Correlation between two dielectric breakdown mechanisms in ultra-thin gate oxides

The origin of stressing polarity dependence of charge-to-breakdown, Q(bd), in thin SiO2 is discussed based on the temperature dependence of Q(bd) for both stressing polarities using wet and dry oxides. It was found that the temperature dependence of Q(bd), which increases with decreasing temperature in the high temperature region and tends to saturate in the low temperature region, is identical irrespective of the stressing polarity and the oxidation condition. It has been proposed that the strain gradient from Si/SiO2 interface to SiO2/gate electrode interface determines directly both the Si-H bond density which dominates Q(bd) in high temperature region and the strained Si-O bond density which dominates Q(bd) in the low temperature region, irrespective of gate polarity and of oxidation condition. (C) 1996 American Institute of Physics.