Study On The Key Technology Of The Magnetic Filters For Multi-arc Ion Planting

The vacuum multi-arc ion plating is one of the most widely used technologies of surface treatment due to its environmentally-friendly deposition process and the excellent performance of the films.However,a major drawback of this deposition process is the emission of macroparticles which can degrade the qualities of the films precluding the wide use of the technology in semiconductor industry.In practice,various measures have been taken to reduce the emission of macroparticles including the magnetic filter.In this paper,a finite element simulation method has been established for the design and improvement of the magnetic filters based on COMSOL Multiphysics 5.3.The distribution of the magnetic field and the transmission of the particles in 45°,60°and 90°duct filters have been analyzed.The function of the coil current(magnetic field),duct bias,baffle aperture and incidence angle of particles on the transmission efficiency have been investigated.Meanwhile,series of experiments on the transmission efficiency of 90°duct were conducted to verify the simulation method.The influences of the coil current,baffle aperture and arc current on the distribution of macroparticles have been analyzed.The tetrahedral amorphous carbon(ta-C)films were deposited and their general properties were measured as well.The conclusions indicate that:(1)The strength of magnetic field can be effectively controlled by adjusting the coil current.The motions of charged particles follow Larmor screwing,while the macroparticles would be filtered owing to the crash on the wall.(2)The transmission efficiency and the number of macroparticles will increase with the rise of the coil current.When the duct bias is about 11 to 16V,the transmission efficiency is about 75 to 80%higher than when no bias is applied.(3)The increase of the baffle aperture would result in the improvement of the transmission efficiency whereas the exacerbation of the macroparticles'pollution as well.In contrast,the decrease of the baffle aperture would lead to the reduction of macroparticles'pollution at the cost of transmission efficiency.The number and size of macroparticles all tend to increase when the arc current is intensified.(4)The experiments conform with the simulation precisely,indicating that the simulation method can be used in the design and optimization for various filters.(5)The ta-C films deposited under optimized parameters have advantages in sp~3 bond content,roughness and hardness.The average density of macroparticles is less than 1.35/?m~2 and the diameter is less than 0.27?m.The excellent properties of the films also prove the stability of the coating technology.