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化学机械抛光中晶圆表面材料去除的非均匀性是影响抛光质量的主要因素之一。材料去除非均匀性直接影响上层布线的质量。通过对抛光垫与晶圆表面不同接触状态下的摩擦学分析,得到抛光垫与晶圆不同接触状态下摩擦系数。采用归一化摩擦系数方法,简化了抛光垫与晶圆之间的接触行为,并建立了基于接触机理的化学机械抛光有限元模型。分析了不同工艺参数下晶圆表面应力分布以及层间剪切应力分布规律,得到了工艺参数对表面材料去除非均匀性和低k介质层材料剥离的影响规律。采用因子设计方法分析了影响晶圆表面材料去除非均匀性的工艺参数的因素水平,为化学机械抛光工艺优化提供了理论依据。
Chemical mechanical polishing wafer surface material removal of non-uniformity is one of the main factors affecting the polishing quality. Material removal non-uniformity directly affects the quality of the upper wiring. Through the tribological analysis of the polishing pad and the wafer under different contact conditions, the friction coefficient of the polishing pad and the wafer under different contact conditions is obtained. Using the normalized friction coefficient method, the contact between the polishing pad and the wafer is simplified, and the chemical mechanical polishing finite element model based on the contact mechanism is established. The distribution of stress on the wafer surface and the distribution of interlaminar shear stress under different process parameters were analyzed. The influence of process parameters on the nonuniformity of the surface material and the delamination of the low k dielectric layer material was obtained. Factorial design method was used to analyze the factors that affect the process parameters of non-uniformity of wafer surface material removal, which provided a theoretical basis for chemical mechanical polishing process optimization.