Vacuum UV Spectroscopic Ellipsometry and X-Ray Reflectance Combined on the same Platform for the Characterization of High-k Gate Dielectrics

Vacuum UV Spectroscopic Ellipsometry and X-Ray Reflectance combined on the same platform for the characterization of high-k gate dielectrics. Christophe DEFRANOUX, Alexis BONDAZ, Laurent KITZINGER, Jean Philippe PIEL. SOPRA 26 rue Pierre Joigneaux, 92270 Bois-Colombes, France christophe.defranoux@sopra-sa.com . New high-k dielectric materials are intensively investigated to replace the silicon dioxide as gate dielectric in the next generations of electronic devices. The layer thickness which will be used in the future devices is of the order of some nanometers and a precise control of this critical stage of the process will be mandatory. In this respect, spectroscopic ellipsometry has long been recognized as a powerful technique for thin film characterization and is now used routinely to control thin films and multilayers at different stages of the device fabrication process. For very thin layers like for high-k dielectrics, the interface property plays a key role in the device. A precise physical model is then needed to extract accurate information from ellipsometry. In addition, since these layers are completely transparent in the visible and UV range, the correlation between thickness and refractive index is very high and so, structural and thickness information cannot be extracted independently with standard ellipsometry.