Patent US5273610A successfully refreshed from Google Patents.
US5273610A
Expired / Lapsed
US
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Apparatus and method for determining power in plasma processing
Assignee: ASSOCIATED INSTITUTIONS FOR MEDICAL SCIENCES Inc
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Filing: 1992-06-23
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Granted: 1993-12-28
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Expires: 2012-06-23
Abstract
Abstract An apparatus and method including a current sensor having a radiation emitter, such as an electrical resistor, and a radiation detector, such as an infrared detector, for sensing current flowing to a plasma generating electrode from a radio frequency (RF) power source. The resistor may include a high emissivity infrared coating to enhance efficiency of the current sensor. The infrared detector provides a highly accurate indication of the average or root-mean-square current delivered to the plasma generating electrode without introducing parasitic capacitance into the measurement, or sensing, circuit. A voltage sensor and a second current sensor, such as a torroidal current sensor, provide the voltage and phase angle of the current delivered to the plasma generating electrode to thereby permit calculation of the power delivered to the plasma generating electrode. A processor controls the RF source responsive to the sensed average current, sensed voltage, and sensed phase angle of the current.
Inventors
- 👤 John H. Thomas, III
- 👤 Bawa Singh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 13:08
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/32; H01J37/32917; H01J37/32935
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
90 words
A radio frequency (RF) plasma processing apparatus comprising: a processing chamber; a plasma generating electrode positioned in said processing chamber; a radio frequency (RF) source connected to said plasma generating electrode; and an electrical current sensor comprising radiation emitter means operatively connected to said plasma generating electrode for emitting radiation responsive to electrical current delivered to said plasma generating electrode, and radiation detector means spaced apart from said radiation emitter means for detecting radiation emitted therefrom to produce a signal relating to electrical current delivered to said plasma generating electrode.
Claim 2
Dependent Claim
90 words
A radio frequency (RF) plasma processing apparatus comprising: a processing chamber; a plasma generating electrode positioned in said processing chamber; a radio frequency (RF) source connected to said plasma generating electrode; and an electrical current sensor comprising radiation emitter means operatively connected to said plasma generating electrode for emitting radiation responsive to electrical current delivered to said plasma generating electrode, and radiation detector means spaced apart from said radiation emitter means for detecting radiation emitted therefrom to produce a signal relating to electrical current delivered to said plasma generating electrode.
Claim 3
Dependent Claim
28 words
An apparatus according to claim 1 wherein said radiation emitter means comprises an electrical resistor electrically connected in series between said RF source and said plasma generating electrode.
Claim 4
Dependent Claim
45 words
An apparatus according to claim 2 wherein said electrical resistor has a relatively low resistance compared to the resistance of plasma generated in said processing chamber so that only a relatively insubstantial portion of power from said RF source is dissipated by said electrical resistor.
Claim 5
Dependent Claim
19 words
An apparatus according to claim 3 wherein said electrical resistor has a resistance of less than about 0.5 ohms.
Claim 6
Dependent Claim
27 words
An apparatus according to claim 2 wherein said electrical resistor has a strip-like shape and a relatively short length so as to reduce the electrical inductance thereof.
Claim 7
Dependent Claim
27 words
An apparatus according to claim 2 further comprising a high emissivity infrared coating on said electrical resistor; and wherein said radiation detector means comprises an infrared detector.
Claim 8
Dependent Claim
36 words
An apparatus according to claim 2 wherein said electrical current sensor further comprises an evacuated housing surrounding said electrical resistor for thermally insulating same; and wherein said evacuated housing includes a radiation transmissive window portion therein.
Claim 9
Dependent Claim
48 words
An apparatus according to claim 7 further comprising a coaxial transmission line connecting said RF source to said plasma generating electrode; and wherein said current sensor further comprises a pair of coaxial connectors carried by said housing and electrically connected to respective opposite ends of said electrical resistor.
Claim 10
Dependent Claim
46 words
An apparatus according to claim 1 wherein said radiation emitter means is positioned in said processing chamber adjacent said plasma generating electrode; wherein said processing chamber includes a radiation transmissive window portion therein; and wherein said radiation detector means is positioned outside of said processing chamber.
