vacuumdeposition

Vacuum deposition refers to coating processes that deposit material from a vapor phase onto a substrate under vacuum or very low pressure. The term broadly encompasses physical vapor deposition (PVD) and chemical vapor deposition (CVD) carried out in a vacuum, as well as related vapor-phase techniques such as atomic layer deposition. Operating in vacuum limits gas-phase collisions and reduces contamination, enabling high-purity films, good step coverage, and precise control of thickness at the nanometer scale.

Physical vapor deposition methods extract material from a solid or liquid source and transport it as a vapor to condense on a cooler substrate. Common PVD techniques include evaporation (thermal or electron-beam), sputtering (including magnetron sputtering), and pulsed laser deposition. These processes typically produce directional, dense films with controllable stoichiometry.

Chemical vapor deposition in vacuum uses volatile precursors that react on the substrate surface to form a solid film. CVD processes in low pressure or ultra-high vacuum can achieve uniform, conformal coatings on complex shapes. Variants include low-pressure CVD, plasma-enhanced CVD, and atomic layer deposition, which is a sequential, self-limiting form of vapor deposition offering excellent thickness control.

Equipment and conditions: A vacuum chamber, pump system, substrate heater or cooling, and a source of vapor—such as a heated crucible, sputtering target, or gas-delivery system. Film properties depend on substrate temperature, deposition rate, chamber pressure, and gas chemistry. Vacuum quality helps minimize impurities and enables high-purity films.

Applications: Vacuum deposition is used for protective coatings on tools and optical components, reflective and anti-reflective coatings on lenses, semiconductor devices and interconnects, thin-film photovoltaics, and microelectromechanical systems. It is chosen for its ability to produce uniform coatings with controlled thickness and good adhesion.