High performance thin film transistor with HfSiO x dielectric fabricated at room temperature RF-magnetron sputtering

Abstract

In this work, we investigated the enhanced performance of IZO-based TFTs with HfSiOx gate insulators. Four types of HfSiOx gate insulators with different deposition powers were deposited by co-sputtering HfO2 and Si. To simplify the processing sequences, all of the layers of the TFTs were deposited by an RF-magnetron sputtering method using patterned shadow-masks without any intentional heating of the substrate or subsequent thermal annealing. The four different HfSiOx structural properties were investigated by x-ray Diffraction (XRD), Atomic Force Microscopy (AFM), and the electrical characteristics were also analyzed. There were some noticeable differences depending on the composition of the HfO2 and Si combination. The TFT based on the HfSiOx gate insulator comprised of HfO2 (100 W)-Si (100 W) showed the best results with a field effect mobility of 2.0 cm2/V·s, a threshold voltage of 0.6 V, an Ion/off ratio of 3.18 × 105, and an insulator surface roughness of 0.16 nm RMS. This confirms that the composition of the HfO2 and Si is an important factor in an HfSiOx insulator. In addition, the effective bonding of the HfO2 and Si reduced the defects in the insulator bulk and also improved the interface quality between the channel and the gate insulator.