Reaction Mechanism and Selectivity Control of Si Compound ALE Based on Plasma Modification and F-Radical Exposure

Area of Science:

• Materials Science
• Chemical Engineering
• Surface Chemistry

Background:

• Atomic Layer Etching (ALE) is crucial for semiconductor fabrication.
• Selective etching of diverse silicon compounds (SiN, SiC, SiCO, SiO₂) presents challenges.

Purpose of the Study:

• To investigate the selective etching of Si compounds using H₂ or N₂ plasma modification followed by fluorine radical exposure.
• To understand the mechanism behind etching selectivity in silicon compounds.

Main Methods:

• Utilized H₂ and N₂ plasma modification followed by fluorine radical exposure for ALE.
• Employed in situ spectroscopic ellipsometry (SE) and Fourier-transform infrared spectroscopy (FTIR).
• Supported findings with ex situ analysis techniques.

Main Results:

• H₂ plasma modification selectively etches SiN, SiC, and SiCO over SiO₂.
• N₂ plasma modification selectively etches SiC and SiCO over SiN and SiO₂.
• Formation of a hydrogen-rich layer is essential for ALE and selectivity.

Conclusions:

• The study elucidates the mechanism of selective etching in Si compounds via plasma modification.
• Insights gained are expected to improve ALE selectivity for Si compounds.
• The approach may be extendable to other materials like Ti and Hf compounds.