Method of and apparatus for controlling reactive impedances of a matching network connected between an RF source and an RF plasma processor
First Claim
1. A method of supplying an r.f. field to a plasma in a vacuum plasma chamber processing a workpiece, the r.f. field being supplied to the plasma by a reactive impedance element connected via a matching network to an r.f. source, the r.f. field having a frequency and power level sufficient to ignite the gas into the plasma and to maintain the plasma, the matching network including first and second variable reactances that control loading of the source and tuning a load including the reactive impedance element and the plasma to the source, the method comprising (1) determining the amount the first variable reactance is to change for each unit change of the second variable reactance to attain the best match between the impedances seen looking into and out of output terminals of the r.f. source by changing the values of the first and second variable reactances, and (2) then varying the values of the first and second variable reactances based on the determination made in step (1) until the best impedance match between the impedances seen looking into and out of output terminals of the r.f. source is attained.
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Accused Products
Abstract
An r.f. field is supplied by a reactive impedance element to a plasma in a vacuum plasma processing chamber. The element and source are connected via a matching network including first and second variable reactances that control loading of the source and tuning a load, including the reactive impedance element and the plasma, to the source. The values of the first and second variable reactances are changed to determine the amount the first variable reactance is to change for each unit change of the second variable reactance to attain the best match between the impedances seen looking into and out of output terminals of the r.f. source. Then the values of the first and second variable reactances are varied simultaneously based on the determination until the best impedance match between the impedances seen looking into and out of output terminals of the r.f. source is attained.
121 Citations
35 Claims
- 1. A method of supplying an r.f. field to a plasma in a vacuum plasma chamber processing a workpiece, the r.f. field being supplied to the plasma by a reactive impedance element connected via a matching network to an r.f. source, the r.f. field having a frequency and power level sufficient to ignite the gas into the plasma and to maintain the plasma, the matching network including first and second variable reactances that control loading of the source and tuning a load including the reactive impedance element and the plasma to the source, the method comprising (1) determining the amount the first variable reactance is to change for each unit change of the second variable reactance to attain the best match between the impedances seen looking into and out of output terminals of the r.f. source by changing the values of the first and second variable reactances, and (2) then varying the values of the first and second variable reactances based on the determination made in step (1) until the best impedance match between the impedances seen looking into and out of output terminals of the r.f. source is attained.
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10. A method of supplying an r.f. field to a plasma in a vacuum plasma chamber processing a workpiece, the r.f. field being supplied to the plasma by a reactive impedance element connected via a matching network to an r.f. source, the r.f. field having a frequency and power level sufficient to ignite the gas into the plasma and to maintain the plasma, the matching network including first and second variable reactances that control loading of the source and tuning a load including the reactive impedance element and the plasma to the source, the method comprising:
- (1) changing the value of only the first of said variable reactances until the best impedance match between the impedances seen looking into and out of output terminals of the r.f. source is attained;
(2) then changing only the value of the second of said variable reactances until the best impedance match between the impedances seen looking into and out of output terminals of the r.f. source is attained;
(3) then changing the value of only the first of said variable reactances until the best impedance match between the impedances seen looking into and out of output terminals of the r.f. source is attained;
(4) from indications of the values of the first and second variable reactances at the completion of steps (1) and (3), determining the amount the first variable reactance is to change for each unit change in the value of the second variable reactance; and
(5) then varying the values of the first and second variable reactances based on the determination of step (4) and until the best possible impedance match between the impedances seen looking into and out of output terminals of the r.f. source is attained. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
- (1) changing the value of only the first of said variable reactances until the best impedance match between the impedances seen looking into and out of output terminals of the r.f. source is attained;
- 23. Apparatus for supplying an r.f. field to a plasma in a vacuum plasma chamber for processing a workpiece, comprising a reactive impedance element for supplying the r.f. field to the plasma, the reactive impedance element being connected via a matching network to an r.f. source, the r.f. field having a frequency and power level sufficient to ignite the gas into the plasma and to maintain the plasma, the matching network including first and second variable reactances for controlling loading of the source and tuning a load including the reactive impedance element and the plasma to the source, a controller for (1) determining the amount the first variable reactance is to change for each unit change of the second variable reactance to attain the best match between the impedances seen looking into and out of output terminals of the r.f. source by changing the values of the first and second variable reactances, and (2) then varying the values of the first and second variable reactances based on the determination of (1) until the best impedance match between the impedances seen looking into and out of output terminals of the r.f. source is attained.
