Title: Materials removal principle in nano-precision wafer polishing based on probability theory and micro-contact mechanism
Authors: Shiwen Du; Yongtang Li
School of Materials Science and Engineering, Taiyuan University of Science and Technology, Taiyuan, 030024, China.
School of Materials Science and Engineering, Taiyuan University of Science and Technology, Taiyuan, 030024, China
Abstract: Based on assumptions of micro-contact over wafer-abrasive and pad-abrasive interfaces, the Gaussian distribution of abrasive size and an assumed normal distribution of pad surface, a novel model for material removal in chemical mechanical polishing is developed. The chemical effect is taken into account by parameter Hw (the hardness of the chemically modified surface layer on wafer). The model proposed integrates process parameter, wafer harness, pad topography, pad properties and abrasive distribution into the model to predict the material removal rate (MRR). Based on the deformation of hyper-elastic asperities attached to a liner-elastic pad, asperity scale MRR is introduced. Active particles is calculated by probability theory and the wafer scale MRR is proposed. Compared with the experimental results, the model accurately predicts MRR.
Keywords: chemical mechanical polishing; CMP; material removal rate; MRR; surface topography; probability theory; micro-contact mechanism; normal distribution; wafer hardness; pad properties; abrasive distribution; nano-precision wafer polishing; nanotechnology.
Int. J. of Nanomanufacturing, 2012 Vol.8, No.3, pp.202 - 211
Submission date: 29 Sep 2011
Date of acceptance: 01 Dec 2011
Available online: 24 May 2012