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. 12, 1995
Filed:
Oct. 13, 1994
Yoshihiro Akashi, Kobe, JP;
Kaoru Kuramochi, Montgomery, OH (US);
Setsuo Okamoto, Nishinomiya, JP;
Yasuji Tsujimoto, Kobe, JP;
Makoto Ito, Saga, JP;
Sumitomo Sitix Corporation, Amagasaki, JP;
Abstract
A process and apparatus for producing silicon single crystals with excellent dielectric strength of gate oxide films by adjusting the temperature gradient of the pulled-up silicon single crystal without loss of its rate of pulling. The process of producing silicon single crystals by pulling up the single crystal from a melt of material of the single crystal imposes a certain average temperature gradient on the grown single crystal while it is still at high temperature. The apparatus is provided with a heating element outside a crucible and pulling shaft with which a single crystal is pulled up from the melt of the material in the crucible. The ratio of length h of the heating element to the inside diameter .phi. of the crucible is adjusted so as to be between 0.2 and 0.8 whereby the temperature gradient can be maintained below 2.5.degree. C./mm.