JP2003005211A - Semitransparent active element array substrate and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semitransparent active element array substrate having a high reflection efficiency and its manufacturing method. SOLUTION: The semiconductor active element array substrate is provided with a transparent substrate 11, a gate electrode 12 formed on the transparent substrate 11, semiconductor layers 14 and 15 which are formed on the gate electrode 12 through a gate insulating film 13, a source electrode 17 and a drain electrode 18 which are formed on the semiconductor layer 15, inter-layer insulating films 20 and 21 which cover the source electrode 17 and the drain electrode 18, and a pixel electrode 22 which is formed on the inter-layer insulating film 21 and is electrically connected to the drain electrode 18. In this semitransparent active element array substrate, a plurality of projecting parts 16 are formed on the gate electrode 12 through the gate insulating film 13 so as to overlap the pixel electrode 22, and a reflection layer 19 is formed which covers the projecting parts 16 and is covered with the inter-layer insulating film 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active element array substrate used in a transflective liquid crystal display device and a method for manufacturing the same.

[0002]

2. Description of the Related Art Liquid crystal display devices are widely used as main display devices, mainly for applications requiring small size and light weight. In particular, the semi-transmissive liquid crystal display device has low power consumption and good outdoor visibility, so that the demand as a display device for a mobile device is rapidly increasing.

The transflective liquid crystal display device displays by reflecting external light in a bright environment where natural light or indoor lighting exists, and displays by transmitting a backlight light in a dark environment. Is.

FIG. 4 is a sectional view showing the structure of an active element array substrate constituting such a transflective liquid crystal display device. A gate electrode 22 is formed on the transparent substrate 21, and a channel layer 24 is formed on the gate electrode 22 via a gate insulating film 23. A source electrode 27 and a drain electrode 28 are formed on the channel layer 24 via a contact layer 25. Furthermore, the source electrode 2
A protective insulating film 30 and an organic insulating film 31 are formed so as to cover 7 and the drain electrode 28. A transparent pixel electrode 32 is formed on the organic insulating film 31, and is electrically connected to the drain electrode 28 via a contact hole. Furthermore, a reflective layer 29 is formed on a part of the transparent pixel electrode 32. By using such an active element array substrate, display is performed by reflecting external light with a reflective layer in a bright environment, and backlight light is transmitted from a portion where the reflective layer of the transparent pixel electrode does not exist in a dark environment. By doing so, it becomes possible to display.

[0005]

However, in the conventional transflective active element array substrate described above, since the reflection layer is a flat surface, the specular reflection component increases when external light is reflected by the reflection layer, There is a problem that good diffuse reflection performance cannot be obtained. In order to solve this problem, in the conventional transflective active element array substrate, it is necessary to stack a transflective plate on the back surface of the transparent substrate when constructing a liquid crystal display device. As a result, the number of parts that make up the liquid crystal display device increases, and the structure becomes complicated, which makes it difficult to reduce the size of the liquid crystal display device.

It is an object of the present invention to provide a semi-transmissive active element array substrate which has a high reflection efficiency and can be miniaturized when used in a liquid crystal display device, and a manufacturing method thereof. To do.

[0007]

To achieve the above object, a semi-transmissive active element array substrate of the present invention comprises a transparent substrate and a gate electrode formed on the transparent substrate.
A semiconductor layer formed on the gate electrode via a gate insulating film, a source electrode and a drain electrode formed on the semiconductor layer, an interlayer insulating film covering the source electrode and the drain electrode, and the interlayer. An active element array substrate formed on an insulating film, comprising: a pixel electrode electrically connected to the drain electrode, further comprising:
A plurality of convex portions formed on the gate electrode via the gate insulating film so as to overlap a part of the pixel electrode, and reflection that covers the convex portions and is covered by the interlayer insulating film. And a layer.

According to such a semi-transmissive active element array substrate, since the reflective layer is formed so as to cover the plurality of convex portions, irregularities are formed on the surface of the reflective layer. As a result, the reflection efficiency in the reflective layer can be improved. Therefore, when a liquid crystal display device is configured using this semi-transmissive active element array substrate, it is not necessary to stack components such as a semi-transmissive reflection plate, so that the liquid crystal display device can be downsized.

In the semi-transmissive active element array substrate, it is preferable that the convex portion and the semiconductor layer are made of the same material. According to this preferable example, since the convex portion and the semiconductor layer can be formed in the same film forming step and patterning step, the manufacturing thereof becomes easy.

