JP2002229049A - Liquid crystal display and method of manufacturing for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display of a translucent type, which minimizes the degradation in production efficiency and has no concern for impairing the contact characteristics between pixel electrodes and drain electrodes, and to provide a method of manufacturing the same. SOLUTION: This liquid crystal display has liquid crystals pinched between two sheets of substrates, has active element arrays on one substrate of two sheets of the substrates, has the pixel electrodes on each of the active element arrays and displays images by driving the liquid crystals across the pixel electrodes; the pixel electrodes have a laminated structure consisting of a least two layers; a transparent electrode layer and a translucent electrode layer; and the transparent electrode layer and the translucent electrode layer are molded simultaneously by one-time photoresist working, using the same resist mask.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device used for an information processing terminal or a video device and a method of manufacturing the same. In particular, the present invention relates to a transflective liquid crystal display device using both incident light and transmitted light, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, information terminal equipment which emphasizes portability has been rapidly developed, as seen in higher performance of mobile phones and the like accompanying personalization of information. Important points for ensuring such portability include long-time operation and reduction in thickness and weight of the battery. However, there is a dilemma that driving for a long time requires a large battery, which is contrary to thinning and weight reduction.To solve this problem, use a backlight in a dark environment and reflect ambient light in a bright environment. Accordingly, a transflective liquid crystal display device capable of performing display without a backlight has attracted attention.

FIG. 3 is a sectional view of a conventional transflective liquid crystal display device and a method of manufacturing the same. In FIG. 3, 1 is a substrate, 2 is a thin film transistor (Thin Film Transistor).
r; hereinafter referred to as “TFT”. ), 3 is a gate insulating film for forming a TFT, and 4 is a TFT.
, A contact layer 5 for forming a TFT, a source electrode 6 for forming a TFT, and a drain electrode 7 for forming a TFT. Reference numeral 8 denotes an interlayer insulating film having a contact hole 8a and an uneven portion 8b, and reference numerals 9 and 10 denote a transmission electrode and a reflection electrode constituting a pixel electrode, respectively.

[0004] First, after a gate electrode 2 is patterned on a substrate 1, a gate insulating film 3 covering the entire surface, a channel layer 4 near the gate insulating film 3 on the gate electrode 2, and further on both ends of the channel layer 4. The TFT array is formed by overlapping the low-resistance contact layer 5 with the source electrode 6 and the drain electrode 7.

Next, an interlayer insulating film 8 having a contact hole 8a on the drain electrode 7 and an uneven portion 8b and made of an organic resin film is formed. Indium tin oxide (hereinafter referred to as "ITO") is used as a transmission electrode material.
That. Is formed, a transmission electrode 9 is formed by photolithography.

Next, after a film of Al is formed as a reflective electrode material, the film is connected to the drain electrode 7 through the contact hole 8a by photolithography, and is connected to the transmission electrode 9 having an uneven shape on the uneven portion 8b. By forming the reflective electrode 10, an active element array substrate as shown in FIG. 3 can be obtained. Further, a substrate having a color filter and a transparent electrode is attached to face the active element array substrate, and liquid crystal is sealed between the two substrates to complete a liquid crystal display device.

As described above, there are two types of the pixel electrode, the reflective electrode 10 having a function as a reflective plate for reflecting ambient light and the transmissive electrode 9 having a function as a transmissive plate for transmitting light from a backlight. By using a pixel electrode composed of an electrode, a transflective liquid crystal display device in which both the reflection characteristics and the transmission characteristics are optimized can be obtained. Therefore, it is possible to obtain a liquid crystal display device having excellent visibility in both a dark environment and a bright environment.

[0008]

However, in the conventional liquid crystal display device and the method of manufacturing the same as described above, in the formation of the pixel electrode, the formation of the transmission electrode 9 and the formation of the reflection electrode
And two steps are required. This causes a fear that the drain electrode 7 at the contact hole 8a is damaged when the transmission electrode 9 is formed by photolithography, and that the contact property between the reflection electrode 10 and the drain electrode 7 formed in the next step is impaired. It will be. In addition, an increase in the number of pixel electrode forming steps causes a decrease in production efficiency.

