JPH0636326B2 - Heat resistant black electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention is a heat-resistant black electrode suitable for use as a wiring electrode of a fluorescent display tube (hereinafter abbreviated as VFD) or a back electrode of a thin film EL display element. It is about.

[Conventional technology]

Generally, Al, which is a good conductor of electricity, is widely used as a back electrode of a thin film EL display element, VFD wiring, and an electrode material. However, since the surface of the Al electrode has a very high light reflectance of about 90%, the display element using the Al electrode has a drawback that glare is likely to occur on the display surface due to reflection of external light. A black electrode is known to improve the optical defect of the Al electrode, and its material is C, AsSs, SiGe or Al, In, Cr, Mn,
Oxides such as Mo have been proposed.

[Problems to be Solved by the Invention]

However, the black electrode in which the amount of the black material and the Al electrode are laminated has weak adhesion and poor heat resistance. Moreover, patterning by etching is difficult and the manufacturing process becomes complicated.

As a solution to such a problem, the present inventors have disclosed in JP-A-63-241846 that a heat-resistant black material and an Al electrode having heat resistance capable of withstanding the heat treatment step of VFD and excellent in patterning property. And a black electrode having a two-layer structure.

However, in this heat-resistant black electrode having a two-layer structure, as shown in FIG. 4, its spectral reflection characteristic has an extremely large undulation, which causes a slight bluish coloring or a slight pink coloring. It is easy (the spectral reflectance of a true black electrode is a flat line). In addition, in order to reduce the reflectance at around 550 nm, where human visibility is high, to about 10% or less, this two-layer structure is used. In the black electrode, there is a problem that extremely strict process control is required in the film formation process and the subsequent heat treatment process because the change in reflectance between the film formation and the heat treatment is extremely large.

In view of the above-mentioned conventional problems, the present invention significantly reduces the glare on the display surface in a display element, particularly a VFD of the type in which the display is observed from the side opposite to the electron excitation surface of the phosphor (substrate side), and The present invention has been made in order to improve the display quality, and provides a heat-resistant black electrode having high heat resistance that can withstand heat treatment in a manufacturing process such as VFD, good patterning property, and higher blackness. It is an object.

[Means for Solving the Problems]

The heat-resistant black electrode according to the present invention, on a translucent insulating substrate,
A black thin film containing at least one of Al and Mo oxides in a heat resistant metal or a black thin film containing at least one of Al, Mo and those oxides in a heat resistant metal oxide. A black thin film (intermediate black thin film) or a Mo thin film (intermediate Mo thin film) having a lower degree of oxidation than the above black thin film is formed thereon, and an Al thin film is further laminated thereon to form a three-layer thin film. To do.

At this time, the refractory metal and its oxide are Ti,
At least one of Cr, Mn, Zr, Mo, W and oxides thereof is used as a main constituent material.

[Action]

In the heat-resistant black electrode in the present invention, the degree of blackness is high, and the adhesion between each thin film and the translucent insulating substrate is excellent,
Heat treatment process for display elements such as VFD (approx. 580 in air)
It has heat resistance capable of withstanding the temperature (° C.), and good patterning can be performed with the same etchant A as the conventional one.

〔Example〕

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

Example 1 FIG. 1 is a main cross-sectional view showing an example of a heat-resistant black electrode according to the present invention. Here, a heat-resistant black electrode according to the present invention is placed on a glass substrate for VFD of a type in which light emission is observed from the substrate side. It shows a case where is manufactured. That is, in this embodiment, as a sputtering target of the black thin film and the intermediate black thin film, the Al oxide small piece 2 is embedded in the Mo plate 1 as shown in FIGS. 2 (a) and 2 (b) in an area ratio of about 40%. The composite target 3 is used, and a film thickness of about 500 is formed on the glass substrate 11 for VFD by Ar gas using an ordinary sputtering method.
A black thin film 12 of Al ₂ O ₃ : Mo of Å is formed. Subsequently, a composite target having an Al oxide content slightly smaller than that of the composite target 3 is used on the black thin film 12 by a sputtering method under the same conditions as described above to obtain a film thickness of about 800.
On the intermediate black thin film 13 of Å, an Al plate was used as a target and Ar gas was used in the same manner by a sputtering method to obtain a film thickness of about 1.5 μm.
Al thin films 14 were laminated to form a black electrode 15 composed of these three-layer thin films. Then, this black electrode 1
When the VFD was manufactured by flowing the glass substrate 11 on which 5 was formed into a VFD manufacturing process similar to the conventional one, the spectral reflectance of the black electrode 15 was about 10% or less in the visible light range of 380 to 780 nm, and The value in the vicinity of 550 nm, where human visibility is high, is as low as 5 to 6% (see FIG. 3), and an electrode having higher blackness than the conventional two-layer structure proposed by the present inventors was obtained. In addition, the black electrode 15 configured in this manner has excellent heat resistance (small change in reflectance between immediately after film formation and after heat treatment) and good performance as compared with the conventional black electrode 15 having a two-layer structure. It has a patterning property, and no whitening, peeling, conduction failure, etching failure, etc. of the electrode were observed in the heat treatment process.

