Effect of H-2 addition during PECVD on the moisture barrier property and environmental stability of H:SiNx film

Abstract

A hydrogenated silicon nitride (H:SiNx) film with enhanced moisture barrier property and environmental stability was developed using plasma-enhanced chemical vapor deposition (PECVD) with the addition of H-2 gas at 100 degrees C. The moisture barrier property and film density of the 100-nm-thick H:SiNx film were ameliorated by increasing the H-2 gas flow rate during PECVD. X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy studies demonstrated that the improved performance was a result of an increase in the amount of Si-N bonds compared to hydrogen-terminated bonds with an increase in the H-2 gas flow rate. It is believed that H-2 gas assisted the formation of aminosilane, which contributed to the condensation of silicon nitride by lowering the activation energy for radicalization reactions of silane and ammonia. After the 85 degrees C/85% RH test, the optimized H:SiNx film maintained a water vapor transmission rate lower than 5 x 10(-5) g/m(2)/day owing to the suppression of oxidation. The optimized H:SiNx film was rarely oxidized owing to the decrease in hydrogen-terminated bonds and increase in the film density. The results indicated that the introduction of H-2 gas during the PECVD process strengthened the environmental stability of the H:SiNx film.