U.S. patent application number 09/851330 was filed with the patent office on 2002-02-21 for processing apparatus.
Invention is credited to Asakawa, Teruo, Matsushima, Keiichi, Narushima, Masaki, Saeki, Hiroaki.
Application Number | 20020020355 09/851330 |
Document ID | / |
Family ID | 18283313 |
Filed Date | 2002-02-21 |
United States Patent
Application |
20020020355 |
Kind Code |
A1 |
Saeki, Hiroaki ; et
al. |
February 21, 2002 |
Processing apparatus
Abstract
Two load lock chambers 130 and 132 are arranged between a first
transfer chamber 122 and a second transfer chamber 133. Each of the
load lock chambers is capable of accommodating a single wafer W.
The first transfer chamber 122 is provided with a first transfer
unit 124 having two substrate holders 124a, 124b each capable of
holding a single object to be processed, in order to transport the
wafer W among a load port site 120, the first load lock chamber
130, the second load lock chamber 132 and a positioning unit 150.
The second transfer chamber 133 is provided with a second transfer
unit 156 having two substrate holders 156a, 156b each capable of
holding the single object to be processed, in order to transport
the wafer between the first load lock chamber 130, the second load
lock chamber 132 and respective vacuum processing chambers 158 to
164. Since the volume of each load lock chamber can be minimized,
it is possible to perform the prompt control of atmospheres in the
load lock chambers. Additionally, it is possible to perform the
delivery of the wafers promptly.
Inventors: |
Saeki, Hiroaki;
(Yamanashi-ken, JP) ; Matsushima, Keiichi;
(Yamanashi-ken, JP) ; Asakawa, Teruo;
(Yamanashi-ken, JP) ; Narushima, Masaki;
(Yamanashi-ken, JP) |
Correspondence
Address: |
Smith, Gambrell & Russell, LLP
The Beveridge, DeGrandi, Weilacher & Young
Intellectual Property Group
1850 M Street, N.W., Suite 800
Washington
DC
20036
US
|
Family ID: |
18283313 |
Appl. No.: |
09/851330 |
Filed: |
May 9, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09851330 |
May 9, 2001 |
|
|
|
PCT/JP99/06226 |
Nov 9, 1999 |
|
|
|
Current U.S.
Class: |
118/719 |
Current CPC
Class: |
Y10S 414/135 20130101;
H01L 21/67745 20130101; H01L 21/67742 20130101; H01L 21/67766
20130101; H01L 21/67167 20130101; Y10S 414/136 20130101; H01L
21/67201 20130101 |
Class at
Publication: |
118/719 |
International
Class: |
C23C 016/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 9, 1998 |
JP |
10-334974 |
Claims
1. A processing apparatus comprising: a first enclosure defining a
first transfer space having an atmosphere of atmospheric pressure;
a load port site, in which a plurality of load ports are aligned
adjacently to the first transfer space, each of the load ports
being capable of mounting a cassette for accommodating objects to
be processed, the cassette having a door; a plurality of door
openers provided at the load ports respectively to open and close
the door of the cassette, the door openers each allowing the first
transfer space to communicate with an interior of the cassette when
the door opener opens the door of the cassette; a second enclosure
defining a second transfer space having an atmosphere of vacuum or
negative pressure; a plurality of vacuum processing chambers
arranged around the second transfer space; a plurality of load lock
chambers opposed to the load port site over the first transfer
space and also disposed between the first transfer space and the
second transfer space, the load lock chambers each capable of
accommodating only one object therein; first gate valves each
arranged at each of the load lock chambers to separate the load
lock chambers from the first transfer space; second gate valves
each arranged at each of the load lock chambers to separate the
load lock chambers from the second transfer space; third gate
valves each arranged at each of the vacuum processing chambers to
separate the vacuum processing chambers from the second transfer
space; a positioning unit that adjusts the positions of an object
and is arranged adjacent to the first transfer space; a first
transfer unit arranged in the first transfer space to transfer an
object among the cassette, the load lock chambers and the
positioning unit, the first transfer unit having two holders each
capable of holding only one object; and a second transfer unit
arranged in the second transfer space to transfer the objects
between the load lock chambers and the vacuum processing chambers,
the second transfer unit having two holders each capable of holding
only one object.
2. The processing apparatus according to claim 1, wherein the first
transfer unit is movable in a direction parallel with an
arrangement direction of the load ports and the positioning unit is
adjacent to an end of the first transfer space with respect to the
arrangement direction of the load ports.
3. The processing apparatus according to claim 1, wherein the
positioning unit is arranged between two of the load lock
chambers.
4. The processing apparatus according to claim 1, further
comprising a cooling unit arranged in the load lock chamber to cool
the objects.
5. The processing apparatus according to claim 1, further
comprising a heater unit arranged in the load lock chamber to heat
the objects.
6. The processing apparatus according to claim 1, wherein clean air
is circulated in the first transfer space.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates to a multi-chamber type
processing apparatus for processing an object to be processed, such
as semiconductor wafer.
BACKGROUND OF THE INVENTION
[0002] The manufacturing process for semiconductor devices
conventionally employs the so-called "clustered" multi-chamber type
processing apparatus that comprises, in view of improvement in its
throughput and prevention of contamination of semiconductor
devices, a vacuum transfer chamber (transfer chamber) at the center
of the apparatus, a plurality of vacuum processing chambers
(process chambers) around the transfer chamber, one or more load
lock chambers and a vacuum preparation chamber for heating or
cooling the objects to be processed. The apparatus further includes
a plurality of load ports each capable of mounting a cassette
thereon. The load ports are connected to the load lock chambers
through a transfer chamber on the side of the atmosphere,
constituting a load port site. In the multi-chamber type processing
apparatus, there are included: a processing apparatus that has a
"batch" type load lock chamber for accommodating the cassette
itself or a plurality of objects, for example, semiconductor wafers
(simply referred "wafers" after) in the cassette; and another
processing apparatus provided with a single-wafer load lock chamber
for accommodating a single wafer therein. The former apparatus will
be called "batch type processing apparatus" hereinafter. Similarly,
the latter apparatus will be called "single wafer processing
apparatus" hereinafter.
[0003] The processing order in the batch type processing apparatus
will be described. After first mounting a sealed (closing) type
cassette on the load port, a first transfer arm in the atmospheric
transfer chamber conveys the cassette itself or all wafers in the
cassette, for example, thirteen or twenty-five pieces of wafers,
into the load lock chamber. Next, the load lock chamber is closed
up and evacuated into vacuum. After the general equalization of
pressure is established between the load lock chamber and the
vacuum transfer chamber, these chambers are communicated with each
other. Subsequently, each wafer in the load lock chamber is
adjusted in position by an object positioning unit arranged in the
vacuum transfer chamber or the vicinity and thereafter, a second
transfer arm in the vacuum transfer chamber transports the aligned
(positioned) wafer to a vacuum preliminary chamber or each vacuum
processing chamber to apply a designated processing, such as thin
film deposition, on the wafer. The processed wafer is again
transferred to the load lock chamber or the cassette therein by the
second transfer arm. Upon collecting all the wafers, the load lock
chamber is sealed up again to raise the pressure of the atmosphere
in the chamber. Next, the load lock chamber is communicated with
the transfer chamber on the side of the atmosphere. Thereafter, the
first transfer arm either conveys the cassette to the load port or
transports the wafer to the cassette on the load port.
[0004] While, the processing order of the single wafer processing
apparatus is as follows. After the wafers in the cassette mounted
on the load port have been adjusted in position by the object
positioning unit in the vicinity of the transfer chamber on the
side of the atmosphere, the first transfer arm transfers the wafers
into the load lock chamber one by one. Next, the load lock chamber
is sealed up and evacuated for vacuum. As similar to above, after
the pressure of the atmosphere in the load lock chamber becomes
equal to the pressure of the atmosphere in the vacuum transfer
chamber substantially, the interior of the load lock chamber is
communicated with the vacuum transfer chamber. Thereafter, the
second transfer arm transports the wafer in the load lock chamber
to the vacuum preliminary chamber or each vacuum processing chamber
to apply a designated processing similar to the above on the wafer.
The processed wafer is again transferred to the load lock chamber
by the second transfer arm. After the load lock chamber is sealed
up again to raise the pressure of the atmosphere in the chamber,
the load lock chamber is communicated with the transfer chamber on
the side of the atmosphere. Thereafter, the first transfer arm
transports the wafer to the cassette on the load port. Note, the
above-mentioned steps are successively carried out every
cassette.
[0005] In order to reduce the possibility that particles invade the
interior of the transfer chamber on the side of the atmosphere, the
batch type processing apparatus and the single wafer processing
apparatus commonly supply the transfer chamber on the side of the
atmosphere with a clean gas, such as N.sub.2, to make the pressure
of the transfer chamber relatively higher than the pressure of a
clean room having the transfer chamber on the side of the
atmosphere, the load port site, etc. arranged therein.
[0006] In the above-mentioned batch type processing apparatus,
however, it takes a lot of time to exhaust the atmosphere in the
load lock chamber or supply the same chamber with gas since the
load lock chamber is formed with a volume capable of accommodating
a cassette itself or several wafers. Additionally, since the batch
type processing apparatus has to arrange the object positioning
unit adjacent to the vacuum transfer chamber, the number of wafer
delivery times by the second transfer arm is increased to make the
transfer time (cycle) long. Consequently, the problems may cause
the throughput of the apparatus to be lowered.
[0007] In the above-mentioned single wafer processing apparatus,
when the first transfer arm or the second transfer arm is
constructed to carry the only wafer, it takes a lot of time to
deliver the wafer through the load lock chamber. If a plurality of
mount tables for mounting the wafer thereon is provided in the load
lock chamber, then it is possible to reduce the above wafer
delivery time. However, as similar to the batch type processing
apparatus, it takes a lot of time to exhaust the atmosphere in the
load lock chamber or supply the same chamber with gas because the
volume of the load lock chamber is increased. Consequently, the
problem may cause the throughput of the apparatus to be
lowered.
SUMMARY OF THE INVENTION
[0008] Under such a situation, the present invention is provided in
consideration of the above-mentioned problems in the conventional
art. The object of the invention is to provide a new and improved
multi-chamber type processing apparatus which is capable of
substantially shortening a time until an object in the cassette has
been loaded into the vacuum processing chamber, a transportation
cycle of the object in the second transfer chamber and a time until
the processed object has been loaded into the caste, thereby to
improve the throughput of the apparatus.
[0009] In order to accomplish the above object, the present
invention provides a processing apparatus, which includes: a first
enclosure defining a first transfer space having an atmosphere of
atmospheric pressure; a load port site, in which a plurality of
load ports are aligned adjacently to the first transfer space, each
of the load ports being capable of mounting a cassette for
accommodating objects to be processed, the cassette having a door;
a plurality of door openers provided at the load ports respectively
to open and close the door of the cassette, the door openers each
allowing the first transfer space to communicate with an interior
of the cassette when the door opener opens the door of the
cassette; a second enclosure defining a second transfer space
having an atmosphere of vacuum or negative pressure; a plurality of
vacuum processing chambers arranged around the second transfer
space; a plurality of load lock chambers opposed to the load port
site over the first transfer space and also disposed between the
first transfer space and the second transfer space, the load lock
chambers each capable of accommodating only one object therein;
first gate valves arranged at the load lock chambers, respectively,
to separate the load lock chamber from the first transfer space;
second gate valves arranged at the load lock chambers,
respectively, to separate the load lock chamber from the second
transfer space; third gate valves arranged at the vacuum processing
chambers, respectively, to separate the vacuum processing chamber
from the second transfer space; a positioning unit that adjusts the
positions of an object and is arranged adjacent to the first
transfer space; a first transfer unit arranged in the first
transfer space to transfer an object among the cassette, the load
lock chambers and the positioning unit, the first transfer unit
having two holders each capable of holding only one object; and a
second transfer unit arranged in the second transfer space to
transfer the objects between the load lock chambers and the vacuum
processing chambers, the second transfer unit having two holders
each capable of holding only one object.
[0010] With the constitution mentioned above, owing to the adoption
of the single substrate processing apparatus capable of
accommodating the only one object in each load lock chamber, it is
possible to reduce the volume of each load lock chamber in
comparison with that of a "batch" type load lock chamber, whereby
both evacuation (vacuum formation) time and gas-supply time of the
load lock chambers can be shortened substantially. Additionally,
with the adoption of the above load lock chambers, it is possible
to reduce the number of delivering the object by the second
transfer unit arranged in the second transfer space having a
pressure reduced atmosphere since the positioning unit is arranged
adjacent to the first transfer unit. Each of the first and second
transfer units is capable of carrying two objects to be processed
and also transporting each object in a predetermined direction.
Therefore, even when adopting the load lock chambers each capable
of accommodating the single object, it is possible to accomplish
prompt delivery/replacement of the object between the first
transfer space and each load lock chamber and also between the load
lock chamber and the second transfer space. Consequently, with the
shortening of respective transportation time and gas-supply/exhaust
time, the throughput of the apparatus can be improved. Furthermore,
since the load lock chambers are arranged to oppose the load port
site over the first transfer space, the transportation distance for
the objects can be reduced to shorten the transportation time.
[0011] In the present invention, preferably, the first transfer
unit is movable in a direction parallel with an arrangement
direction of the load ports and the positioning unit is adjacent to
an end of the first transfer space with respect to the arrangement
direction of the load ports. If a linear motor drives to move the
first transfer unit in parallel with the arrangement of the load
ports, then it is possible to transfer the object promptly.
Further, owing to the above arrangement of the positioning unit
adjacent to the end of the first transfer space in the arrangement
direction of the load ports, there is no limitation to arrange the
respective load ports and the respective load lock chambers.
[0012] Further, the positioning unit may be arranged between two of
the load lock chambers. Then, since it is possible to reduce the
transportation distances of the object between the respective load
ports and the positioning unit and also between the positioning
unit and the respective load lock chambers relatively, the
transportation period of the object can be shortened to improve the
throughput of the apparatus furthermore.
[0013] Further, if the load lock chamber is provided with a cooling
unit for cooling the objects or a heating unit for heating the
objects, then there in no need to provide a cooling chamber or a
heating chamber in the neighborhood of the second transfer space.
As a result, since the steps of transporting the object to the
cooling chamber or the heating chamber can be eliminated, it is
possible to reduce the number of transporting the object by the
second transfer unit, improving the throughput of the apparatus
furthermore.
[0014] Further, if circulating the clean gas in the first transfer
space, it is possible to prevent particles from invading the first
transfer space, the load lock chambers and the opened cassette and
also possible to prevent the particles from adhering to the
objects, thereby improving the yield of products.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a schematic explanatory view showing a
multi-chamber type processing apparatus to which the present
invention is applicable;
[0016] FIG. 2 is a schematic sectional view showing a load port and
a cassette of FIG. 1;
[0017] FIG. 3 is a schematic perspective view showing a first
transfer arm of FIG. 1;
[0018] FIG. 4 is a schematic perspective view showing the load port
and the cassette of FIG. 1;
[0019] FIG. 5A is a schematic sectional view showing a load lock
chamber of FIG. 1 and FIG. 5B is a schematic plan view showing a
substrate holding part of FIG. 5A;
[0020] FIG. 6 is a schematic sectional view showing an
objectpositioning unit of FIG. 1;
[0021] FIG. 7 is a schematic perspective view showing a second
transfer arm of FIG. 1;
[0022] FIG. 8 is a schematic timing chart showing a processing
process of the processing apparatus of FIG. 1;
[0023] FIG. 9 is a schematic timing chart showing the processing
process of the processing apparatus of FIG. 1;
[0024] FIG. 10 is a schematic timing chart showing the processing
process of the processing apparatus of FIG. 1;
[0025] FIG. 11 is a schematic timing chart showing the processing
process of the processing apparatus of FIG. 1;
[0026] FIG. 12 is a schematic timing chart showing the processing
process of the processing apparatus of FIG. 1;
[0027] FIGS. 13A and 13B are schematic explanatory views for
explanation of another stopper applicable to the processing
apparatus of FIG. 1 where FIG. 13A shows a condition to put on and
take off the cassette and FIG. 13B shows a condition to fix the
cassette;
[0028] FIG. 14 is a schematic explanatory view showing another
multi-chamber type processing apparatus to which the present
invention is applicable;
[0029] FIG. 15 is a view for explanation of the effect of the
present invention, also showing both constitution and operation of
the processing apparatus of the embodiment;
[0030] FIG. 16 is a view for explanation of the effect of the
present invention, also showing both constitution and operation of
the processing apparatus in the first comparative example; and
[0031] FIG. 17 is a view for explanation of the effect of the
present invention, also showing both constitution and operation of
the processing apparatus in the second comparative example.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] With reference to the attached drawings, we now describe one
embodiment where the multi-chamber type processing apparatus of the
present invention is applied to a multi-chamber type processing
apparatus for forming various designated films on wafers, in
detail.
