METHOD AND APPARATUS FOR DEPOSITING SEMICONDUCTOR AND OTHER FILMS

It is known to deposit films by decomposition of a gas in a glow discharge, e.g. silane is decomposed to deposit amorphous silicon a substrate. The invention improves the uniformity of deposition by shaping the electrode 2 bearing the substrate and the counter electrode 4 to provide a non-uniform electric field with a weak field over the substrate and a more remote strong field. The gas pressure is adjusted to stabilize the glow discharge P in the weak field region; the discharge spreads all over this region but is excluded from the strong field region, ie. gap d. Alternative embodiments have a counter electrode formed by an array of pins facing the substrate electrode or two back-to-back substrate electrodes with substrates on their outer surfaces. The strong field is then round the edges of the electrodes and AC energization is employed. The invention is suitable for making multi-layer semiconductor devices, e.g. Schottky barrier devices and solar cell devices.