Film uniformity concept for PVD coating equipment?

PVD coating equipment mainly refers to a kind of coating equipment that needs to be carried out under high vacuum, including many types, including vacuum resistance heating evaporation, electron gun heating evaporation, magnetron sputtering, MBE molecular beam epitaxy, PLD laser sputtering deposition, ion beam sputtering, etc. The main idea is divided into evaporation and sputtering.

1. Uniformity in thickness can also be understood as roughness. From the scale of the optical film (that is, 1/10 wavelength as a unit, about 100A), the uniformity of the vacuum coating is quite good, and the roughness can be easily controlled within 1/10 of the wavelength of visible light, that is, there is no obstacle to the optical properties of the film. However, if it refers to the uniformity on the atomic layer scale, that is, to achieve 10A or even 1A surface flatness, the specific control factors will be explained in detail according to different coatings.

2. Uniformity of chemical composition: that is to say, in the film, the atomic components of the compound will easily produce uneven characteristics due to the small size. If the coating process of SiTiO3 film is not scientific, then the actual surface composition is not SiTiO3, but may be other proportions. The coating is not the desired chemical composition of the film, which is also the technical content of vacuum coating.

3. Uniformity of lattice order: this determines that the film is single crystal, polycrystalline, and amorphous, which is a hot issue in vacuum coating technology.