Ion Beam Deposition, or sputtering is a process of applying materials to a target through the application of an ion beam, and is often used in conjunction with ion beam etching in semiconductor manufacturing.
For an example, to deposit a metal on a semiconductor, a block of the metal to be deposited is placed in a vacuum chamber, at a 45-degree angle to an ion beam. The ions striking the metal will knock of individual atoms of the metal at very high speed. The target, placed in this stream of metal atoms, will gradually accumulate a coating of the metal. The thickness of the coating will depend on the length of time that the target is exposed. This technique allows extremely precise control of the thickness of the deposited films.