Turn-around effects during dynamic operation in 0.25μm CMOS technology from low to high temperature

Abstract

The hot-carrier reliability of a 0.25μm CMOS technology with a 5nm-thick gate-oxide is studied from low (−40°C) to high temperature (125°C). Channel hot-carriers are investigated using DC and AC experiments on single transistors and on ring oscillators. Turn-around effects are observed in the degradation of the ring oscillator frequency at short times when P-MOSFET's degradation totally compensate the N-MOSFET's current reduction. As the electron trapping becomes much less efficient in thin gate-oxide P-MOSFET's with respect to field enhanced detrapping, the influence of the generated interface traps dominates leading to a cumulative current reduction in both device types at long stress time which results in a reduction of the oscillator frequency. The degradation behavior of the oscillator frequency exhibits a clear dependence on the P-MOSFET channel-width and on temperature as negative bias temperature instability occurs at 125°C during the high state in P-MOSFET's and the field-assisted discharge of electron traps occurs at −40°C.