Atomic Layer Deposition
Atomic layer deposition, ALD, is a thin film technology that enables new and highly competitive products. ALD is also a powerful resource for advanced nanotechnology research. Typical applications of ALD contain a requirement to manufacture very precise nanometer–thick, pinhole–free and totally conformal thin films on any shape and geometry. For today’s businesses, Beneq ALD offers the necessary tools to accelerate growth, by means of new and innovative applications, production equipment you can count on and affordable cost of ownership.
ALD, a chemical vapor deposition (CVD) method, was initially developed for manufacturing nanolaminate insulators (Al2O3/TiO2) and zinc sulfide (ZnS) phosphor films for thin film electroluminescent (TFEL) displays. Large–scale production of these displays started in the mid–1980’s, mainly thanks to ALD. The unique properties of the coatings, together with the high repeatability, were the main factors leading to successful industrial production.
ALD is an enabling technology for new and improved products. It provides coatings and material features which either cannot be achieved cost–efficiently with existing techniques, or they cannot be achieved at all. ALD, as a thin film coating method, offers:
- Precise control of the film thickness, at true nanometer scale
- Pinhole–free films for, e.g., superior barriers and surface passivation
- Conformal coating of batches, large–area substrates and complex 3D objects, including porous bulk materials, as well as powders
- Engineered and new functional materials and structures, such as nanolaminates
- A highly repeatable and scalable process.
ALD coating process
ALD is based on surface controlled thin film deposition. During coating, two or more chemical vapors or gaseous precursors react sequentially on the substrate surface, producing a solid thin film (see schematic below). Most ALD coating systems utilize a flow–through traveling wave setup, where an inert carrier gas flows through the system and precursors are injected as very short pulses into this carrier flow. The carrier gas flow takes the precursor pulses as sequential “waves” through the reaction chamber, followed by a pumping line, filtering systems and, eventually, a vacuum pump.
Typical process conditions:
- Pressure range: 0.1–10 mbar (Torr, hPa) or atmospheric
- Temperature: typically, 50 - 500 °C
Process and coating properties
Excellent adhesion: Chemisorption of precursors with the surface provides excellent adhesion.
Saturation: Self–terminating surface reactions enable automatic processing and eliminate the need for over–precise dosing and continuous operator attendance.
Sequential: Digital–like sequential growth provides for excellent accuracy without the need for extensive in situ feedback or operator attendance.
Surface–controlled reactions: Surface reactions enable unconditionally conformal coatings, regardless of if the substrate is dense, porous, tubular, a powder or otherwise complex in shape.
Precise and repeatable: Film growth thickness during a single ALD cycle is process specific, but typically about 1 Å (0.1 nm).
Thin, dense, and smooth: ALD enables depositing layers less than one nanometer in thickness. Coatings as thin as 0.8 nm are currently used in certain industrial applications.
High capacity: The surface–controlled growth feature allows for capacity expansion for both large batches and large surfaces.
Plasma enhanced ALD: ALD coating can also be modified by applying plasma to the deposition cycle, e.g., to enable coating with certain metals and low–temperature oxides and nitrides.
Roll–to–Roll and Continuous ALD: Roll–to–Roll coating opens the door for many new ALD applications in, for example, the flexible electronics industry. Beneq, with the world’s first commercially available research platform for continuous ALD, is at the forefront of this development work.
ALD on particles and powders: Combining conformal coating with particulate substrates creates completely new opportunities to, for example, modify the diffusion properties of battery materials and much more.
The most common materials deposited by ALD include (selection):
Oxides: Al2O3, CaO, CuO, Er2O3, Ga2O3, HfO2, La2O3, MgO, Nb2O5, Sc2O3, SiO2, Ta2O5, TiO2, VXOY, Y2O3, Yb2O3, ZnO, ZrO2, etc.
Nitrides: AlN, GaN, TaNX, TiAlN, TiNX, etc.
Carbides: TaC, TiC, etc.
Metals: Ir, Pd, Pt, Ru, etc.
Sulfides: ZnS, SrS, etc.
Fluorides: CaF2, LaF3, MgF2, SrF2, etc.
Biomaterials: Ca10(PO4)6(OH)2 (hydroxyapatite)
Polymers: PMDA–DAH, PMDA–ODA, etc.
