Further work function and interface quality improvement on Al2O3 capped high-k/metal gate p-type metal-oxide-semiconductor field-effect-transistors by incorporation of fluorine

The impact of fluorine (F) incorporation into TiN/HfO2/SiO2 on work function has been investigated. By process scheme optimization, F implanted through sacrificial oxide layer reveals sufficient the flat-band voltage (VFB) shift ~ 170 mV without an equivalent oxide thickness (EOT) penalty. On the contrary, apparent EOT increasing was observed if F implanted directly through Si. Moreover, F incorporation into TiN/Al2O3/HfO2/SiO2, the VFB shift can be up to about 250 mV or 410 mV at 10 keV with a dose of 2 × 1015 cm− 2 or 5 × 1015 cm− 2, respectively. Effective work function has been boosted to 4.95 eV closer to the valence band edge. Besides, interface defect density also can be improved ~ 20% by F incorporation from charge pumping result.

► F implantation into TiN/HfO2/SiO2.
► Flat-band voltage (VFB) shift ~ 170 mV without equivalent oxide thickness penalty.
► Interface defect density can be improved ~ 20% by the incorporation of F.
► F incorporation with Al2O3 cap, the VFB shift can be up to 410 mV.
► Effective work function reaches 4.95 eV near the valence band edge.