Vacuum deposition

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Vacuum deposition is a process used to create a thin layer of a substance (a coating) on a solid object (the substrate). The substrate is placed into a vacuum chamber and a small amount of the coating material is vaporized into the chamber. The molecules or atoms of vapor condense onto the substrate, forming (ideally) a uniform coating of controllable thickness. Many such layers can be built up, for example (in optics) to form an interference filter or other multilayer optic, or (in microelectronics) to form different layers within a complex microchip.

Vacuum deposition is very commonly used in the fabrication of optics. Everyday objects that are created by vacuum deposition include mirrors, which are most frequently made of a glass substrate with aluminum or silver vacuum-deposited onto it; sunglasses, which often use vacuum-deposited coatings to attenuate light; and electronic microchips, which are fabricated using a combination of vacuum deposition and photolithography.

Common vacuum deposition techniques include sputter deposition and ion implantation, in which ions of the coating material are accelerated directly to land on (and possibly implant within) the surface of the substrate.