Physical Vapor Deposition (PVD) is a family of processes that is used to deposit layers of atoms or molecules from the vapor phase onto a solid substrate in a vacuum chamber. Two very common types of processes used are Sputtering and Electron Beam Evaporation.
Sputtering process involves ejecting material from a “target” that is a source onto a “substrate” (such as a silicon wafer) in a vacuum chamber. This effect is caused by the bombardment of the target by ionized gas which often is an inert gas such as argon. Sputtering is used extensively in the semiconductor industry to deposit thin films of various materials in integrated circuit processing. Anti-reflection coatings on glass for optical applications are also deposited by sputtering. Because of the low substrate temperatures used, sputtering is an ideal method to deposit metals for thin-film transistors. Perhaps the most familiar products of sputtering are low-emissivity coatings on glass, used in double-pane window assemblies. An important advantage of sputtering is that even materials with very high melting points are easily sputtered while evaporation of these materials in a resistance evaporator or Knudsen cell is difficult and problematic.
Electron Beam Evaporation (commonly referred to as E-beam Evaporation) is the process used at Abrisa Technologies, the ZC&R Coatings for Optics division. This is a process in which a target material is bombarded with an electron beam given off by a tungsten filament under high vacuum. The electron beam causes atoms from the source material to evaporate into the gaseous phase. These atoms then precipitate into solid form, coating everything in the vacuum chamber (within line of sight) with a thin layer of the anode material. A clear advantage of this process is it permits direct transfer of energy to source during heating and very efficient in depositing pure evaporated material to substrate. Also, deposition rate in this process can be as low as 1 nm per minute to as high as few micrometers per minute. The material utilization efficiency is high relative to other methods and the process offers structural and morphological control of films. Due to the very high deposition rate, this process has potential industrial application for wear resistant and thermal barrier coatings aerospace industries, hard coatings for cutting and tool industries, and electronic and optical films for semiconductor industries. Additionally, coating uniformity and precise layer monitoring techniques are also some advantages with this process.
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Physical Vapor Deposition – Written by: Ace Perez (08/23/12)