JP2845929B2 - Manufacturing method of nonlinear element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a non-linear element having a metal-insulator-metal structure (hereinafter referred to as MIM) used for a liquid crystal switching element in an active matrix type liquid crystal display panel. It relates to a manufacturing method.

[Conventional technology]

Liquid crystal display panels have been put into practical use, and high quality and high density are now desired. This is possible in an active matrix system using MIM elements.

In a MIM element, a conductor can be regarded as a metal. For example, a MIM element having a metal-insulator-conductor (metal) structure such as tantalum (Ta), tantalum monoxide (TaO), and indium tin oxide (ITO) is used. When used for a liquid crystal display panel, it can be manufactured by the following steps. FIG. 3A is a plan view showing a liquid crystal display panel, and FIG. 3B is an enlarged cross-sectional view taken along a line AB in FIG. 3A. Hereinafter, description will be given with reference to FIGS. 3 (a) and 3 (b) alternately. Ta is formed on the glass substrate 1 by a sputtering method, and the lower metal 7 and the wiring 9 of the MIM element are formed by photoetching. Next, anodize Ta
TaO is formed as an insulator 5 on the surface. Next, ITO is formed by a sputtering method and patterned by photoetching, and the upper layer metal 8 of the MIM element and the pixel electrode
To form

[Problems to be solved by the invention]

Since the upper layer metal 8 is formed by using the sputtering method, the lower layer metal 7 has poor fault coverage at the faulted portions and is liable to break.

Furthermore, even if the disconnection of the upper layer metal 8 does not occur, the thickness of the upper layer metal 8 becomes thinner at the cut portion of the lower layer metal 7 than the others. As a result, as shown in FIG. 4, the etchant enters the gap, the side metal of the upper metal 8 progresses at the gap, and the lower metal 7 and the upper metal 8 pass through the insulator 5.
In addition, the insulator 5 is formed by anodizing the surface of the lower metal 7. At this time, the lower metal 7 has a shape as shown in FIG. Therefore, in a portion where the surface of the glass substrate 1 and the surface of the lower metal 7 are in contact with each other, the insulator 5 is difficult to be formed uniformly, and the thickness of the insulator 5 becomes thin. Likely to happen.

An object of the present invention is to solve such problems and to provide a method of manufacturing a high-quality and high-density liquid crystal display panel with less disconnection and variation in element area and with less leakage current.

[Means for solving the problem]

The above object is to form a first metal film on the entire surface of a glass substrate and further form a photosensitive resin, and to pattern the photosensitive resin into a lower metal and wiring pattern by photolithography. Using the patterned photosensitive resin as an etching mask, etching the first metal film to form a lower metal layer and wiring, forming an insulating film over the entire surface, and removing the photosensitive resin to form the first resin. A step of embedding an insulating film in a region where the metal film is not formed, a step of forming an insulator on the lower metal, and a step of forming a second metal film on the entire surface and performing second etching by photoetching.
Forming an upper layer metal made of a metal film and a pixel electrode for driving a liquid crystal.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Example 1 FIG. 2 is a plan view showing a liquid crystal display panel using a MIM element manufactured according to this example, and FIGS. 1 (a) to 1 (f).
FIG. 2 is an enlarged cross-sectional view taken along a line AB in FIG. 2 showing a manufacturing method in the order of steps. Hereinafter, description will be made with reference to FIGS. 1 and 2 alternately.

First, as shown in FIG. 1 (a), Ta is used as a first metal film 2 on a glass
200 nm to 1000 nm is formed, and photosensitive resin 3 is further coated to 1000 nm to 5 nm.
000 nm.

Next, as shown in FIG. 1 (b), the photosensitive resin 3 is patterned into a lower metal and wiring pattern. Then, using the photosensitive resin 3 as a mask, the first metal film 2 is etched by a reactive ion etching method using an etching gas containing fluorine, for example, a carbon tetrafluoride gas, and the lower metal layer 7 shown in FIG. And the wiring 9 are formed.

