Nucleation and growth of copper nanoparticles on silicon surfaces

The recent adoption of copper interconnect technology by the semiconductor industry, has led to great interest in understanding the mechanisms of copper metal deposition onto silicon wafer surfaces from ultra pure water (UPW) solutions. We have studied these processes by using total reflection x-ray fluorescence (TXRF) and x-ray absorption near edge spectroscopy (XANES) in a grazing incidence geometry to determine the surface concentration and chemical state of copper atoms on intentionally contaminated Si surfaces. These measurements established that in deoxygenated UPW, copper is deposited on the silicon surface in the form of metallic nanoparticles with sizes up to 16nm. However, in non-deoxygenated UPW, the copper is incorporated uniformly into the silicon surface oxide as Cu oxide.