Localized charging damage in thin oxides

In the proposed model, breaking of the oxide chemical bonds is assumed to result from the combined effect of electric field and electron fluence in the oxide during electrical stress. Collision between the injected electron and oxide atoms may excite the bond to an unstable electronic state that can lead to the formation of a structural defect. Electric field polarizes, and thus weakens the defect bonds causing bond breakdown. The model describes charge-to-breakdown dependence on electric field, temperature and oxide thickness, The difference in positive and negative gate bias charge-to-breakdown data is attributed to the presence of the structural strained layer at the Si/SiO2 interface. This approach is used for analysis of the effects of process induced charging stress on transistor parameters. It is shown that leakage current may increase or decrease with oxide thickness depending on the magnitude of the stress induced charging damage.