Patent ID: 6020264
Filing Date: 2000-02-01
Classification: B24B,G01B,H01L

Abstract:
An apparatus for in-line thickness measurement of a dielectric film layer on a surface of a workpiece subsequent to a polishing of the dielectric film layer on a chemical-mechanical polishing machine in a polishing slurry, the workpiece having a given level of back-end-of-line (BEOL) structure including junctions, said apparatus comprising:a measurement platen;a measurement electrode embedded within said measurement platen;means for positioning the workpiece above said measurement electrode with the dielectric layer facing in a direction of said measurement electrode;means for maintaining a prescribed level of a conductive polishing slurry above said measurement electrode, the prescribed level to ensure a desired slurry coverage of the workpiece, wherein the slurry maintains a static electrical contact with the dielectric layer and the workpiece;means for sensing a system capacitance C in accordance with an RC equivalent circuit model in which a resistance R is representative of the slurry and workpiece resistances and the system capacitance C is representative of the dielectric material and junction capacitances; andmeans for converting the sensed capacitance to a dielectric thickness in accordance with a prescribed system capacitance/optical thickness calibration, wherein the prescribed calibration corresponds to the given level of BEOL structure of the workpiece.