Understanding the Mechanisms of Vacuum Evaporation Coating

Vacuum evaporation coating is a common method used to deposit thin films onto a substrate. This technique is widely used in a variety of industries, such as electronics, optics, and aerospace, due to its ability to create precise and uniform coatings with a high level of purity. There are several mechanisms used to achieve vacuum evaporation coating, each with its own advantages and limitations.


One common method is resistance evaporation, which uses a resistance evaporation source made of tungsten, molybdenum, or tantalum to evaporate low melting point materials such as gold, silver, zinc sulfide, magnesium fluoride, chromium oxide, and others. However, this method may not meet the needs of vapor deposition of certain metals and non-metals.


Electron beam evaporation is another technique used for vacuum evaporation coating. It involves heating the evaporating material with an electron beam, which can provide a much larger energy density than the resistance heat source. This allows for the heating of refractory metals and non-metallic materials such as tungsten, molybdenum, niobium, SiO2, AI2O3, and others. Additionally, the material to be vapor-deposited is placed in a water-cooled crucible, which helps to avoid evaporation of the container material and reaction between the container material and the membrane material, thus improving the purity of the membrane.

Various Types of Evaporation Pellets Materials


High-frequency induction heating evaporation is another method used for vacuum evaporation coating. The metal is heated to the evaporation temperature using the principle of induction heating. The crucible containing the evaporation material is placed in the center of the spiral coil, and a high-frequency current is passed through the coil to heat the metal evaporation material until evaporation. This method has a large evaporation rate, uniform and stable evaporation source temperature, easy temperature control, and requires less purity of the evaporation materials.


Arc heating evaporation uses the arc discharge heating method, which is similar to the electron beam heating method. This method is particularly suitable for evaporation of refractory metals and graphite that have a high melting point and a certain conductivity. It also has the advantage of being relatively inexpensive compared to the electron beam heating apparatus.


In conclusion, vacuum evaporation coating is a versatile and widely used technique for depositing thin films onto a substrate. There are several methods used to achieve this, each with its own advantages and limitations. By understanding the different mechanisms of vacuum evaporation coating, researchers and industry professionals can choose the appropriate method to achieve the desired coating properties for their specific applications.

If you want to learn more about sputtering targets, such as metals, alloys, oxides, and ceramic materials, you can visit the website of Stanford Advanced Materials (SAM) Corporation at https://www.sputtertargets.net/. SAM is a global supplier of various sputtering targets and regularly updates their knowledge and interesting stories related to sputtering targets on their website.

Five evaporation sources for heating

The evaporation source is a heating element used to vaporize  the molding material. The evaporation sources currently used mainly include the following types:

Resistance evaporation heating source

The resistance heating method is simple and easy to operate, and is a common application method: a filament-like or sheet-like high melting point metal (such as Tungsten, Molybdenum, Titanium, etc.) is made into an evaporation source of a suitable shape. It is equipped with an evaporation material to turn on the power supply, and the evaporation material is directly heated and evaporated. The resistance heating method should mainly consider two problems, the melting point and vapor pressure of the evaporation material; the reaction of the evaporation material with the coating material and the wettability caused by the coating material.

Electron beam evaporation source

The evaporation material is placed in a water-cooled copper dry pot and directly heated by an electron beam, which is called electron beam heating. It can vaporize the evaporation material and form a film on the surface of the substrate. It is an important heating method and development direction in the vacuum evaporation coating technology. In the resistance heating method, the coating material and the evaporation material are in direct contact, and the temperature of the evaporation material is higher than that of the coating material, and is easily mixed into the coating material, especially in the semiconductor device coating. Electron beam evaporation can overcome many shortcomings of general resistance heating evaporation, and is particularly suitable for preparing high melting point film materials and high purity film materials.

High frequency induction heating evaporation source

The high-frequency induction heating evaporation source places the graphite or quartz crucible containing the evaporation material in the center of the water-cooled high-frequency spiral coil, so that the evaporation material generates strong eddy current loss and hysteresis loss under the induction of the magnetic field in the high frequency band (to Ferromagnetic), causing the evaporating material to heat up until evaporation. The smaller the volume of the evaporated material is, the higher the frequency of induction is. In the large-scale vacuum aluminum plating equipment on the steel strip, the high-frequency induction heating evaporation process has achieved great success.

Radiant heating evaporation source

For materials with high absorption of infrared radiation, it can be evaporated by radiant heating, and many substances are evaporated by this method. In addition, the reflectivity of the metal for infrared radiation is high, and the absorption rate of quartz for infrared radiation is low, so they are difficult to be evaporated by radiation heating. The main advantage of the radiant heating method is that the evaporation is only heated on the surface, and the adsorbed gas is released on the surface without splashing the material.

Laser beam evaporation source

The evaporation technique using a laser beam evaporation source is an ideal film preparation method because the laser can be installed outside the vacuum chamber. This not only simplifies the space arrangement inside the vacuum chamber and reduces the abandonment of the heating source, but also completely avoids the contamination of the evaporation material by the evaporator, thus it is advantageous for obtaining a high-purity film.


Stanford Advanced Materials (SAM) Corporation is a global supplier of various sputtering targets such as metals, alloys, oxides, ceramic materials. If you are interested, please visit our website https://www.sputtertargets.net/ for more information.