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:
Apr. 02, 2002
Filed:
Oct. 05, 2000
Sumitomo Metal Industries, Ltd., Osaka, JP;
Abstract
Methods are designed to manufacture an epitaxial wafer wherein the formation of defects in an epitaxial layer is sufficiently suppressed even if the epitaxial wafer is prepared from a silicon single crystal which is grown while doped with nitrogen. Specifically, the methods are to grow an epitaxial layer on a wafer sliced from (1) a silicon single crystal wherein the oxygen concentration at an OSF ring region is 9×10 atoms/cm or less, (2) a silicon single crystal wherein the inside diameter of an OSF ring region is located at a position which is 85% or more of the wafer diameter, and (3) a silicon single crystal doped with nitrogen at a concentration between 1×10 atoms/cm or more and 1×10 atoms/cm or less. Further, another method is to grow an epitaxial layer on (4) a wafer sliced from a silicon single crystal doped with nitrogen at a concentration between 1×10 atoms/cm or more and less than 1×10 atoms/cm , the epitaxial layer being grown after the sliced wafer has been heat-treated at a temperature between 1200° C. and 1300° C. for 1 minute or more. According to the above methods, the density of defects in an epitaxial layer can be reduced to 0.1 piece/cm or less.