The present invention has been made in view of the above problems, and provides a transflective liquid crystal display device which minimizes a decrease in production efficiency and has no fear of impairing contact between a pixel electrode and a drain electrode, and a method of manufacturing the same. The purpose is to.

[0010]

In order to achieve the above object, a liquid crystal display device according to the present invention has a liquid crystal sandwiched between two substrates and has an active liquid crystal on one of the two substrates. What is claimed is: 1. A liquid crystal display device comprising: an element array; a pixel electrode in each of the active element arrays; and a liquid crystal display device for displaying an image by driving a liquid crystal through the pixel electrode. A transparent electrode layer and a semi-transmissive electrode layer are simultaneously formed by one photoresist processing using the same resist mask.

With this configuration, the transparent electrode layer and the semi-transmissive electrode layer can be simultaneously molded in a single molding step, so that a decrease in production efficiency can be minimized.
However, since the drain electrode is not exposed in the element electrode forming process, the drain electrode is not likely to be damaged, and there is no concern that the contact property between the pixel electrode and the drain electrode is impaired.

Further, in the liquid crystal display device according to the present invention, the semi-transmissive electrode layer has a thickness of 20 nm or less.
g or an Ag alloy. This is because a pixel electrode having a high transmittance and a desired transmittance can be obtained.

Further, in the liquid crystal display device according to the present invention, the transparent electrode layer is preferably made of indium tin oxide. This is because a transparent electrode layer with low resistance and transparency can be obtained.

Next, in order to achieve the above object, a method of manufacturing a liquid crystal display device according to the present invention comprises providing a liquid crystal sandwiched between two substrates, providing an active element on one of the two substrates. A method of manufacturing a liquid crystal display device, wherein an array is provided, a pixel electrode is provided in each of the active element arrays, and an image is displayed by driving a liquid crystal through the pixel electrodes, wherein the active elements are formed in an array on a substrate. Forming an interlayer insulating film having a contact hole and a concavo-convex shape on the electrode of the active element; forming a transparent first pixel electrode layer on the entire surface;
Forming a pixel electrode layer, applying a photosensitive resist to the entire surface, forming a resist mask by exposure and development, and selecting a first pixel electrode layer and a second pixel electrode layer using the resist mask. An etching step, removing the resist mask, forming a laminated structure of a transparent electrode layer composed of a first pixel electrode layer and a semi-transmissive electrode layer composed of a second pixel electrode layer, and forming an active element through a contact hole. Forming a pixel electrode electrically connected to the electrode.

With this configuration, the transparent electrode layer and the semi-transmissive electrode layer can be simultaneously molded in one molding step, so that a decrease in production efficiency can be suppressed to a minimum.
However, since the drain electrode is not exposed in the element electrode forming process, the drain electrode is not likely to be damaged, and there is no concern that the contact property between the pixel electrode and the drain electrode is impaired.

Next, in order to achieve the above object, in a method of manufacturing a liquid crystal display device according to the present invention, a liquid crystal sandwiched between two substrates is provided, and an active element is provided on one of the two substrates. A method of manufacturing a liquid crystal display device, wherein an array is provided, a pixel electrode is provided in each of the active element arrays, and an image is displayed by driving a liquid crystal through the pixel electrodes, wherein the active elements are formed in an array on a substrate. Forming an interlayer insulating film having a contact hole and a concavo-convex shape on an electrode of the active element; forming a semi-transparent first pixel electrode layer on the entire surface; and forming a transparent second pixel electrode Forming a layer, applying a photosensitive resist over the entire surface, forming a resist mask by exposure and development, and using the resist mask to form a first pixel electrode layer and a second pixel electrode. And a resist mask is removed, and a stacked structure of a semi-transmissive electrode layer composed of a first pixel electrode layer and a transparent electrode layer composed of a second pixel electrode layer is formed. Forming a pixel electrode electrically connected to the first electrode.

With this configuration, the transparent electrode layer and the semi-transmissive electrode layer can be simultaneously molded in a single molding step, so that a reduction in production efficiency can be suppressed to a minimum.
However, since the drain electrode is not exposed in the element electrode forming process, the drain electrode is not likely to be damaged, and there is no concern that the contact property between the pixel electrode and the drain electrode is impaired.

Further, according to the method of manufacturing a liquid crystal display device according to the present invention, the transflective pixel electrode layer has an A thickness of 20 nm or less.
1, Al alloy, Ag, or Ag alloy. This is because a pixel electrode having a high transmittance and a desired transmittance can be obtained.

In the method of manufacturing a liquid crystal display according to the present invention, it is preferable that the transparent pixel electrode layer is made of indium tin oxide. This is because a transparent electrode layer with low resistance and transparency can be obtained.

In the method of manufacturing a liquid crystal display device according to the present invention, it is preferable that the interlayer insulating film is an organic film. This is because a thick interlayer insulating film can be easily formed.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal display according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a pixel portion in an active element array of a transflective liquid crystal display device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view in each manufacturing process.

1 and 2, reference numeral 20 denotes an opening 2
0a, a reference numeral 23 denotes a pixel electrode formed by laminating a first pixel electrode layer 21 and a second pixel electrode layer 22 formed on the interlayer insulating film 8; Here, the same components as those of the liquid crystal display device shown in FIG. 3 as a conventional example and the method of manufacturing the same are given the same numbers and the same names, and detailed explanations are omitted.

First, a 100/200/100 nm layer of Ti / Al / Ti is formed on a glass substrate 1 by sputtering using Ar gas to form a film. Next, S is formed by plasma enhanced chemical vapor deposition (hereinafter, referred to as “p-CVD”).
After forming three layers of iNx, a-Si and low-resistance a-Si,
The a-Si and the low-resistance a-Si other than the TFT region are removed by etching to form the island-like channel layer 4 and the contact layer 5 and the gate insulating film 3 over the entire surface.

Next, Ti / Al / Ti were respectively reduced to 100/200 by a sputtering method using Ar gas again.
After forming a film with a thickness of / 100 nm, it is processed into a pattern of the source electrode 6 and the drain electrode 7 of the TFT. At this time, the contact layer 5 is formed separately in the source and drain regions.

Then, as shown in FIG.
SiNx as a protective film of the channel layer 4 by the CVD method
By forming the protective film 20 made of, a TFT array is obtained.

Further, as shown in FIG. 2B, an opening 20a is formed on the drain electrode 7 by processing the protective film 20 using a resist as a mask. Then, as shown in FIG. 2 (c), a photosensitive acrylic resin (PC made by JSR)
305) is applied by about 3 μm, and an interlayer insulating film 8 having a contact hole 8a and an uneven portion 8b in the opening 20a is formed by exposure and development.

Next, as shown in FIG. 2D, a 100 nm thick ITO film is formed as the first pixel electrode layer 21 and then a 15 nm thick Al film is formed as the second pixel electrode layer 22. Then, as shown in FIG. 2E, after forming a resist mask having a pixel electrode pattern, the second pixel electrode layer 22 is processed with a phosphoric acid-based etchant using the resist mask, and then the same mask is formed. The first pixel electrode layer 22 is processed with an oxalic acid-based etchant using
Form 3 Then, the active element array can be obtained by removing the resist mask.

Further, a liquid crystal display device is completed by bonding a color filter and a counter substrate having a transparent electrode to a substrate having an active element array obtained in the same manner as in the conventional example, and sealing a liquid crystal between the substrates. I do.

With the above-described manufacturing process, the pixel electrode 23 is made of a first pixel electrode layer 21 made of ITO as a transparent electrode layer and a thin Al
Since the pixel electrode is formed by lamination with the second pixel electrode layer 22, the pixel electrode can be processed by a single photomask formation, so that a reduction in production efficiency can be minimized. Further, since the drain electrode 7 is not exposed in the pixel electrode processing step, the drain electrode 7 is not likely to be damaged by the photomask processing in the pixel electrode forming step, and the contact property between the drain electrode 7 and the pixel electrode is impaired. A transflective liquid crystal display device without concern can be obtained.

In the above description, ITO is used as the first pixel electrode layer 21 and Al is used as the second pixel electrode layer 22.
Is used as the pixel electrode 23 having a stacked structure, but the first pixel electrode layer 21 and the second pixel electrode layer 22 are not particularly limited as long as they are a combination of a transparent electrode layer and a semi-transmissive electrode layer. . That is, the first pixel electrode layer 21 is formed to have a thickness of 15 nm using the first pixel electrode layer 21 as a transflective electrode layer, and then the ITO is formed to have a thickness of 100 nm using the second pixel electrode layer 22 as a transparent electrode layer. The electrode layer 21 and the second pixel electrode layer 22 may have opposite configurations.

In this case, after a resist mask having a pixel electrode pattern is formed, a second mask is formed using the resist mask.
Is processed with an oxalic acid-based etchant,
Subsequently, the pixel electrode 23 is formed by processing the first pixel electrode layer 22 with a phosphoric acid-based etchant using the same mask.

Further, 15n of Al is used as a semi-transmissive electrode layer.
m, but the transflective electrode layer is not particularly limited as long as it has high reflection efficiency and low resistance.
For example, AlTi, AlTa, AlW, A
1Nd, AlZr, etc., or Ag or AgC as Ag alloy
u, AgPdCu, AgTiCu or the like.

The thickness depends on the brightness design of the liquid crystal display device including the backlight. However, since the transflective electrode layer needs to have a transmittance of 10% or more, the thickness is 20 n.
m or less, and is not particularly limited to 15 nm. Further, although the active element is formed of a TFT, it is apparent that a non-linear two-terminal element such as MIM may be used.

The liquid crystal display device as described above can be applied to various types of image display application devices, and it goes without saying that similar effects can be expected in each image display application device.

As described above, according to the present embodiment, since the pixel electrode 23 has a laminated structure of the transparent electrode layer and the semi-transmissive electrode layer, the pixel electrode 23 can be processed by a single photomask formation. It is possible to minimize the decrease.

Further, since the drain electrode 7 is not exposed during the processing of the pixel electrode, a good contact property between the pixel electrode 23 and the drain electrode 7 is ensured.
It is possible to obtain a transflective liquid crystal display device with less occurrence of defects due to contact failure.

[0037]

As described above, according to the method of manufacturing a liquid crystal display device according to the present invention, the pixel electrode has a laminated structure of a transparent electrode layer and a semi-transmissive electrode layer, so that a single photomask can be formed. Since processing can be performed, it is possible to minimize a decrease in production efficiency.

Further, according to the method of manufacturing a liquid crystal display device according to the present invention, since the drain electrode is not exposed during the processing of the pixel electrode, good contact between the pixel electrode and the drain electrode can be ensured. In addition, it is possible to obtain a semi-transmissive liquid crystal display device with less occurrence of defects due to contact failure.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a pixel portion of an active element array in a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is an explanatory sectional view of a method for manufacturing a liquid crystal display device according to an embodiment of the present invention.

