Contact Resistance Reduction in IGZO TFTs Using Al-Induced Microstructure Regularization

Abstract

Small-size In–Ga–Zn–O thin-film transistors (IGZO TFTs) exhibit significant potential for high-end display and memory applications; however, contact resistance remains a critical parameter limiting their miniaturization. To address this challenge, we designed a IGZO TFT with low contact resistance using Al-induced microstructure regularization technique. The contact resistance of the Al-TFT is 4 ± 2 KΩ·μm, which is significantly better than that of the ITO-TFT ((5 ± 4)×10³ KΩ·μm) and Mo-TFT ((1 ± 1)×10³ KΩ·μm). This is due to the different interfacial properties of Al/IGZO compared to Mo/IGZO and ITO/IGZO, with unique nanocrystalline structures, generation of metal oxide layers, and significant changes in In and Zn contents. Measurements of the contact potential difference also indicate that the ohmic contacts formed at the Al/IGZO contact interface are different from the Schottky contacts formed by Mo/IGZO and ITO/IGZO. These findings highlight the effectiveness of the Al-induced microstructure regularization technique in reducing contact resistance through microstructural changes.