JPH11218783A - Production of thin-film element and production of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To embody the fine processing of contact holes and to improve the aperture ratio of a liquid crystal display device having high fineness and high density by improving the alignment accuracy of a conductive thin film to pattern shapes at the time of forming the contact holes in a photpsensitive resin film insulating the conductive thin film. SOLUTION: The photosensitive acrylic resin film 12 of the region [B] smaller than the pattern of a source electrode 28 in a source electrode 28 region is exposed and is then subjected to development by an alkaline soln. With the exposed region [B] removed by etching as a start, the alkaline soln. is penetrated between the photosensitive acrylic resin film 12 and the source electrode 28 and the photosensitive acrylic resin film 12 of the shape nearly resembling the shape of the pattern region [A] of the source electrode 28 by the weakness of the adhesion property to the alkaline soln. between the photosensitive acrylic resin film 12 and the source electrode 28 is peeled and removed, by which the contact hole 31 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a contact hole formed above a conductive thin film of a thin film element in which a conductive thin film is insulated by a photosensitive resin film. Further, the present invention relates to a liquid crystal display device having a matrix-shaped pixel electrode formed above a switching element via a photosensitive resin film, and a method of manufacturing the liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, the resolution of pixels of a liquid crystal display device has been increased.
With the increase in density, fine processing technology for constituent materials is required. Higher definition of pixels is achieved by increasing the number of pixels per unit area in the display area of the liquid crystal display device. However, this increase in the number of pixels increases the number of wiring patterns per unit area. And the aperture ratio of the pixel is reduced as a result.

As one means for improving the conflicting relationship of reducing the aperture ratio in order to obtain such a high definition pixel, as disclosed in Japanese Patent Application Laid-Open No. 9-236826, There is a method of improving the aperture ratio by disposing the pixel electrode above the wiring with a thick insulating film interposed therebetween. The insulating film used for such a structure in which the pixel electrodes are arranged above the wirings has a role of improving the apparent aperture ratio as well as eliminating display unevenness of the liquid crystal display device due to unevenness of the wiring layer. Also plays the role of a flattening layer. For this reason, conventionally, a photosensitive organic resin film, which can be easily thickened, is generally used as an insulating film interposed between the wiring and the pixel electrode.

In an array substrate having a structure in which a pixel electrode is arranged above a wiring via an insulating film, a hole called a contact hole connecting the pixel electrode and the wiring is formed in the insulating film. These contact holes provide electrical connection between a wiring called a pixel contact and a pixel electrode.

[0005]

Conventionally, an array substrate in which pixel electrodes are arranged above wirings with an insulating film interposed between the wirings and the pixel electrodes through contact holes formed in the insulating film. However, in accordance with the demand for miniaturization of the constituent material accompanying the high definition of the liquid crystal display device, it is required to establish a technique for more accurate alignment with the wiring when forming the pattern of the contact hole.

However, the photosensitive resin film, which is an insulating film, is required to be thickened to about 1 to 6 μm in order to planarize the array substrate. There is a problem that the depth of focus of the exposure alignment by the lens becomes deep, and it is difficult to perform high-precision alignment with the lower alignment mark.

Furthermore, the amount of exposure required for patterning a photosensitive resin film having a large thickness of 1 to 6 μm, that is, the time required for exposure, is several tens of times that of a general photoresist. The problem has arisen.

[0008] Therefore, in order to solve the former problem, the mechanical accuracy of the movement of the stage on which the substrate coated with the photosensitive resin film is mounted is improved, or the positioning provided so as to face the stage is performed. It improves the mechanical accuracy of the lens movement in the focal direction of the camera, and increases the reliability of the autofocus to improve the position accuracy. For the latter problem, the overall manufacturing time can be reduced by shortening the time from the end of exposure of the photosensitive resin film to the start of development.
A method of shortening the exposure time by adjusting the development time, shower pressure, and the like has been studied.

