Papers

ICMCTF2001 Session G3-1: Hollow Cathode, Hybrid and Atmospheric Plasma Processing

Monday, April 30, 2001 1:30 PM in Room Town & Country

Monday Afternoon

Start	Invited?	Item
1:30 PM		G3-1-1 Recent Developments in Inverted Cylindrical Magnetron Sputtering D.A. Glocker, M.M. Romach (Isoflux, Incorporated); V.W. Lindberg (Rochester Institute of Technology) Inverted cylindrical magnetron cathodes sputter from the interior surfaces of cylindrical targets and deposit material on all sides of three-dimensional substrates simultaneously. Since their invention in the 1970s they have been widely used to coat wires, fibers and ribbons. As the use of coatings on complex shapes has increased, cylindrical magnetrons have been adopted for a variety of applications ranging from x-ray telescope mirrors to biomedical implants. This paper describes the features of these devices and compares their operation and coating characteristics to those of planar magnetrons. Recent developments in sputtering dielectric materials are described and new methods that take advantage of cylindrical magnetron designs to produce high ionization densities at the substrates are discussed.
2:10 PM		G3-1-3 Construction of High Efficiency Microwave Atmospheric Pressure Plasma for Various Surface Treatment Processes K.H. Lee (Institute for Advanced Engineering (IAE), South Korea); H.Y. Song, J.M. Hong, S.Y. Kim (Institute for Advanced Engineering (IAE), Korea); J.J. Choi (Kwangwoon University, Korea) Microwave atmospheric pressure plasma systems using two different cavity modes of TM011 and TE011 are successfully designed and build to comprehensively study the high efficiency cleanning and ashing semiconductor processes and high rate deposition of diamond coatings for the development of the practical industrial applications. The microwave applicator and the cavity have been specifically designed to maximize microwave coupling into the plasma at resonant frequency. The plasma is reliably sustained up to 6kW using 2.45GHz microwave radiation in a gas flow at atmospheric pressure. Description of the system concept including resonant structure and theplasma discharge chamber will be presented together with the measurement of the process parameters of various surface treatment processes using optical emission spectroscope (OES), quadruple mass spectrometer (QMS) and Langmuir probe. Possible discharge mechanisms in the microwave plasma that can effect the high efficiency surface modification process and high rate, large area deposition in the film formation processes due to higher order mode microwave cavity structure will be discussed.
2:30 PM		G3-1-4 Pulse DC Power Hollow Cathode A. Belkind, C. Paduraru (Stevens Institute of Technology) Hollow cathode glow discharge is widely used in a variety of sources of electrons, ions, plasma, and sputtering material. These sources operate using mainly DC and RF power. Application of DC power pulsed in the range of tens to hundreds kHz improves and widens implementation of the hollow cathode sources. Pulse DC power (PDCP) helps to avoid arcing seen in some DC sources and does not show scale-up difficulties typical for RF sources. In this work, data on PDCP one- and multi-hole hollow cathodes are presented. Pulse duration and frequency influences on oxygen plasma generated in the hollow cathodes are discussed. Properties of PDCP hollow cathodes and magnetrons are compared.
3:10 PM		G3-1-6 Hollow Cathode PVD of Nitride and Oxide Films at Low Substrate Temperatures L. Bardos, H. Baránková (Uppsala University, Angstrom Laboratory, Sweden) Highly oriented crystalline films of aluminum nitride and titanium dioxide were grown from Al or Ti hollow cathode in the nitrogen and oxygen gas mixtures with argon. Films were grown on unheated substrates fixed at a holder with temperature sensor. Both cylindrical and linear hollow cathodes were powered by a radio frequency (rf) 13.56 MHz generator and arranged with the gas flow through the cathode. Properties of films deposited on glass and silicon samples at different hollow cathode regimes were teste d by X-ray diffraction. The film surface topographies were studied by AFM. Highly oriented crystalline AlN films were deposited at substrate temperature below 50Â°C. Best AlN films were deposited in pure nitrogen plasma. Variations in the deposition param eters at constant rf power can be used for modifications of AlN microstructure. Changes in the vibrational temperature of nitrogen molecules correlate with changes of the film deposition rate. Highly textured TiO₂ films can be deposited both as anatase o r rutile structure, which can be controlled by small changes of the oxygen content in argon. Films can be deposited on selected areas or inside holes by small cylindrical hollow cathodes. However, the deposition process can be scaled up to large substrates by magnetized M-M (Magnets in Motion) linear hollow cathodes.
3:30 PM		G3-1-7 Atomic Emission Spectroscopy of a Hollow Cathode Discharge Used for Deposition Applications V.H. Baggio-Scheid, J.W. Neri, G. Vasconcelos de (Centro Técnico Aeroespacial, Brazil) The hollow cathode discharge is a source of metal atoms, which has been used to built metal vapor lasers and in the processes of thin film depositions. The high energy of the secondary beam electrons, high current density and gas temperature make this discharge attractive for other applications in the field of plasma chemistry. Recently, discharges of microhollow cathodes operating at atmospheric pressure also enable their use in large area plasma processing. The characterization of sputter deposition processes requires the measurement of several quantities: the spatial distribution of the sputtered target atoms, ions and their velocity distribution; the accelerating electric field; the density profiles of gas atoms, metastable and ions; and the kinetic of ions and electrons in the cathode region. Many of these quantities can be measured by laser-aided techniques and Langmuir probe. Alternatively, atomic emission spectroscopy is a simple experimental technique which can provide useful information concerning the discharge. In this work a dc discharge with a copper hollow cathode in argon used for deposition applications is investigated using atomic emission spectroscopy. Typical discharge parameters during our investigation are pressures between 80 and 200 Pa and current densities up to 7 mA cm^-2. The sputtered cooper atoms were deposited onto a stainless substrate inserted into the cathode. The radial light intensity profiles of some selected copper and argon lines were measured. The analysis of these profiles gives insights into the excitation rates of the argon and metal atoms and the radial dimension of the negative glow. The correlation between the emitted light intensities and the deposition rates of the sputtered copper atoms onto the metallic substrate will be presented and discussed.
3:50 PM		G3-1-8 Characteristics of He/O2 Atmospheric Pressure Glow Discharge and Its Dry Etching Properties of Organic Materials Y.H. Lee, G.Y. Yeom (Sungkyunkwan University, Korea) In the industrial plasma processes, low-pressure plasmas are dominant in the processing of the materials such as thin film deposition, etching, and surface treatment. However, to generate plasmas at low pressures, costly vacuum equipment and vacuum measurement tools are required, and the use of vacuum in the processing increases the fabrication cost and decreases throughput. If stable glow discharges can be realized under atmospheric conditions, the expensive vacuum equipment and the measurement tools can be eliminated and the throughput can be also increased. In this study, an atmospheric pressure plasma source composed of capillary dielectric electrodes operated with low frequency power has been developed. The basic characteristics of the capillary discharges operated at the atmospheric pressure were investigated using a high voltage probe(Tektronix P6015), current meter(Pearson electronics 6600), and optical emission spectroscopy(SC-Tech PCM 402). Also, using some of the stable He/O₂ capillary discharges, the photoresist etch characteristics were investigated. The discharge voltage of He capillary discharges increased with the increase of the aspect ratio of the capillary while the increase of He flow rate decreased the voltage. Also, the discharge current of He capillary plasma increased with the increase of aspect ratio while the increase of He flow decreased the discharge current. The addition of oxygen flow to a constant He flow rate also increased the discharge voltage, however, decreased the discharge current Using some of the stable capillary He/O ₂ discharge conditions, photoresist on Si-wafers was etched and the etch rates higher than 200 nm/min was obtained on the average. Circular photoresist clearing pattern was observed due to the increased etch rate near the capillaries. To improve the etch rate and overall uniformity, capillary electrodes containing denser capillaries need to be used.
4:10 PM		G3-1-9 Investigation of Microparticles Emission from Plasma of Gas Discharge with Hollow Cathode A.S. Zolkin, V.V. Prihodko, A.A. Maksyashin (Novosibirsk State University, Russia) The plasma of gas discharge with hollow cathode is considered as a reactor in which microparticles are synthesized. Clusters and microparticles of chemical compounds can be formed during atomization of the cathode material and collisions between plasma components when the formation of the new phase occurs mainly on ions. The emission of Cu, Mo, Ta, and Ni microparticles from the plasma of hollow cathode (30 mm in diameter, 120 mm long) with discharge in argon (P = 0.05 Torr) is studied in the present work using the molecular beam technique. Plasma flew into the chamber with reduced pressure through a 3 mm hole in the front part of hollow cathode and interacted with the surface of silicon single crystal at a distance of 2 - 30 mm from the nozzle hole of the cathode. Films and particles on silicon surface were studied with the help of scanning (SEM) combined with X-ray microanalyzer. The back-scattering electrons (BSEM) technique was used as an additional tool. Of special interest are the new data on the emission of copper microparticles with the mean size of 50 micrometer (in liquid state). The flow of copper particles from the plasma is about 2*10¹³ atoms per second. We measured the ion current (0.1 - 10 µmA) at the total discharge current (10 - 60 mA) in the hollow cathode. The results obtained in the present work can be of interest for researchers in the field of plasma chemistry, gas discharge physics, as well as for those studying cluster formation in plasma and the synthesis of thin films.