铜化学机械抛光材料去除机理研究

Study on material removal mechanism of Cu-deposited wafer during chemical mechanical polishing

本文根据铜CMP过程中表面材料的磨损行为,建立了铜CMP时的材料去除率构成成分模型,并通过材料去除率实验,得出了各机械、化学及其交互作用所引起的材料去除率及其作用率:当np=nw=200r/min时,有最佳材料去除率,此时单纯的机械作用率为9.2%;单纯的化学作用率为仅为2.1%,抛光垫的机械与化学交互作用率为5.08%;磨粒的机械与化学交互作用率为83.6%。通过对实验结果进行分析,可得如下结论:硅片化学机械抛光中,一定的参数下有一个最优的抛光速度;在最优的速度下,机械与化学之间交互作用达到平衡,这时可获得最高的材料去除率;硅片化学机械抛光过程是一个多变的动态过程,仅仅通过增加机械作用或化学作用不能获得理想的材料去除效果。本文的研究结果可为进一步研究硅片CMP时的材料去除机理提供理论参考依据。

In this paper, the constituent model of material removal in wafer chemical mechanical polishing （CMP） was described qualitatively based on theory of corrosive wear. The value of each constituent was obtained by a series of wafer CMP experiments. When np= nw = 200 r/min, there are the best material removal rate （MRR）. At this time, the ratio of only mechanical action was 9.2% ; the ratio of only chemical action of the slurry was 2.1%, the interaction ratio between the mechanical action of the polishing pad and the chemical action of polishing slurry was 5.08% ; and the interaction ratio between the mechanical action of the abrasive grains and the chemical action of the slurry was 83. 6%. The results show that there exists an optimum polishing velocity in wafer CMP at certain parameters. Under the optimum velocity, the balance of interaction between the mechanical action and the chemical action is reached and the material removal rate approaches maximum. The wafer CMP is a changeful and dynamic process. We cannot obtain ideal effect of material removal by increasing the mechanical action or chemical action only. These results provide a theoretical guide to further understanding of the material removal mechanism in wafer CMP.