H2 High Pressure Annealed Y-Doped ZrO2 Gate Dielectric With an EOT of 0.57 nm for Ge MOSFETs

We report on the impact of H
₂
high pressure annealing (H
₂
-HPA) on a Y-doped ZrO
₂
(Y-ZrO
₂
)/GeO
_x
/Ge gate stack. In this paper, compared to conventional forming gas annealing (FGA), the H
₂
-HPA increased the k-value of the Y-doped ZrO
₂
gate dielectric to as high as 47.8 by enhancing the crystallization of the Y-ZrO
₂
. This process can achieve an aggressively scaled equivalent oxide thickness (EOT) of 0.57 nm with an extremely low gate leakage current (J
_g
) of 4.5 × 10
^-6
A/cm
²
. In addition, the H
₂
-HPA effectively passivated the dangling bonds and reduced the interface trap density (Dit) to as low as 3.4×10
¹¹
eV
^-1
cm
^-2
. The Ge pMOSFETs of the Y-ZrO
₂
with H
₂
-HPA led to a ~ 70% improvement in the effective hole mobility compared to the counterpart device with the conventional FGA. The device with H
₂
-HPA also showed an improved subthreshold swing (SS) value of 93 mV/dec compared to that with the FGA (135 mV/dec).