U.S. patent application number 10/503947 was filed with the patent office on 2005-07-21 for substrate support mechanism for semiconductor processing system.
Invention is credited to Hiroki, Tsutomu, Saeki, Hiroaki.
Application Number | 20050155823 10/503947 |
Document ID | / |
Family ID | 27750698 |
Filed Date | 2005-07-21 |
United States Patent
Application |
20050155823 |
Kind Code |
A1 |
Hiroki, Tsutomu ; et
al. |
July 21, 2005 |
Substrate support mechanism for semiconductor processing system
Abstract
A supporting mechanism (12A) is used for transferring a target
substrate (W) in cooperation with a transfer arm (32), in a
semiconductor processing system. The supporting mechanism includes
first and second holding portions (38A to 38C, 40A to 40C) each
configured to be moved up and down and transfer a substrate to and
from the transfer arm. The first and second holding portions are
configured to be moved relative to each other in a vertical
direction without spatially interfering with each other, and
support substrates at substantially the same horizontal coordinate
position. The supporting mechanism further includes first and
second drives (46, 48) configured to move the first and second
holding portions up and down, and a controller (68) configured to
control the first and second drives. The controller is arranged to
control the first and second drives to alternatively support a
substrate by the first and second holding portions.
Inventors: |
Hiroki, Tsutomu;
(Nirasaki-shi, JP) ; Saeki, Hiroaki;
(Nirasaki-shi, JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Family ID: |
27750698 |
Appl. No.: |
10/503947 |
Filed: |
August 18, 2004 |
PCT Filed: |
January 29, 2003 |
PCT NO: |
PCT/JP03/00845 |
Current U.S.
Class: |
187/401 |
Current CPC
Class: |
H01L 21/68742 20130101;
H01L 21/68 20130101; H01L 21/6875 20130101; H01L 21/68714 20130101;
Y10S 414/139 20130101 |
Class at
Publication: |
187/401 |
International
Class: |
B66B 011/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 25, 2002 |
JP |
2002-47509 |
Claims
1. A supporting mechanism used for transferring a target substrate
in cooperation with a transfer arm, in a semiconductor processing
system, the supporting mechanism comprising: first and second
holding portions each configured to be moved up and down and
transfer a substrate to and from the transfer arm, the first and
second holding portions being configured to be moved relative to
each other in a vertical direction without spatially interfering
with each other, and support substrates at substantially the same
horizontal coordinate position; first and second drives configured
to move the first and second holding portions up and down; and a
controller configured to control the first and second drives, the
controller being arranged to control the first and second drives to
alternatively support a substrate by the first and second holding
portions.
2. The supporting mechanism according to claim 1, wherein each of
the first and second holding portions comprises a plurality of
lifter pins having top ends, on which a substrate is placed.
3. The supporting mechanism according to claim 1, wherein each of
the first and second holding portions comprises a holder plate
having a top face, on which a substrate is placed.
4. The supporting mechanism according to claim 1, wherein one of
the first and second holding portions comprises a plurality of
lifter pins having top ends, on which a substrate is placed, and
the other of the first and second holding portions comprises a
holder plate having a top face, on which a substrate is placed.
5. The supporting mechanism according to claim 1, wherein each of
the first and second holding portions comprises a lifter pin and a
holder plate, the lifter pin and the holder plate respectively
having a top end and a top face, on which a substrate is
placed.
6. The supporting mechanism according to claim 2, wherein each of
the first and second holding portions comprises a base frame, and
the plurality of lifter pins stand on the base frame.
7. The supporting mechanism according to claim 6, wherein the base
frames of the first and second holding portions are disposed not to
overlap with each other in plan view, and comprise extension
portions extending toward each other and mutually beyond tips of
the extension portions, and one of the lifter pins is supported
near each of the tips of the extension portion.
8. The supporting mechanism according to claim 6, wherein the base
frames of the first and second holding portions are stacked one
above the other, and configured to be moved up and down by
respective driving rods.
9. The supporting mechanism according to claim 3, wherein the
holder plates comprise extension portions disposed not to overlap
with each other in plan view, and extending toward each other and
mutually beyond tips of the extension portions.
10. The supporting mechanism according to claim 4, wherein the
plurality of lifter pins are disposed around a central axis of the
holder plate.
11. The supporting mechanism according to claim 10, wherein the
plurality of lifter pins are supported by a base frame disposed
below the holder plate, and the holder plate and the base frame are
configured to be moved up and down by respective driving rods.
12. The supporting mechanism according to claim 8, wherein the
driving rods form a coaxial structure.
13. The supporting mechanism according to claim 2, wherein the
plurality of lifter pins are configured to be respectively driven
by actuators belonging to the first drive or the second drive, and
the number of the actuators is the same as the number of lifter
pins.
14. The supporting mechanism according to claim 2, wherein the
plurality of lifter pins are substantially disposed on one circle
at substantially regular intervals.
15. The supporting mechanism according to claim 1, further
comprising a pair of auxiliary holding portions for holding a
substrate, disposed at positions sandwiching the first and second
holding portions and configured to be moved up and down, wherein a
position where the pair of auxiliary holding portions hold a
substrate is above a position where the first and second holding
portions hold a substrate.
