U.S. patent number RE37,470 [Application Number 09/388,589] was granted by the patent office on 2001-12-18 for substrate processing apparatus and substrate processing method.
This patent grant is currently assigned to Tokyo Electron Limited. Invention is credited to Naruaki Iida, Hiroyuki Kudou, Jun Ohkura, Yasuhiro Sakamoto, Masanori Tateyama.
United States Patent |
RE37,470 |
Ohkura , et al. |
December 18, 2001 |
Substrate processing apparatus and substrate processing method
Abstract
A wafer processing apparatus includes a common path, extending
in a Y-axis direction, in which one wafer or a plurality of wafers
are conveyed, a plurality of process units stacked on both sides of
the common path to constitute multi-stage structures, a main
handler moved in the common path in the Y-axis direction and
rotated about a Z axis at an angle .theta. to load/unload the wafer
into/from the process units, an arm section arranged to move in the
main handler in the Z-axis direction, a plurality of holding arms
arranged in the arm section to constitute a multi-stage structure
so as to respectively hold the wafers, each holding arm being
advanced and retreated on an X-Y plane from the arm section, an
optical sensor, arranged in the arm section, for detecting a
holding state of the wafer in each of the plurality of holding
arms, and a controller for controlling an operation of the main
handler, an operation of the arm section, and operations of the
plurality of holding arms on the basis of a detection result from
the optical sensor, wherein the controller advances or retreats
each holding arm while operating at least one of the main handler
and the arm section, and causes the optical sensor to detect the
holding state of the wafer by each holding arm before the holding
arm reaches a corresponding one of the process units.
Inventors: |
Ohkura; Jun (Kumamoto,
JP), Iida; Naruaki (Kumamoto, JP), Kudou;
Hiroyuki (Kikuchi-gun, JP), Tateyama; Masanori
(Kumamoto, JP), Sakamoto; Yasuhiro (Kamoto-gun,
JP) |
Assignee: |
Tokyo Electron Limited (Tokyo,
JP)
|
Family
ID: |
26378584 |
Appl.
No.: |
09/388,589 |
Filed: |
September 2, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
594937 |
Jan 31, 1996 |
05664254 |
Sep 2, 1997 |
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Foreign Application Priority Data
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Feb 2, 1995 [JP] |
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7-039254 |
Feb 9, 1995 [JP] |
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7-046413 |
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Current U.S.
Class: |
396/604; 118/500;
396/611; 396/612; 396/624; 414/152; 414/222.13; 414/940 |
Current CPC
Class: |
H01L
21/68707 (20130101); H01L 21/67781 (20130101); H01L
21/6715 (20130101) |
Current International
Class: |
H01L
21/67 (20060101); H01L 21/687 (20060101); H01L
21/677 (20060101); G03D 005/00 () |
Field of
Search: |
;396/604,611,624
;118/52,54,316,319,320,500,719
;414/416,225,939,937,935,786,749,940,941,152,222.13
;250/492.11,492.21 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Rutledge; D.
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier
& Neustadt, P.C.
Claims
What is claimed is:
1. A substrate processing apparatus for performing a plurality of
processes to a substrate comprising:
a common path.[., extending in a Y-axis direction,.]. in which one
substrate or a plurality of substrates are conveyed;
a plurality of process units stacked on .[.both sides of.]. said
common path to constitute multi-stage structures .Iadd.and
surrounding said common path.Iaddend.;
a main handler .[.moved in said common path in the Y-axis direction
and.]. rotated about a Z axis at an angle .theta. to load/unload
the substrate into/from said process units;
an arm section arranged to move in said main handler in the Z-axis
direction;
a plurality of holding arms arranged in said arm section to
constitute a multi-stage structure so as to respectively hold the
substrates, each holding arm being advanced and retreated on an X-Y
plane from said arm section, and wherein one holding arm of said
plurality of holding arms is located at a position higher than that
of another holding arm of said plurality of holding arms, .[.said
one holding arm having a portion which is brought into direct
contact with a substrate, said portion being made of a material of
a friction coefficient higher than that of a material of a
non-contact portion.]. ;
detection means, arranged in said arm section, for detecting a
holding state of the substrate held in each of said plurality of
holding arms; and
control means for controlling an operation of said main handler, an
operation of said arm section, and operations of said plurality of
holding arms on the basis of a detection result from said detection
means .Iadd.wherein said control means moves the arm section in a
Z-axis direction while rotating the main handler about a Z axis at
an angle .theta..Iaddend.;
wherein said control means advances or retreats each holding arm
while operating at least one of said main handler and said arm
section, and causes said detection means to detect the holding
state of the substrate held by each holding arm before said holding
arm reaches a corresponding one of said process units.
2. An apparatus according to claim 1, wherein said control means
advances and retreats each holding arm while at least one of said
main handler and said arm section operates, and until said holding
arm intrudes into an interference area in which said holding arm
physically interferes with the process unit.
3. An apparatus according to claim 1, wherein said detection means
comprises an optical sensor having an optical axis in the Z-axis
direction, and
when the holding arm which holds the substrate is advanced, said
held substrate crosses the optical axis to shield a detection beam,
thereby detecting said held substrate.
4. An apparatus according to claim 3, further comprising a support
member for supporting one of said holding arms, wherein said
support member is formed with an opening through which said
detection beam passes, and wherein said holding arms are arranged
in said arm section such that said holding arms can be
independently advanced or retreated, and
said control means operates said holding arms such that an advance
period of one holding arm overlaps a retreat period of another
holding arm, and detects the detection beam passing through the
opening during this operation.
5. An apparatus according to claim 1, wherein each process unit
comprises an opening facing toward said common path and a mounting
table which the substrate is mounted on,
said holding arm is advanced .[.in the X-axis direction.]. to load
the substrate into said process unit through said opening, and said
arm section is moved downward in the Z-axis direction to transfer
the substrate onto said mounting table, and
said arm section is moved upward in the Z-axis direction to lift
the substrate from said mounting table, and said holding arm is
retreated .[.in the X-axis direction.]. to pick the substrate from
said process unit through said opening.
6. An apparatus according to claim 1, further comprising a
sub-handler for receiving the substrate from said main handler, and
for transferring the substrate to said main handler.
7. An apparatus according to claim 1, wherein said detection means
comprises a light-emitting portion arranged above said holding arms
and a light-receiving portion arranged below said holding arms.
8. An apparatus according to claim 1, wherein said arm section has
first and second arms each having a first holding member for
holding a peripheral portion of the substrate to be processed, and
a third arm having a section holding member which is brought into
contact with only a lower surface of the substrate to be
processed.
9. An apparatus according to claim 1, wherein said control means
comprises arithmetic means for calculating moving distances of said
main handler and arm section, and accelerations used when said main
handler and said arm section are moved are increased/decreased
depending on a moving distance of the main handler and a moving
distance of the arm section calculated by said arithmetic
means.
10. An apparatus according to claim 1, wherein said control means
decreases a downward moving speed of said arm section when the
substrate is transferred from each holding arm onto said mounting
table in a corresponding one of said process units.
11. A substrate processing method comprising the steps of:
(a) a step of loading a substrate from a cassette station into a
process section;
(b) a step of causing a holding arm to hold the substrate,
.Iadd.and rotating the substrate about a Z axis at an angle
.theta., and simultaneously .Iaddend.moving the substrate in a
.[.Y-axis direction along a common path in said process section,
moving the substrate in a.]. Z-axis direction.[., and rotating the
substrate about a Z axis at an angle .theta..]. ;
(c) a step of loading the substrate into a process unit;
(d) a step of unloading the processed substrate from said process
unit; and
(e) a step of unloading the substrate from said process section to
said cassette station;
wherein said step of loading the substrate into a process unit and
said step of unloading the processed substrate from said process
unit are performed simultaneously.
12. A method according to claim 11, wherein, in the step (b),
a holding state of the substrate by said holding arm is changed
depending on a type of a process in one process unit, and a convey
speed used when the substrate is conveyed from said process unit to
another process unit is changed.
