Present status of exposure tool development for Low Energy Electron-beam Proximity Projection Lithography

A beta-tool for Low Energy Electron-beam Proximity Projection Lithography (LEEPL) (1-2) has been developed for proof of lithography (POL) of mass production tool, which is applied to required performance in 100-nm and 70-nm technology node. Major features of system design are an acceleration voltage of 1-5 kV, a beam current of 3-20 muA, a maximum field size of 40 mm x 40 mm (effective field size of 25 mm x 25 mm), a die-by-die alignment system and automatic loader systems for masks and wafers. The throughput is estimated over 20 wafers of 300 mm(lozenge) per hour. As examples of initial evaluation results, resolution of 45-nm US patterns and 48-nm(lozenge) hole patterns in resist image were obtained. Alignment experiments are on going now, and overlay accuracy around 20-nm (3sigma) over effective area of 8-in. wafer is being expected.