Local material removal rate is inversely proportional to the local pattern density in ILDCMP. With the assumption that the local velocity and Preston coefficient are constant across a die, local MRR non-uniformity is attributed to the local pressure non-uniformity. Pressure distributions on two different test patterns consisting of five different pattern density sections were calculated with a finite element model. These pressure distributions were compared with semi-empirical pattern dependant oxide CMP model with three different weighting functions. Results showed that pressure distribution can be well approximated with the pattern density dependant oxide CMP model.
