Analysis of frictional heating of grooved and flat CMP polishing pads

A detailed model is described for the generation, transport and exchange of thermal energy in rotary CMP tools. Frictional energy generated due to abrasion of the wafer by the pad and slurry particles is partitioned between the pad and the rotating wafer, with the majority going to the latter. The slurry at the same time provides a major cooling mechanism, drawing heat away while it is entrained under the wafer and then redistributing it over the pad by radial convection. The slurry flow component of the theory includes thermal effects due to the presence of concentric grooves. The model accounts for the time and radial dependence of pad temperature measurements performed on flat and grooved pads at the leading and trailing edges of the wafer, at the pad center and pad margins, and on the wafer carrier. It suggests that the temperature increase on the wafer may be approximately twice the increase measured on the pad.