Comparison of copper disc and copper wafer polishing processes in terms of their kinetic, tribological and thermal characteristics

Real-time coefficient of friction, removal rate, pad temperature transient and Interfacial Interaction Index were employed to identify and compare the Chemical Mechanical Polishing processes involving copper deposited wafers and copper metal discs. Coefficient of friction and pad temperature transients were slightly higher for the copper deposited wafers, This difference was explained by taking into account the storage modulus of the pad, as well as the significant differences in the bevel shape of discs vs. wafers. Results were consistent with the differences in the Interfacial Interaction Index. Removal rate results were also slightly higher for copper wafers suggesting consistent with a thermally dependent copper removal mechanism. In spite of the minor differences among the two substrates, copper discs are considered to be viable and more economically feasible replacements for copper deposited wafers given the fact that this study indicated that the choice of the copper substrate did not affect the key conclusion regarding the tribological, thermal and removal rate characteristics of the process.