US6128323A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Reliable modular production quality narrow-band high REP rate excimer laser
Assignee: Cymer LLC
•
Filing: 1998-09-18
•
Granted: 2000-10-03
•
Expires: 2018-09-18
Abstract
Abstract The present invention provides a reliable modular production quality excimer laser capable of producing 10 mJ laser pulses at 2000 Hz with a full width half, maximum bandwidth of about 0.6 pm or less. Replaceable modules include a laser chamber; a pulse power system comprised of three modules; an optical resonator comprised of a line narrowing module and an output coupler module; a wavemeter module, an electrical control module, a cooling water module and a gas control module. Improvements in the laser chamber permitting the higher pulse rates and improved bandwidth performance include a single upstream preionizer tube and a high efficiency chamber. The chamber is designed for operation at lower fluorine concentration. Important improvements have been provided in the pulse power unit to produce faster rise time and improved pulse energy control. These improvements include an increased capacity high voltage power supply with a voltage bleed-down circuit for precise voltage trimming, an improved commutation module that generates a high voltage pulse from the capacitors charged by the high voltage power supply and amplifies the pulse voltage 23 times with a very fast voltage transformer having a secondary winding consisting of a single four-segment stainless steel rod. A novel design for the compression head saturable inductor greatly reduces the quantity of transformer oil required and virtually eliminates the possibility of oil leakage which in the past has posed a hazard.
Inventors
- 👤 David W. Myers
- 👤 Herve A. Besaucele
- 👤 Palash P. Das
- 👤 Thomas P. Duffey
- 👤 Alexander I. Ershov
- 👤 Igor V. Fomenkov
- 👤 Thomas Hofmann
- 👤 Richard G. Morton
- 👤 Richard M. Ness
- 👤 Peter C. Newman
- 👤 Robert G. Ozarski
- 👤 Gamaralalage G. Padmabandu
- 👤 William N. Partlo
- 👤 Daniel A. Rothweil
- 👤 Richard L. Sandstrom
- 👤 Paul S. Thompson
- 👤 Richard C. Ujazdowski
- 👤 Tom A. Watson
- 👤 R. Kyle Webb
- 👤 Paolo Zambon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 06:03
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70008; G03F7/70025; G03F7/70041; G03F7/70216; G03F7/70358; G03F7/70483; G03F7/7055; G03F7/70558; G03F7/70575; H; H01; H01S; H01S3/00; H01S3/02; H01S3/03; H01S3/036; H01S3/04; H01S3/041; H01S3/09; H01S3/097; H01S3/0971; H01S3/10; H01S3/105; H01S3/1055; H01S3/13; H01S3/131; H01S3/134; H01S3/14; H01S3/22; H01S3/223; H01S3/225; H03; H03K; H03K17/00; H03K17/51; H03K17/80; H03K3/00; H03K3/02; H03K3/53; H03K3/57; H01S3/05; H01S3/08; H01S3/08004; H01S3/08009; H01S3/081; H01S3/0811; H01S3/0812; H01S3/139; H01S3/1392; H01S3/2251; H01S3/2256
Claims Analysis
Total Claims: 58
Claim 1
Independent Claim
186 words
An electric discharge laser for producing a narrow band pulsed laser beam at repetition rates of at least about 2000 Hz, said laser comprising: A. a laser chamber comprising: 1) two elongated electrodes; 2) a laser gas comprising a) a noble gas, b) fluorine, and c) a buffer gas; 3) a gas circulator for circulating said gas between said electrodes at speeds of at least two cm/millisecond B. a pulse power system comprising a power supply and pulse compression and amplification circuits and pulse power controls for producing high voltage electrical pulses of at least 14,000 volts across said electrodes at rates of at least about 2000 Hz, C. a line narrowing system for controlling wavelengths of said laser beams to less than about 0.6 pm, FWHM; and D. a laser pulse energy control system for controlling the voltage provided by said pulse power system, said control system comprising a laser pulse energy monitor and a computer processor programmed with an algorithm for calculating, based on historical pulse energy data, electrical pulses needed to produce laser pulses having pulse energies within a desired range of energies.
