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:
Oct. 12, 2010
Filed:
Jan. 23, 2006
Fumitaka Kume, Gunma, JP;
Fumitaka Kume, Gunma, JP;
Shin-Etsu Handotai Co., Ltd., Tokyo, JP;
Abstract
There is provided a preferential etching method wherein a preferential etchant which contains at least a hydrofluoric acid whose composition by volume falls within the range of 0.02 to 0.1, a nitric acid whose composition by volume falls within the range of 0.5 to 0.6, an acetic acid whose composition by volume falls within the range of 0.2 to 0.25, and water is used to etch a silicon single crystal substrate whose electrical resistivity is less than 10 mΩ·cm at a rate higher than 0.1 μm/min, thereby eliciting BMDs on a surface of the silicon single crystal substrate. As a result, the preferential etching method that can evaluate and utilize characteristics of crystal defects, especially BMDs in an ultralow-resistance silicon single crystal substrate whose electrical resistivity is less than 10 mΩ·cm, which cannot be readily detected by conventional techniques, by performing preferential etching using a chromeless etchant containing no harmful chrome can be provided.