Metal Deposition
Metals like aluminum, gold and tungsten are used to create conductive layers on a device. They are generally applied with two different methods, evaporation and sputtering, grouped into the category of "physical vapor deposition", or PVD.

Evaporation uses heat (either an electric filament or an electron beam) and high-vacuum (between 5x10-5 Torr and 1x10-7 Torr) to vaporize the metal source. The evaporating source material condenses on the surface of the cooler wafers which are held in a semispherical or "planetary" arrangement over the source.

Sputtering uses a cathode to create an argon plasma which bombards the source metal. The dislodged metal molecules are focused by a "lens" of radiation-absorbent material, called a collimator, and deposited in a thin film on the surface of the wafer.