Gamma-radiation effects on MOSFET's fabricated with NMOS submicrometer technology

Gamma-radiation effects on MOSFET's fabricated with NMOS submicrometer technology are reported. The radiation sensitivity of n-channel MOSFET's with L(eff) varying from 6 to 0.3 microns and with a gate oxide thickness of 250 A was investigated. It is observed that, for radiation doses not greater than 10,000 rad, the threshold voltage shift is less than 75 mV and this shift is independent of the device geometry. A comparison has also been made between TaSi2 gate MOSFET's and poly-gate MOSFET's. The deposition of TaSi2 on poly/oxide/silicon structure does not decrease the radiation sensitivity of these MOSFET's. MOSFET's fabricated with X-ray lithography and optical lithography were also compared. The X-ray lithography does not have a significant effect on the radiation sensitivity of these MOSFET's.