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. 07, 1999
Filed:
Jan. 22, 1998
Komatsu Electronic Metals Co., Ltd., Kanagawa, JP;
Abstract
An apparatus and a method for fabricating a single-crystal semiconductor by means of CZ method are provided for improving the quality control through the modification of thermal cycle of a pulled single-crystal semiconductor. The apparatus includes a ring after heater which is capable of elevation. The method decreases a temperature gradient to smaller than 20.degree. C./cm, and preferably under 15.degree. C./cm, when the pulled single-crystal semiconductor is cooled from 1200.degree. C. to 1000.degree. C. The after heater therefore heats the single-crystal semiconductor where there is a temperature of 100-300.degree. C. lower than the range of 1200-1000.degree. C. A thermal shelter is provided to retain a temperature gradient of larger than 20.degree. C./cm when the single-crystal semiconductor is within the temperature range between the melting point and 1250.degree. C. The after heater and the shelter can be raised to an upper portion when polysilicon blocks are charged and a twisting step is carried out.