The sputtering deposition rate is a parameter that characterizes the deposition rate. The deposition rate is determined by the type and pressure of the working gas, the target species, the sputter etching area, the target surface temperature and the target surface magnetic field intensity, the distance between the target and the substrate. In addition, it is also directly affected by the power density of the target surface, i.e. the “sputter voltage and current” of the target power supply.
1. Sputtering Voltage and Deposition Rate
The stronger and denser the plasma between the front magnetic field control regions of the magnetron target, the higher the atomic detachment rate on the target. Among factors that affect the sputtering coefficient, after the target, sputtering gas and other factors are set, it is the discharge voltage of the magnetron target that is more effective. In general, in the normal process of magnetron sputtering, the higher the discharge voltage, the larger the sputtering coefficient of the magnetron target; that is, the larger incident ion energy, the larger sputtering coefficient. Within the range of energy required for sputter deposition, its effect is moderate and gradual.
2. Sputtering Current and Deposition Rate
The magnetron target's sputtering current is proportional to the target surface ion current, so the impact on the deposition rate is much greater than the voltage. There are two ways to increase the sputtering current: one is to increase the operating voltage, the other is to appropriately increase the working gas pressure. The deposition rate corresponds to an optimum pressure value. Under this gas pressure, the relative deposition rate is the highest. This phenomenon is the common rule of magnetron sputtering. Without affecting the quality of the film or satisfying the requirements of the user, it is appropriate to consider the optimum value of the gas pressure based on the sputtering yield.
3. Sputtering Power and Deposition Rate
In general, when the sputtering power of a magnetron target increases, the deposition rate of the film also increases. There is a prerequisite that the sputtering voltage applied to the magnetron target is sufficiently high so that the energy obtained by working gas ions in the electric field between the cathode and anode is sufficient to exceed the "sputtering energy threshold" of the target. Sometimes, the magnetron target has a very low sputtering voltage (eg, more than 200 volts), but the sputtering current is relatively high. Although the average sputtering power is not low, the target ion sputtering cannot be sputtered out and deposited to a film. Recording the sputtering voltage and sputter current data of the magnetron target can not only help us know the “sputtering power” of the magnetron target, but also can help us roughly understand the level of energy of the bombardment target ion and correctly estimate the deposition status of the target ion. It will help to analyze the problems and phenomena in many vacuum coating processes.