Prospects for Thermal Atomic Layer Etching Using Sequential, Self-Limiting Fluorination and Ligand-Exchange...

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Atomic layer etching (ALE) is crucial for advanced semiconductor fabrication.
• Existing ALE methods often require complex processes or harsh conditions.
• Developing thermal ALE offers a pathway for more controlled and selective material removal.

Purpose of the Study:

• To demonstrate a novel thermal atomic layer etching (ALE) process for Al2O3 and HfO2.
• To explore the potential of sequential fluorination and ligand-exchange reactions for ALE.
• To establish a thermal pathway for ALE that complements atomic layer deposition (ALD).

Main Methods:

• Utilized sequential, self-limiting reactions involving hydrogen fluoride (HF) and tin acetylacetonate (Sn(acac)2).
• Applied thermal energy to drive the etching process, reversing atomic layer deposition (ALD) principles.
• Investigated the chemical selectivity offered by ligand-exchange reactions.

Main Results:

• Successfully demonstrated thermal ALE of Al2O3 and HfO2.
• Established a new thermal pathway for ALE, distinct from traditional ALD.
• Showcased the potential for isotropic etching and conformal coating in high-aspect-ratio structures.

Conclusions:

• Thermal ALE using fluorination and ligand-exchange is a viable technique for semiconductor fabrication.
• This method offers potential for selective etching and creating ultrasmooth thin films.
• Future work could involve radicals or ions to enhance ALE rates and achieve anisotropic etching.