However, there is a limit in improving the reliability of autofocusing by improving the mechanical accuracy of the stage or lens movement as a measure against the former positioning accuracy. When the film thickness is 1 μm or more, the depth of focus is reduced. On the other hand, while the problem that the depth becomes too deep to obtain sufficient accuracy still remains, if a re-adjustment occurs due to an error during autofocusing, there also arises a problem that it takes time for alignment. As for the latter measure for shortening the exposure time, there has been a possibility that the developing performance may be reduced as a result.

In view of the above, the present invention has been made to solve the above-mentioned problems, and it is possible to obtain a high alignment accuracy without requiring a long time for alignment of a contact hole pattern, and to increase the thickness of a photosensitive resin film. It is another object of the present invention to provide a method of forming a contact hole in a thin film element, a liquid crystal display device, and a method of manufacturing a liquid crystal display device, which can perform efficient patterning without deteriorating developing performance.

[0011]

According to the present invention, as a means for solving the above-mentioned problems, a first step of patterning a conductive thin film having a predetermined pattern on an insulating substrate, A second step of forming an insulating photosensitive resin film, a third step of forming a contact hole on the conductive thin film by immersing the photosensitive resin film in a developer after exposing the photosensitive resin film, A fourth step of forming an electrode pattern connected to the conductive thin film via a contact hole, wherein the adhesion between the photosensitive resin film and the conductive thin film with respect to a developing solution is the photosensitive sensitivity. A method of dipping the photosensitive resin film in a developing solution after exposing to an area smaller than the conductive thin film pattern in the third step, which is weaker in adhesion to a developing solution between the resin film and the insulating substrate. It is.

According to the present invention, as a means for solving the above problems, a switching element arranged at an intersection of a signal line arranged on an insulating substrate and a scanning line arranged to intersect the signal line is provided. An array substrate having pixel electrodes connected to a connection region formed of a conductive thin film having a predetermined pattern and arranged in a matrix, a counter substrate having a counter electrode and facing the array substrate, and the array substrate and the counter A method of manufacturing a liquid crystal display device having a liquid crystal composition sealed between substrates, a first step of patterning the signal lines, the scanning lines, and the switching elements on the insulating substrate; A second step of forming an insulating photosensitive resin film covering the lines, the scanning lines, and the switching elements; and after exposing the photosensitive resin film to light. A third step of forming a contact hole on the conductive thin film by immersing in an image liquid; and a fourth step of forming an electrode pattern connected to the conductive thin film via the contact hole. The adhesiveness to the developer between the photosensitive resin film and the conductive thin film is weaker than the adhesiveness to the developer between the photosensitive resin film and the insulating substrate, and in the third step, After exposing an area smaller than the conductive thin film pattern, the photosensitive resin film is immersed in a developer.

With such a configuration, the present invention allows a developer to penetrate between the conductive thin film and the photosensitive resin film in the conductive thin film pattern region, and utilizes the weak adhesion between the two films. In the pattern area of the conductive thin film, the photosensitive resin film in the area substantially similar in shape to the conductive thin film pattern is peeled off, so that the alignment accuracy can be improved regardless of the increase in the thickness of the photosensitive resin film. It is intended to perform contact hole patterning which is excellent and can shorten the exposure time without deteriorating the developability.

Further, according to the present invention, the photosensitive resin film in a region smaller than the pattern of the conductive thin film is exposed, as a trigger for penetrating the developer between the conductive thin film and the photosensitive resin film,
At the time of development, an alkaline solution is permeated from this exposed area, and in the pattern area of the conductive thin film, a region almost similar in shape to the pattern of the conductive thin film is peeled and removed.
The contact hole patterning with excellent alignment accuracy is performed regardless of the increase in the thickness of the photosensitive resin film.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. Reference numeral 10 denotes a liquid crystal display panel of an active matrix type liquid crystal display device.
1 and an array substrate 14 on which the pixel electrodes 13 are patterned through a photosensitive acrylic resin film 12 which is a photosensitive resin film which is a photosensitive resin film formed above the TFT 11, the signal line 26, and the scanning line 22. The liquid crystal composition 17 is sealed between the substrate 16 and the substrate 16.

In the array substrate 14, a semiconductor layer 20 having an active layer 20a and a drain region 20b and a source region 20c obtained by doping the active layer 20a with impurities is formed on a transparent insulating substrate 18 by patterning. 2
On molybdenum-tungsten (MoW) via a gate insulating film 21 made of a silicon oxide (SiO ₂ ) thin film
A gate electrode 23 made of an alloy thin film and integrated with the scanning line 22 is formed.

Further, an interlayer insulating film 24, which is an insulating substrate made of silicon oxide (SiO ₂ ), is formed, and a molybdenum-tungsten (MoW) alloy thin film having a thickness of 1000 angstroms is supplied with a video signal. A drain electrode 27 integral with the signal line 26 and a source electrode 28 as a connection region are formed in a predetermined pattern, and the drain region 20 is formed through contact holes 27a and 28a, respectively.
b, connected to the source region 20c to form the TFT 11. On the TFT 11 and the signal line 26 formed, a pixel electrode 13 made of indium tin oxide (hereinafter referred to as ITO) is pattern-formed via a photosensitive acrylic resin film 12 having a thickness of 2 μm. Is connected to the source electrode 28 via a contact hole 31 formed in a substantially similar shape to the source electrode 28. Here, the interlayer insulating film 24 and the photosensitive acrylic resin film 12
The adhesion between the source electrode 28 and the photosensitive acrylic resin film 12 is weaker than the adhesion between the source electrode 28 and the photosensitive acrylic resin film 12. 32 is an alignment film.

The opposing substrate 16 has an opposing electrode 34 made of ITO and an alignment film 36 on a transparent insulating substrate 33. Reference numerals 37 and 38 denote polarizing plates.

Next, a method of manufacturing a contact hole 31 for electrically connecting the pixel electrode 13 to the source electrode 28 on the array substrate 14 will be described. First, the TFT 11 is formed on the transparent insulating substrate 18. The source electrode 28 of the TFT 11 is formed on the interlayer insulating film 24 by a molybdenum-tungsten (MoW) alloy thin film 2 as shown in FIG.
8 'was formed to a thickness of 1000 Å using a sputtering apparatus, and then RIE using [SF6] gas by photolithography as shown in FIG.
(Reactive-On Etching) A pattern is formed in a predetermined shape through a first step of etching using an apparatus.

Next, as shown in FIG.
A photosensitive acrylic resin film 12 on a TFT 11 having
Is applied to a thickness of 2 μm by spin coating, and the second step is performed. Thereafter, as shown in FIG. 3D, in the pattern region [A] of the source electrode 28, the photosensitive acrylic resin film 12 in a region [B] smaller than the pattern region [A] is formed using a photomask 40. Exposure. In addition,
Molybdenum-tungsten (MoW) alloy thin film pattern
Different photomasks may be prepared for the photomask used for the patterning and the photomask used for the patterning of the photosensitive acrylic resin, or the same photomask may be used.

Next, the exposed photosensitive acrylic resin film 1
2 is developed with an alkaline solution. During the development of the photosensitive acrylic resin film 12, the photosensitive acrylic resin film 1 in the pattern region [A] of the source electrode 28 starts from the region [B] etched away by the alkaline solution.
The alkaline solution permeates between 2 and the source electrode 28,
The permeated alkaline solution gives a trigger to peel the photosensitive acrylic resin film 12 on the source electrode 28 in the region [A]. That is, at the time of development, the photosensitive acrylic resin film 12 on the source electrode 28 is peeled off as shown in FIG. 3 (e) due to the weak adhesion between the source electrode 28 and the photosensitive acrylic resin film 12 with an alkaline solution. The third step is performed in which the contact hole 31 having a substantially similar shape to the source electrode 28 is formed on the source electrode 28 after being removed. Here, the term "adhesion" means the peeling resistance of the photosensitive acrylic resin with respect to the developing time and the concentration of the developing solution. On the interlayer insulating film 24, since the adhesion between the interlayer insulating film 24 and the photosensitive acrylic resin film 12 is high, the photosensitive acrylic resin film 12 does not peel off.

