| 摘要 |
PROBLEM TO BE SOLVED: To obtain an IG wafer having a high IG capability, where a wafer is heat-treated for a smaller number of times and a desired IG effect can be exhibited by a heat treatment at 950 deg.C or lower, as well as to obtain a single- crystal silicon ingot suitable for this IG wafer. SOLUTION: The IG processing method involves the steps of rapidly heating a silicon wafer, after which it is immediately cut out of a silicon single-crystal ingot and ground and polished, starting from the room temperature to 700-950 deg.C at a rate of 10 deg.C/minute or higher, and thereafter holding the heated wafer for 0.5-30 minutes. The ingot is lifted from a silicon melt, such that oxidation induced stacking faults(OSF) are formed in an area which is 25% or more of the total wafer area when thermally oxidized in the form of a wafer, and contains oxygen precipitates accompanying no formation of dislocations in amounts of 1×105-3×107 pieces/cm3. In this IG wafer, a DZ layer is formed to a depth of 1-100μm from the wafer surface and has a density range for oxygen prec ipitates of 1×105-3×107 pieces/cm3 at a portion deeper than the DZ layer.
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