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. 16, 2003
Filed:
Sep. 22, 2000
Etsuro Morita, Tokyo, JP;
Takaaki Shiota, Tokyo, JP;
Yoshihisa Nonogaki, Tokyo, JP;
Yoshinobu Nakada, Tokyo, JP;
Hisashi Furuya, Tokyo, JP;
Hiroshi Koya, Tokyo, JP;
Jun Furukawa, Saitama, JP;
Hideo Tanaka, Saitama, JP;
Yuji Nakata, Saitama, JP;
Mitsubishi Materials Silicon Corporation, Tokyo, JP;
Abstract
An ingot is manufactured by pulling it up such that V/Ga and V/Gb become 0.23 to 0.50 mm /minute ° C., respectively, where V (mm/minute) is a pulling-up speed, and Ga (° C./mm) is and axial temperature gradient at the center of the ingot and Gb (° C./mm) is an axial temperature gradient at the edge of the ingot at temperatures in a range of 1,300° C. to a melting pointy of silicon. A wafer obtained by slicing the ingot is heat treated in a reductive atmosphere at temperature in a renge of 1,050° C. to 1,220° C. for 30 to 150 minutes. A silicon wafer free of OSF's, free of COP's, and substantially free of contamination such as Fe and of occurence of slip, is obtained.