US6018537A — Reliable, modular, production quality narrow-band…

Claim 1

Independent Claim 194 words

A very narrow band reliable modular production quality high repetition rate ArF excimer laser for producing a narrow band pulsed laser beam at repetition rates of at least about 1000 Hz, said laser comprising: A. a quickly replaceable laser chamber module comprising a laser chamber comprising: 1) two elongated electrodes; 2) a laser gas comprised of a) fluorine, and b) a noble gas; 3) a gas circulator for circulating said gas between said electrodes at speeds of at least two cm/millisecond B. a modular pulse power system comprised of at least one quickly replaceable module, said system being comprised of 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 1000 Hz; and C. 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 194 words

A very narrow band reliable modular production quality high repetition rate ArF excimer laser for producing a narrow band pulsed laser beam at repetition rates of at least about 1000 Hz, said laser comprising: A. a quickly replaceable laser chamber module comprising a laser chamber comprising: 1) two elongated electrodes; 2) a laser gas comprised of a) fluorine, and b) a noble gas; 3) a gas circulator for circulating said gas between said electrodes at speeds of at least two cm/millisecond B. a modular pulse power system comprised of at least one quickly replaceable module, said system being comprised of 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 1000 Hz; and C. 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 40 words

A laser as in claim 2 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 5

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 6

Dependent Claim 49 words

A laser as in claim 1 wherein each of said electrodes define an electrode length and said single preionizer tube is comprised of 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 7

Dependent Claim 19 words

A laser as in claim 1 wherein all of said at least three prisms are comprised of calcium fluoride.

Claim 8

Dependent Claim 25 words

A laser as in claim 1 wherein said two elongated electrodes define a cathode and an anode and said anode support bar comprises cooling fins.

Claim 9

Dependent Claim 25 words

A laser as in claim 7 herein said anode and said anode support bar together have a combined mass of at least about 3.4 kg.

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 30 words

A laser as in claim 1 wherein said modular pulse power system is comprised of at least three modules which each of which are designed for quick removal and replacement.

Claim 12

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 comprised of Al 2 O 3 which is attached to a portion of said chamber structure.

Claim 13

Dependent Claim 39 words

A laser as in claim 11 wherein the portion of said chamber structure to which said single piece insulator is comprised of a material having a coefficient of thermal expansion similar to that of Al 2 O 3 .

Claim 14

Dependent Claim 14 words

A laser as in claim 12 wherein said structure material is ASTM A36 steel.

Claim 15

Dependent Claim 17 words

A laser as in claim 13 wherein said cathode is mounted directly on said single piece insulator.

Claim 16

Dependent Claim 17 words

A laser as in claim 1 wherein all seals exposed to said laser gas are metal seals.

Claim 17

Dependent Claim 14 words

A laser as in claim 1 further comprising flow vane structures comprised of monel.

Claim 18

Dependent Claim 11 words

A laser as in claim 1 and further comprising acoustic baffles.

Claim 19

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 20

Dependent Claim 35 words

A laser as in claim 18 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 21

Dependent Claim 48 words

A laser as in claim 19 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 record capacitor.

Claim 22

Dependent Claim 75 words

A laser as in claim 20 and further comprising an inductor, a pulse transformer 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 a very high voltage pulse at the output of said pulse transformer to be stored temporarily on said third capacitor.

Claim 23

Dependent Claim 53 words

A laser as in claim 21 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 is comprised of at least one rod co-aligned with the axis of a plurality of said spools.

Claim 24

Dependent Claim 35 words

A laser as in claim 22 wherein said at least one rod is four rods connected in series and defining two leads, one defining a ground lead and the other a very high voltage lead.

Claim 25

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 emersed in oil contained in a pot which also serves as the high voltage lead of the inductor.

Claim 26

Dependent Claim 71 words

A laser as in claim 1 wherein said gas circulator comprises a blower comprising a shaft supported by active at least two magnetic bearings, each bearing comprising a stator and a rotor; said shaft bearing driver 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 stator outside said laser gas environment.

Claim 27

Dependent Claim 23 words

A laser as in claim 1 wherein said gas circulator comprises a blower comprising a shaft supported by at least two ceramic bearings.

Claim 28

Dependent Claim 43 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.

