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:
Aug. 24, 1999
Filed:
Dec. 29, 1997
Hisami Motoura, Kanagawa, JP;
Kouichirou Hayashida, Kanagawa, JP;
Komatsu Electronics Metals Co., Ltd., Kanagawa, JP;
Abstract
The method of evaluating silicon wafers according to this invention is capable of predicating degradation of the quality of oxide film insulation, which is incurred, on the silicon wafers, by process faults or local residual strains undetectable by the naked eye. The method includes the following steps of: removing selectively a surface of a silicon wafer treated by mirror polishing by using an etching selectivity caused by an unordinary surface state; counting the number of etch pits on the surface of the silicon wafer with the aid of an optical microscope; and judging the quality of the silicon wafer based on the etch pit density, which is calculated from the above number of etch pits, and the threshold value of etch pit density. The threshold value of etch pit density of the silicon wafer treated by selective etching is set to be below 5.times.10.sup.5 pits/cm.sup.2, and improvements to the processing of production lines relating to low-quality silicon wafers can be made.