Physics and Chemistry of Intrinsic Time-Dependent Dielectric Breakdown in SiO2Dielectrics

Abstract

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 tox < 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 tox reduction can be easily incorporated into the Complementary Model where hole capture serves to catalyze Si–O bond breakage.