Novel resist materials for next generation lithography

Abstract

Fullerene derivatives have been demonstrated as negative-tone resists for electron beam lithography with impressive capability for high resolution and high plasma etching resistance, due to their carbon-rich nature. Their primary drawback of extremely poor sensitivity has been addressed by implementation of chemical amplification. A three-component chemically amplified negative-tone resist has been developed via the addition of a photoacid generator and a crosslinker to a fullerene derivative. This thesis work presents a significant extension of the previous work. The resists have undergone comprehensive optimisation, and systematic characterisation of electron beam lithography behaviours. In the first part, a systematic study into chemical amplification of negative-tone fullerene resists through variation of resist composition, additive, and resist processing in order to optimise sensitivity, resolution, line width roughness and etch resistance is presented. Sensitivity of sub 10 C/cm2 at 20 keV, half pitch resolution of 20 nm, a minimum sparse feature linewidth of 12 nm, line width roughness of sub 5 nm, and high etch resistance comparable with a commercial novolac resist have been demonstrated. The second part presents the development of a chemically amplified positive-tone fullerene based resists with the advantage of aqueous base solution development. Their lithographic capability is evaluated and discussed.