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:
Apr. 28, 1998
Filed:
Mar. 22, 1996
Hiroshi Shirai, Kanagawa, JP;
Jun Yoshikawa, Kanagawa, JP;
Youji Ogawa, Niigata, JP;
Kazuhiko Kashima, Kanagawa, JP;
Kazuya Ookubo, Kanagawa, JP;
Yukari Kohtari, Niigata, JP;
Norihiro Shimoi, Niigata, JP;
Masayuki Sanada, Niigata, JP;
Shuji Tobashi, Kanagawa, JP;
Toshiba Ceramics Co., Ltd., Tokyo, JP;
Abstract
A silicon wafer is mirror-polished until obtaining surface roughness Ra of 0.70-1.00 nm, Rq of 0.80-1.10 nm, or Rt of 4.50-7.00 nm. The resulting wafer is heat-treated at a temperature not lower than 1,200.degree. C. for 30 minutes to 4 hours in a hydrogen gas atmosphere. According to another aspect, a silicon wafer is mirror-polished until obtaining surface roughness values Ra' of 0.08-0.70 nm, rms of 0.10-0.90 nm, and P-V of 0.80-5.80 nm in a square area of 90 .mu.m by 90 .mu.m, and surface roughness values Ra' of 0.13-0.40 nm, rms of 0.18-0.50 nm, and P-V of 1.30-2.50 nm in a square area of 500 nm by 500 nm. The resulting wafer is heat-treated at 1,100.degree.-1,300.degree. C. for 30 minutes to 4 hours in a hydrogen gas atmosphere.