Xiao Jinquan

INFLUENCE OF AXISYMMETRIC MAGNETIC FIELD ON CATHODE SPOTS MOVEMENT IN ARC ION PLATING

Arc ion plating(AIP) has been widely utilized in the deposition of various kinds of thin solid films due to the excellent characteristics of the arc plasma produced from an active cathode spot that emits ions of cathode material,as well as electrons.In AIP process,the cathode spot is usually steered by an external magnetic field.Cathode spot motion is the key factor because it affects the physical characteristics of the vacuum arc plasma,the utilization of the cathode material, the emission of macroparticles(MPs) and the quality of subsequent films containing these MPs. Therefore,cathode spot dynamics should be understood practically under a compound external magnetic field,such as in axisymmetric magnetic field(AMF),for industrial applications.An AMF produced by using an adjustable electromagnetic coil associated with a concentric magnetic flux guider was applied to the cathode surface to investigate the influence of the AMF on the arc cathode spot motion.The distribution of the magnetic field was simulated by the finite element method (FEM) software.The magnetic field intensity was measured by an SHT-V magnetometer and the distributions of magnetic field with different intensities were analyzed.Based on the results of FEM simulation and the physical mechanism of the arc cathode spot discharge,the effects of magnetic-field components and AMF on the cathode spot movement were discussed.The results showed that increasing the AMF intensity can strongly influence cathode spot movement.In the case of a weak AMF, the cathode spot moves randomly on the cathode surface.With increasing AMF,there is an increasing tendency for the cathode spot to rotate and drift toward the cathode target edge.The increase in the transverse magnetic field(TMF) intensity,B_T,can accelerate the rotational velocity of the cathode spot,increase the arc voltage and decrease the arc current.With a relatively strong AMF(B_T≈30 Gs), the cathode spot rotates near the edge of the cathode surface and is confined to a circular trajectory. A new arc cathode spot is ignited,splits,and is extinguished repeatedly on the cathode surface,which can be observed at intervals of about 0.5 s,while there is an obvious erosion track left at the bottom of the cathode edge.

STUDY ON DEPOSITION OF MAGNETIC FILMS USING ARC ION PLATING

Arc ion plating(AIP) has been widely used for depositing various kinds of coatings due to the excellent characteristics of high deposition rate,convenient parameter control,high degree of ionization in the target material,good coating-substrate adhesion,flexibility of target arrangements and merits of producing coatings with high packing density.Magnetic films,with a few micrometers or less,could be utilized in the electronics industry,such as magnetic recording,magnetic microelectromechanical systems,magneto optical modulator,and so on.In AIP process,due to magnetic shielding and self-induced magnetic field,arc spot on the surface of the magnetic target moved outside all the time,and the erosion of the magnetic target could not be stable.In this study,arc spot outside moving and unstable erosion of the magnetic target in arc ion plating have been investigated.The distribution of the magnetic field of the nonmagnetic target and the magnetic target under an additional magnetic field was simulated by the finite element method(FEM).The effect of magnetic field on the arc spot movement was researched.With the physical mechanism of the arc spot discharge,the feasibility on the solution of the application problem of the magnetic target has been discussed by the program of the composited structure target,which were composed of magnetic target materials and target shell of low saturation vapor pressure metal,target shell of insulating ceramics,or target shell of soft magnetic metal.The results showed that all these solutions could solve the problem of arc spot outside moving efficiently.In the study,the transition temperature is(136.6±23.0)℃in the solutions of the target shell of low saturation vapor pressure metal or insulating ceramics,during which the arc striking frequently transformed to the controlled movement of arc spot.

INFLUENCE OF AXISYMMETRIC MAGNETIC FIELD ON MICROSTRUCTURE AND FRICTION PERFORMANCE OF TIN FILM DEPOSITED BY ARC ION PLATING

Arc ion plating (AIP) has been widely used in the deposition of various kinds of thin solid films. In AIP process, cathode spot motion is the key factor because it affects the physical characteristics of arc plasma, the utilization of cathode materials, the ejection of macroparticles (MPs) and the quality of subsequent films. It has been found that the cathode spot can be steered by an external magnetic field, such as an axisymmetric magnetic field (AMF). In this work, a new AMF produced by using an adjustable electromagnetic coil associated with a concentric magnetic flux guider was applied to the cathode surface to deposit TiN films, and it was focused on the influence of the AMF on the content and size of MPs, microstructure and friction performance of TiN films. The results show that the size and number of MPs decrease significantly with the increase in the transverse component of AMF. Meanwhile, the TiN film (111) preferred orientation enhances and its grain size decreases. Furthermore, the friction coefficient of films reduces and the wear resistance of films increases.