On the passivation of interface states in SONOS test structures: impact of device layout and annealing process

This paper reports the experimental evidence of anomalous electrical characteristics of large test structures for the characterization of SONOS gate stacks. The anomaly is studied on devices featuring different layout and it is attributed to the property of silicon nitride to block the hydrogen anneal and the passivation of the Si/SiO₂ interface dangling bonds. Since the hydrogen passivation can occur only from the lateral sides of the device, our findings imply restrictions on the dimensions and on the layout of the test structures used to study the electrical properties of SONOS devices.