Heat and its effects to chemical mechanical polishing

Heat is an indispensable factor in understanding the removal rate and WIWNU (within wafer non-uniformity) in CMP (chemical mechanical polishing). The principal heat generation mechanism results from the two-body abrasion mode. Experiments are implemented using the on-machine temperature measuring system with an IR digital camera. This paper investigates the primary process parameters affecting heat generation and temperature distribution on pad surfaces. Meanwhile, the change of temperature affects the characteristics of both slurry and pads. The change in the pH value of the slurry due to the alteration of temperature affects the surface state of the abrasive particles and therefore the agglomeration of abrasives happens above a certain temperature. Moreover, the temperature changes the first and second elastic moduli of the pads and their real contact area, which is closely related to the removal rate and WIWNU.