Soft breakdown enhanced hysteresis effects in ultra-thin oxide SOI nMOSFETs

The impact of soft breakdown location on V/sub t/ hysteresis in partially depleted SOI nMOSFETs with ultra-thin oxide (1.6 nm) is investigated. Two breakdown enhanced hysteresis modes are identified. In a channel breakdown MOSFET, excess holes attributed to valence electron tunneling flow to the floating body and thus cause V/sub t/ hysteresis in gate bias switching. In contrast, for a drain-edge breakdown device, enhanced V/sub t/ hysteresis is observed during drain bias switching because of increased band-to-band tunneling current.