16. The supporting mechanism according to claim 1, wherein the
first and second holding portions are disposed in an airtight
chamber configured to be vacuum-exhausted, the first and second
drives are disposed outside the airtight chamber and connected to
the first and second holding portions respectively through driving
rods, and portions of the airtight chamber, where the driving rods
penetrate, are respectively provided with longitudinally flexible
bellows, which maintain an interior of the airtight chamber
airtight.
17. The supporting mechanism according to claim 1, wherein the
controller controls the first and second drives such that the
respective numbers of substrates supported by the first and second
holding portions become almost the same.
18. The supporting mechanism according to claim 1, wherein the
controller controls the first and second drives such that
first-state substrates are respectively supported by the first
holding portion, and second-state substrates are respectively
supported by the second holding portion.
19. The supporting mechanism according to claim 11, wherein the
driving rods form a coaxial structure.
Description
TECHNICAL FIELD
[0001] The present invention relates to a supporting mechanism used
for transferring a target substrate, such as a semiconductor wafer,
in cooperation with a transfer arm, in a semiconductor processing
system. The term "semiconductor process" used herein includes
various kinds of processes which are performed to manufacture a
semiconductor device or a structure having wiring layers,
electrodes, and the like to be connected to a semiconductor device,
on a target substrate, such as a semiconductor wafer or an LCD
substrate, by forming semiconductor layers, insulating layers, and
conductive layers in predetermined patterns on the target
substrate.
BACKGROUND ART
[0002] In the process of manufacturing semiconductor integrated
circuits, a wafer is subjected to various processes, such as
film-formation, etching, oxidation, and diffusion. Owing to the
demands of increased miniaturization and integration of
semiconductor integrated circuits, the throughput and yield
involving these processes need to be increased. In light of this,
there is a semiconductor processing system of the so-called cluster
tool type, which has a plurality of process chambers for performing
the same process, or a plurality of process chambers for performing
different processes, connected to a common transfer chamber. With a
system of this type, various steps can be performed in series,
without exposing a wafer to air. For example, Jpn. Pat. Appln.
KOKAI Publication Nos. 2000-208589 and 2000-299367 disclose a
semiconductor processing system of the cluster tool type.
[0003] In a semiconductor processing system of the cluster tool
type, there are a plurality of transfer arms for transferring a
semiconductor wafer. Each transfer arm is arranged to extend,
contract, and rotate or move horizontally. The transfer arms
sequentially transfer a wafer among them from a wafer cassette to
processing apparatuses or vice versa.
[0004] In general, transfer of a wafer between transfer arms is not
directly performed therebetween, but via a supporting mechanism
disposed therebetween, which can move the wafer up and down, or a
buffer table having such a supporting mechanism. The wafer is
transferred onto the supporting mechanism or buffer table by one of
the transfer arms, and is then transferred from the supporting
mechanism or buffer table by the other of the transfer arms.
[0005] Depending on the processing manner of a wafer, the wafer is
temporarily kept waiting in a transfer chamber in the middle of
transfer, and another wafer is transferred by priority. In this
case, the transfer chamber may be provided with a supporting
mechanism or buffer table as that described above. For example,
Jpn. Pat. Appln. KOKAI Publication Nos. 4-69917, 9-223727, and
2001-176947 disclose a supporting mechanism or buffer table of this
kind.
[0006] In handling semiconductor wafers for a film-formation
process, for example, there is a case where processed wafers are
accompanied by thin films sticking to the bottom, as well as the
top as a matter of course. In this case, if lifter pins or the like
come into direct contact with the bottom of wafers to handle them,
unprocessed wafers are contaminated with film particles transferred
from the lifter pins.
[0007] Furthermore, the supporting mechanisms disclosed in the
publications mentioned above include two lifters for moving a wafer
up and down, which are used at the same time to transfer a wafer.
Accordingly, it is difficult to use the supporting mechanisms
flexibly in light of the situation.
DISCLOSURE OF INVENTION
[0008] An object of the present invention is to provide a substrate
supporting mechanism for a semiconductor processing system, which
includes two holding portions alternatively usable in light of the
situation, and has a compact structure.
[0009] According to an aspect of the present invention, there is
provided a supporting mechanism used for transferring a target
substrate in cooperation with a transfer arm, in a semiconductor
processing system, the supporting mechanism comprising:
[0010] first and second holding portions each configured to be
moved up and down and transfer a substrate to and from the transfer
arm, the first and second holding portions being configured to be
moved relative to each other in a vertical direction without
spatially interfering with each other, and support substrates at
substantially the same horizontal coordinate position;
[0011] first and second drives configured to move the first and
second holding portions up and down; and
[0012] a controller configured to control the first and second
drives, the controller being arranged to control the first and
second drives to alternatively support a substrate by the first and
second holding portions.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 is a schematic plan view showing a semiconductor
processing system including a substrate supporting mechanism
according to a first embodiment of the present invention;
[0014] FIG. 2 is a sectional view showing an intermediate chamber
having a load-lock function and provided with the supporting
mechanism shown in FIG. 1;
[0015] FIG. 3 is a perspective view of the supporting mechanism
shown in FIG. 1;
[0016] FIG. 4 is a plan view of the supporting mechanism shown in
FIG. 1;
[0017] FIG. 5 is an enlarged partial view showing the supporting
structure of a reciprocation rod used in the supporting mechanism
shown in FIG. 1;
[0018] FIG. 6 is a view schematically showing the placement of
actuators used in a supporting mechanism according to a second
embodiment of the present invention;
[0019] FIG. 7 is a plan view showing the placement of lifter pins
used in the supporting mechanism shown in FIG. 6;
[0020] FIG. 8 is a plan view showing base frames used in a
supporting mechanism according to a third embodiment of the present
invention;
[0021] FIG. 9 is a perspective view showing a supporting mechanism
according to a fourth embodiment of the present invention;
[0022] FIG. 10 is a plan view showing the supporting mechanism
shown in FIG. 9;
[0023] FIG. 11 is a perspective view showing a supporting mechanism
according to a fifth embodiment of the present invention;
[0024] FIG. 12 is a plan view showing the supporting mechanism
shown in FIG. 11;
[0025] FIG. 13 is a perspective view showing a supporting mechanism
according to a sixth embodiment of the present invention;
[0026] FIG. 14 is a plan view showing the supporting mechanism
shown in FIG. 13; and
[0027] FIG. 15 is a view showing a supporting mechanism according
to a modification of the sixth embodiment.
