In the vacuum industry, many workpieces have strict surface quality requirements, so magnetron sputtering vacuum coating machine is used for coating. The magnetron sputtering coating technology has the advantages of fine structure, good film uniformity and strong adhesion, but for different The materials used are different magnetron sputtering methods. Magnetron sputtering is also divided into balanced magnetron sputtering and unbalanced magnetron sputtering. The following is a vacuum editor to introduce these two coating methods:

       Balanced magnetron sputtering of vacuum coater is the traditional magnetron sputtering, which is to place a permanent magnet or electromagnetic coil with the same or similar magnetic field strength as the outer ring behind the cathode target, and form a vertical magnetic field on the surface of the target material. magnetic field. The deposition chamber is filled with a certain amount of working gas, usually Ar. Under the action of high pressure, the original Ar is ionized into Ar+ ions and electrons, resulting in a glow discharge. The Ar+ ions are accelerated by the electric field to bombard the target, and sputter out the target atoms, ions and Secondary electrons, etc.
      Under the action of mutually perpendicular electromagnetic fields, electrons move in a cycloid fashion and are bound on the surface of the target material, extending their trajectory in the plasma, increasing their participation in the process of collision and ionization of gas molecules, and ionizing more electrons. The ions increase the ionization rate of the gas, and the discharge can be maintained at a lower gas pressure. Therefore, the magnetron sputtering not only reduces the gas pressure during the sputtering process, but also improves the sputtering efficiency and deposition rate.
       However, balanced magnetron sputtering also has its shortcomings. For example, due to the action of the magnetic field, the electrons generated by the glow discharge and the sputtered secondary electrons are tightly bound near the target surface by the parallel magnetic field, and the plasma region is strongly bound in the vicinity of the target surface. In the area of about 60 mm of the target surface, the plasma concentration decreases rapidly with the increase of the distance from the target surface. At this time, the workpiece can only be placed within the range of 50 to 100 mm on the surface of the magnetron target to enhance the effect of ion bombardment. Such a short effective coating area limits the geometric size of the workpiece to be plated, is not suitable for larger workpieces or furnace loading, and restricts the application of magnetron sputtering technology. Moreover, during balanced magnetron sputtering, the energy of the flying target particles is low, the bonding strength of the film substrate is poor, and the low-energy deposition atoms have low mobility on the surface of the substrate, and it is easy to generate a porous and rough columnar structure film. Raising the temperature of the workpiece to be plated can certainly improve the structure and properties of the film, but in many cases, the workpiece material itself cannot withstand the required high temperature.
       The emergence of non-equilibrium magnetron sputtering partially overcomes the above shortcomings. The plasma of the cathode target surface is led to the range of 200-300 mm in front of the sputtering target, so that the substrate is immersed in the plasma. In this way, on the one hand, sputtering The atoms and particles are deposited on the surface of the substrate to form a thin film. On the other hand, the plasma bombards the substrate with a certain energy, which plays the role of ion beam-assisted deposition, which greatly improves the quality of the film. Unbalanced magnetron sputtering coating machine There are two structures, one is that the magnetic field strength of the core is higher than that of the outer ring, the magnetic field lines are not closed, and are led to the wall of the vacuum chamber, and the plasma density on the surface of the substrate is low, so this method is rarely used. The other is that the magnetic field strength of the outer ring is higher than that of the core, the magnetic field lines do not completely form a closed loop, and part of the magnetic field lines of the outer ring extend to the surface of the substrate, so that part of the secondary electrons can escape from the target surface area along the magnetic field lines, and at the same time Collision ionization with neutral particles, the plasma is no longer completely confined to the target surface area, but can reach the substrate surface, further increasing the ion concentration in the coating area and increasing the substrate ion current density, usually up to 5 mA/ cm2 or more. In this way, the sputtering source is also an ion source that bombards the surface of the substrate. The ion beam current density of the substrate is proportional to the current density of the target material, the target current density is increased, the deposition rate is increased, and the substrate ion beam current density is increased. play a certain bombardment effect.
      The non-equilibrium magnetron sputtering ion bombardment of the vacuum coating machine can clean the oxide layer and other impurities of the workpiece before coating, activate the surface of the workpiece, and at the same time form a pseudo-diffusion layer on the surface of the workpiece, which helps to improve the film and other impurities. Bonding force between workpiece surfaces. During the coating process, the bombardment of energy-carrying charged particles can achieve the purpose of modification of the film. For example, ion bombardment tends to strip loosely bound and protruding particles from the film, cutting off the dominant growth of the crystalline or condensed state of the film, resulting in a denser, stronger, more uniform film, And can be plated with excellent performance at a lower temperature.