The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 28, 1999
Filed:
Jun. 26, 1998
Shin-Etsu Handotai Co., Ltd., Tokyo, JP;
Abstract
A method for microscopically smoothing a surface of a wafer made of silicon single crystal having a low resistivity. In the method, a native oxide film grown on a surface of a wafer having polished by an ordinary mirror polishing process is removed at a temperature of less than 100.degree. C. with use of a mixture gas of HF and H.sub.2, and then an organic substance deposited thereon is removed at a temperature of less than 800.degree. C. with use of a mixture gas of HCl and H.sub.2. Re-growth of an oxide film is suppressed in a consistent H.sub.2 atmosphere, during which the wafer is substantially not varied in its surface roughness. Then the wafer is thermally treated in an H.sub.2 gas atmosphere at a temperature of not less than 800.degree. C. and less than 1000.degree. C. A process of etching the silicon single crystal substrate and a process of depositing silicon atoms caused by decomposition of a silane compound generated are competitively carried out to thereby soften the microscopic rough surface of the wafer and to improve a smoothness over the smoothness of the mirror-polished surface. Since all process temperatures are set to be less than 1000.degree. C., vaporization of impurities in the wafer can be suppressed and its low resistivity can be secured.