Next, after the photosensitive acrylic resin film 12 is baked, ITO is deposited on the photosensitive acrylic resin film 12 by using a sputtering device as shown in FIG. 13, and the fourth step is completed.
Further, an alignment film 32 is applied to complete the array substrate 14.

Then, a sealant (not shown) is applied to the periphery of the array substrate 14 and a spacer (not shown) is sprayed on the pixel area so that the array substrate 14 and the counter substrate are opposed so that the alignment films 32 and 36 face each other. The liquid crystal display panel 10 is manufactured by injecting the liquid crystal composition 17 into the gap between the substrates 14 and 16 and attaching the polarizing plates 37 and 38 thereto. Further, an external drive circuit (not shown) or an internal drive circuit formed on the same substrate is connected, and a backlight or a projection device is arranged to complete a liquid crystal display device.

According to this structure, although the photosensitive acrylic resin film 12 is made thicker in order to obtain good insulation and flatness, the distance between the source electrode 28 and the photosensitive acrylic resin film 12 is increased. The photosensitive acrylic resin film 1 above the source electrode 28 is exposed by exposing a region smaller than the source electrode 28 in the region of the source electrode 28 and developing with an alkaline solution by utilizing the weak adhesion to the alkaline solution.
2 can be peeled and removed in a shape substantially similar to the source electrode 28,
A contact hole 31 with high positioning accuracy with respect to the source electrode 28 can be formed. Therefore, the source electrode 2 can be used without performing a time-consuming alignment operation using a stage or a camera having a high mechanical precision of movement as in the related art.
The contact hole 31 can be easily finely processed in accordance with the pattern shape of No. 8, and a high aperture ratio can be maintained even in a high-definition and high-density liquid crystal display device, and a high-quality image with good contrast can be obtained.

In addition, the exposed area for forming the contact hole 31 is [B] in which the photosensitive acrylic resin film 12 is peeled off due to the weak adhesion between the source electrode 28 and the photosensitive acrylic resin film 12 to an alkaline solution. The exposure time can be shortened compared to the conventional case where the entire contact hole is exposed by irradiating the exposure light in a narrow area, because the exposure area is enough to give Exposure time can be reduced irrespective of the thickness of the film 12, and productivity can be improved.

Next, a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the interlayer insulating film in the first embodiment has a two-layer structure, an upper interlayer insulating film is patterned, and a source electrode is patterned on the interlayer insulating film. The other parts are the same as those of the first embodiment, and therefore, the same parts are denoted by the same reference numerals and description thereof will be omitted.

In this embodiment, as shown in FIG. 6A, a first interlayer insulating film 52 is formed below the source electrode 51 and on the gate electrode 23, and furthermore, silicon nitride (SiN)
The second interlayer insulating film 53 made of
A film is formed to a thickness of 000 angstroms. Next, FIG.
As shown in (b), the second interlayer insulating film 53 is patterned into a predetermined shape by photolithography, and [CF
4] CDE (chemical dry etching) using gas
Using a device, a contact hole 54 for a source electrode is formed in the second interlayer insulating film 53.

Next, as in the first embodiment, FIG.
As shown in (c), the source electrode 56 connected to the source region 20c via the contact hole 56a is formed in a predetermined pattern, and the TFT 11 is formed. However, the source electrode 5
6 is formed in a concave shape along the source electrode contact hole 54 of the second interlayer insulating film 53.

After forming the TFT 11 and the signal line 26, the photosensitive acrylic resin film 12 is formed as shown in FIG.
Is applied, and the region [B] is exposed as shown in FIG. Next, development is carried out with an alkaline solution, and the alkaline solution penetrates between the photosensitive acrylic resin film 12 and the source electrode 56 by using the region [B] which has been removed by etching, so that the source electrode 56 and the photosensitive acrylic resin film 12 6A, the photosensitive acrylic resin film 12 on the source electrode 56 is peeled off due to the weak adhesiveness to the alkaline solution, and the source electrode 56 has a substantially similar shape to the source electrode 56 as shown in FIG. Is formed. Further, after firing, the pixel electrode 58 as shown in FIG.
Is formed in a pattern to make conduction with the source electrode 56 having a concave depression at the bottom surface of the contact hole 57. Thereafter, an array substrate 59 is formed in the same manner as in the first embodiment,
The liquid crystal display panel 60 is manufactured, and the liquid crystal display device is completed.

