一种新型的机械化学抛光模型

分析了机械化学抛光(CMP)过程中氧化剂与磨粒的化学机械协同作用机理,将CMP过程分为化学作用主导阶段和机械作用主导阶段.应用微观接触力学和颗粒粒度分布理论,对这两个阶段分别建立了表征芯片表面材料去除率的数学模型,根据这两个阶段的平衡点推出了表征芯片表面氧化膜生成速度的数学表达式.模型综合考虑了机械和化学作用因素、磨粒的浓度、磨粒的粒度分布特性及磨粒/芯片/抛光盘的材料特性参数对CMP过程的影响,并通过图表分析了磨粒体积浓度、磨粒平均粒径粒度、磨粒粒度分布宽度以及氧化剂浓度对CMP过程芯片表面材料去除率的影响规律.

A New Model for Chemical Mechanical Polishing

Based on mechanism between chemical action of oxidant and mechanical action of abrasives,the CMP process is divided into two cases:chemical effect dominant and mechanical effect dominant.A new mathematical model characterizing the material removal rate in CMP process is developed by using micro-contact mechanics and particle size distribution theory.The models for the two phases are developed based on mechanical effect,which considers the influence of most valuables in the CMP process including pad properties(modulus,hardness,asperity sizes and distribution),processing variables(down-pressure,velocity) and slurry characteristics(abrasive mechanical effect,oxidant chemical effect).Besides,from the balance point of the two cases,a new model,which can quantitatively describes the generation rate of oxidized layer on wafer surface in CMP,is developed.Finally,the effect of the mechanical factors(abrasive concentration in slurry,abrasive diameter,abrasive size distribution width),chemical factor(oxidant concentration in slurry) on the material removal rate MRR are discussed and analyzed illustratively.