硅片抛光的接触压强分布与宏观形貌创成机理

为了获得单晶硅片化学机械抛光过程中的接触压强分布及其对基片平面度的影响规律,从化学机械抛光的实际出发,建立了抛光过程的接触力学模型和数学模型.利用有限元方法对接触压强分布进行了计算和分析,并利用抛光实验对计算结果进行了验证;获得了化学机械抛光过程硅片与抛光垫之间的接触表面压强分布形态,以及抛光垫的物理参数对压强分布的影响规律,确定了接触压强分布形态和硅片平面度误差的关系.结果表明,接触压强的分布是不均匀的,而且在硅片外径邻域内接触压强最大,从而导致被加工硅片产生平面度误差和塌边现象.合理地选择抛光垫的弹性模量和泊松比,可以改善接触表面压强分布的均匀性,从而使硅片有效区域的平面度变得更好.

Contact Pressure Distribution & Macro-topography Generating Mechanisms of Silicon Wafer Polishing

In order to obtain the contact pressure distribution and its effect on the flatness of the silicon wafer in the chemical mechanical polishing process,the mechanical and mathematical models were developed from the aspect of practical application.The contact pressure distribution was calculated and analyzed with ANSYS, and then confirmed by polishing experiments.The contact pressure distribution and how it was affected by the parameters of a polishing pad were obtained,and the relationship between the non-uniform distribution of the contact pressure and the flatness errors of the polished silicon wafer was determined.The results show that the contact pressure distribution is non-uniform,with the maximum pressure occurring on the edge of the silicon wafer,which induce the flatness errors and the edge subsiding.Selecting Young’s modulus and Poisson’s ratio of the polishing pads properly can improve the uniformity of the contact pressure distribution and the flatness of the functional region of the wafer.