Novel approach to produce polymerized hydrocarbon coatings using dielectric barrier controlled atmospheric pressure glow discharge plasma

Abstract

Conventionally, low-pressure ͑Ͻ1 Torr͒ electrical discharges are used for material processing and thin-film deposition. These schemes suffer mainly due to the high cost of equipment and the complexity of operations. The atmospheric pressure glow discharge plasma is developed using a threaded styled electrode in different configurations, and these reactors are used to produce plasma polymerized coatings, required on plane substrates as self-supporting films to obtain membranes for blocking holes in cavities, and on microballoon targets, which are used as fuel containers for inertial confinement fusion, to avoid DT gas permeation. Helium gas is used as the supporting gas for formation and stabilization of atmospheric pressure glow discharge plasma reactors. Ethylene and acetylene gases are used as monomers to produce plasma polymerized hydrocarbon films. These films are characterized using scanning electron microscopy. Plasma polymerized coatings of thickness 100 nm-10 m with a smooth surface finish ͑rmsϽ100 nm͒ are deposited successfully. The surface finish is further improved using a postdischarge configuration. Preliminary results are very encouraging but further progress is to be made in this area. We are also planning to extend this technique for C:H coating of microballoons, which are used as fuel containers in inertial confinement fusion.

Effect of C2H4/N2 Ratio in an Atmospheric Pressure Dielectric Barrier Discharge on the Plasma Deposition of Hydrogenated Amorphous Carbon-Nitride Films (a-C:N:H)

“…It is thus believed that here, the atmospheric pressure deposition process was limited by the diffusion which ultimately caused this cauliflower-like coating. Acetylene and ethylene in a helium DBD were shown to display a similar cauliflower-like coating in the discharge [63].…”

Atmospheric Pressure Low Temperature Direct Plasma Technology: Status and Challenges for Thin Film Deposition

“…A critical point when using a PECVD process at atmospheric pressure is dust formation 3, 31, 43, 106, 109, 115–117. Hence, an important variable to be considered when designing the process is the balance between homogeneous growth in the plasma phase (which finally results in the formation of powders) and heterogeneous growth at the surface.…”

“…As this balance depends strongly on the partial pressure of the reactive gases, it is always possible to inhibit the dust formation by decreasing the precursor partial pressure 118. However, as this results in an important decrease of the growth rate,31, 115 complementary strategies have been developed, as it will be described in Section 5.3.…”

Growth process of hydrogenated amorphous carbon films synthesized by atmospheric pressure plasma enhanced CVD using nitrogen and helium as a dilution gas

“…Mishra et al reported that many particles were observed on amorphous carbon films synthesized by AP-PECVD and that the smooth surface finish is incompatible with high deposition rates. 26) In this study, the a-C:H films with a smooth surface were obtained by changing the pulse frequency. The comparison of the films synthesized at 10 and 5 kHz showed that the growth of the particles was prevented by lowering the pulse frequency.…”