Oxide breakdown mechanism and quantum physical chemistry for time-dependent dielectric breakdown

Abstract

Abstruct-Thermochemical-breakdown and hole-inducedbreakdown models are theoretically formulated to explain the field-acceleration of TDDB phenomenon. Long-term TDDB test results proved to support the thermochemical-breakdown model. The time-dependent oxide breakdown mechanism is further studied on the basis of quantum physical chemistry. The structural transformations of a-Si02 up to breakdown are simulated by the semiempirical molecular orbital calculation method (PM3 method) using Si5OI6H12 clusters. The structural transformations can be classified into (a) amorphous-like-Si02 (a-Si02), (b) holetrapped-Si02 (hole-trap), and (c) electrically-brokendown-Si02 (breakdown) structures. The atom configuration shows a shortened length between the nearest oxygen atoms due to hole trapping. This leads to oxide breakdown, and the breakdown structure consists of a pair of oxygen-excess (Si-0-0-Si) and oxygenvacancy (Si-Si) defects. The heat of formation and frontier orbital energies of structural transformations account well for the physical aspects of the TDDB phenomenon.

Thin-Gate-Oxide Breakdown and CPU Failure-Rate Estimation

“…The activation energy obtained from Fig. 3 is within the industry trend and published data [18]. Non-Arrhenius dependence and voltage-temperature coupling effects have also been reported [19].…”

Ultrathin gate oxide reliability: physical models, statistics, and characterization

“…was observed to decrease for increasing applied gate voltage or electric field [14], [22], [79] which was predicted by the Thermochemical model [14]. In some reports the was observed to change with temperature [80].…”

“…Researchers attempted to validate the models by conducting tests over long periods of time [20]- [22] and accelerated temperatures [23], [24] to facilitate the collection of breakdown data at lower electric fields. The data reported in [20], [22]- [24] indicated that the logarithm of the time-to-failure was linear with electric fields closer to operating conditions. It was pointed out, however, that the values of the electric field acceleration parameters reported in the studies were greater than what the thermochemical model predicted [25].…”

“…The trend suggests a voltage-driven breakdown model. Data is derived from [3], [13], [20], [22], [24], [114], [115].…”

Temperature dependence of soft breakdown and wear-out in sub-3 nm SiO/sub 2/ films

“…The figure shows that thicker oxides generally exhibit a smaller activation energy for the same stress electric field. This may be due to differences in defect generation or electron energy transfer in thick and ultra-thin It should also be pointed out that not all oxides exhibit a decreasing thermal activation energy with gate voltage or electric field as discussed in [15,17]. Figure 12 illustrates that care must be used when comparing the thermal acceleration as a function of oxide thickness since two films of different oxide thickness can have a similar or different thermal activation energy depending on the stress gate voltage.…”