Off-state gate current in n-channel MOSFETs with nitrided oxide gate dielectrics

The authors report on the off-state gate current (I/sub g/) characteristics of n-channel MOSFETs using thin nitrided oxide (NO) gate dielectrics prepared by rapid thermal nitridation at 1150 degrees C for 10-300 s. New phenomena observed in NO devices are a significant I/sub g/ at drain voltages as low as 4 V and an I/sub g/ injection efficiency reaching 0.8, as compared to 8.5 V and 10/sup -7/ in SiO/sub 2/ devices with gate dielectrics of the same thickness. Based on the drain bias and temperature dependence, it is proposed that I/sub g/ in MOSFETs with heavily nitrided oxide gate dielectrics arises from hot-hole injection, and the enhancement of gate current injection is due to the lowering of valence-band barrier height for hole emission at the NO/Si interface. The enhanced gate current injection may cause accelerated device degradation in MOSFETs. However, it also presents potential for device applications such as EPROM erasure.<
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