SUBSTRATE EFFECTS FROM AN UNBALANCED MAGNETRON

The manipulation of the plasma of a d.c. planar magnetron may be achieved easily by adjusting the magnetic field of the magnetron, in conjunction with the placing of the anode. Such an arrangement of an "unbalanced" magnetron has been studied with regard to the bias voltage that appears on the substrate and the resultant ion and electron currents that flow to it. These are compared with the heat load experienced by it, which is related to the energy dissipation of the magnetron system. The magnetron source is considered from the point of view of providing energy bombardment of the substrate, and the growing film, and the efficacy of this bombardment in initiating structural and chemical reactions of the surface, as well as giving a heat load. A typical unbalanced magnetron, made by us, gave an insulated substrate a bias voltage of 25-30 V with an ion current of 3.4mA cm-2. The heat load was 100 mW cm-2. Of the energy supplied to the magnetron 82% went into the cooling water and 3% into the substrate; the rest was dissipated by the plasma.