title: Stress Management in Thin-Film Gas-Permeation Barriers.
abstract: Gas diffusion barriers (GDB) are essential building blocks for the protection of sensitive materials or devices against ambient gases, like oxygen and moisture. In this work, we study the mechanics of GDBs processed by atomic layer deposition (ALD). We demonstrate that a wide range of ALD grown barrier layers carry intrinsic mechanical tensile stress in the range of 400-500 MPa. In the application of these GDBs on top of organic electronic devices, we derive a critical membrane force (σ · h)crit = 1200 GPaÅ (corresponding to a layer thickness of about 300 nm) for the onset of cracking and delamination. At the same time, we evidence that thicker GDBs would be more favorable for the efficient encapsulation of statistically occurring particle defects. Thus, to reduce the overall membrane force in this case to levels below (σ · h)crit, we introduce additional compressively strained layers, e.g., metals or SiNx. Thereby, highly robust GDBs are prepared on top of organic light emitting diodes, which do not crack/delaminate even under damp heat conditions 85 °C/85% rh.
authors.affiliation: Institute of Electronic Devices, University of Wuppertal , Rainer-Gruenter-Str. 21, 42119 Wuppertal, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Behrendt
authors.affiliation: Philips GmbH , Philipsstrasse 8, 52068 Aachen, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Meyer
authors.affiliation: Philips Research , High Tech Campus 7, 5656AE Eindhoven, The Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: van de Weijer
authors.affiliation: Institute of Electronic Devices, University of Wuppertal , Rainer-Gruenter-Str. 21, 42119 Wuppertal, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Gahlmann
authors.affiliation: Institute of Electronic Devices, University of Wuppertal , Rainer-Gruenter-Str. 21, 42119 Wuppertal, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Heiderhoff
authors.affiliation: Institute of Electronic Devices, University of Wuppertal , Rainer-Gruenter-Str. 21, 42119 Wuppertal, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Riedl
keywords: atomic layer deposition; gas diffusion barrier; mechanical stress; organic electronics; thin-film encapsulation