Acceleration factors of PMOS hot carrier degradation

Abstract

The acceleration factors of hot carrier (HC) degradation are investigated in detail for scaled PMOSFETs. Extrapolated lifetimes under usage conditions are found to be much longer than might be expected from DC stress tests simply interpreted in a traditional manner. The new findings are: (1) the LOG(lifetime) depends on stress-V/sub D/ not by a factor 1/V/sub D/ as in NMOSFETs, but by 1/(|V/sub D/-V/sub 0/), where the constant V/sub 0/ is a weak function of stress-V/sub G/; (2) device parameters have different acceleration factors; /spl Sigma/I/sub ds/, which best represents inverter operation, degrades more slowly than V/sub T/ or I/sub ds/ (at V/sub cc//2) under usage condition; (3) the PMOSFET degradation can be slow for another reason: the release of trapped electrons from oxide back to the silicon (Brox et al, IEEE Trans. vol. ED-41, pp. 1184-1196, 1994).