Sputter deposition is a physical vapor deposition (PVD) method of depositing thin films by sputtering, i.e. ejecting, material from a "target," i.e., source, which then deposits onto a "substrate," e.g., a silicon wafer. Resputtering, is re-emission of the deposited material during the deposition process by ion or atom bombardment.
Sputtered atoms ejected from the target have a wide energy distribution, typically up to 10's of eV's (100000 K). The sputtered atoms (typically only a small fraction -- order 1% -- of the ejected particles is ionized) can ballistically fly from the target in straight lines and impact energetically on the substrates or vacuum chamber (causing resputtering) or, at higher gas pressures, collide with the gas atoms that act as a moderator and move diffusively, reaching the substrates or vacuum chamber wall and condensing after a random walk motion. The entire range from high-energy ballistic impact to low energy thermalized motion is accessible by changing the background gas pressure. The sputtering gas is often an inert gas such as argon. For efficient momentum transfer projectile mass must match target mass, so for sputtering light elements neon is also used and for heavy elements krypton or xenon. Reactive gases are used to sputter compunds. The chemical reaction can occur on the target surface, in-flight or on the substrate depending on the process parameters. The many parameters make sputter deposition a complex process but allow experts a large degree of control over the growth and microstructure of the film.
"Sputter deposition." Wikipedia, The Free Encyclopedia. 27 Jan 2008, 15:33 UTC. Wikimedia Foundation, Inc. 5 Feb 2008 <http://en.wikipedia.org/w/index.php?title=Sputter_deposition&oldid=187263765>.