FIG. 3 is a sectional view showing a pixel portion of an active element array in a conventional liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Gate electrode 3 Gate insulating film 4 Channel layer 5 Contact layer 6 Source electrode 7 Drain electrode 8 Interlayer insulating film 8a Contact hole 8b Concavo-convex part 9 Transmissive electrode 10 Reflective electrode 20 Protective film 21 First pixel electrode layer 22 Second Pixel electrode layer of 23 Pixel electrode

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 29/786 H01L 29/78 612D 21/336 616K 619A (72) Inventor Nobuyuki Tsuboi Okadoma, Kadoma-shi, Osaka 1006 Matsushita Electric Industrial Co., Ltd.F-term (reference) MM05 PP15 QQ08 QQ09 QQ10 QQ19 QQ21 QQ37 RR06 SS15 VV15 WW02 XX09 XX33 5F110 AA16 AA26 CC07 DD02 EE03 EE04 EE15 EE44 FF03 FF30 GG02 NN15 HG45 HK03 HK04 HK03 HK16 HK24

Claims (9)

[Claims] 1. A liquid crystal sandwiched between two substrates, one of the two substrates has an active element array, and each of the active element arrays has a pixel electrode, A liquid crystal display device that displays an image by driving the liquid crystal through the pixel electrode, wherein the pixel electrode has a laminated structure including at least two layers of a transparent electrode layer and a transflective electrode layer, Wherein the transparent electrode layer and the semi-transmissive electrode layer are simultaneously formed by a single photoresist process using the resist mask. 2. The liquid crystal display device according to claim 1, wherein the semi-transmissive electrode layer is any one of Al, Al alloy, Ag, and Ag alloy having a thickness of 20 nm or less. 3. The liquid crystal display device according to claim 1, wherein said transparent electrode layer is made of indium tin oxide. 4. A liquid crystal sandwiched between two substrates is provided; an active element array is provided on one of the two substrates; a pixel electrode is provided on each of the active element arrays; A method of manufacturing a liquid crystal display device that displays an image by driving the liquid crystal through the device, comprising: forming active elements in an array on a substrate; and forming contact holes and irregularities on the electrodes of the active elements. Forming an interlayer insulating film having a shape; forming a transparent first pixel electrode layer on the entire surface; forming a semi-transparent second pixel electrode layer; and applying a photosensitive resist on the entire surface Forming a resist mask by exposure and development; and selectively etching the first pixel electrode layer and the second pixel electrode layer using the resist mask; The resist mask is removed, and a laminated structure of a transparent electrode layer made of the first pixel electrode layer and a semi-transmissive electrode layer made of the second pixel electrode layer is formed. The electrode of the active element is formed through the contact hole. Forming a pixel electrode electrically connected to the liquid crystal display device. 5. A liquid crystal sandwiched between two substrates, an active element array provided on one of the two substrates, a pixel electrode provided on each of the active element arrays, A method of manufacturing a liquid crystal display device that displays an image by driving the liquid crystal through the device, comprising: forming an active element in an array on a substrate; and forming a contact hole and a concavo-convex shape on an electrode of the active element. Forming a semi-transmissive first pixel electrode layer over the entire surface, forming a transparent second pixel electrode layer over the entire surface, and applying a photosensitive resist over the entire surface. Forming a resist mask by exposure and development; and selectively etching the first pixel electrode layer and the second pixel electrode layer using the resist mask; The resist mask is removed, and has a laminated structure of a semi-transmissive electrode layer composed of the first pixel electrode layer and a transparent electrode layer composed of the second pixel electrode layer, and is provided with an electrode of the active element through the contact hole. Forming an electrically connected pixel electrode. 6. The method according to claim 1, wherein the translucent pixel electrode layer has a thickness of 20 nm.
The method for manufacturing a liquid crystal display device according to claim 4, wherein the method is any of the following Al, an Al alloy, Ag, and an Ag alloy. 7. The method according to claim 4, wherein the transparent pixel electrode layer is made of indium tin oxide. 8. The method according to claim 4, wherein the interlayer insulating film is an organic film.
6. The method for manufacturing a liquid crystal display device according to item 5. 9. An image display application device comprising the liquid crystal display device according to claim 1. Description: