Comparison of interface positive charge generated in metal-oxide-silicon devices by high-field electron injection and x-ray irradiation.

Interface positive charge induced in thin oxides (582 Å thick) of metal-oxide-silicon devices by Fowler–Nordheim injection and x-ray irradiation was evaluated based on measurements of room-temperature annealing characteristics. Results showed that in the low-dose regime, the dose dependence of the density and distribution of the positive charge was different for the two forms of stress. However, at higher doses, the positive charge density produced by both methods increased monotonically while its spatial extent decreased and became more localized at the interface. These latter results are attributed to a buildup of negative charge in the oxide that neutralizes the positive charge furthest from the interface, whereas the differences at low dose are due either to the different character of the positive charge generated by the two techniques or to the much smaller electron density present during irradiation than injection. [ABSTRACT FROM AUTHOR]