化学机械抛光中材料去除非均匀性及因子分析

Analysis on the Non-Uniformity and Factors of the Material Removal in Chemical Mechanical Polishing

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。

Material removal non-uniformity of the wafer surface is one of the main factors which affects the polishing quality during chemical mechanical polishing（CMP）.The material removal non-uniformity mainly depends on the quality of the upper wiring.The friction coe-fficients for different contact statuses between the pad and wafer were got based on the tribology analysis.The contact behavior between the pad and wafer was simplified with the normalized friction coefficient method,and the finite element model based on the contact mechanism during the chemical mechanical polishing was established.The surface stress distribution of the wafer and interlayer shear stress distribution for different process parameters were analyzed,and the effect of the process parameters on the wafer surface material removal non-uniformity and the delamination of the low-k dielectric layer was obtained.The factor level for the effect of process parameters on the wafer surface material removal non-uniformity was discussed through a statistical factorial design me-thod,providing the theory basis for the process optimization of chemical mechanical polishing.