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High power impulse magnetron sputtering (HiPIMS) discharge promises high ionization fraction and energetic ions in comparison with dc magnetron sputtering discharge. But acknowledge on the characteristics of HiPIMS plasma in the near-substrate region (substrate vicinity), which is of great importance for film deposition, is still limited. Here, optical emission spectroscopy (OES) combined with the collisional-radiative modelling are developed and used to determine the electron temperature and the number density of neutral sputtered atom for the chromium HiPIMS plasma in substrate vicinity. The OES analysis demonstrated the HiPIMS discharge of Cr sputtering process in low density mode was dominated by the electron impact ionization of argon atoms and excitation of chromium atoms. As the HiPIMS plasma in the substrate vicinity is far from the local thermal equilibrium state, the relative intensities of transition lines to ArI 4p states was used to calculate the electron temperature. Subsequently, the neutral chromium atoms density about 10(17) m(-3) was reported in the near-substrate region. Our findings have important implications for species generation in low density HiPIMS discharge, with applications in synthesis of dense chromium coatings., Funding Agencies|National Natural Science Foundation of ChinaNational Natural Science Foundation of China [11705258]; National Science and Technology Major Project [2017-VII-0012-0108]; Ningbo Science and Technology Innovation Project [2018B10014]

The temporal evolutions of target voltage and current waveforms under different pulse voltage and working pressure conditions were studied during Cr high power impulse magnetron sputtering discharges. Target voltage and current characteristics demonstrated that when the pulse width was set as 200 mu s, HiPIMS discharge went through a four-stage sequence during each pulse, Townsend discharge, glow discharge, afterglow, and pulse-off stages. A discharge state transition in the glow discharge stage happened at high pulse voltage and working pressure conditions. Furthermore, the dependence of reduced cathode fall thickness pdcon pulse voltage, working pressure, and normalized current density j/p(2) was presented. It was found that gas rarefaction leads to a change of relationship between pd(c) and j/p(2). A noticeable increase of the cathode fall thickness caused by gas rarefaction has been found. Published by AIP Publishing., Funding Agencies|National Natural Science Foundation of China [51522106, 5151101342]; State Key Project of Fundamental Research of China [2013CB632302, 2017YFB0702300]; Zhejiang Key Research and Development Program [2017C01001]