JPH11337961A - Reflective liquid crystal display device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflective liquid crystal display having a bright display and a low cost, and a simple method for its manufacturing. SOLUTION: The reflective liquid crystal display comprises a plurality of scanning signal lines and data signal lines located crossing with each other, switching elements located in a pattern of a matrix, an active matrix substrate 30 having pixel electrodes which are provided corresponding to switching element and have reflective functions, a counter substrate 40 having a counter electrode and a liquid crystal layer 10 which is located between the active matrix substrate 30 and the counter substrate 40. The pixel electrode has a surface with projecting and recessing parts which are corresponding to the projecting parts having a layer formed with a substrate protecting layer and another layer formed with a gate insulating film 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reflection type liquid crystal display device and a method for manufacturing the same. More particularly, the present invention relates to a low-cost reflective liquid crystal display device having a bright display and a simple manufacturing method thereof.

[0002]

2. Description of the Related Art In recent years, the application of liquid crystal display devices to office automation equipment such as word processors, laptop computers, pocket televisions and the like has been rapidly advancing. Furthermore, such OA equipment is becoming portable. 2. Description of the Related Art As OA equipment has become more portable, it has been desired to reduce the size of liquid crystal display devices. In particular, a reflective liquid crystal display device that performs display by reflecting light incident from the outside has attracted much attention because it does not require a backlight, has low power consumption, and can be thin and lightweight.

Conventionally, in order to obtain excellent display characteristics,
There has been proposed a reflection type liquid crystal display device provided with a reflection electrode having an uneven shape (for example, Japanese Patent Application Laid-Open No. 5-232465).
Since the reflective electrode having the uneven shape increases the intensity of light scattered in a direction perpendicular to the display screen, a reflective liquid crystal display device with a bright display can be obtained. According to Japanese Patent Application Laid-Open No. H5-232465, such a reflective electrode includes (1) forming a first film made of a photosensitive resin on a substrate; and (2) patterning the first film to form a large number on the substrate. (3) A liquid material such as an acrylic resin is applied to the substrate on which the irregularities are formed and cured to form a second film having a large number of curved surfaces; (4) It is obtained by forming a film made of a reflective material on the two films.

As described above, a reflective liquid crystal display device having a reflective electrode having an uneven shape as described in JP-A-5-232465 has an advantage that the display is bright, but the manufacturing process is complicated. As a result, there is a problem that the manufacturing cost increases. More specifically, such a method of manufacturing a liquid crystal display device includes, in addition to a normal manufacturing process of a reflective liquid crystal display device, a process for providing a concave and convex shape on a reflective electrode (the above processes (1) to (4)). )).

[0005] Alternatively, Japanese Patent Application Laid-Open No. 7-159776 describes a liquid crystal display device provided with a reflective electrode having irregularities formed using auxiliary capacitance wiring. However, such a reflective electrode does not provide sufficient reflective characteristics (that is, brightness). This is because the auxiliary capacitance wiring is related to the driving of the liquid crystal display device, and therefore, the unevenness can be formed only within a range that does not affect the driving.

Therefore, there is a demand for a low-cost reflective liquid crystal display device having a bright display and a simple manufacturing method thereof.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a reflective liquid crystal display device having a bright display and a low cost. It is to provide a simple manufacturing method thereof.

[0008]

The reflection type liquid crystal display device of the present invention comprises a plurality of scanning signal lines and data signal lines provided crossing each other, switching elements provided in a matrix, and the switching elements. An active matrix substrate having a pixel electrode having a reflection function provided in correspondence with: an opposing substrate having an opposing electrode; and a liquid crystal layer disposed between the active matrix substrate and the opposing substrate; The pixel electrode has an uneven surface, and the unevenness of the pixel electrode corresponds to a projection having a layer formed from the substrate protective film and a layer formed from the gate insulating film.

In a preferred embodiment, the convex portion is
The semiconductor device further includes a layer of a material for forming the data signal line.

In a preferred embodiment, the liquid crystal display device further includes an interlayer insulating film on the switching element and the convex portion, and the interlayer insulating film has an uneven surface corresponding to the convex portion. The unevenness of the pixel electrode corresponds to the unevenness of the interlayer insulating film.

The method of manufacturing a reflection type liquid crystal display device according to the present invention comprises the steps of: forming a substrate protective film and a gate insulating film on a substrate; and patterning the substrate protective film and the gate insulating film to form the substrate protective film. Forming a convex portion having a layer formed from the above and a layer formed from the gate insulating film in a pixel portion of the substrate, and simultaneously patterning the gate insulating film in a terminal portion of the substrate; Forming a pixel electrode having a reflective function and having a concave-convex surface corresponding to the portion.

In a preferred embodiment, the method comprises:
Forming a data signal line on the substrate on which the convex portion is formed;
At the same time, the method further includes a step of forming a layer of a material for forming the data signal line on the layer of the convex portion formed from the gate insulating film.

The operation of the present invention will be described below.

According to the present invention, the unevenness of the pixel electrode (reflection electrode) corresponds to the projection having the layer formed of the substrate protective film and the layer formed of the gate insulating film. That is, unevenness is formed on a substrate using a material essential for forming a TFT, and a pixel electrode having an uneven surface is formed using the unevenness. Therefore, a material and a manufacturing process required only for forming the unevenness of the reflective electrode are not required. Therefore, a liquid crystal display device with low cost and excellent manufacturing efficiency can be obtained. Further, since neither the substrate protective film nor the gate insulating film is involved in driving the liquid crystal display device, it is possible to form irregularities having optimal reflection characteristics. Therefore, the reflection characteristics are excellent (that is, bright).
A liquid crystal display device is obtained.

According to a preferred embodiment, the material for the source wiring is also used for forming the irregularities. By using the material for the source wiring to form the irregularities simultaneously with the formation of the source wiring, consumption of materials other than the material for forming the TFT can be further suppressed, and the number of manufacturing steps can be further reduced.

According to another preferred embodiment, an interlayer insulating film is further provided on the projection. The interlayer insulating film is usually
It is formed from a liquid photosensitive acrylic resin. The interlayer insulating film formed of such a liquid photosensitive acrylic resin has an upwardly convex arc-shaped cross section at a portion corresponding to the convex portion due to the surface tension at the time of application, and has a concave portion (a convex portion). The portion corresponding to (other portions) has a downwardly convex arc-shaped cross section.
That is, by forming an interlayer insulating film from a liquid acrylic resin, an uneven surface with few flat portions can be obtained. When a reflective electrode is formed on such an uneven surface having a small number of flat portions, a specular reflection component is reduced, so that a reflective electrode having a reflection characteristic closer to a scattering state rather than a mirror state can be obtained. In addition, since the interlayer insulating film also has a function as a protective film for the TFT, consumption of materials other than the material forming the TFT can be further suppressed, and the number of manufacturing steps can be further reduced.

According to the method of manufacturing a reflection type liquid crystal display device of the present invention, a convex portion is formed in a pixel portion of a substrate, and simultaneously, a terminal portion of the substrate is processed. Therefore, the manufacturing process can be significantly simplified as compared with the conventional manufacturing method.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the drawings, but the present invention is not limited to these embodiments.

FIG. 1 is a schematic plan view of a liquid crystal display according to a preferred embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II of the liquid crystal display of FIG.

As shown in FIGS. 1 and 2, the liquid crystal display device 100 includes an active matrix substrate 30, a counter substrate 40, the active matrix substrate 30, and the counter substrate 40.
And a liquid crystal layer 10 disposed between the two.

In the active matrix substrate 30,
A substrate protection film (base coat film) 2 is provided on an insulating substrate (for example, a glass substrate) 1. Further, on the insulating substrate, switching elements (for example, TFTs) 50 arranged in a matrix, a gate wiring (scanning signal line) 4 for sending a gate signal to each switching element 50, and a source signal (data And a source wiring (data signal line) 6 for transmitting a signal. Gate wiring 4
And source wiring 6 are provided in parallel with each other. The gate wiring 4 and the source wiring 6 are provided so as to cross each other (substantially orthogonal in this embodiment). An interlayer insulating film (acrylic resin film) 7 is provided so as to cover the switching element 50, the gate wiring 4 and the source wiring 6. Further, on the interlayer insulating film 7,
A pixel electrode (reflection electrode) 8 having a reflection function is provided. If necessary, the alignment film 9 is provided on the surface of the active matrix substrate 30 on the liquid crystal layer 10 side.

