High Performance Poly-Si Thin Film Transistors Fabricated by Novel and Simple Crystallization Method Using Ni-Silicide Seeds

Abstract

The major problem of metal-induced crystallized (MIC) polycrystalline Si (poly-Si) thin- film transistors (TFTs) is metal contamination, from Ni and NiSi2. Many attempts have been made to address this problem, however, they all involve complicated processes. In this study, we investigate a new crystallization method, that is, seed-induced crystallization, using Ni silicide seed. There are no additional mask processes, deposition and/or etching processes. The poly-Si thin films crystallized by SIC are characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Auger electron spectroscopy (AES), atomic force microscopy (AFM), micro-Raman scattering spectroscopy and the electrical properties are obtained from ID-VG transfer curve measurements. The results show that, lower Ni contamination, smoother surface and larger grain size are achieved in the SIC produced poly-Si thin films compared to those of the MIC poly-Si thin films. The p-channel SIC poly-Si TFTs, show a mobility of 62.08 cm2/V·s, minimum leakage current of 1.17 × 10−10 A at VD = 10 V, subthreshold slope of 0.7 V/dec and maximum on/off ratio of 1.7 × 106, all of which lead to a high-performance device which exceeds conventional MIC poly-Si TFTs.