Method of manufacturing silicon carbide semiconductor device

Patent metadata

Field	Value
Publication number	US-9613809-B2
Application number	US-201414766963-A
Country	US
Kind code	B2
Filing date	Jan 17, 2014
Priority date	Mar 8, 2013
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

A method of manufacturing a silicon carbide semiconductor device includes the following steps. A silicon carbide substrate is prepared. A first mask layer is formed in contact with a first main surface of the silicon carbide substrate. The first mask layer includes a first layer disposed in contact with the first main surface, an etching stop layer disposed in contact with the first layer and made of a material different from that for the first layer, and a second layer disposed in contact with a surface of the etching stop layer opposite to the surface in contact with the first layer. A recess is formed in the first mask layer by etching the second layer and the etching stop layer. A first impurity region is formed in the silicon carbide substrate using the first mask layer with the recess. The first mask layer does not include a metallic element.

First claim

The invention claimed is:

1. A method of manufacturing a silicon carbide semiconductor device, comprising steps of:
preparing a silicon carbide substrate having a first main surface and a second main surface opposite to each other;
forming a first mask layer in contact with said first main surface of said silicon carbide substrate, said first mask layer including a first layer disposed in contact with said first main surface, an etching stop layer disposed in contact with said first layer and made of a material different from that for said first layer, and a second layer disposed in contact with a surface of said etching stop layer opposite to the surface in contact with said first layer;
forming a recess in said first mask layer by etching said second layer and said etching stop layer; and
forming a first impurity region having a first conductivity type in said silicon carbide substrate using said first mask layer with said recess, said first mask layer not including a metallic element, and
further comprising a step of forming a second mask layer on said second main surface of said silicon carbide substrate, said second mask layer not including a metallic element.

2. The method of manufacturing a silicon carbide semiconductor device according to claim 1 , wherein
said second mask layer includes a third layer disposed in contact with said second main surface and made of a same material as that for said first layer, a fourth layer disposed in contact with said third layer and made of a same material as that for said etching stop layer, and a fifth layer disposed in contact with a surface of said fourth layer opposite to the surface in contact with said third layer and made of a same material as that for said second layer.

3. The method of manufacturing a silicon carbide semiconductor device according to claim 1 , wherein
said first layer, said etching stop layer and said second layer are formed without generation of plasma.

4. The method of manufacturing a silicon carbide semiconductor device according to claim 3 , wherein
said etching stop layer and said second layer are formed by thermal chemical vapor deposition.

5. The method of manufacturing a silicon carbide semiconductor device according to claim 4 , wherein
said etching stop layer and said second layer are formed by low-pressure thermal chemical vapor deposition.

6. The method of manufacturing a silicon carbide semiconductor device according to claim 3 , wherein
said first layer is formed either by a method of thermally oxidizing said first main surface or by low-pressure chemical vapor deposition.

7. The method of manufacturing a silicon carbide semiconductor device according to claim 1 , wherein
said first layer is made of either silicon dioxide or silicon nitride.

8. The method of manufacturing a silicon carbide semiconductor device according to claim 1 , wherein
said second layer is made of either silicon dioxide or silicon nitride.

9. The method of manufacturing a silicon carbide semiconductor device according to claim 1 , wherein
said etching stop layer is made of polysilicon.

10. The method of manufacturing a silicon carbide semiconductor device according to claim 1 , further comprising steps of:
after said step of forming a first impurity region, removing said first mask layer; and
after said step of removing said first mask layer, performing activation annealing on said silicon carbide substrate.

11. The method of manufacturing a silicon carbide semiconductor device according to claim 1 , further comprising steps of:
after said step of forming a first impurity region, forming, in said recess, a third mask layer with an opening having a width smaller than said recess; and
forming a second impurity region having a second conductivity type different from said first conductivity type in said first impurity region using said third mask layer.

12. The method of manufacturing a silicon carbide semiconductor device according to claim 1 , further comprising steps of:
after said step of forming a first impurity region, forming a fourth mask layer in contact with said first layer; and
forming a guard ring region having said first conductivity type in said silicon carbide substrate using said fourth mask layer, with said first layer remaining in contact with said first main surface.

Assignees

• Sumitomo Electric Industries

Inventors

• Horii Taku
• Kijima Masaki

Classifications

• H10P95/90

  Thermal treatments, e.g. annealing or sintering · CPC title

• H10P76/405

  characterised by their composition, e.g. multilayer masks · CPC title

• H10P50/73

  using masks for insulating materials · CPC title

• H10P30/2042

  into crystalline silicon carbide · CPC title

• H10P30/22

  using masks · CPC title