US6625191B2
Expired / Lapsed
US
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Very narrow band, two chamber, high rep rate gas discharge laser system
Assignee: Cymer LLC
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Filing: 2001-11-30
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Granted: 2003-09-23
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Expires: 2021-11-30
Abstract
Abstract An injection seeded modular gas discharge laser system capable of producing high quality pulsed laser beams at pulse rates of about 4,000 Hz or greater and at pulse energies of about 5 mJ or greater. Two separate discharge chambers are provided, one of which is a part of a master oscillator producing a very narrow band seed beam which is amplified in the second discharge chamber. The chambers can be controlled separately permitting separate optimization of wavelength parameters in the master oscillator and optimization of pulse energy parameters in the amplifying chamber. A preferred embodiment in an ArF excimer laser system configured as a MOPA and specifically designed for use as a light source for integrated circuit lithography. In the preferred MOPA embodiment, each chamber comprises a single tangential fan providing sufficient gas flow to permit operation at pulse rates of 4000 Hz or greater by clearing debris from the discharge region in less time than the approximately 0.25 milliseconds between pulses. The master oscillator is equipped with a line narrowing package having a very fast tuning mirror capable of controlling centerline wavelength on a pulse-to-pulse basis at repetition rates of 4000 Hz or greater to a precision of less than 0.2 pm.
Inventors
- 👤 David S. Knowles
- 👤 Daniel J. W. Brown
- 👤 Herve A. Besaucele
- 👤 David W. Myers
- 👤 Alexander I. Ershov
- 👤 William N. Partlo
- 👤 Richard L. Sandstrom
- 👤 Palash P. Das
- 👤 Stuart L. Anderson
- 👤 Igor V. Fomenkov
- 👤 Richard C. Ujazdowski
- 👤 Eckehard D. Onkels
- 👤 Richard M. Ness
- 👤 Scott T. Smith
- 👤 William G. Hulburd
- 👤 Jeffrey Oicles
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:54
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/10; G; G01; G01J; G01J1/00; G01J1/42; G01J1/4257; G03; G03F; G03F7/00; G03F7/70; G03F7/70008; G03F7/70025; G03F7/70041; G03F7/70216; G03F7/70325; G03F7/70333; G03F7/70483; G03F7/7055; G03F7/70575; G03F7/708; G03F7/70908; G03F7/70933; H01S3/005; H01S3/0057; H01S3/02; H01S3/03; H01S3/034; H01S3/0346; H01S3/036; H01S3/038; H01S3/0385; H01S3/05; H01S3/08; H01S3/08004; H01S3/09; H01S3/097; H01S3/09705; H01S3/102; H01S3/104; H01S3/105; H01S3/1055; H01S3/14; H01S3/22; H01S3/223; H01S3/225; H01S3/23; H01S3/2308; H01S3/2325; H01S3/2333; H01S3/2366; H01S3/0387; H01S3/04; H01S3/0404; H01S3/041; H01S3/08009; H01S3/08018; H01S3/08022; H01S3/08031; H01S3/08036; H01S3/091; H01S3/094; H01S3/0943; H01S3/09702; H01S3/0971; H01S3/0975; H01S3/13; H01S3/1305; H01S3/131; H01S3/134; H01S3/136; H01S3/137; H01S3/139; H01S3/2207; H01S3/2251; H01S3/2256; H01S3/2258
Claims Analysis
Total Claims: 79
Claim 1
Independent Claim
331 words
A very narrow band two chamber high repetition rate gas discharge laser system comprising: A) a first laser unit comprising: 1) a first discharge chamber containing; a) a first laser gas b) a first pair of elongated spaced apart electrodes defining a first discharge region, 2) a first fan for producing sufficient gas velocities of said first laser gas in said first discharge region to clear from said first 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, 3) a first heat exchanger system capable of removing at least 16 kw of heat energy from said first laser gas, 4) a line narrowing unit for narrowing spectral bandwidths of light pulses produced in said first discharge chamber, B) a second laser unit comprising: 1) a second discharge chamber containing: a) a second laser gas, b) a second pair of elongated spaced apart electrodes defining a second discharge region 2) a second fan for producing sufficient gas velocities of said second laser gas in said second discharge region to clear from said second 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, 3) a second heat exchanger system capable of removing at least 16 kw of heat energy from said second laser gas, C) a pulse power system configured to provide electrical pulses to said first pair of electrodes and to said second pair of electrodes sufficient to produce laser pulses at rates of about 4,000 pulses per second with precisely controlled pulse energies in excess of about 7 mJ, and D) a laser beam measurement and control system for measuring pulse energy, wavelength and bandwidth of laser output pulses produced by said two chamber laser system and controlling said laser output pulses in a feedback control arrangement.
Claim 2
Dependent Claim
331 words
A very narrow band two chamber high repetition rate gas discharge laser system comprising: A) a first laser unit comprising: 1) a first discharge chamber containing; a) a first laser gas b) a first pair of elongated spaced apart electrodes defining a first discharge region, 2) a first fan for producing sufficient gas velocities of said first laser gas in said first discharge region to clear from said first 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, 3) a first heat exchanger system capable of removing at least 16 kw of heat energy from said first laser gas, 4) a line narrowing unit for narrowing spectral bandwidths of light pulses produced in said first discharge chamber, B) a second laser unit comprising: 1) a second discharge chamber containing: a) a second laser gas, b) a second pair of elongated spaced apart electrodes defining a second discharge region 2) a second fan for producing sufficient gas velocities of said second laser gas in said second discharge region to clear from said second 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, 3) a second heat exchanger system capable of removing at least 16 kw of heat energy from said second laser gas, C) a pulse power system configured to provide electrical pulses to said first pair of electrodes and to said second pair of electrodes sufficient to produce laser pulses at rates of about 4,000 pulses per second with precisely controlled pulse energies in excess of about 7 mJ, and D) a laser beam measurement and control system for measuring pulse energy, wavelength and bandwidth of laser output pulses produced by said two chamber laser system and controlling said laser output pulses in a feedback control arrangement.
Claim 3
Dependent Claim
29 words
A laser system as in claim 1 wherein said first laser unit is configured as a master oscillator and said second laser unit is configured as a power amplifier.
Claim 4
Dependent Claim
16 words
A laser system as in claim 2 wherein said laser gas comprises argon, fluoride and neon.
Claim 5
Dependent Claim
16 words
A laser system as in claim 2 wherein said laser gas comprises krypton, fluorine and neon.
Claim 6
Dependent Claim
32 words
A laser system as in claim 2 wherein said laser gas comprises fluorine and a buffer gas chosen from a group consisting of neon, helium or a mixture of neon and helium.
Claim 7
Dependent Claim
22 words
A laser system as in claim 2 wherein said power amplifier is configured for two beam passes through the second discharge region.
Claim 8
Dependent Claim
22 words
A laser system as in claim 2 wherein said power amplifier is configured for four beam passes through the second discharge region.
Claim 9
Dependent Claim
25 words
A laser as in claim 2 wherein said master oscillator is configured to provide a resonant path making two passes through said first discharge region.
Claim 10
Dependent Claim
41 words
A laser as in claim 2 wherein said master oscillator is configured to provide a resonant path making two passes through said first discharge region and wherein said power amplifier is configured for four beam passes through the second discharge region.
Claim 11
Dependent Claim
29 words
A laser system as in claim 1 and further comprising an optical table for supporting resonant cavity optics of said first laser unit independent of said first discharge chamber.
Claim 12
Dependent Claim
29 words
A laser system as in claim 7 wherein said optical table is generally U-shaped and defines a U-cavity and wherein said first discharge chamber is mounted within the U-cavity.
Claim 13
Dependent Claim
27 words
A laser as in claim 1 and further comprising a vertically mounted optical table with said first and second discharge chambers mounted on said vertical optical table.
Claim 14
Dependent Claim
47 words
A laser system as in claim 1 wherein each of said first and second laser chambers define a gas flow path with a gradually increasing cross section downstream of said electrodes to permit recovery of a large percentage of static pressure drop occurring in the discharge regions.
Claim 15
Dependent Claim
29 words
A laser as in claim 2 and wherein said chamber also comprises a vane structure upstream of said discharge region for normalizing gas velocity upstream of said discharge region.
Claim 16
Dependent Claim
29 words
A laser as in claim 1 wherein said first fan and said second fan each are tangential fans and each comprises a shaft driven by two brushless DC motors.
Claim 17
Dependent Claim
13 words
A laser as in claim 15 wherein said motors are water cooled motors.
Claim 18
Dependent Claim
36 words
A laser as in claim 15 wherein each of said motors comprise a stator and each of said motors comprise a magnetic rotor contained in a pressure cup separating a said stator from said laser gas.
Claim 19
Dependent Claim
26 words
A laser as in claim 1 wherein said first and second fans are each tangential fans each comprising a blade structure machined from said aluminum stock.
Claim 20
Dependent Claim
18 words
A laser as in claim 15 wherein said blade structure has an outside diameter of about five inches.
Claim 21
Dependent Claim
17 words
A laser as in claim 19 wherein said blade structures comprise blade elements having sharp leading edges.
Claim 22
Dependent Claim
35 words
A laser as in claim 15 wherein said motors are sensorless motors and further comprising a master motor controller for controlling one of said motors and a slave motor controller for controlling the other motor.
Claim 23
Dependent Claim
22 words
A laser as in claim 15 wherein each of said tangential fans comprise blades which are angled with respect to said shaft.
Claim 24
Dependent Claim
15 words
A laser as in claim 1 wherein each finned heat exchanger system is water cooled.
Claim 25
Dependent Claim
20 words
A laser as in claim 23 wherein each heat exchanger system comprises at least four separate water cooled heat exchangers.
Claim 26
Dependent Claim
33 words
A laser as in claim 23 wherein each heat exchanger system comprises at least one heat exchanger having a tubular water flow passage wherein at least one turbulator is located in said path.
Claim 27
Dependent Claim
22 words
A laser as in claim 25 wherein each of said four heat exchangers comprise a tubular water flow passage containing a turbulator.
Claim 28
Dependent Claim
17 words
A laser as in claim 1 wherein said pulse power power system comprise water cooled electrical components.
Claim 29
Dependent Claim
27 words
A laser as in claim 27 wherein at least one of said water cooled components is a component operated at high voltages in excess of 12,000 volts.
Claim 30
Dependent Claim
22 words
A laser as in claim 28 wherein said high voltage is isolated from ground using an inductor through which cooling water flows.
Claim 31
Dependent Claim
26 words
A laser as in claim 1 wherein said pulse power system comprises a resonant charging system to charge a charging capacitor to a precisely controlled voltage.
Claim 32
Dependent Claim
15 words
A laser as in claim 30 wherein said resonance charging system comprises a De-Qing circuit.
Claim 33
Dependent Claim
15 words
A laser as in claim 30 wherein said resonance charging system comprises a bleed circuit.
Claim 34
Dependent Claim
19 words
A laser as in claim 30 wherein said resonant charging system comprises a De-Qing circuit and a bleed circuit.
Claim 35
Dependent Claim
25 words
A laser as in claim 1 wherein said pulse power system comprises a charging system comprised of at least three power supplies arranged in parallel.
Claim 36
Dependent Claim
67 words
A laser as in claim 1 wherein said laser beam measurement and control system comprises 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 37
Dependent Claim
31 words
A laser as in claim 35 wherein said measurement an control system also comprises a microprocessor programmed to calculate wavelength and bandwidth from fringe data located by said programmable logic device.
Claim 38
Dependent Claim
27 words
A laser as in claim 35 wherein said programmable logic device is programmed with an algorithm for calculating wavelength and bandwidth based on measurement of said fringes.
Claim 39
Dependent Claim
27 words
A laser as in claim 37 wherein said programmable logic device is configured to make calculations of wavelength and bandwidth faster than {fraction (1/4,000)} of a second.
Claim 40
Dependent Claim
15 words
A laser as in claim 35 wherein said etalon unit comprises a defractive diffusing element.
Claim 41
Dependent Claim
26 words
A laser as in claim 1 and further comprising a line narrowing unit comprising a tuning mirror driven at least in part by a PZT drive.
Claim 42
Dependent Claim
19 words
A laser as in claim 40 wherein said tuning mirror is also driven in part by a stepper motor.
Claim 43
Dependent Claim
12 words
A laser as in claim 40 and further comprising a pretuning means.
Claim 44
Dependent Claim
17 words
A laser as in claim 40 and further comprising an active tuning means comprising a learning algorithm.
Claim 45
Dependent Claim
14 words
A laser as in claim 40 and further comprising an adaptive feed forward algorithm.
Claim 46
Dependent Claim
31 words
A laser as in claim 40 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 47
Dependent Claim
32 words
A laser as in claim 1 wherein said line narrowing unit also comprises a four-prism beam expander configured to expand a beam in a single direction by a factor of about 45.
Claim 48
Dependent Claim
12 words
A laser as in claim 40 wherein said purge gas is helium.
Claim 49
Dependent Claim
22 words
A laser as in claim 1 and further comprising a nitrogen purge system comprising a nitrogen purge system comprising a nitrogen filter.
Claim 50
Dependent Claim
35 words
A laser as in claim 1 and further comprising a nitrogen purge system comprising a purge module comprising flow monitors said laser also comprising purge exhaust tubes for transporting exhaust purge gas from said laser.
Claim 51
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 52
Dependent Claim
57 words
A laser as in claim 1 and further comprising a beam enclosure system providing a first beam seal between a first window of said first chamber and line narrowing unit and a second beam seal between a second window of said first chamber and an output coupler unit, each of said beam seals comprising a metal bellows.
Claim 53
Dependent Claim
25 words
A laser as in claim 51 wherein each of said first and second beam seals are configured to permit easy replacement of said laser chamber.
Claim 54
Dependent Claim
46 words
A laser as in claim 51 wherein each of said beam seals contain no elastomer, provide vibration isolation from said chamber, provide beam train isolation from atmospheric gases and permit unrestricted replacement of said laser chamber without disturbance of said LNP or said output coupler unit.
Claim 55
Dependent Claim
15 words
A laser as in claim 51 wherein said beam enclosure system comprise vacuum compatible seals.
Claim 56
Dependent Claim
23 words
A laser as in claim 54 wherein a plurality of said seals are easy sealing bellows seals configured for easy removal by hand.
Claim 57
Dependent Claim
83 words
A laser as in claim 1 wherein said measurement and control system comprises a primary beam splitter for splitting off a small percentage of 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 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 58
Dependent Claim
21 words
A laser as in claim 56 and further comprising a purge means for purging said isolated region with a purge gas.
Claim 59
Dependent Claim
43 words
A laser as in claim 57 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 60
Dependent Claim
33 words
A laser system as in claim 1 wherein said system is configured to operate either of a KrF laser system, an ArF laser system or an F 2 laser system with minor modifications.
Claim 61
Dependent Claim
29 words
A laser system as in claim 1 wherein substantially all components are contained in a laser enclosure but said system comprises an AC/DC module physically separate from the enclosure.
Claim 62
Dependent Claim
39 words
A laser system as in claim 1 wherein said pulse power system comprises a master oscillator charging capacitor bank and a power amplifier charging capacitor bank and a resonant charger configured to charge both charging capacitor banks in parallel.
Claim 63
Dependent Claim
26 words
A laser as in claim 61 wherein said pulse power system comprises a power supply configured to furnish at least 2000V supply to said resonant charges.
Claim 64
Dependent Claim
29 words
A laser as in claim 1 and further comprising a gas control system for controlling F 2 concentrations in said first laser gas to control master oscillator beam parameters.
