Preparation And Properties Of Zr-Co-Ce Getter Films

With the development trend of miniaturization and integration of MEMS devices,maintaining the vacuum quality inside the microvacuum devices has become a common technical problem in the industry.The thin film getter material can realize the long-term passive maintenance of the micro vacuum environment,and its effective integration in vacuum packaging is the latest development direction of the current high-end micro device system package.The application of thin film getter material can effectively improve the reliability and service life of the micro device.Zr-Co-RE getter film is one of the most promising materials for the vacuum packaging in microsystems.On the basis of the previous work of our research group,we deposited Zr-Co-Ce getter films on Si wafers by magnetron sputtering.In the process,we studied the effect of key process parameters on the microstructure and sorption properties of the films,and explored the effective way to optimize the sorption properties of thin films from the perspective of optimal design of the layer structure,at the same time,developed a method of patterning deposited Zr-Co-Ce getter films based on ultraviolet lithography.The micro structure and morphology of Zr-Co-Ce thin films were characterized and analyzed by SEM,AFM,XPS,etc,and the sorption properties of the films were tested by dynamic method.The main conclusions of the research work are as follows:(1)The Zr-Co-Ce getter film are prepared by controlling the process parameters of the magnetron sputtering method.,such as sputtering gas pressure,sputtering power,background vacuum,and target substrate distance,when the background vacuum reaches 2×10-4 Pa,the sputtering gas pressure is 4 Pa,the sputtering power is 120 W,and the target base distance is 75 mm,the obtained film has a uniform and continuous porous columnar structure,with a large number of interfaces and gaps distributed between tissues,the grain boundary consistency is well,and the film surface shows a cauliflower-like appearance.The prepared films also exhibit relatively better sorption properties,its initial sorption rate was 71.3 cm3·s-1 ·cm-2,and total sorption capacity in 2 hours reached 116.9 Pa·cm3·cm-2.(2)The pre-deposited dense barrier layer on the surface of the substrate can effectively reduce the poisoning effect caused by the residual gas on the substrate,and at the same time,it is also favorable for adjusting the microstructure of the getter film to obtain a better sorption performance.The Pd,Pt,and Au protective layers deposited on the surface of the thin film can effectively avoid the oxidation caused by the open surface of the bulk layer exposed to the atmosphere for a long time.Zr and Co on the surface of Zr-Co-Ce film containing Pd protective layer mainly exist in the form of active metal state.At the same time,due to the selective transmission characteristics of Pd to H,the adsorption and dissociation of H on the surface of the thin film are facilitated,so that the sorption properties of the gettering film is significantly improved.(3)The pattern deposition of the Zr-Co-Ce getter film was realized based on the UV lithography method,however,the organic solvent used in the process of accurately depositing the thin film may cause carbide residue on the surface of the thin film,which affects the adsorption of the reactive gas on the surface of the thin film,resulting in a drastic decrease of the gas suction performance of the thin film.The effect of surface cleaning of the getter film can be achieved by Ar+ ion bombardment treatment,and the sorption properties of the film are obviously recovered.