U.S. patent application number 09/493230 was filed with the patent office on 2001-11-29 for substrate conveying system in semiconductor manufacturing apparatus.
Invention is credited to Nakahara, Takashi, Shimoike, Hiroshi.
Application Number | 20010047225 09/493230 |
Document ID | / |
Family ID | 12093568 |
Filed Date | 2001-11-29 |
United States Patent
Application |
20010047225 |
Kind Code |
A1 |
Shimoike, Hiroshi ; et
al. |
November 29, 2001 |
SUBSTRATE CONVEYING SYSTEM IN SEMICONDUCTOR MANUFACTURING
APPARATUS
Abstract
A substrate conveying system wherein, at a substrate transfer
position of a conveyance robot, a robot arm is moved upwardly at a
normal speed from its lowermost position, and wherein the movement
speed is changed to a lower speed at a predetermined position.
During upward motion at the lower speed, the substrate is received
and, while continuing the upward motion, the movement speed is
changed back to the normal speed, at a second predetermined
position. The robot arm continues its upward motion to its topmost
position, with this normal speed.
Inventors: |
Shimoike, Hiroshi; (Tokyo,
JP) ; Nakahara, Takashi; (Tokyo, JP) |
Correspondence
Address: |
FITZPATRICK CELLA HARPER & SCINTO
30 ROCKEFELLER PLAZA
NEW YORK
NY
10112
US
|
Family ID: |
12093568 |
Appl. No.: |
09/493230 |
Filed: |
January 28, 2000 |
Current U.S.
Class: |
700/250 ; 355/72;
700/245 |
Current CPC
Class: |
Y02P 90/02 20151101;
Y10S 414/135 20130101; Y02P 90/08 20151101; G05B 19/41815 20130101;
Y02P 90/28 20151101; Y10S 414/137 20130101; Y02P 90/083
20151101 |
Class at
Publication: |
700/250 ;
700/245; 355/72 |
International
Class: |
G05B 019/04; G06F
019/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 29, 1999 |
JP |
11-022828 |
Claims
What is claimed is:
1. A substrate conveying system, comprising: a robot arm with
substrate holding means for holding a substrate, said robot arm
being operable to move said substrate holding means to a
predetermined position to enable transfer of the substrate; and
control means for controlling movement of said substrate holding
means to said predetermined position, said control means having at
least one axis and being operable to control the movement of said
substrate holding means related to said at least one axis, with
respect to at least four, first to fourth, positions, wherein the
first position is a movement start position where the movement of
said substrate holding means is to be started, wherein the second
position is a first speed changing position where a movement speed
of said substrate holding means is to be changed from a first set
speed to a second set speed, wherein the third position is a second
speed changing position where the movement speed of said substrate
holding means is to be changed from the second set speed to the
first set speed, and wherein the fourth position is a movement
completion position where the movement of said substrate holding
means is to be completed.
2. A substrate conveying system according to claim 1, wherein the
transfer of the substrate is performed during movement of said
substrate holding means from the first speed changing position to
the second speed changing position.
3. A substrate conveying system according to claim 1, wherein the
second set speed is slower than the first set speed.
4. A substrate conveying system according to claim 1, wherein said
substrate holding means includes a holding mechanism for
mechanically holding the substrate.
5. A substrate conveying method, comprising the steps of: holding a
substrate through a substrate holding device provided on a robot
arm; and moving the substrate holding device to a predetermined
position in accordance with at least one axis, for transfer of the
substrate; wherein said moving step for moving the substrate
holding means device in accordance with the at least one axis
includes (i) moving, at a first set speed, the substrate holding
device to a movement start position where the movement of the
substrate holding device is to be started, (ii) moving, at the
first set speed, the substrate holding device to a first speed
changing position where a movement speed of the substrate holding
device is to be changed from the first set speed to a second set
speed, (iii) moving, at the second set speed, the substrate holding
device to a second speed changing position where the movement speed
of the substrate holding device is to be changed from the second
set speed to the first set speed, and (iv) moving, at the first set
speed, the substrate holding device to a movement completion
position where the movement of the substrate holding device is to
be completed.
6. A method according to claim 5, wherein the transfer of the
substrate is performed during movement, at the second set speed, of
the substrate holding device from the first speed changing position
to the second speed changing position.
7. A method according to claim 5, wherein the second set speed is
slower than the first set speed.
8. A method according to claim 5, wherein the substrate holding
device includes a holding mechanism for mechanically holding the
substrate.
9. A substrate conveying system, comprising: a robot arm with
substrate holding means for holding a substrate, said robot arm
being operable to move said substrate holding means to a
predetermined position to enable transfer of the substrate; and
control means for controlling movement of said substrate holding
means to said predetermined position, said control means having at
least two axes and being operable to control the movement of said
substrate holding means related to said at least two axes, with
respect to at least seven, first to seventh, positions, wherein the
first position is a movement start position for a first axis where
the movement of said substrate holding means with respect to the
first axis is to be started, wherein the second position is a
movement start position for a second axis where the movement of
said substrate holding means with respect to the second axis is to
be started, wherein the third position is a first speed changing
position for the second axis where a movement speed of said
substrate holding means with respect to the second axis is to be
changed from a first set speed for the second axis to a second set
speed for the second axis, wherein the fourth position is a second
speed changing position for the second axis where the movement
speed of said substrate holding means with respect to the second
axis is to be changed from the second set speed for the second axis
to the first set speed for the second axis, wherein the fifth
position is a second speed changing position for the first axis
where the movement speed of said substrate holding means with
respect to the first axis is to be changed from a second set speed
for the first axis to a first set speed for the first axis, wherein
the sixth position is a movement completion position for the first
axis where the movement of said substrate holding means with
respect to the first axis is to be completed, and wherein the
seventh position is a movement completion position for the second
axis where the movement of said substrate holding means with
respect to the second axis is to be completed.
10. A substrate conveying system according to claim 9, wherein the
transfer of the substrate is performed during movement of said
substrate holding means from the first speed changing position for
the second axis to the second speed changing position for the
second axis.
11. A substrate conveying system according to claim 9, wherein the
second set speed for the second axis is slower than the first set
speed for the second axis, and wherein the second set speed for the
first axis is slower than the first set speed for the first
axis.
12. A substrate conveying system according to claim 9, wherein said
substrate holding means includes a holding mechanism for
mechanically holding the substrate.
13. A substrate conveying method, comprising the steps of: holding
a substrate through a substrate holding device provided on a robot
arm; and moving the substrate holding device to a predetermined
position in accordance with at least two axes, to enable transfer
of the substrate; wherein said moving step for moving the substrate
holding device in accordance with at least two axes includes (i)
moving, at a first set speed with respect to a first axis and also
at a first set speed with respect to a second axis, the substrate
holding device to a movement start position for the first axis
where the movement of the substrate holding device with respect to
the first axis is to be started, (ii) moving, at the first set
speed with respect to the first axis, the substrate holding device
to a movement start position for the second axis where the movement
of the substrate holding device with respect to the second axis is
to be started, (iii) moving, at the first set speed with respect to
the second axis, the substrate holding device to a first speed
changing position for the second axis where a movement speed of the
substrate holding device is to be changed from the first set speed
for the second axis to a second set speed for the second axis, (iv)
moving, at the second set speed with respect to the second axis,
the substrate holding device to a second speed changing position
for the second axis where the movement speed of the substrate
holding device is to be changed from the second set speed for the
second axis to the first set speed for the second axis, (v) moving,
at the first set speed with respect to the second axis, the
substrate holding device to a movement completion position for the
second axis where the movement of the substrate holding device with
respect to the second axis is to be completed, (vi) moving, at the
second set speed with respect to the first axis, the substrate
holding device to a second speed changing position for the first
axis where the movement speed of the substrate holding device is to
be changed from a second set speed for the first axis to the first
set speed for the first axis, and (vii) moving, at the first set
speed with respect to the first axis, the substrate holding device
to a movement completion position for the first axis where the
movement of the substrate holding means with respect to the first
axis is to be completed.
14. A method according to claim 13, wherein the transfer of the
substrate is performed during movement, at the second set speed
with respect to the second axis, of the substrate holding device
from the first speed changing position for the second axis to the
second speed changing position for the second axis.
15. A method according to claim 13, wherein the second set speed
for the second axis is slower than the first set speed for the
second axis, and wherein the second set speed for the first axis is
slower than the first set speed for the first axis.
16. A method according to claim 13, wherein the substrate holding
device includes a holding mechanism for mechanically holding the
substrate.
17. A substrate conveying hand mechanism, comprising: fixed pawls
provided at least at two locations; at least one movable pawl
movably disposed with a variable distance to said fixed pawls, for
sandwiching and holding a substrate between the same and said fixed
pawls; and bellows means connected to said at least one movable
pawl and being able to be expanded and contracted through actuation
of a fluid, to change the distance between said at least one
movable pawl and said fixed pawls.
18. A substrate conveying hand mechanism according to claim 17,
wherein said at least one movable pawl includes a pair of parallel
arms each being swingably supported, and a tension spring for
applying a tension urging force between said parallel arms, and
wherein a substrate can be held between said parallel arms as they
are opened against the tension spring.
19. A substrate conveying hand mechanism according to claim 17,
wherein said at least one movable pawl includes an engagement
adapted to be in roll engagement with a substrate when the same is
held.
20. A substrate conveying hand mechanism according to claim 17,
further comprising an opening formed in a face to be opposed to the
substrate, for releasing a heat from the substrate as the same is
held.
21. A substrate conveying method, comprising the steps of: holding
a substrate through a substrate holding device provided on a robot
arm; and moving the substrate holding device in accordance with at
least one axis, to a predetermined position, for transfer of the
substrate; wherein said substrate holding device satisfies a
relation with respect to said at least one axis that a position of
said substrate holding device for receiving the substrate differs
from a position of said substrate holding device for sending the
substrate therefrom.
22. A semiconductor manufacturing apparatus including a substrate
conveying system as recited in claim 1.
23. A semiconductor manufacturing apparatus including a substrate
conveying hand mechanism as recited in claim 17.
24. A semiconductor device manufacturing method including a step
for processing a substrate conveyed in accordance with a substrate
conveying method as recited in claim 5 or 21.
Description
FIELD OF THE INVENTION AND RELATED ART
[0001] This invention relates to a substrate conveying system, a
substrate conveying method and/or a substrate conveying hand
mechanism, for conveying a substrate such as a semiconductor wafer,
for example. In another aspect, the invention is concerned with a
semiconductor manufacturing apparatus having an arrangement for
performing an ashing process by use of such substrate conveying
system, or a semiconductor device manufacturing method including an
ashing process by use of such substrate conveying system.
[0002] In some semiconductor manufacturing apparatuses, for
processing substrates such as semiconductor wafers or glass
substrates, for example, the substrates are sequentially and
circulatively conveyed to various processing units so that various
processes such as surface treatment, for example, are performed to
the substrates in these units.
[0003] As a substrate conveying mechanism used in such circulation
conveyance type substrate conveying systems, there are a sequential
conveyance type robot for conveying each substrate while gripping
the same and a double-hand type robot having a two-level hand
structure with upper and lower substrate holding portions. With
this double-hand type conveying mechanism, each processing unit can
be accessed by two hands sequentially, such that, in each
processing unit, high-speed processing can be done while
interchanging substrates such as wafers.
[0004] Generally, a substrate conveying system has a substrate
holding means provided at a free end of a robot arm. The robot arm
can be moved rotationally, extended or contracted horizontally and
moved vertically, to perform transfer of a substrate between it and
a processing unit. Also, there are cases wherein the robot itself
is made rotationally movable and also movable horizontally or
vertically.
[0005] These motions are controlled in accordance with axes (drive
axes) corresponding to the motions, respectively. Namely, there are
an axis for rotational motion, an axis for horizontal motion and an
axis for vertical motion, for example.
[0006] As regards operation commands to such a conveyance robot,
generally, a distance from a mechanical origin is taught to each
axis defined in the robot in the form of a coordinate value
(teaching position). Each value is stored in a memory of the robot.
A host controller then specifies, with reference to the thus stored
positions, a substrate transfer operation or any other independent
operations related to respective axes.
[0007] In conventional conveying systems such as described above,
only a single operation speed is set with respect to each driving
axis of the robot. As a result, when the conveyance robot conveys a
substrate into a processing unit, a high-speed collision may occur
between the substrate and the processing unit.
[0008] The impact of collision may cause vibration of the substrate
in the processing unit, as the same is loaded into the processing
unit, and accurate processing may be interrupted. On the other
hand, when the conveyance robot takes the substrate out of the
processing unit, there may occur a high-speed collision between the
substrate and the conveyance robot. The impact of collision may
disturb accurate conveyance.
[0009] Recently, the wafer size becomes larger and thus the wafer
weight becomes heavier. This makes the impact of collision between
a substrate and a processing unit or between a substrate and a
conveyance robot quite larger, and the influence thereof becomes
critical.
[0010] On the other hand, conventional substrate conveying robot
systems use substrate holding methods such as of a vacuum finger
type wherein a substrate is attracted by vacuum, a fit-in type
wherein a substrate is fitted in a recessed portion and held
thereby, or a mechanical grip type (Japanese Laid-Open Patent
Application, Laid-Open No. 22502/1995) wherein a free-end side
gripping portion is moved toward an arm grip of arcuate shape so
that a substrate is sandwiched between them.
[0011] However, these conventional substrate holding methods
involve problems of contamination or deformation of a substrate,
for example. While details will be discussed later in this
specification (specifically, in relation to a third embodiment),
there is a possibility that particles produced at a mechanical
sliding portion of a conveyance robot or a friction portion between
a substrate and a substrate holding element of the conveyance robot
are adhered to the substrate, to cause contamination of the same.
Also, there is a possibility that a temperature difference is
created between a top face side of a substrate and a bottom face
side thereof as held by a robot arm of the conveyance robot, which
may cause warp of the substrate or a crack in the substrate.
SUMMARY OF THE INVENTION
[0012] It is accordingly an object of the present invention to
provide a substrate conveying system and/or a substrate conveying
method, by which high-speed collision of a substrate during
transportation of the substrate by a conveyance robot or the like
can be avoided.
[0013] It is another object of the present invention to provide a
substrate conveying hand mechanism by which contamination of a
substrate by particles and/or deformation of the substrate due to a
temperature difference can be avoided.
[0014] In accordance with an aspect of the present invention, there
is provided a substrate conveying system, comprising: a robot arm
with substrate holding means for holding a substrate, said robot
arm being operable to move said substrate holding means to a
predetermined position to enable transfer of the substrate; and
control means for controlling movement of said substrate holding
means to said predetermined position, said control means having at
least one axis and being operable to control the movement of said
substrate holding means related to said at least one axis, with
respect to at least four, first to fourth, positions, wherein the
first position is a movement start position where the movement of
said substrate holding means is to be started, wherein the second
position is a first speed changing position where a movement speed
of said substrate holding means is to be changed from a first set
speed to a second set speed, wherein the third position is a second
speed changing position where the movement speed of said substrate
holding means is to be changed from the second set speed to the
first set speed, and wherein the fourth position is a movement
completion position where the movement of said substrate holding
means is to be completed.
[0015] The transfer of the substrate may be performed during
movement of said substrate holding means from the first speed
changing position to the second speed changing position.
[0016] The second set speed may be slower than the first set
speed.
[0017] The substrate holding means may include a holding mechanism
for mechanically holding the substrate.
