Gallium Nitride (GaN) plasma etch for high efficiency µLED applications ; Gravure Plasma du Nitrure de Gallium pour la réalisation de micro LEDs à hautes performances

Through the development of the internet of things and virtual and augmented reality, increase of microdisplay need appeared. Gallium Nitride (GaN) microLED (µLED) seem to be a promising solution thanks to its electro-optical properties like its wide direct band gap. Nevertheless, GaN µLED efficiency drop significantly when their size shrinks, due to damages induced by singularization process.This thesis aims to understand GaN damages apparition during the plasma etching process and then their reduction. To study mesas sidewall damage after the etching, a new experimental set up using cathodoluminescence has been developed. A standard process using Cl2/BCl3/Ar chemistry is studied to characterize GaN damages. Then through a dichotomy of the chemistry, chlorine turns out to be the main damaging species within the plasma, both on sidewall and bottom trench. Plasma parameters (density and ion bombardment energy) and the damaging effect of the hard mask material have been studied with a plasma chemistry reduced to chlorine only. Noting divergent results with the ones reported in the literature, a comparative study between plan c Ga and N polarities have been carried. This study highlight that N face GaN is mainly damaged by plasma chemical component (reactive species) while Ga face GaN is by plasma physical component (ion bombardment). An etching mechanism is finally proposed to explain those differences. ; Avec le développement de l’internet des objets et des réalités augmentées et virtuelles, la demande en micro-écran très résolu est apparue. Des microLED (µLED) à base de Nitrure de Gallium (GaN) semble une solution prometteuse grâce à ses propriétés électro optiques, notamment son grand gap direct. Les µLED à base de GaN subissent cependant une chute drastique de leur efficacité lorsque leur dimension diminue en raison, au moins partiellement, de dommages induits sur les flancs par l’étape de singularisation.Ces travaux de thèse se concentrent sur la compréhension et la réduction de l’endommagement du GaN au cours ...