The oxide layers of MOSFETs, that are commonly used nowadays, degradate over time under normal operating conditions. This degradation causes that MOSFETs cannot operate their own functions. In this thesis, the degradation of oxide layers are achieved in a shorter time by applying the voltage which is higher than that of the normal operating condition. The effects of this degradation on the terminal capacitances of MOSFET’s are analyzed depending on time. The changes of characteristic parameters (threshold voltage, mobility, on resistance, etc.) of stress induced MOSFETs are also dealt with in the context of this study.
Terminal capacitances play an important role on switching times of digital circuits and frequency characteristic of analog circuits. The related characteristic parameters (switching times, frequency characteristic parameters) of these circuits were determined by operating the degredated transistors in the inverter and amplifier circuits. Effects of electrical stress on the circuits were analyzed over changes of the characteristic parameters. Beside of the obtained experimental results, stress effect is also modeled by carrying out simulation studies. For switching applications, a simple and accurate degradated power MOSFET model was proposed. In respect of the amplifier circuits, an alternative simulation framework is proposed in order to obtain the changes of the high cut-off frequency depending on stress time. Proposed degradation models have ability to help designers to predict circuit reliability in the early stages of designs.