[0033] (1) General Structure of Processing Apparatus First,
referring to FIGS. 1 to 7, the whole structure of the multi-chamber
type processing apparatus 100 of the invention will be
described.
[0034] In FIG. 1, the processing apparatus 100 is provided, on a
first load port 102, with a plate 104 which is movable in the
generally-horizontal direction. Mounted on the plate 104 is a
open-and-close type (front-opening and unified-pot type) cassette
106, which can accommodate, for example, twenty-five pieces of
wafers W with a diameter of 300 mm each. As shown in FIGS. 1 and 2,
there are arranged, for example, three pins 108 on the plate 104.
On the other hand, coping with the pins 108, a recess 110 is formed
on the bottom of the cassette 106, as shown in FIG. 2. Further, as
shown in FIGS. 1, 2 and 4, the first load port 102 has a stopper
112 arranged to urge the back of the cassette 106 mounted on the
port 102 toward the outer face of an partitioning wall 122a of a
first transfer chamber 122 mentioned later. In order to move the
stopper 112 up and down, a not-shown driving mechanism is connected
to the stopper 112. The cassette 106 is provided, on its front
side, with an opening, to which a door 106a is detachably attached.
The cassette 106 has aflange 106b formed on the periphery of the
opening (see FIGS. 4 and 13A).
[0035] The processing apparatus 100 further includes a second load
port 114, a third load port 116 and a fourth load port 118 all
arranged adjacently in succession, substantially linearly together
with the first load port 102. The structures of the ports 114, 116
and 118 are the same as the structure of the first load port 102.
The first to fourth load ports 102, 114, 116 and 118 constitute a
load port site 120. Additionally, as shown in FIG. 1, the first to
fourth load ports 102, 114, 116 and 118 are arranged adjacently to
the first transfer chamber 122, i.e., a first transfer space,
respectively.
[0036] The first transfer chamber 122 is defined by a plurality of
wall members. In these wall members, an partitioning wall 122a
between the first transfer chamber 122 and the respective load
ports insulates an atmosphere of the first transfer chamber 122
from respective atmospheres of the load ports.
[0037] In the first transfer chamber 122, there is a first transfer
unit 124 shown in FIGS. 1 to 3. The first transfer unit 124 is
capable of carrying two wafers W simultaneously and transferring
them independently. That is, as shown in FIG. 3, the first transfer
unit 124 is formed by a pair of so-called "scalar" type
(articulated) transfer arms having substrate holding parts (fork
parts) 124a and 124b, respectively. The first and second substrate
holding parts 124a and 124b are movable in the vertical and
horizontal directions, mutually independently.
[0038] As shown in FIGS. 2 and 4, the first to fourth load ports
102, 114, 116 and 118 are provided, on the side of the first
transfer chamber 122, with door openers 126, respectively. Each
door opener 126 can open and close the detachable door 106a of the
cassette 106 by a holding part 126a movable up and down.
[0039] A gas supply line for supplying N.sub.2-gas as clean gas and
a gas discharge line (both not shown) are together connected with
the first transfer chamber 122. In this embodiment, N.sub.2-gas is
supplied from the top of the first transfer chamber 122 and
discharged from the bottom of the chamber 122. The first transfer
chamber 122 further includes a return line 128 connected thereto
for circulation of N.sub.2-gas, as shown in FIG. 1.
[0040] As shown in FIG. 1, a first load lock chamber 130 and a
second load lock chamber 132 are together connected with the first
transfer chamber 122. The first and second load lock chambers 130
and 132 are opposed to the load port site 120 respectively.
[0041] Gate valves G1, G2 are interposed between the first load
lock chamber 130 and the first transfer chamber 122 and between the
second load lock chamber 132 and the first transfer chamber 122,
respectively. Additionally, the first and second load lock chambers
130, 132 are connected with a second transfer chamber (vacuum
transfer chamber) 133, i.e. a second transfer space.
[0042] Gate valves G3, G4 are interposed between the first load
lock chamber 130 and the second transfer chamber 133 and also
between the second load lock chamber 132 and the second transfer
chamber 133, respectively.
[0043] The structures of the first and second load lock chambers
130 and 132 will be described. Note, since the first and second
load lock chambers 130 and 132 are generally identical to each
other in structure, the following descriptions are represented by
the second load lock chamber 132. Arranged in the second load loch
chamber 132 of FIG. 5A is a cooling plate 134, which also serves as
a table for mounting the wafer W thereon. The cooling plate 134 is
equipped with a built-in coolant circulation path 136 capable of
circulating coolant of a designated temperature. On the upper part
of the second load lock chamber 132, a first glass plate 138 is
arranged to form a part of ceiling of the second load lock chamber
132. Above the first glass plate 138, heating lamps 142 are
arranged through a second glass plate 140, for heating the wafer W
disposed in the second load lock chamber 132 to a designated
temperature.
[0044] A substrate holder 143 capable of holding the wafer W is
arranged in the second load lock chamber 132. The substrate holder
143 is disposed between the first glass plate 138 and the cooling
plate 134. The substrate holder 143 is provided with an elevating
mechanism 144 for moving the substrate, holder 143 up and down. The
substrate holder 143 connected with the elevating mechanism 144 is
arranged between the first glass plate 138 and the cooling plate
134. As shown in FIG. 5B, the substrate holder 143 is shaped to be
generally annular and has its inner diameter larger than the outer
diameter of the cooling plate 134. Attached to the substrate holder
143 at three positions thereon are three holder pins 143a, which
support the wafer W thereon. An exhaust pipe 146 for forming a
vacuum in the second load lock chamber 132 and a gas supply pipe
148 for supplying the second load lock chamber 132 with gas are
connected with the second load lock chamber 132. The second load
lock chamber 132 has a minimum volume capable of accommodating only
one wafer W, for example, the order of 5 liters.
[0045] Referring to FIG. 1 again, an object positioning unit 150
communicating with the first transfer chamber 122 is arranged
between the first load lock chamber 130 and the second load lock
chamber 132. The positioning unit 150 is opposed to the load port
site 120 and arranged below the intermediate position between the
first load lock chamber 130 and the second load lock chamber 132.
In the positioning unit 150, as shown in FIG. 6, there are provided
a rotating mechanism 152 for rotating the wafer W and a sensor 154
for detecting the position of the wafer W.
[0046] Further, a second transfer unit 156 is arranged in the
second transfer chamber 133 shown in FIG. 1. The second transfer
unit 156 is capable of retaining two wafers W simultaneously and
also transferring the wafers W independently. That is, the second
transfer unit 156 has a pair of "frog-leg" type transfer arms
equipped with first and second substrate holders (fork parts) 156a
and 156b, as shown in FIG. 7. The first substrate holder 156a and
the second substrate holder 156b are movable in the designated
horizontal directions, independently of each other. A not-shown
exhausting mechanism is connected with the interior of the second
transfer chamber 133, allowing the atmosphere in the second
transfer chamber 133 to be discharged.
[0047] First to fourth vacuum processing chambers 158, 160, 162 and
164 are connected with the periphery of the second transfer chamber
133. In the shown embodiment, the first to fourth vacuum processing
chambers 158, 160, 162 and 164 define processing chambers of plasma
CVD apparatus for performing film depositing processes,
respectively. Gate valves G5, G6, G7 and G8 are interposed between
the first to fourth vacuum processing chambers 158, 160, 162, 164
and the second transfer chamber 133, respectively. A partition
plate 166 insulates the first to fourth load ports 102, 114, 116
and 118 from the first transfer chamber 122, the first and second
load lock chambers 130, 132, the positioning unit 150, the second
transfer chamber 133 and the first to fourth vacuum processing
chambers 158, 160, 162 and 164 in an airtight manner. The
atmospheres of the first to fourth load ports 102, 114, 116 and 118
to which the cassette 106 is transported are identical to the
atmosphere of a clean room.
[0048] (2) Processing Order
[0049] Next, the processing order to apply film deposition on the
wafers W by the above-mentioned processing apparatus 100 will be
described with reference to FIGS. 1 to 12. The following
descriptions of the processing steps take example by the film
deposition process executed in only the first and fourth vacuum
processing chambers 158 and 164 for ease of understanding.
[0050] First, respective terms used in the timing charts for the
processing steps shown in FIGS. 8 to 12 will be described.
[0051] (a) L-Port: one of the first to fourth load ports 102, 114,
116 and 118
[0052] (b) L-Arm: the first transfer unit 124 (The first and second
substrate holders 124a and 124b are represented by P1 and P2,
respectively.)
[0053] (c) Ort: the object positioning unit 150
[0054] (d) LL1: the first load lock chamber 130
[0055] (e) LL2: the second load lock chamber 132
[0056] (f) T-Arm: the second transfer unit 156 (The first and
second substrate holders 156a and 156b are represented by P1 and
P2, respectively.)
[0057] (g) PM1: the first vacuum processing chamber 158
[0058] (h) PM2: the fourth vacuum processing chamber 164
[0059] (I) # 1-# n: serial number of the wafers W
[0060] (j) Door Open: opening the door 106a of the cassette
[0061] (k) Door Cls: closing the door 106a of the cassette
[0062] (l) Map: mapping of the wafer W in the cassette 106
[0063] Note, "XXX-YYY" in both L-Arm process and T-Arm process
represents to transport the wafer W from XXX to YYY. For example,
"LP-P1" means that the wafer W is transported from any one of the
first to fourth load ports 102, 114, 116 and 118 to the first
substrate holder 124a. Further, since the substantially-identical
operations are repeated in the period between 350 sec. and 1917
sec., the processing contents are abbreviated as shown in FIG. 10.
Next, referring to the timing charts of FIGS. 8 to 12, the
processing steps will be described.
[0064] As shown in FIG. 1, it is firstly executed to mount the
cassette 106 having the unprocessed wafer W accommodated therein,
for example, on the plate 104 of the third load port 116 so that
the pins 108 are engaged in the recess 110. Then, the plate 104
moves to the first transfer chamber 122. Thereafter, with the rise
of the stopper 112, the cassette 106 is urged and fixed to the
outer face of the partitioning wall 122a, as shown in FIGS. 1, 2
and 4. Since the cassette 106 is fixed in the above way, a pressure
in the first transfer chamber 122 is established higher than a
pressure in the clean room where the first to fourth load ports
102, 114, 116 and 118 are arranged, owing to the circulation of
N.sub.2-gas in the chamber 122. Therefore, even if a force of the
order of e.g. 100 g to 1 kg is applied on the cassette 106, it is
possible to fix the cassette 106 in position.
[0065] The following steps are carried out as shown in FIGS. 8 to
12, in sequence. Hereafter, we describe the actions of the first
and second transfer units 124 and 156 and the first and second load
lock chambers 130 and 132 mainly.
[0066] Upon positioning the cassette 106 in the above way, at the
step of FIG. 8, the holding part 126a of the door opener 126 hooks
the door 106a and detaches it from the cassette 106, as shown in
FIGS. 2 and 4. In this state, the interior of the cassette 106 is
communicated with the first transfer chamber 122 through a window
122b, i.e. a communication port, formed in the partitioning wall
122a. Then, the outer face of the partitioning wall 122a engages
with the flange 106b of the cassette 106 tightly.
[0067] Subsequently, a not-shown mapping sensor of the first
transfer unit 124 carries out mapping in order to search both
number and arrangement of the wafers W accommodated in the cassette
106. After completing the mapping, the first transfer unit 124
transports the wafer W in the cassette 106 to the object
positioning unit 150 as shown in FIGS. 1 and 2, and the positioning
unit 150 further carries out the positioning of the wafer W as
shown in FIG. 6.
[0068] Next, the aligned wafer W is mounted on the substrate holder
143 in, for example, the first load lock chamber 130 by the first
transfer unit 124 again. At this time, the interior of the first
load lock chamber 130 is maintained with an atmosphere of
substantial atmospheric pressure since the gate valve G1 is opened
while the gate valve G3 is closed. Thereafter, the gate valve G1 is
closed to discharge the atmosphere in the first load lock chamber
130, so that the pressure of the atmosphere in the first load lock
chamber 130 is lowered to be generally equal to the pressure of the
atmosphere in the second transfer chamber 133, for example, 100 m
Torr. At the same time, the wafer W on the substrate holder 143 is
elevated relatively to approach the heating lamps 142 and
simultaneously, they are lighted to heat the wafer W on the
substrate holder 143 to a designated temperature, for example,
500.degree. C. Note, even when the above-aligned wafer W is
transported into the second load lock chamber 132, there are
performed respective processing steps similar to the
above-mentioned steps.
[0069] After the interior of the first load lock chamber 130 has
reached the designated atmosphere of reduced pressure and also the
wafer W has been heated to the predetermined temperature, the gate
valve G3 is opened, so that the second transfer unit 156 takes the
wafer W out of the first load lock chamber 130 and further loads
the wafer W into the first vacuum processing chamber 158.
Thereafter, the gate valve G5 is closed and the first vacuum
processing chamber 158 is supplied with, for example, WF.sub.6 and
H.sub.2. In this state, the wafer W is heated in the first vacuum
processing chamber 158 by the lamps to form e.g. tungsten thin film
on the wafer W.
[0070] After being unloaded from the first vacuum processing
chamber 158, the wafer W having the thin film formed thereon is
mounted on the substrate holder 143 by the second transfer unit
156. Then, the interior of the second load lock chamber 132 is
maintained at a pressure reduced atmosphere substantially equal to
that of the interior of the second transfer chamber 133 since the
gate valve G4 is opened while the gate valve G2 is closed.
Thereafter, the gate valve G4 is closed to supply the second load
loch chamber 132 with gas, for example, N.sub.2-gas, so that the
pressure of the atmosphere in the second load lock chamber 132 is
increased to be generally equal to the pressure of the atmosphere
in first transfer chamber 122. At the same time, the substrate
holder 143 is lowered relatively to mount the wafer W on the
cooling plate 134, for cooling the wafer W to a designated
temperature, for example, 70.degree. C. Note, even when the wafer W
is transported into the first load lock chamber 130, there are
performed respective processing steps similar to the
above-mentioned steps.
[0071] After the interior of the second load lock chamber 132 has
reached the atmospheric pressure and also the wafer W has been
cooled to the predetermined temperature, the gate valve G2 is
opened, so that the first transfer unit 124 transfers the wafer W
in the second load lock chamber 132 to the first transfer chamber
122 and further loads the wafer W into the cassette 106 again. When
all the processed wafers W are collected into the cassette 106, as
shown in FIG. 12, the holding part 126b of the door opener 126
rises to attach the door 106a to the cassette 106. Next, the
stopper 112 is lowered and the plate 104 moves back to the position
to detach the cassette 106.
[0072] Each unit forming the processing apparatus 100 operates as
above. In this embodiment, several units operate simultaneously and
in combination, as shown in FIGS. 8 to 12. For example, at a point
of time over 150 sec. from the processing start shown in FIG. 8,
there are simultaneously carried out the transportation of the
wafer W by the first transfer unit 124, the positioning of the
wafer W by the object positioning unit 150, both evacuation and
heating of the wafer W in the first load lock chamber 130 and the
film deposition in the first and fourth vacuum processing chambers
158 and 164. Additionally, at a point of time over 250 sec. from
the processing start shown in FIG. 9, there are simultaneously
carried out the transportation of the wafer W by the first transfer
unit 124, the supply of the first load lock chamber 130 with
N.sub.2-gas and the cooling of the wafer W in the same chamber,
both evacuation and heating of the wafer W in the second load lock
chamber 132, the transportation of the wafer W by the second
transfer unit 156 and the film deposition in the fourth vacuum
processing chamber 164. Accordingly, since the processing apparatus
100 of the embodiment is capable of transporting the wafers W in
succession thereby to apply the designated processing on four
wafers simultaneously, it is possible to improve the throughput of
the apparatus.
