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 ;8 3 10 ÿ10 to 2 3 10 ÿ8 A/cm 2 at 1 MV/cm in SiOC:H dielectrics in a Cu-gated capacitor, and a lower 2 3 10 ÿ10 to 5 3 10 ÿ10 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 1 ions in the Cu/TaN/Tagated capacitor was lower than that in a Cu-gated capacitor. A physical model was developed to explain the observed kinetics of Cu 1 ions that drift in Cugated 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 1 ions, which determines the breakdown acceleration. Good Cu 1 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.