U.S. patent application number 10/340645 was filed with the patent office on 2003-07-24 for device manufacturing-related apparatus, reticle, and device manufacturing method.
This patent application is currently assigned to Canon Kabushiki Kaisha. Invention is credited to Yamamoto, Sumitada.
Application Number | 20030136512 10/340645 |
Document ID | / |
Family ID | 19191267 |
Filed Date | 2003-07-24 |
United States Patent
Application |
20030136512 |
Kind Code |
A1 |
Yamamoto, Sumitada |
July 24, 2003 |
Device manufacturing-related apparatus, reticle, and device
manufacturing method
Abstract
A gas purge space such as a pellicle space is purged with inert
gas within a short time in a projection exposure apparatus using an
ultraviolet ray source such as a fluorine excimer laser as a light
source. The pellicle frame of a reticle (20) with a pellicle is
constituted by porous pellicle frame pieces (30a, 30b). Inert gas
is supplied into a pellicle space (100) via the porous pellicle
frame piece (30a). Inert gas is exhausted together with oxygen and
the like in the pellicle space (100) via the porous pellicle frame
piece (30b).
Inventors: |
Yamamoto, Sumitada;
(Tochigi, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Assignee: |
Canon Kabushiki Kaisha
3-30-2, Shimomaruko, Ohta-ku
Tokyo
JP
|
Family ID: |
19191267 |
Appl. No.: |
10/340645 |
Filed: |
January 13, 2003 |
Current U.S.
Class: |
156/345.26 ;
430/5 |
Current CPC
Class: |
H01L 21/67017 20130101;
G03F 9/7096 20130101; G03F 1/64 20130101; G03F 7/70933 20130101;
G03F 7/70983 20130101 |
Class at
Publication: |
156/345.26 |
International
Class: |
C23F 001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 15, 2002 |
JP |
2002-006740 |
Claims
What is claimed is:
1. A device manufacturing-related apparatus comprising: a holding
mechanism which holds a structure in which a gas purge space to be
purged with inert gas is surrounded by a surrounding member; and a
gas control mechanism which forms a flow of inert gas flowing into
the gas purge space and flowing out from the gas purge space, to
purge the gas purge space with inert gas, wherein the surrounding
member has an inflow portion for allowing said gas control
mechanism to supply inert gas into the gas purge space and an
outflow portion for allowing said gas control mechanism to exhaust
inert gas from the gas purge space, at least one of the inflow
portion and the outflow portion is formed from a porous material
which inert gas permeates, and said gas control mechanism forms the
flow of inert gas in the gas purge space by generating between
inner and outer spaces of the structure a pressure difference large
enough to allow inert gas to permeate the porous material.
2. The apparatus according to claim 1, wherein both of the inflow
portion and the outflow portion are formed from the porous material
which inert gas permeates.
3. The apparatus according to claim 1, wherein the surrounding
member includes a pellicle frame which supports a pellicle film of
a reticle with a pellicle, and the inflow portion and the outflow
portion are formed in the pellicle frame.
4. The apparatus according to claim 3, wherein the inflow portion
and the outflow portion are arranged at positions facing each
other.
5. The apparatus according to claim 3, wherein the structure has a
manifold outside the inflow portion.
6. The apparatus according to claim 5, wherein an inner width of
the manifold is substantially equal to an inner width of the
pellicle frame.
7. The apparatus according to claim 3, wherein the structure has a
manifold outside the outflow portion.
8. The apparatus according to claim 7, wherein an inner width of
the manifold is substantially equal to an inner width of the
pellicle frame.
9. The apparatus according to claim 3, wherein the structure has
manifolds outside the inflow portion and the outflow portion.
10. The apparatus according to claim 9, wherein an inner width of
each manifold is substantially equal to an inner width of the
pellicle frame.
11. The apparatus according to claim 1, wherein said gas control
mechanism comprises a gas supply portion which supplies inert gas
into the gas purge space via the inflow portion, and a gas exhaust
portion which exhausts inert gas from the gas purge space via the
outflow portion.
12. The apparatus according to claim 1, wherein said gas control
mechanism comprises a gas supply portion which supplies inert gas
into the gas purge space via the inflow portion, and inert gas is
supplied from the gas supply portion into the gas purge space via
the inflow portion and directly exhausted outside the gas purge
space via the outflow portion.
13. The apparatus according to claim 1, wherein the device
manufacturing-related apparatus further comprises an optical system
which transmits exposure light for transferring a pattern onto a
substrate, and the structure holds said optical system so as to
surround said optical system.
14. The apparatus according to claim 1, wherein the device
manufacturing-related apparatus is constituted as an exposure
apparatus which transfers a pattern onto a substrate.
15. The apparatus according to claim 4, wherein the device
manufacturing-related apparatus is constituted as a purge apparatus
which purges with inert gas an inner space of the reticle with the
pellicle.
16. The apparatus according to claim 4, wherein the device
manufacturing-related apparatus is constituted as a reticle stocker
which stocks the reticle with the pellicle.
17. The apparatus according to claim 4, wherein the device
manufacturing-related apparatus is constituted as a reticle
inspection apparatus which inspects the reticle with the
pellicle.
18. The apparatus according to claim 4, wherein the device
manufacturing-related apparatus is constituted as a reticle
transfer box for transferring the reticle with the pellicle.
19. A reticle with a pellicle, comprising: a reticle; a pellicle
film; and a pellicle frame which supports said pellicle film so as
to form a space between said reticle and said pellicle film,
wherein said pellicle frame has an inflow portion for supplying
inert gas into the space and an outflow portion for exhausting
inert gas from the space, and at least one of the inflow portion
and the outflow portion is formed from a porous material which
inert gas permeates.
20. The reticle according to claim 19, wherein both of the inflow
portion and the outflow portion are formed from the porous
material.
21. The reticle according to claim 19, wherein the inflow portion
and the outflow portion are arranged at positions facing each
other.
22. The reticle according to claim 19, wherein the entire pellicle
frame is formed from the porous material.
23. A device manufacturing method comprising the step of
manufacturing a device by using a device manufacturing-related
apparatus defined in claim 1.
24. A device manufacturing method of manufacturing a device through
lithography, comprising the step of transferring a pattern onto a
substrate by using a device manufacturing-related apparatus defined
in claim 14 which is constituted as the exposure apparatus.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a device
manufacturing-related apparatus, reticle, and device manufacturing
method.
BACKGROUND OF THE INVENTION
[0002] A manufacturing process for a semiconductor element such as
an LSI or VLSI formed from a micropattern uses a reduction type
projection exposure apparatus for printing and forming by reduction
projection a circuit pattern drawn on a mask onto a substrate
coated with a photosensitive agent. With an increase in the
packaging density of semiconductor elements, demands have arisen
for a smaller pattern line width. The resolution has been increased
for micropatterning by exposure apparatuses along with the
development of a resist process.
[0003] Means for increasing the resolving power of the exposure
apparatus include a method of changing the exposure wavelength to a
shorter one, and a method of increasing the numerical aperture (NA)
of the projection optical system.
[0004] As for the exposure wavelength, a KrF excimer laser with an
oscillation wavelength of 365-nm i-line to recently 248 nm, and an
ArF excimer laser with an oscillation wavelength around 193 nm have
been developed. A fluorine (F.sub.2) excimer laser with an
oscillation wavelength around 157 nm is also under development.
[0005] An ArF excimer laser with a wavelength around ultraviolet
rays, particularly, 193 nm, and a fluorine (F.sub.2) excimer laser
with an oscillation wavelength around 157 nm are known to have an
oxygen (O.sub.2) absorption band around their wavelength band.
[0006] For example, the 157-nm wavelength of the fluorine excimer
laser falls within a wavelength region called a vacuum ultraviolet
region. In this wavelength region, light is greatly absorbed by
oxygen molecules, and hardly passes through the air. Light can only
travel in an environment where the oxygen concentration is fully
decreased. According to reference "Photochemistry of Small
Molecules" (Hideo Okabe, A Wiley-Interscience Publication, 1978, p.
178), the absorption coefficient of oxygen to 157-nm light is about
190 atm.sup.-1cm.sup.-1. This means when 157-nm light passes
through gas at an oxygen concentration of 1% at one atmospheric
pressure, the transmittance per cm is only
T=exp(-190.times.1 cm.times.0.01 atm)=0.150
[0007] Oxygen absorbs light to generate ozone (O.sub.3), and ozone
promotes absorption of light, greatly decreasing the transmittance.
In addition, various products generated by the photochemical
reaction of the laser are deposited on the surface of an optical
element, decreasing the light transmittance in the optical
system.
[0008] A decrease in light quantity prolongs the time necessary for
exposure and decreases the productivity.
[0009] In order to ensure sufficiently high productivity, the
oxygen concentration in the optical path is suppressed to low level
of several ppm order or less by a purge mechanism using inert gas
such as nitrogen in the optical path of the exposure optical system
of a projection exposure apparatus using a far ultraviolet laser
such as an ArF excimer laser or fluorine (F.sub.2) excimer laser as
a light source.
[0010] In addition, a load-lock mechanism is arranged at a coupling
portion between the inside and outside of the exposure apparatus.
When a reticle or wafer is to be externally loaded into the
exposure apparatus, the reticle or wafer is temporarily shielded
from outside air. After the load-lock chamber is purged of the
impurity with inert gas, the reticle or wafer is loaded into the
exposure apparatus.
[0011] FIG. 1 is a sectional view schematically showing an example
of a semiconductor exposure apparatus having a fluorine (F.sub.2)
excimer laser as a light source and a load-lock mechanism.
[0012] In FIG. 1, reference numeral 1 denotes a reticle stage for
setting a reticle bearing a pattern; 2, a projection optical system
for projecting the pattern on the reticle serving as a master onto
a wafer serving as a photosensitive substrate; 3, a wafer stage
which supports the wafer and is driven in the X, Y, Z, .theta., and
tilt directions; 4, an illumination optical system for illuminating
the reticle with illumination light; 5, a guide optical system for
guiding light from the light source to the illumination optical
system 4; 6, a fluorine (F.sub.2) excimer laser serving as a light
source; 7, a masking blade for cutting off exposure light so as not
to illuminate the reticle except the pattern region; 8 and 9,
housings which cover the exposure optical path around the reticle
stage 1 and wafer stage 3, respectively; 10, an He air-conditioner
for adjusting the interiors of the projection optical system 2 and
illumination optical system 4 to a predetermined He atmosphere; 11
and 12, N.sub.2 air-conditioners for adjusting the interiors of the
housings 8 and 9 to a predetermined N.sub.2 atmosphere; 13 and 14,
reticle load-lock chambers and wafer load-lock chambers used to
load a reticle and wafer into the housings 8 and 9, respectively;
15 and 16, a reticle hand and wafer hand for transferring the
reticle and wafer, respectively; 17, a reticle alignment mark used
to adjust the reticle position; 18, a reticle stocker for stocking
a plurality of reticles in the housing 8; and 19, a pre-alignment
unit for pre-aligning the wafer. If necessary, the overall
apparatus is stored in an environment chamber (not shown). Air
controlled to a predetermined temperature is circulated within the
environment chamber to keep the internal temperature of the chamber
constant.
[0013] In general, a reticle is equipped with a pattern protection
device called a pellicle. The pellicle prevents deposition of a
foreign matter such as dust onto a reticle pattern surface, and
suppresses the occurrence of defects caused by transfer of a
foreign matter onto a wafer.
[0014] FIG. 2 is a schematic view showing the structure of a
reticle with a pellicle. A pellicle 21 is adhered to the pattern
surface of a reticle 20 with an adhesive agent or the like. The
pellicle 21 is made up of a frame 22 large enough to surround the
reticle pattern, and a pellicle film 23 which is adhered to one end
face of the frame 22 and transmits exposure light. If a space (to
be referred to as a pellicle space hereinafter) defined by the
pellicle 21 and reticle 20 is completely closed, the pellicle film
may expand or contract due to the difference in atmospheric
pressure between the inside and outside of the pellicle space or
the difference in oxygen concentration. To prevent this, a vent
hole 24 is formed in the pellicle frame 22 so as to allow gas to
flow between the inside and outside of the pellicle space. An
auto-screen filter (not shown) is attached to the ventilation path
in order to prevent an external foreign matter from entering the
pellicle space via the vent hole 24.
[0015] FIG. 3 is a schematic view showing an example of a reticle
transfer path in the exposure apparatus shown in FIG. 1.
[0016] In FIG. 3, reference numeral 25 denotes a foreign matter
inspection device which measures the size and number of foreign
matters such as dust deposited on a reticle surface or pellicle
film surface. The reticle 20 is loaded manually or by a transfer
device (not shown) into the reticle load-lock chamber 13 serving as
the entrance of the exposure apparatus. Since the reticle and
pellicle are generally adhered outside the exposure apparatus, the
pellicle 21 has already been adhered to the loaded reticle 20. The
interior of the reticle load-lock chamber 13 is purged with inert
gas until the interior reaches an inert gas atmosphere similarly to
the housing 8. After that, the reticle 20 is transferred by the
reticle hand 15 to any one of the reticle stage 1, reticle stocker
18, and foreign matter inspection device 25.
[0017] As described above, an exposure apparatus using ultraviolet
rays, particularly, an ArF excimer laser beam or fluorine (F.sub.2)
excimer laser beam suffers large absorption of exposure light by
oxygen and moisture. To obtain a sufficient transmittance and
stability of ultraviolet rays, the oxygen and moisture
concentrations in the optical path are reduced and maintained. For
this purpose, a load-lock mechanism is arranged at a coupling
portion between the inside and outside of the exposure apparatus.
When a reticle or wafer is to be externally loaded, the reticle or
wafer is temporarily shielded from outside air. After the load-lock
mechanism is purged of impurity with inert gas, the reticle or
wafer is loaded into the exposure apparatus.
[0018] A reticle loaded into the load-lock chamber bears a
pellicle, and the pellicle space can communicate with outside air
only through a relatively small vent hole. This structure prolongs
a time required to complete purge in the pellicle space even after
the interior of the reticle load-lock chamber reaches a
predetermined inert gas concentration, degrading the
productivity.
[0019] To prevent this problem, Japanese Patent Laid-Open No.
9-73167 discloses an invention of adhering a reticle and pellicle
in advance in an inert gas atmosphere and filling the pellicle
space with inert gas at an oxygen concentration of 1% or less.
However, the transmittance of 157-nm light is merely 15% per cm in
atmospheric-pressure gas at an oxygen concentration of 1%. At
present, the air gap between the reticle and the pellicle film is
about 6 mm. Even if this space is filled with gas at an oxygen
concentration of 0.1%, the transmittance of 157-nm light in the
space is merely 89.2%. The total space distance of an optical path
from the light source of the exposure apparatus to a wafer exceeds
at least 1 m. To ensure a transmittance of 80% or more in the 1-m
space, the oxygen concentration must be suppressed to 10 ppm or
less in the entire optical path. The oxygen concentration is
ideally 1 ppm or less. In the pellicle space, the oxygen
concentration must be 1 to 100 ppm or less in terms of the balance
with another space and maintenance of the transmittance in the
total space distance. This also applies to the moisture and carbon
dioxide gas concentrations.
[0020] The time required for inert gas purge in the pellicle space
in exchanging reticles increases the standby time of the overall
apparatus and influences the productivity. Purge of the pellicle
space with inert gas is desirably performed within as short a time
as possible. Regarding the pellicle function, dust must be
prevented from entering the pellicle space during gas purge.
Japanese Patent Laid-Open No. 2001-133960 proposes a method of
purging the interior of the pellicle space with inert gas through
gas inflow and outflow holes formed in the pellicle frame after the
pellicle is adhered. However, the method disclosed in Japanese
Patent Laid-Open No. 2001-133960 suffers a long purge time due to
stagnation generated near the inlet hole or at the corner of the
pellicle space where gas hardly flows.
SUMMARY OF THE INVENTION
[0021] The present invention has been made in consideration of the
above situation, and has as its object to reduce, e.g., the
nonuniformity and stagnation of the inert gas flow in a gas purge
space to be purged with inert gas, and shorten the purge time in
the gas purge space.
[0022] According to the first aspect of the present invention,
there is provided a device manufacturing-related apparatus
comprising a holding mechanism which holds a structure in which a
gas purge space to be purged with inert gas is surrounded by a
surrounding member, and a gas control mechanism which forms a flow
of inert gas flowing into the gas purge space and flowing out from
the gas purge space, to purge the gas purge space with inert gas,
wherein the surrounding member has an inflow portion for allowing
the gas control mechanism to supply inert gas into the gas purge
space and an outflow portion for allowing the gas control mechanism
to exhaust inert gas from the gas purge space, at least one of the
inflow portion and the outflow portion is formed from a porous
material which inert gas permeates, and the gas control mechanism
forms the flow of inert gas in the gas purge space by generating
between inner and outer spaces of the structure a pressure
difference large enough to allow inert gas to permeate the porous
material.
[0023] According to a preferred aspect of the present invention,
both of the inflow portion and the outflow portion are preferably
formed from the porous material which inert gas permeates.
[0024] According to another preferred aspect of the present
invention, it is preferable that the surrounding member include a
pellicle frame which supports a pellicle film of a reticle with a
pellicle, and the inflow portion and the outflow portion be formed
in the pellicle frame. In this case, the inflow portion and the
outflow portion are preferably arranged at positions facing each
other.
[0025] According to still another preferred aspect of the present
invention, the structure preferably has a manifold outside the
inflow portion, and an inner width of the manifold is preferably
substantially equal to an inner width of the pellicle frame.
[0026] According to still another preferred aspect of the present
invention, the structure preferably has a manifold outside the
outflow portion, and an inner width of the manifold is
substantially equal to an inner width of the pellicle frame.
[0027] According to still another preferred aspect of the present
invention, the gas control mechanism preferably comprises a gas
supply portion which supplies inert gas into the gas purge space
via the inflow portion, and a gas exhaust portion which exhausts
inert gas from the gas purge space via the outflow portion.
[0028] According to still another preferred aspect of the present
invention, it is preferable that the gas control mechanism comprise
a gas supply portion which supplies inert gas into the gas purge
space via the inflow portion, and inert gas be supplied from the
gas supply portion into the gas purge space via the inflow portion
and directly exhausted outside the gas purge space via the outflow
portion.
[0029] According to still another preferred aspect of the present
invention, it is preferable that the device manufacturing-related
apparatus further comprise an optical system which transmits
exposure light for transferring a pattern onto a substrate, and the
structure hold the optical system so as to surround the optical
system.
[0030] The device manufacturing-related apparatus can be
constituted as, e.g., an exposure apparatus which transfers a
pattern onto a substrate, a purge apparatus which purges with inert
gas an inner space of the reticle with the pellicle, a reticle
stocker which stocks the reticle with the pellicle, a reticle
inspection apparatus which inspects the reticle with the pellicle,
or a reticle transfer box for transferring the reticle with the
pellicle.
[0031] According to the second aspect of the present invention,
there is provided a reticle with a pellicle, comprising a reticle,
a pellicle film, and a pellicle frame which supports the pellicle
film so as to form a space between the reticle and the pellicle
film, wherein the pellicle frame has an inflow portion for
supplying inert gas into the space and an outflow portion for
exhausting inert gas from the space, and at least one of the inflow
portion and the outflow portion is formed from a porous material
which inert gas permeates.
[0032] According to still another aspect of the present invention,
both of the inflow portion and the outflow portion are preferably
formed from the porous material.
[0033] According to still another aspect of the present invention,
the inflow portion and the outflow portion are preferably arranged
at positions facing each other.
[0034] According to still another aspect of the present invention,
the entire pellicle frame may be formed from the porous
material.
[0035] According to the third aspect of the present invention,
there is provided a device manufacturing method comprising
manufacturing a device by using the above-described device
manufacturing-related apparatus.
[0036] According to the fourth aspect of the present invention,
there is provided a device manufacturing method of manufacturing a
device through lithography, comprising the step of transferring a
pattern onto a substrate by using the above-described device
manufacturing-related apparatus which is constituted as the
exposure apparatus and applied to the exposure apparatus.
[0037] Other features and advantages of the present invention will
be apparent from the following description taken in conjunction
with the accompanying drawings, in which like reference characters
designate the same or similar parts throughout the figures
thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate embodiments of
the invention and, together with the description, serve to explain
the principles of the invention.
[0039] FIG. 1 is a sectional view showing the schematic arrangement
of an exposure apparatus according to a preferred embodiment of the
present invention;
[0040] FIG. 2 is a schematic view showing the structure of a
reticle with a pellicle;
[0041] FIG. 3 is a schematic view showing an example of a reticle
transfer path in the exposure apparatus shown in FIG. 1;
[0042] FIGS. 4 to 6 are views showing the schematic arrangement of
a purge mechanism (gas purge apparatus) according to the first
embodiment of the present invention;
[0043] FIGS. 7 and 8 are views showing the schematic arrangement of
a purge mechanism (gas purge apparatus) according to the second
embodiment,of the present invention;
[0044] FIGS. 9 to 11 are views showing the schematic arrangement of
a purge mechanism (gas purge apparatus) according to the third
embodiment of the present invention;
[0045] FIG. 12 is a view schematically showing part (light source
lens system) of an exposure apparatus according to the fourth
embodiment of the present invention;
[0046] FIG. 13 is a flow chart showing the flow of the whole
manufacturing process of a semiconductor device; and
[0047] FIG. 14 is a flow chart showing the detailed flow of a wafer
process.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0048] An exposure apparatus according to preferred embodiments of
the present invention is related to an exposure apparatus in which
ultraviolet rays are used as exposure light, the interior of the
exposure apparatus is purged with inert gas, and a mask pattern is
projected onto a photosensitive substrate via a projection optical
system. Ultraviolet rays as exposure light are preferably, e.g.,
far ultraviolet rays, particularly, an ArF excimer laser beam with
a wavelength around 193 nm or a fluorine (F.sub.2) excimer laser
beam with a wavelength around 157 nm.
[0049] Preferred embodiments of the present invention will be
described below with reference to the accompanying drawings.
[0050] [First Embodiment]
[0051] FIGS. 4 to 6 are views showing the schematic arrangement of
a purge mechanism (gas purge apparatus) according to the first
embodiment of the present invention. This purge mechanism purges
the pellicle space with inert gas. The purge mechanism can be
applied to any exposure apparatus which uses a reticle with a
pellicle, and can also be applied to a reticle stocker, reticle
inspection apparatus, reticle transfer box, and the like. In other
words, the present invention can be applied to various device
manufacturing-related apparatuses which use, process, or inspect a
reticle with a pellicle.
[0052] An airtight chamber 26 shown in FIGS. 4 to 6 corresponds to
a housing 8 which stores a reticle stage 1 or reticle stocker 18,
or a reticle load-lock chamber 13 in FIG. 1. Inert gas is
introduced via an inert gas supply port 27, and exhausted via an
inert gas exhaust port 28. As a result, the interior of the
airtight chamber 26 is purged with inert gas.
[0053] A reticle support table 29 is arranged in a reticle transfer
path in the housing 8 of FIG. 1. A reticle 20 to which a pellicle
21 is adhered is set at a predetermined position on the support
table 29 manually or by a reticle hand (not shown: e.g., 15 in FIG.
3) or a transfer robot (not shown) arranged outside the airtight
chamber 26. If necessary, the support table 29 may have a chucking
groove for chucking and fixing a reticle.
[0054] In the first embodiment, a pellicle frame 30 is constituted
by four pellicle frame pieces 30a to 30d. The pellicle frame pieces
30a and 30b are made of a porous material (e.g., graphite or
ceraphite), whereas the pellicle frame pieces 30c and 30d are made
of an unporous material. In FIGS. 4 to 6, the pellicle frame piece
30a is used as the gas supply side (gas inflow portion), and the
pellicle frame piece 30b is used as the gas exhaust side (gas
outflow portion). The pellicle frame pieces 30a and 30b are
arranged on opposite positions (sides). Manifolds 31a and 31b are
respectively attached to the pellicle frame pieces 30a and 30b. The
space widths (vertical widths in FIG. 6) in the manifolds 31a and
31b preferably almost coincide with the width (vertical width in
FIG. 6) in the pellicle space 100. This can effectively reduce
stagnation of the gas flow.
[0055] An inert gas supply joint 33a is arranged near a position
where the manifold 31a is to be arranged, in order to supply inert
gas into a pellicle space (space defined by the reticle 20,
pellicle frame 30, and pellicle film 21) 100 serving as a gas purge
space. An inert gas exhaust joint 33b is arranged near a position
where the manifold 31b is to be arranged, in order to exhaust gas
from the pellicle space 100. Driving mechanisms 34a and 34b move
the inert gas supply and exhaust joints 33a and 33b closer to or
apart from the manifolds 31a and 31b. To ensure the closeness,
i.e., to prevent the inflow/outflow of gas via contact portions
between the manifolds 31a and 31b and the inert gas supply and
exhaust joints 33a and 33b, the manifolds 31a and 31b have O-rings
32a and 32b.
[0056] FIG. 5 is a view schematically showing a state in which
inert gas is supplied into the pellicle space 100 while the driving
mechanisms 34a and 34b bring the inert gas supply and recovery
joints 33a and 33b into tight contact with the manifolds 31a and
31b.
[0057] FIG. 6 is a view when the state in FIG. 5 is viewed from
below, and shows the positional relationship between the reticle
20, the pellicle frame pieces 30a to 30d, the gas supply joint 33a,
and the gas exhaust joint 33b.
[0058] In FIG. 6, the porous pellicle frame pieces 30a and 30b are
arranged on the two, right and left sides of the pellicle frame.
Further, the manifolds 31a and 31b for pressurizing/depressurizing
the pellicle space 100, the inert gas supply joint 33a for
supplying gas into the manifold 31a, and the inert gas exhaust
joint 33b for exhausting gas from the manifold 31b are arranged.
The inert gas supply joint 33a communicates with a path 35a for
supplying inert gas. A positive pressure regulator 36a for
adjusting the interior of the manifold 31a to a desired positive
pressure is inserted midway along the path 35a. The inert gas
exhaust joint 33b communicates with a path 35b for exhausting gas.
A negative pressure regulator 36b for adjusting the interior of the
manifold 31b to a desired negative pressure is inserted midway
along the path 35b.
[0059] The positive pressure regulator 36a, path 35a, inert gas
supply joint 33a, inert gas exhaust joint 33b, path 35b, and
negative pressure regulator 36b can function as a gas control
mechanism which controls the flow of inert gas flowing into the
pellicle space 100 and while being mixed with gas such as oxygen in
the pellicle space 100, flowing from the pellicle space 100.
[0060] The process of purging the pellicle space 100 with inert gas
will be explained with reference to FIGS. 4 to 6.
[0061] The reticle 20 to which the pellicle 21 is adhered is set at
a predetermined position on the reticle support table 29 manually
or by a reticle hand or transfer robot (not shown).
[0062] The inert gas supply and exhaust joints 33a and 33b are
connected by the driving mechanisms 34a and 34b to the manifolds
31a and 31b adhered to the porous pellicle frame pieces 30a and 30b
so as to press the inner sides of the O-rings 32a and 32b. The
supply joint 33a and exhaust joint 33b are respectively connected
to an inert gas supply apparatus and inert gas suction apparatus
(neither is shown) via the supply path 35a and exhaust path 35b.
Simultaneously when inert gas is blown into the pellicle space 100,
gas in the pellicle space 100 is sucked and exhausted outside the
airtight chamber 26.
[0063] Blown inert gas has passed through the porous pellicle frame
piece 30a, and thus flows from the pellicle frame piece 30a to the
facing pellicle frame piece 30b at a uniform flow rate per unit
area. Inert gas is exhausted outside the pellicle space 100 while
kept uniform via the porous exhaust pellicle frame piece 30b. While
inert gas is efficiently mixed with oxygen, moisture, or other
impurities present in the pellicle space without any flow
stagnation, inert gas is sucked outside via the exhaust manifold
31b formed in the exhaust-side porous pellicle frame piece 30b,
completing gas purge in the pellicle space within a short time.
[0064] Gas hardly permeates the porous material in the absence of
any pressure difference between spaces on the two sides. Even if
the supply and exhaust joints 33a and 33b are removed from the
manifolds 31a and 31b after inert gas purge, the pellicle space 100
exhibits the same behavior as a closed space and maintains the
inert gas concentration of the pellicle space 100 during a short
time until the reticle 20 with the pellicle is transferred to the
stage. The porous material as the pellicle frame pieces 30a and 30b
serves as a filter, and can prevent the inflow of dust into the
pellicle space 100. Note that a particle prevention or chemical
contamination prevention filter may be inserted midway along the
path for supplying gas to the pellicle frame piece 30a.
[0065] The inert gas supply and exhaust joints 33a and 33b as shown
in FIGS. 4 to 6 can also be arranged in the reticle stocker 18 (see
FIG. 1). In this case, inert gas purge in the pellicle space is not
executed in the reticle load-lock chamber 13 for a reticle which is
externally loaded into the exposure apparatus, and is not used for
exposure at once but is temporarily stocked in the reticle stocker
18. Instead, the reticle is loaded into a predetermined slot of the
reticle stocker 18 where the joint is arranged, and then inert gas
purge in the pellicle space can be executed in the stocker.
Accordingly, a satisfactory purge time can be ensured to decrease
the inert gas concentration in the pellicle space to a low level in
advance. In addition, the inert gas purge time in the reticle
load-lock chamber 13 can be further shortened or omitted.
[0066] The location where the purge mechanism including the inert
gas supply and exhaust joints is arranged is not limited to the
reticle stage, reticle stocker, or reticle load-lock chamber. The
purge mechanism can be arranged at various locations, e.g., inside
a pellicle inspection apparatus or in a reticle transfer path
within a closed chamber. When the purge mechanism is arranged
midway along the transfer path, the reticle need not be transferred
to a purge mechanism outside the transfer path, shortening the
transfer time in the whole exposure apparatus and increasing the
productivity. The purge mechanism location is not limited to one,
but purge mechanisms can be arranged at a plurality of portions,
and automatically select and execute inert gas purge at an optimal
location suitable for a reticle use plan.
[0067] [Second Embodiment]
[0068] FIGS. 7 and 8 are views showing the schematic arrangement of
a purge mechanism (gas purge apparatus) according to the second
embodiment of the present invention. FIG. 7 is a schematic
sectional view when the purge mechanism is viewed from the lateral
direction. FIG. 8 is a view when the purge mechanism in FIG. 7 is
viewed from below. This purge mechanism purges the pellicle space
with inert gas. The purge mechanism can be applied to any exposure
apparatus which uses a reticle with a pellicle, and can also be
applied to a reticle stocker, reticle inspection apparatus, reticle
transfer box, and the like. That is, the present invention can be
applied to various device manufacturing-related apparatuses which
use, process, or inspect a reticle with a pellicle. The same
reference numerals as in the first embodiment denote the same
parts. The first embodiment applies to matters which will not be
mentioned in the second embodiment.
[0069] In the first embodiment, portions (two sides out of four
sides) of the pellicle frame are made of a porous material. The
spaces in manifolds connected to the pellicle frame portions are
pressurized/depressurized, supplying inert gas into the pellicle
space and exhausting gas from the pellicle space. In the second
embodiment, the entire pellicle frame is made of a porous material.
While the inert gas supply side (inflow side) is pressurized, the
outflow side is not depressurized. More specifically, in the second
embodiment, inert gas is supplied into the pellicle space via a
very small portion (inflow portion) of the pellicle frame, and
exhausted from the pellicle space via the remaining portion
(outflow portion) of the pellicle frame.
[0070] The second embodiment will be described in more detail with
reference to FIGS. 7 and 8. In the second embodiment, a driving
mechanism 34a connects an inert gas supply joint 33a via an O-ring
32a to a manifold 31a arranged at a portion (inflow portion) of a
pellicle frame 30. After the inert gas supply joint 33a is
connected, pressurized inert gas is supplied into a pellicle space
100 via the inert gas supply joint 33a. As shown in FIG. 8, the
inert gas supply manifold 31a is adhered to a very small portion
(inflow portion) of the pellicle frame 30. When the interior of the
manifold 31a is pressurized by inert gas, only this portion of the
pellicle frame 30 functions as an inert gas inflow portion 30e, and
the remaining portion of the pellicle frame functions as an inert
gas outflow portion 30f.
[0071] Inert gas having passed through the inflow portion 30e of
the pellicle frame 30 radially flows toward the outflow portion 30f
of the pellicle frame 30. Inert gas flows out from the outflow
portion 30f to the pellicle frame at a predetermined flow rate per
area because of the nature of the porous material. Outflow gas is
exhausted outside an airtight chamber 26 together with other gases
in the airtight chamber 26 via an inert gas exhaust line 28.
[0072] To make gas permeate the porous material, the pressure
difference must be given to a certain degree on the two sides of
the porous material because of a high pipe resistance of the porous
material. In the second embodiment, the outside of the gas exhaust
porous material 30f is at the atmospheric pressure. Gas does not
permeate the porous material unless the internal pressure of the
pellicle space 100 is set higher than the atmospheric pressure by
the pressure difference or more. To the contrary, the pressure
resistance of a pellicle film 21 is low. Considering this, the
second embodiment increases the area of the porous material which
constitutes the outflow portion 30f, thereby supplying nitrogen
into the pellicle space with a small pressure difference.
[0073] In the first embodiment, gas is forcibly exhausted from the
pellicle space by setting a negative pressure outside the pellicle
space. In the second embodiment, compared to the first embodiment,
the flow rate of inert gas which can be supplied into the pellicle
space and exhausted from it is low. In the second embodiment, the
gas purge time is longer than that in the first embodiment because
the distance from the inflow portion 30e (corresponding to the
pellicle frame piece 30a in the first embodiment) for supplying
inert gas into the pellicle frame to the outflow portion 30f
(corresponding to the pellicle frame piece 30b in the first
embodiment) for exhausting gas from the pellicle space is not the
same between all portions, unlike the first embodiment. However,
according to the second embodiment, any outflow-side manifold can
be eliminated, and the pellicle frame itself can be made of a
single material. The second embodiment is, therefore, superior to
the first embodiment in that the outflow-side gas exhaust mechanism
can be eliminated to simplify the purge mechanism and reduce the
purge mechanism manufacturing cost. Further, the second embodiment
is superior to the first embodiment in that the structure of a
reticle with a pellicle is simple and can be easily formed and thus
the manufacturing cost of the reticle with the pellicle can be
reduced.
[0074] The disadvantage of the second embodiment results from
forming the whole pellicle frame from a porous material and keeping
the gas outflow side at the atmospheric pressure. To prevent this,
the gas outflow side may be adjusted to a negative pressure to
increase the gas inflow/outflow amount in the second embodiment,
similar to the first embodiment. It is also possible to seal, with
a sealing material, porous material portions on the two, upper and
lower sides of the pellicle frame shown in FIG. 8, arrange a gas
outflow manifold 31b on one left side, similar to the first
embodiment, adjust the interior of the manifold 31b to a negative
pressure, and exhaust gas.
[0075] [Third Embodiment]
[0076] FIGS. 9 to 11 are views showing the schematic arrangement of
a purge mechanism (gas purge apparatus) according to the third
embodiment of the present invention. More specifically, FIG. 9 is a
schematic view when the purge mechanism is viewed from the lateral
direction. FIG. 10 is a view showing a state in which inert gas is
supplied into the pellicle space by the purge mechanism shown in
FIG. 9. FIG. 11 is a view when the purge mechanism in FIG. 10 is
viewed from below. The same reference numerals as in the first
embodiment denote the same parts. The first embodiment applies to
matters which will not be mentioned in the third embodiment.
[0077] In the third embodiment, porous members 30a and 30b are
arranged outside a pellicle frame 22 having vent holes 24, and
manifolds 31a and 31b are arranged outside the porous members 30a
and 30b. More specifically, in the third embodiment, the vent holes
24 are formed on two facing sides of the pellicle frame 22 made of
an unporous material. The porous members 30a and 30b are arranged
outside these two sides, and the manifolds 31a and 31b are arranged
outside the two porous members 30a and 30b.
[0078] The process of purging a pellicle space 100 with inert gas
will be explained with reference to FIGS. 9 to 11.
[0079] A reticle 20 to which a pellicle 21 is adhered is set at a
predetermined position on a reticle support table 29 manually or by
a reticle hand or transfer robot (not shown).
[0080] Inert gas supply and exhaust joints 33a and 33b are
connected by driving mechanisms 34a and 34b via O-rings 32a and 32b
to the manifolds 31a and 31b adhered to the porous members 30a and
30b. The supply joint 33a and exhaust joint 33b are respectively
connected to an inert gas supply apparatus and inert gas suction
apparatus (neither is shown) via a supply path 35a and exhaust path
35b. Simultaneously when inert gas is blown into the pellicle space
100, gas in the pellicle space 100 is sucked and exhausted outside
the airtight chamber 26.
[0081] Gas hardly permeates the porous material in the absence of
any pressure difference between spaces on the two sides. Even if
the supply and exhaust joints 33a and 33b are removed from the
manifolds 31a and 31b after inert gas purge, the pellicle space 100
exhibits the same behavior as a closed space and maintains the gas
concentration of the pellicle space 100 during a short time until
the reticle 20 with the pellicle is transferred to the stage. The
porous members 30a and 30b serve as a filter, and can prevent the
inflow of dust into the pellicle space 100. Note that a particle
prevention or chemical contamination prevention filter may be
inserted midway along the path for supplying gas to the porous
member 30a.
[0082] The third embodiment can fabricate a reticle with a pellicle
by, e.g., adhering porous members to the outer surface of the
four-side pellicle frame having vent holes. The reticle with the
pellicle can be manufactured more easily than the first embodiment
in which porous and unporous materials are coupled to constitute a
four-side pellicle frame. That is, the third embodiment simplifies
the pellicle frame fabrication process.
[0083] [Fourth Embodiment]
[0084] An application of the purge mechanism according to the
present invention to the light source lens system of an exposure
apparatus will be described as the fourth embodiment of the present
invention. FIG. 12 is a view schematically showing part (light
source lens system) of the exposure apparatus according to the
fourth embodiment of the present invention. The same reference
numerals as in the first embodiment denote the same parts. The
first embodiment applies to matters which will not be mentioned in
the fourth embodiment.
[0085] The light source lens system is constituted by optical
elements such as many lenses 37a and 37b and a mirror 38. The light
source lens system illuminates an illumination region on a reticle
with a laser beam from the light source at a uniform illuminance.
These optical components are incorporated in a housing 39. The
interior of the housing 39 is purged with high-concentration inert
gas via an inert gas supply line 27 and inert gas exhaust line 28.
When the housing 39 is open for maintenance or the like, outside
air flows into the housing 39. To operate the exposure apparatus
again, the interior of the housing 39 must be purged of outside air
with inert gas. When the housing 39 incorporates optical
components, spaces between the lenses 37a to 37c held in a lens
holding structure 40 held at a predetermined position by a holding
mechanism 42 in the housing 39 are half-sealed. Inert gas hardly
flows to this portion, and gas purge is not performed.
[0086] To prevent this, a purge mechanism which supplies inert gas
into a purge space via a porous material is assembled into the lens
holding structure 40 in the fourth embodiment, similar to the first
to third embodiments.
[0087] More specifically, in the fourth embodiment, as shown in
FIG. 12, a porous member 30a for supplying inert gas is arranged on
the wall (e.g., inner wall) of the lens holding structure 40. Part
of the lens holding structure 40 is processed into a manifold
shape. Pressurized gas is supplied through an inert gas supply path
35a, and inert gas is supplied to the inter-lens space via the
porous member 30a. Inert gas supplied into the inter-lens space has
passed through the porous member 30a, and thus flows toward a
facing surface (left side in FIG. 12) with high uniformity in the
plane direction of the porous member 30a. Gas in the inter-lens
space is exhausted outside the lens holding structure 40 via
exhaust holes 41 formed in the facing surface. While inert gas is
efficiently mixed with oxygen, moisture, or other impurities
present in the inter-lens space without any stagnation, inert gas
can be exhausted outside via the exhaust holes 41, completing gas
purge in the inter-lens space within a short time.
[0088] Even if the inert gas concentration in the purge space
(inter-lens space) decreases owing to maintenance or the like, the
standby time of the exposure apparatus until the inert gas
concentration increases can be shortened. The fourth embodiment has
exemplified the light source lens system. The method of supplying
inert gas using a porous material is not limited to the light
source lens system, and can be applied to purge of a purge space in
all optical components such as a projection lens system and
measurement lens system, and other mechanisms.
[0089] [Device Manufacturing Method]
[0090] A semiconductor device manufacturing process using the
above-described exposure apparatus will be explained. FIG. 13 is a
flow chart showing the flow of the whole manufacturing process of a
semiconductor device. In step 1 (circuit design), a semiconductor
device circuit is designed. In step 2 (mask formation), a mask is
formed based on the designed circuit pattern. In step 3 (wafer
formation), a wafer is formed using a material such as silicon. In
step 4 (wafer process) called a pre-process, an actual circuit is
formed on the wafer by lithography using the mask and wafer. Step 5
(assembly) called a post-process is the step of forming a
semiconductor chip by using the wafer formed in step 4, and
includes an assembly process (dicing and bonding) and packaging
process (chip encapsulation). In step 6 (inspection), the
semiconductor device manufactured in step 5 undergoes inspections
such as an operation confirmation test and durability test. After
these steps, the semiconductor device is completed and shipped
(step 7).
[0091] FIG. 14 is a flow chart showing the detailed flow of the
wafer process. In step 11 (oxidation), the wafer surface is
oxidized. In step 12 (CVD), an insulating film is formed on the
wafer surface. In step 13 (electrode formation), an electrode is
formed on the wafer by vapor deposition. In step 14 (ion
implantation), ions are implanted in the wafer. In step 15 (resist
processing), a photosensitive agent is applied to the wafer. In
step 16 (exposure), the above-described exposure apparatus
transfers a circuit pattern onto the wafer. In step 17
(developing), the exposed wafer is developed. In step 18 (etching),
the resist is etched except the developed resist image. In step 19
(resist removal), an unnecessary resist after etching is removed.
These steps are repeated to form multiple circuit patterns on the
wafer.
[0092] As described above, according to preferred embodiments of
the present invention, inert gas purge in the pellicle space of a
reticle with a pellicle loaded into the apparatus can be
efficiently performed within a short time in a projection exposure
apparatus using an ultraviolet ray source such as a fluorine
excimer laser as a light source.
[0093] Even when the closed inert gas purge space is broken for
maintenance or adjustment, the purge space can be returned to a
necessary purge level within a short time, shortening the standby
time of the apparatus.
[0094] This realizes high-precision, stable exposure amount control
without decreasing the productivity of the exposure apparatus, and
a fine circuit pattern can be efficiently, stably projected onto a
substrate.
[0095] The present invention can reduce, e.g., the nonuniformity
and stagnation of the inert gas flow in a gas purge space to be
purged with inert gas, and shorten the purge time in the gas purge
space.
[0096] As many apparently widely different embodiments of the
present invention can be made without departing from the spirit and
scope thereof, it is to be understood that the invention is not
limited to the specific embodiments thereof except as defined in
the claims.
* * * * *