抛光垫特性对抛光中流体运动的影响分析

The Influences of Pad Characteristics on Slurry Flow

抛光垫表面特性能可大大改变抛光液的流动情况,从而影响化学机械抛光的抛光性能。考虑抛光垫粗糙度和孔隙等对抛光液流动的影响,提出了一个初步的晶片级流动模型,并用数值模拟方法研究了不同参数条件(载荷和速度的变化等)下抛光液的流动特征。计算结果表明增加外载荷将导致粗糙峰的磨损概率增加,增加剪切速率则提高了剪切应力,均可导致高材料去除率。模型能较好理解材料去除机制和输运,从而有助于对化学机械抛光机制的了解。

Slurry flow weighs heavily on the performances of chemical mechanical polishing （CMP） process, wherein the pad surface will alter the flow features considerably. A preliminary wafer-scale flow model was presented taking the roughness as well as the porosity of the pad into consideration. Numerical simulations were conducted to show the slurry flow features under various working conditions. The simulation results show that the film thickness is decreased by the exerted load, and the possibility of asperity-wafer direct contact is increased. The shear stress is enhanced with the increase of the rolling velocity. These two factors give rise to an increase in the material removal rate （MRR）. The model predictions are conducive to the removal rate and mass transport computation.