Impacts of Annealing Temperature on Performance and Reliability of Morphotropic Phase Boundary (MPB) in HZO

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Abstract
This work investigates the impact of annealing temperature on the performance and reliability of morphotropic phase boundary (MPB) Hf ${}_ {{0}.{25}}$ Zr ${}_ {{0}.{75}}$ O2 capacitors for DRAM applications. The films were deposited by atomic layer deposition (ALD) and capacitance-voltage ( $C$ – ${V}\text {)}$ measurements exhibited distinct asymmetric double peaks with a high dielectric constant (57) at $500~^{\circ }$ C annealing temperature. Grazing incidence x-ray diffraction (GIXRD) analysis confirmed that the high dielectric constant originates from a large T-phase fraction (64%) at this annealing temperature. Leakage current and time-dependent dielectric breakdown (TDDB) measurements reveal that the $500~^{\circ }$ C annealed sample achieves the best reliability, yielding a ten-year ${E}_{\text {TDDB}}~\approx ~2.68$ MV/cm at EOT = 6.1 Å while maintaining a very low leakage current density of $6.16\times 10^{-{9}}$ A/cm2 at 1 V. These results indicate that the increased T-phase ratio enhances both dielectric performance and TDDB reliability, which can be attributed to the larger oxygen vacancy diffusion barrier of the T-phase. The proposed MPB HZO structure, therefore, satisfies the voltage and leakage specifications for DRAM storage node capacitors under back end of line (BEOL)-compatible thermal budgets.

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