Investigation of Rare-Earth Stacked Dielectric for Next Generation Nano CMOS Device Applications
DescriptionTo maintain proper control over the channel current of a complementary metal-oxidesemiconductor (CMOS) transistor with a small gate bias, high-dielectric constant (high-k) gate dielectric film must be used for the nanoscale CMOS device-s. The hafnium-based materials used in the state-of-the-art CMOS circuit fabrication will no longer be suitable for the sub-nanometer thick (silicon oxide equivalent thickness) gate dielectric required in the coming technology nodes. Rare-earth (RE) lanthanum oxide (La2O3), having a k value of about 27 and large band offsets at the silicon interface, has been considered as one of the promising candidates for this kind of applications. However, there are still many issues, such as hygroscopic nature, poor interface properties, and poor thermal instability etc., needed to be resolved before it can be brought into the actual CMOS manufacturing process. In this project, we attempt to make use the multivalent nature of the RE cerium oxides (CeO2 and Ce2O3) to improve the material properties of the La2O3 gate dielectric film. We are going to make use of the redox process of the cerium oxides to control the oxygen chemical potential of the La2O3 film and then to reduce its defect density. Various aspects of the material properties, chemical interactions and their impacts on the electrical properties of MOS transistors will be studied in detail.
|Effective start/end date||1/05/12 → 11/03/14|