Patent ID: 6336841
Filing Date: 2002-01-08
Classification: B24B

Abstract:
A method of determining an endpoint of a chemical mechanical polishing (CMP) process applied to a semiconductor wafer to remove a first layer directly atop a second layer on a first side of the semiconductor wafer, the first and second layer each absorbing infrared (IR) light at different wavelengths, the method comprising:directing an IR light source onto the first side of the semiconductor wafer; detecting transmitted IR light received by an IR detector located on a second side of the semiconductor wafer; graphing IR absorptivity of the first layer and the second layer; performing the CMP process and using the IR absorptivity of the first layer and the second layer to produce an IR absorbance curve;and determining the endpoint of the CMP process, wherein the endpoint of the CMP process is determined at a point when a lack of significant change in the IR absorptivity of the first layer occurs in combination with a decrease in the IR absorptivity of the second layer.