Title: Method for manufacturing liquid crystal panel, liquid crystal panel and manufacturing system of the same
Abstract: A substrate is plotted into a plurality of blocks, and each block is plotted into one or a plurality of device-forming regions. By using a first manufacturing line, a conductive film, an insulating film and a semiconductor film which constitute TFT are formed in the device-forming region. Then, primary cutting is performed to cut the substrate into the respective blocks and form a plurality of sub-TFT substrates. Then, by using a second manufacturing line, processing is performed for each sub-TFT substrate in accordance with specifications of a liquid crystal panel to be manufactured. Then, secondary cutting is performed to cut the sub-TFT substrate into respective device-forming regions.
Patent Number: 6,891,576 Issued on 05/10/2005 to Zhang
| Inventors:
|
Zhang; Hongyung (Kanagawa, JP)
|
| Assignee:
|
Fujitsu Display Technologies Corporation (Kawasaki, JP)
|
| Appl. No.:
|
385050 |
| Filed:
|
March 10, 2003 |
Foreign Application Priority Data
| Mar 17, 1999[JP] | 11-072272 |
| Current U.S. Class: |
349/1; 349/187 |
| Intern'l Class: |
G02F 001/13.68 |
| Field of Search: |
349/1,42,43,73,158,187
445/24,25,60,65,66
438/30
118/35,40,719
414/935,937,939
|
References Cited [Referenced By]
U.S. Patent Documents
| 5464490 | Nov., 1995 | Sato et al.
| |
| 5831694 | Nov., 1998 | Onisawa et al.
| |
| 6144082 | Nov., 2000 | Yamazaki et al.
| |
| 6195149 | Feb., 2001 | Kodera et al.
| |
| 6524977 | Feb., 2003 | Yamazaki et al.
| |
| Foreign Patent Documents |
| 9-325328 | Dec., 1997 | JP.
| |
Primary Examiner: Ton; Toan
Assistant Examiner: Duong; Tai
Attorney, Agent or Firm: Greer, Burns & Crain, Ltd.
Parent Case Text
This is a divisional of application Ser. No. 09/490,502, filed Jan. 25, 2000.
Claims
1. A manufacturing system of a liquid crystal panel comprising:
a first manufacturing line including master plotting equipment for plotting a
master glass substrate into a plurality of blocks, block plotting equipment for
plotting each block into one or more device-forming regions, thin film transistor
(TFT) equipment for forming a TFT in at least one of the device-forming regions,
film-forming equipment for forming a semiconductor film serving as an active layer
of the TFT, and cutting equipment for performing a primary cutting process in which
the master glass substrate is cut in line with each of the blocks to be made into
a sub-TFT substrate; and
a second manufacturing line including manufacturing equipment for executing processing
of the sub-TFT substrate after the primary cutting process in accordance with a
device to be manufactured, and pixel electrode film-forming equipment for forming
a pixel electrode above the sub-TFT substrate.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal panel manufacturing method
for manufacturing a plurality of liquid crystal panels by using one master glass
substrate, a liquid crystal panel manufactured by the manufacturing method and
a manufacturing system of the same.
2. Description of the Related Art
A display using a liquid crystal panel of an active matrix system prevents crosstalk
by providing a switch for each pixel (picture element), the switch being turned
OFF at the time of unselection to cut off a signal. Compared with a display using
a liquid crystal panel of a simple matrix system, this display shows a better display
characteristic. Especially, a liquid crystal display using TFT (Thin Film Transistor)
as a switch shows a display characteristic as excellent as that of CRT (Cathode-Ray
Tube), because of high driving performance of TFT.
Generally, the liquid crystal panel has a structure where a liquid crystal
is enclosed between two transparent substrates. A counter electrode, a color filter,
an orientation film, and so on, are formed on one of two opposing surfaces of the
transparent substrates. TFT, a pixel electrode, an orientation film, and so on,
are formed on the other surface. Also, polarizing plates are stuck to surfaces
opposite the opposing surfaces of the respective transparent substrates. These
two polarizing plates are arranged, for example, so that polarization axes of the
polarizing plates can be orthogonal to each other. In this arrangement, a light
is transmitted in a state of no electric field application. In a state of electric
field application, a light shielding mode, i.e., a normally white mode, is set.
Conversely, when the polarization axes of the two polarizing plates are in parallel
with each other, a normally black mode is set. Hereinafter, a transparent substrate
having TFT and a pixel electrode, or a transparent substrate having TFT and a pixel
electrode formed therefrom, is referred to as TFT substrate. A transparent substrate
having a counter electrode and a color filter is referred to as CF substrate.
Recent years have seen a gradual increase in size of the liquid crystal panel
of an active matrix type, which is used in a notebook personal computer (referred
to as "PC", hereinafter), and a desktop PC, a work station or the like.
In manufacturing of a liquid crystal panel, generally, a large substrate called
master glass is used. The master glass substrate is plotted into a plurality of
liquid crystal panel forming regions. TFT, a pixel electrode, and so on, are formed
in each region, and then a spacer is dispersed on the master glass substrate (TFT
substrate). The master glass substrate and a CF substrate are joined with the spacer
between. Subsequently, the master glass substrate is divided to form individual
liquid crystal panels. With enlargement of the liquid crystal panel, a size of
the master glass substrate has a tendency to be increased year by year. Also, in
order to reduce manufacturing costs, the number of liquid crystal panels manufactured
by using one master glass substrate (the number of yielded pieces) has been increased.
Table 1 below shows correspondence between a manufacturing line generation
of a liquid crystal panel of an active matrix system and a size of a master glass
substrate. FIG. 1 shows comparison in size among master glass substrates of respective generations.
| TABLE 1 |
| |
| Line |
|
|
|
|
|
|
| genera- |
Substrate |
|
|
|
|
|
| tion |
size |
Type 10 |
Type 11 |
Type 12 |
Type 13 |
Type 15 |
| |
| Phase 1 |
300 × 400 |
2 pieces |
2 pieces |
1 piece |
1 piece |
1 piece |
| |
mm |
yielded |
yielded |
yielded |
yielded |
yielded |
| Phase 2 |
360 × 465 |
4 pieces |
2 pieces |
2 pieces |
2 pieces |
1 piece |
| |
mm |
yielded |
yielded |
yielded |
yielded |
yielded |
| Phase |
400 × 500 |
|
4 pieces |
2 pieces |
2 pieces |
2 pieces |
| 2.5 |
mm |
|
yielded |
yielded |
yielded |
yielded |
| Phase 3 |
550 × 650 |
|
|
6 pieces |
4 pieces |
4 pieces |
| |
mm |
|
|
yielded |
yielded |
yielded |
| Phase |
600 × 720 |
|
|
|
6 pieces |
4 pieces |
| 3.5 |
mm |
|
|
|
yielded |
yielded |
| Phase 4 |
960 × 1000 |
|
|
|
12 |
9 pieces |
| |
mm |
|
|
|
pieces |
yielded |
| |
|
|
|
|
yielded |
| |
As shown in Table 1, in the manufacturing line of phase
1, a size of the
master glass substrate is 300×400 mm, and two liquid crystal panels of type
10 (length of a diagonal is 10.4 inch) or type
11 (length of a diagonal
is 11.4 inch) can be simultaneously formed. On the other hand, in the manufacturing
line of phase
4 currently under studies by makers, the master glass substrate
has a size of 960×1000 mm, and an area 8 times as large as that of the master
glass substrate of phase
1. With the master glass substrate of phase
4,
twelve liquid crystal panels of type
13 (length of a diagonal is 13.3 inch)
or type
14 (length of a diagonal is 14.1 inch) can be simultaneously manufactured.
Recent years have also seen diversification of demands for liquid crystal
panels. At first, the liquid crystal panel was mainly used as a display for a notebook
PC. Then, there has been expansion year by year regarding markets for a large liquid
crystal panel used as a display for a desktop PC or a work station, a medium or
a small liquid crystal panel used for a mobile equipment such as a mobile communication
equipment or a portable information equipment, and a liquid crystal panel used
for a video equipment such as television (TV), video (VTR), a digital camera or
the like.
Conventionally, the manufacturing line of a liquid crystal panel
has been constructed basically for the purpose of providing a liquid crystal panel
having a specified dimension. For example, as shown in FIGS. 2 and 3, in the manufacturing
line of phase
1, a size of a master glass substrate is decided with a view
to yielding two pieces for the liquid crystal panel of type
10. The manufacturing
line is constructed in accordance with this master glass substrate. The following
manufacturing lines are similarly constructed: the manufacturing line of phase
2 for yielding four pieces of the liquid crystal panel of type
10;
the manufacturing line of phase
2.
5 for yielding four pieces of the
liquid crystal panel of type
10 or
11; the manufacturing line of
phase
3 for yielding four pieces of the liquid crystal panel of type
12
(length of a diagonal is 12.1 inch); and the manufacturing line of phase
3.
5
for yielding six pieces of the liquid crystal panel of type
13. Also, the
manufacturing line of phase
4 is constructed with a view to yielding twelve
pieces of the liquid crystal panel of type
13 or
14, or yielding
four to six pieces of the liquid crystal panel of type
15 or bigger.
The inventors of this application consider that the following three problems
are inherent in the conventional manufacturing method of the liquid crystal panel.
The first problem is great fluctuation in productivity caused by a dimension
of the liquid crystal panel. FIG. 4 shows a relationship between a panel size of
the manufacturing line of phase
3 (size of the master glass substrate is
550×650 mm) and the number of yielded pieces. In the manufacturing line of
phase
3, six pieces of the liquid crystal panel of type
11 or
12
are yielded; four pieces of the liquid crystal panels of types
13 to
15
are yielded; two pieces of the liquid crystal panels of types
16 to
19
are yielded; and one piece of the liquid crystal panel of types
20 to
24
is yielded.
Table 2 below shows dependence of an effective substrate utilization factor
reflecting productivity on the number of panel pieces yielded and a panel dimension.
| TABLE 2 |
| |
| Panel dimension |
|
|
| (type) |
Number of yielded |
Effective substrate |
| (or diagonal inch) |
pieces |
utilization factor |
| |
| Type 12 |
6 pieces yielded |
0.86 |
| Type 13 |
4 pieces yielded |
0.67 |
| Type 15 |
4 pieces yielded |
0.87 |
| Type 16 |
2 pieces yielded |
0.51 |
| Type 19 |
2 pieces yielded |
0.72 |
| Type 20 |
1 piece yielded |
0.40 |
| Type 24 |
1 piece yielded |
0.57 |
| |
Herein, an area of the master glass substrate excluding a handling region
of an edge part is set as a substrate effective area, and an area of a display
region of the liquid crystal panel is set as a panel area. Then, effective utilization
area=panel area×number of yielded pieces, and effective substrate utilization
factor=effective utilization area/substrate effective area are defined.
As can be understood from Table 2, even if panel sizes are changed from type
16
to type
19, the number of liquid crystal panels to be simultaneously manufactured
is still two. Accordingly, an effective substrate utilization factor fluctuates
in a range of 0.51 to 0.72. In other words, in a given manufacturing line, there
is a panel size having a maximum effective substrate utilization factor with the
fixed number of yielded pieces. For example, in the case of the manufacturing line
of phase
3, a panel size having a maximum effective substrate utilization
factor is type
12 with the number of yielded pieces set to 6; type
15
with the number of yielded pieces set to 4; type
19 with the number of yielded
pieces set to 2; and type
24 with the number of yielded pieces set to 1.
Among these, a highest effective substrate utilization factor is 0.86 of type
12
with the number of yielded pieces set to 6, and a lowest effective substrate utilization
factor is 0.4 of type
20 with the number of yielded pieces set to 1. This
means that the conventional method exhibits fluctuation twice as large or more,
because an effective substrate utilization factor fluctuates in a range of 0.4
to 0.87 depending on the sizes of liquid crystal panels to be manufactured.
The second problem is inability to deal with diversification of products, which
is caused by enormous investments made in the manufacturing line for liquid crystal
panels. Recent years have seen gradually expanded use of liquid crystal panels
for a display of a notebook (including sub-notebook) PC, a desktop PC or a work
station, a display of a mobile equipment, a video equipment, and so on. Conventionally,
however, a basic idea has been the following: {circle around (1)} a liquid crystal
panel having a specified size is manufactured in a specified manufacturing line;
and {circle around (2)} a specified variety is fed at a specified lot. Accordingly,
in order to deal with diversified liquid crystal panels, a plurality of manufacturing
lines must be constructed according to sizes and varieties of liquid crystal panels.
Conventionally, manufacturing lines have been constructed to match liquid crystal
panels to be manufactured, for example in a manner that a liquid crystal panel
is manufactured for a notebook PC in a first manufacturing line, a liquid crystal
panel is manufactured for a mobile equipment and a video equipment in a second
manufacturing line, and a liquid crystal panel is manufactured for a monitor in
a third manufacturing line.
It was relatively easy to construct manufacturing lines according to sizes or
varieties of liquid crystal panels when there were not many kinds of products.
From now on, however, with a great increase in size of a master glass substrate
and diversification of products, construction of a manufacturing line for each
product will bring about an enormous increase in plant and equipment investments.
Thus, it will be difficult to deal with diversified products.
The third problem of the conventional method is inability to deal with changes
in market demands. For example, around 1994, each maker of a liquid crystal panel
predicted that a size of a liquid crystal panel for a notebook PC would be type
10, and accordingly constructed a manufacturing line of phase
2 with
a view to yielding four pieces of the liquid crystal panel of type
10. Less
than a year, however, a mainstream size of the liquid crystal panel for a notebook
PC changed to type
11. As a result, almost no manufacturing lines which
had been constructed had capability of dealing with the new need, the line was
changed to type
11 with the number of yielded pieces set to 2. Thus, productivity
was reduced by half.
In the next year, 1995, since a mainstream size of the liquid crystal panel changed
to type
12, a specially constructed manufacturing line of phase
2.
5
became one for manufacturing a liquid crystal panel of type
12 with the
number of yielded pieces set to 2. Also, in this case, productivity was reduced
by half.
SUMMARY OF THE INVENTION
The present invention was made with the foregoing problems in mind, and it is
an object of the invention to provide a method for manufacturing a liquid crystal
panel. This method is capable of efficiently using conventional facilities even
if a size of a master glass substrate is changed, easily meeting diversified market
demands, and reducing manufacturing costs. It is another object of the invention
to provide a liquid crystal panel manufactured by the above method. It is yet another
object of the invention to provide a manufacturing system of a liquid crystal panel.
As shown in FIG. 5, the foregoing object is achieved by a method for manufacturing
a liquid crystal panel of an active matrix system. This method is characterized
in comprising the steps of: performing arraying for plotting a master glass substrate
10 into a plurality of blocks 11
a to 11
d, further
plotting the blocks 11
a to 11
d into a plurality of
device-forming regions 12
a to 12
d, and forming a conductive
film, an insulating film and a semiconductor film which constitute TFT in the device-forming
regions 12
a to 12
d; performing primary cutting to cut
the master glass substrate into the blocks 11
a to 11
d so
as to form a plurality of sub-TFT substrates; performing sub-TFT substrate processing
for executing processing for each sub-TFT substrate in accordance with a device
to be manufactured; and performing secondary cutting to cut the sub-TFT substrate
for the respective device-forming regions 12
a to 12
d.
Generally, the manufacturing process of the liquid crystal panel of an
active matrix system is carried out in the order of the following steps: arraying
for forming TFT on the master glass substrate; sub-TFT substrate processing for
forming the pixel electrode and the orientation film and then joining the substrate
to CF substrate; and cutting for cutting the master glass substrate. In the manufacturing
process of the liquid crystal panel, the contents of the arraying step are basically
the same even if different varieties are processed. In other words, in the arraying
step, even if varieties of liquid crystal panels are different, the order of forming
the insulating film, the semiconductor film and the conductive film, a thickness
of each film and materials are almost the same. On the other hand, a material for
the orientation film, a cell gap and a liquid crystal material formed in the sub-TFT
substrate processing step are different from variety to variety.
Thus, with the present invention, the master glass substrate is plotted into
a plurality of blocks, and each block is further plotted into one or a plurality
of device-forming regions. Then, the conductive film, the insulating film and the
semiconductor film which constitute TFT are formed in at least one device-forming
region by executing TFT formation process in the state of the master glass substrate.
In this way, with the invention, processing of the common process is carried out
in the state of the master glass substrate irrespective of the kind of the liquid
crystal panel. At this time, the process uses the first manufacturing line including
a large film-forming equipment, an exposure device, a developer equipment, an etching
equipment, and so on, which are all capable of performing operations in the state
of the master glass substrate.
Then, in the step of primary cutting, the master glass substrate is cut into
the sub-TFT substrates of the respective blocks. For each sub-TFT substrate, processing
is performed in accordance with a device to be manufactured. In other words, an
orientation film is formed by using a material according to the variety of the
liquid crystal panel, or a cell gap is adjusted. In this case, since processing
is carried out in the state of the sub-TFT substrate smaller than the master glass
substrate, the second manufacturing line including a film-forming equipment, an
aligner, a developer equipment, an etching equipment, and so on, can be used, these
elements being smaller than those of the first manufacturing line. In other words,
a manufacturing line of a generation before the first manufacturing line can be
used. Then, in the step of secondary cutting, the sub-TFT substrate is cut to have
a specified panel size, and a liquid crystal is injected into the panel in accordance
with specifications of the liquid crystal panel.
According to the present invention, since the master glass substrate is
divided into a plurality of sub-TFT substrates in the step of primary cutting and
then the sub-TFT substrate processing is performed, the facilities of a previous
generation can be efficiently used. Accordingly, plant and equipment investments
can be reduced. Also, by properly selecting combination of liquid crystal panels
manufactured by using one master glass substrate, an effective substrate utilization
factor can be increased, and dealing with changes in market demands can be facilitated.
In the present invention, for example, a liquid crystal panel having an identical
size may only be formed in one block. Also, to increase an effective utilization
factor, two or more kinds of liquid crystal panels different from one another in
size may be formed in one block. Further, a direct vision type liquid crystal panel
may be formed in a given block, and projection liquid crystal panels may be formed
in the other blocks. Furthermore, a liquid crystal panel of a transmission type
may be formed in a given block, and projection panels of reflection types may be
formed in the other blocks.
With the present invention, since TFT is formed in the state of the master glass
substrate, the arraying step includes a step of forming a semiconductor film. Furthermore,
in the step of sub-TFT substrate processing, however, a semiconductor film may
be formed on the sub-TFT substrate. For example, for forming a liquid crystal panel
incorporating a photoelectric conversion element such as an optical communication
light sensor, an image sensor of a one-dimensional non-adhesion type, an image
sensor of a two-dimensional non-adhesion type, an image sensor of a one-dimensional
adhesive type, an image sensor of a two-dimensional adhesive type or the like,
a silicon film in the light sensor or the image sensor must be formed to be relatively
thick. Film-forming efficiency is higher in simultaneous formation of silicon films
on the plurality of sub-TFT substrates by using a batch film-forming equipment
after division into the sub-TFT substrate than for thick formation of a silicon
film by using a (sheet-fed) film forming equipment in the state of the master glass
substrate. Accordingly, for forming a liquid crystal panel incorporating an optical
communication light sensor or an image sensor, preferably, the sub-TFT substrate
processing step should include a step of forming a semiconductor film.
Japanese Patent Laid-Open Hei. 9 (1997)-325328 disclosed a technology of
forming liquid crystal panels different from one another in size in a master glass
substrate, and then cutting the master glass substrate to match the individual
liquid crystal panels. According to the technology disclosed in Japanese Patent
Laid-Open Hei. 9 (1997)-325328, however, a plurality of liquid crystal panels are
simultaneously formed by using one master glass substrate and, immediately before
the step of injecting a liquid crystal, the master glass substrate is cut and separated
into the individual liquid crystal panels. Consequently, the number of steps of
cutting the substrate is only one, and a large manufacturing line is necessary
for processing the master glass substrate until separation into the individual
liquid crystal panels. For this reason, with the technology disclosed in Japanese
Patent Laid-Open Hei. 9 (1997)-325328, utilization efficiency of the master glass
substrate can be increased, but the manufacturing line of a previous generation
cannot be used. Thus, the technology is not a satisfactory solution for efficient
use of facilities. Also, with the technology disclosed in Japanese Patent Laid-Open
Hei 9 (1997)-325328, only liquid crystal panels having the same orientation film
materials and the same cell gaps can be simultaneously formed. Liquid crystal panels
having different orientation film materials and different cell gaps cannot be manufactured
by using one master glass substrate.
On the other hand, according to the present invention, although the steps performed
in the state of the master glass substrate are common among the liquid crystal
panels, steps intrinsic to each liquid crystal panel can be performed in the step
of sub-TFT substrate processing after cutting the master glass substrate into the
sub-TFT substrates. Therefore, liquid crystal panels having structures different
from one another can be efficiently manufactured by using one master glass substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view showing comparison in size among master glass substrates
of respective generations.
FIG. 2 is a plan view (1) showing a panel size and the number of yielded
pieces in each generation.
FIG. 3 is a plan view (2) showing a panel size and the number of yielded
pieces in each generation.
FIG. 4 is a plan view showing a relationship between a panel size and the number
of yielded pieces in a manufacturing line of phase 3.
FIG. 5 is a plan view showing in outline a method for manufacturing a liquid
crystal panel according to a first embodiment of the present invention.
FIG. 6 is a schematic view showing a manufacturing system of a liquid crystal
panel according to the present invention.
FIG. 7A is a plan view showing a master glass substrate.
FIG. 7B is a plan view showing a sub-TFT substrate.
FIG. 8 is a schematic view showing a liquid crystal panel manufactured by the
manufacturing method of a liquid crystal panel according to the first embodiment.
FIG. 9 is a sectional view showing the liquid crystal panel manufactured by
the manufacturing method of a liquid crystal panel according to the first embodiment.
FIG. 10A is a flowchart (1) showing the manufacturing method of a liquid
crystal panel according to the first embodiment of the present invention.
FIG. 10B is a flowchart (2) showing the manufacturing method of a liquid
crystal panel according to the first embodiment of the present invention.
FIG. 10C is a flowchart (3) showing the manufacturing method of a liquid
crystal panel according to the first embodiment of the present invention.
FIGS. 11A to 11C is a sectional view (1) showing the manufacturing
method of a liquid crystal panel according to the first embodiment of the present invention.
FIGS. 11D and 11E is a sectional view (2) showing the manufacturing
method of a liquid crystal panel according to the first embodiment of the present invention.
FIGS. 11F and 11G is a sectional view (3) showing the manufacturing
method of a liquid crystal panel according to the first embodiment of the present invention.
FIGS. 11H and 11I is a sectional view (4) showing the manufacturing
method of a liquid crystal panel according to the first embodiment of the present invention.
FIG. 12 is a plan view showing an example (1) of combination of a plurality
of liquid crystal panels manufactured by using one master glass substrate.
FIGS. 13A and 13B is a plan view showing an example (2) of combination of a
plurality of liquid crystal panels manufactured by using one master glass substrate.
FIGS. 14A and 14B is a plan view showing an example (3) of combination of a
plurality of liquid crystal panels manufactured by using one master glass substrate.
FIGS. 15A and 15B are plan views, each of which shows a method for manufacturing
a liquid crystal panel according to a second embodiment of the present invention.
FIG. 16 is a plan view showing in outline a method for manufacturing a liquid
crystal panel according to a third embodiment of the present invention.
FIG. 17 is a plan view showing a projection panel of a reflection type according
to the third embodiment.
FIG. 18 is a sectional view showing the same projection panel of a reflection type.
FIG. 19 is a schematic view showing a liquid crystal panel manufactured by a
method for manufacturing a liquid crystal panel according to a fourth embodiment
of the present invention.
FIG. 20 is a plan view showing in outline the manufacturing method of a liquid
crystal panel according to the fourth embodiment.
FIG. 21A is a flowchart (1) showing the manufacturing method of a liquid
crystal panel according to the fourth embodiment.
FIG. 21B is a flowchart (2) showing the manufacturing method of a liquid
crystal panel according to the fourth embodiment.
FIG. 21C is a flowchart (3) showing the manufacturing method of a liquid
crystal panel according to the fourth embodiment.
FIG. 21D is a flowchart (4) showing the manufacturing method of a liquid
crystal panel according to the fourth embodiment.
FIGS. 22A to 22D is a sectional view (1) showing the manufacturing
method of a liquid crystal panel according to the fourth embodiment.
FIGS. 22E to 22G is a sectional view (2) showing the manufacturing
method of a liquid crystal panel according to the fourth embodiment.
FIGS. 22H and 22I is a sectional view (3) showing the manufacturing
method of a liquid crystal panel according to the fourth embodiment.
FIGS. 22J and 22K is a sectional view (4) showing the manufacturing
method of a liquid crystal panel according to the fourth embodiment.
FIG. 23 is a plan view showing a method for manufacturing a liquid crystal panel
according to a fifth embodiment of the present invention.
FIG. 24 is a sectional view showing a two-dimensional image sensor incorporated
in a liquid crystal panel according to the fifth embodiment.
FIG. 25 is a plan view showing an example of applying the method of the fifth
embodiment to manufacturing of a liquid crystal panel incorporating a one-dimensional
adhesion type image sensor.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereinafter, description will be made of the preferred embodiments of
the present invention with reference to the attached drawings.
First Embodiment
FIG. 5 is a plan view showing in outline a method for manufacturing a liquid
crystal panel according to a first embodiment of the present invention; FIG. 6
is a schematic view showing a manufacturing system of a liquid crystal panel; and
FIGS. 7A and 7B are plan views respectively showing a master glass substrate and
a sub-TFT substrate.
In the first embodiment, a master glass substrate having a size of 960×1000
mm is used. And as shown in FIG. 5, the master glass substrate
10 is plotted
into four blocks
11a to
11d. Then, for example, the
following regions are secured in the respective blocks: in the first block
11a,
one device-forming region
12a for forming a liquid crystal panel
of type
20; in the second block
11b, two device-forming regions
12b for forming liquid crystal panels of types
12 to
15;
in the third block
11c, four device-forming regions
12c
for forming liquid crystal panels of types
10 and
11; and in
the fourth block
11d, numerous (six in the drawing) device-forming
regions
12d for forming liquid crystal panels for portable telephone
sets of types
2 and
3. Because of a necessity of handling each sub-TFT
substrate in a later-described sub-TFT substrate processing process, a handling
area having a width of 10 to 15 mm must be secured in an edge of each of the blocks
11a to
11d.
In the embodiment, as shown in FIG. 6, two kinds of manufacturing lines, first
and second manufacturing lines
16 and
17, are used. The first manufacturing
line
16 is composed of a group of devices including a large cleaning equipment
for treating the master glass substrate
10 having a size of 960×1000
mm, a film-forming equipment, an aligner, a developer equipment, an etching equipment,
and so on. By using this first manufacturing line
16, a silicon film, an
insulating film and a conductive film which constitute TFT are formed in each of
the blocks
11a to
11d of the master glass substrate
10. Then, in primary cutting step, the master glass substrate
10
is cut in positions indicated by broken lines shown in FIG.
5 and FIG. 7A,
and then divided into sub-TFT substrates
10a to
10d for
the respective blocks
11a to
11d as shown in FIG. 7B.
A size of each of the sub-TFT substrates
10a to
10d is
set equal to 480×500 mm. The first manufacturing line
16 includes a
film-forming equipment, for instance PECVD (Plasma Enhanced Chemical Vapor Deposition)
device, for forming a semiconductor film serving as an active layer of TFT.
The second manufacturing line
17 shown in FIG. 6 is composed of a group
of relatively small devices including a cleaning equipment, a film-forming equipment,
an aligner, a developer equipment, an etching equipment, and so on, for treating
the sub-TFT substrates
10a to
10d having sizes of 480×500
mm. In other words, for the second manufacturing line
17, a manufacturing
line of a generation before the first manufacturing line
16 can be used.
In this second manufacturing line
17, processing is executed to the sub-TFT
substrates
10a to
10d according to respective liquid
crystal panels manufactured. The second manufacturing line
17 includes a
film-forming equipment made of ITO (indium-tin oxide), for forming a pixel electrode,
for instance a sputtering equipment.
FIG. 8 is a schematic view showing a liquid crystal panel manufactured by the
manufacturing method of a liquid crystal panel according to the first embodiment.
As shown in FIG. 8, a liquid crystal panel
30 includes a plurality of pixels
31 (one is only shown in the drawing) arranged in a matrix form, and a scanning
line
35 and a data line
36 passed among the pixels
31. Each
pixel
31 is composed of a pixel electrode, a counter electrode, a transmitted
light quantity control unit
33 made of a liquid crystal between these electrodes,
TFT
32 and an auxiliary capacitive element
34.
A gate driver LSI (Large Scale Integrated Circuit)
37 and a data driver
LSI
38 are connected to the liquid crystal panel
30. A scanning signal
is supplied from the gate driver LSI
37 to the scanning line
35 by
a specified timing. Display data is supplied from the data driver LSI
38
to the data line
36 by a specified timing.
FIG. 9 is a sectional view showing a direct-vision liquid crystal panel
30
manufactured according to the first embodiment. The liquid crystal panel
30
includes TFT substrate
40 and CF substrate
50 arranged to sandwich
a spacer (not shown), a sealing material
50 for joining TFT substrate
40
and CF substrate
50 with each other, and a liquid crystal
49 sealed
between TFT substrate
40 and CF substrate
50. Polarizing plates
48
and
57 are respectively arranged in the lower side of TFT substrate
40
and in the upper side of CF substrate
50.
TFT substrate
40 is composed of a glass substrate
41, TFT
42
formed thereon, a wiring
43 such as data line and a scanning line, an interlayer
insulating film
44, a pixel electrode
45, a drawer terminal
46
and an orientation film
47. Also, CF substrate
50 is composed of
a glass substrate
51, a black matrix
52 formed below the same, a
color filter
53, an interlayer insulating film
54, a counter electrode
55 and an orientation film
56.
FIGS. 10A to
10C are flowcharts, each of which shows the method for
manufacturing a liquid crystal panel according to the first embodiment. FIG. 10A
shows a flow of steps in a state of the master glass substrate; FIG. 10B shows
a flow of steps in a state of the sub-substrate; and FIG. 10C shows a flow of panel steps.
Hereinafter, the first embodiment will be described in detail by referring
to the flowcharts of FIGS. 10A to
10C, the plan views of FIGS. 7A and 7B
respectively showing the master glass substrate and the sub-TFT substrate, and
the sectional views of FIGS. 11A to
11I, each of which shows the manufacturing
method in the order of steps. In this example, the master glass substrate
10
is divided into the four blocks
11a to
11d. But as
shown in FIG. 7A, an orientation flat
13 for deciding a direction of the
substrate is provided beforehand in the left upper corner of the master glass substrate.
In the other corner, a corner cut
14 is provided. The orientation flat
13
is a notch having a length of a portion indicated by x
1 set to 2.0 mm, and
a length of a portion indicated by y
1 set to 5.0 mm. The corner cut
14
is a notch having lengths of portions indicated by x
2 and y
2 equally
set to 1.5 mm. A reference mark
15 for alignment is provided in the vicinity
of the corner of each of the blocks
11a to
11d.
First, in step S
11 of the flowchart of FIG. 10A, a substrate cleaning
process is carried out for cleaning the surface of the master glass substrate
10.
Next, in step S
12, Cr (chrome) is sputtered on one surface (hereinafter
referred to as an upper surface) of the master glass substrate
10 to form
a Cr film having a thickness of 0.15 to 0.2 μm. Next, the process moves to
step S
13 to form a resist film having a specified pattern on the Cr film
by using a photoresist. Then, in step S
14, the Cr film is etched to form
a TFT gate electrode
21, and a wiring (not shown) such as a scanning line
or the like of the same wiring layer as that of the gate electrode
21, as
shown in FIG.
11A. Subsequently, the resist film is removed.
Next, as shown in FIG. 11B, in step S
15, a substrate cleaning treatment
is executed. In step S
16, SiN
x is deposited to have a thickness
of 0.3 to 0.4 μm on the upper side of the master glass substrate
10
so as to form a gate insulating film
22. Also, on the gate insulating film
22, an amorphous silicon (a-Si) film
23 serving as a TFT channel
region is formed to have a thickness of 0.03 to 0.1 μm. Then, on the amorphous
silicon film
23, SiN
x is deposited to have a thickness of 0.2
to 0.5 μm in order to form a channel protective film
24.
Subsequently, in step S
17, a photoresist is coated on the channel
protective film
24 to form a photoresist film. This photoresist film is
exposed from the lower surface side of the master glass substrate
10. Then,
developing treatment is performed to leave a resist film
25 only above the
gate electrode
21 as shown in FIG.
11C.
Then, in step S
18, the channel protective film
24 is etched by
using the resist film
25 as a mask. Subsequently, as shown in FIG. 11D,
the photoresist film
25 is removed. Accordingly, the channel protective
film
24 is left only above the gate electrode
21.
Then, in step S
19, the substrate cleaning process is executed. As shown
in FIG. 11E, above the master glass substrate
10, an amorphous silicon film
26 doped with n-type impurities and serving as a TFT source/drain region
is formed to have a thickness of about 0.02 to 0.03 μm. Subsequently, in
step S
20, on the silicon film
26, a Ti (titanium) film having a thickness
of 0.05 to 0.1 μm, an Al (aluminum) film having a thickness of 0.1 to 0.2
μm, and a Ti film having a thickness of 0.05 to 0.1 μm are formed in
this order. Then, a conductive film
27 having a laminate structure including
these Ti, Al and Ti films is formed.
Then, in step S
21, primary cutting is performed for the master glass
substrate
10, and divided into the four sub-TFT substrates
10a
to
10d as shown in FIG.
7A. Then, end face processing
is executed for each of the sub-TFT substrates
10a to
10d,
and an orientation flat for alignment (indicated by a solid line circle in FIG.
7B) and a corner cut (indicated by a broken line circle in FIG. 7B) are provided.
The process thus far is performed in the first manufacturing line
16 shown
in FIG. 6, and the process thereafter is performed in the second manufacturing
line
17 shown in the same drawing. In the process thus far, mask alignment
during pattern formation is performed by using the fiducial marks
15 provided
in the four corners of the master glass substrate
10. In the process described
below, description will be made only of the sub-TFT substrate
10a.
But the process for the other sub-TFT substrates
10b to
10d
is basically the same.
In step S
22, the substrate cleaning process is performed for the sub-TFT
substrate
10a after primary cutting. Then, in step S
23, a
resist film (not shown) having a specified pattern is formed on the conductive
film
27 by using a photoresist. Then, in step S
24, the conductive
film
27 is etched by using this resist film as a mask to form a TFT source
electrode, a drain electrode, and a wiring (data line or the like) on the same
wiring layer as those of these electrodes, as shown in FIG.
11F. Also, the
silicon film
26 on the TFT channel region is then removed by etching.
Subsequently, in step S
25, the substrate cleaning process is
executed. Then, in step S
26, as shown in FIG. 11G, an interlayer insulating
film
28 made of SiN
x is formed to have a thickness of 0.3 to
0.4 μm above the sub-TFT substrate
10a. Then, a resist film
(not shown) having a contact hole pattern is formed on the interlayer insulating
film
28 by using a photoresist. In step S
27, the interlayer insulating
film
28 is etched by using the resist film as a mask to form a contact hole
28a as shown in FIG.
11H. Then, the resist film is removed.
Subsequently, in step S
28, the substrate cleaning process is
executed. Then, in step S
29, an ITO film is formed above the sub-TFT substrate
10a by sputtering. Then, in step S
30, a resist film (not shown)
having a specified pattern is formed on the ITO film by using a photoresist. Then,
in step S
31, the ITO film is etched by using the resist film as a mask to
form a pixel electrode
29 and a drawer electrode, as shown in FIG.
11I.
Then, the resist film is removed. In the process from step S
22 to S
31,
mask alignment during pattern formation is performed by using the fiducial marks
provided in the four corners of the sub-TFT substrate
10a.
Subsequently, in step S
32, the substrate cleaning process is
executed. Then, in step S
33, an orientation film (not shown) made of polyimide
is formed to have a thickness of 0.05 to 0.1 μm on the pixel electrode
29.
In step S
34, a surface of the orientation film is subjected to orientation.
For this orientation, rubbing treatment for the surface of the orientation film
by a cloth roller in one direction is generally employed. A material, a thickness
and an orienting method for the orientation film are properly selected in accordance
with specifications of a liquid crystal panel to be manufactured.
Subsequently, in step S
35, a spherical or cylindrical spacer
made of glass or plastic is dispersed above the sub-TFT substrate
10a.
In step S
36, the sub-TFT substrate
10a is stuck to a CF substrate
(see FIG.
9). However, a liquid crystal injection port must be provided
in order to inject a liquid crystal between the TFT substrate (sub-TFT substrate
10a) and the CF substrate in the later process. A method for forming
the CF substrate is the same as the conventional method, and thus description thereof
will be omitted.
Then, in step S
37, secondary cutting is performed. In other words, the
sub-TFT substrate
10a is cut to make a liquid crystal panel having
a specified size.
Subsequently, in step S
38, a liquid crystal is injected between
the sub-TFT substrate
10a and the CF substrate, and a liquid injection
port is sealed with a resin. The kind of a liquid crystal is also selected properly
in accordance with specifications of a liquid crystal panel to be manufactured.
In this way, the manufacturing of the liquid crystal panel having a structure shown
in FIG. 9 is completed. In addition, a glass substrate
41 in FIG. 9 corresponds
to a sub-TFT substrate
10a, and a TFT
42 in FIG. 9 corresponds
to the TFT composed of the gate electrode
21, the gate insulating film
22
and the silicon films
23 and
26 in FIG. 11I. A pixel electrode
45
in FIG. 9 corresponds to the pixel electrode
29 in FIG.
11I.
In the embodiment, for manufacturing four kinds of liquid crystal panels different
from one another in size by using one master glass substrate
10, the process
is performed in the state of the master glass substrate
10 by using the
first manufacturing line
16 until an arraying step for forming TFT for each
pixel. Then, primary cutting is performed for the master glass substrate
10
to separate the same into four sub-TFT substrates
10a to
10d.
Thereafter, the process is performed in the state of the sub-TFT substrates
10a
to
10d by using the second manufacturing line
17 until
a step for joining with a CF substrate.
Thus, in the present embodiment, the use of the first manufacturing line
16
composed of the group of large devices capable of processing in the state of the
master glass substrate is limited until the arraying step. The process thereafter
is performed by the second manufacturing line
17, which is capable of processing
a substrate having a size of ¼ of the master glass substrate. Accordingly,
the number of large equipment can be reduced, and plant and equipment investments
can be reduced. Since the manufacturing line of, for instance a previous generation,
can be used for the second manufacturing line
17, facility utilization factor
is high. Also, since plural kinds of liquid crystal panels different from one another
in size are formed by using one master glass substrate, a utilization factor of
the master glass substrate can be increased by properly combining the sizes of
the respective liquid crystal panels. Because of these effects provided in combination,
manufacturing costs of a liquid crystal panel can be greatly reduced according
to the embodiment. Moreover, according to the present embodiment, by properly selecting
the kind of a liquid crystal display panel manufactured by using one master glass
substrate, changes in market demands can be flexibly dealt with without reducing productivity.
Furthermore, in the present embodiment, mask alignment in the state
of the master glass substrate
10 is performed by using the fiducial marks
15 provided in the four corners of the master glass substrate
10.
Mask alignment in the state of the sub-TFT substrate
10a is performed
by using the reference marks
15 provided in the four corners of the sub-TFT
substrate
10a. Accordingly, the accuracy of alignment is high. For
example, when TFT or a pixel electrode is formed in the state of the master glass
substrate as in the conventional case, the accuracy of alignment is reduced because
of shrinkage or heat history of the master glass substrate. According to the embodiment,
however, the process that needs high alignment accuracy in a contact portion between
the source/drain and the line, in a contact portion between the pixel electrode
and TFT or the like is performed by using the fiducial marks provided in the four
corners of the sub-TFT substrate in the state of the sub-TFT substrate. Accordingly,
the accuracy of alignment can be set to 2 to 3 μm or lower. In other words,
in the liquid crystal display panel manufactured by using the method of the invention,
alignment accuracy by shrinkage can be set smaller than a value estimated based
on a shrinkage rate of the master glass substrate and a heat history thereof during processing.
In addition, the number of the first and second manufacturing lines
16
and
17 shown in FIG. 6 is one for each. Needless to say, however, a plurality
of second manufacturing lines
17 may be provided for one first manufacturing line.
FIGS. 12 to
14B are plan views, each of which shows an example of combination
of a plurality of liquid crystal panels manufactured by using one master glass
substrate. As in the case of the above example, in FIG. 12, a master glass substrate
10 having a size of 960×1000 mm is used. Then, the master glass substrate
10 is plotted into four blocks
11a to
11d. In
the respective blocks, the following regions are secured: in the block
11a,
one device-forming region
12a for forming a liquid crystal panel
of type
20; in the block
11b, two device-forming regions
12b
for forming a liquid crystal panel of type
12; in the block
11c,
four device-forming regions
12c for forming a liquid crystal panel
of type 10; and in the block
11d, a plurality of device-forming regions
12e for forming a liquid crystal panel of a projection type.
FIG. 13A shows an example of manufacturing four liquid crystal panels of types
16 to
23 by using a master glass substrate of 850×1060 mm. FIG.
13B shows an example of manufacturing eight liquid crystal panels of types
13
to
15 by using a master glass substrate of 850×1060 mm. FIG. 14A shows
an example of manufacturing sixteen liquid crystal panels of type
12 by
using a master glass substrate of 850×1060 mm. FIG. 14B shows an example of
manufacturing twenty four liquid crystal panels of type
8.
4 by using
a master glass substrate of 850×1060 mm. In any of these cases, as in the
case of the above-described first embodiment, the process is carried out in the
state of a master glass substrate until an arraying step. Primary cutting is performed
for the master glass substrate in portions indicated by broken lines in the drawing
to divide the same into sub-TFT substrates. Then, after a pixel electrode, an orientation
film, and so on, are formed in the state of the sub-TFT substrate, the substrate
is joined with a CF substrate. Secondary cutting is performed for the sub-TFT substrate
to form a specified liquid crystal panel. Then, a liquid crystal is sealed between
the TFT substrate and the CF substrate.
Second Embodiment
FIGS. 15A and 15B are views, each of which shows a method for manufacturing
a liquid crystal panel according to a second embodiment of the present invention.
In the second embodiment, a master glass substrate
60 is plotted into
four
blocks
61a to
61d. In an example shown in FIG. 15A,
the following regions are secured in each of the blocks
61a to
61d:
for example, one device-forming region
62 for forming a liquid crystal panel
of type
15 for a monitor; and a plurality of device-forming regions
63
for forming liquid crystal panels of types
2 to
3 for portable telephone sets.
In an example shown in FIG. 15B, for example, the following regions are secured
in each of the blocks
61a to
61d: one device-forming
region
64 for forming a liquid crystal panel of type
15 for a monitor;
and two device-forming regions
65 for forming liquid crystal panels of types
6 to
8 for mobile equipments.
In other words, block division is made for each size of a liquid crystal panel
to be manufactured in the first embodiment. Two or more kinds of liquid crystal
panels different from one another in size, however, are formed in each of the blocks
61a to
61d in the second embodiment. The blocks
61a
to
61d have the same structures.
In the second embodiment, as in the case of the first embodiment, a conductive
film, an insulating film and a semicond
