Investigation of the electrical properties and reliability of amorphous SiCN

摘要

Amorphous SiCN (a-SiCN) is a candidate for barrier dielectric and has lower dielectric constant (k～5) relative to the commonly used barrier SiN (k～7). In this study, we investigate the leaky behavior and barrier characteristics of a-SiCN (k: 4～5) 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 (15/16) penetration, We find that a-SiCN could sustain the stress of electric field up to 4 mV/cm at 150℃. 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.