Regulation of Metal Ion Charge State Distribution in HiPIMS Discharge and Its Mechanism on the Properties of Binary Nitride Films

To address the issues of process control in high-power pulsed magnetron sputtering （HiPIMS） technology relying on macroscopic parameter trial and error and the ambiguity of the underlying mechanisms, this study takes the ratio of metal ion concentrations in the plasma （M⁺/M²⁺） as the core control parameter. A plasma sampling mass spectrometer （PSM） is used to in-situ diagnose the plasma ion states of Cr-Al, Ti-Al, and Al-Si binary alloy targets during HiPIMS discharge. The regulation laws of power supply parameters on M⁺/M²⁺ are investigated. By combining film characterization, a quantitative correlation between power supply parameters, plasma ion states, film microstructure, and macroscopic properties is established, and the dominant elements in the binary systems are identified. The results show that power, frequency, and duty cycle of the power supply can continuously regulate （M⁺/M²⁺）. Reducing this ratio can enhance the high-energy ion bombardment effect, suppress columnar crystal growth, and promote film densification. In binary alloy systems, there is a dominant rule of low second ionization energy elements, with Cr and Ti being the dominant elements in the Cr-Al and Ti-Al systems, respectively, and their （M⁺/M²⁺） ratio determining the film structure and properties. For AlSiN films, due to the high ionization energy of Si and the good stability of the ion state, the film properties are significantly affected by chemical reactions and the precipitation of the Si₃N₄ phase. This study provides a precise control paradigm based on the internal state of the plasma for the preparation of high-performance nitride films by HiPIMS, promoting the development of the technology from empirical trial and error to mechanism-driven intelligent control.