JPH06188196A - Thermal cvd device and manufacture of film el element with it - Google Patents

Abstract

PURPOSE:To perform continuous growth without substrate movement within the same reactor, vacuum release and temperature rising/falling, relating to a light emission layer and an insulation layer that constitute a film EL element, and three-layer continuous growth of an insulation layer-light emission layer- insulation layer. CONSTITUTION:Relating to a thermal CVD device provided with a reactor of double-pipe structure consisting of a reactor inner tube 4 that surrounds a growth area provided with multiple substrates and a reactor outer tube 1 that, further, surrounds the inner tube 4. the outer tube 1 is connected to the reactor with at least one solid material supply path, and to introduce material gas from the outer tube 1 into the inside of the inner tube 4, the wall of the inner tube is provided with a gap or small hole that allows flow-in/out of gas. Thus, a thermal CVD device provided with, to directly introduce a material gas different from the material gas from the outside of the reactor to inside of the inner tube, at least one material gas introduction tube 7 and an exhaust part at part of between the reactor outer tube 1 and the inner tube 4, and manufacture of a thin film EL element using the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal CVD apparatus for producing a thin film EL element by continuously growing a light emitting layer thin film and an insulating layer thin film in the same reaction furnace, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, a thin film EL element has a so-called double insulation structure in which three layers of an insulating layer, a light emitting layer and an insulating layer are laminated between electrodes, at least one of which is transparent, is excellent in stability, luminous efficiency and reliability. Therefore, an EL display having the structure is produced.

Generally, when a thin film EL device is manufactured, the optimum raw material and growth mechanism for the growth of the insulating layer and the light emitting layer are different.
Growth in which an insulating layer is formed by a VD apparatus, then the substrate is taken out and transferred to a CVD apparatus for growing a light emitting layer to form a light emitting layer, and finally returned to the CVD apparatus for growing an insulating layer to form a second insulating layer. Use the method.

For example, the inventors of the present invention used a CVD technique in which a hydrogen or inert gas transport method of ZnS and a halogen transport method of Mn as a luminescent center material or a rare earth element were combined to grow a light emitting layer. It has been found that the uniformity of the thickness of the grown thin film is excellent when the concentration diffusion flow is used (JP-A-1-2899091, JP-A-3-20829).
8). On the other hand, a thermal decomposition reaction of a metal alkoxide-based organic gas is simple for growing an insulating layer of Al ₂ O ₃ , Ta ₂ O ₅ or the like, and it is known as a growth method capable of obtaining a good quality film.

However, in recent years, in order to manufacture a thin film EL element having a uniform crystallinity and a uniform film thickness over a large area and being excellent in mass productivity, an insulating layer and a light emitting layer are continuously formed in the same apparatus. A device and a manufacturing method capable of growing are desired, and various proposals have been made.

For example, the atomic layer epitaxy method (ALE
Method), it is possible to continuously grow an insulating layer and a light emitting layer by switching the gas while the substrate is installed in the same reaction furnace (Japanese Patent Laid-Open No. 55-130896), and a thermal CVD device and a plasma CVD device are integrated. A continuous CVD furnace has been proposed in which the substrate is moved and the substrate is moved in the furnace (JP-A-3-13888).
9) Furthermore, a continuous thermal CVD apparatus has been proposed in which the substrate is not required to be moved by separating the raw material introducing pipes for the light emitting layer and the insulating layer (JP-A-4-021780).

[0007]

However, the above-described conventional growth method and continuous growth apparatus and method have the following problems.

The ALE method utilizing the monoatomic layer growth requires an extremely long time, usually 20 hours or more, for the growth. Further, in the growth method in which the thermal CVD device and the plasma CVD device are connected and integrated, a region for connection between the devices for moving the substrates in the two devices is required, and thus the device becomes large,
And productivity is reduced. Furthermore, in the method in which the reactors are the same and only the raw materials are separated for continuous growth, the optimum temperatures of the respective growth raw materials are considerably different due to the difference in the optimal growth mechanism for the insulating layer and the light emitting layer, and the complicated reaction in the same reactor Since the temperature must be set, the size of the device also increases.

