Plasma nitridation optimization for sub-15 A gate dielectrics

摘要

The work investigates the impact of plasma nitridation process parameters upon the physical properties and upon the electrical performance of sub-15 A plasma nitrided gate dielectrics. The nitrogen distribution and chemical bonding of ultra-thin plasma nitrided films have been investigated using XPS. It is shown that N-Si3 bonds are dominant in the ultra-thin plasma nitrided films, and that O2=N-Si bonding configuration is observed when no PNA is applied after the plasma nitridation. The EOT reduction due to an increase of N in the film is not a monotonic increasing function of the DPN time. It seems that there is an optimum N concentration for a given thickness of the base oxide that enables the continued down scaling of DPN base dielectrics.