Chemical-Mechanical Polishing Model Considering Asperity Contact and Grain Flow Partial Hydrodynamic Lubrication

H.-J. Tsai (Taiwan)


Chemical mechanical polishing, Grain Flow, Pad Roughness, Partial Hydrodynamic Lubrication, Asperity Contact, Removal Rate


Chemical mechanical polishing (CMP) is a key technique for wafer global planarization in sub-micro device fabrication. A physical CMP model combines the effects of slurry flow hydrodynamic pressure, pad roughness, and asperity contact. In this study, an improved model considering both the micro-contact mechanism and the grain flow with roughness effects is proposed. The model applies the average lubrication equation with partial hydrodynamic lubrication theory and elastic-plastic micro-contact theory. The external force acting on the wafer is supported by the partial hydrodynamic slurry pressure in the non-contact area and the surface asperity contact force in the contact area. The results are in good agreement with experimental data in the literature. The effects of the CMP parameters (applied load, rotation speed, particle size and pad roughness) on film thickness, attack angle, contact area ratio and removal rate are studied and discussed.

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