Numerical Simulation Of Slurry Film Lubrication In Chemical Mechanical Polishing Process

In the process of Chemical Mechanical Polishing(CMP), material is removed by the combination of chemical and mechanic effect. The flow characteristic of slurry under the wafer influences material remove rate and quality of surface directly. But due to special processing method of CMP: close contact of workpiece and polishing pad, tiny size of slurry film which decides the difficulties of observing the slurry flow of CMP. Therefore the improvement of CMP mechanism research is hindered.This paper builds Laser Induced Fluorescence(LIF) experiment platform to make a visualization research on slurry film and has a theoretical analysis on Laser Induced Fluorescence technology. On fluorescence intensity detail, Equations of fluorescence was build and relationship between fluorescence intensity with slurry film was defined. Shoot the fluorescence pictures which describe the slurry film of CMP process by CCD camera. The paper exhibits influence of CMP process parameters on film by those fluorescence pictures.The paper is aimed to build model of slurry flow in the wafer-pad interface during CMP. The hydrodynamic behavior of the film is analyzed numerical using the finite-element method to expand the Reynolds equation in three-dimensional cylindrical coordinates. Effects of minimum film thickness and wafer gradient on film load supported were analyzed. Lubrication model was solved with minimum film thickness and wafer gradient which conditioned by force balance and moment balance. Finally, the effects of CMP process parameters involving load and speed on film pressure distribution was discussed.