Magnetron sputtering technology has become one of the most important deposition coating methods in recent decades. It is widely used in industrial production and scientific research. For example, in the modern machining industry, magnetron sputtering technology is used to coat functional films, super-hard films, and self-lubricating films on the surface of workpieces. In the field of optics, magnetron sputtering technology is used to coat antireflection films, low-emissivity films and transparent films, heat-insulating films. Magnetron sputtering technology also plays an important role in the field of microelectronics, optical and magnetic recording. However, magnetron sputtering technology also has its own shortcomings, such as low target utilization, low deposition rate and low ionization rate. The low target utilization rate is due to the existence of tracks on the target surface, which confines the plasma to a local area of the target surface, causing regional sputtering of it. The shape of the tracks is determined by the magnetic field structure behind the target. The key to improving the utilization of the target is to adjust the magnetic field structure so that the plasma exists in a larger target surface area to achieve uniform sputtering. For magnetron sputtering, the sputtering yield can be increased by increasing the target power, but the target may be melted and cracked due to the thermal load.
These problems can be solved by increasing the sputtering area of the target surface in the case of the same target area, resulting in a decrease in the power density of the target surface. Therefore, the magnetic field design of the magnetron sputtering cathode has been continuously improved. Some of them are representative:
1. Circular planar magnetron sputtering source, the tracks on the target surface pass through the center of the target by the reasonable design of the magnetic field, and the magnet is rotated by the mechanical transmission device to achieve full sputtering of the target surface.
2. Rectangular planar magnetron sputtering source, combination of magnets make a diamond or plum blossom shaped movement on the back side of the target by the transmission mechanism, so that the overall target utilization rate is up to 61%. Adjusting the structure of the magnetic field can also improve the uniformity of the film thickness. The unbalanced magnetron sputtering technology developed by adjusting the ratio of the strength of the magnetic field has the function of ion plating. So the magnetic circuit design is the most important part of the magnetron sputtering source.