Patent US2237812A successfully refreshed from Google Patents.
US4727293A
Expired / Lapsed
US
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Plasma generating apparatus using magnets and method
Assignee: Michigan State University
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Filing: 1986-04-07
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Granted: 1988-02-23
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Expires: 2006-04-07
Abstract
Abstract An improved ion generating apparatus for producing a plasma disk using magnets 34 and 35 around a region 16 in a chamber 15 positioned in a microwave cavity is described. The apparatus is particularly operated at a microwave frequency such that electron cyclotron resonance is produced in the plasma to create an accelerating surface for the electrons around and inside of the plasma. The apparatus can be operated to treat an article 100 in the plasma or a holder 39, with a grid 51 to withdraw particles or with a magnets 47 around an opening 48 forming a nozzle which with electron cyclotron resonance produces a neutral beam of charged particles. The apparatus is particularly useful as a plasma source especially for oxidation, etching and deposition.
Inventors
- 👤 Jes Asmussen
- 👤 Donnie K. Reinhard
- 👤 Mahmoud Dahimene
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:50
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/32; H01J37/32009; H01J37/32192; H01J37/32211; H01J37/32247; H01J37/32256; H01J27/00; H01J27/02; H01J27/16; H01J37/32266; H01J37/32284; H01J37/32431; H01J37/3266; H01J37/32678
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
284 words
A plasma generating apparatus including a plasma source employing a radio frequency, including UHF or microwave, wave coupler of a non-magnetic metal in the shape of a hollow cavity which can be excited in one or more TE or TM modes of resonance, including an electrically insulated chamber having a central longitudinal axis and mounted in the coupler, including a gas supply means for providing a gas which is ionized to form the plasma in the chamber, including a moveable plate means of a non-magnetic metal in the cavity mounted perpendicular to the axis of the chamber and moveable towards and away from the chamber as a sliding short, including a moveable probe connected to and extending inside the coupler for coupling the radio frequency waves to the coupler, wherein movement of the moveable plate means and the probe in the coupler achieves the selected TM or TE mode of resonance of the radio frequency wave in the coupler and varies the resonance of the mode and wherein the radio frequency wave applied to the coupler creates and maintains the plasma at reduced pressures in the shape of an elongate plasma disk perpendicular to and surrounding the central longitudinal axis in the chamber, the improvement which comprises: (a) a plurality of first magnets mounted on the apparatus around the longitudinal axis of the chamber on a ring of high permeability magnetic material so as to create magnetic cusps in the chamber which aid in confining the plasma in the chamber; and (b) second magnets mounted on the apparatus on a sheet of high permeability magnetic material so as to provide magnetic cusps inside the chamber which aid in confining the plasma in the chamber.
Claim 2
Dependent Claim
284 words
A plasma generating apparatus including a plasma source employing a radio frequency, including UHF or microwave, wave coupler of a non-magnetic metal in the shape of a hollow cavity which can be excited in one or more TE or TM modes of resonance, including an electrically insulated chamber having a central longitudinal axis and mounted in the coupler, including a gas supply means for providing a gas which is ionized to form the plasma in the chamber, including a moveable plate means of a non-magnetic metal in the cavity mounted perpendicular to the axis of the chamber and moveable towards and away from the chamber as a sliding short, including a moveable probe connected to and extending inside the coupler for coupling the radio frequency waves to the coupler, wherein movement of the moveable plate means and the probe in the coupler achieves the selected TM or TE mode of resonance of the radio frequency wave in the coupler and varies the resonance of the mode and wherein the radio frequency wave applied to the coupler creates and maintains the plasma at reduced pressures in the shape of an elongate plasma disk perpendicular to and surrounding the central longitudinal axis in the chamber, the improvement which comprises: (a) a plurality of first magnets mounted on the apparatus around the longitudinal axis of the chamber on a ring of high permeability magnetic material so as to create magnetic cusps in the chamber which aid in confining the plasma in the chamber; and (b) second magnets mounted on the apparatus on a sheet of high permeability magnetic material so as to provide magnetic cusps inside the chamber which aid in confining the plasma in the chamber.
Claim 3
Dependent Claim
290 words
A plasma generating apparatus which comprises: (a) a plasma source employing a radio frequency, including UHF or microwave, wave coupler which is metallic and non-magnetic and in the shape of a hollow cavity which can be excited in one or more TE or TM modes of resonance; (b) an electrically insulated chamber having a central longitudinal axis and mounted in the coupler; (c) gas supply means for providing a gas which is ionized to form the plasma in the insulated chamber; (d) a movable probe connected to and extending inside the coupler for coupling the radio frequency waves to the coupler; (e) a plurality of first magnets mounted around the longitudinal axis of the chamber on a ring of high permeability magnetic material so as to create magnetic cusps in the chamber which aid in confining the plasma in the chamber; (f) movable plate means as a sliding short in the cavity which is non-magnetic and metallic mounted perpendicular to the axis and movable towards and away from the chamber; (g) second magnets mounted on a sheet of high permeability magnetic material and adjacent to the plate means so as to provide magnetic cusps inside the chamber which aid in confining the plasma in the chamber; and wherein movement of the plate means and the probe in the coupler achieves the selected TE or TM mode of resonance of the radio frequency wave in the coupler and varies the resonance of the mode and wherein the radio frequency wave applied to the coupler creates and maintains the plasma at reduced pressures in the shape of an elongate plasma disk perpendicular to and surrounding the central longitudinal axis in the chamber which is confined in the chamber by the magnetic cusps.
Claim 4
Dependent Claim
290 words
A plasma generating apparatus which comprises: (a) a plasma source employing a radio frequency, including UHF or microwave, wave coupler which is metallic and non-magnetic and in the shape of a hollow cavity which can be excited in one or more TE or TM modes of resonance; (b) an electrically insulated chamber having a central longitudinal axis and mounted in the coupler; (c) gas supply means for providing a gas which is ionized to form the plasma in the insulated chamber; (d) a movable probe connected to and extending inside the coupler for coupling the radio frequency waves to the coupler; (e) a plurality of first magnets mounted around the longitudinal axis of the chamber on a ring of high permeability magnetic material so as to create magnetic cusps in the chamber which aid in confining the plasma in the chamber; (f) movable plate means as a sliding short in the cavity which is non-magnetic and metallic mounted perpendicular to the axis and movable towards and away from the chamber; (g) second magnets mounted on a sheet of high permeability magnetic material and adjacent to the plate means so as to provide magnetic cusps inside the chamber which aid in confining the plasma in the chamber; and wherein movement of the plate means and the probe in the coupler achieves the selected TE or TM mode of resonance of the radio frequency wave in the coupler and varies the resonance of the mode and wherein the radio frequency wave applied to the coupler creates and maintains the plasma at reduced pressures in the shape of an elongate plasma disk perpendicular to and surrounding the central longitudinal axis in the chamber which is confined in the chamber by the magnetic cusps.
Claim 5
Dependent Claim
24 words
The apparatus of claim 2 wherein an ion attracting means is mounted adjacent an opening in the chamber to remove ions from the chamber.
Claim 6
Dependent Claim
28 words
The apparatus of claim 2 wherein a support means is mounted adjacent to an opening in the chamber for providing a surface to be treated in the plasma.
Claim 7
Dependent Claim
31 words
The apparatus of claim 2 wherein some of the first magnets mounted around the cavity adjacent the chamber form connecting magnetic cusps with the second magnets on the moveable metal plate.
Claim 8
Dependent Claim
39 words
The apparatus of claim 5 wherein the first magnets are mounted inside the chamber and are covered with a thin non-magnetic material so as to seal the magnets inside the chamber from charged and energetic species of the plasma.
Claim 9
Dependent Claim
19 words
The apparatus of claim 2 wherein the second magnets are mounted on the moveable metal plate adjacent the chamber.
Claim 10
Dependent Claim
33 words
The apparatus of claim 2 wherein the second magnets are mounted on or adjacent to the moveable metal plate with a thin section of the metal plate between the magnets and the chamber.
Claim 11
Dependent Claim
13 words
The apparatus of claim 2 wherein the high magnetic permeable material is iron.
Claim 12
Dependent Claim
16 words
The apparatus of claim 2 wherein the second magnets and sheet essentially cover the metal plate.
Claim 13
Dependent Claim
28 words
The apparatus of claim 10 wherein the chamber has an opening and wherein additional magnets are mounted around the opening to provide a magnetic nozzle from the chamber.
Claim 14
Dependent Claim
38 words
The apparatus of claim 1 wherein the first and second magnets are permanent rare earth magnets having a field strength of between about 0.01 and 0.5 Tesla such that electron cyclotron resonance can be achieved in the chamber.
