Effect of radio-frequency substrate bias on ion properties and sputtering behavior of 2 MHz magnetron sputtering

The effect of radio-frequency substrate bias on ion properties and sputtering behavior of 2 MHz magnetron discharge was investigated. The ion velocity distribution function (IVDF), the maximum ion energy and ion flux density were measured at the substrate by a retarding field energy analyzer. The sputtering behavior was investigated by the electric characteristics of target and bias discharges using voltage–current probe technique. It was found that the substrate bias led to the decrease of sputtering power, voltage and current with the amplitude <7.5%. The substrate bias also led to the broadening of IVDFs and the increase of ion flux density, made the energy divergent of ions impacting the substrate. This effect was further enhanced by increasing bias power and reducing discharge pressure.