U.S. patent application number 11/797334 was filed with the patent office on 2007-09-06 for system and methods for manufacturing a liquid crystal device.
This patent application is currently assigned to SEIKO EPSON CORPORATION. Invention is credited to Kazuaki Sakurada.
Application Number | 20070204795 11/797334 |
Document ID | / |
Family ID | 27800001 |
Filed Date | 2007-09-06 |
United States Patent
Application |
20070204795 |
Kind Code |
A1 |
Sakurada; Kazuaki |
September 6, 2007 |
System and methods for manufacturing a liquid crystal device
Abstract
The invention provides a thin-film forming device, a thin-film
forming method, a device for manufacturing a liquid crystal
display, a method for manufacturing a liquid crystal display, a
device for manufacturing a thin-film structure, a method for a
thin-film structure, a liquid crystal display, a thin-film
structure, and an electronic apparatus, objects are to achieve easy
control of thickness of a thin film without using rotation means,
cost reduction, and miniaturization of the devices. The thin-film
forming device for forming a thin film by applying a coating
solution onto a substrate, there can be provided an ejection
mechanism having a droplet ejection head for ejecting the coating
solution onto the substrate, a moving mechanism capable of
relatively moving the positions of the droplet ejection head and
the substrate, and a control unit for controlling at least one of
the ejection mechanism and the moving mechanism. As a result, the
control unit described above can control the thickness of the thin
film by changing the coating conditions of the coating solution L
by controlling at least one of an ejection operation by the
ejection mechanism and a moving operation by the moving
mechanism.
Inventors: |
Sakurada; Kazuaki;
(Shimosuwa-machi, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 19928
ALEXANDRIA
VA
22320
US
|
Assignee: |
SEIKO EPSON CORPORATION
TOKYO
JP
|
Family ID: |
27800001 |
Appl. No.: |
11/797334 |
Filed: |
May 2, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10368607 |
Feb 20, 2003 |
7226642 |
|
|
11797334 |
May 2, 2007 |
|
|
|
Current U.S.
Class: |
118/699 ;
118/313; 118/323 |
Current CPC
Class: |
Y10T 428/1023 20150115;
Y10T 428/10 20150115; H01L 21/6715 20130101; C09K 2323/00 20200801;
C09K 2323/027 20200801 |
Class at
Publication: |
118/699 ;
118/313; 118/323 |
International
Class: |
B05B 3/00 20060101
B05B003/00; B05C 5/02 20060101 B05C005/02 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 22, 2002 |
JP |
2002-046295 |
Claims
1. A thin-film forming device for forming a thin film by applying a
coating solution onto a substrate, comprising: an ejection
mechanism having a droplet ejection head that ejects the coating
solution onto the substrate; a moving mechanism capable of
relatively moving positions of the droplet ejection head and the
substrate; and a control unit that controls at least one of the
ejection mechanism and the moving mechanism, the control unit
changing coating conditions of the coating solution by controlling
at least one of an ejection operation by the ejection mechanism and
a moving operation by the moving mechanism so as to control a
thickness of the thin film.
2. The thin-film forming device according to claim 1, the control
unit changing ejection spatial intervals for ejecting the coating
solution onto the substrate.
3. The thin-film forming device according to claim 2, the control
unit changing the ejection spatial intervals by changing a speed of
the moving operation.
4. The thin-film forming device according to claim 2, the control
unit changing the ejection spatial intervals by changing time
intervals for the ejection during the moving operation.
5. The thin-film forming device according to claim 2, the droplet
ejection head being provided with a plurality of nozzles aligned in
at least one line, and the control unit optionally assigning some
nozzles among said plurality of nozzles to simultaneously eject the
coating solution for changing the ejection spatial intervals.
6. The thin-film forming device according to claim 1, the control
unit changing an ejection amount of the coating solution per
dot.
7. The thin-film forming device according to claim 1, the droplet
ejection head being provided with a plurality of nozzles aligned in
at least one line, and the control unit changing an ejection amount
ejected from each of said plurality of nozzles.
8. The thin-film forming device according to claim 1, the droplet
ejection head being provided with a plurality of nozzles aligned in
at least one line, and the control unit changing an angle formed by
an alignment direction of the nozzles and a moving direction by the
moving mechanism.
9. The thin-film forming device according to claim 1, the control
unit setting the coating conditions for each of coating steps which
are repeatedly performed on the substrate.
10. The thin-film forming device according to claim 1, the control
unit setting coating conditions for each of a plurality of regions
on the substrate.
11. The thin-film forming device according to claim 1, the coating
solution being a photoresist solution.
12. The device for manufacturing a liquid crystal display
comprising a pair of substrates, liquid crystal provided
therebetween, and an alignment film and an insulating film provided
on at least one of the substrates, the device comprising: a
thin-film forming device according to claim 1, the thin-film
forming device forming at least one of an alignment film and an
insulating film.
13. A device for manufacturing a thin-film structure having a
substrate and a thin film provided thereon, comprising a thin-film
forming device according to claim 1, the thin-film forming device
forming the thin film.
Description
[0001] This is a Division of application Ser. No. 10/368,607, filed
Feb. 20, 2003. The disclosure of the prior application is hereby
incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of Invention
[0003] The present invention relates to thin-film forming devices
for forming thin films by applying a coating solution onto a
substrate, thin-film forming methods, devices for manufacturing
liquid crystal displays, methods for manufacturing liquid crystal
displays, devices for manufacturing thin-film structures, methods
for manufacturing thin-film structures liquid crystal displays,
thin-film structures, and electronic apparatuses. In particular,
the present invention relates to a preferable device and method
capable of easily and accurately controlling the thickness of a
thin-film.
[0004] 2. Description of Related Art
[0005] Currently, a spin coating method used as one of techniques
for forming thin films is a method for forming a thin film by
dripping a coating solution onto a substrate and subsequently
applying the coating solution over the entire substrate using a
centrifugal force generated by rotating the substrate. In this
method, the film thickness is controlled by a rotation speed, a
rotation time, and viscosity of the coating solution. This spin
coating method has been widely used, for example, for the formation
of photoresist films or interlayer insulating films such as SOG
(spin on glass) in a semiconductor manufacturing process or the
like. The method has also been used in the formation of alignment
films in a process for manufacturing liquid crystal displays or the
like, and the formation of protection films in a process for
manufacturing optical discs or the like.
[0006] In this spin coating method, since most of the coating
solution thus supplied is scattered, a large quantity of the
coating solution must be supplied, and at the same time, the waste
thereof is large, resulting in disadvantageous increase in cost. In
addition, since the substrate is rotated, the coating solution
flows from the inside to the outside due to a centrifugal force,
and as a result, the thickness at the peripheral region tends to be
thick as compared to that at the inside region, resulting in
problem of uneven film thickness. As measures against the
disadvantages described above, in recent years, a coating method
using a so-called inkjet technique has been proposed.
[0007] For example, in Japanese Unexamined Patent Application
Publication Nos. 9-10657, 8-196983, and 9-192573, techniques have
been disclosed in which a rotation technique for rotating a
substrate is provided. In these techniques, a coating solution
ejected onto the substrate by a droplet ejection head is moved by
the rotation movement of the substrate, and the thickness of a thin
film made of the coating solution is controlled by changing the
rotation speed of the substrate, rotation time, and the like.
SUMMARY OF THE INVENTION
[0008] However, in the conventional techniques described above,
there have been the following problems. That is, according to the
coating technique using a rotation technique for rotating the
substrate, since rotation must be used, the thickness uniformity at
four comers of a rectangular substrate or end portions of a large
substrate, which are used for a liquid crystal display or the like,
becomes inferior to that at the central portion of the substrate.
In addition, since a device provided with rotation is necessary,
the device cost is increased. and in addition, an increased
installation area for the device must be disadvantageously secured.
In particular, in recent years, concomitant with increase in size
of substrates for liquid crystal displays, semiconductors, and the
like, the size of the conventional device has been inevitably
increased. Hence, a technique capable of decreasing the size of a
manufacturing device has been desired.
[0009] The present invention was made in consideration of the
problems described above, and an object of the present invention is
to provide a thin-film forming device which can easily control the
thickness of a thin film without using rotation, and which can be
manufactured at a lower cost and can be miniaturized. In addition,
the present invention provides a thin-film forming method, a device
for manufacturing a liquid crystal display, a method for
manufacturing a liquid crystal display, a device for manufacturing
a thin-film structure, a method for manufacturing a thin-film
structure, a liquid crystal display, a thin-film structure, and an
electronic apparatus.
[0010] In order to solve the problems described above, the present
invention employs the structure described below. That is, a
thin-film forming device of the present invention is a thin-film
forming device for forming a thin film by applying a coating
solution onto a substrate. The device can include an ejection
mechanism having a droplet ejection head for ejecting the coating
solution onto the substrate, a moving mechanism capable of
relatively moving the positions of the droplet ejection head and
the substrate, and a control unit for controlling at least one of
the ejection mechanism and the moving mechanism. In this device
described above, the control unit can change coating conditions of
the coating solution by controlling at least one of an ejection
operation by the ejection mechanism and a moving operation by the
moving mechanism so as to control the thickness of the thin
film.
[0011] In addition, a thin-film forming method of the present
invention is a method which applies a coating solution onto a
substrate for forming a thin film by using an ejection mechanism
having a droplet ejection bead for ejecting the coating solution
onto the substrate, a moving mechanism capable of relatively moving
the positions of the droplet ejection head and the substrate, and a
control unit for controlling at least one of the ejection mechanism
and the moving mechanism. The method described above can include
changing coating conditions of the coating solution by controlling
at least one of an ejection operation by the ejection mechanism and
a moving operation by the moving mechanism by using the control
unit so as to control the thickness of the thin film.
[0012] According to the thin-film forming device and the thin-film
forming method described above, in order to control the thickness
of the thin film, the coating conditions are changed by controlling
at least one of the ejection operation by the ejection mechanism
and the moving operation by the moving mechanism by using the
control unit. Hence, the thickness of the thin film can be easily
and highly accurately controlled without using rotation for the
substrate, and in addition, miniaturization and cost reduction of
the device can be achieved.
[0013] According to the thin-film forming device of the present
invention, the control unit can change ejection spatial intervals
for ejecting the coating solution onto the substrate.
[0014] In addition, according to the thin-film forming method of
the present invention, the control unit can change ejection spatial
intervals for ejecting the coating solution onto the substrate.
[0015] According to the thin-film forming device and the thin-film
forming method described above, since the control unit changes the
ejection spatial intervals for ejecting the coating solution onto
the substrate, when the ejection spatial intervals are decreased,
the coating amount per unit area on the surface of the substrate is
increased, thereby increasing the film thickness. In addition, when
the ejection spatial intervals are increased, the coating amount
per unit area on the surface of the substrate is decreased, thereby
decreasing the film thickness. Accordingly, the thickness of the
thin film can be easily and highly accurately controlled.
[0016] According to the thin-film forming device of the present
invention, the control unit can change the ejection spatial
intervals by changing a speed of the moving operation described
above. In addition, according to the thin-film forming method of
the present invention, the control unit can change the ejection
spatial intervals by changing a speed of the moving operation
described above.
[0017] According to the thin-film forming device and the thin-film
forming method described above, since the control unit changes the
ejection spatial intervals by changing the relative moving speed
between the droplet ejection head and the substrate, when the
moving speed is increased, the coating amount per unit moving
length is decreased, thereby decreasing the film thickness, and on
the other hand, when the moving speed is decreased, the coating
amount per unit moving length is increased, thereby increasing the
film thickness.
[0018] According to the thin-film forming device of the present
invention, the control unit can change the ejection spatial
intervals by changing ejection time intervals while the droplet
ejection head and the substrate are relatively moved. In addition,
according to the thin-film forming method of the present invention,
the control unit can change the ejection spatial intervals by
changing ejection time intervals while the droplet ejection head
and the substrate are relatively moved.
[0019] According to the thin-film forming device and the thin-film
forming method described above, since the control unit changes the
ejection spatial intervals by changing the time intervals for
ejection while the droplet ejection head and the substrate are
relatively moved, when the time intervals for ejection are
decreased, the coating amount per unit moving length is increased,
thereby increasing the film thickness, and on the other hand, when
the time intervals for ejection are increased, the coating amount
per unit moving length is decreased, thereby decreasing the film
thickness.
[0020] According to the thin-film forming device of the present
invention, the droplet ejection head can be provided with a
plurality of nozzles aligned in at least one line, and the control
unit optionally assigns some nozzles among said plurality of
nozzles to simultaneously eject the coating solution for changing
the ejection spatial intervals.
[0021] In addition, according to the thin-film forming method of
the present invention the droplet ejection head can be provided
with a plurality of nozzles aligned in at least one line, and the
control unit optionally assigns some nozzles among said plurality
of nozzles to simultaneously eject the coating solution for
changing the ejection spatial intervals.
[0022] According to the thin-film forming device and the thin-film
forming method described above, since the control unit changes the
ejection spatial intervals by optionally assigning some nozzles
among said plurality of nozzles to simultaneously eject the coating
solution, when the number of the nozzles performing the
simultaneous ejection are larger and the distances therebetween are
smaller, the coating amount per unit area becomes larger, thereby
increasing the film thickness, and on the other hand, when the
number of the nozzles performing the simultaneous ejection are
smaller and the distances therebetween are larger, the coating
amount per unit area becomes smaller, thereby decreasing the film
thickness.
[0023] According to the thin-film forming device of the present
invention, the control unit can change the ejection amount of the
coating solution per dot. In addition, according to the thin-film
forming method of the present invention, the control unit can
change the ejection amount of the coating solution per dot.
[0024] According to the thin-film forming device and the thin-film
forming method described above, since the control unit changes the
ejection amount of the coating solution per dot, and the coating
amount per unit area is changed in proportion to the ejection
amount, the film thickness can be increased when the ejection
amount is increased and can be decreased when it is decreased.
[0025] According to the thin-film forming device of the present
invention, the droplet ejection head can be provided with a
plurality of nozzles aligned in at least one line, and the control
unit changes the ejection amount ejected from each of said
plurality of nozzles.
[0026] In addition, according to the thin-film forming method of
the present invention, the droplet ejection head can be provided
with a plurality of nozzles aligned in at least one line, and the
control unit changes the ejection amount ejected from each of said
plurality of nozzles.
[0027] According to the thin-film forming device and the thin-film
forming method described above, since the control unit changes the
ejection amount ejected from each of said plurality of nozzles, the
coating amount can be optionally changed in accordance with the
position of each nozzle and the ejection amount therefrom, and
hence various film thickness control can be performed. For example,
when the ejection amount from every other nozzle is decreased, the
coating amount is decreased on the whole as compared to that
obtained in the case in which all the nozzles eject the same
amount, thereby decreasing the film thickness.
[0028] According to the thin-film forming device of the present
invention, the droplet ejection head can be provided with a
plurality of nozzles aligned in at least one line, and the control
unit changes an angle formed by the alignment direction of the
nozzles and the moving direction by the moving mechanism.
[0029] In addition, according to the thin-film forming method of
the present invention, the droplet ejection head can be provided
with a plurality of nozzles aligned in at least one line, and the
control unit changes an angle formed by the alignment direction of
the nozzles and the moving direction by the moving mechanism.
[0030] According to the thin-film forming device and the thin-film
forming method described above, since the control unit changes the
angle formed by the alignment direction of the nozzles and the
moving direction by the moving mechanism, for example, when the
droplet ejection head is inclined with respect to the moving
direction, an apparent nozzle pitch is decreased, and hence the
coating amount per unit moving length is increased, thereby
increasing the film thickness.
[0031] According to the thin-film forming device of the present
invention, when the coating is repeatedly performed on the
substrate, the control unit sets the coating conditions for each
coating. In addition, according to the thin-film forming method of
the present invention, when the coating is repeatedly performed on
the substrate, the control unit sets the coating conditions for
each coating.
[0032] According to the thin-film forming device and the thin-film
forming method described above, when the coating is repeatedly
performed on the substrate, since the control unit sets the coating
conditions for each coating, for example, the coating conditions
performed for first coating can be changed for subsequent coating
in consideration of characteristics such as a drying characteristic
(volatility) of the coating solution, and hence the coating can be
repeatedly performed in consideration of the state of the coating
solution L.
[0033] According to the thin-film forming device of the present
invention, the control unit sets the coating conditions for each of
a plurality of regions on the substrate. In addition, according to
the thin-film forming method of the present invention, the control
unit sets the coating conditions for each of a plurality of regions
on the substrate.
[0034] According to the thin-film forming device and the thin-film
forming method described above, since the control unit sets the
coating conditions for each of said plurality of regions on the
substrate, the film-thickness can be optionally set in each region,
and in addition, by finely adjusting the coating amount in each
region in consideration of characteristics such as a drying
characteristic (volatility) of the coating solution in said each
region, more highly accurate uniformity of the film thickness can
be obtained. For example, when the thickness at the peripheral
portion of the substrate tends to be large as compared to that at
the central portion thereof, the coating amount can be controlled
beforehand so that the thickness at the peripheral portion is
smaller than that of the central portion.
[0035] According to the thin-film forming device of the present
invention, the coating solution can be a photoresist solution. In
addition, according to the thin-film forming method of the present
invention, the coating solution can be a photoresist solution.
[0036] According to the thin-film forming device and the thin-film
forming method described above, since the coating solution is a
photoresist solution, the thickness of a photoresist film can be
controlled with high accuracy in a photolithographic step used in a
manufacturing process for a liquid crystal display, a semiconductor
device, or the like, thereby obtaining superior exposure
accuracy.
[0037] A device for manufacturing a liquid crystal display,
according to the present invention, can be a device for
manufacturing a liquid crystal display including a pair of
substrates, liquid crystal provided therebetween, and an alignment
film and an insulating film provided on at least one of the
substrates. The device described above can include the thin-film
forming device of the present invention described above, wherein
the thin-film forming device forms at least one of the alignment
film and the insulating film.
[0038] A method for manufacturing a liquid crystal display,
according to the present invention, is a method for manufacturing a
liquid crystal display including a pair of substrates, liquid
crystal provided therebetween, and an alignment film and an
insulating film provided on at least one of the substrates. The
method described above can include forming at least one of the
alignment film and the insulating film by the thin-film forming
method of the present invention described above.
[0039] In addition, a liquid crystal display of the present
invention is a liquid crystal display including a pair of
substrates, liquid crystal provided therebetween, and an alignment
film and an insulating film provided on at least one of the
substrates, wherein at least one of the alignment film and the
insulating film is formed by the thin-film forming method of the
present invention described above.
[0040] According to the liquid crystal display and the device and
method for manufacturing the same, since at least one of the
alignment film and the insulating film is formed by the thin-film
forming device or the thin-film forming method according to the
present invention described above, an alignment film and an
insulating film each having superior thickness uniformity over the
entire substrate can be easily obtained.
[0041] A device for manufacturing a thin-film structure, according
to the present invention, is a device for manufacturing a thin-film
structure having a substrate and a thin film formed thereon and can
include the thin-film forming device of the present invention
described above, wherein the thin-film forming device described
above forms the thin film.
[0042] A method for manufacturing a thin-film structure, according
to the present invention, is a method for manufacturing a thin-film
structure having a substrate and a thin film formed thereon and can
include forming the thin film by the thin-film forming method of
the present invention described above.
[0043] In addition, a thin-film structure of the present invention
is a thin-film structure having a substrate and a thin film formed
thereon, wherein the thin film is formed by the thin-film forming
method of the present invention described above.
[0044] According to the thin-film structure and the device and
method for manufacturing the same, since the thin film is formed by
the thin-film forming device or the thin-film forming method
according to the present invention described above, even in the
thin-film structure such as an optical disc, a thin film such as a
protection film having superior thickness uniformity over the
entire substrate can be easily obtained.
[0045] In addition, an electronic apparatus of the present
invention can include the liquid crystal display of the present
invention described above. Since this electronic apparatus
comprises the liquid crystal display of the present invention, an
electronic apparatus having a high quality display portion can be
realized by the presence of the alignment film or the insulating
film having superior thickness uniformity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] The invention will be described with reference to the
accompanying drawings, wherein like numerals reference like
elements, and wherein:
[0047] FIG. 1 is a perspective view showing the schematic structure
of a thin-film forming device of a first embodiment according to
the present invention;
[0048] FIG. 2 is a perspective view showing the structure of a
droplet ejection head of the thin-film forming device of the first
embodiment according to the present invention;
[0049] FIG. 3 is a cross-sectional view showing the structure of
the droplet ejection head of the thin-film forming device of the
first embodiment according to the present invention;
[0050] FIG. 4 is a plan view showing a plurality of adjoining
pixels on a TFT array substrate forming a liquid crystal display of
the first embodiment according to the present invention;
[0051] FIG. 5 is a cross-sectional view taken along the line A-A'
in FIG. 4;
[0052] FIG. 6 is a view illustrating nozzle pitches when an angle
of the droplet ejection head of the thin-film forming device of the
first embodiment according to the present invention is changed;
[0053] FIG. 7 is a perspective view showing the schematic structure
of a thin-film forming device of a second embodiment according to
the present invention;
[0054] FIG. 8 is a perspective view showing an example of an
electronic apparatus provided with a liquid crystal display of one
embodiment according to the present invention;
[0055] FIG. 9 is a perspective view showing another example of an
electronic apparatus provided with a liquid crystal display of one
embodiment according to the present invention; and
[0056] FIG. 10 is a perspective view showing still another example
of an electronic apparatus provided with a liquid crystal display
of one embodiment according to the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0057] Hereinafter, a first embodiment of the present invention
will be described with reference to FIGS. 1 to 4. FIG. 1 is a view
showing a thin-film forming device for forming, for example, a
polyimide-based alignment film (thin film) by applying a coating
solution L onto a substrate SUB provided with pixel electrodes used
for a liquid crystal display device (liquid crystal display). This
thin-film forming device comprises an ejection mechanism 2 having a
droplet ejection head 1 for ejecting the coating solution L onto
the substrate SUB, a moving mechanism 3 capable of relatively
moving the positions of the droplet ejection head 1 and the
substrate SUB, and a control C for controlling the ejection
mechanism 2 and the moving mechanism 3.
[0058] The moving mechanism 3 can include a head supporter 5 for
supporting the droplet ejecting head 1 at a position over the
substrate SUB provided on a substrate stage 4 so that the head 1
faces downward and for moving the droplet ejection head 1 to an
optional position with respect to the substrate SUB, and a stage
driver 6 for moving the substrate SUB together with the substrate
stage 4 with respect to the droplet ejecting head 1 which is
provided at the upper side.
[0059] The head supporter 5 can include a mechanism, such as a
linear motor, capable of moving the droplet ejection head 1 in the
horizontal direction (X axis) and the vertical direction (Z axis)
at an optional moving speed and positioning the droplet ejection
head 1, and a mechanism such as a stepping motor capable of setting
the droplet ejecting head 1 at an optional angle with respect to
the substrate SUB provided at the lower side by rotating the
droplet ejecting head 1 about a vertical central axis.
[0060] The stage driver 6 can include a .theta. axis stage 7
capable of setting the substrate stage 4 at an optional angle with
respect to the droplet ejection head 1 by rotation about the
vertical central axis, and a Y axis stage 8 capable of moving the
substrate stage 4 in the horizontal direction (Y axis) orthogonally
intersecting the horizontal moving direction of the droplet
ejection head 1 and of positioning the substrate stage 4. In
addition, the .theta. axis stage 7 is formed of a stepping motor or
the like, and the Y axis stage 8 is formed of a linear motor or the
like.
[0061] The ejection mechanism 2 can have a tank 10 connected to the
droplet ejection head 1 through a tube 9, and the tank 10 stores
the coating solution L to be supplied to the droplet ejection head
1. In other words, coating is performed by supplying the coating
solution stored in the tank 10 to the droplet ejection head 1
through the tube 9.
[0062] The droplet ejection head 1 is to eject a liquid material by
a pressure wave generated by compressing a room in which the
coating solution is contained using a piezoelectric element or the
like and has a plurality of nozzles (nozzle holes) aligned in at
least one line. One example of the structure of this droplet
ejection head 1 will be described. As shown in FIGS. 2 and 3, the
droplet ejection head 1 is composed, for example, of a nozzle plate
31 made of a stainless steel and a vibration plate 32 bonded
thereto with a partition member (reserver plate) 33 provided
therebetween. Between the nozzle plate 31 and the vibration plate
32, a plurality of spaces 34 and a liquid pool 35 are formed by the
reserver plate 33. These spaces 34 are communicated with the liquid
pool 35 through supply inlets 36. In addition, the nozzle plate 31
is provided with nozzles 37 for ejecting the coating solution L
from the respective spaces 15. In the vibration plate 32, an
opening 38 is formed for supplying the coating solution L into the
liquid pool 35.
[0063] In addition, as shown in FIG. 2, a piezoelectric element 39
is bonded to the opposite surface of the vibration plate 32 from
that facing the spaces 34. The piezoelectric element 39 is located
between a pair of electrodes 40 and is warped so as to project
outside when electricity is applied thereto, and the vibration
plate 32 bonded to the piezoelectric element 39 is simultaneously
warped outside therewith. As a result, the volume of the space 34
is increased thereby. Consequently, the coating solution L in an
amount corresponding to the volume increased in the space 34 is
supplied thereto from the liquid pool 35 through the supply inlet
36.
[0064] Next, when the application of the electricity to the
piezoelectric element 39 is stopped, the piezoelectric element 39
and the vibration plate 32 return to the respective original
shapes. Hence, the volume of the space 34 also returns to the
original one, the pressure of the coating solution L inside the
space 34 is increased, thereby ejecting a droplet 27 of the coating
solution L to a substrate from the nozzle 37.
[0065] As a type of droplet ejection head 1, in addition to a
piezoelectric jet type using the piezoelectric element described
above, for example, a type provided with an electrothermal
converter as an energy generation element may also be used.
[0066] The control unit C can be composed, for example, of a
computer, which contains a CPU such as a microprocessor for
controlling the entire device and has input/output functions of
various signals, and is electrically connected to the ejection
mechanism 2 and the moving mechanism 3 so as to control at least
one of an ejection operation by the ejection mechanism 2 and a
moving operation by the moving mechanism 3. Accordingly, the
control unit C has functions of controlling the film thickness of
an alignment film by changing the coating conditions of the coating
solution L.
[0067] In other words, as the functions of controlling the film
thickness, the control unit C has a control function of changing
the ejection spatial intervals for the coating solution L onto the
substrate SUB, a control function of changing the ejection amount
of the coating solution L per dot, a control function of changing
an angle .theta. formed by the alignment direction of the nozzles
37 and the moving direction by the moving mechanism 3, a control
function of setting the coating conditions for each coating when
the coating is repeatedly performed on the substrate SUB, and a
control function of setting the coating conditions for each of a
plurality of regions of the substrate SUB.
[0068] Furthermore, as the control function of changing the
ejection spatial intervals described above, the control unit C has
a control function of changing the ejection spatial intervals by
changing a relative moving speed between the substrate SUB and the
droplet ejection head 1, a control function of changing the
ejection spatial intervals by changing ejection time intervals
while moving, and a control function of changing the ejection
spatial intervals by optionally assigning some nozzles among the
plurality of the nozzles to simultaneously eject the coating
solution L.
[0069] Next, a liquid crystal display having an alignment film
formed by the thin-film forming device of this embodiment and a
method for forming the alignment film will be described with
reference to FIGS. 4 to 6.
[0070] FIG. 4 is a view showing an example of the structure of a
TFT array substrate, which is one of substrates of a TFT (thin-film
transistor) type liquid crystal display having an alignment film
formed by the thin-film forming device described above, and FIG. 5
is a view showing a cross-sectional structure of a liquid crystal
display having this TFT array substrate. Among the entire steps of
manufacturing this liquid crystal display, steps other than those
to which the present invention is applied are equivalent to known
steps, and hence descriptions thereof are omitted.
[0071] As shown in FIG. 4, above the TFT array substrate, a
plurality of transparent pixel electrodes 101 are provided in a
matrix, and data lines 103, scanning lines 104, and capacitance
lines 106 are provided along the respective longitudinal and
lateral boundaries of the pixel electrodes 101. The data line 103
is electrically connected to a source region described later of a
semiconductor layer 109 made of a polysilicon film through a
contact hole 108, and the pixel electrode 101 is electrically
connected to a drain region, which will be described later, of the
semiconductor layer 109 through a contact hole 110. In addition,
the scanning line 104 is disposed to oppose a channel 111 region of
the semiconductor layer 109.
[0072] As shown in FIG. 5, the liquid crystal display has a pair of
transparent substrates, one of the transparent substrates is a TFT
array substrate 107, and the other transparent substrate is a
counter substrate 112 facing thereto. The pixel electrodes 101,
each made of a transparent conductive thin film, are provided for
the TFT array substrate 107, and at a position adjacent to each
pixel electrode 101 above the TFT array substrate 107, a TFT 102
performing switching control of each pixel electrode 101 is
provided. The TFT 102 has the LDD (lightly doped drain) structure
and can include the scanning line 104, the channel region 111 of
the semiconductor layer 109 in which a channel is formed by an
electric field applied by the scanning line 104, an insulating thin
film 113 insulating between the scanning line 104 and the
semiconductor layer 109, the data line 103, a lightly doped source
region 114 and a lightly doped drain region 115 of the
semiconductor layer 109, and a heavily doped source region 116 and
a heavily doped drain region 117 of the semiconductor layer
109.
[0073] In addition, on the scanning line 104, the insulating thin
film 113, and the TFT array substrate 107, a first interlayer
insulating film 118 is formed in which the contact hole 108
extending to the heavily doped source region 116 and the contact
hole 110 extending to the heavily doped drain region 117 are
formed. In other words, the data line 103 can be electrically
connected to the heavily doped source region 116 through the
contact hole 108 formed in the first interlayer insulating film
118. In addition, on the data line 103 and the first interlayer
insulating film 118, a second interlayer insulating film 119 is
formed in which the contact hole 110 extending to the highly doped
drain region 117 is formed. That is, the highly doped drain region
117 is electrically connected to the pixel electrode 101 through
the contact hole 110 which penetrates the first interlayer
insulating film 118 and the second interlayer insulating film
119.
[0074] In addition, the insulating thin film 113 used as a gate
insulating film is extended from a position facing the gate
electrode, which is made of a part of the scanning line 104, to
form a dielectric film, the semiconductor layer 109 is extended to
form a first storage capacitance electrode 120, and a part of the
capacitance line 106 facing thereto is used as a second storage
capacitance electrode, thereby forming a storage capacitance
105.
[0075] In addition, on the counter substrate 112, a first shading
film 122 functioning as a black matrix is formed in regions facing
to those in which the data lines 103, the scanning lines 104, and
the TFTs 102 are formed above the TFT array substrate 107, i.e.,
the non-display regions in each pixel. Furthermore, on the entire
surface including the counter substrate 112 and the first shading
film 122, a counter electrode 123 made of a transparent conductive
thin film is provided.
[0076] On the second interlayer insulating film 119 and the pixel
electrode 101, an alignment film 121 formed by the thin-film
forming device described above is provided, and on the counter
electrode 123 provided at the counter substrate 112 side, an
alignment film 124 formed by the thin-film forming device described
above is provided. These TFT array substrate 107 and the counter
substrate 112 are disposed so that the pixel electrodes 101 and the
counter electrode 123 oppose each other, and liquid crystal 125 is
enclosed in a space surrounded by these substrates 107 and 112 and
a sealing material (not shown).
[0077] Next, a method for forming the alignment film 121 described
above will be described. After the pixel electrodes 101 are formed,
a coating solution L (for example, JALS657 manufactured by JSR
Corp.) for forming a polyimide-based alignment film 121 is applied
onto the entire surface of the TFT array substrate 107 by the
thin-film forming device described above, thereby forming a thin
film having a uniform thickness of approximately 50 nm or the like.
Subsequently, rubbing treatment is performed in a predetermined
direction, thereby forming the alignment film 121. In addition, in
a method for forming the alignment film 124, the coating solution L
is applied onto the counter electrode 123 at the counter substrate
112 side by the thin-film forming device as in the case of the
alignment film 121 to form a thin film, and subsequently, rubbing
treatment is performed in a predetermined direction, thereby
forming the alignment film 124. As described above, the TFT array
substrate 107 and the counter substrate 112, prior to the formation
of the alignment films 121 and 124, each correspond to the
substrate SUB described above.
[0078] A method for coating the coating solution L for forming the
alignment films 121 and 124 will be further described in detail. In
order to control the thicknesses of the alignment films 121 and
124, when the coating solution L is applied onto the substrate SUB,
the coating conditions can be changed by performing at least one
operation control of the following controls using the control unit
C of the thin-film forming device. In the following controls, the
control unit C changes the coating conditions based on the actual
thickness data in accordance with the coating conditions, which are
obtained beforehand, so as to obtain a predetermined film
thickness.
[0079] Film thickness control by ejection spatial intervals is
performed by the control unit C is to control the film thicknesses
of the alignment films 121 and 124 by changing the ejection spatial
intervals of the coating solution L applied onto the substrate SUB
as the coating conditions. That is, when the ejection spatial
intervals are decreased, the coating amount per unit area on the
surface of the substrate SUB is increased, thereby forming a thick
film, and on the other hand, when the ejection spatial intervals
are increased, the coating amount per unit area is decreased,
thereby forming a thin film.
[0080] In more particular, by changing the relative moving speed
between the droplet ejection head 1 and the substrate SUB, the
ejection spatial intervals are changed. That is, when the moving
speed is increased, the coating amount per unit moving length is
decreased, thereby decreasing the film thickness, and on the other
hand, when the moving speed is decreased, the coating amount per
unit moving length is increased; thereby increasing the film
thickness. For example, when coating is performed by moving the
droplet ejection head 1 using the moving mechanism 3 in the X axis
direction with respect to the substrate SUB, the film thickness can
be decreased by increasing the moving speed in the X axis direction
while ejection time intervals are maintained constant.
[0081] In addition, the ejection spatial intervals may be changed
by changing ejection time intervals while the droplet ejection head
1 and the substrate SUB are relatively moved. That is, when the
ejection time intervals are decreased, the coating amount per unit
moving length is increased, thereby increasing the film thickness,
and on the other hand, when the ejection time intervals are
increased, the coating amount per unit moving length is decreased,
thereby decreasing the film thickness. For example, when the
ejection time intervals for ejecting the coating solution L by the
ejection mechanism 2 are decreased while the moving speed of the
droplet ejection head 1 by the moving mechanism 3 is maintained
constant, the film thickness can be increased.
[0082] Furthermore, the ejection spatial intervals may be changed
by optionally assigning some nozzles 37 among said plurality of
nozzles 37 to simultaneously eject the coating solution L. That is,
when the number of the nozzles 37 performing simultaneous ejection
is larger, and the distances between the nozzles 37 described above
are smaller, the coating amount per unit area becomes larger,
thereby increasing the film thickness. On the other hand, when the
number of the nozzles 37 performing simultaneous ejection is
smaller, and the distances between the nozzles 37 described above
are larger, the coating amount per unit area becomes smaller,
thereby decreasing the film thickness. That is, for example, when
every other nozzle 37 among those which are aligned at regular
intervals is assigned to eject the coating solution L, the ejection
spatial intervals become two times that obtained in the case in
which all the nozzles 37 eject the coating solution L, and hence
the film thickness can be decreased to one half of that obtained in
the case described above.
[0083] In this embodiment, for example, the ejection spatial
intervals are controlled in the range of from 1 to 100 .mu.m.
[0084] Film thickness control by ejection amount is performed by
the control unit C is to control the film thickness by changing the
ejection amount of the coating solution L per dot as the coating
conditions. That is, since the coating amount per unit area is
changed in proportion to the ejection amount, the film thickness
can be increased when the ejection amount is increased, and on the
other hand, when the ejection amount is decreased, the film
thickness can be decreased. For example, when a drive voltage
applied to the piezoelectric element 39 of the droplet ejection
head 1 is changed in the range of from 0.1 to 34.9 V by the
ejection mechanism 2, and an appropriate drive waveform is
selected, the ejection amount per dot can be changed from
approximately 2 to 20 picoliters, and hence the film thickness can
be controlled with high accuracy.
[0085] In addition, by changing the ejection amount ejected from
each nozzle 37 using the control unit C, the film thickness may be
controlled. That is, the coating amount can be optionally changed
by the ejection mechanism 2 in accordance with the position of each
nozzle 37 and the ejection amount therefrom, and hence various
control of the film thickness can be performed. For example, when
each other nozzle 37 among those which are aligned at regular
intervals is assigned to eject a decreased amount per dot, compared
to the case in which all the nozzles 37 eject the same amount, the
coating amount is decreased, and hence the film thickness can be
decreased.
[0086] Film thickness control by angle of nozzle alignment
direction is performed by the control unit C is to control the film
thickness by changing an angle formed by the alignment direction of
the nozzles and the moving direction by the moving mechanism. For
example, when the angle .theta. formed by the alignment direction
of the nozzles 37 and the moving direction (for example, the X axis
direction) is decreased by rotating the droplet ejection head 1
using the head supporter 5 as shown in FIG. 6, an apparent nozzle
pitch B is decreased as compared to an actual nozzle pitch A, and
hence the coating amount per unit moving length can be increased,
thereby increasing the film thickness.
[0087] In film thickness control by repeated coating, when coating
is repeatedly performed on the substrate SUB, the coating
conditions for each coating is selected from at least one of the
film thickness controls described above by the control unit C. For
example, the coating conditions performed for first coating can be
changed for subsequent coating in consideration of characteristics
such as a drying characteristic (volatility) of the coating
solution L, and hence coating can be repeatedly performed under
appropriate conditions in consideration of the state of the coating
solution L.
[0088] Film Thickness control by regions is performed by the
control unit C, since coating is performed for each of a plurality
of regions on the surface of the substrate SUB under the coating
conditions using at least one of the film thickness controls
described above, the film thickness can be optionally set in each
region, and in addition, by finely adjusting the coating amount for
each region in consideration of characteristics such as a drying
characteristic (volatility) of the coating solution L in said each
region, more highly accurate uniformity of the film thickness can
be obtained. For example, due to the volatility of the coating
solution L, when the film thickness of at the peripheral portion of
the substrate SUB tends to be large as compared to that at the
central portion thereof, the film is divided into two regions,
i.e., the peripheral portion and the central portion of the
substrate SUB, and the coating amount is controlled by the coating
conditions so that the thickness at the peripheral portion is
smaller than that of the central portion beforehand, thereby
obtaining superior thickness uniformity on the whole.
[0089] Next, a second embodiment of the present invention will be
described with reference to FIG. 7.
[0090] The points of the second embodiment differ from those of the
first embodiment are as follows. The moving mechanism 3 of the
thin-film forming device of the first embodiment is provided with
the head supporter 5 capable of moving the droplet ejection head 1
in the X axis direction and the stage driver 6 having the Y axis
stage 8 capable of moving the substrate stage 4 in the Y axis
direction, and in a thin-film forming device of the second
embodiment, as shown in FIG. 7, a moving mechanism 23 is provided
with a head supporter 25 having no moving function of moving the
droplet ejection head 1 in the X axis direction and a stage driver
26 having an X axis stage 27 capable of moving the substrate stage
4 in both the X axis and the Y axis directions and capable of
positioning it.
[0091] That is, in this embodiment, the movement in the horizontal
plane (X axis direction and Y plane direction) of the droplet
ejection head 1 and the substrate SUB on the substrate stage 4 for
relative movement and positioning is controlled by the stage driver
26 side. Accordingly, in the film thickness control performed by
the control unit C described above, the control of moving operation
in the horizontal plane by the moving mechanism 23 is primarily
performed by the X axis stage 27 and the Y axis stage 8 of the
stage driver 26.
[0092] Hereinafter, particular examples of electronic apparatuses
will be described each provided with the liquid crystal display of
the present invention.
[0093] FIG. 8 is a perspective view showing an example of a mobile
phone. In FIG. 8, reference numeral 1000 indicates a mobile phone
body, and reference numeral 1001 indicates a liquid crystal display
portion using the liquid crystal display described above.
[0094] FIG. 9 is a perspective view showing an example of a
wristwatch-shaped electronic apparatus. In FIG. 9, reference
numeral 1100 indicates a watch body, and reference numeral 1101
indicates a liquid crystal display portion using the liquid crystal
display described above.
[0095] FIG. 10 is a perspective view showing an example of a mobile
information processing apparatus such as a word processor or a
personal computer. In FIG. 10, reference numeral 1200 indicates an
information processing apparatus, reference numeral 1202 indicates
an input portion such as a keyboard, reference numeral 1204
indicates an information processing body, and reference numeral
1206 indicates a liquid crystal display portion using the liquid
crystal display described above.
[0096] The electronic apparatuses shown in FIGS. 8 to 10 are each
provided with the liquid crystal display portion using the liquid
crystal display described above, and hence an electronic apparatus
having superior display quality can be obtained because of the use
of the alignment film or insulating film having superior thickness
uniformity.
[0097] In addition, it should be understood that the present
invention is not limited to the embodiments described above and may
be variously modified without departing from the spirit and the
scope of the present invention.
[0098] For example, in the embodiments described above, the
thin-film forming device can be used for forming the alignment film
in the process for manufacturing the liquid crystal display;
however, the thin-film forming device may be used for forming
another thin-film. For example, the thin-film forming technique of
the present invention may be used for forming the second interlayer
insulating film 119 in the process for manufacturing the liquid
crystal display described above. In the case described above, an
interlayer insulating film having superior thickness uniformity
over the entire substrate can be obtained. As the coating solution,
a liquid material for forming an organic film, SOG, or the like may
be used for forming the interlayer insulating film.
[0099] In addition, the present invention may be applied to the
formation of a protection film of an organic EL panel. That is, an
insulating protection film formed on electrodes of the organic EL
panel may be formed by the thin-film forming method and the
thin-film forming device of the present invention. The steps of
manufacturing the entirety of this organic EL panel other than the
protection-film forming step to which the present invention is
applied are equivalent to known manufacturing steps.
[0100] In addition, as the coating solution, various liquid
thin-film forming materials may be used, and by using a photoresist
solution, the thin-film forming technique of the present invention
may be applied to the formation of a resist film in a
photolithographic step performed in a manufacturing process for a
liquid crystal display, a semiconductor device, or the like. In the
case described above, the thickness of the resist film can be
controlled with high accuracy, and hence superior exposure accuracy
can be obtained.
[0101] In addition, in the embodiments described above, the
thin-film forming technique of the present invention can be used as
a technique for forming the liquid crystal display having a
multilayer structure in which a plurality of thin films including
an alignment film is provided on the substrate. However, it should
be understood that the thin-film forming technique of the present
invention may be applied to the formation of another thin-film
structure. For example, the present invention may be applied to a
technique for forming a thin-film structure such as an optical disc
in which a protection film is provided on the surface thereof. In
the case described above, a protection film can be obtained having
superior thickness uniformity over the entire optical disc
substrate. In particular, when a UV curable resin solution is used
as the coating solution, a protection film can be formed which
prevents degradation of a metal-deposition film of an optical
disc.
[0102] As has thus been described, according to the thin-film
forming device and the thin-film forming method of the present
invention, at least one of the ejection operation and the moving
operation performed by the ejection mechanism and the moving
mechanism, respectively, is controlled by the control unit so as to
change the coating conditions, thereby controlling the thickness of
the thin film. Accordingly, the thickness control of the thin film
can be easily and highly accurately performed without using
rotation means for rotating the substrate, and in addition, the
device can be miniaturized and can be manufactured at lower
cost.
[0103] In addition, in the device for manufacturing the liquid
crystal display, the method for manufacturing the liquid crystal
display, the liquid crystal display, and the electronic apparatus
of the present invention, at least one of the alignment film and
the insulating film is formed by the thin-film forming device and
the thin-film forming method of the present invention, and hence an
alignment film and insulating film having superior thickness
uniformity over the entire substrate can be easily obtained.
[0104] Furthermore, in the device for manufacturing the thin-film
structure, the method for manufacturing the thin-film structure,
and the thin-film structure of the present invention, the thin-film
is formed by the thin-film forming device or the thin-film forming
method of the present invention described above, for example, even
in the thin-film structure such as an optical disc, a thin film
such as a protection film having superior thickness uniformity over
the entire optical disc substrate can be easily obtained.
* * * * *