Area-selective plasma-enhanced atomic layer etching (PE-ALE) of silicon dioxide using a silane coupling agent

A novel route to achieve an ideal plasma-enhanced atomic layer etching of silicon dioxide with self-limiting deposition and area-selective feature over silicon nitride is demonstrated in this work using a silane coupling agent and argon plasma. While monitoring the film thickness of silicon dioxide, self-limiting characteristics in both modification and etching steps are attained. Moreover, the dosing step revealed the selective formation of a modification layer on the oxide over the nitride film. In situ infrared spectroscopy results suggest the surface functionalization of the hydroxyl terminal groups of the oxide with the silane coupling agent to form the self-limiting modification layer at a relatively low substrate temperature. Compared to the previously reported fluorocarbon precursors, a higher etch yield for SiO₂ was calculated, showing a promising option to meet the increasing demands in semiconductor production.