It was proposed that a defect complex comprising a sub-oxide Hf–Si bond and an interfacial dangling bond was responsible for the stress-induced build-up of interface traps in Si/SiO2/HfO2 capacitors. With the aid of first-principles calculations, it was shown that these defects possessed a symmetrical double-well energy minimum with a moderate intervening barrier. The calculated activation energies suggested relatively easy hopping of H atoms between the 2 energy minima (a field-aided shuttling mechanism). This mechanism could explain the experimentally measured oscillations of interface-trap densities during switched-bias conditions following X-ray irradiation or constant-voltage stress.

Hydrogen Shuttling Near Hf-Defect Complexes in Si/SiO2/HfO2 Structures. A.G.Marinopoulos, I.Batyrev, X.J.Zhou, R.D.Schrimpf, D.M.Fleetwood, S.T.Pantelides: Applied Physics Letters, 2007, 91[23], 233503