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)R30 0 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.

Ta Surface Chemistry in Aqueous Solutions and the Possible Formation of TaTe2and TaS3

“…1,32 Characterization of Te deposition onto Ta by EC-STM.-Te was investigated as a possible passivating agent for Ta, given its ability to passivate other metal surfaces such as Cu and Au, and because the electrochemistry of Te has been studied extensively by this group for 25 years. [39][40][41][42] Successful deposition of Te onto Ta is also relevant to the attempts by this group to form metal chalcogenides for CDW device fabrication. After reductive removal of the Ta oxide layer, Te was deposited at −1 V. After Te deposition, the solution was exchanged for 0.1 M KClO 4 blank for imaging.…”

Preliminary Investigations of Ta Surface Chemistry in Aqueous Solutions of TeO2, and the Possible Formation of TaTe2

“…After approximately 20 min, atomic resolution was lost, presumably because the surface was slowly reoxidizing at -1.0 V. Characterization of Te Deposition onto Ta by EC-STM Te was investigated as a possible passivating agent for Ta, given its ability to passivate other metal surfaces such as Cu and Au, and because the electrochemistry of Te has been study by this group for 25 years. (12,13) Successful deposition of Te onto Ta is also relevant to the attempts by this group to form metal chalcogenides for CDW device fabrication. After reductive removal of the Ta oxide layer, Te was deposited onto the Ta surface at -1.0 V. Figure 4 shows atomically-resolved EC-STM images of the resulting surface.…”