Experimental Validation of Model of Electro-Chemical-Mechanical Planarization (ECMP) of Copper

This paper describes the development of a COMSOL model of Electro-Chemical-Mechanical Planarization (ECMP) that was validated with experimental data. ECMP is used for processing of semiconductor wafers. We developed a 2D model of flow of phosphoric acid solution (the electrolyte) between two parallel plates that focuses on the physics and electrochemistry in ECMP. The model includes steady-state copper dissolution and species transport inside the electrolyte, ion transport including convection, diffusion, and migration, and electrodic reactions represented by the Butler-Volmer equation. Experiments were conducted to measure the anode current at various spatial locations for different electrode potentials. The agreement between experimental data and the COMSOL model predictions was found to be very good.