JPH0643494A - Production of electrooptical device - Google Patents

Abstract

PURPOSE:To improve electrical characteristics by connecting electrical connections to wirings different from the wirings participating in driving of nonlinear elements and cutting the electrical connections by hot etching. CONSTITUTION:Inter-picture element wiring 34, 35 respectively serve as common electrodes and potentials for anodic oxidation are supplied from the inter-picture element wiring 34, 35 to floating parts 63, 64 respectively in the case of anodic oxidation of the floating parts 63, 64 and formation of insulator films at their ends in forming the nonlinear elements. Namely, the floating parts 63 are electrically connected through conductors 73 not from the inter-picture element wiring 33 participating in driving of the nonlinear elements 103, 104 but from the adjacent inter-picture element wiring 34. The floating parts 64 are connected in the same manner. The conductors 73, 74 are removed by photoetching the parts of apertures 83, 84 after the end of the anodic oxidation of the floating parts 63, 64.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electro-optical device such as a liquid crystal display device, and more specifically to a matrix of pixel electrodes and a non-linear element for driving the pixel electrodes on one of a pair of substrates sandwiching a liquid crystal layer. The present invention relates to a method for manufacturing electro-optical devices arranged in a line.

[0002]

2. Description of the Related Art A conventional electro-optical device having the above-mentioned nonlinear element will be described by taking a liquid crystal display device as an example.

FIG. 8 is a plan view of a part of a substrate having a non-linear element (hereinafter referred to as an element substrate) in a conventional liquid crystal display device of this type, and FIG. 9 is an enlarged sectional view taken along line cc in FIG. is there. In the figure, 1 is a substrate, 2 is the substrate 1
A first conductor made of Ta (tantalum) or the like provided above,
3 is an insulator made of TaOx (tantalum oxide) or the like, 4 is a second conductor made of Cr (chrome) or the like, and 5 is a pixel electrode. The first conductor 2, the insulator 3, and the second conductor 4 form a metal insulator metal (M) as a non-linear element 10 for driving a pixel (pixel electrode).
(etal Insulator Metal, hereinafter abbreviated as MIM).

In particular, the MIM in the illustrated example uses a so-called lateral MIM structure in which only the side surface of the first conductor 2 is used as the nonlinear element 10. That is, this lateral M
The IM is an insulator that covers the side surface of the conductor by covering a surface other than the side surface of the first conductor 2 forming the nonlinear element with a thick insulator (hereinafter also referred to as a barrier layer) 3b as shown in FIG. It has an electric resistance higher than that of 3a so as not to function as a non-linear element. With such a structure, the area of the non-linear element can be made extremely small, and this is a very effective technology for increasing the density and definition of the liquid crystal display device using the MIM as the non-linear element for the pixel. .

Next, an example of a manufacturing process of the above element substrate will be described with reference to FIG. A) First, the first conductor 2 is film-formed on the transparent substrate 1.
(FIG. 10 (a)). B) The conductive film is formed by photoetching to form the first conductor 2 (FIG. 7B). C) The insulator 3 is film-formed on the upper surface of the transparent substrate 1 including the first conductor 2 ((c) of the same figure). D) The barrier layer 3b is formed by performing photoetching for leaving the insulator 3 on the surface of the conductor other than the side surface of the first conductor 2 (FIG. 3D). E) An insulator 3a, which serves as an insulator of the nonlinear element, is film-formed on the side surface of the first conductor 2 ((e) in the figure). F) Next, the second conductor 4 and the pixel electrode 5 are respectively film-formed, and are formed by photoetching ((f) in the same figure).

First conductor 2 formed as described above
And, the overlapping portion of the insulator 3a and the second conductor 4 on the side surface thereof constitutes the MIM as the nonlinear element 10. In addition, in the step (e), the method of depositing the insulator 3a is performed by anodic oxidation, thermal oxidation, sputtering, or the like. For example, in the case of anodic oxidation, an insulator 3a which is a thin TaOx film as an insulating layer is formed on the side surface of the material of the first conductor 2, for example, Ta. In the case of anodic oxidation, the first conductor 2 must be electrically connected to the common electrode in order to apply a potential to the first conductor 2. When the nonlinear element 10 shown in FIGS. 8 and 9 is formed, since the first conductor 2 is formed up to the end of the substrate 1, it is possible to easily apply a potential.

