Influence of PE-CVD and PE-ALD on defect formation in permeation barrier films on PET and correlation to atomic oxygen fluence

A combinatorial approach to enhance barrier properties of thin films on polymers: Seeding and capping of PECVD thin films by PEALD

“…As n def was decreased already for a 1 nm seeding layer with the OTR remaining at the same values as an uncoated PET foil, the OTR seems to be strongly dependent on the overall thickness of the GBL. As reported earlier for GBLs from PECVD, a decreased macro defect density improved the barrier performance. Compared to GBLs comprised of only one binary oxide from PEALD (Figure ), the found OTRs were of the same order of magnitude for comparable thicknesses.…”

“…Similarly low defect densities were found in PECVD grown thin films with thicknesses around 100 nm. In addition, the remaining defect density for the GBL comprised of a 5 nm seeding‐layer (PEALD) and a 15 nm SiO x (PECVD) exhibited a defect density comparable to that of a 20 nm TiO 2 thin film from PEALD, which was reported earlier, indicating the ability of PEALD coatings to facilitate improved growth of the subsequently grown PECVD SiO x . As n def was decreased already for a 1 nm seeding layer with the OTR remaining at the same values as an uncoated PET foil, the OTR seems to be strongly dependent on the overall thickness of the GBL.…”

“…Applying a 2.5 nm seeding layer improved OTR (63 cm 3 m −2 day −1 ) slightly when compared with the 1 nm seeding layer, indicating that the film was not entirely closed for the 1 nm seeding‐layer, while n def was found to be unaffected with a value of 83 defects mm −2 . For a 5 nm thick seeding layer, both the OTR and defect density were found to decrease significantly with values of 0.8 cm 3 m −2 day −1 for the OTR and 9 macro defects mm −2 , which are remarkable values compared to defect densities of PECVD grown SiO x (>60 macro defects mm −2 ) . Similarly low defect densities were found in PECVD grown thin films with thicknesses around 100 nm.…”

“…Defect densities were quantified by the established technique, based on etching all samples for 1 h in a capacitively coupled oxygen plasma (CCP) and subsequent imaging by SEM . Further details on the defect density quantification can be found elsewhere . Reactive oxygen species from a CCP plasma were used to etch the polymer beneath the deposited GBLs.…”

“…Additionally, materials from PEALD usually exhibit high mass density values . It was shown recently that PEALD grown thin films of TiO 2 show a strongly decreased defect density, compared with different PECVD grown SiO x and a‐Si:H thin films, which can be correlated with an improved barrier performance toward oxygen gas . Such PEALD thin films demonstrated an improved barrier against water ingress, i.e., lower WVTR values, compared with SiO x of the same thickness .…”