PHYSICS AND CHEMISTRY OF INTRINSIC TIME-DEPENDENT DIELECTRIC BREAKDOWN IN SiO₂ DIELECTRICS

A molecular physics-based complementary model, which includes both field-induced and current-induced degradation mechanisms, is used to help resolve the E versus 1/E time-dependent dielectric breakdown (TDDB) model controversy that has existed for many years. The Complementary Model indicates either the E or 1/E–TDDB model can be valid for certain specified field, temperature, and molecular bonding-energy ranges. For bond strengths < 3 eV, the bond breakage rate is generally dominated by field-enhanced thermal processes at lower fields and elevated temperatures where the E-model is valid. At higher fields, lower temperatures and higher bond strengths the bond breakage mechanism must be hole-catalyzed and the TDDB physics is described well by the 1/E-model. Neither the E-model nor 1/E-model works well for oxide thickness below t_ox < 4 nm where direct tunneling effects dominate in these hyper-thin films. The increase in DT leakage leads to more hole injection and trapping in the SiO₂. This enhanced dielectric degradation rate with t_ox reduction can be easily incorporated into the Complementary Model where hole capture serves to catalyze Si–O bond breakage.