US Patent 7144308 Apparatus for chemical mechanical polishing

Apparatus for chemical mechanical polishing are disclosed. A disclosed apparatus includes a polishing station having a polishing pad, a gas supplier to generate pressurized gas to press a wafer toward the polishing pad, and a polishing head assembly including a planar member having a plurality of fine holes in communication with the gas supplier and a membrane to press the wafer toward the polishing pad due to the pressurized gas received through the plurality of fine holes, wherein the plurality of fine holes are arranged to rotate at different radii of rotation when the planar member rotates.