What is ALD?
Atomic Layer Deposition (ALD) is an advanced thin film coating method which is used to fabricate ultrathin, highly uniform and conformal material layers for several applications. ALD uses sequential, self-limiting and surface controlled gas phase chemical reactions to achieve control of film growth in the nanometer/sub-nanometer thickness regime. Due to the film formation mechanism - the gases won't react until in touch with the surface which means the film growth proceeds by consecutive atomic layers "up" from the surface - the ALD film is dense, crack-, defect- and pinhole-free and its thickness and structural and chemical characteristics can be precisely controlled on atomic scale. ALD process is digitally repeatable and it can be performed at relatively low temperatures. This gives the possibility to construct not only single material layers but also doped, mixed, or graded layers and nanolaminates, whereas low process temperature allows coating of also sensitive materials such as plastics and polymers. The list of ALD materials is wide, ranging from e.g. oxides, nitrides, fluorides, carbides, and sulfides to ternary compounds, metals (including noble ones), hybrid materials and polymers.
The number of ALD applications has grown exponentially over the past few years. Nowadays, in conjunction with the Moore's law and constantly decreasing IC (integrated circuit) device size, ALD is the only method with which the functional material layers thin enough but still of the highest quality, uniformity, conformality, and structural integrity, can be manufactured on the nanometer-scale features and high aspect ratio structures common in today's memory, logic, and hard drive components. In short, ALD enables our modern mobile communication devices and more and more compact and efficient computers.
In addition to IC component manufacturing, other large scale industrial applications for ALD can be found in sensor, LED and other III-V device, and MEMS (microelectromechanical systems) manufacturing. ALD films are also used in optics and optoelectronics, antitarnishing and wear protection, and renewable energy applications such as solar power, and the method offers novel solutions for corrosion protection, energy storage and production (e.g. advanced thin film batteries and fuel cells), biocompatibe and bioactive surface functionalization of medical devices and implants, ecological packaging materials, moisture- and gas-tight encapsulant layers, decorative coatings, hydrophobic coatings, and anti-cracking layers for glass.