Investigating Pattern Transfer in the Small-Gap Regime Using Electron-Beam Stabilized Nanoparticle Array Etch Masks

Extreme small-gap lithography is necessary for future bit-patterned media, but is under-explored due to lack of etch masks with small enough gaps. Self-assembled nanoparticle arrays featuring 2 nm gaps are promising candidates, but exhibit lateral instability during etching. We present a novel one-step method for stabilizing their order by exposing to intense electron beam doses, and show pattern transfer into an underlying Si wafer. Electron beam-induced cross-linking of the surfactant is hypothesized to explain the improved stability. We suggest that this process could be used to pattern hard masks for subsequent pattern transfer into underlying magnetic films, with the gap and feature size required for bit patterned media to achieve densities in excess of 2 terabits per square inch.