US Patent 7134947 Chemical mechanical polishing system

According to one embodiment of the invention, a chemical mechanical polishing system includes a platen having a first surface adapted to couple a polishing pad thereto. The first surface includes a generally circular center portion and an annular portion surrounding the generally circular center portion. The generally circular center portion encloses an area and has an attachment surface area that is less than the area enclosed by the generally circular center portion. The attachment surface area is adapted to couple an inner portion of the polishing pad to the platen.