Claim 2
Dependent Claim
186 words
An electric discharge laser for producing a narrow band pulsed laser beam at repetition rates of at least about 2000 Hz, said laser comprising: A. a laser chamber comprising: 1) two elongated electrodes; 2) a laser gas comprising a) a noble gas, b) fluorine, and c) a buffer gas; 3) a gas circulator for circulating said gas between said electrodes at speeds of at least two cm/millisecond B. a pulse power system comprising a power supply and pulse compression and amplification circuits and pulse power controls for producing high voltage electrical pulses of at least 14,000 volts across said electrodes at rates of at least about 2000 Hz, C. a line narrowing system for controlling wavelengths of said laser beams to less than about 0.6 pm, FWHM; and D. a laser pulse energy control system for controlling the voltage provided by said pulse power system, said control system comprising a laser pulse energy monitor and a computer processor programmed with an algorithm for calculating, based on historical pulse energy data, electrical pulses needed to produce laser pulses having pulse energies within a desired range of energies.
Claim 3
Dependent Claim
38 words
A laser as in claim 1 wherein said chamber, said pulse power system, said line narrowing system, said energy control system and substantially all electrical, optical and mechanical components of said laser are contained in quickly replaceable modules.
Claim 4
Dependent Claim
36 words
A laser as in claim 1 wherein said chamber and said gas circulator define a gas flow path and an upstream direction and said laser also comprises a single preionizer tube located upstream of said electrodes.
Claim 5
Dependent Claim
47 words
A laser as in claim 3, wherein each of said electrodes define an electrode length and said single preionizer tube comprises a grounded electrically conducting rod positioned along the axis of an Al 2 O 3 hollow cylindrical tube having a length longer than said electrode length.
Claim 6
Dependent Claim
38 words
A laser as in claim 1, wherein said line narrowing system comprises a tuning mirror, a grating tuned to a nominal wavelength, and at least three beam expanding prisms, at least one of which prisms comprises calcium fluoride.
Claim 7
Dependent Claim
17 words
A laser as in claim 5, wherein all of said at least three prisms comprise calcium fluoride.
Claim 8
Dependent Claim
26 words
A laser as in claim 1 wherein said laser gas contains oxygen at a concentration of between 1 part per million and 10 parts per million.
Claim 9
Dependent Claim
29 words
A laser as in claim 1 wherein said two elongated electrodes define a cathode and an anode, said anode being supported by an anode support bar comprising cooling fins.
Claim 10
Dependent Claim
23 words
A laser as in claim 1 wherein said two elongated electrodes define a cathode and an anode and said anode comprises cooling fins.
Claim 11
Dependent Claim
25 words
A laser as in claim 8 wherein said anode and said anode support bar together have a combined mass of at least about 3.4 kg.
Claim 12
Dependent Claim
26 words
A laser as in claim 1 wherein said pulse power system comprises at least three modules each of which is designed for quick removal and replacement.
Claim 13
Dependent Claim
56 words
A laser as in claim 1 wherein said laser chamber defines a chamber structure and wherein said two elongated electrodes define a cathode and an anode and said cathode is insulated from said chamber structure by a single piece insulator comprising Al 2 O 3 , which is attached to a portion of said chamber structure.
Claim 14
Dependent Claim
39 words
A laser as in claim 12 wherein the portion of said chamber structure to which said single piece insulator is attached comprises a material having a coefficient of thermal expansion similar to that of Al 2 O 3 .
Claim 15
Dependent Claim
14 words
A laser as in claim 13 wherein said structure material is ASTM A36 steel.
Claim 16
Dependent Claim
17 words
A laser as in claim 12 wherein said cathode is mounted directly on said single piece insulator.
Claim 17
Dependent Claim
26 words
A laser as in claim 1 wherein said laser chamber includes a plurality of seals and all seals exposed to said laser gas are metal seals.
Claim 18
Dependent Claim
13 words
A laser as in claim 1 further comprising flow vane structures comprising monel.
Claim 19
Dependent Claim
11 words
A laser as in claim 1 and further comprising acoustic baffles.
Claim 20
Dependent Claim
50 words
A laser as in claim 2 wherein said gas circulator comprises a plurality of bearings and wherein said two elongated electrodes define a cathode and an anode and said anode is supported by an anode support bar having a tapered surface positioned to reduce aerodynamic reaction forces on said bearings.
Claim 21
Dependent Claim
79 words
A laser as in claim 1 wherein said power supply comprises a rectifier for converting AC power to DC power, an inverter for converting the DC power to high frequency AC power, a step-up transformer for increasing the voltage of said high frequency AC power to a higher voltage, a rectifier for converting the higher voltage to charge a charging capacitor to a voltage at or approximately at a command voltage established by said laser pulse energy control system.
Claim 22
Dependent Claim
35 words
A laser as in claim 20 wherein said power supply is configured to slightly over charge said charging capacitor and further comprises a bleed circuit to bleed down said charging capacitor to said command voltage.
