抄録
Generation and deposition of dust particles in plasma processes for thin film preparation often causes serious problems leading to yield reduction. A device capable of conveniently measuring the properties of particles suspended in plasma has therefore been needed. In the present work, a compact particle monitoring device based on light scattering is developed, and its performance is examined. This device irradiates suspended particles with laser light consisting of two different wavelengths, and determines the particle diameter from the intensity of scattered light. Preliminary experiments using monodisperse latex particles dispersed in water indicated that the relationship between the scattered light intensity and particle diameter was consistent with that predicted by the light scattering theory. The device was then applied to a plasma enhanced CVD chamber in which SiH4/H2 plasma is formed to fabricate Si thin film. As a result, particles generated and suspended in the plasma could be detected when the amount of particles were sufficient depending on particle size. The particle size determined by the monitoring device was in the range between 0.2 and 0.3 μm. This size was in satisfactory agreement with the size of the particles deposited on the film.
