Programmable virtual source/drain MOSFETs

We present a MOSFET structure with programmable virtual source/drain (PVS) that can be realized by the erase operation of an NVM device. Compared with the side-gate MOSFET, the proposed transistor has structural advantages, including non-external biasing and high integration density. The excellent retention performance of the fabricated twin SONOS memory (TSM) transistor that minimizes the loss of charges is also obtained. These characteristics confirm that the TSM transistor can be used for the programmable virtual source/drain device. From device simulation and experimental works, it is clearly observed that the programmable virtual source/drain, thanks to a positively charged nitride, brings about small drain leakage and well-controlled short channel effect in normal MOSFET operation. The PVS MOSFET appears to be a good candidate for low operating power appliance in the nano-scale regime.