JP3270953B2 - Manufacturing method of liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for manufacturing an active matrix type liquid crystal display device which is switched by a thin film transistor matrix.

An active matrix type liquid crystal display device is widely used as a thin information terminal device together with a simple matrix type liquid crystal display device.

In the active matrix type, since the same operation as driving a large number of pixels independently can be performed, even if the number of lines increases with an increase in display capacity, for example, the active matrix type can be used as in the simple matrix type. In addition, problems such as a reduction in the drive duty ratio, a reduction in contrast, a reduction in viewing angle, and the like do not occur.

[0004] For this reason, the active matrix type liquid crystal display device uses a cathode-ray tube.
e: A CRT) color display can be obtained, and its use as a thin flat display is expanding.

[0005] However, in order to adopt the present invention in, for example, a large-screen color television, it is necessary to reduce costs by manufacturing a display having good display quality by a simple process.

[0006]

2. Description of the Related Art Generally, in an active matrix type liquid crystal display device, in order to obtain a high contrast, a black matrix for preventing light leakage from a portion other than a display electrode portion is provided. I have.

Usually, the black matrix is provided on the color filter substrate facing the active matrix substrate, and takes into account the bonding margin between the active matrix substrate and the display electrode pattern provided on the active matrix substrate. It is formed.

FIG. 12 is a cutaway side view of a main part of an active matrix type liquid crystal display device at a key point in a process for explaining a conventional technique.

In the figure, 1 is an active matrix substrate, 2 is a thin film transistor (TFT).
Stor), 3 is a display electrode, 4 is a color filter substrate, 5 is a black matrix, 6 is a color filter, 7 is an insulating film, and 8 is ITO (indium tin).
oxide) film, 9 is a liquid crystal, 10 is an opening, and M is a bonding margin.

[0010]

As is apparent from FIG. 12, when the conventional technique is used, the pattern of the black matrix 5 is designed to be wider by the margin M for bonding the two substrates 1 and 4 together. Therefore, this is a factor that lowers the aperture ratio.

In order to solve the problem that the aperture ratio is reduced, the width of the alignment margin between the black matrix pattern and the display electrode pattern is reduced by providing a black matrix on the active matrix substrate. However, since the steps of forming and patterning the black matrix are added to the steps in which the manufacturing process of the TFT itself is complicated, problems such as further complicating the process or lowering the manufacturing yield occur.

An object of the present invention is to enable a black matrix to be formed on an active matrix substrate without increasing the number of steps, and to achieve both an improvement in aperture ratio and a reduction in cost.

[0013]

FIGS. 1 and 2 are cutaway side views of a main portion of a liquid crystal display device at important points in a process for explaining the principle of the present invention.

Referring to FIG. 1, 1- (1) A laminated film including a transparent conductive film 12 and a metal film 13 is formed on an insulating substrate 11. 1- (2) At least a drain and a drain bus
A pattern including lines, sources, and display electrodes is formed. 1- (3) In addition to the above, various parts necessary for forming a TFT are formed.

Referring to FIG. 2, 2- (1) A black resin film 14 to be at least a part of the black matrix is formed, and a pattern is formed using the resist film 15 as a mask. Note that, depending on the black resin material and the process, a pattern can be formed by irradiating light from the back surface of the insulating substrate 11 and selectively curing or curing the black resin film 14 with light and developing. . 2- (2) Using the resist film 15 or the black resin film 14 as a mask, the metal film 13 at the display electrode portion is removed,
The display electrode is made transparent by self-alignment.

The black resin film can be formed by various means, for example, spin coating, drain and drain bus lines, and gate and gate bus lines.
In order to apply a voltage to the lines and form an electrodeposition method of forming a black resin film covering each bus line and the like, and to make the black resin film form a desired pattern, a heat treatment is required. Reflow may be used.

