HfSiO Bulk Trap Density Controls the Initial $V_{\rm th}$ in nMOSFETs

The underlying physical mechanism of the
V
_th
adjustment of nMOSFETs with HfSiO/TiN gate stack obtained by As and Ar implantation is investigated. It is experimentally proved that the trapped charge in the HfSiO bulk defects controls the initial
V
_th
value in nMOSFETs. The reduction of the charged trap density in HfSiO by implant explains the tuned
V
_th
values.