[0018] In accordance with another aspect of the present invention,
there is provided a substrate conveying method, comprising the
steps of: holding a substrate through a substrate holding device
provided on a robot arm; and moving the substrate holding device to
a predetermined position in accordance with at least one axis, for
transfer of the substrate; wherein said moving step for moving the
substrate holding means device in accordance with the at least one
axis includes (i) moving, at a first set speed, the substrate
holding device to a movement start position where the movement of
the substrate holding device is to be started, (ii) moving, at the
first set speed, the substrate holding device to a first speed
changing position where a movement speed of the substrate holding
device is to be changed from the first set speed to a second set
speed, (iii) moving, at the second set speed, the substrate holding
device to a second speed changing position where the movement speed
of the substrate holding device is to be changed from the second
set speed to the first set speed, and (iv) moving, at the first set
speed, the substrate holding device to a movement completion
position where the movement of the substrate holding device is to
be completed.
[0019] The transfer of the substrate may be performed during
movement, at the second set speed, of the substrate holding device
from the first speed changing position to the second speed changing
position.
[0020] The second set speed may be slower than the first set
speed.
[0021] The substrate holding device may include a holding mechanism
for mechanically holding the substrate.
[0022] In accordance with a further aspect of the present
invention, there is provided a substrate conveying system,
comprising: a robot arm with substrate holding means for holding a
substrate, said robot arm being operable to move said substrate
holding means to a predetermined position to enable transfer of the
substrate; and control means for controlling movement of said
substrate holding means to said predetermined position, said
control means having at least two axes and being operable to
control the movement of said substrate holding means related to
said at least two axes, with respect to at least seven, first to
seventh, positions, wherein the first position is a movement start
position for a first axis where the movement of said substrate
holding means with respect to the first axis is to be started,
wherein the second position is a movement start position for a
second axis where the movement of said substrate holding means with
respect to the second axis is to be started, wherein the third
position is a first speed changing position for the second axis
where a movement speed of said substrate holding means with respect
to the second axis is to be changed from a first set speed for the
second axis to a second set speed for the second axis, wherein the
fourth position is a second speed changing position for the second
axis where the movement speed of said substrate holding means with
respect to the second axis is to be changed from the second set
speed for the second axis to the first set speed for the second
axis, wherein the fifth position is a second speed changing
position for the first axis where the movement speed of said
substrate holding means with respect to the first axis is to be
changed from a second set speed for the first axis to a first set
speed for the first axis, wherein the sixth position is a movement
completion position for the first axis where the movement of said
substrate holding means with respect to the first axis is to be
completed, and wherein the seventh position is a movement
completion position for the second axis where the movement of said
substrate holding means with respect to the second axis is to be
completed.
[0023] The transfer of the substrate may be performed during
movement of said substrate holding means from the first speed
changing position for the second axis to the second speed changing
position for the second axis.
[0024] The second set speed for the second axis may be slower than
the first set speed for the second axis, and the second set speed
for the first axis may be slower than the first set speed for the
first axis.
[0025] The substrate holding means may include a holding mechanism
for mechanically holding the substrate.
[0026] In accordance with a yet further aspect of the present
invention, there is provided a substrate conveying method,
comprising the steps of: holding a substrate through a substrate
holding device provided on a robot arm; and moving the substrate
holding device to a predetermined position in accordance with at
least two axes, to enable transfer of the substrate; wherein said
moving step for moving the substrate holding device in accordance
with at least two axes includes (i) moving, at a first set speed
with respect to a first axis and also at a first set speed with
respect to a second axis, the substrate holding device to a
movement start position for the first axis where the movement of
the substrate holding device with respect to the first axis is to
be started, (ii) moving, at the first set speed with respect to the
first axis, the substrate holding device to a movement start
position for the second axis where the movement of the substrate
holding device with respect to the second axis is to be started,
(iii) moving, at the first set speed with respect to the second
axis, the substrate holding device to a first speed changing
position for the second axis where a movement speed of the
substrate holding device is to be changed from the first set speed
for the second axis to a second set speed for the second axis, (iv)
moving, at the second set speed with respect to the second axis,
the substrate holding device to a second speed changing position
for the second axis where the movement speed of the substrate
holding device is to be changed from the second set speed for the
second axis to the first set speed for the second axis, (v) moving,
at the first set speed with respect to the second axis, the
substrate holding device to a movement completion position for the
second axis where the movement of the substrate holding device with
respect to the second axis is to be completed, (vi) moving, at the
second set speed with respect to the first axis, the substrate
holding device to a second speed changing position for the first
axis where the movement speed of the substrate holding device is to
be changed from a second set speed for the first axis to the first
set speed for the first axis, and (vii) moving, at the first set
speed with respect to the first axis, the substrate holding device
to a movement completion position for the first axis where the
movement of the substrate holding means with respect to the first
axis is to be completed.
[0027] The transfer of the substrate may be performed during
movement, at the second set speed with respect to the second axis,
of the substrate holding device from the first speed changing
position for the second axis to the second speed changing position
for the second axis.
[0028] The second set speed for the second axis may be slower than
the first set speed for the second axis, and the second set speed
for the first axis may be slower than the first set speed for the
first axis.
[0029] The substrate holding device may include a holding mechanism
for mechanically holding the substrate.
[0030] In accordance with a yet further aspect of the present
invention, there is provided a substrate conveying hand mechanism,
comprising: fixed pawls provided at least at two locations; at
least one movable pawl movably disposed with a variable distance to
said fixed pawls, for sandwiching and holding a substrate between
the same and said fixed pawls; and bellows means connected to said
at least one movable pawl and being able to be expanded and
contracted through actuation of a fluid, to change the distance
between said at least one movable pawl and said fixed pawls.
[0031] The at least one movable pawl may include a pair of parallel
arms each being swingably supported, and a tension spring for
applying a tension urging force between said parallel arms, wherein
a substrate can be held between said parallel arms as they are
opened against the tension spring.
[0032] The at least one movable pawl may include an engagement
adapted to be in roll engagement with a substrate when the same is
held.
[0033] The substrate conveying system may further comprise an
opening formed in a face to be opposed to the substrate, for
releasing a heat from the substrate as the same is held.
[0034] In accordance with a still further aspect of the present
invention, there is provided a substrate conveying method,
comprising the steps of: holding a substrate through a substrate
holding device provided on a robot arm; and moving the substrate
holding device in accordance with at least one axis, to a
predetermined position, for transfer of the substrate; wherein said
substrate holding device satisfies a relation with respect to said
at least one axis that a position of said substrate holding device
for receiving the substrate differs from a position of said
substrate holding device for sending the substrate therefrom.
[0035] In accordance with a yet further aspect of the present
invention, there is provided a semiconductor manufacturing
apparatus including a substrate conveying system such as described
above.
[0036] In accordance with a yet further aspect of the present
invention, there is provided a semiconductor manufacturing
apparatus including a substrate conveying hand mechanism as recited
above.
[0037] In accordance with a still further aspect of the present
invention, there is provided a semiconductor device manufacturing
method including a step for processing a substrate conveyed in
accordance with a substrate conveying method as recited above.
[0038] These and other objects, features and advantages of the
present invention will become more apparent upon a consideration of
the following description of the preferred embodiments of the
present invention taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIG. 1 is a top plan view of an example of a conveyance
robot usable in the present invention.
[0040] FIG. 2 is a side view of an example of a conveyance robot
usable in the present invention.
[0041] FIG. 3 is a diagram for explaining an example of a control
system for a conveyance robot, usable in the present invention.
[0042] FIG. 4 is a schematic view of a general structure of an
ashing processing system according to an embodiment of the present
invention.
[0043] FIG. 5 is a diagram for explaining conveyance turn in the
ashing processing system of FIG. 4.
[0044] FIG. 6 is a side view of an example of a substrate
supporting mechanism of a process unit, used in the ashing
processing system of FIG. 4.
[0045] FIG. 7 is a schematic view for explaining an example of a
teaching position with respect to a Z-axis direction.