[0073] In the above-mentioned embodiment, since each of the first
and second load lock chambers 130 and 132 has a minimum volume
capable of accommodating only one wafer, it is possible to perform
both evacuation and gas supply of the first and second load lock
chambers 130 and 132 promptly, shortening a period required for
adjusting the pressure of the first and second load lock chambers
130 and 132. Consequently, a period to deliver the wafer W between
the first transfer unit 124 and the second transfer unit 156 can be
shortened to improve the throughput of the apparatus. Further,
since the first transfer unit 124 and the second transfer unit 156
are provided with the first and second substrate holders 124a, 124b
and the first and second substrate holders 156a, 156b respectively,
it is possible to perform the delivery/replacement of the wafer W
promptly and further possible to improve the throughput of the
apparatus in spite of the formation of the first and second load
lock chambers 130, 132 of single wafer type.
[0074] Further, since the object positioning unit 150 is arranged
in the vicinity of the first transfer chamber 122 and the heating
and cooling units of the wafer W are arranged in the first and
second load lock chambers 130 and 132, it is possible to reduce the
number of delivering the wafer by the second transfer unit 156,
improving the throughput of the apparatus. Additionally, since the
object positioning unit 150 is disposed in a position between first
load lock chamber 130 and the second load lock chamber 132, it is
possible to shorten the transporting distance among the object
positioning unit 150, the first to fourth load ports 102, 114, 116
and 118, and the first and second load lock chambers 130 and 132.
The resulting narrowed transporting area of the first transfer unit
124 allows the transporting period to be shortened and the first
transfer chamber 122 to be small-sized. Since the cassette 106 is
fixed by the stopper 112, it is possible to prevent the cassette
106 from slipping out of place or falling from the first to fourth
load ports 102, 114, 116 and 118 during the loading/unloading of
the wafer W.
[0075] Although the preferred embodiment of the present invention
has been described with reference to the attached drawings, the
invention is not limited to the above-mentioned structure only. It
will be understood that various changes and modifications may be
made by those skilled in the art without departing from the present
technical spirit in the scope of claims of the invention.
[0076] Although the above embodiment has been described by an
example where the stopper urges the back face of the cassette
against the outer wall of the first transfer chamber, the invention
is not limited to this arrangement. For example, as shown in FIG.
13A, each of the first to fourth load ports 102, 114, 116 and 118
may be provided with a stopper 200 which is movable in the
circumferential direction to urge the flange part 106b formed close
to the door 106a of the cassette 106 against the partitioning wall
122a of the first transfer chamber 122 when fixing the cassette
106, as shown in Fig.13B.
[0077] In the above-mentioned embodiment, the positioning unit is
interposed between the first load lock chamber and the second load
lock chamber. In the modification, as shown in FIG. 14, there can
be provided a positioning unit 302 at one end of the first transfer
chamber 122 in the moving direction of the first transfer unit 124
(i.e. position adjacent to the left end of the first transfer
chamber 122 in FIG. 14) and another positioning unit 303 at another
end of the first transfer chamber 122 in a direction perpendicular
to the moving direction of the unit 124 (i.e. position opposite to
the fourth load port 118 over the first transfer chamber 122 in
FIG. 14).
[0078] Additionally, with no limitation to 25 pcs. of wafers
accommodated in the cassette, any number of wafers may be
accommodated in the cassette.
[0079] Each of the first and second transfer units may be adapted
so as to be able to carry three or more objects to be
processed.
[0080] In the above-mentioned embodiment, the first transfer unit
adopts the "scalar" type transfer arm, while the second transfer
unit adopts the "frog-leg" type transfer arm. In the modification,
the "frog-leg" type transfer unit may be employed as the first
transfer unit while adopting the "scalar" type transfer unit as
second transfer unit. Alternatively, both of the first and second
transfer units may be together formed by the "scalar" type transfer
units or the "frog-leg" type transfer units.
[0081] Without limiting to N.sub.2-gas for circulation of the first
transfer chamber, it may be circulated with clean gas of various
kinds, such as fresh air and various inert gases.
[0082] Moreover, although the processing apparatus of the above
embodiment has four load ports, two load lock chambers and four
vacuum processing chambers, these elements may be provided in
plural number, respectively. Without limiting to the single
positioning unit, the apparatus may be provided with two or more
positioning units.
[0083] In the above embodiment, all the first to fourth vacuum
processing chambers are formed as processing chambers for a CVD
apparatus, which perform the same film-deposition process
respectively. Of course, these vacuum processing chambers may be
constructed as processing chambers for performing different
film-deposition processes in the CVD apparatus. Alternatively,
these vacuum processing chambers may be provided for a variety of
plasma processing systems, such as etching system and ashing
system.
Detailed Description of Advantageous Effects of the Invention
[0084] Next, for detailed description of advantageous effects of
the invention, the order from unloading of the unprocessed wafer W
out of the cassette until loading the processed wafer into the
cassette again will be described with reference to the processing
charts of FIGS. 8 to 10 and also FIGS. 15 to 17. In FIGS. 15 to 17,
members related to the operations are represented by hatching.
Embodiment of the Invention
[0085] First, the operation in the embodiment will be described
with reference to FIG. 15. FIG. 15 is a schematic operational view
corresponding to FIG. 14.
[0086] [Operations in relation with the first transfer unit
124]
[0087] First, the operations related to the first transfer unit 124
will be described. Note, the following actions can be understood
with reference to the operations on and after 240 seconds of the
timing chart in FIG. 9.
[0088] Step 1: The first substrate holder 124a takes the
unprocessed wafer W (#8) out of the cassette 106 (LP-P1).
[0089] Step 2: The first transfer unit 124 moves to the front of
the positioning unit 302 and the second substrate holder 124b takes
the aligned unprocessed wafer W (#7) out of the positioning unit
124 (Ort-P2).
[0090] Step 3: The first substrate holder 124a loads the
unprocessed wafer W (#8) into the positioning unit 302
(P1-Ort).
[0091] Step 4: The first transfer unit 124 moves to the front of
the first load lock chamber 130 and the first substrate holder 124a
takes the processed wafer W (#2) out of the first load lock chamber
130 (LL1-P1).
[0092] Step 5: The second substrate holder 124b loads the
unprocessed wafer W (#7) into the first load lock chamber 130
(P2-LL1).
[0093] Step 6: The first transfer unit 124 moves to the front of
the cassette 106 and the first substrate holder 124a loads the
processed wafer W (#2) into the cassette 106 (P1-LP).
[0094] These steps 1 to 6 are shown with black arrows in FIG. 15.
These steps 1 to 6 as one cycle are carried out any number of
cycles repeatedly. Note, if the wafer W is taken in and out of the
first load lock chamber 130 at steps 4 and 5 in a certain cycle,
the wafer W will be taken in and out of the second load lock
chamber 132 at steps 4 and 5 in the sequent cycle.
[0095] In this operation, the total of time required at steps 2 and
3 amounts to 13 seconds, the total of time required at steps 4 and
5 amounts to 12 seconds and the total of time required at steps 6
and 1 amounts to 10 seconds. Accordingly, a time T1 required for
the operation of one cycle (steps 1 to 6) of the first transfer
unit 124 amounts to 35 seconds.
[0096] [Operations in relation with the second transfer unit
156]
[0097] Next, the operations related to the second transfer unit 156
will be described. Note, the following actions can be understood
with reference to the operations on and after 240 seconds of the
timing chart in FIG. 9.
[0098] Step 1: The first substrate holder 156a takes the processed
wafer W (#3) out of the first vacuum processing chamber 158
(PM1-P1).
[0099] Step 2: The second substrate holder 156b loads the
unprocessed wafer W (#5) into the first vacuum processing chamber
158 (P2-PM1).
[0100] Step 3: The second substrate holder 156b takes the
unprocessed wafer W (#6) out of the second load lock chamber 132
(LL2-P2).
[0101] Step 4: The first substrate holder 156a loads the processed
wafer W (#3) into the second load lock chamber 132 (P1-LL2).
[0102] These steps 1 to 4 are shown with white arrows in FIG. 15.
