The role of electron transport and trapping in MOS total-dose modeling

Radiation-induced hole and electron transport and trapping are fundamental to MOS total-dose models. Here we separate the effects of electron-hole annihilation and electron trapping on the neutralization of radiation-induced charge during switched-bias irradiation for hard and soft oxides, via combined thermally stimulated current (TSC) and capacitance-voltage measurements. We also show that present total-dose models cannot account for the thermal stability of trapped electrons near the Si/SiO/sub 2/ interface, or the inability of electrons in deep or shallow traps to contribute to TSC at positive bias following (1) room-temperature, (2) elevated-temperature, or (3) switched-bias irradiation. These results require modifications to modeling parameters and boundary conditions for hole and electron transport in SiO/sub 2/. Possible types of deep and shallow electron traps in the near-interfacial SiO/sub 2/ are discussed.