Mitsubishi Materials Silicon Corporation

Yukio Muroi

Yoji Suzuki

Hisashi Furuya

Takaaki Shiota

Hiroshi Koya

A method of heat-treating a silicon wafer has the steps of: preparing a silicon wafer having an oxygen concentration of 1.2&times;10 atoms/cm or less (old ASTM) without generating crystal originated particles(COP'S) and interstitial-type large dislocation(L/D); forming a polysilicon layer of 0.1 &mgr;m to 1.6 &mgr;m in thickness on a back of the silicon wafer by a chemical-vapor deposition at a temperature of 670&deg; C.&plusmn;30&deg; C.; and heat-treating the silicon wafer having the polysilicon layer in an oxygen atmosphere at 1000&deg; C.&plusmn;30&deg; C. for 2 to 5 hours and subsequently at 1130&deg; C.&plusmn;30&deg; C. for 1 to 16 hours. In this method, the silicon wafer before the formation of the polysilicon layer thereon is the type of a wafer in which oxidation induced stacking faults(OSF's) manifest itself at a center of the wafer when the wafer is subjected to the heat-treatment. Accordingly, the resulting silicon wafer with a polysilicon layer is of OSF fee and COP free, even when the wafer is subjected to the conventional OSF-manifesting heat treatment. The wafer with the polysilicon layer exerts a uniform gettering effect between the peripheral edge and center of the silicon wafer as a result of a uniform oxygen precipitation occurred at the entire surface of the silicon wafer.

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Tokyo, Japan

Yukio Muroi