Patent ID: 8192822

Claim:
A silicon wafer comprising a central axis, a front surface and a back surface that are generally perpendicular to the central axis, a radius, R, extending from the central axis to a point along the peripheral edge, a point along the peripheral edge nearest the central axis, edge portions of the front and back surfaces of the wafer that extend from the nearest peripheral edge point to a point between the nearest peripheral point and the central axis and no more than about 15 mm from the nearest peripheral edge point, and central portions of the front and back surfaces of the wafer that extend from the point between the nearest peripheral point and the central axis and the central axis; wherein: the front and back surfaces of the wafer have a total thickness variation of at least 20 microns; the central portions of the front and back surfaces of the wafer have a surface roughness of at least about 0.3 μm Ra; and the edge portions of the front and back surfaces of the wafer have a surface roughness of less than about 0.3 μm Ra, the central portions of the front and back surfaces of the wafer having a surface roughness greater than the surface roughness of the edge portions of the front and back surface of the wafer.