Effects of electrical stress on the frequency performance of 0.18 /spl mu/m technology NMOSFETs

The effects of DC hot-carrier stress on DC and RF performance of submicron LDD NMOSFETs are investigated. It is shown that transit frequency f/sub T/ decreases as transconductance g/sub m/ of the transistor is degraded with stress but it is observed that degradation of f/sub T/ versus stress time is faster than that of g/sub m/. This was found to be due to the increase of the gate-source capacitance C/sub gs/ with stress. Threshold voltage V/sub th/ and output conductance g/sub ds/ increase and voltage gain of the device /spl mu//sub f/ decreases with stress. Stability factors K and /spl Delta/ also change toward higher stability with stress.