JPH02244595A - Manufacture of multicolor membranous el element - Google Patents

Abstract

PURPOSE:To obtain a multicolor membranous EL element of a high reliability by etching a phosphor membrane on a large area of substrate at a high uniformity, as well as dry-etching the phosphor membrane mainly of a sulfide such as ZnS and C2S at a high speed. CONSTITUTION:A phosphor membrane 13 which consists of ZnS:Tb, F is formed on the whole surface of a glass base 10 on which an SrTiO3 membrane is formed as a transparent electrode 11 and an insulator layer 12. And a high-frequency power source 6 is operated in a vacuum container 1, an AC voltage is applied to a cathode 2, the etching of the membrane 13 is carried out at a high speed, and a resist pattern 14 on the membrane 13 is removed. Then, an anti-etching layer BaTa2O5 15 is formed on the layer 13, the second phosphor membrane CaS:Eu 16 is vacuum-evaporated on the whole surface, a resist pattern 17 is left at every third electrode 11 where the membrane 1 is not formed, the membrane 16 on the base 10 is etched evenly, and an anti-etching layer BaTa2O5 18, and the third phosphor membrane SrSC6 19 are formed on the whole surface and heat-treated. And a back electrode 22 crossing square to an insulating layer 21 and the electrode 11 is formed, to complete a multicolor membranous EL element.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method of manufacturing a multicolor thin film EL element suitable for character display, graphic ink display flat displays, and the like.

BACKGROUND OF THE INVENTION When manufacturing a thin film EL device for multicolor display, a method of arranging a plurality of phosphor thin films in a predetermined pattern is a practical method from the viewpoint of simplicity of device structure and stability of characteristics. To form a thin film layer into a fine pattern, a thin film is formed uniformly over the entire surface, then a photoresist pattern is formed, and unnecessary material is removed chemically using a solution or physically using gas plasma. A common method is to remove (etch) the part.

When trying to form a phosphor thin film in a thin film EL layer into a predetermined pattern, its constituent materials such as C, S1S, and S are extremely sensitive to acids and moisture, so chemical methods using solutions are required. It is not suitable for etching.

Therefore, physical etching (dry etching) methods such as sputter etching and reactive ion etching are suitable for etching the phosphor thin film.

Problems to be Solved by the Invention A multicolor thin film EL device is required to realize a uniform light emitting state as a display device. However, with the physical etching method described above, uniformity of etching depth can be ensured to some extent when using a small substrate, but it is extremely difficult to ensure uniformity of etching depth when the substrate becomes large. . Furthermore, if you try to ensure uniformity only by using etching conditions such as gas pressure, you will not be able to use the optimum etching conditions that maximize the etching speed, which will lengthen the etching time and cause severe deterioration of the resist. Cyst removal may be extremely difficult. If the uniformity of the etching depth is not ensured, other phosphor thin films underlying the etched area (gap area) will be etched (over-etched).1. or leave some unetched parts. Therefore, etching can be performed at sufficient speed and with good reproducibility.
Moreover, it was extremely difficult to realize uniform multicolor light emission.

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

Means for Solving the Problems The present invention provides that when two or more types of phosphor thin films are formed into a predetermined pattern, an insulating layer is used as an etching-resistant layer, each having an etching rate ratio of 1/2 or less relative to the phosphor thin film. After forming the phosphor thin film on the entire surface, the process of forming the phosphor thin film into a predetermined pattern by dry etching is repeated to form a recording/emitting layer on -.

According to the method of the present invention, the etching rate of the phosphor thin film under dry etching by the gas used for etching the phosphor thin film is 1/2 or less of the etching rate of the phosphor thin film by the etching gas. Since an insulating layer is formed, the etching of the phosphor gap stops progressing or becomes extremely slow when the phosphor thin film is completely etched. Therefore, it is possible to use the etching conditions that give the fastest etching rate of the phosphor thin film, and by taking a time long enough to fully etch the phosphor thin film, the phosphor thin film can be etched at high speed and on the entire surface. Etched evenly over the area.

Example The present invention will be explained in detail below.

FIG. 1 is a schematic structural diagram of a dry etching apparatus used in a method for manufacturing a multicolor thin film EL device according to embodiments of the present invention. Inside the vacuum container 1, there are an electrode pair cathode 2 and an anode 3.
is located. A substrate 4 is placed on the cathode 2''. A high frequency power source 6 is connected to the cathode 2 via a matching circuit 5, and an alternating current voltage is applied thereto. In addition, a gas introduction [17a is attached to the anode 3, and a large number of fine holes 7b provided in the anode;
The structure is such that a uniform gas flow can be supplied onto the substrate 4 through the substrate 4. 18 [The gas pressure inside the empty container 1 is controlled by the vacuum exhaust system 9.

Below, the case of producing the multicolor thin film E1 and the base material using the above-mentioned apparatus will be explained in detail.

First, as shown in FIG. 2(a,
On the glass substrate 10 on which the 03 film was formed, a z, s:Tb, F film was uniformly formed over the entire surface as the first phosphor thin film J3 by co-evaporation. After heat treatment at 450°C, II-, 1, a photoresist is applied to the first phosphor thin film 13], and stripes of the first phosphor thin film 13 are applied to every two transparent electrodes 11. A resist pattern 14 is formed so that a resist pattern 14 is formed.This glass substrate 10 is placed on the cathode 2 of the above-mentioned dry etching apparatus.Vacuum vessel 1
Inside 1. After exhausting to OX 10-'Torr, a mixed gas of methanol and argon is introduced from the gas introduction lower a. Methanol and argon gas are supplied through flowmeters 8a and 8b.
Each flow rate is controlled to a desired flow rate. Further, the pressure inside the vacuum container 1 is maintained at a predetermined constant pressure by an evacuation system 9. The high frequency power supply 6 is operated to apply a predetermined AC voltage to the cathode 2 through the matching circuit 5. Plasma is generated between the electrodes by applying an alternating current voltage, and the first phosphor thin film 13 is etched. The etching rate of the first phosphor thin film 13 decreases rapidly when the etching reaches the first insulating layer 12. Therefore, by taking a sufficient amount of time, the first phosphor thin film 13 can be etched over the entire surface of the substrate. Etched evenly across.

That is, in the case of this example, S, X of Tl 03, -/
The etching speed is 1 of the etching speed of ZnS'Tb,F.
15 or less, the first insulating layer 12 also serves as an etching-resistant layer when the first phosphor thin film 13 is etched. When the etching of the first phosphor thin film 13 is completed, the operation of the high frequency power supply 6 is stopped and the glass substrate 10 is etched.
The resist pattern 14 remaining on the first phosphor thin film 131 was removed by a resist carbonization method using oxygen plasma (FIG. 2(b)).

Next, as shown in FIG. 2(e), BaT-20s is formed as an etching-resistant layer 15 on the entire surface of the first phosphor film 13 on which the pattern has been formed, and then a second phosphor thin film 16 is formed.
C, S:E was uniformly formed on the entire surface by electron beam evaporation, and heat treated at 450°C for 1 hour.

A photoresist is applied to the second phosphor thin film 160, and the first
The photoresist is patterned so that a resist pattern 17 remains at every second transparent electrode 11 in a portion where the phosphor thin film 13 is not formed. This glass substrate is placed on the anode 2 of the dry etching apparatus described above, and the second phosphor thin film 16 is etched in exactly the same manner as the first phosphor thin film 13 described above.

Here, HaTs 2 used as the etching-resistant layer 15
Since the etching speed of No. 06 using the above etching gas is less than 1/3 of the etching speed of C, S: Eu, which is the second phosphor thin film 16, the etched portion of C, S: E is There, the progress of etching is stopped. On the other hand, by continuing etching, the remaining C, S: Eu are also etched,
The second phosphor Fh1i film 16 is etched with very good uniformity. When the etching of the second phosphor thin film 16 is completed, the Rennost pattern 1 remaining on the second phosphor thin film 16 is etched in the same way as the process after etching the first phosphor thin film 13.
7 was removed by a resist carbonization method using oxygen plasma (FIG. 2(d)).

Furthermore, as shown in FIG. 2(e), B, T, and 20s were again formed as an etching-resistant layer 18 on the entire surface where the patterns of the first phosphor 13 and the second phosphor J6 were formed.
Next, the third phosphor thin film 19 was made of S, S:C.

was uniformly formed over the entire surface by electron beam evaporation, and
A heat treatment was performed at °C for 1 hour. A photoresist is applied on the third phosphor thin film 19, and a resist pattern 20 is left in the parts where the first phosphor thin film 13 and the second phosphor thin film 16 are not formed and every second transparent electrode 11. The photoresist is patterned as follows. This glass substrate was etched into the anode 2 of the dry etching device described above.
A third phosphor thin film 1 is placed on top of the phosphor thin film 1 in exactly the same manner as in the case of the first phosphor thin film 13 and the second phosphor thin film 16 described above.
Perform etching in step 9. Here, the etching-resistant layer 18
The etching rate with the etching gas described in B and 7.206 used as the third phosphor thin film 19 is as follows:
Since the etching speed is 1/3 or less compared to the etching speed of S:C, the progress of etching is stopped at the portions where S and S:C have been etched. On the other hand, by continuing etching, the remaining S, S: C,
The third phosphor thin film 19 is also etched with very good uniformity. After the etching of the third phosphor thin film 19 is completed, the resist pattern 20 remaining on the third phosphor thin film 19 is removed in the same way as the treatment after etching the first phosphor thin film 13 and the second phosphor thin film 16. It was removed by a resist carbonization method using oxygen plasma (Fig. 2 (f)
).

The multicolor thin film EL element has a second layer as shown in Fig. 2(g).
This is completed by forming an insulating layer 21 and a back electrode 22 formed in a stripe shape so as to be orthogonal to the transparent electrode 11. When this device was driven, green light was emitted when a voltage was applied only to the electrode where only the first phosphor 13 was formed, but when voltage was applied only to the electrode where only the second phosphor thin film 16 was formed. When voltage was applied, red light was emitted, and when voltage was applied only to the electrode on which only the second phosphor thin film 19 was formed, blue light was emitted. Furthermore, if any two of the three types of phosphor thin films are selected and a voltage is applied to the electrodes on which these phosphor thin films are formed, the mixed color of light will be emitted. When the voltage was applied, white light emission was obtained. The luminous efficiency of each phosphor thin film was the same as that obtained when an EL element was formed using each phosphor thin film alone.