Further, there is a problem in terms of growth material. For example, a metal alkoxide-based organic gas raw material is effective for growth of an insulating film, but since the molecular weight is large and the diffusion distance is short, the growth method using a concentration diffusion flow advantageous for forming a light emitting layer causes uneven film thickness. Therefore, it is not suitable for use as a material for forming an insulating film. Therefore, it was very difficult to continuously grow both the insulating layer and the light emitting layer in the same reaction furnace so that the crystallinity and the film thickness would be uniform.

In view of the above, the present invention is directed to the movement of a substrate between devices,
Optimum growth method for continuous growth of light emitting layer-insulating layer in the same reaction furnace by reducing the factors that cause productivity decline such as releasing the vacuum, moving inside the apparatus, and changing the set temperature as much as possible. C, which has excellent mass productivity and large area
The purpose is to develop a VD device.

[0011]

The present invention has made it possible to form a high-quality thin-film EL light emitting layer by a thermal CVD method by the invention previously made by the present inventors. It is based on the fact that the source gas main flow and the growth region are spatially separated as a means to improve the uniformity of the film thickness.

In a thermal CVD apparatus having a reaction of a double tube structure composed of a reaction furnace inner tube surrounding a growth region in which a plurality of substrates are installed, and a reaction furnace outer tube further surrounding the inner tube from the outside, At least one solid raw material supply path is connected to the reactor in the outer tube, and a gap or a small hole that allows gas to flow in and out is provided in the inner tube wall in order to introduce the raw material gas from the outer tube into the inner tube. In order to introduce a raw material gas different from the above-mentioned raw material gas into the inner pipe directly from the outside of the reaction furnace, at least one raw material gas introduction pipe is provided, and a part between the reaction furnace outer pipe and the inner pipe is provided. This is a thermal CVD apparatus in which an exhaust port is provided in the.

Further, in the thermal CVD apparatus, a second exhaust port for directly exhausting gas from an inner pipe different from the exhaust port is connected to the reactor inner pipe, and the second exhaust port is It is also installed so that it penetrates through the outer tube, and exhaust air is directly emitted to the outside.

Using the thermal CVD apparatus, a solid raw material supply path for growing a light emitting layer is connected to the outer tube of the reaction furnace, and based on the chemical bonding reaction of the raw material gas supplied from the supply path, the inside of the inner tube is introduced. Based on the process of growing the phosphor thin film on the substrate by the raw material diffusion flow of and the thermal decomposition reaction of the raw material gas for insulating layer growth supplied from the direct introduction tube into the inner tube, the insulating thin film is formed on the substrate. And a step of growing, and successively growing them to laminate a light emitting layer and an insulating layer to manufacture a thin film EL element.

ZnS is used as the base material for the light emitting layer growth raw material in the above-mentioned device, and an inorganic compound such as Mn is used for the light emission center material. Al or Ta alkoxides such as methoxide and ethoxide are used as the raw material for the insulating layer growth. Organic gas is used.

In actual growth, the temperature set in the growth region is set in the range of 300 to 700 ° C., and the temperature in the growth region from the organic gas introducing pipe into the inner pipe is from room temperature to 300 ° C.
, The temperature from the inorganic raw material installed in the outer tube to the growth region is in the range of 700 to 1100 ° C. to optimize the temperature distribution of the entire reaction furnace.

[0017]

In the present invention, the light emitting layer and the insulating layer can be grown by the respective optimum reaction mechanisms, and the reaction is performed in the same reaction furnace without complicated temperature setting and substrate movement. You can

That is, in the growth of the light emitting layer, since Zn and S are supplied to the growth region while maintaining a high vapor pressure, the growth utilizing the concentration diffusion flow of the source gas is excellent in film uniformity. . Therefore, in the present invention, in order to introduce the raw material gas from the outer tube into the inner tube, a gap or a small hole that allows the gas to flow in and out is provided in the inner tube wall to shield the main flow of the raw material gas in the reaction chamber. The raw material is supplied to the substrate, that is, to the growth region only by the concentration diffusion of the raw material. Therefore, conventional decompression C
In the VD method, the nonuniformity of the film thickness and the nonuniformity of the emission center concentration, which have been caused by the supply-controlled reaction, are also eliminated.

Further, in the growth of the insulating layer, the method by the thermal decomposition reaction of the metal alkoxide source gas is excellent in the uniformity of the film thickness. For this purpose, the temperature of the gas introduction region is set to the temperature of the substrate in the growth region. On the other hand, the temperature must be set to a considerably low temperature, for example, from room temperature to about 300 ° C. Therefore, in the present invention, another raw material introduction pipe is provided which is separated from the light emitting layer in distance and does not perform complicated temperature setting in the reaction furnace. Therefore, by the raw material introduction pipe,
By introducing the raw material gas directly into the reaction furnace tube and growing it, it was possible to form an insulating layer with excellent film thickness uniformity.

Further, in order to continuously grow the light emitting layer and the insulating layer, the source gas may be mixed by repeatedly supplying and discharging the source gas. This is because the raw material is not sufficiently exhausted. Therefore, a second exhaust port is provided to change the main exhaust path between the growth of the light emitting layer and the growth of the insulating layer and increase the exhaust speed. Moreover, the second exhaust port is provided so that the raw material gas for the insulating layer is not mixed into the raw material supply passage for the light emitting layer, thereby improving the gas leakage of the raw material.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, the first continuous CVD of the present invention.
A basic structure of an apparatus and a manufacturing method using the apparatus are shown. Here, the flow of gas when growing the light emitting layer is shown by a broken line in FIG. 1, and the flow of gas when growing an insulating layer is shown by a broken line in FIG. 1 and 2 are the same except that the flow of gas is shown in the figure.

In FIGS. 1 and 2, the reactor outer tube 1 has an inner diameter 3
A quartz tube having a height of 0 cm and a height of 1 m, and auxiliary tubes 2a and 2b for installing a solid material for growing a light emitting layer are attached to the upper layer. There is an inner tube 4 made of quartz so as to surround a plurality of glass substrates 3 (size 220 mm × 170 mm) installed in the growth region, and a large number of slits 5 through which gas can flow in and out are formed on the side wall of the inner tube. There is. Exhaust is performed through an exhaust port 6 attached to the lower portion between the inner tube 4 and the reactor outer tube 1, and when growing the light emitting layer, the inside of the inner tube is not only the concentration diffusion flow of the source gas but also the gas inflow and outflow. Is an area that does not exist.

In order to grow the insulating layer, an introduction pipe 7 for directly introducing the raw material gas into the inner pipe 4 is attached to the lower portion of the inner pipe. At this time, the exhaust gas passes through the slit 5 on the side wall of the inner pipe 4, and the portion flowing out between the inner pipe and the outer pipe is exhausted from the exhaust port 6. The width of the slit is appropriately in the range of 1 to 10 mm, and in this embodiment, it is set to 3 mm.

A method of manufacturing a thin film EL element using the above apparatus will be described below.

In order to grow the light emitting layer, a base material ZnS and an emission center material Mn are filled in a quartz boat and placed in high temperature raw material parts 8a and 8b, respectively, and H ₂ and HC are respectively supplied.
l gas was supplied from the gas introduction pipes 9a and 9b to grow a ZnS: Mn film on the glass substrate. Growth pressure is 0.1t
Orr and raw material temperatures were set to 950 ° C. and 800 ° C., respectively, and growth was carried out for 1 hour to obtain a light emitting layer having a film thickness of 0.8 μm.

The glass substrate (size 220 mm × 17)
(0 mm) was placed at a pitch of 10 mm, the nonuniformity of the thickness of the light emitting layer was within ± 2%. This allows
It was found that the first growth apparatus of the present invention can improve the uniformity and is suitable for increasing the area of a thin film EL panel.

