IP Library › Granted Patent US 10,665,670

Granted Patent B2

US 10,665,670 · App. 16/082,957 · Granted May 26, 2020

Semiconductor device and method for manufacturing same

Inventors: Kazutoyo Takano (Fukuoka, JP); Kazushige Matsuo (Fukuoka, JP); Masayoshi Hirao (Fukuoka, JP); Junji Yahiro (Fukuoka, JP)

Assignee: Mitsubishi Electric Corporation

H01L29/0661 H01L21/042 H01L21/0475 H01L21/304 H01L21/3043 H01L21/6835 H01L27/04 H01L27/0664 H01L29/0623 H01L29/1095 H01L29/12 H01L29/1602 H01L29/1608 H01L29/2003 H01L29/6631 H01L29/66045 H01L29/66068 H01L29/66348 H01L29/739 H01L29/7397 H01L29/78 H01L29/8613 H01L2221/6834 H01L2221/68327

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Quick Facts

Patent No.: US 10,665,670
App. No.: 16/082,957
Granted: May 26, 2020
Kind: B2

External Links

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Abstract

A semiconductor device according to the present invention includes a substrate having a cell portion and a terminal portion surrounding the cell portion, a surface structure provided on the substrate, and a back surface electrode provided on the back surface of the substrate, the surface structure includes a convex portion protruding upward above the cell portion, and at least a part of the cell portion is thinner than the terminal portion.

Claims (111)

1. A semiconductor device comprising:

a substrate including a cell portion and a terminal portion surrounding the cell portion;

a surface structure provided on the substrate; and

a back surface electrode provided on a back surface of the substrate,

wherein the surface structure includes a convex portion protruding upward above the cell portion,

at least a part of the cell portion is thinner than the terminal portion,

the back surface electrode under the cell portion and the back surface electrode under the terminal portion form a concave shape,

a lower surface of the back surface electrode under the cell portion and a lower surface of the back surface electrode under the terminal portion are smoothly connected to each other,

the surface structure includes a surface electrode provided on the substrate and an insulating film provided on the substrate, the surface electrode having a base portion and an upper portion, the upper portion being on the base portion and narrower than the base portion in plan view, and

the convex portion is a part of the surface electrode, and the insulating film directly contacts a portion of the upper portion of the surface electrode below the convex portion.

2. The semiconductor device according to claim 1 , wherein

the cell portion is provided with an IGBT region and a diode region provided adjacently to the IGBT region,

the convex portion is provided above the IGBT region, and

the IGBT region is thinner than the diode region.

3. The semiconductor device according to claim 1 , wherein

the cell portion is provided with an IGBT region and a diode region provided adjacently to the IGBT region,

the convex portion is provided above the diode region, and

the diode region is thinner than the IGBT region.

4. The semiconductor device according to claim 3 , wherein

the substrate is of N-type,

the substrate includes an N-type buffer layer and a P-type collector on a back surface side of the IGBT region, and the buffer layer is provided on a back surface side of the diode region.

5. The semiconductor device according to claim 1 , wherein the convex portion is thinner than the substrate.

6. The semiconductor device according to claim 1 , wherein the substrate is formed of a wide bandgap semiconductor.

7. The semiconductor according to claim 6 , wherein the wide bandgap semiconductor is silicon carbide, gallium nitride based material or diamond.

8. A method of manufacturing a semiconductor device comprising:

a surface step of forming a surface layer on a surface side of a substrate including a cell portion and a terminal portion surrounding the cell portion;

a surface structure step of forming a surface structure having a convex portion protruding upward above the cell portion after executing the surface step;

a step of sticking a protective film so that the protective film covers the surface structure;

a polishing step of polishing a back surface of the substrate while the protective film is stuck;

a back surface step of forming a back surface semiconductor layer on a back surface side of the substrate; and

a step of forming a back surface electrode on a back surface of the back surface semiconductor layer after executing the polishing step,

wherein at least a part of the cell portion is thinner than the terminal portion,

the back surface electrode under the cell portion and the back surface electrode under the terminal portion form a concave shape,

a lower surface of the back surface electrode under the cell portion and a lower surface of the back surface electrode under the terminal portion are smoothly connected to each other,

the convex portion is a part of the surface electrode, and the insulating film directly contacts a portion of the upper portion of the surface electrode below the convex portion.

9. The method of manufacturing a semiconductor device according to claim 8 , wherein

a base, an emitter, and an anode adjacent to the base are formed in the cell portion in the surface step;

the convex portion is formed above the base and the emitter in the surface structure step;

a buffer layer is formed on the substrate, and a collector and a cathode are formed on a back surface of the buffer layer in the back surface step; and

the polishing step is executed prior to the back surface step.

10. The method of manufacturing a semiconductor device according to claim 8 , wherein

a base, an emitter, and an anode adjacent to the base are formed in the cell portion in the surface step;

the convex portion is formed above the anode in the surface structure step;

a buffer layer is formed on the substrate, and a collector is formed on a back surface of the buffer layer in the back surface step; and

the polishing step is executed after the back surface step.

11. The method of manufacturing a semiconductor device according to claim 8 , wherein the convex portion is formed to be thinner than the substrate.

12. The method of manufacturing a semiconductor device according to claim 8 , wherein the substrate is formed of a wide bandgap semiconductor.

13. A semiconductor device comprising:

a substrate including a cell portion and a terminal portion surrounding the cell portion;

a surface structure provided on the substrate; and

a back surface electrode provided on a back surface of the substrate,

wherein the surface structure includes a convex portion protruding upward above the cell portion,

at least a part of the cell portion is thinner than the terminal portion,

the back surface electrode under the cell portion and the back surface electrode under the terminal portion form a concave shape,

a lower surface of the back surface electrode under the cell portion and a lower surface of the back surface electrode under the terminal portion are smoothly connected to each other,

the surface structure includes a surface electrode provided on the substrate,

the convex portion is a part of the surface electrode,

the cell portion is provided with an IGBT region and a diode region provided adjacently to the IGBT region,

the convex portion is provided above the IGBT region, and

the IGBT region is thinner than the diode region.

14. The semiconductor device according to claim 13 , wherein

the surface structure includes an insulating film provided on the surface electrode above the terminal portion, and

a gap is provided between the insulating film and the convex portion.

15. The method of manufacturing a semiconductor device according to claim 12 , wherein the wide bandgap semiconductor is silicon carbide, gallium nitride based material or diamond.

16. A semiconductor device comprising:

a substrate including a cell portion and a terminal portion surrounding the cell portion;

a surface structure provided on the substrate; and

a back surface electrode provided on a back surface of the substrate,

wherein the surface structure includes a convex portion protruding upward above the cell portion,

at least a part of the cell portion is thinner than the terminal portion,

the back surface electrode under the cell portion and the back surface electrode under the terminal portion form a concave shape,

a lower surface of the back surface electrode under the cell portion and a lower surface of the back surface electrode under the terminal portion are smoothly connected to each other,

the surface structure includes a surface electrode provided on the substrate,

the convex portion is a part of the surface electrode,

the cell portion is provided with an IGBT region and a diode region provided adjacently to the IGBT region,

the convex portion is provided above the diode region, and

the diode region is thinner than the IGBT region.

17. The semiconductor device according to claim 16 , wherein

the surface structure includes an insulating film provided on the surface electrode above the terminal portion, and

a gap is provided between the insulating film and the convex portion.

18. A method of manufacturing a semiconductor device comprising: