Information
-
Patent Grant
-
6183810
-
Patent Number
6,183,810
-
Date Filed
Monday, January 18, 199925 years ago
-
Date Issued
Tuesday, February 6, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Beck; Shrive
- Calcagni; Jennifer
Agents
- Fulbright & Jaworski L.L.P.
-
CPC
-
US Classifications
Field of Search
US
- 427 240
- 427 425
- 118 52
- 118 320
-
International Classifications
-
Abstract
Disclosed is a method of forming a coating film, in which a coating solution is supplied from a linear nozzle onto a substrate held by a spin chuck arranged inside a cup having an opening so as to form a coating film on the substrate, comprising the steps of (a) allowing a spin chuck to hold rotatably a substrate, and (b) moving the linear nozzle and supplying a coating solution from the linear nozzle onto the substrate while rotating the substrate in a moving direction of the linear nozzle.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a coating film forming method and to a coating apparatus for forming a coating film such as a photoresist film or an anti-reflective coating film by applying a coating solution to a substrate such as a glass substrate for a liquid crystal display (LCD) device.
In the manufacturing process of an LCD device, a photolithography technology is employed as in the manufacturing process of a semiconductor device. In the photolithography employed for the manufacture of an LCD device, a resist coating film is formed on a glass substrate, followed by exposing the coating film to light in a predetermined pattern and subsequently developing the patterned coating film. Further, a semiconductor layer, an insulating layer and an electrode layer formed on the substrate are selectively etched to form a thin film of ITO (indium tin oxide), an electrode pattern, etc.
A so-called spin coating method is employed for coating an LCD substrate with a resist solution. A spin coater disclosed in, for example, U.S. Pat. No. 5,688,322 is employed for performing the spin coating treatment. In the spin coater disclosed in this prior art, an LCD substrate is held by vacuum suction by a spin chuck. Also, a solvent and a resist are supplied to the substrate, and an upper opening of a rotary is closed by a lid. Under this condition, the spin chuck and the rotary cup are rotated in synchronism. In this case, the coating amount of the resist, which is attached to the substrate, is only 10 to 20% of the supplied amount, with the remaining 80 to 90% of the supplied resist being discharged into a drain cup. The discharged resist solution is partly recycled for reuse. However, most of the discharged resolution is discarded.
In recent years, the LCD substrate is enlarged from 650×550 mm to 830×650 mm. If the LCD substrate is further enlarged in future, the consumption of the resist solution is further increased. Since the resist solution is wasted in a large amount in the conventional spin coating method as pointed out above, it is of high importance to decrease the waste of the resist solution.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention to provide a coating film forming method and a coating apparatus which permit decreasing the consumption of a coating solution used for coating a substrate.
Since an LCD substrate is rectangular, it is generally difficult to coat uniformly the entire surface of the LCD substrate with a resist solution. For uniformly coating the LCD substrate with a resist solution, a parallel moving mechanism of a nozzle is operated to permit a linear nozzle to be moved in parallel with a stationary LCD substrate. During the movement, a resist solution is spurted from the linear nozzle onto the substrate. However, since the conventional parallel moving mechanism of a nozzle has a large foot print (occupied floor area), the apparatus provided with the particular mechanism is rendered bulky. As a result of an extensive research made in an attempt to overcome the above-noted difficulties, the present inventors have arrived at the present invention.
According to an aspect of the present invention, there is provided a method of forming a coating film, in which a coating solution is supplied from a linear nozzle onto a substrate held by a spin chuck arranged inside a cup having an opening so as to form a coating film on the substrate, comprising the steps of:
(a) allowing a spin chuck to hold rotatably a substrate; and
(b) moving the linear nozzle and supplying a coating solution from the linear nozzle onto the substrate while rotating the substrate in a moving direction of the linear nozzle.
In the coating method of the present invention, the linear nozzle and the substrate are moved relative to each other to permit the linear nozzle to assume a predetermined posture relative to the substrate. As a result, the substrate is efficiently coated with the coating solution so as to decrease the consumption of the coating solution.
According to another aspect of the present invention, there is provided a coating apparatus, comprising a spin chuck for rotatably holding a substrate, a linear nozzle for supplying a coating solution onto the substrate, a nozzle moving mechanism for rocking the linear nozzle above the substrate, a rotary driving mechanism for rotating the spin chuck, a switching mechanism for allowing the coating solution to be spurted or not to be spurted from the linear nozzle, and a controller for controlling the rotary driving mechanism, the nozzle moving mechanism and the switching mechanism so as to supply the coating solution onto the substrate while rotating the substrate and moving the linear nozzle in a rotating direction of the substrate.
It is desirable for the linear nozzle to have a solution spurting port having a length corresponding to at least the shorter side of the rectangular substrate. Further, the coating apparatus may include a solvent supply source for supplying a solvent into the linear nozzle.
The coating apparatus may further include a shaking mechanism for shaking the linear nozzle to permit the longitudinal direction of the linear nozzle to be made parallel to the shorter side or longer side of the rectangular substrate, and a supporting arm mounted to the nozzle moving mechanism for supporting the linear nozzle. In this case, the shaking mechanism should desirably include a first bevel gear, a stationary frame for swingably supporting the supporting arm, a second bevel gear, a pivot joined to the linear nozzle, and a gear shaft arranged in a hollow portion of the supporting arm and provided with bevel gears engaged with the first and second bevel gears, respectively. Also, it is possible for the shaking mechanism to include a pivot rotatably mounted to the supporting arm and joined to the linear nozzle, and a small motor whose rotary driving shaft is joined directly or indirectly to the pivot and whose operation is controlled by the controller.
The coating apparatus may further include a back-and-forth moving mechanism for moving the linear nozzle forward or backward in the longitudinal direction of the linear nozzle until the solution spurting port of the linear nozzle overlaps with the entire region in the width direction of the rectangular substrate.
Further, the controller controls the operations of the nozzle moving mechanism and the rotary driving mechanism to permit a rocking angle α of the linear nozzle to be made equal to a rotating angle γ of the substrate and to permit a differentiation amount (α′=dα/dt), which is obtained by differentiating the rocking angle a with time, to be made equal to a differentiation amount (γ′=dγ/dt), which is obtained by differentiating the rotating angle γ with time.
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 hereinafter.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
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 plan view showing a resist coating-developing system for an LCD substrate;
FIG. 2
is a front view showing a resist coating-developing system for an LCD substrate;
FIG. 3
is a cross sectional view, including a block diagram, showing a resist coating apparatus;
FIG. 4
is an oblique view schematically showing a coating apparatus according to one embodiment of the present invention;
FIG. 5
is a cross sectional view showing a gist portion of a nozzle driving mechanism;
FIG. 6
is a plan view showing the positional relationship between a nozzle portion and the LCD substrate in the coating apparatus according to the embodiment of the present invention;
FIG. 7
is a cross sectional view schematically showing the tip portion of the nozzle portion;
FIG. 8
is a flow chart showing a series of resist processing steps applied to an LCD substrate;
FIG. 9
is a flow chart showing a coating film forming method according to the embodiment of the present invention;
FIG. 10
schematically shows a shaking mechanism for shaking the linear nozzle in the apparatus according to another embodiment of the present invention;
FIG. 11
schematically shows a back-and-forth moving mechanism for moving the linear nozzle back and forth in the apparatus according to another embodiment of the present invention; and
FIG. 12
is a plan view for explaining the operation of each of the linear nozzle and the LCD substrate in the apparatus according to still another embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Let us described preferred embodiments of the present invention with reference to the accompanying drawings. Specifically, a coating-developing system
1
comprises a loader/unloader section
2
, a first process section
3
, a second process section
4
, a third process section
5
and an interface section
6
, as shown in
FIGS. 1 and 2
. The system
1
is provided with various processing mechanisms for coating an LCD substrate G with a photoresist solution and developing the coated resist film and is connected to an light exposure apparatus
7
positioned adjacent to the interface section
6
.
The loader/unloader section
2
comprises a cassette table
10
and a transfer section
11
each extending in an X-axis direction. At most four cassettes C
1
, C
2
can be arranged in the cassette table
10
. LCD substrates G before processing are housed in the two cassettes C
1
, with the LCD cassettes G after the processing being housed in the other two cassettes C
2
. Each cassette is capable of housing a maximum of, for example,
25
LCD substrates. Incidentally, the LCD substrate G is sized at 830 mm×650 mm.
A first sub-arm mechanism
13
is mounted to the transfer section
11
of the loader/unloader section
2
. The first sub-arm mechanism
13
is provided with a holder for loading/unloading the substrate G into/out of each of the cassettes C
1
, C
2
, a back-and-forth driving mechanism for moving the holder back and forth, an X-axis driving mechanism for moving the holder in the X-axis direction, a Z-axis driving mechanism for moving the holder in a Z-axis direction, and a θ-swinging mechanism for rocking and swinging the holder about the Z-axis.
The first process section
3
comprises a central transfer path
15
A extending in a Y-axis direction, a first main arm mechanism
14
A movable along the transfer path
15
A, and a plurality of process units
16
,
17
,
17
and
18
. Two wet type washing units
16
are arranged on one side of the transfer path
15
A. Each of these washing unit
16
is provided with a brush scrubber SCR for scrub-washing the surface of the substrate G with a rotary brush while applying a washing solution onto the substrate G. On the other hand, a heating unit
17
, a dry type washing unit
18
and a cooling unit
19
are arranged on the other side of the transfer path
15
A. The heating unit
17
comprises and upper stage hot plates HP
1
and a lower stage hot plate HP
1
for heating the substrate G. The dry type washing unit
18
comprises an ultraviolet light washing device UV for washing the surface of the substrate G by irradiating the substrate G with an ultraviolet light. The cooling unit
19
comprises a cooling plate COLL for cooling the substrate G. Further, the first main arm mechanism
14
A is provided with a holder
14
a
for holding the substrate, a back-and-forth moving mechanism for moving the holder
14
a
back and forth, a Y-axis driving mechanism for moving the holder
14
a
in the Y-axis direction, a Z-axis driving mechanism for moving the holder
14
a
in the Z-axis direction, and a θ-driving mechanism for rocking and swinging the holder
14
a
about the Z-axis.
The second process section
4
comprises a central transfer path
15
B extending in the Y-axis direction, a second main arm mechanism
14
B movable along the transfer path
15
B, and a plurality of process units
21
,
24
,
25
and
26
. The process unit
21
, which is provided with a resist coating device
21
A and a peripheral resist removing device
21
B, is arranged on one side of the transfer path
15
B. The substrate G, which is kept rotated about its own axis, is coated with a resist solution by the resist coating device
21
A. On the other hand, an excess resist coating film is removed from the peripheral portion of the substrate G by the peripheral resist removing device
21
B.
An adhesion/cooling unit
24
, a heating/cooling unit
25
and a heating/heating unit
26
are arranged on the other side of the transfer path
15
B. The adhesion/cooling unit
24
includes an adhesion device AD for applying a hydrophobic treatment to the surface of the substrate G with a vapor of HMDS and a cooling plate COL
3
for cooling the substrate G. The heating/cooling unit
25
includes a hot plate HP
2
for heating the substrate and a cooling plate COL
3
for cooling the substrate. Further, the heating/heating unit
26
includes an upper stage hot plate HP
2
and a lower stage hot plate HP
2
for heating the substrate.
The third process section
6
comprises a central transfer path
15
C extending in the Y-axis direction, a third main arm mechanism
14
C movable along the transfer path
15
C, and a plurality of process units
28
,
29
,
30
,
31
,
32
,
33
and
34
. Three developing units
28
,
29
,
30
are arranged on one side of the transfer path
15
C. Each of these developing units
28
,
29
,
30
is provided with a developing device DEV for applying a developing solution to the substrate so as to develop the resist coating film. On the other hand, a titler
31
, a heating/heating unit
32
and heating/cooling units
33
,
34
are arranged on the other side of the transfer path
15
C. Each of the second and third main arm mechanisms
14
B,
14
C is substantially equal to the first main arm mechanism
14
A. It should be noted that a cooling unit
20
is arranged between the first process section
3
and the second process section
4
. Likewise, a cooling unit
27
is arranged between the second process section
4
and the third process section
5
. These cooling units
20
and
27
are used for temporarily storing the substrate G waiting for a processing.
The interface section
6
is interposed between the third process section and the light-exposure device
7
. A second sub-arm mechanism
35
and two buffer cassettes BC are arranged in a transfer/waiting section
36
. The second sub-arm mechanism
35
is substantially equal to the first sub-arm mechanism
13
. Substrates G waiting for a processing are temporarily stored in each of these buffer cassettes BC. A delivery table (not shown) is mounted in a delivery section
37
. The substrate G is delivered between the transfer mechanism (not shown) of the light-exposure device
7
and the second sub-arm mechanism
35
via the delivery table noted above.
Two loading/unloading ports (not shown) are formed in the front wall of the unit
21
. The unprocessed substrate G is loaded into the resist coating section
21
A through one of these loading/unloading ports. Also, the processed substrate G is unloaded from the peripheral coating film removing section
21
B through the other port. Incidentally, a transfer mechanism (not shown) is arranged between the resist coating device
21
A and the peripheral resist removing section
21
B so as to permits the substrate G from being transferred from the resist coating device
21
A into the peripheral resist removing section
21
B.
As shown in
FIG. 3
, the resist coating device
21
A is provided with a spin chuck
40
, a rotary cup
42
, a drain cup
44
, a lid
46
, a robot arm
50
, a solvent supply source
73
, a resist solution supply source
82
, a bellows pump
88
, a nozzle moving mechanism
100
, a nozzle section
110
and a controller
120
. The rotary cup
42
is arranged to surround the spin chuck
40
. Further, the drain cup
44
is arranged to surround the rotary cup
42
. The lid
46
is detachably mounted to the upper opening of the rotary cup
42
. A plurality of drain pipes
44
e
are connected to a bottom portion
44
d
of the drain cup
44
. The waste liquid is discharged through these drain pipes
44
e
into a recovery-regeneration device (not shown).
The rotary cup
42
is mounted to surround the upper portion and the circumferential outer portion of the spin chuck
40
. The rotary cup
42
is a cylindrical container having a bottom. A process space
41
for processing the substrate G is formed within the rotary cup
42
. Also, an opening is formed in a central portion at the bottom
42
b
of the rotary cup
42
. During the coating operation, the opening is closed by the spin chuck
40
. A plurality of discharge holes
65
are formed through the side wall
42
c
of the rotary cup. Liquid droplets and mist are discharged through these discharge holes
65
from within the rotary cup
42
into the drain cup
44
.
The spin chuck
40
is formed of a synthetic resin such as polyether ether ketone (PEEK). The rotating speed of a servo motor
51
is controlled by the controller
120
. A rotary shaft
52
a
of a rotary driving mechanism
52
is joined to the lower portion of the spin chuck
40
. The rotary shaft
52
a
is joined to a vertically movable cylinder
53
via a vacuum seal portion
60
and is also slidably joined to and supported by the lower portion of the rotary cup
42
via spline bearing
57
.
The rotary shaft
52
a
is joined to the spline bearing
57
so as to be slidable in a vertical direction. The spline bearing
57
is mounted to the inner surface of a rotary inner cylinder
56
a
which is rotatably mounted to the inner surface of a stationary color
54
with a bearing
55
a
interposed therebetween. A driven pulley
58
a
is mounted to the spline bearing
57
. Also, a belt is stretched between the driven pulley
58
a
and a driving pulley
51
b
. Further, a cylindrical body (not shown) is arranged on the side of the lower portion of the rotary shaft
52
a
. Within the cylindrical body, the rotary shaft
52
a
is joined to a cylinder
53
via the vacuum sealing portion
60
. The rotary shaft
52
a
is moved in a vertical direction by the cylinder
53
so as to cause the spin chuck
40
to be moved in a vertical direction.
A rotatable outer cylinder
56
b
is mounted to the outer circumferential surface of the stationary color
54
with a bearing
55
b
interposed therebetween. Also, a connecting cylinder
61
is fixed to the upper end of the rotatable outer cylinder
56
b
. The rotary cup
42
is mounted to the rotary driving mechanism
52
via the connecting cylinder
61
. A seal bearing
62
is interposed between the rotary cup
42
and the spin chuck
40
so as to permit the rotary cup
42
to be rotated relative to the spin chuck
40
. A driven pulley
58
b
is mounted to the rotatable outer cylinder
56
b
, and a belt
59
b
is stretched between the driven pulley
58
b
and a driving pulley
51
b
. Incidentally, the diameter of the driven pulley
58
b
is equal to the diameter of the driven pulley
58
a
. Also, two belts
59
a
and
59
b
are wound about the common servo motor
51
. It follows that the rotary cup
42
and the spin chuck
40
are rotated in synchronism.
The nozzle section
110
comprises a header
90
, first and second nozzles
111
,
112
, and a nozzle moving mechanism
100
. These first and second nozzles
111
and
112
are supported by a common supporting arm
113
and are moved by the nozzle moving mechanism between a home position outside of the drain cup
44
and an operating position inside the drain cup
44
.
As shown in
FIG. 7
, the inner space of the nozzle section
110
is partitioned by a partition plate
110
so as to form a fluid passageway of the first nozzle
111
a fluid passageway of the second nozzle
112
. These two fluid passageways communicate with a discharge port
111
a
and another discharge port
112
a
, respectively. A solvent
8
a
is spurted from the discharge port
111
a
, with a resist solution
8
b
being spurted from the other discharge port
112
a
. Each of these discharge ports
111
a
and
112
a
consists of a large number of fine holes arranged in series. It is necessary for each of these discharge ports
111
a
and
112
a
to be not shorter than the short side of the substrate G. It is possible for the length of each of these discharge ports
111
a
,
112
a
to be substantially equal to the long side of the substrate G. In this case, however, the nozzle section
110
is rendered unduly heavy, leading to a low operability of the nozzle section
110
. In order to decrease the weight of the nozzle section
110
, it is desirable for the length of the discharge ports
111
a
,
112
a
to be equal to the length of the short side of the substrate G. Incidentally, each of these discharge ports
111
a
,
112
a
may be shaped slit-like.
As shown in
FIG. 3
, the first nozzle
111
communicates with the solvent tank
73
via a tube
71
and a valve
72
. Also, a nitrogen gas supply source (not shown) communicates with the solvent tank
73
. If a nitrogen gas is supplied into the solvent tank
73
, the pressurizing force of the nitrogen gas causes the solvent
8
a
within the tank
73
to be supplied onto the substrate G. Incidentally, the operation of the nitrogen gas supply source is controlled by the controller
120
.
The second nozzle
112
communicates with a tank
82
housing a resist solution
8
b
via a tube
81
. Mounted to the tube
81
are a suck back valve
83
, an air operation valve
84
, a bubble removing mechanism
85
, a filter
86
and a bellows pump
88
in the order mentioned. The bellows pump
88
includes a flexible portion
87
. The flexible portion
87
is elongated or shrunk by a stepping motor
89
so as to allow a predetermined amount of the resist solution
8
b
to be supplied into the second nozzle
112
.
The suck back valve
83
serves to bring the resist solution
8
b
remaining within the discharged fluid passageway of the nozzle
112
back into the header
90
so as to prevent the residual resist solution
8
b
from being solidified within the discharged fluid passageway.
A temperature control mechanism
91
is mounted to the header
90
. A heat exchange fluid
8
c
is circulated into the inner fluid passageway of the temperature control mechanism
91
. The heat exchange fluid
8
c
exchanges heat with the solvent
8
a
and, then, with the resist solution
8
b
so as to set the temperatures of the solvent
8
a
and the resist solution
8
b
at desired levels, e.g., 23° C.
An annular passageway
44
a
, which is formed inside the drain cup
44
, communicates with four exhaust ports
66
formed through the outer circumferential wall of the drain cup
44
. Each of these exhaust ports communicates with an exhaust device (not shown). Also, a radial exhaust passageway
67
is formed in an upper portion along the inner circumferential surface of the drain cup
44
. The radial exhaust passageway
67
communicates with the annular passageway
44
a
and with the exhaust port
66
.
Further, a plurality of drain holes
44
e
are formed at the bottom portion
44
d
interposed between the outer wall
44
b
and the inner wall
44
c
. A tapered surface
44
f
is formed in the inner circumferential wall of the drain cup
44
. A small clearance is formed between the tapered surface
44
f
and the tapered surface
42
e
of the rotary cup
42
. Incidentally, the rotary cup
42
is positioned inside the drain cup
44
in the mechanism shown in the drawings. However, it is also possible for the rotary cup
42
to be arranged above the drain cup
44
.
Each part of the coating device
21
A used for processing an LCD substrate G sized at 830×650 mm is sized as follows. Specifically, the drain cup
44
has an outer diameter of about 130 mm and a height (depth) of about 220 mm. Each of the lid
46
and the rotary cup (inner cup)
42
has an outer diameter of about 110 mm. Further, the rotary cup
42
has a height (depth) of about 40 mm.
A supporting member
49
which projects upward is mounted to the central portion on the upper surface of the lid
46
. Also, a head portion
48
having a diameter larger than that of the supporting member is to the upper end of the supporting member
49
. The robot arm
50
is inserted into the lower side of the head portion
48
of the lid
46
so as to allow an engaging pin
50
a
projecting from the robot arm
50
to be engaged with an engaging groove
48
a
of the head portion
48
. If the head portion
48
is moved upward by this engagement, the lid
46
is moved upward from the cup
42
.
As shown in
FIG. 4
, a spurting head
90
is mounted to the tip portion of a supporting arm
113
, and the nozzle section
110
is mounted to the lower side of the spurting head
90
. The proximal end portion of the supporting arm
113
is joined to a driving force transmitting section
115
of the nozzle moving mechanism
100
, and the driving force transmitting section
115
is connected to a driving shaft
114
a
of a stepping motor
114
. The power source circuit of the motor
114
is connected to the output side of the controller
120
such that the operation of the motor
114
is controlled by using the program stored in the memory of the controller
120
.
Let us describe the nozzle moving mechanism
100
with reference to
FIGS. 5 and 6
. Specifically, the nozzle moving mechanism
100
comprises a mechanism
130
for rocking the nozzle
110
about a vertical driving shaft
114
a
and a mechanism
140
for swinging the nozzle
110
about a pivot
122
. The rocking mechanism
130
comprises a stepping motor
114
which is controlled by the controller
120
. The driving shaft
114
a
of the motor
114
is joined to a case
115
. The case
115
is joined to one end portion of the supporting arm
113
and is movably joined to a stationary frame
126
via conical roller bearing
134
. On the other hand, the other end portion of the supporting arm
113
is joined to the nozzle section
110
via the conical roller bearing
135
SO as to support the nozzle section
110
.
The supporting arm
113
is hollow. A gear shaft
131
is housed in a hollow portion
113
a
of the supporting arm
113
. Bevel gears
132
,
133
are mounted to the end portions of the gear shaft
131
. One bevel gear
132
is engaged with a bevel gear
126
a
of the stationary frame
126
, and the other bevel gear
133
is engaged with a bevel gear
122
a
of the pivot
122
. Also, the pivot
122
is movably joined to the supporting arm
113
via a conical roller bearing
136
. Further, the pivot
122
is joined to a connecting bar
110
a
of the nozzle section
110
.
The gear ratio of the bevel gears
122
a
,
126
a
,
132
and
133
is determined to permit the rocking angle α(=2θ) of the supporting arm
113
to be double the swinging angle δ(=θ) and the shaking angle β(=θ) of the nozzle section
110
, as shown in FIG.
6
. It should be noted that the rocking angle α denotes the rotating angle of the arm
113
about a central point M, the swinging angle δ denotes the rotating angle of the nozzle section
110
about a central point R, and the shaking angle β denotes the rotating angle of the nozzle section
110
about a central point N of the pivot
122
. Further, the controller
120
controls the driving of the servo motor
51
and the stepping motor
114
to permit the rotation angle γ(=θ) of the spin chuck
40
to be equal to each of the rocking angle δ(=θ) and the swinging angle β(=θ) of the nozzle section
110
. To be more specific, the controller
120
permits the rocking of the arm
113
, the swinging of the nozzle section
100
and the rotation of the substrate G to be performed in synchronism such that the nozzle section
110
and the substrate G are moved relative to each other so as to keep the positional relationship that the longitudinal axis of the nozzle section
110
is kept perpendicular to the longer side of the substrate G.
Under an optional position of the nozzle section
110
, an angle ∠KHR is kept at 90°, with the result that the locus of the central point N of the nozzle section
110
depicts a circle C in which a line KR constitutes the diameter. By rocking the supporting arm
113
about the center M of the line KR, the central point N of the nozzle section
110
is kept moved along a central line L in the longitudinal direction of the substrate G. Since the central point N of the nozzle section
110
is kept positioned on the central line L in the longitudinal direction of the substrate G while allowing the nozzle section
110
to be kept perpendicular to the longer side of the substrate G, the substrate G and the nozzle section
110
can be scanned linearly relative to each other.
Incidentally, a nozzle moving mechanism
100
B equipped with a small stepping motor
151
as shown in
FIG. 10
can be used in place of the nozzle moving mechanism
100
. The driving shaft (not shown) of the motor
151
is joined to a pivot (not shown) in a central portion in the longitudinal direction of the nozzle section
110
via a decelerator (not shown). Also, the power source circuit of the motor
151
is connected to an output section of the controller
120
. If the operations of these two motors
114
and
151
are controlled in synchronism by the controller
120
, the supporting arm
113
is rocked and the nozzle section
110
is shaken so as to achieve the relative positional relationship between the nozzle section
110
and the substrate G shown in FIG.
6
.
It is possible to arrange a plurality of spin chucks
40
on the circle C shown in
FIG. 6
so as to coat a plurality of substrates G with a resist solution by commonly using the nozzle section
110
.
Let us describe a series of resist treating process of the LCD substrate G with reference to FIG.
8
.
In the first step, a single substrate G is taken out of the cassette C
1
by the sub-transfer arm
13
so as to be delivered onto the first main transfer arm
14
A of the process section
3
(step S
1
). The substrate G is then transferred by the first main transfer arm
14
A into the unit
18
for washing the substrate G with an ultraviolet light ozone (step S
2
). Further, the substrate G is transferred by the main transfer arm
14
A into the unit
16
for subjecting the substrate G to a scrub-washing (step S
3
), followed by rinsing the substrate G with pure water and subsequently drying the substrate G under heat (step S
4
).
In the next step, the substrate G is transferred by the first main transfer arm
14
A into the unit
24
. Within the unit
24
, an HMDS vapor is applied to the substrate G while heating the substrate G so as to apply an adhesion treatment to the surface of the substrate G (step S
5
). Further, the substrate G is delivered from the first main transfer arm
14
A onto the second main transfer arm
14
B. Then, the substrate G is transferred by the second main transfer arm
14
B into the cooling unit
25
for cooling the substrate G.
The substrate G is taken out of the cooling unit
20
by the second main transfer arm
14
B so as to be transferred into the unit
21
. When the second main transfer arm
14
B arrives at a position in front of the resist coating device
21
A of the unit
21
, the shutter (not shown) is opened and the substrate G is transferred into the resist coating device
21
A. Then, the resist solution
8
b
is applied to the substrate G (step S
6
).
Let us describe the resist coating step S
6
in detail with reference to FIG.
9
.
In the first step, the lid
46
is opened, and the spin chuck
40
is moved upward so as to transfer the substrate G from the arm holder
14
b
of the second main arm mechanism onto the spin chuck
40
. Then, the arm holder
14
b
is retreated from the unit
21
, followed by closing the shutter. Under this condition, the spin chuck
40
holding the substrate G by vacuum suction is moved downward (step S
601
).
In the next step, the nozzle section
110
is moved from the home position toward the operating position so as to permit the nozzle
110
to be positioned right above the center of the substrate G. Under this condition, the solvent
8
a
is supplied from the first nozzle
111
onto the substrate G while rotating the substrate at a low speed. Then, the nozzle section
110
is brought back to the home position, followed by closing the lid
46
(step S
602
). Further, the temperature of the substrate G is controlled at a target temperature (23° C.) (step S
603
).
Then, the lid
46
is opened (step S
604
) and the nozzle section
110
is moved from the home position to the operating position. At the same time, the substrate G is rotated to align the positions of the nozzle section
110
and the substrate G such that the second nozzle
112
is overlapped with the shorter side of the substrate G as denoted by a two-dots-dash line in
FIG. 6
(step S
605
).
Then, the resist solution
8
b
begins to be spurted from the second nozzle
112
and, at the same time, the nozzle section
110
and the substrate G are moved (step S
606
). In this step S
606
, the controller
120
permits the rocking of the arm
113
, the swinging of the nozzle section
110
and the rotation of the substrate G to be performed in synchronism moves the nozzle section
110
and the substrate G such that the longitudinal axis of the nozzle section
110
is kept perpendicular to the longer side of the substrate G. As shown in
FIG. 6
, the rocking angle α(∠N
1
MN
2
=2θ) of the supporting arm
113
is twice the swinging angle β(∠MN
1
R=θ) of the nozzle section
110
, and the rotation angle γ(∠H
1
KH
2
=θ) of the spin chuck
40
is equal to the swinging angle β(∠MN
1
R=θ) of the nozzle section
110
. To be more specific, when the substrate G is in a first position P
1
, the center N
1
of the nozzle section
110
overlaps with the center H
1
of the shorter side of the substrate G. When the substrate G is in a second position P
2
, the center N
2
of the nozzle section
110
overlaps with the center K of rotation of the substrate G. Further, when the substrate G is in a third position P
3
, the center N
3
of the nozzle section
110
overlaps with the center H
3
of the shorter side of the substrate G. In other words, the center of the nozzle section
110
makes a relative linear movement on the substrate G along the loci H
1
-K-H
3
. As a result, the entire surface of the substrate G is coated with the resist solution
8
b
. It should be noted that the solvent
8
a
is already present on the surface of the substrate G, with the result that the resist solution
8
b
is rapidly diffused over the entire surface of the substrate G. Since the entire surface of the substrate G is coated uniformly with the resist solution
8
b
in this fashion, the consumption of the resist solution
8
b
can be markedly decreased. Incidentally, it is also possible to permit the resist solution
8
b
to be spurted from the second nozzle
112
while spurting the solvent
8
a
from the first nozzle
111
so as to further shorten the processing time.
When the substrate G is in the third position and when the center of the nozzle section
110
arrives at the position N
3
, the movements of both the substrate G and the nozzle section
110
are stopped and, at the same time, the supply of the resist solution
8
b
is stopped (step S
607
). Then, the nozzle section
110
is brought back to the home position (step S
608
), and the lid
46
is closed (step S
609
).
Further, the drain cup
44
begins to be exhausted and, at the same time, the substrate G and the rotary cup
42
begin to be rotated in synchronism (step S
610
). In this step S
610
, the rotating speed of the substrate G is set at about 500 rpm, and the maximum rotating speed of the substrate G is set at about 1350 rpm. As a result, the excess resist solution
8
b
is centrifugally separated from the substrate G so as to form a resist film of a uniform thickness on the substrate G.
In the next step, the lid
46
is opened (step S
611
), followed by moving upward the spin chuck
40
so as to release the substrate G held by vacuum suction by the spin chuck
40
. The substrate G is then taken up from the spin chuck
40
by a transfer mechanism (not shown) so as to be transferred into the peripheral coating film removing device
21
B (step S
613
).
In the peripheral coating film removing device
21
B, a thinner is applied to the peripheral portion of the substrate G so as to remove the resist coating film from the peripheral portion of the substrate G (step S
7
). Then, a mounting table (not shown) is moved upward so as to permit the second main transfer arm mechanism
14
B to take up the substrate G from the mounting table and to transfer the substrate G out of the unit
21
.
The second main transfer mechanism
14
B transfers the substrate G into a baking unit
26
. The substrate G is heated in the baking unit
26
so as to evaporate the solvent from the resist coating film (step S
8
). Then, the substrate G is transferred into the cooling unit
27
so as to be cooled. Further, the substrate G is transferred through the interface section
6
into the light exposure device
7
. The resist coating film is selectively exposed in a pattern within the exposure device
7
(step S
9
).
After the light exposure step S
9
, the substrate G is transferred into the unit
28
, in which a developing solution is applied to the resist coating film so as to develop a latent pattern image (step S
10
). Further, pure water is applied to the substrate G for the rinsing purpose, followed by heating the substrate G for the drying purpose (step S
11
). Still further, the substrate G is transferred into the cooling unit
33
for the cooling purpose. The substrate G after the processing is delivered onto the first to third main transfer arms
14
A,
14
B,
14
C and onto the sub-transfer arm
13
. Further, the substrate G is housed in the cassette C
2
within the loader section
2
by the sub-transfer arm
13
. Finally, the cassette C
2
housing the treated substrate G is transferred out of the system
1
so as to be further transferred toward the process apparatus in the subsequent steps (step S
12
).
FIGS. 11 and 12
show a nozzle moving mechanism
100
A according to another embodiment of the present invention. Those portions of this embodiment which are common with those of the embodiment described above are omitted in the following description.
As shown in
FIG. 11
, the nozzle moving mechanism
100
A is provided with a back-and-forth moving mechanism
118
in place of the swinging mechanism
140
. The back-and-forth moving mechanism
118
comprises a rod
116
a
joined to the supporting arm
113
and a cylinder
116
mounted to the case
115
A. The cylinder
116
communicates with an air supply source (not shown) which is controlled by the controller
120
. If the rod
116
a
is projected out of or retreated into the cylinder
116
, the nozzle section
110
is moved forward or backward in the longitudinal direction. The operation of the back-and-forth moving mechanism
118
is controlled by the controller
120
in synchronism with the rotating operation of the substrate G and with the resist solution spurting operation.
As shown in
FIG. 12
, the nozzle section
110
is controlled by the controller
120
so as to perform a rocking operation about the center M of rocking with a rocking angle of a. Also, the substrate G is controlled by the controller
120
so as to perform a rotating operation about the center K of rotation with a rotating angle γ. It should be noted that the swinging angle α is equal to the rotating angle γ. In addition, the differentiation amount dα/dt, which is obtained by differentiating the rocking angle α with time is equal to the differentiation amount dγ/dt, which is obtained by differentiating the rotating angle γ with time. The operations of the nozzle section
110
and the substrate G are controlled in the coating step
6
so as to maintain the relationship between the rocking angle α and the rotating angle γ as described above.
When the substrate G is in the first position P
1
, the center N
1
of the nozzle section
110
overlaps with the center of the shorter side of the substrate G. Also, when the substrate G is in the third position P
3
, H the center N
3
of the nozzle section
110
overlaps with the center of the shorter side of the substrate G. However, when the substrate G is in the second position P
2
, the center N
2
of the nozzle section
110
does not overlap with the center K of rotation of the substrate G. Therefore, the operation of the cylinder
116
is controlled such that, when the substrate G is rotated from the first position P
1
to the second position P
2
, the nozzle section
110
is moved forward and, when the substrate G is rotated from the second position P
2
to the third position P
3
, the nozzle section
110
is moved backward. It follows that the center of the nozzle section
110
makes a relative linear movement on the substrate G along the loci N
1
-N
2
-N
3
.
Since the rotation of the substrate G and the rocking of the nozzle section
110
are carried out in synchronism as described above, the relative positional relationship between the substrate G and the nozzle section
110
is as shown in FIG.
12
. To be more specific, the number of pulses for the servo motor
51
and the stepping motor
114
, which are calculated on the basis of the rocking angle α, the rotating angle γ, the differentiation amount (dα/dt) of the rocking angle, and the differentiation amount (dγ/dt) of the rotating angle, are set in advance in the controller
120
, and is supplied from the controller
120
to each of the servo motor
51
and the stepping motor
114
. Alternatively, it is possible to feed back the number of pulses extracted from one of the servo motor
51
and the stepping motor
114
to the other in synchronism with the number of pulses of the other of the servo motor
51
and the stepping motor
114
. Of course, an additional system can be employed for driving the motors in synchronism.
In each of the embodiments described above, a resist solution is used as a coating solution. However, an additional solution such as a developing solution can be employed in the coating system of the present invention.
Also, in each of the embodiments described above, a coating treatment is applied to a rectangular LCD substrate. However, an additional substrate such as a circular semiconductor wafer can also be processed by the coating system of the present invention.
What should also be noted that the nozzle moving mechanism included in the coating apparatus of the present invention has a small foot print, making it possible to prevent effectively the coating apparatus from being made bulky.
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 and representative embodiments 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.
Claims
- 1. A method of forming a coating film, in which a coating solution is supplied from a linear nozzle supported by a horizontal arm onto a rectangular substrate held by a spin chuck arranged inside a cup having an opening so as to form a coating film on the rectangular substrate, comprising the steps of:(a) allowing the spin chuck to hold rotatably the rectangular substrate and aligning the linear nozzle and the substrate relative to each other such that the linear nozzle is disposed in parallel with a short side or long side of the rectangular substrate; and (b) supplying a coating solution from the linear nozzle onto the substrate while rocking the linear nozzle in substantially a same direction as a rotating direction of the rectangular substrate while rotating the rectangular substrate, and shaking the linear nozzle in substantially an opposite direction to the rotating direction of the rectangular substrate, so that the coating solution is substantially uniformly spread over an entire upper surface of the rectangular substrate.
- 2. A method of forming a coating film, according to claim 1, wherein, in said step (b), the linear nozzle is advanced or retreated in a longitudinal direction of the horizontal arm.
- 3. The method of forming a coating film according to claim 1, further comprising the steps of:(c) mounting a lid to said cup to close the upper opening of the cup and, thus, to have said substrate confined within the cup; and (d) rotating the substrate confined within the cup so as to make the coating film formed on the substrate uniform in thickness.
- 4. The method of forming a coating film according to claim 1, wherein said coating solution is supplied from said linear nozzle to the substrate in said step (b) to cover an entire region in at least a width direction or length direction of the substrate.
- 5. The method of forming a coating film according to claim 4, wherein said substrate is rectangular, and said coating solution is supplied from said linear nozzle to the substrate in said step (b) to cover an entire region along the shorter side of the substrate.
- 6. The method of forming a coating film according to claim 1, wherein a solvent is supplied to the substrate before said step (b).
- 7. The method of forming a coating film according to claim 1, wherein said solvent is supplied from said linear nozzle.
- 8. The method of forming a coating film according to claim 1, wherein, in said step (b), said linear nozzle is rocked along a circle in which a straight line joining the center of rotation of the substrate and the center of rocking of the linear nozzle constitutes the diameter.
- 9. A coating apparatus comprising:a spin chuck for rotatably holding a rectangular substrate; a linear nozzle for supplying a coating solution onto the rectangular substrate; a switching mechanism for switching supply and stop of supply of the coating solution from the linear nozzle; a rotation drive mechanism for rotating the spin chuck; a horizontal arm for supporting the linear nozzle movably above the rectangular substrate held by the spin chuck; a rocking mechanism for supporting the horizontal arm and rocking the horizontal arm substantially within a horizontal surface; a shaking mechanism mounted on the horizontal arm, for shaking the linear nozzle substantially within the horizontal plane; and a control mechanism for controlling each of the switching mechanism, the rotation drive mechanism, the rocking mechanism and the shaking mechanism, so that a coating solution is substantially uniformly spread over an entire upper surface of the rectangular substrate when the coating solution is supplied from the linear nozzle onto the rectangular substrate while rocking the linear nozzle in substantially a same direction as a rotating direction of the rectangular substrate while rotating the rectangular substrate, and shaking the linear nozzle in substantially an opposite direction to the rotating direction of the rectangular substrate.
- 10. The coating apparatus according to claim 9, further comprising a solvent supply source for supplying a solvent to said linear nozzle.
- 11. The coating apparatus according to claim 9, wherein said controller controls the supporting arm rocking mechanism and the shaking mechanism to establish a relationship α′=2γ′=2β′ among the angular speed γ′ at which substrate is rotated, the angular speed α′ at which the supporting arm is rocked, and the angular speed β′ at which the linear nozzle is shaken relative to the supporting arm.
- 12. The coating apparatus according to claim 9, wherein said shaking mechanism comprises:a stationary frame provided with a first bevel gear for swingably supporting the supporting arm; a pivot provided with a second bevel gear and joined to said linear nozzle; and a gear shaft arranged within the hollow portion of the supporting arm and provided with bevel gears engaged with said first and second bevel gears, respectively.
- 13. The coating apparatus according to claim 9, wherein said shaking mechanism comprises:a pivot rotatably mounted to said supporting arm and joined to said linear nozzle; and a small motor whose rotary driving shaft is joined directly or indirectly to said pivot and whose operation is controlled by said controller.
- 14. The coating apparatus according to claim 9, wherein the nozzle moving mechanism comprises:a supporting arm; a supporting arm rocking mechanism for rocking the supporting arm; and a back-and-forth moving mechanism mounted to the supporting arm for moving the linear nozzle forward or backward in the longitudinal direction of the supporting arm.
- 15. The coating apparatus according to claim 9, wherein the control section permits the angular speed δ′ at which the linear nozzle is rocked and the angular speed γ′ at which the substrate is rotated to be made equal to each other.
- 16. The coating apparatus according to claim 9, wherein the control section permits the linear nozzle to be rocked along a circle in which a straight line joining the center of rotation of the substrate and the center of rocking of the linear nozzle constitutes the diameter.
- 17. The coating apparatus according to claim 9, further comprising a cup surrounding the substrate held by said spin chuck and receiving the coating solution dropping from the substrate.
Priority Claims (1)
Number |
Date |
Country |
Kind |
10-022547 |
Jan 1998 |
JP |
|
US Referenced Citations (6)