From the above, in the method of manufacturing a liquid crystal display device according to the present invention,

(1) A transparent conductive film (for example, an ITO film) and a metal film (for example, Cr) are formed on a substrate (for example, a glass substrate 21).
) And patterning is performed to form at least a drain (for example, drain 22), a drain bus line (for example, drain bus line 23), a source (for example, source 24), and a display electrode (for example, display electrode 25). ) And then a working semiconductor layer (for example, working semiconductor layer 27), a gate insulating film (for example, gate insulating film 28), and a gate (for example, gate electrode 2).
9) and a step of forming a gate bus line, and then a step of forming a black resin film (for example, the black resin film 30) on the entire surface and then patterning to form a pattern (for example, a black matrix); Then, a step of removing the metal film in the display electrode using the black resin film pattern as a mask, or

(2) In the above (1), a step of forming a black resin film by applying a spin coating method and then irradiating light from the back surface of the substrate to selectively cure or thermally cure the black resin film; And then performing a step of developing to form a pattern of the black resin film, or

(3) In the above (1), a step of applying a voltage to the conductive portion to form a black resin film pattern made of an electrodeposited resin covering the conductive portion, and then forming a pattern of the electrodeposited resin Or removing the metal film on the display electrode using the black resin film pattern as a mask, or

(4) In the above (3), a black resin film pattern made of an electrodeposited resin covering a conductive portion is formed, and then a flow by heating is performed to form a black resin film pattern made of the electrodeposited resin. Characterized by widening the width, or

(5) In the above (3) and (4), a negative voltage is applied to the conductive portion to form a black resin film pattern made of an electrodeposition resin, which is a cationic resin, covering the conductive portion. It is characterized by the following.

[0023]

According to the present invention, by adopting the above means, at the time of selectively removing the metal film in the display electrode to make it transparent, at least a part of a black matrix made of a black resin film is used as a mask. Since a certain pattern is used, an active matrix substrate provided with a black matrix can be obtained without increasing the number of manufacturing steps, and despite the simplification of the steps, the aperture ratio is improved and the brightness is increased. A liquid crystal display device can be realized.

[0024]

FIG. 3 to FIG. 5 are explanatory views of a main part of a liquid crystal display device at a key point of a process for explaining a first embodiment of the present invention. (A) shows a main part cut side surface, (B) shows a main part plane corresponding to (A), and will be described below with reference to these drawings. still,
In (A), the line X1-X1 seen in (B) is a cutting line.

Referring to FIG. 3, 3- (1) an IT having a thickness of, for example, 500 [Å] is formed on the glass substrate 21 by applying the sputtering method.
An O film and a Cr film having a thickness of, for example, 1500 [Å] are formed.

3- (2) The Cr film and the ITO film formed in the step 3- (1) are patterned by applying a normal lithography technique, and the drain 22 and the drain bus as a data line are formed. -Form a line 23, a source 24, and a display electrode 25.

Referring to FIG. 4, 4- (1) after removing the resist film used as an etching mask in the above-mentioned step 3- (2), plasma chemical vapor deposition (plasma chemical vapor deposition) is performed.
By applying a pour deposition (plasma CVD) method, an ohmic contact layer 26 made of n ⁺ -a-Si doped with P and having a thickness of, for example, 300 [Å] is formed only on the Cr film. still,
“a” in a-Si indicates that it is amorphous (the same applies to the following description).

In order to selectively form the ohmic contact layer 26 made of n ⁺ -a-Si only on the Cr film,
When performing the plasma CVD method, monosilane (Si
A known technique of intermittently supplying a mixed gas of H ₄ ) and hydrogen (H ₂ ) can be applied.

4- (2) The active semiconductor layer 27 made of a-Si having a thickness of, for example, 500 [Å] and a thickness of, for example, 3000 [Å] by applying the plasma CVD method.
A gate insulating film 28 of SiN _x is formed.

4- (3) An Al film having a thickness of, for example, 2000 [Å] is formed by applying the sputtering method.

