# US 11,309,438 B2 · Silicon carbide semiconductor device and method of manufacturing silicon carbide semiconductor device

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- Number: US 11,309,438 B2
- Document ID: US11309438B2
- Status: Granted
- Kind: B2
- Application number: 17/108,591
- Filed: 2020-12-01
- Published: 2021-06-10
- Granted: 2022-04-19
- Earliest claimed: 2019-12-10
- Assignees: Fuji Electric Co., Ltd.
- Applicants: Fuji Electric Co., Ltd.
- Inventors: Naoyuki Ohse; Takahito Kojima; Yuichi Hashizume; Takafumi Uchida
- Web page: https://patentgrep.com/patent/US11309438B2

## CPC

- H10D 8/60: Schottky-barrier diodes
- H10D 62/126: {Top-view geometrical layouts of the regions or the junctions}
- H10D 8/051: {of Schottky diodes}
- H10D 62/105: {by having particular doping profiles, shapes or arrangements of PN junctions; by having supplementary regions, e.g. junction termination extension [JTE] (IGFETs having LDD or drain extension regions H10D30/601)}
- H10D 62/106: {having supplementary regions doped oppositely to or in rectifying contact with regions of the semiconductor bodies, e.g. guard rings with PN or Schottky junctions}
- H10D 62/8325: {Silicon carbide}
- H10D 64/0115: {to silicon carbide}
- H10D 64/0123: {to silicon carbide}
- H10D 64/62: Electrodes ohmically coupled to a semiconductor
- H10D 64/64: Electrodes comprising a Schottky barrier to a semiconductor
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A semiconductor device having, in a plan view, a termination region surrounding an active region. The semiconductor device includes a semiconductor substrate containing silicon carbide, a first-conductivity-type region provided in the semiconductor substrate at its first main surface, a plurality of first second-conductivity-type regions selectively formed in the semiconductor substrate at its first main surface, a plurality of silicide films respectively in ohmic contact with the first second-conductivity-type regions, a first electrode that is in contact with the silicide films to form ohmic regions, with the first second-conductivity-type regions to form non-operating regions, and with the first-conductivity-type region to form Schottky regions, a second electrode provided at a second main surface of the semiconductor substrate, and a second second-conductivity-type region provided in the termination region. The ohmic regions, the non-operating regions and the Schottky regions are formed in the active region in a striped pattern. The second second-conductivity-type region connects the ohmic regions and the non-operating regions.

## Claims

### Claim 1

A silicon carbide semiconductor device having, in a plan view thereof, an active region and a termination region surrounding a periphery of the active region, the silicon carbide semiconductor device comprising:
a semiconductor substrate containing silicon carbide and having a first main surface and a second main surface;
a first-conductivity-type region provided in the semiconductor substrate, and exposed at the first main surface of the semiconductor substrate;
a plurality of first second-conductivity-type regions selectively provided in the active region, the first second-conductivity-type regions being formed in the semiconductor substrate at the first main surface thereof and being in contact with the first-conductivity-type region;
a plurality of silicide films respectively in ohmic contact with the plurality of first second-conductivity-type regions;
a first electrode, which is in contact with the plurality of silicide films to form a plurality of ohmic regions, in contact with the plurality of first second-conductivity-type regions to form a plurality of non-operating regions, and in contact with the first-conductivity-type region to form a plurality of Schottky regions;
a second electrode provided at the second main surface of the semiconductor substrate; and
a second second-conductivity-type region provided in the termination region, surrounding the active region, wherein
the ohmic regions, the non-operating regions, and the Schottky regions are formed in the active region and are provided in a striped pattern, and
the second second-conductivity-type region connects the ohmic regions and the non-operating regions in the termination region.

### Claim 2 (depends on 1)

The silicon carbide semiconductor device according to claim 1, wherein
the ohmic regions include a plurality of stripe-shaped regions separate from one another in the active region.

### Claim 3 (depends on 1)

The silicon carbide semiconductor device according to claim 1, wherein
a contact resistance of each ohmic region with a corresponding one of the silicide films and with the first electrode is at most 5.0×10−3 Ωcm2.

### Claim 4 (depends on 1)

The silicon carbide semiconductor device according to claim 1, wherein
a contact resistance of each ohmic region with a corresponding one of the silicide films and with the first electrode is at most 5.0×10−4 Ωcm2.

### Claim 5 (depends on 1)

The silicon carbide semiconductor device according to claim 1, wherein
each of the silicide films contains nickel, silicon, and aluminum.

### Claim 6 (depends on 1)

The silicon carbide semiconductor device according to claim 1, wherein
each of the ohmic regions and the Schottky regions are in contact with one of the non-operating regions.

### Claim 7 (depends on 1)

The silicon carbide semiconductor device according to claim 1, wherein
each of the ohmic regions has a width that is at most 2 μm.

### Claim 8

A method of manufacturing a silicon carbide semiconductor device having, in a plan view thereof, an active region and a termination region surrounding a periphery of the active region, the method comprising:
providing a semiconductor substrate containing silicon carbide, the semiconductor substrate having a first main surface and a second main surface;
forming a first-conductivity-type region in the semiconductor substrate, a surface of the first-conductivity-type region forming the first main surface of the semiconductor substrate;
selectively forming a plurality of first second-conductivity-type regions in the active region, the plurality of first second-conductivity-type regions being formed in the semiconductor substrate at the first main surface thereof, and being in contact with the first-conductivity-type region;
forming a second second-conductivity-type region in the termination region, surrounding the active region;
forming an oxide film on the first main surface of the semiconductor substrate, covering the first-conductivity-type region and the first second-conductivity-type regions;
forming a plurality of openings in the oxide film, to thereby expose the first second-conductivity-type regions, by selectively removing the oxide film;
forming a metal material film in the openings of the oxide film and in contact with first main surface of the semiconductor substrate, by sequentially stacking a first nickel film, an aluminum film, and a metal film having a melting point higher than that of aluminum;
generating a compound layer on the first main surface of the semiconductor substrate through a first heat treatment that causes the metal material film and the semiconductor substrate to react, to thereby form the compound layer by self-alignment in the openings of the oxide film using the oxide film as a mask;
removing an excess part of the metal material film excluding the compound layer;
generating a nickel silicide in the compound layer to form a silicide film in ohmic contact with the semiconductor substrate, by a second heat treatment at a temperature higher than that of the first heat treatment;
forming a contact hole connecting the openings by removing the oxide film in the active region after forming the silicide film;
forming a first electrode on the first main surface of the semiconductor substrate in the contact hole, by sequentially stacking a titanium film and a metal electrode film containing aluminum, the first electrode being in contact with the first-conductivity-type region to form a plurality of Schottky regions, in contact with the silicide film to form a plurality of ohmic regions, and in contact with the first second-conductivity-type regions to form a plurality of non-operating regions; and
forming a second electrode on the second main surface of the semiconductor substrate, wherein
each of the openings is formed to have a width that is smaller than a width of each of the first second-conductivity-type regions, and
the ohmic regions, the non-operating regions, and the Schottky regions are in the active region and are formed in a striped pattern, and
the second second-conductivity-type region is connected to ohmic regions and the non-operating regions in the termination region.