DEPTH DISTRIBUTION OF ZINC ADSORBED ON SILICON SURFACES OUT OF ALKALINE AQUEOUS-SOLUTIONS

In the mass production of advanced microelectronic devices (chips), co ntamination by transition metals is known as a major risk for device y ield and reliability. Although zinc belongs to the most frequent conta minants, not many efforts have been made to understand the chemistry o f the interactions between this element and silicon surfaces during we t 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 spectro metry), XPS (X-ray photoemission spectroscopy) and ISS (ion scattering spectroscopy) were applied in combination with chemical desorption ex periments to characterize the silicon surfaces and the concentration a nd depth distribution of zinc. These studies show that zinc is partial ly incorporated in the native oxide which is growing under these condi tions on an oxide-free silicon surface. In the case of a chemically ox idized 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 exchan ge reactions during the contamination process. (C) 1998 Elsevier Scien ce B.V. All rights reserved.