The Role of EDTA-2K in the Chemical Mechanical Polishing of Aluminum

Abstract

As the characteristic size of integrated circuits has continued to shrink, there has been increasing interest in using aluminum (Al) as the gate material. In this paper, we have looked at the role ethylenediamine tetraacetic acid dipotassium (EDTA-2K) plays in the chemical mechanical polishing (CMP) of Al for use as a gate material. Currently, the preferred approach to CMP is to use colloidal silica as an abrasive, EDTA-2K as the complexing agent, and H2O2 as the oxidant. We have explored the influence of EDTA-2K and H2O2 on the Al removal rate (RR) during CMP. The results show that when the concentration of EDTA-2K is 1 wt%, the removal rate reaches 3450 Å min−1, and the surface roughness is 0.425 nm. The mechanism of the action of EDTA-2K during CMP was studied through particle size distribution analysis, X-ray photoelectron spectroscopy (XPS), electrochemical tests, and UV–visible (UV–vis) spectroscopy. The results show that EDTA-2K reacts with aluminum ions (Al3+) to form a soluble Al-EDTA complex, which promotes the corrosion rate on the Al surface and thus increases the removal rate of Al.