MOS Integrated Circuit Reliability

This paper presents information on the reliability of MOS integrated circuits based on p-channel enhancement-mode transistors, and describes their failure modes and mechanisms. The principal failure mechanisms were ion migration at the surface and oxide shorting. The results of experimental studies of the effects of variations in construction, processing, and levels of stress are presented, and are compared with other available information on MOS integrated circuit reliability. The failure rate for commercially available complex MOS arrays is on the order of 0.001 to 0.01 per 1000 h of operating life at 125°C for arrays containing approximately 600 p-channel transistors. This corresponds to a failure rate on the order of 5 × 10¿6 to 5 × 10¿5 per equivalent gate per 1000 h. The effects of device complexity, operating temperature, and other factors are discussed. A reliability prediction equation for MOS integrated circuits is derived from available information. An overall activation energy for functional failure mechanisms of approximately 5 kcal/mole (¿0.2 eV/molecule) is considered applicable to typical MOS integrated circuits. Thus, the failure rate of MOS devices operated at 50°C ambient temperature can be predicted to be on the order of 10¿6 to 10¿5 per equivalent gate per 1000 h.