System and method for automatic gas optimization in a two-chamber gas discharge laser system

Patent metadata

Field	Value
Publication number	US-9831628-B2
Application number	US-201515503996-A
Country	US
Kind code	B2
Filing date	Aug 14, 2015
Priority date	Sep 10, 2014
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

A system and method for automatically performing gas optimization after a refill in the chambers of a two chamber gas discharge laser is disclosed. The laser is fired at low power, and the gas in the amplifier laser chamber bled if necessary until the discharge voltage meets or exceeds a minimum value without dropping the pressure below a minimum value. The power output is increased to a burst pattern that approximates the expected operation of the laser, and the amplifier chamber gas bled again if necessary until the voltage and an output energy meet or exceed minimum values, or until the pressure is less than a minimum value. The gas in the master oscillator chamber is then bled if necessary until the output energy of the master oscillator meets or falls below a maximum value, again without dropping the pressure in the chamber below the minimum value. While the pressure is adjusted, bandwidth is also measured and adjusted to stay within a desired range. Once the target values are provided, the process runs quickly without manual interaction.

First claim

What is claimed is:

1. A dual chamber gas discharge laser light source, comprising:
a master oscillator having a laser chamber containing a lasing medium gas comprising a halogen for producing a first laser;
an amplifier coupled to receive the first laser from the master oscillator, the amplifier having a laser chamber containing a lasing medium gas comprising a halogen for producing an amplified laser;
a gas optimization system including a controller executing an optimization scheme, the optimization scheme comprising:
an amplifier optimization sequence for optimizing parameters in the amplifier, the amplifier optimization sequence includes ascertaining if parameters in the amplifier are outside a range of acceptable amplifier parameters and performing one or more bleeding steps to bleed the gas from the laser chamber of the amplifier if the parameters in the amplifier are outside the range of acceptable amplifier parameters, and
a master oscillator optimization sequence following the power amplifier optimization sequence for optimizing parameters in the amplifier, the master oscillator optimization sequence includes one or more bleeding steps to bleed the gas from laser chamber of the master oscillator if the parameters in the master oscillator are outside a range of acceptable master oscillator parameters,
wherein the gas optimization system does not add gas during the optimization scheme into the laser chamber of the amplifier and the laser chamber of the master oscillator.

2. The dual chamber gas discharge laser light source of claim 1 wherein the amplifier optimization sequence includes optimizing bandwidth prior to the ascertaining.

3. The dual chamber gas discharge laser light source of claim 2 wherein the optimizing bandwidth includes adjusting magnification of an optical element in the amplifier.

4. The dual chamber gas discharge laser light source of claim 2 wherein the range of acceptable amplifier parameters includes at least one of output energy and discharge voltage.

5. The dual chamber gas discharge laser light source of claim 2 wherein the range of acceptable amplifier parameters includes both output energy and discharge voltage.

6. The dual chamber gas discharge laser light source of claim 1 wherein the master oscillator optimization sequence includes optimizing bandwidth prior to the ascertaining.

7. The dual chamber gas discharge laser light source of claim 6 wherein the range of acceptable master oscillator parameters includes output energy.

8. The dual chamber gas discharge laser light source of claim 1 wherein the range of acceptable master oscillator parameters includes output energy.

9. The dual chamber gas discharge laser light source of claim 1 wherein the bleeding steps to bleed the gas from the master oscillator are performed only if gas pressure within the laser chamber of the master oscillator is above a minimum pressure value predefined for the master oscillator.

10. The dual chamber gas discharge laser light source of claim 1 wherein performing the amplifier optimization sequence and the master oscillator optimization sequence is accomplished without involvement of a human operator during the performing.

11. A method for executing an optimization scheme in a dual chamber gas discharge laser light source, the dual gas discharge laser light source having a master oscillator having a laser chamber containing a lasing medium gas comprising a halogen for producing a first laser, the dual gas discharge laser light source includes an amplifier coupled to receive the first laser, the amplifier having a laser chamber containing a lasing medium gas comprising a halogen for producing an amplified laser, the method comprising:
an amplifier optimization sequence for optimizing parameters in the amplifier, the amplifier optimization sequence includes ascertaining if parameters in the amplifier are outside a range of acceptable amplifier parameters and performing one or more bleeding steps to bleed the gas from the amplifier if the parameters in the amplifier are outside the range of acceptable amplifier parameters, and
a master oscillator optimization sequence following the power amplifier optimization sequence for optimizing parameters in the amplifier, the master oscillator optimization sequence includes one or more bleeding steps to bleed the gas from the master oscillator if the parameters in the master oscillator are outside a range of acceptable master oscillator parameters,
wherein gas is not added into the laser chamber of the amplifier and the laser chamber of the master oscillator during the optimization scheme.

12. The method of claim 11 wherein the amplifier optimization sequence includes optimizing bandwidth prior to the ascertaining.

13. The method of claim 12 wherein the optimizing bandwidth includes adjusting magnification of an optical element in the amplifier.

14. The method of claim 12 wherein the range of acceptable amplifier parameters includes at least one of output energy and discharge voltage.

15. The method of claim 11 wherein the range of acceptable amplifier parameters includes at least one of output energy and discharge voltage.

16. The method of claim 11 wherein the master oscillator optimization sequence includes optimizing bandwidth prior to the ascertaining.

17. The method of claim 16 wherein the range of acceptable master oscillator parameters includes output energy.

18. The method of claim 11 wherein the range of acceptable master oscillator parameters includes output energy.

19. The method of claim 11 wherein performing the amplifier optimization sequence and the master oscillator optimization sequence is accomplished without involvement of a human operator during the performing.

20. The method of claim 11 wherein the bleeding steps to bleed the gas from the amplifier are performed only if gas pressure within the laser chamber of the amplifier is above a minimum pressure value predefined for the amplifier.

21. The method of claim 11 wherein the bleeding steps to bleed the gas from the master oscillator are performed only if gas pressure within the laser chamber of the master oscillator is above a minimum pressure value predefined for the master oscillator.

22. The method of claim 11 wherein the optimization scheme occurs after a refill of the lasing gas in the laser chamber of the master oscillator and of the lasing gas in the laser chamber of the amplifier.

Assignees

• Cymer LLC

Inventors

• O'Brien Kevin
• Thornes Joshua
• Borrello Michael

Classifications

• 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

• H01S3/225

  comprising an excimer or exciplex · CPC title

• H01S3/104

  in gas lasers · CPC title

• H01S3/2256

  KrF, i.e. krypton fluoride is comprised for lasing around 248 nm · CPC title

• H01S3/13

  Stabilisation of laser output parameters, e.g. frequency or amplitude · CPC title