Gas diffusion ultrabarriers on polymer substrates using Al2O3 atomic layer deposition and SiN plasma-enhanced chemical vapor deposition
TL;DR: In this article, an Al2O3 film with a thickness of only 5 nm on a SiN PECVD film with thickness of 100 nm was shown to achieve a water vapor transmission rate of 5×10−5g/m2
Abstract: Thin films grown by Al2O3 atomic layer deposition (ALD) and SiN plasma-enhanced chemical vapor deposition (PECVD) have been tested as gas diffusion barriers either individually or as bilayers on polymer substrates. Single films of Al2O3 ALD with thicknesses of ≥10 nm had a water vapor transmission rate (WVTR) of ≤5×10−5 g/m2 day at 38 °C/85% relative humidity (RH), as measured by the Ca test. This WVTR value was limited by H2O permeability through the epoxy seal, as determined by the Ca test for the glass lid control. In comparison, SiN PECVD films with a thickness of 100 nm had a WVTR of ∼7×10−3 g/m2 day at 38 °C/85% RH. Significant improvements resulted when the SiN PECVD film was coated with an Al2O3 ALD film. An Al2O3 ALD film with a thickness of only 5 nm on a SiN PECVD film with a thickness of 100 nm reduced the WVTR from ∼7×10−3 to ≤5×10−5 g/m2 day at 38 °C/85% RH. The reduction in the permeability for Al2O3 ALD on the SiN PECVD films was attributed to either Al2O3 ALD sealing defects in the SiN PE...
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4,756 citations
TL;DR: Puurunen et al. as discussed by the authors summarized the two-reactant ALD processes to grow inorganic materials developed to-date, updating the information of an earlier review on ALD.
Abstract: Atomic layer deposition (ALD) is gaining attention as a thin film deposition method, uniquely suitable for depositing uniform and conformal films on complex three-dimensional topographies. The deposition of a film of a given material by ALD relies on the successive, separated, and self-terminating gas–solid reactions of typically two gaseous reactants. Hundreds of ALD chemistries have been found for depositing a variety of materials during the past decades, mostly for inorganic materials but lately also for organic and inorganic–organic hybrid compounds. One factor that often dictates the properties of ALD films in actual applications is the crystallinity of the grown film: Is the material amorphous or, if it is crystalline, which phase(s) is (are) present. In this thematic review, we first describe the basics of ALD, summarize the two-reactant ALD processes to grow inorganic materials developed to-date, updating the information of an earlier review on ALD [R. L. Puurunen, J. Appl. Phys. 97, 121301 (2005)], and give an overview of the status of processing ternary compounds by ALD. We then proceed to analyze the published experimental data for information on the crystallinity and phase of inorganic materials deposited by ALD from different reactants at different temperatures. The data are collected for films in their as-deposited state and tabulated for easy reference. Case studies are presented to illustrate the effect of different process parameters on crystallinity for representative materials: aluminium oxide, zirconium oxide, zinc oxide, titanium nitride, zinc zulfide, and ruthenium. Finally, we discuss the general trends in the development of film crystallinity as function of ALD process parameters. The authors hope that this review will help newcomers to ALD to familiarize themselves with the complex world of crystalline ALD films and, at the same time, serve for the expert as a handbook-type reference source on ALD processes and film crystallinity.
1,160 citations
TL;DR: In this paper, a review of thin-film barrier technologies for flexible organic light emitting diode (OLED) devices is provided, where the significance of the device structure, permeation rate measurement, and proposed permeation mechanism are discussed.
Abstract: Flexible organic light emitting diode (OLED) will be the ultimate display technology to customers and industries in the near future but the challenges are still being unveiled one by one. Thin-film encapsulation (TFE) technology is the most demanding requirement to prevent water and oxygen permeation into flexible OLED devices. As a polymer substrate does not offer the same barrier performance as glass, the TFE should be developed on both the bottom and top side of the device layers for sufficient lifetimes. This work provides a review of promising thin-film barrier technologies as well as the basic gas diffusion background. Topics include the significance of the device structure, permeation rate measurement, proposed permeation mechanism, and thin-film deposition technologies (Vitex system and atomic layer deposition (ALD)/molecular layer deposition (MLD)) for effective barrier films.
406 citations
TL;DR: In this article, a perspective of past and current developments in spatial ALD is discussed and the main players are identified, with a focus on photovoltaics and flexible electronics.
Abstract: Atomic layer deposition (ALD) is a technique capable of producing ultrathin conformal films with atomic level control over thickness. A major drawback of ALD is its low deposition rate, making ALD less attractive for applications that require high throughput processing. An approach to overcome this drawback is spatial ALD, i.e., an ALD mode where the half-reactions are separated spatially instead of through the use of purge steps. This allows for high deposition rate and high throughput ALD without compromising the typical ALD assets. This paper gives a perspective of past and current developments in spatial ALD. The technology is discussed and the main players are identified. Furthermore, this overview highlights current as well as new applications for spatial ALD, with a focus on photovoltaics and flexible electronics. 2012 American Vacuum Society.
