Plasma production device and method and RF driver circuit
AssigneePlasma Control Systems, LLC
InventorsJohn D. Evans, Patrick A. Pribyl
Life of this patent
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Abstract
An RF driver circuit and an orthogonal antenna assembly/configuration, are disclosed as part of a method and system for generating high density plasma. The antenna assembly is an orthogonal antenna system that may be driven by any RF generator/circuitry with suitable impedance matching to present a low impedance. The disclosed RF driver circuit uses switching type amplifier elements and presents a low output impedance. The disclosed low-output impedance RF driver circuits eliminate the need for a matching circuit for interfacing with the inherent impedance variations associated with plasma. Also disclosed is the choice for capacitance or an inductance value to provide tuning for the RF plasma source.
Claims41
A plasma generator system comprising:
- at least one plasma source comprising
- a plasma source chamber, and
- an antenna having a plurality of antenna elements, each comprising at least one loop, the loop having a loop axis, the plurality of antenna elements arranged about a common axis such that each loop axis is substantially orthogonal to the common axis,
- wherein the antenna is positioned such that it can form an electromagnetic field within the chamber;
- and
- at least one radio frequency power source coupled to the plurality of antenna elements.
A plasma generator system comprising:
- at least one plasma source comprising
- a plasma source chamber, and
- an antenna positioned such that it is capable of forming an electromagnetic field within the chamber;
- and
- at least one radio frequency power source;
- at least one reactive circuit;
- wherein when a plasma is present in the chamber, the shift in the resonant frequency of the combination of the reactive circuit, antenna, and plasma is less than the broadening of the resonant frequency peak of the combination;
- and
- wherein power delivered from the power source is substantially insensitive to the shift in the resonant frequency response.
A method for generating plasma comprising the steps of:
- producing radio frequency power by a radio frequency power source;
- coupling the radio frequency power to at least one antenna via at least one reactive circuit;
- wherein the antenna is positioned such that it is capable of forming an electromagnetic field within a plasma source chamber;
- and
- wherein when a plasma is present in the chamber, the shift in the resonant frequency of the combination of the reactive circuit, antenna, and plasma is less than the broadening of a resonant frequency peak of the combination;
- and
- wherein power delivered from the power source is substantially insensitive to the shift in the resonant frequency response.
A method of designing a plasma source to eliminate the need for a matching circuit, the method comprising the steps of:
- providing a low output impedance to a radio frequency power source;
- selecting a capacitance coupling the radio frequency power source to at least one set of antenna loops such that the capacitance and the antenna loops without a plasma have a resonant frequency that is about equal to a specified frequency for the plasma.
Dependencies are inferred from the claim text.