Silicon carbide semiconductor device and manufacturing method therefor

Patent metadata

Field	Value
Publication number	US-9773874-B2
Application number	US-201314418730-A
Country	US
Kind code	B2
Filing date	Jul 25, 2013
Priority date	Aug 1, 2012
Publication date	Sep 26, 2017
Grant date	Sep 26, 2017

Abstract

A silicon carbide semiconductor device includes trenches formed in a lattice shape on the surface of a silicon carbide substrate on which a semiconductor layer is formed, and gate electrodes formed inside of the trenches via a gate insulating film. The depth of the trenches is smaller in a portion where the trenches are crossingly formed than in a portion where the trenches are formed in parallel to each other. Consequently, the silicon carbide semiconductor device is obtained that increases a withstand voltage between the gate electrodes and corresponding drain electrodes on the semiconductor device rear surface to prevent dielectric breakdown and, at the same time, has a large area of the gate electrodes, high channel density per unit area, and low ON resistance.

First claim

The invention claimed is:

1. A silicon carbide semiconductor device comprising:
trenches formed in a lattice shape on a surface of a silicon carbide substrate on which a semiconductor layer is formed;
an insulating film formed inside of the trenches; and
gate electrodes formed inside of the trenches via the insulating film, wherein
the gate electrodes formed inside of the trenches are connected in a lattice form within the trenches,
in the silicon carbide substrate, a plurality of electric contact regions, which are formed in a distributed manner in a region different from the region in which the gate electrodes are formed, are provided for inputting signals to the gate electrodes,
a depth of the trenches in a portion where the trenches are crossingly formed is smaller than a depth of the trenches in a portion where the trenches are formed in parallel to each other,
bottoms of the trenches in the portion where the trenches are formed in parallel to each other are continuously connected to adjacent bottoms of trenches by inclined faces in the portion where the trenches are crossingly formed.

2. The silicon carbide semiconductor device according to claim 1 , wherein the depth of the portion where the trenches are crossingly formed is in a range between 40% or larger and 80% or smaller of the depth of the portion where the trenches are formed in parallel to each other.

3. The silicon carbide semiconductor device according to claim 1 , wherein an aspect ratio, which is a value obtained by dividing the depth of the trenches in the portion where the trenches are crossingly formed by a width of the trenches in the portion where the trenches are crossingly formed, is in a range between 0.1 or larger and 1 or smaller.

4. The silicon carbide semiconductor device according to claim 1 , wherein a width of the trenches in the portion where the trenches are crossingly formed is larger than a width of the trenches in the portion where the trenches are formed in parallel to each other.

5. The silicon carbide semiconductor device according to claim 4 , wherein, in all extending directions of the crossing trenches, the width of the trenches in the portion where the trenches are crossingly formed is equal to or smaller than a value obtained by adding 20% of a repetition pitch of the trenches to the width of the trenches in the portion where the trenches are formed in parallel to each other.

6. The silicon carbide semiconductor device according to claim 1 , wherein
the silicon carbide substrate has a structure in which a p-type semiconductor layer is formed on an n-type semiconductor layer, and
the bottom surface of the trenches in the portion where the trenches are crossingly formed is the p-type semiconductor layer.

Assignees

• Mitsubishi Electric Corp

Inventors

• Fujiwara Nobuo
• Kagawa Yasuhiro
• Tanaka Rina
• Fukui Yutaka

Classifications

• H10P30/2042

  into crystalline silicon carbide · CPC title

• H10P30/21

  of electrically active species · CPC title

• H10D64/01366

  the semiconductor being silicon carbide · CPC title

• H10P50/691

  for Group V materials or Group III-V materials · CPC title

• H10P50/242

  of Group IV materials · CPC title