Deuterium-enabled stabilization of metal/oxide interfaces via suppressed oxygen diffusion in BEOL-compatible InGaZnO thin-film transistors

초록

This study systematically investigates the influence of post-metallization annealing (PMA) ambient on the electrical and interfacial properties of a-IGZO thin-film transistors (TFTs) incorporating BEOL-compatible tungsten (W) contacts. The devices were annealed at 300 degrees C and 350 degrees C using oxygen rapid thermal annealing (O2 RTA) and high-pressure deuterium annealing (HPDA). The HPDA-treated devices exhibited enhanced electrical performance, including reduced subthreshold swing (74 mV dec-1), increased Ion/Ioff ratio, and lowered contact resistance (RCW = 5.74 Omega cm). These improvements are attributed to the passivation of interfacial defects and the formation of W-D bonds, which effectively suppress interfacial oxidation. Furthermore, based on density functional theory (DFT) calculations, it was noted that HPDA promotes W-D bond formation, which can play an important role as an oxygen diffusion barrier. These theoretical results give a physical basis for the dual role of deuterium in defect passivation and suppression of interfacial oxidation at the W electrode, consistent with the HPDA observations of decreased W 4f binding energy and reduced WOx formation.

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