Plasma diagnostics of magnetic field assisted ionized magnetron sputtering

Abstract

The effects of an axially applied axial magnetic field on ionized magnetron sputtering with an internal inductively coupled plasma (ICP) antenna were diagnosed with a Langmuir probe, an impedance probe, and optical emission spectroscopy (OES) to find an operation regime for low energy ionized deposition for low defect density films. A very weak axial magnetic field (Bz) of 20 G was found to reduce plasma potentials by 45% while keeping the ion current density at 80% of the value without Bz. Also based on OES measurements, the plasma density was increased by three times with 5 G of Bz but the coil sputtering was markedly reduced by increasing Bz. However, the radial uniformity of ion saturation current with Bz was about 2.5%–10.4% which was less than the 1.3%–5.5% observed without Bz (std. dev./avg.×100%). However, when the substrate was moved close to ICP coil by 1 cm from 5 cm above the ICP antenna, the radial uniformity was improved to 0.9%–5%, which is thought to be due to a balance between E-mode and H-mode discharge.