Arc current, temperature, bias voltage and binding force
1. The arc current
When the arc current is low, the number of ions is small, the amount of energy is low, the nucleation rate is low, and the structure is not dense. In order to cover the whole matrix, the atoms of the film layer need to be dispersed over a long-range.
With the increase of arc current, the number of ions in the membrane layer increases, the energy increases, and the tissue density increases. The film atoms do not need long-range diffusion to cover the whole matrix, and the film grains are small and the bonding strength with the atoms on the surface of the matrix is high
Arc current continues to increase, film surface appears too many liquid droplets, film strength, hardness decreases, film adhesion decreases.
Note: the so-called arc current size here should be based on the arc current matched with the equipment as the reference, the magnetic field, cooling, target system, etc., the appropriate current matched with it is not the same. There is no corresponding detailed information, and the values given are for reference only.
2. The temperature
When the deposition temperature is low, the atomic activity of film layer is low, nucleation rate is low, compactness is poor, shrinkage cavity is more, internal stress is poor, adhesion is poor.
With the increase of temperature, the atomic activity of film layer is enhanced, the diffusion ability is strong, the nucleation rate is increased, the density is high, the shrinkage cavity is few, the internal stress is low, the binding force is high.
The temperature continues to rise, exceeding the tempering temperature of the matrix. As the hardness of the matrix decreases, it cannot play a strong supporting role on the film, which leads to the reduction of the adhesion force of the film.
Question: if the matrix temper temperature is high enough, whether the binding force will continue to increase?
3. The bias
With the increase of bias voltage, the deposited ions have a strong bombardment effect on the atoms on the surface of the substrate, forming a pseudo-diffusion layer and improving the adhesion of the film. In the film forming process, the continuous bombardment of the film by high-energy particles makes the grain size of the film smaller and the nucleation density increased, which makes the film continue to form a film under relatively thin conditions, thus improving the binding force.
Excessive bias voltage will lead to overheating of the substrate, excessive stress in the interface with the substrate when high-energy ions are deposited, and anti-sputtering action will reduce the bonding force of the film.
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