This paper describes a technique for depositing insulating layers, onto suitable substrates, by the mechanism of sputtering in a radio-frequency excited discharge. The sputtering equipment and vacuum system have been designed so that facilities were available for the direct comparison of three different methods of sustaining a glow discharge at low pressures: 1. 1 By using a two-electrode Penning system (Diode); 2. 2 By means of a hot cathode discharge (Triode); 3. 3 By means of a second RF coil coupling inductively directly into the gas (Double RF). Deposition rates of a barium-alumino silicate glass, as a function of dc power input for the three methods of sputtering mentioned, are given. It is shown that high rates of deposition can be achieved using the double-RF system, i.e. rates in the region of 6.6 × 10-10 m.S-1 (400Å/min) have been obtained for a dc power input of approximately 800 watts. Deposition rates were also investigated over a range of Argon/oxygen mixtures. A detailed examination of the electrical properties of sputtered barium-alumino-silicate glass thin film capacitors has been made by sandwiching the dielectric layers between vacuum-deposited aluminium electrodes. Measurements of permittivity (6.15-6.4), tan δ (0.0017), dielectric strength (3×106 V.cm-1), resistivity (≈1015ωcm), and temperature coefficients of capacitance (120 ppm/°C over the ranges 25°-150°C and 100 Hz-100kHz) were found to compare closely with that of the bulk material. © 1968.
