Patent attributes
A method for control of chemical mechanical polishing of a pattern dependant non-uniform wafer surfaces in a die scale wherein the die in the wafer surface have a plurality of zones of different heights and different pattern densities is provided. The method provides for varying pressure applied to the die both spatially and temporally to reduce both local and global step height variations. In one embodiment, pressure is varied both spatially and temporally using a look ahead algorithm. The algorithm looks ahead and recalculates/modifies the pressure values by identifying the step heights that could be formed after a specified time step. The final surface predictions have improved uniformity on the upper surface as well as on the step heights across the entire die.
