U.S. patent application number 11/376240 was filed with the patent office on 2006-09-21 for device manufacturing apparatus and method of controlling same.
This patent application is currently assigned to CANON KABUSHIKI KAISHA. Invention is credited to Yuichi Takamura.
Application Number | 20060207680 11/376240 |
Document ID | / |
Family ID | 37009066 |
Filed Date | 2006-09-21 |
United States Patent
Application |
20060207680 |
Kind Code |
A1 |
Takamura; Yuichi |
September 21, 2006 |
Device manufacturing apparatus and method of controlling same
Abstract
An apparatus for processing an article in order to manufacture a
device includes a process chamber in which the article is
processed; a relay chamber; a first load-lock chamber disposed
between an outside of the apparatus and the relay chamber; a second
load-lock chamber disposed between the relay chamber and the
process chamber; a first adjusting mechanism configured to adjust
atmosphere in the process chamber to a first atmosphere; and a
second adjusting mechanism configured to adjust atmosphere in the
relay chamber to a second atmosphere that is an intermediate
atmosphere between the first atmosphere and atmosphere of the
outside.
Inventors: |
Takamura; Yuichi;
(Utsunomiya-shi, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Assignee: |
CANON KABUSHIKI KAISHA
Tokyo
JP
|
Family ID: |
37009066 |
Appl. No.: |
11/376240 |
Filed: |
March 16, 2006 |
Current U.S.
Class: |
141/98 |
Current CPC
Class: |
H01L 21/67201
20130101 |
Class at
Publication: |
141/098 |
International
Class: |
B65B 1/04 20060101
B65B001/04 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 18, 2005 |
JP |
2005-080595 |
Claims
1. An apparatus for processing an article in order to manufacture a
device, said apparatus comprising: a process chamber in which the
article is processed; a relay chamber; a first load-lock chamber
disposed between an outside of said apparatus and said relay
chamber; a second load-lock chamber disposed between said relay
chamber and said process chamber; a first adjusting mechanism
configured to adjust atmosphere in said process chamber to a first
atmosphere; and a second adjusting mechanism configured to adjust
atmosphere in said relay chamber to a second atmosphere that is an
intermediate atmosphere between the first atmosphere and atmosphere
of the outside.
2. An apparatus according to claim 1, wherein said first adjusting
mechanism is configured to adjust atmosphere in said process
chamber to a first degree of vacuum as the first atmosphere, and
said second adjusting mechanism is configured to adjust atmosphere
in said relay chamber to a second degree of vacuum, which is an
intermediate vacuum between the first degree of vacuum and a degree
of vacuum at the outside, as the second atmosphere.
3. An apparatus according to claim 1, wherein said first adjusting
mechanism is configured to adjust atmosphere in said process
chamber to an atmosphere of inert gas at a first density as the
first atmosphere, and said second adjusting mechanism is configured
to adjust atmosphere in said relay chamber to an atmosphere of the
inert gas at a second density, that is an intermediate density
between the first density and density of the inert gas at the
outside, as the second atmosphere.
4. An apparatus according to claim 1, wherein said first and second
load-lock chambers are configured so that capacity of said first
load-lock chamber for accommodating the article is greater than
that of said second load-lock chamber.
5. An apparatus according to claim 1, wherein said apparatus
includes a plurality of said first load-lock chambers.
6. An apparatus according to claim 1, wherein said apparatus
includes a plurality of said second load-lock chambers.
7. An apparatus according to claim 1, wherein said apparatus
includes a plurality of said first load-lock chambers having
different capacities for accommodating the article.
8. An apparatus according to claim 1, further comprising an exhaust
mechanism configured to exhaust gas from said first load-lock
chamber, wherein said exhaust mechanism is configured to change
over exhaust rate based on degree of vacuum in said first load-lock
chamber.
9. An apparatus according to claim 1, further comprising a supply
mechanism configured to supply inert gas into said first load-lock
chamber, wherein said supply mechanism is configured to change over
supply rate of the inert gas based on pressure in said first
load-lock chamber.
10. A method applied to an apparatus for processing an article in
order to manufacture a device, the article being transferred from
an outside of the apparatus into a process chamber where the
article is processed, said method comprising steps of: adjusting
atmosphere in the process chamber to a first atmosphere; adjusting
atmosphere in a relay chamber, which is disposed between the
process chamber and the outside, to a second atmosphere that is an
intermediate atmosphere between the first atmosphere and atmosphere
of the outside; transferring the article from the outside into the
relay chamber via a first load-lock chamber; and transferring the
article from the relay chamber into the process chamber via a
second load-lock chamber.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a technique for manufacturing
devices such as semiconductor elements. More particularly, the
invention relates to an atmosphere adjusting technique for
transferring an article between the interior and exterior of a
device manufacturing apparatus.
BACKGROUND OF THE INVENTION
[0002] In a case where the interior and exterior environments of an
apparatus differ greatly from each other, it is necessary to
provide a relay-like process chamber such as a load-lock chamber
for changing over the environment. For example, if there is a
substance of some kind between an exposure source and an article to
be exposed in a EUV exposure apparatus or a direct-writing exposure
apparatus that writes directly using an electron beam or the like,
this will have an effect upon the optical path of the exposing
light or exposing beam and accurate exposure will no longer be
possible. For this reason, it is necessary that the optical path of
the exposing light or exposing beam and the space in which the
wafer stage exists within the apparatus be held in a state of high
vacuum. Further, if oxygen or moisture content is irradiated with
an F.sub.2 laser in an F.sub.2 exposure apparatus, the laser beam
is absorbed and the exposure energy attenuated. This makes it
necessary to fill the optical path with high-concentration nitrogen
gas. In a case where the interior and exterior environments of an
apparatus thus differ greatly, it is necessary to change over the
environment using a load-lock chamber.
[0003] An example of the structure of an ordinary apparatus using a
load-lock chamber will be described with reference to FIG. 4.
[0004] In a case where the interior and exterior environments of
the apparatus differ and an article to be processed is transported
into the apparatus (or a processed article is extracted from the
interior of the apparatus), a load-lock chamber is used in order to
make the process environment such as pressure or gaseous component
outside the apparatus conform to that of the process section inside
the apparatus.
[0005] The apparatus illustrated in FIG. 4 has one such load-lock
chamber 10. The load-lock chamber 10 has two gates, namely an outer
gate 9 and an inner gate 11, capable of cutting off the interior of
the apparatus from the outside. When a processed article is
transferred from the interior of the apparatus, first the two gates
9 and 11 are closed and the environment in the load-lock chamber 10
is adjusted so as to be approximately the same as that in the
apparatus interior 15 by a pressure regulating mechanism 13. The
inner gate 11 is then opened, the processed article inside the
apparatus is extracted and placed inside the load-lock chamber 10
and the inner gate 11 is closed again. After the environment inside
the load-lock chamber 10 is made approximately the same as that
outside the apparatus, the outer gate 9 is opened and the processed
article Is transferred to the exterior of the apparatus. When an
article is transported into the interior of the apparatus, it will
suffice to reverse the above-described operation.
[0006] There are many cases where only a single load-lock chamber
10 is provided, as illustrated in FIG. 4. Even when only a single
load-lock chamber 10 exists, no particular problems arise as in a
case where the difference between the interior and exterior
environments is small or a case where the difference is large but
the application permits the processing time needed to adjust the
environment.
[0007] However, in instances where the environment of the process
section inside the apparatus is markedly different from the
exterior environment in which the apparatus has been installed,
there is a marked increase in process time necessary for the
adjustment of environment within the load-lock chamber produced
when the article such as a wafer is transported into the apparatus.
This results is a decline in throughput. Such a case where there is
a marked difference in environments is one where the pressure
inside the apparatus is lower than that of a high vacuum (on the
order of 10.sup.-5 pa), as in an EUV exposure apparatus, or one
where the optical path of a laser is filled with high-purity
nitrogen gas, as in an exposure apparatus that employs an F.sub.2
laser.
[0008] With the aim of preventing such a decline in throughput, the
specification of Japanese Patent Application Laid-Open No.
2000-150395 proposes an arrangement in which a plurality of
load-lock chambers are provided between the external environment of
an apparatus under atmospheric pressure and a vacuum process
chamber, thereby allowing processing to be performed in parallel.
If this arrangement is adopted, parallel operation in evacuation
and exhaust processes can be performed. This makes it possible to
shorten waiting time for the purpose of making the interior and
exterior environments agree.
[0009] However, by just simply arranging load-lock chambers in
parallel as in the method set forth in the specification of
Japanese Patent Application Laid-Open No. 2000-150395, the pressure
in each individual load-lock chamber is reduced from atmospheric
pressure to the pressure of the process chamber every time.
Consequently, if the set pressure in the vacuum process chamber is
extremely low, as in the case of the pressure of ultra-high vacuum,
it is difficult to make the pressure in each load-lock chamber
reach the target pressure in a short time. For example, it is
preferred that the process pressure in an apparatus such as an EUV
exposure apparatus be less than ultra-high vacuum pressure (i.e.,
less than 10.sup.-5 pa). However, when the set pressure is such a
low pressure, the time needed for chamber evacuation becomes
extremely lengthy and a decline is throughput cannot be avoided
even if a plurality of load-lock chambers are provided.
[0010] In order to shorten the time needed to attain vacuum, a
method of simply strengthening exhaust capability or heating the
load-lock chamber is conceivable. For example, if a load-lock
chamber is baked to release the gas from within or a pump having a
strong exhaust capability is used, an improvement in vacuum
attainment time can be achieved. In this case, however, there is
the possibility that a new problem will arise.
