Depth distribution of zinc adsorbed on silicon surfaces out of alkaline aqueous solutions

Abstract

In the mass production of advanced microelectronic devices (chips), contamination by transition metals is known as a major risk for device yield and reliability. Although zinc belongs to the most frequent contaminants, not many efforts have been made to understand the chemistry of the interactions between this element and silicon surfaces during wet chemical treatments. This paper deals with the interactions of oxide-free and chemically oxidized silicon(100) surfaces with aqueous zinc solutions of pH=9. TXRF (total-reflection X-ray fluorescence spectrometry), XPS (X-ray photoemission spectroscopy) and ISS (ion scattering spectroscopy) were applied in combination with chemical desorption experiments to characterize the silicon surfaces and the concentration and depth distribution of zinc. These studies show that zinc is partially incorporated in the native oxide which is growing under these conditions on an oxide-free silicon surface. In the case of a chemically oxidized surface, only a small part of the adsorbed zinc is incorporated in the oxide in a region close to the oxide surface due to ion exchange reactions during the contamination process.