In chemical vapor deposition process, solid materials such as particles, thin films or nanowires are deposited on a substrate by producing reactive species in the gaseous phase. These reactive species are produced when precursor gases travel over the heated substrate. Different types of CVD processes are employed in present applications and they include low pressure chemical vapor deposition (LPCVD), atmospheric pressure chemical vapor deposition (APCVD), and metal-organic chemical vapor deposition (MOCVD). In the MOCVD process, metal-organic species are utilized as precursors for making thin films of metals, metallic compounds, metal nitrides, metal oxides, etc.
Typical CVD Reactor
Atomic layer deposition (ALD) is a special type of CVD process which makes it possible to control the atomic scale deposition, and as a result helps in creating smooth alternating layers of varied materials that are extremely thick, uniform and have minimum defects. To this end, both ALD and CVD processes offer practical options since they promote the growth of thin films that are uniform and have precise thickness control.
Some of the standard applications of CVD include the formation of protective coatings, such as coatings that are resistant to wear, corrosion, and extreme temperatures, as well as the development of thick structural parts, ceramic composites, optical fibers, and innovative powdered and fibrous materials. CVD is suitable for manufacturing optical storage media and is typically utilized for producing semiconductor devices.
General MOCVD mechanism
On the other hand, ALD provides better control during the formation of films and hence is increasingly being used for depositing thin films in a number of applications like ferroelectric memories, integrated circuits, microelectromechanical structures, switches, thin-film capacitors, radiation detectors, etc. ALD is also essential for improving electroluminescent device technology.