The time and voltage dependence of the neutral defect and positive charge generated in the SiO2/ZrO2 gate dielectric stack during constant gate voltage stress of Si/SiO2/ZrO2/TiN structures was shown to be quite well reproduced by a dispersive H transport model. The model was based on the assumption that impacting electrons release H+ ions near to the Si/SiO2 interface which then randomly hop around in the gate dielectric stack, where they could be trapped and form H-induced defects. By comparing the experimental results and the model, it was found that the positive charge was located close to the Si/SiO2 interface, while the neutral defect resides in the ZrO2 layer. It was suggested that these defects were the positively charged [Si2=OH]+ center and neutral ZrOH center, respectively.

Defect Generation in Si/SiO2/ZrO2/TiN Structures - the Possible Role of Hydrogen. M.Houssa, V.V.Afanasev, A.Stesmans, M.M.Heyns: Semiconductor Science and Technology, 2001, 16, L93-6