Gas mixture control in a gas discharge light source

Patent metadata

Field	Value
Publication number	US-9819136-B2
Application number	US-201615132803-A
Country	US
Kind code	B2
Filing date	Apr 19, 2016
Priority date	Jan 8, 2016
Publication date	Nov 14, 2017
Grant date	Nov 14, 2017

Abstract

A gas discharge light source includes a gas discharge system that includes one or more gas discharge chambers. Each of the gas discharge chambers in the gas discharge system is filled with a respective gas mixture. For each gas discharge chamber, a pulsed energy is supplied to the respective gas mixture by activating its associated energy source to thereby produce a pulsed amplified light beam from the gas discharge chamber. One or more properties of the gas discharge system are determined. A gas maintenance scheme is selected from among a plurality of possible schemes based on the determined one or more properties of the gas discharge system. The selected gas maintenance scheme is applied to the gas discharge system. A gas maintenance scheme includes one or more parameters related to adding one or more supplemental gas mixtures to the gas discharge chambers of the gas discharge system.

First claim

What is claimed is:

1. A method of operating a gas discharge light source comprising a gas discharge system that includes one or more gas discharge chambers, each gas discharge chamber housing an energy source, the method comprising:
filling each of the gas discharge chambers in the gas discharge system with a respective gas mixture;
for each gas discharge chamber, supplying a pulsed energy to the respective gas mixture by activating its energy source to thereby produce a pulsed amplified light beam from the gas discharge chamber;
determining one or more properties of the gas discharge system;
selecting a gas maintenance scheme from among a plurality of possible schemes based on the determined one or more properties of the gas discharge system; and
applying the selected gas maintenance scheme to the gas discharge system;
wherein a gas maintenance scheme includes one or more parameters related to adding one or more supplemental gas mixtures to the gas discharge chambers of the gas discharge system.

2. The method of claim 1 , wherein determining one or more properties of the gas discharge system comprises determining one or more properties of each of the gas discharge chambers in the gas discharge system.

3. The method of claim 1 , wherein applying the selected gas maintenance scheme to the gas discharge system comprises applying the selected gas maintenance scheme to each of the gas discharge chambers of the gas discharge system.

4. The method of claim 1 , wherein the gas discharge system includes two gas discharge chambers.

5. The method of claim 1 , wherein filling a gas discharge chamber with the respective gas mixture comprises filling the gas discharge chamber with a mixture of a gain medium and a buffer gas.

6. The method of claim 5 , wherein filling a gas discharge chamber with the mixture of the gain medium and the buffer gas comprises filling the gas discharge chamber with a gain medium that includes a noble gas and a halogen, and a buffer gas that includes an inert gas.

7. The method of claim 6 , wherein the noble gas includes argon, krypton, or xenon; the halogen includes fluorine; and the inert gas includes helium or neon.

8. The method of claim 1 , wherein supplying the pulsed energy to a respective gas mixture by activating its energy source comprises applying a pulsed voltage to a pair of electrodes within the gas discharge chamber so that an electrical stimulation is applied to a halogen within the gas mixture.

9. The method of claim 1 , wherein determining one or more properties of the gas discharge system comprises determining an age of at least one of the gas discharge chambers of the gas discharge system based on one or more of: how many times that gas discharge chamber has been filled with the gas mixture and how often the energy source of that gas discharge chamber has been activated.

10. The method of claim 1 , wherein determining the one or more properties of the gas discharge system, selecting the gas maintenance scheme, and applying the selected gas maintenance scheme to the gas discharge system occur while pulsed energy is being supplied to the gas mixture of the one or more gas discharge chambers.

11. The method of claim 1 , wherein determining the one or more properties of the gas discharge system, selecting the gas maintenance scheme, and applying the selected gas maintenance scheme to the gas discharge system occur while pulsed energy is not being supplied to the gas mixture of any of the gas discharge chambers.

12. The method of claim 1 , wherein:
selecting the gas maintenance scheme from among the plurality of possible gas maintenance schemes comprises selecting a standard gas injection scheme if it is determined that an age of at least one of the gas discharge chambers is in a first range, and applying the selected gas injection scheme to the gas discharge system comprises pumping at least a first amount of a buffer gas into the gas mixture of the at least one gas discharge chamber; and
selecting the gas maintenance scheme from among the plurality of possible gas maintenance schemes comprises selecting a conservation gas injection scheme if it is determined that an age of the at least one gas discharge chamber is in a second range, and applying the selected conservation gas injection scheme to the gas discharge system comprises pumping a second amount of the buffer gas into the gas mixture of the at least one gas discharge chamber, the second amount being lower than the first amount.

13. The method of claim 12 , wherein selecting the gas maintenance scheme from among the plurality of possible gas maintenance schemes comprises selecting another conservation gas injection scheme if it is determined that an age of the at least one gas discharge chamber is in a third range, and applying the selected gas injection scheme to the gas discharge system comprises pumping a third amount of the buffer gas into the gas mixture of the at least one gas discharge chamber, the third amount being lower than the first amount but greater than the second amount.

14. The method of claim 13 , wherein the first range is a value less than or equal to a lower value, the second range is a value greater than the lower value, and the third range is a value that is greater than an upper value.

15. The method of claim 13 , wherein the first range is a first value of the age, the second range is a second value of the age, and the third range is a third value of the age.

16. The method of claim 12 , wherein the first range is a first value of the age and the second range is a second value of the age.

17. The method of claim 12 , wherein the second range is distinct from the first range.

18. The method of claim 1 , wherein:
selecting the gas maintenance scheme from among the plurality of possible gas maintenance schemes comprises selecting a standard gas injection scheme if it is determined that an age of at least one of the gas discharge chambers is in a first range, and applying the selected gas injection scheme to the gas discharge system comprises performing an injection of a buffer gas into the gas mixture of the at least one gas discharge chamber at a first temporal frequency; and
selecting the gas maintenance scheme from among the plurality of possible gas maintenance schemes comprises selecting a conservation gas injection scheme if it is determined that the age of the at least one gas discharge chamber is in a second range, and applying the selected conservation gas injection scheme to the gas discharge system comprises performing an injection of the buffer gas into the gas mixture of the at least one gas discharge chamber at a second temporal frequency that is different from the first temporal frequency.

19. The method of claim 18 , wherein the second temporal frequency is less than the first temporal frequency.

20. The method of claim 18 , wherein performing an injection of the buffer gas into the gas mixture of the at least one gas discharge chamber also includes injecting one or more components of the gain medium into the gas mixture of the at least one gas discharge chamber.

21. The method of claim 1 , further comprising:
monitoring one or more operating characteristics of the gas discharge light source;
determining whether any of the one or more monitored operating characteristics will be out of an acceptable range at a future time; and
if it is determined that any of the one or more monitored operating characteristics will be out of an acceptable range at a future time, then: selec

Assignees

• Cymer LLC

Inventors

• Ahlawat Rahul
• Aggarwal Tanuj

Classifications

• H01S3/104

  in gas lasers · CPC title

• H01S3/036 Primary

  Means for obtaining or maintaining the desired gas pressure within the tube, e.g. by gettering, replenishing; Means for circulating the gas, e.g. for equalising the pressure within the tube {(H01S3/031 takes precedence)} · CPC title

• H01S3/2251

  ArF, i.e. argon fluoride is comprised for lasing around 193 nm · CPC title

• H01S3/225

  comprising an excimer or exciplex · CPC title

• H01S3/10069

  Memorized or pre-programmed characteristics, e.g. look-up table [LUT] · CPC title