In the semi-transmissive active element array substrate, it is preferable that the reflective layer and the source electrode and the drain electrode are made of the same material. According to this preferable example, the reflective layer and the source electrode and the drain electrode can be formed in the same film forming step and patterning step, so that the manufacturing thereof becomes easy.

In the semi-transmissive active element array substrate, it is preferable that the source electrode, the drain electrode and the reflective layer contain at least one selected from the group consisting of Cr, Al and Ag. This is because the reflection efficiency can be further improved.

In order to achieve the above object, a method of manufacturing a semi-transmissive active device array substrate according to the present invention comprises a step of forming a gate electrode on a transparent substrate and a step of covering the gate electrode with a gate insulating film. A step of forming a semiconductor film, a step of forming a semiconductor layer and a plurality of convex portions by patterning the semiconductor film, and a step of forming a conductive film so as to cover the semiconductor layer and the convex portion. Forming a source electrode and a drain electrode on the semiconductor layer by patterning the conductive film,
A step of forming a reflective layer on the convex portion, a step of forming an interlayer insulating film so as to cover the source electrode, the drain electrode and the reflective layer, and on the interlayer insulating film,
And a step of forming a pixel electrode electrically connected to the drain electrode so that a part of the pixel electrode overlaps the convex portion and the reflective layer.

According to such a manufacturing method, the semi-transmissive active element array substrate of the present invention can be manufactured without impairing the production efficiency.

In the above manufacturing method, the conductive film is
It is preferable to contain at least one selected from the group consisting of Cr, Al and Ag. This is because a semi-transmissive active element array substrate having higher reflection efficiency can be manufactured.

[0015]

1 is a sectional view showing an example of the structure of a semi-transmissive active element array substrate according to the present invention.

In this semi-transmissive active element array substrate, a plurality of pixels are arranged. Each pixel includes an active element formed on a transparent substrate and a pixel electrode electrically connected to the active element. Further, a reflective portion 42 for reflecting external light and a transmissive portion 41 for transmitting backlight light are present in the area where the pixel electrode of each pixel is formed.

A thin film transistor (hereinafter referred to as "TFT") can be used as the active element. Although the structure of the TFT is not particularly limited, for example, the channel layer 14 is formed on the gate electrode 12 via the gate insulating film 13, and the source layer is formed on the channel layer 14 via the contact layer 15. A structure in which the electrode 17 and the drain electrode 18 are formed can be adopted.

Further, in the area which becomes the reflecting portion 42,
A plurality of protrusions 16 are formed on the gate electrode 12 with the gate insulating film 13 interposed therebetween. In the present embodiment, the convex portion 16 is formed by the first layer 16a and the second layer 16b. The first layer 16a and the second layer 16b are the channel layer 14 and the contact layer 1 of the TFT, respectively.
5 and the same material, for example, silicon. Furthermore, the first layer 16a and the second layer 16
b is preferably formed by the same film forming process and patterning process as the channel layer 14 and the contact layer 15 of the TFT, respectively.

The shape of the convex portion 16 is not particularly limited, but may be, for example, a cylindrical shape.
The width (W) of the convex portion 16 is, for example, 1 to 30 μm, preferably 3 to 10 μm. The layer thickness is preferably equal to the total layer thickness of the channel layer and contact layer of the TFT, and is, for example, 100 to 2000 nm, preferably 3
It is 00-800 nm. Moreover, the array of the convex portions 16 may be irregular or regular. In addition, the convex portion 16
The distance (D) between them can be, for example, 0.1 to 30 μm, preferably 1 to 10 μm.

A reflective layer 19 is formed so as to cover the convex portion 16. The reflective layer 19 is made of the same material as the source electrode 17 and the drain electrode 118 of the TFT, and is made of, for example, Cr, Al, Ag and alloys thereof. Furthermore, the reflective layer 19 is preferably formed by the same film forming process and patterning process as the source electrode 17 and the drain electrode 18.

The layer thickness of the reflective layer 19 is preferably equal to the layer thickness of the source electrode 17 and the drain electrode 18 of the TFT, for example, 50 to 1000 nm, preferably 10 nm.
It is 0 to 500 nm.

A protective insulating film 20 and an organic insulating film 21 are formed so as to cover the TFT and the reflective layer 19. A transparent pixel electrode 22 is formed on the organic insulating film 21, and the electrode 22 is electrically connected to the drain electrode 18 of the TFT via a contact hole.
The transparent pixel electrode 21 is arranged so that a part thereof overlaps the convex portion 16 and the reflective layer 19, and that portion becomes a reflective portion 42 and the other portion becomes a transmissive portion 41.

