化学机械研抛过程流体和磨粒分布特性仿真

为深入理解化学机械抛光过程中的摩擦磨损机理,仿真研究了不同工况对抛光作用的影响规律.建立考虑多相流和离散相的三维CFD模型,研究不同工况下晶片和抛光垫间抛光液的速度和压力分布以及抛光磨粒的分布规律.结果表明:膜厚越小,抛光垫和晶片的转速越大,磨粒的分布密度越小.对流体速度和压力分布规律以及磨粒分布特性进行仿真分析,研究抛光过程中磨粒对晶片表面的动压作用过程.用疲劳断裂能量守恒理论,建立可定量分析各种工况下材料去除率的预测模型,采用Matlab软件对去除率模型进行仿真计算,得到不同工况下碳化硅晶片的去除率曲线.结果表明,抛光垫转速越大,膜厚越小,材料去除率越大,但去除率随着抛光的进行呈现减小的趋势.相比抛光垫转速对去除率的影响,膜厚对去除率的影响较小.

Modeling and simulation for the distribution of fluid and slurry particles in chemical mechanical polishing

To fully understand the friction and wear mechanism of chemical mechanical polishing process, the effects of different processing conditions on the polishing process were simulated. Three-dimensional CFD model considering multiphase flow and discrete phase was established to obtain the speed and pressure distribution of the polishing liquid as well as that of the polishing abrasive particles between wafer and polishing pad under different processing conditions. It is found that the abrasive particle distribution density is smaller when the film thickness is smaller, and the greater the speeds of the polishing pad and wafer, the smaller the particle distribution density. Based on the distribution characteristics of fluid velocity, pressure and polishing particles, a model of material removal rate(MRR) was established, and the dynamic pressure caused by flowing polishing abrasive on the surface asperity of the wafer during polishing process was analyzed. By applying the energy-balance fracture theory, the MRR prediction model was established which could be used quantitatively for all kinds of materials. For silicon carbide polishing, its MRR curve under different processing conditions was obtained by Matlab programing. It is found that the MRR is greater when the polishing pad speed is greater and the gap film thickness is smaller. The MRR decreases as polishing continues, and the effect of film thickness on the removal rate is smaller compared with that of the polishing speed.