Suppressing the parasitic bipolar action in fully-depleted MOSFETs/SIMOX by using back-side bias-temperature treatment

A new suppression method for parasitic bipolar action is presented for fully-depleted surface-channel nMOSFETs on SIMOX-structures by using the back-side bias-temperature (BSBT) treatment technique. After 10 h of BSBT treatment, increase in source-drain breakdown voltage of about 300 mV was obtained. A peculiar hot-carrier degradation is also suppressed and device lifetime is improved by 20 times. The device characteristics are not degraded by BSBT treatment because it induces a bias stress to back interface between the buried oxide and the active silicon layer, which does not affect the front channel. Influences of BSBT stress to the back interface were investigated using several methods. The suppression mechanism proposed is the generation of charges and interface traps at the back interface.