BEST MODE FOR CARRYING OUT THE INVENTION
[0028] Embodiments of the present invention will be described
hereinafter with reference to the accompanying drawings. In the
following description, the constituent elements having
substantially the same function and arrangement are denoted by the
same reference numerals, and a repetitive description will be made
only when necessary.
First Embodiment
[0029] FIG. 1 is a schematic plan view showing a semiconductor
processing system including a substrate supporting mechanism
according to a first embodiment of the present invention.
[0030] As shown in FIG. 1, the processing system 2 includes a
plurality of, e.g., four processing apparatuses 4A, 4B, 4C, and 4D,
an almost hexagonal common transfer chamber 6, first and second
intermediate chambers (load-lock chambers) 8A and 8B, and a thin
and long entrance transfer chamber 10. The intermediate chambers 8A
and 8B are respectively provided with substrate supporting
mechanisms 12A and 12B. Each of the common transfer chamber 6 and
first and second intermediate chambers 8A and 8B are formed of an
airtight chamber, which can be vacuum exhausted.
[0031] More specifically, the processing apparatuses 4A to 4D are
respectively connected to four sides of the almost hexagonal common
transfer chamber 6, and the first and second intermediate chambers
8A and 8B are respectively connected to the other two sides
thereof. In other words, the processing system 2 has a structure of
the cluster tool type in which the processing apparatuses and
intermediate chambers are connected to and around the common
transfer chamber 6. The entrance transfer chamber 10 is connected
to the first and second intermediate chambers 8A and 8B in common.
The processing apparatuses 4A to 4D and first and second
intermediate chambers 8A and 8B are connected to the common
transfer chamber 6 respectively through gate valves G1 to G4, and
G5 and G6, which are airtightly opened and closed. The first and
second intermediate chambers 8A and 8B are connected to the
entrance transfer chamber 10 respectively through gate valves G7
and G8, which are airtightly opened and closed.
[0032] The four processing apparatuses 4A to 4D are designed to
perform the same process or different processes on a target
substrate or semiconductor wafer in a vacuum atmosphere. The common
transfer chamber 6 is provided with first transfer means 14
disposed therein at a position to access the two intermediate
chambers 8A and 8B and four processing apparatuses 4A to 4D. The
first transfer means 14 is formed of an articulated arm that can
extend, contract, and rotate. The first transfer means 14 has two
picks 14A and 14B, which can independently extend and contract in
opposite directions, so that it can handle two wafers at a time.
Alternatively, the first transfer means 14 may have only one
pick.
[0033] The entrance transfer chamber 10 has a long thin box-type
configuration in which an inactive gas, such as N.sub.2 gas, or
clean air is circulated. One or more cassette tables, e.g., three
cassette tables 16A, 16B, and 16C in this example, are disposed on
one side of this laterally long box. The cassette tables 16A, 16B,
and 16C are configured to place cassettes 18A to 18C thereon,
respectively.
[0034] Each of the cassettes 18A to 18C is structured to store,
e.g., 25 wafers W at most, at regular intervals in the vertical
direction. Each of the cassettes 18A to 18C has an airtight
structure filled with, e.g., an N.sub.2 gas atmosphere. Wafers are
transferred into and from the entrance transfer chamber 10 through
gate doors 20A, 20B, and 20C disposed correspondingly to the
cassette tables 16A to 16C.
[0035] The entrance transfer chamber 10 is provided with second
transfer means 22 disposed therein, for transferring wafers W in
its longitudinal direction. The second transfer means 22 is
supported on and slides along a guide rail 24 that extends in the
longitudinal direction at the center of the entrance-transfer
chamber 10. The guide rail 24 has an actuating mechanism, such as a
linear motor, built therein. The linear motor moves the second
transfer means 22 on the guide rail 24 in an X-direction.
[0036] An alignment device or orientor 26 for performing alignment
of a wafer is disposed at one end of the entrance transfer chamber
10. The orientor 26 includes a rotary table 28, which is rotated by
a driving motor (not shown), along with a wafer W placed thereon.
An optical sensor 30 is disposed beside the rotary table 28, for
detecting the periphery of the wafer W. The optical sensor 30 is
used to detect the direction and misalignment of the notch or
orientation flat of the wafer W.
[0037] The second transfer means 22 has two transfer arms 32 and 34
formed of articulated arms and disposed on upper and lower sides.
The transfer arms 32 and 34 respectively have fork-like picks 32A
and 34A at their distal ends, on each of which a wafer W is
directly held. Each of the transfer arms 32 and 34 can extend and
contract in a radial direction R from the center. The transfer arms
32 and 34 can be controlled to extend and contract independently of
each other. The transfer arms 32 and 34 can integratedly rotate in
the angular direction .theta. relative to a base 36.
[0038] Next, an explanation will be given of the supporting
mechanisms 12A and 12B respectively disposed in the intermediate
chambers 8A and 8B. Since the two supporting mechanisms 12A and 12B
have completely the same structure, only one of them, e.g., the
supporting mechanism 12A will be exemplified.
[0039] FIG. 2 is a sectional view showing an intermediate chamber
having a load-lock function and provided with the supporting
mechanism shown in FIG. 1. FIGS. 3 and 4 are a perspective view and
a plan view, respectively, of the supporting mechanism shown in
FIG. 1.
[0040] As shown in FIGS. 2 to 4, the supporting mechanism 12A
includes a plurality of, e.g., two in this example, base frames 38
and 40, each of which is formed of a thin plate bar bent to form a
numeral "7" shape, and made of, e.g., aluminum or ceramic. The two
base frames 38 and 40 are disposed not to overlap with each other
in the plan view, so that they do not hit or interfere with each
other when they are moved up and down. As shown in FIGS. 3 and 4,
the base frames 38 and 40 have extension portions 39 and 41, which
extend toward each other and mutually beyond their tips into cut
spaces in the base frames.
[0041] Each of the base frames 38 and 40 is provided with a
plurality of, e.g., three in this embodiment, lifter pins 38A to
38C or 40A to 40C standing upward therefrom. The lifter pins 38A to
38C and 40A to 40C are made of ceramic, such as Al.sub.2O.sub.3.
Each group of lifter pins 38A to 38C and 40A to 40C supports a
wafer W, while their top ends are in direct contact with the
bottoms of the wafers.
[0042] As shown also in FIG. 4, each group of lifter pins 38A to
38C and 40A to 40C are disposed along one common circle 42 at
regular intervals (intervals of about 120 degrees). The number of
lifter pins disposed on one base frame 38 or 40 needs to be at
least three. The two groups of the lifter pins 38A to 38C and 40A
to 40C may be respectively disposed along different circles.
[0043] The two actuators 46 and 48 are disposed at the bottom plate
44 (see FIG. 2) of the intermediate chamber 8A, and used for the
two base frames 38 and 40, respectively. The actuators 46 and 48
include reciprocation rods 50 and 52, which extend through holes 54
and 56 formed in the bottom plate 44, and connected or fixed at the
top to the bottoms of the base frames 38 and 40, respectively. The
actuators 46 and 48 can move up and down the base frames 38 and 40
independently of each other.
[0044] The actuators 46 and 48 are set to give the same stroke of
the vertical movement to the lifter pins 38A to 38C and lifter pins
40A to 40C. Furthermore, the uppermost and lowermost positions of
the top ends of the lifter pins 38A to 38C are essentially the same
as the uppermost and lowermost positions of the top ends of the
lifter pins 40A to 40C. In other words, the lifter pins 38A to 38C
and lifter pins 40A to 40C share essentially the same position
where a wafer W is transferred to and from the first transfer means
14 or second transfer means 22. However, even if the two members
have different vertical strokes or different uppermost and
lowermost positions, a wafer W can be transferred to and from the
first and second transfer means 14 and 22, using vertical movement
of the first and second transfer means 14 and 22.
[0045] Those portions of the bottom plate 44, where the
reciprocation rods 50 and 52 penetrate, are respectively provided
with bellows 58 and 60 each formed of, e.g., a longitudinally
flexible metal accordion hose. More specifically, as shown in FIG.
5, the reciprocation rods 50 and 52 are respectively inserted in
the bellows 58 and 60. The upper ends of the bellows 58 and 60 are
airtightly connected to the bottoms of the base frames 38 and 40,
respectively. The lower ends of the bellows 58 and 60 are
airtightly fixed to the bottom of the bottom plate 44 by screws 66
each through a seal member 62 and an attachment ring 64.
[0046] The bellows 58 and 60 thus arranged maintain the interior of
the intermediate chamber 8A airtight, while allowing the
reciprocation rods 50 and 52 to be moved up and down. A vertical
movement controller 68 formed of, e.g., a microcomputer is used to
control the operation of the actuators 46 and 48.
[0047] Each of the intermediate chambers 8A and 8B has a port 70
for feeding an inactive gas, such as N2 gas, and an exhaust port 72
connected to a vacuum exhaust section (not shown), wherein the
ports are formed in, e.g., the bottom of the chamber. This
arrangement is used to set the pressure inside the intermediate
chambers 8A and 8B between a vacuum atmosphere and atmospheric
pressure atmosphere, as needed.
[0048] Next, an explanation will be given of an outline of the flow
of a wafer W, in relation to the semiconductor processing system
shown in FIG. 1.
[0049] First, an unprocessed wafer W is picked up from one of the
cassettes placed on the three cassette tables 16A to 16C, e.g., the
cassette 18C placed on the cassette table 16C. At this time, one of
the transfer arms of the second transfer means 22, e.g., the
transfer arm 32, is operated to pick up and hold the wafer W from
the cassette 18C by the pick 32A. Then, the second transfer means
22 is moved in the X-direction to transfer the wafer W to the
orientor 26.
