Time-dependent dielectric breakdown of SiO2 films in a wide electric fieldrange

We have performed time dependent dielectric breakdown measurement of SiO2 f ilms in the electric field (E-OX) range 7-13.5 MV/cm and evaluated the elec tric field dependence of intrinsic lifetime, using both area and temperatur e dependences of oxide lifetime. We have evaluated the electric held depend ence of time to breakdown (t(BD)) below 125 degreesC, because the activatio n energy of intrinsic lifetime changes at 125 degreesC t(BD) of 7.1 and 9.6 MI oxides is not proportional to exp(E-OX) but proportional to exp(1/E-OX) . This suggests that the breakdown mechanism of 9.6 and 7.1 nm oxides is th e same and adheres to the anode hole injection model. However, the breakdow n mechanism of 4.0 nm oxides is not the same as that of 7.1 and 9.6 nm oxid es. The slope of log(t(BD)) versus 1/E-OX plot in 4.0 nm oxide increases wi th decreasing oxide fields. The intrinsic lifetime in the positive gate bia s decreases with increasing oxide thicknesses in the range of electric fiel ds employed in the present experiment. (C) 2001 Elsevier Science Ltd. All r ights reserved.