Charge Transport Mechanism in a PECVD Deposited Low-k SiOCH Dielectric

One of the most important issues during the selection of low-k dielectrics is related to their intrinsic properties including their electric breakdown and leakage current that are predominantly determined by conduction mechanisms. This study is devoted to elucidating the charge transport mechanism in the SiOCH low-k dielectric films fabricated by plasma-enhanced chemical vapor deposition. By analyzing four bulk-limited models of the charge transport it was found that only the Nasyrov-Gritsenko model of phonon-assisted electron tunneling between neutral traps describes the experimental I-V-T characteristics with all the fitting parameters with reasonable physical values. The obtained thermal trap energy value 1.2 eV is confirmed independently by photoluminescence spectroscopy data analysis. The trap nature and comparison of the obtained results with the corresponding data for low-k films with similar chemical composition and deposited by the spin-on-glass technology using self-assembling chemistry is discussed. It is hypothesized that the defect with ionization energy of 1.2 eV is the oxygen divacancy.