[0050] Then, an unprocessed wafer W, which has been aligned by the
orientor 26, is taken out of the rotary table 28 to make the rotary
table 28 free. For this purpose, the other transfer arm 34, which
is unoccupied, is operated to pick up and hold, by the pick 34A,
the wafer W from the rotary table 28.
[0051] Then, the transfer arm 32 is operated to place the
unprocessed wafer held on the pick 32A onto the unoccupied rotary
table 28. This wafer is subjected to alignment by the time when a
next unprocessed wafer is transferred thereto. Then, the second
transfer means 22 is moved in the X-direction to transfer the
unprocessed wafer, which has been taken out of the rotary table 28
by the other transfer arm 34, to one of the two intermediate
chambers 8A and 8B, e.g., the intermediate chamber 8A.
[0052] Then, the gate valve G7 is opened to open the intermediate
chamber 8A, which has been adjusted in pressure. At this time, a
processed wafer that has been subjected to a predetermined process,
such as a film-formation process or etching process, is waiting on
one of the groups of the lifter pins, e.g., lifter pins 40A to 40C
in the intermediate chamber 8A.
[0053] Then, the unoccupied transfer arm 32 is operated to pick up
and hold, by the pick 32A, the processed wafer W waiting on the
lifter pins 40A to 40C. Then, the other transfer arm 34 is operated
to place the unprocessed wafer held on the pick 34A onto the other
group of lifter pins 38A to 38C. On the other hand, the processed
wafer is returned back to the original cassette by the second
transfer means 22.
[0054] After the unprocessed wafer W is placed on the lifter pins
38A to 38C, the gate valve G7 is closed to make the intermediate
chamber 8A airtight. Then, the pressure in the intermediate chamber
8A is adjusted by vacuum exhaust. Then, the gate valve G5 is opened
to cause the intermediate chamber 8A to communicate with the common
transfer chamber 6, which has been set to have a vacuum atmosphere
in advance. Then, the first transfer means 14 in the common
transfer chamber 6 is operated to pick up the unprocessed wafer W.
At this time, if a processed wafer is held on the first transfer
means 14, the processed wafer is replaced with the unprocessed
wafer, using the two picks 14A and 14B of the first transfer means
14.
[0055] Then, the unprocessed wafer W is sequentially subjected to
the necessary processes in the processing apparatuses 4A to 4D, for
example. After the necessary processes are completed, the processed
wafer W is returned back to the original cassette, through a route
reverse to that described above. At this time, the processed wafer
W can be transferred through either one of the two intermediate
chambers 8A and 8B. When the processed wafer W is held in the
intermediate chambers 8A and 8B, the lifter pins 40A to 40C are
used, which belong to a group other than the group used for holding
the unprocessed wafer W. As a consequence, the unprocessed wafer W
is prevented, as far as possible, from being contaminated by
contaminants, such as thin films.
[0056] Next, a detailed explanation will be given as to how a wafer
W is transferred in the intermediate chamber 8A. Wafer transfer in
the other intermediate chamber 8B is performed in the same
manner.
[0057] In this embodiment, as described above, unprocessed wafers W
are handled by a group of lifter pins different from a group used
for handling processed wafers W, to prevent contamination of the
wafers W. For example, the three lifter pins 38A to 38C disposed on
the base frame 38 are exclusively used for supporting unprocessed
wafers W, while the three lifter pins 40A to 40C disposed on the
other base frame 40 are exclusively used for supporting processed
wafers W. The following explanation will take as an example a case
where an unprocessed wafer W transferred in from the entrance
transfer chamber 10, and a processed wafer W is replaced with the
unprocessed wafer W.
[0058] First, the lifter pins 40A to 40C of the base frame 40
supporting the processed wafer W are placed at an upper position,
and the unoccupied lifter pins 38A to 38C of the other base frame
38 are placed at a lower position. In this sate, the unoccupied
pick 32A is moved in a horizontal direction into the intermediate
chamber 8A, and inserted into a position below the processed wafer
W (between the wafer W and base frame 40). Then, the lifter pins
40A to 40C are moved down to transfer the processed wafer W onto
the pick 32A. Then, the pick 32A is moved backward to retreat from
the intermediate chamber 8A.
[0059] Then, the other pick 34A holding the unprocessed wafer W is
moved in a horizontal direction into the intermediate chamber 8A.
Then, the other base frame 38 at the lower position is moved up, so
that the lifter pins 38A to 38C receive the unprocessed wafer W
from below. Then, the unoccupied pick 34A is moved backward to
retreat from the intermediate chamber 8A. As a consequence, the
processed wafer W is replaced with the unprocessed wafer W.
Basically the same operation is performed when a wafer W is
transferred between the common transfer chamber 6 and intermediate
chamber 8A.
[0060] In the operation described above, the lifter pins 38A to 38C
keep supporting the unprocessed wafer W until the wafer W is
transferred onto the first transfer means 14, after receiving the
wafer W from the second transfer means 22. During this time, the
lifter pins 40A to 40C support no wafer W. On the other hand, the
lifter pins 40A to 40C keep supporting the processed wafer W until
the wafer W is transferred onto the second transfer means 22, after
receiving the wafer W from the first transfer means 14. During this
time, the lifter pins 38A to 38C support no wafer W. In summary,
the lifter pins 38A to 38C and the lifter pins 40A to 40C
alternatively support a wafer W. This matter is also common to the
following embodiments. The two groups of the lifter pins 38A to 38C
and lifter pins 40A to 40C can be arbitrarily set to be used either
for unprocessed wafers W or for processed wafers W.