FIG. 5 shows the result of measuring the relationship between the substrate temperature and the emission intensity obtained by the above growth. FIG. 5 shows that the emission luminance of the device takes a maximum value at 550 ° C., and thin film growth is possible in the range of 300 to 700 ° C. That is,
Since the growth energy is insufficient at 300 ° C or lower, Z
It is not suitable because n and S are separated as a single substance and black Zn is formed on the substrate, and the glass substrate used is softened at 700 ° C. or higher. Further, since the emission brightness is usually required to be 100 ft-L or more at 100 Hz driving, it is desirable to set the growth temperature in the range of 450 to 600 ° C. to satisfy this condition. It was also found that the uniformity of the film thickness hardly depends on the substrate temperature in the range of 300 to 700 ° C.

Since the chemical reaction of the inorganic compound is used in the growth of the light emitting layer, the lower limit of the temperature of the raw material installation portion is determined by the decomposition temperature of the compound, and the upper limit is limited by the heat resistance of the quartz reaction tube. Therefore, the temperature range of 700 to 1100 ° C is suitable.

In order to grow the insulating film, a metal alkoxide of Al (OC ₃ H ₇ ) ₃ is introduced as a source gas into a temperature-controlled constant temperature layer, and an Ar carrier gas is used as a bubbling gas to form an insulating layer gas. The Al ₂ O ₃ film was grown by being transported from the introduction tube 7 into the tube inside the reaction furnace. Raw material gas flow rate is 1
Litter / min, and the substrate temperature was set to 500 ° C. Al ₂ about 0.2 μm thick with a growth time of 20 min
An O ₃ film was obtained, and the nonuniformity of the film thickness was ± 7%. The temperature of the raw material introduction pipe for the insulating layer is preferably in the range of normal temperature to 300 ° C. because the growth principle is the thermal decomposition of organic gas.

Next, FIGS. 3 and 4 show a basic structure of a second thermal CVD apparatus of the present invention and a manufacturing method using the apparatus.

In FIGS. 3 and 4, another exhaust port 10 is provided on the upper side where the inner pipe and the outer pipe are connected to each other by laminating and joining at the upper part. 3 and 4, the device structure is the same as that of FIGS. 1 and 2 except for the exhaust port 10, and the method of manufacturing the thin film EL element is also the same as that of the first embodiment.

Since the width of the slit 5 is small or the number of the slits 5 is small, the exhaust port 10 has a sufficient exhaust speed from the exhaust port 6 in the growth of the insulating layer of the gas flow shown by the broken line in FIG. This is an effective device structure when the above cannot be obtained.
Further, in the case of growing the insulating layer, the insulating layer raw material is separated from the light emitting layer raw material by the exhaust port 10 as compared with the case of growing the light emitting layer of the gas flow shown by the broken line in FIG. The device structure is effective in reducing cross contamination due to continuous growth.

<Comparative Example> As a first comparative example, an insulating layer and a light emitting layer were grown in a device structure in which the inner tube was removed from the device structure shown in the first embodiment of the present invention.

As a second comparative example, the first embodiment of the present invention
In the device structure shown in the example of, by introducing the source gas for insulating layer growth from the outer tube as in the case of light emitting layer growth,
An insulating layer and a light emitting layer were grown.

The results of the film thickness distribution measurement of the growth according to the present invention and the growth according to the first and second comparative examples are shown in Table 1 (substrate size 220 × 170 mm).

[0036]

[Table 1]

When the inner tube is removed (first comparative example), the film thickness of the insulating layer hardly changes, but the nonuniformity of the film thickness of the light emitting layer is significantly reduced to ± 35%, and the gas flow direction is reduced. It was found that there was a distribution in.

