Abnormal Transconductance Enhancement under Positive Bias Stress in Nanoscale n-Channel Fin Field-Effect-Transistors

Abstract

This work demonstrates an abnormal transconductance (GM) enhancement after positive bias stress (PBS) in n-channel high-k/metal gate stacked fin-field-effect-transistors. This abnormal GM enhancement is observed only in short channel devices. With the speculation that hole-trapping-induced electron accumulation is the dominant mechanism, PBS with floating source and drain is adopted as an investigative approach. This, together with the electric field simulation, verifies that hole-trapping in the HfO2 and SiN near the gate corner induces electron accumulated at the ends of the channel length. Such a phenomenon results in a shortening of effective channel length and further GM enhancement.