PBTI improvement in gate last HfO2 gate dielectric nMOSFET due to Zr incorporation

Abstract

PBTI in the HfxZryO gate dielectric low temperature full gate last process flow nMOSFETs was demonstrated to be reduced compared to the HfO2 gate dielectric devices of a similar EOT. PBTI degradation in both stacks was successfully modeled within a common framework of fast and slow electron trapping components in the gate dielectrics. The fast component was assigned to the resonance electron trapping in the pre-existing high-κ dielectric defects while a slow, temperature dependent component could be attributed to the migration of the trapped electrons to unoccupied defect sites. Lower PBTI degradation in the Zr:HfO2 stack was shown to be caused by a smaller fast electron trapping component.