Zheng Pengjie, Zhao Dewen, Lu Xinchun
State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China.
Micromachines (Basel). 2023 Aug 28;14(9):1683. doi: 10.3390/mi14091683.
As feature sizes decrease, an investigation of pad unevenness caused by pad conditioning and its influence on chemical mechanical polishing is necessary. We set up a kinematic model to predict the pad wear profile caused by only diamond disk conditioning and verify it. This model shows the influences of different kinematic parameters. To keep the pad surface planar during polishing or only conditioning, we can change the sweep mode and range of the conditioner arm. The kinematic model is suitable for the prediction of the pad wear profile without considering the influence of mechanical parameters. Furthermore, based on the pad wear profile obtained from a real industrial process, we set up a static model to preliminarily investigate the influence of pad unevenness on the pad-wafer contact stress. The pad-wafer contact status in this static model can be approximated as an instantaneous state in a dynamic model. The model shows that the existence of a retaining ring helps to improve the wafer edge profile, and that pad unevenness can cause stress concentration and increase the difficulty in multi-zone pressure control of the polishing head.
随着特征尺寸的减小，有必要研究由抛光垫修整引起的抛光垫不均匀性及其对化学机械抛光的影响。我们建立了一个运动学模型来预测仅由金刚石盘修整引起的抛光垫磨损轮廓并进行验证。该模型展示了不同运动学参数的影响。为了在抛光过程中或仅在修整过程中保持抛光垫表面平整，我们可以改变修整器臂的扫描模式和范围。该运动学模型适用于预测抛光垫磨损轮廓，而无需考虑机械参数的影响。此外，基于从实际工业过程中获得的抛光垫磨损轮廓，我们建立了一个静态模型，以初步研究抛光垫不均匀性对抛光垫 - 晶圆接触应力的影响。此静态模型中的抛光垫 - 晶圆接触状态可近似为动态模型中的瞬时状态。该模型表明，挡环的存在有助于改善晶圆边缘轮廓，并且抛光垫不均匀性会导致应力集中并增加抛光头多区域压力控制的难度。
