Plasma-assisted thermal atomic layer etching of Al2O3

In this paper, we report on plasma assisted thermal Atomic Layer Etching (ALE) of Al 2 O 3 . The surface was modified via a fluorine containing plasma without bias power. The removal was accomplished by a thermal reaction step using tin-(II) acetylacetonate Sn(acac) 2 . After a few cycles, material removal stopped and growth of a Sn-containing layer was observed. Insertion of a hydrogen plasma step was found to remove the Sn layer and a continuous material removal of 0.5 A/cycle was measured. The results show that plasma assistance can be used to realize thermal ALE of Al 2 O 3 . Specifically, plasma can be used both in the fluorination step and to keep the surface free from contaminations.