Polymer layers by initiated chemical vapor deposition for thin film gas barrier encapsulation

A combination of SiNx and polymer layers, in our case poly(glycidyl methacrylate) (PGMA) is very suitable as a permeation barrier layer on sensitive electronic devices. Our experiments thus far concentrate on increasing the stability and deposition rate of the polymer layers. To reach the thermal stability needed for the deposition of SiNx on PGMA by HWCVD, the PGMA chain length must be large. PGMA with a very high molecular weight (MW) (78,000 Da, ~ 548 monomers) was deposited at a high deposition rate (> 60 nm/min). To mimic the reactive atomic H ambient during SiNx deposition conditions during HWCVD, the polymer layers were exposed to an atomic hydrogen environment for 0 to 550 s. Surprisingly, the most important factor for stability under these conditions was the filament temperature which was used during PGMA deposition, rather than the expected parameters such as MW or surface roughness. Using lower filament temperatures for PGMA deposition, the layers were much more stable in atomic H ambient.