INFLUENCE OF SECONDARY ELECTRONS IN PROXIMAL PROBE LITHOGRAPHY

This article describes the limitations of proximal probe lithography d ue to electrons that are mirrored by the electric field between the ti p and the surface. The incident beam generates two kinds of electrons at the sample surface: primary electrons which are elastically backsca ttered and secondary electrons which are produced in the resist/substr ate system. The electric field confines the electrons emanating from t he surface. The electron trajectories are bent in such a way that the electrons impinge on the sample surface in the vicinity of their origi n. These reflected electrons contribute to the exposure of the resist and therefore, limit the resolution. For hexadecanethiol monolayers on gold substrates, we have measured the energy distribution of the mirr ored electrons and the secondary electron yield as a function of the p rimary energy. With near edge x-ray absorption fine structure spectros copy, we have investigated the relevance of low energy electrons in th e exposure of hexadecanethiol films. Simulations of secondary electron trajectories can explain the occurrence of triple line structures obs erved in field emission proximal probe lithography. (C) 1997 American Vacuum Society.