Vapor-Phase Self-Assembled Monolayer With Functional Groups as a Copper Diffusion Barrier Layer for InSnZnO Thin-Film Transistors

Controlling the contact properties of a copper (Cu) electrode is crucial for enhancing the performance of InSnZnO (ITZO) thin-film transistors (TFTs) in high-speed applications. This is due to the inherently low resistance-capacitance product constant of Cu. High diffusivity of Cu, when integrated into ITZO, poses a major challenge as it leads to the formation of detrimental electron trap states, resulting in performance degradation of ITZO TFTs. A self-assembled monolayer (SAM) serves a dual purpose, effectively functioning as a diffusion barrier (DB) for Cu and a passivation layer. The study showcases the efficacy of vapor-phase SAM with suitable functional groups in enhancing the electrical properties of ITZO TFTs, with SAMs featuring -SH groups being particularly effective. The impressive electrical performance of SAMs with -SH groups makes them highly effective as Cu DBs and passivation layers. These versatile SAMs exhibit potential as a great choice for a thin copper DB in upcoming electronic technologies.