Electrode modification by electron-induced patterning of self- assembled monolayers

Gold electrodes were coated with self-assembled monolayers of 1-1'-biphenyl-4-thiol (C6H5-C6H4-SH, BPT) and 1-octadecanethiol (CH3-(CH2)(17)-SH, ODT) and patterned by proximity printing with stencil masks using electron energies of 300 eV and area doses of 40 000 muC/cm(2) (BPT) as well as 10 000 muC/cm(2) (ODT). The subsequent copper deposition in an electrochemical cell revealed that e-beam patterned alkanethiol behaves opposite to that of e-beam patterned biphenyl. ODT acts as a "positive template" leading to copper deposition only on the irradiated parts. BPT on the other hand acts as a "negative template," where the irradiated and therefore cross-linked biphenyl layer exhibits a blocking behavior, and hence copper is only deposited on the nonirradiated parts. The influence of the deposition potential and the copper ion concentration of the electrolyte on the process has been investigated to find the optimal parameters for producing nanostructures with high selectivity. (C) 2002 American Vacuum Society.