γ—Radiation effects on MOSFET's fabricated with NMOS Submicrometer technology

In this letter, we report γ-radiation effects on MOSFET's fabricated with NMOS submicrometer technology. We have investigated the radiation sensitivity of n-channel MOSFET's with L
eff
varying from 6 to 0.3 µm and with a gate oxide thickness of 250 Å. We observed that, for radiation doses ≤ 10
⁴
rad's, the threshold voltage shift is less than 75 mV and this shift is independent of the device geometry (even for L
eff
= 0.3 µm). A comparision has also been made between TaSi
2
gate MOSFET's and poly-gate MOSFET's. The deposition of TaSi
2
on poly/oxide/silicon structure does not decrease the radiation sensitivity of these MOSFET's. We have also compared MOSFET's fabricated with X-ray lithography and optical lithography. The X-ray lithography does not have a significant effect on the radiation sensitivity of these MOSFET's.