U.S. patent application number 16/020595 was filed with the patent office on 2019-01-17 for gas laser apparatus.
This patent application is currently assigned to Gigaphoton Inc.. The applicant listed for this patent is Gigaphoton Inc.. Invention is credited to Natsushi SUZUKI, Hiroaki TSUSHIMA, Osamu WAKABAYASHI, Masanori YASHIRO.
Application Number | 20190020167 16/020595 |
Document ID | / |
Family ID | 53179142 |
Filed Date | 2019-01-17 |
View All Diagrams
United States Patent
Application |
20190020167 |
Kind Code |
A1 |
SUZUKI; Natsushi ; et
al. |
January 17, 2019 |
GAS LASER APPARATUS
Abstract
A gas laser apparatus may include: a laser chamber connected
through a first control valve to a first laser gas supply source
that supplies a first laser gas containing a halogen gas and
connected through a second control valve to a second laser gas
supply source that supplies a second laser gas having a lower
halogen gas concentration than the first laser gas; a purification
column that removes at least a part of the halogen gas and a
halogen compound from at least a part of a gas exhausted from the
laser chamber; a booster pump, connected through a third control
valve to the laser chamber, which raises a pressure of a gas having
passed through the purification column to a gas pressure that is
higher than an operating gas pressure of the laser chamber; and a
controller that calculates, on a basis of a first amount of a gas
supplied from the booster pump through the third control valve to
the laser chamber, a second amount of the first laser gas that is
to be supplied to the laser chamber and controls the first control
valve on a basis of a result of the calculation of the second
amount.
Inventors: |
SUZUKI; Natsushi;
(Oyama-shi, JP) ; WAKABAYASHI; Osamu; (Oyama-shi,
JP) ; TSUSHIMA; Hiroaki; (Oyama-shi, JP) ;
YASHIRO; Masanori; (Oyama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Gigaphoton Inc. |
Tochigi |
|
JP |
|
|
Assignee: |
Gigaphoton Inc.
Tochigi
JP
|
Family ID: |
53179142 |
Appl. No.: |
16/020595 |
Filed: |
June 27, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15631676 |
Jun 23, 2017 |
10038295 |
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16020595 |
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15145016 |
May 3, 2016 |
9722384 |
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15631676 |
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PCT/JP2014/081106 |
Nov 25, 2014 |
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15145016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D 53/0446 20130101;
B01D 2251/602 20130101; B01D 53/86 20130101; B01D 2255/20761
20130101; B01D 2255/20753 20130101; B01D 2253/108 20130101; H01S
3/2366 20130101; B01D 53/346 20130101; H01S 3/104 20130101; B01D
53/685 20130101; B01D 53/82 20130101; B01D 2257/2027 20130101; H01S
3/036 20130101; H01S 3/225 20130101; B01D 2259/40003 20130101; B01D
2251/404 20130101; B01D 2258/0216 20130101 |
International
Class: |
H01S 3/036 20060101
H01S003/036; B01D 53/04 20060101 B01D053/04; B01D 53/68 20060101
B01D053/68; B01D 53/86 20060101 B01D053/86; B01D 53/82 20060101
B01D053/82; B01D 53/34 20060101 B01D053/34; H01S 3/225 20060101
H01S003/225; H01S 3/104 20060101 H01S003/104 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 25, 2013 |
JP |
PCT/JP2013/081651 |
Claims
1. A gas laser apparatus comprising: a laser chamber connected
through a first control valve to a first laser gas supply source
that supplies a first laser gas containing a halogen gas and
connected through a second control valve to a second laser gas
supply source that supplies a second laser gas having a lower
halogen gas concentration than the first laser gas; a purification
column that removes at least a part of the halogen gas and a
halogen compound from at least a part of a gas exhausted from the
laser chamber; a booster pump, connected through a third control
valve to the laser chamber, which raises a pressure of a gas having
passed through the purification column to a gas pressure that is
higher than an operating gas pressure of the laser chamber; and a
controller that calculates, on a basis of a first amount of a gas
supplied from the booster pump through the third control valve to
the laser chamber, a second amount of the first laser gas that is
to be supplied to the laser chamber and controls the first control
valve on a basis of a result of the calculation of the second
amount.
2. The gas laser apparatus according to claim 1, further
comprising: a first tank disposed between the purification column
and the booster pump; a first pressure sensor that measures a first
pressure inside the first tank; a second tank disposed between the
booster pump and the third control valve; and a second pressure
sensor that measures a second pressure inside the second tank,
wherein the controller controls the booster pump on a basis of the
first pressure and controls the third control valve on a basis of
the second pressure.
3. The gas laser apparatus according to claim 2, wherein the
controller controls the booster pump so that the first pressure is
equal to or higher than a first predetermined value and equal to or
lower than a second predetermined value and permits the third
control valve to open if the second pressure is equal to or higher
than a third predetermined value.
4. The gas laser apparatus according to claim 1, further
comprising: a fourth control valve disposed between the second
laser gas supply source and the second control valve, wherein the
booster pump is connected through a third control valve to a pipe
between the fourth control valve and the second control valve, and
the controller selectively executes a first control mode in which
the third control valve is closed and the fourth control valve is
opened and a second control mode in which the fourth control valve
is closed and the third control valve is opened.
5. The gas laser apparatus according to claim 4, further
comprising: a first tank disposed between the purification column
and the booster pump; a first pressure sensor that measures a first
pressure inside the first tank; a second tank disposed between the
booster pump and the third control valve; and a second pressure
sensor that measures a second pressure inside the second tank,
wherein the controller controls the booster pump on a basis of the
first pressure and controls the third control valve on a basis of
the second pressure.
6. The gas laser apparatus according to claim 5, wherein the
controller controls the booster pump so that the first pressure is
equal to or higher than a first predetermined value and equal to or
lower than a second predetermined value and permits the third
control valve to open if the second pressure is equal to or higher
than a third predetermined value.
7. The gas laser apparatus according to claim 1, wherein the first
laser gas contains a fluorine gas, an argon gas, a neon gas, and a
xenon gas, and the second laser gas contains an argon gas, a neon
gas, and a xenon gas.
8. The gas laser apparatus according to claim 7, wherein the laser
chamber is connected through a fifth control valve to a third laser
gas supply source that supplies a third laser gas having a higher
xenon gas concentration than the second laser gas.
9. The gas laser apparatus according to claim 8, further comprising
a xenon concentration meter that measures a xenon gas concentration
of the gas having passed through the purification column, wherein
the controller controls the fifth control valve on a basis of the
xenon gas concentration.
10. The gas laser apparatus according to claim 8, further
comprising an operating characteristic measuring instrument that
measures an operating characteristic of laser light that is
outputted from the laser chamber, wherein the controller controls
the fifth control valve on a basis of the operating
characteristic.
11. The gas laser apparatus according to claim 1, further
comprising: a second laser chamber connected through a sixth
control valve to the first laser gas supply source and connected
through a seventh control valve to the second laser gas supply
source; a common pipe connected to the second laser gas supply
source and divided into a first branch pipe in which the second
control valve is disposed and a second branch pipe in which the
seventh control valve is disposed; and a fourth control valve
disposed in the common pipe, wherein the purification column
removes at least a part of the halogen gas and a halogen compound
from at least a part of a gas exhausted from the laser chamber and
at least a part of a gas exhausted from the second laser chamber,
and the booster pump, connected through the third control valve to
the common pipe between the fourth control valve and a place where
the common pipe is divided into the first and second branch pipes,
raises a pressure of a gas having passed through the purification
column to a gas pressure that is higher than an operating gas
pressure of the laser chamber and an operating gas pressure of the
second laser chamber.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Divisional Application of U.S. patent
application Ser. No. 15/631,676, filed Jun. 23, 2017, which is a
Divisional Application of U.S. patent application Ser. No.
15/145,016, filed May 3, 2016, which is a Continuation Application
of International Patent Application No. PCT/JP2014/081106, filed
Nov. 25, 2014, which claims benefit of priority to International
Patent Application No. PCT/JP2013/081651, filed Nov. 25, 2013, the
entire content of which is incorporated herein by reference.
TECHNICAL FIELD
[0002] The present disclosure relates to a gas laser apparatus.
BACKGROUND ART
[0003] In recent years, along with the miniaturization and
integration of semiconductor integrated circuits, a semiconductor
exposure device (hereinafter referred to as "exposure device") has
been required to have higher resolution. For this reason,
shortening of the wavelength of light that is emitted from an
exposure light source has been under development. Generally, as an
exposure light source, a gas laser apparatus is used instead of a
conventional mercury lamp. For example, as a gas laser apparatus
for exposure, a KrF excimer laser apparatus configured to output
ultraviolet laser light with a wavelength of 248 nm as well as an
ArF excimer laser apparatus configured to output ultraviolet laser
light with a wavelength of 193 nm may be used.
[0004] As next-generation exposure technology, immersion exposure
has been put to practical use. In immersion exposure, a gap between
an exposure lens in an exposure device and a wafer is filled with
fluid. Since the refractive index between the exposure lens and the
wafer changes, an apparent wavelength of the exposure light source
is shortened. In a case where immersion exposure is performed using
an ArF excimer laser apparatus as an exposure light source, a wafer
is irradiated with ultraviolet light whose wavelength in water is
134 nm. This technique may be referred to as "ArF immersion
exposure (or ArF immersion lithography)".
[0005] Natural oscillation wavelengths of KrF and ArF excimer laser
apparatuses are as wide as approximately 350 to 400 .mu.m.
Therefore, the constitution of a projector lens by a material that
transmits ultraviolet rays such as KrF or ArF laser light may cause
chromatic aberration, thus lowering resolution. Therefore, a
spectrum line width of laser light that is outputted from a gas
laser apparatus needs to be narrowed to the extent that chromatic
aberration can be ignored. In order to narrow a spectrum line
width, a line narrow module (LNM) having a line narrowing element
(an etalon, a grating, or the like) may be provided in a laser
resonator of a gas laser apparatus. In the following, a laser
apparatus whose spectrum line width is narrowed may be referred to
as a "line narrowed laser apparatus".
CITATION LIST
Patent Document
[0006] Patent Document 1: Japanese Patent No. 4891969
[0007] Patent Document 2: United States Patent Application
Publication No. 2010/0086459
SUMMARY
[0008] A gas laser apparatus according to an aspect of the present
disclosure may include: a laser chamber connected through a first
control valve to a first laser gas supply source that supplies a
first laser gas containing a halogen gas and connected through a
second control valve to a second laser gas supply source that
supplies a second laser gas having a lower halogen gas
concentration than the first laser gas; a purification column that
removes at least a part of the halogen gas and a halogen compound
from at least a part of a gas exhausted from the laser chamber; a
booster pump, connected through a third control valve to the laser
chamber, which raises a pressure of a gas having passed through the
purification column to a gas pressure that is higher than an
operating gas pressure of the laser chamber; and a controller that
calculates, on a basis of a first amount of a gas supplied from the
booster pump through the third control valve to the laser chamber,
a second amount of the first laser gas that is to be supplied to
the laser chamber and controls the first control valve on a basis
of a result of the calculation of the second amount.
[0009] A gas laser apparatus according to another aspect of the
present disclosure may include: a laser chamber connected through a
first control valve to a first laser gas supply source that
supplies a first laser gas containing a halogen gas and connected
through a second control valve to a second laser gas supply source
that supplies a second laser gas having a lower halogen gas
concentration than the first laser gas; a purification column that
removes at least a part of the halogen gas and a halogen compound
from at least a part of a gas exhausted from the laser chamber; a
booster pump, connected through a third control valve to the laser
chamber, which raises a pressure of a gas having passed through the
purification column to a gas pressure that is higher than an
operating gas pressure of the laser chamber; a first tank disposed
between the purification column and the booster pump; a first
pressure sensor that measures a first pressure inside the first
tank; a second tank disposed between the booster pump and the third
control valve; a second pressure sensor that measures a second
pressure inside the second tank; and a controller that controls the
booster pump on a basis of the first pressure and controls the
third control valve on a basis of the second pressure.
[0010] A gas laser apparatus according to another aspect of the
present disclosure may include: a laser chamber connected through a
first control valve to a first laser gas supply source that
supplies a first laser gas containing a halogen gas and connected
through a second control valve to a second laser gas supply source
that supplies a second laser gas having a lower halogen gas
concentration than the first laser gas; a fourth control valve
disposed between the second laser gas supply source and the second
control valve; a purification column that removes at least a part
of the halogen gas and a halogen compound from at least a part of a
gas exhausted from the laser chamber; a booster pump, connected
through a third control valve to a pipe between the fourth control
valve and the second control valve, which raises a pressure of a
gas having passed through the purification column to a gas pressure
that is higher than an operating gas pressure of the laser chamber;
and a controller that selectively executes a first control mode in
which the third control valve is closed and the fourth control
valve is opened and a second control mode in which the fourth
control valve is closed and the third control valve is opened.
[0011] A gas laser apparatus according to still another aspect of
the present disclosure may include: a first laser chamber connected
through a first control valve to a first laser gas supply source
that supplies a first laser gas containing a halogen gas and
connected through a second control valve to a second laser gas
supply source that supplies a second laser gas having a lower
halogen gas concentration than the first laser gas; a second laser
chamber connected through a sixth control valve to the first laser
gas supply source and connected through a seventh control valve to
the second laser gas supply source; a common pipe connected to the
second laser gas supply source and divided into a first branch pipe
in which the second control valve is disposed and a second branch
pipe in which the seventh control valve is disposed; a fourth
control valve disposed in the common pipe; a purification column
that removes at least a part of the halogen gas and a halogen
compound from at least a part of a gas exhausted from the first
laser chamber and at least a part of a gas exhausted from the
second laser chamber; and a booster pump, connected through the
third control valve to the common pipe between the fourth control
valve and a place where the common pipe is divided into the first
and second branch pipes, which raises a pressure of a gas having
passed through the purification column to a gas pressure that is
higher than an operating gas pressure of the first laser chamber
and an operating gas pressure of the second laser chamber.
BRIEF DESCRIPTION OF DRAWINGS
[0012] Exemplary embodiments of the present disclosure will be
described hereinafter with reference to the appended drawings.
[0013] In the drawings, a dashed arrow means at least one of an
input and an output of a signal. In the drawings, a solid arrow
means the movement of matter or the travel of light.
[0014] FIG. 1 is a diagram illustrating an example of a
configuration of an excimer laser apparatus.
[0015] FIG. 2 is a diagram illustrating an example of operation of
a gas control unit of the excimer laser apparatus.
[0016] FIG. 3 is a diagram illustrating an example of a
configuration of a laser apparatus including a gas purification
system according to a first embodiment of the present
disclosure.
[0017] FIG. 4 is a diagram illustrating an example of operation of
a gas purification control unit of the laser apparatus including
the gas purification system according to the first embodiment of
the present disclosure.
[0018] FIG. 5 is a diagram illustrating an example of operation of
a gas control unit of the laser apparatus including the gas
purification system according to the first embodiment of the
present disclosure.
[0019] FIG. 6 is a diagram illustrating an example of a
configuration of a laser apparatus including a gas purification
system according to a second embodiment of the present
disclosure.
[0020] FIG. 7 is a diagram illustrating an example of operation of
a gas purification control unit of the laser apparatus including
the gas purification system according to the second embodiment of
the present disclosure.