[0011] By way of example, it is effective to perform the baking of
a load-lock chamber at as high a temperature as possible. However,
there is the concern that the heat from baking will penetrate into
the interior of the apparatus and affect exposure performance and
that the wafer undergoing processing will be subjected to thermal
damage, depending upon the set temperature. Further, it is not easy
to select a material that can withstand repetitive shifts between
room temperature and high temperature and between atmospheric
pressure and ultra-high vacuum pressure over an extended period of
time, and it is not easy to realize a vacuum-seal mechanism for
forming such a load-lock chamber. In addition, if a pump having a
strong exhaust capability is used, vacuum attainment time can be
shortened because the exhaust speed rises. However, merely adopting
a pump having an excellent exhaust performance causes dust to rise
within the process chamber and can cause the wafer to be
contaminated.
SUMMARY OF THE INVENTION
[0012] The present invention has been devised in view of the
background set forth above and an exemplary object thereof is to
provide a novel technique relating to transfer of an article
between the interior and exterior of a device manufacturing
apparatus.
[0013] According to one aspect of the present invention, there is
provided an apparatus for processing an article in order to
manufacture a device, the apparatus comprising: a process chamber
in which the article is processed; a relay chamber; a first
load-lock chamber disposed between an outside of the apparatus and
the relay chamber; a second load-lock chamber disposed between the
relay chamber and the process chamber; a first adjusting mechanism
configured to adjust atmosphere in the process chamber to a first
atmosphere; and a second adjusting mechanism configured to adjust
atmosphere in the relay chamber to a second atmosphere that is an
intermediate atmosphere between the first atmosphere and atmosphere
of the outside.
[0014] Also, according to another aspect of the present invention,
there is provided a method applied to an apparatus for processing
an article in order to manufacture a device, the article being
transferred from an outside of the apparatus into a process chamber
where the article is processed, the method comprising steps of:
adjusting atmosphere in the process chamber to a first atmosphere;
adjusting atmosphere in a relay chamber, which is disposed between
the process chamber and the outside, to a second atmosphere that is
an intermediate atmosphere between the first atmosphere and
atmosphere of the outside; transferring the article from the
outside into the relay chamber via a first load-lock chamber; and
transferring the article from the relay chamber into the process
chamber via a second load-lock chamber.
[0015] 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
[0016] 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.
[0017] FIG. 1 is a diagram illustrating an example of equipment
according to a first embodiment of the present invention;
[0018] FIG. 2 is a diagram illustrating an example of equipment
according to a second embodiment of the present invention;
[0019] FIG. 3 is a diagram illustrating an example of equipment
according to a third embodiment of the present invention;
[0020] FIG. 4 is a diagram illustrating an example of equipment
constituting a vacuum exposure apparatus according to the prior
art;
[0021] FIG. 5 is a flowchart useful in describing an operation for
transferring a wafer by a controller; and
[0022] FIG. 6 is a flowchart useful in describing an operation for
transferring a wafer by a controller.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] Preferred embodiments of the present invention will now be
described in detail in accordance with the accompanying
drawings.
[0024] <Overview of the embodiments>
[0025] First, reference will be had to FIG. 1 to describe
embodiments in a case where the present invention is applied to an
exposure apparatus.
[0026] In the embodiments, an environment adjusting mechanism is
provided between a process section (process chamber 15), which is
located in an exposure apparatus, and the environment in which the
apparatus is installed. The environment adjusting mechanism has a
plurality of load-lock chambers 2a, 2b, 10 arranged in parallel and
in series, and a transfer mechanism 6 constituted by a transfer
robot or the like for transferring an article such as a wafer. The
environment adjusting mechanism further includes regulating
mechanisms 5a, 5b, 8, 13, 14 that are capable of individually
controlling the environment in all of the sealable spaces from the
exterior to the interior of the apparatus. The regulating
mechanisms 5a, 5b, 8, 13, 14 use pressure regulating valves and
vacuum pumps to make possible individual control of regulated
pressure in each chamber (relay chamber 7 and process chamber 15)
and in each load-lock chamber. The load-lock chambers 2a, 2b
arranged in parallel are provided for the purpose of performing
parallel processing in order to shorten the time needed for
adjusting environment. On the other hand, the load-lock chamber 10
is disposed in series with the load-lock chambers 2a, 2b. The
load-lock chamber 10 does not perform an adjustment of environment
from the installation environment outside the apparatus to the
wafer process environment (the environment inside the process
chamber 15) in one stroke as is done conventionally. Rather, the
load-lock chamber 10 is provided for the purpose of reducing
waiting time for environmental adjustment via the relay chamber 7,
which is in an intermediate state. Adopting such an arrangement
improves the throughput of the apparatus.
