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

We report on a technique for measuring dynamic surface roughness changes during the chemical mechanical polishing (CMP) of metal and dielectric films. The technique is based upon the measurement of lateral frictional forces during the CMP operation. These measurements were carried out in particle-free slurries, which led to reduced noise in the measurements. Under constant slurry and pad conditions, the frictional forces were dependent on the surface roughness of the silica and tungsten films. For silica, the lateral frictional 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 tungsten during the experiment. (C) 1999 The Electrochemical Society. S1099-0062(98)06-058-1. All rights reserved.