JP2000275660A - Liquid crystal display device and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal display device of both transmission and reflection type, with which an always stable display grade is obtained by specifying the effective display areas of the transparent electrodes and reflection electrodes in the pixel parts of the liquid crystal display device of both transmission and reflection type always constant. SOLUTION: The liquid crystal display device of both transmission and reflection type is constituted, by taking the misalignment of interlayer insulating films 3 and reflection electrode materials 4 and 5 into consideration so as to avoid the direct contact of the electrode material constituting the transmissible display part and the electrode materials 4, 5 constituting the reflection display part in the boundary region of the transmissible display part and the reflection display part. More specifically, a stepped sloping part having a gradient is formed in the boundary region of the transmissible display part and the reflection display part of the interlayer insulating films 3 and the ends of the electrode materials 4 and 5 constituting the reflection display particularly are positioned on the stepped sloping part of the interlayer insulating films 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device used for OA equipment such as a word processor or a personal computer, portable information equipment such as an electronic organizer, or a camera-integrated VTR equipped with a liquid crystal monitor, and a method of manufacturing the same. About.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been used in word processors, personal computers, televisions, video cameras, still cameras, in-vehicle monitors, portable OA equipment, portable game machines, etc. by utilizing the characteristics of being thin and having low power consumption. Widely used.

Such a liquid crystal display device includes a transmissive liquid crystal display device using a transparent electrode such as ITO (Indium Tin Oxide) as a pixel electrode and a reflective liquid crystal display device using a reflective electrode such as a metal as a pixel electrode. There is a liquid crystal display device.

A liquid crystal display device is not a self-luminous display device that emits light by itself unlike a CRT (CRT) or an EL (electroluminescence) device. A lighting device such as a fluorescent tube, a so-called backlight, is arranged behind the device,
The display is performed by the light incident from there. Further, in the case of a reflection type liquid crystal display device, display is performed by reflecting external incident light by a reflection electrode.

Here, in the case of a transmission type liquid crystal display device,
In order to perform display using the backlight as described above,
Although it has the advantage of being able to perform a bright and high-contrast display without being greatly affected by the surrounding brightness, a backlight typically accounts for 50% or more of the total power consumption of a liquid crystal display device. From consuming
There is also a problem that power consumption increases.

Further, in the case of the reflection type liquid crystal display device, since the backlight is not used as described above, it has an advantage that the power consumption can be extremely reduced. There is also a problem that the brightness and contrast of the display are affected by the use environment or use conditions.

As described above, the reflection type liquid crystal display device has a drawback that the visibility is extremely lowered in the use environment such as the surrounding brightness, especially when the external light is dark. On the other hand, the transmissive liquid crystal display device also has a problem in that, when the external light is very bright, the visibility in, for example, clear weather is reduced.

As a means for solving such problems, a liquid crystal display device having both functions of a reflection type and a transmission type has been proposed, for example, in Japanese Patent Application No. 9-201176. The liquid crystal display device proposed by this patent application incorporates a reflective display unit that reflects external light and a transmissive display unit that transmits light from a backlight in one display pixel, so that the surroundings are completely dark. Is a transmissive liquid crystal display device that performs display by using light transmitted from the backlight through the transmissive display unit, and in the case where external light is dark, light transmitted through the transmissive display unit from the backlight and light A dual-purpose liquid crystal display device that performs display using both light reflected by a reflective display portion formed of a film having a relatively high reflectance, and further, when external light is bright, the light reflectance is relatively high. This is a transflective liquid crystal display device that can be used as a reflective liquid crystal display device that performs display using light reflected by a reflective display portion formed of a high film.

[0009] The liquid crystal display device having the above-described structure can provide a liquid crystal display device always having excellent visibility regardless of the brightness of external light. For example, after forming a bus wiring, a thin film transistor, and a transparent electrode for a transmissive display portion on a substrate,
An interlayer insulating film made of a photosensitive resin or the like is formed on these portions, and the photosensitive resin in the contact portion and the transmissive display portion is completely removed by exposure and development, and at the same time, becomes a reflective display portion on the photosensitive resin. In order to obtain an optimal reflection characteristic for the portion, for example, by performing a heat treatment after exposing and developing the photosensitive resin through a light shielding unit in which circular light shielding regions are arranged, a plurality of uneven patterns are formed. ing. Then, a method is used in which a reflective electrode for a reflective display portion made of a metal thin film is formed on the concave / convex pattern along the shape of the concave / convex portion.

[0010] In addition, when the reflection plate is formed outside the substrate (the side opposite to the liquid crystal layer) and the double reflection due to the influence of the glass thickness is caused, the reflection plate is formed inside the substrate and the pixel is formed. The problem is solved by using a structure also serving as an electrode, that is, a reflective electrode.

[0011]

The liquid crystal display device having such a structure can provide a liquid crystal display device which always has excellent visibility irrespective of the brightness of external light. In order to realize bright and high color purity color display in both the reflection type and the reflection type, it is necessary to increase the intensity of light scattered in the direction perpendicular to the display screen for incident light from all angles, Further, in order to obtain stable display quality as a liquid crystal display device, it is necessary that the reflection characteristics and the transmission characteristics of individual display devices are always constant without fluctuation.

For this purpose, it is necessary to manufacture a reflective electrode having an optimal reflection characteristic and a transparent electrode having an optimal transmission characteristic. In order to provide an optimal reflection characteristic on the surface of a substrate made of glass or the like. It is necessary to form controlled irregularities and form a reflective electrode on which a thin film made of a metal film or the like is formed, and to form a reflective electrode and a transparent electrode, a film forming step, a photolithographic step, and etching. It has been necessary to strictly control factors relating to patterning accuracy in the process and the like so that the effective display area of the reflective electrode and the transparent electrode is always constant.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to effectively display a transparent electrode and a reflective electrode in a pixel portion of a transflective liquid crystal display device. An object of the present invention is to provide a transmission-reflection type liquid crystal display device capable of always obtaining a stable display quality by keeping the area constant, and a method of manufacturing the same.

[0014]

In order to achieve the above-mentioned object, a liquid crystal display device according to the present invention is provided on one of a pair of substrates disposed opposite to each other with a liquid crystal layer interposed therebetween. In a liquid crystal display device in which a pixel electrode that forms a reflective display unit that reflects external light and a transmissive display unit that transmits light from a back light source in one pixel is formed, the reflective display unit that constitutes the pixel electrode And the transmissive display unit are each formed of an electrode material, and these electrode materials are partially or entirely overlapped with an interlayer insulating film interposed therebetween. And a step slope having a slope is formed in a boundary region of the transmissive display section, and an end of an electrode material forming the reflective display section is located on the step slope of the interlayer insulating film. Characteristic It is.

[0015] In order to achieve the above-mentioned object, a method of manufacturing a liquid crystal display device according to the present invention comprises the steps of: forming a substrate on one of a pair of substrates arranged to face each other with a liquid crystal layer interposed therebetween; In a method for manufacturing a liquid crystal display device, in which a pixel electrode that forms a reflective display portion that reflects external light and a transmissive display portion that transmits light from a back light source in one pixel is formed, at least the transmissive display portion is formed. Forming a transparent electrode material by patterning on one side of the substrate including a region to be formed, and forming an interlayer insulating film by patterning on the transparent electrode including at least the region constituting the reflective display section And a step of patterning and forming a reflective electrode material in a region constituting the reflective display portion on the interlayer insulating film, wherein a boundary region between the reflective display portion and the transmissive display portion of the interlayer insulating film is formed. , Forming a stepped inclined portion having an arrangement, and patterning so that an end portion of a reflective electrode material constituting the reflective display portion is located on the stepped inclined portion formed in the interlayer insulating film. .

Hereinafter, the operation of the present invention will be described.

According to the liquid crystal display device and the method of manufacturing the same of the present invention, the boundary region between the transmissive display unit and the reflective display unit is
The boundary between the transmissive display section and the reflective display section is taken into account in consideration of misalignment between the interlayer insulating film and the reflective electrode so that the electrode material forming the transmissive display section does not directly contact the electrode material forming the reflective display section. The end of the reflective electrode in the region is configured to be located at the step inclined portion of the interlayer insulating film.