[0021] FIG. 8 is a diagram illustrating an example of operation of
a gas control unit of the laser apparatus including the gas
purification system according to the second embodiment of the
present disclosure.
[0022] FIG. 9 is a diagram illustrating an example of a
configuration of a laser apparatus including a gas purification
system according to a third embodiment of the present
disclosure.
[0023] FIG. 10 is a diagram illustrating an example of operation of
a gas purification control unit of the laser apparatus including
the gas purification system according to the third embodiment of
the present disclosure.
[0024] FIG. 11 is a diagram illustrating an example of operation of
a gas control unit of the laser apparatus including the gas
purification system according to the third embodiment of the
present disclosure.
[0025] FIG. 12 is a diagram illustrating an example of a
configuration of a laser apparatus including a gas purification
system according to a fourth embodiment of the present
disclosure.
[0026] FIG. 13 is a diagram illustrating an example of operation of
a gas purification control unit of the laser apparatus including
the gas purification system according to the fourth embodiment of
the present disclosure.
[0027] FIG. 14 is a diagram illustrating an example of a
configuration of a laser apparatus including a gas purification
system according to a fifth embodiment of the present
disclosure.
[0028] FIG. 15 is a diagram illustrating an example of a
configuration of a laser apparatus including a gas purification
system according to a sixth embodiment of the present
disclosure.
[0029] FIG. 16A is a diagram for explaining a principle of
estimation of a xenon concentration on the basis of changes in
energy E of pulse light during burst operation.
[0030] FIG. 16B is a diagram for explaining the principle of
estimation of a xenon concentration on the basis of changes in
energy E of pulse light during burst operation.
[0031] FIG. 16C is a diagram for explaining the principle of
estimation of a xenon concentration on the basis of changes in
energy E of pulse light during burst operation.
[0032] FIG. 16D is a diagram for explaining the principle of
estimation of a xenon concentration on the basis of changes in
energy E of pulse light during burst operation.
[0033] FIG. 17A is a diagram for explaining a principle of
estimation of a xenon concentration on the basis of changes in
charging voltage V due to a charger during burst operation.
[0034] FIG. 17B is a diagram for explaining the principle of
estimation of a xenon concentration on the basis of changes in
charging voltage V due to a charger during burst operation.
[0035] FIG. 17C is a diagram for explaining the principle of
estimation of a xenon concentration on the basis of changes in
charging voltage V due to a charger during burst operation.
[0036] FIG. 17D is a diagram for explaining the principle of
estimation of a xenon concentration on the basis of changes in
charging voltage V due to a charger during burst operation.
[0037] FIG. 18 is a diagram illustrating an example of operation of
a laser control unit of the laser apparatus including the gas
purification system according to the sixth embodiment of the
present disclosure.
[0038] FIG. 19 is a diagram illustrating an example of operation of
a gas control unit of the laser apparatus including the gas
purification system according to the sixth embodiment of the
present disclosure.
[0039] FIG. 20 is a diagram illustrating an example of operation in
which the laser control unit of the laser apparatus including the
gas purification system according to the sixth embodiment of the
present disclosure estimates a xenon concentration Cxe.
[0040] FIG. 21 is a diagram illustrating an example of operation in
which the laser control unit of the laser apparatus including the
gas purification system according to the sixth embodiment of the
present disclosure estimates the xenon concentration Cxe.
[0041] FIG. 22 is a diagram illustrating an example of a controller
according to an embodiment of the present disclosure.
DESCRIPTION OF EMBODIMENTS
[0042] Details [0043] 1. Outline [0044] 2. Excimer Laser Apparatus
[0045] 3. Laser Apparatuses Including Gas Purification Systems
According to Embodiments of Present Disclosure
[0046] 3.1 Laser Apparatus Including Gas Purification System
According to First Embodiment of Present Disclosure
[0047] 3.2 Laser Apparatus Including Gas Purification System
According to Second Embodiment of Present Disclosure
[0048] 3.3 Laser Apparatus Including Gas Purification System
According to Third Embodiment of Present Disclosure
[0049] 3.4 Laser Apparatus Including Gas Purification System
According to Fourth Embodiment of Present Disclosure
[0050] 3.5 Laser Apparatus Including Gas Purification System
According to Fifth Embodiment of Present Disclosure
[0051] 3.6 Laser Apparatus Including Gas Purification System
According to Sixth Embodiment of Present Disclosure [0052] 4.
Controller According to Embodiment of Present Disclosure
[0053] Embodiments of the present disclosure will be described in
detail hereinafter with reference to the drawings. The embodiments
described hereinafter indicate several examples of the present
disclosure, and are not intended to limit the content of the
present disclosure. Furthermore, not all of the configurations and
operations described in the embodiments are required configurations
and operations in the present disclosure. Note that identical
constituent elements will be given identical reference numerals,
and redundant descriptions thereof will be omitted.
[0054] 1. Outline
[0055] An embodiment of the present disclosure may relate to a gas
purification system. An embodiment of the present disclosure may
relate to a laser apparatus. An embodiment of the present
disclosure may relate to a laser apparatus including a gas
purification system.
[0056] A laser apparatus according to an embodiment of the present
disclosure may be a discharge excitation gas laser apparatus. The
discharge excitation gas laser apparatus may be an apparatus
configured for laser oscillation such that a laser gas that is
supplied to a chamber is discharged and excited by applying a
predetermined voltage to a pair of electrodes disposed in the
chamber. The discharge excitation gas laser apparatus may be an
excimer laser apparatus. A laser apparatus according to an
embodiment of the present disclosure may be a laser apparatus for
use in a semiconductor exposure device.
[0057] The discharge excitation gas laser apparatus for use in a
semiconductor exposure device may be an apparatus configured to
output pulse laser light having a desired energy with longer-term
stability. Long-term laser oscillation in the discharge excitation
gas laser apparatus for use in a semiconductor exposure device may
generate impurities in the gas supplied to the chamber of the laser
apparatus. The impurities generated in the gas may absorb pulse
laser light or worsen the condition of discharge of the gas. The
impurities generated in the gas may make it difficult or impossible
to output pulse laser light having the desired energy.
[0058] In order to output pulse laser light having the desired
energy, at least a part of the gas containing the impurities may be
replaced with a new gas containing few impurities. In a case where
at least a part of the gas containing the impurities is replaced
with a new gas containing few impurities, there may be an increase
in the amount of consumption of a gas that is supplied to the
chamber of the laser apparatus.
[0059] A gas laser apparatus according to an embodiment of the
present disclosure may include: a laser chamber connected through a
first control valve to a first laser gas supply source that
supplies a first laser gas containing a halogen gas and connected
through a second control valve to a second laser gas supply source
that supplies a second laser gas having a lower halogen gas
concentration than the first laser gas; a purification column that
removes at least a part of the halogen gas and a halogen compound
from at least a part of a gas exhausted from the laser chamber; a
booster pump, connected through a third control valve to the laser
chamber, which raises a pressure of a gas having passed through the
purification column to a gas pressure that is higher than an
operating gas pressure of the laser chamber; and a controller that
calculates, on a basis of a first amount of a gas supplied from the
booster pump through the third control valve to the laser chamber,
a second amount of the first laser gas that is to be supplied to
the laser chamber and controls the first control valve on a basis
of a result of the calculation of the second amount.
[0060] A gas laser apparatus according to an embodiment of the
present disclosure may include: a laser chamber connected through a
first control valve to a first laser gas supply source that
supplies a first laser gas containing a halogen gas and connected
through a second control valve to a second laser gas supply source
that supplies a second laser gas having a lower halogen gas
concentration than the first laser gas; a fourth control valve
disposed between the second laser gas supply source and the second
control valve; a purification column that removes at least a part
of the halogen gas and a halogen compound from at least a part of a
gas exhausted from the laser chamber; a booster pump, connected
through a third control valve to a pipe between the fourth control
valve and the second control valve, which raises a pressure of a
gas having passed through the purification column to a gas pressure
that is higher than an operating gas pressure of the laser chamber;
and a controller that selectively executes a first control mode in
which the third control valve is closed and the fourth control
valve is opened and a second control mode in which the fourth
control valve is closed and the third control valve is opened.
[0061] A gas laser apparatus according to an embodiment of the
present disclosure may include: a first laser chamber connected
through a first control valve to a first laser gas supply source
that supplies a first laser gas containing a halogen gas and
connected through a second control valve to a second laser gas
supply source that supplies a second laser gas having a lower
halogen gas concentration than the first laser gas; a second laser
chamber connected through a sixth control valve to the first laser
gas supply source and connected through a seventh control valve to
the second laser gas supply source; a common pipe connected to the
second laser gas supply source and divided into a first branch pipe
in which the second control valve is disposed and a second branch
pipe in which the seventh control valve is disposed; a fourth
control valve disposed in the common pipe; a purification column
that removes at least a part of the halogen gas and a halogen
compound from at least a part of a gas exhausted from the first
laser chamber and at least a part of a gas exhausted from the
second laser chamber; and a booster pump, connected through the
third control valve to the common pipe between the fourth control
valve and a place where the common pipe is divided into the first
and second branch pipes, which raises a pressure of a gas having
passed through the purification column to a gas pressure that is
higher than an operating gas pressure of the first laser chamber
and an operating gas pressure of the second laser chamber.
[0062] An embodiment of the present disclosure makes it possible to
provide a gas purification system or a laser apparatus capable of
replacing at least a part of a gas containing impurities with a
purified gas. An embodiment of the present disclosure makes it
possible to provide a gas purification system or a laser apparatus
capable of reducing an amount of consumption of a gas.
[0063] 2. Excimer Laser Apparatus
[0064] FIG. 1 is a diagram illustrating an example of a
configuration of an excimer laser apparatus.
[0065] An excimer laser apparatus 1000 is a discharge excitation
gas laser apparatus. The excimer laser apparatus 1000 may be used
together with an exposure device 2000. Laser light emitted from the
excimer laser apparatus 1000 may enter the exposure device 2000.
The exposure device 2000 may include an exposure device controller
2100. The exposure device controller 2100 may be configured to
control the semiconductor exposure device 2000. The exposure device
controller 2100 may be configured to send a signal to a laser
control unit 100 of the laser apparatus 1000.
[0066] The excimer laser apparatus 1000 may include the laser
control unit 100, a laser oscillation system 200, and a gas control
system 300. The laser control unit 100 may be configured to control
the laser oscillation system 200 and the gas control system 300.
The laser control unit 100 may be configured to receive signals
from a power monitor 220 and chamber pressure sensor 215 of the
laser oscillation system 200 and send signals to a charger 230 and
a switch 214 of a pulse power module (PPM) 213. The laser control
unit 100 may be configured to receive an emission trigger Tr from
the exposure device controller 2100.
[0067] The laser oscillation system 200 may include a chamber 210,
a laser resonator, a power monitor 220, and the charger 230.
[0068] The chamber 210 may be configured to generate light by
discharging and exciting a gas supplied to the chamber 210 and
emitting the light thus generated. The chamber 210 may be disposed
on an optical path of the laser resonator. The chamber 210 may
include a pair of discharge electrodes 211a and 211b, two windows
212a and 212b, the pulse power module 213, and the chamber pressure
sensor 215. The pair of discharge electrodes 211a and 211b may be
configured to apply a voltage to a gas supplied into the chamber
210. The two windows 212a and 212b may be configured to cause the
light generated in the chamber 210 to be transmitted out of the
chamber 210. The pulse power module 213 may be configured to apply
a pulse voltage between the pair of discharge electrodes 211a and
211b. The pulse power module 213 may include the switch 214. The
pulse power module 213 may be configured to apply a pulse voltage
between the pair of discharge electrodes 211a and 211b by switching
on and off the switch 214. The switch 214 may receive an emission
trigger Tr from the laser control unit 100. The chamber pressure
sensor 215 may be configured to measure a pressure (total pressure)
of the gas supplied into the chamber 210. The chamber pressure
sensor 215 may be configured to send a signal representing the
pressure thus measured to the laser control unit 100 and a gas
control unit 310 of the gas control system 300.
[0069] The laser resonator may be configured to obtain laser light
from the light generated and emitted from the chamber 210. The
laser resonator may include an output coupling (OC) mirror 240 and
a line narrow module (LNM) 250. The output coupling mirror 240 may
be a partial reflection mirror configured to transmit a part of the
light emitted from the chamber 210 and reflect a part of the light
emitted from the chamber 210. The line narrow module 250 may be
configured to narrow the range of wavelengths of the light emitted
from the chamber 210. The line narrow module 250 may include a
prism 251 and a grating 252. The prism 251 may be configured to
enlarge the beam diameter of the light emitted from the chamber
210. The prism 251 may be configured to change the angle of
incidence of the light entering the grating 252. The grating 252
may be configured to diffract the light emitted from the chamber
210 and select a wavelength of the light emitted from the chamber
210. Mounting of the grating 252 may be Littrow mounting, in which
the angle of incidence of the light entering the grating 252 and
the angle of diffraction of the light diffracted by the grating 252
are completely or substantially equal.
[0070] The power monitor 220 may be configured to detect pulse
energy of laser light outputted from the output coupling mirror
240. The power monitor 220 may include a beam splitter 221, a
collector lens 222, and an optical sensor 223. The beam splitter
221 of the power monitor 220 may be disposed on the optical path of
light from the laser resonator. The beam splitter 221 may be
configured to transmit a part of the laser light outputted from the
output coupling mirror 240 and reflect a part of the laser light
outputted from the output coupling mirror 240. The collector lens
222 and optical sensor 223 of the power monitor 220 may be disposed
on an optical path of the laser light reflected by the beam
splitter 221. The collector lens 222 may be configured to focus the
laser light reflected by the beam splitter 221 onto the optical
sensor 223. The optical sensor 223 may be configured to convert
pulse energy of the laser light focused by the collector lens 222
into an electrical signal and send the electrical signal to the
laser control unit 100.
[0071] The charger 230 may be configured to charge the pulse power
module 213. The charger 230 may receive a signal from the laser
control unit 100 and be controlled by the laser control unit
100.
[0072] The gas control system 300 may include the gas control unit
310, a gas supply device 320, and an exhaust device 330. The gas
control unit 310 may be controlled by the laser control unit 100.
The gas control unit 310 may be configured to send a signal to the
laser control unit 100. The gas control unit 310 may receive a
signal from the chamber pressure sensor 215 of the laser
oscillation system 200. The gas control unit 310 may be configured
to control the gas supply device 320 and the exhaust device 330.
The gas control unit 310 may be configured to control valves F2-V1
and B-V1 of the gas supply device 320 and a valve Ex-V and an
exhaust pump 332 of the exhaust device 330.
[0073] The gas supply device 320 may include a pipe connected to a
fluorine-containing gas supply source 3100 and to the chamber 210
of the laser oscillation system 200. The gas supply device 320 may
include the valve F2-V1 provided in the pipe connected to the
fluorine-containing gas supply source 3100 and to the chamber 210
of the laser oscillation system 200. The supply of a
fluorine-containing gas from the fluorine-containing gas supply
source 3100 to the chamber 210 of the laser oscillation system 200
may be controlled by the valve F2-V1. The valve F2-V1 may be
controlled by the gas control unit 310.
[0074] The gas supply device 320 may include a pipe connected to a
buffer gas supply source 3200 and to the chamber 210 of the laser
oscillation system 200. The gas supply device 320 may include the
valve B-V1 provided in the pipe connected to the buffer gas supply
source 3200 and to the chamber 210 of the laser oscillation system
200. The supply of a buffer gas from the buffer gas supply source
3200 to the chamber 210 of the laser oscillation system 200 may be
controlled by the valve B-V1. The valve B-V1 may be controlled by
the gas control unit 310.
[0075] The exhaust device 330 may include a pipe connected to the
chamber 210 of the laser oscillator system 200 and to the outside.
The exhaust device 330 may include the valve Ex-V provided in the
pipe connected to the chamber 210 of the laser oscillator system
200 and to the outside. The exhaust of a gas from the chamber 210
of the laser oscillator system 200 to the outside may be controlled
by the valve Ex-V. The valve Ex-V may be controlled by the gas
control unit 310. The exhaust device 330 may include a fluorine
trap 331 and the exhaust pump 332. The fluorine trap 331 and the
exhaust pump 332 may be provided in the pipe connected to the
chamber 210 of the laser oscillator system 200 and to the outside.
The fluorine trap 331 may be configured to trap fluorine contained
in a gas to be exhausted from the chamber 210 of the laser
oscillator system 200 to the outside. The exhaust pump 332 may be
configured to exhaust the gas from the chamber 210 of the laser
oscillator system 200 to the outside. Operation of the exhaust pump
332 may be controlled by the gas control unit 310.
[0076] The fluorine-containing gas supply source 3100 may be a gas
cylinder including a regulator configured to supply a
fluorine-containing gas containing a fluorine gas that is a halogen
gas. The fluorine-containing gas may be a mixed gas of fluorine and
rare gasses, such as a mixed gas of fluorine, argon, and neon or a
mixed gas of fluorine, krypton, and neon.
[0077] The buffer gas supply source 3200 may be a gas cylinder
including a regulator configured to supply a buffer gas (a
fluorine-free gas). The buffer gas may be a mixed gas of rare
gasses, such as a mixed gas of argon and neon or a mixed gas of
krypton and neon.
[0078] The following describes a method for controlling energy of
laser light in the excimer laser apparatus 1000.
[0079] First, upon receiving a target pulse energy Et from the
exposure device controller 2100, the laser control unit 100 may
send, to the charger 230, a signal representing a predetermined
charging voltage Vhv for achieving the target pulse energy Et.
[0080] Next, upon receiving an emission trigger Tr from the
exposure device controller 2100, the laser control unit 100 may
apply a voltage between the pair of discharge electrodes 211a and
211b by switching on the switch 214 of the pulse power module 213.
Light may be generated in the chamber 210 by discharging and
exciting a gas supplied between the pair of discharge electrodes
211a and 211b. The light generated in the chamber 210 may be
outputted as laser light by the laser resonator. The laser light
outputted from the laser resonator may be narrowed by the grating
252 of the laser resonator. The laser light thus narrowed may be
outputted from the output coupling mirror 240. The laser light
outputted from the output coupling mirror 240 may enter the power
monitor 220. Pulse energy Er of the laser light may be measured by
the power monitor 220. The pulse energy Er measured by the power
monitor 220 may be sent to the laser control unit 100. A part of
the laser light outputted from the output coupling mirror 240 may
enter the exposure device 2000.
[0081] Next, on the basis of a difference .DELTA.E between the
target pulse energy Et and the pulse energy Er thus measured, the
laser control unit 100 may perform feedback control of the charging
voltage Vhv to be sent to the charger 230.
[0082] In this manner, the charging voltage Vhv to be sent to the
charger 230 may be controlled so that the pulse energy Er thus
measured may become equal to the target pulse energy Et. The laser
apparatus 1000 may output, in synchronization with an emission
trigger Tr, pulse laser light having a predetermined pulse
energy.
[0083] The following describes an operation of complete gas
replacement in the excimer laser apparatus 1000.
[0084] First, the laser control unit 100 may send, to the gas
control unit 310 of the gas control system 300, a signal for
starting complete gas replacement.
[0085] Next, the gas control unit 310 may bring the exhaust pump
332 of the exhaust device 330 into operation.
[0086] Next, the gas control unit 310 may open the valve Ex-V to
exhaust the gas in the chamber 210 until a pressure P1 measured by
the chamber pressure sensor 215 becomes a pressure that is close to
a vacuum.
[0087] Next, the gas control unit 310 may close the valve Ex-V and
stop the exhaust pump 332.
[0088] Next, the gas control unit 310 may control the opening and
closing of the valves F2-V1 and B-V1 so that the pressure P1
measured by the chamber pressure sensor 215 may become equal to a
predetermined pressure and the composition of a gas that is
supplied to the chamber 210 becomes a predetermined
composition.
[0089] In this manner, complete gas replacement in the excimer
laser apparatus 1000 may be performed.
[0090] The following describes an operation of partial gas
replacement in the excimer laser apparatus 1000.
[0091] Continuation of laser oscillation in the excimer laser
apparatus 1000 may generate impurities, i.e., fluorine compounds,
in the gas contained in the chamber 210. Examples of the
impurities, i.e., fluorine compounds, may include hydrogen fluoride
(HF), carbon tetrafluoride (CF.sub.4), silicon tetrafluoride
(SiF.sub.4), nitrogen trifluoride (NF.sub.3), hexafluoroethane
(C.sub.2F.sub.6), and the like. The impurities generated in the gas
contained in the chamber 210 may absorb pulse laser light or worsen
the condition of discharge of the gas. The impurities generated in
the gas contained in the chamber 210 may drop the energy of the
pulse laser light or degrade the stability of the energy of the
pulse laser light. In order to suppress an increase in
concentration of the impurities in the gas contained in the chamber
210, it is possible to supply the chamber 210 with a predetermined
amount of a new gas containing few impurities and exhaust the gas
in the chamber 210 by the same amount as the amount of the new gas.
In this manner, partial gas replacement in the excimer laser
apparatus 1000 may be performed.
[0092] FIG. 2 is a diagram illustrating an example of operation of
the gas control unit of the excimer laser apparatus.
[0093] In step S101, the gas control unit 310 may make preparations
for partial gas replacement. In preparation for partial gas
replacement, the valve F2-V1 and valve B-V1 of the gas supply
device 320 and the valve Ex-V of the exhaust device 330 may all be
closed. In preparation for partial gas replacement, the exhaust
pump 332 of the exhaust device 330 may be brought into
operation.
[0094] In step S102, the gas control unit 310 may determine whether
it has received, from the laser control unit 100, a signal for
starting partial gas replacement. The laser control unit 100 may
send the signal for starting partial gas replacement to the gas
control unit 310 in accordance with a predetermined number of shots
of laser oscillation, predetermined time intervals, or the like. In
a case where the gas control unit 310 has received, from the laser
control unit 100, the signal for starting partial gas replacement,
the gas control unit 310 may proceed to step S103. In a case where
the gas control unit 310 has not received, from the laser control
unit 100, the signal for starting partial gas replacement, the gas
control unit 310 may repeat step S102.
[0095] In step S103, the gas control unit 310 may receive an
initial pressure P10 of the gas in the chamber 210 (i.e., a
pressure of the gas in the chamber 210 before partial gas
replacement) from the chamber pressure sensor 215.
[0096] In step S104, the gas control unit 310 may calculate a
target value P1b of the pressure of the gas in the chamber 210
after supplying the buffer gas to the chamber 210.
[0097] In step S105, the gas control unit 310 may receive the
pressure P1 of the gas in the chamber 210 from the chamber pressure
sensor 215 and may control the valve B-V1 so that the pressure P1
may become closer to the target value P1b. In this manner, the
buffer gas may be supplied to the chamber 210.
[0098] In step S106, the gas control unit 310 may calculate a
target value .DELTA.P1F2 of a rise in pressure in the chamber 210
due to supplying the fluorine-containing gas to the chamber 210.
The gas control unit 310 may calculate the target value .DELTA.P1F2
of the rise in pressure so that the concentration of a fluorine gas
in the gas in the chamber 210 may become equal to a predetermined
concentration CF2. For example, in a case where the
fluorine-containing gas is a fluorine gas, the target value
.DELTA.P1F2 of the rise in pressure may be calculated according to
the formulae .DELTA.P1b=P1b-P10 and
.DELTA.P1F2=CF2.times..DELTA.P1b/(1-CF2). In a case where the
fluorine-containing gas is a mixed gas, the calculation may be
performed further in consideration of the mixing ratio of
fluorine.
[0099] In step S107, the gas control unit 310 may calculate a
target value P1F2 of the pressure of the gas in the chamber 210
after supplying the fluorine-containing gas to the chamber 210. The
target value P1F2 of the pressure may be calculated according to
the formula P1F2=P1b+.DELTA.P1F2.
[0100] In step S108, the gas control unit 310 may receive the
pressure P1 of the gas in the chamber 210 from the chamber pressure
sensor 215 and may control the valve F2-V1 so that the pressure P1
may become closer to the target value P1F2. In this manner, the
fluorine-containing gas may be supplied to the chamber 210.
[0101] In step S109, the gas control unit 310 may receive the
pressure P1 of the gas in the chamber 210 from the chamber pressure
sensor 215 and may control the valve Ex-V so that the pressure P1
may become closer to the initial pressure P10. In this manner, a
part of the gas in the chamber 210 may be exhausted to the
outside.
[0102] In step S110, the gas control unit 310 may determine whether
it has received, from the laser control unit 100, a signal for
stopping partial gas replacement. The laser control unit 100 may
send the signal for stopping partial gas replacement to the gas
control unit 310 in accordance with the pressure P1 measured by the
chamber pressure sensor 215 or the like. In a case where the gas
control unit 310 has received, from the laser control unit 100, the
signal for stopping partial gas replacement, the gas control unit
310 may terminate the operation for partial gas replacement. In a
case where the gas control unit 310 has not received, from the
laser control unit 100, the signal for stopping partial gas
replacement, the gas control unit 310 may return to step S102.
[0103] An amount Q of a gas that is replaced by a single round of
partial gas replacement may be calculated according to the formula
Q=(.DELTA.P1b+.DELTA.P1F2).times.V/P, where V is the volume of the
chamber 210 and P is 1 atm (1013 hPa).
[0104] In this manner, an increase in the concentration of
impurities that may be generated in the gas in the chamber 210 may
be suppressed by replacing the predetermined amount Q of the gas in
the chamber 210 with the predetermined number of shots of laser
oscillation or at the predetermined time intervals.
[0105] In a case where a new gas containing few impurities is
supplied to the chamber 210 and the gas in the chamber 210 is
exhausted by the same amount as the amount of the new gas in order
to suppress an increase in the concentration of impurities in the
gas in the chamber 210, the amount of consumption of gas may
increase.
[0106] 3. Laser Apparatuses Including Gas Purification Systems
According to Embodiments of Present Disclosure
[0107] 3.1 Laser Apparatus Including Gas Purification System
According to First Embodiment of Present Disclosure
[0108] FIG. 3 is a diagram illustrating an example of a
configuration of a laser apparatus including a gas purification
system according to a first embodiment of the present disclosure.
The laser apparatus shown in FIG. 3 may include the same
configuration as the laser apparatus illustrated in FIG. 1.
Components of the laser apparatus illustrated in FIG. 3 which are
identical to those of the laser apparatus illustrated in FIG. 1 are
given the same reference signs, and as such, are omitted from the
description below.
[0109] The excimer laser apparatus 1000 according to the first
embodiment of the present disclosure may further include a gas
purification system 400.
[0110] The gas purification system 400 may include a gas
purification device 410 and a gas purification control unit 420.
The gas purification control unit 420 may be configured to receive
a signal from the gas control unit 310 of the gas control system
300 and send a signal to the gas control unit 310. The gas
purification control unit 420 may be configured to control the gas
purification device 410.
[0111] The gas purification device 410 may include a purification
column 411, a filter 412, a circulation pump 413, a mass flow
controller (MFC) 414, a valve C-V1, a valve C-V2, and a valve C-V3.
The gas purification device 410 may include a circulation gas pipe
connecting the valve C-V1, the purification column 411, the filter
412, the circulation pump 413, the mass flow controller 414, and
the valve C-V3. The gas purification device 410 may include a
bypass pipe connecting a pipe between the valve C-V1 and the
purification column 411 and a pipe between the circulation pump 413
and the mass flow controller 414. The bypass pipe may be provided
with the valve C-V2.
[0112] One end of the circulation gas pipe may be connected to a
pipe connected to both the chamber 210 of the laser oscillation
system 200 and the exhaust device 330 of the gas control system
300. The other end of the circulation gas pipe may be connected to
a pipe connected to both the chamber 210 of the laser oscillation
system 200 and the gas supply device 320 of the gas control system
300.
[0113] The purification column 411, the circulation pump 413, the
mass flow controller 414, the valve C-V1, the valve C-V2, and the
valve C-V3 may be configured to receive signals from the gas
purification control unit 420. The purification column 411, the
circulation pump 413, the mass flow controller 414, the valve C-V1,
the valve C-V2, and the valve C-V3 may be configured to be
controlled by the gas purification control unit 420.
[0114] The purification column 411 may include a first treatment
tower (not illustrated) and a second treatment tower (not
illustrated). The first treatment tower may be filled with a
treating agent for treating a fluorine gas and impurities, i.e.,
fluorine compounds. The treating agent for treating the fluorine
gas and the impurities, i.e., the fluorine compounds, may be a
treating agent containing at least one of zeolite and calcium
oxide. The second treatment tower may be filled with a treating
agent for treating at least one of moisture and oxygen generated by
the treatment of the fluorine gas and the impurities, i.e., the
fluorine compounds, by the treating agent filled in the first
treatment tower. The treating agent for treating at least one of
moisture and oxygen may be a treating agent containing at least one
of a nickel (Ni) catalyst, a copper (Cu) catalyst, and a compound
thereof. The purification column 411 may include a heating device
(and a temperature regulating device) (not illustrated) for causing
the first treatment tower and the second treatment tower to operate
at a temperature that is higher than room temperature.
[0115] The filter 412 may be a filter for trapping particles
generated by the discharge of a gas supplied between the pair of
discharge electrodes 211a and 211b in the chamber 210. The filter
412 may be a filter made of a material that hardly reacts with
fluorine. The material that hardly reacts with fluorine may be a
metal or ceramic material.
[0116] The circulation pump 413 may be a pump configured to cause a
gas to flow through the circulation gas pipe.
[0117] The mass flow controller 414 may be a valve configured to
control the mass flow of the gas flowing through the circulation
gas pipe.
[0118] The following describes an operation of complete gas
replacement in the excimer laser apparatus 1000 according to the
first embodiment of the present disclosure.
[0119] First, the laser control unit 100 may send a signal for
starting complete gas replacement to the gas control unit 310 of
the gas control system 300.
[0120] Next, the gas control unit 310 may bring the exhaust pump
332 of the exhaust device 330 into operation.
[0121] Next, the gas control unit 310 and the gas purification
control unit 420 may open the valve Ex-V, the valve CV-1, the valve
C-V2, and the valve C-V3 to exhaust the gas in the chamber 210 and
the gas in the pipe of the gas purification device 410. The gas
control unit 310 and the gas purification control unit 420 may
exhaust the gas in the chamber 210 and the gas in the pipe of the
gas purification device 410 until the pressure P1 measured by the
chamber pressure sensor 215 becomes a pressure that is close to a
vacuum.
