Semiconductor Device

Abstract

A semiconductor substrate (1) has a drift layer (8). An IGBT region (2) and a diode region (3) are provided on the semiconductor substrate (1) and have an emitter electrode (16) on the surface of the semiconductor substrate (1). A sense IGBT region (4) is provided on the semiconductor substrate (1), has a smaller area than that of the IGBT region (2), and has a sense emitter electrode (20) that is on the surface of the semiconductor substrate (1) and that is separated from the emitter electrode (16). A sense diode region (5) is provided on the semiconductor substrate (1), has a smaller area than that of the diode region (3), and has a sense anode electrode (21) that is on the surface of the semiconductor substrate (1) and that is separated from the emitter electrode (16). The sense diode region (5) is separated from the IGBT region (2) by a distance that is greater than or equal to the thickness of the drift layer (8).

Description

[Technical field]

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

[0002] Reverse conducting insulated gate bipolar transistors (RC-IGBTs) are widely used in power conversion devices such as inverters. In recent years, the element size of the RC-IGBTs mounted on inverters has been reduced in order to miniaturize inverters and reduce their costs. If the area ratio of the IGBT region is increased to reduce the conduction loss and switching loss, the diode region becomes relatively narrow. This can cause the diode to exceed the peak surge forward current during freewheeling, resulting in destruction. Therefore, it has been proposed to provide a sense diode region that monitors the conduction current of the diode and detect the application of a current that can cause destruction (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2009-135414 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional semiconductor devices have a problem in that the accuracy of detecting the current in the sense diode region is low.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a semiconductor device capable of improving the accuracy of current detection in a sense diode region. [Means for solving the problem]

[0006] A semiconductor device according to the present disclosure includes a semiconductor substrate having a drift layer, an IGBT region and a diode region provided in the semiconductor substrate and having an emitter electrode on a surface of the semiconductor substrate, a sense IGBT region provided in the semiconductor substrate, having an area smaller than that of the IGBT region and having a sense emitter electrode separated from the emitter electrode on the surface of the semiconductor substrate, and a sense diode region provided in the semiconductor substrate, having an area smaller than that of the diode region and having a sense anode electrode separated from the emitter electrode on the surface of the semiconductor substrate, the sense diode region being spaced apart from the IGBT region by a distance equal to or greater than the thickness of the drift layer. the diode region is disposed within a thickness of the drift layer from the sense diode region; It is characterized by: Effect of the Invention

[0007] In the present disclosure, the sense diode region is separated from the IGBT region and the sense IGBT region by at least the thickness of the drift layer, which makes it possible to prevent the reflux current from flowing into the IGBT region and the sense IGBT region during reflux operation, thereby improving the current detection accuracy of the sense diode region. [Brief description of the drawings]

[0008] [Figure 1] 1 is a plan view showing a semiconductor device according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view taken along line I-II of FIG. [Diagram 3] FIG. 2 is a cross-sectional view taken along line III-IV in FIG. [Figure 4] FIG. 2 is a cross-sectional view taken along line V-VI in FIG. [Diagram 5] FIG. 2 is a diagram illustrating a diode current detection circuit. [Figure 6] FIG. 11 is a top view showing a semiconductor device according to a second embodiment. [Figure 7] FIG. 7 is a cross-sectional view taken along line I-II in FIG. [Figure 8] FIG. 11 is a top view showing a semiconductor device according to a third embodiment. [Figure 9] FIG. 9 is a cross-sectional view taken along line I-II of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A semiconductor device according to an embodiment will be described with reference to the drawings. The same or corresponding components are designated by the same reference numerals, and repeated description may be omitted.

[0010] Embodiment 1 1 is a plan view showing a semiconductor device according to a first embodiment. This semiconductor device is an RC-IGBT in which an IGBT region 2 and a diode region 3 are provided on one semiconductor substrate 1. A sense IGBT region 4, a sense diode region 5, and a gate pad 6 are provided on the semiconductor substrate 1. A termination region 7 is provided on the outer periphery of the semiconductor substrate 1 so as to surround these regions.

[0011] FIG 2 is a cross-sectional view taken along the line I-II of FIG 1. The semiconductor substrate 1 is a N - The semiconductor device has a P-type drift layer 8. A P-type body layer 9 is provided on the drift layer 8. An N-type buffer layer 10 is provided below the drift layer 8.

[0012] In the IGBT region 2, an N-type emitter layer 11 is provided on the surface layer of a P-type body layer 9. A trench gate 12 is provided in a trench penetrating the N-type emitter layer 11 and the P-type body layer 9 via a gate insulating film. A P-type collector layer 13 is provided below the N-type buffer layer 10. The trench gate 12 is connected to a gate pad 6 for connection to a gate power supply.

[0013] In the diode region 3, a P-type anode layer 14 is provided on the surface layer of the P-type body layer 9. A trench gate 12 is provided in a trench penetrating the P-type body layer 9 via a gate insulating film. An N-type cathode layer 15 is provided under the N-type buffer layer 10.

[0014] An emitter electrode 16 is provided on the surface of the semiconductor substrate 1 in both the IGBT region 2 and the diode region 3. The emitter electrode 16 is connected to the P-type body layer 9, the N-type emitter layer 11, and the P-type anode layer 14. An insulating film 17 is provided on the trench gate 12 to insulate the trench gate 12 from the emitter electrode 16. A collector electrode 18 is provided on the back surface of the semiconductor substrate 1 in both the IGBT region 2 and the diode region 3. The collector electrode 18 is connected to the P-type collector layer 13 and the N-type cathode layer 15.

[0015] 3 is a cross-sectional view taken along line III-IV in FIG. 1. The structure of the sense IGBT region 4 is similar to that of the IGBT region 2. In the sense IGBT region 4, a sense emitter electrode 20 provided on the surface of the semiconductor substrate 1 is connected to the P-type body layer 9 and the N-type emitter layer 11, and is separated from the emitter electrode 16. An isolation region 19 exists between the IGBT region 2 and the sense IGBT region 4. The isolation region 19 is a region where the N-type emitter layer 11, the P-type anode layer 14, and the trench gate 12 do not exist. The sense IGBT region 4 is provided only directly below the sense emitter electrode 20.

[0016] Fig. 4 is a cross-sectional view taken along line V-VI in Fig. 1. The structure of the sense diode region 5 is similar to that of the diode region 3. In the sense diode region 5, a sense anode electrode 21 provided on the surface of the semiconductor substrate 1 is connected to the P-type body layer 9 and the P-type anode layer 14, and is separated from the emitter electrode 16. The sense diode region 5 is provided only directly below the sense anode electrode 21.

[0017] The sum of the areas of the IGBT regions 2, SI, is greater than the sum of the areas of the diode regions 3, SD (SI>SD). The area of ​​the sense IGBT region 4, SSI, is smaller than the sum of the areas of the IGBT regions 2, SI>SSI. The area of ​​the sense diode region 5, SSD, is smaller than the sum of the areas of the diode regions 3, SD (SD>SSD).

[0018] 5 is a diagram showing a diode current detection circuit. The sense emitter electrode 20 of the sense IGBT region 4 and the emitter electrode 16 of the main part including the IGBT region 2 and the diode region 3 are connected via a sense resistor Ra. The sense anode electrode 21 of the sense diode region 5 and the emitter electrode 16 of the main part are connected via a sense resistor Rb.

[0019] A current corresponding to the area ratio between the IGBT region 2 and the sense IGBT region 4 flows through the resistor Ra. Therefore, by measuring the inter-terminal voltage between the sense emitter electrode 20 of the sense IGBT region 4 and the emitter electrode 16 of the IGBT region 2, the current flowing through the IGBT region 2 can be detected.

[0020] A current corresponding to the area ratio between the diode region 3 and the sense diode region 5 flows through the resistor Rb. Therefore, the current ID flowing through the diode region 3 can be detected by measuring the terminal voltage Vb between the sense anode electrode 21 of the sense diode region 5 and the emitter electrode 16 of the IGBT region 2. For example, the current ID is expressed as follows using Vb, SD, SSD, and Rb. ID=(Vb / Rb)*(SD / SSD) Similarly, Vb is expressed as follows: Vb=Rb*ID*(SSD / SD) Therefore, ID can be detected by the voltage measurement circuit measuring Vb.

[0021] By monitoring the current in the diode region 3 using the sense diode region 5, it becomes possible to detect an overcurrent in the diode region 3 and feed it back to the protection function. During freewheeling operation, a current flows through the drift layer 8 within a range of 45 degrees from the rear surface of the substrate. If this current flows into the IGBT region 2 and the sense IGBT region 4, the current detection accuracy of the sense diode region 5 decreases. Therefore, in this embodiment, the sense diode region 5 is separated from the IGBT region 2 and the sense IGBT region 4 by at least the thickness of the drift layer 8. This makes it possible to prevent the current from flowing into the IGBT region 2 during freewheeling operation, and improves the current detection accuracy of the sense diode region 5.

[0022] Moreover, by separating the sense diode region 5 from the sense IGBT region 4 by at least the thickness of the drift layer 8, the current detection accuracy of the sense diode region 5 is further improved.

[0023] In addition, the width d1 of the isolation region 19 that isolates the IGBT region 2 and the sense IGBT region 4 is also larger than the thickness d2 of the drift layer 8 (d1>d2). That is, the sense IGBT region 4 is separated from the IGBT region 2 by at least the thickness of the drift layer 8. This prevents the current from flowing into the IGBT region 2, improving the current detection accuracy of the sense IGBT region 4.

[0024] Embodiment 2 Fig. 6 is a top view showing a semiconductor device according to a second embodiment. Fig. 7 is a cross-sectional view taken along line I-II in Fig. 6. In this embodiment, a diode region 3 is disposed around a sense diode region 5. The distance from the outer end of the sense diode region 5 to the boundary between the diode region 3 surrounding the sense diode region 5 and the IGBT region 2 is d3, where d3>d1.

[0025] It is necessary to separate the sense diode region 5 from the IGBT region 2, but if the region for separating them is the separation region 19, the region contributing to the conduction of current in the semiconductor device will be reduced. Therefore, in this embodiment, the diode region 3 is disposed in a region within the thickness of the drift layer 8 from the sense diode region 5. During the return current operation, the diode region 3 around the sense diode region 5 also performs the return current operation. Therefore, the current flowing through the sense diode region 5 can be ensured without providing a wide separation region 19 that does not contribute to the conduction of current. Therefore, the current detection accuracy of the sense diode region 5 can be improved, and the separation region 19 can be narrowed to reduce the size of the semiconductor device.

[0026] The isolation region 19 is a region that does not have the P-type anode layer 14, etc., and it is necessary to electrically isolate the anode of the diode region 3 from the anode of the sense diode region 5. Since it is expected that the potential difference between the diode region 3 and the sense diode region 5 will increase by several volts by adding a sense resistor, the width of the isolation region 19 is set to 20 μm or more.

[0027] Embodiment 3 FIG. 8 is a top view showing a semiconductor device according to a third embodiment. FIG. 9 is a cross-sectional view taken along line I-II in FIG. 8. The IGBT regions 2 and the diode regions 3 are alternately arranged in stripes along the trench gate 12 in a plan view. The semiconductor substrate 1 is divided into two or more regions including a first region 22 and a second region 23. The first region 22 and the second region 23 are adjacent to each other in the extending direction of the trench gate 12. The trench gate 12 and the diffusion layer are separated between the adjacent regions. The repetition of the IGBT regions 2 and the diode regions 3 is reversed in the first region 22 and the second region 23. As a result, the IGBT regions 2 that mainly generate heat during inverter operation are arranged apart from each other, so that the heat generation of the entire semiconductor device is suppressed and the current carrying capacity can be improved.

[0028] It is desirable to arrange the IGBT region 2 around the sense IGBT region 4, and the diode region 3 around the sense diode region 5. However, if the sense IGBT region 4 and the sense diode region 5 are arranged in the same region, one trench gate 12 is provided in both the IGBT region 2 and the diode region 3 in the peripheral region of the sense IGBT region 4 and the sense diode region 5. In this case, the trench gate 12 cannot be grounded to the emitter. Therefore, the diode region 3 has a capacitance, and the input capacitance and feedback capacitance of the semiconductor device increase.

