Patent ID: 8142885

Claim:
A heat treated silicon wafer containing BMDs having a shape, exhibiting reduced occurrence of slips and warpage, and having an interstitial oxygen concentration of 5×10 17 atoms/cm 3 or less, comprising a wafer a) wherein the shape of BMDs in the wafer is octahedral, and the density of BMDs whose diagonal lengths are in a range of 10 nm to 50 nm in the bulk of the wafer at a distance of 50 μm or more from a wafer surface is 5×10 11 /cm 3 or more, and the density of BMDs whose diagonal lengths are 300 nm or more in the bulk of the wafer at a distance of 50 μm or more from the wafer surface, is 1×10 7 /cm 3 or less, b) both plate-shaped BMDs and octahedral BMDs are present, and the density of octahedral BMDs whose diagonal lengths are in a range of 10 nm to 50 nm in the bulk of the wafer at a distance of 50 μm or more from the wafer surface is 5×10 11 /cm 3 or more, and the density of plate-shaped BMDs whose diagonal lengths are 750 nm or more in the wafer bulk at a distance of 50 μm or more from the wafer surface, are 1×10 7 /cm 3 or less, or c) the BMDs are plate-shaped, and the density of BMDs whose diagonal lengths are in a range of 10 nm to 120 nm in the bulk of the wafer at a distance of 50 μm or more from the wafer surface is 1×10 11 /cm 3 or more, and the density of BMDs whose diagonal lengths are 750 nm or more in the bulk of the wafer at a distance of 50 μm or more from the wafer surface, is 1×10 7 /cm 3 or less.