Plasma reactor with plasma load impedance tuning for engineered transients by synchronized modulation of a source power or bias power RF generator
First Claim
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1. A plasma reactor including a chamber for processing a workpiece, comprising:
- plural impedance matches and plural RF plasma power generators coupled to deliver respective RF plasma powers into said chamber through respective ones of said impedance matches;
a controller for generating a time-varying modulation control signal corresponding to a desired process transient cycle and an amplitude modulator coupled to modulate the output of a first one of said generators in response to said time-varying modulation control signal; and
a follower modulator coupled to modulate the output of a second one of said generators in response to said time-varying modulation control signal;
wherein;
said first generator provides a signal representing a measured level of RF power reflected back to the first generator, said signal being coupled to said controller; and
said controller being programmed to alter the degree of modulation of said second generator to minimize said measured level of RF power reflected back to said first generator.
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Abstract
In a plasma reactor employing source and bias RF power generators, plasma is stabilized against an engineered transient in the output of either the source or bias power generator by a compensating modulation in the other generator.
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Citations
8 Claims
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1. A plasma reactor including a chamber for processing a workpiece, comprising:
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plural impedance matches and plural RF plasma power generators coupled to deliver respective RF plasma powers into said chamber through respective ones of said impedance matches; a controller for generating a time-varying modulation control signal corresponding to a desired process transient cycle and an amplitude modulator coupled to modulate the output of a first one of said generators in response to said time-varying modulation control signal; and a follower modulator coupled to modulate the output of a second one of said generators in response to said time-varying modulation control signal; wherein; said first generator provides a signal representing a measured level of RF power reflected back to the first generator, said signal being coupled to said controller; and said controller being programmed to alter the degree of modulation of said second generator to minimize said measured level of RF power reflected back to said first generator. - View Dependent Claims (2, 3, 4, 5)
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6. A plasma reactor including a chamber with gas distribution apparatus for processing a workpiece, comprising:
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an RF plasma source power applicator; a source power impedance match and an RF plasma source power generator coupled to said RF plasma source power applicator through said source power impedance match; a controller for providing a time-varying modulation control signal corresponding to a desired process transient cycle and an amplitude modulator coupled to modulate the output of said source power generator in response to said time-varying modulation control signal; and an RF bias power generator operatively coupled to deliver RF bias power to said workpiece, and a follower modulator coupled to modulate the output of said RF bias power generator in response to said time-varying modulation control signal; wherein; said RF bias power generator has a frequency at which over 80% of RF power contributes to plasma sheath thickness; said source power generator provides a signal representing a measured level of RF power reflected back to the source power generator, said signal being coupled to said controller; and said controller being programmed to alter the degree of modulation of said bias power generator to minimize said measured level of RF power reflected back to said generator. - View Dependent Claims (7, 8)
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Specification