Patent ID: 6108092
Filing Date: 2000-08-22
Classification: B24B,G01B,H01L

Abstract:
A method for detecting an endpoint in chemical-mechanical polishing of a semiconductor wafer having a lower layer of material with a first reflectivity and an upper layer with a second reflectivity positioned over the lower layer, wherein the upper layer is polished with a chemical-mechanical polishing process to form a polished surface on the wafer, the method comprising:selecting an endpoint site on the wafer defined by a boundary between the upper and lower layers at a selected location on a topography of a circuit of the wafer, the selected location being at a depression in the boundary between the upper and lower layers;impinging a beam of light against the polished surface of the wafer, the beam of light being reflected to a light sensor;sensing an actual intensity of the reflected beam of light; andcomparing the actual intensity of the reflected light beam with an expected intensity.