Self-Limited Behavior Study on Dielectric Quasi-Atomic Layer Etching for Selectivity Achievement

Atomic layer etching (ALE) has attracted wide attention in the continuous downscaling progress of semiconductor devices. It is achieved by cyclic process of surface modification (deposition step) and subsequent removal of modified layer (etch step). The self-limited feature is the key for ALE to fulfill atomic-scale etch precision and high material selectivity. In this work, self-limited behavior was explored in dielectric ALE with fluorocarbon plasma. The effect of ion energy was studied by pure argon sputtering on different substrates. The etch behaviors of silicon oxide (SiO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>) and silicon nitride (SiN<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf>) at different surface states were compared to provide an insight to selectivity achievement. Moreover, the LF-assisted deposition was proved to be valuable for realizing high selectivity, promoting wide application of ALE in advanced semiconductor manufacturing.