Slurry Activation for Enhanced Surface Redox Reactions in CMP

Abstract

A novel add-on hardware device is placed near the point of slurry dispense that can instantaneously activate slurry performance during polishing via megasonic irradiation. This new technology (Flucto-CMP® is able to overcome the inherent polisher-slurry weaknesses such as wafer-level defects, process vibrations, cost of ownership, slurry waste, remval rate (RR), and RR selectivity. Flucto-CMP® has been successfully applied to various types of CMP slurries resulting in significant increases in the removal rates of copper, SiC, borosilicate hard mask, ILD, TiN, and silicon carbide through chemical alteration of the passivation layer needed for material removal. Specifically, for copper CMP, using Flucto-CMP®, we see an up to 31% boost in RR which is well correlated with the amount of reactive oxidizing species generated through irradiation as well as the measured relative indentation depth of the passivation layer. In addition to boosts in RR, for copper, we see a 50X drop in the variance of shear force and a 5X drop in the variance of normal force when Flucto-CMP® is used. This dramatic reduction in process vibration for copper soft-landing processes ought to reduce wafer-level defects. Much greater rate improvements are observed when polishing SiC, and borosilicate hard masks.