That is, according to the present invention, as shown in FIG. 7, for example, a stepped inclined portion 17 having a gradient is formed in a boundary region B between the reflective display portion C and the transmissive display portion A of the interlayer insulating film 3. And that the reflective electrode material 4 is patterned so that the end of the reflective electrode material 4 constituting the reflective display portion C is located on the stepped inclined portion 17 formed in the interlayer insulating film 3. Features. (Note that the reference numeral 18 in the drawing indicates the unevenness formed in the region of the reflective display section C on the interlayer insulating film 3.) Here, the step inclined portion 17 formed in the interlayer insulating film 3 This is a portion that does not substantially contribute to both the reflective display and the transmissive display (because of the slant, the reflective display cannot be performed correctly, and the transmissive display cannot be correctly performed due to a voltage drop). Therefore, by forming the end portion of the reflective electrode material 4 so as to be located on the stepped inclined portion 17, even if the area of the reflective electrode changes due to the variation in patterning accuracy, the range of the stepped inclined portion 17 is reduced. Within the range, there is no effect on the change in the effective display area of the reflective display section and the transmissive display section, and the effective display area of the transparent electrode and the reflective electrode in the pixel portion of the transflective liquid crystal display device is not affected. It is possible to be a constant.

In this regard, for example, as shown in FIG.
If the end portion of the reflective electrode material 4 is formed so as to be located at the transmissive display portion A, the effective area of the transmissive display portion A changes due to a variation in patterning accuracy. For example, as shown in FIG. The end of the reflective electrode material 4 is connected to the reflective display section C.
In this case, the effective area of the reflective display section C is similarly changed due to a variation in patterning accuracy.

As described above, according to the present invention, in the boundary region between the transmissive display section and the reflective display section, the electrode material forming the transmissive display section and the electrode material forming the reflective display section are prevented from directly contacting each other. By taking into account the misalignment between the interlayer insulating film and the reflective electrode material, the problem of corrosion due to electrolytic corrosion of the electrode material and blackening due to reduction can be solved, and the transflective liquid crystal is used. The effective area of the transmissive display unit and the reflective display unit in the display device can always be made constant, and a transflective liquid crystal display device with stable transmittance and reflectance can be realized. ing.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows Embodiment 1 of the present invention.
2 is a plan view showing a configuration of a pixel portion of the liquid crystal display device in FIG. 2, and FIG. 2 is a cross-sectional view taken along line AA 'of FIG.

FIGS. 3A to 3D and FIG.
FIGS. 3E to 3H are cross-sectional views illustrating processes of a transmissive display unit and a reflective display unit in a pixel portion of the liquid crystal display device according to the first embodiment.

The transmissive display and the reflective display constituting the pixel portion of the liquid crystal display according to the first embodiment will be described with reference to FIGS. First, as shown in FIG. 3A, a T layer is formed on the insulating substrate 1 as a base coat film.
forming an insulating film such as a ₂ O ₅ , SiO ₂ (not shown);
Thereafter, a metal thin film made of Al, Mo, Ta or the like is formed on the insulating substrate 1 by a sputtering method, and is patterned to form the gate electrode 8.

Next, a gate insulating film 10 is laminated on the insulating substrate 1 so as to cover the gate electrode 8 described above. In the first embodiment, the SiNx film is formed to 3000
ÅLaminated to form a gate insulating film 10. In order to enhance the insulating property, the gate electrode 8 is anodized, the anodized film is used as a first gate insulating film 9, and an insulating film 10 such as SiN is formed by a CVD method to form a second insulating film. The film 10 may be used.

Next, the channel layer 11 (amorphous S
i) and the electrode contact layer 12 (amorphous Si or microcrystalline Si doped with an impurity such as phosphorus) are continuously formed on the gate insulating film 10 by the CVD method.
500 ° and 500 ° are laminated, and both Si films of the electrode contact layer 12 and the channel layer 11 are formed by patterning by a dry etching method using a mixed gas of HCl + SF ₆ .

