JPH063703A - Nonlinear active element and its production - Google Patents

Abstract

PURPOSE:To lower the capacity of a MIM element and to obtain a higher capacity and higher image quality by etching back a second insulating film on the flanks of a first insulating film bored with a hole with the min. design rule in the upper part of a lower electrode, thereby forming side walls. CONSTITUTION:A metallic thin film is formed on a transparent insulating substrate 101 and is patterned to form the lower electrode 102 of the MIM element; thereafter, the first insulating thin film 103 is laminated thereon. An aperture 104 is formed atop the lower electrode 102 and the second insulating film 105 is laminated. The insulating film 105 is thereafter etch back to form the side walls 106 on the flanks of the insulating film 103 and the oxide film 107 of the lower electrode 102 is thereafter formed. The metallic thin film is then laminated thereon and is patterned to a desired shape to form an upper electrode 108. Namely, the effective MIM element is formed in the area narrower than the min. design rule in the aperture part of the upper surface of the lower electrode 102.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-linear active element which is effectively applied to a liquid crystal display device and the like and a method for manufacturing the same.

[0002]

2. Description of the Related Art Recently, as an image display device, a CRT (C
In place of the Athode Ray Tube, liquid crystal display devices such as flat panel displays are receiving increasing attention. As elements of this liquid crystal display device,
3-terminal thin film transistor (Thin Film Tr)
TFT: thin film diode with two terminals.
Although a thin film diode (TFD) and the like are considered, TFD has been attracting attention due to the simplicity of the manufacturing process and the high yield. TFD
One of the metal-insulating film-metal (Metal-In
Research and development on a nonlinear active device (MIM) composed of a surfacer-metal have been advanced for some time. The structure of a conventional MIM element will be described with reference to FIG. 2 which is a sectional view of the element in each manufacturing process. First, as shown in FIG. 2A, a metal thin film is formed on a transparent insulating substrate 201 by a sputtering method or a vapor deposition method, and is patterned into a desired shape to form a lower electrode 202 of the MIM. A thin oxide film 203 is formed. Tantalum, aluminum, or the like is used for the metal thin film that becomes the lower electrode 202, and the oxide film 203 is often formed by an anodic oxidation method or a thermal oxidation method. Then, a metal thin film is further formed by using a sputtering method or a vapor deposition method, and is patterned into a desired shape to obtain the upper electrode 204 shown in FIG. 2B, and the nonlinear active element (MIM) is completed. As the upper electrode 204, a metal thin film of tantalum, aluminum, chromium or the like is used.

[0003]

However, with the recent development of liquid crystal displays as in recent years, in the situation where the MIM element is also required to have a large capacity and high image quality, in the MIM element as described above, It has become difficult to meet that demand. One of the reasons is that it is difficult to reduce the capacitance of the MIM element. FIG. 3 shows an equivalent circuit diagram of a liquid crystal display device using MIM elements. Reference numeral 301 is a segment electrode, 302 is a capacitance CMIM of the MIM element, 303 is a nonlinear resistance RMIM of the MIM element, 304 is a capacitance CLC of the liquid crystal layer, 305 is a resistance RLC of the liquid crystal layer, and 306 is a common electrode. As shown in FIG. 3, the applied external voltage is divided by the ratio of the capacitance CMIN of the MIM and the capacitance CLC of the liquid crystal. Here, if CMIN is large, the voltage applied to MIM becomes small, so that the external voltage is effectively MIM.
It can be seen that it is not applied to. Therefore, if the capacity of the MIM element is large, it also causes crosstalk, and it is difficult to increase the capacity and image quality of the liquid crystal display device.

As a method for reducing the capacity of the MIM element,
A structure as shown in JP-A-60-172028 has been considered. This structure is shown in FIG. Reference numeral 401 is a transparent insulating substrate, 402 is a lower electrode, 403 is an insulating film, 404 is an oxide film of the lower electrode, and 405 is an upper electrode. According to the structure shown here, the effective MIM element is formed by the opening portion on the upper surface of the lower electrode, but this area is determined by the minimum design rule. That is, it is difficult to further reduce the capacity with this method. Further, considering the disconnection of the upper electrode, it is necessary to taper the insulating film opening portion, but it is difficult to process this taper accurately and the element characteristics also vary. There is.

The present invention solves the problems of the prior art as described above, and an object of the present invention is to provide a non-linear active element having a small MIM capacitance, high image quality, and a small variation, and a manufacturing method thereof. To provide.

[0006]

The present invention provides a non-linear active element composed of metal-insulating film-metal (MIM) and a method of manufacturing the same, in which after forming a lower electrode, laminating and patterning a first insulating film, The second insulating film is laminated and etched back to form a side wall on the side surface of the first insulating film.
Is formed, and an effective MIM element is formed in an area of the opening of the upper surface of the lower electrode that is narrower than the minimum design rule.

[0007]

According to the structure of the liquid crystal display device of the present invention, the metal-
The non-linear active element made of insulating film-metal forms an effective MIM element between the sidewalls of the first insulating film, which is narrower than the minimum design rule on the upper surface of the lower electrode, and is a MIM element compared with the conventional one. It is possible to reduce the capacity, and it is possible to increase the capacity and image quality.

