Comparison of the cohesive and delamination fatigue properties of atomic-layer-deposited alumina and titania ultrathin protective coatings deposited at 200 °C

Sadeghi-Tohidi, Farzad; Samet, David; Graham, Samuel; Pierron, Olivier N.

doi:10.1088/1468-6996/15/1/015003

Cited by 7 publications

(8 citation statements)

References 30 publications

(62 reference statements)

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“…Al 2 O 3 deposited by atomic layer deposition (ALD) as a protective coating has attracted considerable interest in the past years. − ALD coatings in general are highly attractive due to the conformal nature of the deposited films. In principle, any geometry can be coated uniformly as long as the gaseous precursors are able to diffuse to the desired locations.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, even geometries, such as pinholes and partly sealed cavities, can be protected. Protective ALD coatings can be applied in various areas such as (medical) microdevices ,, and organic electronics . Besides utilizing ALD alumina films as protective coatings, they may also be used as functional and structural layers in microsystem manufacturing.…”

Section: Introductionmentioning

confidence: 99%

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Chemically Stable Atomic-Layer-Deposited Al₂O₃ Films for Processability

et al. 2017

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Atomic-layer-deposited alumina (ALD Al 2 O 3 ) can be utilized for passivation, structural, and functional purposes in electronics. In all cases, the deposited film is usually expected to maintain chemical stability over the lifetime of the device or during processing. However, as-deposited ALD Al 2 O 3 is typically amorphous with poor resistance to chemical attack by aggressive solutions employed in electronics manufacturing. Therefore, such films may not be suitable for further processing as solvent treatments could weaken the protective barrier properties of the film or dissolved material could contaminate the solvent baths, which can cause cross-contamination of a production line used to manufacture different products. On the contrary, heat-treated, crystalline ALD Al 2 O 3 has shown resistance to deterioration in solutions, such as standard clean (SC) 1 and 2. In this study, ALD Al 2 O 3 was deposited from four different precursor combinations and subsequently annealed either at 600, 800, or 1000 °C for 1 h. Crystalline Al 2 O 3 was achieved after the 800 and 1000 °C heat treatments. The crystalline films showed apparent stability in SC-1 and HF solutions. However, ellipsometry and electron microscopy showed that a prolonged exposure (60 min) to SC-1 and HF had induced a decrease in the refractive index and nanocracks in the films annealed at 800 °C. The degradation mechanism of the unstable crystalline film and the microstructure of the film, fully stable in SC-1 and with minor reaction with HF, were studied with transmission electron microscopy. Although both crystallized films had the same alumina transition phase, the film annealed at 800 °C in N 2 , with a less developed microstructure such as embedded amorphous regions and an uneven interfacial reaction layer, deteriorates at the amorphous regions and at the substrate–film interface. On the contrary, the stable film annealed at 1000 °C in N 2 had considerably less embedded amorphous regions and a uniform Al–O–Si interfacial layer.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chemically Stable Atomic-Layer-Deposited Al₂O₃ Films for Processability

et al. 2017

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“…A variety of CVD SiO 2 and SiN x films were recently investigated for applications in transient electronics, where an inverse correlation of stability and density was observed. 8 ALD alumina and titania films were recently examined in context of their stability in neutral water.…”

Section: Introductionmentioning

confidence: 99%

“…Atomic layer deposited (ALD) oxide films are being explored for protective coatings for electronic, optical, biological, and mechanical applications. − These applications are motivated by the conformal deposition and precise thickness control afforded by the self-limiting surface reactions that result in ALD growth. Many of these applications expose films to potentially reactive liquid ambients, highlighting the importance of chemical stability.…”

Section: Introductionmentioning

confidence: 99%

Chemical Stability of Titania and Alumina Thin Films Formed by Atomic Layer Deposition

