KR20070030708A - Liquid crystal display device and method for manufacturing the same - Google Patents

Abstract

An object of the present invention is to provide a liquid crystal display device suitable for a relatively small pixel area or high precision, and a method of manufacturing the same, in which the capacitance of the storage capacitor electrode is increased without reducing the aperture ratio of each pixel. A plurality of signal lines 17 and scan lines arranged in a matrix on the transparent substrate 11, a plurality of storage capacitor lines provided in parallel between the scan lines, thin film transistor TFTs provided near the intersections of the signal lines and the scan lines, and the signal lines 17. And a pixel electrode 20 arranged at each position partitioned by a scanning line and electrically connected to the drain electrode D of the thin film transistor TFT, wherein the gate electrode G of the thin film transistor TFT is provided. And the scanning line is covered with a gate insulating film composed of the insulating film 5 of the first layer and the insulating layer 26 of the second layer, with the insulating layer 26 of the second layer interposed on the storage capacitor electrode 18a. The drain electrode D of the thin film transistor TFT is extended.

Description

Liquid crystal display and its manufacturing method {LIQUID CRYSTAL DISPLAY DEVICE AND METHOD FOR MANUFACTURING THE SAME}

1 is an enlarged plan view of a portion corresponding to one pixel of the liquid crystal display device according to the first embodiment and through a color filter substrate;

FIG. 2 is a side sectional view showing a state cut along line II-II of the liquid crystal display of FIG. 1; FIG.

3A to 3G are cross-sectional views illustrating a manufacturing process for manufacturing the array substrate of FIG. 1.

4A-4E are cross-sectional views illustrating a fabrication process for fabricating the array substrate of FIG. 1 following FIG. 3G.

5A to 5E are sectional views showing the manufacturing process for manufacturing the array substrate of Example 2. FIG.

6A to 6D are cross-sectional views illustrating a manufacturing process for manufacturing the array substrate of Example 2 following FIG. 5E.

7A to 7F are sectional views showing the manufacturing process for manufacturing the array substrate of Example 3. FIG.

8A to 8E are cross-sectional views illustrating a manufacturing process for manufacturing the array substrate of Example 3 following FIG. 7F.

9A is a plan view of an array substrate of a first conventional example, and FIG. 9B is a sectional view taken along line BB-B of FIG. 9A.

10 is a plan view of several pixels of the array substrate of the second conventional example;

11A to 11G are partial cross-sectional views sequentially illustrating a manufacturing process of the array substrate of FIG. 10.

<Description of Symbols for Main Parts of Drawings>

10, 10A, 10B liquid crystal display

11, 12 transparent substrate

13 array boards

14 color filter substrate

15 LCD

16 scan lines

17 signal line

18 auxiliary capacitance line

18a auxiliary capacitance electrode

19 semiconductor layer

20 pixel electrode

22 color filter

23 common electrode

24 conductive material layer

25 first insulating film

25 'insulating film

26 second insulating layer

26 'insulation layer

27 Window

28 protective insulating film

29 interlayer

30 contact holes

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a method for manufacturing the same, and particularly to a liquid crystal display device and a method for manufacturing the same, which are very suitable for a relatively small pixel area or high precision, in which the capacitance of the storage capacitor electrode is increased without reducing the aperture ratio of each pixel. It is about.

In recent years, liquid crystal displays have been widely used not only for information and communication devices but also for general electric devices. A liquid crystal display device comprises a substrate made of a pair of glass or the like having an electrode or the like formed on the surface thereof, and a liquid crystal layer formed between the pair of substrates, and the light transmittance by rearranging liquid crystal molecules by applying a voltage to an electrode on the substrate To display various images.

Such a liquid crystal display device forms a scan line and a signal line in a matrix form on its surface, and applies a voltage to a thin film transistor (TFT), a liquid crystal driving switching element, and a liquid crystal in a region surrounded by both wirings. An array substrate on which a pixel electrode and a storage capacitor line forming a storage capacitor for holding a signal are formed, and a color filter including red (R), green (G), and blue (B) and a common electrode formed on a surface thereof It consists of a filter board | substrate, and the structure which liquid crystal was enclosed between both board | substrates is provided.

The storage capacitor line formed on the array substrate is provided to form the storage capacitor that holds the charge of the signal supplied from the signal line for a predetermined period, and the storage capacitor is a portion of the storage capacitor line and the TFT electrode or the pixel electrode of the TFT as an electrode. The capacitor is formed by using a gate insulating film covering the gate electrode of the TFT as a dielectric. The storage capacitor line is generally formed of a light-shielding conductive member such as aluminum, molybdenum or chromium.

By the way, the auxiliary capacitance needs to be increased in terms of preventing crosstalk or flicker of the liquid crystal display device, but with the recent technological innovation, miniaturization and high precision of the liquid crystal display device have progressed. Since each pixel size is reduced by this, in consideration of the aperture ratio for each pixel, it is practically difficult to thicken the storage capacitor line itself in order to take more storage capacity.

As a solution to the above problems, the array substrate 70 of the liquid crystal display device disclosed in Patent Document 1 will be described with reference to FIG. 9 as follows. For reference, FIG. 9A is a plan view of the array substrate, and FIG. 9B is a sectional view taken along line BB-B of FIG. 9A.

The array substrate 70 of the liquid crystal display device includes a scan line made of conductive material such as aluminum, chromium, molybdenum, chromium nitride, molybdenum nitride, or an alloy thereof on the transparent insulating substrate 71 as shown in FIGS. 9A and 9B. 72, the storage capacitor line 73 and the rectangular storage capacitor pattern 74 are formed. The scanning line 72 is connected to the gate electrode G of the thin film transistor TFT, and the storage capacitor pattern 74 is connected to the storage capacitor line 73.

On the insulating substrate 71, a gate insulating film 75 having a thickness of 2500 to 4500 Å made of an insulating material such as silicon nitride or silicon oxide covers the long line 72, the storage capacitor line 73, and the storage capacitor pattern 74. A semiconductor pattern 76 made of amorphous silicon or the like is formed on the gate insulating film 75 so as to overlap with the gate electrode G. As shown in FIG. A signal line 77 made of a conductive material and a conductive pattern 78 for a storage capacitor are formed on a portion of the semiconductor pattern 76 and the gate insulating film 75. The signal line 77 extends in the vertical direction and serves as the source electrode S of the TFT.

The storage capacitor pattern 78 is formed in an island shape on the same layer as the signal line 77, and forms the storage capacitor together with the storage capacitor pattern 74 positioned below the gate insulating layer 75. do. At this time, the storage capacitor pattern 78 is electrically connected to the pixel electrode 79 described later.

The signal line 77, the storage capacitor conductive pattern 78, and the semiconductor pattern 76 are covered with a protective insulating film 80 having a thickness of 500 to 2000 μm made of an insulating material such as silicon nitride or silicon oxide. In the protective insulating film 80, a contact hole 81 is formed over the drain electrode D, and an opening 82 is provided over the storage capacitor conductive pattern 78. The pixel electrode 79 is formed on the protective insulating film 80, and the pixel electrode 79 and the drain electrode D are electrically connected to each other through the contact hole 81, and at the same time, a storage capacitor is formed through the opening 82. The conductive conductive pattern 78 and the pixel electrode 79 are connected, and as a result, the storage capacitor conductive pattern 78 and the drain electrode D are electrically connected through the pixel electrode 79. The pixel electrode 79 is formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO).

In the related art, the pixel electrode 79 overlaps the storage capacitor line 73 and the storage capacitor conductive pattern 78, but the protective insulating film 80 and the gate insulating film 75 overlap with the storage capacitor line 78. Is formed between the capacitor electrodes, and the pixel electrode 79 is electrically connected to the conductive pattern 78 for the storage capacitor, but the conductive pattern 78 for the storage capacitor is formed of the storage capacitor pattern 74 and the gate insulating film. Away from 75 to form another auxiliary dose. In this case, since the thickness of the gate insulating film 75 interposed between the storage capacitor conductive pattern 78 and the storage capacitor pattern 74 is thick, the storage capacitor pattern 74 is formed together with the pixel electrode 79. It is possible to secure a larger capacitance even with the same overlap area as compared with the case of forming a. Therefore, in the liquid crystal display device disclosed in Patent Document 1 as follows, the capacitance can be increased without increasing the area of the storage capacitor pattern 74 and the storage capacitor line 73, thereby improving the aperture ratio relative to the capacitance. I can do it.

However, in the array substrate 70 of the liquid crystal display device disclosed in Patent Literature 1 as follows, the capacitance (auxiliary capacitance) uses the auxiliary capacitance conductive pattern 78 and the auxiliary capacitance pattern 74 as electrodes, and Although the gate insulating film 75 provided between them is made into a dielectric material, the thickness of the gate insulating film 75 is considered to be thin. However, since the thickness of the gate insulating film 75 is 2500 to 4500 kV, crosstalk, flicker, etc. In order to ensure a sufficient storage capacity for suppressing display defects, the area of the storage capacitor pattern 74, which is also made of a light-shielding conductive material, must be increased. That is, in the array substrate 70 of the liquid crystal display device disclosed in Patent Document 1 as follows, it is possible to make the thickness of the gate insulating film 75 thinner in order to increase the auxiliary capacitance. When the thickness is reduced, it becomes difficult to maintain the electrical insulation between the gate electrode G and the scan line 72 covered by the gate insulating film 75 and the other members.

In addition, an array substrate of the liquid crystal display device 90 disclosed in Patent Literature 2 will be described below with reference to FIGS. For reference, FIG. 10 is a plan view of several pixels of the array substrate disclosed in Patent Document 2 as follows, and FIGS. 11A to 11G are partial cross-sectional views sequentially illustrating a manufacturing process of the array substrate of FIG. 10. First, a storage capacitor line 92 made of indium tin oxide (ITO) is patterned on an insulating substrate 91 made of a glass plate. Next, the gate metal film 93 is formed and patterned (FIG. 11A).

In addition, the gate insulating film 94 made of SiN _x or SiO _x , the amorphous semiconductor film 95 made of a-Si as an active layer, and, for example, n ⁺ a-Si doped with impurities by plasma CVD or the like The ohmic contact semiconductor film 96 made of a film is formed successively (FIG. 11B). At this time, the film thickness X of the gate insulating film is set sufficiently thick so that short between the drain gate and the source gate does not occur, for example, X = 4000 kPa.

Next, the ohmic contact semiconductor film 96 and the amorphous semiconductor film 95 are pattern-etched by the same resistor (FIG. 11C). Then, a resistor (not shown in FIG. 11) left after the portion where the storage capacitor line 92 overlaps with the pixel electrode 97 formed by a subsequent process as an opening pattern (broken line in FIG. 10) is coated, and the gate insulating film The etching liquid for (94) is etched so as to be thinned to a desired film thickness Y = 2000 kPa as the storage capacitor insulating film (FIG. 11D).

Next, the pixel electrode 97 made of ITO is formed and patterned (Fig. 11E). In addition, by forming and patterning the dray and source metal film 98 (FIG. 11F), and removing the ohmic contact semiconductor film 96 remaining in the channel portion of the TFT by etching, an array substrate for a liquid crystal display device is completed. (Figure 11g). The liquid crystal display device 90 can be obtained by arranging the array substrate obtained by such a configuration to face the common electrode substrate via the liquid crystal material.

In such a prior art, the storage capacitor line 92 and the pixel electrode 97 correspond to the electrodes of the capacitor, and the gate insulating film 94 existing between the storage capacitor line 92 and the pixel electrode 97 is a capacitor. Although it is equivalent to the dielectric of the dielectric layer of the insulating film 94 on the gate electrode 93, the thickness of the insulating film 94 on the auxiliary capacitance line 92, while the thickness of the insulating film 94 on the gate electrode 93, so that the drain gate, source gate The shortness of the liver becomes less likely to occur, and it is possible to secure the necessary auxiliary capacity without increasing the area of the auxiliary capacity line 92.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2005-506575 (Fig. 8, Fig. 9, Paragraph [0069] to [0085])

[Patent Document 2] Japanese Patent No. 2584290 (Patent Claims, Line 2 of 4, Line 30 to Line 3, Line 5 of 17, Line 1, Fig. 2)

In the array substrate of the liquid crystal display device 70 disclosed in the patent document 1, in order to secure a storage capacity sufficient to suppress display defects, a storage area pattern of a large area is required, and the aperture ratio is lowered, and the pixel is further reduced. Since the TFT and the storage capacitor conductive pattern 78 exist as a light shielding member, the aperture ratio becomes smaller. In the array substrate of the liquid crystal display device 90 disclosed in Patent Document 2, the gate electrode and the scan line covered by the gate insulating film by partially thinning only the thickness of the gate insulating film on the surface of the storage capacitor line by etching. Although the storage capacitance is increased while maintaining the electrical insulation between the other member and the other member, it is difficult to control the etching amount to obtain a desired thickness by partially thinning the thickness of the gate insulating film of the storage capacitor line. It was difficult to maintain the uniformity of the gate insulating film thickness of the storage capacitor line.

Furthermore, in the array substrate of the liquid crystal display device 90 disclosed in the patent document 2, after forming the auxiliary capacitance line 92 made of ITO on the insulating substrate 91 made of glass plate, the gate metal film ( Since the scan lines and the gate electrodes are formed by patterning 93, the distance between the pixel electrode 97 and the source metal film 98 is increased in consideration of the fact that the number of steps increases and manufacturing efficiency decreases, mask differences, and the like. Since the aperture ratio becomes small due to the necessity to take a large size and the fact that the pixel electrode cannot be provided in the portion of the TFT, the storage capacitor forming means for a relatively small pixel area or a highly precise liquid crystal display device is adopted. It is difficult.

In view of the above problems, the inventors of the present application make the efficiency of the capacitor for forming the storage capacitor higher, in particular, not to increase the number of processes, and to have a large aperture ratio and a relatively small pixel area or high precision liquid crystal display device. As a result of various studies on the storage capacitor forming means that can be used effectively, the drain electrode of the TFT is extended and used as an electrode paired with the storage capacitor line serving as one electrode of the capacitor forming the storage capacitor. In order to shorten the distance between the storage capacitor line and the drain electrode, replacing the gate insulating film interposed therebetween and interposing an insulating layer having a thickness thinner than that of the gate insulating film, in particular, increases the number of steps and decreases the aperture ratio. We find that capacity of subcapacitor can increase without work, and The invention has been completed.

That is, an object of the present invention is to provide a liquid crystal display device having a small pixel area or high definition pixel and a method of manufacturing the same, which can suppress display defects such as crosstalk and flicker without lowering the aperture ratio of each pixel. will be.

In order to achieve the first object of the present invention, the liquid crystal display device of the present invention comprises: a plurality of signal lines and scanning lines arranged in a matrix on a transparent substrate; A plurality of storage capacitor lines disposed in parallel between the scan lines; A thin film transistor provided near an intersection of the signal line and the scan line; And a pixel electrode disposed at each position defined by the signal line and the scan line and electrically connected to a drain electrode of the thin film transistor, wherein the gate electrode and the scan line of the thin film transistor are formed of a gate insulating film. And a drain electrode of the thin film transistor is extended on the auxiliary capacitor line with an insulating layer thinner than the thickness of the gate insulating film interposed therebetween.

In the above liquid crystal display device, the gate insulating film has a plural-layer structure, and the insulating layer is composed of at least one of them.

The present invention is also characterized in that in the above liquid crystal display device, the insulating film is one layer formed on the most surface side of the plurality of layers constituting the gate insulating film.

