磁控溅射种类？Magnetron sputtering type?

　　磁控溅射包括很多种类。各有不同工作原理和应用对象。但有一共同点：利用磁场与电场交互作用，使电子在靶表面附近成螺旋状运行，从而增大电子撞击氩气产生离子的概率。所产生的离子在电场作用下撞向靶面从而溅射出靶材。

　　靶源分平衡和非平衡式，平衡式靶源镀膜均匀，非平衡式靶源镀膜膜层和基体结合力强。平衡靶源多用于半导体光学膜，非平衡多用于磨损装饰膜。磁控阴极按照磁场位形分布不同，大致可分为平衡态和非平衡磁控阴极。平衡态磁控阴极内外磁钢的磁通量大致相等，两极磁力线闭合于靶面，很好地将电子/等离子体约束在靶面附近，增加碰撞几率，提高了离化效率，因而在较低的工作气压和电压下就能起辉并维持辉光放电，靶材利用率相对较高，但由于电子沿磁力线运动主要闭合于靶面，基片区域所受离子轰击较小.非平衡磁控溅射技术概念，即让磁控阴极外磁极磁通大于内磁极，两极磁力线在靶面不完全闭合，部分磁力线可沿靶的边缘延伸到基片区域，从而部分电子可以沿着磁力线扩展到基片，增加基片

　　区域的等离子体密度和气体电离率.不管平衡非平衡，若磁铁静止，其磁场特性决定一般靶材利用率小于30%。为增大靶材利用率，可采用旋转磁场。但旋转磁场需要旋转机构，同时溅射速率要减小。旋转磁场多用于大型或贵重靶。如半导体膜溅射。对于小型设备和一般工业设备，多用磁场静止靶源。

　　用磁控靶源溅射金属和合金很容易，点火和溅射很方便。这是因为靶（阴极），等离子体，和被溅零件/真空腔体可形成回路。但若溅射绝缘体如陶瓷则回路断了。于是人们采用高频电源，回路中加入很强的电容。这样在绝缘回路中靶材成了一个电容。但高频磁控溅射电源昂贵，溅射速率很小，同时接地技术很复杂，因而难大规模采用。为解决此问题，发明了磁控反应溅射。就是用金属靶，加入氩气和反应气体如氮气或氧气。当金属靶材撞向零件时由于能量转化，与反应气体化合生成氮化物或氧化物。

　　磁控反应溅射绝缘体看似容易,而实际操作困难。主要问题是反应不光发生在零件表面，也发生在阳极，真空腔体表面，以及靶源表面。从而引起灭火，靶源和工件表面起弧等。德国莱宝发明的孪生靶源技术，很好的解决了这个问题。其原理是一对靶源互相为阴阳极，从而消除阳极表面氧化或氮化。

　　冷却是一切源（磁控，多弧，离子）所必需，因为能量很大一部分转为热量，若无冷却或冷却不足，这种热量将使靶源温度达一千度以上从而溶化整个靶源。

    There are many kinds of magnetron sputtering. There are different working principles and application objects. But there is one thing in common: using the interaction of magnetic field and electric field, the electrons move in a spiral shape near the target surface, thus increasing the probability of electrons impacting argon to produce ions. The generated ions hit the target surface under the action of electric field, thus splashing out of the target.

    The target source is divided into equilibrium and non-equilibrium type, the equilibrium type target source coating is uniform, and the non-equilibrium type target source coating has strong binding force with the substrate. The balanced target source is mainly used for semiconductor optical films, and the unbalanced target source is mainly used for wear decorative films. According to the different distribution of magnetic field configuration, the magnetron cathodes can be roughly divided into equilibrium and non-equilibrium. The magnetic flux of the inner and outer magnetic steel of the balanced magnetic control cathode is approximately the same, and the two pole magnetic field lines are closed to the target surface, which confines the electron / plasma to the target surface well, increases the collision probability, and improves the ionization efficiency. Therefore, the glow discharge can be started and maintained under the lower working pressure and voltage, and the utilization ratio of the target material is relatively high, but the electron movement along the magnetic field lines is mainly closed to The concept of unbalanced magnetron sputtering technology is that the magnetic flux of the outer pole of the magnetron cathode is larger than that of the inner pole, the two pole magnetic field lines are not completely closed on the target surface, and some magnetic field lines can extend to the substrate area along the edge of the target, so that some electrons can extend to the substrate along the magnetic field lines and increase the substrate

    The plasma density and gas ionization rate in the region. No matter the balance is unbalanced, if the magnet is stationary, its magnetic field characteristic determines that the utilization rate of general target material is less than 30%. In order to increase the utilization ratio of the target, the rotating magnetic field can be used. But the rotating magnetic field needs a rotating mechanism, and the sputtering rate should be reduced. Rotating magnetic field is mostly used for large or valuable targets. Such as semiconductor film sputtering. For small equipment and general industrial equipment, magnetic static target source is used.

   It is easy to sputter metals and alloys with magnetron target source, and easy to ignite and sputter. This is because the target (cathode), plasma, and splashed parts / vacuum cavity can form a circuit. But if sputtering insulator such as ceramic, the circuit will be broken. So people use high-frequency power supply, and a strong capacitance is added to the circuit. In this way, the target becomes a capacitor in the insulating circuit. However, the high frequency magnetron sputtering power supply is expensive, the sputtering rate is very small, and the grounding technology is very complex, so it is difficult to use it on a large scale. In order to solve this problem, magnetron reactive sputtering was invented. It is to use metal target, add argon and reaction gas such as nitrogen or oxygen. When the metal target collides with the part, it combines with the reaction gas to form nitride or oxide due to energy conversion.

   Magnetron reactive sputtering insulator seems easy, but it is difficult to operate. The main problem is that the reaction occurs not only on the surface of parts, but also on the surface of anode, vacuum cavity and target source. So as to cause fire-extinguishing, arc on target source and workpiece surface, etc. The twin target source technology invented by German LeiBao solves this problem well. The principle is that a pair of target sources are cathode and anode to each other, so as to eliminate anodizing or nitriding on the anode surface.

Cooling is necessary for all sources (magnetically controlled, multi arc, ion), because a large part of energy is converted into heat. If there is no cooling or insufficient cooling, this heat will make the target temperature reach more than 1000 degrees and dissolve the whole target.