Chemistry: electrical and wave energy – Apparatus – Coating – forming or etching by sputtering
Reexamination Certificate
1999-04-14
2002-02-26
Nguyen, Nam (Department: 1753)
Chemistry: electrical and wave energy
Apparatus
Coating, forming or etching by sputtering
C204S298110, C204S298190, C204S298410
Reexamination Certificate
active
06350356
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to coating deposition and plasma processing (ion implantation, etching, etc.) and particularly to magnetron cathodes.
BACKGROUND OF THE INVENTION
Magnetron cathodes, in which a closed-loop magnetic field is established over at least part of the evaporable surface of the cathode, have come into wide use over the last 2 decades or so in the arts of sputtering and arc evaporation. In the case of a sputtering cathode the magnetic field serves to intensify an inert-gas plasma discharge and guide the plasma in a closed-loop path along the evaporable surface. In the case of an arc cathode, the magnetic field serves to guide the direction of one or more arc spots in a closed-loop path along the evaporable surface. Similar cathode and magnetic field geometries have been used for both sputtering and arc evaporation, with the main differences being the magnetic field strength required and the means of lateral confinement of the discharge. Sputtering cathodes have field strength of typically several hundred Gauss, while arc cathodes typically have field strength of only a few Gauss or tens of Gauss. Most conventional, currently used magnetron cathodes can be described as having basically planar or cylindrical geometry.
Planar magnetrons generally comprise a flat circular or rectangular plate of the material to be vaporized. A magnetic field is projected through or over the plate to form a closed-loop, magnetic tunnel or “racetrack” over the evaporable surface as disclosed for example in U.S. Pat. No. 5,407,551 (Sieck, et al.), U.S. Pat. No. 4,162,954 (Morrison), U.S. Pat. No. 4,673,477 (Ramalingam, et al.), and U.S. Pat. No. 4,724,058 (Morrison). The magnetic tunnel guides and contains the sputtering or arc discharge, typically forming a circular or oval erosion groove on the evaporable surface (the cathode surface from which material is vaporized). Material vaporized by either process is emitted in directions substantially perpendicular to the evaporable surface. Substantially perpendicular directions are understood for the purposes of this invention to refer to an emission distribution centered around the perpendicular to a surface, in which the amount of material emitted from a particular point on the cathode in a particular direction falls off as a function of the angle away from the perpendicular at that point. Substrates to be coated typically face the cathode surface and may be rotated and/or translated to extend the area of uniform coverage. Portions of the cathode surface may be inclined with respect to a planar surface, as disclosed in U.S. Pat. No. 4,428,816 (Class, et al.) and U.S. Pat. No. 4,457,825 (Lamont) in order to influence the distribution of emitted material or the cathode erosion profile.
A rectangular planar triode sputtering apparatus is disclosed in U.S. Pat. No. 4,404,077 (Fournier) in which a parallel field component extends over a non-closed path on the evaporable surface, with an electron emitter at one end of the path and a collector at the other end. A rectangular planar arc cathode is disclosed in U.S. Pat. No. 5,480,527 (Welty) in which the polarity of a parallel field component is reversed to make an arc scan back and forth along the length of the evaporable surface. A rectangular arc evaporation cathode is disclosed in U.S. Pat. No. 5,380,421 (Gorokhovsky) in which the evaporable surface is one side of a rectangular plate having beveled edges, and in which combined static and dynamic magnetic means are taught to control the arc movement along the length. A magnetron sputtering cathode is disclosed in U.S. Pat. No. 5,277,779 (Henshaw) comprising a rectangular frame, in which the erosion path wraps around the inner periphery of the frame, vaporized material is directed inwardly toward the center of the frame aperture, and substrates to be coated are passed through the aperture. A two-sided planar magnetron sputtering cathode is disclosed in U.S. Pat. No. 4,116,806 (Love) which has a separate closed-loop magnetic tunnel on each of two planar targets disposed on each side of a central frame comprising magnetic means. A planar magnetron cathode for either arc evaporation or sputtering is disclosed in U.S. Pat. No. 5,160,595 (Hauzer, et al.), in which part of the magnet means may be moved relative to the target surface in order to adjust the field strength depending on the vaporization method to be employed.
