Influence of bias-temperature stressing on the electrical characteristics of SiOC : H film with Cu/TaN/Ta-gated capacitor

Abstract

Experiments on bias-temperature stressing, capacitance-voltage measurements, current-voltage characteristics, and time-dependent dielectric breakdown were performed to evaluate the reliability of Cu and low-k SiOC:H integration. A high leakage current of similar to 8 X 10(-10) to 2 X 10(-8) A/cm(2) at 1 MV/cm in SiOC:H dielectrics in a Cu-gated capacitor, and a lower 2 X 10(-10) to 5 X 10(-10) A/cm(2) at 1 MV/cm in a Cu/TaN/Ta-gated capacitor, were observed at evaluated temperatures. The drift mobility of the Cu ions in the Cu/TaN/Ta-gated capacitor was lower than that in a Cu-gated capacitor. A physical model was developed to explain the observed kinetics of Cu+ ions that drift in Cu-gated and Cu/TaN/Ta-gated capacitors. The electric field in the Cu-gated MIS capacitor in the cathode region is believed to be increased by the accumulation of positive Cu+ ions, which determines the breakdown acceleration. Good Cu, ions drift barrier layers are required as reliable interconnects using thin TaN and Ta layers. Additionally, Schottky emission dominates at low electric fields, E < 1.25 MV/cm, and Poole-Frenkel emission dominates at high fields, E > 1.5 MV/cm.