Study On Cr Film Deposition In Tube With Hybrid Electric-Magnetic Field Enhanced High Power Impulse Magnetron

Compared with plasma surface modification of flat parts,there will be more technical obstacles in the preparation of inner surface coating of tubular parts.For complex and small-size pipes,the existing treatment methods can not be applied,and the film with excellent surface properties can not be obtained.At the same time,the limitation of small inner diameter and difficulty to apply relative negative bias to tube are also thorny problems to be solved.Hipims technology has many advantages,such as dense film,good adhesion between film and substrate,good coating ability and high plasma density.The plasma density in the tube can be further enhanced and the plasma distribution in the tube can be improved by the auxiliary anode traction and the electrical coil for magnetic filed.In view of the limitation of inner diameter of the tube and the difficulty to produce dense films,this paper proposes a method to prepare Cr film with improving the film quality to optimize the depth of plasma entering the whole pipe by using auxiliary anode and electrical-coil.The results show that the peak value of the pulse current increases with the increase of the volatage of the auxiliary anode at four different positions from the nozzle to the end of the tube.Especially at the end of the tube,the peak value of the pulse current increases obviously when the auxiliary anode voltage is 60 V,compared with that without the auxiliary anode.By the acceleration of electrons and variation of the potential difference between the auxiliary anode and the cathode target,the ionization effect in the tube is enhanced,and the uniformity of substratecurrent is improved.With the increase of coil current,the non-equilibrium degree of the magnetic field increases,which makes the electrons move towards the end of the tube,thus enhance the ionization.It leads to a larger substrate current at the end of the tube increases.With the increase of substrate negative bias,the substrate current at the end of the tube increases,and the overall uniformity of the substrate current increases.The results of structure and mechanical properties analysis of Cr film at the nozzle position show that with the increase of ionization rate of sputtered target atoms,it is beneficial to the deposition of the film in the deep pipe.1.5 ?m thick Cu film can be deposited at the tail of the tube,but Cr film can not be deposited at the tail of the tube.And the films have denser film-structure,smoother surface,higher adhesion between the film and substrate and beterwear resistance.With the increase of the auxiliary anode voltage,the film may be deposited at the much longer distance in the tube.When the auxiliary anode voltage is 60 V,the film may be fabricated at the farthest site with smaller grain size,the highest hardness.The films also demonstrate higher adhesion between the film and substrate,and superior tribological properties.When the coil current is 4A,a 97 nm thick film has been grown at the middle of the tube,with a smaller grain size and denser structure.The films display the better film-substrate adhesion and tribolgical properties.With the auxiliary anode voltage of 60 V and the coil current of 4A,the films have been deposited.The results show that the thickness of the film decreases with the distance from the tube orifice,and the film with thickness of 210 nm can be deposited in the middle of the tube.Moreover,the structure of the film is very compact and the trend of transformation to amorphous state seems to appear.There is no porous and pit structure,and the grain is fine.The film-substrate adhesion and wear resistance show a slight variation at the different site of the tube.