The thin film on the coated target is a special material shape. In the specific direction of thickness, the scale is very small, which is a microscopic measurable quantity. In addition, because of the appearance and interface of film thickness, material continuity terminates, which makes the film data and target data have different common properties.And the target is mainly the use of magnetron sputtering coating, Beijing Richmat’s edither will take us to understand the principle and skills of sputtering coating.
一、Principle of sputtering coating
Sputtering coating skill is to use ion shelling target appearance, the target atoms are hit out of the phenomenon known as sputtering. The atoms deposited on the surface of the substrate are called sputtering coating.Generally, gas ionization is produced by gas discharge, and the positive ions bombast the cathode target at high speed under the action of electric field, striking out the atoms or molecules of the cathode target, and flying to the surface of the substrate to be deposited into a film.Simply speaking, sputtering coating uses low pressure inert gas glow discharge to generate ions.
Generally, the sputtering film plating equipment is equipped with two electrodes in a vacuum discharge chamber, and the cathode target is composed of coating data. The vacuum chamber is filled with argon gas with a pressure of 0.1~10Pa. Glow discharge occurs at the cathode under the action of negative high voltage of 1~3kV dc or rf voltage of 13.56mhz.Argon ions bombard the target surface and cause the sputtered target atoms to accumulate on the substrate.
二、Sputtering coating skills characteristics
1、Fast stacking speed
The difference between the high speed magnetron sputtering electrode and the traditional two stage sputtering electrode is that the magnet is arranged below the target, so the closed uneven magnetic field occurs on the surface of the target。The lorentz force on the electrons is towards the center of the heterogeneous magnetic field. Because of the focusing effect, the electrons escape less. The heterogeneous magnetic field goes around the target surface, and the secondary electrons captured in the heterogeneous magnetic field collide with the gas molecules repeatedly, which improves the high conversion rate of the gas molecules.Therefore, the high speed magnetron sputtering consumes low power, but can obtain a great coating efficiency, with ideal discharge characteristics.
2、The substrate temperature is low
High speed magnetron sputtering, also known as low temperature sputtering. The reason is that the device uses discharges in a space of electromagnetic fields that are straight to each other. The secondary electrons that occur on the outside of the target, in each other. Under the action of a straight electromagnetic field, it is bound near the target’s surface and moves along the runway in a circular rolling line, repeatedly knocking against the gas molecules to ionize the gas molecules.Together, the electrons themselves gradually lose their energy, through repeated bumps, until their energy is almost completely lost before they can escape from the surface of the target near the substrate. Because the energy of the electrons is so low, the temperature of the target does not rise too high. That’s enough to counteract the substrate temperature rise caused by the high-energy electron bombardment of an ordinary diode shot, which completes the cryogenization.
3、A wide range of membrane structures
The structure of thin films obtained by vacuum evaporation and injection deposition is quite different from that obtained by thinning bulk solids. In contrast to the generally existing solids, which are classified as essentially the same structure in three dimensions, the films deposited in the gas phase are classified as heterogeneous structures.The thin films are columnar and can be investigated by scanning electron microscopy. The columnar growth of the film is caused by the original convex surface of the substrate and a few shadows in the prominent parts of the substrate. However, the shape and size of the column are quite different due to the substrate temperature, the surface dispersion of stacked atoms, the burial of impurity atoms and the incident Angle of incident atoms relative to the substrate surface. In the excessive temperature range, the thin film has a fibrous structure, high density, composed of fine columnar crystals, which is the unique structure of the sputtering film.
Sputtering pressure and film stacking speed also affect the structure of the film. Because gas molecules have the effect of suppressing the dispersion of atoms on the surface of the substrate, the effect of high sputtering pressure is suitable for the substrate temperature drop in the model. Therefore, porous films containing fine grains can be obtained at high sputtering pressure. This small grain size film is suitable for lubrication, wear resistance, surface hardening and other mechanical applications.
4、Arrange composition evenly
Compounds, mixtures, alloys, etc., which are suitably difficult to be coated by vacuum evaporation because the vapor pressures of the components are different or because they differentiate when heated.Sputtering coating method is to make the target surface layer of atoms layer by layer to the substrate, in this sense is a more perfect film making skills. All kinds of materials can be used in industrial coating production by sputtering.
Post time: Apr-29-2022