Claim 23
Dependent Claim
48 words
A laser as in claim 21 wherein said pulse power system comprises a solid state switch which upon closing initiates said high voltage electrical pulses by allowing charge to flow from said charging capacitor to a second capacitor to create a high voltage charge on said second capacitor.
Claim 24
Dependent Claim
93 words
A laser as in claim 12 and further comprising an inductor, a pulse transformer having a primary side and an output terminal, and a third capacitor wherein said inductor, pulse transformer and said third capacitor are arranged to permit the high voltage charge on said second capacitor to flow to ground through the primary side of said pulse transformer in order to produce an electrical pulse having a voltage higher than that of said high voltage charge at the output terminal of said pulse transformer to be stored temporarily on said third capacitor.
Claim 25
Dependent Claim
51 words
A laser as in claim 23 wherein said primary side of said pulse transformer comprises a plurality of hollow spools, each spool defining an axis, connected in series, and a secondary side of said pulse transformer comprises at least one rod co-aligned with an axis of said plurality of hollow spools.
Claim 26
Dependent Claim
32 words
A laser as in claim 24 wherein said at least one rod is four rods connected in series and defining two leads, respectively a ground lead and a very high voltage lead.
Claim 27
Dependent Claim
39 words
A laser as in claim 1 wherein said laser pulse power system comprises at least one saturable inductor with a coil immersed in oil contained in a pot which also serves as the high voltage lead of the inductor.
Claim 28
Dependent Claim
70 words
A laser as in claim 1 and further comprising an electric power distribution module comprising a plurality of multi-pin electrical connectors mounted on a frame and at least one easily replaceable breaker-relay DIN rail having mounted thereon a plurality of breakers and/or relays and also having mounted thereon with respect to each breaker and/or relay a multi-pin connector for quick electrical connection with a mating multi-pin connector on said frame.
Claim 29
Dependent Claim
31 words
A laser as in claim 27 wherein said at least one breaker-relay DIN rail is a plurality of breaker-relay DIN rails and said frame is in the form of stair steps.
Claim 30
Dependent Claim
70 words
A laser as in claim 1 wherein said gas circulator comprises a blower comprising a shaft supported by at least two magnetic bearings, each bearing comprising a stator and a rotor; said shaft bearing driven by a motor comprising a stator and a rotor, said blower also comprising a sealing means for sealing said rotors within an environment containing said laser gas with said stators outside said laser gas environment.
Claim 31
Dependent Claim
76 words
A laser as in claim 1 and further comprising an N 2 purge system providing an N 2 purge flow to all laser optical components outside the laser chamber wherein said purge flow is contained at a pressure of less than 10 pascals, and wherein an outlet of said purge flow from each of said optical components is connected to a flow rate sensing device for monitoring of the operation of said N 2 purge system.
Claim 32
Dependent Claim
15 words
A laser as in claim 1 and further comprising a line narrowing etalon output coupler.
Claim 33
Dependent Claim
15 words
A laser as in claim 5 and further comprising a line narrowing etalon output coupler.
Claim 34
Dependent Claim
33 words
A laser as in claim 32 wherein said etalon output coupler is configured and aligned to operate in a reflective mode and is tuned to substantially the same nominal wavelength as said grating.
Claim 35
Dependent Claim
25 words
A laser as in claim 1 and further comprising a wavemeter configured to measure wavelengths of laser pulses at rates of at least 2 kHz.
Claim 36
Dependent Claim
69 words
A laser as in claim 1 and further comprising a wavemeter, said wavemeter comprising a grating-based wavelength monitor providing a coarse measurement of wavelength being aligned to focus an optical indication of relative wavelength at a first location on a diode array and an etalon-based wavelength monitor being aligned to focus an optical indication of relative wavelength at a location on said diode array different from said first location.
Claim 37
Dependent Claim
24 words
A laser as in claim 35 and further comprising an atomic reference unit for calibrating said grating-based wavelength monitor and said etalon-based wavelength monitor.
Claim 38
Dependent Claim
43 words
A laser as in claim 1 and further comprising a blower and an anode support means comprising a tapered surface for reducing the magnitude of aerodynamic reaction forces resulting from laser gas exiting said blower and being redirected by said anode support means.
Claim 39
Dependent Claim
59 words
A laser as in claim 1 and further comprising a fluorine injection system comprising a processor programmed with an algorithm designed to cause fluorine to be injected continuously or at intervals of less than 30 minutes in order to maintain fluorine concentration substantially constant at a desired concentration over extended time periods of at least more than one day.
Claim 40
Dependent Claim
38 words
A laser as in claim 38 further comprising a feedback circuit providing to said processor a voltage signal representative of laser discharge voltages, which signal is used by said processor to maintain said signal within a predetermined range.
Claim 41
Dependent Claim
28 words
A laser as in claim 39 wherein said predetermined range is revised periodically in order to keep the laser operating with a fluorine concentration within a desired range.
Claim 42
Dependent Claim
26 words
A laser as in claim 38 further comprising a means for periodically determining a laser parameter representative of a temporal pulse width of the laser pulses.
Claim 43
Dependent Claim
19 words
A laser as in claim 41 wherein said determined parameter represents the full width half maximum temporal pulse width.
Claim 44
Dependent Claim
16 words
A laser as in claim 41 wherein said determined parameter is an integral square pulse width.
Claim 45
Dependent Claim
121 words
A laser as in claim 1 and further comprising a component cooling system said system comprising: A. an enclosure housing a plurality of laser components, said components defining at least four major waste heat sources, B. a vent containing a blower to maintain said components in a slight vacuum, C. a chilled water cooling system comprising a system of water pipes providing chilled water flow to a heat exchanger located inside said laser chamber and at least three other water/air heat exchangers, positioned near said waste heat sources within said enclosure, D. at least one blower positioned near each of said at least three other heat exchangers and oriented to force air cooled by said heat exchanger onto said heat source.
Claim 46
Dependent Claim
30 words
A laser as in claim 44 wherein said heat sources comprise respectively components of a high voltage power supply, components of a commutator, and components of a voltage compression circuit.
Claim 47
Dependent Claim
225 words
An electric discharge laser for producing a narrow band pulsed laser beam at a repetition rate of at least about 2 Khz, said laser comprising: A. a quickly replaceable laser chamber module comprising: 1) two elongated electrodes 2) a laser gas comprising a noble gas, fluorine and a buffer gas, 3) a gas circulator system for circulating said laser gas between said electrodes at at least two cm/millisecond comprising: a) a braze-free blade structure defining a shaft, b) a brushless motor for rotating said shaft, c) magnetic bearings for supporting said shaft; said motor and said bearings having rotors attached to said shaft and sealed within an environment exposed to said laser gas, and said motor and said bearings having stators outside of said laser gas environment, B. a pulse power system substantially contained within at least one quickly replaceable module and comprising: 1) a processor controlled high voltage power supply for periodically, at rates of at least about 2000 Hz, charging with electrical energy a charging capacitor to a predetermined pulse control voltage, 2) a compression and amplification circuit for connecting electrical energy stored on said charging capacitor into a high voltage electrical pulse of at least 14,000 volts across said electrodes, and C. a quickly replaceable line narrowing module for controlling wavelength of said laser beam to less than about 0.6 pm, FWHM.
Claim 48
Dependent Claim
225 words
An electric discharge laser for producing a narrow band pulsed laser beam at a repetition rate of at least about 2 Khz, said laser comprising: A. a quickly replaceable laser chamber module comprising: 1) two elongated electrodes 2) a laser gas comprising a noble gas, fluorine and a buffer gas, 3) a gas circulator system for circulating said laser gas between said electrodes at at least two cm/millisecond comprising: a) a braze-free blade structure defining a shaft, b) a brushless motor for rotating said shaft, c) magnetic bearings for supporting said shaft; said motor and said bearings having rotors attached to said shaft and sealed within an environment exposed to said laser gas, and said motor and said bearings having stators outside of said laser gas environment, B. a pulse power system substantially contained within at least one quickly replaceable module and comprising: 1) a processor controlled high voltage power supply for periodically, at rates of at least about 2000 Hz, charging with electrical energy a charging capacitor to a predetermined pulse control voltage, 2) a compression and amplification circuit for connecting electrical energy stored on said charging capacitor into a high voltage electrical pulse of at least 14,000 volts across said electrodes, and C. a quickly replaceable line narrowing module for controlling wavelength of said laser beam to less than about 0.6 pm, FWHM.
Claim 49
Dependent Claim
78 words
A laser as in claim 46 wherein said chamber and said gas circulator define a gas flow path and an upstream direction and said laser also comprises a single preionizer tube located upstream of said electrodes, and wherein each of said electrodes defines an electrode length, and said single preionizer tube comprises a grounded electrically conducting rod positioned along the axis of an Al 2 O 3 hollow cylindrical tube having a length longer than said electrode length.
Claim 50
Dependent Claim
31 words
A laser as in claim 46 wherein said line narrowing module comprises a tuning mirror, a grating, and at least three beam expanding prisms, all of said prisms comprising calcium fluoride.
Claim 51
Dependent Claim
30 words
A laser as in claim 1, wherein said electric discharge laser is selected from the group consisting of ArF and KrF excimer lasers and fluorine (F 2 ) molecular lasers.
Claim 52
Dependent Claim
30 words
A laser as in claim 46, wherein said electric discharge laser is selected from the group consisting of ArF and KrF excimer lasers and fluorine (F 2 ) molecular lasers.
Claim 53
Dependent Claim
162 words
A laser as in claim 1 and further comprising a processing means programmed with an algorithm for controlling pulse energy and integrated energy dose in bursts of pulses produced by the laser, said algorithm comprising steps in which: A) the laser output energy of each pulse in a burst of pulses defining a present burst of pulses is measured, B) the rate of change of pulse energy with charging voltage is determined, C) a pulse energy error is determined with respect to a pulse occurring prior to a next pulse in the present burst of pulses, D) an integrated dose error is determined for all previous pulses in the present burst of pulses, and E) a charging voltage for a next pulse needed to produce in said next pulse a pulse energy converging on a target pulse energy is determined using the pulse energy error, the integrated dose error, the rate of change of energy with charging voltage, and a reference voltage.
Claim 54
Dependent Claim
26 words
A laser as in claim 51 wherein the reference voltage for said next pulse is a voltage calculated using prior pulse energy and charging voltage data.
Claim 55
Dependent Claim
94 words
A laser as in claim 52 wherein: for a next pulse in a first set of consecutive pulses in said present burst, a specified voltage calculated using charging voltage and pulse energy data for a pulse in a previous burst of pulses corresponding to said next pulse is utilized as the reference voltage, and for a next pulse in a second set of consecutive pulses in said present burst, the reference voltage is a voltage specified for a pulse immediately preceding the next pulse in said second set of pulses in said present burst.
Claim 56
Dependent Claim
228 words
A laser as in claim 51 wherein charging voltage V N for consecutive pulses P 1 , P 2 . . . P k is determined as follows: V.sub.N =(V.sub.B).sub.N -(V.sub.C).sub.N-1 N=1,2, . . . k where: ______________________________________
V.sub.N =
charging voltage for N'th pulse,
(V.sub.B).sub.N =
an array of k stored charging voltages which represents the
current best estimate of the charging voltage required to
produce the target pulse energy E.sub.T for the N'th pulse in
the K region;
(V.sub.C).sub.N-1 =
a voltage correction based on the energy errors which
occurred for the previous pulses in the burst, up to
pulse N - 1
##STR3##
______________________________________ where by definition, (V C ) 0 =0, ______________________________________
A,B = fractions typically between 0 and 1, preferably about 0.5,
ε.sub.i =
the energy error of the i'th pulse
= E.sub.i - E.sub.T, wherein E.sub.i is the pulse energy for the
i'th pulse,
and E.sub.T is the target pulse energy
D.sub.i =
the cumulative dose error of the burst, including all pulses
from 1 through i
##STR4##
dE/dV = a rate of change of pulse energy with charging voltage,
______________________________________ wherein the stored values (V B ) N are updated during or after each burst according to the following relation: ##EQU11## where the index M refers to the burst number and C=a fraction typically between 0 and 1, preferably about 0.3.
Claim 57
Dependent Claim
51 words
A laser as in claim 54 wherein charging voltage V n for pulses P K+1 to P f , wherein P f is the final pulse in the burst, is determined as follows: ##EQU12## where: V N =charging voltage for the N'th pulse V N-1 =charging voltage for N-1'st (previous) pulse.
Claim 58
Dependent Claim
47 words
The laser as in claim 55 wherein dE/dV is determined by dithering the voltage in a controlled manner for two successive pulses, j and j+1 where: ##EQU13## where V Dither =a fixed voltage and V.sub.j+1 =V.sub.j -2·V.sub.Dither, and after pulse j+1, dE/dV is calculated according to: ##EQU14##
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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) | 2003-10-03 | 2004-04-03 | 2004-10-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-10-03 | 2008-04-03 | 2008-10-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-10-03 | 2012-04-03 | 2012-10-03 | $7700.00 | Window Closed / Lapsed |