Claim 65
Dependent Claim
29 words
A laser as in claim 1 and further comprising a gas control system for controlling laser gas pressure in said first laser gas to control master oscillator beam parameters.
Claim 66
Dependent Claim
33 words
A laser as in claim 2 and further comprising a discharge timing controller for triggering discharges in said power amplifier to occur between 20 and 60 ns after discharges in said master oscillator.
Claim 67
Dependent Claim
28 words
A laser as in claim 2 and further comprising a discharge controller programmed to cause in some circumstances discharges so timed to avoid any significant output pulse energy.
Claim 68
Dependent Claim
33 words
A laser as in claim 66 wherein said controller in said some circumstances is programmed to cause discharge in said power amplifier at least 20 ns prior to discharge in said master oscillator.
Claim 69
Dependent Claim
22 words
A laser as in claim 1 and further comprising a pulse multiplier unit for increasing duration of output pulses from said laser.
Claim 70
Dependent Claim
186 words
A laser as in claim 68 wherein pulse multiplier unit is arranged to receive said output pulse laser beam and to multiply the number of pulses per second by at least a factor of two so as to produce a single multiplier output pulse beam comprised of a larger number of pulses with substantially reduced intensity values as compared with the laser output pulses, and pulse multiplier unit comprising: (1) a first beam splitter arranged to separate a portion of said output beam, the separated portion defining a delayed portion, and the output beam defining a beam size and angular spread at said first beam splitter; (2) a first delay path originating and terminating at said first beam splitter said first delay path comprising at least two focusing mirrors, said mirrors being arranged to focus said delayed portion at a focal point within said first delay path and to return said delayed portion to said first beam splitter with a beam size and angular spread equal to or approximately equal to the beam size and angular spread of the output beam at said first beam splitter.
Claim 71
Dependent Claim
17 words
A laser system as in claim 69 wherein said at least two focusing mirrors are spherical mirrors.
Claim 72
Dependent Claim
20 words
A laser system as in claim 69 and further comprising a second delay path comprising at least two spherical mirrors.
Claim 73
Dependent Claim
16 words
A laser system as in claim 69 wherein said first delay path comprises four focusing mirrors.
Claim 74
Dependent Claim
26 words
A laser system as in claim 72 and further comprising said second delay path created by a second beam splitter located in said first delay path.
Claim 75
Dependent Claim
86 words
A laser as in claim 69 wherein said first delay path comprises a second beam splitter and further comprising a second delay path comprising at least two focusing mirrors, said mirrors being arranged to focus said delayed portion at a focal point within said first delay path and to return said delayed portion to said first beam splitter with a beam size and angular spread equal to or approximately equal to the beam size and angular spread of the output beam at said first beam splitter.
Claim 76
Dependent Claim
30 words
A laser as in claim 69 wherein said first beam splitter is configured to direct a laser beam in at least two directions utilizing optical property of frustrated internal reflection.
Claim 77
Dependent Claim
43 words
A laser as in claim 69 wherein said first beam splitter is comprised of two transparent optical elements each element having a flat surface, said optical elements being positioned with said surfaces parallel to each other and separated by less than 200 nm.
Claim 78
Dependent Claim
33 words
A laser as in claim 69 wherein said first beam splitter is an uncoated optical element oriented at an angle with said output laser beam so as to achieve a desired reflection-transmission ratio.
Claim 79
Dependent Claim
76 words
A laser as in claim 1 wherein said pulse power system comprises a first charging capacitor bank and a first pulse compression circuit for providing electrical pulses to said first pair of electrodes and a second charging capacitor bank and a second pulse compression circuit for providing electrical pulses to said second pair of electrodes and a resonant charging system to charge in parallel said first and second charging capacitor banks to a precisely controlled voltage.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2006-09-22 | 2007-03-24 | 2007-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2010-09-22 | 2011-03-24 | 2011-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2014-09-22 | 2015-03-24 | 2015-09-23 | $7700.00 | Window Closed / Lapsed |