The use of Very High Frequency (VHF) glow discharge for the deposition of amorphous silicon films is one approach to influencing the deposition conditions.
For the experiments a capacitatively-coupled parallel plate reactor with two aluminium electrodes of 125 mm in diameter is used. The VHF is generated by means of an all-solid state amplifier which has a frequency response ranging from 250 kHz to 150 MHz. Experiments with an nitrogen discharge within the range from 5 to 150 MHz are an principle in agreement with the results in the literature. The results show, that the frequency dependence of the discharge strongly depends on the design and the external electrical connection of the VHF-reactor. In the examined range of frequency resonances appear, which are probably responsible for the maximum of the deposition rate. These resonances are not essentially resultant from changes in the physics of the discharge but a result of the reactor construction and the external electrical connection. Possibilities which influence this frequencies of resonance will be discussed.
Results for an electrical network model will be discussed in the comparison with different reactors and the optimization of the behaviour of the deposition process.