Claim 29

Dependent Claim 481 words

A laser as in claim 1 and further comprising a means of measuring the rate of change of pulse energy with changing voltage ΔE/ΔV, and a computer controller programmed with an algorithm for controlling pulse energy and integrated energy dose in a burst of pulses defining present burst pulses, P 1 , P 2 . . . P N . . . P k , P K+1 , P K+2 . . . P K+N' . . . P 1 , P 2 . . . P N-1 , P N , from said laser having a pulse power system including a high voltage charging system defining a charging voltage, said algorithm comprising the steps of: A) measuring the energy in each pulse of said burst of pulses, B) determining a rate of change of pulse energy with charging voltage, ΔE/ΔV, C) controlling the pulse energy of each pulse P N in the first K pulses, in said burst of pulses by regulating the charging voltage of the laser utilizing a computer processor programmed with a first algorithm which: (1) determines for each P N a pulse energy error, ε, based on a measured energy of at least one previous pulse in said burst and a predetermined target pulse energy value, (2) determines for each P N an integrated dose error, D, of all previous pulses P 1 through P N-1 in said burst, (3) determines a charging voltage V N , for each of said pulses, P N , in said first plurality of pulses using: (i) said ΔE/ΔV (ii) said ε (iii) said D (iv) a reference voltage based on specified voltages for PN in a plurality of previous bursts, D) controlling the pulse energy of each pulse P K+N' in pulses following P K in said burst of pulses by regulating the charging voltage of the laser utilizing a computer processor programmed with a second algorithm which: (1) determines for each P N a pulse energy error, ε, based on a measured energy of at least one previous pulse in said burst and a predetermined target pulse energy value, (2) determines for each P N an integrated dose error, D, of all previous pulses, P 1 through P N-1 in said burst, (3) determines a charging voltage, V N , for each of said pulses, P N in said first plurality of pulses using: (i) said ΔE/ΔV (ii) said ε (iii) said D (iv) a reference voltage based on specified voltages for P N in a plurality of previous bursts, wherein said V N 's in said fast and second algorithms are functions of at least said ΔE/ΔV, said ε, said D and said at least one reference voltage and said V N 's when calculated one utilized to adjust said charging voltage to control both the individual pulse energy and the integrated energy dose to desired values.

Claim 30

Dependent Claim 40 words

A laser as in claim 1 and further comprising 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 31

Dependent Claim 57 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 several days.

Claim 32

Dependent Claim 43 words

A laser as in claim 30 wherein said fluorine injection system and further comprising a feedback 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 33

Dependent Claim 28 words

A laser as in claim 31 wherein said predetermined range is revised periodically in order to keep the laser operating with a fluorine concentration within a desired range.

Claim 34

Dependent Claim 26 words

A laser as in claim 32 further comprising a means for periodically determining a laser parameter representative of a temporal pulse width of the laser pulses.

Claim 35

Dependent Claim 16 words

A laser as in claim 30 wherein said determined parameter is the integral square pulse width.

Claim 36

Dependent Claim 208 words

A reliable modular production quality high repetition rate excimer laser for producing a narrow band pulsed laser beam at a repetition rate of at least about 1 Khz, said laser comprising: A. a quickly replaceable laser chamber module comprising: 1) two elongated electrodes 2) a laser gas comprised of 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 a stator 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 1000 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 pulses of at least 14,000 volts across said electrodes.

Claim 37

Dependent Claim 208 words

A reliable modular production quality high repetition rate excimer laser for producing a narrow band pulsed laser beam at a repetition rate of at least about 1 Khz, said laser comprising: A. a quickly replaceable laser chamber module comprising: 1) two elongated electrodes 2) a laser gas comprised of 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 a stator 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 1000 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 pulses of at least 14,000 volts across said electrodes.

Claim 38

Dependent Claim 80 words

A laser as in claim 35 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 electrode and wherein each of said electrodes define an electrode length and said single preionizer tube is comprised of 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 39

Dependent Claim 481 words

A laser as in claim 35 and further comprising a means of measuring the rate of change of pulse energy with changing voltage ΔE/ΔV, and a computer controller programmed with an algorithm for controlling pulse energy and integrated energy dose in a burst of pulses defining present burst pulses, P 1 , P 2 . . . P N . . . P K , P K+1 , P K+2 . . . P K+N' . . . P 1 , P 2 . . . P N-1 , P N , from said laser having a pulse power system including a high voltage charging system defining a charging voltage, said algorithm comprising the steps of: A) measuring the energy in each pulse of said burst of pulses, B) determining a rate of change of pulse energy with charging voltage, ΔE/ΔV, C) controlling the pulse energy of each pulse P N in the first K pulses, in said burst of pulses by regulating the charging voltage of the laser utilizing a computer processor programmed with a first algorithm which: (1) determines for each P N a pulse energy error, ε, based on a measured energy of at least one previous pulse in said burst and a predetermined target pulse energy value, (2) determines for each P N an integrated dose error, D, of all previous pulses P 1 through P N-1 in said burst, (3) determines a charging voltage V N , for each of said pulses, P N , in said first plurality of pulses using: (i) said ΔE/ΔV (ii) said ε (iii) said D (v) a reference voltage base on specified voltages for PN in a plurality of previous bursts, D) controlling the pulse energy of each pulse P K+N' in pulses following P K in said burst of pulses by regulating the charging voltage of the laser utilizing a computer processor programmed with a second algorithm which: (1) determines for each P N a pulse energy error, ε, based on a measured energy of at least one previous pulse in said burst and a predetermined target pulse energy value, (2) determines for each P N an integrated dose error, D, of all previous pulses, P 1 through P N-1 in said burst, (3) determines a charging voltage, V N , for each of said pulses, P N in said first plurality of pulses using: (i) said ΔE/ΔV (ii) said ε (v) said D (vi) a reference voltage based on specified voltages for P N in a plurality of previous bursts, wherein said V N 's in said first and second algorithms are functions of at least said ΔE/ΔV, said ε, said D and said at least one reference voltage and said V N 's when calculated one utilized to adjust said charging voltage to control both the individual pulse energy and the integrated energy dose to desired values.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2003-01-24	2003-07-26	2004-01-25	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2007-01-24	2007-07-26	2008-01-25	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2011-01-24	2011-07-26	2012-01-25	$7700.00	Window Closed / Lapsed

Reliable, modular, production quality narrow-band high rep rate F2 laser

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