Breakdown voltage instability mechanism and improving ruggedness in Trench Field Plate Power MOSFET

Breakdown voltage instability mechanism of Trench Field Plate Power MOSFET was studied. We found that breakdown voltage (BV
_DSS
) shifts obeyed power-law time dependence by analysis of time dependent BV
_DSS
shifts. Furthermore, stress/suspend measurements revealed that BV
_DSS
shift repeated increase/recovery behaviors. These results were discussed by Si-H bond dissociation Reaction-Diffusion (R-D) model as well as hot carrier degradation and negative bias temperature instability (NBTI) in conventional MOSFET. TCAD simulations suggested that positively charged traps at bottom of trench caused the BV
_DSS
instability. Therefore, we believe that Si-H bond dissociation at trench bottom Si/SiO
₂
interface was induced by hot carriers. Based on these findings, improvement of BV
_DSS
stability by trench bottom electric field optimization was demonstrated.