Line width roughness reduction strategies for patterns exposed via electron beam lithography

摘要

Among the different next generation lithography techniques, multibeam may arise as a cost effective solution to pattern sub-22nm technological nodes. A low LWR is required to keep downscaling. In this study, capability of producing low LWR 32/32nm L/S patterns with two different ebeam tools was evaluated. One state-of-the-art single variable shaped-beam (50kV) VISTEC SB3054 and a multiple Gaussian beam MAPPER ASTERIX pre-alpha tool (5kV) are used. Thanks to the great flexibility of e-beam lithography, exposure of biased designs in which the exposed area is reduced is carried out. Such exposure strategy showed a great effectiveness to lower LWR (down to around 3.0nm). To reduce further LWR some post litho-treatments such as thermal processing, plasma treatments and UV treatments are used on patterns exposed with VISTEC SB3054. A combination of a biased exposure and post-litho treatments reduced initial 4.8nm LWR down to 2.8nm (41.7% reduction). Once complete the LWR reduction protocol will be transferred on MAPPER exposures.