Jianfeng Luo
Sponsored
By: NSF and UC SMART
Abstract
In this paper, the abrasion mechanism in solid-solid contact mode of chemical mechanical
polishing (CMP) process is investigated in detail. Based on assumptions of plastic contact over
wafer-abrasive and pad-abrasive interfaces, the normal distribution of abrasive size and an assumed
periodic roughness of pad surface, a novel model is developed for material removal in CMP and
formulations are presented to predict the material removal rate. Compared with previous work, such as
Preston?s equation, the model proposed integrates not only process parameters including pressure and
velocity but other important input parameters including the wafer hardness, pad hardness, pad
roughness, abrasive size and abrasive geometry into the same formulation to predict the material
removal rate. It is found that the down pressure dependence of material removal rate (MRR) are related
to a probability density function. Compared with experiment results of material removal rate, the model
accurately predicts MRR. By further verification of the model, a better understanding of the fundamental
mechanism involved in the CMP process can be obtained.
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