Method of producing a thin layer of crystalline material

• US 6,806,171 B1
• Filed: 08/07/2002
• Issued: 10/19/2004
• Est. Priority Date: 08/24/2001
• Status: Expired due to Fees

• Current Assignee: Silicon Wafer Technologies Incorporated
• Original Assignee: Silicon Wafer Technologies Incorporated
• Inventors: Ulyashin, Alexander, Usenko, Alexander
• Primary Examiner(s): FOURSON III, GEORGE R
• Application Number:
  US10/213,593
• Time in Patent Office: 804 Days
• Field of Search: 438/FOR.330, 438/492, 438/466, 438/960, 257/E21.485
• US Class Current: 438/492
• CPC Class Codes: H01L 21/02381 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/0245 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02513 Microstructure
• CPC Class Codes: H01L 21/02532 Silicon, silicon germanium, germanium
• CPC Class Codes: H01L 21/02579 P-type
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02658 Pretreatments cleaning in general H01L21/02041
• CPC Class Codes: H01L 21/76259 with separation/delamination along a porous layer
• CPC Class Codes: Y10S 438/96 Porous semiconductor

Abstract

A technique for forming a film of crystalline material, preferably silicon. The technique creates a sandwich structure with a weakened region at a selected depth underneath the surface. The weakened region is a layer of porous silicon with high porosity. The high porosity enclosed layer is formed by (1) forming a porous silicon layer with low porosity on surface of the substrate, (2) epitaxial growth of a non-porous layer over the low-porous layer (3) increasing of porosity of the low-porous layer making the said layer hi-porous, (4) cleaving the semiconductor substrate at said high porous layer. The porosity of the buried low-porous layer is increased by hydrogenation techniques, for example, by processing in hydrogen plasma. The process is preferentially used to produce silicon-on-insulator wafers.

Claims

1. A method comprising:

forming a porous layer with low porosity on a single crystalline substrate growing the single-crystal layer on the surface of said porous layer then increasing of porosity of the said porous layer by hydrogenation of the substrate in hydrogen plasma

separating said non-porous layer from said substrate by cleaving the wafer along the layer with increased porosity.

2. The method of claim 1 wherein said plasma processing comprises RF hydrogen plasma or DC hydrogen plasma.

3. The method of claim 2 wherein said plasma hydrogenation is performed at hydrogen platelet growth conditions.

4. The method of claim 3 wherein said plasma hydrogenation is performed at temperature 250°

C. or less for a duration of at least 30 minutes.

5. The method of claim 2 wherein said plasma hydrogenation is performed to achieve pore growth conditions.

6. The method of claim 4 wherein said plasma hydrogenation is performed at temperature in a range 250°

C. to 350°

C. during at least 10 minutes.