[0122] Next, the gas control unit 310 may close the valve Ex-V and
stop the exhaust pump 332.
[0123] Next, the gas control unit 310 may control the opening and
closing of the valves F2-V1 and B-V1 so that the pressure P1
measured by the chamber pressure sensor 215 may become equal to a
predetermined pressure and the composition of a gas that is
supplied to the chamber 210 may become a predetermined
composition.
[0124] Next, the gas purification control unit 420 may close the
valve C-V1, the valve C-V2, and the valve C-V3.
[0125] In this manner, the chamber 210 and the gas purification
device 420 may be filled with a gas. In this manner, complete gas
replacement in the excimer laser apparatus 1000 may be
performed.
[0126] Furthermore, the gas purification control unit 420 may heat
the purification column 411 (and control the temperature of the
purification column 411).
[0127] FIG. 4 is a diagram illustrating an example of operation of
the gas purification control unit of the laser apparatus including
the gas purification system according to the first embodiment of
the present disclosure.
[0128] In step S201, the gas purification control unit 420 may make
preparations for gas purification. In preparation for gas
purification, the circulation gas pipe and bypass pipe of the gas
purification control unit 410 may be filled with a gas. In
preparation for gas purification, the purification column 411 may
be heated. In preparation for gas purification, the valve C-V1, the
valve C-V2, and the valve C-V3 may be closed.
[0129] In step S202, the gas purification control unit 420 may
determine whether it has received, from the laser control unit 100
through the gas control unit 310, a signal for starting gas
purification. The laser control unit 100 may send the signal for
starting gas purification to the gas purification control unit 420
through the gas control unit 310 in accordance with the
predetermined number of shots of laser oscillation, the
predetermined time intervals, and the like. In a case where the gas
purification control unit 420 has received, from the laser control
unit 100 through the gas control unit 310, the signal for starting
gas purification, the gas purification control unit 420 may proceed
to step S203. In a case where the gas purification control unit 420
has not received, from the laser control unit 100 through the gas
control unit 310, the signal for starting gas purification, the gas
purification control unit 420 may repeat step S202.
[0130] In step S203, the gas purification control unit 420 may
bring the circulation pump 413 of the gas purification device 410
into operation.
[0131] In step S204, the gas purification control unit 420 may set
a flow rate L of a gas that is controlled by the mass flow
controller 414 of the gas purification device 410. The setting of
the flow rate L of the gas that is controlled by the mass flow
controller 414 of the gas purification device 410 may be carried
out by sending the flow rate L from the gas purification control
unit 420 to the mass flow controller 414.
[0132] In step S205, the gas purification control unit 420 may open
the valve C-V1 of the gas purification device 410.
[0133] In step S206, the gas purification control unit 420 may wait
for a predetermined period of time T1. By the gas purification
control unit 420 waiting for the predetermined period of time T1,
the pressure of the gas in the circulation gas pipe of the gas
purification device 410 may be made substantially equal to the
pressure of the gas in the chamber 210.
[0134] In step S207, the gas purification control unit 420 may open
the valve C-V2 of the gas purification device 410 and close the
valve C-V1.
[0135] In step S208, the gas purification control unit 420 may wait
for a predetermined period of time T2. By the gas purification
control unit 420 waiting for the predetermined period of time T2,
the gas contained in the gas purification device 410 may be
circulated through the circulation gas pipe and the bypass pipe and
more effectively purified by the purification column 411 and the
filter 412.
[0136] In step S209, the gas purification control unit 420 may
close the valve C-V2 of the gas purification device 410 and open
the valve C-V1 and valve C-V3 of the gas purification device
410.
[0137] In step S210, the gas purification control unit 420 may wait
for a predetermined period of time T3. While the gas purification
control unit 420 is waiting for the predetermined period of time
T3, the circulation pump 413 and the mass flow controller 414 may
supply the gas purified by the purification column 411 and the
filter 412 to the chamber 210 at the flow rate L through the
circulation gas pipe.
[0138] In step S211, the gas purification control unit 420 may
close the valve C-V1 and valve C-V3 of the gas purification device
410.
[0139] In step S212, the gas purification control unit 420 may
calculate an amount Qb of the purified gas supplied to the chamber
210. The amount Qb of the purified gas supplied to the chamber 210
may be calculated according to the formula Qb=L.times.T3. The gas
purification control unit 420 may send, to the laser control unit
100 through the gas control unit 310, the amount Qb of the purified
gas supplied to the chamber 210.
[0140] In step S213, the gas purification control unit 420 may
determine whether it has received, from the laser control unit 100
through the gas control unit 310, a signal for stopping gas
purification. The laser control unit 100 may send the signal for
stopping gas purification to the gas purification control unit 420
through the gas control unit 310 in accordance with the pressure P1
measured by the chamber pressure sensor 215 and the like. In a case
where the gas purification control unit 420 has received, from the
laser control unit 100 through the gas control unit 310, the signal
for stopping gas purification, the gas purification control unit
420 may stop the circulation pump 413 of the gas purification
device 410 in step S214. Then, the operation of gas purification
may be terminated. In a case where the gas purification control
unit 420 has not received, from the laser control unit 100 through
the gas control unit 310, the signal for stopping gas purification,
the gas purification control unit 420 may return to step S205.
[0141] FIG. 5 is a diagram illustrating an example of operation of
the gas control unit of the laser apparatus including the gas
purification system according to the first embodiment of the
present disclosure.
[0142] In step S301, the gas control unit 310 may make preparations
for partial gas replacement. In preparation for partial gas
replacement, the valve F2-V1 and valve B-V1 of the gas supply
device 320 and the valve Ex-V of the exhaust device 330 may all be
closed. In preparation for partial gas replacement, the exhaust
pump 332 of the exhaust device 330 may be brought into
operation.
[0143] In step 302, the gas control unit 310 may determine whether
it has received, from the laser control unit 100, data representing
the amount Qb of the purified gas supplied to the chamber 210. The
laser control unit 100 may send, to the gas control unit 310, the
amount Qb of the purified gas supplied to the chamber 210 thus
received from the gas purification control unit 420. In a case
where the gas control unit 310 has received, from the laser control
unit 100, data representing the amount Qb of the purified gas
supplied to the chamber 210, the gas control unit 310 may proceed
to step S303. In a case where the gas control unit 310 has not
received, from the laser control unit 100, data representing the
amount Qb of the purified gas supplied to the chamber 210, the gas
control unit 310 may repeat step S302.
[0144] In step S303, the gas control unit 310 may read out the
amount Qb, received from the laser control unit 100, of the
purified gas supplied to the chamber 210. In a case where the
purified gas supplied to the chamber 210 completely or
substantially does not contain a fluorine gas, the concentration of
fluorine in the gas in the chamber 210 may be reduced. In order to
suppress a reduction in the concentration of fluorine in the gas in
the chamber 210, fluorine-containing gas may be supplied
(replenished) from the fluorine-containing gas supply source 3100
into the chamber 210, depending on the amount Qb of the purified
gas supplied to the chamber 210.
[0145] In step S304, the gas control unit 310 may receive an
initial pressure P10 of the gas in the chamber 210 (i.e., a
pressure of the gas in the chamber 210 before partial gas
replacement) from the chamber pressure sensor 215.
[0146] In step S305, the gas control unit 310 may calculate a
target value .DELTA.P1F2 of a rise in pressure in the chamber 210
due to supplying the fluorine-containing gas to the chamber 210.
The gas control unit 310 may calculate the target value .DELTA.P1F2
of the rise in pressure so that the concentration of a fluorine gas
in the gas in the chamber 210 may become equal to a predetermined
concentration CF2. For example, in a case where the
fluorine-containing gas is a fluorine gas, the target value
.DELTA.P1F2 of the rise in pressure may be calculated according to
the formula .DELTA.P1F2=CF2.times.(Qb/V)/(1-CF2), where V is the
volume of the chamber 210. In a case where the fluorine-containing
gas is a mixed gas, the calculation may be performed further in
consideration of a mixing ratio of fluorine.
[0147] In step S306, the gas control unit 310 may calculate a
target value P1F2 of the pressure of the gas in the chamber 210
after supplying the fluorine-containing gas to the chamber 210. The
target value P1F2 of the pressure may be calculated according to
the formula P1F2=P10+Qb/V+.DELTA.P1F2.
[0148] In step S307, the gas control unit 310 may receive the
pressure P1 of the gas in the chamber 210 from the chamber pressure
sensor 215 and may control the valve F2-V1 so that the pressure P1
may become closer to the target value P1F2. In this manner, the
fluorine-containing gas may be supplied to the chamber 210.
[0149] In step S308, the gas control unit 310 may receive the
pressure P1 of the gas in the chamber 210 from the chamber pressure
sensor 215 and may control the valve Ex-V so that the pressure P1
may become closer to the initial pressure P10. In this manner, a
part of the gas in the chamber 210 may be exhausted to the
outside.
[0150] In step S309, the gas control unit 310 may determine whether
it has received, from the laser control unit 100, a signal for
stopping partial gas replacement. The laser control unit 100 may
send the signal for stopping partial gas replacement to the gas
control unit 310 based on the pressure P1 measured by the chamber
pressure sensor 215 and the like. In a case where the gas control
unit 310 has received, from the laser control unit 100, the signal
for stopping partial gas replacement, the gas control unit 310 may
terminate the operation for partial gas replacement. In a case
where the gas control unit 310 has not received, from the laser
control unit 100, the signal for stopping partial gas replacement,
the gas control unit 310 may return to step S302.
[0151] In the excimer laser apparatus 1000 according to the first
embodiment of the present disclosure, the mass flow controller 414
is used to obtain the amount of the purified gas that is supplied
to the chamber 210. Alternatively, a flowmeter may be provided
instead of the mass flow controller 414.
[0152] In this manner, the laser apparatus 1000 according to the
first embodiment of the present disclosure makes it possible to
purify a part of the gas in the chamber 210 and supply the purified
gas to the chamber 210. In this manner, the laser apparatus 1000
according to the first embodiment of the present disclosure makes
it possible to reduce the amount of a gas that is sent from the
buffer gas supply source 3200 to the chamber 210.
[0153] 3.2 Laser Apparatus Including Gas Purification System
According to Second Embodiment of Present Disclosure
[0154] FIG. 6 is a diagram illustrating an example of a
configuration of a laser apparatus including a gas purification
system according to a second embodiment of the present disclosure.
The laser apparatus shown in FIG. 6 may include the same
configuration as the laser apparatus illustrated in FIG. 1.
Components of the laser apparatus illustrated in FIG. 6 which are
identical to those of the laser apparatus illustrated in FIG. 1 are
given the same reference signs, and as such, are omitted from the
description below. The excimer laser apparatus 1000 according to
the second embodiment of the present disclosure may further include
a gas purification system 500.
[0155] The gas purification system 500 may include a gas
purification device 510 and a gas purification control unit 520.
The gas purification control unit 520 may be configured to receive
a signal from the gas control unit 310 of the gas control system
300 and send a signal to the gas control unit 310. The gas
purification control unit 520 may be configured to receive a signal
from the gas purification device 510 and send a signal to the gas
purification device 510.
[0156] The gas purification device 510 may include a purification
column 511, a first filter 512, a first tank 513, a first pressure
sensor 514, a booster pump 515, a second filter 516, a second tank
517, a second pressure sensor 518, a purifier 519, a valve C-V1,
and a valve C-V3. The gas purification device 510 may include a
circulation gas pipe connecting the valve C-V1, the purification
column 511, the first filter 512, the first tank 513, the booster
pump 515, the second filter 516, the second tank 517, the purifier
519, and the valve C-V3.
[0157] One end of the circulation gas pipe may be connected to a
pipe connected to both the chamber 210 of the laser oscillation
system 200 and the exhaust device 330 of the gas control system
300. The other end of the circulation gas pipe may be connected to
a pipe connected to both the chamber 210 of the laser oscillation
system 200 and the gas supply device 320 of the gas control system
300.
[0158] The purification column 511 and the booster pump 515 may be
configured to receive a signal from the gas purification control
unit 520. The purification column 511 and the booster pump 515 may
be configured to be controlled by the gas purification control unit
520.
[0159] The first pressure sensor 514 and the second pressure sensor
518 may be configured to send signals representing measured
pressures to the gas purification control unit 520.
[0160] The valve C-V1 and the valve C-V3 may be configured to
receive signals from the gas control unit 310 of the gas control
system 300. The valve C-V1 and the valve C-V3 may be configured to
be controlled by the gas control unit 310 of the gas control system
300.
[0161] The purification column 511 may include a first treatment
tower (not illustrated) and a second treatment tower (not
illustrated). The first treatment tower may be filled with a
treating agent for treating a fluorine gas and impurities, i.e.,
fluorine compounds. The treating agent for treating the fluorine
gas and the impurities, i.e., the fluorine compounds, may be a
treating agent containing at least one of zeolite and calcium
oxide. The second treatment tower may be filled with a treating
agent for treating at least one of moisture and oxygen generated by
the treatment of the fluorine gas and the impurities, i.e., the
fluorine compounds, by the treating agent filling the first
treatment tower. The treating agent for treating at least one of
moisture and oxygen may be a treating agent containing at least one
of a nickel (Ni) catalyst, a copper (Cu) catalyst, and a compound
thereof. The purification column 511 may include a heating device
(and a temperature regulating device) (not illustrated) for causing
the first treatment tower and the second treatment tower to operate
at a temperature that is higher than room temperature. The first
filter 512 and the second filter 516 may each be a filter for
trapping particles generated by discharge of a gas supplied between
the pair of discharge electrodes 211a and 211b in the chamber 210.
The first filter 512 and the second filter 516 may each be a filter
made of a material that hardly reacts with fluorine. The material
that hardly reacts with fluorine may be a metal or ceramic
material.
[0162] The first tank 513 may be a container configured to contain
a gas purified by the purification column 511 and the first filter
512. The volume of the first tank 513 may be 5 liters or larger and
15 liters or smaller.
[0163] The first pressure sensor 514 may be configured to measure a
pressure of the purified gas contained in the first tank 513. The
first pressure sensor 514 may be provided in the first tank 513.
The first pressure sensor 514 may be configured to send a signal
representing the measured gas pressure to the gas purification
control unit 520.
[0164] The second tank 517 may be a container configured to contain
a purified gas that is sent from the first tank 513 by the booster
pump 515. The volume of the second tank 517 may be 5 liters or
larger and 15 liters or smaller.
[0165] The second pressure sensor 518 may be configured to measure
a pressure of the purified gas contained in the second tank 517.
The second pressure sensor 518 may be provided in the second tank
517. The second pressure sensor 518 may be configured to send a
signal representing the measured gas pressure to the gas
purification control unit 520.
[0166] The booster pump 515 may be a pump configured to cause a gas
to flow through the circulation gas pipe. The booster pump 515 may
be provided between the first tank 513 and the second tank 517. The
booster pump 515 may be configured to send a gas from the first
tank 513 to the second tank 517. The booster pump 515 may receive a
signal from the gas purification control unit 520 and be controlled
by the gas purification control unit 520.
[0167] The purifier 519 may be a metal filter including a metal
getter serving as a purification agent for a gas contained in the
circulation gas pipe.
[0168] The following describes an operation of complete gas
replacement in the excimer laser apparatus 1000 according to the
second embodiment of the present disclosure.
