KR950013666B1 - Thin el display element and manufacture method thereof - Google Patents

Abstract

The thin film EL display device wherein a transparent electrode, a first insulating layer, a fluorescent layer made of ZnS: M, Sm, Tb, Tm, a second insulating layer and an Al rear electrode are sequentially formed over a transparent glass substrate, is characterized in that the ZnS: Mn, Sm, Tb, Tm constituting the fluorescent layer are composed with uniform concentration, thus making the inherent wave length of red, blue and green colors uniform.

Description

Thin film EL display device and manufacturing method thereof

1 is a cross-sectional view showing a configuration of a conventional thin film EL display element.

Fig. 2 is a sectional view of a deposition machine for manufacturing the thin film EL display element of the present invention.

* Explanation of symbols for main parts of the drawings

1: transparent glass substrate 2: transparent electrode

3: first insulating layer 4 ': fluorescent layer

5: second insulating layer 6: Al back electrode

8 main body 9 substrate support

10: ZnS Fert 11: Crucible

12 electron beam source 13 dopant

14 ceramic crucible 15 resistance wire

The present invention relates to a thin film EL display device and a method of manufacturing the same, in particular the fluorescent layer of the thin film EL display device is ZnS; A thin film EL display device manufactured by Mn, Sm, Tb, and Tm so as to be suitable for a white light source of a full color display device using a filter, and a manufacturing method thereof.

Conventional thin-film EL display devices for monochromatic display include devices displaying yellow orange light using ZnS: Mn as phosphors, red light display devices using CaS: Eu as phosphors, blue light display devices using SrS: Ce as phosphors, and ZnS : A green light display device using TbF ₃ as a phosphor is known, and as a method for manufacturing a full color thin film EL display device, a red light using CaS: Eu as a phosphor and a phosphor using ZnS: Tb as a phosphor are generally known. Using green light and blue light using SrS: Ce as a phosphor, there is a method of laminating these layers onto each EL film on one glass substrate, and etching each layer to line red, green and blue fluorescent films on one plane. There is a stripe method in which it is arranged in a line to make one pixel, but this method requires a large amount of work in the manufacturing process and The only cause bad also has a lot of weaknesses, such as not using the signs as jegusil.

For this reason, a method of filtering red, green, and blue wavelengths using a white light as a filter has been in the spotlight as a new method for manufacturing a full color display panel more easily.

The structure currently being studied with this white light source is a method of forming a ZnS: Mn thin film on both sides of a SrS: Ce fluorescent layer and using it as a fluorescent layer and a method of using light obtained by using ZnS: PrF ₃ as a fluorescent layer. However, since all of them have low luminous luminance and not all wavelengths in the field of view, even if the filter is used, the luminance is further lowered to obtain even luminance distribution of red, green, and blue required for full colorization. There was a problem with many difficulties in practical use because there is no.

The present invention has been made in view of the above-mentioned problems. In a thin film display device in which ZnS: Mn is used as a fluorescent layer, pure white light can be obtained by forming a fluorescent layer using a unique phosphor to be described later instead of ZnS: Mn. It is to provide a method of manufacturing the thin film EL display element which makes it possible.

Prior to explaining the present invention, a typical example of a thin film EL display device in which a conventional ZnS: Mn is used as a fluorescent layer will be described in more detail with reference to FIG.

In the conventional thin film EL display device, a transparent electrode (ITO) 2 is coated on the transparent glass substrate 1 to a thickness of about 2000 microseconds, and line-etched to a desired width by photoetching, and the first insulating layer 3 having a high dielectric constant thereon is formed thereon. After coating to a suitable thickness, the concentration of the phosphor and the dopant according to the wavelength of the desired light is selected, and after coating the phosphor to a thickness of about 1㎛ to form the fluorescent layer 4, the first insulation again The second insulating layer 5 is formed in the same manner as the layer 3, and Al is coated thereon by thermal evaporation or sputtering to a thickness of 2000 Å and line-etched to a desired width perpendicular to the transparent electrode 2. An Al back electrode 6 was formed, and the EL display panel thus formed was encapsulated with silicon oil or the like on the back side to protect the cornea from moisture and to mitigate external shock.

In the conventional thin film EL display device as described above, when an alternating voltage of about 200 V is applied between the transparent electrode 2 and the back electrode 6, a high field (˜MV / Cm) is generated in the insulating layer and the fluorescent layer. The surface electrons of the layer 4 and the insulating layer 3 and 5 are accelerated, and the hot electrons having energy collide with the phosphor and the emission center. Here, when the electron in the ground state of the light emitting center jumps to the energy level in the excited state and returns to the ground state, light of a wavelength having energy equal to this energy difference is generated. At this time, the intensity of light strongly depends on the thickness doping concentration of the fluorescent layer 4, the thickness uniformity of the cornea, etc. in addition to external factors such as the applied voltage and frequency, and the emitted light is the first insulating layer 3 and the transparent electrode. (2) Then, it comes out through the transparent glass substrate 1 and selectively emits each pixel to display a desired image.

As described above, the EL display device illustrated in FIG. 1 forms a fluorescent layer 4 by doping ZnS to an appropriate concentration, and coating it by electron beam deposition or sputtering, so that only light having a unique wavelength according to the dopant is emitted. Will be.

In the present invention, the fluorescent layer in the above-described EL display device has a new structure in which ZnS is a doped phosphor and a dopant is doped with Mn, Sm, Tb, and Tm to cover all wavelengths of the visible region. The present invention provides an EL display device and a method for manufacturing the same, which are suitable for a filter-use display device being studied in the main direction of a full color display panel by emitting white light.

That is, referring to FIG. 1, the transparent electrode 2, the first insulating layer 3, the fluorescent layer 4 ′, the second insulating layer 5, and the Al back electrode are disposed on the transparent glass substrate 1. (6) is sequentially stacked, and the fluorescent layer 4 is formed of ZnS: Mn, Sm, Tb, and Tm to display high luminance white light.

In manufacturing the thin film EL display device of the present invention, the transparent electrode 2 is formed by sputtering about 2000 kV of ITO on the transparent glass substrate 1 from which Na ions are removed, and Y ₂ O ₃ or Al ₂ O ₃ is deposited by electron beam deposition. Coating to form a first insulating layer (3) and then fixing the substrate (7) thus secured to the substrate support (9) inside the deposition base (8) as a second degree, and ZnS pellets (10). Is deposited into a crucible (11) and heated with accelerating electrons generated from the electron beam source (12) to deposit ZnS. At this time, dopants 13 such as Mn and SmF ₃ , TbF ₃ , and TmF ₃ are respectively placed in a small ceramic crucible 14. It is heated by the resistance wire 15 and deposited by an independent power source. In the figure, 16 shows a power line.

At this time, the entrance of the ceramic crucible 14 into which the dopant 13 is placed is made small so as to accurately adjust the doping concentration, and to prevent the dopant 13 from being widely diffused in the evaporator, and at the same time, rotate the substrate support 9 at a constant speed. A uniform thin film is obtained.

In order to make the ratio of ZnS and each dopant uniform and to improve the crystallinity of ZnS, the deposition rate of ZnS should be very small (1-2Å / sec), and Mn, SmF ₃ , TbF ₃ , and TmF ₃ may be converted into ceramic crucibles (14). ), It should be deposited at a very small deposition rate. Thus formed ZnS: Mn, Sm, Tb, Tm fluorescent layer (4 ') has a total thickness of 1-1.2㎛ and immediately heat treatment at 450-500 ℃ for 1 hour to achieve a uniform doping concentration in ZnS To have. Thereafter, a second insulating layer 5 is formed on the ZnS: Mn, Sm, Tb, and Tm fluorescent layers 4 'like the first insulating layer 3, and an Al back electrode 6 is formed thereon. .

The EL display device fabricated as described above is orange-yellow generated in ZnS: Mn due to a high field of about 2MV / Cm induced in the fluorescent layer 4 'when a voltage of about 200V is applied to the positive electrodes 2,6. In addition, it has the red, green, and blue inherent emission wavelengths of ZnS: Sm, ZnS: Tb, and ZnS: Tm, so that white light covering the full visible region of more uniform luminance is one light emitting layer in the fluorescent layer 4 '. Generated and displayed through the insulating layer 3, the transparent electrode 2, and the transparent glass substrate 1;

ZnS: PrF ₃ , SrS: Ce / ZnS: Mn, SrS: Ce, Eu, etc., which are used as a white light source in a color EL display device by a conventional filtering method, have sufficient luminance and color because they cannot cover the full visible region. Although it was not possible to derive rich colors, the thin film EL display device manufactured according to the present invention has a simple manufacturing process of the ZnS: Mn, Sm, Tb, and Tm fluorescent layers, and also uses only ZnS as a matrix, so that SrS or CaS is used. The EL element used as a ZnS: Mn, Sm, Tb, and Tm fluorescent layer has a high brightness to compensate for the low luminance such as ZnS: PrF ₃ , which is conventionally used, and has a full filter. The effect of producing the ideal white light source of a color display device very simply is also great.

Claims (2)

Transparent electrode 2, first insulating layer 3, ZnS: fluorescent layer 4 'formed of Mn, Sm, Tb and Tm on transparent glass substrate 1, second insulating layer 5 and Al back electrode (6) is sequentially stacked, characterized in that ZnS: Mn, Sm, Tb, and Tm constituting the fluorescent layer 4 'are uniformly intrinsic in red, blue, and green at a uniform concentration. Thin film EL display element. In manufacturing a thin film EL display element using a rotatable substrate support 9, a crucible 10 containing phosphors, and an electron beam source 12 for generating accelerating electrons, a conventional evaporator provided in the main body 8 is used. To the crucible 11 while rotating the substrate 7 on which the transparent electrode 2 and the second insulating layer 5 are formed on the transparent glass substrate 1 to the substrate support 9 of the vapor deposition body 8. Mn, SmF ₃ , TbF ₃ , TmF ₃ and the like are heated in several ceramic crucibles 14 which are heated around the crucible 11 while heating the contained ZnS ferrite 10 with the accelerating electrons generated from the electron beam source 12. ZnS: Mn, Sm, Tb, and Tm fluorescent layers were placed on the first insulating layer 3 of the substrate 7 by separately heating the dopant 13 with the resistance wire 15 wound around the crucible 11. And (4 '). A method of manufacturing a thin film EL display device, characterized by depositing 4'.

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