Silicon carbide semiconductor device and method of manufacturing silicon carbide semiconductor device

Patent metadata

Field	Value
Publication number	US-2021074863-A1
Application number	US-202016942201-A
Country	US
Kind code	A1
Filing date	Jul 29, 2020
Priority date	Sep 6, 2019
Publication date	Mar 11, 2021
Grant date	—

Abstract

A semiconductor device including a silicon carbide semiconductor substrate having a first-conductivity-type region at its first main surface. The semiconductor device has, at the first main surface, a plurality of first second-conductivity-type regions and a second second-conductivity-type region selectively provided in the first-conductivity-type region, respectively in an active region and a connecting region of the semiconductor device, and an oxide film provided in a termination region of the semiconductor device and having an inner end that faces the active region. A first silicide film is in ohmic contact with the first second-conductivity-type regions. A second silicide film is in contact with the inner end of the oxide film and in ohmic contact with the second second-conductivity-type region. The semiconductor device has a first electrode including a titanium film and a metal electrode film stacked sequentially on the first main surface, and a second electrode provided at a second main surface.

First claim

What is claimed is:

1 . A method of manufacturing a silicon carbide semiconductor device that includes an active region, and a termination region that includes a connecting region surrounding a periphery of the active region, the method comprising:
providing a semiconductor substrate having a first main surface and a second main surface, the semiconductor substrate containing silicon carbide, and including a first-conductivity-type region of which a main surface is the first main surface of the semiconductor substrate, the first-conductivity-type region having a first region in the active region and a second region spanning an entire area of the connecting region; selectively forming a plurality of first second-conductivity-type regions in the first region of the first-conductivity-type region at the first main surface of the semiconductor substrate; forming a second second-conductivity-type region in the second region of the first-conductivity-type region at the first main surface of the semiconductor substrate; forming an oxide film at the first main surface of the semiconductor substrate, to cover the first-conductivity-type region, the plurality of first second-conductivity-type regions, and the second second-conductivity-type region; selectively removing the oxide film, to thereby form a plurality of first openings that expose the plurality of first second-conductivity-type regions, and form a second opening that exposes the second second-conductivity-type region in the connecting region; sequentially forming and stacking a metal film containing aluminum and a nickel film in the plurality of first openings and the second opening, to thereby form a metal material film; generating a compound layer in the plurality of first openings and the second opening of the oxide film, through self-alignment using the oxide film as a mask, the compound layer being generated by a first heat treatment causing the metal material film and the semiconductor substrate to react with each other; removing an excess part of the metal material film after generating the compound layer, the excess part excluding the compound layer; forming a nickel silicide film in ohmic contact with the semiconductor substrate, by generating nickel silicide in the compound layer through a second heat treatment after removing the excess part, the second heat treatment being performed at a temperature higher than a temperature of the first heat treatment; forming a contact hole that connects the plurality of first openings and the second opening with one another, the contact hole being formed by removing parts of the oxide film in the active region, after forming the nickel silicide film; forming, in the contact hole, a first electrode in which
a titanium film that is in contact with the first-conductivity-type region and forms a Schottky junction with the first-conductivity-type region, and
a metal electrode film that contains aluminum are sequentially stacked; and
forming a second electrode at the second main surface of the semiconductor substrate.

2 . The method according to claim 1 , wherein
the plurality of first openings and the second opening are formed by selectively removing the oxide film by dry etching.

3 . The method according to claim 1 , wherein
the metal film is an aluminum film.

4 . The method according to claim 3 , wherein
the temperature of the first heat treatment is in a range from 400 degrees C. to 550 degrees C.

5 . The method according to claim 1 , wherein
the metal film is an aluminum-silicon film.

6 . The method according to claim 5 , wherein
the temperature of the first heat treatment is in a range from 400 degrees C. to 800 degrees C.

7 . The method according to claim 5 , wherein
the aluminum-silicon film has a thickness in a range from 5 nm to 300 nm.

8 . The method according to claim 5 , wherein
the aluminum-silicon film has a silicon concentration in a range from 0.1 wt % to 3 wt %.

9 . The method according to claim 1 , wherein
the temperature of the second heat treatment is in a range from 900 degrees C. to 1050 degrees C.

10 . The method according to claim 1 , wherein
forming the contact hole includes:
forming a resist mask that covers an outer peripheral part of the oxide film, from one of sidewalls of the second opening that is furthest from the active region, and
removing the parts of the oxide film in the active region through wet etching using the resist mask as a mask.

11 . A silicon carbide semiconductor device having an active region and a termination region that includes a connecting region surrounding a periphery of the active region, the silicon carbide semiconductor device comprising:
a semiconductor substrate having a first main surface and a second main surface, the semiconductor substrate containing silicon carbide, and including a first-conductivity-type region of which a main surface is the first main surface of the semiconductor substrate; a plurality of first second-conductivity-type regions selectively provided in the first-conductivity-type region in the active region, at the first main surface of the semiconductor substrate, the plurality of first second-conductivity-type regions being in contact with the first-conductivity-type region; a second second-conductivity-type region provided in the first-conductivity-type region to have an entire area of the connecting region, at the first main surface of the semiconductor substrate, the second second-conductivity-type region being in contact with the first-conductivity-type region; an oxide film provided on the first main surface of the semiconductor substrate in the termination region, the oxide film having an inner end that faces the active region, the connecting region being between the active region and the oxide film; a first silicide film in ohmic contact with the plurality of first second-conductivity-type regions; a second silicide film in contact with the inner end of the oxide film and in ohmic contact with the second second-conductivity-type region; a first electrode in which a titanium film and a metal electrode film containing aluminum are stacked sequentially on the first main surface of the semiconductor substrate, the titanium film being in contact with and forming a Schottky junction with the first-conductivity-type region, and being in contact with and connected to the first silicide film and the second silicide film; and a second electrode provided at the second main surface of the semiconductor substrate.

12 . The silicon carbide semiconductor device according to claim 11 , wherein
the first silicide film contains nickel, silicon, and aluminum.

13 . The silicon carbide semiconductor device according to claim 12 , wherein
the first silicide film contains carbon.

14 . The silicon carbide semiconductor device according to claim 11 , wherein
the second silicide film contains nickel, silicon, and aluminum.

15 . The silicon carbide semiconductor device according to claim 14 , wherein
the second silicide film contains carbon.

Assignees

• Fuji Electric Co Ltd

Inventors

• Ohse Naoyuki
• Kojima Takahito

Classifications

• H10P30/2042

  into crystalline silicon carbide · CPC title

• H10P30/21

  of electrically active species · CPC title

• H10D64/0123

  to silicon carbide · CPC title

• H10D64/0115

  to silicon carbide · CPC title

• H10W10/031

  of isolation regions comprising PN junctions · CPC title