JPH0470623A - Manufacture of element substrate of liquid crystal display device - Google Patents

Abstract

PURPOSE:To improve yield by manufacturing a picture element electrode by leaving a first insulating body on the surface other than the side plane of a first conductor by etching, and forming a second in-sulating body and a second conductor on the side plane of the first conductor. CONSTITUTION:The picture element electrode 4 is manufactured by forming the first conductor 1 on a transparent substrate 7, filming the first insulating body 6 on the first conductor 1 and the transparent substrate 7, and furthermore,applying exposure from the back plane of the transparent substrate 7 by applying positive resist 5, performing the development of the positive resist 5, leaving the first insulating body 6 on the surface of the first conductor 1 except for the side plane 2 of the first conductor 1 by etching the first insulating body 6, forming the second insulating body 8 on the side plane 2 of the first conductor 1, and forming the second conductor 3. Therefore, it is possible to prevent the step separation of the second conductor 3 on the side plane of the first conductor pattern 1 from occurring, and to uniformalize the element area of a rateral MIM consisting of a part where the first conductor 1, the second insulating body 8, and the second conductor 3 are superimposed. In such a way, the yield can be improved.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing a liquid crystal display device.

[Prior Art] FIG. 3 shows a plan view of an element substrate of a conventional liquid crystal display device. FIG. 4 is a sectional view taken along aa' of FIG. 3.

Figure 3 shows a metal insulator (Metal In5) as a pixel element for driving pixels.
The case is shown in which ulator metal (hereinafter referred to as MIM) is used. Furthermore, it can be seen that the MIMs shown in FIGS. 4 to 3 use a lateral MIM structure in which only the side surface (2) of the first conductor (1) is used as a pixel element.

Lateral MIM has a first conductor (1) as shown in Figure 4.
The side surface (2), that is, the surface other than the part where the MIM is formed, is covered with a first insulator (hereinafter referred to as a barrier layer) so that the electrical resistance of the first insulator is increased so that it does not function as an MIM element. This is what I did.

By adopting such a structure, the area of the MIM element can be made extremely small. This is an effective technique for increasing the density and definition of liquid crystal display devices that use MIM elements as pixel elements.

The manufacturing process of a conventional element substrate of a liquid crystal display device is shown in FIGS. 5(a) to 5(e).

A first conductor (1) is formed on a transparent substrate (7).
(a) Forming a barrier layer (6) on the first conductor (1).
(b) Patterning the first conductor and barrier layer simultaneously by photoetching. (C) Side surface of the first conductor (
2) forming a second insulator (8); (d) Form and pattern the second conductor (3) and pixel electrode (4), respectively. (e) Here, the overlapping portions of the first conductor (1), the second insulator (8), and the second conductor (3) form an MIM element.

Ta, A1, A1 are used as conductors for MIM devices.
u, IT○, NiCr+Au, and ITQ+Cr are well known. In addition, as the second insulator, TaOx
, SiOx, SiNx, SiOxNy, TaNx, Zn
0x etc. are well known. These second insulating films are formed by thermal oxidation, anodic oxidation, sputtering, or the like.

In addition to the inorganic material used for the second insulating film, it is also known that the barrier layer uses an organic film such as polyimide.

The most well-known structure for MIM elements is Ta (tantalum) for the first conductor (1), TaOx (tantalum oxide) for the second insulator (8), and C for the second conductor (3).
It uses r (chromium).

Below, T a / which is a typical structure as an MIM element
This will be explained using T a Ox / Cr.

The description will be made using TaOx as the barrier layer.

[Problems to be Solved by the Invention] However, the conventional manufacturing method shown in FIG. 5 has a problem in that the yield is extremely low and it is not practical.

This will be explained using FIGS. 6(a)-(b) and (c)-(e).

Etching is performed in FIG. 6C, but generally an oxide film or a nitride film which is an insulator has a slower etching rate than a metal film which is a conductor. Ta and Taox are TaOx
The etching rate is about 1/2 that of TaNx.
In the case of , the difference becomes even wider. Therefore, as shown in FIG. 6(C), the side surface (2) of Ta (1) has an overhang shape.

Figure 6(d) forms TaOx (8) and Figure 6(e)
The pixel electrode (4) is formed with Cr (3), but Cr (
3), the overhang of the Ta side surface (2) causes a step break in the Cr. Further, even if there is no step cut in Cr, the shape (tapered shape) of the side surface (2) of Ta cannot be controlled, so the area of the lateral MIM element cannot be controlled.

The fact that the element area of the MIM element cannot be controlled means that the display state of the pixels cannot be controlled for the liquid crystal display device, which is a fatal defect.

As described above, the conventional manufacturing method has a problem in that the yield is extremely low and it is not practical.

