Patent Number: 8,871,109

Title: Method for preparing a donor surface for reuse

Abstract: A donor wafer, for example of silicon, has an irregular surface following cleaving of a lamina from the surface, for example by exfoliation following implant of hydrogen and/or helium ions to define a cleave plane. Pinholes in the lamina leave column asperities at the exfoliated surface of the donor wafer, and the beveled edge may leave an edge asperity which fails to exfoliate. To prepare the surface of the donor wafer for reuse, mechanical grinding removes the column and edge asperities, and minimal additional thickness. Following cleaning, growth and removal of an oxide layer at the surface rounds remaining peaks. The smoothed surface is well adapted to bonding to a receiver element and exfoliation of a new lamina. A variety of devices may be fabricated from the lamina, for example a photovoltaic cell.

Inventors: Prabhu; Gopal (San Jose, CA), Jackson; Kathy J. (Felton, CA), Leland; Orion (Fremont, CA), Agarwal; Aditya (Sunnyvale, CA)

Assignee: GTAT Corporation

International Classification: C03C 15/00 (20060101); H01L 21/461 (20060101); H01L 21/302 (20060101); C03C 25/68 (20060101)

Expiration Date: 2018-10-28 0:00:00