A new mechanism was proposed for dielectric breakdown in thin gate oxides. Using first-principles calculations, a new metastable structure was found where an interstitial H radical attached to a network O without breaking the Si-O bond. Calculations in an external electric field showed that the energy of the state was reduced. A pair of such states was further stabilized when they formed a dimer. This electric field-induced dimer state was thermally accessible for very thin oxides and could form a percolating path that may explain the phenomenon of soft breakdown.

Dielectric Breakdown in SiO2 via Electric Field Induced Attached Hydrogen Defects. J.Tahir-Kheli, M.Miyata, W.A.Goddard: Microelectronic Engineering, 2005, 80, 174-7