Cu(111) Surface Passivation with Atomic Layers of Te, Se or I, Studied Using Auger Spectrscopy

Abstract

Efforts are described to identify an atomic layer (AL) passivating agent for Cu, allowing it to be transferred from solution, between solutions, or from solution into vacuum without oxidation. Atomic layers investigated included tellurium, selenium and iodine. Potentials and pH used to form the AL were investigated. Elemental ratios from auger electron spectroscopy (AES), such as O/Cu, and low energy electron diffraction (LEED) patterns were used to characterize the Te, Se and I AL before and after exposure to oxygen. The AL for all three elements resulted in 1/3 ML coverage (√3x√3)R300 structures. The ability of an AL to passivate the Cu(111) surface was investigated by exposing it to solution vapor in 1 atm of UHP Ar for 5 minutes within the EC ante-chamber. The resulting surface was then characterized in the analysis chamber. The intent was to mimic transfer between tools in a FAB. In addition, AL coated Cu(111) substrates were exposed to atmospheric oxygen for over 10 minutes, followed by characterization. Exposure to solution vapor and 1 atm UHP Ar resulted in no significant oxygen uptake, though small oxygen signals were detected for the Se AL and the I AL. However, only the Te AL provided passivation to atmospheric oxygen for 10 minutes.