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Abstract

The invention relates to a silicon wafer and an epitaxial silicon wafer, which are doped with arsenic (As) as an n-type dopant and are excellent in gettering characteristics. A first silicon wafer has a resistivity of 10 .OMEGA.cm to 0.001 .OMEGA.cm as a result of addition of arsenic and has a nitrogen concentration of 1.times.10.sup.13 to 1.times.10.sup.15 atoms/cm.sup.3. A second silicon wafer has a resistivity of 0.1 .OMEGA.cm to 0.005 .OMEGA.cm and a nitrogen concentration of 1.times.10.sup.14 to 1.times.10.sup.15 atoms/cm.sup.3. A third silicon wafer has a resistivity of 0.005 .OMEGA.cm to 0.001 .OMEGA.cm and a nitrogen concentration of 1.times.10.sup.13 to 3.times.10.sup.14 atoms/cm.sup.3. An epitaxial silicon wafer derived from any of the first to third silicon wafers by forming an epitaxial layer in the surface layer portion is provided. In producing this epitaxial silicon wafer, epitaxial layer formation is desirably carried out after subjecting the silicon wafer to heat treatment for forming oxygen precipitates under conditions of a temperature not lower than 700.degree. C. but lower than 900.degree. C. and a period of 30 minutes to 4 hours. By these, an oxygen precipitate density can be secured and a sufficient gettering effect can be produced in the device producing process in spite of their being n-type silicon wafers doped with a high concentration of arsenic.

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First Claim