Doping, nanolaminates and mixed structures: ALD enables avast array of material combinations.
There are many more materials and processes available in ALD today. Beneq ALD specialists are at your service, if you have any inquiries. See ALD Coating Services for more information.
Encapsulation of OLED microdisplaysBeneq developed a thin-film encapsulation nanolaminate coating for a leading Asian OLED microdisplay manufacturer to enable long lifetime for their microdisplays.
Insulator for thin film electroluminescent displaysAn ALD nanolaminate film was developed for Lumineq displays to create a fully pin-hole free thin film insulator layer.
Top electrode for transparent displayBeneq developed an ALD Transparent Conductive Oxide (TCO) for Lumineq's electroluminescent displays to replace the sputtered IDO that was used in the transparent top electrode.
Moisture protection of PCBsBeneq developed a low-temperature ALD moisture barrier solution for a leading supplier of electronics for personal safety monitoring to protect the sensitive circuit board components from moisture.
Encapsulation of phosphor powderBeneq provided a moisture barrier solution using ALD for FBR (fluidized-bed reactor) for a leading phosphor material manufacturer to protect the sensitive phosphor powders used in LED lighting from moisture.
Anti-corrosion coating for LED packagingBeneq's ALD coating solution solved a leading LED manufacturer's silver reflector corrosion problem by both applying ALD to coat the semi-finished wire-bonded LED assemblies, and by protecting the silver surface with nSilver.
Anti-reflection coating for solar glassBeneq and DSM created a production scale solution using DSM AR coating material and Beneq nFOG aerosol technology for a leading solar glass manufacturer to reduce light reflection on solar panels.
Metal-like coatings for watch partsBeneq developed a thin ALD-based optical coating for a leading watch parts manufacturer to both provide a specific color and to protect from corrosion.
Wafer-level moisture barrier for LEDBeneq provided moisture coating using TFS 200 for a leading LED manufacturer to protect LED dies from moisture and prevent oxidation.
Bottom DBR for LEDBeneq developed a multi-layer DBR structure on a patterned surface for a leading LED manufacturer.
Filling of diffractive gratingsBeneq used ALD coating to fill diffractive gratings for a leading optical system manufacturer to keep the gratings free from debris and boost their optical performance.
Anti-corrosion coating for sensorsThe highly conformal and pin-hole free ALD coating solved a leading sensor manufacturer's sensor corrosion problems without compromising sensor sensitivity.
Buffer layer for CIGS solar panelBeneq developed a thin, cadmium-free ALD buffer for the solar panels of a leading CGIS solar panel manufacturer.
Diffusion barrier for Li-ion batteriesBeneq's ultra-thin ALD coating solved a leading Li-ion battery manufacturer's battery corrosion challenges by reducing the fading of battery capacity caused by repeated charge and unload cycles.
Anti-tarnishing coating for jewelryBeneq helped Kalevala Jewelry in preventing the discoloration of silver surfaces by providing the patented nSilver industrial-scale protection solution for an ultra-thin, totally conformal, and fully transparent anti-tarnish coating.
Optical NIR filter on a glass cylinderBeneq developed a customized batch ALD process for a CCD sensor -based industrial vision systems supplier to coat their near-infrared (NIR) filters.
Optical coatings for lenses in high power lasersBenq developed a conformal high- and low-index multilayer optical coating for a leading provider of high power laser optics and coatings using the TFS 500 batch ALD system.
Coating of Microchannel Plates (MCP)Beneq developed an ALD coating solution for microchannel plates (MCP) for Incom, Inc., the world’s largest supplier of rigid fused fiber optics, to allow for significantly greater secondary electron emission .
Thin-film encapsulation of OLED lightingBeneq developed a conformal, dense, and pinhole-free Al2O3 and TiO2 barrier coating for a leading OLED lighting panel manufacturer to protect OLED panels from humidity.
Thin-film encapsulation of scintillator plates for X-ray imagingBeneq developed a conformal, dense, and pinhole-free low temperature Al2O3 and TiO2 barrier coating for a leading scintillator plate manufacturer to protect scintillator materials from moisture and increase product lifetime and reliability.