Annealing effects of carbon in n-channel LDD MOSFETs

Abstract

The degradation pattern of lightly doped drain (LDD) structure MOSFETs with carbon doping under various steps has been studied. For a carbon-doped LDD device with first- and second-level metal and passivation layer but without any final anneal, the results show that a significant reduction in the shifts of the threshold voltage of MOSFETs with time can be achieved. The authors demonstrate that threshold voltage degradation has been reduced for carbon-doped devices and that a final anneal does not improve the hot-electron degradation of these devices. These results imply the existence of neutral electron traps in the gate oxides of MOSFETs. >