13. A method according to claim 11, wherein, in the step (c),
said holding arm is advanced .[.to an X-axis direction.]. to load
the substrate into said process unit through an opening, and an arm
section is moved downward in the Z-axis direction to transfer the
substrate onto a mounting table in the process unit, and
said arm section is moved upward in the Z-axis direction to lift
the substrate from said mounting table, and said holding arm is
retreated .[.in the X-axis direction.]. to pick the substrate from
said process unit through said opening.
14. A method according to claim 11, wherein, in the step (b),
an acceleration and a deceleration used when the substrate is moved
is changed depending on a moving distance of the substrate.
15. A method according to claim 11, wherein, in the step (c), a
downward moving speed of said arm section is decreased when the
substrate is transferred from said holding arm onto a mounting
table in said process unit.
16. A substrate processing apparatus for performing a plurality of
processes to a substrate comprising:
a common path.[., extending in a Y-axis direction,.]. in which one
substrate or a plurality of substrates are conveyed;
a plurality of process units stacked on .[.both sides of.]. said
common path to constitute multi-state structures .Iadd.and
surrounding said common path.Iaddend.;
a main handler .[.moved in said common path in the Y-axis direction
and.]. rotated about a z axis at an angle .theta. to load/unload
the substrate into/from said process units;
an arm section arranged in said main handler, having an
ascending/descending mechanism for moving said arm section in a
Z-axis direction, said ascending/descending mechanism further
including a slider connected to said arm portion, a guide rail for
guiding the slider in the Z-axis direction, a belt to which the
slider is attached, a driving pulley and a driven pulley between
which the belt is looped, a hollow rodless cylinder arranged in
parallel with the guide rail, and an upward moving force applying
means for supplying a compressed gas into a lower end of the
rodless cylinder to apply an upward force to the rodless
cylinder;
a plurality of holding arms arranged in said arm section to
constitute a multi-stage structure so as to respectively hold the
substrates, each holding arm being advanced and retreated on an X-Y
plane from said arm section;
detecting means, arranged in said arm section, for detecting a
holding state of the substrate held in each of said plurality of
holding arms; and
control means for controlling an operation of said main handler, an
operation of said arm section, and operations of said plurality of
holding arms on the basis of a detection result from said detection
means .Iadd.wherein said control means moves the arm section in a
Z-axis direction while rotating the main handler about a Z axis at
an angle .theta..Iaddend.,
wherein said control means advances or retreats each holding arm
while operating at least one of said main handler and said arm
section, and causes said detection means to detect the holding
state of the substrate held by each holding arm before said holding
arm reaches a corresponding one of said process units.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to substrate processing apparatus and
a substrate processing apparatus for processing a substrate such as
a semiconductor wafer.
2. Description of the Related Art
In a photolithography process in manufacturing a semiconductor
device, a resist coating process for coating a resist on a wafer
and a developing process for developing a coated resist after an
exposure process. These processes are simultaneously performed by
using a composite process system described in, e.g., U.S. Pat. No.
5,339,128. This system comprises a main handler for conveying a
wafer, and is designed such that a wafer W is loaded by the main
handler from a cassette station into a process section, the wafer W
are exchanged between process chambers in the process section, and
the above processes are performed.
A conventional handler has an arm section driven by three axes (Y
axis, Z axis, and .theta. rotation axis), and the arm section a
plurality of holding arms driven by only the X axis. All the 4-axis
drive operations in the main handler are independently
(individually) performed. For example, the arm section of the main
handler moves in the Y-axis direction first, moves in the Z-axis
direction, and then rotated at the angle .theta.. Finally, the
holding arms move in the X-axis direction to receive a wafer.
In recent years, a demand for an increase in a throughput for a
resist coating/developing process system is strong. For this
reason, in order to answer this demand, the main handler must be
operated at a speed as high as possible in a process section.
However, since the 4-axis drive operations in the X-axis direction,
Y-axis direction, Z-axis direction, and .theta.-rotation-axis
direction are independently performed in the conventional main
handler, the speed of the main handler operation is limited to a
certain speed. The main handler performs sequential operations,
e.g., the start of moving in the Y-axis direction, the end of the
moving of the Y-axis direction, the start of moving in the Z-axis
direction, the end of the moving of the Z-axis direction, the start
of moving in the .theta.-rotation-axis direction, the end of the
moving of the .theta.-rotation-axis direction, the start of moving
in the X-axis direction, and the end of the moving of the X-axis
direction. Therefore, a time from when the main handler reaches a
target point to when the main handler receive a wafer is too long
so that it is very difficult to increase the throughput.
In addition, when each drive system employs a high-speed drive
mechanism to more increase the operation of the main handler, an
excessive load acts on the mechanism, its durability and
reliability may be degraded. In addition, when the operation speed
of each drive system is increased, a noticeable amount of particle
is generated, the wafer is contaminated by attaching particle on
the wafer, and a yield may be decreased.
When a resist solution such as polyimide having a high viscosity is
used in a resist coating process, even after a side rinse process
in a coating device, the resist is not completely removed from the
wafer peripheral portion, and the resist may be partially left on
the wafer peripheral portion. When the residual resist is attached
to the holding arms of the main handler, the wafer W is easily
removed from the holding arms, and the wafer W cannot be smoothly
conveyed. For this reason, the contact area between the wafer
peripheral portion and the holding arms shall be minimized.
In a conventional method of conveying a wafer, independently of the
distance between a main handler and a target point, the main
handler is moved at a constant acceleration and a constant
deceleration. For this reason, the distance between the main
handler and the target point is long, the torque of a servo motor
instantaneously, excessively varies at the start of the servo
motor, vibration from the servo motor may be transmitted to the
main handler. When the main handler vibrates, the contact state
between the holding arms and the wafer W changes, and resist
residue easily moves to the holding arms.
In a process using a resist solution having a low viscosity, it may
be impossible to perform a side rinse process. For this reason, a
wafer W on which a resist is coated is conveyed, the resist is
attached to the holding arms due to vibration. This attached resist
is dried soon and removed from the holding arms, thereby generating
particles. In this manner, the wafer is contaminated by the
particles, and a production yield is decreased.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a substrate
processing apparatus and a substrate processing method in which a
substrate can be conveyed as a whole within a short time without
causing an excessive load to act on each drive mechanism to
increase a throughput and to suppress generation of particles.
It is another object of the present invention to provide a
substrate processing apparatus and a substrate processing method in
which vibration generated during convey of a substrate can be
suppressed, and a convey method can be selected depending on the
conditions of the substrate.
According to the present invention, there is provided to a
substrate processing apparatus for performing a plurality of
processes to a substrate comprising:
a common path, extending in a Y-axis direction, in which one
substrate or a plurality of substrates are conveyed;
a plurality of process units stacked on both sides of the common
path to constitute multi-stage structures;
a main handler moved in the common path in the Y-axis direction and
rotated about a Z axis at an angle .theta. to load/unload the
substrate into/from the process units;
an arm section arranged to move in the main handler in the Z-axis
direction;
a plurality of holding arms arranged in the arm section to
constitute a multi-stage structure so as to respectively hold the
substrates, each holding arm being advanced and retreated on an X-Y
plane from the arm section;
detection means, arranged in the arm section, for detecting a
holding state of the substrate held in each of the plurality of
holding arms; and
control means for controlling an operation of the main handler, an
operation of the arm section, and operations of the plurality of
holding arms on the basis of a detection result from the detection
means,
wherein the control means advances or retreats each holding arm
while operating at least one of the main handler and the arm
section, and causes the detection means to detect the holding state
of the substrate held by each holding arm before the holding arm
reaches a corresponding one of the process units.
The main handler, the arm section and the holding arms of the above
apparatus various multi-axis synchronous drive operations such as
(1) to (3) can be executed.
(1) A synchronous operation of Z-axis direction moving/.theta.
rotation is started, X-axis direction moving is started, a
synchronous operation of Z-axis direction moving/.theta. rotation
is completed, and the X-axis direction moving is completed.
(2) Z-axis direction moving is started first, .theta. rotation is
started, and a synchronous operation of Z-axis direction
moving/.theta. rotation is completed.
(3) .theta. rotation is started first, Z-axis direction moving is
started, and a synchronous operation of Z-axis direction
moving/.theta. rotation.
In each of all the operations, a time required to convey a wafer is
shorter than that in the conventional sequential operations. A
whole convey time can be adjusted to a longer one of a time
required for Z-axis direction moving and a time required for
.theta. rotation. In this manner, the wafer can be rapidly conveyed
at a rated moving speed within a time shorter than a time required
in the conventional operation. Furthermore, an amount of particle
generation can be suppressed.
A period of time until a substrate intrudes into an interference
area of the process unit such as the target point, the holding arms
can be synchronously advanced and retreated during moving of the
main handler. For this reason, a time required to convey a
substrate by the main handler can be shortened, and a throughput
increases.
When the holding arms are advanced and retreated while the main
handler moves in the Z-axis direction, it can be detected and
checked whether the substrate is held by the holding arms. On an
early stage before the next step, so that held wafer can be checked
in advance. A trouble can be prevented.
In case of using two upper and lower holding arms arranged on each
other, when the upper and lower arms are synchronously driven to
cause the advance operation period of the upper arm to overlap the
retreat operation period of the lower arm, a processed substrate
stored in the processing apparatus in advance can be rapidly
replaced with an unprocessed substrate (including not only an
unprocessed substrate but also a substrate processed in the
previous step) held by the holder member.
In addition, at this time, a notched opening is formed in the
support portion of each holding arm. For this reason, when the
upper and lower arms overlap, it can be detected through the
opening of one holding arm whether the other holding arm holds a
substrate.
According to the present invention, there is provided to a
substrate processing method comprises, the steps of;
(a) step of loading a substrate from a cassette station into a
process section;
(b) first moving step of causing a holding arm to hold the
substrate, moving the substrate in a Y-axis direction along a
common path in the process section, moving the substrate in a
Z-axis direction, and rotating the substrate about a Z axis at an
angle .theta.;
(c) second moving step of loading the substrate into a process
unit;
(d) third moving step of unloading the processed substrate from the
process unit; and
(e) step of unloading the substrate from the process section to the
cassette station.
In the process (b), a holding state of the substrate by the holding
arm is preferably changed depending on the type of a process in one
process unit, and a convey speed at which the substrate is conveyed
from the process unit into another process unit is preferably
changed. In the step (b), an acceleration and a deceleration at
which the substrate is moved is preferably changed depending on a
moving distance of the substrate. In addition, in the step (c),
when the substrate is transferred from the holding arm onto a
mounting table in the process unit, the downward moving speed of
the arm section is preferably decreased.
Additional objects and advantages of the invention will be set
forth in the description which follows, and in part will be obvious
from the description, or may be learned by practice of the
invention. The objects and advantages of the invention may be
realized and obtained by means of the instrumentalities and
combinations particularly pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings, which are incorporated in and constitute
a part of the specification, illustrate presently preferred
embodiments of the invention and, together with the general
description given above and the detailed description of the
preferred embodiments given below, serve to explain the principles
of the invention.
FIG. 1 is a perspective view showing the entire outline of a resist
coating/developing process system;
FIG. 2 is a block plan view showing a resist processing device
according to the first embodiment of the present invention;
FIG. 3 is a plan view showing the coating/developing process
system;
FIG. 4 is a rear view showing the coating/developing process
system;
FIG. 5 is a partially cutaway perspective view showing a main
handler;
FIG. 6 is a block sectional view showing the main handler;
FIG. 7 is a plan view showing an arm section of the main
handler;
FIG. 8 is a side view showing the arm section of the main
handler;
FIG. 9 is a sectional view showing a drive mechanism of the arm
section of the main handler;
FIG. 10 is a block sectional view showing the main handler when
viewed in a side direction;
FIG. 11 is a sectional view showing an adhesion unit serving as one
of process chambers;
FIGS. 12A and 12B are flow charts showing wafer convey procedures
when resist coating/developing processes are performed to a wafer,
respectively;
FIGS. 13A, 13B, 13C, 13D, 13E, 13F, 13G, 13H, and 13I are views for
explaining operations performed when a wafer is loaded/unloaded
into/from a process chamber by the main handler, respectively;
FIG. 14 is a plan layout view showing a resist processing apparatus
according to the second embodiment of the present invention;
FIG. 15 is a partially cutaway perspective view showing a main
handler;
FIG. 16 is a plan view showing an arm section of the main
handler;
FIG. 17 is a sectional view showing a drive mechanism of the arm
section of the main handler; and
FIGS. 18A, 18B, 18C, 18D, and 18E are views for explaining
operations performed when a wafer is loaded/unloaded into/from a
process chamber by the main handler, respectively.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the present invention will be described
below with reference to the accompanying drawings.
As shown in FIG. 1, a process section 11 of a resist
coating/developing process system 101 is arranged between a
cassette station 10 and an interface section 12. The process
section 11 comprises a central path 112, a brush-washing unit 103,
a jet-water-washing unit 104, an adhesion unit 105, a cooling unit
106, a resist coating unit 107, a heating unit 108, a peripheral
exposure unit 109, and a developing unit 111. These process units
103 to 111 are arranged on both the sides of the central path 112.
The wafer outlet/inlet port of each of the units 103 to 111 faces
the central path 112. The central path 112 extends, in the
longitudinal direction (Y-axis direction) of the system 101, from
the cassette station 10 to the interface section 12. A main handler
22 is arranged such that the main handler 22 can move in the
central path 112.
A cassette station 102 comprises a first sub-handler 21. The first
sub-handler 21 is designed to get a wafer W in and out of a
cassette CR and to give the wafer W to a main handler 22.
The interface section 12 comprises a second sub-handler 24. The
second sub-handler 24 is designed to receive the wafer W from the
main handler 22 and load the wafer into an exposure process section
(not shown). Note that the operations of the main handler 22 and
the first and second sub-handlers 21 and 24 are controlled by a
controller 90.
The brush-washing unit 103 is designed to brush-wash the wafer W.
The jet-water-washing unit 104 is designed to wash the wafer W with
high-pressure jet water. The adhesion unit 105 is designed to
perform a hydrophobic process (adhesion process) to the surface of
the wafer W in order to improve the fixing state of a resist. The
cooling unit 106 is designed to cool the wafer W. The resist
coating unit 107 is designed to coat a resist solution on the wafer
W. The heating unit 108 is designed to perform a heating process to
the wafer W before and after resist coating. The peripheral
exposure unit 109 is designed to remove the resist from the
peripheral portion of the wafer W. The developing unit 111 is
designed to develop the exposed wafer W with a developing
solution.
The process units in the system will be further described with
reference to FIGS. 2 to 4.
In the cassette station 10, a cassette placing table 20 having four
positioning projections 20a. Cassettes CR are positioned by the
positioning projections 20a to respectively have openings facing
the process section 11. These wafer cassettes CR are aligned in the
X-axis direction.
The first sub-handler 21 is arranged between the cassette placing
table 20 and the process section 11. The first sub-handler 21
comprises drive mechanisms (not shown) in the X- and Y-axis
directions, and is designed to selectively access the cassette
wafers CR. The first sub-handler 21 comprises a drive mechanism for
.theta. rotation, and is designed to also access alignment unit
(ALIM) and an extension unit (EXT) (to be described later).
In the process section 11, the large number of process units 103 to
111 are arranged. Of these process units, the adhesion unit 105,
the cooling unit 106, and the heating unit 108 are arranged to
respectively constitute multi-stage structures. In addition, the
brush-washing unit 103, the jet-water-washing unit 104, the resist
coating unit 107, the peripheral exposure unit 109, and the
developing unit 111 are arranged to respectively constitute
two-stage structures.
In this embodiment, as shown in FIGS. 3 and 4, the process section
11 comprises five process unit groups G.sub.1, G.sub.2, G.sub.3,
G.sub.4, and G.sub.5. The first and second multi-stage process unit
groups G.sub.1 and G.sub.2 are arranged on the front surface side
of the system, the third multi-stage process unit group G.sub.3 is
arranged adjacent to the cassette station 10, the fourth
multi-stage process unit group G.sub.4 is arranged adjacent to the
interface section 12, and the fifth multi-stage process unit group
G.sub.5 is arranged on the rear surface side of the system.
