JPH0212796A - Forming method for electrode of thin film el element - Google Patents

Abstract

PURPOSE:To drive EL element at a low voltage and simplify a manufacturing process by using an organic alkali solution as a liquid developer of resist and an etchant of Al film. CONSTITUTION:In a forming method for a back plate, an organic alkali solution as a liquid developer of resist and an etchant of Al film is used. The same organic alkali solution is used as a liquid developer of resist and an etchant of Al film, so that the resist can be developed and the Al film, etched at the same time to simplify the process and use Sm2O3 or HfO2 easily affected by acid for an insulation layer at the lower layer of a back plate.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention provides a thin J
The present invention relates to a 1% EL element, and particularly to a method for forming electrodes thereof.

(Prior Art) Generally, a thin film EL device is manufactured by forming an Inn20.
．． A large number of band-shaped transparent electrodes made of 5n02 etc. are formed,
Y, O, on top of this.

Forming a first insulating layer made of TiO2, 5in2, etc.
A light emitting layer obtained by electron beam evaporation of ZnS:Mn sintered pellets is formed thereon, a second insulating layer made of the same material as the first insulating layer is formed, and a second insulating layer made of the same material as the first insulating layer is formed. A! are arranged in parallel in the direction perpendicular to the transparent electrode. It is constructed by forming a large number of strip-shaped back electrodes made of QM. Further, a Ni film is usually formed on the Al film as an electrode lead terminal. In such a thin film EL element, a method for forming a back electrode number is disclosed in Japanese Patent Publication No. 62-48358, etc., and as shown in FIG. and N1 film are sequentially stacked.

Then, a positive type resist (for example, 0FPR-800 manufactured by Tokyo Ohka Co., Ltd.) is applied to the entire surface of N1Jll, and prebaking is performed at a temperature of about 85° C. in order to evaporate the solvent in the resist.

Next, a band-shaped patterned mask is placed over the resist and exposed to light, and a developer is flowed to remove the resist in the areas irradiated with light. Then, in order to increase the adhesion of the remaining resist, a post-bake is performed at a temperature of about 100°C, and then NiI! is applied using a dilute nitric acid-based etching solution at room temperature. li, and then etched the Al film using an etching solution for An film made of a phosphoric acid/nitric acid mixture heated to 40 to 60''C to obtain N1FtlA and AC films etched into strips. , the resist is resistant to acid-based etching solutions (remains on the Ni ridge). Then, after drying, in order to form electrode extraction terminals, a mask with a pattern covering the corresponding portions of the terminals is placed above the resist. Overlapping double exposure is performed, and then development is performed to remove unnecessary resist on the N1JIA.Then, the N1 film is etched again using a dilute nitric acid-based etching solution at room temperature, and finally the resist is peeled off. A back electrode is formed by a band-shaped Al film facing the electrode and a Ni 15 film (at the upper end of /iv/, which serves as an electrode extraction terminal for connection to an external circuit).

(Problems to be Solved by the Invention) In the above-mentioned prior art, since an acid-based etching solution such as a phosphoric acid/nitric acid mixed solution is used as the etching solution for the An film, the second insulating layer which is the underlying layer is used as the etching solution for the An film. is Al2
Only acid-resistant materials such as 03 and SiO2 could be used. However, when these materials are used, there is a problem that the withstand voltage becomes high and the driving voltage of the EL becomes high. Also, like the prior art, AlII! When using double exposure to leave a Ni film on the edge of the Al film in the double-layered back electrode of /N1WA, the process becomes quite complicated if an acid-based etching solution is used to etch the AlWA.

Therefore, the present invention has been made based on the above-mentioned problems, and an object of the present invention is to provide a method for forming electrodes of a thin film EL element, which can lower the driving voltage and simplify the process. be.

[Structure of the Invention] (Means for Solving the Problems) The present invention uses an organic alkaline solution as a resist developer and an AΩ film etching solution in a method for forming a back electrode.

(Function) By using the same organic alkaline solution as the resist developer and the Al film etching solution, resist development and Alfi etching can be performed at the same time, simplifying the process, and improving the insulating layer below the back electrode. Sm is weak against acids as
20. Materials such as HfO2 and HfO2 can be used.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings. In FIG. 3, a large number of band-shaped transparent electrodes 2 are formed on a glass substrate [1], and on top of this are formed Sm20. A first insulating layer 3 made of an insulating material such as or HfO is formed, a light emitting layer 4 is formed on this, and a second insulating layer 3 made of the same material as the first insulating layer 3 is further formed on top of this. Layer 5 is formed. Then, on the second insulating layer 5, AlJI is applied over the entire substrate.
! 6 and N1g7 are formed successively in the same vacuum.

