Systems and methods for reducing power reflected towards a higher frequency rf generator during a period of a lower rf generator and for using a relationship to reduce reflected power

Patent metadata

Field	Value
Publication number	US-2016308560-A1
Application number	US-201615098912-A
Country	US
Kind code	A1
Filing date	Apr 14, 2016
Priority date	May 9, 2013
Publication date	Oct 20, 2016
Grant date	—

Abstract

Systems and methods for reducing reflected towards a higher frequency radio frequency (RF) generator during a period of a lower frequency RF generator and for using a relationship to reduce reflected power are described. By tuning the higher frequency RF generator during the period of the lower frequency RF generator, precise control of the higher frequency RF generator is achieved for reducing power reflected towards the higher frequency RF generator. Moreover, by using the relationship to reduce the reflected power, time is saved during processing of a wafer.

First claim

1 . A method for reducing reflected power during a period of a low frequency radio (RF) generator, comprising:
receiving during a first RF cycle of a first RF generator a first plurality of measured input parameter values sensed between an output of a second RF generator and an input of an impedance matching network when the second RF generator operates at a first plurality of parametric values and the impedance matching network has a first variable measurable factor; initializing for the first RF cycle one or more models to have the first variable measurable factor and the first plurality of parametric values, wherein the one or more models include a model of the impedance matching network; calculating for the first RF cycle a first plurality of output parameter values using the one or more models from the first plurality of measured input parameter values when the one or more models have the first variable measurable factor and the first plurality of parametric values; calculating, using the first plurality of output parameter values and the one or more models, a first plurality of favorable parametric values, wherein for each of the favorable parametric values of the first plurality, a reflection coefficient for the first RF cycle at an input of the one or more models is minimum; controlling, during a second RF cycle of the first RF generator, the second RF generator to operate at the first plurality of favorable parametric values.

2 . The method of claim 1 , further comprising:
receiving during the second RF cycle of the first RF generator a second plurality of measured input parameter values sensed between the output of the second RF generator and the input of the impedance matching network when the second RF generator operates at the first plurality of favorable parametric values; initializing for the second RF cycle the one or more models of the impedance matching network to have the first plurality of favorable parametric values; calculating for the second RF cycle a second plurality of output parameter values using the one or more models from the second plurality of measured input parameter values when the one or more models has the first plurality of favorable parametric values; calculating, using the second plurality of output parameter values and the one or more models, a second plurality of favorable parametric values, wherein for each of the favorable parametric values of the second plurality, the reflection coefficient for the second RF cycle at the input of the one or more models is minimum; controlling, during a third RF cycle of the first RF generator, the second RF generator to operate at the second plurality of favorable parametric values.

3 . The method of claim 2 , wherein the third RF cycle is consecutive to the second RF cycle.

4 . The method of claim 2 , wherein the third RF cycle follows the second RF cycle after one or more intermediate RF cycles between the second RF cycle and the third RF cycle.

5 . The method of claim 1 , wherein the second RF cycle is consecutive to the first RF cycle.

6 . The method of claim 1 , wherein the second RF cycle follows the first RF cycle after one or more intermediate RF cycles between the first RF cycle and the second RF cycle.

7 . The method of claim 1 , further comprising calculating, using the first plurality of output parameter values and the one or more models, an optimum variable capacitance value for which a weighted reflection coefficient at the input of the one or more models is minimum.

8 . The method of claim 1 , further comprising weighting the measured input parameter values of the first plurality.

9 . A system for reducing reflected power reflected towards a radio frequency (RF) generator, comprising:
a first radio frequency (RF) generator having an output; a second RF generator having an output; an impedance matching network having a first input connected to the output of the first RF generator and having a second input connected to the output of the second RF generator; a plasma chamber connected to the impedance matching network via an RF transmission line; and a processor coupled to the RF generator, wherein the processor is configured to receiving during a first RF cycle of the first RF generator a first plurality of measured input parameter values sensed between the output of the second RF generator and the second input of the impedance matching network when the second RF generator operates at a first plurality of parametric values and the impedance matching network has a first variable measurable factor, wherein the processor is configured to initialize for the first RF cycle one or more models to have the first variable measurable factor and the first plurality of parametric values, wherein the one or more models include a model of the impedance matching network, wherein the processor is configured to calculate for the first RF cycle a first plurality of output parameter values using the one or more models from the first plurality of measured input parameter values when the one or more models have the first variable measurable factor and the first plurality of parametric values, wherein the processor is configured to calculate, using the first plurality of output parameter values and the one or more models, a first plurality of favorable parametric values, wherein for each of the favorable parametric values of the first plurality, a reflection coefficient for the first RF cycle at an input of the one or more models is minimum, and wherein the processor is configured to control, during a second RF cycle of the first RF generator, the second RF generator to operate at the first plurality of favorable parametric values.

10 . The system of claim 9 ,
wherein the processor is configured to receive during the second RF cycle of the first RF generator a second plurality of measured input parameter values sensed between the output of the second RF generator and the input of the impedance matching network when the second RF generator operates at the first plurality of favorable parametric values, wherein the processor is configured to initialize for the second RF cycle the one or more models of the impedance matching network to have the first plurality of favorable parametric values, wherein the processor is configured to calculate for the second RF cycle a second plurality of output parameter values using the one or more models from the second plurality of measured input parameter values when the one or more models has the first plurality of favorable parametric values, wherein the processor is configured to calculate, using the second plurality of output parameter values and the one or more models, a second plurality of favorable parametric values, wherein for each of the favorable parametric values of the second plurality, the reflection coefficient for the second RF cycle at the input of the one or more models is minimum, wherein the processor is configured to control, during a third RF cycle of the first RF generator, the second RF generator to operate at the second plurality of favorable parametric values.

11 . The system of claim 10 , wherein the third RF cycle is consecutive to the second RF cycle.

12 . The system of claim 10 , wherein the third RF cycle follows the second RF cycle after one or more intermediate RF cycles between the second RF cycle and the third RF cycle.

13 . The system of claim 9 , wherein the second RF cycle is consecutive to the first RF cycle.

14 . The system of claim 9 , wherein the second RF cycle follows the first RF cycle after one or more intermediate RF cycles between the first RF cycle and the s

Assignees

• Lam Res Corp

Inventors

• Howald Arthur M
• Valcore Jr John C
• Fong Andrew
• Hopkins David

Classifications

• G06F30/36 Primary

  Circuit design at the analogue level · CPC title

• G05B17/02

  electric · CPC title

• H04B2001/0491

  with frequency synthesizers, frequency converters or modulators · CPC title

• H04B1/0475 Primary

  with means for limiting noise, interference or distortion (H04B1/0483 takes precedence) · CPC title

• H05B6/50

  for monitoring or control · CPC title