Optimization And Discharge Analysis Of High-power Pulsed Magnetron Sputtering Based On Physical Simulation

High-power pulsed magnetron sputtering?HiPIMS?is a new magnetron sputtering technique which can produce high energy and high density plasmas by applying high power pulses with low duty ratio on the magnetron target.Due to its high ionization rate of the sputtering materials,the coatings prepared by HiPIMS have a good performance such as large density,high adhesion and nice mechanical properties.However,HiPIMS has some intrinsic disadvantages such as the low deposition rate,unstable discharge,and different ionization rates for different materials thereby hampering its wider industrial adoption.Based on the basic physical principles,this work proposed a new type of cathode structure in which the HiPIMS discharge is enhanced by the hollow cathode effect.Particle-in-cell/Monte Carlo Collision model was used to verify the enhancement of the hollow cathode effect.In order to improve the deposition rate,an electromagnetic control scheme was proposed to constrain the ion beam,and the plasma diffusion model was established to calculate the plasma transport.The simulation results reveal that electromagnetic control can effectively reduce plasma loss,control coating components and improve deposition rate.The HiPIMS discharge on a Cr target in N2/Ar was analyzed by a hollow cathode effect modified time-dependent global model,indicating an asynchronous discharge phenomenon of different particles and its effect on the particle density evolution curves.To verify the accuracy of the simulation,high-precision and time-resolved spectrometry?2 ns?was utilized to monitor the evolution of typical particles with time,and experiment results were consistent with the simulation.The specific conclusions are as follows:1.The hollow cathode effect can enhance the discharge,so that the HiPIMS discharge in the cylindrical cathode is strong and stable,the plasma density reaches 10²⁰m^-3,which is one order of magnitude higher than the ordinary plane cathode.The ionization rate and ion return probability increase by about 3.0%and 4.3%,respectively.The magnetic field enables farther diffusion of ions than atoms,resulting in a high percentage ion deposition on the substrate.2.The plasma transport path is controlled by extraneous electromagnetic coils.The transport simulation results show that effective electromagnetic control can adjust the plasma discharge,control the focusing degree of the plasma beam,reduce the ion diffusion loss,and improve the ion deposition rate by an order of magnitude.Different ions show different distribution.The uniformity of coating and the selectivity of deposition particles can be realized by controlling magnetic field according to requirements.3.A hollow cathode effect modified time-dependent global model was established to simulate the HiPIMS discharge of N₂/Ar/Cr system.The simulation results reveal particles(Ar,Ar⁺,Ar^m,Ar^H,N,N₂,N₂^m,N₂⁺,N⁺,Cr,Cr⁺,Cr²⁺,etc.)appear successively,resulting in an asynchronous discharge phenomenon.The reason is that the gas discharge depends on the reaction energy of particles and the metal discharge depends on the sequence of the physical processes.A series of inflection points corresponding to different physical processes including excitation,sputtering,ionization and diffusion are observed from the particle density evolution curves.