JPH0348879Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a thin film EL element that generates EL (electroluminescence) light upon application of an alternating current electric field.

[Prior art]

As a conventional thin film EL element, there is one described in Patent Application No. 19128 of 1982, for example.

FIG. 2 is a cross-sectional view of the above thin film EL element.

In Fig. 2, In ₂ O ₃ and
Transparent conductive film 2 such as SnO ₂ , first film such as Y ₂ O ₃ or Si ₃ N ₄
A dielectric film 3, a light emitting film 4 made of ZnS containing a small amount of Mn, and a second dielectric film 5 made of the same material as the first dielectric film 3 are sequentially laminated by electron beam evaporation or sputtering, A transparent multilayer film 100 is formed by these 2 to 5.

The film thickness of each part above is 5000Å for the dielectric film.
The thickness of the luminescent film is approximately 6000 Å.

Further, the mass film thickness on the second dielectric film 5 is 50~
An island absorber film 6 made of a 300 Å Mo film is formed by electron beam evaporation or sputtering.

Note that this island-like absorber film 6 can be replaced with another metal film or semiconductor film having an island-like structure, such as Ta, Cr, Si, or the like.

Furthermore, a transparent dielectric film 7 such as Al ₂ O ₃ having a film thickness of about 500 Å is formed on the island-like absorber film 6, and a metal film 8 such as Al is deposited on it by vapor deposition or sputtering. Then, stack them one by one.

These 6 to 8 form the blackened back electrode 200.

The transparent conductive film 2 and the blackened back electrode 200 are patterned into a suitable shape by ordinary photolithography.

In the above device, when an AC voltage is applied between the transparent conductive film 2 and the blackened back electrode 200, and the electric field within the luminescent film 4 reaches 1 to 2×10 ⁶ V/cm, the two electrodes The sandwiched portion emits light to display the patterned shape.

Therefore, it is desirable to use a material with a high dielectric constant as the first and second dielectric films.

In addition, in the device shown in FIG. 2, since the blackened back electrode 200 is used as described above, the external light that has entered through the transparent multilayer film 100 is absorbed by the island-like absorber film 6 and the transparent dielectric film 7. As a result, the contrast in bright environments is significantly improved compared to elements using high-reflectance metals such as Al for the back electrode.

[Problem that the invention attempts to solve]

In the conventional element as described above, the blackened back electrode has a structure in which the transparent dielectric film 7 is sandwiched between the island-like absorber 6 and the metal film 8, so the driving voltage increases (approximately 5% increase). Therefore, it is necessary to increase the breakdown voltage of the drive element, which causes a problem of increased manufacturing cost of the drive circuit.

Further, since the transparent dielectric film 7 is formed on the island-like absorber film 6 which is itself very thin and has large irregularities, its dielectric properties become extremely unstable and dielectric breakdown is likely to occur. This causes a decrease in yield during manufacturing.

The present invention aims to solve the problems of the prior art as described above.

[Means to solve the problem]

In order to achieve the above purpose, in this invention,
A hole or groove reaching at least from the backmost conductive film to the frontmost conductive film of a back electrode consisting of a plurality of conductive films and dielectric films is formed in an area where the front electrode of the back electrode is not formed. By burying a conductor in the hole or groove, the frontmost surface (for example, the island-like absorber film 6) and the rearmost surface (metallic film 8) of the back electrode are electrically connected to have the same potential. It is configured to

[Example of idea]

FIG. 1 is a sectional view of an embodiment of the present invention,
The same reference numerals as in FIG. 2 above indicate the same parts.

In the embodiment of FIG. 1, the blackened back electrode 2
00, a metal film 8, a transparent dielectric film 7,
A groove 9 penetrating the island-like absorber membrane 6 is provided, and this groove 9
A conductor 10 is buried in the.

Note that the groove 9 is formed in a portion where the transparent conductive film 2 does not exist below.

