Patent ID: 6632278
Filing Date: 2003-10-14
Classification: C30B,H01L,Y10T

Abstract:
An epitaxial wafer, comprising a single crystal silicon substrate having a central axis, a front side and a back side which are generally perpendicular to the central axis, a circumferential edge, a radius extending from the central axis to the circumferential edge, and a nominal diameter of 150 mm, 200 mm, or greater than 200 mm, the substrate comprising an axially symmetric region which is substantially free of agglomerated intrinsic point defects, the axially symmetric region extending radially inwardly from the circumferential edge and having a width, as measured from the circumferential edge radially toward the center axis, which is at least about 30% the length of the radius, wherein silicon self-interstitials are the predominant intrinsic point defect in the axially symmetric region of the wafer, and an epitaxial layer which is deposited on the front side of the substrate.