4- (4) A resist film having a pattern of a gate electrode and a gate bus line is formed by applying a normal lithography technique.

4- (5) Using the resist film formed in step 4- (4) as a mask, the Al film formed in step 4- (3) is used.
The film is patterned to form a gate electrode 29 (and a gate bus line). In the figure, the gate bus line does not appear due to the cut surface, and the gate electrode 29 does not entirely appear.

4- (6) Subsequently, the gate insulating film 28,
The active semiconductor layer 27 and the ohmic contact layer 26 are patterned to form a TFT matrix.

FIG. 5 5- (1) By applying the spin coating method,
A black resin film 30 having a thickness of, for example, about 1.5 [μm] is formed on the flat portion. In addition, as the black resin, for example, DARC100 (manufactured by Brewer Science: trade name)
Can be used.

5- (2) The temperature is set to, for example, 150 ° C., and the black resin film 30 is baked. 5- (3) By applying the spin coating method,
A positive resist film 31 having a thickness of, for example, about 1.5 [μm] is formed on the flat portion. As the resist, for example, S1800 (trade name, manufactured by Shipley) can be used.

5- (4) The positive resist film 31 is developed by applying a resist process in a usual lithography technique, and an opening 31A corresponding to the display electrode 25 is formed.

When this development is performed, the unexposed portion of the positive resist film 31, that is, the positive resist film 31 on the display electrode 25 is removed. The unexposed portion of the black resin film 30 is also removed. Here, the remaining black resin film 30 constitutes a black matrix.

5- (5) The positive resist film 31, and thus the black matrix, is formed by applying a wet etching method using an etchant containing ceric ammonium nitrate and perchloric acid as main components as an etchant. The display electrode 25 is made transparent by removing the Cr film as a mask.

5- (6) The positive resist film 31 used as a mask is removed.

In the liquid crystal display device completed as described above, the process is simple because the transparency of the display electrode 25 and the pattern formation of the black matrix can be performed using the same mask.

The black matrix and the display electrode 2
The combination with 5 is ~ 3 [μm] by using a stepper
About 7 [μm], which is the margin when a black matrix is formed on the color filter substrate side and bonded to the active matrix substrate. The rate increases.

Further, the drain bus line 23
Has a two-layer structure of a Cr film and an ITO film,
Its resistance is kept low.

In the first embodiment, when forming the black matrix, the black resin film was patterned by using a resist process in lithography technology. However, if an electrodeposition resin is used, a lithography process is used. An embodiment comprising a manufacturing process capable of forming a black matrix without the need for the present invention can be realized.

FIGS. 6 to 8 are cutaway side views of a main part of a liquid crystal display device at a key point of a process for explaining a second embodiment of the present invention. A line X2-X2 seen in the main part plane (B) is a cutting line.

In the second embodiment, the steps up to the stage immediately before the formation of the black resin film are the same as those in the first embodiment, and therefore the description thereof will be omitted. The same symbol and the same symbol represent the same part or have the same meaning.

6- (1) The glass substrate 21 on which the drain and the drain bus line 23 are formed is immersed in an electrodeposition resin liquid in a resin electrodeposition apparatus. In the case of the present invention, the electrodeposition resin needs to be a black resin. Therefore, usually, a resin having a carboxyl group used as an electrodeposition resin and about 20% of a black pigment added thereto Is used.

6- (2) Drain and drain bus
The line 23 as an anode and the opposing electrode as a cathode,
By performing the electrodeposition for 30 [sec] with the applied voltage being 10 [V], the thickness on the drain bus line 23 is reduced to
A black resin film 30 of about [μm] is obtained.

Incidentally, it is necessary to prevent the black resin film from being applied only to the display electrode 25 during this step. To this end, it is necessary to maintain the resistance of the TFT portion at a sufficiently high level. Specifically, it is preferable to set the gate bus line to the ground potential or the negative potential.

