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, 2011
Filed:
Apr. 21, 2009
Tatsumi Kusaba, Takeo, JP;
Hidehiko Okuda, Imari, JP;
Tatsumi Kusaba, Takeo, JP;
Hidehiko Okuda, Imari, JP;
Sumco Corporation, Tokyo, JP;
Abstract
This p-type silicon wafer was subjected to heat treatment to have a resistivity of 10 Ω·cm or more, a BMD density of 5×10defects/cmor more, and an n-type impurity concentration of 1×10atoms/cmor less at a depth of within 5 μm from a surface of the wafer. This method for heat-treating p-type silicon wafers, the method includes the steps of: loading p-type silicon wafers onto a wafer boat, inserting into a vertical furnace, and holding in an argon gas ambient atmosphere at a temperature of 1100 to 1300° C. for one hour; moving the wafer boat to a transfer chamber and discharging the silicon wafers; and transferring to the wafer boat silicon wafers to be heat treated next, wherein after the discharge of the heat-treated silicon wafers, the silicon wafers to be heat-treated next are transferred to the wafer boat within a waiting time of less than two hours.