Cylindrical magnetrons generally comprise a cylindrical bar or tube of the material to be vaporized. The evaporable surface is generally the entire exterior or interior cylindrical surface, while the emission distribution depends on the particular magnetic configuration. A cylindrical sputtering cathode with a solenoidal magnetic field parallel to the long cylinder axis is disclosed in U.S. Pat. No. 4,031,424 (Penfold, et al.) which has an emission distribution perpendicular to the exterior surface and (ideally) uniform around the circumference and along the length. Sputtering and arc cathodes using magnetic means inside a cylindrical target to generate a closed-loop magnetic tunnel and erosion track over part of the exterior surface are disclosed for example in U.S. Pat. No. 4,417,968 (McKelvey), U.S. Pat. No. 5,364,518 (Hartig, et al.), and U.S. Pat. No. 4,849,088 (Veltrop, et al.), which employ relative movement between the magnet means and the target cylinder to achieve uniform erosion of the target. The magnetic means may remain fixed while the cylinder rotates or vice versa. The emission distribution is substantially perpendicular to the points on the cylindrical surface comprising the instantaneous location of the erosion track. Short cylindrical arc evaporation cathodes with solenoidal magnetic fields are disclosed in U.S. Pat. No. 4,492,845 (Kljuchko, et al.) and U.S. Pat. No. 5,518,597 (Storer, et al.). Long cylindrical arc evaporation cathodes generally require dynamic means to ensure uniform arc movement over the cathode length, as disclosed for example in U.S. Pat. No. 5,269,898 (Welty) and U.S. Pat. No. 5,451,308 (Sablev, et al). A cylindrical arc cathode in which an external coil applies a magnetic field perpendicular to the long axis of the cathode is disclosed in Soviet Inventor=s Certificate 711787. In this case the arc spots are described to be confined in the area in which the magnetic field lines are near perpendicular to the cathode surface, and it is specified that arc motion around the circumference is achieved by rotating the coil around the cathode. The magnetic field does not in this case comprise a closed-loop tunnel or path over the cathode surface.
Insulator means for preventing arc discharge spots from moving off an evaporable surface are disclosed in U.S. Pat. No 4,430,184 (Mularie). Magnetically permeable ring means for preventing arc spots from moving off an evaporable surface are disclosed in U.S. Pat. No. 4,448,659 (Morrison), U.S. Pat. No. 4,559,121 (Mularie), and U.S. Pat. No. 4,600,489 (Lefkow). Shielding and gap means for extinguishing arc spots which move off specified evaporable surfaces are disclosed in U.S. Pat. No. 3,793,179 and U.S. Pat. No. 3,783,231 (Sablev, et al.). Conductive ring means employing eddy currents for containing an arc discharge are disclosed in U.S. Pat. No. 5,387,326 (Buhl, et al.). Projecting side-wall means for containing a sputtering discharge are taught in U.S. Pat. No. 4,515,675 (Kieser, et al.), U.S. Pat. No. 4,933,064 (Geisler et al.), U.S. Pat. No. 5,133,850 (Kukla, et al.), U.S. Pat. No. 5,266,178 (Sichmann, et al.), and U.S. Pat. No. 5,597,459 (Altshuler) in which outward projections of the target, magnetic poles, or shielding at the sides of the evaporable surface serve to provide lateral confinement of the plasma.
U.S. Pat. No. 4,581,118 (Class, et al.) discloses a magnetron substrate support electrode having a book-shaped rectangular body, and a magnet core with flange-like pole pieces to provide a longitudinal magnetic field wrapped around the electrode body. The apparatus is taught to provide uniform plasma processing of a s
Cantelmo Gregg
Doigan Lloyd D.
Kapustij Myron B.
Nguyen Nam
Vapor Technologies Inc.
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