Magnetron sputtering

Thin layers of molybdenum are applied (sputtered) using the magnetron sputtering process. The starting material for this vacuum-based coating process takes the form of a sputtering target.

A plasma is ignited in a vacuum chamber by applying a voltage of several hundred volts and admitting argon gas. This plasma consists of pure argon, positively charged argon particles (argon ions) and free electrons. An electric field accelerates the positively charged argon ions towards the negatively charged cathode (the target). Here they collide with the surface of the target with a high kinetic energy of a few tens up to a hundred electron volts (eV). In a way that resembles a game of billiards, the argon particles dislodge atoms from the surface of the sputtering target. In this way, the coating material is slowly eroded. The atoms that are released from the target travel through the vacuum chamber toward the substrate opposite where they are deposited as a thin layer (similar to a bathroom mirror that films over with water vapor while the shower is running).

How PVD coating works: