Effect of Thermal and Forming Gas Annealing on the Characteristics of Si/SiON/Ti-Pt MOS Capacitor

Abstract

We report the effect of thermal and formal gas annealing on the electro-physical characteristics of Si/SiON/Ti-Pt MOScap by analyzing high-frequency capacitance-voltage (C-V) and current-voltage (I-V) characteristics. Thermal and forming gas annealing (FGA) were carried out at the temperatures of 800°C for 15 min in Nitrogen (N2) ambient and at 420°C for 20 min in 95% N2 and 5% H 2 ambient respectively. Ellipsometery, Field Emission Scanning Electron Microscopy (FESEM), Atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR) were used to study the effect of thermal annealing on the physical characteristics of deposited silicon oxynitride film. We also present a comparative study between the as-deposited and annealed film for FGA and without FGA. It was found that annealed SiON with FGA shows significant improvement in electrical parameters $\boldsymbol{k}=6.3, {\boldsymbol{D}}_{\boldsymbol{it}}0.5\times 10^{11}\mathbf{eV}^{-1}\mathbf{cm}- 2$ & $\boldsymbol{Q_{eff}}=1.2\times 10^{12} \mathbf{cm}^{-2}$ which is further attributed to the improvement in Si/SiON interface properties. In the negative gate bias regime for both as-deposited and annealed SiON film, the maximum current through the Si/SiON/Ti-Pt device never exceeded a value of 100nA/cm2 which indicates that the film were very good insulators. For thermally annealed samples, the leakage current reduced from 10 nA/cm2(Without FGA) to 0.1nA/cm2 (With FGA) due to reduction in the density of defects in the SiON film. These results indicate that the obtained SiON film is an appropriate gate insulator for advanced nano electronic devices.