Simulation And Optimization Of Film Thickness Uniformity In Physical Vapor Deposition

Physical vapor deposition(PVD)system is widely used in the preparation of optical films due to its good repeatability,low production cost and high surface quality.The thin film thickness uniformity is an important index to measure the quality of the film.Its advantages and disadvantages seriously affect the performance of the optical film.How to effectively control the film thickness uniformity has become a technical difficulty in the physical vapor deposition system.In this paper,the uniformity of film thickness in PVD system is studied,which provides theoretical basis and technical support for the improvement of film uniformity and the development of thin film deposition equipment.Based on the cosine and non-cosine theorems,the emission characteristics of point source,surface source,extended source,virtual source and sputtering source were studied to determine the film thickness distribution model of evaporation source and sputtering source:The evaporation source obeys the distribution of cosn?,and the sputtering source obeys the distribution of cosn(?+?0).By establishing precise mathematical and physical models,the relative film thickness distribution of evaporation source and sputtering source was simulated,and the influence of the geometric configuration of the mask and equipment on the uniformity of film thickness distribution was investigated.A new film thickness uniformity simulation program was developed using Mathcad programming.The simulation results were compared with the thickness distribution theory and experimental results,and the agreement was very good.The correctness of the software program was verified.The simulation program was optimized according to the actual situation,and the function of adjusting the uniformity of the ion assisted deposition(IAD)film thickness was added in the program,and the short wave pass multilayer film was deposited on the K9 substrate to control the film thickness uniformity within 1%.In addition,factors affecting the uniformity of the film thickness such as substrate tilt,vacuum degree,temperature unevenness and the like were analyzed and an improved method was proposed.Finally,the software was used to correct the uniformity of different structure deposition systems.The automatically designed mask could quickly solve the problem of uniformity of film thickness which reduced the film thickness unevenness of the rotating planar system from 30.7%to 0.89%,the film thickness unevenness of the rotating spherical system increased from 15.4%to 0.58%,the film thickness unevenness of the planetary system increased from 4.5%to 0.26%,and the film thickness unevenness of the rotary drum sputtering system from 5.3%to 0.74%.It satisfied the requirement of uniformity of film thickness for large-area high-precision optical films.