327 citations
TL;DR: Al( 2)O(3) and TiO(2) atomic layer deposition (ALD) were employed to develop an ultrathin barrier film on copper to prevent water corrosion and were found to be much more resilient to dissolution in water and prevented the water corrosion of copper.
Abstract: Al2O3 and TiO2 atomic layer deposition (ALD) were employed to develop an ultrathin barrier film on copper to prevent water corrosion. The strategy was to utilize Al2O3 ALD as a pinhole-free barrier and to protect the Al2O3 ALD using TiO2 ALD. An initial set of experiments was performed at 177 °C to establish that Al2O3 ALD could nucleate on copper and produce a high-quality Al2O3 film. In situ quartz crystal microbalance (QCM) measurements verified that Al2O3 ALD nucleated and grew efficiently on copper-plated quartz crystals at 177 °C using trimethylaluminum (TMA) and water as the reactants. An electroplating technique also established that the Al2O3 ALD films had a low defect density. A second set of experiments was performed for ALD at 120 °C to study the ability of ALD films to prevent copper corrosion. These experiments revealed that an Al2O3 ALD film alone was insufficient to prevent copper corrosion because of the dissolution of the Al2O3 film in water. Subsequently, TiO2 ALD was explored on copper...
251 citations
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Book•
01 Jan 1991
TL;DR: A review of materials science can be found in this paper, where the authors describe the properties of thin-film materials and their applications in the following categories: electrical and magnetic properties, optical properties, and material properties.
Abstract: A Review of Materials Science. Vacuum Science and Technology. Physical Vapor Deposition. Chemical Vapor Deposition. Film Formation and Structure. Characterization of Thin Films. Epitaxy. Interdiffusion and Reactions in Thin Films. Mechanical Properties of Thin Films. Electrical and Magnetic Properties of Thin Films. Optical Properties of Thin Films. Metallurgical and Protective Coatings. Modification of Surfaces and Films. Emerging Thin-Film Materials and Applications. Appendixes. Index.
3,257 citations
TL;DR: In this article, the properties of low-temperature Al2O3 ALD films were investigated versus growth temperature by depositing films on Si(100) substrates and quartz crystal microbalance (QCM) sensors.
Abstract: Al2O3 films were deposited by atomic layer deposition (ALD) at temperatures as low as 33 °C in a viscous-flow reactor using alternating exposures of Al(CH3)3 (trimethylaluminum [TMA]) and H2O. Low-temperature Al2O3 ALD films have the potential to coat thermally fragile substrates such as organic, polymeric, or biological materials. The properties of low-temperature Al2O3 ALD films were investigated versus growth temperature by depositing films on Si(100) substrates and quartz crystal microbalance (QCM) sensors. Al2O3 film thicknesses, growth rates, densities, and optical properties were determined using surface profilometry, atomic force microscopy (AFM), QCM, and spectroscopic ellipsometry. Al2O3 film densities were lower at lower deposition temperatures. Al2O3 ALD film densities were 3.0 g/cm3 at 177 °C and 2.5 g/cm3 at 33 °C. AFM images showed that Al2O3 ALD films grown at low temperatures were very smooth with a root-mean-squared (RMS) roughness of only 4 ± 1 A. Current−voltage and capacitance−voltage...
1,274 citations
TL;DR: In this article, the basic concepts of atomic layer growth using molecular precursors and binary reaction sequence chemistry are reviewed and the characteristics of film deposition using ALP are explored using recent examples for Al2O3 ALP.
Abstract: Atomic layer controlled film growth is an important technological and scientific goal that is closely tied to many issues in surface chemistry. This article first reviews the basic concepts of atomic layer growth using molecular precursors and binary reaction sequence chemistry. Many examples are given for the various films that have been grown using this atomic layer growth technique. The paradigms for atomic layer epitaxy (ALE) and atomic layer processing (ALP) are then discussed in terms of self-limiting surface reactions. Recent investigations of the surface chemistry of SiO2 and Al2O3 ALP and GaAs ALE are examined and used to illustrate the possible mechanisms of atomic layer growth. Subsequently, the characteristics of film deposition using atomic layer growth techniques are explored using recent examples for Al2O3 ALP. The structure of the deposited films is also reviewed using results from previous Al2O3 deposition investigations. This article then concludes by discussing possible complications to...
836 citations
TL;DR: Al2O3 films with thicknesses ranging from 30 to 3540 A were grown in a viscous flow reactor using ALD with trimethylaluminum and water as the reactants as mentioned in this paper.
689 citations