JPS6054196A - Thin film el element - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an AC EL device having a double insulation structure consisting of an amorphous hydrogenated silicon carbide thin film and an amorphous hydrogenated silicon nitride thin film.

Conventionally, EL elements (EL is e
Regarding electroluminescence (abbreviation for electroluminescence), elements using amorphous silicon (J, 1.Pank
oveet al, App, 1. Phys, Le
tt, 29 (, 9) 1320 (1978)) and devices using amorphous silicon carbide (Hayashiki et al., Proceedings of the 28th Japan Society of Applied Physics, 3a-2-8 (Spring 1980)), etc. It is being

However, the former device using amorphous silicon with a small band gap does not emit visible light and is extremely unsuitable for practical use as a light emitting display device. Recently, in an attempt to overcome these drawbacks, amorphous silicon carbide with a large <n1ζ gap has been developed. It began to be seen. It is the latter that uses this, and visible EL has been reported, but its practical properties such as EL brightness and drive stability are not satisfactory, and future 4-piece, 2-layer products are desperately needed. The current situation is that In addition, electron beam evaporation Y is used as an insulating film.
Since a 2O3 thin film is used, there is an extremely high probability that the device will be exposed to the atmosphere during device fabrication, leading to instability and deterioration of physical properties of the device.

The present invention is the result of extensive research to overcome these problems.
A double insulation structure EL element using amorphous hydrogenated silicon carbide for the light emitting layer and amorphous hydrogenated silicon nitride for the insulating layer is blue-white ~
This was based on the discovery that it could be an element with excellent EL ability that exhibits orange visible EL.

The present invention is a thin-film EL device having a laminated structure of a light-emitting film and an insulator 11, in which the light-emitting member is made of a non-carbon material having a carbon content of 45 atomic % or more (carbon/carbon+silicon). The present invention provides a thin film EL device using crystalline hydrogenated silicon carbide and (1) using amorphous hydrogenated silicon nitride as the insulating film.

The main feature of the thin film EL device of the present invention is that amorphous hydrogenated silicon carbide that emits visible light is used as the light emitting layer, and amorphous hydrogenated silicon nitride is used as the insulating layer.

In other words, since all of the constituent films of the device can be fabricated by glow discharge decomposition within a cycle chamber, the device can be fabricated without being exposed to the atmosphere at all.Therefore, there is no possibility of film surface contamination due to contamination of impurities or EL performance due to deterioration of interface physical properties. It is possible to remove negative factors such as decline.

Furthermore, amorphous hydrogenated silicon nitride has favorable characteristics for EL devices as shown below.

(b) It is possible to create large-area thin films at low temperatures.

(b) Has a high resistance value.

(c) Has high voltage resistance.

(d) Large dielectric constant.

(e) Excellent moisture resistance.

Therefore, the device manufactured according to the present invention can stably exhibit strong EL in the visible region. In addition, because amorphous silicon hydrogenated nitride is used for the insulator film, the total film thickness of the device can be made thinner than when using a normal Y2O3'al film, and a reduction in the light emission voltage can also be achieved. This shows a double effect.

The carbon content of the amorphous hydrogenated silicon carbide used in the light emitting layer of the thin film EL device of the present invention is required to be 45 atomic % or more. In the case of 45 atom % end groove, no visible EL is shown and it is unsuitable. Here, the carbon content means the atomic ratio of (carbon)/(carbon+silicon). A more preferable carbon content is 70 atom % or more.

The EL brightness and emission color can be changed by appropriately adjusting the carbon content ♀. For example, in order to obtain blue-white light emission, the carbon content must be selected to be 75 atomic % or more.

It is also believed that hydrogen contained in amorphous hydrogenated silicon carbide acts particularly effectively to compensate for dangling bonds, which are the center of non-radiative transition of light emission. If there is no hydrogen, many dangling bonds remain and the EL is poor, but if there is too much hydrogen, the thermal stability decreases and is not preferred as a device.

The range of hydrogen content is 3 atomic % or more - 60 atomic % or less,
Preferably, the range is 3 atomic % or more and 50 atomic % or less.

