System for characterizing AC properties of a processing plasma
First Claim
1. A method of characterizing a plasma being subjected to an alternating power transmission comprising the steps of:
- a. accepting said alternating power transmission as an input;
b. sensing at least two signals from said alternating power transmission;
c. deriving at least three alternating signals from said sensed signals;
d. measuring at least three scalar values from said alternating signals wherein each of said scalar values are representative of the magnitude of the alternating signals;
e. manipulating said measured scalar values as variable inputs to characterize the plasma; and
f. passing a substantial portion of said alternating power transmission through to said plasma.
1 Assignment
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Accused Products
Abstract
A probe to be inserted in-line in an AC plasma processing system allows accurate, real time determination of plasma parameters such as power and complex impedance over a broad dynamic range. Any need to know power output from a source is avoided and signals are selected to optimize accuracy such that only two alternating signals need be sensed for many applications. Signals are selected such that magnitudes of simple alternating signals can be easily measured as scalar values in a fashion that affords the use of these values to completely characterize the power actually delivered to the processing plasma and its complex impedance in real time. Plasma characterization can be limited to only specific frequencies for more accurate determination. Microstrip directional couplers are used to sense signals from the power transmission. These signals are then utilized to derive simple alternating signals representative of power or voltage. Three or more scalar values representative of the magnitude of the alternating signals and their combination serve as the variable inputs to determine complex reflection coefficient or impedance using known formulas. Use of a sign bit detector or assumptions with respect to the processing plasma is disclosed for complete characterization of the plasma in an efficient manner.
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Citations
56 Claims
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1. A method of characterizing a plasma being subjected to an alternating power transmission comprising the steps of:
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a. accepting said alternating power transmission as an input; b. sensing at least two signals from said alternating power transmission; c. deriving at least three alternating signals from said sensed signals; d. measuring at least three scalar values from said alternating signals wherein each of said scalar values are representative of the magnitude of the alternating signals; e. manipulating said measured scalar values as variable inputs to characterize the plasma; and f. passing a substantial portion of said alternating power transmission through to said plasma. - View Dependent Claims (2, 3, 4, 5, 6, 10)
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7. A method of characterizing a plasma being subjected to an alternating power transmission comprising the steps of:
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a. accepting said alternating power transmission; b. sensing a first signal from said alternating power transmission; c. deriving a first alternating signal from said first signal; d. measuring a first scalar value from said first alternating signal wherein said first scalar value is representative of the magnitude of said first alternating signal; e. sensing a second signal from said alternating power transmission; f. deriving a second alternating signal from said second signal; g. measuring a second scalar value from said second alternating signal wherein said second scalar value is representative of the magnitude of said second alternating signal; h. combining said first and said second alternating signals to create a third alternating signal; i. measuring a third scalar value representative of the magnitude of said third alternating signal; j. manipulating said first, second, and third scalar values to characterize said plasma; and k. passing a substantial portion of said alternating power transmission through to said plasma. - View Dependent Claims (8, 9)
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11. A method of characterizing a plasma being subjected to an alternating power transmission comprising the steps of:
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a. accepting said alternating power transmission; b. sensing a first signal from said alternating power transmission wherein said first signal is representative of the sum of a voltage across said plasma and a multiple of the current passing through to said plasma; c. deriving a first alternating signal from said first signal; d. limiting the content of said first alternating signal to that of only a specific frequency; e. measuring a first scalar value from said first alternating signal wherein said first scalar value is representative of the magnitude of said first alternating signal; f. sensing a second signal from said alternating power transmission wherein said second alternating signal is representative of the difference between said voltage across said plasma and said multiple of the current passing through to said plasma; g. deriving a second alternating signal from said second signal; h. limiting the content of said second alternating signal to that of only said specific frequency; i. measuring a second scalar value from said second alternating signal wherein said second scalar value is representative of the magnitude of said second alternating signal; j. ascertaining a third alternating signal; k. measuring a third scalar value from said third alternating signal wherein said third scalar value is representative of the magnitude of said third alternating signal; l. manipulating said first, second, and third scalar values to characterize said plasma; and m. passing a substantial portion of said alternating power transmission through to said plasma. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A circuit to characterize a plasma being subjected to an alternating power transmission comprising:
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a. a means for accepting a power transmission; b. a means for sensing at least two signals from said power transmission provided by said means for accepting; c. a means for deriving at least three alternating signals from said signals provided by said means for sensing; d. a means for measuring at least three scalar values from said alternating signals wherein said scalar values are representative of the magnitude of the alternating signals; e. a means for manipulating said measured scalar values as variable inputs to characterize the plasma; and f. a means for passing a substantial portion of said power transmission from said means for accepting to said plasma. - View Dependent Claims (28, 29, 30, 31, 32, 34, 37, 39, 40, 41, 42, 45, 47, 48, 49, 50)
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33. A circuit to characterize a plasma being subjected to an alternating power transmission comprising:
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a. a means for accepting a power transmission; b. a means for sensing a first signal from said power transmission provided by said means for accepting; c. a means for deriving a first alternating signal from said first signal provided by said means for sensing said first signal; d. a means for measuring a first scalar value representative of the magnitude of said first alternating signal; e. a means for sensing a second signal from said power transmission provided by said means for accepting; f. a means for deriving a second alternating signal from said second signal provided by said means for sensing said second signal; g. a means for measuring a second scalar value representative of the magnitude of said second alternating signal; h. a means for combining said first and said second alternating signals to create a third alternating signal; i. a means for measuring a third scalar value representative of the magnitude of said third alternating signal; j. a means for manipulating said measured scalar values as variable inputs to characterize the plasma; and k. a means for passing a substantial portion of said power transmission from said means for accepting to said plasma. - View Dependent Claims (35, 36, 38, 43, 44, 46, 51, 52, 53, 54, 55, 56)
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Specification