Gas optimization in a gas discharge light source

Patent metadata

Field	Value
Publication number	US-9634455-B1
Application number	US-201615044677-A
Country	US
Kind code	B1
Filing date	Feb 16, 2016
Priority date	Feb 16, 2016
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

One or more operating characteristics of a light source are adjusted by estimating a plurality of extreme values of operating parameters of the light source while operating the light source under a set of extreme test conditions. For each extreme test condition, a group of pulses of energy is supplied to a first gas discharge chamber of the light source while operating the first gas discharge chamber under the extreme test condition to produce a first pulsed amplified light beam; a group of pulses of energy is supplied to a second gas discharge chamber of the light source while operating the second gas discharge chamber under the extreme test condition to produce a second pulsed amplified light beam. An extreme value of an operating parameter for the extreme test condition is measured to thereby estimate the extreme value of the operating parameter.

First claim

What is claimed is:

1. A method of adjusting one or more operating characteristics of a light source comprising a first stage with a first gas discharge chamber filled with a first gas mixture and including a first pulsed energy source and a second stage with a second gas discharge chamber filled with a second gas mixture and including a second pulsed energy source, the method comprising:
estimating a plurality of extreme values of operating parameters of the light source while operating the light source under a set of extreme test conditions, the estimating comprising, for each extreme test condition:
supplying a group of pulses of energy to the first gas discharge chamber while operating the first gas discharge chamber under the extreme test condition to produce a first pulsed amplified light beam from the first stage that is directed to the second stage;
supplying a group of pulses of energy to the second gas discharge chamber while operating the second gas discharge chamber under the extreme test condition and while the first pulsed amplified light beam is input to the second gas discharge chamber to produce a second pulsed amplified light beam; and
measuring an extreme value of an operating parameter for the extreme test condition;

determining whether to adjust at least one operating characteristic of the light source out of a plurality of operating characteristics based on the estimated plurality of extreme values of operating parameters; and
if it is determined that an operating characteristic should be adjusted, then adjusting that operating characteristic.

2. The method of claim 1 , further comprising determining a plurality of error values, each error value being determined from one or more measured extreme values of the operating parameters.

3. The method of claim 1 , wherein:
supplying the group of pulses of energy to the first gas discharge chamber comprises supplying a burst of pulses of energy to the first gas discharge chamber; and
supplying the group of pulses of energy to the second gas discharge chamber comprises supplying a burst of pulses of energy to the second gas discharge chamber.

4. The method of claim 1 , wherein:
operating the light source under the set of extreme test conditions comprises operating the light source under an extreme test condition in which energy supplied to the first gas discharge chamber is increased while operating at a non-optimum relative timing between pulses of the first amplified light beam and the second amplified light beam; and
measuring the extreme value of the operating parameter for the extreme test condition comprises measuring a maximum energy of the second pulsed amplified light beam.

5. The method of claim 1 , wherein:
operating the light source under the set of extreme test conditions comprises operating the light source under an extreme test condition in which energy supplied to the first gas discharge chamber is decreased while operating at an optimum relative timing between pulses of the first amplified light beam and the second amplified light beam; and
measuring the extreme value of the operating parameter for the extreme test condition comprises measuring a minimum energy of the second pulsed amplified light beam.

6. The method of claim 1 , wherein:
operating the light source under the set of extreme test conditions comprises operating the light source under an extreme test condition in which a relative timing between pulses of the first amplified light beam and the second amplified light beam is decreased while supplying a minimum energy to the first gas discharge chamber; and
measuring the extreme value of the operating parameter for the extreme test condition comprises measuring a maximum spectral property of the second pulsed amplified light beam.

7. The method of claim 1 , wherein:
operating the light source under the set of extreme test conditions comprises operating the light source under an extreme test condition in which a relative timing between pulses of the first amplified light beam and the second amplified light beam is increased while supplying a maximum energy to the first gas discharge chamber; and
measuring the extreme value of the operating parameter for the extreme test condition comprises measuring a minimum spectral property of the second pulsed amplified light beam.

8. The method of claim 1 , wherein measuring the extreme value of an operating parameter for the extreme test condition comprises:
measuring a maximum energy of the second pulsed amplified light beam while operating the light source under a first extreme test condition; and
measuring a minimum energy of the second pulsed amplified light beam while operating the light source under a second extreme test condition.

9. The method of claim 1 , wherein measuring the extreme value of an operating parameter for the extreme test condition comprises:
measuring a maximum spectral property of the second pulsed amplified light beam while operating the light source under a third extreme test condition; and
measuring a minimum spectral property of the second pulsed amplified light beam while operating the light source under a fourth extreme test condition.

10. The method of claim 1 , wherein measuring the extreme value of the operating parameter comprises measuring one or more of:
an extreme value of an energy of the second pulsed amplified light beam, and
an extreme value of a spectral property of the second pulsed amplified light beam.

11. The method of claim 1 , wherein:
determining whether to adjust an operating characteristic of the light source is also based on one or more of a plurality of calibrated constants and a plurality of nonlinear functions.

12. The method of claim 1 , wherein determining whether to adjust at least one operating characteristic of the light source comprises:
determining whether to adjust a pressure of a gas mixture of at least one of the gas discharge chambers; and
determining whether to adjust an optical feature of a pulsed amplified light beam.

13. The method of claim 12 , wherein determining whether to adjust the optical feature of the pulsed amplified light beam comprises determining whether to adjust an optical magnification of the first pulsed amplified light beam.

14. The method of claim 12 , wherein adjusting the pressure of the gas mixture of the at least one gas discharge chamber comprises permitting at least some of the gas mixture to escape from the gas discharge chamber.

15. The method of claim 12 , wherein adjusting the optical feature of the pulsed amplified light beam comprises adjusting an optical magnification of the first pulsed amplified light beam to thereby adjust a bandwidth of the second pulsed amplified light beam.

16. The method of claim 12 , wherein:
determining whether to adjust the pressure of the gas mixture of the at least one gas discharge chamber comprises determining whether a measured pressure of the gas mixture is greater than a lower acceptable value and an energy of the second pulsed amplified light beam is in an acceptable range; and
determining that the pressure of the gas mixture of the at least one gas discharge chamber should be adjusted only if the measured pressure of the gas mixture is greater than the lower acceptable value and the energy of the second pulsed amplified light beam is in the acceptable range.

17. The method of claim 12 , wherein:
determining whether to adjust the optical feature of the pulsed amplified light beam comprises determining whether a condition of a spectral property actuation is met; and
determin

Assignees

• Cymer LLC

Inventors

• Aggarwal Tanuj

Classifications

• H01S3/1305

  Feedback control systems · CPC title

• H01S3/134 Primary

  in gas lasers · CPC title

• H01S3/08036

  using intracavity dispersive, polarising or birefringent elements · CPC title

• H01S3/09705

  with particular means for stabilising the discharge · CPC title

• H01S3/225

  comprising an excimer or exciplex · CPC title