JP2000284324A - Reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display device which can be produced without increasing the material or the production process. SOLUTION: In the reflection type liquid crystal display device 1, a first substrate 2 having thin film transistor arrays and a second substrate 3 having a common electrode 24 are disposed facing each other with the liquid crystal layer 4 interposed and a reflection electrode 5 is connected to the thin film transistors on the first substrate 2. In this device, the base layer of the reflection electrode 5 includes layers 20a, 20b, 20c, 20d formed as recesses and projections by etching, and these layers are produced by using the layers formed when the thin film transistors are produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a reflection type liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, in order to reduce the power consumption of a display device, a reflection type liquid crystal display device which does not require a backlight has attracted attention. In such a reflection type display device, Japanese Patent Application Laid-Open No. H6-23023 has been proposed in order to effectively utilize incident light.
As shown in Japanese Patent Publication No. 399 and the like, irregularities are formed on the surface of the reflective electrode. And the unevenness of the reflective electrode is
It is formed using the unevenness formed on the surface of the underlayer. As the underlayer, an organic insulating film such as an acrylic resin formed so as to cover the thin film transistor array is used.

[0003]

If the organic insulating film covering the thin film transistor array is used as the base layer as described above, the occupation ratio of the pixels can be increased, but it is necessary to separately form an organic insulating layer. There is a problem that the number of materials used and the number of manufacturing steps increase. Therefore, an object of the present invention is to provide a reflective liquid crystal display device that can be manufactured without increasing the number of materials and manufacturing steps.

[0004]

According to a first aspect of the present invention, there is provided a reflection type liquid crystal display device comprising a first substrate provided with a thin film transistor array and a second substrate provided with a common electrode with a liquid crystal layer interposed therebetween. In a reflection type liquid crystal display device in which a reflection electrode is connected to a thin film transistor of the first substrate, the reflection liquid crystal display device includes, as a base layer of the reflection electrode, a layer formed to be uneven by etching after film formation. It is characterized in that a layer formed at the time of manufacturing a thin film transistor is used.

The reflection type liquid crystal display device of the present invention is described in claim 2
A reflective liquid crystal display device in which a first substrate having a thin film transistor array and a second substrate having a common electrode are disposed to face each other with a liquid crystal layer interposed therebetween as described in, and a reflective electrode is connected to the thin film transistor of the first substrate. In the above, as a base layer of the reflective electrode, a layer formed unevenly by etching after film formation is used, and a plurality of types of layers having different height differences using a layer formed at the time of manufacturing the thin film transistor. Are formed.

The reflection type liquid crystal display device of the present invention is described in claim 3.
The reflective liquid crystal display device according to claim 1 or 2, wherein the underlayer has a protrusion in which a conductive layer is covered with an insulating layer.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of an essential part showing one embodiment of a reflection type liquid crystal display device of the present invention, and FIG.
1 is a plan view showing a main part of one substrate, FIG. 3 is a sectional view showing an embodiment of a base layer, and FIG. 4 is a schematic process diagram showing a method for manufacturing one substrate.

As shown in FIG. 1, a reflection type liquid crystal display device 1 includes a first substrate 2 having a thin film transistor array,
A second substrate 3 having a common electrode is opposed to the second substrate 3 with a liquid crystal layer 4 interposed therebetween.

As shown in FIG. 2, a plurality of gate wirings 7 mainly made of aluminum, chromium or the like are formed in parallel on a first substrate 2 on an insulating substrate 6 made of glass or the like. A gate electrode 8 is formed integrally with the gate wiring 7. A gate insulating film 9 made of silicon nitride, silicon oxide, or the like is formed so as to cover the gate wiring 7 and the gate electrode 8.

On the gate insulating film 9 located above the gate electrode 8, a semiconductor layer 10 made of amorphous silicon or polycrystalline silicon is formed. In the semiconductor layer 10, a channel region 11 thinned by an etching process is formed. Semiconductor layer 10
A pair of contact layers 12, 12 made of a silicon semiconductor layer which is made conductive by increasing the impurity concentration is formed so as to sandwich the channel region 11. A source electrode 13 made of chromium, titanium, or the like is formed on one contact layer 12 so as to overlap, and a drain electrode 14 made of chromium, titanium, or the like is formed on the other contact layer 12 so as to overlap. Have been. Source electrode 13
As shown in FIG. 2, the source wiring 15 is connected to the direction perpendicular to the gate wiring 7. A thin film transistor 16 including the above-described elements is formed near the intersection of the gate line 7 and the source line 15, and the thin film transistors 16 are arranged in a matrix to form a thin film transistor array on the substrate 6.