In the following examples, the flow rates of methanol and argon were 105 ccIII and 50 SCCM, respectively, and the gas pressure during etching was 30 mTorr. The etching speed under these conditions is zflS;Tll,F is 30
nm/mln, CaS:F, and S, S:
C, are both 25 nm/mln, and sr T l
03 and BiTmaOs respectively Grim/mfns
and 8 nm/win. The selection ratio of each is 5
rTIOs/ZnS:TbJ:115, BaTaz
06/C, S:E, :l/3.1, B*Ta205/S
fS:Cm=1/3.1. However, although the selectivity is not affected by the size of the substrate as long as the etching conditions are the same, the etching speed varies depending on the size of the substrate even if the etching conditions are the same because of the loading effect.

In this example, a mixed gas of methanol and argon was used as the gas for etching the phosphor thin film containing sulfide as the main component, but the etching gas is not limited to this. A gas including a gas of a compound containing can be used. In addition, the etching-resistant layer is made of an oxide or nitride insulating material whose etching rate with respect to the gas is less than 1/2 of the etching rate of a phosphor thin film whose main component is a sulfide. Body membranes can be used, and as those satisfying this condition, sr'r+oa, BaT
-2Qa as well as Ta2O,, T l 03.5102.
Examples include 5I3N, 51on, Y2O3, and the like. Note that a halogen-based compound gas can also be used as the gas for etching the phosphor thin film whose main component is sulfide, but the halogen-based gas can also be used to etch the above-mentioned oxide and nitride insulator films. Since etching occurs at a very high rate, it is not suitable for the method of the present invention.

In addition, in this example, Z, S:Tb, FlCaS:E
We have described the case where a multicolor thin film EL element is formed using three types of phosphor thin films: 1. u, S, and S:C. The types of phosphor thin films are not limited to these. Also, 2
If a phosphor thin film of type 1 or more is to be formed.

It goes without saying that the method for manufacturing a multicolor thin film EL device of the present invention is effective.

Effects of the Invention According to the method for manufacturing a multicolor thin film EL device of the present invention, Z, l
Dry etching of phosphor thin films mainly composed of sulfides such as S, C, S, S, S, etc. can be performed at high speed and with good reproducibility."Second, It becomes possible to etch a thin phosphor film on a substrate with very high uniformity. by this,
A plurality of phosphor thin films having original luminous efficiency can be formed between a pair of electrode layers, and a multicolor thin film EL element with high reliability can be provided.

4. Explanation of Drawings Figure 1 shows a multicolor thin film E I in an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of an apparatus used for dry etching a phosphor thin film in the device manufacturing method, and is used to explain the process of manufacturing a multicolor thin film EL device in one embodiment of the present invention. FIG.

DESCRIPTION OF SYMBOLS 1... Vacuum container, 2... Cathode, 3... Anode, 4... Substrate, 5... Matching circuit, 6...
High frequency power supply, 7a... Gas inlet, 7b... Fine hole, 8a, 8b... Flow meter, 9... Vacuum iJ gas system,
10... Glass substrate, 11... Transparent electrode, 12
...first insulator layer, 13...first phosphor thin film, 14
...Resist pattern, 15...Etching resistant layer,
16... Second phosphor thin film, 17... Cyst pattern, Third phosphor thin film,... Second insulator layer,

Claims (2)

[Claims] (1) A method for manufacturing a multicolor thin film EL device having a light-emitting layer having two or more types of phosphor thin films formed on a light-transmitting substrate, and an insulator layer and an electrode layer sandwiching the light-emitting layer, in which two or more types of phosphor thin films are formed on a transparent substrate. When forming a phosphor thin film in a predetermined pattern, an insulating layer having an etching rate ratio of 1/2 or less to each phosphor thin film is formed on the entire surface as an etching-resistant layer, and then the phosphor thin film is formed. A multicolor thin film E characterized in that the light emitting layer is formed by repeating the steps of forming a film and forming a predetermined pattern by dry etching.
Method for manufacturing L element. (2) In the method for manufacturing a multicolor thin film EL element having a light emitting layer having two or more types of phosphor thin films formed on a transparent substrate, an insulator layer sandwiching the light emitting layer, and an electrode layer, When forming a phosphor thin film, which is the main component, into a predetermined pattern by reactive ion etching, a gas containing a compound containing a methyl group or an ethyl group is used as an etching gas, and at the same time, the phosphor thin film is formed into a predetermined pattern using a reactive ion etching method. As an etching-resistant layer when forming a pattern, an oxide or nitride insulating film having an etching rate ratio of 1/2 or less to each phosphor thin film is formed on the entire surface, and then the phosphor thin film is formed. 2. The method of manufacturing a multicolor thin film EL device according to claim 1, wherein the light emitting layer is formed by repeating the steps of forming a film and forming a predetermined pattern using a reactive ion etching method.