I-V characteristics of electron-cyclotron-resonance plasma-enhanced chemical-vapor-deposition silicon nitride thin films

Abstract

Silicon nitride thin films were fabricated by electron-cyclotron-resonance plasma-enhanced chemical-vapor deposition (ECR PECVD) at room temperature and current-voltage characteristics were analyzed. A ledge in the first I-V curve always appeared in ECR PECVD silicon nitride films and then disappeared in the subsequent I-V curves. It turned out that the trapped charges caused by injection of electrons were responsible for the ledge in the I-V curves of fresh samples. A new conduction mechanism for low electric field was proposed, namely trapping current by tunneling. This model turned out to be very successful to explain the low-field I-V characteristics in ECR-PECVD silicon nitride films, such as temperature dependence of I-V curves and the reverse current phenomenon. Computer simulation suggested the trapping cross section as 1×10−16 cm2 and the trap density as 7×1018 cm−3. The calculated trapping cross section corresponds to that of the neutral trap centers, which agrees well with the experimental results.