Proton beam writing: A platform technology for nano-integration

Abstract

Proton beam writing (p-beam writing) is a process which uses a focused beam of MeV protons to pattern resist material at nanodimensions. This makes p-beam writing the only one tool for fast prototyping of high aspect ratio structures with vertical walls up to 60μm and high aspect ratio values with details down to the 20 nm level. The process, although similar in many ways to direct writing using electrons, nevertheless offers some interesting and unique advantages. Protons, being more massive, have deeper penetration in materials whilst maintaining even energy deposition along a straight path, enabling p-beam writing to fabricate 3D high aspect ratio structures with vertical smooth sidewalls and low line edge roughness. Calculations have also indicated that p-beam writing exhibits minimal proximity effects, since the secondary electrons induced in proton/electron collisions have low energy. A platform technology to integrate 3D nanowires is proposed through high aspect ratio nanofabrication using p-beam writing.