Effect of early stage growth on moisture permeation of thin-film Al2O3 grown by atomic layer deposition on polymers

The authors investigated moisture permeation for Al2O3 barrier films grown by atomic layer deposition (ALD) on the two individual chemically distinct surfaces of a commercial (DuPont Teijin Films, Chester, VA) polyethylene terephthalate (PET) film. One surface is “bare” PET polymer, whereas the opposite surface is coated with a low friction “slip” layer to facilitate winding and unwinding of the polymer film on a roll. For early stage Al2O3 film growth (<8 nm), the authors found that moisture permeation was less on the bare polymer side than the slip side but converged to same instrument limited value (∼1 × 10−4 g H2O/m2 day) for thicker films. However, thicker barrier films grown on the slip side experienced abrupt permeation breakthrough in longer-term Ca-testing at 60 °C/85% RH, whereas equivalently grown barrier films on the bare PET-side were stable. Mildly etching the slip side in Ar, before depositing Al2O3, resulted in permeation performance equivalent to barriers grown on the bare polymer side. T...