Effect of Ultrathin Silicon Oxide Film for Enhanced Performance and Reliability of Metal-Induced Laterally Crystallized Thin-Film Transistors Using Silicon Nitride as a Gate Dielectric

Abstract

In this work, we successfully fabricated high performance and excellent reliability of metal-induced laterally crystallized (MILC) polycrystalline-silicon thin-film transistors (poly-Si TFTs) with various surface treatments. The MILC poly-Si TFTs using silicon nitride as a gate dielectric shows high grain-boundary and interface trap-density with the MILC poly-Si film. Therefore, several surface treatment techniques, including oxidizing silicon surface with HNO3, H2SO4, and HCl, as well as N2O plasma treatment, were investigated. Comparing the characteristics of the proposed MILC poly-Si TFTs, the N2O plasma treated was the most effective, showing superior electrical performance and reliability to the other surface treatment methods. The role of the N2O plasma is to insert nitrogen into the poly-Si surface, which causes a relaxation and passivation of the trap states by producing Si≡N strong bonds, while the surface treatments using acids simply oxidize Si atoms.