Furthermore, by incorporating at least one of oxygen or nitrogen into the amorphous hydrogenated silicon carbide, the EL intensity can be increased and the EL
It is possible to reduce the half value rtJ of the spectrum, and it is possible to impart practically preferable characteristics. The content of oxygen or nitrogen is preferably 1 atomic % to 7 atomic % of at least one of them. If it exceeds 7 atomic %, the resistance of the light emitting layer becomes extremely high, making it unsuitable for use as an EL device. If the content is less than 0.1 atomic %, the effect of containing oxygen or nitrogen is not significant.

On the other hand, the silicon content of the amorphous hydrogenated silicon nitride as the insulating film is preferably 43 to 50 at %. Outside this range, it will not be a good insulating film for EL elements.

The thin 11u EL device of the present invention can be manufactured, for example, by the following method.

The substrate may be any material that can be heated within a temperature range of room temperature to 400' (!).For example, a semiconductor such as single crystal Si,
The material may be appropriately selected from metals such as stainless steel and aluminum, glass, ceramics, and materials whose surfaces are coated with a conductive coating such as metal or metal oxide. A preferable substrate is one in which a conductive film is provided on a substrate transparent in the visible range, such as glass.

As the conductive film, Pt, Au, AM, In703.
5n02, ITO, etc. can be used, but the more colorless and transparent the better.

After washing the plate surface clean, place it in a glow discharge decomposition device as shown in Figure 1, and use N2 or NH
An appropriate amount of silicon-containing compound such as monosilane or disilane gas is mixed with the 3 dregs, and glow discharge decomposition is performed in the amorphous gas to deposit an amorphous hydrogenated silicon nitride insulating film on the substrate. After the residual gas is completely evacuated, a hydrocarbon, e.g. CH4, C2H4, etc. and a silicon-containing compound, e.g. SiH4, Si2 H6, (ill:H3) are added.
4 Si etc. and in some cases N2 and/or 02
The above-mentioned insulating film is obtained by mixing appropriate amounts of the above and decomposing it by glow discharge.
An amorphous hydrogenated silicon carbide light-emitting layer is stacked and deposited on the wafer. Subsequently, after the remaining gas is completely exhausted, an insulating film is deposited on the light emitting layer using exactly the same method as for depositing the insulating film described above.

The gas decomposed by glow discharge can also be used after being diluted with H2 or a high purity inert gas such as Ar.

In this case, it is more suitable for the pressure of the mixed gas to be about 0.05 to 5 Torr and between 0.1 to 2 Torr.

(The plate temperature is appropriately selected from room temperature to 400'C! depending on each layer, but preferably from 80 to 400'C!).

After each layer has been deposited, it is taken out of the system and quickly set in a vacuum evaporator, and an EL element (FIG. 2) can be fabricated by evaporating, for example, pattern A as a back electrode.

The EL element of the present invention can be used as flat display televisions for terminals, level meter displays for audio equipment, digital displays for home appliances, signal displays, image display materials, and the like.

Next, the present invention will be explained in detail with reference to examples, but the present invention is not limited thereto.

In addition, C, Si of the deposited film in the following Examples and Comparative Examples
, 0, and N were analyzed by Auger electron spectroscopy.

Example 1 Using SiH4 diluted to 10% with hydrogen and pure N2 gas, the mixing ratio was adjusted so that the silicon content (Si/Si -N) was 46 at%, and the mixture was placed in the apparatus shown in Figure 1. After glow discharge decomposition, amorphous hydrogenated silicon nitride (hereinafter abbreviated as a-3iN) was deposited at a thickness of about 100 A on the NESA glass which had been cleaned in advance and placed in the position shown in FIG.

The substrate temperature during the reaction was 320'C, and the system internal pressure was 0.5 Torr.
(Process A).

Next, after completely removing υ1 of the reaction gas used above from the system and resetting the substrate temperature to 150°C, the carbon content ( The mixing ratio was adjusted so that C/C+Si) was 78 atomic %, and amorphous hydrogenated silicon carbide (hereinafter abbreviated as a-3iC) was added to the a-9iN deposited in step 2 by about aoo A.
Deposited. Further, the amount of hydrogen in a-9iC determined from the IR spectrum was 46 at.%. The internal pressure of the system during the reaction was 9.
Maintained at 8 Torr (Process B).

