Do You Know CVD

                                                                                              The denifition of CVD

This technology was originally developed as a means of coating, but it is not only applied to the coating of heat-resistant substances, but also applied to the refining of high-purity metals, powder synthesis, semiconductor films, etc., which is a quite characteristic technical field.
Its technical features are: ⑴ High melting point materials can be synthesized at low temperature; ⑵ The forms of precipitated substances are single crystal, polycrystalline, whisker, powder, film, etc.; ⑶ It can not only be coated on the substrate, but also on the powder surface. Especially at low temperature, it can synthesize materials with high melting point, which has made contributions to energy saving. As a new technology, it has great prospects.

For example, a-Al2O3 and SiC can be synthesized at about 1000 ℃ and are developing towards lower temperature.CVD is carried out in the gas phase of multi-component system including raw gas, by-product gas generated by reaction, carrier gas, etc. Therefore, when coating, a diffusion layer is formed on the boundary between the heated substrate and the fluid. The existence of this layer has a great impact on the density of the coating. Figure 2 shows the schematic diagram of this diffusion layer. In this way, although the diffusion layer formed by many chemical molecules exists, its precipitation process is complex. During powder synthesis, the control of nucleus formation and growth is the key point of the process.

CVD (Chemical Vapor Deposition) refers to the process of introducing the vapor of gaseous or liquid reactants and other gases required for the reaction into the reaction chamber, which contains the elements constituting the film, to produce the film by chemical reaction on the substrate surface. In VLSI, many thin films are prepared by CVD method. After CVD treatment, the adhesion of the surface treatment film is improved by about 30% to prevent the scratch caused by bending, stretching and other forming of high-strength steel.