Patent ID: 6190631
Filing Date: 2001-02-20
Classification: C30B,H01L,Y10T

Abstract:
A single crystal silicon wafer having two major, generally parallel surfaces, one of which is the front surface of the wafer and the other of which is the back surface of the wafer, a central plane between the front and back surfaces, a circumferential edge joining the front and back surfaces, a central axis generally perpendicular to the front and back surfaces, a radius extending from the central axis to the circumferential edge, a surface layer which comprises the region of the wafer between the front surface and a distance, D.sub.1, of at least about 10 micrometers measured from the front surface and toward the central plane, and a bulk layer which comprises a second region of the wafer between the central plane and the first region, the wafer being characterized in thatthe wafer has a non-uniform distribution of crystal lattice vacancies with the concentration of vacancies in the bulk layer being greater than the concentration of vacancies in the surface layer with the vacancies having a concentration profile in which the peak density of the vacancies is at or near the central plane with the concentration generally decreasing from the position of peak density in the direction of the front surface of the wafer; and,the wafer comprises a first axially symmetric region which is substantially free of agglomerated intrinsic point defects.