Modification of Aromatic Self-Assembled Monolayers by Electron Irradiation: Basic Processes and Related Applications

Abstract

The effect of electron irradiation on aromatic thiolate self-assembled monolayers (SAMs) with oligophenyl, acene, and oligo(phenylene ethynylene) (OPE) backbones, containing from one to three phenyl rings, was studied, with emphasis on the basic irradiation-induced processes and performance of these films as negative resists in electron lithography. All films exhibited similar behavior upon the irradiation, with clear dominance of cross-linking, taking hold of the systems at already very early stages of the treatment. The cross sections for the modification of the SAM matrix and the damage of the SAM–substrate interface were determined for the primary electron energy of 50 eV, frequently used for the fabrication of carbon nanomembranes (CNM). They show only slight dependence on the backbone character as demonstrated by the example of the three-ring films. The two-ring systems exhibited the best performance as lithographic resists, with an optimal dose of 10–20 mC/cm2 at 0.5–1 keV. The performance of the o...