Annealing temperature modulated interfacial chemistry and electrical characteristics of sputtering-derived HfO2/Si gate stack

Abstract

Sputtering-derived HfO2 high-k gate dielectric thin films have been deposited on Si substrate by means of high vacuum physics vapor deposition method. Via characterization from x-ray photoelectron spectroscopy (XPS) and electrical measurements, the effect of post-deposition annealing temperature on the interfacial and electrical properties of HfO2/Si gate stack has been investigated. XPS analyses show that an interfacial layer between HfO2 and silicon substrate has been found in the post-deposition annealing process. Increase in Hf-silicate layer and reduction in SiO2 low-k interface layer have been detected. Electrical measurements of MOS capacitor based on Al/HfO2/Si gate stacks indicate that annealing HfO2 sample at 300 °C demonstrated the improved electrical performance. As a result, the leakage current of 3.60 × 10−5 A/cm2 at applied substrate voltage of 2 V, which is much lower than those samples annealed at other temperature, has been obtained. The leakage current mechanism for different annealing temperature has been discussed systematically.