Effects of hydrogen dilution on electron density in multi-hollow discharges with magnetic field for A-Si:H film deposition
We have measured dependence of electron density n<inf>e</inf> on hydrogen dilution ratio R= [H<inf>2</inf>]/([SiH<inf>4</inf>]+[H<inf>2</inf>]) in the multi-hollow discharges with or without magnetic fields to obtain information about the deposition rate enhancement due to hydrogen dilution and applying the magnetic fields. The R dependence of the n<inf>e</inf> did not correlate with that of the deposition rate. The n<inf>e</inf> exponentially decreases with a distance from the discharges z. The n<inf>e</inf> decreases faster for higher R. These complicated behaviors of n<inf>e</inf> may be explained by electron attachment to the clusters generated in the SiH<inf>4</inf>+H<inf>2</inf> discharges. For R=0, the n<inf>e</inf> was almost same value regardless with or without magnetic fields. For R=1, n<inf>e</inf> with magnetic fields was 1/10 of that without magnetic fields. We also found that, for R=0, ne drastically decreased with increasing the z, while for R=1, ne showed a gradual decrease with z. The effects of applying magnetic fields on the deposition are unclear but applying the magnetic fields may affect the electron energy distribution.
Two-Dimensional Spatial Profile of Volume Fraction of Nanoparticles Incorporated Into a-Si:H Films Deposited by Plasma CVD
Using an optical-scanning method, we obtained 2-D spatial profile of deposition rate of hydrogenated amorphous silicon (a-Si:H) films deposited by a multihollow discharge plasma CVD with a high spatial resolution. From the profile, we deduced 2-D spatial profile of the volume fraction of nanoparticles incorporated into films, since nanoparticles affect optical and electronic properties of a-Si:H films.
Effects of Gas Temperature Gradient, Pulse Discharge Modulation, and Hydrogen Dilution on Particle Growth in Silane RF Discharges
The effects of gas temperature gradient, pulse discharge modulation, and hydrogen dilution on the growth of particles below about 10 nm in size in silane parallel-plate RF discharges are studied using a high-sensitivity photon-counting laser-light-scattering (PCLLS) method. Thermophoretic force due to the gas temperature gradient between the electrodes drives neutral particles above a few nm in size toward the cool RF electrode which is at room temperature. Pulse discharge modulation is much more effective in reducing the particle density when it is combined with the gas temperature gradient, and particles above a few nm in size cannot be detected by the PCLLS method even after 2 h. Hydrogen dilution of a high H2/SiH4 concentration ratio above about 5 is also useful in suppressing particle growth in the radical production region around the plasma/sheath boundary near the RF electrode.