Study On The Component Uniformity Of Composite Film Deposited By Two Co-Sputtering Targets System In The Vacuum Coating Field

With the development of coating technology, the composite films consisted of a variety of component elements have been widely deposited because it has the incomparable physical and chemical properties to the single component film.Because it has the incomparable physical and chemical properties to the single component film.Through independently regulating the working current of two targets, the sputtering rates are changed, and can conveniently change two kinds of material composition ratio in the coating. It is benefit for the experiment research of the relationship between the composition and coating properties.Through increase gradually sputtering rate of one target,while decrease gradually sputtering rate of the other, gradient films which two kinds of component proportion uniform transition still could be prepared.The co-sputtering by two or more targets has become the main technical method for preparing the composite film with binary or complex elements. Different elements of distribution uniformity and controllability in multiple membrane are of vital importance to coating performance,should pay a special attention.It is used especially in the case of depositing the gradient film in which the ratio of two components changes uniformly and gradually along the thickness direction,testing the suitable ratio of different components in the composite film,optimizing the film performance,and so on.The uniformity and controllability of different element distribution in the composite film directly affects the film performance.Therefore,the distribution uniformity and controllability of co-sputtering system should be studied further.In the coating film prepared by the co-sputtering system with two targets, in this paper, the co-sputtering method by two or more targets has been widely used for coating the composite film consisted of a variety of component elements. In this paper, a typical co-sputtering system is studied which composes the twin round planar magnetron sputtering targets settled symmetrically and slantways towards a single flat substrate with self-rotation. The mathematical models which two co-sputtering targets off-Y-axis rotation substrate and two co-sputtering targets off Y-axis and Y-axis rotation substrate are established, respectively. Models are set up to describe the non-dimensional geometric relationship between the substrate and sputtering circles on two target surfaces. The relationship between film characteristics and the structural parameters of co-sputtering system (distance of the substrate-to-target h symmetrical eccentricity e, translation length d and obliquity angle of targetα) is described quantificationally. Some of calculating examples are given by use of MATLAB program.And it analyze the structural parameters of the co-sputtering system and optimize structural parameters by comparing the calculating results in order to obtain the uniform film.Sputtering film layer of twin co-sputtering target system is actually simply the addition of two magnetron sputtering targets.The film thickness distribution,is essentially determined separately by emission characteristics of two magnetron targets and relatively geometric structure parameters of the target-substrate system. Besides these, the film thickness distribution on the substrate is completely equivalent to target deposition rate distribution on the substrate.Therefore, according to the model above, the absolute and relative deposition rates of the target materials at different position of the substrate, root-mean-square deviation of relative deposition rates, as well as material utilization ratio of the magnetron sputtering target, can be given.According to the calculation mentioned above, during the co-sputtering process by two or more targets, there is component difference in the film at the different depth in the film thickness direction.The ratio of two components changes periodically along thickness direction in the film, i.e., there is the micro non-uniformity of the component distribution. For every point on the rotational substrate, the depositing process is a alternate growth process of two components. At the beginning, the depositing rate of one component is the maximum while the other is the minimum. Then, the former will decrease gradually till it reaches the minimum, as well as the later will increase gradually till it reaches the maximum. Afterwards, the former begins to increase same way till it reaches the maximum again, along with the later decreasing to the minimum. Thus, a period of the depositing process is finished which corresponds to the substrate rotating a round cycle.According to the result of theoretical study, a optimized group of structure parameters which can get good the film thickness distribution and the local component uniformity was selected as an object of study to experiment.And the samples were analysed by energy dispersive spectrum (EDS),and the calculated results are in good agreement with the experimental ones.Through the research and analysis for the component uniformity of composite film, in the process of manufacturing the composite powder materials, some of the chamical compenents are difficult to mix with each other. Aiming to this problem, a new method and mating equipment of manufacturing the composite powder materials is introduced which can make any two (or multi) kinds of compenents mixing in nanoscale based on the co-depositing technology of two (or more) vaporization sources.