Silicon wafers having controlled precipitation distribution

摘要

PCT No. PCT/IT91/00095 Sec. 371 Date May 13, 1993 Sec. 102(e) Date May 13, 1993 PCT Filed Nov. 11, 1991 PCT Pub. No. WO92/09101 PCT Pub. Date May 29, 1992.A silicon wafer containing oxygen precipitate nucleation centers (or oxygen precipitates) and having a first face, a second face, and a central plane equidistant between the first and second faces. The nucleation centers (or oxygen precipitates) have a non-uniform distribution between the first and second faces with a maximum density of the nucleation centers (or oxygen precipitates) being in a region which is between the first face and the central plane and nearer to the first face than the central plane. The density of the nucleation centers (or oxygen precipitates) increases from the first face to the region of maximum density and decreasing from the region of maximum density to the central plane.