Fabrication of <5 nm width lines in poly(methylmethacrylate) resist using a water:isopropyl alcohol developer and ultrasonically-assisted development

We report on the fabrication of 3-4 nm wide continuous lines in a positive tone electron beam resist poly(methylmethacrylate) on a solid substrate. This narrow linewidth was made possible through the use of a nonsolvent-based developer system, water:isopropyl alcohol, together with ultrasonically-assisted development, which reduced the effective development time thus limiting the swelling of the unexposed resist. This combination of solvent system and development technique results in a smaller radius of gyration in the developing polymer molecules and in a wider exposure dose latitude compared to conventional processing and so allows ultrasmall features to be reproduced. (C) 2001 American Institute of Physics.