Corrosion control of copper wiring by barrier CMP slurry containing azole inhibitor: Combination of simulation and experiment

Abstract

In the chemical mechanical polishing (CMP) process of barrier layer of multilayer copper wiring in integrated circuits, it is necessary to add appropriate corrosion inhibitor into the polishing slurry to protect copper from corrosion, reduce the height difference with the barrier material and achieve high planarization. There are few literatures about the behavior of inhibitors on metal surface in CMP studied by computational chemistry. In this study, density functional calculation and Monte Carlo simulation combined with electrochemical and CMP experiments were used to investigate the adsorption and corrosion inhibition of azole inhibitors (BTA, TAZ and TT-LYK) on copper wiring in barrier layer in glycine/hydrogen peroxide reference solution system. The results show that all the azole inhibitors in the reference solution system have obvious corrosion inhibition on copper surface, and the inhibition effect of azole inhibitors was positively correlated with the increase of concentration. In particular, TT-LYK has a stronger corrosion inhibition effect, which was verified by electrochemical and CMP measurements, MD results support there are more adsorption sites between TT-LYK and copper surface. In addition, the stability of the solution containing TT-LYK and the state of copper surface evaluated by SEM after TT-LYK treatment are better. The combination of molecular dynamics methods and experiments approach may well be able to study corrosion inhibitors at the micro level and foretell better molecular structures which is more suitable to improve the efficiency of wiring corrosion inhibition.