[0061] The first embodiment includes a plurality of, e.g., two,
base frames 38 and 40, each having a plurality of, e.g., three,
lifter pins 38A to 38C or 40A to 40C disposed thereon. One group of
lifter pins 38A to 38C is exclusively used for transferring
unprocessed wafers W, and the other group of lifter pins 40A to 40C
is exclusively used for transferring processed wafers W. As a
consequence, unprocessed wafers W are prevented from being
contaminated by substances or particles derived from thin
films.
[0062] Furthermore, even if one of the base frames or actuators
malfunctions, the other base frame can keep operating to move up
and down to transfer a wafer W, as described above. Accordingly,
this improves the flexibility of usage.
[0063] The first embodiment includes the two base frames 38 and 40,
but may have a third base frame or more, which are disposed not to
interfere with the two base frames 38 and 40, and each provided
with lifter pins, as described above.
[0064] The supporting mechanisms disclosed in the publication
mentioned in "Background Art" include two lifters for moving a
wafer up and down, and transfer a wafer, using the two lifters at
the same time. Accordingly, it is difficult to use the supporting
mechanisms flexibly in light of the situation. More specifically,
for example, the supporting mechanism disclosed in Jpn. Pat. Appln.
KOKAI Publication No. 9-223727 includes two sets of target
substrate supporting means (support pins), which can be moved
independently of each other. The two sets of supporting means
support only one target substrate in cooperation with each other,
or the two sets of supporting means simultaneously and respectively
support an unprocessed target substrate and a processed target
substrate.
[0065] On the other hand, the substrate supporting mechanism
according to the first embodiment includes two (a plurality of)
sets of target substrate supporting means (corresponding to the two
base frames 38 and 40 in this embodiment), which are disposed not
to interfere with each other, and support target substrates W at
substantially the same horizontal coordinate position to transfer
them to and from a transfer unit. The two (a plurality of) sets of
target substrate supporting means alternatively support a target
substrate (only one set of supporting means supports one target
substrate at a time). In other words, when one set of supporting
means supports a target substrate, the other set of supporting
means supports no target substrate. Accordingly, the supporting
mechanism according to the first embodiment has a structure
completely different from that of the prior art described above.
This matter is also common to the following embodiments.
Second Embodiment
[0066] The first embodiment includes a plurality of, e.g., two,
base frames each provided with a plurality of, e.g., three, lifter
pins 38A to 38C or 40A to 40C. Instead, there may be lifter pins
38A to 38C and 40A to 40C respectively provided with actuators one
by one. In such an aspect, FIG. 6 is a view schematically showing
the placement of actuators used in a supporting mechanism according
to a second embodiment of the present invention. FIG. 7 is a plan
view showing the placement of lifter pins used in the supporting
mechanism shown in FIG. 6.
[0067] As shown in FIG. 6, the lifter pins 38A to 38C and 40A to
40C are divided into two groups, i.e., a first group of lifter pins
38A to 38C and a second group of lifter pins 40A to 40C. The lifter
pins are respectively provided with actuators 80A to 80C and 82A to
82C correspondingly disposed therebelow.
[0068] As shown in FIG. 7, the actuators 80A to 80C and 82A to 82C
are disposed along one circle, but FIG. 6 shows them on one plane,
for the sake of comprehension. It may be arranged such that one
group of actuators 80A to 80C are disposed on one circle, and the
other group of actuators 82A to 82C are disposed along a different
circle. The lifter pins 38A to 38C and 40A to 40C are respectively
connected to the tips of the reciprocation rods 84A to 84C and 86A
to 86C of the actuators 80A to 80C and 82A to 82C. The vertical
movement of the actuators 80A to 80C and 82A to 82C are controlled
by a vertical movement controller 68. Those portions of the
intermediate chamber bottom plate 44, where the reciprocation rods
84A to 84C and 86A to 86C penetrate, are respectively provided with
bellows 88.
[0069] The actuators 80A to 80C connected to one group of lifter
pins 38A to 38C are operated to perform synchronous vertical
movement. Similarly, the actuators 82A to 82C connected to the
other group of lifter pins 40A to 40C are operated to perform
synchronous vertical movement. The group of actuators 80A to 80C
and the group of actuators 82A to 82C can be controlled
independently of each other to perform vertical movement.
[0070] Also in the second embodiment, each group of lifter pins,
i.e., the group of lifter pins 38A to 38C or lifter pins 40A to
40C, are controlled to synchronously move up and down. As a
consequence, the second embodiment can provide the same operation
and effect as those of the first embodiment described above. For
example, one group of lifter pins 38A to 38C is exclusively used
for transferring unprocessed wafers W, and the other group of
lifter pins 40A to 40C is exclusively used for transferring
processed wafers W.
Third Embodiment
[0071] The first embodiment includes a plurality of, e.g., two,
base frames each provided with a plurality of, e.g., three, lifter
pins 38A to 38C or 40A to 40C. Instead, there may be base frames 38
and 40 provided with no lifter pins 38A to 38C and 40A to 40C, but
configured to function as holder plates, each of which comes into
direct contact with the bottom of a wafer W to support it by the
top face. In such an aspect, FIG. 8 is a plan view showing base
frames (holder plates) used in a supporting mechanism according to
a third embodiment of the present invention.
[0072] As shown in FIG. 8, the two base frames 38 and 40 are
provided with no lifter pins thereon. Each of the base frames 38
and 40 come into direct contact with the bottom of a wafer W to
support the wafer W. It should be noted that the two base frames 38
and 40 are arranged not to interfere with a pick, e.g., pick 32A,
during transfer of a wafer. For this reason, the base frames 38 and
40 shown in FIG. 8 has a smaller size than the base frames 38 and
40 of the first embodiment shown in FIG. 3. The third embodiment
can also provide the same operation and effect as those of the
first embodiment described above.
Fourth Embodiment
[0073] The second embodiment includes no base frames, but includes
lifter pins directly connected to reciprocation rods. The third
embodiment includes no lifter pins, but includes base frames
configured to directly support a wafer. These features of them can
be combined for use. In such an aspect, FIG. 9 is a perspective
view showing a supporting mechanism according to a fourth
embodiment of the present invention. FIG. 10 is a plan view showing
the supporting mechanism shown in FIG. 9.
[0074] As shown in FIGS. 9 and 10, this supporting mechanism
includes lifter pins 38A and 40A provided with an associated
structure the same as that shown in FIGS. 6 and 7. Specifically,
the two lifter pins 38A and 40A are directly connected to the
reciprocation rod 84A of an actuator 80A and the reciprocation rod
86A of an actuator 82A, respectively. However, the supporting
mechanism includes no other lifter pins 38B, 38C, 40B, and 40C (see
FIG. 3), but includes base frames 38 and 40 the same as those of
the third embodiment shown in FIG. 8 to compensate for the function
of the omitted lifter pins. Specifically, each of the base frames
38 and 40 is arranged to directly support the bottom of a wafer. In
this case, however, the base frames 38 and 40 do not have a numeral
"7" shape shown in FIG. 4, but have, e.g., a "U" shape, formed by
excluding the portion that supports the lifter pin 38A or 40A.
[0075] In this case, the lifter pin 38A and base frame 38 form one
group and are synchronously moved up and down. Also, the other
lifter pins 40A and base frame 40 form one group and are
synchronously moved up and down. The fourth embodiment can also
provide the same operation and effect as those of the first
embodiment described above.
Fifth Embodiment
[0076] Each of the first to fourth embodiments cannot handle two
wafers at a time, but handles always only one wafer. However, means
for secondarily supporting a wafer may be disposed to handle a
plurality of, e.g., two, wafers at a time. In such an aspect, FIG.
11 is a perspective view showing a supporting mechanism according
to a fifth embodiment of the present invention. FIG. 12 is a plan
view showing the supporting mechanism shown in FIG. 11.
[0077] As shown in FIGS. 11 and 12, a supporting mechanism
according to any one of the first to fourth embodiments is disposed
at the center of an intermediate chamber 8A. A pair of
reciprocation rods 90 and 92 are disposed outside the vertical
movement area where a wafer W is moved up and down by the
supporting mechanism. The reciprocation rods 90 and 92 are disposed
at positions shifted by 90 degrees from gate valves G5 and G7
provided on opposite sides of the intermediate chamber 8A, so that
they do not interfere with a pick 14A, 14B, 32A, or 34A to be
inserted when a wafer is transferred into and out of the
intermediate chamber 8A. FIGS. 11 and 12 shows a case where the
supporting mechanism according to the first embodiment is disposed
at the center of the intermediate chamber 8A. Those portions of the
bottom plate 44 of the intermediate chamber, where the
reciprocation rods 90 and 92 penetrate, are respectively provided
with bellows 94 and 96, which maintain the interior of the
intermediate chamber airtight, while allowing the reciprocation
rods 90 and 92 to be moved up and down.
[0078] The reciprocation rods 90 and 92 are respectively moved up
and down by actuators (not shown) disposed therebelow, which
perform synchronous vertical movement. The reciprocation rods 90
and 92 are moved up and down by a stroke larger than that of the
reciprocation rods 50 and 52. The reciprocation rods 90 and 92 may
be connected to each other at the bottom, so that only one actuator
suffices for them.
[0079] Support plates 98 and 100 made of, e.g., ceramic are
respectively fixed to the tops of the reciprocation rods 90 and 92,
and horizontally extend toward the center of the intermediate
chamber 8A. The support plates 98 and 100 have a "T" shape in this
embodiment, with top faces to hold a wafer W transferred by the
first and second transfer means 14 and 22, while they are in direct
contact with the bottom of the wafer W. The other intermediate
chamber 8B is also provided with the same supporting mechanism as
that disposed in the intermediate chamber 8A, as described
above.
[0080] According to the fifth embodiment having the arrangement
described above, the lifter pins 38A to 38C and 40A to 40C are
operated, as in the first embodiment, while the pair of support
plates 98 and 100 hold an unprocessed wafer W at a higher position,
as shown in FIG. 11, for example. In other words, one wafer W is
kept waiting at a higher position by the support plates 98 and 100,
while another wafer is transferred therebelow into and from the
intermediate chamber. As a consequence, the flexibility in handling
target substrates improves.
Sixth Embodiment
[0081] The embodiments described above include a plurality of,
e.g., two, base frames 38 and 40, which are disposed not to overlap
with each other in the plan view. Instead, there may be base frames
38 and 40 disposed to overlap with each other in the plan view,
i.e., to be stacked one above the other, thereby reducing the
occupied space in the plan view. In such an aspect, FIG. 13 is a
perspective view showing a supporting mechanism according to a
sixth embodiment of the present invention. FIG. 14 is a plan view
showing the supporting mechanism shown in FIG. 13.
