In situ lateral force technique for dynamic surface roughness measurementsduring chemical mechanical polishing

We report on a technique for measuring dynamic surface roughness changes du ring the chemical mechanical polishing (CMP) of metal and dielectric films. The technique is based upon the measurement of lateral frictional forces d uring the CMP operation. These measurements were carried out in particle-fr ee slurries, which led to reduced noise in the measurements. Under constant slurry and pad conditions, the frictional forces were dependent on the sur face roughness of the silica and tungsten films. For silica, the lateral fr ictional forces were approximately constant with polishing time, suggesting no significant change in surface roughness during polishing time. However, for tungsten, the force response changed drastically with time. The change in response was correlated with changes in the surface morphology of tungs ten during the experiment. (C) 1999 The Electrochemical Society. S1099-0062 (98)06-058-1. All rights reserved.