TREATMENT OF DUST PARTICLES IN AN RF PLASMA MONITORED BY MIE SCATTERING ROTATING COMPENSATOR ELLIPSOMETRY

Micrometer size particles can be processed by trapping them in a low p ressure radio-frequency (RF) plasma. Their size can be influenced by e tching or deposition. Mie scattering ellipsometry has been applied to monitor the particle properties during the plasma processing. Using th is diagnostic, in which the polarization of light is modulated by mean s of a rotating compensator, the size and the size distribution of a c loud of particles are measured. The 5 mu m particles, made of melamine -formaldehyde (MF) have been etched in an oxygen plasma. The experimen tal data have been fitted with a numerical model. The results indicate that the average size of the particles decreases and that the etching rate is 1.1 Angstrom s(-1). At the same time, the dispersion of the p article size increases.