Abstract: Chemical mechanical polishing (CMP) enables global and local flatness polishing of a wide range of materials and is now widely used in the field of integrated circuit manufacturing. As one of the main consumables in the CMP process, slurry accounts for 50% of the total cost of the CMP process. However, most of the slurry is discharged into the waste stream by centrifugal force before it reaches the polishing pad-wafer interface, resulting in a very low slurry effective utilization rate. Therefore, optimizing the CMP process parameters to improve the slurry effective utilization can not only reduce the polishing cost but also solve some environmental problems. For the CMP process, the retaining ring not only fixes the wafer to prevent it from slipping out but also helps the slurry to transfer between the pad-wafer interfaces through its multiple grooves to improve the slurry effective utilization. Consequently, in this work, construct a dynamic coupling model of slurry flow and retaining ring rotation, and the finite element method (FEM) was employed to investigate the effect of retaining ring structure (including the number of grooves, groove width, groove area, and the presence of rounded corners at the grooves) on the slurry effective utilization rate during the CMP process. The results showed that the slurry effective utilization rate improved with the increase of retaining ring groove number with the same groove width (3.0 mm). For the same groove area (1785.4±0.3 mm2), the increase of retaining ring groove number led to a decrease in the slurry effective utilization rate. And the same number of grooves, the larger the groove width, the greater the slurry effective utilization rate. Fillet grooves had a higher slurry effective utilization rate than sharp-edged grooves. When the groove width of the retaining ring was enlarged and the groove of the retaining ring was designed as fillet, the slurry effective utilization rate could be improved significantly. This work optimizes the CMP process parameters by FEM simulation and provides theoretical guidance to reduce the CMP cost.

Key words: chemical mechanical polishing, retaining ring, slurry, finite element simulation, effective utilization rate

摘要： 化学机械抛光(CMP)过程中抛光液占其总成本的50%，抛光液有效利用率却非常低。改进保持环的沟槽结构可以提高抛光液的有效利用率。本工作中，构建了抛光液流动与保持环转动的动态耦合模型，采用有限元方法(FEM)探究了CMP过程中保持环结构(包括沟槽数量、沟槽宽度、沟槽面积以及沟槽处是否为圆角)对抛光液有效利用率的影响。结果表明，同沟槽宽度(3.0 mm)时，抛光液的有效利用率随着保持环沟槽数量的增加而提高。而同沟槽面积(1785.4±0.3 mm2)时，保持环沟槽数量增加会导致抛光液的有效利用率下降。在其他条件相同的情况下，圆角型沟槽比尖角型沟槽有更高的抛光液有效利用率。本工作通过FEM优化了CMP工艺参数，为降低CMP成本提供了理论指导。

关键词: 化学机械抛光, 保持环, 抛光液, 有限元模拟, 有效利用率