抛光液中离子浓度对化学机械抛光过程的影响

Influence of Ionic Concentration of Slurry on Process of Chemical Mechanical Polishing

在化学机械抛光过程中,抛光液中的离子浓度对化学机械抛光的速率和表面质量影响显著。为了解释化学机械抛光过程中抛光液中离子浓度的作用,利用荧光观察试验及实际抛光试验,研究抛光液中离子浓度对抛光过程的影响,并使用白光形貌仪观察抛光后表面质量。结果表明:颗粒运动速度随着抛光液中的硫酸钾浓度的增加而下降,材料去除率随硫酸钾浓度上升而提高。但是过高的离子浓度会导致表面质量下降。当硫酸钾浓度大于175mmol/L时,抛光后晶片表面出现明显缺陷。为了兼顾完成质量和去除速率,应当选用硫酸钾浓度为150mmol/L左右的抛光液。

In the process of chemical mechanical polishing, the ionic strength of the slurry has significant effect on the material removal rate and surface quality. To illustrate the effect of ionic strength on the chemical mechanical polishing, the experiments were conducted with a self-developed fluorescence device and chemical mechanical polishing apparatus. The results show that with the increase of the ionic strength of the slurry, the velocities of polishing particles decrease and the material removal rateincrease. The surface quality becomes worse when the ionic strength is high. When the concentration of K2SO4 is over 175 mmol/L, there are obvious scratches on the surface of the wafer. To compromise both removal rate and surface quality, the slurry with 150 mmol/L concentration of K2 SO4 will be appropriate in the chemical mechanical polishing process.