Today CCER PhD researcher Chidozie Onwudinanti succesfully defended his thesis On hydrogen penetration into ruthenium – The role of tin in blistering of EUV mirrors. Congratulations to the new doctor!
The reflectivity and operational lifetime of the ruthenium-capped multi-layer mirrors used in EUV lithography are reduced by the formation of blisters – hydrogen-filled bubbles under the ruthenium layer. These bubbles have been observed to form rapidly in the presence of tin, which may be deposited on the reflector surface from the laser-produced tin plasma in the EUV source. This dissertation proposes a mechanism via which tin facilitates the blistering of the mirrors, on the basis of atomistic modelling and simulation of ruthenium-hydrogen-tin interactions.
Dr. Onwudinanti's PhD thesis may be downloaded here (pdf).