Lamination wafers and method of producing bonded wafers using the same

A lamination wafer, which is to be bonded to a support wafer and thinned by grinding, to form a bonded wafer, comprising:

• a large-diameter portion whose peripheral edge is chamfered, which forms a backside surface of the lamination wafer;
• and
• a small-diameter portion, smaller in diameter than that of the large-diameter portion, formed on the large-diameter portion concentrically and integrally with the large-diameter portion, which forms a front surface of the lamination wafer;
• wherein the large-diameter portion and the small-diameter portion constitute a single, integral silicon wafer;
• the small-diameter portion comprising
• a straight body portion whose side surface is perpendicular to the wafer surface;
• and
• a neck portion disposed between the straight body portion and the large-diameter portion, wherein the neck portion has a peripheral surface that is tilted to the wafer surface at a tilting angle θ in a range of 45°≤θ<90°,
• wherein the small-diameter portion is formed such that the upper face of the straight body portion is to be bonded to the support wafer.