Amorphous SiCN (a-SiCN) is a candidate for barrier dielectric and has lower dielectric constant (ksimilar to5) relative to the commonly used barrier SiN (ksimilar to7). In this study, we investigate the leaky behavior and barrier characteristics of a-SiCN (k: 4similar to5) doped with different nitrogen concentration. The leaky behavior of a-SiCN is Poole-Frenkel at high electric field. This is similar to SiN. Thermal stability of a-SiCN films is good enough to meet the prescription in back-end-of-line fabrication process. The bias-temperature stress (BTS) test has been conducted on a-SiCN to investigate the barrier ability against copper 15/16penetration. We find that a-SiCN could sustain the stress of electric field up to 4 mV/cm at 150 degreesC. In addition, a-SiCN films with higher nitrogen concentration exhibit better barrier property against copper penetration. The SIMS spectra also have been used to monitor the distributions of copper after different BTS conditions, confirming our inference on leakage mechanism. (C) 2003 Elsevier Science B.V. All rights reserved.