Optimization Design Of Planar Magnetron Sputtering Target And Analysis Of Film Thickness Uniformity

In the field of vacuum coating,magnetron sputtering is widely used in the manufacture of the various thin film due to its low sputtering temperature and high deposition rate,and plays an irreplaceable role in the field of science and industrial production.As a key part of sputtering coating equipment,the stability of the sputtering process and the uniformity of film layers is directly related to the magnetron sputtering target.However,there still exists many issues such as the uneven distribution of the horizontal magnetic field,the low heat exchange efficiency of cooling system,and the poor uniformity of film thickness in traditional sputtering target.Aiming at these problems,on the basis of the existing research,the optimization design and the film thickness analysis of the small circular planar magnetron sputtering target are carried out in this thesis,so that the performance of the target and film quality are improved,which makes a reference value and guiding significance for practical production.(1)Based on the sputtering deposition and plasma theory,two dimensional argon DC glow discharge model is established.The process of DC glow discharge is simulated by Comsol5.2.The spatial distribution of electrons and heavy particles with times variety are obtained,and the distribution rule of electric field and electric potential are obtained as the discharge becomes stable.Combined with the simulation results,the mechanism of discharge is discussed and analyzed,and the correctness of the model is verified theoretically,which makes a further understanding of sputtering coating principle.(2)Based on the traditional circular planar magnetron sputtering target structure,a double circular structure of magnetron sputtering target is designed.In order to obtain an ideal horizontal magnetic field distribution,the magnetic field is simulated by Comsol5.2,and the optimization model is designed by installing the FSS(ferromagnetic shunt shim).The results show that when the height of the inner magnet is 10 mm and the distance between the outer magnet and target is 7mm,the horizontal distribution of magnetic is the most uniform.Besides,by choosing a appropriate size of FSS and adjusting the distance between FSS to magnet,the uniformity of the horizontal magnetic field distribution can be significantly improved.(3)To ensure the stability of the sputtering process and the normal temperature of the target,according to the structural characteristics of the double circular magnetron sputtering target,a new cooling structure is designed.The heat exchange of cooling system is simulated by Fluent,by changing the cooling channel structure and the direction between inlet and outlet,the structure of cooling system is optimized.The simulation results show that the heat transfer effect of the plane structure is better than that of the serpentine cooling channel,and the effect of water turbulence can be greatly enhanced when the bump structure added on the target surface.For every kind of structure,the cooling channel condition can be greatly improved by increasing the water velocity of inlet.The temperature distribution of target surface is best when the inlet and outlet are in a relative parallel position and the cooling water flow along the tangential direction of chamber wall.(4)In order to produce the uniform film in large substrate with a small target,a new magnetron sputtering coating method is designed,in which the movement of target and rate of substrate are changed and controlled from fixed to removable,the new model contains a rotation substrate and a step-moving target.According to the correlation theories of magnetron sputtering,the mathematical model was set up.By using Matlab to simulate and calculate the film thickness,the conclusion can be drawn that the thickness uniformity of film is greatly affected by two important parameters: target stay time in every equidistant point and its moving step.The film thickness distribution is more uniform when target stay time changed in proportion to its scanning area at the rotating substrate,the deviation of film thickness gradually reduces as the target moving step decreases,and the uniformity of film thickness is best when the moving step is 5mm.