Mechanistic Studies of Atomic Layer Deposition and Thermal Atomic Layer Etching Processes of Various Oxide Thin Films

Atomic layer deposition (ALD) and atomic layer etching (ALE) will be the key techniques for sub10 nm node technology. Establishing a mechanistic understanding of the underlying surface chemistry is crucial for the optimization ALD/ALE processes and their use in microelectronics device fabrication. However, non-traditional reactions occurring concurrently with ALD/ALE complicate the deposition/etching process. Herein, several mechanisms are investigated for the ALD and thermal ALE of various oxide thin films. The first study demonstrates how the coreactant can affect the deposition process for TiO2 ALD from a cyclopentadienyl-based precursor. The next study highlights an important, but mostly overlooked, phenomenon of precursor/substrate reactivity during an ALD process. The third study describes the ALD of Sc2O3 thin films using a novel precursor with ozone. The final study reveals the limitations of thermal ALE processes for Al2O3 and SiO2 thin films, and proposes possible solutions to mitigate contamination issues inherent to the etching of these films. These investigations emphasize the need for surfacesensitive characterization techniques to unravel the complexities of these ALD/ALE processes.