According to this structure, the photosensitive acrylic resin film 12 is removed by etching in order to obtain excellent flatness and excellent insulating properties as in the first embodiment, despite the fact that the photosensitive acrylic resin film 12 is thickened. By exfoliating and removing the photosensitive acrylic resin film 12 above the source electrode 56 using the region [B], a contact hole 57 having a substantially similar shape to the source electrode 56 can be formed. Therefore, there is no need to perform a time-consuming alignment operation using a stage or a camera having high mechanical precision of movement as in the conventional case, and the contact hole 57 can be easily finely processed in accordance with the pattern shape of the source electrode 56, and high A high aperture ratio can be maintained even in a fine and high-density liquid crystal display device, and a high-quality image with good contrast can be obtained.

In addition, since the exposure area for forming the contact hole 57 may be an area which provides a trigger for peeling and removing the photosensitive acrylic resin film 12, the conventional exposure area can be used regardless of the thickness. As compared with the case where the entire contact hole is exposed, the exposure time can be reduced,
Productivity can be improved.

Further, first and second two-layer interlayer insulating films 5
2 and 53, and a concave source electrode contact hole 54 is formed in the second interlayer insulating film 53 to form a source electrode 5
6, a source electrode 56 is formed.
And the pixel electrode 58 can be connected with a taper, and the disconnection of the pixel electrode caused by the contact hole 58 can be suppressed.
The yield at the time of manufacturing can be improved. Moreover, the source electrode 56
The taper angle at the connection portion of the pixel electrode 58 can be easily obtained by adjusting the size of the source electrode contact hole 54 formed in the second interlayer insulating film 53.

The present invention is not limited to the above-described embodiment, but can be changed without departing from the spirit of the present invention. For example, the material of the conductive thin film or the photosensitive resin film is arbitrary. Although the thickness is not limited, for example, the thickness of the photosensitive resin film is required to be at least 3.9 μm in order to flatten the step of the conductive thin film of 3 μm. In order to reduce unevenness when coating, the thickness of the conductive thin film is preferably set to 1 / 1.3 or less of the photosensitive resin film. If the thickness of the photosensitive resin film is 1 μm or more, at which autofocus of the camera becomes a problem due to a large depth of focus, the effect of the present invention can be improved as compared with the pattern alignment accuracy using a conventional camera. That is, the improvement of the pattern alignment accuracy can be more effectively exhibited.

The material of the interlayer insulating film, which is an insulating substrate, may be silicon nitride oxide (SiOxNy) or the like, and the thickness thereof is not limited. In order to suppress the occurrence of crosstalk due to coupling, the second interlayer insulating film in which the contact hole for the source electrode is formed must be formed in a thickness of 3000 to 10
Preferably, the thickness is set to 2,000 angstroms.

[0035]

As described above, according to the present invention, a photosensitive resin film is formed on a conductive thin film formed in a predetermined pattern, and then an alkaline solution is permeated between the two films. The photosensitive resin film above the conductive thin film area can be peeled off and removed in a shape almost similar to the conductive thin film by utilizing the weak adhesion between the two films to an alkaline solution, and the contact hole with high positioning accuracy can be patterned. From what you can do,
There is no need for a stage or camera with high mechanical precision of movement as before, and no time for positioning is required,
The fine workability of the contact hole can be improved, and even in a high-definition and high-density liquid crystal display device, a high aperture ratio and a good contrast can be obtained, and the display quality can be improved. In addition, when forming the contact hole, not only when the alkaline solution is allowed to penetrate between the conductive thin film and the photosensitive resin film without performing the exposure, but also when the exposure is performed, the alkaline solution is formed between the conductive thin film and the photosensitive resin film. It only exposes a part of the conductive thin film area in order to make the solution penetrate, and the exposure time can be shortened compared with the conventional one. Drop can be prevented.

