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UID:3622-1775642400-1775642400@www.cnrs-imn.fr
SUMMARY:Tojo RASOANARIVO (PCM) thesis defense
DESCRIPTION:Wednesday\, April 8 at 10:00 a.m.\n \n\nMultiscale modeling of GaN atomic layer etching in chlorinated plasmas\nSummary: Gallium nitride (GaN) is a key material for power electronics devices operating in the radio frequency domain. The miniaturization of architectures makes nanometric control of etching critical. Conventional etching processes using continuous cold plasmas in chlorinated chemistries offer high speeds\, but can induce defects in the material\, impacting device performance and reliability. Atomic layer etching (ALE)\, a cyclic process alternating chemical surface modification and activation by low-energy ion bombardment\, aims to control etching at the atomic scale while improving surface finish. This thesis focuses on the development of a multiscale model of GaN FTA in Cl₂/Ar plasmas. The simulator couples a dynamic global model describing plasma species fluxes and densities with a Monte-Carlo sheath model providing ion energy and angular distribution functions. The results of these first two models are then exploited by a kinetic Monte-Carlo surface model to describe chlorine-induced modification reactions and ion bombardment selectivity at the GaN surface during the ALE process. This surface model is fed by an ab initio study describing Cl-GaN(0001) interactions. Ultimately\, the simulator package makes it possible to link mesoscopic parameters to plasma/surface interactions at the atomic scale\, to gain a deeper understanding of the mechanisms involved and optimize process performance\, such as post-etch GaN surface finish and control of etched thickness per cycle. Ultimately\, this work can be integrated into a digital twin of GaN ALE processes\, to guide the optimization and industrialization of atomic-scale etching.          \nKeywords: semiconductor\, cold plasma process\, etching\, modeling\, multiscale \n\nMultiscale modelling of Atomic Layer Etching of GaN in chlorinated plasmas\nAbstract: Gallium nitride (GaN) is a key material for power electronics devices operating in radiofrequency ranges. The downscaling of architectures makes nanometric control of etching critical. Conventional etching processes using continuous plasmas in chlorinated chemistries offer high etch rates but can induce defects in the material\, degrading device performance and reliability. Atomic layer etching (ALE)\, a cyclic process alternating between chemical surface modification and activation by low-energy ion bombardment\, aims to control etching at the atomic scale while improving the surface state. This thesis focuses on the development of a multiscale model for ALE of GaN in Cl₂/Ar plasmas. The simulator combines a global dynamic model describing plasma species fluxes and densities with a Monte Carlo sheath model providing ions energy and angular distribution functions. The results from these first two models are then used as inputs for a kinetic Monte Carlo surface model to describe chlorine-induced modification reactions and ion bombardment selectivity on the GaN surface during ALE processing. This surface model relies on ab initio study describing Cl-GaN(0001) interactions. The simulator associates mesoscopic parameters to plasma/surface interactions at the atomic scale in order to deepen understanding of the involved mechanisms and optimize process performances\, such as the GaN surface state after etching and etched thickness per cycle. Ultimately\, this work can be integrated into a digital twin for GaN ALE processes to guide the optimization and industrialization of atomic-scale etching.          \nKeywords: semiconductor\, low temperature plasma process\, etching\, modelling\, multiscale
URL:https://www.cnrs-imn.fr/en/event/tojo-rasoanarivo-pcm-thesis-defense/
LOCATION:Amphi IMN
ATTACH;FMTTYPE=image/jpeg:https://www.cnrs-imn.fr/wp-content/uploads/2026/02/rasoanarivo_tojo.jpg
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