Thereafter, as shown in FIG. 3 (b), a transparent conductive film (ITO) 13 is laminated as an electrode material constituting the transmissive display portion by sputtering at a thickness of 1500 °, followed by an Al, Mo, Ta film or the like. The metal thin films 14 and 15 are stacked. And by patterning these,
Source electrodes 13 and 14 and drain electrodes 13 and 15 are formed.

Next, as shown in FIG. 3C, an insulating film of SiN or the like is laminated at 3000.degree. By a CVD method and then patterned to form an insulating film 7. Next, as shown in FIG.

Next, as shown in FIG. 3D, a photosensitive resin 3 serving as an interlayer insulating film is applied on the insulating film 7, and after exposing and developing the photosensitive resin 3, a heat treatment is performed. Thereby, a plurality of uneven portions 18, contact portions, and transmissive display portions are formed. The photosensitive resin 3 serving as the interlayer insulating film is formed with a thickness of 30000 ° and has a step inclined portion 7 corresponding to a boundary region between the reflective display portion and the transmissive display portion.
Are patterned so as to have a gradient of about 45 °.

Next, as shown in FIG. 4E, a reflective electrode composed of Al / Mo films 4 and 5 is formed on a substrate 1 containing a photosensitive resin 3 as an electrode material constituting a reflective display section by a sputtering method. To form a film having a thickness of 1000/500 °.

Then, as shown in FIG. 4F, a photoresist 16 is formed in a predetermined shape on the electrode material constituting the reflective display portion by using a photolithography process. At this time, I, which is an electrode material constituting the transmissive display section,
Since Mo5 exists between TO2 and Al4 which is an electrode material constituting the reflective display portion, the photoresist 1
Even if the electrolyte solution infiltrates from the Al4 film defect part during the development of No. 6, Mo5 functions as a barrier metal, so that no electrolytic corrosion reaction occurs.

At this time, when patterning the electrode material constituting the reflective display in the next step, ITO2 and Al4 /
It is necessary to prevent direct contact with Mo5. That is, as shown in the cross-sectional view of FIG. 2, the photoresist 16 in the boundary area between the transmissive display section and the reflective display section is taken into account in consideration of the misalignment between the interlayer insulating film 3 and the reflective electrodes 4 and 5. The end portion is a step inclined portion 7 of the interlayer insulating film 3.
Exposure development. With such an arrangement, since the step inclined portion 7 of the interlayer insulating film 3 is a portion that does not participate in both transmissive display and reflective display, even if the patterning accuracy of the reflective electrode varies somewhat. In addition, the effective display area of the transparent electrode and the reflective electrode can be always kept constant by stabilizing the reflectance and the transmittance, and a stable display quality can be always realized.

Then, as shown in FIG.
Using an etchant composed of acetic acid + phosphoric acid + water, Al4 / Mo5, which is an electrode material constituting the reflective display portion, is simultaneously etched to form a reflective electrode.

Finally, as shown in FIG. 4H, the photoresist 16 formed by photolithography is removed by using a batch type peeling device, whereby the pixel of the liquid crystal display device according to the first embodiment is removed. The part is completed.

Here, a batch type stripping apparatus used for removing the photoresist 16 formed by the photolithography will be described with reference to FIG. FIGS. 5A to 5C are schematic views showing a batch type photoresist 16 stripping step in the first embodiment.

As shown in FIGS. 5 (a) to 5 (c), the substrate 20 having undergone the above-described steps is treated with MEA as an amine.
The substrate 20 is immersed in a stripping solution 21 containing 60 wt% (monoethanolamine), and then immersed in water 22 to remove the stripping solution 21 on the surface of the substrate 20 and washed with water. At this time, in the process of transporting the substrate 20 from the stripping tank to the washing tank as shown in FIG. 5B, the stripping liquid 21 is attached to the surface of the substrate 20, and the substrate 20 is washed with water. By immersing in the bath, the MEA 21 and the water 22 are mixed on the surface of the substrate 20 to increase the alkalinity.

Therefore, in the conventional liquid crystal display device, when the photoresist 16 is removed,
In the boundary region between the transmissive display unit and the reflective display unit, ITO2, which is an electrode material forming the transmissive display unit, and Al4 / Mo5, which is an electrode material forming the reflective display unit, are adjacent to each other. Will happen.

However, in the first embodiment, as described above, in the boundary region between the transmissive display section and the reflective display section, as shown in the sectional view of FIG. In consideration of misalignment between the interlayer insulating film 3 and the reflective electrodes 4 and 5, the transmissive display unit and the reflective display unit may be used to prevent direct contact between the reflective display unit and Al 4 / Mo 5 as an electrode material constituting the reflective display unit. The edge of the photoresist 16 in the boundary region of the interlayer insulating film 3
Because it is configured to be located at the step inclined portion 7 of
The photoresist 16 can be removed without causing electrolytic corrosion between ITO as the transparent electrode material and Al as the reflective electrode material.

An alignment film is applied to each of the TFT substrate having a pixel portion manufactured as described above and a transparent counter substrate (not shown) on which a transparent electrode is formed, and baked. Then, a rubbing treatment is applied to this alignment film, and spacers are scattered. Then, these two substrates are bonded together with a sealing resin, and liquid crystal is injected by a vacuum injection method to produce a liquid crystal display element. In the first embodiment, in order to operate in the horizontal alignment liquid crystal mode, the rubbing directions are set to be parallel, and a nematic liquid crystal having a positive dielectric anisotropy is injected. Finally, one polarizing plate and one retardation plate are provided on both sides of the liquid crystal display element, respectively, and a backlight is provided on the back surface. Thus, the transflective liquid crystal display device according to the first embodiment is completed.

(Embodiment 2) In Embodiment 1 described above, a method of removing the photoresist 16 formed by photolithography using a batch-type peeling apparatus has been described. A method for removing the photoresist 16 formed by photolithography using a single-wafer stripper will be described.

FIGS. 6A to 6D are schematic views showing a step of removing the photoresist 16 in the second embodiment. The manufacturing process of the liquid crystal display device according to the second embodiment is performed according to the same flow as that of the first embodiment described above, except for the step of removing the photoresist 16.

As shown in FIGS. 6A to 6D, the substrate 20 having undergone the steps of FIGS.
Is MEA (monoethanolamine) as amine
It is immersed in a stripping solution 21 containing 0 wt%, and then immersed in water 22 and washed with water to remove the stripping solution 21 on the surface of the substrate 20. At this time, in a process in which the substrate 20 as shown in FIG.
The surface of the substrate 20 is in a state in which a stripping liquid 21 is attached.
The MEA 21 and the water 22 mix on the surface and the alkalinity increases.

Therefore, in the conventional liquid crystal display device, when the photoresist 16 is removed,
In the boundary region between the transmissive display unit and the reflective display unit, ITO2, which is an electrode material forming the transmissive display unit, and Al4 / Mo5, which is an electrode material forming the reflective display unit, are adjacent to each other. Although this occurs, the second embodiment
Also, as described above, in the boundary region between the transmissive display section and the reflective display section, as shown in the cross-sectional view of FIG. 2, ITO2 which is an electrode material constituting the transmissive display section and an electrode material which constitutes the reflective display section In order to prevent direct contact with Al4 / Mo5, the photoresist 16 in the boundary area between the transmissive display section and the reflective display section is taken into account in consideration of misalignment between the interlayer insulating film 3 and the reflective electrodes 4 and 5. The end is
The photoresist 16 is removed without causing electrolytic corrosion between ITO, which is a transparent electrode material, and Al, which is a reflective electrode material, because it is configured to be located at the step inclined portion 7 of the interlayer insulating film 3. be able to.

[0044]

As described above, according to the liquid crystal display device and the method of manufacturing the same of the present invention, in the boundary region between the transmissive display section and the reflective display section, the electrode material constituting the transmissive display section and the reflective display section are formed. By taking into account the misalignment between the interlayer insulating film and the reflective electrode material so that the electrode material constituting the part does not come into direct contact, the problem of corrosion due to electrolytic corrosion of the electrode material and blackening due to reduction is eliminated. In addition to being able to solve the problem, the effective area of the transmissive display section and the reflective display section in the transflective liquid crystal display device can always be made constant, and the transmissive and reflective dual-use liquid crystal display apparatus has stable transmittance and reflectivity. Type liquid crystal display devices can be realized.

[Brief description of the drawings]

FIG. 1 is an enlarged plan view illustrating a configuration of a pixel portion of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a configuration of a pixel portion of the liquid crystal display device according to the embodiment of the present invention.

FIGS. 3A to 3D are enlarged cross-sectional views showing processes of a pixel portion of the liquid crystal display device according to the embodiment of the present invention.

FIGS. 4E to 4H are enlarged cross-sectional views showing processes of a pixel portion of the liquid crystal display device according to the embodiment of the present invention.

FIGS. 5A to 5C are schematic views showing a batch type photoresist stripping step in the embodiment of the present invention.

FIGS. 6A to 6D are schematic views showing a single-wafer photoresist stripping step according to the embodiment of the present invention.

FIG. 7 is an enlarged cross-sectional view showing a configuration of a pixel portion of the liquid crystal display device according to the present invention.

FIG. 8 is an enlarged sectional view showing a configuration of a pixel portion of a liquid crystal display device according to a comparative example of the present invention.

FIG. 9 is an enlarged cross-sectional view illustrating a configuration of a pixel portion of a liquid crystal display device according to a comparative example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Transparent electrode material (ITO) 3 Photosensitive resin (interlayer insulating film) 4 Reflective electrode material (Al) 5 Reflective electrode material (Mo) 6 Transmissive display part 7 Insulating film 8 Gate electrode 9 Anodized film 10 Gate insulation Film 11 Channel layer 12 Electrode contact layer 13 Source electrode (ITO) 14 Source electrode (Ta) 15 Drain electrode (Ta) 16 Photoresist 17 Step inclined part 18 Uneven part 20 Substrate 21 Stripping liquid 22 Water

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuki Kobayashi F-term (reference) 2H092 HA05 JA26 JA29 JA33 JA35 JA38 JA42 JA44 JB13 JB23 JB32 JB33 JB38 JB51 in 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka JB56 JB63 JB69 KA05 KA07 KA12 KA16 KA18 MA05 MA08 MA14 MA15 MA16 MA18 MA19 MA20 MA24 MA27 MA35 MA37 MA41 NA25 NA27 5C094 AA07 AA12 AA43 AA48 AA54 BA03 BA43 CA19 CA20 DA13 DA15 DB04 EA04 AEB EA05 EA05 EA05 EA05 BB16 CC09 EE25 FF03 FF11 FF13 KK05 LL07

Claims (2)

[Claims] 1. A reflective display section for reflecting external light and a transmissive display section for transmitting light from a back light source on one of a pair of substrates disposed opposite to each other with a liquid crystal layer interposed therebetween. In a liquid crystal display device in which a pixel electrode constituting one pixel is formed, the reflective display portion and the transmissive display portion constituting the pixel electrode are each made of an electrode material, and these electrode materials are A part or the whole thereof is overlapped with an insulating film interposed therebetween, and the interlayer insulating film is formed with a step inclined portion having a gradient in a boundary region between the reflective display portion and the transmissive display portion, and A liquid crystal display device, wherein an end portion of an electrode material forming a reflective display portion is located on a step inclined portion of the interlayer insulating film. 2. A reflective display section for reflecting external light and a transmissive display section for transmitting light from a rear light source on one of a pair of substrates disposed opposite to each other with a liquid crystal layer interposed therebetween. In a method for manufacturing a liquid crystal display device in which a pixel electrode constituting one pixel is formed, a transparent electrode material is formed by patterning a transparent electrode material on at least one substrate including a region constituting the transmissive display portion. A step of patterning and forming an interlayer insulating film on the transparent electrode including at least a region constituting the reflective display portion; and forming a reflective electrode material on the region constituting the reflective display portion on the interlayer insulating film. Forming a stepped inclined portion having a gradient in a boundary region between the reflective display portion and the transmissive display portion of the interlayer insulating film, and configuring the reflective display portion. Method of manufacturing a liquid crystal display device ends morphism electrode material, characterized by patterning so as to be positioned in the interlayer insulating film which is formed in the stepped inclined portion on.