Investigation Of Preparation Process And Properties For Plasma Etching Resistant YF₃ Coating

With the rapid development of the semiconductor industry,plasma etching technology has gradually become one of the key processes for manufacturing semiconductor devices.However,the fluorine-containing plasma in the process of etching silicon wafers will also have serious etching effects on the components in the reaction chamber of the plasma etching machine,which will result in the generation of pollutants in the reaction chamber and reduce the yield of semiconductor products.A protective coating that is resistant to plasma etching is prepared on the surface of the parts that are used in the plasma environment,which can effectively slow down the etching damage of the parts.YF₃ coating is a new type of protective coating for plasma environment,which has high etching resistance in fluorine-containing plasma environment.In this paper,spherical YF₃ powder was used as the raw material,and the YF₃ coating was prepared on the surface of 6061 aluminum alloy by using atmospheric plasma spraying technology.The spraying process parameters of the coating were designed according to the orthogonal test method.The structure and properties of the coating under different process parameters were comparatively studied.The microstructure,etching rate,microhardness,bonding strength,dielectric strength of the coating were characterized by X-ray diffractometer,scanning electron microscope,3D profile measuring instrument,plasma etching machine and other experimental equipment.Moreover,the influence of process parameters on the performance of the coating was discussed,and the plasma etching behavior of the coating was analyzed.Conclusions are as follows:All YF₃ coatings prepared by atmospheric plasma spraying under different process parameters are polycrystalline,the main phase is YF₃ phase,and there are a small amount of Y₂O₃ and YOF phase at the same time.The coating is mainly formed by stacking dispersedly distributed flat particles and spherical particles,and there are some pores scattered on the surface of the coating.The surface roughness of the coating is different under different spraying process parameters.The maximum surface roughness of the coating is Sa9.842?m,and the minimum surface roughness is Sa4.374?m.All the coatings have obvious pore structure inside.The coating and the substrate are occluded with each other.Before the process optimization,there are a small amount of pores and microcracks in the local area of the bonding interface.The plasma etching resistance,microhardness,bonding strength and dielectric strength of the coating show a gradual decrease with the increase of its porosity.The order of the influence of spraying process parameters on the porosity of YF₃ coating is: hydrogen flow> spraying current> spraying distance> argon flow.The porosity first decreases and then increases with the increase of hydrogen flow,argon flow,and spray current,while the porosity gradually increases with the increase of the spraying distance.The optimized spraying process parameters obtained under the experimental conditions are as follows: the hydrogen flow rate is 6NLPM,the argon flow rate is40 NLPM,the spraying current is 500 A,and the spraying distance is 110 mm.Compared with the process before optimized,the internal pores of the YF₃ coating prepared by the optimized spraying process parameters were significantly reduced,and the bonding between the coating and the substrate became closer,and no obvious microcracks appeared at the interface.The porosity,etching rate,microhardness,bonding strength and dielectric strength of the coating have been significantly improved.After the YF₃ coating was etched for 600 minutes in a plasma environment with an etching gas of CF4/Ar/O₂,the surface roughness of the coating is significantly increased compared with that before the etching,and the etching traces are very obvious.In the plasma etching process of the coating,the edges of the original holes,grain boundaries and local weak areas on the surface of the coating are etched first.After the grain boundary and the local weak area are etched,there will be etch pits and etching lines.The size of the original holes,etched pits,and etched lines will gradually expand from their edges as the etching progresses,and their edges will eventually extend to the entire coating surface,so that the entire outer surface of the coating will be etched.With the increase of etching time,the material on the coating surface is removed layer by layer,and the etching depth of the coating is gradually increased.