METHOD AND APPARATUS FOR MEASURING LAYER THICKNESS OF SUBSTRATE UNDER CHEMICAL MECHANICAL POLISHING

摘要

PROBLEM TO BE SOLVED: To measure the layer thickness of a substrate in the process of chemical mechanical polishing.

SOLUTION: A light beam is split by passing through a window in a polishing pad and movement of the polishing pad to the substrate moves the light beam within a path traversing a substrate surface. An interference signal generated by the light beam reflected from the substrate is monitored to extract multiple measured intensity values from the signal. Each measured intensity value corresponds to a sampling area within the path traversing the substrate surface. A radial position is decided for each sampling area and the measured intensity value is split into multiple radial widths corresponding to the radial position. The layer thickness is calculated for each radial width, based on the measured intensity value associated with that radial width.

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