Measurement of Thickness Profile and Elastic Modulus Profile of a Polishing Pad

摘要

An apparatus for measuring the thickness profile and elastic modulus profile of a polishing pad comprise an eddy current sensor and a mechanism to press the eddy current sensor against the polishing pad. The pad thickness is given by the signal of the eddy current sensor. The elastic modulus of the polishing pad is extracted from measurements at different forces applied to the eddy current sensor. The thickness profile and elastic modulus profile of the polishing pad are obtained by scanning the measurement across the whole polishing pad or along a diameter of the polishing pad. The pad thickness profile is used to adjust pad conditioning recipe so that more pad materials is eroded away at thicker area of the pad. By employing the apparatus of present invention, the thickness uniformity of a polishing pad can be better maintained, resulting in longer pad lifetime and better CMP removal rate uniformity.