring WL1 and wiring WL2 (not shown) are formed. In the wiring formation step S12, first, a constituent material of the wiring (wiring WL1 and wiring WL2) is deposited on the interlayer insulating film ILD. Second, the deposited constituent material of the wiring is etched using a resist formed by photolithography as a mask. As a result, the wiring WL1 and wiring WL2 are formed.

[0050] FIG. 15 is a cross-sectional view illustrating the polishing step S13. As shown in FIG. 15, in the polishing step S13, the second main surface MS2 side of the semiconductor substrate SUB is polished, thereby reducing the thickness of the semiconductor substrate SUB. FIG. 16 is a cross-sectional view illustrating the fourth ion implantation step S14. As shown in FIG. 16, in the fourth ion implantation step S14, a buffer region BFR is formed by ion implantation. FIG. 17 is a cross-sectional view illustrating the fifth ion implantation step S15. As shown in FIG. 17, in the fifth ion implantation step S15, a collector region CLR is formed by ion implantation.

[0051] FIG. 18 is a cross-sectional view for explaining the sixth ion implantation step S16. As shown in FIG. 18, in the sixth ion implantation step S16, a cathode region CAR is formed. In the sixth ion implantation step S16, first, a resist is formed on the second main surface MS2. This resist is patterned by photolithography so that only the portion where the cathode region CAR is to be formed is opened. Second, ion implantation is performed using the resist as a mask. As a result, the cathode region CAR is formed. Note that the portion of the semiconductor substrate SUB where the ion implantation is not performed becomes the drift region DR.

[0052] In the electrode formation step S17, the electrode EL is formed on the second main surface MS2. The electrode EL is formed by, for example, sputtering. In this manner, the semiconductor device DEV1 having the structure shown in FIG.

[0053] <Effects of semiconductor device DEV1> The effects of the semiconductor device DEV1 will be described below in comparison with a comparative example, which will be referred to as a semiconductor device DEV2.

[0054] Fig. 19 is a cross-sectional view of the semiconductor device DEV2. As shown in Fig. 19, the semiconductor device DEV1 has a semiconductor substrate SUB, a gate insulating film GI, a gate G, an interlayer insulating film ILD, a contact plug CP1, and an electrode EL. In the semiconductor device DEV2, the semiconductor substrate SUB has a collector region CLR, a buffer region BFR, a drift region DR, an emitter region EMR, a base region BR, a backgate region BGR, and a cathode region CAR.

[0055] In the semiconductor device DEV2, a cathode region CAR is arranged in place of the collector region CLR on the second main surface MS2 below the backgate region BGR. In the semiconductor device DEV2, the backgate region BGR, the base region BR, the drift region DR, and the cathode region CAR configure a body diode. In the body diode of the semiconductor device DEV2, since the anode has the backgate region BGR with a high dopant concentration, the efficiency of hole injection to the cathode is high and the forward voltage can be reduced, but the recovery loss is large.

[0056] Furthermore, in the semiconductor device DEV2, if the dopant concentration in the backgate region BGR is lowered, the parasitic npn bipolar transistor formed by the emitter region EMR, the base region BR, and the drift region DR becomes easier to operate, and therefore it is difficult to lower the dopant concentration in the backgate region BGR.

[0057] On the other hand, in the semiconductor device DEV1, the anode of the body diode is composed of the anode region ANR. The anode region ANR is formed by diffusing a dopant from the polysilicon film PSF1. Therefore, in the semiconductor device DEV1, the dopant concentration in the anode region ANR can be made low independently of the dopant concentration in the backgate region BGR. In this way, in the semiconductor device DEV1, the recovery loss of the body diode can be reduced while suppressing the operation of the parasitic npn bipolar transistor composed of the emitter region EMR, the base region BR, and the drift region DR.

[0058] In addition, in the semiconductor device DEV1, the polysilicon film PSF1 used for forming the anode region ANR is formed in the same process as the polysilicon film PSF2. Therefore, in the semiconductor device DEV1, a body diode with reduced recovery loss can be formed without adding a new process.

[0059] <Modification> In the above description, the IGBT included in the semiconductor device DEV1 is a trench gate type IGBT. However, the IGBT included in the semiconductor device DEV1 may be a planar gate type IGBT.

[0060] Second embodiment A semiconductor device according to a second embodiment will be described. The semiconductor device according to the second embodiment will be referred to as a semiconductor device DEV3. Here, differences from the semiconductor device DEV1 will be mainly described, and overlapping descriptions will not be repeated.

[0061] <Configuration of semiconductor device DEV3> The configuration of the semiconductor device DEV3 will be described below.

[0062] Fig. 20 is a cross-sectional view of the semiconductor device DEV3. As shown in Fig. 20, the semiconductor device DEV3 includes a semiconductor substrate SUB, a gate insulating film GI, a gate G, an insulating film IF1, a polysilicon film PSF1, a polysilicon film PSF2, an interlayer insulating film ILD, contact plugs CP1, CP2, and CP3 (not shown), wirings WL1 and WL2 (not shown), and an electrode EL.

[0063] In the semiconductor device DEV3, the semiconductor substrate SUB has a collector region CLR, a cathode region CAR, a buffer region BFR, a drift region DR, an emitter region EMR, a base region BR, a backgate region BGR, and an anode region ANR. In these respects, the configuration of the semiconductor device DEV3 is common to the configuration of the semiconductor device DEV1.

[0064] The semiconductor device DEV3 further has an insulating film IF2. The insulating film IF2 is disposed between the anode region ANR and the polysilicon film PSF1. The insulating film IF2 is formed of, for example, silicon oxide. The thickness of the insulating film IF2 is preferably 5 nm or less from the viewpoint of suppressing the dopant in the polysilicon film PSF1 from being difficult to diffuse into the semiconductor substrate SUB and from the viewpoint of suppressing electrical insulation between the polysilicon film PSF1 and the anode region ANR. The thickness of the insulating film IF2 is more preferably 3 nm or less. In these respects, the configuration of the semiconductor device DEV2 differs from the configuration of the semiconductor device DEV1.

[0065] <Manufacturing Method of Semiconductor Device DEV3> A method for manufacturing the semiconductor device DEV3 will be described below.

[0066] The manufacturing method of the semiconductor device DEV3 includes a preparation step S1, a gate trench formation step S2, a gate insulating film formation step S3, a gate formation step S4, an insulating film formation step S5, a polysilicon film formation step S6, a first ion implantation step S7, a second ion implantation step S8, and an interlayer insulating film formation step S9. The manufacturing method of the semiconductor device DEV3 further includes a third ion implantation step S10, a contact plug formation step S11, a wiring formation step S12, a polishing step S13, a fourth ion implantation step S14, a fifth ion implantation step S15, a sixth ion implantation step S16, and an electrode formation step S17. In this respect, the manufacturing method of the semiconductor device DEV3 is common to the manufacturing method of the semiconductor device DEV1.

[0067] In the insulating film forming step S5, after etching of the constituent material of the insulating film IF1, the first main surface MS1 is cleaned, for example, with APM (Ammonia-hydrogen Peroxide Mixture). As a result, the insulating film IF2 is formed. In this respect, the manufacturing method of the semiconductor device DEV3 differs from the manufacturing method of the semiconductor device DEV1.

[0068] <Effects of semiconductor device DEV3> The effects of the semiconductor device DEV3 will be described below.

[0069] The barrier height of the insulating film IF2 against holes (about 1.0 eV) is higher than the barrier height of the insulating film IF2 against electrons (about 0.3 eV). Therefore, in the semiconductor device DEV3, holes are less likely to move from the polysilicon film PSF1 to the body diode across the insulating film IF2, and the hole injection efficiency is further reduced. As a result, the semiconductor device DEV3 can further reduce the recovery loss of the body diode.

[0070] The invention made by the inventor has been specifically described above based on an embodiment, but it goes without saying that the present invention is not limited to the above embodiment and can be modified in various ways without departing from the gist of the invention. [Explanation of symbols]

[0071] ANR anode region, BFR buffer region, BGR backgate region, BR base region, CAR cathode region, CH1 contact hole, CH2 contact hole, CH3 contact hole, CLR collector region, CP1 contact plug, CP2 contact plug, CP3 contact plug, CTR contact region, D1 first direction, D2 second direction, DEV1 semiconductor device, DEV2 semiconductor device, DEV3 semiconductor device, DR drift region, EL electrode, EMR emitter region, G gate, GI gate insulating film, IF1 insulating film, IF2 insulating film, ILD interlayer insulating film, MS1 first main surface, MS2 second main surface, PSF1, PSF2 polysilicon film, S1 preparation step, S2 gate trench formation step, S3 gate insulating film formation step, S4 gate formation step, S5 insulating film formation step, S6 polysilicon film formation step, S7 first ion implantation step, S8 second ion implantation step, S9 an interlayer insulating film forming step, S10 a third ion implantation step, S11 a contact plug forming step, S12 a wiring forming step, S13 a polishing step, S14 a fourth ion implantation step, S15 a fifth ion implantation step, S16 a sixth ion implantation step, S17 an electrode forming step, SUB a semiconductor substrate, SUBa a first portion, SUBb a second portion, SUBc a third portion, TR a gate trench, and WL1 and WL2 wirings.

Claims

1. A semiconductor substrate; A gate insulating film; Gate and a first polysilicon film; the semiconductor substrate has a first main surface and a second main surface opposite to the first main surface; the semiconductor substrate having a first portion and a second portion; the semiconductor substrate has a collector region disposed on the second main surface located in the first portion, a cathode region disposed on the second main surface located in the second portion, a drift region disposed on the collector region and the cathode region, an emitter region disposed on the first main surface located in the first portion, a base region disposed between the emitter region and the collector region, and an anode region disposed on the first main surface located in the second portion, the gate is disposed to face a portion of the base region sandwiched between the emitter region and the drift region with the gate insulating film interposed therebetween; the first polysilicon film is disposed on the anode region; the emitter region, the emitter region, and the cathode region have an n-type conductivity; the collector region, the base region, the anode region and the first polysilicon film have a conductivity type of p-type; a first insulating film disposed between the anode region and the first polysilicon film; The semiconductor device, wherein the first insulating film has a thickness of 5 nm or less.

2. a gate trench is formed in the first main surface located in the first portion, the gate trench extending toward the second main surface so as to expose the emitter region, the base region, and the drift region; The gate is embedded in the gate trench, The semiconductor device according to claim 1 , wherein the gate insulating film is disposed between the gate and the side and bottom surfaces of the gate trench.

3. the semiconductor substrate further includes a back gate region disposed within the base region and having a p-type conductivity; The semiconductor device according to claim 1 , wherein a dopant concentration in said anode region is lower than a dopant concentration in said back gate region.

4. A second insulating film; A second polysilicon film is further provided, the semiconductor substrate further comprising a third portion; the second insulating film is disposed on the first main surface located in the third portion, 2. The semiconductor device according to claim 1, wherein said second polysilicon film is disposed on said second insulating film.

5. 5. The semiconductor device according to claim 4, wherein said second polysilicon film constitutes a resistor or a diode.

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