Role of oxygen in wetting of copper nanoparticles on silicon surfaces at elevated temperature.

Tapas Ghosh,Biswarup Satpati

doi:10.3762/bjnano.8.45

Abstract

Copper nanoparticles have been deposited on silicon surfaces by a simple galvanic displacement reaction, and rapid thermal annealing has been performed under various atmospheric conditions. In spite of the general tendency of the agglomeration of nanoparticles to lower the surface energy at elevated temperatures, our plan-view and cross-sectional transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) analysis shows that the thermal oxidation of the copper nanoparticles and formation of cupric oxide (CuO) on silicon surfaces leads to wetting rather than agglomeration. In contrast, agglomeration has been observed when copper nanoparticles were annealed in a nitrogen environment. The lattice transformation from cubic Cu to monoclinic CuO, and hence the change in surface energy of the particles, assists the wetting process. The occurrence of wetting during the oxidation step implies a strong interaction between the oxidized film and the silicon surface.

Highlights

The transition metal oxide cupric oxide (CuO) is a stable oxide of copper, and due to its diverse applications, immense research on CuO nanostructure fabrication have been carried out
Copper deposited on silicon surfaces by the galvanic displacement reaction were extensively examined by transmission electron microscopy (TEM)
The thermal oxidation was performed in a rapid thermal annealing system at 500 °C for 1 min

Summary

Introduction

The transition metal oxide cupric oxide (CuO) is a stable oxide of copper, and due to its diverse applications, immense research on CuO nanostructure fabrication have been carried out. We found that the formation of CuO by the thermal oxidation of Cu nanoparticles on Si surfaces leads to wetting, where no such wetting was observed when the Cu nanoparticles were annealed under a nitrogen atmosphere. We have studied the oxidation of Cu nanoparticles deposited by the galvanic displacement reaction on silicon surfaces at various ambient conditions.

Results

Conclusion