Planarizing technique for multilayered substrates

• US 6,103,599 A
• Filed: 06/03/1998
• Issued: 08/15/2000
• Est. Priority Date: 07/25/1997
• Status: Expired due to Term

• Current Assignee: Silicon Genesis
• Original Assignee: Silicon Genesis
• Inventors: Cheung, Nathan, Henley, Francois J.
• Primary Examiner(s): Mulpuri, Savitri
• Application Number:
  US09/089,931
• Time in Patent Office: 804 Days
• Field of Search: 438/528, 438/459, 438/974, 438/977, 438/766, 438/770, 438/697, 438/745, 438/756, 438/723, 438/513, 438/455, 438/458, 438/406, 438/4, 438/694
• US Class Current: 438/459
• CPC Class Codes: H01L 21/30604 Chemical etching
• CPC Class Codes: H01L 21/76254 with separation/delamination along an ion implanted layer, e.g. Smart-cut, Unibond
• CPC Class Codes: Y10S 438/977 Thinning or removal of substrate

Abstract

The present invention provides a multilayered wafer 10 such as an SOI wafer having a novel implanted layer. This implanted layer is removable and provides a resulting wafer having a substantially uniform surface. The wafer includes a bulk substrate 11 and an insulating layer 13 formed overlying the bulk substrate 15. A film of semiconductor material is formed overlying the insulating layer. Surface non-uniformities are formed overlying and in the film of semiconductor material. The non-uniformities are implanted, and are bordered by a substantially uniform interface 17 at a selected depth underlying the surface non-uniformities. The substantially uniform interface provides a substantially uniform resulting surface for the SOI wafer.

Claims

1. A method for fabricating a substrate, said method comprising steps of:

providing a substrate comprising a thickness of material having a non-uniform surface, said thickness of material being implant damaged and having a substantially planar interface region at a selected depth underying said non-uniform surface;

converting said implant damaged thickness of material that is at a lower density up to said substantially planar interface region into an insulating material; and

selectively removing said insulating material from said substrate using at least an etching process to expose said substantially uniform interface region to provide a substantially uniform surface;

wherein said separation process is provided by a Smart Cut™

process or controlled cleaving process.

2. The method of claim 1 wherein said implant damaged thickness of material has a lower density than said substrate.

3. The method of claim 1 wherein said insulating material is an oxide material.

4. The method of claim 1 wherein said step of converting is an oxidation step.

5. The method of claim 4 wherein said converting step converts said implant damaged thickness of material into an oxide material.

6. The method of claim 1 wherein said implant damaged thickness of material is made using a process selected from beam ion implantation, PIII, or separation.

7. The method of claim 1 wherein said implant damaged thickness of material is made by way of implantation.

8. The method of claim 1 wherein said non-uniform surface is made by a cut process.

9. The method of claim 1 wherein said etching process is a selective plasma etching process.

10. The method of claim 1 wherein said etching process is a wet etching process.

11. The method of claim 10 wherein said wet etching process is a hydrofluoric acid dip.

12. The method of claim 1 wherein said substrate is a silicon wafer.

13. The method of claim 12 wherein said converting step decomposes said implant damaged thickness of material into an oxide layer, said oxide layer having said substantially uniform interface region to single crystalline silicon.

14. The method of claim 1 wherein said converting step also removes a possible impurity from said substrate, said impurity being trapped in said implant damaged thickness of material.

15. A method for planarizing a surface of a silicon-on-insulator semiconductor substrate, said method comprising steps of:

providing a semconductor substrate, said semiconductor substrate comprising a semiconductor material over a substrate material with an insulating layer sandwiched in between;

forming a thickness of material having implant damage that is at a lower density therein and surface non-uniformities thereon in said semiconductor material;

converting said thickness of material into an insulating material; and

selectively removing said insulating material from said semiconductor material to provide a substantially uniform surface, said selective removing comprising an etching process;

wherein said separation is provided by a Smart Cut.sup.™

process or a controlled cleaving process.

16. The method of claim 15 wherein said thickness of material has a lower density relative to said semiconductor material.

17. The method of claim 15 wherein said insulating material is an oxide material.

18. The method of claim 15 wherein said step of converting is an oxidation step.

19. The method of claim 18 wherein said converting step changes said thickness of material into an oxide layer.

20. The method of claim 15 wherein said thickness of material is made using a process selected from ion implantation or separation of said semiconductor material.

21. The method of claim 15 wherein said thickness of material is implant damaged.

22. The method of claim 15 wherein said surface non-uniformities are surface roughness provided by a cut process.

23. The method of claim 15 wherein said etching process is a selective plasma etching process.

24. The method of claim 15 wherein said etching process is a wet etching process.

25. The method of claim 24 wherein said wet etching process is a hydrofluoric acid dip.

26. The method of claim 15 wherein said bulk substrate is a silicon wafer.

27. The method of claim 26 wherein said converting step decomposes said thickness of material into an oxide layer, said oxide layer having a substantially uniform interface to single crystalline silicon in said semiconductor material.

28. The method of claim 15 wherein said converting step also removes a possible impurity from said semiconductor material, said impurity being trapped in said thickness of material.