Process of fabricating a semiconductor substrate

• US 5,405,802 A
• Filed: 05/25/1994
• Issued: 04/11/1995
• Est. Priority Date: 01/31/1992
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Yonehara, Takao, Yamagata, Kenji
• Primary Examiner(s): Breneman, R. Bruce
• Assistant Examiner(s): Paladugu, Ramamohan Rao
• Application Number:
  US08/249,067
• Time in Patent Office: 321 Days
• Field of Search: 437/71, 437/83, 437/84, 437/86, 437/974, 148/DIG. 135, 148/DIG. 150, 148/33.5
• US Class Current: 438/459
• CPC Class Codes: H01L 21/30604 Chemical etching
• CPC Class Codes: H01L 21/76251 using bonding techniques
• CPC Class Codes: H01L 21/76256 using silicon etch back techniques, e.g. BESOI, ELTRAN
• CPC Class Codes: H01L 2221/68363 used in a transfer process involving transfer directly from an origin substrate to a target substrate without use of an intermediate handle substrate
• CPC Class Codes: Y10S 438/96 Porous semiconductor
• CPC Class Codes: Y10S 438/977 Thinning or removal of substrate
• CPC Class Codes: Y10T 428/249953 Composite having voids in a component [e.g., porous, cellular, etc.]
• CPC Class Codes: Y10T 428/249967 Inorganic matrix in void-containing component

Abstract

A process for preparing a semiconductor substrate comprises a step of porousifying a silicon monocrystalline substrate to form a porous layer, a step of making a silicon monocrystalline thin film to epitaxially grow on a surface of the porous layer, a step of oxidizing the surface of the epitaxial growth layer, a step of forming a deposited film on the oxidized surface, thereby obtainig a first substrate, a step of closely contacting the deposited film of the first substrate to a second substrate, a step of heat treating the closely contacted substrates and a step of selectively etching the porous layer.

Claims

1. A process for preparing a semiconductor substrate, which comprises a step of porousifying a silicon monocrystalline substrate to form a porous layer, a step of making a silicon monocrystalline thin film to epitaxially grow on a surface of the porous layer, a step of oxidizing the surface of the epitaxial growth layer, a step of forming a deposited film on the oxidized surface, thereby obtaining a first substrate, a step of closely contacting the deposited film of the first substrate to a second substrate, a step of heat treating the closely contacted substrates and a step of selectively etching the porous layer.

2. A process according to claim 1, wherein the deposited film is a film containing silicon atoms.

3. A process according to claim 2, wherein the deposited film is selected from a polycrystalline silicon film, an amorphous silicon film, a silicon oxide film and a silicon nitride film.

4. A process according to claim 1, where the deposited film is formed by CVD.

5. A process according to claim 1, wherein the deposited film has a thickness of 2 μ

m or more.

6. A process according to claim 5, wherein the deposited film has a thickness of 10 μ

m or more.

7. A process according to claim 1, wherein the heat treatment is carried out at 800°

C. or more.

8. A process according to claim 1, wherein the oxide film obtained by oxidizing the surface of the epitaxial layer has a thickness of 0.5 μ

m to 1.0 μ

m.

9. A process according to claim 1, wherein the second substrates is a transparent substrate.

10. The process according to claim 1, including conducting the step of porousifying by anodization.

11. The process according to claim 9, wherein the second substrate comprises quartz.

12. The process according to claim 1, wherein the second substrate comprises silicon.