These steps 1 to 4 as one cycle are carried out any number of
cycles repeatedly. Note, if the wafer W is taken in and out of the
vacuum processing chamber 158 at steps 1 and 2 in a certain cycle
and the wafer W is taken in and out of the second load lock chamber
132 at steps 3 and 4 in the same cycle, the wafer W will be taken
in and out of the fourth vacuum processing chamber 164 at steps 1
and 2 in the sequent cycle and the wafer W will be taken in and out
of the first load lock chamber 130 at steps 3 and 4 in the same
cycle.
[0103] In this operation, the total of time required at steps 1 and
2 amounts to 18 seconds and the total of time required at steps 3
and 4 amounts to 16 seconds. Accordingly, a time T2 required for
the operation of one cycle (steps 1 to 4) of the second transfer
unit 156 amounts to 34 seconds.
[0104] [Operations in relation with the first load lock chamber
130]
[0105] Next, the actions related to the first load lock chamber 130
will be described. Note, the following actions can be understood
with reference to the operations on and after 260 seconds of the
timing chart in FIG. 9.
[0106] Step 1: The first substrate holder 124a takes the processed
wafer W (#2) out of the first load lock chamber 130 (LL1-P1).
[0107] Step 2: The second substrate holder 124b loads the
unprocessed wafer W (#7) into the first load lock chamber 130
(P2-LL1).
[0108] Step 3: Close the gate valve G1 to exhaust the first load
lock chamber 130 and subsequently, open the gate valve G3.
[0109] Step 4: The second substrate holder 156b takes the
unprocessed wafer W (#7) out of the first load lock chamber 130
(LL1-P2).
[0110] Step 5: The first substrate holder 156a loads the processed
wafer W (#4) into the first load lock chamber 130 (P1-LL1).
[0111] Step 6: Close the gate valve G3 to supply the first load
lock chamber 130 with gas (i.e., venting the first load lock
chamber 130) and subsequently, open the gate valve G1.
[0112] In this operation, the total of time required at steps 1 and
2 amounts to 12 seconds, the total of time required at steps 4 and
5 amounts to 16 seconds, and the times required at steps 3 and 6
amount to 26 seconds respectively. Accordingly, a time T3 required
for the operation of one cycle (steps 1 to 6) of the first load
lock chamber 130 amounts to 80 seconds.
[0113] [Operations in relation with the second load lock chamber
132]
[0114] Next, the operations related to the second load lock chamber
132 will be described. Note, the following actions can be
understood with reference to the operations on and after 220
seconds of the timing chart in FIG. 9.
[0115] Step 1: The first substrate holder 124a takes the processed
wafer W (#2) out of the second load lock chamber 132.
[0116] Step 2: The second substrate holder 124b loads the
unprocessed wafer W (#6) into the second load lock chamber 132.
[0117] Step 3: Close the gate valve G2 to exhaust the second load
lock chamber 132 and subsequently, open the gate valve G4.
[0118] Step 4: The second substrate holder 156b takes the
unprocessed wafer W (#6) out of the second load lock chamber
132.
[0119] Step 5: The first substrate holder 156a loads the processed
wafer W (#3) into the second load lock chamber 132.
[0120] Step 6: Close the gate valve G4 to supply the second load
lock chamber 132 with gas (i.e., venting the first load lock
chamber 132) and subsequently, open the gate valve G2.
[0121] Hereat, the actions related to the second load lock chamber
132 are substantially identical to those related to the first load
lock chamber 130. Accordingly, a time T3 required for the operation
of one cycle (steps 1 to 6) of the second load lock chamber 132
amounts to 80 seconds. [Operations in relation with the first
vacuum processing chamber 158]
[0122] Next, the operations related to the first vacuum processing
chamber 158 will be described. Note, the following actions can be
understood with reference to the operations on and after 240
seconds of the timing chart in FIG. 9.
[0123] Step 1: The first substrate holder 156a takes the processed
wafer W (#3) out of the first vacuum processing chamber 158
(PM1-P1).
[0124] Step 2: The second substrate holder 156b loads the
unprocessed wafer W (#5) into the first vacuum processing chamber
158 (P2-PM1).
[0125] Step 3: Close the gate valve G5 and carry out a designated
process for the unprocessed wafer W (#5) in the first vacuum
processing chamber 158. After completing the process, open the gate
valve G5.
[0126] In this operation, the total of time required at steps 1 and
2 amounts to 18 seconds and the time required at step 3 amounts to
62 seconds. Accordingly, a time T4 required for the operation of
one cycle (steps 1 to 3) of the first vacuum processing chamber 158
amounts to 80 seconds. [Operations in relation with the fourth
vacuum processing chamber 164]
[0127] Next, the operations related to the fourth vacuum processing
chamber 164 will be described. Note, the following actions can be
understood with reference to the operations on and after 270
seconds of the timing chart in FIG. 9.
[0128] Step 1: The first substrate holder 156a takes the processed
wafer W (#4) out of the fourth vacuum processing chamber 158
(PM2-P1).
[0129] Step 2: The second substrate holder 156b loads the
unprocessed wafer W (#6) into the fourth vacuum processing chamber
164 (P2-PM2).
[0130] Step 3: Close the gate valve G8 and carry out a designated
process for the unprocessed wafer W (#6) in the fourth vacuum
processing chamber 164. After completing the process, open the gate
valve G8.
[0131] Hereat, the operations elated to the fourth vacuum
processing chamber 164 are substantially identical to those related
to the first vacuum processing chamber 158. Accordingly, a time T4
required for the operation of one cycle (steps 1 to 3) of the
fourth vacuum processing chamber 164 amounts to 80 seconds.
[0132] As mentioned above;
[0133] the cycle time T1 of the first transfer unit 124 is 35
seconds;
[0134] the cycle time T2 of the second transfer unit 156 is 34
seconds;
[0135] the cycle times T3 of the load lock chambers 130 and 132 are
80 seconds respectively; and
[0136] the cycle times T4 of the vacuum processing chambers 158 and
162 are 80 seconds respectively. Thus, there can be found the
following relationship:
[0137] T1.apprxeq.T2.apprxeq.T3/number of load lock chambers
[0138] .apprxeq.T4/number of vacuum processing chambers
[0139] The establishment of this relationship means enabling loss
of time that the constituents 124, 156, 130, 132, 158 and 162 cease
the operations to be minimized, also implying the possibility of
improving the throughput of the whole apparatus.
[0140] The reason of improving the throughput will be described
below.
[0141] In the conventional apparatus, the cycle time of the load
lock chambers is remarkably longer than the cycle time of the
vacuum processing chambers (T4/number of vacuum processing
chambers) and therefore, the process of the load lock chambers
constitutes a "rate controlling" step of the whole apparatus. The
reason is because the load lock chamber capable of accommodating
two wafers requires a lot of time to supply and exhaust the chamber
with gas. Therefore, in place of the conventional provision of two
load lock chambers each capable of accommodating two wafers W, the
apparatus of the invention provides two load lock chambers each
capable of accommodating the single wafer W only, in other words,
the chambers of small capacity thereby to reduce a time required to
supply and exhaust the respective load lock chambers with gas, by
the order of half.
[0142] However, it might be noted that if each load lock chamber
only accommodates the single wafer W therein, it becomes impossible
to deliver the wafer between the load lock chamber and the vacuum
processing chamber and also between the cassette and the load lock
chamber so quickly. Nevertheless, this problem can be solved by the
present invention since the apparatus is provided with the first
and second transfer units each having two wafer holders.