[0169] First, the laser control unit 100 may send a signal for
starting complete gas replacement to the gas control unit 310 of
the gas control system 300.
[0170] Next, the gas control unit 310 may bring the exhaust pump
332 of the exhaust device 330 into operation.
[0171] Next, the gas control unit 310 may open the valve Ex-V, the
valve CV-1, and the valve C-V3 to exhaust the gas in the chamber
210 and the gas in the pipe of the gas purification device 510. The
gas control unit 310 may exhaust the gas in the chamber 210 and the
gas in the pipe of the gas purification device 510 until the
pressure P1 measured by the chamber pressure sensor 215 becomes a
pressure that is close to a vacuum.
[0172] Next, the gas control unit 310 may close the valve Ex-V and
stop the exhaust pump 332. The gas control unit 310 may close the
valve C-V1 and the valve C-V3.
[0173] Next, the gas control unit 310 may control the opening and
closing of the valves F2-V1 and B-V1 so that the pressure P1
measured by the chamber pressure sensor 215 may become equal to a
predetermined pressure and the composition of a gas that is
supplied to the chamber 210 may become a predetermined
composition.
[0174] In this manner, the chamber 210 may be filled with a gas.
The gas purification device 520 may be completely or substantially
in a vacuum state. In this manner, complete gas replacement in the
excimer laser apparatus 1000 according to the second embodiment of
the present disclosure may be performed.
[0175] Furthermore, the gas purification control unit 520 may heat
the purification column 511 (and control the temperature of the
purification column 511).
[0176] FIG. 7 is a diagram illustrating an example of operation of
the gas purification control unit of the laser apparatus including
the gas purification system according to the second embodiment of
the present disclosure.
[0177] In step S401, the gas purification control unit 520 may make
preparations for gas purification. In preparation for gas
purification, the circulation gas pipe of the gas purification
device 510 may be filled with a gas. In preparation for gas
purification, the purification column 511 may be heated. In
preparation for gas purification, the valve C-V1 and the valve C-V3
may be closed.
[0178] In step S402, the gas purification control unit 520 may
determine whether it has received, from the laser control unit 100
through the gas control unit 310, a signal for starting gas
purification. The laser control unit 100 may send the signal for
starting gas purification to the gas purification control unit 520
through the gas control unit 310 based on the predetermined number
of shots of laser oscillation, the predetermined time intervals,
and the like. In a case where the gas purification control unit 520
has received, from the laser control unit 100 through the gas
control unit 310, the signal for starting gas purification, the gas
purification control unit 520 may proceed to step S403. In a case
where the gas purification control unit 520 has not received, from
the laser control unit 100 through the gas control unit 310, the
signal for starting gas purification, the gas purification control
unit 520 may repeat step S402.
[0179] In step S403, the gas control unit 310 of the gas control
system 300 may as needed control the opening and closing of the
valve C-V1 and thereby introduce the gas in the chamber 210 of the
laser oscillation system 200 into the gas purification device 510.
The gas in the chamber 210 which is introduced into the gas
purification device 510 may be purified by the purification column
511 and the first filter 512 of the gas purification device 510.
The gas thus purified may be supplied to the first tank 513 of the
gas purification device 510.
[0180] In step S404, the gas purification control unit 520 may
control the booster pump 515 of the gas purification device 510.
The gas purification control unit 520 may receive a pressure P2 of
the gas in the first tank 513 of the gas purification device 510 as
measured by the first pressure sensor 514 of the gas purification
device 510. The booster pump 515 may be controlled so that the
pressure P2 of the gas in the first tank 513 of the gas
purification device 510 may fall within a predetermined range of
pressure. The booster pump 515 may be controlled so that the
pressure P2 of the gas in the first tank 513 may satisfy
P2min.ltoreq.P2.ltoreq.P2max. P2min may be the atmospheric pressure
(1013 hPa). P2max may be a pressure (e.g., 1300 hPa) that is higher
than the atmospheric pressure. The booster pump 515 may be
configured to send the gas contained in the first tank 513 to the
second tank 517. When the pressure P2 of the gas in the first tank
513 satisfies P2min P2, the booster pump 515 may more efficiently
send the gas contained in the first tank 513 to the second tank
517. When the pressure P2 of the gas in the first tank 513
satisfies P2 P2max, the booster pump 515 may more efficiently send
a part of the gas in the chamber 210 to the first tank 513 of the
gas purification device 510.
[0181] In step S405, the gas purification control unit 520 may
receive a pressure P3 of the gas in the second tank 517 of the gas
purification device 510 as measured by the second pressure sensor
518 of the gas purification device 510.
[0182] In step S406, the gas purification control unit 520 may
determine whether the pressure P3 of the gas in the second tank 517
is equal to or higher than a predetermined pressure P3reg. The
predetermined pressure P3reg may be a pressure (e.g., 5000 hPa or
higher and 5700 hPa or lower) indicated by a regulator provided in
a pipe through which the buffer gas is supplied. In a case where
the pressure P3 of the gas in the second tank 517 is equal to or
higher than the predetermined pressure P3reg, the gas purification
control unit 520 may proceed to step S407. In a case where the
pressure P3 of the gas in the second tank 517 is equal to or higher
than the predetermined pressure P3reg, the gas in the second tank
517 may be more efficiently sent to the chamber 210. In a case
where the pressure P3 of the gas in the second tank 517 is not
equal to or higher than the predetermined pressure P3reg, the gas
purification control unit 520 may return to step S403.
[0183] In step S407, the gas purification control unit 520 may
send, to the gas control unit 310, a signal permitting the supply
of purified gas to the chamber 210.
[0184] In step S408, the gas control unit 310 of the gas control
system 300 may as needed control the opening and closing of the
valve C-V3 and thereby introduce the purified gas in the gas
purification device 510 into the chamber 210 of the laser
oscillation system 200.
[0185] In step S409, the gas purification control unit 520 may
determine whether it has received, from the laser control unit 100
through the gas control unit 310, a signal for stopping gas
purification. The laser control unit 100 may send the signal for
stopping gas purification to the gas purification control unit 520
through the gas control unit 310 based on the pressure P1 measured
by the chamber pressure sensor 215 and the like. In a case where
the gas purification control unit 520 has received, from the laser
control unit 100 through the gas control unit 310, the signal for
stopping gas purification, the gas purification control unit 520
may terminate the operation of gas purification. In a case where
the gas purification control unit 520 has not received, from the
laser control unit 100 through the gas control unit 310, the signal
for stopping gas purification, the gas purification control unit
520 may return to step S403.
[0186] FIG. 8 is a diagram illustrating an example of operation of
the gas control unit of the laser apparatus including the gas
purification system according to the second embodiment of the
present disclosure.
[0187] In step S501, the gas control unit 310 may make preparations
for partial gas replacement. In preparation for partial gas
replacement, the valve F2-V1 and valve B-V1 of the gas supply
device 320 and the valve Ex-V of the exhaust device 330 may all be
closed. In preparation for partial gas replacement, the valve C-V1
may as needed be opened to increase the pressure P3 of the gas in
the second tank 513.
[0188] In step S502, the gas control unit 310 may determine whether
it has received, from the laser control unit 100, a signal for
starting partial gas replacement and whether it has received, from
the gas purification control unit 520, a signal permitting the
supply of the purified gas to the chamber 210. The laser control
unit 100 may send the signal for starting partial gas replacement
to the gas control unit 310 based on a predetermined number of
shots of laser oscillation, predetermined time intervals, and the
like. The gas purification control unit 520 may send the signal
permitting the supply of the purified gas to the chamber 210 to the
gas control unit 310 based on the value of the pressure P3 measured
by the second pressure sensor 518. In a case where the gas control
unit 310 has received both the signal for starting partial gas
replacement from the laser control unit 100 and the signal
permitting the supply of the purified gas to the chamber 210 from
the gas purification control unit 520, the gas control unit 310 may
proceed to step S503. In a case where the gas control unit 310 has
not received at least either the signal for starting partial gas
replacement from the laser control unit 100 or the signal
permitting the supply of the purified gas to the chamber 210 from
the gas purification control unit 520, the gas control unit 310 may
repeat step S502.
[0189] In step S503, the gas control unit 310 may receive an
initial pressure P10 of the gas in the chamber 210 (i.e., a
pressure of the gas in the chamber 210 before partial gas
replacement) from the chamber pressure sensor 215.
[0190] In step S504, the gas control unit 310 may calculate a
target value P1b of the pressure of the gas in the chamber 210
after supplying the purified gas to the chamber 210.
[0191] In step S505, the gas control unit 310 may receive the
pressure P1 of the gas in the chamber 210 from the chamber pressure
sensor 215 and may control the valve C-V3 so that the pressure P1
may become closer to the target value P1b. In this manner, the
purified gas may be supplied from the gas purification device 510
to the chamber 210.
[0192] In step S506, the gas control unit 310 may calculate a
target value .DELTA.P1F2 of a rise in pressure in the chamber 210
due to supplying the fluorine-containing gas to the chamber 210.
The gas control unit 310 may calculate the target value .DELTA.P1F2
of the rise in pressure so that the concentration of a fluorine gas
in the gas in the chamber 210 may become equal to a predetermined
concentration CF2. For example, in a case where the
fluorine-containing gas is a fluorine gas, the target value
.DELTA.P1F2 of the rise in pressure may be calculated according to
the formulae .DELTA.P1b=P1b-P10 and
.DELTA.P1F2=CF2.times..DELTA.P1b/(1-CF2). In a case where the
fluorine-containing gas is a mixed gas, the calculation may be
performed further in consideration of a mixing ratio of
fluorine.
[0193] In step S507, the gas control unit 310 may calculate a
target value P1F2 of the pressure of the gas in the chamber 210
after supplying the fluorine-containing gas to the chamber 210. The
target value P1F2 of the pressure may be calculated according to
the formula P1F2=P1b+.DELTA.P1F2.
[0194] In step S508, the gas control unit 310 may receive the
pressure P1 of the gas in the chamber 210 from the chamber pressure
sensor 215 and may control the valve F2-V1 so that the pressure P1
may become closer to the target value P1F2. In this manner, the
fluorine-containing gas may be supplied to the chamber 210.
[0195] In step S509, the gas control unit 310 may receive the
pressure P1 of the gas in the chamber 210 from the chamber pressure
sensor 215 and may control the valve C-V1 so that the pressure P1
may become closer to the initial pressure P10. In this manner, a
part of the gas in the chamber 210 may be introduced into the gas
purification device 510.
[0196] In step S510, the gas control unit 310 may determine whether
it has received, from the laser control unit 100, a signal for
stopping partial gas replacement. The laser control unit 100 may
send the signal for stopping partial gas replacement to the gas
control unit 310 based on the pressure P1 measured by the chamber
pressure sensor 215 and the like. In a case where the gas control
unit 310 has received, from the laser control unit 100, the signal
for stopping partial gas replacement, the gas control unit 310 may
terminate the operation of partial gas replacement. In a case where
the gas control unit 310 has not received, from the laser control
unit 100, the signal for stopping partial gas replacement, the gas
control unit 310 may return to step S502.
[0197] In this manner, the laser apparatus 1000 according to the
second embodiment of the present disclosure makes it possible to
purify a part of the gas in the chamber 210 and supply the purified
gas to the chamber 210. In this manner, the laser apparatus 1000
according to the second embodiment of the present disclosure makes
it possible to reduce the amount of a gas that is sent from the
buffer gas supply source 3200 to the chamber 210.
[0198] 3.3 Laser Apparatus Including Gas Purification System
According to Third Embodiment of Present Disclosure
[0199] FIG. 9 is a diagram illustrating an example of a
configuration of a laser apparatus including a gas purification
system according to a third embodiment of the present disclosure.
The laser apparatus shown in FIG. 9 may include the same
configuration as the laser apparatus illustrated in FIG. 6.
Components of the laser apparatus illustrated in FIG. 9 which are
identical to those of the laser apparatus illustrated in FIG. 6 are
given the same reference signs, and as such, are omitted from the
description below.
[0200] The laser apparatus according to the third embodiment of the
present disclosure may include a plurality of excimer laser
apparatuses such as a first excimer laser apparatus 1001 and a
second excimer laser apparatus 1002.
[0201] One end of a circulation gas pipe of the gas purification
system 500 may be connected through a plurality of valves C-V1 of
the plurality of excimer laser apparatuses to a plurality of pipes.
The plurality of pipes are connected to the plurality of chambers
210 of the plurality of excimer laser apparatuses, respectively,
and to a plurality of exhaust devices 330, respectively.
[0202] The other end of the circulation gas pipe of the gas
purification system 500 may be connected to a pipe connecting the
buffer gas supply source 3200 and the plurality of gas supply
devices 320 of the plurality of excimer laser apparatuses. The pipe
connecting the buffer gas supply source 3200 and the plurality of
gas supply devices 320 of the plurality of excimer laser
apparatuses may correspond to a common pipe in the present
disclosure. A gas purified by the gas purification device 510 may
be supplied from the gas purification device 510 at completely or
substantially the same pressure as the pressure of the regulator
for the buffer gas supply source 3200. This allows a single gas
purification device 510 to supply the purified gas to the plurality
of excimer laser apparatuses.
[0203] The fluorine-containing gas supply source 3100 and the
buffer gas supply source 3200 may be connected to the plurality of
gas supply devices 320 of the plurality of excimer laser
apparatuses.
[0204] The gas purification system 500 of the laser apparatus
according to the third embodiment of the present disclosure may
further include an oximeter 600. The oximeter 600 may be one
configured to measure the concentration of oxygen in a gas flowing
through the circulation gas pipe of the gas purification system
500. The oximeter 600 may be configured to send, to the gas
purification control unit 520, data representing the concentration
of oxygen in the gas flowing through the circulation gas pipe of
the gas purification system 500.
[0205] In the laser apparatus according to the third embodiment of
the present disclosure, a valve B-V2 may be provided to a pipe
present between (i) the circulation gas pipe of the gas
purification system 500 connected to the plurality of gas supply
devices 320 of the plurality of excimer laser apparatuses and (ii)
the regulator provided in the buffer gas supply source 3200.
[0206] The plurality of valves C-V1 of the plurality of excimer
laser apparatuses may be controlled by the plurality of gas control
units 310 of the plurality of excimer laser apparatuses,
respectively.
[0207] The gas purification control unit 520 may perform at least
either sending signals or receiving signals to or from the
plurality of gas control units 310 through the laser control units
100 of the plurality of excimer laser apparatuses.
[0208] The following describes an operation of exhaust for the
circulation gas pipe of the gas purification device 510 in the
excimer laser apparatus 1000 according to the third embodiment of
the present disclosure.
[0209] First, the gas purification control unit 520 may close the
valve C-V3 and may close the plurality of valves C-V1 of the
plurality of excimer laser apparatuses through the plurality of
laser control units 100 and gas control units 310 of the plurality
of excimer laser apparatuses.
[0210] Next, by bringing into operation an exhaust pump (not
illustrated) connected to the circulation gas pipe of the gas
purification device 510, the circulation gas pipe of the gas
purification device 510 may be exhausted until pressures measured
by the first pressure sensor 514 and the second pressure sensor 518
become pressures that are close to a vacuum. In this manner, the
circulation gas pipe of the gas purification device may be brought
into a state that is close to a vacuum.
