Nanoparticles and plasmas

Nanoparticles can form via chemical nucleation from gas-phase species during plasma processing of silicon films. Nanoparticle-plasma interactions are studied by simulating finite-rate charging and transport of particle nuclei in a low-pressure processing plasma. Results show little change in electron temperature and concentration during the early stages of particle nucleation. However, the ion density profile changes drastically as ions accumulate near the reactor center. Increased ion concentration corresponds to the growing concentration of negatively charged particles, which are shown to have the highest production rate in the reactor center where they are trapped. A significant number of neutral particles are deposited on reactor walls or onto a deposition substrate by diffusion. Positively charged particles impact the substrate at low concentrations but with high energies, which may affect film morphology during plasma-enhanced chemical vapor deposition (PECVD).