Input DC, high frequency or microwave power to the raw gas with certain pressure to generate gas discharge and to form plasma. In gas discharge plasma, because of the collision between low speed electrons and gas atoms, a large number of active groups (excited atoms, molecules, etc.) will be produced in addition to positive and negative ions, which can greatly enhance the activity of the reaction gas. In this way, the reaction can occur and the thin films can be deposited at a relatively low temperature.
The film can be formed at lower temperature, which has little effect on the substrate, so that the defects such as the coarse grain size of the film layer caused by high temperature film formation and the easy shedding of the film and the substrate can be avoided.
Under lower pressure, due to the collision, scattering and ionization between molecules, atoms, plasma particles and electrons in the reactants, the thickness and composition uniformity of the film can be improved, and the pinhole of the film can be reduced, the microstructure is dense, the internal stress is small, and the microcrack is not easy to occur.
Plasma can clean the substrate and the surface of the film and improve the adhesion strength of the film to the substrate.
The application range of chemical vapor deposition is expanded, especially the possibility of preparing various metal films, amorphous inorganic films and organic polymer films on different substrate.
The characteristics of high deposition rate and low deposition temperature decrease the internal stress of the films and improve the quality of film formation.
In the optical industry, it is used to manufacture optical filters, anti-reflective films and devices with undesirable refractive index. In mechanical engineering, it is used to extend the life of tools by applying wear-resistant coatings (for example,diamond-like carbon or quasi-diamond) or preventing corrosion (for example, Cr2O3 or MgO). In electronics and microelectronics, it is used to provide insulation for parts or devices as well as to produce solar cells for surface passivation, high quality diamond-like carbon film, hard coating, optical film and so on.
