Abstract
We report the development of a new family of electron beam resists based on liquid crystalline polysubstituted derivatives of triphenylene. These new resists show excellent performance in terms of both high resolution and high durability to plasma etching. Films of the derivatives have been produced in a controlled manner via room temperature spin coating on hydrogen terminated silicon substrates. The dissolution behaviour of the derivatives in various organic solvents was altered by exposure to a 20 keV electron beam. The solubility of the derivative hexapentyloxytriphenylene, in polar solvents, was substantially increased by electron doses greater than ∼ 3 × 10−4 C/cm2 (positive tone behaviour). Doses greater than ∼ 2.5 × 10−3 C/cm2 led to negative tone behaviour in both polar and non-polar solvents. Other derivatives also demonstrated a reduction in their dissolution rate for doses between ∼ 1 × 10−3 and ∼ 7 × 10−3 C/cm2. The derivative sensitivity was found to be roughly proportional to the molecular mass. Negative tone patterns were found to have an etch durability ∼ 70 % greater than that of a conventional novolac based negative tone resist (SAL601). The performance of these new resists has been demonstrated by the definition of line and space patterns with a resolution of ∼ 14 nm, whilst structures with an aspect ratio of.∼ 50 to 1 were etched into the silicon substrate.
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The contrast is equal to (log10(D2/D1))−1 where D2 and D1 are the doses at which the extrapolation of the linear section of the rising response curve intersects with the 100% and 0% levels for film retention, respectively.
Acknowledgments
The authors thank Drs. J. C. Barnard D. Philp for useful discussions. This work was supported in part by NEDO, through the management of ATP. APGR, MTA and REP thank the Engineering and Physical Sciences Research Council, UK, for financial support. APGR thanks NAIR, Japan, for financial support. The authors are grateful to the British Council for financial support of their UK-Japan research collaboration. JAP would like to acknowledge financial support from NATO.
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Robinson, A.P.G., Palmer, R.E., Tada, T. et al. New High Resolution Liquid Crystal Electron Beam Resists. MRS Online Proceedings Library 584, 129–134 (1999). https://doi.org/10.1557/PROC-584-129
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DOI: https://doi.org/10.1557/PROC-584-129