Kaufman & Robinson, Inc.

Other

Advanced Energy Industries, Inc.

Veeco Instruments Inc.

Front Range Fakel, Inc.

James R Kahn

Harold R Kaufman

Viacheslav V Zhurin

Raymond S Robinson

Steven J Geissler

David Alan Baldwin

Todd Lanier Hylton

Richard E Nethery

Denis M Shaw

Chris M Shonka

Kirk A Thompson

Rhonda J Parker

In accordance with one embodiment of the present invention, an end-Hall ion source has an electron emitting cathode, an anode, a reflector, an internal pole piece, an external pole piece, a magnetically permeable path, and a magnetic-field generating means located in the permeable path between the two pole pieces. The anode and reflector are enclosed without contact by a thermally conductive cup that has internal passages through which a cooling fluid can flow. The closed end of the cup is located between the reflector and the internal pole piece and the opposite end of the cup is in direct contact with the external pole piece, and wherein the cup is made of a material having a low microhardness, such as copper or aluminum.

End-hall ion source with enhanced radiation cooling

In accordance with one embodiment of the present invention, the dielectric discharge chamber of a generally axially symmetric ion source has a hollow cylindrical shape. One end of the discharge chamber is closed with a dielectric wall. The working gas is introduced through an aperture in the center of this wall. The ion-optics grids are at the other end of the discharge chamber, which is left open. The inductor is a helical coil of copper conductor that surrounds the cylindrical portion of the dielectric discharge chamber. The modification that produces uniformity about the axis of symmetry is a shorted turn of the helical-coil inductor at the end of the inductor closest to the ion-optics grids.

Mitigation of plasma-inductor termination

In accordance with one embodiment of the present invention, there is provided a switch-mode power supply to generate the heating current for a hot-filament electron-emitting cathode. The power supply directly couples, without an output power transformer, the output from a full-bridge converter that operates at an output frequency in the range from ten Hz to tens of Khz to the output terminals of the power supply. A connection to a reference potential that minimizes the potential fluctuation of the cathode is provided by the center tap on an autotransformer connected across the output terminals, where the conductors in the autotransformer are sized for half of the emission current from the cathode rather than the much larger heating current.

Power supply for a hot-filament cathode

In accordance with one embodiment, the hollow cathode is comprised of a first tantalum tube, tantalum foil, and a second tantalum tube. The foil is in the form of a spiral winding around the outside of the first tube and is held in place by the second tube, which surrounds the foil. One end of the second tube is approximately flush with one end of the first tube. The other end of the second tube extends to a cathode support through which the working gas flows. To start the cathode, a flow of ionizable inert gas, usually argon, is initiated through the hollow cathode and out the open end of the first tube. An electrical discharge is then started between an external electrode and the first tube. When the first tube is heated to operating temperature, electrons are emitted from the open end of the first tube.

Industrial hollow cathode

In accordance with one embodiment of the present invention, the hollow-cathode apparatus comprises a small-diameter tantalum tube with a plurality of tantalum-foil radiation shields, wherein the plurality of shields in turn comprise one or more spiral windings external to that tube and approximately flush with the open end from which electron emission takes place. The axial length of at least one of the inner windings (closer to the tantalum tube) is equal to or less than approximately half the length of the tantalum tube. An enclosed keeper surrounds the cathode. To start the cathode, a flow of ionizable inert gas, usually argon, is initiated through the cathode and out the open end. An electrical discharge is then started between the keeper and the hollow cathode. When heated to operating temperature, electrons exit from the open end of the hollow cathode.

Industrial hollow cathode with radiation shield structure

In accordance with one embodiment of the present invention, there is provided a switch-mode power supply to generate the heating current for a hot-filament electron-emitting cathode. The power supply directly couples, without an output transformer, the output from a full-bridge converter that operates at an output frequency in the range from ten Hz to ten kHz. A connection to a reference potential that minimizes the potential fluctuation of the cathode is provided by one of the direct-current inputs to the converter.

In accordance with one specific embodiment of the present invention, the ion optics for use with an ion source have a plurality of electrically conductive grids that are mutually spaced apart and have mutually aligned respective pluralities of apertures through which ions may be accelerated and wherein each grid has an integral peripheral portion. A plurality of moment means are applied to a circumferentially distributed plurality of locations on the peripheral portion of each grid, which is initially flat, thereby establishing an annular segment of a cone as the approximate shape for that peripheral portion and a segment of a sphere as the approximate dished shape for the grid as a whole. The plurality of grids have conformal shapes in that the direction of deformation and the approximate spherical radii are the same. This elastic deformation during installation avoids any need for any permanent or inelastic deformation during fabrication, as well as controlling the excessive thermal displacements and accompanying performance changes to which flat grids are prone.

Ion optics with shallow dished grids

In one embodiment of this invention, the apparatus for sputter deposition within an evacuated volume comprises a compact gridless ion source into which an ionizable gas is introduced and from which ions leave with directed energies at or near the sputtering threshold and a sputter target near that source, biased negative relative to the surrounding vacuum enclosure, and located within the beam of ions leaving that source. Particles sputtered from the target are deposited on a deposition substrate spaced from both the ion source and the sputter target. An energetic beam of electrons can be generated by the incident ions striking the negatively biased sputter target and the deposition substrate is located either within or outside of this beam, depending on whether the net effect of bombardment by energetic electrons is beneficial or detrimental to that particular deposition process.