[Brief description of the drawings]

FIG. 1 is a partial schematic cross-sectional view illustrating a liquid crystal display panel according to a first embodiment of the present invention.

FIG. 2 is a partial schematic plan view showing the array substrate according to the first embodiment of the present invention.

3A and 3B show a contact hole forming step according to the first embodiment of the present invention. FIG. 3A shows a state in which a molybdenum-tungsten (MoW) alloy thin film is formed on the interlayer insulating film, and FIG. Shows a state in which the source electrode is patterned, (c) shows a state in which a photosensitive acrylic resin film is formed on the source electrode and the interlayer insulating film, and (d) shows a state in which the photosensitive acrylic resin film is formed. FIG. 3E is a schematic explanatory view showing an exposure state, FIG. 4E shows a state in which a contact hole is patterned in the photosensitive acrylic resin film, and FIG.

FIG. 4 is a partial schematic cross-sectional view showing a liquid crystal display panel according to a second embodiment of the present invention.

5A and 5B show a contact hole forming step according to a second embodiment of the present invention, wherein FIG. 5A shows a state in which first and second interlayer insulating films are formed, and FIG. (C) shows a state in which a source electrode contact hole is patterned in the interlayer insulating film, (c) shows a state in which the source electrode is patterned, and (d) shows a photosensitive layer on the source electrode and the interlayer insulating film. The state in which the acrylic resin film is formed is shown,
(E) shows an exposure state of the photosensitive acrylic resin film,
(F) is a schematic explanatory view showing a state in which contact holes are patterned in the photosensitive acrylic resin film, and (g) is a schematic explanatory view showing a state in which the pixel electrodes are patterned.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display panel 11 ... TFT 12 ... Photosensitive acrylic resin film 13 ... Pixel electrode 14 ... Array substrate 16 ... Counter substrate 17 ... Liquid crystal composition 20 ... Semiconductor layer 21 ... Gate insulating film 22 ... Scanning line 23 ... Gate electrode 24 ... interlayer insulating film 26 ... signal line 27 ... drain electrode 28 ... source electrode 31 ... contact hole 40 ... photomask

Claims (4)

[Claims] A first step of patterning a conductive thin film having a predetermined pattern on an insulating substrate; a second step of forming an insulating photosensitive resin film over the conductive thin film;
A third step of forming a contact hole on the conductive thin film by immersing the photosensitive resin film in a developing solution after exposure, and forming an electrode pattern connected to the conductive thin film via the contact hole. And the adhesiveness to the developing solution between the photosensitive resin film and the conductive thin film is higher than the adhesiveness to the developing solution between the photosensitive resin film and the insulating substrate. And dipping the photosensitive resin film in a developing solution after exposing a region smaller than the conductive thin film pattern in the third step. 2. The method according to claim 1, wherein the development of the photosensitive resin film is performed with an alkaline solution. 3. A connection region comprising a conductive thin film having a predetermined pattern of switching elements arranged at intersections of signal lines arranged on an insulating substrate and scanning lines arranged to intersect the signal lines. An array substrate having pixel electrodes connected and arranged in a matrix, a counter substrate having a counter electrode and facing the array substrate, and a liquid crystal composition sealed between the array substrate and the counter substrate. A method of manufacturing a liquid crystal display device, comprising: a first step of pattern-forming the signal lines, the scanning lines, and the switching elements on the insulating substrate;
A second step of forming an insulating photosensitive resin film covering the signal lines, the scanning lines, and the switching elements; and immersing the photosensitive resin film in a developer after exposing the photosensitive resin film to the conductive thin film. A third step of forming a contact hole thereon, and a fourth step of forming an electrode pattern connected to the conductive thin film through the contact hole, wherein the photosensitive resin film and the conductive The adhesiveness to the developing solution between the thin film and the photosensitive resin film is weaker than the adhesiveness to the developing solution between the insulating substrate and the insulating substrate, and in the third step, the area is smaller than the conductive thin film pattern. A method of manufacturing a liquid crystal display device, comprising immersing the photosensitive resin film in a developer after exposure. 4. The method according to claim 3, wherein the development of the photosensitive resin film is performed with an alkaline solution.