Effects of gas flow on particle growth in silane RF discharges

The effects of gas flow on particle growth in silane RF discharges in a plasma chemical vapor deposition (PCVD) reactor with a shower-type powered electrode are studied using an in situ two-dimensional polarization-sensitive laser-light-scattering method. Particle growth depends on both the production of short-lifetime radicals and the loss of neutral clusters in the radical production region around the plasma/sheath boundary near the powered electrode. Gas flow of a velocity above about 6 cm/s is effective in suppressing particle growth because of increase in loss of neutral clusters. Moreover, particles larger than 120 nm in size that flow to the plasma/sheath boundary near the grounded electrode are found to pass through the sheath. This implies that such particles may deposit on film surfaces for PCVD reactors with the shower-type powered electrode.