Dependence of LDD device optimization on stressing parameters at 77 K

The optimization of lightly doped drain (LDD) devices to minimize hot-carrier-induced device degradation at cryogenic temperature is studied. The degradation behavior of LDD devices at 77 K does not follow the simple behavior modeled by substrate current (I/sub sub/). Also, for a given device, the maximum degradation is not observed at the maximum I/sub sub/ gate bias. Furthermore, the optimum LDD design is found to depend on the specific stressing bias conditions at 77 K. Therefore, the conventional DC acceleration technique cannot predict operating device lifetime or the optimum cryogenic LDD design.<
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