Defect generation in Si/SiO2/ZrO2/TiN structures: the possible role of hydrogen
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 is shown to be quite well reproduced by a dispersive hydrogen transport model. The model is based on the assumption that impacting electrons release H+ ions near the Si/SiO2 interface which then randomly hop around in the gate dielectric stack, where they can be trapped and form hydrogen-induced defects. By comparing the experimental results and the model, it is found that the positive charge is located close to the Si/SiO2 interface, while the neutral defect resides in the ZrO2 layer. We suggest that these defects concern the positively charged [Si2 = OH]+ centre and neutral ZrOH centre, respectively.