As the conductors 2 and 4 used in the MIM element, Ta, Al, Au, ITO, NiCr + Au, ITO + Cr and the like are well known. Insulator 3
(3a) includes TaOx, SiOx, SiNx, S
iOxNy, TaNx, ZnOx and the like are well known. As the barrier layer 3b, there is also known a material using an organic film such as polyimide in addition to the inorganic material used for the insulator. The most well-known structure as the MIM element is Ta (tantalum) for the first conductor 2, TaOx (tantalum oxide) for the insulator 3, and Cr for the second conductor 4.
(Chromium) is used.

However, in the structure of the conventional liquid crystal display device shown in FIGS. 8 and 9, the liquid crystal is deteriorated by the DC component generated by the polarity difference of the MIM element, and a high quality image can be obtained as the liquid crystal display device. It had the problem of not having it. In addition, there is a big problem that the liquid crystal is deteriorated and the reliability of the liquid crystal display is low. In particular, since the polarity difference of the MIM element changes depending on the temperature, there is a big problem that it cannot be controlled during driving. In order to solve the problem, for example, as shown in FIGS. 11 and 12, a liquid crystal display device having two non-linear elements in each pixel electrode 5 and having no polarity difference is considered. In addition, although it is considered that the same effect is produced when the non-linear elements are arranged in parallel, FIG. 11 is a plan view of the element substrate when two kinds of non-linear elements are connected in series, and FIG. 6 is an enlarged cross-sectional view taken along line cc in FIG. In the figure, the signal path is from the second conductor 4 on the left side in FIG.
The second conductor 4, the insulator 3a, and the first conductor 2
1 and the first conductor 21, the insulator 3a, and the second conductor 40.
It is input to the pixel electrode 5 via the second non-linear element 102 composed of. The same is true when the second conductor and the first conductor are replaced. Although the signal for driving the pixel electrode 5 is input through the conductor 4, it may be connected to the conductor 4 through the conductor 2 formed thereunder.

13 and 14 show an example of a liquid crystal display device in which non-linear elements are arranged in parallel to eliminate the polarity difference. FIG.
14A is a plan view of the element substrate, and FIGS. 14A and 14B are enlarged cross-sectional views taken along lines aa and bb in FIG. 13, respectively.

A portion indicated by 101 in FIG. 14A and a portion indicated by 102 in FIG. 14B are first and second non-linear elements (MIM elements), respectively. The signal path through the elements 101 and 102 is as follows.

In the signal path passing through the first nonlinear element 101, the signal input to the second conductor 4 enters the first conductor 2 through the contact hole 11 and the first conductor 2
And a first insulator 3a and a second conductor 4
After passing through the non-linear element 101, the voltage is directly applied to the pixel electrode 5, and is applied to the pixel electrode 5 via the insulator 3a and the first conductor 21 used for the second non-linear element 102. The route is branched at the branch point 13. In the signal path passing through the second non-linear element 102, the signal input to the second conductor 4 is supplied to the second conductor 4 and the insulator 3a.
And is applied to the pixel electrode 5 through the second non-linear element 102 composed of the first conductor 2 and the second non-linear element 102.

In the method of manufacturing a liquid crystal display device having a plurality of non-linear elements as shown in FIGS. 12 and 14, the conductor 21 is finally insulated from the pixel electrode 5 and the conductor 4. Must be manufactured as described above (the conductor 21 is in an electrically floating state). But,
In the step of forming the nonlinear elements 101 and 102, when the anodic oxidation method is selected as the method of forming the insulator 3a, it is necessary to apply a constant potential to the conductor 21 from the outside. For that purpose, it is necessary to once form a conductor pattern electrically connected to the common electrode on the conductor 21 and remove the conductor pattern after the anodic oxidation process is completed. The present invention is subjected to anodization as described above,
It is also an object of the present invention to provide a manufacturing method for finally forming an electrically floating conductor.

[0012]

According to the present invention, a plurality of pixel electrodes and a non-linear element for driving each pixel electrode and each pixel electrode are provided on one of a pair of substrates sandwiching a liquid crystal layer. Of the first conductor, the insulator, and the second conductor, the non-linear element having a wiring arranged in the first conductor, the insulator, and the second conductor. A step of cutting the electrical connection between the first conductor and the wiring after forming the insulator whose overlapping portion has non-linearity in current-voltage characteristics by anodic oxidation of the first conductor In a method of manufacturing an electro-optical device such as a liquid crystal display device, the electrical connection is connected to a wiring different from a wiring involved in driving a nonlinear element, and the electrical connection is cut by photoetching. It is a method of manufacturing a device.

[0013]

Embodiments will be described in detail below based on embodiments. FIG. 1 is a plan view of the liquid crystal display device and corresponds to FIG. 11 (except that the positions of the two nonlinear elements are linear arrangements). Reference numerals 33, 34 and 35 denote conductive inter-pixel wirings, and reference numerals 53 and 54 denote adjacent pixel electrodes. The pixel electrode 53 is driven by a signal from the inter-pixel wiring 33 or the conductor 43 formed thereon. Reference numerals 63 and 64 denote floating portions, which correspond to the conductor 21 in FIGS. 11 and 12, and nonlinear elements are formed at their ends 103, 104, 105 and 106 in the subsequent manufacturing process. In forming the non-linear element, the floating portions 63 and 64 are anodized, and the ends thereof are formed as shown in FIG.
When the insulator 3a as shown in (e) is applied as a film, the inter-pixel wirings 34 and 35 serve as common electrodes, and the floating portions 63 and 64 are anodized from the inter-pixel wiring 34 and the inter-pixel wiring 35, respectively. The electric potential of is supplied. That is, the floating portion 63 is composed of the nonlinear elements 103, 1
Electrical connection is not made from the inter-pixel wiring 33 involved in driving 04, but from the adjacent inter-pixel wiring 34 (which is originally used for the purpose of driving the pixel electrode 54) through the conductor 73. The same applies to the floating portion 64. After the anodic oxidation of the floating portions 63 and 64 is completed, the conductors 73 and 74 are closed by the closed portions 83 and 8.
4 is removed by photoetching. The floating portion 63 is electrically connected not to the conductor 33 but to the adjacent conductor 34 for the following reason.

Even after the conductor 73 is removed by etching the closed portion 83 by photoetching, the electrical connection resistance of the closed portion 83 including the portion where the conductor 73 was present is different from that of another portion such as the conductive portion. It is inevitably lower than that of the non-patterned portion 85 in which the body pattern is not formed (the amount of electrical leakage differs by one digit).
Therefore, even if the floating portion 63 is connected to the inter-pixel wiring 33 via the position of the non-patterned portion 85 and the portion is later removed by photoetching or the like, the electric insulation resistance of the portion must be lowered. This means that the non-linear elements 103 and 104 are connected to the conductor 43 (or the inter-pixel wiring 3
In the case of driving in 3), the influence of electric leak is large and it becomes extremely inconvenient. Therefore, it is useful that the floating portion 63 is electrically connected to the adjacent inter-pixel wiring that is not involved in driving the formed nonlinear element. Further, the longer the distance is, the smaller the influence of the electric leak is. Therefore, the length of the conductor 73 is preferably larger than the distance between the floating portion 63 and the inter-pixel wiring 33.

2 to 5 are explanations in which the method of taking the connection of the floating part from the wiring between the adjacent pixels which is not involved in the driving of the non-linear element is applied to the manufacturing method of the liquid crystal display device in which two non-linear elements are connected in parallel. It is a figure. This figure is shown in Figure 1.
FIG. 3 is a part of a process diagram for manufacturing the liquid crystal display device shown in FIG. Is. FIG. 2 shows a state in which the first conductor 2 is formed. After forming the insulator 3 (barrier layer 3b) in FIG. 3, the insulator 3a forming the nonlinear element is formed on the side surface of the first conductor 2. The insulator 3a is formed by anodic oxidation, thermal oxidation, or the like, but the first conductor 2 in the portion forming the insulator 3a needs to be electrically connected when performing anodic oxidation. The portion indicated by the broken line in FIG. 3 is removed by photoetching. FIG. 4 shows the state after the etching. Here, the first conductor 21 of the second nonlinear element 102 is formed in a floating state. FIG. 5 shows a state in which the second conductor 4 and the pixel electrode 5 are formed. As described above, even if the structure according to each of the above embodiments is used, the load of the manufacturing process is 5
The four types of photomasks are the same as the conventional structure.

Next, a specific method for removing the wiring connection between the closed portion, that is, the floating portion and the inter-pixel wiring by etching will be described. FIG. 6A shows a state in which the film of the first conductor including the inter-pixel wirings 33 and 34 is formed on the substrate. Figure 1
The same reference numerals as in FIG. In the same figure, (b) shows a state in which a potential is externally applied to the inter-pixel wirings 33 and 34 to perform anodic oxidation, and an insulating film is formed in a shaded portion. After that, the insulating film of the non-linear element is formed by the same method as shown in the steps of FIGS. 10C, 10D, and 10E. FIG. 6C shows a state in which the closed portion 84 is photo-etched using a photoresist and the conductor 73 is removed from the substrate. FIG. 6D shows a state in which the second conductor 4 and the pixel electrode 5 are formed in the subsequent steps.