[0046] FIG. 8 is a schematic view for explaining an operation for
taking a substrate out of a unit.
[0047] FIG. 9 is a flow chart for explaining a control procedure of
the operation shown in FIG. 8.
[0048] FIG. 10 is a schematic view for explaining an operation for
loading a substrate into a unit.
[0049] FIG. 11 is a flow chart for explaining a control procedure
of the operation shown in FIG. 10.
[0050] FIG. 12 is a schematic view of an example of a robot arm
having a mechanism for mechanically holding a substrate.
[0051] FIG. 13 is a schematic view for explaining an example of a
teaching position, for accomplishing a substrate transfer operation
with variation in speed in a Z-axis direction, according to a first
embodiment of the present invention.
[0052] FIGS. 14A and 14B are graphs, respectively, for explaining
the relation between an operation speed and an operation time
(position), in a conventional control operation method.
[0053] FIG. 15 is a flow chart for explaining a control procedure
for Z-axis operation with variation in speed, according to the
first embodiment of the present invention.
[0054] FIG. 16 is a graph for explaining the relation between an
operation speed and an operation time (position), in the control
operation method of FIG. 13.
[0055] FIG. 17 is a schematic view for explaining an example of a
teaching position for R-axis operation using a robot arm shown in
FIG. 12, in a second embodiment of the present invention.
[0056] FIG. 18 is a flow chart for explaining a control procedure
for the operation shown in FIG. 17.
[0057] FIG. 19 is a graph for explaining the relation between an
operation speed and an operation time (position), in the operation
shown in FIG. 17.
[0058] FIG. 20 is a top plan view of an example of a hand mechanism
in a third embodiment of the present invention.
[0059] FIG. 21 is a side view of the hand mechanism of FIG. 20.
[0060] FIG. 22 is a top plan view of the hand mechanism of FIG. 20,
in a gripping position thereof.
[0061] FIG. 23 is a schematic view for explaining a receiving
operation of the hand mechanism of FIG. 20.
[0062] FIG. 24 is a schematic view for explaining a sending
operation of the hand mechanism of FIG. 20.
[0063] FIG. 25 is a top plan view of a hand mechanism in a fourth
embodiment of the present invention.
[0064] FIG. 26 is a top plan view of a hand mechanism in a fifth
embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0065] Preferred embodiments of the present invention will now be
described with reference to the accompanying drawings.
[0066] [First Embodiment]
[0067] FIG. 1 is a top plan view of a double-hand type robot having
two substrate holding portions (upper and lower hands) arrayed
vertically. FIG. 2 is a side view thereof.
[0068] As shown in FIG. 1, the robot 1 includes two, upper and
lower robot arms each having a substrate holding means at a free
end thereof (in the illustrated example, there are substrates
W.sub.u and W.sub.l held thereby), and the robot has an axis
(.theta. axis) for rotational motion (.theta.) and an axis (R axis)
for forward/backward motion (R). In the illustrated example, the
mechanisms for performing forward/backward motions of the robot
arms comprise arm-like link mechanisms R.sub.1 and R.sub.2. There
is additional axes for moving the robot 1 as a whole in a lateral
direction (X axis) and a longitudinal direction (Y axis). Further,
as shown in FIG. 2, the robot 1 has an axis (Z axis) for moving its
arms in its height direction (Z direction). As best seen in FIG. 2,
this robot 1 is arranged so that two substrates W.sub.u and W.sub.l
are simultaneously held by the upper and lower substrate holding
means, respectively.
[0069] This conveyance robot 1 is connected to a control system
such as shown in FIG. 3, for example. More specifically, in
response to a communication command or an electric signal from a
machine controlling controller (HOST) 2, a conveyance robot
controller 3 for practically controlling the operation of the
conveyance robot 1 is actuated, such that, while sequentially
conveying substrates in an order as scheduled by the machine
controlling controller (HOST) 2, they are circulated through
predetermined processing units to be processed thereby.
[0070] As regards operation commands to this conveyance robot 1, a
distance from a mechanical origin is taught to each axis defined in
the robot in the form of a coordinate value (teaching position).
Each value is stored in a memory, in the conveyance robot
controller 3, such as a non-volatile storing device, for example.
The machine controlling controller (HOST) 2 then specifies, with
reference to the thus stored positions, a substrate transfer
operation or any other independent operations related to respective
axes.
[0071] FIG. 4 shows an example of a substrate processing system
having such a substrate conveyance robot 1 incorporated therein,
and illustrates the structure of an ashing processing system for a
photosensitive resin (photoresist) to be used in semiconductor
manufacturing processes.
[0072] In semiconductor manufacturing processes, usually, a
photosensitive resin is applied, by using a coating machine, onto a
film to be processed, which is formed on the surface of a substrate
such as a silicon wafer, for example. To this photosensitive resin,
a pattern of a mask (reticle) having been prepared beforehand is
lithographically transferred by use of an exposure apparatus.
Thereafter, a developing process is performed to it by use of a
developing apparatus, by which a desired transferred pattern of
photosensitive resin is produced. Then, by using this transferred
pattern as a mask, an etching process, a diffusion process and a
film forming process, and the like, are performed. After completion
of all the required processes, the pattern of photosensitive resin
having been used as a mask is ashed by using ozones produced by
plasma and, by cleaning, it is removed.
[0073] As shown in FIG. 4, the ashing processing system 4 includes
substrate containing cassettes a.sub.1 and a.sub.2 for supplying
and collecting substrates, ashing processing chambers c.sub.1 and
c.sub.2, and cooling plates b.sub.1 and b.sub.2 for cooling the
substrates. There are plural identical units, and this is to enable
simultaneous and parallel execution of the same processings to
thereby improve the throughput. Conveyance of substrates to these
units is performed by use of the conveyance robot 1 disposed at the
center of the processing system.
[0074] The substrate conveyance may be performed in accordance with
the sequence such as shown in Figure 5, for example. More
specifically, first, a substrate is taken out of the container
cassette a.sub.1 (step <1>). It is conveyed to the ashing
processing chamber c.sub.1 (step <2>). In this ashing
processing chamber c.sub.1, first, a substrate having been
processed is taken out (step <3>) and, then, the substrate
conveyed thereto is loaded (step <4>). The substrate taken
out of the ashing processing chamber c.sub.1 is conveyed to the
cooling plate b.sub.1 (step <5>). Also at this cooling plate
.sub.1, a substrate having been cooled is taken out (step
<6>) and, then, the substrate conveyed thereto is loaded
(step <7>). The substrate taken out of the cooling plate
b.sub.1 is conveyed to the container cassette a.sub.1 (step
<8>), and it is stored into the cassette a.sub.1 (step
<9>).
[0075] The ashing processing chambers c.sub.1 and c.sub.2 for
performing an ashing process to substrates may include a process
unit PC such as shown in FIG. 6. Here, denoted at 5 are supporting
pins being movable upwardly and downwardly, and being for use in
receiving a substrate W. These supporting pins 5 move upwardly for
transfer of a substrate, and they are provided at positions not
mechanically interfering with the transfer operation of the
conveyance robot. Also, they are moved downwardly for execution of
the substrate processing, to enable that the substrate processing
is performed at the position appropriate for the substrate
processing condition.
[0076] For transfer of a substrate to and from these supporting
pins 5 of the process unit, conventionally, it is done by
specifying two position coordinates of an upper position (U) and a
lower position (L) with respect to the Z-axis teaching, as shown in
FIG. 7.
[0077] The operation for placing a substrate on these supporting
pins in the conventional system will first be explained with
reference to FIGS. 8 and 9.
[0078] First, the .theta. axis (FIG. 1) and the Z axis (FIG. 2) are
actuated so that the robot arm is moved to a position A at the
upper side (U) in FIG. 8 (steps S901 and S902 in FIG. 9).