[0143] In order to improve the throughput of the apparatus, it is
necessary to make the cycle time T1 of the first transfer unit 124
and the cycle time T2 of the second transfer unit 156 even. For
this purpose, the apparatus of the invention has the positioning
unit 302 not arranged in the second transfer chamber 133 but the
first transfer chamber 122. Because of the (atmospheric) atmosphere
or the near (atmospheric) atmosphere in the first transfer chamber
122, the first transfer unit 124 has a simple structure that it is
not required to cope with the vacuum atmosphere, allowing of
high-speed action. On the contrary, due to the vacuum atmosphere or
the near vacuum atmosphere in the second transfer chamber 133, the
second transfer unit 156 has to be constructed to meet the vacuum
atmosphere in complication, causing the difficulty in high-speed
operation. Additionally, owing to the handling of the wafers at a
normal temperature or the near temperature, the substrate holders
124a and 124b of the first transfer unit 124 can be provided with
rubber materials, so that it is possible to prevent the wafers from
falling in spite of the high-speed operation. While, since the
second transfer unit 156, which is required to hold the wafers W of
high temperature immediately after processing, is provided with no
rubber materials resisting such a high temperature, it is difficult
to operate the unit at a high speed. In the transfer unit in charge
of the positioning unit 302, the cycle time of operation is
increased due to the addition of two steps in one cycle. For this
reason, the present apparatus has the positioning unit 302 arranged
on the side of the first transfer chamber 122 equipped with the
first transfer unit 124 capable of high-speed operation thereby to
make the cycle time T1 of the first transfer unit 124 and the cycle
time T2 of the second transfer unit 156 even. In case of the
positioning unit 302 on the side of the second transfer chamber
133, the cycle time T1 is shortened by 13+.alpha. seconds: the
former comes from to the elimination of steps 2 and 3 from the
action related to the first transfer unit 124; and the latter comes
from the deletion of time for the first transfer unit 124 to move
to the positioning unit 302. On the other hand, since the operation
related to the second transfer unit 156 is accompanied with the
actions corresponding to steps 2 and 3 of the first transfer unit
124 and furthermore a time (.beta.seconds) for the unit 156 to move
to the positioning unit 302, the cycle time T2 is increased by
13.times.k+.beta. seconds (k: a ratio in operation speed of the
first transfer unit 124 to the second transfer unit 156), so that
the cycle time T2 is remarkably larger than the cycle time T1.
Note, according to our trial calculation of throughput under the
same conditions but the above arrangement, it is found that the
arrangement of the positioning unit 302 on the side of the second
transfer chamber 133 has a throughput of 72 pcs./ hour, while the
arrangement of the positioning unit 302 on the side of the first
transfer chamber 122 has a throughput of 90 pcs./hour.
[0144] Further, according to the present apparatus, since the first
transfer unit 124 has two substrate holders 124a and 124b, a
positioning time (5 seconds) by the positioning unit 302 does not
have any influence on the cycle time T1 of the first transfer unit
124. Conversely, if the first transfer unit 124 has the single
substrate holder only, the unit 124 has to stand ready for the
completion of positioning of the wafer after the wafer has been
delivered to the positioning unit 302 by the first transfer unit
124. While, if the first transfer unit 124 has two substrate
holders, there is no need for the unit 124 to stand by the
completion of positioning (see steps 2 and 3 of the actions related
to the first transfer unit 124).
[0145] As mentioned above, according to the present apparatus, the
relationship among the cycle times T1 to T4 of the constituents
124, 156, 130, 132, 158 and 162 is optimized to allow of the
improvement of throughput.
[0146] In the above way, we have described the process in the
respective vacuum processing chambers by 62 seconds in each
processing time. When the processing time at the vacuum processing
chamber takes 102 seconds, it is possible to realize the similar
throughput by using three vacuum processing chambers.
[0147] We now describe the following comparative examples in order
to facilitate understanding of the effects of the present
apparatus.
[0148] 1st. Comparative Example
[0149] First, the first comparative example will be described with
reference to FIG. 16. The comparative example of FIG. 16 differs
from the embodiment of FIG. 15 in that each of load lock chambers
130' and 132' is capable of accommodating two wafers, and each of
first and second transfer units 124', 156' has a single substrate
holder 124a, 156a. As to the other structures, the comparative
example of FIG. 16 is identical to the embodiment of FIG. 15.
[0150] [Operations in relation with the first transfer unit
124']
[0151] First, the operations related to the first transfer unit
124' will be described.
[0152] Step 1: The first transfer unit 124' takes the unprocessed
wafer W out of the cassette 106.
[0153] Step 2: The first transfer unit 124' moves to the front of
the positioning unit 302 and loads the unprocessed wafer W into the
positioning unit 302.
[0154] Step 3: The positioning unit 302 carries out positioning of
the unprocessed wafer W (the time required is 5 seconds).
[0155] Step 4: The first transfer unit 124' takes the unprocessed
wafer W out of the positioning unit 302.
[0156] Step 5: The first transfer unit 124' moves to the front of
the first load lock chamber 130' and loads the unprocessed wafer W
into the first load lock chamber 130'.
[0157] Step 6: The first transfer unit 124' takes the processed
wafer W out of the first load lock chamber 130'.
[0158] Step 7: The first transfer unit 124' moves to the front of
the cassette 106 and loads the processed wafer W into the cassette
106).
[0159] These steps 1 to 7 are shown with black arrows in FIG. 16.
The cycle of steps 1 to 7 is carried out repeatedly while
alternating the load lock chambers (130' and 132') where the wafers
are to be delivered.
[0160] The cycle time T1' of the first transfer unit 124' amounts
to 40 seconds since a time (5 seconds) at step 3 is added to the
cycle time T1 of the first transfer unit 124.
[0161] [Operations in relation with the second transfer unit
156']
[0162] Next, the operations related to the second transfer unit
156' will be described.
[0163] Step 1: The second transfer unit 156' takes the processed
wafer W out of the first vacuum processing chamber 158.
[0164] Step 2: The second transfer unit 156' loads the processed
wafer W into the second load lock chamber 132'.
[0165] Step 3: The second transfer unit 156' takes the unprocessed
wafer W out of the second load lock chamber 132'.
[0166] Step 4: The second transfer unit 156' loads the unprocessed
wafer W into the first vacuum processing chamber 158.
[0167] These steps 1 to 4 are shown with white arrows in FIG. 16.
The cycle of steps 1 to 4 is carried out repeatedly while
alternating the load lock chamber (130' or 132') and the vacuum
processing chambers (158, 164) where the wafers are to be
delivered.
[0168] The time of steps 1 to 4 related to the second transfer unit
156' (the cycle time T2' of the second transfer unit 156') amounts
to 34 sec. as similar to the case of the second transfer unit 156.
Note, although the amount of rotation of the second transfer unit
156' is twice as large as that of the second transfer unit 156, an
increment in rotation time is neglected in the above
measurement.
[0169] [Operations in relation with the first load lock chamber
130']
[0170] Next, the operations related to the first load lock chamber
130' will be described.
[0171] Step 1: The first transfer unit 124' loads the unprocessed
wafer W into the first load lock chamber 130'.
[0172] Step 2: The first transfer unit 124' takes the processed
wafer W out of the first load lock chamber 130'.
[0173] Step 3: Close the gate valve G1 to exhaust the first load
lock chamber 130' and subsequently, open the gate valve G3.
[0174] Step 4: The second transfer unit 156' loads the processed
wafer W into the first load lock chamber 130'.
[0175] Step 5: The second transfer unit 156' takes the unprocessed
wafer W out of the first load lock chamber 130'.
[0176] Step 6: Close the gate valve G3 to supply the first load
lock chamber 130' with gas and subsequently, open the gate valve
G1.
[0177] In this operation, the total of time of steps 1, 2, 4 and 5
related to the first load lock chamber 130' is generally equal to
that of steps 1, 2, 4 and 5 related to the first load lock chamber
130. However, the times of steps 3 and 6 related to the first load
lock chamber 130' increase to 52 sec. respectively, corresponding
to the increase in volume of the load lock chamber.
[0178] Accordingly, the time required at steps 1 to 6 related to
the first load lock chamber 130' (the cycle time T3' of the first
load lock chamber 130') amounts to 132 sec. Note, the cycle time of
the second load lock chamber 132' amounts to 132 sec., too.
[0179] [Operations in relation with the first vacuum processing
chamber 158]
[0180] Next, the operations related to the first vacuum processing
chamber 158 will be described.
[0181] Step 1: The second transfer unit 156' loads the unprocessed
wafer W into the first vacuum processing chamber 158.
[0182] Step 2: Close the gate valve G5 and carry out a designated
process for the unprocessed wafer W in the first vacuum processing
chamber 158. After completing the process, open the gate valve
G5.
[0183] Step 3: The second transfer unit 156' takes the processed
wafer W out of the first vacuum processing chamber 158.
[0184] In this operation, the time required at steps 1, 2 and 3
related to the first vacuum processing chamber 158 (the cycle time
T4' of the first vacuum processing chamber 158) amounts to 80 sec.,
as similar to the embodiment of FIG. 15. Note, the cycle time of
the fourth vacuum chamber 164 also amounts to 80 sec.
