Detection of surface electronic defect states in low and high-k dielectrics using reflection electron energy loss spectroscopy

The continuation of Moore’s law requires new materials at both extremes of the dielectric permittivity spectrum and an increased understanding of the fundamental mechanisms limiting their electrical reliability. To address the latter, reflection electron energy loss spectroscopy has been utilized to measure the band gap of various oxide-based low and high dielectric constant (k) materials of interest to the semiconductor industry. In situ Ar+sputtering has been additionally utilized to simulate process-induced defect states that are believed to contribute to electrical leakage, time-dependent dielectric breakdown, charge trapping, and other fixed-charge reliability issues in nano-electronic devices. It is observed that Ar+sputtering predominantly generates surface oxygen vacancy defects in the upper portion of the band gap for both low and high-kdielectric materials. These results are in agreement with numerous theoretical investigations of defects in low and high-kdielectric materials and models for mechanisms that limit their reliability.