Cable power loss determination for virtual metrology
First Claim
1. A method for modeling cable loss, comprising:
- receiving a measurement of reverse power at a radio frequency (RF) generator, the RF generator coupled via an RF cable to an input of an impedance matching network, the impedance matching network coupled via an RF transmission line to a plasma chamber, the RF generator having a frequency of operation;
receiving a measurement of forward power at the RF generator;
computing a theoretical power delivered to the impedance matching network as a difference between the forward power and the reverse power;
calculating a ratio of the reverse power to the forward power to generate an RF power reflection ratio;
identifying a cable power attenuation fraction of the RF cable based on the frequency of operation of the RF generator and a length of the RF cable;
calculating a cable power loss as a function of the RF power reflection ratio, the cable power attenuation fraction, and the theoretical power;
calculating an actual power to be delivered to the input of the impedance matching network based on the theoretical power and the cable power loss; and
sending the calculated actual power to the RF generator to generate an RF signal,wherein the method is executed by a processor.
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Abstract
A method for modeling cable loss is described. The method includes receiving a measurement of reverse power and forward power at a radio frequency (RF) generator. The method further includes computing theoretical power delivered to a matching network as a difference between the forward power and the reverse power and calculating a ratio of the reverse power to the forward power to generate an RF power reflection ratio. The method further includes identifying a cable power attenuation fraction based on a frequency of the RF generator and calculating a cable power loss as a function of the RF power reflection ratio, the cable power attenuation fraction, and the theoretical power. The method includes calculating actual power to be delivered to the impedance matching network based on the theoretical power and the cable power loss and sending the calculated actual power to the RF generator to generate an RF signal.
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Citations
19 Claims
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1. A method for modeling cable loss, comprising:
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receiving a measurement of reverse power at a radio frequency (RF) generator, the RF generator coupled via an RF cable to an input of an impedance matching network, the impedance matching network coupled via an RF transmission line to a plasma chamber, the RF generator having a frequency of operation; receiving a measurement of forward power at the RF generator; computing a theoretical power delivered to the impedance matching network as a difference between the forward power and the reverse power; calculating a ratio of the reverse power to the forward power to generate an RF power reflection ratio; identifying a cable power attenuation fraction of the RF cable based on the frequency of operation of the RF generator and a length of the RF cable; calculating a cable power loss as a function of the RF power reflection ratio, the cable power attenuation fraction, and the theoretical power; calculating an actual power to be delivered to the input of the impedance matching network based on the theoretical power and the cable power loss; and sending the calculated actual power to the RF generator to generate an RF signal, wherein the method is executed by a processor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method comprising:
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receiving a measurement of reverse power at a radio frequency (RF) generator, the RF generator coupled via an RF cable to an input of an impedance matching network, the impedance matching network coupled via an RF transmission line to a plasma chamber, the RF generator having a frequency of operation; receiving a measurement of forward power at the RF generator; computing a theoretical power delivered to the impedance matching network as a difference between the forward power and the reverse power; calculating a ratio of the reverse power to the forward power to generate an RF power reflection ratio; identifying a cable power attenuation fraction of the RF cable based on the frequency of operation of the RF generator and a length of the RF cable; calculating a cable power loss as a function of the RF power reflection ratio, the cable power attenuation fraction, and the theoretical delivered power; calculating an actual power to be delivered to the input of the impedance matching network based on the theoretical delivered power and the cable power loss; determining an actual power at a node associated with a computer-generated model based on the actual power to be delivered to the input of the impedance matching network; and sending the actual power at the node to the RF generator to control the RF generator, wherein sending the actual power at the node to the RF generator to control the RF generator comprises sending a value of the actual power at the node for generating an RF signal to achieve a threshold, wherein the method is executed by a processor. - View Dependent Claims (14, 15, 16, 17)
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18. A plasma system comprising:
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a radio frequency (RF) generator for supplying forward power, the RF generator having a frequency of operation; an impedance matching circuit having an input coupled to the RF generator for receiving the forward power and to generate a modified RF signal based on the forward power; an RF cable coupling the RF generator to the impedance matching circuit to facilitate a transfer of the forward power to the impedance matching circuit; a plasma chamber coupled to the impedance matching circuit via an RF transmission line, the plasma chamber for generating plasma based on the modified RF signal; a sensor coupled to the RF generator to measure the forward power and to measure reverse power, the reverse power reflected from the plasma towards the RF generator via the RF cable; a host system coupled to the sensor for receiving the measurement of the forward power and the reverse power, wherein the host system is configured to; compute a theoretical power delivered to the impedance matching circuit as a difference between the forward power and the reverse power; calculate a ratio of the reverse power to the forward power to generate an RF power reflection ratio; identify a cable power attenuation fraction of the RF cable based on the frequency of operation of the RF generator and a length of the RF cable; calculate a cable power loss as a function of the RF power reflection ratio, the cable power attenuation fraction, and the theoretical delivered power; calculate an actual power to be delivered to the input of the impedance matching circuit based on the theoretical delivered power and the cable power loss; and send the calculated actual power to the RF generator to control the RF generator. - View Dependent Claims (19)
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Specification