Developement of new technologic nodes involves both a pattern dimension shrink and a pattern density increase. For the last years, development of multi-Patterning strategies with in particular Spacer Patterning (also called SADP) has signifcantly increased. This approach is based on a sacrificial pattern on which a material is depsosited with a conformal configuration to be etched and thus to define spacers used as masks to pattern the sublayer after sacrificial pattern removals. One of the main challenges of this intergration is the material choice in terms of compatibility (thermal budget, selectivity, etc.). Using SiCo(N)-based materials could be a favourable alternative to standard dielectrics (SiO2, SiN). Another challenge is to achieve only one population after SADP : to prevent microloading effects, etching process with an atomic controlwill be developped (ex. pulsing, ALE, etc.). Environmental footprint should be considered during these process developments.
The purpose of this thesis is to set an integration flow with SiCO(N)-based materials, to developp these materials and to determine associated etching strategies.
To lead your research activity, you would be able to benefit privileged environment offered by CEA-Leti with state of the art tool for process development and for material characterization

The advantageous properties (electro-optical, - acoustic, -mechanical) of new materials such as Sc-doped ALN, LNO, LTO or KNN make them essential to meet the development needs of integrated optics, RF telecommunication and microsystems. The production of patterns with submicron dimensions with a significant etch rate (>100nm/min), a vertical profile and a reduced roughness of the pattern's sidewalls are the main goals of the thesis work so as to satisfy the performance criteria of the devices targeted at the application level.

Direct bonding consists of bringing sufficiently smooth and clean surfaces into contact, in order to create adhesion between them without adding any external material. This technology presents many advantages for the production of stacked structures for microelectronics and micro-technologies and has given rise to numerous innovations (manufacturing of SOI by SmartCutTM, manufacturing of SmartSiCTM, production of MEMS, wafer level packaging, 3D integration, etc.). Today, the rise of photonic technologies and the development of direct die-to-wafer bonding are paving the way for the integration of materials such as InP and GaAs in the world of silicon. In order to push these developments we wish to study the bonding mechanisms of these materials which have not yet been established in the literature.

The thesis will consist of studying the direct bonding mechanisms of InP and GaAs wafers:
A first part of the study will consist of finely characterizing the surface of these materials during pre-bonding preparations (type of bonds created, type of oxide, quantity of water adsorbed, etc.).
Then the impact of water in the establishment of adhesion will be particularly studied in relation to the mechanisms established for silicon and its oxide. The stress corrosion sensitivity of InP and GaAs surface oxides will be evaluated. Infrared spectroscopy and X-ray reflectivity studies at the synchrotron will support the conclusions.
A final axis will concern the mechanical properties of these materials to better understand their integration within heterostructures. Their ductile-brittle transition will be characterized using bonding on silicon or other substrates (silica, sapphire, etc.).
The candidate will be trained in all clean room technological tools allowing direct bonding (chemical cleaning, CMP polishing, bonding, thermal annealing) and their characterization (infrared spectroscopy, acoustic microscopy, anhydrous bonding energy measurement, X-ray reflectivity, mass spectrometry, etc.).

To address environmental concerns in the microelectronics industry, CEA-LETI is committed to an eco-innovation approach [1]. In this context, the development of eco-responsible processes that reduce PerFluoro-Carbon (PFC) emissions is crucial [2]. Plasma etching processes are a major emitter of PFCs because they traditionally use high GWP gases. The aim of this thesis will be to develop plasma etching processes on 300mm substrates by replacing fluorinated gases such as NF3, SF6 and CF4 with high GWP by F2 (GWP ~0). This work will involve understanding the changes induced in the etching processes for advanced devices. The dual challenge is to reduce the environmental impact while guaranteeing the high performance of these devices.
To achieve this objective, you will implement new F2-based mixtures on targeted applications for etching materials and cleaning reactors. You will provide comparative data on the performance of these new processes compared with reference processes in terms of etching results and the level of abatement of reaction by-products.
You will be based at the CEA-LETI Etching Laboratory. The work, which will be predominantly experimental on CEA-Leti's 300mm platform (see : https://www.youtube.com/watch?v=on1NH08AZfE), will benefit from the state-of-the-art process equipment and characterisation resources of the Nanotechnologies platform. The scientific and industrial interest of the subject guarantees that your work will be showcased in international communications. If you want your research to have an impact on society, apply now!