Low-Leakage Tetragonal ZrO2 (EOT < 1 nm) With In Situ Plasma Interfacial Passivation on Germanium

We successfully fabricated gate stacks (ZrO
₂
/GeO
_x
/Ge) with a subnanometer equivalent oxide thickness (EOT) and low-leakage current on n-/p-Ge through plasma-enhanced atomic layer deposition (ALD). A 0.78-nmthick GeOx was formed through plasma oxidation (i.e., in situ plasma interfacial passivation, followed by 3.48-nm-thick ZrO
₂
growth in the same ALD reactor). A subnanometer EOT of N0.9 nm was achieved with a relatively high dielectric constant (roughly 30) of tetragonal-phase ZrO
₂
. The gate leakage was N1 x 10
^-4
A/cm2 at VFB - 1 V, and roughly 5 x 10-5 A/cm2 at VFB t 1 V on pand n-type Ge, respectively. Our ZrO
₂
stabilized in the tetragonal phase, when the post-deposition annealing temperature, was higher than 500 °C. Therefore, the proposed scheme is simple and effective for use in pursuing an ultralow EOT gate dielectric on Ge.