Patent ID: 6071177
Filing Date: 2000-06-06
Classification: B24B

Abstract:
A method for determining an end point in a polishing process comprising the steps of:providing a sample to be polished, said sample having at least a surface layer and a base layer formed of different materials, said surface layer material is adapted for penetration by a laser beam, an interface formed between said surface layer and said base layer for reflecting said laser beam,providing a polishing platen having installed thereon a polishing pad for removing at least partially said surface layer on said sample, said polishing platen further comprises a laser generator and a laser detector situated therein for sending and receiving emissions toward and from said interface in said sample through a window provided in said polishing pad,rotating said sample and said polishing platen independently and frictionally engaging a top surface of said surface layer on said sample with a top surface of said polishing pad,emitting from said laser generator emissions comprising two different wavelengths toward said interface in said sample and receiving a composite wavelength interference curve in said laser detector, anddetermining an end point in said composite wavelength interference curve corresponding to a thickness of said surface layer retained.