# US 10,374,050 B2 · Silicon carbide semiconductor device and manufacturing method of silicon carbide semiconductor device

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- Number: US 10,374,050 B2
- Document ID: US10374050B2
- Status: Granted
- Kind: B2
- Application number: 14/960,293
- Filed: 2015-12-04
- Published: 2016-03-24
- Granted: 2019-08-06
- Earliest claimed: 2013-11-22
- Assignees: Fuji Electric Co., Ltd.
- Applicants: Fuji Electric Co., Ltd.
- Inventors: Fumikazu Imai; Tsunehiro Nakajima
- Web page: https://patentgrep.com/patent/US10374050B2

## CPC

- H10D 64/62: Electrodes ohmically coupled to a semiconductor
- C23C 14/185: {by cathodic sputtering}
- H10D 62/8325: {Silicon carbide}
- H10D 64/0115: {to silicon carbide}
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)

## Abstract

A titanium layer and a nickel layer are sequentially formed on a back surface of a SiC wafer. Next, by high-temperature heat treatment, the SiC wafer is heated and the titanium layer and the nickel layer are sintered forming a nickel silicide layer that includes titanium carbide. By this high-temperature heat treatment, an ohmic contact of the SiC wafer and the nickel silicide layer is formed. Thereafter, on the nickel silicide layer, a back surface electrode multilayered structure is formed by sequentially stacking a titanium layer, a nickel layer, and a gold layer. Here, in forming the nickel layer that configures a back surface electrode multilayered structure, the nickel layer is formed under a condition that satisfies 0.0<y<−0.0013x+2.0, where the thickness of the nickel layer is x [nm] and the deposition rate of the nickel layer is y [nm/second]. Thus, peeling of the back surface electrode can be suppressed.

## Claims

### Claim 1

A silicon carbide semiconductor device comprising:
a metal layer disposed on a semiconductor substrate of silicon carbide and forming an ohmic contact with the semiconductor substrate, the metal layer being a nickel silicide layer that has titanium carbide distributed therein; and
a metal electrode multilayered structure formed by sequentially stacking at least a titanium layer and a nickel layer on the metal layer,
wherein residual stress of the nickel layer is 200 MPa or less, and
wherein a thickness of the nickel layer is 400-1200 nm.

### Claim 2 (depends on 1)

The silicon carbide semiconductor device according to claim 1, wherein
the residual stress of the nickel layer is 100 MPa or less.

### Claim 3 (depends on 1)

The silicon carbide semiconductor device according to claim 1, wherein
the nickel layer is formed under a condition satisfying 0.0<y<−0.0013x+2.0, where thickness of the nickel layer is x [nm] and deposition rate of the nickel layer is y [nm/second].

### Claim 4 (depends on 3)

The silicon carbide semiconductor device according to claim 3, wherein the nickel layer is formed to under a condition satisfying 0.0<y<−0.0015x+1.2.

### Claim 5

A manufacturing method of a silicon carbide semiconductor device, the manufacturing method comprising:
forming a metal layer on a semiconductor substrate of silicon carbide, the metal layer being a nickel silicide layer that has titanium carbide distributed therein;
forming an ohmic contact of the semiconductor substrate and the metal layer by heat treatment; and
forming a metal electrode multilayered structure by sequentially stacking at least a titanium layer and a nickel layer on the metal layer, wherein
the forming of the metal electrode multilayered structure includes forming the nickel layer under a condition satisfying 0.0<y<−0.0013x+2.0, where thickness of the nickel layer is x [nm] and deposition rate of the nickel layer is y [nm/second], and
wherein a thickness of the nickel layer is 400-1200 nm.

### Claim 6 (depends on 5)

The manufacturing method of the silicon carbide semiconductor device according to claim 5, wherein
the forming of the metal electrode multilayered structure includes forming the nickel layer under a condition satisfying 0.0<y<−0.0015x+1.2.

### Claim 7 (depends on 5)

The manufacturing method of the silicon carbide semiconductor device according to claim 5, wherein
the forming of the metal electrode multilayered structure includes forming the nickel layer by a vapor-deposition method.

### Claim 8 (depends on 5)

The manufacturing method of the silicon carbide semiconductor device according to claim 5, wherein
the forming of the metal layer includes forming on the semiconductor substrate, the metal layer, which includes titanium and nickel, and
the forming of the ohmic contact includes reacting the semiconductor substrate and the metal layer by heat treatment, forming a nickel silicide layer that includes titanium carbide, and forming an ohmic contact of the semiconductor substrate and the nickel silicide layer.

### Claim 9 (depends on 1)

The silicon carbide semiconductor device of claim 1, wherein the thickness of the nickel layer is 400-500 nm.

### Claim 10 (depends on 1)

The silicon carbide semiconductor device of claim 1, wherein the thickness of the nickel layer is 400 nm and the deposition rate of the nickel layer is 0.5 nm/second or less.