[0082] As shown in FIGS. 13 and 14, a first base frame 38 is
disposed above a second base frame 40, so that they vertically
overlap with each other. The first base frame 38 is supported at
the center by a first reciprocation rod, e.g., rod 50. The second
base frame 40 is supported at the center by a second reciprocation
rod, e.g., rod 52. The first and second reciprocation rods 50 and
52 form a coaxial structure, and can be moved up and down
independently of each other. The two rods 50 and 52 may be disposed
in parallel with each other, in place of the coaxial structure.
[0083] The first reciprocation rod 50 is connected to a first
actuator, e.g., actuator 46 (see FIG. 2) at the bottom. The second
reciprocation rod 52 is connected to a second actuator, e.g.,
actuator 48 (see FIG. 2) at the bottom. A longitudinally flexible
first bellows 110 is interposed between the first base frame 38 and
second base frame 40, and covers the first reciprocation rod 50. A
longitudinally flexible second bellows 112 is interposed between
the second base frame 40 and a transfer chamber bottom (not shown),
and covers second reciprocation rod 52.
[0084] The second base frame 40 is formed of an almost circular
plate, which is provided with a plurality of, e.g., three in this
example, lifter pins 40A to 40C standing on the periphery. The top
ends of the lifter pins 40A to 40C extend beyond the first base
frame 38, to support a wafer W thereon. The lifter pins 40A to 40C
are disposed on the periphery of the second base frame 40 at almost
regular intervals in the angular direction.
[0085] On the other hand, the first base frame 38 has a deformed
triangle shape, which is formed by curving the three sides of a
regular triangle toward the center, so that it does not interfere
with the three lifter pins 40A to 40C. The first base frame 38 is
configured to come into direct contact with a wafer W to hold it by
the top face. In the sixth embodiment, the top ends of the lifter
pins 40A to 40C of the second base frame 40 are moved up beyond the
first base frame 38, when they support a wafer W.
[0086] The sixth embodiment can provide an operation similar to
that of the first embodiment described above. Specifically, the top
face of the first base frame 38, and the lifter pins 40A to 40C of
the second base frame 40 alternatively support a wafer W.
[0087] Since the two base frames 38 and 40 are stacked one above
the other, the base frames 38 and 40 can be smaller and reduce the
occupied area in the plan view. As a consequence, a pick with a
smaller tip opening angle can be used for transferring a wafer
without interfering with the base frames 38 and 40. Furthermore,
during transfer of a wafer, the supporting mechanism can be easily
controlled to perform vertical movement.
[0088] The sixth embodiment includes the first base frame 38
configured to support a wafer W by the top face. Instead, there may
be a first base frame 38 provided with lifter pins. In such an
aspect, FIG. 15 is a view showing a supporting mechanism according
to a modification of the sixth embodiment. As shown in FIG. 15, the
first base frame 38 is provided with a plurality of, e.g., three in
this example, lifter pins 38A to 38C standing on the periphery. The
lifter pins 38A to 38C are configured to support a wafer W by the
top ends.
[0089] In the embodiments described above, a supporting mechanism
is disposed in the intermediate chambers 8A and 8B, each formed of
an airtight chamber that can be vacuum exhausted. Instead, a
supporting mechanism may be disposed in a free space within the
entrance transfer chamber 10 or common transfer chamber 6, so that
it functions as a waiting position of a wafer.
[0090] In the embodiments described above, where the base frames 38
and 40 or support plates 98 and 100 are configured to support a
wafer W by the top face, the top face comes into direct contact
with the bottom of the wafer W. Instead, the top face may be
provided with a plurality of projections having a height of about 1
mm and a diameter of about 5 mm, so that the projections come into
contact with the bottom of a wafer to support it. Alternatively,
the top face may be provided with a recess to hold a wafer W
therein.
[0091] In the embodiments described above, the controller performs
control such that one group of lifter pins or base frame supports
unprocessed wafers W, while the other group of lifter pins or base
frame supports processed wafers. Instead, discriminatory use of a
plurality of lifter pins or base frames may be determined,
depending on the type of a process (film-formation, etching, etc)
to be performed on wafers W, the temperature of wafers W (timing
before or after heating or cooling of wafers W), or other
conditions of wafers W, (also taking into consideration a case
where a supporting mechanism according to each of the embodiments
is used in a common transfer chamber 6 or the like).
[0092] In the embodiments described above, the lifter pins or base
frames are made of the same material. Instead, the lifter pins or
base frames may be respectively made of different materials (for
example, a heat-resistant material, heat-conductive material, and
so forth), depending on some conditions of wafers W to be
supported.
[0093] Furthermore, the controller may be arranged such that the
respective numbers of wafers supported by the lifter pins or base
frames become almost the same. This arrangement allows the time
period between cleaning operations of wafer-contact portions to be
increased, and also allows the service life of members, such as a
bellows, of a supporting mechanism to be longer. Incidentally, a
supporting mechanism according to the present invention may also be
provided with a mechanism for rotating a wafer W.
[0094] In the embodiments described above, a semiconductor wafer is
handled as a target substrate. The present invention may also be
applied to a glass substrate or LCD substrate.
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