Development of single‐layer positive resist process for electron beam direct writing technology

A single‐layer resist process using a high resistivity positive resist by solubility reversal (PSR) for electron beam direct writing is described. Conventional PSR designed for mask creation is found to have inhomogeneous dissolution characteristics due to a side effect during the stage of deprotection reaction. To overcome this problem, the efficiency of dissolution inhibition is improved by controlling the composition of base resin materials. Using an optimized base resin structure, 0.4‐μm contact window patterns were successfully delineated in a 1.6‐μm thick single‐layer with a sensitivity of 3.5 μC/cm 2 . The dry etching durability of a single‐layer PSR was also examined and a high level of dry etching durability for SiO 2 etching was observed.