Surface modification by chlorine-chemistry during atomic layer etching of aluminum nitride: A first principles-based analysis

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 (Cl) and molecular chlorine (Cl2) on the Al-terminated 0001 surface of aluminum nitride (AlN). 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 the AlN atomic layer etching process in semiconductor fabrication.