Claim 15
Dependent Claim
27 words
The apparatus of claim 1 wherein the magnets are electromagnets which provide a variable field strength and thus produces variable electron cyclotron resonance zones in the chamber.
Claim 16
Independent Claim
305 words
A method for forming a plasma which comprises: (a) providing plasma generating apparatus including a plasma source employing a radio frequency, including UHF or microwave, wave coupler of a non-magnetic metal in the shape of a hollow cavity which can be excited in one or more TE or TM modes of resonance, including an electrically insulated chamber having a central longitudinal axis and mounted in the coupler, including a gas supply means for providing a gas which is ionized to form the plasma in the chamber, including a movable plate means of a non-magnetic metal in the cavity mounted perpendicular to the axis of the chamber and moveable towards and away from the chamber as a sliding short, including a moveable probe connected to and extending inside the coupler for coupling the radio frequency waves to the coupler, wherein movement of the moveable plate means and the probe in the coupler achieves the selected TM or TE mode of resonance of the radio frequency wave in the coupler and varies the resonance of the mode and wherein the radio frequency wave applied to the coupler creates and maintains the plasma at reduced pressures in the shape of an elongate plasma disk perpendicular to and surrounding the central longitudinal axis in the chamber, the improvement which comprises: a plurality of first magnets mounted on the apparatus around the longitudinal axis of the chamber on a ring of high permeability magnetic material so a to create magnetic cusps in the chamber which aid in confining the plasma in the chamber; and second magnets mounted on the apparatus on a sheet of high permeability magnetic material so as to provide magnetic cusps inside the chamber which aid in confining the plasma in the chamber; and (b) forming the plasma disk in the chamber confined by the magnetic cusps.
Claim 17
Independent Claim
305 words
A method for forming a plasma which comprises: (a) providing plasma generating apparatus including a plasma source employing a radio frequency, including UHF or microwave, wave coupler of a non-magnetic metal in the shape of a hollow cavity which can be excited in one or more TE or TM modes of resonance, including an electrically insulated chamber having a central longitudinal axis and mounted in the coupler, including a gas supply means for providing a gas which is ionized to form the plasma in the chamber, including a movable plate means of a non-magnetic metal in the cavity mounted perpendicular to the axis of the chamber and moveable towards and away from the chamber as a sliding short, including a moveable probe connected to and extending inside the coupler for coupling the radio frequency waves to the coupler, wherein movement of the moveable plate means and the probe in the coupler achieves the selected TM or TE mode of resonance of the radio frequency wave in the coupler and varies the resonance of the mode and wherein the radio frequency wave applied to the coupler creates and maintains the plasma at reduced pressures in the shape of an elongate plasma disk perpendicular to and surrounding the central longitudinal axis in the chamber, the improvement which comprises: a plurality of first magnets mounted on the apparatus around the longitudinal axis of the chamber on a ring of high permeability magnetic material so a to create magnetic cusps in the chamber which aid in confining the plasma in the chamber; and second magnets mounted on the apparatus on a sheet of high permeability magnetic material so as to provide magnetic cusps inside the chamber which aid in confining the plasma in the chamber; and (b) forming the plasma disk in the chamber confined by the magnetic cusps.
Claim 18
Dependent Claim
36 words
The method of claim 14 wherein the magnets are permanent rare earth magnets having a field strength between about 0.01 and 0.5 Tesla and wherein the microwave frequency is between about 400 MegaHertz and 10 GigaHertz.
Claim 19
Dependent Claim
17 words
The method of claim 15 wherein the apparatus is operated at electron cyclotron resonance in the chamber.
Claim 20
Dependent Claim
20 words
The method of claim 15 wherein the field strength is about 875 gauss and the frequency is about 2.45 GigaHertz.
Claim 21
Dependent Claim
21 words
The method of claim 15 wherein the electron cyclotron resonance creates an accelerating electron cyclotron resonance surface entirely inside the chamber.
Claim 22
Dependent Claim
29 words
The method of claim 18 wherein the electron cyclotron resonance surface is positioned in the chamber by varying the strength and position of the magnets relative to the chamber.
Claim 23
Dependent Claim
30 words
The method of claim 16 wherein the electron cyclotron resonance facilitates generation of the plasma in the chamber at low pressures of less than about 10 microns in the chamber.
Claim 24
Dependent Claim
26 words
The method of claim 16 wherein the plasma generated in the chamber produce charged species having enhanced properties as a result of the electron cyclotron resonance.
