Papers by Keyword: Non-Uniformity (UN)

Abstract: A contact-mechanics-based finite model for Cu/ low-k chemical mechanical polishing is presented. 2D axisymmetric quasi-static model for chemical mechanical polishing which includes four-layer structure: Si, low-k, Copper and polishing pad is established. The mechanical response at the interface between the silicon, low-k, copper, and pad is simulated under the loading of the chemical mechanical polishing. The effect of slurry is simplified as the friction force reacted onto both the copper and the polishing pad in the finite element model. Down pressure, status of slurry and the elastic modulus of polishing pad are treated as the parameter in the simulation. Using the model, the effects of applied down pressure, pad properties, status of slurry on the non-uniformity of the wafer surface can be readily evaluated. Simulation results show that the distribution of the Von Mises stresses across a wafer’s surface correlates with experimental removal rate profiles.

Abstract: Polishing pad plays a key role in determining polish rate and planarity of a chemical mechanical planarization (CMP). The properties of the pad would deteriorate during polishing because of pad surface grazing, which results in reduced removal rates and poorer planarity of wafer surface. Pad conditioning and its influence on pad surface structure and CMP process is introduced and discussed in this paper. The study shows that the surface structure can be regenerated by breaking up the glazed areas with conditioner, MRR(Material Removal Rate) can be maintained at high level with proper pad conditioning, and UN(Non-uniformity)can also improved. Orthogonal experiments design is employed in this study to determine the best conditioning parameters.