JPS6326994A - Thin film electroluminescence device - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a thin film electroluminescence sensing element (hereinafter referred to as a thin film EL element) which has high brightness, high breakdown voltage, and is resistant to photo-processing of a back metal electrode film. [Prior art] A group 14 compound conductor, such as zinc oxide (ZnS), is used as a matrix, and manganese (Mn) is used to form a luminescent center therein.
Alternatively, a thin film doped with a rare earth compound or the like is used as a light-emitting layer, and an insulating film such as a oxide or nitride or @(dielectric/il) thin film is provided on both sides of the light-emitting layer in the form of a sandwich. It is well known that a thin film EL element is sandwiched between a pair of opposing electrodes, one of which is transparent. ! It is known that by applying an alternating current of 130 nm between the electrodes, it emits light with high brightness and has a long life. In the figure, 1 is a glass 2 substrate, 2 is IflO:5I
LO□ Transparent monopolar film made of silence, 3 is TA205, Y2
A first insulating layer film made of O3, Sm2O3, etc., 4 is ZnS or Sr added with Mn or a rare earth compound.
S # IW group compound semiconductor light emitting, 9 films, 5 is the same as 3, 2nd. Other class layers, 6 (is different from At etc. back metal M)
There is an L electrode film.

When an alternating current voltage is applied to a thin film EL element with such a structure and the electric field strength inside the light emitting atmosphere is approximately 10'V/(7), nine electrons are generated from the interface between the barrier layer and the light emitting layer 1, and nine electrons are emitted. The light travels within the layer while being accelerated by an electric field (==), and is obtained at the EL source 75 by collision-exciting the luminescent center substance.

[Problems to be Solved by the Invention] As shown in Figure K4, the device has a structure in which a light-emitting layer film is sandwiched between insulating layers and films, which is usually called an insulating structure. Maximum charge density flowing through '! ! (Q
max) is determined by the Qmax of the ee layer M. ,
A large Qrne x of the element means that the voltage at which the element breaks down (vBD) and the II king (vop) during operation of the element
It is desirable to use an insulating layer with a large Qmax from the viewpoint of increasing the reliability of the thin film EL element. Also,
The larger the Qmax, the higher the brightness of 1° can be obtained. However, among the insulating layer materials used in thin film EL devices, materials with a large Qmax usually have
These materials are called dielectric constant materials, and these materials have a weak adhesion to the light-emitting layer.

Therefore, it is preferable to use a material with a large Qmax (for example, Ta203) as the insulating layer of a thin-film EL element from the viewpoint of customizing light emission. For example, when a back metal electrode film of 1 m is made of At and buttered with a +14.M etching solution, Ta
The etching solution penetrates into the interface between 205 and ZnS, and 'r
a2o5 The problem is that the pattern peels off.

On the other hand, in a device using only an insulating layer film as an insulating layer, which has strong adhesion to the light emitting layer film, the Qmax of the insulating layer film itself
Because of its small size, both its breakdown voltage and brightness were low.

The present invention was invented to solve this drawback.
7i8 edge/i! between the light emitting layer and the back metal electrode film in the thin film EL device structure. To provide a thin film electroluminescence element with high brightness, high breakdown voltage, and high resistance to photo-etching of the back metal electrode film by forming a composite structure in which two or more types of insulating layers are laminated. Means for Solving Problem C] The present invention provides a thin film in which a thin structure is sandwiched between a pair of electrodes, and an alternating current voltage is applied between the electrodes to emit light. In electroluminescence electronics, the insulating layer between the light emitting layer film and the back metal electrode film is characterized by a structure in which two or more types of insulating 7# films are laminated.

[Example of actual address]

Embodiments of the present invention will be described below with reference to the accompanying drawings. It should be noted that the examples are merely illustrative, and it goes without saying that the implantation may be modified or improved without departing from the spirit of the present invention. In the figure, 7 is a glass substrate, 8 is a transparent electrode film, 9 is an insulating layer film, and 10 is a cross-sectional configuration diagram.
11 is an insulating # film with strong adhesion to the emissive layer film; 12 is an insulating # film with weak adhesion to the emissive layer film.
# Membrane, 13 is back metal 1! It is a c-polar membrane.

Back metal 1! using an element with such a structure! When photo-processing the c-electrode film, there is an insulating layer film with strong adhesion to the light emitting layer film between the light emitting layer and the light emitting layer film (41! Iwk layer film with weak adhesion to the two). The back metal electrode film can be photo-processed without any adverse effects on the copying film structure 1.

Next (2) The above embodiment will be explained in more detail.

After plotting the thin film EL device shown in FIG. 1, Corning 7059 (trade name) was used as the glass substrate 7. In2O3: 5no2 transparent type ftjl on this glass substrate
J 8 200 nm% primary film formed by sputter deposition method, Ta205 as insulating 1M film 9, 300 nm thick by high frequency magnetron sputtering method, Q optical layer film 1
ZnS as 0:Mn was deposited to 500 nm by electron beam evaporation, if&M, [Sm2O as 11].
3 using electron beam evaporation! l 50 nm% As the insulating layer film 12, 300 nm of T8□05 was added to the same machine as 9.
, , 'mR1 product, ja was formed 6 and finally, as the back metal layer 13, At was formed to a thickness of 9100 nm by electron beam evaporation to fabricate a thin film EL device. At the same time, we created an element with a conventional structure except for the insulating layer 11 from the above structure. Hereinafter, the element including the insulating layer 11 will be referred to as element A, and the element without it will be referred to as element B. Next, an element having exactly the same configuration as element A but patterned by mask deposition of a back metal 'a' electrode film was also tabulated. This element is referred to as element C. When the back At electrode films of these elements A1 and B were processed with an etching solution having a composition of phosphoric acid: nitric acid: acetic acid: water = 35:14 near:3, no difference was observed in element A. ≠While we were able to process the back At electrode and the back surface without any problems,
Now, after about 30 seconds of soaking in the etching solution, the ZnS
The etching solution began to enter between the light emitting layer film and the T^205 insulating layer film, and after one minute, it was observed that the Ta2 (15 film) was peeled off over almost the entire surface. This state is shown in Figure 2. At this point, element B becomes unusable.9 As is clear from the above results, the element of this example has significantly improved resistance to photoprocessing process C2 than the conventional element. Figure @3 shows a comparison of the custom-made brightness and voltage of element A whose back metal electrode film is patterned by photo processing and element C which is patterned by mask vapor deposition.
song? Rc represents the customization of element C, respectively. curve a
As can be seen from , and the song IC, both pixel elements show exactly the same brightness-voltage #P note, and the photo-processing process of the back metal electrode film had a negative impact on the custom-made elements. As you can see, it is an insulating layer film with strong adhesion to the light emitting layer film.

S10□, Si3N4, Al2O instead of Sm2O3
3. A similar effect was obtained using a thin film of Y2O3. Also, the thickness of the insulating layer, which has strong adhesion to the light emitting layer, is important from the viewpoint of minimizing the increase in driving voltage.
Q-150 nm is suitable.

Note that the present invention and its effects are not limited to the round materials described in the above examples (for example, the light-emitting layer may be ZnS to which rare earth compounds such as Th% Sm and Co are added, or Sr8%). CaS #1-■
Group compound semiconductor thin film, wc1 figure 4[! 1Fli layer 12
5rTiO% is used as an insulating layer with a large Qmax for
BaTi0% pb'rio% Ba
A similar effect can be expected by using a TaO3 thin film, etc.
[Effects of the Invention] According to the present invention, the insulating weight between the light-emitting layer film and the back metal electrode film is 211 or more, and the structure is made by laminating F8 edge layer films, so that the insulating layer adjacent to the light-emitting I4 film is The film is a light-emitting layer film (
: It is possible to form an insulating layer film with strong adhesion to the film, and in this case, it is possible to prevent the etching solution from entering during photo-processing, and to prevent any adverse effects on the thin-film structure (photo-processing can be avoided). Therefore, according to the present invention, since the resistance to the photo-processing process can be increased, a high-performance thin-film KL display panel with high brightness, high breakdown voltage, and high reliability can be manufactured.

[Brief explanation of drawings]

Figure 81!1 is a cross-sectional view of a thin film EL element shown as an example of the present invention, and Figure 3g2 is a conventional element after the photo-processing process!
8 is a photograph showing a state in which the edge layer film has been peeled off, and shows the structure of the joint between the light emitting layer film and the insulating layer film. FIG. Figure 4 is a cross-sectional view of a conventional thin film EL element.
7...Glass substrate, 8...Transparent electrode film, 9.12...Insulating layer film with weak adhesion to the light emitting layer film, 10...Light emission /lll membrane, 11...
...Insulating layer film with strong adhesion to the light-emitting Ijl film,
13...Back metal 'electrode film.

Claims (2)

[Claims] (1) In a thin film electroluminescent device in which a thin film structure is held between a pair of electrodes and an alternating current voltage is applied between the electrodes to emit light, two insulator layers are formed between the light emitting layer film and the back metal electrode film. A thin film electroluminescent device characterized by having a structure in which more than one type of insulating layer film is laminated. (2) One type of insulator layer between the light emitting layer film and the back metal electrode film is Ta_2O_5, and the others are SiO_2 and Al.
_2O_3, Si_3N_4, Sm_2O_3, Y_2
The thin film electroluminescent device according to claim 1, characterized in that one of O_3 or a plurality of layers thereof is used, and the insulating layer adjacent to the light emitting layer is an insulating layer other than Ta_2O_5. sense element.