By Xps Hf As The Main Ingredient High-k Material, The Thermal Stability Study

The thermal stability of high-k thin film deposited on Si substrate has been studied using X-ray photoelectron spectroscopy (XPS). We focused our attention on Hf-based materials, which are promising candidates for gate oxide materials in CMOS.We prepared laminated thin Al₂0₃-Hf0₂ film, HfAlO and HfO₂ thin film respectively. The laminated and HfAlO compound thin films were treated by RTA at 900℃. Comparison of as-deposited and RTA samples showed that RTA had strong impact on laminate film.In order to investigate the interfacial reaction of high-k thin film on Si substrate, the high-k samples were studied by XPS as a function of annealing temperature. XPS results showed that for laminated sample, silicate compounds in interface layer are formed below 900℃ and HfAlO is more stable. These high-k materials degraded to silicide island at temperatures of higher than 950℃.These results are consistent with RTA samples.We found that the thermal stability of HfAlO film is best in these samples.