Electrical conduction mechanism and breakdown property in sputter-deposited silicon dioxide films on polycrystalline silicon

Abstract

Silicon dioxide films are sputter deposited on polycrystalline silicon (polysilicon) in an oxygen-argon atmosphere at 200 °C. Electrical conduction and breakdown are measured at various gate fields and temperatures. In addition to the Fowler–Nordheim tunneling current reported for thermal oxide, the sputter-deposited films have another, newly identified high-activation-energy current as electrical conduction mechanisms. The high-activation-energy current contribution to the total current is considerably reduced by increasing the oxygen mixing ratio and/or by decreasing the sputtering gas pressure, resulting in a considerable total current reduction. High-activation-energy current contributes little to the triggering of breakdown, unlike Fowler–Nordheim tunneling injections. In contrast to polysilicon thermal oxide, sputter-deposited films on polysilicon have no observable field enhancement in Fowler–Nordheim tunneling current, which indicates smooth surfaces. Thus, electrical properties in oxygen-argon sputter-deposited films on polysilicon are explained by high-activation-energy current and Fowler–Nordheim tunneling current.