A Model for Design Optimization of Electrochemical Mechanical Polishing Polish Pad

Bian Yanfei

doi:10.11648/j.ijmea.20170504.16

Abstract

The polishing pad plays a vital role in achieving the desired removal rate and level of surface planarity during the electrochemical mechanical planarization (ECMP) process. Material removal rate (MRR) and within wafer non-uniformity (WIWNU) are two important factors in determining the polishing performance. In this work, a theoretical model for predicting the radial distribution of tribasic ammonium citrate (TAC) concentration on the wafer is proposed. The experimentally measured MRR was found as a function of the TAC concentration in the slurry. Hence, the model could not only predict the removal rate at a given point on the wafer surface, but also reflect the WIWNU. Model predictions are in good agreement with the experimental data. The proposed model are used to perform an analysis of the effect of pad designs on the MRR and WIWNU of the wafer.

Highlights

Chemical mechanical polishing (CMP) technology has become a widely used technique for planarization removal
In order to overcome the inherent defects of CMP, electrochemical mechanical polishing (ECMP) technology has been introduced and gotten more and more attention [4]
Bian Yanfei et al.: A Model for Design Optimization of Electrochemical Mechanical Polishing Polish Pad surface and the pressures at its neighboring nodes as well as the liquid flow rates in its neighboring grooves obey the relationship given by Eq (8)

Summary

Introduction

Chemical mechanical polishing (CMP) technology has become a widely used technique for planarization removal. Traditional CMP technology faces severe challenges due to the introduction of new porous low-k dielectric material, which may be damaged in the CMP process [1,2,3]. In order to overcome the inherent defects of CMP, electrochemical mechanical polishing (ECMP) technology has been introduced and gotten more and more attention [4]. The planarization performance of ECMP is significantly influenced by polishing pad characteristics [5,6,7]. Pad structure and properties are important to determine the removal rate and within wafer nonuniformity (WIWNU) during ECMP process, which are very important factors in determining the polishing performance. The design of the pad is critical in achieving the desirable ECMP performance

The Model Used to Predict the Removal Rate and WIWNU

Experimental Procedure

Conclusion