Exposure mechanism of fullerene derivative electron beam resists

We report systematic studies of the response of C-60 derivatives to electro n beam irradiation. Films of nine different methanofullerene C-60 monoadduc ts, produced by spin coating on Si surfaces, were irradiated with a 20 keV electron beam. All exhibited negative tone resist behaviour with a sensitiv ity much higher than that of C-60. In the case of derivatives with two poly ether chains, the sensitivity was found to be linearly dependent upon the d erivative mass, consistent with an increasing electron cross-section for la rger derivatives. Features with widths of 20 nm were produced using these c ompounds, and the etch ratios of the compounds were found to be more than t wice those of a standard novolac-based resist. (C) 1999 Elsevier Science B. V. All rights reserved.