To provide the above groove 9, the blackened back electrode 20
0 with a diamond cutter, or by using a processing machine that uses ultrasonic vibration, a sand blasting machine, etc.

After the cutting dust is thoroughly removed, a conductor 10 such as silver paste is embedded in this groove, and the metal film 8 is filled with a conductor 10 such as silver paste.
and the island-like absorber membrane 6 are electrically connected.

Next, the action will be explained.

The sheet resistance of the island-like absorber film 6 made of metal such as Mo, Ta, Cr, etc. is about 10 to 20 Ω, and this value is about the same as the value of the transparent conductive film 2.

Therefore, it is possible to use the island-like absorber film 6 as a power supply electrode.

With the configuration shown in FIG. 1, the electric power supplied to the metal film 8 is applied to the island-like absorber film 6 via the conductor 10, so that all the voltage applied to the thin film EL element is transferred to the transparent conductive film 2. and the island-like absorber film 6.

Therefore, the device shown in FIG. 1 can be driven with the same voltage as a normal device without the island absorber film 6 and dielectric film 7, and the problem of increased cost of the drive circuit does not occur. .

Further, since no voltage is applied to the dielectric film 7, there is no fear of dielectric breakdown occurring, and no reduction in yield occurs.

Next, FIG. 3 is a diagram showing another embodiment of the present invention,
A case where the present invention is applied to a case where the blackened back electrode 300 is formed of a multilayer film of an Al film and an Al ₂ O ₃ film (as described in Published Patent Publication No. 27506 of 1982) is illustrated. are doing.

In FIG. 3, the blackened back electrode 300 has a two-layer structure laminated in two stages: Al films 11 and 13 with a thickness of 300 Å or less and Al ₂ O ₃ films 12 and 14 with a thickness of 300 Å or less. , and has a structure in which a metal film 8 is provided thereon.

Even in the case of such an element, the blackened back electrode 3
A groove or hole 15 is provided in the hole 15 in the same manner as in the case of FIG.
and selectively placed near it.

Incidentally, instead of the conductive thin film 16, a silver paste or the like similar to that shown in FIG. 1 may be filled.

Even in the case of the embodiment shown in FIG. 3, since the supplied power is supplied to the lowermost Al film 11 through the metal film 8, the increase in driving voltage and yield due to the use of the blackened back electrode 300 can be avoided. No decrease occurs.

[Effect of idea]

As explained above, in the present invention, holes or grooves are provided in the back electrode, which has a structure in which at least one dielectric film is laminated between a plurality of conductive films, in an area where the electrode is not formed. Since the conductor is embedded in the structure, an increase in drive voltage due to the provision of the back electrode is prevented.
The manufacturing cost of the drive circuit does not increase.

In addition, there will be no dielectric breakdown, so
It is also possible to prevent a decrease in yield during manufacturing.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of one embodiment of the present invention, FIG. 2 is a sectional view of one embodiment of a conventional element, and FIG. 3 is a sectional view of another embodiment of the present invention. Explanation of symbols: 1...Glass substrate, 2...Transparent conductive film, 3...First dielectric film, 4...Light emitting film, 5...
...Second dielectric film, 6... Island-shaped absorber film, 7... Transparent dielectric film, 8... Metal film, 9... Groove, 10...
Conductor, 11, 13... Al film, 12, 14...
Al ₂ O ₃ film, 15...hole, 100...transparent multilayer film,
200...blackened back electrode.

Claims (1)

[Claims for Utility Model Registration] A transparent front electrode selectively disposed on a light-transmissive substrate; a light-emitting film formed on the substrate and the front electrode; and a light-emitting film formed on the light-emitting film. a back electrode having a structure in which at least one dielectric film is laminated between a plurality of conductor films; and at least a conductor closest to the back side on a region of the back electrode where the front electrode is not formed. 1. A thin film EL device comprising: a hole or groove formed from a film to a conductor film on the frontmost side; and a conductor embedded in the hole or groove.