Glow discharge is mainly used to impact argon ions on the surface of the target material, and the atoms of the target material are ejected and accumulated on the surface of the substrate to form a thin film. The properties and uniformity of sputtered films are better than those of vaporized films, but the coating speed is much slower than that of vaporized films. Almost all new sputtering equipment use powerful magnets to move the electrons in a spiral motion to accelerate the ionization of the argon gas around the target, which increases the collision probability between the target and the argon ions and increases the sputtering rate. Generally, metal coatings mostly use DC sputtering, while non-conductive ceramic materials use AC sputtering. The basic principle is to use glow discharge in a vacuum to impact argon ions on the surface of the target, and the cations in the plasma will accelerate toward the surface of the negative electrode of the sputtered material, this impact will cause the target material to fly out and deposit on the substrate to form a thin film.
Generally speaking, the sputtering process for film coating has several characteristics:
(1) Metals, alloys or insulators can be made into thin film materials
(2) Under appropriate setting conditions, a thin film of the same composition can be made from multiple and complex targets.
(3) By adding oxygen or other active gases into the discharge atmosphere, a mixture or compound of target material and gas molecules can be made.
(4) The target input current and sputtering time can be controlled, and it is easy to obtain high-precision film thickness.
(5) Compared with other processes, it is more conducive to the production of large-area uniform films.
(6) The sputtering particles are almost not affected by gravity, and the positions of the target and the substrate can be freely arranged.
(7) The adhesion strength between the substrate and the film is more than 10 times that of the general vapor deposition film, and because the sputtered particles have high energy, they will continue to diffuse on the film forming surface to obtain a hard and dense film. At the same time, this high energy makes the substrate only need a low temperature can get the crystalline film.
(8) The nucleation density is high at the initial stage of film formation, and it can produce extremely thin continuous films below 10nm.
(9) The target material has a long life and can be automatically and continuously produced for a long time.
(10) The target material can be made into various shapes, with the special design of the machine for better control and the most efficient production.
