Studies in remote plasma nitridation of silicon dioxide for metal-oxide-semiconductor gate dielectric applications

The semiconductor industry strongly relies on its ability to continuously scale device size to increase performance and reduce costs. However, this trend is being threatened by the physical limitations of the materials used. The "Metal-Oxide-Semiconductor" (MOS) capacitor and transistor are the devices being addressed in this work. The "OXIDE" in MOS is traditionally silicon dioxide (SiO2), the incorporation of N in the SiO2 (called nitridation) can be used to extend SiO 2 based gate insulator technology. The nitridation of SiO2 increases the dielectric constant of the material, thus allowing for physically thicker dielectrics to be used while maintaining the same electrically equivalent oxide thickness. The advantage of a physically thicker dielectric is that it reduces the susceptibility of the oxide integrity to process fluctuations and reduced direct tunneling gate leakage. Reduction gate leakage implied a more reliable film.; An attractive technique for nitrogen incorporation in SiO2 films is Remote Plasma Nitridation (RPN). In the RPN process, a high quality oxide is grown and then exposed to a nitrogen plasma under slight vacuum. Oxynitride films produced by RPN have been confirmed to have a 10 fold reduction in gate leakage over silicon dioxide films of same electrically equivalent oxide thickness. The RPN process results in nitrogen distributed throughout the film as well as near surface and at Si-SiO2 interface. The nitrogen distribution and bonding configurations are measured using Time of Flight Secondary Ion Mass Spectroscopy and Xray Photoelectron Spectroscopy, respectively. Using these analytical techniques, a model describing the nitrogen incorporation that predicts the observed electrical behavior for oxynitride thicknesses greater than 2.5 nm is achieved.; Investigations into the origin of the flatband voltage shifts allowed for the elimination of some potential candidates contributing to the shift. The change in density of the films as a function of nitrogen incorporation has also been studied, yielding a physical understanding of why the density remains approximately constant for 0--12 nitrogen atomic percent. Studies involving the alternate base oxide growth techniques and alternate RPN plasma sources are studied to better understand the mechanisms of nitrogen incorporation and origins of the dielectric constant increase.