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:
Jun. 25, 2002
Filed:
Mar. 23, 2001
Robert A. Falster, London, GB;
Joseph C. Holzer, St. Charles, MO (US);
Steve A. Markgraf, St. Charles, MO (US);
Paolo Mutti, Merano, IT;
Seamus A. McQuaid, St. Louis, MO (US);
Bayard K. Johnson, St. Louis, MO (US);
MEMC Electronic Materials, Inc., St. Peters, MO (US);
Abstract
The present invention relates a process for the preparation of single crystal silicon, which contains an axially symmetric region which is free of agglomerated intrinsic point defects. The process for growing the single crystal silicon including controlling the ratio v/G , where v is the growth velocity and G is the average axial temperature gradient during the growth of a constant diameter portion of the crystal over a temperature range from solidification to a temperature of no less than about 1325° C., and a cooling rate of the crystal from a solidification temperature to about 1,050° C., in order to cause the formation of an axially symmetrical segment which is substantially free of agglomerated intrinsic point defects. The control of V/G accomplished by controlling heat transfer at the melt/solid interface.