JPS60200227A - Thin-film nonlinear resistance element for display device - Google Patents

Abstract

PURPOSE:To increase the threshold voltage of a nonlinear resistance element and to improve display quality, and to stabilize characteristics and to prevent the deterioration by forming >=2 kinds of metallic layer between stacked thin-film nonlinear resistance elements. CONSTITUTION:A display electrode layer 23 and a light shield layer 33 are provided on a substrate 31, and then a lower rectifying connection part 34 is provided. A lower metallic short-circuit layer 35 and an upper metallic short-circuit layer 35 are provided on the connection part 34, and an upper rectifying connection part 37 is provided on the short-circuit layer 36. Further, a deterioration prevention layer 38 for the rectifying connection parts, an interlayer insulation layer 39, and a mutual wiring layer 40 are provided on the connection part 37. Thus, the threshold voltage of the rectifying connection parts is increased to improve the display quality, and the adhesive strength between the rectifying connection parts and metallic layers is improved to stabilize the characteristics and prevent the deterioration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is for efficiently forming a display nonlinear resistance element with a large threshold voltage.

[Background of the invention]

Liquid crystal, EL, EC, FDP, fluorescent display, etc.

All display devices have reached the stage of practical use, and the current goal is to create a high-density matrix type display.

For displays where matrix driving is problematic, a so-called "active matrix" method using active additive elements is effective.

By using thin-film nonlinear resistance elements in display devices, high-density, high-quality displays are possible.
The superiority of the thin film rectifying element as an active addition element for display devices has been described in a previous application (Japanese Patent Application No. 167945/1983). Furthermore, in order to increase the driving ability of the thin film nonlinear resistance element, the threshold voltage (vth
) needs to be increased. Regarding this point, the previous application (
It is described in Japanese Patent Application No. 57-16794).

The present invention introduces a metal layer into the reverse rectifying connection part in order to short-circuit the reverse rectifying joint part that occurs when thin film nonlinear resistance elements are vertically connected (superimposed), and the metal layer is It has at least two or more types of metal layers. By having multiple metal layers, it is possible to improve the adhesion with the thin film nonlinear resistance element, reduce the amount of side etching between the metal layer and the thin film nonlinear resistance element due to etching, etc., and reduce the amount of side etching between the metal layer and the thin film nonlinear resistance element. This makes it possible to control the diffusion, etc. of the thin film nonlinear resistance element, thereby preventing deterioration and improving heat resistance of the thin film nonlinear resistance element.

[Conventional technology and problems]

FIG. 1 shows an example in which rectifying connection portions of thin film nonlinear resistance elements are stacked in two stages, and a metal layer is formed between the stacks. 1st
In the figure, 1 is a substrate, 2 is a display electrode, 6 is a light shield layer, 4 is a lower rectifier connection of a thin film nonlinear resistance element, 5 is a metal layer that short-circuits the upper and lower rectifier connections, and 6 is an upper rectifier connection. A rectifier connection portion, 8 is a film that serves as a deterioration prevention layer for the rectification connection portion and a masking during etching, 8 is an interlayer insulating film, 9
is an interconnection layer.

Although FIG. 1 shows an ideal structure, there are some problems in actual use. Examples are shown in FIGS. 2 and 3. FIG. 2 is a diagram showing poor adhesion between the upper and lower rectifying connection portions and the shorting layer, and side etching has progressed. This side etching causes a reduction in the withstand voltage of the interlayer insulating layer, a short circuit between the wiring layer and the element, or a disconnection of the wiring, which causes element irregularities and display defects, leading to a deterioration in display quality.

Figure 3 is a diagram showing that when etching the upper rectifying connection, variations in the etching speed of the layer constituting the rectifying connection, pinholes, or pinholes in the shorting layer occurred; , deterioration of the display electrode layer, clouding of the substrate, generation of a difference Q), etc. occur, leading to deterioration of display quality. In FIG. 2, 10 is a substrate, 11 is a display electrode, 1
2 is a light shield layer, 16 is a lower rectifier connection, 14 is a metal layer that short-circuits the upper and lower rectifier connections, 15 is an upper rectifier connection, 16 is a deterioration prevention layer for the rectifier connection, 17.18 is, It shows the side etching part.

