Vacuum evaporation technology

Vacuum evaporation technology
The PVD method can prepare films with excellent performance at lower temperatures, and the raw materials used are solid, which can prepare metal and compound films. The PVD method includes positive air vapor deposition, sputtering film formation, and so on. The glass bottle manufacturer heats the solid substance in a vacuum below 10-2Pa by the so-called vacuum evaporation to evaporate and form a film on the substrate. This is the most basic PVD method. The process of forming the thin film is that the vapor deposition raw material is heated in the evaporation source, the molecules or atoms of the vapor deposition raw material fly toward the machine board, and the molecules or atoms adhere to the clean substrate and form a thin film.
Since the temperature and vacuum degree of the evaporation source are different for different evaporators, the heating temperature when the vapor pressure of the substance is 1Pa is generally used as the reference point and the vacuum degree is less than 10-3Pa. It is better that molecules or atoms do not collide with remaining gas molecules during the flight before reaching the substrate, so that the energy they had before evaporation can be maintained. The glass bottle manufacturer does not collide with other molecules at temperature T, and the distance of travel is the mean free path. Generally, the vacuum degree to prevent the vapor deposited molecules or atoms from colliding with the residual gas molecules should be 10-2Pa. the following. In actual evaporation, in addition to the incident and adhesion of evaporated atoms or molecules to the substrate, the frequency of this gas molecule incident and adhesion to the substrate, the glass bottle factory needs to prepare a thin film that contains no or very little residual gas as impurities. The vacuum should be lower, and the practical one should be below 10-3Pa. We require that the film with high purity should be below 10-7Pa, which is the source of evaporation. Compared with the evaporation area S, the opening area S is very small. If the loss of molecules is negligible, it can be considered as the vapor pressure in the furnace. balance. At this time, the number of molecules ejected from the opening is only affected by the temperature in the furnace, and this temperature can control the intensity of the molecules flying outward.