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:
Sep. 16, 2014
Filed:
Dec. 05, 2011
Katsuhiko Nakai, Yamaguchi, JP;
Masamichi Ohkubo, Burghausen, DE;
Katsuhiko Nakai, Yamaguchi, JP;
Masamichi Ohkubo, Burghausen, DE;
Siltronic AG, Munich, DE;
Abstract
Annealed wafers having reduced residual voids after annealing and reduced deterioration of TDDB characteristics of an oxide film formed on the annealed wafer, while extending the range of nitrogen concentration contained in a silicon single crystal, are prepared by a method wherein crystal pulling conditions are controlled such that a ratio V/G between a crystal pulling rate V and an average axial temperature gradient G is ≧0.9×(V/G)and ≦2.5×(V/G), and hydrogen partial pressure is ≧3 Pa and ≦40 Pa. The silicon single crystal has a nitrogen concentration of >5×10atoms/cmand ≦6×10atoms/cm, a carbon concentration of ≧1×10atoms/cmand ≦9×10atoms/cm, and heat treatment is performed in a noble gas atmosphere having an impurity concentration of ≦5 ppma, or in a non-oxidizing atmosphere.