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/SiO2 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 SiO2. Possible types of deep and shallow electron traps in the near-interfacial SiO2 are discussed.