[0211] FIG. 10 is a diagram illustrating an example of operation of
the gas purification control unit of the laser apparatus including
the gas purification system according to the third embodiment of
the present disclosure.
[0212] In step S601, the gas purification control unit 520 may make
preparations for gas purification. In preparation for gas
purification, the circulation gas pipe of the gas purification
device 510 may be filled with a gas. In preparation for gas
purification, the purification column 511 may be heated. In
preparation for gas purification, the valves C-V1 and the valve
C-V3 may be closed.
[0213] In step S602, the gas purification control unit 520 may
determine whether it has received, from the laser control unit 100
of each excimer laser apparatus through the gas control unit 310 of
the corresponding excimer laser apparatus, a signal for starting
gas purification. Each laser control unit 100 may send the signal
for starting gas purification to the gas purification control unit
520 through the corresponding gas control unit 310 based on the
predetermined number of shots of laser oscillation, the
predetermined time intervals, and the like. In a case where the gas
purification control unit 520 has received, from each laser control
unit 100 through the corresponding gas control unit 310, the signal
for starting gas purification, the gas purification control unit
520 may proceed to step S603. In a case where the gas purification
control unit 520 has not received, from each laser control unit 100
through the corresponding gas control unit 310, the signal for
starting gas purification, the gas purification control unit 520
may repeat step S602.
[0214] In step S603, the gas purification control unit 520 may open
the valve B-V2 and close the valve C-V3. That is, in a case where
any of the plurality of gas control units 310 performs partial gas
replacement, the supply of the buffer gas from the buffer gas
supply source 3200 to each chamber 210 may be prepared.
[0215] In step S604, each gas control unit 310 may as needed
control the opening and closing of the corresponding valve C-V1 and
thereby introduce the gas in the corresponding chamber 210 into the
gas purification device 510. The gas in each chamber 210 which is
introduced into the gas purification device 510 may be purified by
the purification column 511 and the first filter 512 of the gas
purification device 510. The gas thus purified may be supplied to
the first tank 513 of the gas purification device 510.
[0216] In step S605, the gas purification control unit 520 may
control the booster pump 515. The gas purification control unit 520
may receive a pressure P2 of the gas in the first tank 513 as
measured by the first pressure sensor 514. The booster pump 515 may
be controlled so that the pressure P2 of the gas in the first tank
513 may fall within a predetermined range of pressure. The booster
pump 515 may be controlled so that the pressure P2 of the gas in
the first tank 513 may satisfy P2min.ltoreq.P2.ltoreq.P2max. P2min
may be the atmospheric pressure (1013 hPa). P2max may be a pressure
(e.g., 1300 hPa) that is higher than the atmospheric pressure. The
booster pump 515 may be configured to send the gas contained in the
first tank 513 to the second tank 517. When the pressure P2 of the
gas in the first tank 513 satisfies P2min P2, the booster pump 515
may more efficiently send the gas contained in the first tank 513
to the second tank 517. When the pressure P2 of the gas in the
first tank 513 satisfies P2.ltoreq.P2max, the booster pump 515 may
more efficiently send a part of the gas in each chamber 210 to the
first tank 513 of the gas purification device 510.
[0217] In step S606, the gas purification control unit 520 may
receive a pressure P3 of the gas in the second tank 517 as measured
by the second pressure sensor 518.
[0218] In step S607, the gas purification control unit 520 may
determine whether the pressure P3 of the gas in the second tank 517
is equal to or higher than a predetermined pressure P3reg. The
predetermined pressure P3reg may be a pressure (e.g., 5000 hPa or
higher and 5700 hPa or lower) indicated by a regulator provided in
a pipe through which the buffer gas is supplied. In a case where
the pressure P3 of the gas in the second tank 517 is equal to or
higher than the predetermined pressure P3reg, the gas purification
control unit 520 may proceed to step S608. In a case where the
pressure P3 of the gas in the second tank 517 is equal to or higher
than the predetermined pressure P3reg, the gas in the second tank
517 may be more efficiently sent to each chamber 210. In a case
where the pressure P3 of the gas in the second tank 517 is not
equal to or higher than the predetermined pressure P3reg, the gas
purification control unit 520 may return to step S603.
[0219] In step S608, the gas purification control unit 520 may
receive, from the oximeter 600, an oxygen concentration C in a gas
flowing through the circulation gas pipe of the gas purification
device 510. The oxygen concentration C may be measured by the
oximeter 600 of the gas purification control unit 520.
[0220] In step S609, the gas purification control unit 520 may
determine whether the oxygen concentration C in the gas flowing
through the circulation gas pipe of the gas purification device 510
is equal to or lower than a predetermined concentration Cmax. In a
case where the oxygen concentration C in the gas flowing through
the circulation gas pipe of the gas purification device 510 is
equal to or lower than the predetermined concentration Cmax, the
gas purification control unit 520 may proceed to step S610. In a
case where the oxygen concentration C in the gas flowing through
the circulation gas pipe of the gas purification device 510 is
equal to or lower than the predetermined concentration Cmax, the
purification column 511 may function normally. In a case where the
oxygen concentration C in the gas flowing through the circulation
gas pipe of the gas purification device 510 is not equal to or
lower than the predetermined concentration Cmax, the gas
purification control unit 520 may proceed to step S611. In a case
where the oxygen concentration C in the gas flowing through the
circulation gas pipe of the gas purification device 510 is not
equal to or lower than the predetermined concentration Cmax, the
purification column 511 may not necessarily function normally.
[0221] In step S610, the gas purification control unit 520 may
close the valve B-V2 and open the valve C-V3. That is, in a case
where any of the plurality of gas control units 310 performs
partial gas replacement, the supply of a gas purified by the gas
purification device 510 from the gas purification device 510 to
each chamber 210 may be prepared. After step S610, the gas
purification control unit 520 may proceed to step S612.
[0222] In step S611, the gas purification control unit 520 may
output, to each laser control unit 100, a signal for renewal or
replacement of the purification column 511 or a signal indicating
that the purification of a gas by the purification column 511 is
difficult or impossible. In step S611, renewal or replacement of
the purification column 511 may be performed.
[0223] In step S612, each gas control unit 310 may as needed
control the opening and closing of the corresponding valve B-V1 and
thereby introduce the gas purified by the gas purification device
510 into the corresponding chamber 210.
[0224] In step S613, the gas purification control unit 520 may
determine whether it has received, from each laser control unit 100
through the corresponding gas control unit 310, a signal for
stopping gas purification. Each laser control unit 100 may send the
signal for stopping gas purification to the gas purification
control unit 520 through the corresponding gas control unit 310
based on the pressure P1 measured by a chamber pressure sensor (not
illustrated) and the like. In a case where the gas purification
control unit 520 has received, from each laser control unit 100
through the corresponding gas control unit 310, the signal for
stopping gas purification, the gas purification control unit 520
may terminate the operation of gas purification. In a case where
the gas purification control unit 520 has not received, from each
laser control unit 100 through the corresponding gas control unit
310, the signal for stopping gas purification, the gas purification
control unit 520 may return to step S604.
[0225] FIG. 11 is a diagram illustrating an example of operation of
each gas control unit of the laser apparatus including the gas
purification system according to the third embodiment of the
present disclosure.
[0226] In step S701, each gas control unit 310 may make
preparations for partial gas replacement. In preparation for
partial gas replacement, the valve F2-V1 and valve B-V1 of each gas
supply device 320, the valve Ex-V of each exhaust device 330, and
each valve C-V1 may all be closed. In preparation for partial gas
replacement, the exhaust pump 332 of each exhaust device 330 may be
brought into operation.
[0227] In step S702, each gas control unit 310 may determine
whether it has received, from the corresponding laser control unit
100, a signal for starting partial gas replacement. Each laser
control unit 100 may send the signal for starting partial gas
replacement to the corresponding gas control unit 310 based on a
predetermined number of shots of laser oscillation, predetermined
time intervals, and the like. In a case where each gas control unit
310 has received, from the corresponding laser control unit 100,
the signal for starting partial gas replacement, the gas control
unit 310 may proceed to step S703. In a case where each gas control
unit 310 has not received, from the corresponding laser control
unit 100, the signal for starting partial gas replacement, the gas
control unit 310 may repeat step S702.
[0228] In step S703, each gas control unit 310 may receive an
initial pressure P10 of the gas in the corresponding chamber 210
(i.e., a pressure of the gas in the corresponding chamber 210
before partial gas replacement) from the corresponding pressure
sensor.
[0229] In step S704, each gas control unit 310 may calculate a
target value P1b of the pressure of the gas in the corresponding
chamber 210 after supplying the buffer gas or the purified gas to
the corresponding chamber 210.
[0230] In step S705, each gas control unit 310 may receive the
pressure P1 of the gas in the corresponding chamber 210 from the
corresponding pressure sensor and may control the corresponding
valve B-V1 so that the pressure P1 may become closer to the target
value P1b. At this point in time, in a case where the valve B-V2 is
open and the valve C-V3 is closed, as described in the
aforementioned step S603, the buffer gas may be supplied from the
buffer gas supply source 3200 to each chamber 210. Alternatively,
in a case where the valve B-V2 is closed and the valve C-V3 is
open, as described in the aforementioned step S610, the purified
gas may be supplied from the gas purification device 510 to each
chamber 210. In this manner, each gas control unit 310 may cause
the buffer gas or the purified gas to be supplied to the
corresponding chamber 210.
[0231] In step S706, each gas control unit 310 may calculate a
target value .DELTA.P1F2 of a rise in pressure in the corresponding
chamber 210 due to supplying the fluorine-containing gas to the
corresponding chamber 210. Each gas control unit 310 may calculate
the target value .DELTA.P1F2 of the rise in pressure so that the
concentration of a fluorine gas in the gas in the corresponding
chamber 210 may become equal to a predetermined concentration CF2.
For example, in a case where the fluorine-containing gas is a
fluorine gas, the target value .DELTA.P1F2 of the rise in pressure
may be calculated according to the formulae .DELTA.P1b=P1b-P10 and
.DELTA.P1F2=CF2.times..DELTA.P1b/(1-CF2). In a case where the
fluorine-containing gas is a mixed gas, the calculation may be
performed further in consideration of a mixing ratio of
fluorine.
[0232] In step S707, each gas control unit 310 may calculate a
target value P1F2 of the pressure of the gas in the corresponding
chamber 210 after supplying the fluorine-containing gas to the
corresponding chamber 210. The target value P1F2 of the pressure
may be calculated according to the formula
P1F2=P1b+.DELTA.P1F2.
[0233] In step S708, each gas control unit 310 may receive the
pressure P1 of the gas in the corresponding chamber 210 from the
corresponding pressure sensor and may control the corresponding
valve F2-V1 so that the pressure P1 may become closer to the target
value P1F2. In this manner, each gas control unit 310 may cause the
fluorine-containing gas to be supplied to the corresponding chamber
210.
[0234] In step S709, each gas control unit 310 may receive the
pressure P1 of the gas in the corresponding chamber 210 from the
corresponding chamber pressure sensor 215 and may control the
corresponding valve C-V1 so that the pressure P1 may become closer
to the initial pressure P10. In this manner, each gas control unit
310 may introduce a part of the gas in the corresponding chamber
210 into the gas purification device 510.
[0235] In step S710, each gas control unit 310 may determine
whether it has received, from the corresponding laser control unit
100, a signal for stopping partial gas replacement. Each laser
control unit 100 may send the signal for stopping partial gas
replacement to the corresponding gas control unit 310 based on the
pressure P1 measured by the corresponding pressure sensor and the
like. In a case where each gas control unit 310 has received, from
the corresponding laser control unit 100, the signal for stopping
partial gas replacement, the gas control unit 310 may terminate the
operation of partial gas replacement. In a case where each gas
control unit 310 has not received, from the corresponding laser
control unit 100, the signal for stopping partial gas replacement,
the gas control unit 310 may return to step S702.
[0236] 3.4 Laser Apparatus Including Gas Purification System
According to Fourth Embodiment of Present Disclosure
[0237] FIG. 12 is a diagram illustrating an example of a
configuration of a laser apparatus including a gas purification
system according to a fourth embodiment of the present disclosure.
The laser apparatus shown in FIG. 12 may include the same
configuration as the laser apparatus illustrated in FIG. 9.
Components of the laser apparatus illustrated in FIG. 12 which are
identical to those of the laser apparatus illustrated in FIG. 9 are
given the same reference signs, and as such, are omitted from the
description below.
[0238] In the laser apparatus according to the fourth embodiment of
the present disclosure, a gas supply source 3300 containing
fluorine and a small amount of xenon may be used instead of the
fluorine-containing gas supply source 3100. The gas supply source
3300 may supply a gas containing fluorine and a small amount of
xenon to each chamber 210 through the corresponding gas supply
device 320. The gas containing fluorine and a small amount of xenon
may be a mixed gas of fluorine, argon, neon, and xenon. The gas
containing fluorine and a small amount of xenon may be a mixed gas
of fluorine, krypton, neon, and xenon.
[0239] In the laser apparatus according to the fourth embodiment of
the present disclosure, a buffer gas supply source 3400 containing
a small amount of xenon may be used instead of the buffer gas
supply source 3200. The buffer gas supply source 3400 may supply a
buffer gas containing a small amount of xenon to each chamber 210
through the corresponding gas supply device 320. The buffer gas
containing a small amount of xenon may be a mixed gas of argon,
neon, and xenon. The buffer gas containing a small amount of xenon
may be a mixed gas of krypton, neon, and xenon.
[0240] Use of gasses containing small amounts of xenon such as the
gas containing fluorine and a small amount of xenon and the buffer
gas containing a small amount of xenon may stabilize discharge of a
gas supplied between the pair of discharge electrodes in each
chamber 210. The concentration of xenon in a gas containing a small
amount of xenon may be approximately 10 ppm.
[0241] Meanwhile, xenon may produce XeF.sub.2 by reacting with
fluorine according to the formula Xe+F.sub.2.fwdarw.XeF.sub.2.
XeF.sub.2 produced by the reaction between xenon and fluorine may
be adsorbed to a metal surface to reduce the concentration of xenon
in the gas supplied to each chamber 210. Since the purification
column 511, first filter 512, and second filter 516 of the gas
purification system 500 have metal surfaces with larger surface
areas, XeF.sub.2 may be adsorbed to the purification column 511,
the first filter 512, and the second filter 516. Such purification
by the gas purification system 500 of a part of the gas supplied to
each chamber 210 may reduce the concentration of xenon in the gas
that is supplied to each chamber 210. A reduction in the
concentration of xenon in the gas that is supplied to each chamber
210 may lead to a reduction in energy of initial pulse laser light
during burst operation of the laser apparatus. The burst operation
of the laser apparatus may be such that laser oscillation is
executed at a predetermined repetition frequency and the stoppage
of laser oscillation is repeated at predetermined time
intervals.
[0242] In the laser apparatus according to the fourth embodiment of
the present disclosure, a buffer gas supply source 3500 containing
a large amount of xenon may further be used. The buffer gas supply
source 3500 may supply a buffer gas containing a large amount of
xenon to each chamber 210 through the corresponding gas supply
device 320. The buffer gas containing a large amount of xenon may
be a mixed gas of argon, neon, and xenon. The buffer gas containing
a large amount of xenon may be a mixed gas of krypton, neon, and
xenon.