Apparatus for sputter deposition

In accordance with one specific embodiment of the present invention, a Hall-current ion source of the end-Hall type has an anode that is contoured with one or more recesses in the electron-collecting surface which have areas that are protected from the deposition of externally generated contamination thereon, as well as one or more protrusions that have higher temperatures than the bulk of the anode, thereby increasing the removal or passivation of coatings during operation by the thermal degradation of the coating and the effects of thermomechanical stresses. In another specific embodiment, which can be combined with the above embodiment, electrically isolated baffle or baffles are located to protect a substantial fraction of the electron-collecting surface of the anode from the deposition of externally generated contamination thereon.

Hall-current ion source

In accordance with one embodiment of the present invention, the ion-beam apparatus takes the form of a gridless ion source with a hot-filament cathode-neutralizer, in which the hot filament is heated with a current from the cathode-neutralizer heater. The cathode-neutralizer is connected to the negative terminal of the discharge supply for the gridless ion source. This connection is substantially isolated from ground (the potential of the surrounding vacuum chamber, which is usually at earth ground) and its potential is measured relative to ground. The heater current to the cathode-neutralizer is controlled by adjusting it so as to maintain this potential in a narrow operating range. This control can be manual or automatic.

Ion-source neutralization with a hot-filament cathode-neutralizer

In accordance with one specific embodiment of the present invention, the apparatus for sputter deposition within an evacuated volume comprises a compact ion source to generate ions into which an ionizable gas is introduced and from which ions leave with directed energies near or below the sputtering threshold, a sputter target near that source and located within the beam of ions leaving that source, a sputter target with a grounded shield that defines the target portion exposed to sputtering, and a power supply to bias the target negative relative to ground so that ions are attracted to and sputter the target. Particles sputtered from the target are deposited on a deposition substrate separate from both the ion source and the sputter target. For an insulating target, the target is biased with a radiofrequency power supply and the bias has a mean negative value rather than a direct-current negative value relative to ground. The rate and energy with which the ions arrive at the target determine the rate with which that target is sputtered and the deposition rate on the substrate. In using a compact gridless ion source, the high pressure required for generating ions is confined to the ion source, reducing the pumping gas load. For ion energies at or near the sputtering threshold, the sputtering from extraneous hardware is reduced or eliminated. In addition, the target biases can be low enough to minimize the damage due to energetic neutrals that result from reflection of energetic target ions.

In accordance with an embodiment of the present invention, apparatus for ion-assisted magnetron deposition takes a form that includes a magnetron, a deposition substrate displaced from the magnetron, and an ion source also displaced from the magnetron and located so that the ion beam from the ion source is directed at the deposition substrate. The ion source is operated without an electron-emitting cathode-neutralizer, the electron current for this function being provided by electrons from the magnetron. In one specific embodiment, the ion source is operated so that the potential of the deposition substrate is maintained close to that of a common ground for the magnetron and the ion source. In another embodiment, the ion source is of the Hall-current type and the discharge current of the ion source is approximately equal in magnitude to the current of the magnetron discharge.

Ion-assisted magnetron deposition

In accordance with one specific embodiment of the present invention, the closed drift hollow cathode comprises an axisymmetric discharge region into which an ionizable gas is introduced, an annular electron emitting cathode insert disposed laterally about that discharge region, a surrounding enclosure, an aperture in that enclosure disposed near the axis of symmetry and at one end of that region, and a magnetic field within that region which is both axisymmetric and generally disposed transverse to a path from the cathode insert to the aperture. An electrical discharge is established between the cathode insert and the enclosure. The electrons emitted from the cathode insert drift in closed paths around the axis, collide with molecules of ionizable gas, and sustain the discharge plasma by generating additional electron-ion pairs. Ions from the plasma bombard the cathode insert, thereby maintaining an emissive temperature. Electrons from the plasma diffuse to and escape through the aperture to provide the electron emission. The closed drift nature of the discharge circumferentially distributes the heating of the cathode insert and the utilization of the electron emitting capabilities thereof. The discharge current controls the maximum value of the electron emission.

Closed drift hollow cathode

In one embodiment of the present invention, the ion optics for use with an ion source have first and second electrically conductive grids having mutually aligned respective pluralities of apertures through which ions may be accelerated and wherein each has an integral peripheral portion. There is also a support member. There are first and second series of seats around the respective peripheral portions of the first and second grids. A plurality of first spherical insulators are distributed between seats of the first and second series, thereby establishing a predetermined distance between the grids while still enabling radial movement between their peripheral portions. There are third and fourth series of seats around the support member and the peripheral portion of the second grid, respectively, with seats of the fourth series displaced from those of the second series in the same grid. A plurality of second spherical insulators are distributed between seats of the third and fourth series, thereby establishing a predetermined distance between the support member and the second grid while still enabling motion in at least the radial direction between the support member and the peripheral portion of the second grid. A clamping force between the support member and the peripheral portion of the first grid maintains contact between the insulators and their seats.

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Ft. Collins, CO, United States of America

James R Kahn