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:
May. 10, 2016
Filed:
Mar. 06, 2013
Shinya Iwasaki, Toyota, JP;
Shinya Iwasaki, Toyota, JP;
TOYOTA JIDOSHA KABUSHIKI KAISHA, Toyota, JP;
Abstract
There is provided a method for reducing the nonuniformity of forward voltage Vf of an N-type semiconductor wafer in which density of impurities included in an N-layer is nonuniformly distributed in a plane view of the semiconductor wafer. The method reduces the nonuniformity of forward voltage, by irradiating charged particles to the N-type semiconductor wafer, and generating defects in the N-layer to reduce the nonuniformity of forward voltage. In one aspect of the method, charged particles are irradiated so that a reaching positon in a depth direction or an irradiation density may differ according to the density of impurities in the N-layer in the plane view of the semiconductor wafer.