Energy distribution function of substrate incident negative ions in DC magnetron sputtering of metal-doped ZnO target measured by magnetized retarding field energy analyzer*

In planar magnetron sputtering deposition using oxide targets, there is a problem of film composition and crystallinity degradation on the substrate surface opposite the target erosion region. This is believed to be due to the incident of high-energy particles emitted from the erosion zone of the oxide target onto the opposite substrate, but the details have not yet been clarified. Thus, it is extremely important to measure the energy distribution function (EDF) of the charged particles.

While several examples have been reported in the past of the detection of negative ions from sputtering targets using large, expensive energy-resolved mass spectrometers that require differential pumping, few have used the compact, inexpensive, and highly mobile retarding field energy analyzer (RFEA). RFEA by itself cannot separate the incoming fluxes of electrons and negative ions. However, an orthogonal magnetic field region of several hundred gauss above the RFEA injection aperture can suppress the inflow of electrons into the RFEA and measure the EDF of negative ions. In this paper, we report the results of charged-particle EDF measurements with magnetized RFEA during DC magnetron sputtering (DCMS) of metal-doped ZnO targets.