Impedance-Matching Network Using BJT Switches in Variable-Reactance Circuits
First Claim
1. A switch circuit comprising:
- a bipolar junction transistor comprising;
a collector terminal connected to a collector of the bipolar junction transistor, the collector terminal configured to pass a collector current with an alternating current component having a first amplitude;
a base terminal connected to a base of the bipolar junction transistor, the base terminal configured to pass a base current with an alternating current component having a second amplitude;
an emitter terminal connected to an emitter of the bipolar junction transistor, the emitter terminal configured to pass an emitter current with an alternating current component having a third amplitude;
a base-collector junction; and
a base-emitter junction; and
a biasing circuit that;
establishes an on-state of the bipolar junction transistor by forward biasing the base-emitter junction, wherein the second amplitude is greater than the third amplitude; and
establishes an off-state of the bipolar junction transistor by reverse biasing the base-emitter junction and the base-collector junction.
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Accused Products
Abstract
This disclosure describes systems, methods, and apparatuses for impedance-matching radio frequency power transmitted from a radio frequency generator to a plasma load in a semiconductor processing chamber. Impedance-matching can be performed via a match network having a variable-reactance circuit. The variable-reactance circuit can comprise one or more reactive elements all connected to a first terminal and selectively shorted to a second terminal via a switch. The switch can comprise a bipolar junction transistor (BJT) or insulated gate bipolar transistor (IGBT) controlled via bias circuitry. In an on-state, the BJT base-emitter junction is forward biased, and AC is conducted between a collector terminal and a base terminal. Thus, AC passes through the BJT primarily from collector to base rather than from collector to emitter. Furthermore, the classic match network topology used with vacuum variable capacitors can be modified such that voltages do not overload the BJT'"'"'s in the modified topology.
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Citations
21 Claims
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1. A switch circuit comprising:
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a bipolar junction transistor comprising; a collector terminal connected to a collector of the bipolar junction transistor, the collector terminal configured to pass a collector current with an alternating current component having a first amplitude; a base terminal connected to a base of the bipolar junction transistor, the base terminal configured to pass a base current with an alternating current component having a second amplitude; an emitter terminal connected to an emitter of the bipolar junction transistor, the emitter terminal configured to pass an emitter current with an alternating current component having a third amplitude; a base-collector junction; and a base-emitter junction; and a biasing circuit that; establishes an on-state of the bipolar junction transistor by forward biasing the base-emitter junction, wherein the second amplitude is greater than the third amplitude; and establishes an off-state of the bipolar junction transistor by reverse biasing the base-emitter junction and the base-collector junction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An impedance-matching apparatus comprising:
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at least one variable reactance element comprising; a first terminal; a second terminal; at least one reactive element connected to the first terminal; at least one switch circuit configured to selectively connect the at least one reactive element to the second terminal thereby altering a reactance between the first terminal and the second terminal, the at least one switch circuit comprising; a bipolar junction transistor having; an on-state, wherein a base-emitter junction is forward biased, and an AC component of a first current through a base terminal of the bipolar junction transistor is greater than an AC component of a second current through an emitter terminal of the bipolar junction transistor; and an off-state, wherein the base-emitter junction is reverse biased, and a base-collector junction is reverse biased; and a fixed impedance-matching section in cascade with the at least one variable reactance element and configured to be arranged in cascade with a plasma load, and comprising one or more shunt elements and one or more series elements, the one or more shunt elements and the one or more series elements being in a ladder network. - View Dependent Claims (16, 17, 18)
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19. An impedance-matching apparatus comprising:
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at least one variable reactance element comprising; a first terminal; a second terminal; at least one reactive element connected to the first terminal; at least one switch circuit configured to selectively connect the at least one reactive element to the second terminal thereby altering a reactance between the first terminal and the second terminal, the at least one switch circuit comprising; a bipolar junction transistor having; an on-state, wherein a base-emitter junction is forward biased, and an AC component of a first current through a base terminal of the bipolar junction transistor is greater than an AC component of a second current through an emitter terminal of the bipolar junction transistor; and an off-state, wherein the base-emitter junction is reverse biased, and a base-collector junction is reverse biased; and a fixed impedance-matching section in cascade with the at least one variable reactance element and configured to be arranged in cascade with a plasma load, and comprising at least two distinct Darlington sections.
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20. A method comprising:
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forward biasing a base-emitter junction of a bipolar junction transistor; conducting a first current through the bipolar junction transistor between a collector terminal of the bipolar junction transistor and a base terminal of the bipolar junction transistor, wherein the first current has an alternating current component with a first amplitude; and conducting a second current through the bipolar junction transistor between the collector terminal of the bipolar junction transistor and an emitter terminal of the bipolar junction transistor, wherein the second current has an alternating current component with a second amplitude, and wherein the second amplitude is less than the first amplitude, and the second amplitude is equal to or greater than zero.
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21. A switch circuit comprising:
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means for forward biasing a base-emitter junction of a bipolar junction transistor; means for conducting a first current through the bipolar junction transistor between a collector terminal of the bipolar junction transistor and a base terminal of the bipolar junction transistor, wherein the means for conducting the first current includes means for conducting the first current with an alternating current component with a first amplitude; and means for conducting a second current through the bipolar junction transistor between the collector terminal of the bipolar junction transistor and an emitter terminal of the bipolar junction transistor, wherein the means for conducting the second current includes means for conducting the second current with an alternating current component with a second amplitude, and wherein the second amplitude is less than the first amplitude, and the second amplitude is equal to or greater than zero.
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Specification