On the other hand, when the source gas for growing the insulating layer is introduced from the outer tube as well as the light emitting layer while the inner tube is installed (second
Comparative Example), the film thickness distribution of the insulating layer from the periphery of the substrate toward the center was remarkable, and the nonuniformity of the film thickness was ± 52%.

[0039]

According to the present invention, when the light emitting layer and the insulating layer which form the EL thin film, and further the three layers of the insulating layer, the light emitting layer and the insulating layer are continuously formed, the substrate is moved and the vacuum is released in the same reaction furnace. Moreover, continuous growth is possible without raising or lowering the temperature.

Therefore, a uniform film thickness can be obtained over a large area, the production efficiency of the thin film EL element is improved, and it is effective for cost reduction and quality improvement.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the basic structure of a first double-tube structure continuous CVD apparatus of the present invention, showing a gas flow when a light emitting layer is grown.

FIG. 2 is a schematic diagram showing the basic structure of the first double-tube structure continuous CVD apparatus of the present invention, showing a gas flow when an insulating layer is grown.

FIG. 3 is a schematic view showing a basic structure of a second continuous CVD apparatus having a double tube structure of the present invention, showing a gas flow when growing a light emitting layer.

FIG. 4 is a schematic diagram showing the basic structure of the first double-tube structure continuous CVD apparatus of the present invention, showing a gas flow when an insulating layer is grown.

FIG. 5 is a graph in which the growth temperature dependence of emission brightness is measured.

[Explanation of symbols]

 1 Reactor Outer Tube 2a First Auxiliary Tube for Installing Solid Source 2b Second Auxiliary Tube for Installing Solid Source 3 Glass Substrate 4 Reactor Inner Tube 5 Slit 6 Exhaust Port 7 Insulating Layer Material Gas Introducing Tube 8a 1 high temperature raw material part 8b 2nd high temperature raw material part 9a 1st light emitting layer carrier gas introducing pipe 9b 2nd light emitting layer carrier gas introducing pipe 10 exhaust port

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Morihiro Kawarazaki 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Corporation (72) Inventor Mikihiro Noma 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Osaka Within the corporation

Claims (4)

[Claims] 1. A thermal CV having a reaction furnace having a double-tube structure composed of a reactor inner tube surrounding a growth region where a plurality of substrates are installed, and a reactor outer tube further surrounding the inner tube from the outside.
In the apparatus D, at least one solid raw material supply path is connected to the reaction furnace in the outer tube, and a gap through which gas can flow in and out of the inner tube wall for introducing the raw material gas from the outer tube into the inner tube. Alternatively, at least one raw material gas introduction pipe is provided for providing a small hole and directly introducing a raw material gas different from the above raw material gas into the inner pipe from the outside of the reaction furnace, and the outer pipe and inner pipe of the reaction furnace. The thermal CVD apparatus is characterized in that an exhaust port is provided in a part of the space. 2. The thermal CVD apparatus according to claim 1, wherein, apart from the exhaust port, a second exhaust port for directly exhausting from the inside of the inner pipe is connected to the reactor inner pipe, and the second exhaust port is provided. Is a thermal CVD apparatus that is installed so that it also penetrates the outer tube, and exhaust is directly performed to the outside. 3. The thermal CV according to claim 1 or 2.
D device is used to connect a solid material supply path for growing a light emitting layer to the outer tube of the reaction furnace,
The step of growing the phosphor thin film on the substrate by the concentration diffusion flow into the inner tube by the chemical bonding reaction of the raw material gas supplied from the supply path, and the insulation supplied from the direct introduction tube into the inner tube. A step of growing an insulating thin film on a substrate by a thermal decomposition reaction of a raw material gas for layer growth, and continuously growing them to laminate a light emitting layer and an insulating layer. . 4. An inorganic compound such as ZnS is used as a base material and Mn is used as an emission center material as a raw material for growing a light emitting layer,
4. The method of manufacturing a thin film EL element according to claim 3, wherein an alkoxide-based organic gas such as methoxide and ethoxide of Al or Ta is used as a raw material for growing the insulating layer.