[0027] The control method and appropriate pressure values will now
be described in detail.
[0028] Condensation will be discussed first. There are instances
where an article such as a wafer develops condensation owing to
removal of heat by sudden adiabatic expansion. The humidity and
pressure of the environment in which the article has been placed
can be mentioned as conditions that give rise to condensation. It
is known that if pressure is less than 100 pa in a case where the
initial humidity is on the order of 50%, condensation will not
occur even if the chamber is evacuated at high speed.
[0029] The raising of dust is another factor. An appropriate
pressure value for preventing the attachment of dust differs
depending upon the estimated size of the dust particles. That is,
pressure at which the falling of dust under the force of gravity
and the floating of dust due to Brownian movement are substantially
in competition differs depending upon the size of the dust
particles. Specifically, it is known that this pressure is
10.sup.-2 pa in case of dust particles of size 10 nm, 10 pa in case
of dust particles of size 50 nm, and 100 pa in case of a dust
particles of size 0.1 .mu.m. Further, when dust becomes
electrically charged, it attaches itself to the wafer owing to the
force of static electricity. This makes it necessary to perform
de-electrification by a vacuum ionizer. Dust having a size of less
than 50 nm usually is the object of de-electrification, although
this will depend upon the specifications of the de-electrification
apparatus.
[0030] In view of the foregoing, in this embodiment the entry
load-lock chambers 2a, 2b for accepting an article such as a wafer
are evacuated slowly from atmospheric pressure down to about 100
pa, then evacuation is performed at high speed on the side of
pressure below this level. With regard to the relay chamber 7 for
transferring the wafer from the entry load-lock chambers 2a, 2b to
the load-lock chamber 10 of the process section (herein after
referred to as the process-section load-lock chamber 10), it is
preferred that the pressure here be made less than 10 pa in
consideration of the fact that dust particles that have been
de-electrified by a vacuum ionizer (not shown) are the object of
interest. The pressure in the interior of the relay chamber 7
should at least be less than 100 pa, which is a pressure at which
high-speed evacuation is possible. Further, with regard to the
pressure of the process-section load-lock chamber 10 through which
the article is introduced into the interior of the apparatus, the
pressure varies from a pressure identical with that inside the
relay chamber 7 to the pressure of the process section inside the
apparatus (namely the pressure inside the process chamber 15).
[0031] The embodiments thus provide a space in which the
environment is adjusted in multiple stages and a plurality of
load-lock chambers for accepting an article between stages. This
arrangement makes it possible for the adjustment of environment in
each load-lock chamber to be completed in a short period of
time.
[0032] It should be noted that when an environment filled to a high
concentration with a specific gas such as nitrogen gas is prepared,
an environment adjusting mechanism constituted by an environment
adjusting space of a plurality of stages and a plurality of
load-lock chambers connected thereto is effective for reasons
similar to those for regulating the pressure environment. More
specifically, a gas exchange can be performed at high speed by
injecting nitrogen gas into the article entry load-lock chambers
2a, 2b after evacuation without raising dust particles in a manner
similar to that of a vacuum apparatus. Further, by providing the
relay chamber 7 having the intermediate environment from the
article entry point to the process section inside the apparatus,
the environment such as the nitrogen gas concentration or amount of
water content can be made to approximate the state of the process
section in stages in a manner similar to that of the pressure
adjustment. Various embodiments will be described next.
[0033] <First Embodiment>
[0034] FIG. 1 illustrates the structure of a vacuum exposure
apparatus for performing exposure treatment in an ultra-high
vacuum, examples of the apparatus being an EUV exposure apparatus
and a direct-writing exposure apparatus that uses an electron beam.
Further, the vacuum exposure apparatus of FIG. 1 assumes a
mass-production apparatus in which a multiplicity of wafers are
processed.
[0035] As illustrated in FIG. 1, two entry load-lock chambers 2a,
2b are provided in order to carry in articles such as a wafer from
outside the apparatus. This makes it possible to process the wafers
in. parallel. The entry load-lock chamber 2a (2b) is provided with
an outer gate 1a (1b) and an inner gate 3a (3b). The interior of
the load-lock chamber can be made a sealed space by closing both
gates. If the outer gate 1a (1b) is opened, the load-lock chamber
is communicated with the exterior of the apparatus, and if the
inner gate 3a (3b) is opened, the load-lock chamber is communicated
with the relay chamber 7.
[0036] Further, the process-section load-lock chamber 10 is
provided in order to carry the wafer into the interior of the
apparatus (into process chamber 15). The process-section load-lock
chamber 10 also is provided with an outer gate 9 and an inner gate
11. The interior of this load-lock chamber can be made a sealed
space by closing both gates. If the outer gate 9 is opened, the
load-lock chamber is communicated with the relay chamber 7, and if
the inner gate 11 is opened, the load-lock chamber is communicated
with the process chamber 15.