[0029] Therefore, the sense IGBT region 4 is disposed in the IGBT region 2 of the first region 22, and the sense diode region 5 is disposed in the diode region 3 of the second region 23. The IGBT region 2 of the first region 22 in which the sense IGBT region 4 is disposed and the diode region 3 of the second region 23 in which the sense diode region 5 is disposed are adjacent to each other. The trench gates 12 provided in the adjacent IGBT region 2 of the first region 22 and the diode region 3 of the second region 23 are not connected to each other. Therefore, the trench gate 12 provided in the diode region 3 can be grounded to the emitter to suppress an increase in capacitance. As a result, the input capacitance and feedback capacitance of the semiconductor device are only in the IGBT region, so that the switching loss can be reduced and the semiconductor device can be made smaller.

[0030] Furthermore, the distance from the outer end of the sense diode region 5 to the boundary between the diode region 3 surrounding the sense diode region 5 and the IGBT region 2 is d4, where d4>d1. As a result, similarly to the second embodiment, the current detection accuracy of the sense diode region 5 can be improved, and the isolation region 19 can be narrowed to reduce the size of the semiconductor device.

[0031] The semiconductor substrate 1 is not limited to being made of silicon, and may be made of a wide band gap semiconductor having a larger band gap than silicon. The wide band gap semiconductor is, for example, silicon carbide, gallium nitride-based material, or diamond. A semiconductor chip made of such a wide band gap semiconductor has high voltage resistance and allowable current density, and can be miniaturized. By using this miniaturized semiconductor chip, a semiconductor device incorporating this semiconductor chip can also be miniaturized and highly integrated. In addition, since the semiconductor chip has high heat resistance, the heat dissipation fins of the heat sink can be miniaturized, and the water-cooled part can be air-cooled, so the semiconductor device can be further miniaturized. In addition, since the power loss of the semiconductor chip is low and highly efficient, the efficiency of the semiconductor device can be increased. [Explanation of symbols]

[0032] 1 semiconductor substrate, 2 IGBT region, 3 diode region, 4 sense IGBT region, 8 drift layer, 16 emitter electrode, 20 sense emitter electrode, 22 first region, 23 second region

Claims

1. A semiconductor substrate having a drift layer; an IGBT region and a diode region provided on the semiconductor substrate, the IGBT region and the diode region having emitter electrodes on a surface of the semiconductor substrate; a sense IGBT region provided on the semiconductor substrate, the sense IGBT region having an area smaller than that of the IGBT region and including a sense emitter electrode separated from the emitter electrode on the surface of the semiconductor substrate; a sense diode region provided on the semiconductor substrate, the sense diode region having an area smaller than that of the diode region, and a sense anode electrode separated from the emitter electrode on the surface of the semiconductor substrate; the sense diode region is spaced from the IGBT region by a distance equal to or greater than the thickness of the drift layer, 2. A semiconductor device comprising: a first region including a first electrode and a second electrode; a second electrode disposed in a first region of the first electrode and a second electrode disposed in a second region of the first electrode;

2. the semiconductor substrate is divided into a first region and a second region; the IGBT region and the diode region have trench gates; the IGBT regions and the diode regions are alternately arranged in stripes along the trench gate in a plan view, the first region and the second region have a reversed arrangement of the IGBT region and the diode region, the sense IGBT region is disposed within the IGBT region of the first region; 2. The semiconductor device according to claim 1, wherein the sense diode region is disposed within the diode region of the second region.

3. 3. The semiconductor device according to claim 1, wherein the sense diode region is spaced apart from the sense IGBT region by a distance equal to or greater than the thickness of the drift layer.

4. 4. The semiconductor device according to claim 1, wherein the sense IGBT region is spaced apart from the IGBT region by at least the thickness of the drift layer.

5. 5. The semiconductor device according to claim 1, wherein the semiconductor substrate is made of a wide band gap semiconductor.

Images