OBSERVATION OF DUST PARTICLE GROWTH AND FALLOUT IN RF-EXCITED SILANE DISCHARGES

Particles formed during plasma enhanced chemical vapor deposition of a morphous silicon thin films which fall to the film surface, either dur ing or after the process, may have a severely deleterious effect on fi lm properties. In order to understand the mechanisms of particle forma tion and fallout we have investigated the growth and dynamics of parti cles in RF discharges in pure silane. The diameter of particles formed within the first 20 s of the discharge was investigated by electron m icroscopy of substrates with fallen out particles. Furthermore we used a He-Ne laser in combination with a diode array camera to measure tem porally and spatially resolved light scattering from particles and ded uced their sinking speed after switching off the discharge. The result s are compared to a theoretical model on the particle dynamics.