Rectangular vacuum-arc plasma source
First Claim
1. An apparatus for a vacuum arc discharge, said apparatus comprising:
- (a) a cathode composed at least in part of a material to be evaporated, said cathode having an evaporable surface of substantially rectangular shape,(b) sensing means operatively connected at or near each of a pair of opposite ends along a length of said evaporable surface for sensing when an arc spot approaches either of said opposite ends, said sensing means capable of generating a signal when the arc spot approaches either of said opposite ends,(c) magnetic field establishing means for establishing over said evaporable surface a magnetic field, said magnetic field being represented by magnetic flux lines, said magnetic field establishing means being independent of an electrical current flowing through said cathode, and said flux lines having a predominant component which is substantially parallel to said evaporable surface and substantially perpendicular to the length thereof, and(d) magnetic field reversing means for reversing the direction of said magnetic flux lines responsive to said signal from said sensing means without substantially changing the shape of said predominant component thereof or its orientation with respect to said evaporable surface.
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Accused Products
Abstract
A rectangular vacuum-arc plasma source and associated apparatus for generating and directing a stream of plasma containing an ionized vapor of a cathode material toward a substrate by vacuum arc evaporation of a rectangular planar cathode mounted in a rectangular plasma duct. The rectangular duct conducts the plasma from the cathode to the substrate region, while intercepting the molten droplets of cathode material also generated by the arc. Magnets control the arc motion on the cathode surface while simultaneously generating the magnetic field which guides the plasma through the duct. Benefits of a filtered cathodic arc (fully ionized vapor stream, elimination of splattered droplets) are combined with the benefits of a rectangular source (uniform evaporation from the source and uniform deposition on the substrate using linear motion). The rectangular source may be extended indefinitely in length, thus allowing coating or ion implantation on large or long substrates.
78 Citations
30 Claims
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1. An apparatus for a vacuum arc discharge, said apparatus comprising:
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(a) a cathode composed at least in part of a material to be evaporated, said cathode having an evaporable surface of substantially rectangular shape, (b) sensing means operatively connected at or near each of a pair of opposite ends along a length of said evaporable surface for sensing when an arc spot approaches either of said opposite ends, said sensing means capable of generating a signal when the arc spot approaches either of said opposite ends, (c) magnetic field establishing means for establishing over said evaporable surface a magnetic field, said magnetic field being represented by magnetic flux lines, said magnetic field establishing means being independent of an electrical current flowing through said cathode, and said flux lines having a predominant component which is substantially parallel to said evaporable surface and substantially perpendicular to the length thereof, and (d) magnetic field reversing means for reversing the direction of said magnetic flux lines responsive to said signal from said sensing means without substantially changing the shape of said predominant component thereof or its orientation with respect to said evaporable surface. - View Dependent Claims (2, 3, 4)
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5. A plasma duct for a vacuum arc discharge, said plasma duct comprising:
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(a) an entrance arm of rectangular cross section having a width and a length in substantially the same proportions as, and at least as large as, those of a substantially rectangular cathode adopted to be mounted at or near said entrance arm, (b) an exit arm of rectangular cross section, the plasma duct having an axis alone a center line passing from the entrance arm through the exit arm, (c) a bend between said entrance arm and said exit arm, said bend having an inner radius and an outer radius, and (d) magnetic field generating means disposed in relation to said plasma duct for generating within said duct a magnetic field having a magnetic flux density in the vicinity of said outer radius which is greater than or equal to the magnetic flux density in the vicinity of said inner radius, said magnetic field being represented by magnetic flux lines, a portion of said magnetic flux lines being oriented in a direction substantially parallel to the axis of said plasma duct within said exit arm. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12)
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13. A method of controlling an arc discharge between a cathode composed at least in part of a material to be evaporated, and an anode, said arc discharge originating in an arc spot on an evaporable surface of the cathode having a length and a width, said method comprising:
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(a) establishing over said evaporable surface a magnetic field, said magnetic field being represented by magnetic flux lines, said magnetic field establishing means being independent of a electrical current flowing through said cathode, and said flux lines having a predominant component which is substantially parallel to said evaporable surface and substantially perpendicular to the length thereof; (b) detecting whenever said arc spot approaches either end of the length of said evaporable surface of the cathode; and (c) whenever said arc spot detected by said detecting step approaches either end of said evaporable surface of the cathode, reversing the direction of said magnetic flux lines without substantially changing the shape of said predominant component thereof or its orientation with respect to said evaporable surface.
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14. An apparatus for generating a beam of plasma containing an ionized vapor of a cathode material, in which a vacuum arc discharge is used to vaporize said cathode material, comprising:
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(a) a cathode having an evaporable surface of substantially rectangular shape; (b) an anode; (c) an arc power supply operatively connected to the cathode and the anode; (d) a plasma duct for transporting to a substrate area in which an object to be coated or implanted may be located, at least part of the plasma containing an ionized vapor of the cathode, said plasma generated by an arc discharge from said cathode, and said plasma duct having a rectangular cross-sectional shape and a width and a length in substantially the same proportions as, and at least as large as, those of said cathode, said plasma duct containing a bend in the axis along its centerline, forming in said plasma duct an entrance arm and an exit arm, said cathode being located at or near the end of said entrance arm with said evaporable surface facing into said plasma duct, and said substrate area being located at or near the end of said exit arm, (e) magnetic field generating means in electromagnetic communication with said plasma duct for generating within the plasma duct and over said evaporable surface of said cathode a magnetic field, said magnetic field being represented by magnetic flux lines, at least a first portion of said magnetic flux lines being oriented in a direction substantially parallel to the axis of said duct within said exit arm, and at least a second portion of said flux lines having a predominant component oriented substantially parallel to said evaporable surface of said cathode within the region of said entrance arm at or near said cathode; (f) sensor means for sensing an arc spot, said sensor means located adjacent to each end of said rectangular evaporable surface of said cathode, said sensor means being capable of producing a signal whenever said arc spot approaches either end of said evaporable surface; and (g) magnetic field reversing means responsive to said signal from the sensor means for reversing the direction of at least said second portion of said magnetic flux lines without substantially changing the shape of said second portion of said flux lines or their orientation with respect to said plasma duct. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification