Hafnium Titanate bilayer structure multimetal dielectric nMOSCAPs

A novel approach of fabricating laminated TiO₂/HfO₂ bilayer multimetal oxide dielectric has been developed for high-performance CMOS applications. Ultrathin equivalent oxide thickness (∼8 Å) has been achieved with increased effective permittivity (k∼36). Hysteresis was significantly reduced using the bilayer dielectric. Top TiO₂ layer was found to induce effective negative charge from the flatband voltage shift. Leakage current characteristic was slightly higher than control HfO₂, and this is believed to be due to the lower band offset of TiO₂. However, the interface state density of this bilayer structure was found to be similar to that of HfO₂ MOSCAP because the bottom layer is HfO₂. These results demonstrate the feasibility of new multimetal dielectric application for future CMOS technology.