A variable channel-size MOSFET with lightly doped drain structure

We propose a metal oxide semiconductor field-effect transistor (MOSFET) whose channel size can be modified by applying control voltage. The variable-channel-size MOSFET (VS-MOS) has a control gate between the main gate and the source/drain. The control gate possesses a gap at its end in the active region. Owing to this unique layout, the VS-MOS achieves continuous modulation of effective channel size and can be fabricated using the conventional complementary MOS (CMOS) fabrication process. Results of test device fabrication show that the channel size modulation can be enhanced by employing the lightly doped drain (LDQ) structure. It is also shown that the logic threshold can be controlled in a CMOS inverter composed of the VS-MOS.