Papers

ICMCTF1999 Session G3: Hollow Cathode Plasma Processing

Tuesday, April 13, 1999 2:30 PM in Room Town & Country

Tuesday Afternoon

Start	Invited?	Item
2:30 PM		G3-4 Fundamentals of the Hollow Cathode Discharge and the Plasma Database GAPHYOR J.-L. Delcroix (Université Paris-Sud, France) Basic principles of the hollow cathode effect and regimes of the hollow cathode discharge will be summarized. Parameters and performance of the hollow cathode plasma depend strongly on the cathode material, gas and gas dynamics. Both the understanding of the hollow cathode plasma and the design of hollow cathodes require knowledge of the plasma and material data, and also some basic data from other fields of physics. The most important are Atomic and Molecular Data - energy levels, cross sections, reaction rates, gas surface interactions, etc. A very large amount of available information is tractable only by electronic media. Special databases accessible on the Webs have been developed. The author has been working in this field for 25 years and has developed the GAPHYOR (GAs-PHYsics-ORsay) database (http://gaphyor.lpgp.u-psud.fr). It includes more than 500 000 entries covering for atoms and small molecules a large variety of phenomena of interest for gas discharge modelling and experimental analyses (structures, photon and electron collisions, atomic and molecular reactions, transport coefficients, etc.). A detailed description, and hopefully an on-line demo, will be given during the presentation.
3:10 PM		G3-6 The Use of Hollow Cathode Structured Magnetron Targets J.W. Bradley (UMIST, United Kingdom) Magnetron sputtering is a widely used technique for the deposition of thin-films and coatings. It has been shown that by structuring the cathode target with drilled cylindrical holes ¹, the current-voltage characteristics of these sources can be modified. In this study, a series of experiments has been carried out with grooved Cu and Ti targets. The aim is to induce a significant hollow cathode effect by trapping magnetized electrons between the walls, but still allowing the E x B current rotation. The grooves, typically 2.5 mm deep and 2 mm wide were placed initially in the position of the sputter trench. The discharge current-voltage characteristics were measured and compared to similar flat targets, in a pressure range of 0.5 to 4 mTorr. It is found that lower breakdown voltages and higher discharge currents, (compared to flat targets), can be achieved with the new design, and the discharge is more efficient than with the use of holes. An investigation has been made into how changing the position of the grooves, (and hence the magnetic field orientation relative to the groove walls) can alter the discharge performance. ¹ Bradley J. W. and Cecconello M., Vacuum - 49 (1998), 315.
3:30 PM		G3-7 Effect of the Gas and Cathode Material on the rf Hollow Cathode Discharge H. Baránková, L. Bardos (Uppsala University, Sweden) The process of generation of the radio frequency (rf) Hollow Cathode Discharge was examined for different gases and different materials of the rf electrode. The rf delivered power range used in the experiments enabled to analyze the development of the Hollow Cathode Discharge together with the transition into the Hollow Cathode Arc for selected combinations of cathode materials and gases. The results for combinations of argon, nitrogen, oxygen and Al, Ti, Mo and Zn electrodes are shown as examples. The threshold rf power for generation of the Hollow Cathode Discharge, i.e. for the gap-sheath boundary breakdown, depends on the type of gas. Increasing the rf power, the power dependence of the discharge characteristics exhibits different features for different gases and gas mixtures, which influences also the transition into the arc regime. Physical parameters of the target material, e.g. the work function and the melting point, affect strongly the performance of the discharge, too. Reactive deposition, investigated simultaneously with the performance of the discharge, is illustrated by the Al-N and Al-O film growth. AlN films with the preferential orientation of (002) were grown without substrate heating. Crystalline phases of stoichiometric alumina films were obtained at a substrate temperature as low as 400 °C.
3:50 PM		G3-8 Parallel Operation of Hollow Cathode Plasma Sources R. Wilberg (VTD Vacuumtechnik Dresden GmbH, Germany); T. Lunow, M. Falz (VTD Vakuumtechnik Dresden GmbH, Germany); H. Morgner, S. Straach, M. Krug (FEP, Dresden, Germany) By means hollow cathode arc discharge (HCD), extremely high plasma density can be achieved. In this way, this type of the discharge gains an increasing importance for the plasma activated reactive deposition on large surfaces. Important parameters of the HCD are explained at first. Using hollow cathode arc discharge for the plasma assisted deposition on large substrates arrangements with several hollow cathodes are necessary. Results about extensive studies for the parallel operation of several hollow cathodes as plasma source during deposition of silicon dioxide and alumina oxide layers are demonstrated. Their correlation with the layer properties and the layer uniformity will be explained. The application in production demands a high reproducibility of the deposited layers and therefore a well adapted control design and important results will be presented.
4:10 PM		G3-9 Jet Matrix Plasma Source for Near Atmospheric Pressure Operation St. Jelinek, D. Korzec, J. Engemann (University of Wuppertal, Germany) For many industrial applications plasma sources working near atmospheric pressure are needed. A Jet Matrix Plasma Source (JEMPS-1) was proved to be an efficient tool for large area film deposition in the mbar pressure range. The plasma jets used in JEMPS-1 are extracted from 13.56 MHz high density hollow cathode discharges. An advantage of JEMPS concept is the scalability of geometrical dimensions with increasing pressure. Following the scaling rools a novel plasma source JEMPS-10 for operation in the pressure range from 5 mbar to 250 mbar has been developed. The JEMPS-10 is realized as a matrix of 17 x 28 plasma jets. Its typical working conditions are: gas flow from 100 sccm to 1500 sccm, pressure range from 6 mbar to 100 mbar and RF power up to 1000 W. The JEMPS-10 makes it possible to treate temperature sensitive materials, like plastics, textiles and other organic materials. The surface treatment by use of JEMPS sources is realized as a remote process. The carrier gas, i.e. oxygen or hydrogen is introduced in the JEMPS and is extracted as jets. Crucial for the process operation of the JEMPS-10 is the spatial distribution of the chemical radicals generated in the jet zone. The wave length selective observation by use of a CCD camera for different pressures and gas flows of oxygen and hydrogen will be presented. The chemically active gases or monomeres are distributed outside the JEMPS in a distance from 10 mm to 30 mm from the anode. The substra te surface is placed in a distance of 30 mm to 60 mm from the source. Typical deposition rates for siloxane/oxygen based deposition process will be presented.