Water vapor transmission rate property of SiNx thin films prepared by low temperature (<100 °C) linear plasma enhanced chemical vapor deposition

We used an inline system equipped with a linear plasma enhanced chemical vapor deposition (L-PECVD) source available at low temperatures for the thin film encapsulation of flexible organic light emitting diode displays. This inline system can be used for coating on a moving substrate, which can increase productivity than a cluster system with the typical PECVD source. In this paper, we report the excellent water vapor barrier properties of SiNx films deposited on PEN film substrates at low temperatures process using the L-PECVD source. The SiNx thin film was deposited using silane (SiH4), ammonia (NH3) and helium (He) gases. The SiNx thin film deposited by L-PECVD showed good results for pinhole, grain boundary, stress, wet etch which are defects that can affect the lifetime of the OLED. The moisture permeation characteristics of the optimized SiNx thin films were finally measured using a MOCON's WVTR measuring instrument and WVTR values lower than the detection limit of the measuring device (less than 5.0 × 10−5 g/m2·day) were obtained. Based on these results, SiNx deposited using the L-PECVD is considered a good candidate for TFE (Thin Film Encapsulation) application of flexible OLEDs.