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Link visio: to come
The defence will be in English.
Abstract: Diamond has garnered significant attention in recent years due to its exceptional properties, positioning it as a promising material for advanced electronic and optical devices. However, realizing the full potential of diamond in these applications requires overcoming significant challenges, particularly in the fabrication and etching processes. Although the very strong carbon-carbon bonds of diamond give it highly desirable properties, they also make etching processes ineffective or poorly adapted. Conventional etching methods have been limited by surface and subsurface damage, which degrade device performance. Moreover, the low efficiency of these methods makes deep etching impossible. Additionally, defects and rough sidewalls created during etching pose significant barriers to the advancement of vertical designs. This thesis investigates three advanced diamond etching techniques aimed at achieving precise, controllable, defect-free deep etching and anisotropic etching with smooth sidewalls.
The challenge of achieving precise, controllable, and defect-free etching has been addressed by the successful development of two plasma Atomic Layer Etching (ALE) processes for diamond using different gas/ion combinations. An ALE process consists of sequences of cycles, each combining two auto-limiting steps: modification and removal. This auto-limiting characteristic allows ALE to achieve atomic-scale control, where, during each cycle, one (or a fixed number of) monolayer is removed. This technique provides a key and powerful solution to the challenge of achieving defect-free surfaces and subsurfaces, as well as precise control of etching depth.
To address the challenge of anisotropic deep etching with smooth sidewalls, the Thermal Catalytic Etching (TCE) technique has been advanced with two new approaches: the double-metal layer (DML) technique and the termination method. TCE is based on the catalytic reactions of several transition metals with diamond under hydrogen or water vapor atmospheres. This technique can produce anisotropic patterns in (100) diamond with high-quality sidewalls.
Electron Beam Induced Etching (EBIE) is a process in which material is removed upon electron exposure inside a scanning electron microscope (SEM) chamber containing low-pressure gases such as air or oxygen. The EBIE mechanism involves primary electrons colliding with the diamond surface, generating secondary electrons that dissociate nearby gas molecules into reactive radicals. These radicals chemisorb onto the diamond surface, react with carbon atoms, and form volatile byproducts that desorb, leading to material removal. EBIE is particularly well-suited for fast surface smoothing or for producing anisotropic etch pits with longer etching durations.
Combining these three techniques—ALE, TCE, and EBIE—offers powerful tools for fabricating high-performance diamond electronic devices, such as vertical transistors and diodes, as well as optical devices like light emitters.