Example 2 In this example, a black electrode having a three-layer structure using a Mo thin film as an intermediate layer was manufactured. First, as in Example 1, the Al ₂ O ₃ : Mo black thin film 1 having a film thickness of about 500Å was formed on the glass substrate 11.
2 is formed on the black thin film 12, and a Mo plate as an intermediate layer is sputtered with a target of Ar gas to deposit a thin film of Mo having a thickness of about 1000Å. A 1.5 μm Al thin film 14 was laminated to form a black electrode. When the black electrode thus constructed was patterned using a phosphoric acid-based Al etchant similar to the conventional one, no peeling of the film or disturbance of the electrode pattern occurred, and the spectral reflectance was the same as in Example 1. Same as 380 ~ 7
The value is approximately 10% or less in the visible light region of 80 nm, and the value is around 5% at around 550 nm where human visibility is high (3rd
(See the figure).

Example 3 In this example, a composite target in which Mo oxide was embedded in an Al plate was used as a sputtering target for forming a black thin film. First, the film thickness is about 500Å on the glass substrate 11.
MoOx: Al black thin film was formed. At this time, the occupied area of Mo oxide on the surface of the composite target is about 50%,
Ar gas was used as the sputtering gas. Next, on this black thin film, an intermediate Mo thin film with a film thickness of about 1000Å,
On the thin film, an Al thin film 14 having a thickness of about 1.5 μm was deposited by each sputtering method to produce a black electrode. Also in the black electrode thus configured, high blackness, heat resistance and good patterning property were obtained as in the case of Examples 1 and 2 described above.

According to the experiments conducted by the inventors, the black thin film and the intermediate black thin film used in the present invention have Al, A and A in the composite target.
It is possible to etch with a phosphoric acid etchant by including at least one of 1 oxide, Mo and Mo oxide, and the Mo intermediate layer can also be etched with the above etchant. Therefore, it is necessary to change the conventional patterning process. No Ti, Cr, Mn, Zr, M
o, W, Si and at least one of these oxides
By including one of them, a black electrode having excellent heat resistance could be manufactured.

〔The invention's effect〕

As described above, according to the present invention, as compared with the conventional heat-resistant black electrode having a two-layer structure, the heat resistance in the manufacturing process of the display element such as VFD is high and the blackness is excellent in the patterning property. It is possible to obtain a black electrode with high efficiency. Therefore, by using the black electrode according to the present invention as a wiring material, it is possible to inexpensively provide a VFD of a type viewed from the side opposite to the electron excitation surface of the phosphor having an extremely excellent display quality, and at the same time other than the above VFD. Similar effects can be obtained when used as a back electrode of another display element, for example, a thin film EL display element.

[Brief description of drawings]

FIG. 1 is a main sectional view showing an embodiment of a black electrode according to the present invention, FIGS. 2 (a) and 2 (b) are plan views showing an example of a composite target used in the above embodiment, and BB 'thereof. FIG. 3 is a diagram showing a typical example of the spectral reflection characteristics of the black electrode according to the present invention, and FIG. 4 is a diagram showing an example of the spectral reflectance of the conventional heat-resistant black electrode having a two-layer structure. is there. 1 ... Mo plate, 2 ... Al oxide, 3 ... composite target, 11 ... glass substrate, 12 ... black thin film, 13 ...
Intermediate black thin film, 14 ... Al thin film, 15 ... black electrode.

Claims (1)

[Claims] 1. A heat-resistant metal in a transparent insulating substrate
a black thin film containing at least one of the oxides of 1 and Mo or a black thin film containing at least one of Al, Mo and those oxides in a heat-resistant metal oxide An intermediate black thin film or an intermediate Mo thin film having a degree of oxidation lower than that of the black thin film is deposited on the thin film, and an Al thin film is further laminated on the intermediate black thin film or the intermediate Mo thin film to form a three-layer thin film. A heat-resistant black electrode characterized by that.