New observation of an abnormal leakage current in advanced CMOS devices with short channel lengths down to 50nm and beyond

In this work, for the first time, an abnormal leakage current has been observed in MOSFET with 50nm channel length and beyond. This effect shows that, in an ultra-short channel MOSFET, sub-threshold swing (SS) and I_off are decreased for back-biased nMOSFET and pMOSFET. This effect is attributed to the BJT-induced current from the source to the drain. An experimental approach has been used to verify the existence of this BJT current component. As a consequence, this BJT current can be reduced with appropriate control of the SID-to-substrate junction. As an application of the approach to advanced embedded-SiC MOSFET with various splits, it was found that a higher band-offset of SID-to-substrate junction will give rise to a larger the BJT ballistic transport current. This provides us important information on reducing the leakage current for advanced CMOS with 50nm and beyond.