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Differences between evaporation coating and sputtering coating

  As we all know, vacuum evaporation and ion sputtering are commonly used in vacuum coating. What is the difference between evaporation coating and sputtering coating? Next, the technical experts from RSM will share with us.

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  Vacuum evaporation coating is to heat the material to be evaporated to a certain temperature by means of resistance heating or electron beam and laser bombardment in an environment with a vacuum degree of not less than 10-2Pa, so that the thermal vibration energy of molecules or atoms in the material exceeds the binding energy of the surface, so that a large number of molecules or atoms evaporate or sublimate, and directly precipitate on the substrate to form a film. Ion sputtering coating uses the high-speed movement of positive ions generated by gas discharge under the action of electric field to bombard the target as the cathode, so that atoms or molecules in the target escape and precipitate to the surface of the plated workpiece to form the required film.

  The most commonly used method of vacuum evaporation coating is resistance heating, which has the advantages of simple structure, low cost and convenient operation; The disadvantage is that it is not suitable for refractory metals and high temperature resistant dielectric materials. Electron beam heating and laser heating can overcome the shortcomings of resistance heating. In electron beam heating, the focused electron beam is used to directly heat the bombarded material, and the kinetic energy of the electron beam becomes heat energy, which makes the material evaporate. Laser heating uses high-power laser as the heating source, but due to the high cost of high-power laser, it can only be used in a few research laboratories at present.

  Sputtering technology is different from vacuum evaporation technology. “Sputtering” refers to the phenomenon that charged particles bombard the solid surface (target) and make solid atoms or molecules shoot out from the surface. Most of the emitted particles are in atomic state, which is often called sputtered atoms. The sputtered particles used to bombard the target can be electrons, ions or neutral particles. Because ions are easy to accelerate under the electric field to obtain the required kinetic energy, most of them use ions as bombarded particles. Sputtering process is based on glow discharge, that is, sputtering ions come from gas discharge. Different sputtering technologies adopt different glow discharge modes. DC diode sputtering uses DC glow discharge; Triode sputtering is a glow discharge supported by hot cathode; RF sputtering uses RF glow discharge; Magnetron sputtering is a glow discharge controlled by an annular magnetic field.

  Compared with vacuum evaporation coating, sputtering coating has many advantages. For example, any substance can be sputtered, especially elements and compounds with high melting point and low vapor pressure; The adhesion between sputtered film and substrate is good; High film density; The film thickness can be controlled and the repeatability is good. The disadvantage is that the equipment is complex and requires high-voltage devices.

  In addition, the combination of evaporation method and sputtering method is ion plating. The advantages of this method are that the obtained film has strong adhesion with the substrate, high deposition rate and high film density.


Post time: Jul-20-2022