JPH02304534A - Display device driving nonlinear element - Google Patents

Abstract

PURPOSE:To increase the ratio of the liquid crystal capacity to a MIM element capacity without generating disconnection by bringing a second metal and an insulator on a first metal into contact with each other through the minute area aperture part of an inter-layer insulating film. CONSTITUTION:A second metal 4 and an insulator 3 on a first metal 2 are brought into contact with each other through an aperture part 7 formed in an inter-layer insulating film by fine working. Consequently, the dimensions of the MIM element are determined by the dimensions of the aperture part 7, and the dimensions of the MIM element are reduced since the aperture part is formed with a minute area by fine working. Since the size of the MIM element is not dependent upon the line width of the first and the second metals 2 and 4, the line width is sufficiently widened to remarkably reduce the probability of the disconnection. Thus, the ratio of the liquid crystal capacity to the MIM element capacity is set to a large value without generating the disconnection.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a nonlinear element for driving a display device, and particularly to a nonlinear element having a metal-insulator-metal configuration (hereinafter referred to as an MIM element). LCD capacity and MIM
The present invention relates to a nonlinear element for driving a display device suitable for forming an MIM element with a large element capacitance ratio.

[Prior Art] Thin display devices such as liquid crystal displays are used in large quantities as display devices for small electronic devices such as trains and watches.
Currently, the goal is to increase the size and quality of display screens.

An effective method for realizing high-quality display on a large screen is an active matrix method in which a nonlinear element is provided in each pixel of the screen to drive the liquid crystal. As active matrix type nonlinear elements, three-terminal elements such as thin transistors, two-terminal elements such as MIM elements, varistors, and thin film diodes, and the like are used. In particular, since the two-terminal element has a simple structure, the active matrix method using the three-terminal element is superior to the active matrix method using the three-terminal element in terms of cost per meter. - As an example, active matrix display devices using MIM elements are used in IEE, transaction, EDA -28,
6, pp. 736-739 June.

1981, Day, Earl, Rose 7 (t!! (IEE
E rtans,.

ED-28, 6, pp 736-739 June, 1
981. D., R. Baraff, et al.).

In active matrix display devices, in order to improve display performance, it is necessary to increase the aperture ratio of the display screen, reduce the capacitance of nonlinear elements, and form nonlinear elements with small areas at high density on the substrate. be done.

Furthermore, in order to obtain high display performance in a display device using M1M elements, it is necessary to increase the liquid crystal capacitance C1° and the MIM element capacitance ratio (C1°/CHI-). For example, Assuming that the pixel electrode (1 dimension) is 200 μm square, the dimensions of the MIM strands need to be 3 μm square or less.

FIG. 7 is an explanatory cross-sectional view showing a conventional MIM cord, and FIG. 8 is a plan view thereof. As shown, conventional MI
In the M element, a first metal 2 is provided on a glass substrate 1, the first metal 2 is anodized to form an insulator 3, a second metal 4 is provided on the insulator 3, and a second metal 2 is provided on the insulator 3. metal 4 and pixel electrode 5
It has a structure in which it is electrically connected to the Here, for example, the first metal is Ta, and the second metal 4 is C.
r, as the insulator 3, D205 is used.

[Problems to be Solved by the Invention] The dimensions of a conventional MIM element are determined by the line width of the first metal or the second metal. For example, M shown in FIGS. 7 and 8
In the case of an IM element, depending on the line width of the first metal 2,
The dimensions of the MIM element are determined.

Therefore, in order to increase the capacitance ratio cLc/cHTH mentioned above, it is necessary to make the line width of the first metal and the second metal as thin as possible.

However, if the line width is reduced to 3 μI11 or more, there is a problem that the probability of wire breakage occurring increases and the yield of non-defective products decreases. In particular, when the screen size becomes 10 inches, the size of the glass substrate becomes 300 mm square, and it becomes extremely difficult to form high-definition line widths on such a large screen. Therefore, the yield of good products further decreases,
There was a problem in that the manufacturing cost was extremely high.

For the above reasons, in the prior art, a high-definition active matrix large-screen display device using MIM elements has not been realized.

The present invention has been made in view of the problems of the prior art described above, and provides a nonlinear element for driving a display device that can form a MrM element with a large ratio CLC/CHIH between liquid crystal capacitance and MIM element capacity. It is an object.

[Means for Solving the Problems] A nonlinear element for driving a display device of the present invention includes a first metal-
It is applied to a nonlinear element for driving a display device having a structure of an insulator and a second metal, and in particular, the second metal and the insulator are in contact with each other through an opening in an interlayer insulating film. It is characterized by the presence of

[Function] According to the present invention, the dimensions of the MIM element are determined by the openings in the interlayer insulating film, so in order to reduce the dimensions of the MIM element, it is sufficient to reduce the dimensions of the openings.
There is no need to narrow the line width of the metal forming the i-element.

