Impact of Source/Drain contact and gate finger spacing on the RF reliability of 45-nm RF nMOSFETs

We report the radio frequency (RF) stress reliability response of 45-nm SOI RF nMOSFETs. The dependence of gate oxide degradation and off-state leakage (due to RF stress) on the contact spacing of the Source/Drain (S/D) terminals and the gate finger-to-gate finger spacing is investigated. The RF device performance trade-offs vs. RF stress reliability that result are investigated. Devices with “tight” S/D contact spacing have improved RF performance but worse RF reliability than devices with “loose” S/D contact spacing. Devices with “loose” gate-finger to gate-finger spacing have better RF performance and also better RF reliability. The net result of this investigation is that fundamental tradeoffs between RF performance and reliability exist at these advanced scaling nodes.