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32. A memory for use with a computer for controlling an r.f. field supplied to a plasma in a vacuum plasma chamber for processing a workpiece, the r.f. field being supplied to the plasma by a reactive impedance element connected via a matching network to an r.f. source, the r.f. field having a frequency and power level sufficient to ignite the gas into the plasma and to maintain the plasma, the matching network including first and second variable reactances that control loading of the source and resonating a load including the reactive impedance element and the plasma to the source, the memory storing signals to cause the computer to:
- (1) determine the amount the first of the variable reactances is to change for each unit change of the second of the variable reactances to attain the best match between the impedances seen looking into and out of output terminals of the r.f. source by commanding the computer to change the values of the first and second variable reactances; and
(2) then vary the values of the first and second variable reactances based on the determination (1) until the computer determines the best impedance match between the impedances seen looking into and out of output terminals of the r.f. source is attained.
- (1) determine the amount the first of the variable reactances is to change for each unit change of the second of the variable reactances to attain the best match between the impedances seen looking into and out of output terminals of the r.f. source by commanding the computer to change the values of the first and second variable reactances; and
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33. A method of supplying an r.f. field to a plasma in a vacuum plasma chamber processing a workpiece, the r.f. field being supplied to the plasma by a reactive impedance element connected via a matching network to an r.f. source, the r.f. field having a frequency and power level sufficient to ignite the gas into the plasma and to maintain the plasma, the matching network including first and second variable reactances that control loading of the source and tuning a load including the reactive impedance element and the plasma to the source, the method comprising (1) determining the amount the first variable reactance is to change for each unit change of the second variable reactance by changing the values of the first and second variable reactances until an initial best match is attained between the impedances seen looking into and out of output terminals of the r.f. source, and (2) then varying the values of the first and second variable reactances based on the determination made in step (1) until the best impedance match between the impedances seen looking into and out of output terminals of the r.f. source is attained.
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34. Apparatus for supplying an r.f. field to a plasma in a vacuum plasma chamber for processing a workpiece, comprising a reactive impedance element for supplying the r.f. field to the plasma, the reactive impedance element being connected via a matching network to an r.f. source, the r.f. field having a frequency and power level sufficient to ignite the gas into the plasma and to maintain the plasma, the matching network including first and second variable reactances for controlling loading of the source and tuning a load including the reactive impedance element and the plasma to the source, a controller for (1) determining the amount the first variable reactance is to change for each unit change of the second variable reactance by changing the values of the first and second variable reactances until the best initial match between the impedances as seen looking into and out of output terminals of the r.f. source is attained, and (2) then varying the values of the first and second variable reactances based on the determination of (1) until the best impedance match between the impedances seen looking into and out of output terminals of the r.f. source is attained.
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35. A memory for use with a computer for controlling an r.f. field supplied to a plasma in a vacuum plasma chamber for processing a workpiece, the r.f. field being supplied to the plasma by a reactive impedance element connected via a matching network to an r.f. source, the r.f. field having a frequency and power level sufficient to ignite the gas into the plasma and to maintain the plasma, the matching network including first and second variable reactances that control loading of the source and resonating a load including the reactive impedance element and the plasma to the source, the memory storing signals to cause the computer to:
- (1) determine the amount the first of the variable reactances is to change for each unit change of the second of the variable reactances by commanding the computer to change the values of the first and second variable reactances until the best initial match between the impedances seen looking into and out of output terminals of the r.f. source is attained; and
(2) then vary the values of the first and second variable reactances based on the determination (1) until the computer determines the best impedance match between the impedances seen looking into and out of output terminals of the r.f. source is attained.
- (1) determine the amount the first of the variable reactances is to change for each unit change of the second of the variable reactances by commanding the computer to change the values of the first and second variable reactances until the best initial match between the impedances seen looking into and out of output terminals of the r.f. source is attained; and
Specification