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:
Dec. 08, 2009
Filed:
Jan. 17, 2007
Shigeru Umeno, Tokyo, JP;
Shigeru Umeno, Tokyo, JP;
Sumco Corporation, Tokyo, JP;
Abstract
A single crystal silicon wafer for use in the production of insulated gate bipolar transistors is made of single crystal silicon grown by the Czochralski method and has a gate oxide with a film thickness of from 50 to 150 nm. The wafer has an interstitial oxygen concentration of at most 7.0×10atoms/cm, a resistivity variation within the plane of the wafer of at most 5% and, letting t(cm) be the gate oxide film thickness and S (cm) be the electrode surface area when determining the TZDB pass ratio, a density d (cm) of crystal originated particles (COP) having a size at least twice the gate oxide film thickness which satisfies the formula d≦−ln(0.9)/(S·t/2). The wafers have an increased production yield and a small resistivity variation.