磁控溅射的工作原理是什么？What is the working principle of magnetron sputtering?

磁控溅射的工作原理是指电子在电场E的作用下，在飞向基片过程中与氩原子发生碰撞，使其电离产生出Ar正离子和新的电子;新电子飞向基片，Ar离子在电场作用下加速飞向阴极靶，并以高能量轰击靶表面，使靶材发生溅射。在溅射粒子中，中性的靶原子或分子沉积在基片上形成薄膜，而产生的二次电子会受到电场和磁场作用，产生E(电场)×B(磁场)所指的方向漂移，简称E×B漂移，其运动轨迹近似于一条摆线。

若为环形磁场，则电子就以近似摆线形式在靶表面做圆周运动，它们的运动路径不仅很长，而且被束缚在靠近靶表面的等离子体区域内，并且在该区域中电离出大量的Ar 来轰击靶材，从而实现了高的沉积速率。随着碰撞次数的增加，二次电子的能量消耗殆尽，逐渐远离靶表面，并在电场E的作用下最终沉积在基片上。由于该电子的能量很低，传递给基片的能量很小，致使基片温升较低。

磁控溅射台是入射粒子和靶的碰撞过程。入射粒子在靶中经历复杂的散射过程，和靶原子碰撞，把部分动量传给靶原子，此靶原子又和其他靶原子碰撞，形成级联过程。在这种级联过程中某些表面附近的靶原子获得向外运动的足够动量，离开靶被溅射出来。

     The working principle of magnetron sputtering is that electrons collide with argon atoms in the process of flying to the substrate under the action of electric field E, resulting in AR positive ions and new electrons; new electrons fly to the substrate, and Ar+ ions accelerate to the cathode target under the action of electric field, and bombard the target surface with high energy, resulting in sputtering of the target. In sputtered particles, the neutral target atoms or molecules are deposited on the substrate to form a thin film, and the secondary electrons generated will be affected by the electric field and magnetic field, resulting in the direction drift of E (electric field) × B (magnetic field), which is called e × B drift for short, and its motion track is similar to a cycloid.  

      If the magnetic field is circular, the electrons move in the form of approximate cycloid on the target surface. Their motion path is not only very long, but also bound in the plasma region near the target surface. In this region, a lot of AR is ionized to bombard the target, thus achieving a high deposition rate. With the increase of the number of collisions, the energy of the secondary electrons is exhausted and gradually away from the target surface, and finally deposited on the substrate under the action of the electric field E. Because the energy of the electron is very low and the energy transferred to the substrate is very small, the substrate temperature rise is low.

Magnetron sputtering is a collision process between the incident particles and the target. The incident particle experiences a complex scattering process in the target, collides with the target atom, and transfers part of the momentum to the target atom, which collides with other target atoms, forming a cascade process. In this kind of cascade process, some target atoms near the surface obtain enough momentum to move outwards, leaving the target to be sputtered out.