Atomic layer etching by gas cluster ion beams with acetylacetone

Atomic layer etching (ALE) of metals using gas cluster ion beams (GCIBs) and acetylacetone vapor was demonstrated. Since GCIBs are an aggregate of thousands of gas atoms or molecules, the energy/atoms or energy/molecules can be easily reduced down to several eV, which is ideal for the energetic beam in the removal steps of ALE. In addition, GCIB creates the transient high-temperature and high-pressure condition on a target surface, surface reactions between the adsorbed molecules and target atoms are enhanced even at low substrate temperature. In the previous study, we have reported ALE with oxygen GCIB using acetic acid vapor. In this study, acetylacetone (acac) was used as an organic vapor. Atomic layer etching of Cu films with 5 kV O 2 -GCIB and acac were demonstrated successfully. From the etching experiment with continuous O 2 -GCIB irradiation, etching for metals (Cu, Co, Ni, Ru, Ta) are also enhanced by the addition of acac during O 2 -GCIB irradiation. ALEs for these metals are also expected.