Claims
- 1. An excimer or molecular fluorine laser system, comprising:
a discharge chamber filled with a gas mixture including molecular fluorine and a buffer gas; a plurality of electrodes within the discharge chamber and defining a discharge region therebetween connected to a pulsed discharge circuit for applying discharge pulses to the electrodes for energizing the gas mixture; a resonator including the discharge chamber and a line-narrowing module for generating a line-narrowed laser beam; and an attenuator for reducing an energy of the laser beam to a predetermined energy for lithographic processing.
- 2. The laser system of claim 1, wherein said attenuator is configured to reflect a first portion of the beam to a diagnostic module for monitoring one or more parameters of the beam, and wherein a second portion of said beam transmits said attenuator as an output beam of said laser system.
- 3. The laser system of claim 2, wherein said diagnostic module includes an energy detector for detecting an energy of the reflected beam.
- 4. The laser system of claim 2, wherein said diagnostic module includes a spectrometer for determining a spectral parameter of the reflected beam.
- 5. The laser system of claim 2, wherein said diagnostic module includes a detector for measuring a parameter of the reflected beam selected from the group of parameters consisting of temporal pulse shape, spatial profile, beam alignment, beam divergence and spectral distribution
- 6. The laser system of claim 2, wherein said diagnostic module includes an inspection window.
- 7. The laser system of claim 1, wherein said attenuator includes an attenuator plate for reflecting away a first portion of the beam and for transmitting a second portion of said beam as an output beam of said laser system, and wherein said laser system further comprises a compensator plate for compensating a shift of the beam produced by refraction through said attenuator plate.
- 8. The laser system of claim 1, wherein said attenuator is disposed outside of said resonator of said laser system and said attenuator reduces the energy of an outcoupled laser beam from said resonator.
- 9. The laser system of claim 8, said attenuator for reflecting a first portion of the beam to a diagnostic module for monitoring one or more parameters of said beam selected from the group of beam parameters consisting of energy, bandwidth, wavelength, temporal pulse shape, spatial profile, beam alignment, beam divergence and spectral distribution
- 10. The laser system of claim 8, wherein the discharge circuit is configured to operate in a range between a minimum voltage and a maximum voltage, and wherein when the minimum voltage is applied across the electrodes, the energy of the outcoupled laser beam before impinging upon the attenuator is greater than the predetermined energy.
- 11. The laser system of claim 8, wherein the attenuator is disposed in a housing flushed with an inert gas.
- 12. The laser system of claim 11, wherein the inert gas is selected from the group of inert gases consisting of nitrogen and argon.
- 13. The laser system of claim 8, wherein the attenuator is driven by a motor for adjusting the attenuation.
- 14. The laser system of claim 1, wherein said attenuator includes an attenuator plate for reflecting away a first portion of the beam and for transmitting a second portion of said beam as an output beam of said laser system.
- 15. The laser system of claim 1, wherein the attenuator has variable attenuation for reducing several output pulse energies of the outcoupled laser beam each to said predetermined pulse energy.
- 16. The laser system of claim 15, wherein said several output pulse energies are energies of output pulses produced by application of a same input voltage from said discharge circuit to said electrodes at different stages of aging of optics of said line-narrowing module.
- 17. The laser system of claim 15, wherein the attenuator includes a plurality of attenuator plates for reflecting a portion of the output energy of pulses of the outcoupled laser beam, each plate having a different reflectivity.
- 18. The laser system of claim 15, wherein said attenuator includes a slot for insertion of any of a plurality of attenuator plates for adjusting the variable attenuation of the attenuator.
- 19. The laser system of claim 15, wherein said attenuator includes a rotatable holder for holding a plurality of attenuator plates for reflecting a portion of the energy of pulses of the outcoupled laser beam, each plate being rotatable into the path of the laser beam for selecting an amount of attenuation depending on the pulse energy of pulses of the outcoupled laser beam and a value of the predetermined energy.
- 20. The laser system of claim 1, wherein the attenuator includes one or more attenuator plates arranged at Brewster's angle.
- 21. The laser system of claim 1, wherein the attenuator includes one or more attenuator plates each including a reflective coating.
- 22. The laser system of claim 1, wherein the attenuator includes one or more attenuator plates, and wherein a reflectivity of the one or more plates is polarization coupled.
- 23. The laser system of claim 1, wherein the discharge circuit is configured to operate in a range between a minimum voltage and a maximum voltage, and wherein when the minimum voltage is applied across the electrodes, the energy of laser pulses before impinging upon the attenuator is greater than the predetermined energy.
- 24. A method of operating an excimer or molecular fluorine laser system including a discharge chamber filled with a gas mixture and having a plurality of electrodes therein connected to a pulsed discharge circuit, and including a laser resonator for generating pulsed output beam, said method for increasing lifetimes of optical components of the resonator, and comprising the steps of:
configuring the pulsed discharge circuit to apply electrical pulses to the electrodes of the laser system to output laser pulses initially having an energy in a range above a predetermined energy for industrial lithographic processing; and attenuating said energy of said output laser pulses to the predetermined energy for industrial lithographic processing.
- 25. The method of claim 24, further comprising the step of reducing an attenuation amount as optics of the laser resonator age to maintain the energy of the output laser pulses at the predetermined energy.
- 26. The method of claim 24, further comprising the step of reducing an attenuation amount for producing output laser pulses having a higher energy than the predetermined energy.
- 27. The method of claim 24, wherein the attenuating step is performed outside of the laser resonator to outcoupled pulses from the resonator.
- 28. The method of claim 27, wherein the attenuating step is performed using an attenuator disposed within a housing, and the method further comprises the step of flushing the housing with an inert gas.
- 29. The method of claim 27, further comprising the step of driving the attenuator with a motor for adjusting the attenuation to maintain the energy of the output pulses at the predetermined energy.
PRIORITY
[0001] This application claims the benefit of priority to U.S. provisional patent application Ser. No. 60/178,620, filed Jan. 27, 2000.
Provisional Applications (1)
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Number |
Date |
Country |
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60178620 |
Jan 2000 |
US |