Next, using a photo-etching process, the An
A method for processing the film 6 and the Ni film 7 for the electrode lead terminal into stripes will be explained based on FIGS. 1 and 2.9 First, as shown in FIG. A positive type resist 8 is applied to the surface using a spinner or the like. Then, a lick 85 for evaporating the solvent in the resist 8
Pre-bake is performed at a temperature of about ℃. Next, Figure 2 (B
), a mask 9 having a band-shaped light transmitting portion 9At
is placed on top of the resist 8 and irradiated with light to perform exposure.
Thereafter, by developing using an organic alkaline solution containing tetramethylammonium hydroxide and water as main components (for example, NMD-3 manufactured by Tokyo Ohka) as a developer, the unexposed part resist 8
Only A remains. The mixing ratio of this tetramethylammonium hydroxide to water is 2 to 3 weights and 1%. After rinsing and drying by air blowing, etc., a boss bake is performed at a temperature of approximately IOOC to increase the adhesion of the resist 8A, but the steps up to this point are the same as the conventional example shown in FIG.

Next, in order to leave the Ni film 7 only on the electrode extraction terminal,
As shown in FIG. 2(D), mask 1 is placed on resist 8A.
By performing double exposure and etching the Ni film 7 using a dilute nitric acid-based etching solution at room temperature, a band-shaped Ni film 7 is formed as shown in FIG. 2(E).
or is formed. At this time, the resist 8A does not react with the acid-based etching solution, so NiB! The resist 8A remains on A7. Next, etching of AQJ1!6 is carried out. As the etching solution, an organic alkaline solution containing tetramethylammonium hydroxide and water as the main components, which is the same as the developer described above, is used. As a result of this etching, the A IQ film 6 is etched into a band shape as shown in FIG.
Next, using dilute nitric acid-based etching solution again, Ni17 was etched.
By performing this etching, only the Ni film 7 corresponding to the electrode lead terminal remains as shown in FIG. 2(G), and finally, the resist 9B is peeled off to form a back electrode.

As described above, according to the present invention, the resist developer and A
An organic alkaline solution is used as the 1M6 etching solution. For this reason, the second insulating layer 5 as the underlying layer of A QM, 6 is made of Sm20. Insulating materials such as HfO2 and HfO2 can be used. When these materials are used, the driving voltage becomes low, and it becomes possible to drive the EL element at a low voltage. Furthermore, by using an organic alkaline solution, double exposure is performed before etching the Ni film 7 in the first half, and after etching the Ni film 7, the etching of A I;:LH6 and the phenomenon of the resist 8A are simultaneously performed. In addition, after etching the Al film as in the conventional method,
Since the step of drying for double exposure is also unnecessary, the process can be greatly simplified. In the latter half of the N1M7 etching step, an etching solution of dilute nitric acid flows onto the second insulating layer 5, but this etching solution has weak acidity and therefore has almost no effect on the second insulating layer 5.

Although one embodiment of the present invention has been described in detail above, it can be modified as appropriate within the scope of the gist of the present invention.

For example, in the above embodiments, the back electrode has a two-layer structure of Ill and Ni films, but the present invention can be similarly applied to a single-layer structure of Al films.

[Effects of the Invention] As detailed above, according to the present invention, by using an organic alkaline solution as a resist developer and an Al film etching solution, it is possible to drive the EL element at a low voltage, and the process can be simplified. It is possible to provide a method for forming electrodes of an RI film EL element that can be

4,

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the steps of an embodiment of the present invention;
Figures 2 (A) to (G) are schematic explanatory diagrams along the process;
The figure is a sectional view, and FIG. 4 is a flowchart showing a conventional process. 6...Al film 8...Resist figure 4 procedure? m Official document 1 (Indication of the incident August 10, 1988 Patent application No. 1 62018 2, Title of the invention i [Electrode formation method for EL element 3, Person making the amendment

Claims (1)

[Claims] (1) At least Al is used as the back electrode of the thin film EL element.
In a method for forming electrodes of a thin film EL element, in which films are laminated and the Al film is processed into a predetermined shape by photo-etching, a developer for a resist applied on the Al film and A
1. A method for forming electrodes of a thin film EL device, characterized in that an organic alkaline solution is used as an etching solution for the film.