Materials Science, Integration, and Performance Characterization of High-dielectric Constant Thin Film Based Devices

Book excerpt: The knowledge obtained on the study of barrier properties of TiAl inspired a continuous research on the materials science issues related to the application of the hybrid TiAlOx, as high-k gate dielectric in MOSFET devices. Novel fabrication process such as deposition of ultra-thin TiAl alloy layer followed by oxidation with atomic oxygen has been established in this study. Stoichiometric amorphous TiAlOx layers, exhibiting only Ti4+ and Al3+ states, were produced with a large variation of oxidation temperature (700°C to room temperature). The interfacial SiOx formation between TiAlOx and Si was substantially inhibited by the use of the low temperature oxidation process. Electrical characterization revealed a large permittivity of 30 and an improved band structure for the produced TiAlOx layers, compared with pure TiO2. A modified 3-element model was adopted to extract the true C-V behavior of the TiAlOx-based MOS capacitor. Extremely small equivalent oxide thickness (EOT) less than 0.5 nm with dielectric leakage 4∼5 magnitude lower than that for SiO2 has been achieved on TiAlOx layer as a result of its excellent dielectric properties.