[0185] In the first comparative example,
[0186] the cycle time T1' of the first transfer unit 124' is 40
sec.;
[0187] the cycle time T2' of the second transfer unit 156' is 34
sec.;
[0188] the cycle times T3' of the first and second load lock
chambers 130' and 132' are 132 sec. respectively; and
[0189] the cycle times T4' of the first and fourth vacuum
processing chambers 158 and 164 are 80 seconds, respectively. Thus,
in this example, there is greatly collapsed the above-mentioned
relationship of:
[0190] T1.apprxeq.T2.apprxeq.T3/number of load lock chambers
[0191] .apprxeq.T4/number of vacuum processing chambers
[0192] Since the throughput of the whole apparatus is occupied by
the longest cycle time (the cycle time of the load lock chamber in
this case), it will be understood that the apparatus of the 1st.
comparative example has a remarkably-small throughput in comparison
with that of the apparatus of the invention.
[0193] 2nd. Comparative Example
[0194] Next, the second comparative example will be described with
reference to FIG. 17. The comparative example of FIG. 17 differs
from the embodiment of FIG. 15 in that each of the first and second
transfer unit 124', 156' has the single substrate holder 124a,
156a, and a buffer B (temporary space for wafer) is arranged in the
second transfer chamber 133. As to the other structures, the
comparative example of FIG. 17 is identical to the embodiment of
FIG. 15.
[0195] [Operations in relation with the first transfer unit
124']
[0196] First, the operations related to the first transfer unit
124' will be described.
[0197] Step 1: The first transfer unit 124' moves to the front of
the first load lock chamber 130 and takes the processed wafer W out
of the first load lock chamber 130.
[0198] Step 2: The first transfer unit 124' moves to the front of
the cassette 106 and loads the processed wafer W into the cassette
106.
[0199] Step 3: The first transfer unit 124' moves to the front of
the positioning unit 302 and takes the aligned wafer W out of the
positioning unit 302.
[0200] Step 4: The first transfer unit 124' moves to the front of
the first load lock chamber 130 and loads the unprocessed wafer W
into the first load lock chamber 130.
[0201] Step 5: The first transfer unit 124' moves to the front of
the cassette 106 and takes the unprocessed wafer W out of the
cassette 106.
[0202] Step 6: The first transfer unit 124' moves to the front of
the positioning unit 302 and loads the unprocessed wafer W into the
positioning unit 302.
[0203] These steps 1 to 6 are shown with black arrows in FIG.
17.
[0204] The cycle of steps 1 to 6 is carried out repeatedly while
alternating the load lock chambers (130 and 132) where the wafers
are to be delivered.
[0205] Comparing with the cycle time T1 of the embodiment, the
cycle time T1" of the first transfer unit 124' is increased by 10
sec. to 45 sec. because of the elongated moving distance of the
first transfer unit 124' per cycle.
[0206] [Operations in relation with the second transfer unit
156']
[0207] Next, the operations related to the second transfer unit
156' will be described.
[0208] Step 1: The second transfer unit 156' takes the processed
wafer W out of the first vacuum processing chamber 158.
[0209] Step 2: The second transfer unit 156' loads the processed
wafer W into the buffer B.
[0210] Step 3: The second transfer unit 156' takes the unprocessed
wafer W out of the second load lock chamber 132.
[0211] Step 4: The second transfer unit 156' loads the unprocessed
wafer W into the first vacuum processing chamber 158.
[0212] Step 5: The second transfer unit 156' takes the processed
wafer W out of the buffer B.
[0213] Step 6: The second transfer unit 156' loads the processed
wafer W into the second load lock chamber 132.
[0214] These steps 1 to 6 are shown with white arrows in FIG. 17.
The cycle of steps 1 to 6 is carried out repeatedly while
alternating the load lock chamber (130 or 132) and the vacuum
processing chamber (158 or 164) where the wafers are to be
delivered.
[0215] Comparing with the cycle time T2 of the embodiment, the
cycle time T2" of the second transfer unit 156' is increased to 50
sec. by the addition of delivering time (16 sec.) of the wafer W to
and from the buffer B (steps 2 and 5).
[0216] [Operations in relation with the first load lock chamber
130]
[0217] Next, the operations related to the first load lock chamber
130 will be described.
[0218] Step 1: The first transfer unit 124' takes the processed
wafer W out of the first load lock chamber 130.
[0219] Step 2: The first transfer unit 124' loads the unprocessed
wafer W into the first load lock chamber 130.
[0220] Step 3: Close the gate valve G1 to exhaust the first load
lock chamber 130 and subsequently, open the gate valve G3.
[0221] Step 4: The second transfer unit 156' takes the unprocessed
wafer W out of the first load lock chamber 130.
[0222] Step 5: The second transfer unit 156' loads the processed
wafer W into the first load lock chamber 130.
[0223] Step 6: Close the gate valve G3 to supply the first load
lock chamber 130 with gas and subsequently, open the gate valve
G1.
[0224] There is no change between the number of action steps
related to the first load lock chamber 130 of this comparative
example and the number of action steps related to the first load
lock chamber 130 of the embodiment. Nevertheless, as understood
with reference to the descriptions of the actions related to the
first and second transfer units 124' and 156' of this comparative
example, another wafer W is not accommodated in the first load lock
chamber 130 immediately after the wafer W has been unloaded out of
the load lock chamber 130. Therefore, comparing with the cycle time
T3 of the first load lock chamber 130 of the embodiment, the cycle
time T3" of this comparative example is increased by 30 sec. to 110
sec. Note, the cycle time of the second load lock chamber 132
amounts to 110 sec. similarly.
[0225] [Operations in relation with the first vacuum processing
chamber 1581]
[0226] Next, the operations related to the first vacuum processing
chamber 158 will be described.
[0227] Step 1: The second transfer unit 156' loads the unprocessed
wafer W into the first vacuum processing chamber 158.
[0228] Step 2: Close the gate valve G5 and carry out a designated
process for the unprocessed wafer W in the first vacuum processing
chamber 158. After completing the process, open the gate valve
G5.
[0229] Step 3: The second transfer unit 156' takes the processed
wafer W out of the first vacuum processing chamber 158.
[0230] There is no change between the number of action steps
related to the first vacuum processing chamber 158 of this
comparative example and the number of action steps related to the
same chamber 158 of the embodiment. Nevertheless, as understood
with reference to the descriptions of the actions related to the
second transfer unit 156' of this comparative example, another
wafer W is not accommodated in the first vacuum processing chamber
158 immediately after the wafer W has been unloaded out of the same
chamber 158. Therefore, comparing with the cycle time T4 of the
first processing chamber 158 of the embodiment, the cycle time T4"
of this comparative example is increased by 16 sec. to 96 sec.
Note, the cycle time of the second vacuum processing chamber 164
amounts to 96 sec. similarly.
[0231] In the second comparative example,
[0232] the cycle time T1" of the first transfer unit 124' is 45
sec.;
[0233] the cycle time T2" of the second transfer unit 156' is 50
sec.;
[0234] the cycle times T3" of the first and second load lock
chambers 130 and 132 are 110 sec. respectively; and
[0235] the cycle times T4" of the first and second vacuum
processing chambers 158 and 164 are 96 seconds respectively.
[0236] That is, not only does the above-mentioned relationship (T1
.apprxeq.T2.apprxeq.T3/number of load lock
chambers.apprxeq.T4/number of vacuum processing chambers) collapse,
but also the cycle times of the individual units are increased.
Therefore, it will be understood that the apparatus of the 2nd.
comparative example has also a remarkably-small throughput in
comparison with that of the apparatus of the invention.
[0237] As can be understood from the above descriptions, according
to the apparatus of the present invention, it is possible to
improve the throughput of the whole apparatus remarkably.
[0238] Note, in the above-mentioned embodiment of the invention,
the processing apparatus employs the transfer units each having two
arm parts provided with, at respective ends thereof, with the
substrate holders, as shown in FIGS. 3 and 7. In the modification,
the present invention is applicable to the apparatus having the
transfer units each having the single arm part provided, at the
leading end, with two substrate holders, accomplishing the
advantageous effects.
* * * * *