Stress-driven oxidation chemistry of wet silicon surfaces

Lucio Colombi Ciacchi,^1,2 Daniel J. Cole,³ Mike C. Payne,³ Peter Gumbsch^1,2

¹Fraunhofer Institut für Werkstoffmechanik, 79108 Freiburg, Germany
²Institut für Zuverlässigkeit von Bauteilen und Systemen, University of Karlsruhe, 76131 Karlsruhe, Germany
³Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, CB3 0HE, UK

The formation of a hydroxylated native oxide layer on Si(001) under wet conditions is studied by means of first principles molecular dynamics simulations. Water molecules are found to adsorb and dissociate on the oxidised surface leading to rupture of Si-O bonds and producing reactive sites for attack by dissolved dioxygen or hydrogen peroxide molecules. Tensile strain is found to enhance the driving force for the dissociative adsorption of water, suggesting that similar reactions could be responsible for environmentally-driven sub-critical crack propagation in silicon.

Journal of Physical Chemistry C 112, 12077 (2008)