Claim 25
Dependent Claim
16 words
The method of claim 14 wherein the magnets are electromagnets which provide a variable field strength.
Claim 26
Independent Claim
319 words
A method for forming a plasma which comprises: (a) providing a plasma generating apparatus which comprises a plasma source employing a radio frequency, including UHF or microwave, wave coupler which is metallic and non-magnetic and in the shape of a hollow cavity and which is excited in one or more TE or TM modes of resonance; an electrically insulated chamber having a central longitudinal axis and mounted in the coupler; gas supply means for providing a gas which is ionized to form the plasma in the insulated chamber; a plurality of first magnets mounted around the longitudinal axis of the chamber on a ring of high permeability magnetic material so as to create magnetic cusps in the chamber which aid in confining the plasma in the chamber; movable plate means in the cavity which is non-magnetic and metallic mounted perpendicular to the axis and movable towards and away from the chamber; second magnets mounted on a sheet of high permeability magnetic material to provide magnetic cusps inside the chamber which aid in confining the plasma in the chamber; and a movable probe connected to and extending inside the coupler for coupling the radio frequency waves to the coupler, wherein movement of the plate means and the probe in the coupler achieves the selected TE or TM mode of resonance of the radio frequency wave in the coupler and varies the resonance of the mode, wherein the radio frequency wave applied to the coupler creates and maintains the plasma at reduced pressures in the shape of an elongate plasma disk perpendicular to and surrounding the central longitudinal axis in the chamber which is confined in the chamber by the magnetic cusps and wherein the magnets have a field strength and position adjacent to or around the chamber sufficient to create electron cyclotron resonance in the chamber; and (b) forming the plasma disk in the chamber confined by the magnetic cusps.
Claim 27
Independent Claim
319 words
A method for forming a plasma which comprises: (a) providing a plasma generating apparatus which comprises a plasma source employing a radio frequency, including UHF or microwave, wave coupler which is metallic and non-magnetic and in the shape of a hollow cavity and which is excited in one or more TE or TM modes of resonance; an electrically insulated chamber having a central longitudinal axis and mounted in the coupler; gas supply means for providing a gas which is ionized to form the plasma in the insulated chamber; a plurality of first magnets mounted around the longitudinal axis of the chamber on a ring of high permeability magnetic material so as to create magnetic cusps in the chamber which aid in confining the plasma in the chamber; movable plate means in the cavity which is non-magnetic and metallic mounted perpendicular to the axis and movable towards and away from the chamber; second magnets mounted on a sheet of high permeability magnetic material to provide magnetic cusps inside the chamber which aid in confining the plasma in the chamber; and a movable probe connected to and extending inside the coupler for coupling the radio frequency waves to the coupler, wherein movement of the plate means and the probe in the coupler achieves the selected TE or TM mode of resonance of the radio frequency wave in the coupler and varies the resonance of the mode, wherein the radio frequency wave applied to the coupler creates and maintains the plasma at reduced pressures in the shape of an elongate plasma disk perpendicular to and surrounding the central longitudinal axis in the chamber which is confined in the chamber by the magnetic cusps and wherein the magnets have a field strength and position adjacent to or around the chamber sufficient to create electron cyclotron resonance in the chamber; and (b) forming the plasma disk in the chamber confined by the magnetic cusps.
Claim 28
Dependent Claim
26 words
The method of claim 23 wherein the apparatus has an ion attracting means adjacent an opening in the chamber and ions are removed from the plasma.
Claim 29
Dependent Claim
29 words
The method of claim 23 wherein the apparatus has a support means adjacent an opening in the chamber and a surface to be treated is provided in the plasma.
Claim 30
Dependent Claim
17 words
The method of claim 23 wherein plasma which is formed is used for plasma processing of substrates.
Claim 31
Dependent Claim
19 words
The method of claim 23 wherein the plasma formed has multimode excitation to provide a more uniform plasma discharge.
References Cited (Backward Citations)
US3230418A
Cited
EP0054621A1
Cited
US4598231A
Cited
US4507588A
Cited
US4585668A
Cited
US4611121A
Cited
US4559477A
Cited
US4631438A
Cited
US4630566A
Cited
EP0184812A2
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-02-22 | 1991-08-24 | 1992-02-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-22 | 1995-08-24 | 1996-02-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-22 | 1999-08-24 | 2000-02-23 | $7700.00 | Window Closed / Lapsed |