Electron-beam-induced deposition of 3-nm-half-pitch patterns on bulk Si

This paper demonstrates electron-beam-induced deposition of few-nm-width dense features on bulk samples by using a scanning electron-beam lithography system. To optimize the resultant features, three steps were taken: (1) features were exposed in a repetitive sequence, so as to build up the deposited features gradually across the entire pattern, and thus avoid proximity effects; (2) an additional delay was added between exposures to permit diffusion of reactants into the exposed area; and (3) the exposures were phase-synchronized to the dominant noise source (the 50-Hz line voltage) to minimize the effect of noise. The reasons these steps led to significant improvements in patterning resolution are discussed.