In FIG. 3, 21 is a substrate, 22 is a display electrode, 26 is a light shield layer, 24 is a lower rectifier connection, 25 is a metal layer that short-circuits the upper and lower rectifier connections, 26 is an upper rectifier connection,
27 is a deterioration prevention layer of the rectifying connection portion, and 28 is a damaged portion of the short circuit layer.

[Purpose of the invention]

The present invention eliminates what contributes to the deterioration of display quality as shown in FIGS. 1 and 2 by using multiple shorting layers, and
Each layer is made thinner, without increasing the element thickness or etching time, and can be formed in succession in a vacuum. Nonlinear resistors improve display quality without increasing process load. The purpose is to provide an element.

[Embodiments of the invention]

FIG. 4 shows an embodiment using the present invention. 2 short circuit layers
By layering, it is possible to improve the adhesion force independently at the upper and lower rectifying connection parts, and it is possible to reduce side etching.
Since an etching stopper layer can be formed for the layer constituting the rectifying connection portion, an element with an ideal structure can be formed without deterioration of the display electrode layer. Its structure is an element as shown in FIG.

In FIG. 4, 61 is a substrate, 62 is a display electrode layer, and 66
is a light shield layer, 64 is a lower rectifying connection part, 65 is a lower shorting layer, 66 is an upper shorting layer, 67 is an upper rectifying connection part,
68 is a deterioration prevention layer of the rectifier connection portion, 69 is an interlayer insulating layer, 4
0 is an interconnection layer.

FIG. 5 shows an example in which the present invention is utilized and the number of shorting layers is three. The three-layer structure improves electrical contact and physical adhesion with the upper and lower rectifier connections, and allows the formation of an independent etching stopper layer for the upper rectifier connection, reducing thin film nonlinearity. It is possible to stabilize the characteristics of the resistive element, prevent deterioration, and reduce variations, thereby improving the appearance of the display device. FIG. 5 shows an example in which the shorting layer is made of three layers.

In FIG. 5, 51 is a substrate, 52 is a display electrode, 53 is a light shield layer, 54 is a lower rectifying connection part, 55 is a lower shorting layer, 56 is an intermediate shorting layer, 57 is an upper shorting layer, 5
Reference numeral 8 designates an upper rectification connection portion, 59 a deterioration prevention layer for the rectification connection portion, 60 an interlayer insulating layer, and 61 an interconnection layer.

As is clear from the above, the present invention provides a multilayer thin film nonlinear resistance element in which a plurality of multilayer thin film nonlinear resistance elements are formed in a stacked manner. By forming a metal layer, the threshold voltage of the thin film nonlinear resistance element can be increased, thereby improving the display quality.In addition, the adhesion between each metal layer and the thin film nonlinear resistance element is improved, so side etching is reduced. , a structure close to the ideal structure is possible, and damage to the underlying layer when etching the E-layer thin film nonlinear resistance element structure can be prevented, and the characteristics of the thin film nonlinear resistance element are stabilized, deterioration is prevented, and variations are prevented. This makes it possible to reduce the amount of noise and improve the appearance of the display device.

The present invention will be explained below using examples.

FIG. 6 shows that the rectifying connection part of the thin film nonlinear resistance element of the present invention has a two-layer structure of a PIN junction consisting of a P-type semiconductor layer, a ■-type semiconductor layer with a low impurity concentration, and an N-type semiconductor layer. This shows the manufacturing process of a two-layer thin film nonlinear resistance element in which two metal layers are formed between PIN and PIN. Figure 6 fA
+ is a transparent electrode layer (display electrode layer) and a light shield layer on the substrate, a lower PIN type diode layer (rectifying junction), two types of metal layers between the lower and upper layer PIN type diodes, and an upper layer PIN. In addition to the diode layer, a metal layer is also formed to prevent deterioration of the semiconductor layer due to etching or IJ process. In FIG. 6(A), 71 is a glass or ceramic substrate, and 72 is a display electrode layer made of ITO, 5N02, or a thin metal film. 73 is a light shield layer made of C'', Ni or
It is A7. 74 is a P-type semiconductor layer, which is amorphous silicon doped with B (boron) as an impurity. 75 is an I-type semiconductor layer with a low impurity concentration, 65 is an N-type semiconductor layer, and P (phosphorus) is added as an impurity.
is amorphous silicon which is not doped. 7
7 is a lower metal layer, consisting of Ta, Mo, Cr%Ni, w
, Al, Pi, etc. 78 is an upper metal layer and is made of Cr, Ni, A1, etc. 79 is a P-type semiconductor layer, 80 is an I-type semiconductor layer, and 81 is an N-type semiconductor layer, which are made of amorphous silicon.

