Benefits of Atomic Layer Deposition
Conformity
Ability to coat complex 3D components or structures
ALD does not require line-of-sight like PVD
Tailorable
Films can be engineered to exhibit desired properties, enhancing the component to which the film is applied
Ultra-thin
ALD films are measured in nanometers
Low Process Temperatures
Allows the use of sensitive substrates like plastics or papers
Self-limiting
Self-limiting surface reactions result in negligible pinhole defects and a monolayer film
Example Process using Atomic Layer Deposition
First Gas, Precursor A, is Introduced
Excess Precursor A is Purged
Second Gas, Precursor B, is Introduced
Excess Precursor B is Purged
What's the Catch?
While Atomic Layer Deposition has many upsides and growing, there are a couple of caveats to be aware of.
One drawback is that the Atom to be deposited needs to be package in a precursor. This makes proper precursor selection essential.
Another drawback and possibly the most important is the speed at which layers can be built up. A deposition speed of < 1 Angstrom / second is typical. For comparison, your hair grows at an average rate of 46 angstroms / second.
Applications
Microelectronics
Biomedical
Aerogels
Energy Storage
Nanostructures
Corrosion Resistant Coatings
Wear Resistant Coatings
Solar Cell Technologies
Chemical Sensors
Recyclable Packaging
The practical applications for atomic layer deposition technology are almost limitless. Here at UPT we are always pushing the boundaries of technology and have developed a new proprietary coating using a hybrid coating technology, which involves ALD.
Adsorption
Let's get into the weeds, so to speak. Adsorption is the mechanism used in Atomic Layer Deposition and is the interaction between an adsorbing molecule, the precursor, and a solid surface, the substrate. There are two types of adsorption, Physisorption and Chemisorption. An understanding of adsorption mechanisms is critical when developing thin films using Atomic Layer Deposition. While either may be used, Chemisorption is preferred, and you'll see why below.
Physisorption
Weak interactions, Van der Waals forces
Reversible
Interactions are NOT specific, resulting in multilayer formation.
Only occurs at low temperatures
Chemisorption
Chemical bond formed
Strong Interactions
Irreversible
Interactions are specific, which makes them self-limiting, resulting in monolayer formation.
Can occur at all temperatures
Typical Materials deposited with ALD
Customization of the individual layers can result in some fantastic properties, unachievable through traditional production technologies.
Oxides
Nitrides
Flourides
Sulfides
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