Next, an example of a method of manufacturing the semi-transmissive active element array substrate according to the present invention will be described. Figure 2
FIG. 6A is a cross-sectional view for explaining an example of the method for manufacturing the semi-transmissive active element array substrate. In addition, FIG.
It is the same top view.

First, the gate electrode 12 is formed on the transparent substrate 11.
Are formed (FIGS. 2A and 3A). Transparent substrate 11
For example, a glass substrate can be used. As the gate electrode 12, for example, Cr, Al, A
1 alloy, Ag or Ag alloy can be used, and as a method for forming the same, for example, a method of forming a film of a gate electrode material by a sputtering method and then patterning it by photolithography and etching can be adopted. The film thickness of the gate electrode 12 is not particularly limited, but is, for example, 50 to 10
00 nm.

Then, a gate insulating film 13 is formed so as to cover the gate electrode 12. As the gate insulating film 13, for example, a silicon nitride film can be used, and as its forming method, for example, a plasma chemical vapor deposition method (hereinafter, referred to as “p-CVD method”) can be adopted. it can. The thickness of the gate insulating film 13 is, for example, 10
~ 1000 nm.

A first semiconductor film and a second semiconductor film are formed on the gate insulating film 13. As the first semiconductor film, for example, amorphous silicon can be used, and the film thickness thereof is, for example, 50 to 500 nm, preferably 100 to 300 nm. Further, as the second semiconductor film, for example, phosphorus-doped low resistance amorphous silicon can be used, and the film thickness thereof is, for example, 5 to 2
00 nm, preferably 10 to 100 nm. Also,
As a method of forming these semiconductor films, for example, pC
The VD method can be adopted.

Subsequently, the first and second semiconductor films are patterned to form the channel layer 14 and the contact layer 15 in the region where the TFT is formed, and the reflection portion 4 is formed.
The convex portion 16 including the first layer 16a and the second layer 16b is formed in the region to be 2 (FIGS. 2B and 3B).
Thus, the channel layer 14 and the contact layer 15
And the convex portion 16 are formed by the same film forming process and patterning process. In addition, this patterning
For example, it can be performed by photolithography and etching.

A conductive film is formed so as to cover the channel layer 14 and the contact layer 15 of the TFT and the convex portion 16. As the conductive film, for example, Cr, Al, Al alloy, Ag, Ag alloy, or the like can be used, and as a forming method thereof, for example, a sputtering method can be adopted. The film thickness of the conductive film is, for example, 50 to 1
It is 000 nm, preferably 100 to 500 nm.

Subsequently, the conductive film is patterned to source electrode 1 so as to cover contact layer 15.
7 and the drain electrode 18, and the reflective layer 19 is formed so as to cover the convex portion 16 (FIG. 2C and FIG. 3).
(C)). In this way, the source electrode 17 and the drain electrode 18 and the reflective layer 19 are formed by the same film forming process and patterning process. In addition, this patterning can be implemented by photolithography and etching, for example.

A protective insulating film 20 is formed so as to cover the source electrode 17, the drain electrode 18 and the reflective layer 19, and a contact hole 20a is formed therein (FIG. 2).
(D), FIG. 3 (d)). As the protective insulating film 20, for example, a silicon nitride film can be used, and as a method for forming the protective insulating film 20, for example, a p-CVD method can be adopted. The thickness of the protective insulating film 20 is, for example, 10 to 1000.
nm. The contact hole 20a is formed by
For example, it can be performed by etching.

An organic insulating film 21 is formed on the protective insulating film 20. The organic insulating film 21 can be formed, for example, by applying a photosensitive resin such as an acrylic resin. The film thickness of the organic insulating film 21 is, for example, 0.5 to 10 μm.
Is. After that, the opening 21b and the contact hole 21a are formed in the organic insulating film 21 (FIG. 2E, FIG.
(E)). The opening 21b is formed in a portion corresponding to the transmissive portion 41, and the contact hole 21a has at least T.
It is formed on the drain electrode 18 of the FT. Opening 21b
The contact hole 21a can be formed by photolithography, for example, when a photosensitive resin is used as the organic insulating film 21.