Therefore, it is possible to provide a nonlinear element for driving a display device that does not cause disconnection, and as a result, it becomes possible to manufacture a large-screen, high-definition display device with a high quality-quality product yield.

[Examples] Hereinafter, the present invention will be roughly described in detail with reference to examples shown in the accompanying drawings.

FIGS. 1(a), (b), and (C) are cross-sectional views showing the manufacturing process of the first embodiment of the nonlinear element for driving a display device of the present invention, and FIG. .

FIG. 4 is an explanatory plan view of the first embodiment shown in FIGS. Note that the same parts as those of the conventional MIM resistor shown in FIGS. 7 and 8 are given the same reference numerals, and the explanation thereof will be omitted. As shown in FIG. 1(a), a 300 mm thick layer of Ta is deposited on the entire surface of a glass substrate 1 by sputtering, and a first film 4 is formed.
A first metal 2 is formed by patterning using a mask and plasma etching using a mixed gas of CF4 and 02. Next, in a 0.05% citric acid aqueous solution, anodic oxidation is performed on the first metal 2 at a voltage of 40 V to form an insulator 3 made of T-820s of 4ooA on the surface of the Ta film. . Next, as shown in FIG. 1(b), an insulating layer with a film thickness of 3000 mm was formed using a CVD method.
3N4, using the second mask and the C
The insulating film 6 and the opening 7 are formed by plasma etching using a mixed gas of F4 and 02. Next, Figure 1 (
As shown in C), a film thickness of 10
A second metal 4 is formed by depositing 000 Cr and wet-etching the Cr using a third photomask with a mixed aqueous solution of ceric ammonium nitrate and perchloric acid. Roughly, by sputtering method, the film thickness too
oA of ITO is deposited and wet-etched using an aqueous solution of ferric chloride and hydrochloric acid using a fourth photomask to pattern the pixel electrode 5 (see FIG. 2).

In the first embodiment described above, in order to stabilize the device characteristics of the MIM element, it is desirable to form the interlayer insulating film 6 to be appropriately thick, for example, to a thickness of tooA or more.

The reason for this is that by increasing the thickness of the layer-level insulating film 6, the MIM element composed of the first metal 2 (Cr), the insulator 3 (Si3N4), and the second metal 4 (Cr) can be This is because it comes to dominate the physical characteristics. The MrM element of the present invention is used by being connected between the pixel electrode of the transparent insulating substrate and one scanning bar.

According to the first embodiment described above, since the dimensions of the MIM element are determined by the dimensions of the opening 7, the opening 7 may be microfabricated in order to reduce the dimensions of the MIM strand.

Therefore, the dimensions of the MIM element can be reduced without narrowing the line widths of the first metal 2 and the second metal 4. For example, even if the line width of the first and second metals is set to 20 μm, if the dimension of the opening 7 is 3 μm square, the line width will be 3 μm.
MIM elements with a corner area can be manufactured. Therefore, since the size difference of the MiM element does not depend on the line widths of the first and second metals, by increasing the line width to 1 minute, the probability of wire breakage occurring can be extremely reduced.

3(a), (b), and (c) are cross-sectional explanatory views showing the manufacturing process of the second embodiment of the nonlinear element for driving a display device of the present invention, and FIG. a), (b), (C)
FIG. 2 is an explanatory plan view of the first embodiment shown in FIG. Note that the same parts as those of the conventional MIM element shown in FIGS. 7 and 8 are given the same reference numerals. As shown in FIG. 3(a), a first metal 2 is patterned on a glass substrate 1 using a first photomask, and then a living room insulating film 6 is formed using a second photomask. The opening 7 is formed by patterning. Next, as shown in FIG. 3(b), the first metal 2 is selectively anodized to form the insulator 3 only in the opening 7. Then, as shown in FIG. Next, as shown in FIGS. 3(C) and 4, the second metal 4 and the pixel electrode 5 are formed by patterning, respectively.

According to the second embodiment described above, since the dimensions of the MIM element are determined by the dimensions of the opening 7, the opening 7 may be microfabricated in order to reduce the dimensions of the MIM element.

Therefore, the dimensions of the MIM element can be reduced without reducing the line widths of the first metal 2 and the second metal 4. For example, the line width of the first and second metals is 20. Even if it is set to Bm, if the dimension of the opening 7 is 3μm square, the
It is possible to produce an MIM element with an area of m square. Therefore, the size difference of the MiM cord does not depend on the line width of the first and second metals, so by making the line width sufficiently thick, the probability of wire breakage occurring can be extremely reduced. .

