Chemistry: electrical and wave energy – Apparatus – Vacuum arc discharge coating
Patent
1994-01-19
1995-07-18
Weisstuch, Aaron
Chemistry: electrical and wave energy
Apparatus
Vacuum arc discharge coating
20419238, 427540, 427580, 250426, 31511141, C23C 1432
Patent
active
054338360
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to arc sources and in particular to arc source macroparticle filters which substantially remove all the macroparticles from the generated plasma.
BACKGROUND ART
The invention was developed primarily for use with electron bombardment and the deposition of metal ions and their associated oxides, and will be described hereinafter with reference to these applications. However, it will be appreciated that the invention is not limited to these particular fields of use, and is also suitable for vacuum deposition of nitrides and carbides.
Macroparticles are those particles emitted from the cathode with sizes ranging between 0.1 microns up to 10 microns. Without removal of these macroparticles from the plasma the resulting coating is found to be non-uniform and cratered. When a coating is to be applied in a high precision application such as those associated with microelectronic or optical fields, macroparticles are particularly undesirable.
The presence of macroparticles in the plasma prevents prior art arc sources from being effectively able to produce electron beams for heating of associated work pieces. When applied to this manner of operation the macroparticles would partially cover and mark the workpiece making it unsuitable for further coatings.
In conjunction with the above mentioned problem, the presence of macroparticle does not create a favourable environment for the deposition of various coatings, in particular vanadium dioxide. This coating is of considerable interest due to its transition between semiconductor and metallic properties over a small temperature range, but is difficult to produce in the exact atomic proportions required.
In the past, many macroparticle filters have included the use of 90.degree. bending of the plasma by magnetic fields so that the much larger macroparticles would separate from the plasma. However, an extended magnetic field is needed to produce the required bending and confining of the plasma. These prior art devices only accommodate positive ion currents of less than 200 mA for 100 A arcs, and thereby have a very restricted deposition rate and film growth rate.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide an arc source macroparticle filter which overcomes or substantially ameliorates at least some of the disadvantages of the prior art.
According to one aspect of the invention there is provided an arc source macroparticle filter comprising a cathode for emitting particles, an extended tubular anode adjacent and substantially coaxial with the cathode for accelerating the emitted particles, and means for generating a magnetic field to define a continuous non-linear plasma duct to direct preselected charged particles and separate therefrom undesirable larger particles, the duct being minimally non-linear to permit high rates of charged particle transmission.
Preferably, the temperature of the anode is maintained within a predetermined range to facilitate removal of the undesirable particles from the plasma.
Preferably also, the length of the extended anode is at least six times the diameter of the cathode to facilitate removal of the undesirable particles from the plasma.
In a preferred form the non-linear plasma would form a smooth curve, traversing an angle of substantially 45.degree. to facilitate removal of the undesirable particles from the plasma while allowing high charge transfer rates.
According to another aspect of the invention there is provided a method of producing vanadium dioxide including the steps of: macroparticle free; and an oxygen atmosphere while maintaining a lower level of said electron bombardment.
Preferably, the vanadium dioxide is produced using an arc source macroparticle filter as described above, wherein vanadium dioxide coatings are applied to workpieces.
Preferably also, the arc source macroparticle filter is provided with low voltage positive biasing of the workpiece for enabling simultaneous bombardment of the workpiece with both electrons and vanadium i
REFERENCES:
patent: 3483110 (1969-12-01), Rozgonyi
patent: 3899407 (1975-08-01), Eastwood et al.
patent: 4146810 (1979-03-01), Hicks et al.
patent: 4452686 (1984-06-01), Axenov et al.
patent: 4654231 (1987-03-01), Nyberg et al.
patent: 5078848 (1992-01-01), Anttila et al.
patent: 5126030 (1992-06-01), Tamagaki et al.
patent: 5279723 (1994-01-01), Falabella et al.
patent: 5317235 (1994-05-01), Treglio
"High-rate deposition of Al.sub.2 O.sub.3 films using modified cathodic plasma deposition processes"; H. Randhawa; Journal of Vacuum Science & Technology; (1989), pp. 2346-2349.
"Ion Implantation: Equipment and Techniques"; Proceedings of the Fourth International Conference; Sep. 1-13, 1982, pp. 56-58 and 274-290.
EPO Patent Abstract 417-780-A; "Evaporating arc discharge cathode with cathode spots with reduced macro-particle emission"; 1991.
Japanese Kokai No. 51-111484; "Manufacture of Thin Layer of Vanadium Dioxide"; 1976.
Kinder Terence J.
Martin Philip J.
Netterfield Roger P.
Commonwealth Scientific and Industrial Research Organization
Weisstuch Aaron
LandOfFree
Arc source macroparticle filter does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Arc source macroparticle filter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Arc source macroparticle filter will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2417990