Si-Cl₂-Ar⁺ Atomic Layer Etching Window: A Fundamental Study Using Molecular Dynamics Simulations and a Reduced Order...

Area of Science:

• Materials Science
• Surface Science
• Plasma Physics

Background:

• Silicon atomic layer etching (ALE) is critical for microelectronics fabrication.
• Contradictory experimental results exist regarding the ALE window for Si-Cl2-Ar+ systems.
• Understanding the ALE window is essential for process control and optimization.

Purpose of the Study:

• To investigate the properties of the ALE window for silicon etching using Cl2 and Ar+.
• To elucidate the ion energy range defining the ALE window.
• To resolve discrepancies in experimental findings regarding the ALE window.

Main Methods:

• Molecular dynamics (MD) simulations were employed to model the etching process.
• A reduced order model (ROM) was developed and utilized for analysis.
• The study analyzed the interplay between ion energy, chemical reactions, and physical sputtering.

Main Results:

• Both MD simulations and the ROM identified a narrow ALE window between approximately 15 and 20 eV for normal incidence Ar+ ions.
• The etch yield per cycle was found to be less than one atomic layer.
• Modifications to the ROM, specifically altering the physical sputtering threshold, demonstrated an expansion of the ALE window, highlighting the significance of sputtering thresholds.

Conclusions:

• The Si-Cl2-Ar+ ALE system exhibits a narrow ALE window, primarily influenced by the balance of chemical and physical sputtering.
• The findings provide a theoretical basis for understanding and controlling silicon ALE processes.
• Further research using the ROM can explore dependencies on ion fluence and other process parameters.