JPH063702A - Solid state device having nonlinear element - Google Patents

Abstract

PURPOSE:To lower wiring resistance while assuring a cost advantage and to lower the contact resistance between metallic electrodes and pixel electrodes by using MIM type nonlinear elements for an active matrix array. CONSTITUTION:The MIM type nonlinear element constituted of a Ta electrode layer 202b, a Ta2O5 film 203 and an Al electrode layer 204 is formed in each of the respective picture element regions of the active matrix array. An Al electrode layer 204 is wired on the Ta electrode layer 202a. The Al electrode layer 204 is conducted and connected to a scanning circuit and the pixel electrode 205 is conducted and connected to the Ta electrode layer 202b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a MIM type non-linear element used in a liquid crystal display device or the like.

[0002]

2. Description of the Related Art Generally, in an active matrix type liquid crystal display device, a non-linear element is provided in each pixel region to form a matrix array between a substrate on one side and a substrate on the other side on which a color filter is formed. Liquid crystal is filled in advance, and the alignment state of the liquid crystal is controlled for each pixel region to display predetermined information. Here, as the nonlinear element, TF
3-terminal element such as T, or MIM (MeTal-In
A two-terminal element such as a slater-metal type non-linear element is used. However, a method using a MIM type non-linear element is advantageous in order to meet the demand for a larger screen and lower cost of the liquid crystal display device. Further, when the MIM type non-linear element is used, the scanning line can be provided on the substrate on one side where the matrix array is formed, and the signal line can be provided on the substrate on the other side, so that the scanning line and the signal line are crossed. There is also an advantage that an over short circuit does not occur.

In the active matrix type liquid crystal display device using the MIM type non-linear element, as shown in FIG. 4, the MIM type non-linear element is provided between each scanning line 401 and each signal line 402 for each pixel region 403. A signal applied to the scanning line 401 and the signal line 402 is represented as a configuration in which a liquid crystal display element 405 (indicated by a capacitor in the drawing) and a liquid crystal display element 405 (indicated by a variable in the drawing) are connected in series. Based on the above, the liquid crystal display element 3 is switched between the selected state (display state) and the non-selected state (non-display state) to control the display operation.

As shown in FIG. 3, a conventional MIM type non-linear element is formed on the surface of a transparent substrate 301 and has scanning lines 401.
And a Ta electrode layer 302 which is conductively connected to a scanning circuit (driving circuit) via a T electrode layer 302 formed by anodic oxidation on its surface.
a ₂ O ₅ film 303 and a pixel electrode 305 formed on the surface thereof
And a Cr electrode layer 304 that is conductively connected to.

[0005]

In the conventional MIM type non-linear element, the C formed on the surface of the Ta ₂ O ₅ layer 303.
When the r electrode layer 304 and the pixel electrode 305 are electrically conductively connected, there is a problem that the contact resistance between Cr and the pixel electrode increases because an oxide layer is formed on the surface of Cr. Also, in the same structure as the conventional one, instead of the Cr electrode layer, A
When the l electrode layer is used, in addition to the problem of the contact resistance as described above, Al has a poor resistance to the etching solution of ITO used for the pixel electrode, and therefore, there is a possibility that Al may be corroded during etching of ITO. Al could not be used as an electrode layer. On the other hand, even when the stacking order of Al and ITO is reversed, the contact with Al on ITO has higher resistance than that in the case of manufacturing in the stacking order described above, and the linearity may deteriorate. know.

Further, when the tantalum layer which is the first metal electrode layer of the MIM type non-linear element is conductively connected to the scanning circuit,
Due to the relatively high resistance of tantalum, the driving voltage had to be increased.

In order to solve such a problem, the inventor of the present application reduces the wiring resistance by using aluminum for the second metal electrode layer of the MIM type non-linear element and conductively connecting it to the scanning circuit. At the same time, it is proposed that the pixel electrode and tantalum, which is the first metal electrode layer, are conductively connected to ensure the conductive connection between the MIM type non-linear element and the pixel electrode.

[0008]

Means for Solving the Problems In order to solve the above problems, the means taken in the present invention is to form an aluminum layer which is a second metal electrode layer on a tantalum layer which is a first metal electrode layer. Then, this is conductively connected to the scanning circuit, and at the same time, the tantalum layer which is the first metal electrode layer and the pixel electrode are conductively connected.

[0009]

EXAMPLES A method of manufacturing a MIM type non-linear element according to an example of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of the solid state device of the present invention, and FIG.
1 is a sectional view of the MIM type non-linear element taken along line AB in FIG. 1, FIG. 3 is a sectional view of the conventional MIM type non-linear element, and FIG. 4 is an equivalent circuit of an active matrix type liquid crystal display panel using the MIM type non-linear element. It is a figure.

Conventionally, as shown in FIGS. 3 and 4, a Ta electrode layer 3 is conductively connected to a scanning circuit (driving circuit) via a scanning line 401 for each pixel region 403 of a matrix array.
02 (first metal electrode layer), a Ta ₂ O ₅ film 303 (anodized film) formed by anodizing on the surface of the Ta electrode layer 302, and a Ta ₂ O ₅ film 303 formed on the surface of the anodized film 303. Cr that is conductively connected to the pixel electrode 305 made of ITO
The electrode layer 304 (second metal electrode layer) forms a MIM type non-linear element on the surface of the transparent substrate 301.

