Pneumatic polishing head for CMP apparatus

摘要

A polishing head for chemical-mechanical polishing apparatus includes a carrier plate having concentric, integral, cylindrical walls, an annular piston fitting within the outer of the cylindrical walls and a second piston fitting within the inner cylindrical wall and engaging the annular piston. Each piston defines a chamber with the carrier plate and the chambers are isolated from each other by a seal. Pneumatic fittings supply air or vacuum to each chamber. The second piston includes a cylindrical side wall and an integral bottom plate. The bottom plate is thicker in the center than at the side wall and the underside of the plate is covered with a wafer adhering layer. A retaining ring is attached to the lower edge of the annular piston. The retaining ring includes a peripheral groove for separating an outwardly extending flange from the main body of the ring. The underside of the ring includes one or more spiral grooves for circulating slurry about a wafer during polishing.