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Nanocrystalline diamond (NCD) is exceptionally useful for a variety of applications and is of significant interest to researchers in technological and scientific fields due to its excellent mechanical and chemical properties, such as its hardness and high thermal conductivity. We have modified a microwave plasma chemical vapor deposition (MPCVD; Astex Inc.) system with a slot antenna designed for surface wave plasma (SWP) and successfully fabricated high quality thin NCD film. This SWP-CVD process fabricates high quality diamond film at 300 °C, while a normal MPCVD process requires the temperature of the substrate to be above 800 °C. We studied the fabricated NCD samples in detail, measuring their surface morphology by field emission scanning electron microscopy (FESEM); their structural-chemical properties by Raman spectroscopy; and their surface roughness by atomic force microscopy (AFM).

RF glow discharges are widely used in deposition, etching and surface treatments for semiconductor materials. Especially, roll-to-roll processing is necessary for flexible display or thin film solar cell modules. For a roll-to-roll thin film deposition processing, it is necessary to use cylindrical grounded electrode. The effects of electrode shapes on the plasma properties of capacitively coupled rf argon discharge at 13.56 MHz are investigated using self-consistent two-dimensional fluid simulation. The simulation model includes blocking capacitor and external circuit effects. Comprehensive analysis has been made in terms of time-varying current–voltage characteristic, spatial distributions of plasma density and ion current density on the substrate. The effects of applied voltage ( V f = 200 ∼ 800 [ V ] ) and gas pressure ( p = 0.5 ∼ 2 Torr ) on the plasma properties are also investigated. We found that flat electrode has a little bit higher impedance than that of cylindrical ground electrode. However the difference between the two configurations is less than 5% therefore we may conclude that the shape of grounded electrode does not significantly affect current–voltage characteristics of the discharge system. For roll-to-roll reactor version, displacement current come from dielectric layer between electrodes reaches more than 75% of total displacement current. Large displacement current results in degradation of power factor and matching circuit efficiency. For the cylindrical electrode, increasing electrode gap length along lateral direction makes that the location of peak electron density moves toward center of the reactor. The effect of the cylindrical electrode on the plasma spatial structure is reflected in the ion current density at substrate (dielectric layer) on grounded electrode. At low voltage and low power condition, about 90% of input power is consumed for electron heating. The efficiency decreases with increasing power and decreasing pressure as a consequence of increasing power to drive ion current. Electron heating efficiency decreased with pressure. The increase of pressure mainly reduces the diffusive component of the loss rate for both charged and neutral species.

A 2.45GHz microwave plasma source with a linear antenna has been developed for low temperature large scale deposition processing. Microwave power is transmitted through WR340 waveguide and a copper rod, linear antenna, is located in a quartz tube. The power matching is effectively achieved by a linear antenna is located at λ g /4 or 3λ g /4 from the end of WR340 waveguide. The Ar plasma was generated along the surface of quartz tube and a clear standing wave pattern with nearly 10cm wavelength was observed at Ar pressure of 200mTorr and 200W input power. The electron density and electron temperature were investigated by using the electrostatic probe. The electron density and electron temperature were highly measured near the surface of quartz tube. Ar plasma density along the quartz tube is mostly uniform despite standing wave set-up and antenna of long length. A uniform temperature was measured at 10~40cm distance from the end quartz tube and 5cm distance from the surface of quartz tube.