Measurement and Analysis of Single-Pass Conditioning Furrows in CMP Pad Surfaces

Diamond conditioning of polishing pads is an essential step in chemical mechanical planarization (CMP) that generates favorable surface texture for wafer polishing. Texture formation is governed by polymer fracture mechanics and depends on the characteristics of individual diamonds and their arrangement on the disk, the conditioning recipe (downforce and sliding speed), and the pad polymer mechanical properties and porosity. This work focuses on measurement of furrows formed in CMP pad surfaces using a diamond element, extracted from an industry-standard conditioning disk, comprising a single row of eight to ten diamonds having representative variations in protrusion and shape. Differences among the diamonds lead to various degrees of engagement with the pad surface and a corresponding mix of fracture modes typical of a commercial process. The observed spacing between adjacent furrows allows each to be linked to the diamond from which it originated—and its fracture characteristics to be related to features of the particular diamond. The experiment and analysis are illustrated by comparing three pad materials having dissimilar pore loadings.