Bipolar plasma source, plasma sheet source, and effusion cell utilizing a bipolar plasma source
First Claim
1. A plasma source, comprising:
- a first hollow cathode structure and a second hollow cathode structure;
an AC power source connected to each of said hollow cathode structures and arranged to apply a negative voltage to a respective one of said hollow cathode structures that is sufficiently negative relative to a voltage of the other of said hollow cathode structures to cause plasma generation, said negative voltage being alternatingly applied to each of the hollow cathode structures, wherein said AC power source is arranged such that, when said negative voltage is applied to the first hollow cathode structure and a plasma is generated therein, the second of the hollow cathode structures serves as an anode to attract electrons from the first of the two hollow cathode structures and thereby complete an electrical circuit with the power source, and wherein when a polarity of voltage applied to the first hollow cathode structure reverses, another plasma is generated in said second hollow cathode structure, and the first hollow cathode structure serves as an anode to attract electrons from the second hollow plasma structure and thereby again complete the electrical circuit with the power source.
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Abstract
A plasma source includes a structure made up of two hollow cathode shapes connected to a bipolar AC power supply. The bipolar power supply alternately drives one hollow cathode to a negative voltage while the opposite hollow cathode is driven to a positive voltage. As one of the two hollow cathode shapes is driven negative, the hollow cathode discharge forms within the corresponding cavity. The other cathode then forms an anode, causing electrons to escape the plasma and travel to the other side, completing the electric circuit. The plasma generator thus formed may be used as a heat source for an effusion cell to form a plasma from a reactant gas, or to increase the reactivity of gas situated between a vacuum deposition source and a substrate to be coated.
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Citations
30 Claims
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1. A plasma source, comprising:
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a first hollow cathode structure and a second hollow cathode structure;
an AC power source connected to each of said hollow cathode structures and arranged to apply a negative voltage to a respective one of said hollow cathode structures that is sufficiently negative relative to a voltage of the other of said hollow cathode structures to cause plasma generation, said negative voltage being alternatingly applied to each of the hollow cathode structures, wherein said AC power source is arranged such that, when said negative voltage is applied to the first hollow cathode structure and a plasma is generated therein, the second of the hollow cathode structures serves as an anode to attract electrons from the first of the two hollow cathode structures and thereby complete an electrical circuit with the power source, and wherein when a polarity of voltage applied to the first hollow cathode structure reverses, another plasma is generated in said second hollow cathode structure, and the first hollow cathode structure serves as an anode to attract electrons from the second hollow plasma structure and thereby again complete the electrical circuit with the power source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of generating a plasma, comprising the steps of:
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providing first and second hollow cathode structures arranged such that free electrons can pass between the structures when a differential voltage is applied to the structures, and applying the differential voltage to the first and second hollow cathode structures by applying an alternating current to the hollow cathode structures in such a manner that the power supply initially drives the first hollow cathode shape to a negative voltage, allowing plasma formation while the second hollow cathode shape is driven to a positive voltage in order to serve as an anode for the voltage application circuit, and then drives the first hollow cathode shape to a positive voltage, reversing the roles of plasma generator and anode. - View Dependent Claims (15, 16, 17, 18, 19)
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20. An effusion source, comprising:
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an effusion cell having a lid, said lid having an exit through which vapor exits the effusion source;
a plasma generator arranged in said lid adjacent said exit, said plasma generator serving as a heat source for said effusion cell. - View Dependent Claims (21, 22, 23, 24, 25)
a first hollow cathode structure extending along one side of said exit and a second hollow cathode structure extending along an opposite side of said exit;
an AC power source connected to each of said hollow cathode structures such that a negative voltage sufficient to cause plasma generation is alternatingly applied to each of the hollow cathode structures, wherein said AC power source is arranged such that, when said negative voltage is applied to the first hollow cathode structure and a plasma is generated therein, the second of the hollow cathode structures serves as an anode to attract electrons from the first of the two hollow cathode structures and thereby complete an electrical circuit with the power source, wherein when a polarity of voltage applied to the first hollow cathode structure reverses, another plasma is generated in said second hollow cathode structure, and the first hollow cathode structure serves as an anode to attract electrons from the second hollow plasma structure and thereby again complete the electrical circuit with the power source, and wherein said plasma serves as a heat source for vapor exiting through said exit.
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22. An effusion source as claimed in claim 21, wherein said hollow cathode structures are in the form of grooves extending along facing surfaces of the hollow cathode structures.
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23. An effusion source as claimed in claim 21, wherein said AC power source is a mid-frequency generator having a midfrequency output of on the order of 10 kHz to 500 kHz.
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24. An effusion source as claimed in claim 20, wherein said plasma serves as a heat source for an evaporant in said cell.
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25. An effusion source as claimed in claim 20, wherein said plasma serves as a heat source for structures which transfer said heat to said evaporant and ionize said evaporant to increase the reactivity of said evaporant.
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26. A plasma sheet source, comprising:
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a first hollow cathode structure including a first groove and a second hollow cathode structure including a second groove facing and parallel to said first groove;
an AC power source connected to each of said hollow cathode structures such that a negative voltage sufficient to cause plasma generation is alternatingly applied to each of the hollow cathode structures; and
a magnetic structure on each side of each of said grooves, wherein said AC power source is arranged such that, when said negative voltage is applied to the first hollow cathode structure and a plasma is generated therein, the second of the hollow cathode structures serves as an anode to attract electrons from the first of the two hollow cathode structures and thereby complete an electrical circuit with the power source, wherein when a polarity of voltage applied to the first hollow cathode structure reverses, another plasma is generated in said second hollow cathode structure, and the first hollow cathode structure serves as an anode to attract electrons from the second hollow plasma structure and thereby again complete the electrical circuit with the power source, and wherein said magnetic structures generate a magnetic field that confines said electrons to paths extending between said grooves. - View Dependent Claims (27, 28, 29, 30)
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Specification