Hole Trap Creation in SiO2 by Phosphorus Ion Penetration of Polycrystalline Silicon

Anomalously deep penetration of polycrystalline silicon by high energy phosphorus ions is shown to produce large concentrations of hole traps in MOS devices. In some cases the damage created by the implantations could not be detected in pre-irradiation characteristics. A strong dependence of hole trap concentration on implantation dose was found up to very high doses, and the effects of ion energy and silicon thickness were determined. The observations and results are directly applicable to the definition of a radiation hardened MOS process.