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Abstract

The present invention provides a silicon wafer having a DZ layer near a surface and an oxide precipitate layer in a bulk portion, wherein interstitial oxygen concentrations of the DZ layer, the oxide precipitate layer and a transition region between the DZ layer and the oxide precipitate layer are all 8 ppma or less, and an epitaxial silicon wafer, wherein an epitaxial layer is formed on a surface of the silicon wafer, as well as a method for producing a silicon wafer, which comprises growing a silicon single crystal ingot having an initial interstitial oxygen concentration of 10 to 25 ppma by the Czochralski method, processing the silicon single crystal ingot into a wafer, and subjecting the wafer to a first heat treatment at 950 to 1050.degree. C. for 2 to 5 hours, a second heat treatment at 450 to 550.degree. C. for 4 to 10 hours, a third heat treatment at 750 to 850.degree. C. for 2 to 8 hours, and a fourth heat treatment at 950 to 1100.degree. C. for 8 to 24 hours. Thus, there is provided a method for producing a silicon wafer of which high resistivity can surely be maintained even when the wafer is subjected to a heat treatment for device production.

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First Claim