The electron yield is a key parameter because it quantifies the magnitude of electronic processes occurring in photoresists during exposure to extreme ultraviolet (EUV) light. Contrary to previous technologies, EUV lithography is triggered by a large cascade of low energy electrons generated by few primary photoelectrons. It is believed that photoresists with high electron yield are more efficient in generating the secondary electron cascade, which could lead to higher sensitivity, lower dose and increased throughput. However, there is not yet enough experimental evidence to confirm this hypothesis. For this reason, at imec we are exploring state-of-the-art photoresists using a dedicated tool for photoemission in the extreme ultraviolet wavelength (13.5 nm). Our study mainly films of << 30 nm thickness to enable the fabrication of next generation integrated circuits at single-digit technology nodes (< 10 nm) and meet needs of industry and advance science. The main challenge of photoelectron yield measurement lies in the undesired effects introduced by, for example, surface conditions and charging, in addition to the chemical modifications induced in the material during exposure to the beam itself. On the other hand, this latter feature opens new opportunities to track the chemical changes happening in the photoresist during exposure to the EUV beam “in situ”. In the framework of this project, the trainee will develop the instrumentation needed to measure electron yield and understand how secondary electron cascade evolves in photoresists of different composition and chemistry. She/he will also interpret the experimental data using physical modeling of the electronic structure of the materials involved in the conduction-emission from the surface of the thin film. The outcome of this work is relevant not only for EUV but for all next generation nano-fabrication methods which will be based on electron-mediated exposure, such as electron-beam lithography.
Type of project: Combination of internship and thesis, Thesis, Internship
Duration: 3 months or more
Required degree: Master of Engineering Technology, Master of Science, Master of Engineering Science
Required background: Physics, Nanoscience & Nanotechnology, Materials Engineering, Electrotechnics/Electrical Engineering