Investigation of the effect of ionizing radiation on M.O.S. devices with plasma anodic SiO2 as the insulator

The anodization of silicon in an oxygen plasma produces silicon dioxide (SiO2) insulators that are inherently better than thermal oxides becausea) they are grown in a clean environment, andb) their crystal structure is more ordered.Metal-oxide-semiconductor transistors (MOSTs) and metal-oxide-semiconductor capacitors (MOSCs) are fabricated in two plasma anodization systems in an effort to produce a high quality plasma SiO2. Thedevices with the best SiO2 layers are used in radiation tests. For comparison purposes, MOSTs and MDSCs with thermal SiO2 and thermal HCl are used.Radiation tests performed on the devices indicated that plasma anodic SiO2 holds promise of being more radiation resistant than thermal SiO2. This is only a tentative conclusion, however, since the plasma oxide results were not consistently better than the results for all the thermal oxides. This may, at least in part, be due to the usually high degree of sodium contamination present in the plasma SiO2 introduced during the MOST fabrication procedure after the growth of the plasma SiO2.