Next, the transparent pixel electrode 22 is formed on the organic insulating film 21 (FIG. 2 (f), FIG. 3 (f)). The transparent pixel electrode 22 is formed so that a part thereof overlaps the reflective layer 19, and is electrically connected to the drain electrode 18 and the reflective layer 19 via a contact hole. As the transparent pixel electrode 22, for example, indium tin oxide (I
TO) can be used, and as a forming method thereof,
For example, a method of patterning by photolithography and etching after forming a film by a sputtering method can be adopted.

[0033]

As described above, according to the semi-transmissive active element array substrate of the present invention, a plurality of convex portions are formed on the transparent substrate and the reflective layer is formed so as to cover the convex portions. Therefore, unevenness is formed on the surface of the reflective layer, and as a result, a semi-transmissive active element array substrate having high reflection efficiency can be obtained.

Further, according to the manufacturing method of the present invention, the convex portion and the semiconductor layer are formed by the same film forming step and the patterning step, and the reflective layer and the source electrode and the drain electrode are formed by the same film forming step and the patterning step. Since it is formed by steps, a semi-transmissive active element array substrate having high reflection efficiency can be manufactured without impairing production efficiency.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a semi-transmissive active element array substrate according to the present invention.

FIG. 2 is a process sectional view showing an example of a method of manufacturing a semi-transmissive active element array substrate according to the present invention.

FIG. 3 is a process plan view showing an example of a method of manufacturing a semi-transmissive active element array substrate according to the present invention.

FIG. 4 is a cross-sectional view showing a conventional transflective active device array substrate.

[Explanation of symbols]

11, 21 Transparent substrate 12, 22 Gate electrode 13, 23 Gate insulating film 14, 24 Channel layer 15, 25 Contact layer 16 convex 17, 27 Source electrode 18, 28 Drain electrode 19, 29 Reflective layer 20, 30 Protective insulation film 21, 31 Organic insulating film 22, 32 Transparent pixel electrode

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Nobuyuki Tsuboi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 2H092 JA26 JA34 JA37 JA41 JA46                       JB07 JB57 JB58 KA05 KA10                       KA12 KA18 MA08 MA13 MA18                       NA25 NA27 NA29                 5C094 AA07 BA03 CA19 DA14 DA15                       DB04 EA04 EA06 EA07 EB02                       ED11 FB12 FB14 FB15                 5F110 AA30 BB01 CC07 DD02 EE02                       EE03 EE04 EE06 EE44 FF03                       FF30 GG02 GG15 GG24 GG45                       HK02 HK03 HK04 HK06 HK09                       HK16 HK21 HK25 HK33 HK35                       HL07 HL23 NN03 NN04 NN24                       NN27 NN35 NN36 NN72

Claims (6)

[Claims] 1. A transparent substrate, a gate electrode formed on the transparent substrate, a semiconductor layer formed on the gate electrode via a gate insulating film, a source electrode formed on the semiconductor layer, and An active element array substrate including a drain electrode, an interlayer insulating film covering the source electrode and the drain electrode, and a pixel electrode formed on the interlayer insulating film and electrically connected to the drain electrode. Further, a plurality of convex portions formed on the gate electrode via the gate insulating film so as to overlap a part of the pixel electrode and the convex portion are covered, and by the interlayer insulating film. A transflective active element array substrate, comprising: a coated reflective layer. 2. The semi-transmissive active element array substrate according to claim 1, wherein the convex portion and the semiconductor layer are formed of the same material. 3. The semi-transmissive active element array substrate according to claim 1, wherein the reflective layer and the source electrode and the drain electrode are formed of the same material. 4. The semi-transmissive active element according to claim 1, wherein the source electrode, the drain electrode and the reflective layer include at least one selected from the group consisting of Cr, Al and Ag. Array substrate. 5. A semiconductor layer is formed by forming a gate electrode on a transparent substrate, forming a semiconductor film so as to cover the gate electrode with a gate insulating film interposed therebetween, and patterning the semiconductor film. And a step of forming a plurality of convex portions, a step of forming a conductive film so as to cover the semiconductor layer and the convex portion, and patterning the conductive film to form a source electrode and a drain electrode on the semiconductor layer. A step of forming a reflective layer on the convex portion, a step of forming an interlayer insulating film so as to cover the source electrode, the drain electrode and the reflective layer, and the step of forming an interlayer insulating film on the interlayer insulating film. And a step of forming a pixel electrode electrically connected to the drain electrode so that a part of the pixel electrode overlaps the convex portion and the reflective layer. Method for manufacturing active element array substrate. 6. The method for manufacturing a semi-transmissive active element array substrate according to claim 5, wherein the conductive film contains at least one selected from the group consisting of Cr, Al and Ag.