[0037] A transfer mechanism 6 transfers the article such as a wafer
from the entry load-lock chamber 2a or entry load-lock chamber 2b
to the process-section load-lock chamber 10 and includes a transfer
robot or the like. The relay chamber 7 encloses the transfer
mechanism 6 and is regulated so as to have a pressure between
atmospheric pressure outside the apparatus and the pressure inside
the process chamber 15. Further, pressure regulating mechanisms 5a,
5b, 8, 13 and 14 are capable of individually regulating the
pressures within the entry load-lock chambers 2a, 2b, relay chamber
7, process-section load-lock chamber 10 and process chamber 15,
respectively. A controller 101 controls the opening and closing of
the gates of the load-lock chambers, the pressure regulating
mechanisms and the transfer mechanism, etc.
[0038] Reference will now be had to the flowcharts of FIGS. 5 and 6
and to FIG. 1 to describe control of transfer of articles (wafers)
in the exposure apparatus of this embodiment constructed as set
forth above. FIGS. 5 and 6 are flowcharts useful in describing
operation performed by the controller 101.
[0039] As mentioned above, it is assumed that the interior of the
apparatus has been de-electrified by a vacuum ionizer, which is not
shown. Further, in order to simplify the description, a case where
a wafer is introduced from the entry load-lock chamber 2a will be
described. Operation is similar also in a case where a wafer is
introduced from the entry load-lock chamber 2b.
[0040] The entry load-lock chamber 2a is regulated in such a manner
that its pressure will become substantially identical with the
pressure outside the apparatus. The outer gate 1a thereof is then
opened. That is, with the outer gate 1a and inner gate 3a in the
closed state, the pressure inside the entry load-lock chamber 2a is
equalized with the pressure outside and the outer gate 1a is then
opened (steps S101, S102, S103).
[0041] A plurality of wafers introduced to a wafer carrier 4a in
advance are carried into the entry load-lock chamber 2a. At this
time the outer gate 1a of the entry load-lock chamber 2a has
already been opened by the controller 101 and the inner gate 3a has
already been closed by the controller, as set forth above. The
placement of the wafer carrier 4a in the entry load-lock chamber 2a
may be performed manually or automatically by a transfer robot or
the like. If completion of placement of the wafer carrier 4a is
detected, the controller 101 closes the outer gate 1a (steps S104,
S105) and the entry load-lock chamber 2a starts to be depressurized
by the corresponding pressure regulating mechanism 5a (step S106).
At this time the pressure in the load-lock chamber 2a is lowered
gradually from atmospheric pressure to 100 pa, and depressurization
is then performed at high speed once the pressure has fallen below
100 pa, as mentioned above. By exercising such control of
depressurization, it is possible to prevent the wafer from
developing condensation due to adiabatic expansion caused by sudden
evacuation, and to prevent the wafer from being contaminated by
rising dust ascribable to an air stream produced within the entry
load-lock chamber 2a.
[0042] Depressurization is performed until the pressure becomes
substantially equal to the pressure inside the relay chamber 7.
After such depressurization the controller 101 opens the inner gate
3a of the entry load-lock chamber 2a (steps S107, S108). It is
preferred that the pressure in the relay chamber 7 be on the order
of 10 pa, as mentioned above. This is followed by transferring
wafers in the wafer carrier 4a to the process-section load-lock
chamber 10 by the transfer mechanism 6 such as a vacuum robot (step
S110). It should be noted that since the processing of steps S101
to S108 transfers a plurality of wafers as a unit to the entry
load-lock chamber 2a by means of the wafer carrier 4a, the
processing need be executed only one time for these plurality of
wafers.
[0043] On the other hand, with regard to the process-section
load-lock chamber 10, the pressure within this chamber is made the
same as that (less than 10 pa) in the relay chamber 7 by the
corresponding pressure regulating mechanism 13 with the outer gate
9 and inner gate 11 being in the closed state, after which the
outer gate 9 is opened (steps S121, S122, S123). That is, it is
assumed that at least at the time of execution of step S110, the
process-section load-lock chamber 10 will have been regulated to a
prescribed pressure by the pressure regulating mechanism 13 and
that the outer gate 9 of on the side of the transfer mechanism 6
will have been opened. When it is detected that the wafers have
been placed inside the process-section load-lock chamber 10 by the
transfer mechanism 6 ("YES" at step S124), the controller 101
closes the outer gate 9 (step S125). The interior of the
process-section load-lock chamber 10 is depressurized until its
pressure becomes equal to that of the process chamber 15
[ultra-high vacuum pressure (i.e., less than 10.sup.-5 pa)] (steps
S126, S127). The inner gate 11 is then opened (step S128). Under
these conditions the wafers are transferred to the process chamber
15 by a transfer mechanism (not shown) within the process chamber
15 (step S130).
[0044] Although it is preferred that the pressure inside the
process chamber 15 in the main body of the exposure apparatus be
less than ultra-high vacuum pressure (less than 10.sup.-5 pa), it
is conceivable, depending upon the structure and volume of the
process section within the apparatus, that a further load-lock
chamber capable of local evacuation will be added. (Adopting a high
vacuum within the entirety of the apparatus is difficult if the
apparatus is large in size. Accordingly, the area that is to be
evacuated is reduced by providing a new load-lock chamber in the
process section within the apparatus and locally evacuating the
portion through which the light beam passes.) However, there are
also cases where the above-mentioned set pressure value is decided
comprehensively taking into account exposure process time,
evacuation time and number of wafer accepting ports. For example,
although the pressure in the relay chamber 7 for wafer transfer is
desirably 10 pa, there are cases where this pressure will be 100 pa
depending upon apparatus conditions.
[0045] As mentioned above, two entry load-lock chambers 2a, 2b are
meant to allow evacuation to be performed in parallel. The number
of these load-lock chambers is not limited to two and may be three
or more. Further, it is also possible to construct an apparatus
having a single entry load-lock chamber.
[0046] Operation for carrying wafers into the process chamber 15
from outside the apparatus has been described. Operation for
transporting wafers from the process chamber 15 to the exterior of
the apparatus is the reverse of the above-described operation. An
example of this process will be described with reference to FIG.
6.
[0047] First, with the inner gate 11 and outer gate 9 of
process-section load-lock chamber 10 closed, the pressure within
the process-section load-lock chamber 10 is made equal to that
inside the process chamber 15, after which the inner gate 11 is
opened (steps S201 to S203). Then, after wafers are placed inside
the process-section load-lock chamber 10 by a transfer mechanism
(not shown), the inner gate 11 is closed (steps S204, S205). This
is followed by elevating the pressure in process-section load-lock
chamber 10 until it becomes equal to the pressure in the relay
chamber 7. The outer gate 9 is opened after the pressures are
equalized (steps S206 to S208). The transfer mechanism 6 is then
driven to extract the wafers from the load-lock chamber 10 and
place them in the relay chamber 7 (step S210).
[0048] It should be noted that it is not necessarily required to
close the inner gate 11 of the process-section load-lock chamber 10
after the wafers have been carried into the process chamber 15 from
the process-section load-lock chamber 10. Accordingly, if the inner
gate 11 is open, naturally the operation at steps S201 to S203 in
FIG. 6 is omitted.
[0049] On the other hand, the controller 101 closes the inner gate
3a and outer gate 1a of the entry load-lock chamber 2a and
regulates the pressure inside this load-lock chamber until it
becomes equal to the pressure inside the relay chamber 7, after
which the controller 101 closes the inner gate 3a (steps S211 to
S213). Under these conditions, the transfer mechanism 6 transfers
the wafers, which have been extracted from the process-section
load-lock chamber 10, to the interior of the entry load-lock
chamber 2a and places the wafers on the wafer carrier 4a.
[0050] It should be noted that it is not necessarily required to
close the inner gate 3a of the entry load-lock chamber 2a after the
wafers have been carried into the relay chamber 7 from the entry
load-lock chamber 2a. Accordingly, if the inner gate 3a is open,
naturally the operation at steps S211 to S213 in FIG. 6 is
omitted.
[0051] If completion of transfer into the entry load-lock chamber
2a is detected, the controller 101 closes the inner gate 3a, causes
the pressure in this chamber to rise until it becomes equal to
atmospheric pressure outside the apparatus and thenceforth opens
the outer gate 1a (steps S214 to S218). This is followed by
transferring the wafers from the entry load-lock chamber 2a by a
transfer mechanism (not shown) or manually (step S220). The wafers
can be extracted to the exterior of the apparatus by the
above-described processing. It should be noted that since the entry
load-lock chamber 2a enables a plurality of wafers to be brought in
and taken out in one batch by the wafer carrier 4a, the processing
of steps S215 to S218 need only be executed one time per plurality
of wafers.
[0052] The advantages obtained by using the environment adjusting
mechanism set forth above will now be described. Considered first
will be a case where there is no serially arranged relay chamber 7
of the kind according to this embodiment, namely a case where only
a single load-lock chamber intervenes, as in the example of the
prior art shown in FIG. 4.
[0053] In order to shorten even slightly the time needed to attain
a desired vacuum pressure, the smaller the volume and surface area
of the object to be evacuated, the better. In particular, in the
case of low pressure such as ultra-high vacuum pressure, surface
area is important. Accordingly, if a comparison is made based upon
length of evacuation time per cycle, it will be found that a method
of supplying wafers one at a time is better than supplying wafers
using the wafer carrier 4a in terms of enabling a reduction in the
volume of the load-lock chamber and the surface area thereof. This
means that a short evacuation time per cycle will suffice. This is
the reason why the process-section load-lock chamber 10 of this
embodiment has a structure that supplies wafers one at a time.
However, even though the method of supplying wafers one at a time
is the same as the conventional method, this embodiment is such
that evacuation is performed by lowering the pressure in the relay
chamber 7, which is a pressure sufficiently lower than atmospheric
pressure. Consequently, the total amount of air exhausted is much
less in comparison with the conventional method (where evacuation
starts from atmospheric pressure) and, as a result, the time needed
to attain the target pressure can be shortened.
[0054] Further, in order to shorten target-pressure attainment time
per wafer, it is better to place a plurality of wafers in vacuum
simultaneously using the wafer carrier 4a than to supply wafers one
at a time. This is because the number of times the outer gate 1a of
the entry load-lock chamber 2a is opened and closed can be reduced
and because transfer time is curtailed. In this case, however, a
great deal of time is required to attain the necessary degree of
vacuum because of the large volume and surface area involved. This
is extremely influential particularly in a case where the target
pressure is low, as when the target pressure is ultra-high vacuum
pressure. In this embodiment, however, the entry load-lock chambers
2a, 2b are evacuated only down to the pressure in the relay chamber
7, and not down to the region of ultra-high vacuum, from
atmospheric pressure. This makes it possible to shorten process
time. That is, the advantage of placing a plurality of wafers in
vacuum simultaneously by the wafer carrier 4a can be exploited.
[0055] Thus, in accordance with the first embodiment, as set forth
above, the relay chamber 7 that has been set to a pressure (on the
order of 10 pa) sufficiently lower than atmospheric pressure is
provided between the entry load-lock chamber 2a and the
process-section load-lock chamber 10. As a result, the total amount
of air exhausted from the process-section load-lock chamber 10 can
be reduced in comparison with a case where vacuum is produced
starting from atmospheric pressure. Furthermore, since volume and
surface area can be reduced by introducing wafers from the relay
chamber 7 to the process-section load-lock chamber 10 one at a
time, processing is speeded up in the process-section load-lock
chamber 10 where evacuation to ultra-high vacuum pressure is
required. Further, since the wafer carrier 4a is used to carry
wafers into the entry load-lock chambers 2a, 2b that do not need to
be evacuated to the region of ultra-high vacuum, amount of air
exhausted per wafer can be reduced. Furthermore, by providing a
plurality of entry ports and performing processing in parallel, the
time needed to evacuate the entry load-lock chambers 2a, 2b can be
reduced as well.
[0056] In accordance with the arrangement of this embodiment,
therefore, processing time needed to adjust the environment can be
shortened in comparison with the prior-art methods. The embodiment
is particularly effective in cases where a plurality of wafers are
processed simultaneously.
[0057] <Second Embodiment>
[0058] FIG. 2 is a diagram illustrating an example of equipment
according to a second embodiment of the present invention. The
arrangement using the wafer carrier 4a as described in the first
embodiment is very effective in cases where a number of wafers are
processed simultaneously. In a case where the number of wafers
processed is small, however, there is the concern that process time
will be lengthened rather than shortened owing to the large volume
of air that must be exhausted in the entry load-lock chamber
2a.
[0059] In the second embodiment, an entry load-lock chamber 2c that
is capable of introducing wafers one at a time is provided taking
the above-mentioned case into consideration. Adopting such an
arrangement makes it possible to offset the drawback of increased
amount of air exhaust mentioned above.
[0060] Depending upon the method of apparatus operation,
arrangements in which there is a mixture of wafer-carrier entry
ports or in which a plurality of wafer-by-wafer entry ports are
provided are also conceivable. Further, although only one entry
port for wafers one at a time is provided in FIG. 2, two or more
may be provided.
[0061] Thus, the second embodiment provides the load-lock chamber
2c, which makes it possible to mount wafers one at a time, besides
using a wafer carrier to supply wafers. This is one exemplary
variation of a method of supplying wafers. This arrangement is
effective in a case where small lots of wafers are processed.
[0062] <Third Embodiment>
[0063] An example of the structure of a vacuum apparatus has been
described in the first and second embodiments. The environment
adjusted in this vacuum apparatus is pressure. However, the
arrangements of the first and second embodiments are effective also
in a case where a gaseous composition or water content, etc., is
adjusted. FIG. 3 is a diagram illustrating an example of equipment
according to a third embodiment of the present invention. The third
embodiment provides a gas control mechanism in addition to a
pressure control mechanism, thereby similarly raising throughput
even in an environment other than a vacuum environment.
[0064] In the third embodiment, gas regulating mechanisms 16 to 20
are provided in addition to pressure regulating mechanisms similar
to those of the first embodiment. The gas regulating mechanisms 16
to 20 each comprise a mechanism (e.g., a mass-flow controller) for
injecting a high-purity specific gas such as nitrogen gas, and a
drier for removing water content. These control each chamber and
load-lock chamber individually. The gas regulating mechanisms 16 to
20 are installed for the purpose of regulating the respectively
connected sealable spaces to desired gas components.
[0065] Even in a case where the purity of the gas component
required for the interior of the process chamber 15 is extremely
stringent, adjustment time can be shortened more by relying upon
the intermediary of the relay chamber 7, as described in the
pressure adjustment of the first and second embodiments, than by
performing adjustment at one stroke from the installation
environment external to the apparatus. That is, for reasons similar
to those for adjusting the pressure environment, an environment
adjusting mechanism composed of a plurality of load-lock chambers
is useful also when preparing an environment for filling a space
with a specific gas such as nitrogen gas at a high
concentration.
[0066] In accordance with each of the foregoing embodiments as
described above, providing a plurality of ports for acceptance of
wafers from atmospheric pressure makes it possible to execute
depressurization of the entry load-lock chambers, which are
provided at the acceptance ports, simultaneously and in parallel.
As a result, effective depressurization time can be shortened and
an improvement in throughput achieved.
[0067] In a case where the environment that supplies an article
such as a wafer differs greatly from the process environment inside
the exposure apparatus, process time needed for the environmental
adjustment can be reduced and throughput raised by providing an
environment adjusting mechanism comprising a plurality of load-lock
chambers and passing wafers through an intermediate
environment.
[0068] Further, when a wafer under atmospheric pressure is fed into
the process section within an apparatus having a vacuum space or
nitrogen-gas purging space, it is necessary to carry out evacuation
or gas exchange. In a case where the required process environment
is very stringent, the time needed for the adjustment of
environment is prolonged, waiting time up to exposure process
lengthens and throughput declines.
[0069] By contrast, with the first embodiment, processing at a
speed higher than that with the conventional method becomes
possible by providing a plurality of entry load-lock chambers in
parallel, placing the entry load-lock chambers in series with a
load-lock chamber of a process section, as illustrated in FIG. 1,
and establishing an appropriate environment in each of the
chambers. Further, depressurization of a plurality of wafers is
performed at one time using a wafer carrier or the like and relying
upon the intermediary of a plurality of entry load-lock chambers,
and the wafers are carried into interior of the apparatus one at a
time. The result is greatly improved throughput.
[0070] Further, in relation to the entry load-lock chambers, it is
so arranged that a plurality of wafers can be carried in and out at
one time using a wafer carrier. This means that the number of times
a gate valve of the load-lock chamber is opened and closed can be
reduced. That is, the amount of air actually exhausted can be
reduced more by introducing a plurality of wafers into a load-lock
chamber at one time than by accepting the wafers one at a time.
This makes it possible to achieve improved throughput.
[0071] As illustrated in each of the foregoing embodiments,
exercising control in such a manner that the plurality of load-lock
chambers will attain prescribed pressures makes it possible to
perform high-speed processing while suppressing the effects of
wafer contamination, which is due to rising dust, and wafer
condensation. That is, in an entry load-lock chamber for accepting
a wafer, there is a changeover between high-speed evacuation and
low-speed evacuation about a boundary value of 100 pa. Further, by
making the value of pressure less than 100 pa in the transfer area
of the relay chamber 7 and in the process-section load-lock chamber
10 for introducing a wafer to the apparatus process area (the
process chamber 15) and, in particular, by making the pressure 10
pa in the relay chamber 7, throughput can be improved while
contamination due to dust is suppressed.
[0072] With regard to the above-described advantages of the vacuum
apparatus, namely a reduction in the total amount of air exhausted
and the prevention of rising dust, it is obvious that the invention
is similarly effective also with regard to an apparatus that
requires filling with a specific gas such as nitrogen gas at a high
concentration. Accordingly, when a gas exchange is performed in a
case where an apparatus is filled with a specific gas such as
nitrogen gas at a high concentration, it is preferred that the
speed at which the load-lock chambers are evacuated or at which
they are filled with gas be controlled appropriately in accordance
with the pressure inside the load-lock chambers. Further, although
each of the embodiments indicates an arrangement in which a
plurality of entry load-lock chambers and a single process-section
load-lock chamber 10 are provided, a plurality of the
process-section load-lock chambers 10 may be provided.
[0073] Thus, in accordance with the implementation of the present
invention as described above, the introduction and extraction of an
article to and from an apparatus can be performed at high speed and
the throughput of the apparatus can be raised in a case where the
environment inside the apparatus differs greatly from the
environment outside the apparatus.
[0074] 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 appended claims.
[0075] This application claims the benefit of Japanese Patent
Application No. 2005-080595, filed on Mar. 18, 2005, which is
hereby incorporated by reference herein in its entirety.
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