Development and characterization of bio-based photoresists for lithography applications

Context :
CEA-Leti designs the microelectronic components of tomorrow. This involves developing new materials for devices, as well as essential materials for integrated circuit manufacturing, such as photoresists. These innovations also aim to reduce environmental impact by creating products without PFAS or toxic substances. In this context, the Advanced Lithography Processes Laboratory (LALP) collaborates with the Materials for Sensors and Delivery Laboratory (LMCD) at CEA to co-develop new bio-based lithography resists containing methacrylate functions. The goal of the PhD is to study the performances of these new photoresists in lithography and to evaluated their environmental and economical impact. To do so, an emphasis will be made on the influence of the chemical synthesis on the optical properties of the resists, their polymerization mechanisms, and the mechanical characteristics of the resists after exposure. Finally, tools will be given to conduct life cycle analysis on the different products.
Required skills :
The study will examine the entire photolithography process: from the synthesis of the base product and its formulation, to the final structuring. An initial study will analyze the rheological properties of the material after synthesis. Next, its behavior will be evaluated during the spin-coating step (ellipsometry and TGA/DSC). An analysis will focus on the product's sensitivity to a wavelength of 365 nm. Characterization of the product will be carried out by examining the shape of the obtained patterns (SEM) and the physical properties of the resist (ellipso-porosimetry and AFM). Etching tests will also be conducted.

Reproducible elemental quantification of technological materials by photoemission using REELS data

The main objective of this thesis is to refine the methodology for the elemental quantification of high-energy photoemission spectra (HAXPES) in order to achieve uncertainty levels of 5 per cent or less in the measurements carried out, by incorporating, into the recently established methodology, material-dependent physical data relating to the inelastic energy losses of photoelectrons (REELS data). The quantification carried out using this protocol—refined through a study of pure elements—will be compared with existing methods to determine the gain in precision. Subsequently, it will be applied to binary, doped binary and ternary compounds of technological interest, for example for FD-SOI technology; in parallel, a calibration study will be carried out using measurements taken by a cleanroom spectrometer on the same samples; integration aspects will be investigated using measurements on test boxes. In particular, the aim will be to investigate the extent to which the composition measured by HAXPES on a material prepared prior to the transistor integration stages (for the optimisation of deposition processes) compares with that determined by other techniques (atomic probe tomography, TEM-EDX, TEM-EELS) at the end of the integration of nanometric devices.