Resolution Limit of Negative Electron Resist Exposed on a Thin Film Substrate

Abstract

The ultimate resolution of the high contrast negative electron resist, chloromethylated poly‐α‐methylstyrene, was investigated by exposing thin films with 10 nm diam, 39 kV electron beam on a thin Si3N4 substrate. The resolution of the negative resist showed a significant dependence on initial resist thickness and molecular weight of polymer. The swelling of cross‐linked polymer during development limits the pitch resolution, which showed a remarkable improvement by the reduction in the resist thickness and the molecular weight. Rather smaller initial thickness and molecular weight dependences of the resolution were observed in the minimum linewidth achieved, which seems to be limited by the size of cross‐linked polymer chains. The highest resolution pattern of 23 nm wide lines on 82 nm pitch was delineated in a thin film of a low molecular weight resist.

Nanolithography with a high-resolution STEM

“…A compromise between resolution and sensitivity is achieved with resists such as PMMA processed in the positive mode, in which liftoff structures about 12 nm wide are possible [7,8]. Structures with linewidths of roughly 23 nm made using conventionally processed negative resists have appeared in the literature [9,10]. This paper describes the adaptation of a high-resolution scanning transmission electron microscope (STEM) to fabricate complex patterns.…”