Atomic Layer Deposition (ALD) is a thin-film deposition technique that uses a sequential gas phase chemical process. ALD is a subclass of Chemical Vapour Deposition (CVD). With ALD, thin film is slowly deposited with the repeated exposure to separate precursors. Most ALD reactions use two chemicals called precursors. These precursors react with the surface of a material one at a time in a sequential, self-limiting, manner. The precursors are pulsed and purged onto the substrate (material) one at a time. One precursor is introduced, then purged, and the second precursor is introduced. This process builds an atomic level coating, one layer at a time. This process can be repeated as many times as necessary, in order to achieve the desired thickness, or specific surface properties.
ST Instruments offers a range of R&D scale and commercial systems from Forge Nano to perform ALD on powders & particles, objects & high surface area substrates, wafers and semiconductors.
Atomic Layer Deposition consists of sequential pulses of gaseous precursors, chemicals that will bond to the substrate. Precursor pulses are separated by a purge phase. The precursors only bind to reactive sites on the substrate, and thus, the process is self-limiting. This first step is usually a ‘half reaction’, which after a purge is followed by a second precursor, resulting in the required pure monolayer. The technique is mainly limited by the chemical reactions of the precursors. However, the list of materials that can be deposited with atomic layer deposition is vast, including fluorides, oxides, metals and sulphides. The wide application range of atomic layer deposition explains why it has become a popular tool to develop nano-coatings and thin films.
In contrast to other techniques for thin film deposition, e.g. spin coating, this method works well on surfaces that are not flat. It results in a conformal nano-coating, suitable for different nanomaterials as well as larger objects. Furthermore, it is possible to create multilayers using this technique.
ALD can also be used to coat nanoparticles. Various particles can be coated using this Particle ALD (or PALD), ranging from simple iron particles to complex hexagonal Boron Nitride nanoparticles. Finally, the technology is scalable, and can be applied as a continuous and semi-continuous high-throughput process.
Coating of rechargeable batteries
When batteries are stored and when they are used, unwanted reactions occur leading to degradation of performance. Many of these reactions, such as transition metal dissolution, lithium inventory loss, and solid electrolyte interphase growth, can be slowed or passivated by surface coatings applied by ALD. ALD can be applied to a wide variety of cathode and anode powders to produce benefits including longer cycle life, lower gas generation, slower impedance growth, higher voltage utilization and enhanced safety (through higher thermal runaway onset temperature). High throughput ALD systems can process 3,000 kg – 30,000 kg of powder per day for under $1/kg total coating.
Further reading: see the white paper on Batteries: https://www.forgenano.com/resources/whitepapers/
Medical device require biocompatible coatings to protect them during contact with body tissue and corrosive body fluids. Electrical surgical devices can benefit from an insulating coating that can withstand high temperatures and higher energy delivery. Forge Nano provides ALD-Cap®, a ceramic coating that is inherently inert and stable to temperatures as high 1000°C and has been tested to have excellent biocompatibility. The exceptional barrier properties of ALD-Cap® are ideally suitable for the most demanding medical applications. ALD-Cap® ceramic coatings are flexible and can be deposited on flexible plastic substrates at low temperatures.
Further reading: see the white paper on Medical Devices: https://www.forgenano.com/resources/whitepapers/
Polymers are used in all kinds of packaging, including food and beverages. However, high gas permeability can limit their use in these applications. One solution is us Particle ALD (PALD) to coat polymer particles in an inorganic gas diffusion barrier – such as an ultrathin alumina layer – to dramatically improve polymer performance.
Further reading: see the white paper on Surface Modification with ALD: https://www.forgenano.com/resources/whitepapers/