Electrical Conduction and Dielectric Breakdown in Silicon Dioxide Films on Silicon

Abstract

Conduction through SiO2 films, thermally grown on Si substrates, was found to take place via a Fowler‐Nordheim (F‐N) tunneling mechanism, after an initial transient current associated with trapping of charge, mobile ions, and space charge redistribution has died away. The temperature dependence of the steady‐state F‐N current decreases with increasing applied field and was found to be smaller in magnitude than previously reported. Typical post‐metalization annealing treatments (e.g., 5 min at 500°C in dry N2) lowers the conductivity of the MOS capacitor structures by two to three orders of magnitude, an effect that can be attributed to the elimination of either traps or fixed charge distributed throughout the oxide. For applied fields larger than 8 MV/cm, a current instability arises which can lead to dielectric breakdown. For a wide range of different electrode materials, the onset of this instability appears to correlate well with the temperature and oxide thickness dependences of breakdown, as observed earlier (10). These findings are discussed in terms of a model which suggests that carriers can be generated and redistributed by collision ionization processes within the oxide.

Mechanical stress field assisted charge de-trapping in carbon doped oxides

“…In a recent electron paramagnetic resonance (EPR) study, Pomorski et al [22] has shown that for a-SiOC:H SE dominates at moderate electric fields (>2.5 MV/cm), but at lower fields, leakage occurs through carbon dangling bond defect populations via other mechanisms such as variable range hopping (VRH). Similar conduction mechanism studies have been carried out for SiOC:H [17] and silicon dioxide [21] thin films as well. Another dominant mechanism for CDOs is the PF mechanism, where the excitation emits electrons from defects or traps into the conduction band of the dielectric.…”

“…Such carbon-rich microstructure may result in higher leakage currents, lower breakdown voltages, and shorter TDDB lifetimes [20]. For CDOs, the dominant mechanisms are known to be SE, where an energy barrier exists between the metal Fermi level and oxide conduction band, and the electron from the electrode can be emitted over the barrier to the oxide by thermal emission when an electric field is applied [21]. In a recent electron paramagnetic resonance (EPR) study, Pomorski et al [22] has shown that for a-SiOC:H SE dominates at moderate electric fields (>2.5 MV/cm), but at lower fields, leakage occurs through carbon dangling bond defect populations via other mechanisms such as variable range hopping (VRH).…”

Experimental Observations on Conduction Through Polysilicon Oxide

“…Unfortunately, our understanding of traps in electrically stressed silicon dioxide films remains far from clear (5)(6)(7)(8)(9)(10). Differentiation between models emphasizing the continuous generation of electron traps during large current flow in silicon dioxide subjected to high electric fields or the filling of previously existing traps, however, is not straightforward.…”

Comparison of device structures for the dielectric breakdown measurement of hexagonal boron nitride

“…Since the EBD value was not affected by the polarity of the voltage in the type B measurement, which has the highest structural symmetry, the difference in the electrode material and the work function of the metal is ignored. 16 In the actual experiment, the top electrode was grounded in all measurements. EBD was defined simply by EBD = VBD / th-BN, where VBD and th-BN are the breakdown voltage and the thickness of h-BN, respectively.…”