Silicon carbide substrate, semiconductor device, and methods for manufacturing them

Patent metadata

Field	Value
Publication number	US-9722028-B2
Application number	US-201615229694-A
Country	US
Kind code	B2
Filing date	Aug 5, 2016
Priority date	Apr 2, 2012
Publication date	Aug 1, 2017
Grant date	Aug 1, 2017

Abstract

A silicon carbide substrate has a first main surface, and a second main surface opposite to the first main surface. A region including at least one main surface of the first and second main surfaces is made of single-crystal silicon carbide. In the one main surface, sulfur atoms are present at not less than 60×10 10 atoms/cm 2 and not more than 2000×10 10 atoms/cm 2 , and carbon atoms as an impurity are present at not less than 3 at % and not more than 25 at %. Thereby, a silicon carbide substrate having a stable surface, a semiconductor device using the substrate, and methods for manufacturing them can be provided.

First claim

What is claimed is:

1. A silicon carbide substrate, comprising:
a first main surface; and
a second main surface opposite to said first main surface,
a region including at least one main surface of said first and second main surfaces consisting essentially of single-crystal silicon carbide,
sulfur atoms being present in said one main surface at not less than 120×10 10 atoms/cm 2 and not more than 600×10 10 atoms/cm 2 , and carbon atoms as an impurity being present in said one main surface at not less than 3 atomic percent (at %) and not more than 25 atomic percent (at %).

2. The silicon carbide substrate according to claim 1 , wherein chlorine atoms are present in said one main surface at not more than 3000×10 10 atoms/cm 2 .

3. The silicon carbide substrate according to claim 1 , wherein oxygen atoms are present in said one main surface at not less than 3 atomic percent (at %) and not more than 30 atomic percent (at %).

4. The silicon carbide substrate according to claim 1 , wherein a metal impurity is present in said one main surface at not more than 4000×10 10 atoms/cm 2 .

5. The silicon carbide substrate according to claim 1 , wherein said one main surface has a surface roughness of not more than 0.5 nm when evaluated in Rq.

6. The silicon carbide substrate according to claim 1 , having a diameter of not less than 110 mm.

7. The silicon carbide substrate according to claim 1 , having a diameter of not less than 125 mm and not more than 300 mm.

8. The silicon carbide substrate according to claim 1 , wherein
said single-crystal silicon carbide has a 4H structure, and
said one main surface has an off angle of not less than 0.1° and not more than 10° relative to a {0001} plane of said single-crystal silicon carbide.

9. The silicon carbide substrate according to claim 1 , wherein
said single-crystal silicon carbide has a 4H structure, and
said one main surface has an off angle of not more than 4° relative to a {03-38} plane of said single-crystal silicon carbide.

10. The silicon carbide substrate according to claim 1 , comprising:
a base layer; and
a single-crystal silicon carbide layer formed on said base layer,
wherein said one main surface is a surface of said single-crystal silicon carbide layer on a side opposite to a side facing said base layer.

11. The silicon carbide substrate according to claim 2 , wherein chlorine atoms are present in said one main surface at not more than 1300×10 10 atoms/cm 2 .

12. The silicon carbide substrate according to claim 2 , wherein chlorine atoms are present in said one main surface at not more than 100×10 10 atoms/cm 2 .

13. The silicon carbide substrate according to claim 3 , wherein oxygen atoms are present in said one main surface at not less than 5 atomic percent (at %) and not more than 21 atomic percent (at %).

14. The silicon carbide substrate according to claim 3 , wherein oxygen atoms are present in said one main surface at not less than 9 atomic percent (at %) and not more than 15 atomic percent (at %).

15. The silicon carbide substrate according to claim 4 , wherein a metal impurity is present in said one main surface at not more than 900×10 10 atoms/cm 2 .

16. The silicon carbide substrate according to claim 4 , wherein a metal impurity is present in said one main surface at not more than 80×10 10 atoms/cm 2 .

17. The silicon carbide substrate according to claim 5 , wherein said one main surface has a surface roughness of not more than 0.3 nm when evaluated in Rq.

18. The silicon carbide substrate according to claim 5 , wherein said one main surface has a surface roughness of not more than 0.1 nm when evaluated in Rq.

19. The silicon carbide substrate according to claim 1 , wherein
said single-crystal silicon carbide has a 4H structure, and
said one main surface has an off angle of not less than 0.01° and not more than 5° relative to a {000-1} plane of said single-crystal silicon carbide.

Assignees

• Sumitomo Electric Industries

Inventors

• Ishibashi Keiji

Classifications

• H10P90/129

  by polishing · CPC title

• H10P90/126

  by chemical etching · CPC title

• H10P90/12

  Preparing bulk and homogeneous wafers · CPC title

• H10P90/00

  Preparation of wafers not covered by a single main group of this subclass, e.g. wafer reinforcement · CPC title

• H10P50/00

  Etching of wafers, substrates or parts of devices · CPC title