Digital Twins for Plasma-Surface Interactions in Atomic Layer Etching

A digital twin for plasma tools in semiconductor processing requires a bidirectional interplay between the physical plasma system and an appropriately defined computational or virtual representation that evolves with time. [1] Any physics-based digital twin of a plasma tool will need a reduced order model (ROM) of plasma-surface interactions. I present one version of a ROM for simulating a plasma atomic layer etching (ALE) process. [2] The ROM is based on a transient version of a well-established surface site balance model.[3] Molecular dynamics (MD) simulations of ALE of Si using Cl₂/Ar⁺ cycles are first validated with experimental measurements [4] and then used to provide values for parameters for the ROM. The ROM is computationally much faster than the MD simulations and is shown to reproduce the MD results as well as additional, and previously unexplained, experimental results.



[1] National Academies of Sciences, Engineering, and Medicine. 2024. Foundational Research Gaps and Future Directions for Digital Twins. Washington, DC: The National Academies Press.

[2] J. R. Vella et al., Plasma Sources Science and Technology, submitted, 2024.

[3] J. P. Chang et al., J. Vac. Sci. Technol. A, 1997, 15, 1853-1863.

[4] J. R. Vella et al., J. Vac. Sci. Technol. A, 2023, 41, 062602.