Soft breakdown enhanced hysteresis effects in ultrathin oxide silicon-on-insulator metal-oxide-semiconductor field effect transistors

The impact of oxide soft breakdown location on threshold voltage hysteresis in partially depleted silicon-on-insulator metal-oxide-semiconductor field effect transistors with an ultrathin oxide (1.6nm) is investigated. Two breakdown enhanced hysteresis modes are identified. In a drain-edge breakdown device, excess holes result from band-to-band tunneling flow to the floating body, thus causing threshold voltage variation in drain bias switching. In contrast, in a channel breakdown device, enhanced threshold hysteresis is observed during gate bias switching because of increased valence band electron tunneling. Our findings reveal that soft breakdown enhanced hysteresis effect can be a serious reliability issue in silicon-on-insulator devices with floating body configuration.