Silicon deposition in diode and hollow-cathode systems

Deposition of silicon from silane discharges is studied in diode and hollow‐cathode systems. Using the single‐target (‘‘diode’’) configuration as a reference, it is shown that discharge confinement results in substantial increases in deposition rate and efficiency. The ‘‘target‐confined hollow cathode’’ exhibits the best performance; in comparison with a diode discharge at 2‐Pa silane pressure, rates are 20–50× higher at fixed applied rf voltage and 5× higher at fixed input power density. Alternatively, for a fixed deposition rate this new configuration allows the applied rf voltage to be reduced by ∼10 and the power density to be reduced by ∼20, again at a 2‐Pa pressure. Planarizing films are obtained at low pressures and/or low gas flows, while high pressures yield more directional deposition over surface steps. Good agreement with this profile study, and with our deposition rate data, is given by a model wherein ion bombardment is the dominant film forming and etching mechanism at low pressures, and wh...