A method of manufacturing the MIM type non-linear element according to the present invention will be described below.

In advance, a Ta ₂ O ₅ layer 201a (Ta thermal oxide film)
A Ta layer is formed by sputtering on the surface of the transparent substrate 201 on which the Ta electrode layer 202 is patterned.
To form.

Next, the Ta electrode layer 202b in the portion for forming the MIM type non-linear element is selectively anodized to form the surface layer thereof as a Ta ₂ O ₅ layer 203 (anodized film). At this time, a film of SiO ₂ or the like is formed on the surface of the transparent substrate 201 on which the Ta electrode layer 202 is formed.
After removing only the portion of b to be anodized by etching, anodization is performed to form a Ta ₂ O ₅ layer 203. After that, the film such as SiO ₂ formed before the anodization is removed by etching.

Thereafter, the Ta electrode layer 202a used for wiring and the Ta electrode layer 202b used for forming the MIM type non-linear element and the portion conductively connected to the pixel electrode are formed.
Are separated by dry etching, and T of the portion forming the MIM type non-linear element and the portion connected to the pixel electrode are separated.
The a electrode layer 202b is left in an island shape.

Next, after forming an Al layer by sputtering, M
The Al layer is patterned by leaving the part for forming the IM type nonlinear element and the part used for the wiring, and the Al electrode layer 20.
4 is formed. At this time, the portion of the Al electrode layer 204 used for wiring is the T portion of the portion used for wiring formed in the previous step.
It is formed on the a-electrode layer 202a and is conductively connected to the scanning circuit through the scanning line 401. At this time, only one Al electrode layer 204 or T
Either of the two-layer structure composed of the a-electrode layer 202a and the Al electrode layer 204 may be used, but the two-layer structure is preferable in order to prevent disconnection of the Al electrode layer 204.

Further, the width of the Ta electrode layer 202a is narrowed at the portion which is the approach from the wiring portion to the MIM type non-linear element in order to prevent disconnection of the Al electrode layer 204.

Al of the portion forming the MIM type non-linear element
The electrode layer 204 is formed only on the Ta ₂ O ₅ layer 203, and the portion of the Ta electrode layer 2 not anodized is
It is not formed on 02b.

Through these steps, the Ta electrode layer 20
2. A MIM type non-linear element including the Ta ₂ O ₅ layer 203 and the Al electrode layer 204 is formed.

The transparent conductive film such as ITO which becomes the pixel electrode 205 is formed by forming Al as the upper electrode of the MIM type non-linear element.
Since the pixel electrode is not conductively connected to the Al electrode layer 204
It may be either before or after formation.

[0021]

As described above, in the present invention, MI
A structure in which the first metal electrode layer of the M-type non-linear element and the pixel electrode are conductively connected, and the second metal electrode layer is conductively connected to the scanning circuit, and Al is used for the second metal electrode layer. It is characterized by

Therefore, the present invention has the following effects.

By conductively connecting the tantalum, which is the first metal electrode layer, and the pixel electrode, the MIM type non-linear element and the pixel electrode are surely conductively connected, and the second metal electrode layer and the pixel electrode are conductively connected. Since this is not done, it is possible to use a metal, such as aluminum, which forms an oxide between the second metal electrode layer and the oxide when they are brought into contact with the second metal electrode layer, resulting in poor contact.

In order to prevent corrosion breakage of the second metal electrode layer or the pixel electrode, the formation order of tantalum, which is the first metal electrode layer, and the pixel electrode is conductively connected, so that the second metal electrode layer and the pixel electrode can be formed in an arbitrary order. Can be changed. This is a structure that makes it possible to use aluminum for the second metal electrode layer, for example.

Since aluminum can be used as a wiring material that is conductively connected to the scanning circuit, the resistance of the wiring can be reduced.

[Brief description of drawings]

FIG. 1 is a plan view of a solid-state device of the present invention.

FIG. 2 is a cross-sectional view of the MIM type non-linear element of the present invention taken along the line AB in FIG.

FIG. 3 is a cross-sectional view of a conventional MIM type nonlinear element.

FIG. 4 is an equivalent circuit diagram of an active matrix type liquid crystal display device using MIM type nonlinear elements.

[Explanation of symbols]

201 transparent substrate 201a Ta ₂ O ₅ layer (Ta thermal oxide film) 202 Ta electrode layer (first electrode layer) 202a Ta electrode layer wiring part 202b Ta electrode layer element part 203 Ta ₂ O ₅ film (anodic oxide film) 204 Al electrode layer (second electrode layer) 205 Pixel electrode 301 Transparent substrate 302 Ta electrode layer 303 Ta ₂ O ₅ film (anodized film) 304 Cr electrode layer 305 Pixel electrode 401 Scan line 402 Signal line 403 Pixel region 404 MIM type Non-linear element 405 Liquid crystal display element

Claims (2)

[Claims] 1. A first metal electrode layer, an anodized film formed on the surface of the first metal electrode layer, and an anodized oxide film in each pixel region of a matrix array formed on the surface of a transparent substrate. The second metal electrode layer formed on the film surface constitutes a MIM type nonlinear element, the first metal electrode layer and the pixel electrode are conductively connected, and the second metal electrode layer is conductive to the scanning circuit. A solid-state device provided with a non-linear element characterized by being connected. 2. The solid-state device according to claim 1, wherein the first metal electrode layer is a tantalum layer and the second metal electrode layer is an aluminum layer.