[0243] The gas purification system 500 in the laser apparatus
according to the fourth embodiment of the present disclosure may
further include a valve Xe-V1. The valve Xe-V1 may be provided to
supply the buffer gas containing a large amount of xenon from the
buffer gas supply source 3500 containing a large amount of xenon to
a pipe through which a purified gas is supplied from the gas
purification system 500 to each gas supply device 320. The gas
purification control unit 520 may send a signal to the valve Xe-V1,
and the valve Xe-V1 may receive a signal from the gas purification
control unit 520 and be controlled by the gas purification control
unit 520.
[0244] The gas purification device 510 in the laser apparatus
according to the fourth embodiment of the present disclosure may
further include a xenon concentration meter 700. The xenon
concentration meter 700 may be configured to measure the
concentration of xenon in the gas purified by the gas purification
system 500. The xenon concentration meter 700 may be a gas
chromatograph mass spectrometer (GS-MS). The xenon concentration
meter 700 may be configured to send the concentration of xenon in
the purified gas to the gas purification control unit 520.
[0245] In the laser apparatus according to the fourth embodiment of
the present disclosure, the gas purification control unit 520 may
receive the concentration of xenon in the purified gas from the
xenon concentration meter 700 as measured by the xenon
concentration meter 700. The gas purification control unit 520 may
control the opening and closing of the valve Xe-V1, depending on
the concentration of xenon in the purified gas as measured by the
xenon concentration meter 700. For example, in a case where the
concentration of xenon in the purified gas is lower than a
predetermined concentration, the valve Xe-V1 may be opened to
supply the buffer gas containing a large amount of xenon so that
the concentration of xenon in the purified gas may become equal to
the predetermined concentration. In this manner, a reduction in the
concentration of xenon in the purified gas may be suppressed.
Energy of pulse laser light that is outputted from the laser
apparatus according to the fourth embodiment of the present
disclosure may be stabilized.
[0246] In the laser apparatus according to the fourth embodiment of
the present disclosure, the concentration of xenon in the purified
gas may be measured by the xenon concentration meter 700. However,
changes in energy of pulse light that is outputted from each
excimer laser apparatus during burst operation and changes in
charging voltage Vhv that is supplied from each charger during
burst operation may be monitored. A reduction in the concentration
of xenon in the purified gas may be predicted from a relationship
between the initial energy of pulse light that is outputted from
each excimer laser apparatus during burst operation and the
charging voltage that is applied from each charger during burst
operation. The gas containing xenon may be supplied to the purified
gas on the basis of the predicted reduction in xenon
concentration.
[0247] FIG. 13 is a diagram illustrating an example of operation of
the gas purification control unit of the laser apparatus including
the gas purification system according to the fourth embodiment of
the present disclosure.
[0248] In step S801, the gas purification control unit 520 may make
preparations for gas purification. In preparation for gas
purification, the circulation gas pipe of the gas purification
device 510 may be filled with a gas. In preparation for gas
purification, the purification column 511 may be heated. In
preparation for gas purification, the valves C-V1 and the valve
C-V3 may be closed.
[0249] In step S802, the gas purification control unit 520 may
determine whether it has received, from the laser control unit 100
of each excimer laser apparatus through the gas control unit 310 of
that excimer laser apparatus, a signal for starting gas
purification. Each laser control unit 100 may send the signal for
starting gas purification to the gas purification control unit 520
through the corresponding gas control unit 310 based on the
predetermined number of shots of laser oscillation, the
predetermined time intervals, and the like. In a case where the gas
purification control unit 520 has received, from each laser control
unit 100 through the corresponding gas control unit 310, the signal
for starting gas purification, the gas purification control unit
520 may proceed to step S803. In a case where the gas purification
control unit 520 has not received, from each laser control unit 100
through the corresponding gas control unit 310, the signal for
starting gas purification, the gas purification control unit 520
may repeat step S802.
[0250] In step S803, the gas purification control unit 520 may open
the valve B-V2 and close the valve C-V3. In this manner, the gas
purification control unit 520 may cause the buffer gas containing a
small amount of xenon to be supplied from the buffer gas supply
source 3400 containing a small amount of xenon to each chamber
210.
[0251] In step S804, each gas control unit 310 may as needed
control the opening and closing of the corresponding valve C-V1 and
thereby introduce the gas in the corresponding chamber 210 into the
gas purification device 510. The gas in each chamber 210 which is
introduced into the gas purification device 510 may be purified by
the purification column 511 and the first filter 512 of the gas
purification device 510. The gas thus purified may be supplied to
the first tank 513 of the gas purification device 510.
[0252] In step S805, the gas purification control unit 520 may
control the booster pump 515. The gas purification control unit 520
may receive a pressure P2 of the gas in the first tank 513 as
measured by the first pressure sensor 514. The booster pump 515 may
be controlled so that the pressure P2 of the gas in the first tank
513 may fall within a predetermined range of pressure. The booster
pump 515 may be controlled so that the pressure P2 of the gas in
the first tank 513 may satisfy P2min.ltoreq.P2.ltoreq.P2max. P2min
may be the atmospheric pressure (1013 hPa). P2max may be a pressure
(e.g., 1300 hPa) that is higher than the atmospheric pressure. The
booster pump 515 may be configured to send the gas contained in the
first tank 513 to the second tank 517. When the pressure P2 of the
gas in the first tank 513 satisfies P2min P2, the booster pump 515
may more efficiently send the gas contained in the first tank 513
to the second tank 517. When the pressure P2 of the gas in the
first tank 513 satisfies P2.ltoreq.P2max, the booster pump 515 may
more efficiently send a part of the gas in each chamber 210 to the
first tank 513 of the gas purification device 510.
[0253] In step S806, the gas purification control unit 520 may
receive a pressure P3 of the gas in the second tank 517 as measured
by the second pressure sensor 518.
[0254] In step S807, the gas purification control unit 520 may
determine whether the pressure P3 of the gas in the second tank 517
is equal to or higher than a predetermined pressure P3reg. The
predetermined pressure P3reg may be a pressure (e.g., 5000 hPa or
higher and 5700 hPa or lower) indicated by a regulator provided in
a pipe through which the buffer gas is supplied. In a case where
the pressure P3 of the gas in the second tank 517 is equal to or
higher than the predetermined pressure P3reg, the gas purification
control unit 520 may proceed to step S808. In a case where the
pressure P3 of the gas in the second tank 517 is equal to or higher
than the predetermined pressure P3reg, the gas in the second tank
517 may be more efficiently sent to each chamber 210. In a case
where the pressure P3 of the gas in the second tank 517 is not
equal to or higher than the predetermined pressure P3reg, the gas
purification control unit 520 may return to step S803.
[0255] In step S808, the gas purification control unit 520 may
receive, from the oximeter 600, an oxygen concentration C in a gas
flowing through the circulation gas pipe of the gas purification
device 510. The oxygen concentration C may be measured by the
oximeter 600 of the gas purification control unit 520.
[0256] In step S809, the gas purification control unit 520 may
determine whether the oxygen concentration C in the gas flowing
through the circulation gas pipe of the gas purification device 510
is equal to or lower than a predetermined concentration Cmax. In a
case where the oxygen concentration C in the gas flowing through
the circulation gas pipe of the gas purification device 510 is
equal to or lower than the predetermined concentration Cmax, the
gas purification control unit 520 may proceed to step S810. In a
case where the oxygen concentration C in the gas flowing through
the circulation gas pipe of the gas purification device 510 is
equal to or lower than the predetermined concentration Cmax, the
purification column 511 may function normally. In a case where the
oxygen concentration C in the gas flowing through the circulation
gas pipe of the gas purification device 510 is not equal to or
lower than the predetermined concentration Cmax, the gas
purification control unit 520 may proceed to step S811. In a case
where the oxygen concentration C in the gas flowing through the
circulation gas pipe of the gas purification device 510 is not
equal to or lower than the predetermined concentration Cmax, the
purification column 511 may not necessarily function normally.
[0257] In step S810, the gas purification control unit 520 may
receive, from the xenon concentration meter 700, a xenon
concentration Cxe in a gas flowing through the circulation gas pipe
of the gas purification device 510. The xenon concentration Cxe may
be measured by the xenon concentration meter 700 of the gas
purification control unit 520. The gas purification control unit
520 may proceed to step S812.
[0258] In step S811, the gas purification control unit 520 may
output, to each laser control unit 100, a signal for renewal or
replacement of the purification column 511 or a signal indicating
that the purification of a gas by the purification column 511 is
difficult or impossible. In step S811, renewal or replacement of
the purification column 511 may be performed.
[0259] In step S812, the gas purification control unit 520 may
control the valve Xe-V1. The valve Xe-V1 may be controlled so that
the xenon concentration Cxe in the gas flowing through the
circulation gas pipe of the gas purification device 510 may fall
within a predetermined range.
[0260] In step S813, the gas purification control unit 520 may
close the valve B-V2 and open the valve C-V3. In this manner, the
gas purification control unit 520 may make preparations for the
supply of the gas purified by the gas purification device 510 from
the gas purification device 510 to each chamber 210.
[0261] In step S814, each gas control unit 310 may as needed
control the opening and closing of the corresponding valve B-V1 and
thereby introduce the gas purified by the gas purification device
510 into the corresponding chamber 210.
[0262] In step S815, the gas purification control unit 520 may
determine whether it has received, from each laser control unit 100
through the corresponding gas control unit 310, a signal for
stopping gas purification. Each laser control unit 100 may send the
signal for stopping gas purification to the gas purification
control unit 520 through the corresponding gas control unit 310
based on the pressure P1 measured by a chamber pressure sensor (not
illustrated) and the like. In a case where the gas purification
control unit 520 has received, from each laser control unit 100
through the corresponding gas control unit 310, the signal for
stopping gas purification, the gas purification control unit 520
may terminate the operation of gas purification. In a case where
the gas purification control unit 520 has not received, from each
laser control unit 100 through the corresponding gas control unit
310, the signal for stopping gas purification, the gas purification
control unit 520 may return to step S804.
[0263] 3.5 Laser Apparatus Including Gas Purification System
According to Fifth Embodiment of Present Disclosure
[0264] FIG. 14 is a diagram illustrating an example of a
configuration of a laser apparatus including a gas purification
system according to a fifth embodiment of the present disclosure.
The laser apparatus shown in FIG. 14 may include the same
configuration as the laser apparatus illustrated in FIG. 9.
Components of the laser apparatus illustrated in FIG. 14 which are
identical to those of the laser apparatus illustrated in FIG. 9 are
given the same reference signs, and as such, are omitted from the
description below.
[0265] In the laser apparatus according to the fifth embodiment of
the present disclosure, not the gas purification device 510 but
each excimer laser apparatus may be provided with a purification
column 511 and a first filter 512. Providing each excimer laser
apparatus with the purification column 511 and the first filter 512
allows a purified gas to flow through a pipe between that excimer
laser apparatus and the gas purification device 510.
[0266] 3.6 Laser Apparatus Including Gas Purification System
According to Sixth Embodiment of Present Disclosure
[0267] FIG. 15 is a diagram illustrating an example of a
configuration of a laser apparatus including a gas purification
system according to a sixth embodiment of the present disclosure.
The laser apparatus shown in FIG. 15 may include the same
configuration as the laser apparatus illustrated in FIG. 12.
Components of the laser apparatus illustrated in FIG. 15 which are
identical to those of the laser apparatus illustrated in FIG. 12
are given the same reference signs, and as such, are omitted from
the description below.
[0268] In the laser apparatus according to the sixth embodiment of
the present disclosure, each gas supply device 320 may include a
buffer gas cylinder 350 containing a large amount of xenon instead
of the buffer gas supply source containing a large amount of xenon.
The buffer gas cylinder 350 may supply a buffer gas containing a
large amount of xenon to the corresponding chamber 210. The buffer
gas cylinder 350 may be small in size, e.g., a cylinder of
approximately 1 liter.
[0269] In the laser apparatus according to the sixth embodiment of
the present disclosure, each gas supply device 320 may include a
valve Xe-V1 instead of the valve Xe-V1 of the gas purification
system 500. The valve Xe-V1 of each gas supply device 320 may be
provided in a pipe connecting the corresponding buffer gas cylinder
350 and the corresponding chamber 210. The valve Xe-V1 may be
controlled by the corresponding gas control unit 310.
[0270] FIGS. 16A to 16D are each a diagram for explaining a
principle of estimation of a xenon concentration on the basis of
changes in energy E of pulse light during burst operation in the
laser apparatus including the gas purification system according to
the sixth embodiment of the present disclosure.
[0271] FIG. 16A shows changes in pulse energy E in the early phase
of burst operation in a case where the xenon concentration is a
concentration Ct that is close to an optimum value and the charging
voltage V is constant. In a case where the xenon concentration is
close to the optimum value, the stability of the pulse energy E may
be high and the difference between the maximum value Emax of the
pulse energy E and the minimum value Emin of the pulse energy E may
be small.
[0272] FIG. 16B shows changes in pulse energy E in the early phase
of burst operation in a case where the xenon concentration is a
concentration C1 that is lower than the optimum value and the
charging voltage V is constant. When the xenon concentration is
lower, the stability of the pulse energy E may be lower and the
difference between the maximum value Emax of the pulse energy E and
the minimum value Emin of the pulse energy E may be larger.
[0273] FIG. 16C shows changes in pulse energy E in the early phase
of burst operation in a case where the xenon concentration is a
concentration C2 that is even lower than the concentration C1 and
the charging voltage V is constant. When the xenon concentration is
even lower, the stability of the pulse energy E may be even lower
and the difference between the maximum value Emax of the pulse
energy E and the minimum value Emin of the pulse energy E may be
even larger.
[0274] In this manner, the stability of the pulse energy E in the
early phase of burst operation in a case where the charging voltage
V is constant may be correlated with the xenon concentration.
[0275] FIG. 16D shows a relationship between the stability of the
pulse energy E in the early phase of burst operation and the xenon
concentration Cxe in a case where the charging voltage V is
constant. The stability of the pulse energy may be indicated by a
ratio Er of the minimum value Emin to the maximum value Emax. The
ratio Er is represented by the following formula:
Er=Emin/Emax
[0276] As shown in FIG. 16D, the xenon concentration Cxe may be
expressed as a function f(Er) of the ratio Er, and this function
may be stored. Use of the relationship between the ratio Er and the
xenon concentration Cxe makes it possible to estimate the xenon
concentration Cxe from the ratio Er without using a xenon
concentration meter.
[0277] FIGS. 17A to 17D are each a diagram for explaining a
principle of estimation of a xenon concentration on the basis of
changes in charging voltage V by a charger during burst operation
in the laser apparatus including the gas purification system
according to the sixth embodiment of the present disclosure.
[0278] FIG. 17A shows changes in charging voltage V in the early
phase of burst operation in a case where the xenon concentration is
a concentration Ct that is close to an optimum value and the pulse
energy E is constant. In a case where the xenon concentration is
close to the optimum value, the stability of the charging voltage V
may be high and the difference between the maximum value Vmax of
the charging voltage V and the minimum value Vmin of the charging
voltage V may be small.
[0279] FIG. 17B shows changes in charging voltage V in the early
phase of burst operation in a case where the xenon concentration is
a concentration C1 that is lower than the optimum value and the
pulse energy E is constant. When the xenon concentration is lower,
the stability of the charging voltage V may be lower and the
difference between the maximum value Vmax of the charging voltage V
and the minimum value Vmin of the charging voltage V may be
larger.
