Dual functionality of DTPMP and OHA: Enhancement in removal rates and excellent surface quality of cobalt CMP

Abstract

This study investigates a novel slurry composition for the chemical mechanical polishing (CMP) of cobalt (Co) interconnects, addressing the critical demands of semiconductor device miniaturization to 10 nm feature sizes. Utilizing diethylene triamine penta methylene phosphonic acid (DTPMP) as a complexing agent and octyl hydroxamic acid (OHA) as an inhibitor, we demonstrate that the dual functionality of DTPMP and OHA optimizes Co removal rates while minimizing static etch rates, achieving a delicate balance between high removal rate and surface integrity. This interaction results in a controlled Co removal rate of up to 2078.2 Å/min, a dissolution rate as low as 19.2 Å/min at optimized concentrations, and a root mean square (RMS) roughness (Sq) of 0.744 nm. Experimental data and theoretical simulation studies reveal enhanced complexation due to the increased deprotonation of the phosphate group in DTPMP, laying a foundation for developing environmentally friendly and efficient CMP applications across various metal interconnects in advanced semiconductor devices.