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:
Nov. 19, 1991
Filed:
Jul. 23, 1990
Hiroshi Kaneta, Kawasaki, JP;
Shuichi Muraishi, Tokyo, JP;
Fujitsu Limited, Kawasaki, JP;
Jeol, Ltd., Tokyo, JP;
Abstract
A silicon crystal evaluation method includes the step of measuring, at room temperature, an intensity of an oxygen impurity infrared absorption peak of each of a plurality of silicon crystals at a wavenumber of 1107.+-.3cm.sup.-1, Each of the silicon crystals contains oxygen impurities, the silicon crystals including an evaluated silicon crystal having an unknown thermal history and reference silicon crystals having respective known thermal histories. The second step is to measure, at a temperature equal to or lower than 10K, an intensity of an oxygen impurity infrared absorption peak of each of the silicon crystals at a predetermined wavenumber. A third step is to calculate a first peak intensity ratio between the intensity of the oxygen impurity infrared absorption peak of each of the silicon crystals at 1107.+-.cm.sup.-1 and the intensity of the oxygen impurity infrared absorption peak at the predetermined wavenumber. The fourth step is to calculate a first difference between the first peak intensity ratio of the evaluated silicon crystal and a corresponding, second peak intensity ratio obtained when all oxygen impurities are isolated point lattice defects. The fifth step is to calculate a second difference between the first peak intensity ratio of each of the reference silicon crystals and the second peak intensity ratio. The sixth step is to evaluate the unknown thermal history of the evaluated silicon crystal from reference data which defines a relationship between the second difference and the known thermal histories.