[0280] FIG. 17C shows changes in charging voltage V in the early
phase of burst operation in a case where the xenon concentration is
a concentration C2 that is even lower than the concentration C1 and
the pulse energy E is constant. When the xenon concentration is
even lower, the stability of the charging voltage V may be even
lower and the difference between the maximum value Vmax of the
charging voltage V and the minimum value Vmin of the charging
voltage V may be even larger.
[0281] In this manner, the stability of the charging voltage V in
the early phase of burst operation in a case where the pulse energy
E is constant may be correlated with the xenon concentration.
[0282] FIG. 17D shows a relationship between the stability of the
charging voltage V in the early phase of burst operation and the
xenon concentration Cxe in a case where the pulse energy E is
constant. The stability of the charging voltage V may be indicated
by a ratio Vr of the minimum value Vmin to the maximum value Vmax.
The ratio Vr is represented by the following formula:
Vr=Vmin/Vmax
[0283] As shown in FIG. 17D, the xenon concentration Cxe may be
expressed as a function g(Vr) of the ratio Vr, and this function
may be stored. Use of the relationship between the ratio Vr and the
xenon concentration Cxe makes it possible to estimate the xenon
concentration Cxe from the ratio Vr without using a xenon
concentration meter.
[0284] FIG. 18 is a diagram illustrating an example of operation of
a laser control unit of the laser apparatus including the gas
purification system according to the sixth embodiment of the
present disclosure. The laser control unit 100 may estimate the
xenon concentration Cxe through the following process. It should be
noted the same process as that shown in FIG. 18 may be performed in
the fourth embodiment.
[0285] In step S910, the laser control unit 100 may determine
whether to check the xenon concentration. For example, the laser
control unit 100 may determine to check the xenon concentration
when a predetermined period of time has elapsed since it checked
the xenon concentration last. In a case where the laser control
unit 100 checks the xenon concentration, the laser control unit 100
may proceed to step S920. In a case where the laser control unit
100 does not check the xenon concentration, the laser control unit
100 may repeat step S910.
[0286] In step S920, the laser control unit 100 may output a signal
representing exposure NG to the exposure device controller 2100 of
the exposure device 2000. This may enable operation in such a burst
pattern as to show the effect of a reduction in xenon
concentration.
[0287] In step S930, the laser control unit 100 may estimate the
xenon concentration Cxe by measuring burst characteristics. This
process will be described in detail later with reference to FIGS.
20 and 21.
[0288] In step S950, the laser control unit 100 may determine
whether the xenon concentration Cxe estimated in step S930 is equal
to or lower than a predetermined threshold Cxet. In a case where
the xenon concentration Cxe is not equal to or less than a
predetermined threshold Cxet, the laser control unit 100 may
proceed to step S960 in order to resume the exposure process. In a
case where the xenon concentration Cxe is equal to or lower than
the predetermined threshold Cxet, the laser control unit 100 may
proceed to step S970 in order to cause the gas control unit 310 to
execute xenon injection.
[0289] In step S960, the laser control unit 100 may output a signal
representing exposure OK to the exposure device controller 2100 of
the exposure device 2000. After step S960, the laser control unit
100 may return to step S910.
[0290] In step S970, the laser control unit 100 may send data
representing the xenon concentration Cxe to the gas control unit
310. This may enable the gas control unit 310 to execute a process
for xenon injection.
[0291] In step S980, the laser control unit 100 may determine
whether it has received a xenon injection signal from the gas
control unit 310. In a case where it has not received a xenon
injection signal, the laser control unit 100 may repeat step S980.
In a case where it has received a xenon injection signal, the laser
control unit 100 may return to S930 in order to newly estimate a
xenon concentration.
[0292] FIG. 19 is a diagram illustrating an example of operation of
a gas control unit of the laser apparatus including the gas
purification system according to the sixth embodiment of the
present disclosure. The gas control unit 310 may control the valve
Xe-V1 through the following process. It should be noted the same
process as that shown in FIG. 19 may be performed by the gas
purification control unit in the fourth embodiment.
[0293] In step S991, the gas control unit 310 may determine whether
it has received data representing the xenon concentration Cxe from
the laser control unit 100. The data representing the xenon
concentration Cxe may be data that is sent from the laser control
unit 100 in step S970 described with reference to FIG. 18. In a
case where the gas control unit 310 has not received data
representing the xenon concentration Cxe, the gas control unit 310
may repeat step S991. In a case where the gas control unit 310 has
received data representing the xenon concentration Cxe, the gas
control unit 310 may proceed to step S992.
[0294] In step S992, the gas control unit 310 may calculate the
difference .DELTA.Cxe between the xenon concentration Cxe and the
target concentration Ct according to the following formula:
.DELTA.Cxe=Cxe-Ct
[0295] The target concentration Ct may be a concentration that is
close to the optimum value described with reference to FIG. 16A or
17A. The target concentration Ct may be a concentration that is
higher than the threshold Cxet described with reference to FIG.
18.
[0296] In step S993, the gas control unit 310 may control the valve
Xe-V1 so that the difference .DELTA.Cxe may become closer to 0. By
controlling the valve Xe-V1, a small amount of a xenon gas may be
supplied into the chamber.
[0297] In step S994, the gas control unit 310 may wait for a
predetermined period of time. This predetermined period of time may
be a period of time assumed as a period of time it takes to show
the effect of xenon injection.
[0298] In step S995, the gas control unit 310 may send a xenon
injection signal to the laser control unit 100. The xenon injection
signal may be a signal that the laser control unit 100 receives in
step S980 described with reference to FIG. 18. After step S995, the
gas control unit 310 may return to step S991.
[0299] FIGS. 20 and 21 are each a diagram illustrating an example
of operation in which the laser control unit of the laser apparatus
including the gas purification system according to the sixth
embodiment of the present disclosure estimates the xenon
concentration Cxe.
[0300] FIG. 20 shows a first example of an operation for estimating
the xenon concentration Cxe on the basis of the stability of the
pulse energy E. The operation shown in FIG. 20 may be performed by
the laser control unit 100 as a subroutine of step S930 shown in
FIG. 18.
[0301] In step S931, the laser control unit 100 may set the
charging voltage V by the charger at a constant value.
[0302] In step S932, the laser control unit 100 may start burst
operation in a predetermined pattern. The burst operation may
include repetition of a trigger pattern including oscillation at a
repetition frequency of 6 kHz for 1 second and then a pause for 1
second, for example, so as to easily show the effect of a reduction
in xenon concentration.
[0303] In step S933, the laser control unit 100 may obtain data
representing the pulse energy E during burst operation from the
power monitor 220.
[0304] In step S934, the laser control unit 100 may calculate the
ratio Er of the minimum value Emin of the pulse energy E to the
maximum value Emax of the pulse energy E according to the following
formula:
Er=Emin/Emax
[0305] In step S935, the laser control unit 100 may calculate the
xenon gas concentration Cxe on the basis of the ratio Er of the
minimum value Emin of the pulse energy E to the maximum value Emax
of the pulse energy E.
[0306] After step S935, the laser control unit 100 may proceed to
step S950 described with reference to FIG. 18.
[0307] FIG. 21 shows a second example of an operation for
estimating the xenon concentration Cxe on the basis of the
stability of the charging voltage V. The operation shown in FIG. 21
may be performed by the laser control unit 100 as a subroutine of
step S930 shown in FIG. 18.
[0308] In step S936, the laser control unit 100 may set a target
value of the pulse energy E at a constant value.
[0309] In step S937, the laser control unit 100 may start burst
operation in a predetermined pattern. The burst operation may
include repetition of a trigger pattern including oscillation at a
repetition frequency of 6 kHz for 1 second and then a pause for 1
second, for example, so as to easily show the effect of a reduction
in xenon concentration.
[0310] In step S938, the laser control unit 100 may obtain data
representing the charging voltage V during burst operation.
[0311] In step S939, the laser control unit 100 may calculate the
ratio Vr of the minimum value Vmin of the charging voltage V to the
maximum value Vmax of the charging voltage V according to the
following formula:
Vr=Vmin/Vmax
[0312] In step S940, the laser control unit 100 may calculate the
xenon gas concentration Cxe on the basis of the ratio Vr of the
minimum value Vmin of the charging voltage V to the maximum value
Vmax of the charging voltage V.
[0313] After step S940, the laser control unit 100 may proceed to
step S950 described with reference to FIG. 18.
[0314] In a case where, during the burst operation shown in FIGS.
17A, 17B, and 21, the charging voltage V is controlled so that an
approximation to a predetermined pulse energy may be made and the
xenon concentration is estimated on the basis of a change in
charging voltage V at that time, the xenon concentration may be
estimated during actual exposure. This eliminates the need to
perform the process in steps S920 and S960 of FIG. 18.
[0315] Further, as shown in the graphs of FIGS. 16D and 17D, as the
xenon concentration increases to go beyond the target concentration
Ct, the Er and Vr values may reach the respective maximum values
and then the Er and Vr values may decrease. In this case, the gas
control unit may exhaust a part of the laser gas and inject a new
laser gas so that the xenon concentration may become lower.
[0316] 4. Controller According to Embodiment of Present
Disclosure
[0317] FIG. 22 is a diagram illustrating an example of a controller
according to an embodiment of the present disclosure.
[0318] Each of the controllers in the above-described embodiments
may be constituted by a general-purpose control device such as a
computer or a programmable controller. For example, the controller
may be constituted as described below.
(Configuration)
[0319] The controller may include a processing unit 4000, and a
storage memory 4005, a user interface 4010, a parallel input/output
(I/O) controller 4020, a serial I/O controller 4030, and an
analog-to-digital (A/D) and digital-to-analog (D/A) converter 4040
that are connected to the processing unit 4000. The processing unit
4000 may include a central processing unit (CPU) 4001, and a memory
4002, a timer 4003, and a graphics processing unit (GPU) 4004 that
are connected to the CPU 4001.
(Operation)
[0320] The processing unit 4000 may read out programs stored in the
storage memory 4005. The processing unit 4000 may execute read-out
programs, read out data from the storage memory 4005 in accordance
with the execution of the programs, or store data in the storage
memory 4005.
[0321] The parallel I/O controller 4020 may be connected to devices
communicable through parallel I/O ports. The parallel I/O
controller 4020 may control communication using digital signals
through parallel I/O ports that is performed in the process where
the processing unit 4000 executes programs.
[0322] The serial I/O controller 4030 may be connected to devices
communicable through serial I/O ports. The serial I/O controller
4030 may control communication using digital signals through serial
I/O ports that is performed in the process where the processing
unit 4000 executes programs.
[0323] The A/D and D/A converter 4040 may be connected to devices
communicable through analog ports. The A/D and D/A converter 4040
may control communication using analog signals through analog ports
that is performed in the process where the processing unit 4000
executes programs.
[0324] The user interface 4010 may be configured to display
progress of program execution by the processing unit 4000 to an
operator or to receive instructions by the operator to the
processing unit 4000 to stop execution of the programs or to
execute interruption processing.
[0325] The CPU 4001 of the processing unit 4000 may perform
arithmetic processing of programs. In the process where the CPU
4001 executes programs, the memory 4002 may temporally store
programs or temporally store data in the arithmetic process. The
timer 4003 may measure time or elapsed time to output the time or
the elapsed time to the CPU 4001 in accordance with the execution
of the programs. When image data is input to the processing unit
4000, the GPU 4004 may process the image data in accordance with
the execution of the programs and output the results to the CPU
4001.
(Connected Devices)
[0326] The devices communicable through parallel I/O ports, which
are connected to the parallel I/O controller 4020, may be parallel
I/O devices 5010 such as the emission trigger Tr, the charger, the
control valves, and the like.
[0327] The devices communicable through serial I/O ports, which are
connected to the serial I/O controller 4030, may be serial I/O
devices 5020 such as the laser control unit, the gas control unit,
and the gas purification control unit.
[0328] The devices communicable through analog ports, which are
connected to the A/D and D/A converter 4040, may be analog I/O
devices 5030 such as the optical sensor 223 and a pressure
sensor.
[0329] The aforementioned descriptions are intended to be taken
only as examples, and are not to be seen as limiting in any way.
Accordingly, it will be clear to those skilled in the art that
variations on the embodiments of the present disclosure can be made
without departing from the scope of the appended claims.
[0330] The terms used in the present specification and in the
entirety of the scope of the appended claims are to be interpreted
as not being limiting. For example, wording such as "includes" or
"is included" should be interpreted as not being limited to the
item that is described as being included. Furthermore, "has" should
be interpreted as not being limited to the item that is described
as being had. Furthermore, the modifier "a" or "an" as used in the
present specification and the scope of the appended claims should
be interpreted as meaning "at least one" or "one or more".
REFERENCE SIGNS LIST
[0331] 100 Laser control unit
[0332] 200 Laser oscillation system
[0333] 210 Chamber
[0334] 211a, 211b Discharge electrode
[0335] 212a, 212b Window
[0336] 213 Pulse power module
[0337] 214 Switch
[0338] 215 Chamber pressure sensor
[0339] 220 Power monitor
[0340] 221 Beam splitter
[0341] 222 Collector lens
[0342] 223 Optical sensor
[0343] 230 Charger
[0344] 240 Output coupling mirror
[0345] 250 Line narrow module
[0346] 251 Prism
[0347] 252 Grating
[0348] 300 Gas control system
[0349] 310 Gas control unit
[0350] 320 Gas supply device
[0351] 330 Exhaust device
[0352] 331 Fluorine trap
[0353] 332 Exhaust pump
[0354] 400 Gas purification system
[0355] 410 Gas purification device
[0356] 411 Purification column
[0357] 412 Filter
[0358] 413 Circulation pump
[0359] 414 Mass flow controller
[0360] 420 Gas purification control unit
[0361] 500 Gas purification system
[0362] 510 Gas purification device
[0363] 511 Purification column
[0364] 512 First filter
[0365] 513 First tank
[0366] 514 First pressure sensor
[0367] 515 Booster pump
[0368] 516 Second filter
[0369] 517 Second tank
[0370] 518 Second pressure sensor
[0371] 519 Purifier
[0372] 520 Gas purification control unit
[0373] 600 Oximeter
[0374] 700 Xenon concentration meter
[0375] 1000 Excimer laser apparatus
[0376] 1001 First excimer laser apparatus
[0377] 1002 Second excimer laser apparatus
[0378] 2000 Exposure device
[0379] 2100 Exposure device controller
[0380] 3100 Fluorine-containing gas supply source
[0381] 3200 Buffer gas supply source
[0382] 3300 Gas supply source containing fluorine and a small
amount of xenon
[0383] 3400 Buffer gas supply source containing a small amount of
xenon
[0384] 3500 Buffer gas supply source containing a large amount of
xenon
[0385] 4000 Processing unit
[0386] 4001 CPU
[0387] 4002 Memory
[0388] 4003 Timer
[0389] 4004 GPU
[0390] 4005 Storage memory
[0391] 4010 User interface
[0392] 4020 Parallel I/O controller
[0393] 4030 Serial I/O controller
[0394] 4040 A/D or D/A converter
[0395] 5010 Parallel I/O device
[0396] 5020 Serial I/O device
[0397] 5030 Analog I/O device
* * * * *