Correa

Bao

Strandwitz

2015

ACS Appl. Mater. Interfaces

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Thin films formed by atomic layer deposition (ALD) are being examined for a variety of chemical protection and diffusion barrier applications, yet their stability in various fluid environments is not well characterized. The chemical stability of titania and alumina thin films in air, 18 MΩ water, 1 M KCl, 1 M HNO3, 1 M H2SO4, 1 M HCl, 1 M KOH, and mercury was studied. Films were deposited at 150 °C using trimethylaluminum-H2O and tetrakis(dimethylamido)titanium-H2O chemistries for alumina and titania, respectively. A subset of samples were heated to 450 and 900 °C in inert atmosphere. Films were examined using spectroscopic ellipsometry, atomic force microscopy, optical microscopy, scanning electron microscopy, and X-ray diffraction. Notably, alumina samples were found to be unstable in pure water, acid, and basic environments in the as-synthesized state and after 450 °C thermal treatment. In pure water, a dissolution-precipitation mechanism is hypothesized to cause surface roughening. The stability of alumina films was greatly enhanced after annealing at 900 °C in acidic and basic solutions. Titania films were found to be stable in acid after annealing at or above 450 °C. All films showed a composition-independent increase in measured thickness when immersed in mercury. These results provide stability-processing relationships that are important for controlled etching and protective barrier layers.

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“…Currently, the technology for ultrabarrier films has reached an effective water vapor transmission rate less than 10 −4 g·m −2 day −1 1 – 7 . With recent demonstrations of curved and now foldable organic displays, solar cells and light emitting diodes with radii of curvature down to 30 μm 8 , the understanding of their reliability under mechanical deformation has become paramount to their adoption as a viable technology 9 – 16 . This is critically important for ultrabarrier films that are made with brittle inorganic thin films and have limited tolerance to strain.…”

Section: Introductionmentioning

confidence: 99%

Influence of Polymer Substrate Damage on the Time Dependent Cracking of SiNx Barrier Films

Kim

Luo

Zhu

et al. 2018

Sci Rep

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This work is concerned with the long-term behavior of environmentally-assisted subcritical cracking of PECVD SiNx barrier films on polyethylene terephthalate (PET) and polyimide (PI) substrates. While environmentally-assisted channel cracking in SiNx has been previously demonstrated, with constant crack growth rates over short periods of time (<1 hour) during which no substrate damage was observed, the present experiments over longer periods reveal a regime where cracking also develops in the polymer substrate. This time-dependent local cracking of the polymer underneath the channel crack is expected based on creep rupture or static fatigue. Our combined in-situ microscopy and finite-element modeling results highlight the combined effects of neighboring cracks and substrate cracking on the crack growth rate evolution in the film. In most cases, the subcritical crack growth rates decrease over time by up to two orders of magnitude until steady-state rates are reached. For SiNx on PI, crack growth rates were found to be more stable over time due to the lack of crack growth in the substrate as compared to SiNx on PET. These results provide a guideline to effectively improving the long-term reliability of flexible barriers by a substrate possessing high strength which limits substrate damage.

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Comparison of the cohesive and delamination fatigue properties of atomic-layer-deposited alumina and titania ultrathin protective coatings deposited at 200 °C

Cited by 7 publications

References 30 publications

Chemically Stable Atomic-Layer-Deposited Al₂O₃ Films for Processability

Chemically Stable Atomic-Layer-Deposited Al₂O₃ Films for Processability

Chemical Stability of Titania and Alumina Thin Films Formed by Atomic Layer Deposition

Influence of Polymer Substrate Damage on the Time Dependent Cracking of SiNx Barrier Films

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Comparison of the cohesive and delamination fatigue properties of atomic-layer-deposited alumina and titania ultrathin protective coatings deposited at 200 °C

Cited by 7 publications

References 30 publications

Chemically Stable Atomic-Layer-Deposited Al2O3 Films for Processability

Chemically Stable Atomic-Layer-Deposited Al2O3 Films for Processability

Chemical Stability of Titania and Alumina Thin Films Formed by Atomic Layer Deposition

Influence of Polymer Substrate Damage on the Time Dependent Cracking of SiNx Barrier Films

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Chemically Stable Atomic-Layer-Deposited Al₂O₃ Films for Processability

Chemically Stable Atomic-Layer-Deposited Al₂O₃ Films for Processability