Electrochemical corrosion behavior and theoretical simulation of cobalt in chemical mechanical polishing process

The chemical mechanical polishing (CMP) process for cobalt (Co) interconnects is essential for the fabrication of integrated circuits with feature sizes below 10 nm. However, achieving high removal rates coupled with low dissolution rates remains a significant challenge. In this work, we have developed a dual-functional polishing slurry, which integrates ethylenediamine tetramethylphosphonic acid (EDTMPA) as a complexing agent, and octahydroxamic acid (OHA) as a corrosion inhibitor. The novel slurry-derived Co CMP meets ideal situation, delivering a removal rate (RR) of 246 nm/min, a dissolution rate (DR) of 0.8 nm/min, and a root mean square (RMS) roughness (Sq) of 2.31 nm. Experimental data and theoretical calculations reveal that the improved CMP performance results from the effective complexation of EDTMPA with Co ions. Furthermore, the adsorption of OHA as a corrosion inhibitor on the Co surface effectively counteracts the corrosion induced by EDTMPA. The development of this novel polishing slurry presents a strategy that harmoniously combines reduced process time with enhanced surface quality, holding the potential to significantly influence the CMP field.