[Means for Solving the Problems] A method for manufacturing an element substrate for a liquid crystal display device according to the present invention includes a first conductor on a transparent substrate, and a first conductor formed on the surface of the first conductor except for the side surfaces. A first insulator, a second insulator formed on a side surface of the first conductor, and a second conductor are laminated, and the first conductor and the second insulator are laminated. forming the first conductor on the transparent substrate in an element substrate of a liquid crystal display device in which the overlapping portion of the second conductor becomes a pixel element for driving a pixel electrode of the liquid crystal display device; The first insulator is deposited on the first conductor and the transparent substrate, a positive resist is applied, exposure is performed from the back side of the transparent substrate, the positive resist is developed, and the first etching the first insulator to leave the first insulator on the surface of the first conductor except for the side surfaces of the first conductor;
A second insulator is formed on a side surface of the conductor, the second conductor is formed, and the pixel electrode is formed.

[Example] A manufacturing process of an element substrate of a liquid crystal display device according to the present invention is shown in FIGS. 1(a) to 1(f), and will be explained using these figures.

A Ta film is deposited on a transparent substrate (7). (a) A Ta pattern is formed by photoetching.

(b) A TaOx film as a barrier layer is deposited on the transparent substrate (7) and the Ta pattern (1). (C) Ta pattern (1)
Photoetching is performed to leave only the upper TaOx (6) as a barrier layer.

(C) A thin film of Ta0x (8) is deposited by anodic oxidation or thermal oxidation. (e) Cr and pixel electrode are deposited as a film, and Cr is removed by photo-etching.
A pattern (3) and a pixel electrode pattern (4) are formed.

(f) The steps shown in FIG. 1(C) and (d) are the processes characteristic of the present invention.

The second figure shows the steps in Figures 1(C) to (d) in detail.
Figures (a) to (d).

Here, the step shown in FIG. 1(C) is to form a barrier layer, and the Taox film is deposited by sputtering or CvD (chemical).
This is done using methods such as barber deposition. The barrier layer is made of a material other than TaOx film (for example, TaNx, SiN
The same applies to the case of using x, etc.).

The method of leaving the TaOx film of the barrier layer on the Ta pattern in the step of FIG. 1(d) is carried out as follows.

This will be explained using FIGS. 2(a) to 2(d).

A positive resist (a resist that leaves areas not exposed to light) is applied to the film surface (the surface where the Ta pattern is present) of the transparent substrate (7). Next, exposure is performed from the opposite side of the transparent substrate to the film surface, that is, from the back side of the transparent substrate.

FIG. 2(b) Since an oxide film such as TaOx or a nitride film is a transparent film, only the positive resist on the Ta pattern, which is an opaque film, is not exposed. Therefore, when development is performed, only the resist on the Ta pattern remains.

Figure 2(c) Next, the barrier layer of TaOx is etched.

FIG. 2(d) Unlike the state shown in FIG. 6(C) in the conventional process, the film to be etched is a Ta film deposited on the entire surface of the transparent substrate.
Since it is an Ox film, the etching rate is the same. Therefore, the side surface (2) of the Ta pattern (1) can be etched without overhanging. In addition, the tapered shape of the side surface (2) of the Ta pattern is
Since it has already been formed in the process shown in FIG. 1(b), it is possible to obtain a uniform and good side surface shape. by this,
Cr(3) does not cause step cuts on the side surfaces of the Ta pattern, and the element area of the lateral MIM made of the overlapping portions of Ta(1), TaOx(8), and Cr(3) can be made uniform.

[Effects of the Invention] As described above, by the manufacturing process of the present invention, element substrates for liquid crystal display devices using lateral MIMs as pixel elements can be provided at a high yield.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a method of manufacturing an element substrate of a liquid crystal display device according to the present invention. FIG. 2 is a cross-sectional view showing a method of manufacturing an element substrate of a liquid crystal display device according to the present invention. FIG. 3 is a partial plan view of an element substrate of a liquid crystal display device. FIG. 4 is a sectional view taken along aa' in FIG. 3. FIG. 5 is a cross-sectional view showing a conventional method of manufacturing an element substrate of a liquid crystal display device. FIG. 6 is a cross-sectional view showing a conventional method of manufacturing an element substrate of a liquid crystal display device. 1. Conductor (Ta) 2. Side surface of the first conductor 3. Second conductor (Cr) Pixel electrode positive resist 6. First insulator (TaOx) (barrier layer) 7. Transparent substrate 8. 2. Insulator (TaOx) or more

Claims (1)

[Claims] A first conductor on a transparent substrate, a first insulator formed on the surface of the first conductor except for the side surfaces, and a second insulator formed on the side surfaces of the first conductor. and a second conductor, the first conductor, the second insulator, and the second conductor.
In an element substrate of a liquid crystal display device in which an overlapping portion of the conductors serves as a pixel element for driving a pixel electrode of the liquid crystal display device, the first conductor is formed on the transparent substrate, and the first conductor is formed on the transparent substrate. The first insulator is coated on the conductor and the transparent substrate, and a positive resist is applied and exposed from the back side of the transparent substrate. The positive resist is developed to form a film of the first conductor. etching the first insulator to leave the first insulator on the surface of the first conductor except for the side surfaces, forming a second insulator on the side surfaces of the first conductor; A method for manufacturing an element substrate for a liquid crystal display device, characterized in that a second conductor is formed and the pixel electrode is formed.