Investigation of anomalous leakage current in mesa-isolated SOI MOSFETs

The mechanism of an anomalous leakage current in mesa-isolated SOI NMOSFETs in the short-channel region was analyzed. The enhanced diffusion of the source-drain impurities was observed in the mesa edge region by Energy Dispersive X-ray Spectroscopy (EDX) analysis. Moreover, using high-resolution TEM observation, it was found that there were no crystalline defects in the edge region. The frequency of leakage currents in short-channel MOSFETs was higher than that of long-channel MOSFETs. The level of leakage current was not changed by the gate voltage and back gate voltage, and the activation energy of the leakage current was almost 0 eV. According to these results, it is concluded that the origin of the anomalous leakage current is the enhanced diffusion of source-drain impurities.