[NanoIC topic] Understanding the cross-linking mechanisms in EUV metal-oxide photoresists through X-ray absorption spectroscopy

Extreme-ultraviolet (EUV) lithography is enabling manufacturing of integrated circuits with critical dimensions of less than 20 nm for the latest technology nodes, but the high photon energy is imposing new challenges on photoresist materials. Metal-oxide photoresists (MORs) are promising materials that have been driving the progress in EUV lithography since they offer higher resolution, absorption and etch-resistance compared to traditional polymeric organic photoresists. Typical MORs consist of a metallic or metal-oxide core and organic substituents. Upon EUV exposure and baking of a MOR coated on a wafer the organic compounds leave the film, and it is commonly assumed that the activated metal centers create covalent bonds between each other leading to a cross-linked metal-oxide network that is insoluble in organic developer solvents. However, only little experimental evidence about cross-linked networks and their properties has been reported in the literature, since nanoscale films only yield weak signals, for example in infrared spectroscopy, where the characteristic metal-oxygen stretching bands furthermore lie in a spectral region that is difficult to detect. Extended X-ray absorption fine structure (EXAFS) is a spectroscopic technique, which can yield insights on the coordination and interatomic distances of metal atoms and therefore help to better understand the exposure chemistry of MORs. The goal of this internship is to analyze, simulate, and interpret EXAFS data from a model metal-organic photoresists and link it to the EUV patterning performance.

You will work on an extensive dataset of x-ray absorption spectroscopy measurements on a photoresist covering different EUV doses and process parameters, such as baking steps, recorded recently at the European Synchrotron Radiation Facility (ESRF) in Grenoble. Your task will be to pre-process the spectra, extract the EXAFS signal, transform it into real space, build and fit a structural model, and finally interpret the structure. Here you will mainly use established open-source tools and codes, such as Athena and Artemis for the pre-processing and fitting, or FEFF for the simulations, but you might also modify and tailor the tools to your specific problem. Your findings are complementing experiments on the same photoresist system performed by imec researchers, and together you will then advance the state-of-the-art on the fundamental understanding of MOR exposure chemistry. This will contribute eventually to the development of better photoresists by imec’s suppliers and achieve better performances of photoresists for future technology nodes in chip manufacturing.

Who you are:

• Motivated student with a passion for data analysis and modeling of spectroscopic data
• In-progress Masters’s degree in chemistry, physics, material science, nanoscience (or comparable)
• Solid background on spectroscopic techniques, affinity to theoretical simulations
• Proficiency in data analysis and coding (Python, Matlab, etc.) is highly valued
• Good written and verbal English skills

Type of work: