Identification of the (√E+1/E)-dependence of porous low-k time dependent dielectric breakdown using over one year long package level tests

Abstract

Over-one-year-long test results for low-k dielectric TDDB are reported.A methodology has been set up to compare different models that predict lifetime.The lucky-electron model shows a higher ability to predict dielectric lifetime.The fitting parameters are determined independently from the MTTF fit. In the present paper, different analytical lifetime models have been assessed on porous low-k dielectrics (in CMOS 28nm structures) to predict lifetimes. Quantitative comparisons are made thanks to over-one-year-long low-field reliability tests. The lucky electron model (fitted at high fields) shows its higher ability to predict the dielectric mean-time-to-failure (MTTF) at low-field. Then the fitting parameters of this model (α=32 et γ=14.5) have been determined independently from this MTTF fitting procedure: these new values (α=31 et γ=14), extracted from the analysis of both Poole-Frenkel conduction and initial leakage current, are in very good agreement with the MTTF-fitted ones. The consequences of this model are discussed.