The switching element (TFT) 50 includes a gate electrode 4b, a gate insulating film 3, a semiconductor layer 5, and a contact layer 5a.
5b, a source electrode 6b, and a drain electrode 6c. A part of the gate wiring 4 branches to form a gate electrode 4b, and a part of the source wiring 6 branches to form a source electrode 6b. The TFT 50 has a drain electrode 6c electrically connected to the reflective electrode 8 via a contact hole 13 provided through the interlayer insulating film 7.

The counter substrate 40 has a color filter 12, a black matrix 11, and an alignment film 9 if necessary, on the insulating substrate 1.

The reflection electrode 8 has an uneven surface. This is to increase the intensity of light scattered in a direction perpendicular to the display screen with respect to incident light from all angles. The unevenness of the reflective electrode 8 corresponds to the convex portion 14 having at least the layer formed from the substrate protective film 2 and the layer formed from the gate insulating film 3 (that is, the convex portion on the surface of the reflective electrode is convex). The recesses on the surface of the reflective electrode correspond to the portions where the protrusions 14 are not formed (for convenience, the recesses 14 ').
Preferably, the projections 14 are formed by simultaneously patterning the substrate protection film 2 and the gate insulating film 3. Preferably, this convex portion 14 may have a layer 6 ′ of a source wiring material on a layer formed from the gate insulating film 3.
Preferably, the uneven surface of the reflective electrode 8 is formed corresponding to the uneven surface of the interlayer insulating film provided on the substrate 1 having the convex portions 14.

FIG. 3 is a schematic plan view showing the whole of such a reflection type liquid crystal display device. In the display area 19, as described above, a large number of gate wirings and source wirings provided to intersect with each other, and switching elements (TFTs) provided in a matrix near the intersection of the gate wirings and the source wirings are provided. Have been. Each TFT is electrically connected to a reflection electrode provided corresponding to the switching element (for simplicity, these are not shown).

A portion of the periphery of the active matrix substrate 30 exposed from the counter electrode 40 has a gate terminal portion 15 electrically connected to a terminal of a gate driving IC (not shown);
A source terminal portion 16 electrically connected to a terminal of a source driving IC (not shown), and a terminal portion 17 electrically connected to a terminal of a driving substrate called a so-called flexible substrate.
Are provided. The gate terminal unit 15, the source terminal unit 16, and the terminal unit 17 are electrically connected by the terminal lead-out wiring 18. Further, common transition electrodes 20 are provided at two corners of the counter substrate 40. A schematic sectional structure of the gate terminal portion is shown in FIG. 4A, and a schematic sectional structure of the source terminal portion is shown in FIG.

FIG. 5 is a schematic plan view of the gate terminal portion of FIG. FIG. 6 is a sectional view taken along line VI-VI of FIG.
As shown in FIGS. 5 and 6, in the gate terminal portion 15, the gate wiring 4 is provided on the insulating substrate 1, and the insulating film 3 is provided to cover the periphery of the end of the gate wiring 4 and the substrate 1. Have been. Further, a source wiring 6 is provided so as to cover the gate wiring 4 and partially overlap the insulating film 3.

Hereinafter, an example of a method for manufacturing such a liquid crystal display device will be described with reference to FIGS. FIG.
9 are schematic cross-sectional views for explaining a manufacturing process of the active matrix substrate of the liquid crystal display device of the present invention. 7 to 9 each illustrate a manufacturing process of a TFT portion, a pixel portion, and a terminal portion of a substrate.

First, as shown in FIGS. 7 (a), 8 (a) and 9 (a), an insulating substrate (for example, glass substrate; manufactured by Corning, trade name 1737) 1 Tantalum (T
a ₂ O ₅ ) is deposited to a thickness of 3000 mm by sputtering,
An insulating substrate protection film 2 is formed. Further, for example, tantalum (Ta) is deposited to a thickness of 3000 ° by a sputtering method to form a gate wiring film 4 ′. Next, FIG. 7 (b), FIG.
As shown in FIG. 9B and FIG. 9B, the gate wiring film 4 ′ is patterned into a predetermined shape by photolithography and etching to form the gate electrode 4 b and the gate wiring 4. The gate wiring film 4 ′ may be formed, for example, by oxidizing tantalum by anodic oxidation to form an insulating film made of Ta ₂ O _{5 on the} surface in order to protect the insulating properties of the wiring.

Next, as shown in FIGS. 7 (c), 8 (c) and 9 (c), for example, silicon nitride (SiNx) is
The gate insulating film 3 is formed so as to cover the entire surface of the substrate by a thickness of 3000 ° by the D method. Further, as shown in FIG. 7C, the semiconductor layer 5 of the TFT 50 and the contact layers 5a and 5b are formed by using an appropriate material and using an appropriate method.

Next, as shown in FIGS. 8D and 9D, the pixel portion and the terminal portion are simultaneously processed. Specifically, as shown in FIG. 9D, the insulating film 3 on the gate wiring 4 in the terminal portion is formed in a predetermined shape (for example, as shown in FIG. 6) by photolithography and dry etching. ). At the same time, the pixel portion is patterned by photolithography using a hole pattern (for example, a pattern having a large number of holes having a diameter of 2 to 8 μm) as indicated by reference numeral 14 in FIG.
A projection 14 having a layer formed from the substrate protective film 2 and a layer formed from the gate insulating film 3 is formed. in this way,
At the same time as the processing of the terminal portion, the convex portion 14 is formed in the pixel portion.

Next, as shown in FIGS. 7 (e) and 9 (e), a source wiring film such as titanium (Ti) deposited to a film thickness of 3000.degree.
The source electrode 6b and the drain electrode 6c of T50 and the source bus wiring 6 are formed. At the time of patterning the source wiring film 6 ′, in the pixel portion, by etching with a resist pattern shown by reference numeral 14 in FIG. 1, the gate insulating film of the convex portion 14 is formed as shown in FIG. The layer 6 ′ of the source wiring material can be formed on the layer formed from 3.

Next, as shown in FIG. 7 (f), a photosensitive acrylic resin is applied by spin coating and cured to form an interlayer insulating film 7 and patterned by photolithography to form a TFT 50. A contact hole 13 is formed in the drain electrode 6c.
The thickness of the interlayer insulating film 7 can be adjusted to any appropriate thickness (for example, 0.5 to 4.5 μm) by appropriately changing the rotation speed and rotation time of the spin coater. In the terminal portion, as shown in FIG. 9F, the interlayer insulating film 7 is patterned so that the source wiring 6 is exposed.

In the pixel portion, as shown in FIG. 8F, the interlayer insulating film 7 has an upwardly convex curved surface (for example, an arc-shaped cross section) at a portion corresponding to the convex portion 14, and the concave portion 14. 'Has a downwardly convex curved surface (for example, an arc-shaped cross section). Such an uneven surface is caused by the surface tension of the resin at the time of application. The interlayer insulating film 7 not only forms an uneven surface for the reflective electrode 8, but also functions as a protective film of the TFT 50 as is apparent from FIG. The interlayer insulating film 7 is denoted by reference numeral 14 in FIG.
(In this case, the protrusions 14 having the layer of the interlayer insulating film are formed on the layer 6 ′ of the source wiring material).

Finally, as shown in FIGS. 7 (g) and 8 (g), for example, aluminum (Al) is vapor-deposited by sputtering at an appropriate thickness (for example, 100 to 400 nm), and then photolithography is performed. Then, a reflective electrode having an uneven surface is formed on the pixel portion and the contact hole 13 by patterning by an etching method. Thus, the active matrix substrate 30 is manufactured.

Finally, the active matrix substrate 30 and the counter substrate 40 are attached to each other, and a liquid crystal material for forming a liquid crystal layer as a display medium is injected into a gap between the substrates to manufacture a liquid crystal display device.

[0037]

According to the present invention, a pixel electrode (reflection electrode) is provided.
Correspond to the protrusions having the layer formed from the substrate protective film and the layer formed from the gate insulating film. That is, unevenness is formed on a substrate using a material essential for forming a TFT, and a pixel electrode having an uneven surface is formed using the unevenness. Therefore, a material and a manufacturing process required only for forming the unevenness of the reflective electrode are not required. Therefore, a liquid crystal display device with low cost and excellent manufacturing efficiency can be obtained. In addition, since neither the substrate protective film nor the gate insulating film is involved in driving the liquid crystal display device, it is possible to form irregularities having optimal reflection characteristics. Accordingly, a liquid crystal display device having excellent (ie, bright) reflection characteristics can be obtained. As described above, according to the present invention, a low-cost reflective liquid crystal display device having a bright display is provided.

Further, according to the method of manufacturing a reflection type liquid crystal display device of the present invention, a convex portion is formed in a pixel portion of a substrate, and simultaneously, a terminal portion of the substrate is processed. Therefore, the manufacturing process can be significantly simplified as compared with the conventional manufacturing method. As a result, a low-cost and simple manufacturing method of a reflective liquid crystal display device having a bright display is provided.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a liquid crystal display according to a preferred embodiment of the present invention.

FIG. 2 is a cross-sectional view of the liquid crystal display device of FIG. 1 taken along the line II-II.

FIG. 3 is a schematic plan view showing the entire reflection type liquid crystal display device according to a preferred embodiment of the present invention.

4A is a schematic sectional view of a gate terminal section of FIG. 3, and FIG. 4B is a schematic sectional view of a source terminal section of FIG.

FIG. 5 is a schematic plan view of a gate terminal unit in FIG. 3;

6 is a sectional view taken along line VI-VI of FIG.

FIG. 7 is a schematic cross-sectional view for explaining a manufacturing process of the TFT portion of the active matrix substrate of the liquid crystal display device of the present invention.

FIG. 8 is a schematic cross-sectional view for explaining a manufacturing process of the pixel portion of the active matrix substrate of the liquid crystal display device of the present invention.

FIG. 9 is a schematic cross-sectional view for explaining a manufacturing process of the terminal portion of the active matrix substrate of the liquid crystal display device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Substrate protective film 3 Gate insulating film 4 Gate wiring 5 Semiconductor layer 6 Source wiring 7 Interlayer insulating film 8 Reflective electrode 9 Alignment film 10 Liquid crystal layer 11 Black matrix 12 Color filter 13 Contact hole 14 Convex part 30 Active matrix substrate 40 Opposite Substrate 100 LCD

Claims (5)

[Claims] 1. A plurality of scanning signal lines and data signal lines provided to intersect with each other, switching elements provided in a matrix, and a pixel electrode having a reflection function provided corresponding to the switching elements. An active matrix substrate having: a counter substrate having a counter electrode; a liquid crystal layer disposed between the active matrix substrate and the counter substrate; the pixel electrode having an uneven surface; A reflection type liquid crystal display device in which unevenness corresponds to a projection having a layer formed from a substrate protective film and a layer formed from a gate insulating film. 2. The reflection type liquid crystal display device according to claim 1, wherein said projection further includes a layer of a material forming said data signal line. 3. An interlayer insulating film is further provided on the switching element and on the projecting portion, the interlayer insulating film having an uneven surface corresponding to the projecting portion, wherein the unevenness of the pixel electrode is caused by the interlayer insulating film. 3. The reflection type liquid crystal display device according to claim 1, wherein the reflection type liquid crystal display device corresponds to the unevenness of the film. Forming a substrate protective film and a gate insulating film on the substrate; patterning the substrate protective film and the gate insulating film to form a layer formed from the substrate protective film and the gate insulating film; Forming a convex portion having the formed layer in the pixel portion of the substrate, and simultaneously patterning the gate insulating film of the terminal portion of the substrate; and a reflection function having a concave-convex surface corresponding to the convex portion. Forming a pixel electrode having: a method of manufacturing a reflective liquid crystal display device. 5. A method for forming a data signal line on a substrate on which the convex portion is formed, and simultaneously forming a layer of a material for forming the data signal line on a layer of the convex portion formed from the gate insulating film. The method for manufacturing a reflective liquid crystal display device according to claim 4, further comprising a forming step.