Studies on the formation of microcrystalline silicon with PECVD under low and high working pressure

The formation of microcrystalline silicon films has been studied under both low and high pressures with plasma enhanced chemical vapor deposition (PEC VD). Under low pressure, the growth rate of films may be enhanced by increa sing the silane fraction in the reaction gas, or by increasing the input po wer density. However, both of these methods tend to inhibit the growth of m icrocrystalline films and promote the growth of amorphous phase. Under high pressure, the microcrystalline can be formed as the silane is depleted by increasing the power density. In this paper, the mechanism of microcrystall ine formation of the films has been analyzed based on the observations of t he optical emission intensities of H-alpha and Si* in the deposition plasma . It has also been found that the crystallinity near the interface between the deposited film and the substrate can be significantly improved for film s deposited under high pressure. (C) 2000 Elsevier Science S.A. All rights reserved.