Atomic layer deposition of thermally stable conductive MoOx films using a low-valent precursor for ZrO2-based capacitors

초록

Atomic layer deposition (ALD) of conductive molybdenum oxide is attractive for advanced capacitor electrodes; however, ALD-grown MoOx typically forms in a highly oxidized MoO3-like phase and can undergo degradation during post-deposition annealing, making the stable formation of MoO2 films remain challenging. Here, ALD using a low-valent Mo(II) precursor and O3 yielded as-deposited MoOx films containing Mo4+, Mo5+, and Mo6+ species. After annealing at 500 °C for 1 min in either N2 or H2, the films became Mo4+-dominant and crystallized primarily as monoclinic MoO2 while retaining a continuous surface morphology. Resistivities of 723 μΩ·cm under N2 and 612 μΩ·cm under H2 were obtained for films thicker than approximately 12 nm. In ZrO2/MoOx/TiN capacitors, the MoOx interlayer thickness strongly influenced the overall electrical performance of the capacitor stack, with the most favorable characteristics obtained at ∼ 5.2 nm. Compared with conventional ZrO2/TiN capacitors, the optimized ZrO2/MoOx/TiN structure achieved lower EOT and higher capacitance density with comparable or lower leakage current. These results demonstrate an integrated process–material–device approach in which ALD-grown mixed-valence MoOx is converted into a conductive MoO2-dominant film and employed as a thickness-optimized interlayer on TiN to improve the EOT–leakage trade-off of ZrO2-based capacitors.

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