Claim 11
Dependent Claim
156 words
A radio frequency (RF) plasma processing apparatus comprising: a processing chamber; a plasma generating electrode positioned in said processing chamber; an radio frequency (RF) source connected to said plasma generating electrode; a first electrical current sensor comprising radiation emitter means operatively connected to said plasma generating electrode for emitting radiation responsive to electrical current delivered to said plasma generating electrode, and radiation detector means spaced apart from said radiation emitter means for detecting radiation emitted therefrom to produce a signal relating to electrical current delivered to said plasma generating electrode; a voltage sensor operatively connected to said plasma generating electrode; a second electrical current sensor operatively connected to said plasma generating electrode for sensing the phase angle of electrical current delivered thereto; and processor means operatively connected to said voltage sensor, said radiation detector means of said first electrical current sensor, and said second electrical current sensor for determining power delivered to said plasma generating electrode.
Claim 12
Dependent Claim
156 words
A radio frequency (RF) plasma processing apparatus comprising: a processing chamber; a plasma generating electrode positioned in said processing chamber; an radio frequency (RF) source connected to said plasma generating electrode; a first electrical current sensor comprising radiation emitter means operatively connected to said plasma generating electrode for emitting radiation responsive to electrical current delivered to said plasma generating electrode, and radiation detector means spaced apart from said radiation emitter means for detecting radiation emitted therefrom to produce a signal relating to electrical current delivered to said plasma generating electrode; a voltage sensor operatively connected to said plasma generating electrode; a second electrical current sensor operatively connected to said plasma generating electrode for sensing the phase angle of electrical current delivered thereto; and processor means operatively connected to said voltage sensor, said radiation detector means of said first electrical current sensor, and said second electrical current sensor for determining power delivered to said plasma generating electrode.
Claim 13
Dependent Claim
28 words
An apparatus according to claim 10 wherein said radiation emitter means comprises an electrical resistor electrically connected in series between said RF source and said plasma generating electrode.
Claim 14
Dependent Claim
45 words
An apparatus according to claim 11 wherein s electrical resistor has a relatively low resistance compared to the resistance of plasma generated in said processing chamber so that only a relatively insubstantial portion of power from said RF source is dissipated by said electrical resistor.
Claim 15
Dependent Claim
19 words
An apparatus according to claim 12 wherein said electrical resistor has a resistance of less than about 0.5 ohms.
Claim 16
Dependent Claim
27 words
An apparatus according to claim 11 wherein said electrical resistor has a strip-like shape and a relatively short length so as to reduce the electrical inductance thereof.
Claim 17
Dependent Claim
27 words
An apparatus according to claim 11 further comprising a high emissivity infrared coating on said electrical resistor; and wherein said radiation detector means comprises an infrared detector.
Claim 18
Dependent Claim
37 words
An apparatus according to claim 11 wherein said first electrical current sensor further comprises an evacuated housing surrounding said electrical resistor for thermally insulating same; and wherein said evacuated housing includes a radiation transmissive window portion therein.
Claim 19
Dependent Claim
51 words
An apparatus according to claim 16 further comprising a coaxial transmission line connected between said RF source and said plasma generating electrode; and wherein said first electrical current sensor further comprises a pair of coaxial connectors carried by said housing and electrically connected to respective opposite ends of said electrical resistor.
Claim 20
Dependent Claim
17 words
An apparatus according to claim 10 wherein said second electrical current sensor comprises a torroidal current sensor.
Claim 21
Dependent Claim
30 words
An apparatus according to claim 10 wherein said processor means includes means for controlling said RF source within a predetermined range responsive to power delivered to said plasma generating electrode.
Claim 22
Dependent Claim
46 words
An apparatus according to claim 10 wherein said radiation emitter means is positioned in said processing chamber adjacent said plasma generating electrode; wherein said processing chamber includes a radiation transmissive window portion therein; and wherein said radiation detector means is positioned outside of said processing chamber.
Claim 23
Dependent Claim
103 words
An electrical current sensor adapted for use with a radio frequency (RF) plasma processing apparatus including an RF generator connected to a plasma generating electrode through a matching network, the plasma generating electrode being positioned within a processing chamber, said electrical current sensor comprising: an electrical resistor adapted to be electrically connected in series between the RF generator and the plasma generating electrode for emitting radiation responsive to electrical current flowing through said electrical resistor; and a radiation detector positioned in spaced apart relation from said electrical resistor for sensing radiation emitted therefrom to produce a signal relating to electrical current flowing therethrough.
Claim 24
Dependent Claim
103 words
An electrical current sensor adapted for use with a radio frequency (RF) plasma processing apparatus including an RF generator connected to a plasma generating electrode through a matching network, the plasma generating electrode being positioned within a processing chamber, said electrical current sensor comprising: an electrical resistor adapted to be electrically connected in series between the RF generator and the plasma generating electrode for emitting radiation responsive to electrical current flowing through said electrical resistor; and a radiation detector positioned in spaced apart relation from said electrical resistor for sensing radiation emitted therefrom to produce a signal relating to electrical current flowing therethrough.
Claim 25
Dependent Claim
45 words
An apparatus according to claim 21 wherein said electrical resistor has a relatively low resistance compared to the resistance of plasma generated in said processing chamber so that only a relatively insubstantial portion of power from said RF source is dissipated by said electrical resistor.
Claim 26
Dependent Claim
22 words
An electrical current sensor according to claim 22 wherein said electrical resistor has a resistance of not greater than about 0.5 ohms.
Claim 27
Dependent Claim
29 words
An electrical current sensor according to claim 21 wherein said electrical resistor has a strip-like shape and a relatively short length so as to reduce the electrical inductance thereof.
Claim 28
Dependent Claim
28 words
An electrical current sensor according to claim 21 further comprising a high infrared emissivity coating on said electrical resistor; and wherein said radiation detector comprises an infrared detector.
Claim 29
Dependent Claim
25 words
An electrical current sensor according to claim 21 further comprising a housing surrounding said electrical resistor, said housing including a radiation transmissive window portion therein.
Claim 30
Dependent Claim
21 words
An electrical current sensor according to claim 26 wherein said housing is an evacuated housing for thermally insulating said electrical resistor.
Claim 31
Dependent Claim
30 words
An electrical current sensor according to claim 26 further comprising a pair of coaxial connectors carried by said housing and electrically connected to respective opposite ends of said electrical resistor.
Claim 32
Dependent Claim
44 words
An electrical current sensor according to claim 26 further comprising a pair of electrically conductive mounting supports positioned within said housing and mounting said electrical resistor therebetween so that said electrical resistor and said mounting supports are positioned in spaced relation from said housing.
Claim 33
Dependent Claim
45 words
An electrical current sensor according to claim 29 wherein said housing is electrically conductive; and wherein the spacing between said housing and said electrical resistor and the spacing between said housing and said pair of mounting supports are each selected to provide a predetermined impedance.
Claim 34
Independent Claim
74 words
A method for determining the current delivered to a plasma generating electrode from a radio frequency (RF) source, said method comprising the steps of: connecting an electrical resistor in series between the plasma generating electrode and the RF source, the electrical resistor emitting radiation responsive to electrical current flowing therethrough; and sensing the emitted radiation from the electrical resistor to thereby produce a signal related to electrical current delivered to the plasma generating electrode.
Claim 35
Independent Claim
74 words
A method for determining the current delivered to a plasma generating electrode from a radio frequency (RF) source, said method comprising the steps of: connecting an electrical resistor in series between the plasma generating electrode and the RF source, the electrical resistor emitting radiation responsive to electrical current flowing therethrough; and sensing the emitted radiation from the electrical resistor to thereby produce a signal related to electrical current delivered to the plasma generating electrode.
Claim 36
Dependent Claim
58 words
A method according to claim 31 further comprising the steps of: sensing the voltage of the plasma generating electrode; sensing the phase angle of the current to the plasma generating electrode; and determining the power delivered to the plasma generating electrode based upon the voltage, the current, and the phase angle of the current relative to the voltage.
Claim 37
Dependent Claim
32 words
A method according to claim 32 further comprising the step of controlling the RF source within a predetermined output range responsive to the thus determined power delivered to the plasma generating electrode.
Claim 38
Dependent Claim
25 words
A method according to claim 31 wherein the step of sensing the emitted radiation from the electrical resistor comprises sensing the infrared radiation emitted therefrom.
Claim 39
Dependent Claim
54 words
A method according to claim 31 wherein the step of connecting the electrical resistor in series with the RF source and the plasma generating electrode comprises the step of positioning the electrical resistor closely adjacent the plasma generating electrode to thereby obtain a relatively accurate sensing of current delivered to the plasma generating electrode.
Claim 40
Dependent Claim
80 words
A method according to claim 31 wherein the RF source comprises an RF generator and a matching network connected thereto; and further comprising the steps of connecting a second electrical resistor in series between the RF generator and the matching network, the electrical resistor emitting radiation responsive to a current flowing therethrough, and sensing the emitted radiation from the second electrical resistor to thereby produce a signal related to the current delivered to the matching network from the RF generator.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-12-27 | 1997-06-28 | 1997-12-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-12-27 | 2001-06-28 | 2001-12-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-12-27 | 2005-06-28 | 2005-12-28 | $7700.00 | Window Closed / Lapsed |