AVS 54th International Symposium | |
Thin Film | Monday Sessions |
Session TF-MoM |
Session: | Atomic Layer Deposition and Applications |
Presenter: | S.M. George, University of Colorado at Boulder |
Authors: | A.A. Dameron, University of Colorado at Boulder S.M. George, University of Colorado at Boulder P.F. Carcia, DuPont Research and Development R.S. McLean, DuPont Research and Development |
Correspondent: | Click to Email |
Flexible, ultrathin gas diffusion barriers are required for the protection of organic electronics, e.g. organic light emitting diodes (OLEDs) in flexible displays. Existing barriers provide insufficient protection from permeating H2O and O2 gases. Our earlier work demonstrated that a low water vapor transmission rate (WVTR) of ~1 × 10-3 g/m2/day could be achieved on polyethylene naphthalate (PEN) and Kapton using Al2O3 ALD films with thicknesses of ~25 nm. These H2O transmission rates are not low enough to meet OLED requirements. The Al2O3 ALD films also degrade over time with exposure to H2O vapor. To lower the H2O transmission rates further and to protect the Al2O3 ALD films, we have used additional layers in combination with the ~25 nm Al2O3 ALD layer. The additional layers were one layer of silicon nitride with a thickness of >60 nm deposited by plasma-enhanced chemical vapor deposition (PE-CVD) or one layer of SiO2 with a thickness of ~60 nm deposited using rapid SiO2 ALD. Both of these additional layers in combination with the ~25 nm Al2O3 ALD layer reduced the measured WVTR to ~1 × 10-4 g/m2/day. When deposited on top of the Al2O3 ALD film, these silicon-containing layers also protect the Al2O3 ALD film from H2O exposure. Nanolaminates of Al2O3 ALD and SiO2 ALD should further reduce the WVTRs. These nanolaminate films are fabricated by alternating the Al2O3 ALD and SiO2 ALD to create 2 bilayers, 3 bilayers or higher numbers of bilayers. Tests of multiple bilayer nanolaminate structures of Al2O3 ALD and SiO2 ALD on Kapton have yielded extremely low WVTRs of 5 × 10-5 g/m2/day using the HTO testing technique. These exceptionally low WVTRs are approaching the range that is necessary for OLED devices in flexible displays.