Next, as shown in FIG. 1 (c), TaO is formed as the insulating film 4 to have substantially the same thickness as the first metal film 2 by the sputtering method.

Next, as shown in FIG. 1D, the photosensitive resin 3 used as an etching mask is removed to remove the first resin.
Where the first metal film 2 is formed, that is, the first metal film 2
The upper insulating film 4 is removed, and the insulating film 4 is formed in a region where the first metal film 2 is not formed. By the above steps, the first
There is almost no difference in the surface of the metal film 2 and the surface is flattened.

Next, as shown in FIG. 1 (e), Ta as the first metal film 2 is anodized in a 0.1% aqueous citric acid solution at a voltage of 30 V to form an insulator on the surface of the first metal film 2. TaO as 5,
It is formed to a thickness of 50 nm.

Next, as shown in FIG. 1 (f), ITO is formed on the entire surface as a second metal film 6 by a sputtering method, and is patterned by photoetching to form an upper layer metal 8 of an MIM element made of ITO and a liquid crystal drive. The pixel electrode 10 is formed.

In this embodiment, an example in which an anodic oxidation method is used as a method for forming the insulator 5 has been described. 5 may be formed.

In this embodiment, the lower metal 7 is Ta, and the upper metal 8 is Ta.
Was used, and TaO was used as the insulating film 2.
Also, a MIM element can be manufactured by using other metals such as aluminum, chromium, tungsten, and nickel as the lower metal 7 and silicon nitride or silicon oxide as the insulating film 4.

In the removal of the insulating film 4 on the first metal film 2 described with reference to FIG. 1D, the cross-sectional shape of the photosensitive resin 3 has a larger opening on the side in contact with the first metal film 2 than the upper surface. By making it reversely tapered, it can be performed reliably. In addition, a metal material such as aluminum can be used instead of the photosensitive resin.

[Effects of the Invention] As is clear from the above description, according to the present invention, since the step of the lower metal can be eliminated, it is possible to suppress the element area variation due to disconnection of the upper metal or penetration of the etching solution. Becomes Further, since the lower metal surface is flat, a leak current in which a uniform insulator is formed is reduced. As described above, a high-quality and high-density liquid crystal display panel can be obtained.

Furthermore, according to the present invention, the thickness of the lower metal layer and the thickness of the wiring can be arbitrarily set, so that the problem of the wiring resistance, which has been a problem with large liquid crystal panels, can be solved, and a large liquid crystal panel can be realized.

[Brief description of the drawings]

1A to 1F are cross-sectional views showing a method of manufacturing a MIM element according to the present invention in the order of steps, and FIG.
FIGS. 3A and 3B are plan views showing a liquid crystal display panel using M elements, and FIGS. 3A and 3B show a liquid crystal display panel using MIM elements in a conventional example. FIG. 3A is a plan view and FIG. FIG. 4B is a cross-sectional view, and FIG. 4 is a perspective view for explaining a problem of the conventional MIM element. DESCRIPTION OF SYMBOLS 1 ... Glass substrate, 2 ... 1st metal film, 3 ... Photosensitive resin, 4 ... Insulating film, 5 ... Insulator, 7 ... Lower layer metal, 8 ... Upper layer metal, 9 ... Wiring , 10 ... Pixel electrode for driving liquid crystal.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02F 1/136 G02F 1/1333 G02F 1/13 101 G02F 1/1343 G09F 9/30 H01L 49/02

Claims (1)

(57) [Claims] A step of forming a first metal film on the entire surface of the glass substrate and forming a photosensitive resin on the entire surface; and patterning the photosensitive resin into a pattern of lower metal and wiring by photolithography. Forming the lower metal and the wiring by etching the first metal film using the patterned photosensitive resin as an etching mask; forming an insulating film on the entire surface; Removing the conductive resin, removing the insulating film formed on the upper surface of the photosensitive resin, and embedding the insulating film in a region where the first metal film is not formed; Forming a second metal film on the entire surface, and forming an upper metal layer made of the second metal film by photo-etching. Manufacturing method of a nonlinear element.