Chemical-Mechanical Impact of Nanoparticles and pH Effect of the Slurry on the CMP of the Selective Layer Surfaces

Filip Ilie,George Ipate

doi:10.3390/lubricants5020015

Abstract

This paper provides a tribochemical study of the selective layer surface by chemical mechanical planarization (CMP). CMP is used to remove excess material obtained in the process of selective transfer. The paper aims at a better understanding of the planarization (polishing) and micromachining. The planarization becomes effective if the material removal rate (MRR) is optimal and the surface defects are minimal. The pH of the slurry plays a very important role in removing the selective layer by CMP, and hydrogen peroxide (H2O2) is the most common oxidizer used in CMP slurry. The purpose of this paper is the analysis of the pH effect on the etching rate (ER) and on the behavior of selective layer polishing by a constant concentration of H2O2 and the influence of nanoparticles size and concentration on selective layer surface CMP. The nanoparticle size used is 250 nm. The MRR results through CMP and ER have been shown to be influenced by the presence of oxides on the selective layer surface and have been found to vary with the slurry pH at constant H2O2 concentrations. The CMP slurry plays an important role in the CMP process performance and should be monitored for optimum results and minimal surface defects. The paper analyzes the impact of chemical-mechanical, inter-nanoparticle, and pad-nanoparticle-substrate interactions on CMP performance, taking into account the state of friction at the interface, by measuring the friction force. Selective layer CMP optimization studies were required to control the chemical and mechanical interactions at the interface between the slurry and the selective layer, the slurry chemistry, the properties, and the stability of the suspended abrasive nanoparticles.

Highlights

The selective transfer phenomenon takes place in the friction process of two materials and in the presence of specific lubricants by transferring the material from one element of a friction couple to the other
It is essential that, during the chemical mechanical planarization (CMP) process, the superior characteristics of a sample to be polished at a rate higher than that of the lower characteristics leads to a surface planarization
This requires that the pad has to be rigid enough so that it does not deform the supplementary recessed sample areas and the slurry does not etch the lower characteristics during CMP

Summary

Introduction

The selective transfer phenomenon takes place in the friction process of two materials and in the presence of specific lubricants by transferring the material from one element of a friction couple to the other. This transfer can be performed safely if there is a favorable energy, a relative movement, and if, in the friction area, is a copper-based material and a suitable lubricant (glycerin or a special lubricant) [1]. By scanning with an atomic force microscope (AFM) of the selective layer after the chemical mechanical planarization (CMP) process it is found that the surface of the oxide layer is removed at different rates depending on the depth of removal and the pH of the solution. CMP is a material removal and surface smoothing process, which is possible by the combination of chemical and mechanical interactions [4,5,6,7,8,9]

Objectives

Results

Conclusion