Subsequently, the R axis is actuated to move the robot arm forward,
up to a position B at the upper side (U) in FIG. 8 (step s903 in
FIG. 9). Then, the Z axis is actuated to move the robot arm
downwardly, to a position C at the lower side (L) in FIG. 8 (step
S904 in FIG. 9). In the course of this downward motion, the
substrate W is placed on the supporting pins 5. Thereafter, the R
axis is actuated to retract the robot arm, to a position D at the
lower side (L) in FIG. 8 (step S905 in FIG. 9).
[0079] Next, the operation for picking up a substrate from the
supporting pins 5 will be explained with reference to FIGS. 10 and
11.
[0080] First, the .theta. axis and Z axis are actuated to move the
robot arm to a position D at the lower side (L) in FIG. 10 (steps
S1101 and S1102 in FIG. 11). Subsequently, the R axis is actuated
to move the robot arm forward, to a position D at the lower side
(L) in FIG. 10 (step S1103 in FIG. 11). Thereafter, the Z axis is
actuated to move the robot arm upwardly to a position B at the
upper side (U) of FIG. 10 (step S1104 in FIG. 11). In the course of
this upward motion, the substrate W is transferred from the
supporting pins 5 to the robot arm. Thereafter, the R axis is
actuated to retract the robot arm, to a position A at the upper
side (U) in FIG. 10 (step S1105 in FIG. 11).
[0081] These operations are made in accordance with a common
operation speed, a common acceleration, a common S-shaped driving
parameter, and the like, all being set in common with regard to all
the axes prepared for the conveyance robot 1. Therefore, these
operations are made surely at the same speed.
[0082] As regards the method of specifying these operations to the
conveyance robot controller 3 from the machine controlling
controller (HOST) 2, a sequential control flow such as shown in
FIG. 9 or 11 is executed in response to a single operation
command.
[0083] FIGS. 14A and 14B show the relation between the operation
speed in Z axis and the operation time (position) to be established
when these operations are made. In FIGS. 14A and 14B, the axis of
abscissa denotes the operation time (position) and the axis of
ordinate corresponds to the operation speed. Also, the origin of
the graph is taken on the upper side (U), and the operation toward
the lower side (L) from this position is plotted in the graph.
[0084] Here, if the position of a supporting pin as the same
receives a substrate is .alpha., then the collision speed of the
substrate and the supporting pin at that moment is .alpha.s. This
speed .alpha.s is variable in dependence upon the teaching
positions U and L as well as the actual operation speed between
them. For example, FIG. 14A corresponds to a case where the
interval between U and L is relatively narrow as compared with the
set speed, and, in this example, the operation speed starts its
deceleration without reaching the set speed (or instantaneously
thereafter even it is reached). On the other hand, FIG. 14B shows a
case where the interval between U and L is relatively wide, and, in
this example, the operation speed reaches the set speed and, after
a constant-speed state is continued for a certain time,
deceleration starts.
[0085] In any of these cases, the substrate and the supporting pin
collide with each other at a relatively high speed. As a result,
due to its impact, vibration of the substrate is generated upon the
supporting pins when the substrate is loaded into a processing
unit. This disturbs accurate processing of the substrate in the
unit.
[0086] When, on the other hand, the robot arm receives a substrate
from the supporting pins, in this turn, the substrate and the robot
arm collide with each other at a relatively high speed. This
disturbs precise substrate conveyance.
[0087] In accordance with a preferred embodiment of the present
invention, in consideration of the above, as shown in FIG. 13, for
example, two points U.sub.s and Ls are newly added between the
upper side (U) position and the lower side (L) position, for a
lower-speed operation as compared with the normal speed. Also, as
for the Z-axis operation speed, an operation speed S.sub.s lower
than the normal or steady state speed S.sub.n, is newly set for the
motion between the positions U.sub.s and L.sub.s, separately from
the normal operation speed S.sub.n. The position teaching is
performed on the basis of them.
[0088] FIG. 15 illustrates the operational sequence for conveying a
substrate out of a processing unit, and FIG. 16 shows the relation
between the operation speed and the operation time (position) in
that sequence.
[0089] First, the .theta. axis and the Z axis are actuated,
respectively, to move the robot arm to a position D at the lower
side (L) in FIG. 10 (steps S1501 and S1502 in FIG. 15). Here, the Z
axis is driven at a normal Z-axis speed S.sub.n. Subsequently, the
R axis is actuated to move the robot arm forwardly to a position C
at the lower side (L) in FIG. 10, namely, to the lower side (L)
position in FIG. 13 (step S1503 in FIG. 15). Thereafter, the Z axis
is driven at the normal Z-axis speed S.sub.n, to a position Ls in
FIG. 13 (step S1504 in FIG. 15). As the robot arm reaches the
position L.sub.s (step S1505 in FIG. 15), the set Z-axis speed is
changed to S.sub.s (step S1506 in FIG. 15) and, while keeping this
speed, the robot arm is moved toward the position U.sub.s (step
S1507 in FIG. 15). In the course of this motion, a substrate W is
transferred to the robot arm from the supporting pins 5. As the
robot arm reaches the position U.sub.s (step S1508 in FIG. 15), the
set Z-axis speed S.sub.s is changed back to S.sub.n (step S1509 in
FIG. 15) and, while keeping this speed, the robot arm is moved to a
position B at the upper side (U) in FIG. 10, namely, to the upper
side (U) position in FIG. 13 (step S1510 in FIG. 15). As the robot
arm reaches the position B (step S1511 in FIG. 15), the R axis is
actuated to retract the robot arm, back to the position A at the
upper side (U) in FIG. 10 (step S1512 in FIG. 15).
[0090] With this control, as shown in FIG. 16, the speed at the
moment whereat the substrate and the robot arm contact with each
other can be controlled to a desired low speed, and thus the impact
of collision can be reduced significantly.
[0091] Similar control may be made when a substrate is to be loaded
into a processing unit. The result is that the speed at the moment
whereat the substrate and the supporting pins contact with each
other can be controlled to a desired low speed, and consequently,
the collision impact can be reduced significantly.
[0092] As described above, the driving speed of the robot arm is
controlled to a lower speed only for the moment for substrate
transfer, and, in the remaining period, the robot arm is driven at
a normal speed. This enables desirable substrate transfer without
considerable elongation of the entire operation time.
[0093] [Second Embodiment]
[0094] The control procedure of the present invention when applied
to a robot arm having a mechanical substrate holding mechanism such
as shown in FIG. 12, will be explained.
[0095] As shown in FIG. 12, the robot arm 10 has a pair of fixed
holding guides G and a pair of movable holding guides Gp, wherein a
substrate W can be held thereby when sandwiched between them. More
specifically, while a substrate W is sandwiched between them, the
movable holding guides Gp relatively move toward the fixed holding
guides G, by which the substrate W is gripped.
[0096] When a substrate is transferred to this robot arm 10 and is
held thereby, if, for example, the spacing between juxtaposed upper
and lower substrates being accommodated is narrow, as in the case
of a substrate accommodating cassette, for example, the movable
holding guides Gp can not be driven at the position where they
receive a substrate. This means that, during a period from
receiving the substrate to moving the movable holding guides Gp,
the substrate is placed on the robot arm 10 for free motion. If
therefore the driving speed of the robot arm 10 is large, there
easily occurs positional shift of the substrate. Thus, accurate
holding ends in failure.
[0097] In this embodiment, in consideration of the above, as shown
in FIG. 17, as for the driving speed of the robot arm 10 with
respect to the R-axis direction, too, dual values of a normal speed
SG.sub.n and a pre-gripping speed SG.sub.g lower than the former
are set. Thus, as the teaching positions with respect to the R-axis
direction, there are a substrate position W, a speed changing
position W.sub.p for changing from SG.sub.n to SG.sub.g, a holding
guide driving position G.sub.p, and a speed changing position
(high-speed conveyance starting position) for changing from
SG.sub.g to SG.sub.n. It should be noted that, in this example, the
same coordinates are specified to the substrate position W.sub.o
and the speed changing position W.sub.p (from SG.sub.n to
SG.sub.g). This is because of the following reason. In the R-axis
operation, it is not effective to perform a similar speed changing
control also in an operation period in which no substrate is being
held. Thus, in relation to the substrate loading operation for
moving the substrate from the robot arm 10 to the processing unit,
the movement operation of the R-axis from the substrate position
W.sub.o to the origin after the substrate is transferred, the
R-axis operation is made at the normal speed SG.sub.n. Similarly,
in relation to the substrate unloading operation for moving the
substrate from the processing unit side to the robot arm 10, the
R-axis operation to the substrate position W.sub.o from the origin
before the substrate is received, is made at the normal speed
SG.sub.n.
[0098] FIG. 18 shows the flow of operational control for the
substrate unloading operation, moving a substrate from a processing
unit side to the robot arm 10.
[0099] First, the .theta. axis and the Z axis are actuated
respectively, to move the robot arm 10 to a lower side (L) position
with respect to the Z axis, similar to that described hereinbefore,
which is at a predetermined position close to a processing unit to
be used (steps S1801 and S1802 in FIG. 18, or a stage (a) in FIG.
17). Here, the Z axis is driven at a normal Z-axis speed S.sub.n.
Subsequently, the R axis is driven at a normal speed SG.sub.n to
move the robot 10 forwardly, to a substrate position
W.sub.o/W.sub.p (step S1803 in FIG. 18, or a stage (b) in FIG. 17).
Thereafter the Z axis is driven at the normal Z-axis speed S.sub.n,
to a position L.sub.s (FIG. 13) (step S1804 in FIG. 18). As the
robot arm 10 reaches the position L.sub.s (step S1805 in FIG. 18),
the set Z-axis speed is changed to S.sub.s (step S1806 in FIG. 18).
While keeping this speed, the robot arm 10 is moved toward the
position U.sub.s (FIG. 13) (step S1807 in FIG. 18). In the course
of this motion, the substrate W is transferred from the unit side
to the robot arm 10. As the robot arm 10 reaches the position
U.sub.s (step S1808 in FIG. 18), the set Z-axis speed S.sub.s is
changed back to S.sub.n (step S1809 in FIG. 18). While keeping this
speed, the robot arm 10 is moved to the upper side (U) position
(FIG. 13) (step S1810 in FIG. 18). As the robot arm 10 reaches the
position U (step S1811 in FIG. 18), the set speed of the R axis is
changed from SG.sub.n to SG.sub.g (step S1812 in FIG. 18) and,
thereafter, the robot arm 10 is retracted back to the position
G.sub.s in FIG. 17 (step S1813 in FIG. 18). At the moment whereat,
in the course of this motion, the robot arm 10 reaches the position
G.sub.p, the substrate holding mechanism of the robot arm 10 is
actuated to grip the substrate, as shown at a stage (c) in FIG. 17
(step S1814 in FIG. 18). As the robot arm 10 reaches the position
G.sub.s (step S1815 in FIG. 18), the set speed of the R axis is
changed from SG.sub.g back to SG.sub.n (step S1816 in FIG. 18).
While keeping this speed, the robot arm 10 is moved to the origin
of the R axis (step S1817 in FIG. 18). When the robot arm 10
reaches the R-axis origin (step S1818 in FIG. 18), the process is
completed (at a stage (d) in FIG. 17).
[0100] FIG. 19 shows the relation between the operation speed and
the operation time (position), in the movement of the robot arm 10
from the substrate position W.sub.o/W.sub.p to the R-axis origin
R.sub.o as controlled as described above. The axis of ordinate
denotes the operation speed, and the axis of abscissa corresponds
to the operation time (position).
[0101] In the operation control described above, the substrate
position W.sub.o and the speed changing position W.sub.p, changing
from SG.sub.n to SG.sub.g, are specified as the same coordinate
position. Therefore, as the robot arm 10 receives the substrate, it
promptly starts its operation at the lower speed SG.sub.g. Since
the operation start position G.sub.p of the substrate holding
mechanism of the robot arm 10 is set before the high-speed
conveyance start position G.sub.s, the movement of the robot arm 10
in a state in which no substrate is held by the substrate holding
mechanism of the robot arm 10 can be made at a lower speed, that
is, SG.sub.g. Therefore, any shift of the substrate in this state
can be reduced significantly.
[0102] [Third Embodiment]
[0103] The substrate holding mechanism of the robot arm in the
embodiments described above may comprise a mechanical holding
mechanism such as shown in FIG. 12, or it may comprise a vacuum
attraction system used prevalently. Hereinafter, a robot hand
having a more preferable substrate holding mechanism will be
described.
[0104] Wafer conveying systems in semiconductor manufacturing
apparatuses are generally based on a vacuum finger type wherein a
scalar shaped or straight shaped robot has a vacuum attracting
portion of thin plate-like shape formed on a free end of its arm,
or a fit-in type wherein a wafer is fitted in a recessed portion
and is conveyed thereby. Recently, in an attempt to solving the
problem of particles on the bottom face of a wafer and also to
assuring positioning of a wafer upon a hand, a proposal has been
made in Japanese Laid-Open Patent Application, Laid-Open No.
22502/1995 to a handling system including an arm grip of arcuate
shape and having a size slightly larger than a wafer outside
diameter, as well as a free-end side grip being movable toward the
arm grip.
[0105] In such vacuum type conveying systems, however, there is a
problem of contamination of a wafer since, due to the vacuum
attraction, particles are adhered to the bottom face of the wafer.
Further, in a system to be used for a wafer process such as a
resist removing system (ashing processing system), generally, the
wafer is placed in a high temperature. If vacuum attraction is
applied to the wafer in that state, the bottom face of the wafer is
cooled quickly and it produces a difference in heat distribution
between the top face and the bottom face of the wafer. This easily
causes large warp of the wafer. This is an undesirable factor for
generation of micro-cracks in the wafer. Further, any warp of the
wafer causes failure of vacuum, and it deteriorates the stability
of conveyance.
[0106] In the fit-in type, on the other hand, a largest margin for
the size of the recessed portion will be only about 1 mm. If the
margin is large, a wafer will move around within the hand. It means
a difficulty in robot arm positioning, as the robot arm teaching is
to be done. Also, in this system, there occurs a sliding contact
between a wafer and a guide member therefor, during wafer
positioning. This causes a problem of particle production due to
the friction.
[0107] In the mechanical gripping system as proposed in
aforementioned Japanese Laid-Open Patent Application, Laid-Open No.
22502/1995, the free-end grip moves slidingly. Thus, particles are
produced, which causes contamination of a wafer. Further, it uses a
sliding cylinder in a driving source, and, also in this respect,
there is a problem of particle production.
[0108] Moreover, in conventional systems described above, where a
high-temperature wafer as having been high-temperature processed by
a processing system such as a resist removing apparatus is to be
conveyed, because of a difference in thermal distribution between
the top and bottom faces of the wafer, the wafer is deformed
largely. This makes the conveyance very unstable. For this reason,
it is necessary to delay the start of wafer conveyance until the
wafer temperature decreases and the warp is stabilized. This is a
large loss of time, and the throughput of the manufacturing system
as a whole is lowered considerably.
[0109] This embodiment uses a robot hand of the structure to be
described below, to avoid these inconveniences.
[0110] FIG. 20 is a top plan view of a robot hand as a first
example, in a state before gripping a wafer (hereinafter,
"un-gripped state"). FIG. 21 is a side view of the robot hand. FIG.
22 is a similar top plan view of the robot hand, but showing it in
a state after gripping a wafer. FIG. 23 illustrates the procedure
for picking up (unloading) a wafer on a wafer table, by using this
robot hand. FIG. 24 illustrates the procedure for placing (loading)
a wafer on a wafer table, by using the robot hand.
[0111] As shown in FIGS. 20 and 21, the robot hand 100 has a
supporting base table 101 which, when viewed from the above of a
wafer W, has a forked shape having two parallel extensions. Two
fixed pawls 102 are provided at the free ends of these extensions.
On the other hand, in an opposite direction thereto, there are two
movable pawls 103 having rollers 114. These fixed pawls 102 and
movable pawls 103 are disposed so as to be engaged with a
circumferential periphery of the wafer W when the same is gripped.
The fixed pawls 102 may be made rotatable in response to engagement
with the wafer circumferential periphery.
[0112] Each fixed pawl 102 is fixedly mounted at a free end of the
fork described above, and the its engagement portion with the wafer
edge face is formed into a circular shape (or arcuate shape). Also,
there is a wafer abutment 102a formed in a portion of the fixed
pawl, for supporting the wafer W.
[0113] The movable pawls 103 have a slider 107 movably mounted on
the supporting base table 101 through a linear motion bearing
(rolling type), two arms 105 swingably mounted on this slider 107
through hinges 106, and a spring 108 for applying a tension holding
force to these arms 105 through spring hooks 109. The rollers 114
mounted at the free ends of the arms 105 for engagement with the
wafer edge face, are made rotatable. The two arms 105 are pulled
toward each other by the spring 108, and also they are made
swingable in predetermined directions .theta..sub.1 and
.theta..sub.2, respectively. The slider 107 is connected to an end
of a bellows 104 which can be expanded and contracted in response
to a pneumatic pressure. The other end of the bellows 104 to a
bellows table 115, fixedly mounted on the supporting base table
101.
[0114] The expansion/contraction operation of the bellows 104 is
limited by stopper means (not shown) which is provided in a portion
of the slider 107. The operational stroke of the bellows ranges
from a smallest distance necessary for obtaining a sufficient
gripping force at the fixed pawls 102 to a largest distance for
obtaining a sufficient space for receiving a wafer.
[0115] A single air tube 116 is connected to this bellows 104, to
supply an air to the bellows. Another end (not shown) of this air
tube is connected to an electromagnetic valve (not shown) by which
pressurization and de-pressurization of the bellows 104 can be
interchangeably controlled, from the outside of the system. With
the structure of drive control using a single air tube such as at
116, the mechanism of the robot can be advantageously made very
simple.
[0116] Disposed on the supporting table 101 is a supporting pin 112
for supporting a wafer W in cooperation with the wafer abutments
102a, mounted on the fixed pawls 102.
[0117] In FIGS. 20 and 22, a reference numeral 111 denotes the
center of the wafer W, and a reference numeral 113 denotes a wafer
table (corresponding to the supporting pins 5 in FIG. 6) which is
on the processing unit side for processing the wafer.
[0118] The gripping operation for holding a wafer W through the
robot hand 100 of the structure described above, as well as its
un-gripping operation for releasing the gripping, will be described
below.
[0119] FIG. 20 shows the un-gripped state. Before a wafer is
loaded, the inside of the bellows 104 is evacuated to vacuum
through the air tube 116, by the control of the electromagnetic
valve (not shown). Through this vacuum attraction, the bellows 104
has been contracted in a direction of an arrow CS2 (FIG. 21), while
taking the bellows table 115 as a fixed point. Also, the slider 107
connected to the bellows 104 and movably mounted on the supporting
base table 101 for sliding motion along an X-X axis, has been
shifted in the same direction CS2 by an amount corresponding to the
contracted length of the bellows. Further, the arms 105 connected
to the slider 107 has been shifted together with the slider 107,
such that a sufficient space for placing a wafer W is defined
between the rollers 114, mounted on the free ends of the arms and
the fixed pawls 102. This state is the un-gripped state. In this
state, the wafer W is placed on the top faces of the supporting pin
112 and of the wafer abutments 102a of the fixed pawls 102, fixedly
mounted on the supporting table 101.
[0120] Next, the gripping operation for gripping the wafer W placed
in this un-gripped state, will be described with reference to FIG.
22.
[0121] In order to grip the wafer W placed un-gripped, a compressed
air is supplied into the the bellows 104. Changing the supply to
this compressed air is executed by means of the electromagnetic
valve, not shown. With the thus supplied compressed air, the
bellows 104 is expanded in a direction of an arrow CS1. Also, with
this expansion, the movable pawl structure 103 comprising the
slider 107, the arms 105, the rollers 114, the spring 108, and the
like, shifts in the direction CS1. In the course of this movement,
the rollers 114 engage with the edge face of the wafer W and press
the wafer W until it abuts against the fixed pawls 102. At this
moment, the movement of the wafer W is completed, so that the two
fixed pawls 102 and the two rollers 114 engage with the
circumferential periphery of the wafer W. However, at this moment,
the wafer W is not gripped sufficiently. Thus, the movable pawl 103
is then pressed more, by which the rollers 114 which are rotatably
mounted on the free ends of the two arms 105 are moved, while being
rotated, along the circumferential edge of the wafer W, and by
which, on the other hand, the two arms 105 pulled to each other by
the spring 108 are pivotably moved in .theta..sub.1 and
.theta..sub.2 directions, about their hinges 106, by predetermined
angles. Since the spring 108 applies a tension force sufficiently
holding the wafer W as the two arms 105 are opened by a
predetermined angle, the wafer W is thus gripped between the two
rollers 114 and the two fixed pawls 102 with a sufficient holding
force. At this moment, by means of the stopper (not shown) provided
on the slider 107, the expansion motion of the bellows 104 is
stopped, and this state is kept. This is the gripped state.
[0122] The swinging motion of the arms 105 in the gripping
operation will be explained in greater detail. At the moment
whereat the wafer W pressed by the rollers 114 brought into
engagement with the fixed pawls 102, since the arms 105 are not yet
swingingly moved in .theta..sub.1 and .theta..sub.2 directions, no
sufficient force for gripping the wafer W is not applied to the
rollers 114. When the movable pawls 103 are pressed more in the
direction CS1, in response it the rollers 114 moves along the
peripheral edge of the wafer W while being rotated, such that the
arms 105 are gradually swingingly moved in .theta..sub.1 and
.theta..sub.2 directions, respectively. With this swinging motion,
the spring 108 is extended by which a gripping force is gradually
produced. At the moment whereat a sufficient gripping force is
produced, the gripping operation is accomplished. Namely, this
structure provides a gradually gripping mechanism, rather than
applying the grip suddenly. As a result, the impact by the gripping
is very small, and production of particles by the impact can be
reduced effectively.
[0123] Although the gripping operation described above concerns a
wafer having a notch a wafer of circular shape, if a wafer having
an orientation flat with a large notch at the circumferential
periphery is used, similar operations such as described above may
be performed once the orientation of the orientation flat is fixed
in a particular direction.
[0124] In the robot hand 100 described above, the movable pawl 103
is moved by means of a bellows 104 being expanded and contracted by
a pneumatic pressure. Thus, as compared with a case where a drive
is provided by a sliding cylinder, the sliding motion area can be
reduced such that particle production can be suppressed. Also,
practically, there occurs no air leakage. Further, when the movable
pawl 103 engages with the wafer, the two arms 105 connected to each
other by the spring 108 are swingingly moved to be opened to
thereby absorb any impact. Therefore, the impact is very small, and
particle production due to the impact can be reduced.
[0125] Further, rollers 114 are provided at the free ends of the
pawl 103, and these rollers are arranged to move along the wafer
circumference while being rotated. Thus, particle production due to
sliding motion there can be prevented. Additionally, the wafer
bottom face side structure for conveyance has a forked shape, and
there is a large void. As a result, even when a high-temperature
wafer W is to be conveyed, the heat collected between the wafer W
bottom face and the robot hand 100 can be released effectively.
Therefore, the heat distributions on the top face and bottom face
of the wafer W are uniformed, and unwanted warp of the wafer can be
avoided. This accomplishes assured gripping of the wafer W.
[0126] Next, referring to FIGS. 23 and 24, loading and unloading
operations of the robot hand 100 will be explained.
[0127] The following description will be made on an assumption that
the robot hand 100 moves along an X-X axis (FIG. 20) containing a
portion about the center 111 of the wafer W, and that a direction
along this axial direction in which the robot hand 100 goes toward
a wafer table 113 is denoted by RS1 while a direction in which the
robot hand 100 moves away from the wafer table 113 is denoted by
RS2. Also, in the upward and downward relative movement of the
robot hand 100 relative to the wafer W on the wafer table 113, the
upward direction is denoted by ZU while the downward direction is
denoted by ZD.
[0128] FIG. 23 illustrates an unloading (receiving) operation. In
order to move the robot hand 100 to receive a wafer W placed at a
predetermined position on the wafer table 113, first, the robot
hand 100 is moved in the direction RS1 while a predetermined gap G2
is kept between the bottom face of the wafer W, placed on the table
113, and the top faces of the fixed pawls 102 at the free ends of
the hand so that they do not contact with each other. The robot
hand 100 is moved to a position shown in a portion (a) in FIG. 23.
At this position, as illustrated, a gap G1 is defined between the
wafer contact surface of the fixed pawl 102 and the end face of the
wafer W. Thus, as the robot hand 100 moves in the direction ZU, the
wafer contact surface of the fixed pawl 102 does not contact with
the end face of the wafer W. At this time, the movable pawl 103 of
the robot hand 100 is in the un-gripped state.
[0129] In this state, the robot hand 100 moves upwardly in the
direction ZU, to a position shown in a portion (b) of FIG. 23. In
the course of this movement, the bottom face of the wafer W is
supported by the wafer abutment 102a of the fixed pawl 102 of the
robot hand 100 and by the supporting pin 112, such that the wafer
is transferred to the robot hand 100 from the wafer table 113.
Here, as regards the movement distance of the robot hand 100 in the
direction ZU, an extent with which the bottom face of the wafer W
can be released away from the wafer table 113 and a clearance U can
be formed therebetween, to avoid interference with the subsequent
motion of the robot hand 100, will be sufficient.
[0130] Subsequently, as shown in a portion (c) in FIG. 23, at the
moment where the robot hand 100 has moved in the RS2 direction by a
predetermined distance S, the movable pawl 102 is moved in the
direction CS1 to thereby grip the wafer W. Here, as regards the
distance S for moving the robot hand 100, if the wafer table 113 is
provided by a wafer cassette, the distance should be of an extent
which assures that, when the wafer W moves by an amount
corresponding to the gap G1 as the same is gripped, the wafer W
does not abut against a wafer stopper, not shown (usually, it is
provided in the depth direction of the wafer cassette, for
positioning of the wafer in the depth direction).
[0131] After the movable pawl 103 grips the wafer W as described
above, while keeping the grip, the robot hand 100 moves further in
the RS2 direction. At the origin position, it stands by for a
subsequent operation. With these sequential operations, the wafer
unloading (receiving) operation is accomplished.
[0132] The wafer loading (sending) operation will now be described.
First, the robot hand having a wafer W gripped thereon is moved in
the direction RS1, toward the position of the wafer table 113, as
shown in a portion (b) of FIG. 24. Here, in order to prevent
contact between the bottom face of the wafer W and the top face of
the wafer table 113, a clearance U is kept therebetween. The
movement of the robot hand 100 is continued until the center of the
wafer W reaches a predetermined position on the wafer table 113 as
described hereinbefore, and then, the motion is stopped. This is
the position shown in the portion (b) of FIG. 24. This position
differs from the position shown in the portion (a) of FIG. 23 in
the wafer unloading operation described above. This is because of a
positional deviation resulting from the clearance G1 to the wafer,
in the wafer unloading operation.
[0133] Once the position of the robot hand 100 is determined, then,
the sequence goes to the operation for placing the wafer W upon the
wafer table 113. Thus, as shown in a portion (c) of FIG. 24, first
the grip of the wafer W is released (un-gripped state). Namely, the
movable pawl 103 is moved in the direction CS2 to thereby release
the gripping. Then, while keeping this state, the robot hand 100 is
moved downwardly, in the direction ZD. In the course of this
downward motion, the wafer W is transferred onto the wafer table
113. The robot hand 100 continues its downward motion until a
clearance G2 is defined between the bottom face of the wafer W and
the top face of the fixed pawl 102. As the clearance G2 is assured,
the downward motion is stopped. This corresponds to the state shown
in a portion (d) of FIG. 24. Subsequently, while keeping its
stopped position with respect to the downward direction, the robot
hand 100 moves in the direction RS2. At the origin position, it
stands by for a subsequent operation. With these sequential
operations, the wafer loading (sending) operation is
accomplished.
[0134] As described above, the teaching position for the robot hand
is changed, for the wafer loading operation and wafer unloading
operation. This effectively avoids unexpected contact between the
robot hand 100 and the wafer W. Further, by setting the wafer
gripping timing in the wafer unloading (receiving) operation with a
delay corresponding to the movement by a predetermined distance S
from the wafer receiving position, unexpected collision between the
wafer W and the wafer table side mechanism can be prevented. Thus,
the structure is very effective in respect to prevention of damage
of the wafer as well as prevention of particle production.
[0135] It will be readily understood that similar operation control
as has been described with reference to FIG. 15 or 18 may be
applied to the wafer loading and unloading operations in this
embodiment.
[0136] [Fourth Embodiment]
[0137] FIG. 25 shows another example of a robot hand. In this robot
hand 200, a movable pawl 103 has a single arm 105. Also, a slider
107 and a bellows 104 are connected with each other by means of a
U-shaped spring 128 for impact absorption. The remaining structure
is essentially the same as that of the robot hand 100 shown in FIG.
20. With this robot hand 200, substantially the same advantageous
effects as attainable with the robot hand 100 of FIG. 20 are
provided.
[0138] [Fifth Embodiment]
[0139] FIG. 26 shows a further example of a robot hand. This robot
hand 300 has a similar structure as of the robot hand 200 of FIG.
25, with an exception that the free ends of a forked-shape portion
of a supporting base table 101 are connected with each other, and
that a large evacuation space 121 is opened at the central portion
of the wafer W to prevent collection of heat between the wafer W
and the supporting table 101. With this structure, the rigidity of
the fixed pawls 102 is enlarged. Therefore, the fixed pawls 102 do
not easily shift, such that the reliability of wafer gripping is
improved.
[0140] While the present invention has been described above with
reference to some preferred embodiments thereof, the invention is
not limited to the disclosed forms. For example, although a
teaching position or positions are added in these examples to
enable two-stage switching (higher speed and lower speed switching)
of the operation speed with respect to a certain axis, more
teaching positions may be added to enable three-stage or more
switching of the set speed. Further, the present invention is
applicable also to various conveyance systems wherein substrates
are to be sequentially conveyed through plural units by means of
robot. Also, a bellows to be used in a hand mechanism of the
present invention may be driven by any other than an air described
above, such as a liquid, if appropriate.
[0141] In accordance with the present invention, as described
hereinbefore, an impact between a substrate and a substrate
conveying robot or a processing unit as the substrate is to be
transferred between a the conveying robot and various processing
units can be reduced significantly. Also, any shift as the
substrate is gripped can be reduced effectively. Therefore, assured
conveyance of a substrate is accomplished.
[0142] Further, a substrate conveying hand mechanism of the present
invention includes reduced sliding portions, such that the present
invention accomplishes a substrate conveying system of small
particle production and small wafer contamination.
[0143] While the invention has been described with reference to the
structures disclosed herein, it is not confined to the details set
forth and this application is intended to cover such modifications
or changes as may come within the purposes of the improvements or
the scope of the following claims.
* * * * *