Prediction of Real Contact Area from Microtopography on CMP Pad

Abstract

A simplified model related to microtopography on CMP pad and prediction of real contact area between the pad and wafers is presented in this paper. The model has been developed on the basis of the analysis of the pad surface roughness and contact mechanics. The bearing area curve, representing tribological properties of the surface, is used to formulate the model. The pad microtopography which is expressed in the model is uniform and simple. Particularly, the important characteristics of the pad microtopography for the CMP process are emphasized in the model. It provides more convenient way to perceive the situation of the pad surface during the CMP process. The progress of the pad surface wear and the real contact area can be easily taken and connected each other by using the model. The model is also verified by comparing the tendency of actual removal rates with those theoretically anticipated. Finally, authors could get the efficient link between the pad surface wear and the real contact area, which results in a strong tool to understand the fundamental CMP mechanism of material removal.

Keywords

• microtopography
• chemical mechanical polishing (cmp)
• real contact area
• surface roughness
• bearing area curve