Evaluation of most recent chemically amplified resists for high resolution direct write using a Leica SB350 variable shaped beam writer

E-beam direct writing, one node ahead of advanced optical lithography, can be a time and cost effective option for early device and technology development as well as for fast prototyping. Because of the device complexity only a variable-shaped e-beam writer combined with sensitive chemically amplified resists (CAR) can be considered for this approach. We evaluated various pCARs and nCARs of all major suppliers for our goal to structure DRAMs of the 50nm node using the Leica SB350 e-beam writer. The most promising samples were selected for a process optimization by variation of bake and development conditions. Finally, one resist of each tonality met the most of our specifications like dense lines and contact holes resolution, sensitivity and vacuum stability.