Spin-on carbon based on fullerene derivatives as hardmask materials for high-aspect-ratio etching

Abstract

The advance of lithographic resolution has made it necessary to adopt extremely thin photoresist films for the fabrication of "2× nm" structures in order to mitigate problems such as resist collapse during development but limiting achievable etch depths at the same time. By using multilayer hardmask stacks, a considerable increase in achievable aspect ratio is possible. We have previously presented a fullerene-based spin-on carbon hardmask material capable of high-aspect-ratio etching. We report our latest findings in material characterization of an original and a modified formulation. By using a higher adduct derivative fullerene, the solubility in industry-friendly solvents and thermal stability could be improved. The etching performance and materials characteristics of the new higheradduct fullerene hardmask were found to be comparable to those of the original hardmask.