Modification of MIS structures by electron irradiation and high-field electron injection

Abstract

The change in the charge state of metal–insulator–semiconductor (MIS) structures with a two-layer silicon-dioxide–phosphosilicate-glass gate insulator upon their modification under electron irradiation and high-field electron injection is studied. A thin glass film is formed by doping a thermal SiO2 film formed on the surface of a silicon wafer with phosphorus. It is found that the negative charge accumulated in a thin film of phosphosilicate glass during high-field tunneling electron injection or electron irradiation can be used to adjust the threshold voltage and to increase the charge stability and the breakdown voltage of MIS devices. It is shown that MIS structures need to be annealed at a temperature of approximately 200°C to obtain high thermal-field stability after modification of their charge state by the electron injection or electron irradiation. It is found that the use of a two-layer silicon-dioxide–phosphosilicate-glass gate dielectric increases the average value of the charge injected into the insulator to breakdown and decreases the amount of defect structures.