Modification of metal-oxide-semiconductor devices by electron injection in high fields

Abstract

The modification of metal-oxide-semiconductor (MOS) devices having Si/SiO 2/phosphosilicate glass/Al structure by Fowler–Nordheim (FN) tunnelling electron injection taking place in high fields is studied. The constant current FN electron injection from silicon substrate and metal electrode was used to modify the charge state of the MOS structure. The parameters characterizing the change of charge state in the MOS structures during the modification have been monitored by means of time dependence of voltage shift applied to a sample during the injection. It was found that the changes in the range of threshold voltage in MOS devices, which resulted from the electron injection, could reach values up to 6 V, while the range is extended with the growth of the concentration of phosphorus in the PSG layer. However, the value of the injected charge must not exceed the level of 0.1 mC/cm 2 during the adjustment of the threshold voltage, so as to provide acceptable surface state density.