Hard-copy versus soft-copy image reading for detection of ureteral stones on abdominal radiography.

A method of polishing semiconductor wafers and apparatus therefore are described. According to the present invention, a semiconductor wafer mounted on the lower side of a wafer mounting plate may be polished on a polishing pad by the front referenced polishing technique due to a flexibility of the wafer mounting plate to make the same to conform in detail with the backside contour of the wafer under polishing pressure and a selected flexibility differential between a wafer holding region and the outer moving region of the wafer mounting plate. An apparatus includes the wafer mounting plate that also works as a vacuum chuck plate is constructed out of a flexible thin disc of hard plastics, a central round region is used for a wafer holding region facing the backside of the wafer and the outside annular region is more flexible to work as a moving region, a pan-shaped rubber sheet is secured to a ring projection, the wafer mounting disc is adhered to the inner periphery of the rubber sheet at and along the periphery thereof to generate a sealed space, passes for vacuum communication and for a compressed air supply are formed through a rotary shaft, and vacuum chuck holes are communicated with the vacuum pass and the compressed air pass is in communication with a sealed space in the wafer holder.