Effects of post-stress hydrogen annealing on MOS oxides after /sup 60/Co irradiation or Fowler-Nordheim injection

Changes in interface trap density, D/sub it/, have been determined in MOSFETs as a function of time during hydrogen annealing at 295 K. Large increases in D/sub it/ are observed during H/sub 2/ annealing in MOSFETs previously stressed by either /sup 60/Co irradiation or Fowler-Nordheim electron injection. The annealing behavior is very similar for both types of stress, and this suggests that the D/sub it/ creation mechanism involves similar chemistry for hydrogen reactions. Studies of the time dependence of D/sub it/ creation as a function of MOSFET gate length show that the time dependence is limited primarily by lateral diffusion of molecular hydrogen through the gate oxide. An activation energy of 0.57 eV, which is consistent with H/sub 2/ diffusion, is obtained from the temperature dependence.<
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