Atomic Layer Etching of Aluminum Nitride: Mechanistic Insights from First-Principles Studies of Chlorine Chemistry

Using first-principles density functional theory calculations in combination with the climbing-image nudged elastic band method, we investigated the adsorption, desorption, and diffusion of atomic chlorine and molecular chlorine on the Al terminated 0001 surface of aluminum nitride. Our results reveal that both atomic Cl and Cl2 exhibit a chemisorption character with high binding energies. Calculations revealed that the splitting pathway of Cl2 on the Al terminated AlN 0001 surface is a barrierless and exothermic process. These findings provide new microscopic-scale insights into halogen-insulator surface interactions and opportunities for new strategies in optimizing AlN atomic layer etching process in semiconductor fabrication.