High mobility high-k/Ge pMOSFETs with 1 nm EOT -New concept on interface engineering and interface characterization

High-k/Ge interfaces are significantly improved through a new interface engineering scheme of using both effective pre-gate surface GeO
₂
passivation and post gate dielectric (post-gate) treatment incorporating fluorine (F) into high-k/Ge gate stack. Minimum density of interface states (D
_it
) of 2 times 10
¹¹
cm
^-2
eV
^-1
is obtained for Ge MOS capacitors. Hole mobility up to 396 cm
²
/Vs is achieved for Ge pMOSFETs with EOT ~10 Aring and gate leakage current density less than 10
^-3
A/cm
²
at V
_t
plusmn 1 V. Best drain current to date of 37.8 muA/mum at V
_g
-V
_t
= Vd= -1.2V is presented for an L
_g
of 10 mum. Variable rise and fall time charge pumping (CP) method is used to investigate Ge interface property and a significant D
_it
reduction in both upper and lower half of bandgap is observed with F incorporation.