Radiation induced lattice defects in n-MOSFETs and their effects on device performance
Kobayashi, K × Ohyama, H Nakabayashi, M Simoen, E Claeys, Cor Takami, Y Yoneoka, M Hayama, K Kohiki, S #
Trans tech publications ltd
Beam injection assessment of microstructures in semiconductors, 2000 vol:78-79 pages:205-210
Results are presented of a study on the radiation damage and its recovery behavior resulting from thermal annealing of n-MOSFETs fabricated in a 0.8 mum single-well BiCMOS process, subjected to gamma -rays. After irradiation, Drain current for input characteristics, base (substrate) current and interface trap density normally increase with increasing fluence. This result points out that both ionisation damage in the gate oxide and lattice defects in the p-well with interface trap are induced by the irradiation. The degraded device performance was recovered by isothermal annealing. The interface trap density recovers by 85 % for gamma -ray irradiation with a fluence of 1 x 10(8) rad, after a 300 degreesC annealing. Activation energy of recovery (F-a) of drain current for input characteristics for 1 x 10(6) and 1 x 10(8) rad is calculated to be 0.19 and 0.40 eV, respectively, while F-a for both fluence for interface trap density is about 0.22 CV. The results means that increase of drain current for high fluence is mainly responsible for the induced lattice defects in channel region such as divacancy or A center, and that increase of interface trap density is mainly due to radiation damage of interface region.