Study of a radiation hard CMOS process under the influence of Co/sup 60/ irradiation

Test structures fabricated in the UTMC (United Technology Microelectronics Center) 1.2- mu m p-well CMOS process were irradiated by Co/sup 60/ up to 3.8 Mrad. The threshold voltage shifts, Delta V/sub t/, of the NMOS were less than 270 mV, and those of the PMOS were less than 200 mV. The transconductance and transconductance parameter, KP, decreased by about 25% and 10%, for the NMOS and PMOS, respectively. The output conductance did not change much up to 3.8 Mrad. In addition, the change in mobility did not depend on the width and length of the transistor, but Delta V/sub t /of the NMOS, after 1.7 Mrad of irradiation, is shown to depend slightly on the length of the transistor.<
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