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:
Jan. 16, 2001
Filed:
Mar. 30, 1999
Eiichi Iino, Gunma-ken, JP;
Shin-Etsu Handotai Co., Ltd., Tokyo, JP;
Abstract
In a method for producing a silicon single crystal, a silicon seed crystal having a sharp tip end is prepared, and a part of the silicon seed crystal is melted down from a tip end to a position having a predetermined thickness. This is followed by performing a necking operation to form a tapered necking part and a neck portion, and by subsequently pulling a single crystal ingot after increasing a diameter. The part to be melted down is a part from a tip end to a position in which a thickness is 1.1 to 2 times the diameter of the neck portion to be formed. The necking operation is then performed in such a way that a tapered necking part in the shape of a cone is formed at an early stage thereof by pulling a crystal with gradually decreasing a diameter to a minimum diameter of 5 mm or more, then forming a neck portion. Subsequently, the single crystal ingot is pulled after being increased in diameter. Methods according to the invention enable growing of a single crystal ingot without lowering the rate of success in making the crystal dislocation-free in cases where a thick neck is formed. This improves productivity of heavy silicon single crystals having a large diameter.