Optimization of chemically amplified resist for high-volume manufacturing by electron-beam direct writing toward 14nm node and beyond

We investigated a high-resolution chemically amplified resist for introducing a multi-column cell electron-beam directwriting system into the manufacturing of sub-14 nm technology node LSIs. The target of total blur, which leads to an exposure latitude above 10%, is less than 13.6 nm for 14 nm logic node LSIs. We divided the total blur into three terms, forward-scattering, electron-beam and resist. At a 40 nm-thick resist, the forward-scattering blur was calculated as 1.0 nm in lithography simulation, and beam blur was estimated to be 7.1 nm from the patterning results of hydrogen silsesquioxane. We found that there is a proportional relation between resist blur and acid diffusion length by using a new evaluation method that uses a water-soluble polymer. By applying a chemically amplified resist with a short acid diffusion length, resist blur decreased to 14.5 nm. Even though total blur is still 16.2 nm, we have already succeeded in resolving 20 nm line and space patterns at an exposure dose of 79.6 μC/cm2.