Abstract: The invention is directed a patterned contact sheet and to a method of bonding a cover wafer to an interposer wafer using the patterned contact sheet having a waffle-like pattern of a plurality of ridges and plurality of wells to form a cover/interposer combination or unit that can be bonded to a substrate having a MEMs device thereon, the cover wafer, interposer wafer and substrate together forming a protective packaging for the MEMS. Use of the patterned contact sheet results fewer defects on the window area (the critical area) through which light is transmitted. Surprisingly, use of the patterned contact sheet also results in windows having improved flatness relative to windows made using an unpatterned contact sheet.