Patent ID: 6135856
Filing Date: 2000-10-24
Classification: B24B

Abstract:
A method of polishing a surface to be polished comprising the steps of:providing a pad assembly including a lower pad and an upper pad, said upper pad having an abrasive surface and a lower surface, said abrasive surface defining a generally annular polishing region extending circumferentially around a center point, said lower pad having an upper surface, said upper pad being disposed over said lower pad, said lower pad upper surface defining one or more grooves at least partially disposed under said polishing region, a circle centered about the center point and extending through said polishing region forming intersections with some of said one or more grooves where said circle overlaps some of said one or more grooves, a length of the intersections varying according to a radius of the circle, the length of the intersections monotonically increasing from a first value to a second value as the radius of the circle increases from a first radius to a second radius, the length of the intersections monotonically decreasing from the second value to a third value as the radius of the circle increases from the second radius to a third radius, the first radius defining an inner boundary of the polishing region, the third radius defining an outer boundary of the polishing region, the second radius defining a circle near a middle of the polishing region, said upper pad defining at least temporarily one or more channels, at least a portion of said one or more channels being formed over said one or more grooves;holding said surface to be polished adjacent said abrasive surface; androtating said pad assembly.