5(a), (b), and (c) are cross-sectional explanatory views showing the manufacturing process of the third embodiment of the nonlinear element for driving a display device of the present invention, and FIG. a), (b), (C)
FIG. 3 is an explanatory plan view of the third embodiment shown in FIG. Note that the same parts as those of the conventional MIM element shown in FIGS. 7 and 8 are given the same reference numerals. As shown in FIG. 5(a), a first metal 2 is patterned on a glass substrate 1 using a first photomask, and then an insulator 3 is formed by anodizing the first metal 2. Next, an interlayer insulating film 6 and an ITO film used as the second pixel electrode 5 are successively deposited.Next,
As shown in FIG. 5(b), the ITO film used as the pixel electrode 5 and the interlayer insulating film 6 are patterned in the same pattern using a second photomask, and the living room insulation 115!
6, an opening 7, and a pixel electrode 5 are formed. Next, see Figure 5 (
As shown in FIG. 6 and C), the second metal 4 is patterned using a third photomask. According to this embodiment, an MIM element with a small G can be manufactured using only three photomasks. According to the third embodiment described above,
Since the dimensions of the MIM strand are determined by the dimensions of the opening 7, the opening 7 may be microfabricated in order to reduce the dimensions of the MIM element. Therefore, the first metal 2 and the second metal
The size of the MIM cord can be reduced without reducing the line width of the metal 4. For example, even if the line width of the first and second metals is set to 20 μm, the dimension of the opening 7 is set to 3 μm.
If the size is m square, a MIMi element with an area of 3 μm square can be manufactured. Therefore, since it does not depend on the size of the MIM element or the line width of the first and second metals, by making the line width sufficiently thick, the probability of wire breakage occurring can be extremely reduced.

Note that in the above embodiments, a glass substrate was used as the substrate, but the present invention is not limited thereto; for example, a polymer substrate or the like may be used. Further, although Ta is used as the first metal, the present invention is not limited thereto, and it is also possible to use Ta, AI, etc.

Furthermore, although Or is used as the second metal, the present invention is not limited thereto;
1st grade can be used.

Further, although an ITO film is used as a transparent pixel electrode, the present invention is not limited thereto, and SnO2, a metal thin film, etc. can be used.

Furthermore, although Si3N4 was used as the interlayer insulating film 6,
This invention is not limited to this, but includes SiO2,
- [Inorganic material such as a205 r4 f', -K 1,1
Organic materials such as imides can be used.

Further, as a method for forming the insulator, a method using anodic oxidation is preferable. Furthermore, as a method for forming each layer, in addition to the sputtering method, a vacuum evaporation method or a CVD method can be used.

[Effects of the Invention] According to the present invention, the dog-edge of the MIM element can be made finer without being affected by the line widths of the first and second metals, so the MIM element can be manufactured with high reliability t1 without disconnection. As a result, large-screen, high-definition display devices can be produced with a high yield of non-defective products.

[Brief explanation of drawings]

FIGS. 1(a>, b>, and c) are cross-sectional explanatory views showing the manufacturing process of the first embodiment of the nonlinear element for driving a display device of the present invention, and FIG. 3(a>, (b), and (c) are plan views of nonlinear elements for driving display devices manufactured by the manufacturing steps shown in FIG. 3(a), (b), and (c). FIG. 4 is a cross-sectional explanatory diagram showing the manufacturing process of a second embodiment of the nonlinear element, and FIG. 4 is a diagram showing the manufacturing process of FIG. Planar explanatory diagram of the element, FIGS. 5(a) and (b)
), '(c) are cross-sectional explanatory views showing the manufacturing process of the third embodiment of the nonlinear element for driving a display device of the present invention;
The figure is an explanatory plan view of a nonlinear element for driving a display device manufactured by the manufacturing process shown in FIGS. 5(a), (b), and (C),
FIG. 7 is an explanatory cross-sectional view showing a conventional MIM element, and FIG. 8 is a plan view of the MIM element shown in FIG. ]... Glass substrate, 2... First metal, 3... Insulator, 4... Second metal, 5... Pixel electrode, 6...
- Interlayer insulating film, 7... opening. 1-...Glass substrate 2--First metal 3--Thread-colored edge A book 4-Second metal 5,-1 pixel electrode 6-Interlayer insulating film 7-Opening part 1--Figure 2- ...Glass substrate 2 - First metal 6 - System color border f Book 4 - Second metal 5 - Pixel electrode 6 - Interlayer insulating film 7 - Opening part Figure 3 Figure 4 Figure 1 --- Glass substrate 2 - First metal 3 - Insulator 4 - Second metal 5 - Pixel electrode 61. Single layer insulating film 7 - Opening part Fig. 6

Claims (1)

[Claims] (1) In a nonlinear element for driving a display device having a structure of first metal-insulator-second metal, the second metal and the insulator are in contact with each other through an opening in an interlayer insulating film. A nonlinear element for driving a display device, characterized in that: