U.S. patent application number 17/325327 was filed with the patent office on 2022-03-31 for extreme ultraviolet light source systems.
The applicant listed for this patent is Samsung Electronics Co., Ltd.. Invention is credited to Myeongjun Gil, SUNGHYUP KIM, Injae Lee, Sanghoon Lee, Yebin Nam.
Application Number | 20220104336 17/325327 |
Document ID | / |
Family ID | |
Filed Date | 2022-03-31 |
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United States Patent
Application |
20220104336 |
Kind Code |
A1 |
KIM; SUNGHYUP ; et
al. |
March 31, 2022 |
EXTREME ULTRAVIOLET LIGHT SOURCE SYSTEMS
Abstract
Extreme ultraviolet light source systems may include a chamber
including a condensing mirror and having an intermediate focus, by
which extreme ultraviolet light reflected from the condensing
mirror is emitted along a first optical path, a blocking plate that
may be on the chamber so as to intersect the first optical path and
may include an opening through which the extreme ultraviolet light
is emitted, a transparent cover on the blocking plate so as to
cover the opening, a nozzle that may be between the chamber and the
blocking plate so that an end portion faces the intermediate focus
and may spray a first gas in a direction intersecting the first
optical path, and an exhaust pipe between the chamber and the
blocking plate so as to face the end portion of the nozzle.
Inventors: |
KIM; SUNGHYUP; (Hwaseong-si,
KR) ; Gil; Myeongjun; (Seoul, KR) ; Nam;
Yebin; (Suwon-si, KR) ; Lee; Sanghoon; (Seoul,
KR) ; Lee; Injae; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., Ltd. |
Suwon-si |
|
KR |
|
|
Appl. No.: |
17/325327 |
Filed: |
May 20, 2021 |
International
Class: |
H05G 2/00 20060101
H05G002/00; G03F 7/20 20060101 G03F007/20 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2020 |
KR |
10-2020-0126588 |
Claims
1. An extreme ultraviolet light source system comprising: a chamber
including a condensing mirror that is configured to reflect extreme
ultraviolet light along an optical path; a blocking plate on the
chamber and comprising an opening that is configured to pass the
extreme ultraviolet light therethrough; a transparent cover on the
blocking plate and covering the opening, the blocking plate
extending between the transparent cover and the chamber; a nozzle
between the chamber and the blocking plate and comprising an end
portion adjacent the opening, the end portion of the nozzle being
configured to spray a first gas in a direction intersecting the
optical path; and an exhaust pipe between the chamber and the
blocking plate and facing the end portion of the nozzle, wherein a
width of the transparent cover is larger than a width of the
opening.
2. The extreme ultraviolet light source system of claim 1, wherein
an internal space of the chamber is configured to include a second
gas that comprises a material the same as that of the first
gas.
3. The extreme ultraviolet light source system of claim 2, wherein
the first gas and the second gas are each hydrogen (H.sub.2)
gas.
4. The extreme ultraviolet light source system of claim 3, wherein
a temperature of the first gas is lower than a temperature of the
second gas.
5. The extreme ultraviolet light source system of claim 4, wherein
the temperature of the first gas is in a range of about 25.degree.
C. to about 230.degree. C., and the temperature of the second gas
is in a range of about 400.degree. C. to about 500.degree. C.
6. The extreme ultraviolet light source system of claim 1, wherein
the exhaust pipe comprises a pressure sensor that is configured to
measure an internal pressure of the exhaust pipe.
7. (canceled)
8. The extreme ultraviolet light source system of claim 1, wherein
the transparent cover includes: a transparent thin film layer that
is configured to pass the extreme ultraviolet light therethrough;
and a cover frame contacting an edge of the transparent thin film
layer.
9. (canceled)
10. The extreme ultraviolet light source system of claim 8, wherein
the transparent thin film layer has a thickness of in a range of 10
nm to 100 nm.
11. An extreme ultraviolet light source system comprising: a
chamber including a condensing mirror that is configured to reflect
extreme ultraviolet light along an optical path; a blocking plate
on the chamber and comprising an opening that is configured to pass
the extreme ultraviolet light therethrough; a transparent cover
replacement unit including a plurality of transparent covers on the
blocking plate, the plurality of transparent covers including a
first transparent cover covering the opening and a second
transparent cover adjacent to the first transparent cover; a nozzle
between the chamber and the blocking plate and comprising an end
portion adjacent the opening, the nozzle being configured to spray
a gas in a direction intersecting the optical path; an exhaust pipe
between the chamber and the blocking plate and facing the end
portion of the nozzle; a driving unit configured to move the
plurality of transparent covers; and a control unit configured to
control the driving unit to replace the first transparent cover
with the second transparent cover, wherein the exhaust pipe
includes a pressure sensor that is configured to measure an
internal pressure of the exhaust pipe and configured to transmit
the measured internal pressure to the control unit, and the control
unit is configured to control the driving unit to replace the first
transparent cover with the second transparent cover when the
measured internal pressure is higher than a predetermined
value.
12-14. (canceled)
15. The extreme ultraviolet light source system of claim 11,
wherein the plurality of transparent covers each include: a
transparent thin film layer that is configured to pass the extreme
ultraviolet light therethrough; and a cover frame contacting an
edge of the transparent thin film layer.
16-20. (canceled)
21. The extreme ultraviolet light source system of claim 1, wherein
the exhaust pipe is configured to receive the first gas from the
end portion of the nozzle.
22. The extreme ultraviolet light source system of claim 1, wherein
the end portion of the nozzle is adjacent to an intermediate focus,
and the condensing mirror is configured to reflect the extreme
ultraviolet light along the optical path by the intermediate
focus.
23. An extreme ultraviolet light source system comprising: a
chamber including a condensing mirror, that is configured to
reflect extreme ultraviolet light along an optical path; a blocking
plate on the chamber and comprising an opening that is configured
to pass the extreme ultraviolet light therethrough; a transparent
cover on the blocking plate and covering the opening, the blocking
plate extending between the transparent cover and the chamber; a
nozzle between the chamber and the blocking plate and comprising an
end portion adjacent the opening, the end portion of the nozzle
being configured to spray a first gas in a direction intersecting
the optical path; and an exhaust pipe between the chamber and the
blocking plate and facing the end portion of the nozzle, wherein an
internal space of the chamber is configured to include a second
gas, and a temperature of the first gas is lower than a temperature
of the second gas.
24. The extreme ultraviolet light source system of claim 23,
wherein the first gas and the second gas comprise the same
material.
25. The extreme ultraviolet light source system of claim 23,
wherein the temperature of the first gas is in a range of about
25.degree. C. to about 230.degree. C., and the temperature of the
second gas is in a range of about 400.degree. C. to about
500.degree. C.
26. The extreme ultraviolet light source system of claim 23,
wherein the exhaust pipe comprises a pressure sensor that is
configured to measure an internal pressure of the exhaust pipe.
27. The extreme ultraviolet light source system of claim 23,
wherein the transparent cover includes: a transparent thin film
layer that is configured to pass the extreme ultraviolet light
therethrough; and a cover frame contacting an edge of the
transparent thin film layer.
28. The extreme ultraviolet light source system of claim 23,
further comprising: a droplet supply unit that is configured to
discharge a droplet along a first path and above the condensing
mirror and is on a side wall of the chamber; and a laser light
source configured to irradiate the droplet with laser light at a
focal point on the first path, wherein the exhaust pipe is
configured to receive debris from the droplet.
29. The extreme ultraviolet light source system of claim 28,
wherein the droplet comprises tin (Sn).
30. The extreme ultraviolet light source system of claim 23,
wherein the transparent cover is a first transparent cover of a
transparent cover replacement unit that further comprises a second
transparent cover adjacent to the first transparent cover, wherein
the extreme ultraviolet light source system further comprises: a
driving unit configured to move the first and second transparent
covers; and a control unit configured to control the driving unit
to replace the first transparent cover with the second transparent
cover, wherein the control unit is configured to control the
driving unit to replace the first transparent cover with the second
transparent cover upon a predetermined time elapsing.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims priority under 35 U.S.C. .sctn. 119
to Korean Patent Application No. 10-2020-0126588 filed on Sep. 29,
2020 in the Korean Intellectual Property Office, the disclosure of
which is incorporated herein by reference in its entirety.
BACKGROUND
[0002] The present disclosure relates to an extreme ultraviolet
light source system.
[0003] Recently, a lithography method using extreme ultraviolet
light for fine machining of a semiconductor device has been
proposed. A critical dimension of a circuit formed by the
lithography method may depend on a wavelength of a light source.
Therefore, it may be beneficial to shorten a wavelength of a light
source used for a lithography method to form fine patterns of a
semiconductor device. The extreme ultraviolet light has a
wavelength of about 1 nm to 100 nm. Since the extreme ultraviolet
light is highly absorbable by any material, a reflection type
optical system may be used, rather than a transmission type optical
system such as a lens. A laser produced plasma (LPP) method using a
laser irradiation method has been used for generation of light of
an extreme ultraviolet light source.
SUMMARY
[0004] Example embodiments of the present invention provide an
extreme ultraviolet light source system that may reduce or possibly
prevent contamination of a mask of a lithography apparatus by
debris from a droplet.
[0005] According to some embodiments of the present invention, an
extreme ultraviolet light source system may include: a chamber
including a condensing mirror and having an intermediate focus, by
which extreme ultraviolet light reflected from the condensing
mirror may be emitted along a first optical path; a blocking plate
on (e.g., in front of) the chamber, which may intersect the first
optical path and may include an opening through which the extreme
ultraviolet light may be emitted; a transparent cover on the
blocking plate so as to cover the opening; a nozzle that may be
between the chamber and the blocking plate so that an end portion
may face the intermediate focus and may spray a first gas in a
direction intersecting the first optical path; and an exhaust pipe
between the chamber and the blocking plate so as to face the end
portion of the nozzle. In some embodiments, the blocking plate may
extend between the transparent cover and the chamber.
[0006] According to some embodiments of the present invention, an
extreme ultraviolet light source system may include: a chamber
including a condensing mirror and having an intermediate focus, by
which extreme ultraviolet light reflected from the condensing
mirror may be emitted along a first optical path; a blocking plate
on (e.g., in front of) the chamber, which may intersect the first
optical path and may include an opening through which the extreme
ultraviolet light may be emitted; a transparent cover replacement
unit including a plurality of transparent covers that may include a
first transparent cover on the blocking plate so as to cover the
opening and a second transparent cover that is adjacent to the
first transparent cover and is moved along one direction by a
driving unit, a nozzle that may be between the chamber and the
blocking plate so that an end portion may face the intermediate
focus and may spray gas in a direction intersecting the first
optical path; an exhaust pipe between the chamber and the blocking
plate so as to face the end portion of the nozzle; and a control
unit that controls the driving unit to replace the first
transparent cover with the second transparent cover.
[0007] According to some embodiments of the present invention, an
extreme ultraviolet light source system may include: a chamber
including a condensing mirror and having an intermediate focus, by
which extreme ultraviolet light reflected from the condensing
mirror may be emitted along a first optical path; a droplet supply
unit that may be arranged so as to discharge a droplet along a
first path intersecting and above the condensing mirror and may be
on one side wall of the chamber; a laser light source irradiating
the droplet with laser light at a focal point on the first path; a
blocking plate that may be on (e.g., in front of) the chamber so as
to intersect the first optical path and may include an opening
through which the extreme ultraviolet light may be emitted; a
transparent cover on the blocking plate so as to cover the opening;
a nozzle that may be between the chamber and the blocking plate so
that an end portion may face the intermediate focus and may spray a
first gas in a direction intersecting the first optical path; and
an exhaust pipe that may be between the chamber and the blocking
plate so as to face the end portion of the nozzle and may provide a
path through which debris from the droplet passing through the
intermediate focus moves. In some embodiments, the blocking plate
may extend between the transparent cover and the chamber.
BRIEF DESCRIPTION OF DRAWINGS
[0008] The above and other aspects, features, and advantages of the
present invention will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0009] FIG. 1 is a view schematically illustrating an extreme
ultraviolet light exposure equipment adopting an extreme
ultraviolet light source system according to some embodiments of
the present invention;
[0010] FIG. 2 is a side cross-sectional view schematically
illustrating an extreme ultraviolet light source system according
to some embodiments of the present invention;
[0011] FIG. 3 is an enlarged view of a part A of FIG. 2;
[0012] FIG. 4 is an exploded perspective view of an extreme
ultraviolet light source system according to some embodiments of
the present invention; and
[0013] FIGS. 5 and 6 are views illustrating an extreme ultraviolet
light source system according to some embodiments of the present
invention.
DETAILED DESCRIPTION
[0014] Hereinafter, some example embodiments of the present
invention will now be described in detail with reference to the
accompanying drawings.
[0015] FIG. 1 is a view schematically illustrating an extreme
ultraviolet light exposure equipment adopting an extreme
ultraviolet light source system according to some embodiments of
the present invention, FIG. 2 is a side cross-sectional view
schematically illustrating an extreme ultraviolet light source
system according to some embodiments of the present invention, and
FIG. 3 is an enlarged view of a part A of FIG. 2.
[0016] Referring to FIG. 1, an extreme ultraviolet light exposure
equipment 1 may include a light exposure chamber 90, an extreme
ultraviolet light source system SO, a lithography apparatus LA, a
projection system PS, an upper electrostatic chuck (ESC) 72, and a
lower electrostatic chuck 80. Each component of the extreme
ultraviolet light exposure equipment 1 may be controlled by a
control unit CON.
[0017] The control unit CON, which may control an overall operation
of the light exposure equipment 1, may be implemented by, for
example, a central processing unit (CPU), a graphics processing
unit (GPU), a microprocessor, an application specific integrated
circuit (ASIC), and/or a field programmable gate arrays (FPGA), and
may include a memory for storing various data for the operation of
the light exposure equipment 1. As used herein the term "and/or"
includes any and all combinations of one or more of the associated
listed items.
[0018] The light exposure chamber 90 may include an internal space
91, and the extreme ultraviolet light source system SO, the
lithography apparatus LA, the projection system PS, the upper
electrostatic chuck 72, and the lower electrostatic chuck 80 may be
disposed in the internal space 91. However, in some embodiments,
some components may be disposed outside the exposure chamber 90.
For example, a portion of the light source system SO may be
disposed outside the exposure chamber 90. A mask 71 may be loaded
or unloaded on or from the upper electrostatic chuck 72 by an
electrostatic force generated by, for example, power applied from a
power supply unit 73, and a substrate W such as a semiconductor
wafer may be loaded or unloaded on or from the lower electrostatic
chuck 80. The internal space 91 of the light exposure chamber 90
may have a low pressure of, for example, about 5 Pa or lower, or
may be in a vacuum state in order to reduce or possibly prevent
absorption of extreme ultraviolet light B by gas, the extreme
ultraviolet light B being generated in the extreme ultraviolet
light source system SO.
[0019] Referring to FIG. 2, the extreme ultraviolet light source
system SO may generate the extreme ultraviolet light B having a
wavelength of less than about 100 nm. The extreme ultraviolet light
source system SO may be a laser-produced plasma (LPP) light source
that generates plasma P by irradiating a droplet DP formed of at
least one of tin (Sn), lithium (Li), or xenon (Xe) with laser light
(DL) emitted from a light source unit 30. Further, the extreme
ultraviolet light source system SO according to some embodiments
may use a so-called master oscillator power amplifier (MOPA)
method. That is, the extreme ultraviolet light may be emitted using
the plasma P generated by generating a pre-pulse and a main pulse
using seed laser emitted from the light source unit 30, irradiating
the droplet DP with the pre-pulse to expand the droplet DP, and
then irradiating the droplet DP with the main pulse again.
[0020] In a light source chamber 10 of the extreme ultraviolet
light source system SO, the laser light DL supplied by the light
source unit 30 and droplets DP supplied by a droplet supply unit 20
collide with each other 50,000 or more times per second, thereby
generating the plasma P. A condensing mirror 11A of the light
source chamber 10 may collect the extreme ultraviolet light B
omnidirectionally radiated from the plasma P and concentrate the
collected extreme ultraviolet light B forward, thereby supplying
the extreme ultraviolet light B to the lithography apparatus
LA.
[0021] The lithography apparatus LA may include a plurality of
mirrors and may radiate the extreme ultraviolet light B emitted
from the extreme ultraviolet light source system SO toward the
upper electrostatic chuck 72. The plurality of mirrors included in
the lithography apparatus LA may be conventional ones, which have
known configurations and/or structures, and thus, only two mirrors
61 and 62 are illustrated for simplification of the drawing and
convenience of explanation.
[0022] The projection system PS may include a plurality of mirrors
to irradiate the substrate W disposed on the lower electrostatic
chuck 80 with a pattern of the extreme ultraviolet light B
reflected from the mask 71 attached to the upper electrostatic
chuck 72, thereby exposing a surface of the substrate W with the
pattern. The plurality of mirrors included in the projection system
PS may be conventional ones, which have known configurations and/or
structures, and thus, only two mirrors 63 and 64 are illustrated
for simplification of the drawing and convenience of
explanation.
[0023] Hereinafter, the extreme ultraviolet light source system SO
will be described in detail with reference to FIGS. 2 through
4.
[0024] Referring to FIG. 2, the extreme ultraviolet light source
system SO may include the light source chamber 10, the droplet
supply unit 20, the light source unit 30, and a catcher 40.
Further, the extreme ultraviolet light source system SO may be
controlled by the control unit CON controlling the light exposure
equipment 1.
[0025] The light source unit 30 is a driver light source, and the
laser light DL emitted therefrom may be provided in a form of pulse
waves and may include a pre-pulse and a main pulse. The pre-pulse
may increase a surface area of the droplet DP before the main pulse
is absorbed by and interacts with the droplet DP, thereby improving
conversion efficiency. The conversion efficiency means a ratio of
output power of the emitted extreme ultraviolet light B to input
power of the laser light DL emitted from the light source unit
30.
[0026] The light source chamber 10 may include a lower body 11 that
collects the generated extreme ultraviolet light B, and an upper
body 12 that may be coupled to the lower body 11 and may have a
conical shape. The inside of the light source chamber 10 may be
maintained in an ultra-low pressure state to reduce or possibly
prevent absorption of the generated extreme ultraviolet light B by
gas in the light source chamber 10. Further, the light source
chamber 10 may be filled with, for example, hydrogen (H.sub.2) gas
and/or oxygen (O.sub.2) gas, in an ultra-low pressure state. In
some embodiments, the light source chamber 10 may be filled with
hydrogen gas and oxygen gas at a volume ratio of about
98.8:0.2.
[0027] The condensing mirror 11A that collects the generated
extreme ultraviolet light B toward the upper body 12 may be
disposed in the lower body 11. The condensing mirror 11A may be a
prolate spheroid mirror having a first focal point in a laser light
irradiation region of the droplet DP, or a region adjacent to the
laser light irradiation region, and a second focal point at an
intermediate focus (IF).
[0028] A reflection layer RL1 for improving reflectance of the
extreme ultraviolet light B may be formed on the condensing mirror
11A. The reflection layer RL1 may be implemented by multilayered
thin film in which molybdenum (Mo) and silicon (Si) may be
alternately stacked. A light aperture AP may be disposed at the
center of the condensing mirror 11A to adjust an irradiation amount
of the laser light DL emitted from the light source unit 30.
[0029] The upper body 12 may be a cover having a conical shape
whose width increases upwardly as illustrated in FIG. 2, and the
intermediate focus (IF) that provides a path through which the
generated extreme ultraviolet light B is emitted may be positioned
at an end portion of the conical shape.
[0030] The droplet supply unit 20 for supplying the droplet DP may
be disposed on one side of the upper body 12. The catcher 40 in
which the droplet DP discharged from the droplet supply unit 20 is
accommodated may be disposed on the other side of the upper body
12.
[0031] The droplet supply unit 20 may include a droplet supply
source 21 and a droplet discharge portion 22. The droplet supply
source 21 may supply a target material for forming the droplet DP.
The target material may be a material such as tin (Sn), lithium
(Li), or xenon (Xe), and the droplet DP may be a liquefied form of
the target material or may have a form in which solid particles of
the target materials are contained in a liquid material.
[0032] The target material stored in the droplet supply source 21
may be pressurized to discharge the droplet DP through the droplet
discharge portion 22. The droplet DP may be continuously discharged
through the droplet discharge portion 22 at a speed of, for
example, about 20 to 70 m/s and a time interval of about 20 .mu.s.
The droplet DP may be irradiated with the pre-pulse and the main
pulse after being discharged through the droplet discharge portion
22.
[0033] Referring to FIGS. 2 and 3, the droplet DP may be expanded
in a pancake shape by being irradiated with the pre-pulse, and the
plasma P may be radiated after the expanded droplet DP is
irradiated with the main pulse. The droplet DP irradiated with the
main pulse may explode and may leave debris DD. The debris DD may
be a microdroplet, gas, or a mixture thereof. Such debris DD may
pass through the intermediate focus IF of the upper body 12 by an
ascending air flow AF2 in the light source chamber 10 and may be
attached to the mask 71 of the lithography apparatus LA, and thus
the lithography apparatus LA may be contaminated (see FIG. 1).
[0034] In one example, a transparent cover 53 may be disposed in
front of the intermediate focus IF to reduce or possibly prevent
contamination in the lithography apparatus LA by the debris DD
passing through the intermediate focus IF and scattered. Further, a
nozzle 54 that sprays gas AF1 supplied from a gas source 57 may be
disposed between the intermediate focus IF and the transparent
cover 53 to guide the ascending air flow AF2 of the light source
chamber 10 into an exhausted air flow AF3 that is directed toward
an exhaust pipe 55. Therefore, a flow of the debris DD contained in
the ascending air flow AF2 of the light source chamber 10 may be
guided by the gas AF1, such that the debris DD may be discharged
through the exhaust pipe 55 along the exhausted air flow AF3.
Hereinafter, the transparent cover 53, the nozzle 54, and the
exhaust pipe 55 will be described in detail.
[0035] Referring to FIGS. 3 and 4, a blocking plate 51 may be
disposed in front of the light source chamber 10 so as to intersect
a first optical path DR1 of the extreme ultraviolet light B. The
blocking plate 51 may block the light source chamber 10 and the
lithography apparatus LA from each other and may be provided as a
support on which the transparent cover 53 is disposed. An opening
52 through which the extreme ultraviolet light B is transmitted may
be formed in a region where the blocking plate 51 and the first
optical path DR1 overlap each other. A width W1 of the opening 52
may be sufficient (e.g., wide enough) for the extreme ultraviolet
light B to pass through the opening 52, and the extreme ultraviolet
light B radiated through the intermediate focus IF may be
transmitted through the opening 52 without being blocked by the
blocking plate 51.
[0036] The transparent cover 53 may be disposed on the blocking
plate 51 so as to cover the opening 52. The transparent cover 53
may be disposed on the light source chamber 10, may block the
ascending air flow AF2 discharged from the light source chamber 10,
and may be used as a guide for changing the ascending air flow AF2
into the exhausted air flow AF3.
[0037] The transparent cover 53 may be formed of a transparent
material to allow the extreme ultraviolet light B to pass
therethrough. A width W2 of the transparent cover 53 may be wider
than the width W1 of the opening 52, and thus, the transparent
cover 53 may sufficiently cover the opening 52.
[0038] The transparent cover 53 may include a cover frame 53A and a
transparent thin film layer 53B. The cover frame 53A may fix the
transparent thin film layer 53B and may be formed of a material
such as a metal or a resin. The transparent thin film layer 53B may
be fixed by the cover frame 53A and disposed on the opening 52 of
the blocking plate 51. The transparent thin film layer 53B may be
formed of a material robust enough to block the ascending air flow
AF2 of the light source chamber 10 and through which the extreme
ultraviolet light B may be transmitted. The transparent thin film
layer 53B may be formed of a transparent material through which 90%
or more of extreme ultraviolet light B may be transmitted. For
example, the transparent thin film layer 53B may be implemented by
a single-layer or multilayer structure of a material such as
silicon carbide (SiC) and/or graphene. For example, the transparent
thin film layer 53B may have a thickness T of about 10 nm to about
100 nm. In a case in which the thickness T of the transparent thin
film layer 53B is less than 10 nm, it may be difficult to sustain a
pressure generated by the ascending air flow AF2 of the light
source chamber 10 because of the excessively thin thickness T of
the transparent thin film layer 53B. Further, in a case in which
the thickness T of the transparent thin film layer 53B exceeds 100
nm, the extreme ultraviolet light B transmitted through the
transparent thin film layer 3B may be absorbed, and as a result, a
light quantity of the extreme ultraviolet light B may be
excessively decreased.
[0039] The transparent cover 53 may be separably disposed on the
blocking plate 51, and thus, may be separated and replaced when
damaged or contaminated. In a case in which the transparent thin
film layer 53B or the cover frame 53A of the transparent cover 53
is damaged, the ascending air flow AF2 of the light source chamber
10 may be leaked between the transparent cover 53 and the blocking
plate 51. At this time, the exhausted air flow AF3 passing through
the exhaust pipe 55 is weakened, and thus, an internal pressure of
the exhaust pipe 55 is relatively increased. Therefore, whether or
not the transparent cover 53 is damaged may be checked by
monitoring the internal pressure of the exhaust pipe 55. In some
embodiments, a plurality of transparent covers 53 may be disposed
on the blocking plate 51. In a case in which the number of
transparent covers 53 is plural, when one transparent cover 53 is
damaged or contaminated, the control unit CON may detect the damage
or contamination and may replace the one transparent cover 53 with
another transparent cover 53 that is not damaged or contaminated.
Further, in a case in which the number of transparent covers 53 is
plural, the control unit CON may replace the transparent cover 53
on a predetermined cycle. Such a cycle is calculated in advance and
may be an average period of time within which the transparent cover
53 is contaminated or damaged. In some embodiments, the control
unit CON may replace a first transparent cover 53 with a second
transparent cover 53 upon a predetermined time elapsing.
[0040] The nozzle 54 and the exhaust pipe 55 may be disposed
between the light source chamber 10 and the blocking plate 51. The
nozzle 54 may be disposed so that an end portion 54N may face the
intermediate focus IF and may spray the gas AF1 in a direction
intersecting the first optical path DR1 of the extreme ultraviolet
light B. The gas AF1 sprayed from the nozzle 54 may move along a
first axis (AX) direction intersecting the first optical path DR1
and may guide the ascending air flow AF2 supplied from the light
source chamber 10 to the exhausted air flow AF3 directed to the
exhaust pipe 55. Further, the debris DD contained in the ascending
air flow AF2 may move toward the exhaust pipe 55 along the gas AF1
sprayed from the nozzle 54. The gas AF1 sprayed from the nozzle 54
may have the same composition as that of a major component of the
gas in the light source chamber 10. In some embodiments, the gas
AF1 sprayed from the nozzle 54 may be hydrogen gas. Further, the
gas AF1 sprayed from the nozzle 54 may have a temperature lower
than that of the ascending air flow AF2 of the light source chamber
10. The temperature of the gas AF1 sprayed from the nozzle 54 may
be equal to or lower than a temperature at which the debris DD
contained in the ascending air flow AF2 of the light source chamber
10 is solidified. In some embodiments, in a case in which the
droplet DP is tin (Sn), the temperature of the ascending air flow
AF2 may be about 400 to about 500.degree. C., the temperature of
the gas AF1 sprayed from the nozzle 54 may be about 230.degree. C.
or lower at which the debris DD of the droplet DP is solidified,
for example, about 25 to about 230.degree. C. Therefore, the debris
DD may be solidified by being cooled while passing through the
exhaust pipe 55 and may be easily removed through the exhaust air
flow AF3.
[0041] The exhaust pipe 55 and the nozzle 54 may be disposed to
face each other, such that the gas AF1 sprayed from the nozzle 54
and the ascending air flow AF2 of the light source chamber 10 may
be exhausted. An end portion 55N of the exhaust pipe 55 may be
disposed along the first axis (AX) direction, similarly to the end
portion 54N of the nozzle 54. In some embodiments, the exhaust pipe
55 may be connected to a vacuum source 58 so that gas in a region
adjacent to the intermediate focus IF may be vacuum-sucked.
Therefore, the debris DD contained in the ascending air flow AF2
may be sucked into the exhaust pipe 55 and removed.
[0042] A pressure sensor 56 for measuring an internal pressure may
be disposed in the exhaust pipe 55. The pressure sensor 56 may
measure the internal pressure of the exhaust pipe 55 and transmit a
measurement value to the control unit CON. In a case in which a
pressure value detected by the pressure sensor 56 is increased to a
preset value or more, the control unit CON may determine that the
transparent cover 53 is damaged and may display a determination
result through, for example, a screen or an alarm lamp. Further, in
a case in which the number of transparent covers 53 is plural, the
control unit CON may replace the damaged transparent cover 53 with
another transparent cover.
[0043] The extreme ultraviolet light source system SO having the
above-described configuration may block the ascending air flow AF2
of the light source chamber 10 using the transparent cover 53,
thereby reducing or possibly preventing contamination in the
lithography apparatus LA by the debris DD contained in the
ascending air flow AF2. Further, the nozzle 54 and the exhaust pipe
55 may be disposed between the transparent cover 53 and the light
source chamber 10 to be adjacent to the intermediate focus IF, and
the nozzle 54 may spray the gas AF1 toward the exhaust pipe 55 to
direct the ascending air flow AF2 of the light source chamber 10 to
the exhaust pipe 55. Therefore, the debris DD contained in the
ascending air flow AF2 of the light source chamber 10 may be
discharged through the exhaust pipe 55, thereby reducing or
possibly preventing contamination in the lithography apparatus
LA.
[0044] The transparent cover 53 adopted in the extreme ultraviolet
light source system according to some embodiments will be described
with reference to FIGS. 5 and 6. FIGS. 5 and 6 illustrate a case in
which the number of transparent covers adopted in the extreme
ultraviolet light source system according to some embodiments of
the present invention is plural.
[0045] Referring to FIG. 5, the transparent cover 53 adopted in the
extreme ultraviolet light source system according to some
embodiments may be different in that the transparent cover 53 of
the above-described example is substituted with a transparent cover
replacement unit 153 including a plurality of transparent covers
153-1 to 153-3. The transparent cover replacement unit 153 may
include the plurality of transparent covers 153-1 to 153-3, and the
plurality of transparent covers 153-1 to 153-3 may be movably
disposed on a transfer member 159. In some embodiments, the
transfer member 159 may be a pair of rails 159A and 159B. Although
a case in which the transparent cover replacement unit 153 includes
three transparent covers 153-1 to 153-3 has been described by way
of example, but the number of transparent covers is not limited
thereto, and two or more than three transparent covers may be
provided.
[0046] The control unit CON may control the first to third
transparent covers 153-1 to 153-3 disposed on the transfer member
159 to be sequentially positioned on the opening 52 of the blocking
plate 51. That is, the transparent cover replacement unit 153 may
be moved in a second direction DR2 under the control of the control
unit CON, such that the third transparent cover 153-3, the second
transparent cover 153-2, and the first transparent cover 153-1 are
sequentially positioned on the opening 52. In some embodiments, in
a case in which a pressure value detected by the pressure sensor 56
of the exhaust pipe 55 is increased to a reference value or more,
the control unit CON may drive a driving unit (not illustrated) to
move the first to third transparent covers 153-1 to 153-3 in the
second direction DR2. FIG. 5 illustrates a state where the third
transparent cover 153-3 is damaged or contaminated and thus is
replaced with the second transparent cover 153-2.
[0047] Referring to FIG. 6, a transparent cover replacement unit
253 adopted in the extreme ultraviolet light source system
according to some embodiments may be similar to the above-described
example in that a plurality of transparent covers are included.
However, the plurality of transparent covers are not individually
separate, and a plurality of transparent thin film layers 253B are
disposed in one cover frame 253A. In some embodiments, the
transparent thin film layer 253B may be disposed in each opening of
the circular cover frame 253A having a plurality of openings. In
the above-described example, a plurality of transparent covers are
disposed on a pair of rails and move in one direction. On the other
hand, in this example, a driving unit 254 may be disposed on a
rotation axis C of the circular cover frame 253A to rotate the
circular cover frame 253A in a third direction DR3, such that each
of the plurality of transparent thin film layer 253B is positioned
on the opening 52 of the light source chamber 10. In this case,
when the circular cover frame 253A rotates once, the control unit
CON may display that the circular cover frame 253A needs to be
replaced through, for example, a screen or an alarm lamp.
[0048] As set forth above, according to some embodiments of the
present invention, the extreme ultraviolet light source system, in
which contamination of the mask of the lithography apparatus by
debris from a droplet may be reduced or possibly prevented, may be
provided.
[0049] While some example embodiments have been shown and described
above, it will be apparent to those skilled in the art that
modifications and variations could be made without departing from
the scope of the present invention as defined by the appended
claims.
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