CHANNEL-LENGTH INDEPENDENT SUBTHRESHOLD CHARACTERISTICS IN SUBMICRON MOSFETS

This letter reports an anomalous subthreshold characteristic of MOSFET for the first time, It is observed that the subthreshold characterist ic does not change as the channel length decreases, The cause of chann el length independent subthreshold characteristics is identified as th e localized pileup of channel dopants near the source and drain ends o f the channel, The low surface potential of this pileup region limits the subthreshold current of MOSFET. As a result, the ratio of on-curre nt to off-current for this MOSFET increases as the channel length is r educed, which is an important parameter for low-voltage operation. It is found that a MOSFET with channel length independent subthreshold ch aracteristic is more suitable for low voltage operation.