[0008]

EXAMPLE An example of the liquid crystal display device of the present invention will be described in detail with reference to the cross-sectional views of the elements in each manufacturing process shown in FIG. First, as shown in FIG. 1A, a metal thin film having a thickness of about 1000 Å to 10000 Å is formed on a transparent insulating substrate 101, and is patterned to form a lower electrode 102 of a MIM element. Thin film 103 to 200
The second insulating film 105 is laminated after the holes 104 are formed on the upper surface of the lower electrode 102 by laminating with a thickness of about 0Å to 10000Å. As the transparent insulating substrate 101, a quartz substrate or an alkali glass is used. Moreover, tantalum, aluminum, or the like is formed on the lower electrode 102 by a sputtering method, a vapor deposition method, or the like.

In this embodiment, a tantalum thin film is deposited by a sputtering method to a thickness of about 5000 Å and then etched to form a lower electrode 102. In addition, a silicon dioxide film, a silicon nitride film, or the like is used as the first insulating thin film 103 and the second insulating film 105, and an atmospheric pressure CVD method, a low pressure CVD method, a plasma CVD method, an ECR plasma CVD method, a sputtering method, or the like. Formed and used. In this embodiment,
As the first insulating film 103, a silicon nitride film was used by being stacked by about 5000 Å by plasma CVD method.
Further, as the second insulating film 105, a silicon dioxide film formed by atmospheric pressure CVD to a thickness of about 5000 Å was used. The diameter of the opening 104 of the first insulating film is a square having a side of 2 μm. After that, the second insulating film 105 is etched by using an etch back method to form a sidewall 106 on the side surface of the first insulating film 103, and then the oxide film 107 of the lower electrode 102 is 500 Å. It is formed with a thickness of about 2000 Å to obtain FIG. A method such as an anodic oxidation method, a thermal oxidization method, or a plasma oxidization method is used for forming the oxide film 107. In the present embodiment, the anodic oxidation method is used, and about 60
We were able to obtain about 0Å tantalum oxide. afterwards,
As shown in FIG. 1C, metal thin films are laminated and patterned into a desired shape to form the upper electrode 108, and a nonlinear active element composed of metal-insulating film-metal is completed.

In this embodiment, the length of the side wall of the first insulating film is about 4000 Å, and the area between the side walls of the first insulating film is about one third of the area of the opening. Therefore, the capacitance of the MIM element can be reduced to about 1/2 to 1/3 as compared with the case where there is no side wall.

[0011]

According to the structure of the nonlinear active element and the method of manufacturing the same of the present invention, the second insulating film is etched on the side surface of the first insulating film which is opened in the upper part of the lower electrode by the minimum design rule. By forming the sidewalls by backing, the capacitance of the MIM element can be reduced as compared with the conventional one, thereby increasing the capacitance and crosstalk, and forming a non-linear active element capable of high image quality. .

[Brief description of drawings]

FIG. 1 is an element cross-sectional view in each manufacturing process of a nonlinear active element shown in an embodiment of the present invention.

FIG. 2 is an element cross-sectional view in each manufacturing process of a non-linear active element according to a conventional technique.

FIG. 3 is an equivalent circuit diagram of a liquid crystal display device using MIM elements.

FIG. 4 is an element cross-sectional view of a non-linear active element in a conventional technique.

[Explanation of symbols]

 101, 201, 401 ... Transparent insulating substrate 102, 202, 402 ... Lower electrode 103, 105, 403 ... Insulating film 104 ... Opening portion 106 ... Side wall formed by etch back method 107, 203, 404 ... Oxide film of lower electrode 108, 204, 405 Upper electrode 301 ... Segment electrode 302 ... MIM element capacitance 303 ... MIM element resistance 304 ... Liquid crystal layer capacitance 305 ... Resistance of liquid crystal layer 306 ... Common electrode

Claims (4)

[Claims] 1. A non-linear active element composed of a metal-insulating film-metal, wherein a sidewall of an insulating film different from an oxide film of the lower electrode is provided on an upper surface of the lower electrode, and an effective area of the non-linear active element is A non-linear active element characterized by being specified to be smaller than the minimum design rule between side walls. 2. The nonlinear active element according to claim 1, wherein the insulating film is thicker than the oxide film of the lower electrode. 3. The nonlinear active element according to claim 1, wherein the relative dielectric constant of the insulating film is smaller than the relative dielectric constant of the oxide film of the lower electrode. 4. A method of manufacturing a non-linear active element composed of a metal-insulating film-metal, which includes a step of forming a lower metal electrode, a step of forming an oxide film of the lower electrode, and a step of forming an upper electrode. A step of forming a first insulating film on the entire surface after forming the lower electrode, a step of forming an opening on the upper surface of the lower electrode, a step of forming a second insulating film, and a step of forming the second insulating film. And a step of forming an oxide film of the lower electrode, and a step of forming an upper electrode, the method of manufacturing a nonlinear active element.