A novel CMOS compatible L-shaped impact-ionization MOS (LI-MOS) transistor

Abstract

This paper reports a novel L-shaped Impact-ionization MOS (LI-MOS) transistor technology that achieves subthreshold swing well below 60 mV/decade at room temperature. First, the LI-MOS transistor is CMOS process compatible, and requires little process modification for integration in a manufacturable process. Second, the LI-MOS structure employs raised source/drain (S/D) regions that enable controllability and scalability of the impact ionization region (I-region). Third, the LI-MOS has superior compactness over previously reported I-MOS device structures. Fourth, the LI-MOS enables the integration of novel materials for band gap and strain engineering to enhance the impact ionization rate in the I-region. Based on the above technology, we demonstrate a record subthreshold swing of 4.5 mV/decade at room temperature for a 100 nm gate length device that incorporates a SiGe I-region. The smallest impact-ionization-based MOS device with a gate length of 60 nm is also demonstrated with a subthreshold swing that is well below 60 mV/decade. © 2005 IEEE.