Effect of gas pressure on ion energy at substrate side of Ag target radio-frequency and very-high-frequency magnetron sputtering discharge

Abstract

The effect of gas pressure on ion energy distribution at the substrate side of Ag target radio-frequency (RF) and very-high-frequency (VHF) magnetron sputtering discharge was investigated. At the lower pressure, the evolution of maximum ion energy (E) with the discharge voltage (V) varied with the excitation frequency, due to the joint contribution of the ion generation in the bulk plasma and the ion movement across the sheath related to the ion transit sheath time τi and RF period RF. At the higher pressure, the evolution of E-V relationships do not vary with the excitation frequency, due to the balance between the energy lost through collisions and the energy gained by acceleration in the electric field. Therefore, for the RF and VHF magnetron discharge, the lower gas pressure can have a clear influence on the E-V relationship.