Highly enhanced Schottky barrier heights in source/drain contacts of IGZO FETs using AZO-based MIS structures with post-interlayer deposition annealing (PIDA)

초록

Amorphous indium gallium zinc oxide (a-IGZO) is a promising channel material for future 3-dimensional (3D) dynamic random-access memory (DRAM) applications, owing to its exceptional low off-current, high mobility and compatibility with low-temperature processes. However, the intrinsically high contact resistance of a-IGZO remains a critical bottleneck to hindering high device performance. To overcome this limitation, we propose a novel contact engineering approach by introducing a post-interlayer deposition-anneal (PIDA) metal-interlayersemiconductor (MIS) S/D contact structure, utilizing an aluminum-doped zinc oxide (AZO) interlayer. The AZO PIDA MIS contact leverages a unique interaction between the AZO interlayer and a-IGZO channel, inducing increased carrier concentration in a-IGZO and interface dipole at the contact interface. These synergistic effects lead to a significant reduction in both the Schottky barrier height (SBH) and contact resistivity (rho c). As a result, the effective SBH and rho c were significantly improved from 216 meV and 5.37 E-4 Omega & sdot;cm2 in conventional metal-semiconductor (MS) contacts to 104 meV and 6.92 E-6 Omega & sdot;cm2, respectively. These results represent the bestreported values for a-IGZO-based contacts and establish the AZO PIDA MIS process as a breakthrough strategy for next-generation amorphous oxide semiconductor devices.

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