Influence of process parameters on hydrogen silsesquioxane chemistry at low voltage electron beam exposures

In the frame of the European project MAGIC, a massively multibeam tool working at 5kV is under installation in LETI premises. Because of its high resolution capability and suitable high exposure dose, hydrogen silsesquioxane (HSQ) is a good candidate for evaluating tool performances. In order to prepare low voltage exposures on HSQ, we studied three process parameters that are post application bake (PAB) temperature, tetramethylammonium hydroxide (TMAH) based developer concentration and beam acceleration voltage, down to 5kV. We combined those experiments with physico-chemical characterization in order to better understand resist reactions leading to measured contrast and base dose variations. As a starting point, we achieved 10nm lines with a pitch of 60nm at 100kV. Thus we validated the high contrast capability of HSQ with our process parameters, with automatic coating and development track. By modifying PAB temperature and developer concentration, we found a suitable resist process for low voltage exposure. With proper process conditions, high resolution is achievable at 5kV, with a lower exposure dose than at higher voltages.