JPH0476091B2 - - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a liquid crystal display element, and more particularly, to a method for manufacturing a liquid crystal display element having a configuration in which an electrical signal is applied to each display electrode via an electrically insulating thin film.

BACKGROUND ART FIG. 1 is a plan view of a portion of a substrate 1 of a typical liquid crystal display device according to the prior art, and FIG.
FIG. 3 is a perspective view of a portion of the figure; A plurality of first conductors 2 are patterned on a substrate 1, and a first insulating film 3 is formed on the surface thereof to a thickness of 2000 Å to 4000 Å. To selectively cover the first insulating film 3,
A plurality of second conductors 4 are formed, and between the first conductor 2 and the second conductor 4 there is a second insulating film 5 of 300 mm.
It is formed with a thickness of Å to 700 Å. Here the second
The conductor 4, the second insulating film 5, and the first conductor 2 are a nonlinear resistance element (Metal-Insulator-Metal element, hereinafter referred to as a metal-insulator-metal element) having a so-called metal-insulator-metal structure.
(abbreviated as MIM element) 6.

Next, a display electrode 7 is formed to be electrically connected to the second conductor 4. Liquid crystal display elements are manufactured through these processes, but MIM as described above
Hereinafter, the liquid crystal display element including the element 6 will be abbreviated as an MIM type liquid crystal display element.

There are two major problems involved in manufacturing such MIM type liquid crystal display elements. The first point is related to mask alignment accuracy, and the second point is related to the size of display electrode 7. First, we will discuss the first problem regarding mask alignment accuracy. As shown in the first diagram, if the arrangement pitch L1 of the display electrodes 7 is 200 μm to 600 μm, the interval L2 between each display electrode 7 is 20 μm to 60 μm. In addition, the mask alignment accuracy when forming patterns such as the second conductor 4 is 1/4 to 1/1 of the width of the thinnest line to be formed.
Precision of 0 is required. Therefore, each display electrode 7
If the pitch L1 is 200 μm to 600 μm, the mask alignment accuracy in this case is required to be 2 μm to 6 μm.

The mask alignment accuracy of the photolithographic technology conventionally used for manufacturing liquid crystal display elements that do not include MIM elements is several tens of micrometers, and this accuracy has become unsuitable for manufacturing MIM type liquid crystal display elements. Therefore, high-precision photolithographic technology, which is used in manufacturing large-scale integrated circuits, is used, which is one of the factors that increases the cost of manufacturing MIM type liquid crystal display elements.

The second issue, the size of the display electrode 7, will be discussed. When manufacturing an MIM type liquid crystal display element using the conventional technology, a first conductor had to be disposed between display electrodes 7 as shown in the first diagram. Therefore, there is a problem in that the size of the display electrode 7 is limited.

Another conventional example having problems similar to those described above is JP-A-57-182779 (hereinafter referred to as the second conventional example).
and JP-A-57-179884 (hereinafter referred to as the third conventional example).

The second conventional example consists of a transparent electrode, an insulating film, and an MIM.
It shows a configuration in which the elements are formed in this order,
A configuration is shown in which the transparent electrode is electrically connected to one of the metals constituting the MIM element through a through hole provided in an insulating film. Also, the third
A conventional example shows an MIM element in which an oxide is formed over the entire surface. Both conventional examples have a problem in that the aperture ratio is low and excessively high positioning accuracy is required.

Purpose A first object of the present invention is to provide an improved method for manufacturing a liquid crystal display element that does not require extremely high precision during manufacturing, improves yield during manufacturing, and reduces manufacturing costs. The second purpose is to increase the area of the display electrodes to increase the proportion of the area occupied by the display electrodes on the display screen, thereby providing high display quality and electrical insulation properties. An object of the present invention is to provide a method for manufacturing a liquid crystal display element including a circuit with a thin film interposed therebetween.

Structure of the Invention The present invention is a method for manufacturing a liquid crystal display device, which is characterized by including the following steps A to E.

A. A first strip made of a metal material is placed on a glass substrate.
A plurality of conductors are formed.

B The first conductor is oxidized by an anodic oxidation method to form a first insulating film having a predetermined thickness.

C A second conductor made of a metal material and a peeling auxiliary layer are laminated to cover a plurality of formation regions where MIM elements are respectively formed on the first insulating film, and a peeling auxiliary layer is laminated and formed in each formation region.
Configures the MIM element.

D. A second insulating film made of an electrically insulating material is formed on the entire surface of the glass substrate, each of the peeling auxiliary layers is removed by a lift-off method, and a through hole is formed in each of the formation regions.

E. A plurality of display electrodes covering each of the through holes and electrically connected to the second conductor are formed in a matrix arrangement over the entire surface of the glass substrate.

According to the present invention, it is possible to cover the first insulating film and the second insulating film, which requires detailed mask alignment accuracy during manufacturing.
One is when a conductor is formed, and the other is when a display electrode is formed by covering the through hole. In the former case, the second
The conductor only needs to cover the first insulating film, and a mask alignment accuracy of several tens of μm is sufficient. In the latter case, the display electrode only needs to cover the through hole, so a mask alignment accuracy of several hundred μm is sufficient. In other words, the present invention eliminates the need to use excessively high-precision manufacturing technology, and the conventionally used photolithography technology with a mask alignment accuracy of several tens of micrometers is sufficient, and in this respect, the manufacturing process is simplified. It has the effect of being possible.

Further, the MIM element as a switching element used in the present invention is formed in a through hole formed in a second insulating film that insulates the display electrode and the second conductor.

Embodiment FIG. 3 is a perspective view showing a partial cross section of a liquid crystal display element according to the present invention, FIG. The figure is a perspective view of a portion of FIG. 4. In FIG. 3, substrates 10 and 10a are arranged parallel to each other and facing each other. A first conductor 11 is formed on the substrate 10, and a plurality of circuits including an MIM element 12 and a display electrode 13, which will be described later, are configured on the first conductor 11. Furthermore, an alignment film 14 is formed thereon.

A plurality of band-shaped electrodes 15 are formed on the surface of the substrate 10a, extending in parallel in a direction perpendicular to the extending direction of the first conductor 11 (vertical direction in FIG. 4). Each strip electrode 15 is arranged to face each display electrode 13 on the substrate 10, and each strip electrode 15 is arranged to face each display electrode 13 on the substrate 10.
and each display electrode 13 constitute a dot matrix display system. Strip electrode 15
An alignment film 14a is formed on the surface of the substrate 10a including the substrate 10a. A liquid crystal 16 is sealed between the alignment films 14 and 14a.

FIG. 6 is a plan view of a portion of the substrate 10 for explaining the method of manufacturing a liquid crystal display element according to the present invention. Figures 71 to 75 are Figures 61 to 65.
FIG. 3 is a cross-sectional view taken from a cutting plane line to be described later. Fig. 6 1 and section line A-A in Fig. 6 1
Please refer to FIG. 7 1, which is a sectional view taken from above. Substrate 10
A first conductor 11 is patterned thereon. The substrate 10 is made of borosilicate glass, for example.
The first conductor 11 is made of tantalum Ta, for example. Next, an electrically insulating thin film of tantalum pentoxide (Ta ₂ O ₅₎ is applied to the surface of the first conductor 11 using an anodic oxidation method.
The first insulating film 17 is formed with a thickness of Å to 700 Å.

Next, see FIG. 6 2, and the section line B- in FIG. 6 2.
Please refer to FIG. 72, which is a cross-sectional view seen from B. On the first insulating film 17, an MIM element 1, which will be described later,
2 is formed in the first conductor 11.
A second conductor 19 made of Ta is patterned using a photosensitive material such as photoresist so as to cover the second conductor 19 in a direction perpendicular to the extending direction (vertical direction in FIG. 6). At this time, the photoresist 20 on the second conductor is left as a peeling auxiliary layer without being peeled off.

Next, see FIG. 6 3 and the cutting plane line C- in FIG. 6 3.
Please refer to FIG. 7, which is a cross-sectional view taken from C. A second insulating film 21 is formed over the entire surface of the substrate 10 on which the second conductor 19 and the like are formed by the process described above.
form. At this time, the second insulating film 21 is formed of, for example, silicon dioxide SiO ₂ . At this time,
The second insulating film 21 is formed so as to overlap the remaining portion of the first insulating film 17 other than the formation region 18 . Therefore, current is prevented from flowing between the first conductor 11 and the display electrode 13 in areas other than the formation region 18.

Next, see FIG. 6 4 and the cutting plane line D- in FIG. 6 4.
Please refer to FIG. 74, which is a cross-sectional view seen from D. Photoresist 20 and second insulating film 21 on second conductor 19 are removed. At this time, a through hole 22 is formed in the second insulating film 21, and the second
This means that the conductor 19 is exposed.

Next, FIG. 6 5 and the cutting plane line E- in FIG. 6 5
Please refer to FIG. 75, which is a cross-sectional view seen from E. Through hole 2
2 to form a display electrode 13. At this time, the display electrode 13 is made of, for example, indium oxide In ₂ O ₃
The second conductor 19 is formed through the through hole 22.
to be electrically connected.

Substrate 10 realized by the manufacturing process described above
In the above configuration, the first conductor 1 is formed in the formation region 18.
1, the first insulating film 17, and the second conductor 19 are
The MIM element 12 is configured. Therefore, the display electrode 13 could be given an electrical signal only through the MIM element 12.

FIGS. 8 and 9 are diagrams illustrating a method of manufacturing a liquid crystal display element according to another embodiment of the present invention.
This embodiment is similar to the previous embodiment and corresponding parts are provided with the same reference numerals. FIG. 8 is a plan view of a part of the substrate 10, and FIGS. 91 to 95 correspond to FIGS. 81 to 85, and FIGS.
Each section line F-F, G-G, H-H, I-I,
FIG. 3 is a cross-sectional view taken along JJ.

What should be noted is the peeling auxiliary layer 23 formed in FIG. 8 2 and FIG. 9 2 . This peeling auxiliary layer 23
is formed, for example, from zinc oxide ZnO. 8th
The first conductor 11 and first insulating film 17 formed on the substrate 10 are coated as shown in FIGS. 1 and 9, and the second conductor is formed as shown in FIGS. 2 and 9. 19 and a peeling auxiliary layer 23 are formed. During this formation, techniques such as photoetching are used. When an organic material such as polyimide is used as the second insulating film 21, the curing process involves baking at a temperature of 300°C or higher;
For example, a photoresist has no resistance to such temperatures, and the photoresist melts, making it impossible to obtain the through holes 22.

On the other hand, the peeling auxiliary layer 23 formed of ZnO in this embodiment has resistance to the above-mentioned heat treatment, and can sufficiently form the desired through-holes 22.

Furthermore, when peeling off the second insulating film 21 formed on the substrate 10 as shown in FIGS. 8 and 9 (see FIGS. 8 and 9), the peeling auxiliary layer 23 is used as a mask. It can be used as
Next, as shown in FIG. 8 and FIG. 9, display electrodes 13 are formed in the same manner as in the previous embodiment. In this way, a desired MIM type liquid crystal display element can be obtained.

In the two embodiments described above, mask alignment accuracy is required during manufacturing when forming the second conductor 19 by covering the first insulating film 17 and when forming the through hole 22.
This is when the display electrodes 13 are formed by covering the substrate. In the former case, the second conductor 19 is the first insulating film 1
It is enough to cover 7, and the mask alignment accuracy is several tens of microns.
m is sufficient. In the latter case, the display electrode 13
Since it is sufficient to cover the through hole 22, a mask alignment accuracy of several 100 μm is sufficient. Therefore, the MIM type liquid crystal display element can be manufactured using the photolithographic technology used in manufacturing conventional liquid crystal display elements.

In addition, a display electrode 13 is superimposed on the first conductor 11.
Since the shape of the display electrode 13 is formed, the shape of the display electrode 13 can be prevented from being affected by the arrangement state of the first conductor 11 or the like.

Furthermore, since the peeling auxiliary layer 23 is used as a mask during the partial peeling process of the second insulating film 21, the manufacturing process can be simplified.

In the above embodiment, Ta was used as the material for the first conductor 11 and the second conductor 19, but other materials such as aluminum Al may also be used.

Further, in the above-described embodiment, the first insulating film 17 and the second insulating film 21 were formed using an anodic oxidation method, so they were made of tantalum oxide Ta ₂ O ₅ . However, in other embodiments, when forming using a vapor deposition technique or the like, other electrically insulating materials can be widely used.

Further, other photosensitive materials such as a photosensitive polyimide film may be used in place of the photoresist.

Although the display electrode 13 is made of In ₂ O ₃ , other materials such as tin oxide (SnO _{2 )} or Al may also be used.

Further, in the above-mentioned embodiment, the second conductor 19 and the display electrode 13 were formed separately, but in another embodiment, the second conductor 19 may be replaced in the process explained with reference to FIG. 6 4 and FIG. The display electrode 13 can be formed so as to cover the second insulating film 21. In this case, since the process of vapor depositing the second conductor 19 is not necessary, the manufacturing process can be simplified and the associated costs can be further reduced.

Effects As described above, according to the present invention, in the manufacturing process of a liquid crystal display element that includes a configuration in which electrical signals are applied through a thin film having electrical insulation properties, the accuracy is within several tens of micrometers to several hundred micrometers. That's enough.
Therefore, it is not necessary to use high-precision photolithographic technology used in the manufacture of large-scale integrated circuits, and costs can be reduced.
It is possible to improve the yield of manufactured liquid crystal display elements.

Furthermore, when the electrically insulating thin film on the second conductor is peeled off, it is only necessary to peel it off at the same time as the peeling auxiliary layer, thereby simplifying the manufacturing process and reducing precision.

In addition, since the display electrode is formed on top of the first conductor, the size of the display electrode is the same as that of the second conductor.
It is not limited by the conductor, so the display electrodes can be made sufficiently large, and the spacing between each display electrode can also be made small. As a result, a liquid crystal display element with high display quality can also be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a portion of a substrate 1 of a prior art liquid crystal display element, FIG. 2 is an enlarged perspective view of a portion of FIG. 1, and FIG. 3 is a perspective view showing a cross section of a liquid crystal display element according to the present invention. , FIG. 4 is a plan view of a portion of the substrate 10 shown in FIG. 3, FIG. 5 is an enlarged perspective view of a portion of FIG. 4, and FIGS. 6 and 7 explain the manufacturing process of the configuration shown in FIG. 4. FIGS. 8 and 9 are diagrams for explaining the manufacturing process of other embodiments of the present invention. 10... Substrate, 11... First conductor, 12...
MIM element, 13... display electrode, 17... first insulating film, 19... second conductor, 20... photoresist, 21... second insulating film, 23... peeling auxiliary layer.

Claims (1)

[Scope of Claims] 1. A method for manufacturing a liquid crystal display device, comprising the following steps A to E. A. A first strip made of a metal material is placed on a glass substrate.
A plurality of conductors are formed. B The first conductor is oxidized by an anodic oxidation method to form a first insulating film having a predetermined thickness. C A second conductor made of a metal material and a peeling auxiliary layer are laminated to cover a plurality of formation regions where MIM elements are respectively formed on the first insulating film, and a peeling auxiliary layer is laminated and formed in each formation region.
Configures the MIM element. D. A second insulating film made of an electrically insulating material is formed on the entire surface of the glass substrate, each of the peeling auxiliary layers is removed by a lift-off method, and a through hole is formed in each of the formation regions. E. A plurality of display electrodes covering each of the through holes and electrically connected to the second conductor are formed in a matrix arrangement over the entire surface of the glass substrate.