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Title: Roll-to-roll atomic layer deposition process for flexible electronics encapsulation applications

Abstract

At present flexible electronic devices are under extensive development and, among them, flexible organic light-emitting diode displays are the closest to a large market deployment. One of the remaining unsolved challenges is high throughput production of impermeable flexible transparent barrier layers that protect sensitive light-emitting materials against ambient moisture. The present studies deal with the adaptation of the atomic layer deposition (ALD) process to high-throughput roll-to-roll production using the spatial ALD concept. We report the development of such a process for the deposition of 20 nm thickness Al{sub 2}O{sub 3} diffusion barrier layers on 500 mm wide polymer webs. The process uses trimethylaluminum and water as precursors at a substrate temperature of 105 °C. The observation of self-limiting film growth behavior and uniformity of thickness confirms the ALD growth mechanism. Water vapor transmission rates for 20 nm Al{sub 2}O{sub 3} films deposited on polyethylene naphthalate (PEN) substrates were measured as a function of substrate residence time, that is, time of exposure of the substrate to one precursor zone. Moisture permeation levels measured at 38 °C/90% relative humidity by coulometric isostatic–isobaric method were below the detection limit of the instrument (<5 × 10{sup −4} g/m{sup 2} day) for films coated at web moving speed of 0.25 m/min. Measurements using themore » Ca test indicated water vapor transmission rates ∼5 × 10{sup −6} g/m{sup 2} day. Optical measurements on the coated web showed minimum transmission of 80% in the visible range that is the same as the original PEN substrate.« less

Authors:
; ; ;  [1]; ;  [2]; ;  [3]; ;  [4]
  1. Advanced Surface Technology Research Laboratory, Lappeenranta University of Technology, Sammonkatu 12, 50130 Mikkeli (Finland)
  2. Beneq Oy, P.O. Box 262, 01511 Vantaa (Finland)
  3. Tampere University of Technology, Paper Converting and Packaging Technology, P.O. Box 589, 33101 Tampere (Finland)
  4. Samsung Cheil Industries, San Jose R and D Center, 2186 Bering Drive, San Jose, California 95131 (United States)
Publication Date:
OSTI Identifier:
22317970
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films; Journal Volume: 32; Journal Issue: 5; Other Information: (c) 2014 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM OXIDES; DEPLETION LAYER; DEPOSITION; ELECTRONIC EQUIPMENT; ENCAPSULATION; LIGHT EMITTING DIODES; POLYETHYLENES

Citation Formats

Maydannik, Philipp S., E-mail: philipp.maydannik@lut.fi, Kääriäinen, Tommi O., Lahtinen, Kimmo, Cameron, David C., Söderlund, Mikko, Soininen, Pekka, Johansson, Petri, Kuusipalo, Jurkka, Moro, Lorenza, and Zeng, Xianghui. Roll-to-roll atomic layer deposition process for flexible electronics encapsulation applications. United States: N. p., 2014. Web. doi:10.1116/1.4893428.
Maydannik, Philipp S., E-mail: philipp.maydannik@lut.fi, Kääriäinen, Tommi O., Lahtinen, Kimmo, Cameron, David C., Söderlund, Mikko, Soininen, Pekka, Johansson, Petri, Kuusipalo, Jurkka, Moro, Lorenza, & Zeng, Xianghui. Roll-to-roll atomic layer deposition process for flexible electronics encapsulation applications. United States. doi:10.1116/1.4893428.
Maydannik, Philipp S., E-mail: philipp.maydannik@lut.fi, Kääriäinen, Tommi O., Lahtinen, Kimmo, Cameron, David C., Söderlund, Mikko, Soininen, Pekka, Johansson, Petri, Kuusipalo, Jurkka, Moro, Lorenza, and Zeng, Xianghui. Mon . "Roll-to-roll atomic layer deposition process for flexible electronics encapsulation applications". United States. doi:10.1116/1.4893428.
@article{osti_22317970,
title = {Roll-to-roll atomic layer deposition process for flexible electronics encapsulation applications},
author = {Maydannik, Philipp S., E-mail: philipp.maydannik@lut.fi and Kääriäinen, Tommi O. and Lahtinen, Kimmo and Cameron, David C. and Söderlund, Mikko and Soininen, Pekka and Johansson, Petri and Kuusipalo, Jurkka and Moro, Lorenza and Zeng, Xianghui},
abstractNote = {At present flexible electronic devices are under extensive development and, among them, flexible organic light-emitting diode displays are the closest to a large market deployment. One of the remaining unsolved challenges is high throughput production of impermeable flexible transparent barrier layers that protect sensitive light-emitting materials against ambient moisture. The present studies deal with the adaptation of the atomic layer deposition (ALD) process to high-throughput roll-to-roll production using the spatial ALD concept. We report the development of such a process for the deposition of 20 nm thickness Al{sub 2}O{sub 3} diffusion barrier layers on 500 mm wide polymer webs. The process uses trimethylaluminum and water as precursors at a substrate temperature of 105 °C. The observation of self-limiting film growth behavior and uniformity of thickness confirms the ALD growth mechanism. Water vapor transmission rates for 20 nm Al{sub 2}O{sub 3} films deposited on polyethylene naphthalate (PEN) substrates were measured as a function of substrate residence time, that is, time of exposure of the substrate to one precursor zone. Moisture permeation levels measured at 38 °C/90% relative humidity by coulometric isostatic–isobaric method were below the detection limit of the instrument (<5 × 10{sup −4} g/m{sup 2} day) for films coated at web moving speed of 0.25 m/min. Measurements using the Ca test indicated water vapor transmission rates ∼5 × 10{sup −6} g/m{sup 2} day. Optical measurements on the coated web showed minimum transmission of 80% in the visible range that is the same as the original PEN substrate.},
doi = {10.1116/1.4893428},
journal = {Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films},
number = 5,
volume = 32,
place = {United States},
year = {Mon Sep 01 00:00:00 EDT 2014},
month = {Mon Sep 01 00:00:00 EDT 2014}
}
  • Water and oxygen were compared as oxidizing agents for the Al{sub 2}O{sub 3} atomic layer deposition process using spatial atomic layer deposition reactor. The influence of the precursor dose on the deposition rate and refractive index, which was used as a proxy for film density, was measured as a function of residence time, defined as the time which the moving substrate spent within one precursor gas zone. The effect of temperature on the growth characteristics was also measured. The water-based process gave faster deposition rates and higher refractive indices but the ozone process allowed deposition to take place at lowermore » temperatures while still maintaining good film quality. In general, processes based on both oxidation chemistries were able to produce excellent moisture barrier films with water vapor transmission rate levels of 10{sup −4} g/m{sup 2} day measured at 38 °C and 90% of relative humidity on polyethylene naphthalate substrates. However, the best result of <5 × 10{sup −5} was obtained at 100 °C process temperature with water as precursor.« less
  • Direct deposition of barrier films by atomic layer deposition (ALD) onto printed electronics presents a promising method for packaging devices. Films made by ALD have been shown to possess desired ultrabarrier properties, but face challenges when directly grown onto surfaces with varying composition and topography. Challenges include differing nucleation and growth rates across the surface, stress concentrations from topography and coefficient of thermal expansion mismatch, elastic constant mismatch, and particle contamination that may impact the performance of the ALD barrier. In such cases, a polymer smoothing layer may be needed to coat the surface prior to ALD barrier film deposition.more » We present the impact of architecture on the performance of aluminum oxide (Al{sub 2}O{sub 3})/hafnium oxide (HfO{sub 2}) ALD nanolaminate barrier films deposited on fluorinated polymer layer using an optical calcium (Ca) test under damp heat. It is found that with increasing polymer thickness, the barrier films with residual tensile stress are prone to cracking resulting in rapid failure of the Ca sensor at 50 °C/85% relative humidity. Inserting a SiN{sub x} layer with residual compressive stress between the polymer and ALD layers is found to prevent cracking over a range of polymer thicknesses with more than 95% of the Ca sensor remaining after 500 h of testing. These results suggest that controlling mechanical properties and film architecture play an important role in the performance of direct deposited ALD barriers.« less
  • Cited by 9
  • Direct deposition of barrier films by atomic layer deposition (ALD) onto printed electronics presents a promising method for packaging devices. Films made by ALD have been shown to possess desired ultrabarrier properties, but face challenges when directly grown onto surfaces with varying composition and topography. Challenges include differing nucleation and growth rates across the surface, stress concentrations from topography and coefficient of thermal expansion (CTE) mismatch, elastic mismatch, and particle contamination that may impact the performance of the ALD barrier. In such cases, a polymer smoothing layer may be needed to coat the surface prior to ALD barrier film deposition.more » We present the impact of architecture on the performance of aluminum oxide (Al2O3)/hafnium oxide (HfO2) ALD nanolaminate barrier films deposited on fluorinated polymer layer using an optical calcium (Ca) test under damp heat. It is found that with increasing polymer thickness, the barrier films with residual tensile stress are prone to cracking resulting in rapid failure of the Ca sensor at 50{degree sign}C/85% RH. Inserting a SiNx layer with residual compressive stress between the polymer and ALD layers is found to prevent cracking over a range of polymer thicknesses with more than 95% of the Ca sensor remaining after 500 h of testing. These results suggest that controlling mechanical properties and film architecture play an important role in the performance of direct deposited ALD barriers.« less
  • Since epitaxial silicene is not chemically inert under ambient conditions, its application in devices and the ex-situ characterization outside of ultrahigh vacuum environments require the use of an insulating capping layer. Here, we report on a study of the feasibility of encapsulating epitaxial silicene on ZrB{sub 2}(0001) thin films grown on Si(111) substrates by aluminum nitride (AlN) deposited using trimethylaluminum (TMA) and ammonia (NH{sub 3}) precursors. By in-situ high-resolution core-level photoelectron spectroscopy, the chemical modifications of the surface due to subsequent exposure to TMA and NH{sub 3} molecules, at temperatures of 300 °C and 400 °C, respectively, have been investigated. While anmore » AlN-related layer can indeed be grown, silicene reacts strongly with both precursor molecules resulting in the formation of Si–C and Si–N bonds such that the use of these precursors does not allow for the protective AlN encapsulation that leaves the electronic properties of silicene intact.« less