Fifty nanometer lines patterned into silica using water developable chitosan bioresist and electron beam lithography

Current chemicals used in electron beam (e-beam) lithography generate safety and waste management issues. To replace them, chitosan, a natural and abundant polymer soluble in water based solutions, was assessed as a positive and water developable resist for a two-layer e-beam lithography and as a mask for transfer by etching in silica. Fifty nanometer line patterns were successfully obtained in a chitosan film by e-beam lithography at doses between 160 and 300 μC cm−2, then, transferred into a silica layer by CHF3 plasma reactive ion etching with respect of the feature dimensions.