A protective layer 82 is made of Al or Cr for stabilizing the semiconductor layer and preventing deterioration of the semiconductor layer due to etching and photolithography processes.

FIG. 6(B) is a diagram in which the layers formed up to FIG. 6(A) are patterned to a predetermined size.

FIG. 6 (q is a thin film nonlinear resistance element formed using the present invention. FIG. 6 (q is an interlayer insulating film, Si
02. After forming Si, N4, polyimide resin, etc., a contact hole is formed at a predetermined position, and a glue layer of Al, Cr, NiCr, or a multilayer metal layer is formed and then patterned. FIG. 6 (In Q, 83 is an interlayer insulating film, and 84 is a wiring layer.
By combining the q elements and each display medium, a high-density, high-quality display device can be formed. Effective methods for forming the semiconductor layer include not only the plasma CVD method but also the photo CVD method, sputtering method, vapor deposition method, and ion blating method. Types of semiconductors include amorphous silicon, microcrystalline silicon, silicon carbide, silicon germanium, and silicon nitride. Amorphous silicon is a suitable material for semiconductors because it can control valence electrons even though it is a thin film. B, P%H1N, 0, as necessary
C, Ge.

Sn, A7%L1, As, etc. may be added.

〔Effect of the invention〕

As described above, in multilayer thin film nonlinear resistance elements for display devices, by forming two or more metal layers between the superimposed thin film nonlinear resistance elements, the stability and yield rate of the element are improved, and the display is uniform. A display device with excellent display quality can be manufactured. Furthermore, the metal layer can be formed within the same vacuum device, which is advantageous economically without increasing the number of manufacturing steps.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view showing the structure of a conventional thin film nonlinear resistance element. FIG. 2 is a partial sectional view showing the method of manufacturing a conventional nonlinear resistance element, in which the adhesion between the upper and lower thin film nonlinear resistance elements and the shorting layer was poor, and side etching progressed. FIG. 3 is a partial cross-sectional view showing damage caused to the shorting layer when etching the upper thin film nonlinear resistance element in the conventional manufacturing process of the nonlinear resistance element. FIG. 4 is a partial cross-sectional view showing the structure of the nonlinear resistance element of the present invention, in which the shorting layer is made up of two layers. Figure 5 shows. FIG. 2 is a partial cross-sectional view showing the structure of the nonlinear resistance element of the present invention, in which the shorting layer has three layers, the lower layer and the upper layer are of the same metal, and the intermediate layer is of different metals. FIG. 6 is a partial cross-sectional view showing the manufacturing process of a nonlinear resistance element according to an embodiment of the present invention. 1.10.21.61.51.71...Substrate,
2.11.22.62.52.72...Display electrode, 4.13.24.64.54.6.15.26.67.
58... Thin film nonlinear resistance element, 7.16.27
．． 68.59.82...Deterioration prevention layer, 8.69.60.86...Interlayer insulating film, 9.4
0.61.84...Interconnection layer, 5.14.2
5.65.66.55.56.57.77.78...
...Short layer. Figure 2 Figure 3 Figure 4 Figure 5

Claims (3)

[Claims] (1) A thin film nonlinear element for a display device is a multilayer thin film nonlinear resistance element formed by stacking a plurality of thin film nonlinear resistance elements, and is characterized by having at least two or more types of metal layers between the stacked thin film nonlinear resistance elements. Thin film nonlinear resistance element for display devices. (2) The metal layer between the stacked thin film nonlinear resistance elements has a three-layer structure, and from the bottom, the first and third layers are made of the same metal, and the second intermediate layer is made of a different metal. A thin film nonlinear resistance element for a display device according to claim 1. (3) The thin film nonlinear resistance element for a display device according to claim 1, wherein the thin film nonlinear resistance element is made of amorphous silicon.