An insulating protective film 17 made of silicon nitride or silicon oxide, similar to the gate insulating film 9, is formed so as to cover the gate wiring 7, the source electrode 13, the source wiring 15, and the thin film transistor 16. A contact hole 18 is formed in a region of the protective film 17 located above the drain electrode 14.
The connection between the reflective electrode 5 and the thin film transistor 16 is achieved via the reference numeral 8.

The reflective electrode 5 is formed of aluminum having good reflectivity or an aluminum compound mainly composed of aluminum. The reflective electrode 5 is formed in a region surrounded by the gate wiring 7 and the source wiring 15 except for a region where the thin film transistor 16 is formed. Has formed. Various irregularities 19 having different shapes are formed on the surface of the reflective electrode 5. This unevenness 19 is
For example, the planar shape can be formed by a circular convex or concave shape, and the shape is determined by the layer 20 serving as the base of the reflective electrode 5.
Shape is reflected. The underlayer 20 with the irregularities 19
Is an underlayer 20a formed simultaneously with the gate insulating film 9.
An underlayer 20 b formed simultaneously with the semiconductor layer 10;
An underlayer 20c formed simultaneously with the contact layer 12,
It is formed by selectively utilizing the underlayer 20d formed simultaneously with the protective film 17, and is formed into a predetermined shape at the same time as the patterning of each layer. The height of each unevenness 19 is determined by the thickness and pattern shape of each underlying layer, and in the example shown in FIG. 1, the total thickness of the four underlying layers is 6000 to 150.
It is about 00 °. On the reflective electrode 5 and the protective film 16,
An alignment film 21 made of polyimide or the like is formed.

The other substrate 3 has a color filter layer 23 and a common electrode 24 on an insulating substrate 22 made of glass or the like.
Is formed over substantially the entire surface, and an alignment film 25 made of polyimide or the like is formed thereon. The first and second substrates 2 and 3 are positioned with a predetermined distance therebetween, and are sealed by a sealing material around the surroundings, and then injected with a liquid crystal, for example, a TN type, a guest host type, or the like, to reflect light. Type liquid crystal display device 1.

Next, a method of manufacturing one substrate 2 will be schematically described with reference to FIG. The insulating substrate 6 having been subjected to the cleaning process is prepared, and the gate wiring 7 and the gate electrode 8 are formed thereon (first step S1). Next, a gate insulating film made of silicon nitride is formed to a thickness of about 2000 to 5000 ° (second step S2). Subsequently, a semiconductor layer made of amorphous silicon is formed to a thickness of about 2000 to 5000 °, and a contact layer made of impurity-doped amorphous silicon is formed to a thickness of about 300 to 800 ° (third step S3). ).

Next, the layers formed in the third step S3 are subjected to etching and patterning, so that the underlayers 20c and 20 are formed in addition to the contact layer 12 and the semiconductor layer 10.
b is formed (fourth step S4). Next, the second step S
The underlying layer 20a is formed simultaneously with the formation of the gate insulating film contact hole (not shown) by etching and patterning the layer formed in Step 2 (fifth step).
Step S5). Next, a source electrode 13, a drain electrode 14, and a source wiring 15 are formed by depositing and patterning chromium (sixth step S6).

Next, the channel layer 11 is formed by etching the contact layer 12 and the semiconductor layer 10 (seventh step S7). Next, a protective film made of silicon nitride is formed to a thickness of about 2000 to 5000 ° so as to cover the entire surface of the substrate 6 (eighth step S8). Next, by etching and patterning the layer formed in the eighth step S8, the hole 26 is formed at the same time as the formation of the contact hole 18 for the reflection electrode, and the underlayer 20d is formed (ninth embodiment). Step S9). Next, a reflective electrode 5 is formed by depositing and patterning aluminum (tenth process S10).

In this way, the substrate 2 having the thin film transistors 16 with the reflective electrodes 5 in an array can be manufactured.

Next, an underlayer 20 serving as an underlayer of the reflective electrode 5
Will be described with reference to FIG. FIG. 2A shows the same structure as that shown in FIG.
With this structure, the base of the reflective electrode 5 has a form in which the truncated cone-shaped irregularities (projections or depressions) 19 are dispersed on the insulating substrate 6. Since the underlayer 20c having conductivity is covered with insulating underlayers 20a and 20d, contact between the reflective electrode 5 and the underlayer 20c (contact layer 12) is prevented by the underlayers 20a and 20d. Can be. The underlayer 20d that covers the underlayers 20a, 20b, and 20c covers the portions corresponding to the corners of the underlayers 20a, 20b, and 20c that have been sharpened by etching so as to be rounded. It also functions to disperse the applied stress. Here, the height of the truncated cone-shaped protrusion (depth in the case of a recess) corresponds to the total thickness of the underlayers 20a to 20d, and is about 6000 to 15000 ° in this example.

