Variations in composition and structure occurring in multicomponent alloy targets during their service term

The composition and microstructure of the targets used in the magnetron sputtering (MP) method may change during its operation, especially if the target is a multicomponent alloy. Therefore, the information on the composition and microstructure of the sputtered region of the target, namely, the groove, which forms on the target over time, makes it possible to predict changes in the properties of the film. The targets for our experiments were fabricated from CoCrCuFeNi, CoCrCuFeMnNi and AlCoCrCuFeNiV high-entropy alloys (HEAs). Scanning electron microscopy (SEM) and chemical microanalysis were utilized to study the structure and composition of the grooves on the targets at the beginning and at the end of the targets service life. The results of the investigations allowed to derive the following conclusions: (1) signs of melting found on the surface of the grooves indicate to high temperatures arising on the targets during their sputtering; (2) a new type of preferential sputtering effect has been established, the main condition of which is the presence in the target composition of inclusions of a component whose sputtering coefficient is noticeably higher than that of the others; (3) the formation of a specific microrelief on the target surface is a consequence of the combined action of two factors: high temperature and sputtering.