HOT-CARRIER-RELATED DEVICE RELIABILITY FOR DIGITAL AND ANALOG CMOS CIRCUITS

In the past five years, a sufficient understanding of hot-carrier degr adation has been obtained to allow reliability predictions of digital and analogue CMOS circuits. The proven quasi-static behaviour and a un iversal time dependence of the degradation, which is independent of th e specific stress condition, prove helpful in developing simple formul ae for predicting n-channel lifetimes in digital circuits. In p-channe l devices, in contrast, a detailed quantitative understanding is obtai ned which leads to a precise description of the degradation in this ty pe of device. Reliability predictions of digital CMOS circuits are per formed on this basis. Analogue circuits operate with long-channel devi ces and in regimes differing from those for digital applications, thus requiring additional considerations. Channel-length dependences of th e hot-carrier degradation have been found for a variety of electrical parameters relevant to the analogue operation of n- and p-MOSFETs. In particular, a new degradation effect independent of channel length tha t is important for modelling analogue circuits has been discovered in p-MOSFETs. The reliability of devices in analogue circuits is describe d and tested on this basis.