How does the vacuum coating equipment work?
Vacuum coating machine mainly refers to a type of coating that needs to be carried out under a higher vacuum, including many types, including vacuum resistance heating evaporation, electron gun heating evaporation, magnetron sputtering, MBE molecular beam epitaxy, PLD laser sputtering deposition, ion There are many kinds of beam sputtering. The main idea is divided into two kinds of evaporation and sputtering.
Evaporation coating generally heats the target material to evaporate the surface components in the form of radicals or ions. And it settles on the surface of the substrate and forms a thin film through a film-forming process (scattered points-island structure-vagus structure-layered growth). For sputtering coatings, it can be simply understood as using electrons or high-energy lasers to bombard the target material, and the surface components are sputtered out in the form of radicals or ions, and finally deposited on the surface of the substrate, undergoing the film forming process, and finally forming a thin film , Vacuum coating machine.
The uniformity of the thickness of the vacuum coating machine can also be understood as the roughness. On the scale of the optical film (that is, 1/10 wavelength as the unit, about 100A), the uniformity of the vacuum coating is quite good, and it can be easily changed. The roughness is controlled within 1/10 of the wavelength of visible light, which means that there is no obstacle to the optical properties of the film in vacuum coating. But if it refers to the uniformity on the atomic layer scale, that is to say, to achieve a 10A or even 1A surface smoothness, the specific control factors will be explained in detail below according to different coatings.
Film uniformity means that in the film, the atomic composition of the compound will easily produce uneven characteristics due to the small size. For the SiTiO3 film, if the coating process is unscientific, then the actual surface composition is not SiTiO3, but may be other The ratio of the coating film is not the chemical composition of the desired film, which is also the technical content of the vacuum coating.
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