Stabilized oscillator circuit for plasma density measurement
AssigneeTokyo Electron Limited
InventorsMurray D. Sirkis, Joseph T. Verdeyen
Life of this patent
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Abstract
A method and system for controlling electron densities in a plasma processing system. By applying a dither voltage and a correction voltage to a voltage-controlled oscillator, electron (plasma) density of a plasma processing system (acting as an open resonator) may be measured and controlled as part of a plasma-based process.
Claims4
In a circuit for controlling a plasma chamber with a voltage controlled oscillator controlled by a feedback signal, the improvement comprising:
- a dither voltage source for generating a dither voltage;
- an adder for adding the dither control voltage source to the feedback signal and for applying an output of the adder to a voltage control input of the voltage controlled oscillator.
In a circuit for controlling a plasma chamber with a voltage controlled oscillator controlled by a feedback signal, wherein the plasma chamber acts as an open resonator, the improvement comprising:
- a dither voltage source for generating a dither voltage;
- an adder for adding the dither control voltage source to the feedback signal and for applying an output of the adder to a voltage control input of the voltage controlled oscillator.
Dependencies are inferred from the claim text.