6- (3) After forming the black resin film 30 covering the drain and the drain bus line 23, the gate and the gate bus line (not shown) are used as an anode, and the opposite electrode is used. Is used as a cathode, and a black resin film covering the gate and the gate bus line is formed.

During this process, a positive potential is applied to the gate, so that the TFT is turned on. Therefore, the drain and the drain bus line 23 are formed so that the display electrode 25 is not covered with the black resin film. Set to ground potential or negative potential.

The black resin film 3 formed as described above
0 is the distance between the electrodes, that is, the distance between the object to be electrodeposited and the counter electrode, or the degree of stirring of the solution is appropriately selected. Is the film thickness + α, that is, in the case of this embodiment,
3 [μm] for the width of line or gate bus line
It can be formed so as to expand by about 5 to 5 μm.

FIG. 7 7- (1) As shown in FIG. 6, when the black resin film 30 does not overlap the display electrode 25, the black resin film 30 is heated and allowed to flow to spread. It can overlap with the display electrode 25.

The spread of the black resin film 30 can be controlled by the softening point temperature, heating temperature, heating time and the like of the resin material.

For example, a resin having a carboxyl group serving as a base of the black resin film 30 has a softening point temperature of -10 to
[° C], applied voltage ~ 15 [V], time ~ 1
[Min] electrodeposition and a thickness of 3 [μ] immediately after the electrodeposition.
m] to 4 [μm] of the black resin film 30 at a temperature of 180
[° C.], and heating and drying for a time of 30 [minutes]. As a result, the width of the black bus expanded by about 10 [μm] with respect to the width of the drain bus line or the gate bus line.
A matrix pattern is obtained.

8- (1) Cr on display electrode 25 using black resin film 30 as a black matrix pattern as a mask
By removing the film by etching, the ITO film is exposed to make it transparent.

In the black matrix formed as described above, since the width of the pattern is expanded by the flow due to heating, the thickness becomes thinner at the edge portion.
Since the Cr film remains without being etched and the edge of the thinned black matrix pattern overlaps the remaining Cr film, the function as the black matrix does not decrease.

In the liquid crystal display device completed according to the second embodiment, the drain and the drain bus line 23 have a two-layer structure of a transparent conductive film (ITO film) and a metal film (Cr film). Low resistance.

Further, since the formation of the black matrix pattern and the transparency of the display electrode 25 can be realized without using a lithography technique, the manufacturing process is simplified.

Furthermore, since the alignment between the black matrix and the display electrode 25 is performed within the active matrix substrate, it can be adjusted within ~ 3 [μm].
Since a black matrix is formed on the opposite color filter substrate side and bonded to an active matrix substrate, the margin can be reduced to half or less compared with a margin of 7 μm, so that the aperture ratio increases.

In each of the first and second embodiments, a black resin is electrodeposited on a drain, a drain bus line, a gate, a gate bus line, etc. to form a pattern in a matrix. However, for example, electrodeposition of black resin is performed only on the drain and the drain bus line,
The black resin film corresponding to the gate and the gate bus line may be formed separately.

FIG. 9 is a plan view of a main part showing a liquid crystal display device at a key point in a process for explaining a third embodiment of the present invention. The symbols used in FIGS. The same symbols represent the same parts or have the same meaning.

As is clear from the figure, in this embodiment, the black resin film 30 is provided along the drain bus line 23.

Assuming that the direction in which the drain bus line 23 extends is the Y direction, and the direction orthogonal to the Y direction is the X direction, the color filter substrate is only in the X direction.
A black resin pattern corresponding to the gate bus line is formed in a stripe, and the color filter substrate and the active matrix substrate shown in FIG. 9 are bonded to complete the black matrix pattern. .

To make the display electrode 25 transparent, the black resin film 30 formed along the drain bus line 23 is formed.
By etching the Cr film using the mask and the gate bus line made of Al as a mask, self-alignment can be performed as in the first and second embodiments. Note that Al is not etched by an etchant containing ceric ammonium nitrate and perchloric acid as the etchants of Cr as the main components.

In the third embodiment, when the active matrix substrate and the color filter substrate are bonded to each other, the alignment is easy, and the overlap of the black matrix pattern in the X direction is caused by the active matrix substrate. It may be performed between the black resin layer on the side and the display electrode,
Accordingly, it is not necessary to provide a wide margin for alignment, and the aperture ratio is improved.

In each of the above embodiments, the black matrix pattern is formed mainly in alignment with the drain bus line and the gate bus line. For improvement, it is advantageous to form the display electrode pattern, that is, the pixel electrode pattern in a self-aligned manner.

FIGS. 10 and 11 are cutaway side views of a main part of a liquid crystal display device at a key point in a process for explaining a fourth embodiment of the present invention, and FIGS. The same symbols as used symbols represent the same parts or have the same meaning.

10- (1) In the same manner as in each of the embodiments described above, the TFT matrix on the glass substrate 21 is in the stage immediately before the black resin film serving as the black matrix pattern is formed. Is formed.

10- (2) By applying the spin coating method, a black resin film 30 is formed by adding a black dye to a photocurable polyimide as a base.

10- (3) When ultraviolet light is irradiated from the back surface of the glass substrate 21, the drain bus line and the gate
Portions other than the portion where the Cr film is present, such as bus lines and display electrodes, and portions where the ultraviolet light circulates, that is, portions which enter from the edge of the Cr film by about 0.5 μm to 1 μm are photocured. 10- (4) The uncured portion is removed by etching.

Referring to FIG. 11, the entirety of 11- (1) was immersed in an electrodeposition resin solution in a resin
A voltage is applied only to the bus line 23 and the electrodeposition resin film 30 is applied.
Form A.

11- (2) The ITO film is removed by removing the Cr film from the display electrode 25 using the black resin film 30 and the electrodeposited resin film 30A formed in self-alignment with the display electrode 25 as a mask. The display electrode 25 is made transparent by exposing it.

According to the fourth embodiment, the overlap between the black matrix pattern and the display electrode 25 is 0.5 μm
m] to 1 [μm], the aperture ratio is further improved.

In the present invention, the present invention is not limited to the above embodiments, and many other modifications can be realized.

For example, in the embodiment using an electrodeposition resin, since an anion type electrodeposition resin having a carboxyl group is used, for example, when the resin is electrodeposited on a gate and a gate bus line. Then, a positive potential is applied to the gate of the TFT to turn it on, and the black resin film adheres to the display electrode portion as it is.

Therefore, the electrodeposition is performed while maintaining the drain and the drain bus line at the ground potential. Therefore, the electrodeposition of the gate and the gate bus line and the electrodeposition of the drain and the drain bus line are performed. Is implemented separately.

However, if a cationic electrodeposition resin having an amine group, which can perform electrodeposition by applying a negative potential to each bus line, is used, the drain and the drain bus line, the gate And gate bus
By setting both lines to the cathode and the counter electrode to the ground potential, it is possible to perform the electrodeposition of the black resin all at the same time while the TFT is in the OFF state, and the process is further simplified.

In the fourth embodiment, the black resin film 30 is formed in a self-aligning manner, and then the electrodeposited resin film 30A is formed on the drain and the drain bus line. Depending on the conditions, a protective film for the Cr film in the drain and the drain bus line may be formed.

[0079]

According to the method of manufacturing a liquid crystal display device of the present invention, a transparent conductive film and a metal film are formed on a substrate and then patterned to form at least a drain, a drain bus line, a source and a drain. Forming a display electrode, then forming an operating semiconductor layer and a gate insulating film and a gate and a gate bus line, then forming a black resin film over the entire surface and then patterning to form a pattern, The metal film on the display electrode is removed using the black resin film pattern as a mask.

By adopting the above configuration, when the metal film on the display electrode is selectively removed and made transparent, a pattern which is at least a part of a black matrix made of a black resin film is used as a mask. Since it is used, it is possible to obtain an active matrix substrate provided with a black matrix without increasing the number of manufacturing steps. Can be realized.

[Brief description of the drawings]

FIG. 1 is a cutaway side view of a main part of a liquid crystal display device at a key point in a process for explaining the principle of the present invention.

FIG. 2 is a cutaway side view of a main part of the liquid crystal display device at a key point in the process for explaining the principle of the present invention.

FIG. 3 is an explanatory view of a main part of the liquid crystal display device at a key point in the process for explaining the first embodiment of the present invention.

FIG. 4 is an explanatory view of a main part of the liquid crystal display device at a key point in the process for explaining the first embodiment of the present invention.

FIG. 5 is an explanatory view of a main part of the liquid crystal display device at a key point in the process for explaining the first embodiment of the present invention.

FIG. 6 is a fragmentary side view showing a liquid crystal display device at a key point in a process for explaining a second embodiment of the present invention.

FIG. 7 is a cutaway side view of a main part of a liquid crystal display device at a key point in a process for explaining a second embodiment of the present invention.

FIG. 8 is a fragmentary side view showing a liquid crystal display device at a key point in a process for explaining a second embodiment of the present invention.

FIG. 9 is a plan view of a main part of a liquid crystal display device at a key point in a process for explaining a third embodiment of the present invention.

FIG. 10 is a fragmentary side view showing a liquid crystal display device at a key point in a process for explaining a fourth embodiment of the present invention.

FIG. 11 is a fragmentary side view showing a liquid crystal display device at a key point in a process for explaining a fourth embodiment of the present invention.

FIG. 12 is a cutaway side view of a main part of an active matrix type liquid crystal display device at an important part of a process for explaining a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Glass substrate 22 Drain 23 Drain bus line 24 Source 25 Display electrode 26 Ohmic contact layer 27 Operating semiconductor layer 28 Gate insulating film 29 Gate electrode 30 Black resin film 30A Electrodeposited resin film 31 Positive resist film 31A Opening

Continued on the front page (72) Inventor Tsutomu Tanaka 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Yutaka Takizawa 1015 Uedanaka, Nakahara-ku, Nakahara-ku Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (72) Invention Kenichi Oki 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (56) References JP-A-61-59389 (JP, A) JP-A-61-182266 (JP, A) JP-A-2-2523 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/1368 G02F 1/1335 500 G09F 9/30 338 H01L 29/786

Claims (5)

(57) [Claims] A step of forming a transparent conductive film and a metal film on a substrate and patterning them to form at least a drain, a drain bus line, a source, and a display electrode; A step of forming a gate insulating film, a gate, and a gate bus line, and then a step of forming a black resin film on the entire surface and then performing patterning to form a pattern, and then using the black resin film pattern as a mask. Removing the metal film from the display electrode. 2. A step of forming a black resin film by applying a spin coating method, and then irradiating light from the back surface of the substrate to selectively light-cur or heat-cur, and then developing the black resin film. 2. The method according to claim 1, further comprising the step of forming a film pattern. A step of applying a voltage to the conductive portion to form a black resin film pattern made of an electrodeposited resin covering the conductive portion; and a display electrode using the black resin film pattern made of the electrodeposited resin as a mask. 2. The method according to claim 1, further comprising the step of removing the metal film in the step (a). 4. The method according to claim 1, wherein a black resin film pattern made of an electrodeposited resin covering the conductive portion is formed, and then a flow based on heating is performed to increase the width of the black resin film pattern made of the electrodeposited resin. Item 4. The method for manufacturing a liquid crystal display device according to item 3. 5. A black resin film pattern made of an electrodeposition resin, which is a cation-type resin, which covers the conductive portion by applying a negative voltage to the conductive portion. Method for manufacturing a liquid crystal display device.