FIG. 7 shows a method of etching the closed portion using a metal mask, which is shown in FIGS. 6 (a) and 6 (b).
The steps are common. After the insulating film of the nonlinear element as shown in FIG. 6B is formed, as shown in FIG.
The second conductor 4 is formed except for the closed portion 84. For the conductor 4, for example, Cr metal is used. After that, the etchant is selected such that the second conductor 4 is not etched and only the conductor 73 is etched to etch the closed portion (the second conductor 4 functions as an etching stopper) and FIG. Then, the second conductor 4 is etched into a predetermined shape pattern to form the pixel electrode 5 (FIG. 6G).

In the example shown in FIG. 1, since the closed portion 83 has the above-described properties, the position may not overlap with another pattern formed in a subsequent step, for example, the layer of the pixel electrode 53. It is useful. The larger the area of the pixel electrode 53 is, the more desirable it is. However, if the positions of the pixel electrode 53 and the closing portion 83 overlap each other, the electrically insulating connection between the floating portion 63 and the pixel electrode cannot be said to be sufficient. Therefore, the driving of the nonlinear elements 103 and 104 is adversely affected. In the case of the liquid crystal display device shown in FIGS. 2 to 5, the portion of the conductor removed by photo etching and the pixel electrode 5 are removed.
However, in this case, the conductor 21 is electrically at the same potential as the pixel electrode 5 as shown in FIGS. 13 and 14, and the insulation resistance of the removed portion adversely affects the driving of the nonlinear elements 101 and 102. Does not reach. From such a viewpoint, in the conductor 73 in FIG. 1, the floating portion 63 contributes to the formation of the nonlinear element. That is, since it constitutes the non-linear element, it is inconvenient to overlap the pattern of the pixel electrode 53.

Further, when the closed portion 83 is photoetched in FIG. 1, the etching speed can be increased by providing the resist closed portions 93 and 94 inside the positions of the pixel electrodes 53 and 54. This is because the area of the pixel electrodes 53 and 54 is large and the resist density of the entire area can be lowered when the resist is not applied to most of the area.

[0020]

Since the present invention has the above-mentioned structure, it is possible to manufacture a liquid crystal display device or the like having a plurality of non-linear elements, in which the polarity difference is eliminated, with extremely excellent electrical characteristics. It has become possible.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing another embodiment of the present invention.

FIG. 3 is an explanatory diagram of a post process of FIG.

FIG. 4 is an explanatory diagram of a post process of FIG.

5 is an explanatory view of a post process of FIG.

FIG. 6 is an explanatory diagram of an etching process of the present invention.

FIG. 7 is an explanatory view of another method of the etching step of the present invention.

FIG. 8 is a plan view of a conventional liquid crystal display device.

9 is an enlarged cross-sectional view of FIG.

10 is an explanatory view of the manufacturing process of the liquid crystal display device of FIG.

FIG. 11 is a plan view of a liquid crystal display device in which the polarity difference is eliminated.

12 is an enlarged cross-sectional view of FIG.

FIG. 13 is a plan view of another liquid crystal display device in which the polarity difference is eliminated.

14 is an enlarged cross-sectional view of FIG.

[Explanation of symbols]

 1 Substrate 2, 21 First Conductor 3 Insulator 4 Second Conductor 5, 53, 54 Pixel Electrode 33, 34, 35 Inter-Pixel Wiring 63, 64 Floating Part 43, 73, 74 Conductor 83, 84 Opening Part 101, 102, 103, 104 Non-linear element

Claims (2)

[Claims] 1. A plurality of pixel electrodes, a non-linear element for driving each pixel electrode, and a wiring arranged between each pixel electrode are provided on one substrate of a pair of substrates sandwiching a liquid crystal layer. , The non-linear element has a first conductor, an insulator, and a second conductor, and an overlapping portion of the first conductor, the insulator, and the second conductor is non-linear in current-voltage characteristics. Electro-optical device, such as a liquid crystal display device, including a step of forming the electrically conductive insulator by anodic oxidation of the first conductor and then disconnecting the electrical connection between the first conductor and the wiring. 2. The method for manufacturing an electro-optical device according to claim 1, wherein the electrical connection is connected to a wiring different from a wiring involved in driving the nonlinear element, and the electrical connection is cut by photoetching. 2. The method of manufacturing an electro-optical device according to claim 1, wherein the same material as that of a conductor pattern formed in a subsequent step is used as a mask for the photo-etching.