Method of preventing surface roughening during hydrogen pre-bake of SiGe substrates using chlorine containing gases

• US 20050148162A1
• Filed: 01/02/2004
• Published: 07/07/2005
• Est. Priority Date: 01/02/2004
• Status: Abandoned Application

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Bedell, Stephen W., Chen, Huajie, Sadana, Devendra K., Murphy, Richard J., Mocuta, Dan M.
• Application Number:
  US10/751,207
• Publication Number:
  US 20050148162A1
• Time in Patent Office: Days
• US Class Current: 438/503
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 29/52 Alloys
• CPC Class Codes: H01L 21/02046 Dry cleaning only H01L21/02085 takes precedence
• CPC Class Codes: H01L 21/02052 Wet cleaning only H01L21/02085 takes precedence
• CPC Class Codes: H01L 21/02381 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/0243 Surface structure
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02658 Pretreatments cleaning in general H01L21/02041
• CPC Class Codes: H01L 21/02661 In-situ cleaning

Abstract

The invention forms an epitaxial silicon-containing layer on a silicon germanium, patterned strained silicon, or patterned thin silicon-on-insulator surface and avoids creating a rough surface upon which the epitaxial silicon-containing layer is grown. In order to avoid creating the rough surface, the invention first performs a hydrofluoric acid etching process on the silicon germanium, patterned strained silicon, or patterned thin silicon-on-insulator surface. This etching process removes most of oxide from the surface, and leaves only a sub-monolayer of oxygen (typically 1×10¹³-1×10¹⁵/cm² of oxygen) at the silicon germanium, patterned strained silicon, or patterned thin silicon-on-insulator surface. The invention then performs a hydrogen pre-bake process in a chlorine containing environment which heats the silicon germanium, strained silicon, or thin silicon-on-insulator surface sufficiently to remove the remaining oxygen from the surface. By introducing a small amount of chlorine containing gases, the heating processes avoid changing the roughness of the silicon germanium, patterned strained silicon, or patterned thin silicon-on-insulator surface. Then the process of epitaxially growing the epitaxial silicon-containing layer on the silicon germanium, patterned strained silicon, or patterned silicon-on-insulator surface is performed.

Claims

1. A method of forming an epitaxial silicon-containing layer on a silicon germanium surface, said method comprising:

performing an ex-situ chemical oxide removal process on said silicon germanium surface so as to remove oxygen from said silicon germanium surface, and leave a remaining amount of oxygen at said silicon germanium surface;

heating said silicon germanium surface in a chlorine containing environment to remove said remaining amount of oxygen from said silicon germanium surface; and

epitaxially growing said epitaxial silicon-containing layer on said silicon germanium surface.

2. The method in claim 1, wherein said ex-situ chemical oxide removal and heating processes increase the roughness of said silicon germanium surface by less than 1 Å

RMS.

3. The method in claim 1, wherein said silicon-containing layer comprises one of Si, Si_xGe_1-x, Si_xC_1-x, and Si_xGe_yC_1-x-y.

4. The method in claim 1, wherein said ex-situ chemical oxide removal comprises a hydrofluoric acid etch.

5. The method in claim 4, where said hydrofluoric acid comprises a H₂O:

HF solution with ratio of 10;

1 to 500;

1.

6. The method in claim 1, wherein said chlorine containing environment comprises a mixture of a larger flow of hydrogen with smaller flows of HCl and DCS.

7. The method in claim 6, where the ratio of HCl and DCS is chosen to have a zero etch rate.

8. The method in claim 7, where the ratio of HCl and DCS is chosen to have a positive etch rate.

9. The method in claim 1, wherein said chlorine containing environment comprises a mixture of a larger flow of hydrogen with smaller flow of mixture of HCl with any one or any combination of SiH₄, DCS, SiHCl₃, Si₂H₆, and GeH₄.

10. A method of forming an epitaxial silicon-containing layer on a silicon surface, said method comprising:

performing an ex-situ chemical oxide removal process on said silicon surface so as to remove oxygen from said silicon surface, and leave a remaining amount of oxygen at said silicon surface;

heating said silicon surface in a chlorine containing environment to remove said remaining amount of oxygen from said silicon surface; and

epitaxially growing said epitaxial silicon-containing layer on said silicon surface.

11. The method in claim 10, wherein said silicon surface comprises one of a patterned strained silicon surface and a patterned thin silicon-on-insulator (SOI) surface.

12. The method in claim 10, wherein said ex-situ chemical oxide removal and heating processes increase the roughness of said silicon surface by less than 1 Å

RMS.

13. The method in claim 10, wherein said silicon-containing layer comprises one of Si, Si_xGe_1-x, Si_xC_1-x, and Si_xGe_yC_1-x-y.

14. The method in claim 10, wherein said ex-situ chemical oxide removal comprises a hydrofluoric acid etch.

15. The method in claim 14, where said hydrofluoric acid comprises a H₂O:

HF solution with ratio of 10;

1 to 500;

1.

16. The method in claim 10, wherein said chlorine containing environment comprises a mixture of a larger flow of hydrogen with smaller flows of HCl and DCS.

17. The method in claim 16, where the ratio of HCl and DCS is chosen to have one of a zero etch rate and positive etch rate.

18. The method in claim 10, wherein said chlorine containing environment comprises a mixture of a larger flow of hydrogen with smaller flow of mixture of HCl with any one or any combination of SiH₄, DCS, SiHCl₃, Si₂H₆, and GeH₄.

19. A method of forming an epitaxial silicon-containing layer on a silicon surface, wherein said silicon surface comprises one of a patterned strained silicon surface and a patterned thin silicon-on-insulator (SOI) surface, said method comprising:

performing an ex-situ chemical oxide removal process on said silicon surface so as to remove oxygen from said silicon surface, and leave a remaining amount of oxygen at said silicon surface;

heating said silicon surface in a chlorine containing environment to remove said remaining amount of oxygen from said silicon surface; and

epitaxially growing said epitaxial silicon-containing layer on said silicon surface.