title: Low-Temperature Plasma-Assisted Atomic Layer Deposition of Silicon Nitride Moisture Permeation Barrier Layers.
abstract: Encapsulation of organic (opto-)electronic devices, such as organic light-emitting diodes (OLEDs), photovoltaic cells, and field-effect transistors, is required to minimize device degradation induced by moisture and oxygen ingress. SiNx moisture permeation barriers have been fabricated using a very recently developed low-temperature plasma-assisted atomic layer deposition (ALD) approach, consisting of half-reactions of the substrate with the precursor SiH2(NH(t)Bu)2 and with N2-fed plasma. The deposited films have been characterized in terms of their refractive index and chemical composition by spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). The SiNx thin-film refractive index ranges from 1.80 to 1.90 for films deposited at 80 °C up to 200 °C, respectively, and the C, O, and H impurity levels decrease when the deposition temperature increases. The relative open porosity content of the layers has been studied by means of multisolvent ellipsometric porosimetry (EP), adopting three solvents with different kinetic diameters: water (∼0.3 nm), ethanol (∼0.4 nm), and toluene (∼0.6 nm). Irrespective of the deposition temperature, and hence the impurity content in the SiNx films, no uptake of any adsorptive has been observed, pointing to the absence of open pores larger than 0.3 nm in diameter. Instead, multilayer development has been observed, leading to type II isotherms that, according to the IUPAC classification, are characteristic of nonporous layers. The calcium test has been performed in a climate chamber at 20 °C and 50% relative humidity to determine the intrinsic water vapor transmission rate (WVTR) of SiNx barriers deposited at 120 °C. Intrinsic WVTR values in the range of 10(-6) g/m2/day indicate excellent barrier properties for ALD SiNx layers as thin as 10 nm, competing with that of state-of-the-art plasma-enhanced chemical vapor-deposited SiNx layers of a few hundred nanometers in thickness.
authors.affiliation: Department of Applied Physics, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: Anne-Marije
authors.initials: AM
authors.lastname: Andringa
authors.affiliation: Department of Applied Physics, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands.|Dutch Polymer Institute (DPI) , P.O. Box 902, 5600 AX Eindhoven, The Netherlands.
authors.forename: Alberto
authors.initials: A
authors.lastname: Perrotta
authors.affiliation: Department of Applied Physics, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
authors.forename: Koen
authors.initials: K
authors.lastname: de Peuter
authors.affiliation: Department of Applied Physics, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands.|Oxford Instruments Plasma Technology , North End, Bristol BS49 4AP, United Kingdom.
authors.forename: Harm C M
authors.initials: HC
authors.lastname: Knoops
authors.affiliation: Department of Applied Physics, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands.|Solliance Solar Research , High Tech Campus 5, 5656 AE Eindhoven, The Netherlands.
authors.forename: Wilhelmus M M
authors.initials: WM
authors.lastname: Kessels
authors.affiliation: Department of Applied Physics, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands.|Solliance Solar Research , High Tech Campus 5, 5656 AE Eindhoven, The Netherlands.
authors.forename: Mariadriana
authors.initials: M
authors.lastname: Creatore
keywords: atomic layer deposition; calcium test; ellipsometric porosimetry; moisture permeation barrier layers; plasma; silicon nitride