ELECTRON-DISTRIBUTION FUNCTIONS IN A SPUTTERING MAGNETRON DISCHARGE

The electron distribution function g (v(z)) in a cylindrically symmetr ic, planar, sputtering magnetron has been characterized using a one-si ded, planar Langmuir probe. Measurements were made above the magnetic trap at six radial locations in the direction normal to the cathode. T he distribution function is found to be non-Maxwellian, with a shape t hat depends sensitively on radial position. Near the symmetry axis, g (v(z)) is anisotropic and exhibits a strong electron drift from the ca thode to the anode. Off axis, g (v(z)) is nearly symmetric and has two components: a dense, cold Maxwellian component, and a tenuous, energe tic shell component.