Papers

ICMCTF2005 Session G3: Atmospheric Plasma, Hollow Cathode and Hybrid Plasma Processing

Thursday, May 5, 2005 2:50 PM in Room California

Thursday Afternoon

Start	Invited?	Item
2:50 PM		G3-5 Atmospheric Pressure Plasma Deposition of Thin Films with a Townsend Discharge at Atmospheric Pressure F. Massines (CNRS - LGET UPS-CNRS, France); N. Gherardi (LGET-CNRS, France) The development of a PECVD process working at atmospheric pressure and allowing an easy on-line treatment is a challenge of great interest. Dielectric Barrier Discharge (DBD) is the most suitable plasma generation mode for roll to roll processing of polymers thin film, fabrics, glass plate, etc.¦: it is cold, robust and not disturbed by the movement of the substrate. Moreover, the conditions to get a homogeneous DBD are now widely known and easy to up-scale in one direction allowing to get a uniform plasma band of several meters in the direction perpendicular to that of the substrate movement. At atmospheric pressure, the reactive gases leading to the coating formation are diluted in a main gas, which is usually helium, argon or nitrogen. In nitrogen, the homogeneous discharge is a Townsend discharge. In this presentation, first the physics of the Townsend discharge will be quickly discussed to (i) explain the experimental conditions which have to be fulfilled to get the Atmospheric Pressure Townsend Discharge and (ii) present the nature and density of the energetic species at the origin of the dissociation of the chemical vapours. Then silicon oxide thin film properties obtained with SiH4 or hexamethyldisiloxane (HMDSO) diluted in N2/N2O mixtures will be compared in terms of chemical composition, density, growth rate and structure. The contribution of homogeneous and heterogeneous growth will be separated. The kinetic of these two mechanisms will be discussed paying attention to particles growth and transport.}
3:30 PM		G3-7 The Effect of N₂ Flow Rate in He/O₂/N₂ on the Characteristics of Large Area Pin-To-Plate Dielectric Barrier Discharge Y.H. Lee, S.J Kyung, G.Y. Yeom (Sungkyunkwan University, South Korea) Atmospheric pressure plasmas are currently applied to various processes such as air purification process, surface modification process for hydrophilic or hydrophobic properties, germ killing process, etc. Also, for the semiconductor and flat panel display processing, atmospheric pressure plasmas are studied as the replacement of wet cleaning processing to resolve environmental pollution due to the large quantity of liquid waste producing during wet cleaning, to cut down the operating cost such as chemical cost, to automize the process, etc. For these purposes, among the various atmospheric pressure plasma equipments, the plasma equipments that can generate uniform glow discharges such as dielectric barrier discharge(DBD), capillary electrode discharge(CED), microwave discharge, plasma jet, and hollow cathode discharge, are more widely investigated. In this study, the effects of N₂ flow rate in the He/O₂/N₂ gas mixture on the characteristics of a pin-to-plate DBD having the size of 100mmx1000mm have been investigated for the application to flat panel display processing such as photoresist ashing. The pin-to-plate DBD showed about 70~120% higher photoresist ashing rate at the same applied voltage compared to the conventional DBD. The addition of 3slm of N₂ to He(10slm)/O₂(3slm) showed the highest photoresist ashing rate of about 580nm/min for the pin-to-plate DBD at 12kV of AC voltage. The increase of N₂ flow rate in He/ O₂ gas mixture up to 3slm appeared to increase the density of N₂⁺ ions and N₂ metastables while the oxygen atomic density appeared to decrease continuously. The increase of photoresist ashing rate with the increase of N₂ flow rate up to 3slm was related to the increase of the substrate surface temperature by the increased collision of N₂⁺ ions and N₂ metastables with the substrate.
3:50 PM		G3-8 Atmospheric Pressure Plasma CVD and Plasma Chemical Etching for High Throughput Processing of Parts V. Hopfe (Fraunhofer IWS, Germany) Plasma CVD at atmospheric pressure provide a unique combination of advantages with respect on both economic and technological factors. Plasma activation substantially widen out range of potential applications against conventional thermal CVD because of capability for processing of temperature sensitive substrates, e.g. steel, lightweight metals, pre-shaped glass, plastics. Furthermore a much wider range of layer materials can be deposited. Potential cost saving factors are linked to in-line processing capability, increased throughput and decrease of capital cost. At Fraunhofer IWS currently two methods for atmospheric pressure processing are under development, microwave CVD and DC ArcJet-CVD based on a linearly extended plasma source. All kinds of AP-PECVD reactors are designed for continuous air-to-air processing on flat or slightly shaped substrates. The reactors operate in a remote plasma mode being imperative for long term stability of the coater head. Supported by extensive fluid dynamic modelling a gas flow system has been designed which effectively balance out the three main factors being critical for process performance: (i) throughput / high deposition rate, (ii) avoid / control powder formation, and (iii) avoid stray deposition on reactor walls. Deposition rates are in the range of 5 â?" 100 nm/s (static) and up to 2.0 nm*m/s (dynamic). By changing plasma conditions the reactors can be used for plasmachemical etching. Again etching rates above 100 nm/s can be achieved, e.g. on silicon. Developments are underway to explore the use the innovative coating technology for e.g. scratch resistant coatings on metals, barrier layers, self-clean functional surfaces and, for antireflective coatings. Coating materials range comprise: silica, titania, carbon and silicon nitride. Layer characterisation demonstrate that both composition/structure and optical/mechanical properties are close to data being well known from low pressure PECVD.}
4:50 PM		G3-11 Effect of Ferromagnetic Substrates on the Film Growth in Magnetized Plasma Systems L-E. Gustavsson, H. Baránková, L. Bárdos (Uppsala University, Sweden) We found substantial differences in TiN films on austenite and martensite steel substrates. The films were grown by the reactive PVD in a magnetized linear hollow cathode plasma as well as in a hybrid hollow cathode and microwave ECR plasma system. A detailed study shows that martensite steel substrates can, depending on their position and shape, deform the magnetic field of the plasma PVD source. The substrate can create certain kind of "bypass" channel for magnetic field lines causing deflection of charged particles towards the substrate surface. This may lead to considerable enhancement of the particle bombardment of the surface. Enhanced ion bombardment of the martensite steel substrate at ground potential often leads to granulated or damaged TiN films contrary to good quality TiN films grown on austenitic steel substrates at identical conditions. It was also found that the substrate bias could compensate this effect at considerable extent. Results of the relevant experimental study are discussed. Although the observed effect is of particular importance for very high-density plasmas generated by the magnetized hollow cathodes, it might affect the film growth even in conventional magnetron sputtering systems.
5:10 PM		G3-12 Characterization of Hot Wall Grown 1,4 -Hydroxy-9,10-Anthraquinone Films for Device Applications A. Mahajan (D. A. V. College, India); R.K. Bedi, H. Gupta (Guru Nanak Dev University, India) 1,4-Dihydroxy-9,10-anthraquinone films has been grown by hot wall technique onto the glass substrates kept at different temperatures in a vacuum of 1.3c 10-3 Pa. These films are characterized by NMR, optical absorption (IR, visible, near-UV), X-ray diffraction and scanning electron microscopy. Besides these, the electrical properties of the films are determined in the temperature range 290-370 K. SEM micrographs of 1,4-dihydroxy-9,10-anthraquinone films show that the films are composed of well defined and uniformly distributed crystallites with preferred orientation nearly perpendicular to the plane of the substrate. Crystallites as large as 7µm are observed in the case of films deposited at 348K. The X-ray diffraction pattern of these films show crystalline behaviour of films. The films deposited at higher substrate temperature suggest the formation of more ordered and crystalline films. Analysis of optical absorption measurements indicate that both direct and indirect transitions are involved in the absorption process and corresponding interband transition energies of films lie in the range 1.80 -2.40 eV. The current-voltage characteristics of films show ohmic behaviour of conduction within the investigated field and temperature range (10-60 V, 290-360 K). Also, the conductivity of hot wall grown 1,8-dihydroxy-9,10-anthraquinone films appear to increase by an order of 10 approximately as compared to thermally evaporated films. The substrate temperature appears to influence the properties of the films. The electrical conductivity, carrier concentration, drift mobility and optical band gap of the films increase with increases in substrate temperature, whereas activation energy decreases. The FTO/1,4-dihydroxy-9,10-anthraquinone/Al Schottky barrier device has been prepared by depositing 1,4-dihydroxy-9,10-anthraquinone onto FTO coated glass slides by hot wall technique. The device so obtained was studied for its J-V characteristics and the typical parameters such as open circuit voltage, short circuit current, fill factor and power conversion efficiency has been calculated.