US6795474B2
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gas discharge laser with improved beam path
Assignee: Cymer Inc
•
Filing: 2001-11-14
•
Granted: 2004-09-21
•
Expires: 2021-11-14
Abstract
Abstract An excimer laser with a purged beam path capable of producing a high quality pulsed laser beam at pulse rates in excess of 2,000 Hz at pulse energies of about 5 mJ or greater. The entire purged beam path through the laser system is sealed to minimize contamination of the beam path. A preferred embodiment comprises a thermally decoupled LNP aperture element to minimize thermal distortions in the LNP. This preferred embodiment is an ArF excimer laser specifically designed as a light source for integrated circuit lithography. An improved wavemeter is provided with a special purge of a compartment exposed to the output laser beam.
Inventors
- 👤 William N. Partlo
- 👤 Richard L. Sandstrom
- 👤 Holzer K. Glatzel
- 👤 Raymond F. Cybulski
- 👤 Peter C. Newman
- 👤 James K. Howey
- 👤 William G. Hulburd
- 👤 John T. Melchior
- 👤 Alex P. Ivaschenko
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 17:25
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70008; G03F7/70025; G03F7/70483; G03F7/7055; G03F7/70575; G03F7/708; G03F7/70908; G03F7/70933; H; H01; H01S; H01S3/00; H01S3/02; H01S3/03; H01S3/036; H01S3/038; H01S3/0385; H01S3/04; H01S3/0401; H01S3/10; H01S3/102; H01S3/104; H01S3/105; H01S3/1055; H01S3/14; H01S3/22; H01S3/223; H01S3/225; H01S3/005; H01S3/0057; H01S3/041; H01S3/05; H01S3/08; H01S3/08004; H01S3/08009; H01S3/08018; H01S3/08022; H01S3/08031; H01S3/08036; H01S3/09; H01S3/097; H01S3/0971; H01S3/0975; H01S3/1022; H01S3/1024; H01S3/13; H01S3/1305; H01S3/131; H01S3/134; H01S3/139; H01S3/2207; H01S3/2251; H01S3/2256; H01S3/2258; H01S3/23; H01S3/2366
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
331 words
An extreme repetition rate gas discharge modular laser capable of operating at pulse repetition rates in excess of 2,000 pulses per second, said laser comprising: A) a laser chamber module containing: (1) a laser gas, (2) two elongated electrodes, defining a discharge region (3) a tangential type fan for producing sufficient gas velocities of said laser gas in said discharge region to clear from said discharge region, following each pulse, substantially all discharge produced ions prior to a next pulse when operating at a repetition rate in the range of 4,000 pulses per second or greater, and (4) a heat exchanger system comprising at least one finned heat exchangers, said system being capable of removing at least 16 kw of heat energy from said laser gas, B) a pulse power system configured to provide electrical pulses to said electrodes sufficient to produce laser pulses from said discharge region at rates of about 4,000 pulses per second with precisely controlled pulse energies in the range of about 5 mJ, C) a first optics module comprising line narrowing optical components, D) a second optics module comprising an output coupler, said output coupler and said line narrowing module defining a resonant cavity and a laser beam path through discharge region and said laser chamber module and being mounted in said laser separated from said chamber module and E) a beam path purge system for purging portions of said laser beam path, said beam path purge system comprising: 1) a first easy sealing bellows seal unit for providing with said purge system a vacuum quality substantially oxygen free beam path between said chamber module and said first optic module and, 2) a second easy sealing bellows seal unit for providing with said purge system a vacuum quality substantially oxygen free beam path between said chamber module and said second optic module; wherein said first and second easy sealing bellows seals units each can be quickly and easily removed for fast replacement of said chamber module.
Claim 2
Dependent Claim
331 words
An extreme repetition rate gas discharge modular laser capable of operating at pulse repetition rates in excess of 2,000 pulses per second, said laser comprising: A) a laser chamber module containing: (1) a laser gas, (2) two elongated electrodes, defining a discharge region (3) a tangential type fan for producing sufficient gas velocities of said laser gas in said discharge region to clear from said discharge region, following each pulse, substantially all discharge produced ions prior to a next pulse when operating at a repetition rate in the range of 4,000 pulses per second or greater, and (4) a heat exchanger system comprising at least one finned heat exchangers, said system being capable of removing at least 16 kw of heat energy from said laser gas, B) a pulse power system configured to provide electrical pulses to said electrodes sufficient to produce laser pulses from said discharge region at rates of about 4,000 pulses per second with precisely controlled pulse energies in the range of about 5 mJ, C) a first optics module comprising line narrowing optical components, D) a second optics module comprising an output coupler, said output coupler and said line narrowing module defining a resonant cavity and a laser beam path through discharge region and said laser chamber module and being mounted in said laser separated from said chamber module and E) a beam path purge system for purging portions of said laser beam path, said beam path purge system comprising: 1) a first easy sealing bellows seal unit for providing with said purge system a vacuum quality substantially oxygen free beam path between said chamber module and said first optic module and, 2) a second easy sealing bellows seal unit for providing with said purge system a vacuum quality substantially oxygen free beam path between said chamber module and said second optic module; wherein said first and second easy sealing bellows seals units each can be quickly and easily removed for fast replacement of said chamber module.