As shown in FIG. 3, in the first process unit group G.sub.1, as two
spinner type process units for placing a wafer W on a spin chuck
and performing a process to the wafer in a cap CP, a resist coating
unit (COT) and a developing unit (DEV) are stacked in this order.
In the second process unit group G.sub.2, two spinner type process
units, a resist coating unit (COT) and a developing unit (DEV) are
stacked in this order. In each of the resist coating units (COT)
are preferably arranged as lower stages because exhaust of the
resist solution is mechanically cumbersome in maintenance.
As shown in FIG. 4, in the third process unit group G.sub.3, open
type process units for placing a wafer W on a placing plate SP and
performing a predetermined process to the wafer W, a cooling unit
(COL), an adhesion unit (AD), an alignment unit (ALIM), an
extension unit (EXT), a pre-baking unit (PREBAKE), and a
post-baking unit (POBAKE) are sequentially stacked in this order to
constitute an 8-stage structure. In the fourth process unit group
G.sub.4, open type process units, a cooling unit (COL), an
extension/cooling unit (EXTCOL), an extension unit (EXT), a cooling
unit (COL), a prebaking unit (PREBAKE), and a post-baking unit
(POBAKE) are sequentially stacked in this order to constitute an
8-stage structure.
As described above, the cooling unit (COL) and extension/cooling
unit (EXTCOL) having low process temperatures are arranged as the
lower stages, the prebaking unit (PREBAKE), the post-baking unit
(POBAKE), and the adhesion unit (AD) are arranged as upper stages.
For this reason, thermal mutual interference between the units can
be reduced.
The interface section 12 has a dimension equal to that of the
process section 11 in the depth direction (X-axis direction) and a
dimension different from that of the process section 11 in the
width direction. On the front portion of the interface section 12,
a portable pickup cassette CR and a buffer cassette BR are arranged
to constitute two stages. On the other hand, a peripheral exposure
device 23 is arranged on the rear surface portion of the interface
section 12, and a second sub-handler 24 is arranged on the central
portion of the interface section 12.
The second sub-handler 24 comprises an X-axis drive mechanism and a
Z-axis drive mechanism, and is designed to move in the X- and
Y-axis directions and to access both the cassettes CR and BR and
the peripheral exposure device 23. In addition, the second
sub-handler 24 also comprises a .theta.-rotation drive mechanism,
and is designed to access the extension unit (EXT) belonging to the
process unit group G.sub.4 and a wafer exchange table (not shown)
on the exposure device adjacent to the second sub-handler 24.
The process unit group G.sub.5 indicated by a broken line in FIG. 2
can be arranged on the rear surface side of the main handler 22.
The process unit group G.sub.5 is arranged slidable along a guide
rail 25, and can be shifted in the side direction when viewed from
the main handler 22. Since a space can be assured by shifting the
process unit group G.sub.5, the main handler 22 can be subjected to
maintenance checking from the rear side of the main handler 22.
Note that the process unit group G.sub.5 is not only linearly
slide-shifted along the guide rail 25, but also pivotally shifted
out of the system as indicated by an alternate long and short dash
line in FIG. 2.
A main handler according to the first embodiment of the present
invention will be described below with reference to FIGS. 5 to
10.
The casing of the main handler 22 is constituted by a cylindrical
support member 33, and an arm section 34 is arranged in the
cylindrical support member 33 such that the arm section 34 can be
vertically moved in the Z-axis direction. The cylindrical support
member 33 comprises a pair of vertical wall portions 31 and 32
which are connected to each other at the upper and lower ends and
opposite to each other.
As shown in FIG. 6, the cylindrical support member 33 is connected
to the vertical drive shaft of a motor 35. When the cylindrical
support member 33 is rotated about the vertical drive shaft, the
arm section 34 is rotated together with the cylindrical support
member 33, thereby rotating the arm section 34 about the Z axis at
an angle .theta.. Note that the cylindrical support member 33 may
be constituted to be connected to another rotating shaft (not
shown) rotated by the motor 35.
The arm section 34 comprises a convey base 40 and three holding
arms 41, 42, and 43. The three holding arms 41, 42, and 43 are
vertically arranged on the convey base 40 to constitute a 3-stage
structure, and extend in the X-axis direction. Each of the holding
arms 41, 42, and 43 has a shape and a size which can passes through
a side opening 36 between both the vertical wall portions 31 and 32
of the cylindrical support member 33. Note that the holding arms
41, 42, and 43 are designed to move in the X-axis direction by a
drive motor (not shown) and a belt (not shown) which are
incorporated in the convey base 40.
The holding arms 41, 42, and 43 substantially have the same
arrangements. The arrangement of the holding arm 41 located at the
uppermost portion will be representatively described. The holding
arm 41, as shown in FIGS. 5, 7, and 8, comprises three support
members 41a for directly supporting the peripheral portion of a
wafer W, a holder member 41b, having an almost 3/4-annular shape,
for holding these support members 41a, and an arm member 41c for
supporting the holder member 41b. Note that the holding arm 41 is
designed to entirely move when a stay 41d arranged on the arm
member 41c is slid.
As shown in FIG. 7, a rectangular long hole 41e is formed in the
arm member 41c. Light-emitting portions 52a and 52b of a sensor 52
are located on the forward extended line in the longitudinal
direction of the long hole 41e.
The X-axis drive mechanisms of the holding arms 41, 42, and 43 are
variously controlled by the controller 90 backed up by a computer
system. For example, the X-axis drive mechanisms may be controlled
such that the second holding arm 42 is advanced during retreat of
the first holding arm 41, or the X-axis drive mechanisms may be
controlled such that in the second holding arm 42 is advanced to a
wafer detection position in an early stage of an advancing
operation of the second holding arm 42, and, thereafter, the second
holding arm 42 is further advanced depending on a wafer detection
result or is kept stopped.
As shown in FIG. 8, the interval between the first holding arm 41
located at the uppermost portion and the second holding arm 42 at
the middle portion is larger than the interval between the second
holding arm 42 and the third holding arm 43 at the lowermost
portion. This is because thermal interference between the wafer W
held by the first holding arm 41 and the wafer W held by the second
holding arm 42 is made as small as possible. Therefore, the first
holding arm 41 is desirably used from the cooling step to the
resist coating step, and the second and third holding arms 42 and
43 are desirably used in the steps in which the wafers W are not
adversely affected by thermal interference. Note that, in order to
further improve the thermal interference prevention effect, a heat
insulator may be arranged between the first holding arm 41 and the
second holding arm 42.
As shown in FIGS. 5 to 8, a sensor stand 51 is arranged on the
convey base 40, and light-emitting portions 52a and 52b for
emitting a laser beam are attached to the almost tip portion of the
sensor stand 51. The sensor 52 has the light-emitting portion 52a
and light-receiving portion 53a of the first sensor and the
light-emitting portion 52b and light-receiving portion 53b of the
second sensor. The light emitting portion 52a and light-receiving
portion 53a of the first sensor are to detect the presence/absence
of the wafer W in the holder member 41b (42b, 43b). The
light-emitting portion 52b and light-receiving portion 53b of the
second sensor are arranged outside the light emitting portion 52a
and light-receiving portion 53a of the first sensor to detect
whether the wafer W is held at a predetermined position of the
holder member 41b (42b, 43b) (whether the wafer sticks out of the
predetermined position).
The sensor 52 is connected to the controller 90. The controller 90
checks on the basis of a detection signal from the sensor 52
whether each of the holding arms 41, 42, and 43 holds the wafer W
(the presence/absence of wafer holding), and checks whether the
wafer W is held at correct positions.
An operation of detecting a wafer W by the sensor 52 will be
described below with reference to FIGS. 7 and 8.
When the holding arm 41 (42, 43) advances (retreats), and the front
edge portion of the wafer W advances to a position (position
indicated by a broken line M in FIGS. 7 and 8) between an optical
axis a and an optical axis b, laser beams are emitted from the
light-emitting portions 52a and 52b, respectively. When the optical
axis a is shielded by the wafer W, it is determined that the
holding arm 41 (42, 43) holds the wafer W. At the same time, when
the optical axis b is shielded by the wafer W, the wafer W is
correctly held by the holding arm 41 (42, 43) without sticking out
of the holding arm 41 (42, 43).
A Z-axis drive mechanism for vertically moving the arm section 34
of the main handler 22 will be described below with reference to
FIGS. 9 and 10.
A driven pulley 61 is arranged near the upper end portion in the
vertical wall portion 31, and a drive pulley 62 is arranged near
the lower end portion. An endless belt 63 is looped between the
driven pulley 61 and the drive pulley 62. The convey base 40 of the
arm section 34 is connected to the endless belt 63 through a belt
clamp 64. In addition, the drive pulley 62 is attached to a drive
shaft 65a of a motor 65 fixed on the bottom surface of the
cylindrical support member 33.
A pair of parallel guide rails 66 and 67 are vertically arranged on
the left and right end portion in the vertical wall portion 31. A
pair of horizontal support members 68 and 69 extend from the side
surface of the convey base 40, and sliders 70 and 71 are engaged
with the end portions of the horizontal support members 68 and 69
such that the sliders 70 and 71 can be slid on both the guide rails
66 and 67. When the vertical belt drive mechanism and vertical
slide mechanism described above are used, the arm section 34 can be
vertically moved in the Z-axis direction.
As shown in FIG. 10, a rodless cylinder 72 is vertically arranged
between the central portion in the vertical wall portion 31 and the
guide rail 66. An almost cylindrical mobile portion 72a is slidably
arranged on the rodless cylinder 72, the mobile portion 72a is
connected to the convey base 40 of the arm section 34 through the
horizontal support member 68. This mobile portion 72a is
magnetically coupled to the piston (not shown) of the rodless
cylinder 72, and the arm section 34 and the piston are designed to
be simultaneously moved through the mobile portion 72a.
A board 72b is attached to the lower end of the rodless cylinder
72. Compressed air having a pressure at which a force almost equal
to the weight of the arm section 34 is generated by the piston is
supplied to the board 72b. This compressed air is supplied from an
sir source 91 to the board 72b through a regulator 73 and a pipe
74. Note that the board 72c on the upper end of the rodless
cylinder 72 is open-air. In addition the sir source 91 and the
regulator 73 are controlled by the controller 90.
Since the weight of the arm section 34 is canceled by the operation
of the rodless cylinder 72, the arm section 34 can be moved upward
at a high speed. Even if the endless belt 63 for driving is cut,
the arm section 34 is kept at its position by dynamic lift from the
rodless cylinder 72, and the arm section 34 does not fall due to
its weight. Therefore, the arm section 34 and the cylindrical
support member 33 are not damaged.
Each drive mechanism is operated and controlled by the controller
90. The controller 90 can also rotate the main handler 22 at the
angle .theta. while the arm section 34 is moved in the Z-axis
direction. In addition, the controller 90 can advance/retreat the
holding arms 41, 42, and 43.
Processes for a wafer W in the resist coating/developing process
system 1 will be briefly described below.
The first sub-handler 21 accesses the cassette CR in the cassette
station 10, and then picks one of unprocessed wafers W from the
cassette CR. The first sub-handler 21 moves to the alignment unit
(ALIM) arranged in the third process unit group G.sub.3 on the
process section 11 side, and then transfers the wafer W into the
alignment unit (ALIM).
When orientation flat alignment and centering of the wafer W is
completed in the alignment unit (ALIM), the arm section 34 of the
main handler 22 receives the wafer whose alignment is completed,
moves it to a position in front of the adhesion unit (AD) located
under the alignment unit (ALIM) in the third process unit group
G.sub.3, and then loads the wafer W into the adhesion unit. The
wafer W is loaded into the cooling unit (COL) belonging to the
stacked units of the third process unit group G.sub.3 or the fourth
process unit group G.sub.4. The wafer W is cooled to, e.g.,
23.degree. C., in the cooling unit (COL).
The cooling process is completed, the main handler 22 causes the
first holding arm 41 to unload the wafer W from the cooling unit
(COL), exchanges the wafer W for the next wafer W held by the
second holding arm 42, and loads the cooled wafer W into the resist
coating unit (COT) belonging to the stacked units of the first
process unit group G.sub.1 or the second process unit group
G.sub.2. In this resist coating unit (COT), a resist solution is
coated on the wafer surface by a spin coating method to have a
uniform thickness.
When the resist coating process is completed, the main handler 22
unloads the wafer from the resist coating unit (COT), and loads it
into the prebaking unit (PREBAKE). In the prebaking unit (PREBAKE),
the wafer W is heated at, e.g., 10.degree. C., for a predetermined
time, and the residual solvent is evaporated and removed from the
coated film on the wafer W.
Upon completion of the prebaking process, the main handler 22
unloads the wafer from the prebaking unit (PREBAKE), and loads it
into the extension/cooling unit (EXTCOL) belonging to the stacked
units of the fourth process unit group G.sub.4. In this
extension/cooling unit (EXTCOL), the wafer is cooled to a
temperature, e.g., 24.degree. C., suitable for the next step, i.e.,
the peripheral exposure process in the peripheral exposure device
23. Upon completion of this cooling process, the main handler 22
conveys the wafer W into the extension unit (EXT) immediately above
the extension/cooling unit (EXTCOL), and places the wafer W on a
predetermined placing table (not shown) in the extension unit
(EXT).
When the wafer W is placed on the placing table of the extension
unit (EXT), the second sub-handler 24 accesses the wafer W from the
opposite side to receive the wafer W. The second sub-handler 24
loads the wafer W into the peripheral exposure device 23 in the
interface section 12. In this case, the peripheral portion of the
wafer W receives the exposure process.
Upon completion of the peripheral exposure process, the second
sub-handler 24 unloads the wafer W from the peripheral exposure
device 23, and transfers the wafer W onto a wafer receiving table
(not shown) on the exposure device adjacent to the peripheral
exposure device 23. In this case, before the wafer is received by
the exposure device, the wafer may be temporarily stored in the
buffer BR as needed.
Upon completion of entire pattern exposure process in the exposure
device, when the wafer W is returned onto the wafer receiving table
on the exposure device, the second sub-handler 24 accesses the
wafer receiving table to receive the wafer subjected to the
exposure process, and loads the wafer W into the extension unit
(EXT) belonging to the fourth process unit group G.sub.4. Note
that, in this case, before the wafer W is given to the process
section 11, the wafer W may be temporarily stored in the buffer
cassette BR in the interface section 12.
When the wafer W is loaded in the extension unit (EXT), the main
handler 22 accesses the wafer W from the opposite side to receive
the wafer W, and loads the wafer W into the developing unit (DEV)
belonging to the first process unit group G.sub.1 or the second
process unit group G.sub.2. In this developing unit (DEV), the
wafer W is placed on the pin chuck, and a developing solution is
uniformly poured on the resist on the wafer surface. When the
developed, exposed resist at the peripheral portion of the wafer
are completely removed, a rinse solution is poured on the wafer
surface to remove the developing solution.
Upon completion of the developing step, the main handler 22 unloads
the wafer W from the developing unit (DEV), and loads the wafer W
into the post-baking unit (POBAKE) belonging to the third process
unit group G.sub.3 and the fourth process unit group G.sub.4. In
this post-baking unit (POBAKE), the wafer W is heated at, e.g.,
100.degree. C., for a predetermined time.
Upon completion of the post-baking process, the main handler 22
unloads the wafer W from the post-baking unit (POBAKE), and loads
the wafer into one of the cooling unit (COL). In this case, after
the temperature of the wafer W returns to room temperature, the
main handler 22 conveys the wafer W into the extension unit (EXT)
belonging to the third process unit group G.sub.3.
When the wafer W is placed on a placing table (not shown) in the
extension unit (EXT), the first sub-handler 21 accesses the wafer W
from the opposite side to receive the wafer W. The first
sub-handler 21 loads the received wafer W into the a predetermined
slot of the cassette CR on the cassette placing table 20.
Throughout the resist coating and developing processes described
above, the main handler 22 operates most frequently. The above
wafer convey operations are continuously repeated, these processes
are simultaneously performed. Therefore, the main handler 22 is
reciprocated without an interval between the process units in the
process section 11 to convey the wafer W. For this reason, in order
to increase the throughput, it is necessary that the main handler
22 is rapidly and smoothly operated. In consideration of this
point, the main handler 22 having the arm section 34 according to
this embodiment performs the following convey operation.
For convey between the units, as shown in FIG. 2, the arm section
34 must horizontally convey the wafer W serving as a substrate to
be processes between the five unit groups G.sub.1 to G.sub.5
surrounding the main handler 22.
Since each of the process unit groups G.sub.1 to G.sub.5, as shown
in FIGS. 3 and 4, constitutes a multi-stage unit structure, the arm
section 34 always performs .theta. rotation and upward moving in
the Z-axis direction. In the wafer loading/unloading port of each
process unit, the holding arms 41, 42, and 43 are advanced and
retreated to perform transfer and exchange of the wafers.
Since the main handler can be rotated at the angle .theta. while
the arm section 34 moves in the Z-axis direction, various convey
processes described in (1) to (3) described below.
(1) Both Z-axis direction moving/.theta. rotation are started, and
both the Z-axis direction moving/.theta. rotation are
completed.
(2) Z-axis direction moving is started, .theta. rotation is
started, and both the Z-axis direction moving/.theta. rotation are
completed.
(3) .theta. rotation is started, Z-axis direction moving is
started, and both the Z-axis direction moving/.theta. rotation are
completed.
As a matter of course, in the above moving processes, the Z-axis
direction moving/.theta. rotation need not be completed at once,
the following stopping procedures can be employed. That is, the
.theta. rotation is completed upon completion of the Z-axis
direction moving, or the Z-axis direction moving is completed upon
completion of the .theta. rotation. In any case, the start of
moving and the completion of moving are preferably set depending on
the moving distance in the Z-axis direction and the angle .theta.
of the rotation.
When the parallel operation of Z-axis direction moving/.theta.
rotation using the above multi-axis synchronous drive operation is
employed, a load on the mechanism can be reduced, and a moving
operation can be performed quicker and smoother than a conventional
moving operation without excessively increasing the speed of each
drive system.
In addition, before the Z-axis direction moving and .theta.
rotation are completed, a necessary one of the holding arms 41, 42,
and 43 can be advanced in advance.
Note that the allowable area of moving of the holding arms 41, 42,
and 43 to be advanced/treated is an area except for an interference
area in which the holding arms 41, 42, and 43 adversely affect
various equipments or devices in each process unit. In other words,
the area is an area in which the holding arms 41, 42, and 43 do not
affect the various equipments and devices in their physical
conditions or process performance.
The arm section 34 has the sensor 52, the sensor 52 can
simultaneously detect the presence/absence of the held wafer and
the protruding portion of the held wafer while the main handler 22
is moved, and can quickly perform these checking operations before
the wafer is loaded into the process units. For this reason, a
trouble can be prevented, uniformity of a process in each process
unit can be assured.
When a processed wafer is exchanged for an unprocessed wafer, the
following procedures are performed.
(a) Advance of a no-load holding arm is started, and the advance is
completed.
(b) The processed wafer is received.
(c) Retreat of the holding arm which receives the processed wafer
is started, and retreat of the holding arm is completed.
(d) Advance of a holding arm which holds an unprocessed wafer is
started, and the advance is completed.
(e) The unprocessed wafer is given to a process unit.
(f) Retreat of the no-load arm is started, and the retreat is
completed.
In the method according to this embodiment, when a processed wafer
is exchanged for an unprocessed wafer, operations of the holding
arms 41, 42, and 43 are controlled by the following procedures.
(1) Advance of the no-load holding arm 41 is started, and the
advance is completed.
(2) The processed wafer is received.
(3) Retreat of the holding arm 41 which receives the processed
wafer is started, and advance of the holding arm 42 which holds an
unprocessed wafer is started.
(4) Retreat of the holding arm 41 which receives the processed
wafer is completed, the advance of the second holding arm 42 which
holds the unprocessed wafer is completed.
(5) The unprocessed wafer is given to a process unit.
(6) Retreat of the no-load holding arm 42 is started, and the
retreat is completed.
In the steps (3) and (4), operations of the two holding arms 41 and
42 overlap. Therefore, a time required for the exchange process is
shorter in the method of this embodiment than in a conventional
method.
The above exchange process described above and a wafer detection
operation can be parallelly performed. An operation in the adhesion
unit (AD) arranged in the third process unit group G.sub.3 will be
exemplified below.
FIG. 11 is a sectional view showing the main portion of the
adhesion unit (AD). A process vessel 81 of the adhesion unit (AD)
has a disk-like heating table (mounting table) 82, a cylindrical
heating plate holding member 83, and a lid 84. The lid 84 covers
the upper portion of the heating table 82 through a gap S.sub.1 and
a space S.sub.2. A gas supply port 84a is formed in the central
portion of the lid 84, and an HMDS (hexamethyldisilazane) gas is
supplied from the gas supply port 84a into the process vessel 81
through a gas supply pipe 85.
The lid 84 has a double-lid structure having an upper lid 84b and a
lower lid portion 84c which are vertically divided by two to form a
hollow portion S.sub.3 having a sectional area which gradually
increases from a portion near the gas supply port 84a to the
outside of the lid 84 in the radial direction. A gap S.sub.4 is
formed almost throughout the periphery between the peripheral
portion of the upper lid 84b and the inner side wall of the lower
lid portion 84c. A draft portion 84d is formed almost throughout
the periphery in the connection portion between the upper lid 84b
and the lower lid portion 84c. A gap 84e between the upper lid 84b
and the lower lid portion 84c communicates with an exhaust port 86
formed in the outer side surface of the lid 84. In this manner, the
HMDS gas supplied from the gas supply port 84a is uniformly
diffused toward the periphery in the space S.sub.2, and is
uniformly exhausted via the gap S.sub.4. The exhaust port 86 is
connected to an exhaust pump (not shown) through an exhaust pipe
87.
The heating table 82 consists of, e.g., aluminum, and a wafer W is
placed on the heating table 82. A heater and a temperature sensor
are incorporated in the heating table 82. Three through holes 82a
are formed in the heating table 82, and vertically movable support
pins 88 used for exchanging wafers are inserted into the through
holes 82a. When the wafer is loaded/unloaded, the support pins 88
project (move) upward from the upper surface of the heating table
82 to carry the wafer W. In this manner, wafers W are exchanged
between the holding arms 41, 42, and 43 of the main handler 22.
In the adhesion unit (AD) having the above arrangement, the HMDS
gas is supplied into the process vessel 81 while the process vessel
81 is evacuated in advance. The HMDS gas reacts to the wafer W
while the wafer is heated to improve the fixing and adhering
properties of the resist with respect to the wafer surface. Note
that the processed gas is exhausted from the exhaust port 86 to the
outside of the vessel through the gap S.sub.4 and the draft portion
84d of the lid 84. Therefore, an N.sub.2 gas is supplied from a gas
supply pipe 85 into the vessel to perform N.sub.2 gas purging.
Wafer exchanges before and after the adhesion process will be
exemplified with reference to FIGS. 12A and 12B and FIGS. 13A to
13I.
Assume that the main handler 22 is at a homo position first. Moving
of the main handler 22 is started from the homo position, and, as
shown in FIG. 13B, the second holding arm 42 and the third holding
arm 43 are alternately advanced to check the presence/absence of
wafer holding (step S1). Note that the first holding arm 41 at the
uppermost portion is not used when the wafer W is loaded/unloaded
into/from the adhesion unit (AD). For this reason, the first
holding arm 41 is omitted in FIGS. 13A to 13I.
The controller 90 checks on the basis of a detection signal from
the sensor 52 whether both the arms 42 and 43 are no-load arms
which hold no wafer W (step S2). If YES in step S2, the main
handler 22 causes the third holding arm 43 to receive an
unprocessed wafer W (step S3). If NO in step S2, the flow jumps to
the step S5 (to be described later). In this case, unprocessed
wafers W include not only an unprocessed wafer in the cassette
station 10 but also wafers in the other process units. Note that
the support pins 88 move upward from the heating plate 82 in the
vessel of the adhesion unit (AD) to carry a processed wafer
W.sub.1, thereby easily receiving the wafer W.sub.1 by the holding
arm.
While the main handler 22 moves toward the adhesion unit (AD)
serving as a target point, the second holding arm 42 and the
holding arms 41, 42, and 43 are alternately advanced to check the
presence/absence of wafer holding (step S4). Note that when the
unit for the previous process and the adhesion unit (AD) belong to
different process unit groups, respectively, the main handler 22 is
rotated at the angle .theta. while the arm section 34 is moved in
the Z-axis direction.
The controller 90 checks whether a wafer holding state stored in a
memory coincides with actual wafer holding states in the arms 42
and 43 (step S5).
While the arm section 34 moves in the Z-axis direction, as shown in
FIG. 13B, the second holding arm 42 advances to a predetermined
detection position, and detection beams are emitted from the two
light-emitting portions 52a and 52b of the sensor 52. At this time,
when the holding arm 42 is a no-load arm, both the light-receiving
portions 53a and 53b receives the beams. For this reason, it is
confirmed in advance that the holding arm 42 is set in a receivable
state. If one of the light-receiving portions 53a and 53b receives
a beam, it is determined that the second holding arm 42 is not set
in a receivable state, and the sequential operations are stopped.
At the same time, this may be displayed on an external device,
e.g., a monitor.
Thereafter, the second holding arm 42 which holds an unprocessed
wafer W.sub.0 advances to a predetermined detection position, the
two light-emitting portions 52a and 52b emit detection beams. As
shown in FIG. 13c, a support member 42c of the second holding arm
42 is located above a holding member 43b of the third holding arm
43 to cover the holding member 43b. However, since a long hole 42c
is formed in the second holding arm 42, the detection beam can
reaches the front edge portion of the third holding arm 43 and the
light-receiving portions 53a and 53b through the long hole 42e.
Therefore, the detection operation is not adversely affected by the
second holding arm 42.
When only the light-receiving portion 53b receives the detection
beam, and the light-receiving portion 53a does not receive the
detection beam, it is determined that the third holding arm 43
holds the wafer W.sub.0. At this time, if both the light-receiving
portions 53a and 53b do not receive the detection beam, it is
determined that the third holding arm 43 does not hold the wafer
W.sub.0. On the other hand, when both the light-receiving portions
53a and 53b receive the detection beams, it is determined that the
holding position of the wafer W.sub.0 sticks out of a predetermined
position.
If YES in step S5, the main handler 22 is caused to reach the
adhesion unit (AD) serving as the target point (step S6). If NO in
step S5, it is determined that abnormality occurs to perform an
abnormal process (step S13). In this abnormal process, the main
handler 22 is returned to the home position first, and an operator
confirms the actual states of the holding arms 42 and 43. After the
cause of the abnormality is removed, the operator pushes a reset
button to return the control to a normal process.
Moving of the main handler 22 is stopped, and, as shown in FIG.
13D, the second holding arm 42 serving as a no-load arm is inserted
into the adhesion unit (AD) (step S7). When the arm section 34 is
moved upward, as shown in FIG. 13E, the processed wafer W.sub.1 is
transferred to the second holding arm 42 (step S8).
As shown in FIGS. 13F and 13G, the second holding arm 42 is
retreated from the adhesion unit (AD), and the third holding arm 43
is inserted into the adhesion unit (AD) (step S9). When the arm
section 34 is moved downward, as shown in FIGS. 13H and 13I, the
unprocessed wafer W.sub.0 is transferred from the third holding arm
43 to the support pins 88.
The second holding arm 42 and the third holding arm 43 are
alternately advanced during or after retreat of the third holding
arm 43 to check the presence/absence of wafer holding (step S11).
The controller 90 checks whether the second holding arm 42 holds
the processed wafer W.sub.1, and whether the third holding arm 43
is a no-load arm which holds no wafer (step S12). If YES in step
S12, the main handler 22 is returned to the home position, or the
main handler 22 is moved toward the cooling unit (COL) in which the
next step is to be executed (step S1). If NO in step S12, it is
determined that abnormality occurs to perform an abnormal process
(step S13).
The semiconductor wafer is exemplified in the above embodiment.
However, according to the present invention, an LCD substrate, a CD
substrate, a photomask, various printed boards, or a ceramic
substrate can also be processed.
According to the apparatus of the present invention, a convey
operation can be performed at a speed higher than that of a
conventional convey operation without an excessive load acting on
the drive system, and a throughput can be increased with
suppressing particle generation.
Until holding arms are in the interference areas of process units
in which substrates are to be processed, the holding arms are
simultaneously advanced/retreated into/from the process units. For
this reason, the moving time of the overall convey device required
to load/unload the substrate in/from the processing apparatus can
be further shortened.
Since the presence/absence of substrate holding can be confirmed in
an early stage before a substrate is loaded into the processing
apparatus, a trouble related to substrate holding can be detected
in the early stage. Therefore, a time required to perform such
detection can be made shorter than that of a case wherein this
detection is performed when the convey operation is stopped.
A time required to exchange a processed substrate for an
unprocessed substrate and insert the unprocessed substrate into the
process unit can be made shorter than that of the prior art. In
addition, a trouble related to substrate holding in an exchange
operation can be detected in advance.
The second embodiment of the present invention will be described
below with reference to FIGS. 14 to 18E. The same reference
numerals as in the first embodiment denote the same parts in the
second embodiment, and a description thereof will be omitted.
In an apparatus according to the second embodiment, an acceleration
acting on a main handler 222 is controlled depending on the moving
distance to a target point. In addition, the wafer contact/holding
portion of a third holding arm 241 consists of a material having a
high friction coefficient to cope with control of the acceleration
of the main handler 222.
An arm section 34 of the main handler 222 comprises a first holding
arm 243, a second holding arm 242, and the third holding arm 241
which are sequentially arranged from below. Of these holding arms,
the lower two holding arms 243 and 242 are the same as those of the
first embodiment.
The third holding arm 241 at the uppermost portion, as shown in
FIGS. 16 and 17, comprises a holding member 241a having a flat
almost C-character shape, and a support member 241b for supporting
the holding member 241a. As shown in FIG. 16, when a wafer W is
held and conveyed by the third holding arm 241, only the lower
surface of the wafer W is brought into contact with the holding
member 241a, and is supported thereby. More specifically, the outer
diameter of the holding member 241a of the third holding arm 241 is
smaller than the outer diameter of the wafer W to be conveyed.
The inner diameter of the holding member 241a of the third holding
arm 241 is larger than the contact portion between the wafer W and
a spin chuck in a resist coating unit (COT) or a developing unit
(DEV).
The width of the notched opening in the front end of the holding
member 241a is set to be larger than the outer diameter of the spin
chuck. Therefore, the holding member 241a of the third holding arm
241 is brought into contact with the lower surface of the wafer W
in a hatched area in FIG. 16. When the third holding arm 241 is
formed to have the above shape, the third holding arm 241 is not
brought into contact with the spin chuck or support pins 88 when
the wafer W is loaded/unloaded into/from a process unit.
In the third holding arm 241, at least the upper surface of the
holding member 241a consists of a material having a high friction
coefficient, e.g., a rubber-based material. The frictional force
between the holding member 241a and the wafer W is increased, a
positional error can be prevented when the wafer conveyed.
In addition, the upper surface of the holding member 241a has heat
resistance to stand heat of, e.g., 100.degree. C. or more, and
preferably consists of a material which generates a small amount of
particle.
In this embodiment, the entire upper surface of the holding member
241a is in contact with the lower surface of the wafer W. However,
a plurality of projections (not shown) may be formed on the upper
surface of the holding member 241a to support the wafer W. Note
that the material of the holding member 241a itself except for its
upper surface may be, e.g., ceramic.
When a stay 241c arranged on the support member 241b is slid by a
drive motor (not shown), the third holding arm 241 is moved as a
whole in the front and rear directions of a convey base 240.
A long hole 41d having an almost rectangular shape, for forming an
opening along the longitudinal direction of the support member
241b, i.e., the moving direction of the third holding arm 241 is
formed in the support member 241b. Sensor light-emitting portions
52a and 52b are located on the line extending from the front of the
long hole 41d in the longitudinal direction.
In this embodiment, the accelerations and decelerations of Z-axis
direction moving of the arm section 34 and .theta. rotation of the
main handler 22 can be changed depending on the distance between
the process units.
For example, as shown in FIG. 14, the moving distance of the arm
section 34 when the arm section 34 moves from a third process unit
group G.sub.3 to a second process unit group G.sub.2 is longer than
the moving distance of the arm section 34 when the arm section 34
moves from a first process unit group G.sub.1 to the third process
unit group G.sub.3.
In this case, the acceleration and deceleration of the arm section
34 when the arm section 34 moves from the first process unit group
G.sub.1 to the third process unit group G.sub.3 are set to be
smaller than the acceleration and deceleration of the arm section
34 when the arm section 34 moves from the third process unit group
G.sub.3 to the second process unit group G.sub.2. In this manner,
an instantaneous excessive change in torque acting on the motor 35
is suppressed, and vibration is suppressed. A moving state wherein
the arm section 34 is suddenly stopped as soon as the arm section
34 suddenly advances can be avoided. Therefore, vibration to the
wafers held by the holding arms 241, 242, and 243 can be
suppressed, and preferable holding states can be realized.
The numerical values of the acceleration and deceleration are
calculated in advance depending on the convey distance between the
process units, and the controller 90 determines the numerical
values on the basis of a moving distance according to an actual
process to change the acceleration and deceleration.
After a resist solution is coated on the wafer W, the wafer W is
loaded into a prebaking unit (PREBAKE) in which a heating process
in the next step is performed. In this case, when the coated resist
solution is a resist solution having a high viscosity, e.g., a
polyimide-based resist solution, even if a side rinse process is
performed in a resist coating unit (COT), polyimide on the wafer
periphery is not easily removed. Therefore, the wafer W is conveyed
from the resist coating unit (COT) to the prebaking unit (PREBAKE),
the resist solution must be prevented from being attached to the
holding member for contact-holding the wafer W.
In consideration of this point, in the arm section 34 according to
this embodiment comprises the third holding arm 241 for supporting
only the central side of the lower surface of the wafer W. For this
reason, when the wafer W on which the resist solution is coated is
picked from the resist coating unit (COT) and conveyed into the
prebaking unit (PREBAKE), the wafer W is held by the holding member
241a of the third holding arm 241. In this case, the process
solution such as the resist solution on the peripheral portion is
not attached to the third holding arm 241.
When the wafer W is to be conveyed by using the third holding arm
241, the wafer W is conveyed such that the wafer W is placed on the
holding member 241a and held by a frictional force. For this
reason, in advance/retreat of the third holding arm 241, more
specifically, unloading from the resist coating unit (COT), loading
into the prebaking unit (PREBAKE), Z-axis direction moving, and
.theta. rotation, their speeds are desirably set to be lower than
those in another convey operation.
In this embodiment, a holding member for placing and holding a
wafer W is only the third holding arm 241. However, two or more
holding members for placing and holding wafers W may be arranged.
For example, when two third holding arms 241 are arranged, the
present invention can cope with a case wherein a so-called
multi-stage heating process must be performed after a resist
solution is coated.
A resist is not completely hardened by one (primary) heating
process, and a heating process (secondary) at a higher temperature
is continuously performed again. In this case, when it is still
undesirable that the lower edge of the periphery of the wafer W is
directly held when the primary heating process is completed, a
holding member (holding arm) for placing and holding a wafer W is
short in an exchange of wafers W in the next heating process unit.
Therefore, when a holding arm having the same arrangement as that
of the third holding arm 241 is arranged as the fourth arm, the
present invention can cope with the multi-stage heating
process.
The above description relates to control of an acceleration and a
deceleration when the wafer W is conveyed between the process
units, and selection of a convey means. However, when a vertical
moving speed of the arm section 34 in exchanges of the wafers
between the process units is controlled, an yield can be
increased.
A case wherein a wafer W is loaded into the adhesion unit (AD)
having the above arrangement, and the wafer W held by the holding
arm 242 is transferred onto the support pins 88 will be described
below with reference to FIGS. 18A to 18E. Note that each arrow in
FIGS. 18A to 18E indicates a moving speed. That is, a speed
indicated by two arrows is higher than a speed indicated by one
arrow.
As shown in FIG. 18A, after the holding arm 242 which holds a wafer
W advances to the downward moving start position of the holding arm
242 in the adhesion unit (AD), the arm section 34 as a whole is
moved downward at a relatively high speed at first.
When the wafer W held by the holding member 242a of the holding arm
242, as shown FIG. 18B, moves upward from the heating plate 82 of
the adhesion unit (AD) to become close to the top portions of the
support pins 88 which is standby for carriage, the downward moving
speed is switched, and the wafer is moved downward at a relatively
low speed. As shown in FIG. 18C, the wafer W is still moved
downward at a relatively low speed even when the lower surface of
the wafer W is brought into contact with the top portions of the
support pins 88. In addition, as shown in FIG. 18D, the wafer W is
carried on the support pins 88, and the wafer W is kept moved
downward at the relatively low speed until the holding member 242a
of the holding arm 242 reaches a position slightly separated from
the top portions of the support pins 88. Therefore, the downward
moving speed is switched to a relatively high speed. Subsequently,
as shown in FIG. 18E, the wafer is kept moved downward at the
relatively high speed until the holding arm 242 moves downward to a
downward point. After the holding arm 242 reaches the predetermined
downward point, the holding arm 242 is retreated.
As described above, the downward moving speeds of the holding arm
242 (arm section 34) are switched to each other. For this reason,
since the lower surface of the wafer W is brought into contact with
the top portions of the support pins 88 at a relatively low speed
when the wafer W is carried by the support pins 88, the shock is
small. Therefore, abnormal noise is not generated, and a positional
error of the wafer W does not occur. In addition, a total transfer
time is not considerably long.
Upon completion of the adhesion process, when the processed wafer W
is received by, e.g., the holding arm 242, the holding arm 242 (arm
section 34) is preferably moved upward such that the speed
switching operations are performed by the procedures reverse to the
above procedures. As these speeds, proper speeds are calculated by
an experiment or the like in advance. The speeds are automatically
selected from the proper speeds to perform variable control of the
speeds.
Note that control of a vertical moving speed in an exchange of
wafers W by the arm section 34 can be applied to not only an
exchange of wafers between the arm section 34 and a unit having the
support pins 88 but also an exchange of wafers between the arm
section 34 and another process unit having a spin chuck, e.g., the
resist coating unit (COT).
According to the method of the present invention, since an
acceleration in a convey operation is changed depending on a moving
distance, an acceleration and a deceleration are increased when the
moving distance to the target point to convey a wafer at a high
speed, and the wafer can be caused to reach the target point within
a short time. On the other hand, when the moving distance to the
target point is short, the acceleration and deceleration are
decreased to convey a wafer at a low speed, and vibration in a
convey operation can be suppressed.
According to the present invention, contamination caused by
attaching of a process solution or the like and a high-speed convey
operation can be realized with a good balance.
Additional advantages and modifications will readily occur to those
skilled in the art. Therefore, the invention in its broader aspects
is not limited to the specific details, representative devices, and
illustrated examples shown and described herein. Accordingly,
various modifications may be made without departing from the spirit
or scope of the general inventive concept as defined by the
appended claims and their equivalents.
* * * * *