Radial current distribution at a planar magnetron cathode

Abstract

Experiments and theory are used to investigate the radial distribution of current at the cathode of a cylindrically symmetric, planar magnetron discharge. We have developed a simple model of the distribution of incident ions at the cathode, in the form of an integral equation. Energetic electrons, produced by secondary electron emission when ions strike the cathode, are accelerated into the discharge through a thin sheath. The Hamiltonian motion of the energetic electrons in the magnetic field determines the birthplace of discharge ions, and thus, the distribution of ion current density at the cathode. The radial current distribution has been measured for various magnetic fields using a radially staggered array of sixteen 1-mm-diam current probes imbedded in a 9-in.-diam cathode. In agreement with the model, the current distribution is peaked at the radius at which the magnetic field is tangent to the cathode plate, and the width of the distribution scales as the square root of the energetic electron Larmor radius.

Electron drift and the loss balance of charged particles in planar-unbalanced dc magnetron discharge

“…6 The annular magnetic and axial electric fields which are generated within a sheath by the permanent magnets and a negative dc voltage of few hundreds or more applied to the cathode, respectively, induce an E ϫ B drift motion for electrons near the cathode surface. [6][7][8] The electrons trapped near the cathode by the transverse magnetic field hover below the cathode and are accelerated by the electron field. These electrons undergo a sufficient number of ionizing collisions to maintain the discharge.…”

Improvement of coating deposition and target erosion uniformity in rotating cylindrical magnetrons

“…Moreover, at the first groove the sputtering rate is higher at the upper cathode part, while at the second groove, it is higher at the lower cathode part. This cathode sputtering asymmetry is related to the drift electron motion over the cathode surface in the crossed electrical E and magnetic B fields~Wendt et al., 1988;Sheridan et al, 1990!. For a magnetic system with a north pole placed in the center, electrons drift in the direction indicated with the arrows in Fig.…”

Sputter Deposition Processes

“…1]. The current density at the cathode of a magnetron is peaked where the magnetic field lines are tangent to the surface of the cathode [62]. The current density at the cathode of a magnetron is peaked where the magnetic field lines are tangent to the surface of the cathode [62].…”