Claim 3
Dependent Claim
33 words
A modular laser as in claim 1 wherein each of said first and second easy sealing bellows seals units comprise a hand-operated lever for removing said seals by hand without any special tools.
Claim 4
Dependent Claim
28 words
A modular laser as in claim 1 and further comprising a thermally decoupled aperture positioned in said beam path between said chamber module and said first optical module.
Claim 5
Dependent Claim
23 words
A modular laser as in claim 3 wherein said thermally decoupled aperture is a part of said first easy sealing bellows seal unit.
Claim 6
Dependent Claim
37 words
A modular laser as in claim 1 wherein said laser is configured to produce a pulsed laser beam defining an output beam and also comprises a wavemeter module for monitoring wavelength and bandwidth of said output beam.
Claim 7
Dependent Claim
38 words
A modular laser as in claim 5 and further comprising a third easy sealing bellows seal for providing with said purge system a vacuum quality substantially oxygen free beam path between said output coupler and said wavemeter module.
Claim 8
Dependent Claim
18 words
A modular laser as in claim 1 wherein said beam path purge system comprises a nitrogen purge source.
Claim 9
Dependent Claim
32 words
A modular laser as in claim 1 wherein said beam path purge system comprises a helium purge source and said purge system is configured to purge said line narrowing module with helium.
Claim 10
Dependent Claim
38 words
A modular laser as in claim 1 wherein said purge system includes a nitrogen purge source and a helium purge source and said helium purge source is configured to purge at least said line narrowing module with helium.
Claim 11
Dependent Claim
30 words
A modular laser as in claim 1 and further comprising a purge gas contamination detector for detecting laser beam absorbing material in said beam path or in said output beam.
Claim 12
Dependent Claim
31 words
A modular laser as in claim 10 wherein said contamination detector comprises a electret acoustic detector for detecting pressure waves resulting from the absorption by said material of laser pulse radiation.
Claim 13
Dependent Claim
68 words
A laser as in claim 1 further comprising: a laser beam measurement and control system comprising an etalon unit, a photo diode array, a programmable logic device, and optics to focus laser light from said etalon unit on to said photo diode array wherein said programmable logic device is programmed to analyze data from said photodiode array to determine locations on said photo diode array of etalon fringes.
Claim 14
Dependent Claim
31 words
A laser as in claim 12 wherein said measurement and control system also comprises a microprocessor programmed to calculate wavelength and bandwidth from fringe data located by said programmable logic device.
Claim 15
Dependent Claim
27 words
A laser as in claim 12 wherein said programmable logic device is programmed with an algorithm for calculating wavelength and bandwidth based on measurement of said fringes.
Claim 16
Dependent Claim
27 words
A laser as in claim 14 wherein said programmable logic device is configured to make calculations of wavelength and bandwidth faster than {fraction (1/4,000)} of a second.
Claim 17
Dependent Claim
15 words
A laser as in claim 15 wherein said etalon unit comprises a diffractive diffusing element.
Claim 18
Dependent Claim
88 words
A laser as in claim 12 wherein said measurement and control system comprises a primary beam splitter for splitting off a small percentage of the light from the output pulses from said laser, a second beam splitter for directing a portion of said small percentage to said pulse energy detector and a means isolating a volume bounded by said primary beam splitter, said secondary beam splitter and a window of said pulse energy detector from other portions of said measurement and control system to define an isolated region.
Claim 19
Dependent Claim
21 words
A laser as in claim 17 and further comprising a purge means for purging said isolated region with a purge gas.
Claim 20
Dependent Claim
43 words
A laser as in claim 18 wherein said laser further comprises an output coupler unit, and an output window unit said purge means being configured so that exhaust from said isolated region also purges said output coupler unit and said output window unit.
Claim 21
Dependent Claim
31 words
A laser as in claim 1 wherein said line narrowing unit comprises a grating defining a grating face and a purge means for forcing purge gas adjacent to said grating face.
Claim 22
Dependent Claim
22 words
A laser as in claim 1 and farther comprising a nitrogen purge system comprising a nitrogen purge system comprising a nitrogen filter.
Claim 23
Dependent Claim
33 words
A laser as in claim 1 and farther comprising a nitrogen comprising a purge system comprising flow monitors, said laser also comprising purge exhaust tubes for transporting exhaust purge gas from said laser.
Claim 24
Dependent Claim
35 words
A laser as in claim 1 and further comprising a shutter unit comprising an electrically operated shutter and a power meter which can be positioned in a laser output beam path with a command signal.
Claim 25
Dependent Claim
23 words
A laser as in claim 1 wherein each of said first and second easy seal bellows seals units comprise a metal C-seal ring.
Claim 26
Dependent Claim
52 words
A laser as in claim 1 wherein each of said first and second easy sealing bellows seals units contains no elastomer, provides vibration isolation from said chamber, provides beam train isolation from atmospheric gases and permits unrestricted replacement of said laser chamber without disturbance of said LNP or said output coupler unit.
Claim 27
Dependent Claim
33 words
A laser as in claim 25 wherein at least one of said easy sealing bellows seals comprise a bellows part having a circular ridge configured to prevent damage to said metal c-seal ring.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2007-09-21 | 2008-03-22 | 2008-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2011-09-21 | 2012-03-22 | 2012-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2015-09-21 | 2016-03-22 | 2016-09-21 | $7700.00 | Window Closed / Lapsed |