Polishing pad surface shape measuring instrument, method of using polishing pad surface shape measuring instrument, method of measuring apex angle of cone of polishing pad, method of measuring depth of groove of polishing pad, cmp polisher, and method of manufacturing semiconductor device

Abstract

The main sensormeasures the distance Lm to the surface of the pad, and the sub-sensormeasures the distance Ls to the surface of the reference block. What is actually taken as the measured value is the value of (Lm+Ls). The reference blockis used in order to give a reference position for measuring the surface position of the pad. Accordingly, correct measurements can be performed even if the position of the movable elementshould fluctuate, for example, as a result of deformation of the guiding and holding plateor guide. When the motoris caused to rotate, the ball screwrotates, so that the movable elementmoves leftward and rightward, and the distance to the padis measured. From the measured data of this distance, the circular-conical vertical angle, groove depth, thickness, and the like of the padare determined.