Large Sputtering System
Small Sputtering System
The Sputtering systems are located in room 20b of the ASTeCC building. The sputtering system can deposit a wide variety of materials from metals to oxides to alloys and compounds. The large system has 5 sputtering guns powered by both DC and RF power sources. The substrate holder rotates and can be heated. The recommended maximum deposition thickness is 200 nm (2,000 A).The Center does provide some deposition targets: Aluminum, Alumina, Cobalt, Iron, Nickel, Permalloy, Silicon, and Titanium. The Center also provides Nitrogen and Argon gases. Targets are changed every other week in the large system and can be changed for every deposition in the small system. Non-standard targets (targets not listed above) are allowed ONLY on the last week of the month. Copper, Gold, and Silver are not allowed in the Large Sputtering system. A gold sputtering target is available for the small system for an additional fee.
At high vacuums,process gases are used to create a plasma which is then used to bombard a target material in order to eject that materials atoms into the vacuum.Deposition of this material onto the sample occurs when a shutter is opened to expose the sample to these free atoms.(Some example targets include gold,aluminium,nickel,cobalt,titanium,etc...). Deposited materials have same composition as source materials(as opposed to evaporation techniques with alloys).Better adhesion and more control than evaporation methods.
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>.