The working principle and mode of high-power pulsed magnetron sputtering power supply
The high-power pulsed magnetron sputtering power supply uses a rectangular wave voltage pulsed power supply instead of the traditional DC power supply for magnetron sputtering deposition. The high-power pulsed magnetron sputtering power supply technology can effectively suppress the generation of arcs, eliminate the resulting film defects, and at the same time increase the sputtering deposition speed, reduce the deposition temperature and a series of significant advantages, then, let's understand the next high How does the power pulse magnetron sputtering power supply work!
Pulses can be divided into two-way pulses and one-way pulses. The two-way pulses have two phases of positive voltage and negative voltage in one cycle. In the negative voltage zone, the high-power pulsed magnetron sputtering power source sputters the target material, and in the positive voltage zone, it electronically neutralizes the positive charge accumulated on the surface of the target material to purify the surface and expose the metal surface. The pulse voltage applied to the target is the same as that of normal magnetron sputtering (400~500V). Pulsed magnetron sputtering usually adopts square wave pulse waveform, mid-frequency band) 20~200 kHz), which effectively eliminates abnormal arc discharge. Occurrence, thereby eliminating the occurrence of arc discharge. Since the movement speed of electrons in the plasma is much higher than the ion speed, the positive voltage of the conversion target is usually 10% to 20% of the negative bias voltage, which can prevent arc discharge. Some studies believe that the pulse width (the ratio of positive and negative voltage to time) plays an important role, and when the pulse width reaches 1) 1, it has a suppressive effect; the magnitude of the positive voltage has no great influence on the existence of arc discharge, but it greatly affects the deposition Speed, the positive voltage rises from 10% to 20% (ratio to the negative voltage), and the deposition speed increases by 50%.
High-power pulsed magnetron sputtering power supply is mostly used in double-target closed unbalanced magnetron sputtering system. The two magnetron targets in the system are connected to the same pulse power supply. Like the intermediate frequency twin target, the two targets alternately function as the cathode and the anode. The cathode target completes the cleaning of the anode target surface while sputtering. Sexually
The main parameters of high-power pulsed magnetron sputtering power supply are sputtering voltage, pulse frequency, and duty cycle. Since the electrons in the plasma have higher motility to ions, the positive voltage value is 10% to 20% of the negative voltage value, which can effectively neutralize the positive charge accumulated on the target surface. The pulse frequency is usually in the intermediate frequency range. The lower limit of the frequency is determined by ensuring that the electric field intensity generated by the accumulated charges on the target surface is lower than the threshold value of the breakdown electric field intensity. The upper limit of the frequency mainly considers the accumulation speed, generally under the premise of ensuring stable discharge , Take the lowest possible frequency. The duty cycle is selected, on the basis of ensuring that the charge accumulated on the surface of the target is completely neutralized during the positive voltage stage during sputtering, the duty cycle is increased as much as possible to achieve greater efficiency of the power supply.
Another new development is the application of pulsed bias to the substrate. The pulsed bias voltage can greatly increase the flow of the ion beam on the substrate. In magnetron sputtering, it is generally believed that when a negative DC bias voltage is applied to -100 V, the ion beam current of the substrate is saturated. Even if the negative bias voltage is increased, the ion beam current of the substrate does not increase. The saturation current is the ion beam current. , The electrons cannot be close to the surface of the substrate. Studies have shown that if the pulse bias voltage is used, it will not be the case. The pulse bias voltage will not only increase the saturation current of the substrate, but also as the negative bias voltage increases, the saturation current will also increase; When the frequency becomes higher, the effect is more pronounced; the mechanism is not yet clear, and it may be related to the dissociation rate of the oscillating electric field on the plasma and the high electron temperature. The substrate pulse negative bias provides a new method for effectively controlling the current density of the substrate, and its effect can be applied to film structure, adhesion optimization, sputtering cleaning and shortening the substrate heating time.
The above is the working principle and working method of the high-power pulsed magnetron sputtering power supply. If you need to know more, please feel free to contact us!