Improvement of SiO₂/Si Interface Properties Utilising Fluorine Ion Implantation and Drive-in Diffusion

Thermal drive-in diffusion of ion-implanted F atoms has been employed to fluorinate SiO 2 /Si interfaces and thereby improve their electrical properties. The interface state density can be lowered with little fixed charge generation. Correspondingly, pn-junction surface leakage current decreases. Furthermore, the interfaces can be hardened against hot-electrons due to Fowler-Nordheim current injection and avalanche current at the junction surface. As a result, a fluorinated MOSFET shows higher hot-carrier immunity. It is pointed out that there is an optimal F dose for these improvements to be achieved.