Image Number 3 for United States Patent #5232875.
A method and apparatus for improving planarity of chemical mechanical planarization of semiconductor wafers. The wafer is affixed to the planar surface of a wafer carrier. A planar platen, on which is mounted a polishing pad, is moved about in a plane parallel to the pad surface with either an orbital, fixed-direction vibratory, or random-direction vibratory motion. In one embodiment of the invention, pressure between the surface of the wafer to be polished and the moving polishing pad is generated by the force of gravity acting on at least the wafer and the carrier; in another it is provided by a mechanical force applied normal to the wafer surface. The polishing pad is wetted with a slurry having abrasive particles suspended in a liquid which may be chemically reactive with respect to at least one material on the wafer.