In the above liquid crystal display device, the insulating layer is one layer formed on the side of the most transparent substrate among the plurality of layers constituting the gate insulating film.

The present invention is also characterized in that in the above liquid crystal display device, the insulating layer is composed of a layer having the thinnest thickness among the plurality of layers constituting the gate insulating film.

In the above liquid crystal display device, the edge of the thin portion of the insulating layer on the storage capacitor line is located inward of the edge of the storage capacitor line.

In the above liquid crystal display device, the gate insulating film has a thickness of 2500 to 5500 kPa, and the insulating layer has a thickness of 500 to 1500 kPa.

In the liquid crystal display device according to the present invention, an interlayer insulating film is formed between the pixel electrode and the drain electrode, and a contact hole is formed in a portion of the interlayer insulating film located above the storage capacitor line. The pixel electrode and the drain electrode are electrically connected through a contact hole.

In the above liquid crystal display device, the reflective film is formed on the surface or the back of the pixel electrode so as to cover the entire region of the thin film transistor and the storage capacitor line or the position corresponding to the pixel electrode. It features.

Furthermore, in order to achieve the second object of the present invention, the invention provides a method of manufacturing a liquid crystal display device, comprising: disposing a plurality of scanning lines and storage capacitor lines parallel to each other on a transparent substrate; Forming a gate insulating film to cover the entire surface on the transparent substrate; Thinning a portion of the gate insulating layer on the storage capacitor line to form an insulating layer having a thickness thinner than a periphery of the storage capacitor line; And forming a storage capacitor by forming a drain electrode of the thin film transistor on the gate insulating film and extending the drain electrode of the thin film transistor to cover the insulating layer on the storage capacitor line.

In addition, the present invention provides a method of manufacturing the liquid crystal display device, wherein the step of forming the insulating layer comprises: forming a semiconductor layer on the gate insulating film; Applying a photoresist to the surface of the semiconductor layer; Removing a photoresist of the storage capacitor forming portion on the storage capacitor line by using a halftone mask, leaving a thick photoresist at a position corresponding to the gate electrode, and leaving a thin photoresist at the other portion; Removing an exposed semiconductor layer of the first half storage capacitance forming portion by etching, and then removing a portion of the gate insulating film positioned in the storage capacitance forming portion to form an insulating layer having a thickness thinner than a peripheral gate insulating film; Removing the thin photoresist and leaving the photoresist only at a position corresponding to the gate electrode; Removing the exposed semiconductor layer by etching; And removing the remaining photoresist.

In addition, the present invention provides a method of manufacturing the liquid crystal display device, wherein the step of forming the insulating layer includes a step of dividing the gate insulating film into a plurality of layers and a step of removing at least one layer therein. Characterized in that it comprises a.

The present invention is a method of manufacturing the liquid crystal display device, wherein the step of forming the insulating layer is a step of removing the first formed layer when the gate insulating film is divided into several layers to form a plurality of layers. do.

The present invention also provides a method of manufacturing the liquid crystal display device, wherein the step of forming the insulating layer is a step of removing the last formed layer after dividing the gate insulating film into a plurality of layers in order. It is done.

In the method of manufacturing the liquid crystal display device, the gate insulating film of the multilayer structure is formed by changing the substrate temperature for each layer using the same material.

In the method of manufacturing the liquid crystal display device, the substrate temperature is characterized in that the first gate insulating film is formed at the highest time, and the subsequent gate insulating film is sequentially lowered.

In the method for manufacturing the above liquid crystal display device, the gate insulating film of the multilayer structure is formed by changing the components of the ambient atmosphere gas for each layer using the same material.

In addition, the present invention provides a method of manufacturing the liquid crystal display device, comprising: forming an interlayer insulating film so as to cover the drain electrode; Forming a contact hole in the interlayer insulating layer at a position where the drain electrode and the storage capacitor line overlap each other; And forming a pixel electrode on the interlayer insulating layer to be electrically connected to the drain electrode through a contact hole.

In addition, the present invention provides a method of manufacturing the liquid crystal display device, wherein before or after the pixel electrode is formed, the entire surface of the position corresponding to the thin film transistor and the storage capacitor line or the position corresponding to the pixel electrode is provided. It is characterized by including a step of forming a reflecting plate.

This invention has the outstanding effect demonstrated below by having the said structure. That is, according to the liquid crystal display device of the present invention, although the drain electrode connected to the pixel electrode is provided with an insulating layer which is a part of the gate insulating film of the multilayer structure provided on a part of the storage capacitor line, the thickness of the insulating film is Since the insulating layer is thinner than the thickness of the gate insulating film covering the storage capacitor line, and the insulating layer forms the dielectric layer of the storage capacitor, the storage capacitor can be made remarkably large, which does not increase the area of the storage capacitor line and crosstalks it. The liquid crystal display device which can suppress display defects, such as a light and a flicker, can be obtained.

That is, the gate insulating film is originally provided with a uniform thickness over the entire transparent substrate for the purpose of maintaining the insulating property between the layers, but especially on the gate electrode serving as one terminal of the TFT, in order to maintain the electrostatic breakdown voltage of the TFT, It is impossible to thin. However, as in the liquid crystal display device of the present invention, by forming a thin insulating layer that is part of a double-layered gate insulating film on the surface of the storage capacitor line, the insulating film on the storage capacitor line can be made thin without particularly reducing the thickness of the entire gate insulating film. As a result, the above-described effects can be achieved without adversely affecting other configurations. Furthermore, since the storage capacitor can be formed simply by extending the drain electrode, the storage capacitance of the light shielding can be efficiently disposed, and the aperture ratio is improved.

According to the liquid crystal display device of the present invention, when the gate insulating film of the multilayer structure is formed, one of the plurality of insulating layers on the storage capacitor line is formed, that is, the layer formed on the most surface side of the gate insulating film or the most transparent substrate side. In the case where the layer is formed in the layer, the thin insulating layer described above can be easily formed by, for example, removing unnecessary layers by etching using a material having different etching characteristics from each layer of the gate insulating film. Moreover, if the layer used as this insulating layer is made into the thinnest layer of each layer of the gate insulating film, the capacity of the storage capacitor can be easily increased.

In addition, according to the liquid crystal display device of the present invention, since the edge of the thin portion of the insulating layer on the storage capacitor line is positioned inward from the edge of the storage capacitor line, there is a sufficient gap between the phase electrode and the scanning line constituting the storage capacitor. The capacitance of the storage capacitor can be increased while ensuring the electrostatic breakdown voltage of the upper electrode and the lower electrode constituting the storage capacitor near the edge of the storage capacitor line.

According to the liquid crystal display device of the present invention, since the thickness of the gate insulating film is 2500 to 5500 kPa, the film thickness is maintained so as not to impair insulation, and the insulating layer is thinned to 500 to 1500 kPa. It is possible to increase the capacity. On the other hand, the film thickness of the gate insulating film is more preferably 2800 kPa or more, and the thickness of the insulating layer is more preferably around 1000 kPa.

In addition, according to the liquid crystal display device of the present invention, these wirings are covered by an interlayer insulating film after various wirings such as scanning lines, signal lines, and thin film transistors are formed, but the pixel electrodes are provided on the surface of the interlayer film. This is flattened. For this reason, the cell gap of a liquid crystal display device can be made uniform, and a liquid crystal display device with a favorable display quality can be obtained. In addition, since the pixel electrode is electrically connected to the drain electrode through a contact hole provided on the storage capacitor line, even if the cell gap on the contact hole is different from the surrounding cell gap, the part of the contact hole is formed by the light blocking drain electrode. By shielding the light from the backlight, the display quality is not adversely affected.

