New advances in resist system for next generation lithography

摘要

A novel nanocomposite resist system was developed for sub-100 nm resolution e-beam lithography by dispersing surface-treated silica nanoparticles in a commercial ZEP520~(~R) resist. At 4.0 wt % loading of silica nanoparticles, the system exhibited a much higher resolution than ZEP520~(~R) without sacrificing the intrinsic sensitivity and contrast of the starting polymer. The first major result is that 46 nm-wide isolated lines were obtained in the nanocomposite system (～250 nm thick layer), whereas comparatively 130 nm-wide lines were obtained in ZEP520~(~R) under the same experimental conditions. Interestingly, this dramatic reduction of line broadening already occurred at 20 keV while higher energy e-beams (up to 100 keV) did not lead to further line broadening reduction. Moreover, it was shown that the addition of silica nanoparticles resulted in a higher resistance of the nanocomposite to plasma etching with O_2 gas. Extending the nanocomposite approach to the KRS-XE~(~R) resist led to both enhanced resolution and mechanical stability. The major resolution improvement in both systems indicates that nanocomposite systems are promising candidates for sub-100 nm resolution e-beam lithography. A mechanism, explaining the electron-nanocomposite interactions at the origin of line broadening reduction, is proposed and tentatively backed by preliminary Monte Carlo simulations.