FIG. 2B shows a structure in which the hole 26 formed in the underlayer 20 d (protective film 17) is not formed in the structure of FIG. That is, the uppermost layer 2 of the underlayer
0d is left in a continuous shape without being etched in the region above the reflective electrode 5 after the film is formed. By doing so, the height of the unevenness is slightly reduced,
A sharp edge portion formed above the hole 26 of the underlayer 20d can be eliminated, and the stress applied to the reflective electrode 5 from this portion can be eliminated. (C) and (d) of FIG.
This is an example in which the underlayer 20a removed by etching is left as it is in the structure shown in FIG. By doing so, the height of the unevenness is slightly reduced, but it is possible to eliminate the sharp edge portion formed above the etching hole of the base layer 20a and eliminate the stress applied to the reflective electrode 5 from this portion. .

The underlayer 20 shown in FIGS.
Can be formed by selecting the same type for each substrate 2 unit, but a plurality of types can be mixed in one substrate 2. For example, although the base layer of one reflective electrode 5 is formed of the same type of base layer, the type of the base layer may be different if the reflective electrode 5 is different. In addition, in one reflective electrode 5, as a base layer thereof, FIG.
A plurality of types of underlayers as shown in (a) to (d) may be mixed. Further, the reflection state of the reflective electrode 5 can be variously set in accordance with the color element of the color filter layer 23, and the mixed form of the underlayer 20 can be variously set in accordance with the color element. .

The underlayer 20 having such an unevenness is formed.
Can use the same manufacturing process as the conventional one using only the material used for manufacturing the transistor 16 and making a slight modification to the patterning mask, so that the manufacturing is easy and without increasing the cost. It is useful in that it can. In addition, the underlayer 20 is composed of a plurality of layers 20a to 20d, and a step is formed for each predetermined layer and provided with recesses having different depths, so that the shape of the reflective electrode 5 formed thereon is complicated. This is effective in forming a reflective electrode suitable for scattering incident light.

[0022]

As described above, according to the present invention, a reflection type liquid crystal display device can be manufactured without increasing materials and manufacturing steps. In addition, it is possible to provide a shape of the reflective electrode capable of effectively scattering incident light by complicating the unevenness of the underlying layer that defines the shape of the reflective electrode.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of an embodiment of a reflection type liquid crystal display device of the present invention.

FIG. 2 is a schematic plan view around a transistor of the device.

FIG. 3 is a cross-sectional view of a main part showing a configuration example of a reflective electrode base layer of the device.

FIG. 4 is a schematic process diagram illustrating a method for manufacturing a substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reflection type liquid crystal display device 5 Reflection electrode 8 Gate electrode 9 Gate insulating film 19 Unevenness 20 Underlayer

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Taku Ikemoto 3-201 Minamiyoshikata, Tottori City, Tottori Prefecture F-term in Tottori Sanyo Electric Co., Ltd. (reference) 2H092 JA26 JA46 JB07 JB08 KA04 KA05 KA12 KA17 NA27 QA07 QA08

Claims (3)

[Claims] 1. A reflection type liquid crystal display device comprising: a first substrate having a thin film transistor array and a second substrate having a common electrode opposed to each other with a liquid crystal layer interposed therebetween; and a reflection electrode connected to the thin film transistor of the first substrate. The method according to claim 1, wherein the underlayer of the reflective electrode includes a layer formed unevenly by etching after the film is formed, and the layer uses a layer formed at the time of manufacturing the thin film transistor. Liquid crystal display device. 2. A reflection type liquid crystal display device comprising: a first substrate having a thin film transistor array and a second substrate having a common electrode disposed opposite to each other with a liquid crystal layer interposed therebetween, and a reflection electrode connected to the thin film transistor of the first substrate. In the above, as a base layer of the reflective electrode, a layer formed unevenly by etching after film formation is used, and a plurality of types of layers having different height differences using a layer formed at the time of manufacturing the thin film transistor. A reflection type liquid crystal display device characterized by forming irregularities. 3. The reflection type liquid crystal display device according to claim 1, wherein the underlayer has a protrusion in which a conductive layer is covered with an insulating layer.