Method of fabricating semiconductor device

• US 7,364,978 B2
• Filed: 04/20/2004
• Issued: 04/29/2008
• Est. Priority Date: 04/25/2003
• Status: Active Grant

• Current Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Original Assignee: Sumitomo Electric Industries Limited (Sumitomo Corporation)
• Inventors: Harada, Shin, Fujikawa, Kazuhiro
• Primary Examiner(s): Le; Thao P.
• Application Number:
  US10/528,440
• Publication Number:
  US 20060063342A1
• Time in Patent Office: 1,470 Days
• Field of Search: 438/369
• US Class Current: 438/369
• CPC Class Codes: H01L 21/046 using ion implantation
• CPC Class Codes: H01L 21/0465 using masks
• CPC Class Codes: H01L 21/266 using masks H01L21/26586 takes precedence

Abstract

There is provided a method of fabricating semiconductor devices that allows ion implantation to be performed at high temperature with ions accelerated with high energy to help to introduce dopant in a semiconductor substrate, in particular a SiC semiconductor substrate, at a selected region to sufficient depth. To achieve this the method includes the steps of: providing the semiconductor substrate at a surface thereof with a mask layer including a polyimide resin film, or a SiO₂ film and a thin metal film; and introducing dopant ions.

Claims

1. A method of fabricating a semiconductor device by employing ion implantation to provide a SiC semiconductor substrate at a surface thereof with a region having dopant introduced therein, comprising the steps of:

providing said semiconductor substrate at least at a first region of a surface thereof with a mask layer including a polyimide resin film; and

implanting dopant ions to an implantation depth into said semiconductor substrate at a second region of said surface of said semiconductor substrate free of said polyimide resin film;

wherein said polyimide resin film has a thickness of at least twice said implantation depth.

2. The method of claim 1, wherein said semiconductor substrate is heated to at least 300°

C., and said dopant ions are implanted.

3. The method of claim 1, wherein said semiconductor substrate is heated to at least 500°

C. and said dopant ions are implanted.

4. The method of claim 1, wherein said polyimide resin film is formed of photosensitive polyimide resin.

5. The method of claim 1, wherein a thin metal film is further interposed between said polyimide resin film and said semiconductor substrate.

6. The method of claim 1, wherein a thin film formed of SiO₂ is further interposed between said polyimide resin film and said semiconductor substrate.

7. The method of claim 1, wherein said mask layer is deposited on said semiconductor substrate at said first region to be undoped with said dopant ions.

8. The method of claim 1, wherein said a dopant ions are implanted into said second region which is not masked by said mask layer.

9. A method of preparing a doped semiconductor substrate, comprising the steps:

a) providing a semiconductor substrate comprising SiC;

b) providing a mask layer including a polyimide resin film that consists of a photosensitive polyimide resin on a first region of a surface of said substrate, by applying said polyimide resin film on said first region and a second region of said surface, then exposing said polyimide resin film to light at said first region, and then removing said polyimide resin film at said second region, wherein said step b) does not involve photolithography employing a photoresist;

c) heating said substrate to at least 300°

C.; and

d) while said substrate is at least 300°

C., implanting, by ion implantation, dopant ions into said substrate through said second region of said surface to form in said substrate a doped region that is doped with said dopant ions;

wherein said method does not involve chemical vapor deposition and does not involve dry etching.

10. The method according to claim 9, further comprising, after said step d), a step of removing said polyimide resin film by wet etching using hydrofluoric acid.

14. The method according to claim 9, wherein said step b) further comprises forming said mask layer to include a metal film interposed between said polyimide resin film and said substrate.

15. The method according to claim 9, wherein said step b) further comprises forming said mask layer to include a SiO₂ film interposed between said polyimide resin film and said substrate.

11. A method of preparing a doped semiconductor substrate, comprising the steps:

a) providing a semiconductor substrate comprising SiC;

b) providing a mask layer including a polyimide resin film on a first region of a surface of said substrate;

c) heating said substrate to at least 300°

C.; and

d) while said substrate is at least 300°

C., implanting, by ion implantation, dopant ions into said substrate through a second region of said surface to form in said substrate a doped region that is doped with said dopant ions;

wherein said polyimide resin film has a thickness of at least twice a depth of said doped region.

12. The method according to claim 11,

wherein said step b) further comprises forming said mask layer to include a metal film interposed between said polyimide resin film and said substrate.

13. The method according to claim 11,

wherein said step b) further comprises forming said mask layer to include a SiO₂ film interposed between said polyimide resin film and said substrate.