Despiau-Pujo, Emilie (2009) Etching of III-V semiconductors in inductively coupled chlorine plasmas. PhD thesis Physique, Laboratoire de Physique des Plasmas, EP/X p.220.

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Abstract

This thesis work is part of an emerging area of research: plasma etching for photonics and optoelectronics. The control of etching processes requires to predict the energies and fluxes of plasma species as function of the discharge parameters, and to understand the mechanisms of plasma-surface interaction. This work addresses both aspects through fluid modeling and atomistic simulations. We have developed molecular dynamics simulations to understand the fundamental mechanisms that govern the sputtering of two III-V semiconductors (GaAs and GaN) by low energy Ar ions. This numerical study, confronted to a series of experiments, shows that the composition of bombarded materials is modified over a few tens of angstroms and that sputtered Ga atoms leave the surface with energies sufficient to damage the etching sidewalls and passivation layers, in processes dominated by ion bombardment. We have also worked on fluid simulations (two-dimensional and global) to understand the dynamics of inductive chlorine discharges and to study the transport of species within the plasma bulk. Comparisons between model and experiments show that the 2D fluid model overestimates the charged particles densities but predicts fairly well the neutral and ionic composition of the plasma. The global model is the first step toward the modeling of the low power regime of inductive chlorine plasmas ; it has allowed us to study the instabilities that develop at the E to H transition.

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