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 (similar to 8 angstrom) has been achieved with increased effective permittivity (k similar to 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.