In addition, according to the liquid crystal display device of the present invention, if a reflecting plate is provided on the surface or the back side of the thin film transistor and the storage capacitor line of the pixel electrode, the liquid crystal display device of a transflective type can be easily formed. If the reflecting plate is provided so as to cover the entire surface or the rear surface, it is possible to simply form a reflective liquid crystal display device.

On the other hand, according to the manufacturing method of the liquid crystal display device of the present invention, in addition to being able to easily manufacture the liquid crystal display device having the effect of the present invention, the gate insulating film and the semiconductor layer of the multilayer structure were formed successively in order, Compared to the method of forming the semiconductor layer after the gate insulating film forming and etching processes, the process of maintaining the surroundings of the substrate from the normal pressure state to the vacuum state can be reduced once, and the etching process of the gate insulating film is performed. It is less likely to be affected by the resulting contamination, and the characteristics of the TFT are less likely to deteriorate.

According to the manufacturing method of the liquid crystal display device of the present invention, when the gate insulating film having a multilayer structure is formed, one of the plurality of insulating layers formed on the storage capacitor line, that is, the first formed layer or the last formed layer of the gate insulating film is formed. Since it is made to remove, the insulating layer of thickness thinner than a gate insulating film can be formed simply.

In addition, according to the manufacturing method of the liquid crystal display device of the present invention, since the gate insulating film of the multilayer structure is formed by changing the substrate temperature for each layer using the same material, it is possible to change only the substrate temperature without changing the ambient atmosphere. As a result, a multi-layered gate insulating film having substantially the same composition but different physical properties can be formed. In addition, only the insulating layer on the surface of the storage capacitor line can be easily left by etching using the difference in physical properties. Therefore, when forming the multi-layered gate insulating film, it is not necessary to perform an etching process for each film. Therefore, contamination of the surface of each film can be avoided, and a predetermined insulating film and a gate insulating film can be formed in a short time. In this case, silicon nitride, silicon oxide, or the like can be used as the gate insulating film forming material.

Further, according to the manufacturing method of the liquid crystal display device of the present invention, the gate insulating film of the multilayer structure can be formed by changing the components of the ambient atmosphere gas for each layer by using the same material, and also based on the difference in this composition. The difference in physical properties allows etching to leave only the insulating layer on the surface of the auxiliary capacitance line. Therefore, when forming the gate insulating film of the multilayer, it is not necessary to perform an etching process for each film. Therefore, contamination of the surface of each film can be avoided, and a predetermined insulating film and a gate insulating film can be formed in a short time. It is preferable that the gate insulating film of the multilayer structure which consists of thin films of this different composition consists of a silicon nitride layer and a silicon oxide layer, Furthermore, it is more preferable that the uppermost layer consists of a silicon nitride layer.

EMBODIMENT OF THE INVENTION Hereinafter, the best embodiment of this invention is described with reference to drawings. However, embodiment shown below illustrates the liquid crystal display device for manufacturing the technical idea of this invention, and its manufacturing method, and does not intend specifying this invention with this liquid crystal display device and its manufacturing method, The same applies to other embodiments that are included in the claims. For reference, the liquid crystal display of the embodiment described below will be described with reference to a transmissive liquid crystal display device. However, the liquid crystal display device of the present invention is not limited to a transmissive type, but can also be applied to a transflective or reflective liquid crystal display device. Is obvious.

Example 1

1 is an enlarged plan view showing a portion corresponding to one pixel of the liquid crystal display device according to the first embodiment of the present invention and through the other substrate, for example, a color filter substrate, and FIG. It is a side cross-sectional view which shows the state cut | disconnected by the II-II line of a liquid crystal display device, and FIG. 3 and FIG. 4 are sectional drawing which shows the manufacturing process which manufactures the array substrate of the liquid crystal display device of FIG. 3 and 4 show the state of the section cut | disconnected by the II-II line | wire of FIG.

The liquid crystal display device 10 according to the first embodiment has a surface outer periphery of a pair of substrates formed of an array substrate 13 and a color filter substrate 14 having various wirings and the like formed on transparent substrates 11 and 12 made of glass or the like. Is bonded by a seal material (not shown), and the liquid crystal 15 is inject | poured into it, and is produced.

Various wirings and the like are formed on the array substrate 13 and the color filter substrate 14 (inner surface side), and among the array substrate 13, a plurality of scan lines 16 and signal lines (in a matrix form) are formed. 17 and a plurality of lines of storage capacitor lines 18 provided between the plurality of lines of scan lines 16 and parallel to the lines of scan lines 16, source electrodes S, gate electrodes G, drain electrodes D, and semiconductor layers 19. ) And a pixel electrode 20 covering a region surrounded by the scan line 16 and the signal line 17. In addition, although polysilicon (p-Si) or amorphous silicon (a-Si) is normally used as the semiconductor layer 19 of TFT, it is not limited to this, Any active element may be sufficient.

The color filter substrate 14 includes a black matrix 21 provided in a matrix shape in accordance with the pixel region of the array substrate 13, and red (R) and green (green) provided in an area surrounded by the black matrix 21. Color filters 22, such as G) and blue (B), and the common electrode 23 provided so that the color filter may be electrically connected to the electrode of the array substrate side are normally provided. However, the present invention is not limited thereto, and in the case of the transverse electric field system, there may be no common electrode, in the case of black and white display, there may be no color filter. It may be comprised by the color filter of.

In the region surrounded by the array substrate 13, the color filter substrate 14, and the sealant, a plurality of spacers or the like for uniformizing the distance between the substrates are disposed as necessary, and the liquid crystal 15 is encapsulated. It is.

Next, the manufacturing process of the above-mentioned array substrate of the liquid crystal display device is shown below with reference to FIG. 3 and FIG.

First, as shown in FIG. 3A, a conductive material layer 24 made of aluminum, molybdenum, chromium, or an alloy thereof having a predetermined thickness is formed on the transparent substrate 11. As shown in Fig. 3B, by patterning using a known photolithography method, a part of the portion is removed by etching, and between the plurality of scanning lines 16 extending in the lateral direction and the scanning lines 16 of the plurality of lines. Auxiliary capacitance line 18 is formed. 3B shows the storage capacitor electrode 18a formed by widening a portion of the gate electrode G and the storage capacitor line 18 growing from the scan line 16. In addition, the scanning line 16 and the storage capacitor line 18 which are shown here are shown as the wiring of the multilayer structure which consists of aluminum and molybdenum. This has the advantage that aluminum has a small resistance value, but on the other hand, since it has a drawback such as high contact resistance with ITO, which is easy to corrode, such a defect can be improved by having a multilayer structure in which aluminum is covered with molybdenum. .

Next, the insulating film 25 of the 1st layer of predetermined thickness is formed into a film so that the scanning line 16 and the auxiliary capacitance line 18 may be covered by the said process. As the insulating film 25 of the first layer, a transparent resin material made of silicon nitride or the like is used. Since the thickness of the insulating film 25 of the first layer is related to the insulating property of the scan line 16 and the gate electrode G, the thickness is 2500 to 2500. It is preferable to set it as the range of 5500 Hz, More preferably, you may be 2800 Hz or more. When the insulating film 25 of the first layer is formed, as shown in FIG. 3D1, only the portion located on the storage capacitor electrode 18a of the insulating film 25 of the first layer is removed by etching to form the window 27. To form.

After the process is completed, as shown in FIG. 3E, the second insulating layer 26 thinner than the first insulating layer 25 is formed so as to cover the transparent substrate 11. The insulating layer 26 of the second layer is formed on the insulating film 25 of the first layer and the storage capacitor electrode 18a from which the insulating film 25 of the first layer has been removed by the above-described etching, so that the scanning line 16 is formed. The gate electrode G is covered by both the insulating film 25 of the first layer and the insulating layer 26 of the second layer material, and this two-layer film constitutes the gate insulating film. The storage capacitor electrode 18a is covered only by the second insulating layer 26. On the other hand, the material of the insulating layer 26 of the second layer may be made of the same material as that of the insulating film 25 of the first layer, that is, silicon nitride, or may be another insulating film, for example, silicon oxide. The thickness is thinner than the insulating film 25 of the 1st layer, Preferably it is 500-1500 kPa, More preferably, it is 1000 kV, for example, 800-1200 kPa.

In such a configuration, in the same method as the gate insulating film, the purpose is to form an insulating film thinner than the thickness of the gate electrode portion, that is, the thickness around the storage capacitor line, as the main portion of the storage capacitor electrode 18a of the storage capacitor line. It is also contemplated to form the layer insulating layer 26 in particular, but it is efficient to form the gate insulating film, for example, of two to five layers, and the insulating layer is composed of at least one of them. In such a case, the etching properties may be changed by changing the film quality, and the lowermost one of the layers formed as the gate insulating film of the multilayer structure may be used. The most efficient is to form the first layer of the film thickness as described above, remove it to the surface of the electrode by etching, and form an insulating film made of a thin film thereon to form the insulating layer as one layer formed on the surface side of the gate insulating film. It is preferable. Thereby, the insulating layer can be comprised by the thinnest layer in the several layer which comprises a gate insulating film, and can make a storage capacity largely remarkably.

Next, as shown in FIG. 3F, a silicon layer, for example, a-Si, is formed on the second insulating layer 26 to a thickness of 1800 GPa. As shown in Fig. 3G, the a-Si layer is removed by etching leaving a portion covering the gate electrode G, thereby forming a semiconductor layer 19 that becomes part of the TFT. By a similar method, as shown in FIG. 4A, a conductive material is formed on the transparent substrate 11, and a plurality of signal lines 17 extending in a direction orthogonal to the scan line 16, and the semiconductors extended from the signal lines 17. The drain electrode D connected to the semiconductor layer 19 is patterned at the same time as covering the source electrode S connected to the layer 19 and the storage capacitor electrode 18a. As a result, a TFT serving as a switching element is formed in the vicinity of the intersection of the scan line 16 and the signal line 17 of the transparent substrate 11.

Further, as shown in Fig. 4B, a protective insulating film 28 made of an inorganic insulating material for stabilizing the surface is formed on the transparent substrate 11 so as to cover these various wirings, and then, as shown in Fig. 4C, an array is formed. An interlayer film 29 made of an organic insulating material for flattening the surface of the substrate 13 is formed. In addition, in the portion located on the storage capacitor electrode 18a of the interlayer film 29, holes for forming contact holes 30 for electrically connecting the pixel electrode 20 and the drain electrode D, which will be described later, are provided. The position of this hole is not limited to the storage capacitor electrode 18a. However, since the distance between the substrates is different from the other portions when the portion where the contact hole 30 is formed is bonded to the color filter substrate 14 as the liquid crystal display device 10, there is a possibility that a difference in display quality may occur. Preferably, it is provided on the storage capacitor electrode 18a which is a light shielding material. Then, as shown in FIG. 4D, after removing the protective insulating film 28 made of the inorganic insulating material exposed from the hole formed in the interlayer film 29, and finally, as shown in FIG. 4E, the scanning line 16 And a pixel electrode 20 made of, for example, ITO for each pixel region surrounded by the signal line 17. At this time, preferably, a part thereof is disposed on the scan line 16 and the signal line 17, and the adjacent pixel electrodes 20 are arranged to be in a non-connected state. The array substrate 13 is manufactured by the above process.

The storage capacitor of the array substrate 13 formed in accordance with the above-described manufacturing method is a drain electrode D whose electrodes are connected to the storage capacitor electrode 18a and the pixel electrode 20, and the dielectric layer has an insulating layer of the second layer having a thickness of 1000 Å. And a condenser structure of (26). Therefore, as in the prior art, since the dielectric is an insulating film thinner than the gate insulating film of 2500 to 4500 kV, the capacitor capacity can be dramatically increased. Moreover, since the gate electrode G and the scanning line 16 are coat | covered with the laminated body of the insulating film 25 of 1st layer, and the insulating layer 26 of 2nd layer, the insulation is ensured.

In addition, by increasing the capacitor capacitance, the electrode portion constituting the storage capacitor can be made small, and the aperture ratio of the pixel can be increased. Since the drain electrode D also serves as an electrode constituting the storage capacitor, the light shielding portion in the pixel can be made smaller than in the case where an electrode (conductive layer) is provided in addition to the drain electrode D as the storage capacitor electrode, thereby improving the aperture ratio. Can be.

In order to increase the capacity of the storage capacitor, it is preferable to make the insulating film thin at all portions forming the storage capacitor. In this embodiment, since the insulating film of the storage capacitor portion is made thin by partially removing the insulating film 25 of the first layer, in order to increase the capacitance, the portion of the storage capacitor electrode that removes the insulating film 25 of the first layer is removed. It is better to make it larger than (18a). In other words, the edge of the window portion 27 of the insulating film 25 of the first layer may be outside the edge of the storage capacitor electrode 18a. By the way, when the drain electrode D also serves as an electrode of the storage capacitor, the storage capacitor is arranged near the scanning line 16. Therefore, when the insulating film is made thinner to the outside of the storage capacitor portion, the gap between the storage capacitor phase electrode (drain electrode D) and the scanning line 16 becomes too close, causing problems such as parasitic capacitance. Therefore, when the drain electrode D also serves as the storage capacitor phase electrode, it is necessary to thin the insulating film of the storage capacitor portion while widening the interval between the storage capacitor phase electrode and the scan line 16, and the edge of the thin portion of the insulating film is It is positioned inside the edge of the storage capacitor electrode (18a). In addition, since the insulating film formed on the storage capacitor electrode 18a tends to be thinner than other portions in the vicinity of the edge of the storage capacitor electrode 18a, the storage capacitor electrode 18a and the storage capacitor electrode 18a are near the edges of the storage capacitor electrode 18a. In order to ensure the electrostatic withstand voltage with the phase electrode, the insulating film near the edge of the storage capacitor electrode 18a is preferably thicker than the insulating film near the center of the storage capacitor electrode 18a. In this embodiment, the scanning line 16 with the storage capacitor phase electrode (drain electrode D) is formed by making the edge of the portion (window portion 27) from which the insulating film 25 of the first layer is removed is inside the storage capacitor electrode 18a. A sufficient interval is established between the electrodes and the electrostatic withstand voltage between the phase electrode and the storage capacitor electrode is also secured.

In this embodiment, as a method of thinning the insulating film of the storage capacitor portion, first, the insulating film of the first layer is formed, the portion corresponding to the storage capacitor electrode of the insulating film of the first layer is completely removed, and the first layer is The insulating film of the 2nd layer thinner than the insulating film of is laminated | stacked. As a method of thinning the insulating film of the storage capacitor portion, there is also a method of forming a thick insulating film first, and then partially etching the insulating film to make it thin, but this embodiment can easily control the thickness of the insulating film of the storage capacitor portion. A film of uniform thickness can be formed.

As described above, according to the liquid crystal display device of the present invention, the capacitance of the storage capacitor can be increased without increasing the area of the storage capacitor electrode made of the light-shielding material. 16) and the adjacent pixel electrodes 20 provided on the signal line 17 so as to be in a non-connected state, it is possible to suppress display defects such as crosstalk and flicker without lowering the aperture ratio of each pixel. . Furthermore, since the pixel electrode 20 is provided on the flat interlayer film 29, the cell gap of the obtained liquid crystal display device 10 can be made uniform, so that the liquid crystal display device 10 with good display image quality can be obtained. Can be.

In the case where the liquid crystal display device of the present invention is not transmissive but semi-transmissive, at the same time, partial irregularities are formed on the surface of the interlayer film 29 formed in the region excluding the contact hole 30 of the pixel electrode. What is necessary is just to form the reflecting film which consists of a light reflection material between this uneven part and the pixel electrode 20 or the surface of the pixel electrode 20. FIG. In the transflective liquid crystal display device, the area of the transmissive part is smaller than that of the transmissive liquid crystal display device, and therefore, the liquid crystal display device of the present invention and its manufacturing method which can increase the area of the opening are particularly effective. In the case where the liquid crystal display device is to be a reflective type, a reflective film may be formed between the interlayer film 29 or the entire surface of the pixel electrode 20.

Example 2

Next, the manufacturing process of the array substrate of the liquid crystal display device 10a of Example 2 is demonstrated using FIG. For reference, an enlarged plan view of a portion corresponding to one pixel of the array substrate shown through the color filter substrate of the liquid crystal display device 10a of the second embodiment is the case of the liquid crystal display device 10 of the first embodiment shown in FIG. As in Fig. 1, the drawings corresponding to the II-II cross-sectional view of Fig. 1 on the array substrate of the second embodiment are the same as those of the liquid crystal display device 10 of the first embodiment shown in Fig. The same reference numerals are given to the same parts as those of the liquid crystal display device 10 according to the first embodiment. 5A to 5E and 6A to 6D are sectional views showing the manufacturing process for manufacturing the array substrate of the liquid crystal display device 10a of the second embodiment. 5A to 5E and 6A to 6D all show positional states corresponding to the II-II cross section of FIG. 1.

First, as shown in FIG. 5A, a conductive material layer 24 made of aluminum, molybdenum, chromium, or an alloy of a predetermined thickness is formed on the transparent substrate 11. Then, as shown in Fig. 5B, by patterning using a known photolithography method, a plurality of scanning lines 16 which are etched and removed to grow laterally and the gates which line the scanning lines 16 are formed. The storage capacitor line 18 is formed between the electrode G and the plurality of scanning lines 16, respectively. 5B, the storage capacitor electrode 18a formed by widening the gate electrode G extending from the scanning line 16 and a part of the storage capacitor line 18 is shown.

Next, as shown in Fig. 5C, the transparent substrate 11 on which the scanning line 16 and the auxiliary capacitance line 18 are formed by the above process is heated to a high temperature, for example, 350 DEG C in a vacuum apparatus, According to the method, the insulating film 25 of the 1st layer which consists of silicon nitride of predetermined thickness (for example, 1000 micrometers) is formed in the surface by plasma CVD (Chemical Vapor Depositioin) method. Thereafter, the temperature of the transparent substrate 11 having the first insulating film 25 formed thereon is lowered to a temperature lower than the initial temperature, for example, 250 ° C. For example, the second insulating layer 26 made of 3000 ns of silicon nitride is formed. Both the insulating film 25 of the first layer and the insulating layer 26 of the second layer serve as gate insulating films. Further, the semiconductor layer 19 made of, for example, an a-Si layer and an n ⁺ a-Si layer is formed on the entire surface of the insulating layer 26 of the second layer (for example, a-Si layer 1800 kPa). And n ⁺ a-Si layer 500 Hz).

The insulating film 25 of the 1st layer, the insulating layer 26 of the 2nd layer, and the semiconductor layer 19 can be formed continuously, without taking out the transparent substrate 11 from a vacuum apparatus. On the other hand, the insulating film 25 of the first layer and the insulating layer 26 of the second layer have different substrate temperatures at the time of forming the respective insulating films, so that even if they are made of the same silicon nitride, the degree of curing of the film is different and the substrate temperature is high. Since the insulating film 25 of the 1st layer becomes hard, the wet etching rate by buffered hydrofluoric acid falls. Moreover, as long as the thickness of the insulating film 25 of a 1st layer does not produce a short circuit, it is preferable that it is thin, and it is good to set it as 500-1500 kPa. In addition, both the insulating film 25 of the 1st layer and the insulating layer 26 of the 2nd layer may be put together, and the thickness may be 2500-5500 kPa, in order to prevent insulation breakdown by static electricity in the gate electrode G part of TFT. .

In this case, an insulating film having a different etching rate is formed by changing the substrate temperature when the insulating film is laminated. Alternatively, an insulating film having a different etching rate may be formed by changing a component of the atmosphere gas. For example, silicon nitride is formed using silane gas and nitrogen gas, and a higher ratio of silane gas is used when forming the second layer than when forming the first layer, so that the insulating film is higher than the insulating layer (second layer). It is also possible to harden (1st layer) further.

Thereafter, as shown in FIG. 5D, the semiconductor layer 19 is removed by dry etching so that the semiconductor layer 19 remains on the surface of the gate electrode G of the TFT, and then the surface of the storage capacitor electrode 18a is removed. The window 27 is formed by removing the insulating layer 26 of the second layer by wet etching or dry etching using buffered hydrofluoric acid so that the insulating layer 25 of the first layer is exposed. At this time, since the etching rate of the insulating layer 25 of the first layer is lower than that of the insulating layer 26 of the second layer, the insulating layer 25 of the first layer can be left in an unetched state. .

Next, after forming a conductive material layer made of aluminum, molybdenum, chromium or these alloys on the transparent substrate 11, as shown in Figs. 1 and 5E, a plurality of layers extending in the direction orthogonal to the scanning line 16 are shown. Two signal lines 17, a source electrode S extending from the signal line 17, connected to the semiconductor layer 19, and a drain connected to the semiconductor layer 19 at one end thereof while covering the storage electrode 18a. The electrode D is patterned. As a result, a TFT serving as a switching element is formed in the vicinity of the intersection between the scan line 16 and the signal line 17 of the transparent substrate 11.

As shown in Fig. 6A, a protective insulating film 28 made of an inorganic insulating material (for example, silicon nitride) for stabilizing the surface is formed on the transparent substrate 11 so as to cover these various wirings. As shown in FIG. 6B, after forming an interlayer film 29 made of an organic insulating material such as polyimide for planarizing the surface of the array substrate 13, the storage capacitor electrode 18a is formed by etching as shown in FIG. 6C. The contact hole 30 is formed in the interlayer film 29 and the protective insulating film 28 which are located on it. The position at which the contact hole 30 is formed is not limited to the storage capacitor electrode 18a, but the portion where the contact hole 30 is formed is combined with the color filter substrate 14 as the liquid crystal display device 10. Since the distance between the substrates, i.e., the cell gap, is different from that of other parts, there is a possibility that a variation in display quality may occur, and therefore, it is preferable to provide it on the storage capacitor electrode 18a, which is a light-shielding material.

As shown in FIG. 6D, the pixel electrode 20 made of, for example, ITO is formed for each pixel region surrounded by the scan line 16 and the signal line 17. At this time, in order to prevent light leakage, a part of the pixel electrode 20 is preferably positioned on the scan line 16 and the signal line 17 so that the adjacent pixel electrodes 20 are arranged in a non-connected state. The array substrate 13 is manufactured by the above process.

As for the storage capacitor of the array substrate 13 of the liquid crystal display device 10a of Example 2 formed according to the above-described manufacturing method, the drain electrode D connected to the storage capacitor electrode 18a and the pixel electrode 20 is the electrode of the capacitor. The dielectric layer 25 of the first layer disposed between the storage capacitor electrode 18a and the drain electrode D corresponds to the dielectric of the capacitor, and the thickness of the dielectric composed of the dielectric layer 25 of the first layer is Since the thickness of the gate insulating film that is conventionally used can be set to 500 to 1500 kW, which is thinner than the thickness of 2500 to 4,500 kW, the storage capacitance can be dramatically increased without increasing the area of the storage capacitor electrode 18a. In addition, since the gate electrode G and the scanning line 16 are covered by the gate insulating film which consists of a laminated body of the insulating film 25 of the 1st layer, and the insulating layer 26 of a 2nd layer, insulation is fully ensured.

As described above, according to the liquid crystal display device of the second embodiment, the storage capacitor can be increased without increasing the area of the storage capacitor electrode 18a made of the light-shielding material, so that the crosstalk without reducing the aperture ratio of each pixel is reduced. And display defects such as flicker can be suppressed. Furthermore, since the pixel electrode 20 is provided on the flat interlayer film 29, the cell gap of the obtained liquid crystal display device 10a can be made uniform, so that the display quality of the liquid crystal display device 10 is good. Can be obtained.

Furthermore, in Example 2 mentioned above, although the example in which the insulating film 25 of the 1st layer and the insulating layer 26 of the 2nd layer were made into silicon nitride together was shown, both may be formed from silicon oxide, and One of the insulating film 25 of the first layer and the insulating layer 26 of the second layer may be silicon oxide, and the other may be silicon nitride. However, it is better to bring a layer having a high etching rate to the uppermost layer, and in terms of insulation, the insulating layer 26 of the second layer may be made of silicon nitride. Further, the storage capacitor line may be made of aluminum, the surface may be anodized to aluminum oxide, and the film may be used as the insulating layer of the storage capacitor portion.

Example 3

Next, the manufacturing process of the array substrate of the liquid crystal display device 10b of Example 3 is demonstrated using FIG. For reference, an enlarged plan view of a portion corresponding to one pixel of the array substrate shown through the color filter substrate of the liquid crystal display device 10b of the third embodiment is the case of the liquid crystal display device 10 of the first embodiment shown in FIG. In the same manner as in the case of the liquid crystal display device 10 of the first embodiment shown in FIG. 2, the drawings corresponding to the II-II cross-sectional view of FIG. 1 in the array substrate of the third embodiment are similar to those of FIG. 1. And FIG. 2 is used, and the same part as the structure of the liquid crystal display device 10 of Example 1 is attached | subjected, and it demonstrates. 7A to 7F and 8A to 8E are sectional views showing the manufacturing process for manufacturing the array substrate of the liquid crystal display device 10b of the third embodiment. 7A to 7F and 8A to 8E all show positional states corresponding to the II-II cross section of FIG. 1.

First, as shown in FIG. 7A, a conductive material layer 24 made of aluminum, molybdenum, chromium, or an alloy of predetermined thickness is formed on the transparent substrate 11. As shown in FIG. 7B, by patterning by using a known photolithography method, a part of the wafer is etched and removed, and the plurality of scanning lines 16 growing in the transverse direction and the scanning lines 16 are lined up. The storage capacitor line 18 is formed between the gate electrode G and the plurality of scanning lines 16, respectively. In FIG. 7B, the storage capacitor electrode 18a formed by widening the gate electrode G growing from the scanning line 16 and a part of the storage capacitor line 18 is shown. In addition, the scanning line 16 and the storage capacitor line 18 which are shown here have a multilayer structure which consists of aluminum and molybdenum in order to make the junction contact with a pixel electrode.

Next, as shown in FIG. 7C, the plasma CVD (Chemica 1 Vapor Deposition) method or the like is performed on the surface of the transparent substrate 11 on which the scanning line 16 and the auxiliary capacitance line 18 are formed by the above process. To form an insulating film 25 'made of silicon nitride having a predetermined thickness (for example, 4000 kPa) on the surface, and further, for example, an a-Si layer and an n ⁺ a-Si layer on the entire surface of the insulating film 25'. The semiconductor layer 19 is formed to have a predetermined thickness (for example, a-Si layer 1800 mV and n ⁺ a-Si layer 500 mV).

Both of the insulating film 25 'and the semiconductor layer 19 can be formed continuously without taking out the transparent substrate 11 from the vacuum apparatus. Further, the thickness of the insulating film 25 'may be set to 2500 to 5500 Pa in order not to cause dielectric breakdown in the gate electrode G portion of the TFT.

Subsequently, as shown in FIG. 7D, the positive photoresist 31 is provided on the entire surface of the transparent substrate 11 so as to have a uniform thickness, and the photoresist 31 is replaced with the halftone mask 32. Exposure by using. In this halftone mask 32, the portion 33 corresponding to the gate electrode G of the TFT is completely light-shielding, the portion 34 corresponding to the storage capacitor electrode 18a is translucent, and the other portion 35 is semi-transmissive. It is. Therefore, when developing the photoresist 31. After exposure, as shown in Figure 7e, the gate electrode G surface remains a thick photoresist (31 _1), the surface of the photoresist of the storage capacitor electrode (18a) is not present no semiconductor layer 19 is exposed, and the remaining portion of the surface, the thickness than the photoresist (31 ₁₎ of the gate electrode G thin photoresist (31 ₂₎ remains.

In this state, as shown in FIG. 7F, the semiconductor layer 19 on the surface of the storage capacitor electrode 18a is removed by dry etching to expose the insulating film 25 ′, and the surface of the storage capacitor electrode 18a is exposed. A part of the exposed insulating film 25 'is wet etched or dry etched with hydrofluoric acid so that an insulating layer 26' having a predetermined thickness (for example, 1000 kPa) is left. And then, as shown in Figure 8a, to remove a thin layer of photoresist (31 ₂₎ by ashing to expose the semiconductor layer 19. At this time, part of the thick photoresist layer 31 _{1 positioned} on the gate electrode G is ashed, so that the thickness becomes thin, but the semiconductor layer 19 remains as it is. Thereafter, as shown in FIG. 8B, the semiconductor layer 19 exposed by dry etching is removed.

Thereafter, the thick photoresist layer 31 ₁ located on the gate electrode G is removed by ashing, and a conductive material layer made of aluminum, molybdenum, chromium, or an alloy thereof is formed on the transparent substrate 11, As shown in FIG. 1 and FIG. 8C, a plurality of signal lines 17 extending in a direction orthogonal to the scanning line 16, source electrodes S and auxiliary capacitances extending from the signal lines 17 and connected to the semiconductor layer 19. The drain electrode D whose one end is connected to the semiconductor layer 19 is patterned, covering the electrode 18a. As a result, a TFT serving as a switching element is formed in the vicinity of the intersection between the scanning line 16 and the signal line 17 of the transparent substrate 11. A protective insulating film 28 made of an inorganic insulating material (for example, silicon nitride) for stabilizing the surface is formed on the transparent substrate 11 so as to cover such various wirings, and then the surface of the array substrate 13 is formed. An interlayer film 29 made of an organic insulating material such as polyimide for planarization is formed.

As shown in FIG. 8D, the contact hole 30 is formed in the interlayer film 29 and the protective insulating film 28 positioned on the storage capacitor electrode 18a by etching. Further, the position at which the contact hole 30 is formed is not limited to the storage capacitor electrode 18a, but the portion where the contact hole 30 is formed is combined with the color filter substrate 14 as the liquid crystal display device 10. Since the distance between the substrates, i.e., the cell gap, is different from that of other parts, there is a possibility that the display quality may vary. Therefore, it is preferable that the substrate is provided on the storage capacitor electrode 18a, which is a light-shielding material.

As shown in Fig. 8E, a pixel electrode 20 made of, for example, ITO, IZO, or the like is formed for each pixel region surrounded by the scan line 16 and the signal line 17. The pixel electrode 20 shown in Figs. At this time, in order to prevent light leakage, preferably, a part of the pixel electrode 20 is positioned on the scan line 16 and the signal line 17, and the adjacent pixel electrodes 20 are arranged so as to be in a non-connected state. By the above process, the array substrate 13 of the liquid crystal display device 10b of Example 3 is manufactured.

As for the storage capacitor of the array substrate 13 formed by the manufacturing method of Example 3 mentioned above, the drain electrode D connected to the storage capacitor electrode 18a and the pixel electrode 20 corresponds to the electrode of a capacitor | condenser, The insulating layer 26 'disposed between 18a) and the drain electrode D corresponds to the dielectric of the capacitor, and the thickness of the dielectric made of the insulating layer 26' is larger than the 2500 to 4600 GPa thickness of the gate insulating film conventionally used. Since it can be set to 500-1500 microseconds large, a storage capacity can be increased remarkably, without increasing the area of the storage capacitor electrode 18a. In addition, since the gate electrode G and the scanning line 16 are covered by the gate insulating film which consists of the insulating film 25 'thicker than the insulating layer 26', insulation is fully secured.

On the other hand, in Example 3 mentioned above, although the case where it was set as the single silicon nitride layer was shown as the insulating film 25 ', in this case, since the insulating film 25' becomes homogeneous, the insulating film 25 'is buffered. When wet etching with hydrofluoric acid to form a thin insulating layer 26 ', it is necessary to strictly control the etching time. However, if the insulating film 25 'is made of a multilayer structure made of a material having a different etching rate, the etching conditions can be made more flexible and the manufacturing becomes easier. For example, when the temperature of the transparent substrate 11 is first raised to provide a hard silicon nitride film, and then the temperature of the transparent substrate 11 is lowered to stack the soft silicon nitride film, the soft silicon nitride film is buffered hydrofluoric acid. Since the etching rate is faster, the hard silicon nitride film of the lower layer is not double-etched even if there is a slight error in etching time, so that the insulating layer 26 with the correct thickness can be obtained.

In addition, the insulating film 25 'can be made into a single layer of silicon oxide, and can also be made into the multilayer structure of a silicon nitride layer and a silicon oxide layer. In terms of insulation, however, the uppermost layer is preferably made of a silicon nitride film.

In addition, in Example 3 mentioned above, although the example in which the insulating film 25 'and the insulating layer 26' were made together with silicon nitride was shown, both can be formed with silicon oxide etc., Furthermore, the 1st insulating film And either one of the second insulating layers may be silicon oxide, and the other may be silicon nitride.

As described above, according to the liquid crystal display device 10b of the third embodiment, the storage capacitor can be increased without increasing the area of the storage capacitor electrode 18a, so that the crosstalk is not reduced without decreasing the aperture ratio for each pixel. And display defects such as flicker can be suppressed. In addition, according to the manufacturing method of the liquid crystal display device 10b of Example 3, since the gate insulating film and the semiconductor layer were formed successively, the semiconductor layer was formed after performing the film forming and etching processes of the gate insulating film. Compared with the method, the surface of the storage capacitor line is etched by etching using the photoresist layer left around the storage capacitor line by the halftone mask as a mask while reducing the process of maintaining the periphery of the substrate in the vacuum state from the normal pressure state. It is possible to remove the semiconductor layer located in the above, and furthermore, it becomes less susceptible to the contamination caused by the etching process of the gate insulating film, so that the characteristics of the TFT are reduced. Furthermore, according to the manufacturing method of the liquid crystal display device 10b of Example 3, after the semiconductor layer on the surface of the storage capacitor line is etched, the formation of the insulating layer is performed by etching the remaining photoresist layer and the semiconductor layer as a mask as it is. Since the etching process of a semiconductor layer increases after formation of an insulating layer, it becomes unnecessary to perform a photolithography process at the time of especially forming an insulating layer.

ADVANTAGE OF THE INVENTION According to this invention, display defects, such as crosstalk and a flicker, can be suppressed, without reducing the aperture ratio for every pixel, and it is possible to provide the liquid crystal display device which has a small pixel area or a high definition pixel, and its manufacturing method. Do.

Claims (19)

A plurality of signal lines and scanning lines arranged in a matrix on a transparent substrate; A plurality of storage capacitor lines disposed in parallel between the scan lines; A thin film transistor provided near an intersection of the signal line and the scan line; And A liquid crystal display device comprising a pixel electrode disposed at each position partitioned by the signal line and the scanning line and electrically connected to a drain electrode of the thin film transistor. The gate electrode and the scanning line of the thin film transistor are covered with a gate insulating film, and the drain electrode of the thin film transistor is extended on the auxiliary capacitor line with an insulating layer thinner than the thickness of the gate insulating film interposed therebetween. A liquid crystal display device. The method of claim 1, And the gate insulating film has a plural-layer structure, and the insulating layer is composed of at least one layer thereof. The method of claim 2, And the insulating film is one layer formed on the most surface side of the plurality of layers constituting the gate insulating film. The method of claim 2, And said insulating layer is one layer formed on the side of the most transparent substrate of the plurality of layers constituting said gate insulating film. The method of claim 2, And said insulating layer is formed of the thinnest layer among the plurality of layers constituting said gate insulating film. The method of claim 1, And an edge of the thin portion of the insulating layer on the storage capacitor line is located inward of the edge of the storage capacitor line. The method of claim 1, And the gate insulating film has a thickness of 2500 to 5500 kPa, and the insulating layer has a thickness of 500 to 1500 kPa. The method of claim 1, An interlayer insulating layer is formed between the pixel electrode and the drain electrode, and a contact hole is formed in a portion of the interlayer insulating layer on the auxiliary capacitance line, and the pixel electrode and the drain electrode are electrically connected through the contact hole. The liquid crystal display device, characterized in that connected. The method of claim 8, And a reflecting film is formed on the surface or the back of the pixel electrode so as to cover the entire region of the thin film transistor and the storage capacitor line or the position corresponding to the pixel electrode. Disposing a plurality of scanning lines and storage capacitor lines arranged in parallel on the gate electrode on the transparent substrate in parallel with each other; Forming a gate insulating film to cover the entire surface on the transparent substrate; Thinning a portion of the gate insulating layer on the storage capacitor line to form an insulating layer having a thickness thinner than the periphery of the storage capacitor line; And Forming a storage capacitor by forming a drain electrode of the thin film transistor on the gate insulating film and extending the drain electrode of the thin film transistor to cover the insulating layer on the storage capacitor line. Method of manufacturing the device. The method of claim 10, The step of forming the insulating layer, Forming a semiconductor layer on the gate insulating film; Applying a photoresist to the surface of the semiconductor layer; Removing a photoresist of the storage capacitor forming portion on the storage capacitor line by using a halftone mask, leaving a thick photoresist at a position corresponding to the gate electrode, and leaving a thin photoresist at the other portion; Removing an exposed semiconductor layer of the first half storage capacitance forming portion by etching, and then removing a portion of the gate insulating film positioned in the storage capacitance forming portion to form an insulating layer having a thickness thinner than a peripheral gate insulating film; Removing the thin photoresist and leaving the photoresist only at a position corresponding to the gate electrode; Removing the exposed semiconductor layer by etching; And And removing the remaining photoresist. The method of claim 10, The step of forming the insulating layer includes a step of dividing the gate insulating film into a plurality of layers in a plurality of times, and a step of removing at least one layer therein. The method of claim 12, And the step of forming the insulating layer is a step of removing the first formed layer when the gate insulating film is divided into several layers to form a plurality of layers. The method of claim 12, And the step of forming the insulating layer is a step of dividing the gate insulating film several times to form a plurality of layers, and then removing the last formed layer. The method of claim 12, And the gate insulating film of the multilayer structure is formed by changing the substrate temperature for each layer using the same material. The method of claim 15, Wherein the substrate temperature is highest at the time of forming the first gate insulating film and sequentially lowered at the time of forming the gate insulating film thereafter. The method of claim 12, And the gate insulating film of the multilayer structure is formed by changing the components of the ambient atmosphere gas for each layer using the same material. The method of claim 10, Forming an interlayer insulating film to cover the drain electrode; Forming a contact hole in the interlayer insulating layer at a position where the drain electrode and the storage capacitor line overlap each other; And And forming a pixel electrode on the interlayer insulating layer so as to be electrically connected to the drain electrode through a contact hole. The method of claim 18, Before or after the pixel electrode is formed, forming a reflector on the entire surface of a position corresponding to the thin film transistor and the storage capacitor line or a position corresponding to the pixel electrode. Manufacturing method.

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