How to improve the sputtering efficiency of magnetron sputtering station?

The sputtering method of the magnetron sputtering station is generally not efficient. In order to increase the sputtering efficiency, it is first necessary to increase the ionization efficiency of the gas. To illustrate this, let's discuss the sputtering process. When the accelerated incident ions bombard the surface of the target (cathode), it will cause electron emission. The electrons generated on the surface of the cathode begin to accelerate toward the anode and enter the negative glow region, and collide with the neutral gas atoms to produce self-sustainability. The ions required for glow discharge. The mean free path of these so-called primary electrons increases with increasing electron energy, but decreases with increasing gas pressure. At low pressures, ions are generated away from the cathode, so that their thermal wall loss is large. At the same time, there are many initial electrons that can collide with the anode with larger energy, and the loss caused by the collision cannot be caused by the collision. The emission electrons are cancelled, and the ionization efficiency is so low that the ions required for self-sustaining glow discharge cannot be achieved. The method of increasing the accelerating voltage also increases the mean free path of electrons, and thus cannot effectively increase the ionization efficiency. Although increasing the gas pressure can increase the ionization rate, at higher gas pressures, the chance of collision of the sputtered particles with the gas increases, and the actual sputtering rate is hard to be greatly improved. If a magnetic field parallel to the surface of the cathode is added, the movement of the initial electrons can be restricted to the region adjacent to the cathode, thereby increasing the ionization efficiency of the gas atoms.

Common magnetron sputtering machines mainly use a cylindrical structure and a planar structure. In both structures, the magnetic field direction is substantially parallel to the cathode surface, and the electron motion is effectively confined near the cathode. The preparation conditions of magnetron sputtering are usually: acceleration voltage: 300~800V, magnetic field: about 50~300G, pressure: 1~10 mTorr, current density: 4~60mA/cm, power density: 1~40W/cm, for The maximum deposition rate of different materials ranges from 100 nm/min to 1000 nm/min. Like sputtering, magnetron sputtering is also divided into direct current (DC) magnetron sputtering and radio frequency (RF) magnetron sputtering. In RF magnetron sputtering, the frequency of the RF power supply is usually 50~30MHz. The main advantage of RF magnetron sputtering over DC magnetron sputtering is that it does not require that the target as an electrode be electrically conductive. Therefore, theoretically any material can be sputter deposited using RF magnetron sputtering. Due to the shielding effect of the magnetic material on the magnetic field, they will weaken or change the magnetic field distribution of the target surface during sputtering deposition, affecting the sputtering efficiency. Therefore, the target of the magnetic material needs to be specially processed into a sheet to minimize the influence on the magnetic field.