Detailed analysis of edge effects in SIMOX-MOS transistors

A comprehensive investigation of edge effects in LOCOS-isolated silicon-on-insulator devices is made by combining the measurements of the static characteristics, charge pumping, and noise. Even when a substrate bias is used to mask the conduction on the island edges, the high-frequency edge effects are still detectable. Appropriate models are proposed to separate the edge contribution from those of the front and back interfaces. It is found that the defect density on the edges is inhomogeneous, increasing vertically from the top to the bottom of the film and laterally from the middle to the end of the channel. Slow traps are identified at the back interface, close to the source/drain junctions     

Modeling of the 1/f noise overshoot in short-channel MOSFETs locally degraded by hot-carrier injection

On the basis of previous results concerning the 1/f noise in electrically stressed MOS transistors and the characterization of aged MOSFETs, the authors present a theoretical model for the flicker noise in nonhomogeneous short-channel MOS transistors operated in the ohmic region. When applied to hot-carrier-induced degradation, a simple two-region approximation of this model is shown to account for the existence of a noise peak (overshoot) near the threshold voltage, similar to the transconductance overshoot already observed. A two-dimensional simulation makes it possible to detail the influence of the gate bias, the distance over which the interface states (or traps) are generated, and their density. The 1/f noise overshoot appears to be more sensitive to aging conditions than transconductance overshoot.<>     

Low-frequency noise in depletion-mode SIMOX MOS transistors

Low-frequency noise measurements in depletion-mode SIMOX MOSFETs are reported. A simple model provides a reliable interpretation of the low-frequency noise in multi-interface depletion-mode transistors. An experimental procedure to separate noise contributions of front and back interfaces from noise due to bulk carrier fluctuations is described. The noises generated in the thin Si film and at the two Si-SiO₂ interfaces can be identified and characterized independently in terms of bulk properties and interface trap densities. Single-level traps at the back interface and defects in the volume are detected in high-temperature annealed materials