A comparative study on the roles of velocity in the material removal rate during chemical mechanical polishing

Relative velocities between the flowing slurry and selected points on a 150 mm wafer and nonuniformity of velocity are calculated given the known carr ier speed, platen speed, and pad-to-wafer distance. Based on simulation res ults, the combination of a high pad rpm, a medium wafer rpm, and a large pa d-to-wafer distance should give rise to a minimum nonuniformity of velocity . Chemical mechanical polish (CMP) removal rates data are fitted to the ori ginal Preston equation, Tseng's model,(1) and a modified Preston equation w hich incorporates the deterioration characteristics of abrasives into the r emoval rate model. Theoretical removal rate data predicted by Tseng's model and the modified Preston equation exhibit much better agreement with exper imental removal rates than those by the original Preston equation. The nonl inear dependence of removal rate on velocity can be explained by the deteri oration in slurry abrasion capability. (C) 1999 The Electrochemical Society . S0013-4651(97)11-028-X. All rights reserved.