Okay... indeed, they have demonstrated 10ns switching in 90nm technology. I went back to a Berkeley MEMS paper presented at ISSCC 2010 titled "Prospects for MEM Logic Switch Technology" by Tsu-Jae King Liu, et. al. A very interesting and well written paper. Please contemplate the implications of the following statement pulled from the cited paper. "Ideally, relay endurance should exceed ~3×10^14 cycles, e.g. so that a relay- based microcontroller for embedded sensor applications
could operate reliably for 10 years at 100 MHz clock frequency and 0.01 average transition probability." The clock restrictions implied in that statement are significant. Since this is an emerging technology, perhaps they will find a chemistry that enables higher reliability, which translates into greater reliability and longer life or significantly higher transition probability. Higher clock rate... perhaps.
I have built MEMS switches for RF applications and I don't want to rain on anyone's parade, but it also makes me well aware of fundamental physics. i hope they prove me wrong and will gladly drink to their success.
Interesting discussion, we had very interesting talks on this topic at emerging technologies symposiums (www.cmoset.com)...mechanical devices look slow but at nanoscale they can be actually pretty fast, ns or so...they also look large but again at nanosacel they can be quite small so you can put fair amount of them on IC...having said that there is no way they can replace MOSFETs, they can only add value by providing extra functionality like lower leakage switches...Kris
This is actually not true; the UC Berkeley group has already demonstrated ns response times and sub-micron features. The technology promises to scale well. The issues are really system-level: device advantages often get lost when the constraints of an entire system are considered.
No matter how small you make a mems switch, the switching speed is still in kHz or at best barely reaching MHz. Although it is small, there is still inertia associated with the metal that is being moved. For those applications that are okay with kHz clock rates but almost no power consumption and extraordinarily radiation hard, this could be what you are waiting for.