Plasma production device and method and RF driver circuit with adjustable duty cycle
First Claim
1. A method of making 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; and
controlling an average input power by modulating a duty cycle for operating the radio frequency power source.
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Accused Products
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 plasmas. Also disclosed is the choice for capacitance or an inductance value to provide tuning for the RF plasma source. There is also provided a method for rapidly switching the plasma between two or more power levels at a frequencies of about tens of Hz to as high as hundreds of KHz.
54 Citations
17 Claims
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1. A method of making a plasma source to eliminate the need for a matching circuit, the method comprising the steps of:
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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; and
controlling an average input power by modulating a duty cycle for operating the radio frequency power source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of operating a plasma source to eliminate the need for a matching circuit, the method comprising the steps of:
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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; and
modulating a spatial distribution of the plasma by changing a duty cycle for operating the radio frequency power source. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification