A spatially resolved spectroscopic study of ionization in the planar magnetron discharge

Abstract

Spatially resolved optical emission spectroscopy has been used to investigate the sputtering and ionization of titanium in a DC planar magnetron using argon as a sputtering gas. Maps of argon and titanium atomic and ionic emission have been obtained. Characteristic emission patterns have been identified and explained by the sputtering of atoms from the magnetron target and their subsequent ionization in the dense plasma at the magnetron target. The inverse Abel transformation was used to reconstruct plasma emission profiles, revealing that the non-uniform erosion profile at the magnetron target leads to a non-uniformity in plasma properties some distance into the discharge. An enhanced metal ionic content has been found in the plasma on the axis of symmetry of the discharge, and this has been explained by an enhanced lateral diffusion of metal ions arising from the change in momentum of sputtered metal during collisional ionization by metastable argon atoms.

A semi-quantitative model for the deposition rate in non-reactive high power pulsed magnetron sputtering

“…The sputtering process is initiated when Ar + ions with a current density j Ar + impinge on the target causing ejection (sputtering) of target atoms, M. A fraction of the species M is ionized close to the target and subsequently, a number of the M + ions are attracted back to the target with a current density j M + . In dcMS the target ion current consists mostly of Ar + species, due to the low ionization of the sputtered material [16], i.e.…”

The control of thin film deposition and recent developments in oxide film growth

“…Whilst the direct measurement of the energy of depositing species is a rather specialised technique, 34 in situ monitoring of the deposition environment is now often achieved using plasma characterisation methods such as optical emission or absorption spectroscopy. 33,35,36 The fabrication of complex multi-component materials, including the precise deposition of functional oxides, is currently being performed using a range of physical and chemistry-based techniques, and this article has described just a selection of these. MBE and PLD are specialised deposition methods which are contributing to advances in the understanding and development of film growth processes, as well as allowing the assessment of novel material structures, but they are limited by both cost and scalability issues.…”

“…4) and the measurement of particle energies. [33][34][35][36] Another technique for increasing control of the depositing flux is the addition of an independent ionisation source, for Fig. 4 Two-dimensional maps of spectral emission in front of a titanium planar magnetron target (the face of the target is at elevation = 0 mm): (a) Ti atomic emission, and (b) ionic emission, showing enhanced intensity (red/yellow) in the high density plasma regions corresponding to strongest magnetic field; (c) the ratio of ionic to atomic emission, with the region of highest relative ionisation pushed out in front of the target face.…”

“…4 Two-dimensional maps of spectral emission in front of a titanium planar magnetron target (the face of the target is at elevation = 0 mm): (a) Ti atomic emission, and (b) ionic emission, showing enhanced intensity (red/yellow) in the high density plasma regions corresponding to strongest magnetic field; (c) the ratio of ionic to atomic emission, with the region of highest relative ionisation pushed out in front of the target face. 35 example, a radio-frequency coil located between the sputtering target and substrates. 37 The energy and direction of ionised film species may then be controlled with an electrical bias at the substrates.…”

Electron transport in E x B devices

“…A linear profile would be a conservative estimate over an exponential profile, as the exponential profile would result in a greater correction to mobility measurements. Spatial ionization data in the similar geometry of a planar magnetron discharge shows a roughly linear relation between relative ionization and distance from the cathode (target) for the lowest pressures examined[143]. Although the low-pressure condition in the planar magnetron was higher than the pressures in the Hall Electron Mobility Gage, similar principles may apply as the pressure is further decreased in the planar magnetron discharge.…”