What Does Vacuum Deposition Mean?
Vacuum deposition refers to a family of processes used to deposit layers of material atom-by-atom or molecule-by-molecule on a solid surface.
This technique involves depositing a desired film thickness, even in the nanometer range, in the clean environment of high vacuum. It is widely used for film preparation of inorganic materials on an industrial scale. This method is often used for applying corrosion-resistant coatings onto substrates.
Corrosionpedia Explains Vacuum Deposition
Vacuum deposition is a technique which is used to deposit layers of material onto substrates under vacuum conditions. There may be multiple layers of different materials with thicknesses that can range from less than 1 nm to several microns.
This technique is particularly useful for the production of coatings, since it has a greatly reduced environmental impact and high versatility. The advantages of this techniques are:
- Many devices employed for the generation of vapors work only in a vacuum.
- The majority of the materials would be oxidized in conventional atmospheres.
- Vacuum deposition processes are ecologically very clean.
- At atmospheric pressure, the average free vapor molecules are very short (less than a millimeter), and therefore they could not reach the substrates.
This technique can be subdivided into two main families:
- PVD (Physical Vapor Deposition) - The condensing vapors forming the film are obtained by physical means (heating, sputtering).
- CVD (Chemical Vapor Deposition) - Vapors are obtained by means of dissociation of suitable gaseous species.
Each of these two categories includes many different techniques. Amongst the PVD techniques are:
- Evaporation by electronic gun
- Evaporation by cathodic arc
- Molecular beam epitaxy
Amongst the CVD techniques are:
- Thermal (conventional) CVD
- Plasma activated (PECVD)
The vacuum environment serves following purposes:
- Reducing the particle density
- Providing a low-pressure plasma environment
- Providing a means for controlling gas and vapor composition
- Providing a means for mass flow control into the processing chamber
Vacuum depositions are generally used to improve hardness, wear resistance and oxidation resistance. Thus, such coatings are used in a wide range of applications, such as:
- Electrical conduction
- Semiconductor devices
- Solar cells
- Optical films
- Reflective coatings
- Energy conservation & generation
- Magnetic films
- Diffusion barriers
- Corrosion protection
- Automotive applications