Next, the reaction gas used for a-SiC deposition was completely exhausted and removed from the system, and the substrate temperature was reset to 320°C. Then, a-3iN was laminated using the exact same method as in Process A to form a double insulation structure. The device was fabricated. After cooling, the inside of the system was taken out and A pattern was vacuum-deposited as a back electrode to fabricate a device.

Examples 2 to 4 and Comparative Example 1 10% with hydrogen so that the carbon content takes the value shown in Table 1.
Four types of elements were fabricated in the same manner as in Example 1, except that Process B was carried out by varying the mixing ratio of SiH4 diluted to pure c2H4.

Further, the hydrogen content of each obtained a-9iC is also shown in Table 1.

Table 1 □□ τ Above Example 5 When an AC electric field of 1.5 k) Iz was applied to each element shown in Example 1 and Table 1, all except the elements in Table 1 and Comparative Example 1 exhibited stable EL in the visible range. Indicated. Table 2 shows the driving characteristics of each EL element. Note that vth is the dark value voltage of light emission.

Table 2 Comparative example 2.

Approximately 250 OA of Y2O3 was deposited by electron beam evaporation onto a clean NESA glass. Next, this substrate was carefully taken out and placed in the position shown in FIG. 1 and 2, and about 120 OA of a-3iC with a carbon content of 78 atom % was laminated in exactly the same manner as in Example 1, Process B.

After cooling the exhaust gas, carefully take out the substrate from the glow discharge device and apply Y2O3 to about 250OA by electron beam evaporation again.
Further layers were added.

Thereafter, a layer A was vacuum-deposited as a back electrode to produce a device.

Example 6 In Example 1 and Comparative Example 2, 1.5kHz was applied to the elements (j, J).
FIG. 3 shows the voltage-EL variation characteristics when an alternating current electric field is applied.

When a-3iN is used for insulation, vth is about 1/2 compared to Y2O3. The EL brightness was approximately three times higher, showing excellent characteristics.

Example 7.8 Example 1, Process B using 10% diluted SiH4 and pure C2H4 was carried out except that it was changed to using 10% diluted SiH, pure C2H0 and pure N2 or 02. Using exactly the same method as in Example 1, a-3 of the composition shown in Table 3 was prepared.
A device having an iC layer was obtained.

Table 3 When an AC electric field of 1.5 kHz was applied to each element shown in Table 3, vth = 10 for the element of Example 7 containing nitrogen.
5V, vth=110V for the device of Example 8 containing oxygen.
Both exhibited stable bluish-white EL.

Moreover, compared to the device of Example 1 which does not contain nitrogen or oxygen, the EL density of Examples 7 and 8 was about 1.5 times smaller, and the half-value I11 was 15 to 30 nm smaller, showing a clear doping effect.

[Brief explanation of drawings]

Fig. 1 is a manufacturing apparatus for a thin film EL device of the present invention, Fig. 2 is a cross-sectional view of a thin film EL device, and Fig. 3 is a thin 11QE obtained by the present invention.
It is a figure which shows the relationship between the applied voltage of an L element, and EL brightness. 1... Reaction container, 2... Substrate susceptor and electrode, 3
... Gas outlet and electrode, 4... Waste inlet, 5...
・Gas exhaust port, 6... Heater for heating the substrate, 7...
Thermocouple, 8...Crow, 9...5n02.10・=
a-SiN, 1l-a-3iN, 12-a-5
iC113...AM main electrode 14...AC power supply □Applicant Asahi Kasei Corporation Agent Yutaka 1) Piece H1 Figure 1 Figure 3 E11 Applied voltage (■)

Claims (3)

[Claims] (1) Thin film E having a laminated structure of a light emitter film and an insulator film
L element, which contains 45 atomic % as a bipedal light emitter 11.
It is characterized by using amorphous hydrogenated silicon carbide having the above carbon-containing gradient (carbon/iK + silicon) and using amorphous hydrogenated silicon nitride as the bipedal insulator film. A thin film EL device with (2) The thin 11-layer EL device according to claim 1, wherein the amorphous hydrogenated silicon carbide contains at least one of oxygen and nitrogen in an amount of 1 atomic % to 7 atomic %. (3) silicon-containing insulator H of 43 to 50 atomic %,
1J1-(silicon/silicon dinitrogen).