Chalcogenide glasses are materials of interest for many applications: in phase-change memories, for example optical storage (CD-RW, DVD-RAM, Blu-ray Disks) or more recently Storage Class Memory, as a selector in 3D architecture resistive memories (OTS selector) or as an active medium for non-linear optics and reconfigurable photonics. In the latter case, the production of metasurfaces with controllable optical refractive indices and the development of photonic actuators is a subject of renewed interest, given the unique optical properties of these materials.
In this field, CEA-LETI is one of the major international players in the development of thin films of chalcogenide glasses and phase-change materials, as well as in the characterization and understanding of their unusual physical properties. Today, although these materials are well mastered at industrial level for memory applications, it is nevertheless necessary to work on integrating these innovative, high-performance materials into small-scale structures while preserving their unique physical properties. Initial integration studies carried out during a previous thesis showed that the etching and stripping process steps were far from being optimized, even though they are critical if the properties of the material are not to be degraded during the production of photonic structures. Although essential for process control, the etching mechanisms of chalcogenide glasses are relatively poorly described in the literature, with the exception of Ge2Sb2Te5 used in phase-change memories.
This theme is therefore innovative and has real added value. The aim of the thesis is therefore to study and understand the etching mechanisms of GeSbSeTe-based chalcogenide glasses in order to control the profile and size of the transferred structures. The work to be carried out is highly experimental and will take place mainly in the LETI's 300 mm clean room. The candidate will have access to state-of-the-art chalcogenide materials thin films, an industrially designed plasma etching reactor and a wide range of characterization facilities. This thesis will be carried out in collaboration with the LETI advanced materials deposition service and the optoelectronic devices applications department (DOPT).