JPH0883684A - Manufacture of electroluminescence thin film and manufacturing device therefor - Google Patents

Abstract

PURPOSE: To reduce the intensity of electric field for starting light emission by performing thermal treatment in gas atmosphere containing carrier gas composed of at least one of hydrogen gas, a VIb group hydrogen compound and inert gas as well as the simple substance gas of a decomposed VIb group. CONSTITUTION: A glass substrate, after layers up to a luminous layer is formed thereon, is immediately placed on a substrate holder in a thermal treatment chamber 11. After the chamber 11 is evacuated and gas is discharged therefrom at temperature lower than thermal treatment temperature, carrier gas is introduced to the chamber 11 for raising the temperature thereof. Then, a valve is selected to allow the carrier gas to pass a bubbler 19 before a temperature rise to target thermal treatment temperature. In this case, a decomposing heater 12 is heated up to the target thermal treatment temperature. An EL substrate 10, after heated up to the target thermal treatment temperature, is held at that temperature level over the preset time and, then, the carrier gas is changed to hydrogen gas or hydrogen sulfide unable to pass the bubbler 19. After the exchange of gas, the substrate 10 is kept at a constant temperature level and, then, this temperature level is lowered to room temperature. At this process, low luminous voltage and high brightness characteristics can be provided by specifying the carrier gas.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to IIa-VIb group or
The present invention relates to a method and an apparatus for manufacturing an electroluminescent thin film using a IIb-VIb group compound semiconductor as a base material.

[0002]

2. Description of the Related Art Electroluminescent (hereinafter abbreviated as EL) elements for displays have achieved high brightness and long life by applying a double insulating layer structure, and have been put to practical use as lightweight and thin display devices. . A sectional view of the double insulating layer structure EL element is shown in FIG. A transparent electrode layer 2, a first insulating layer 3, an EL light emitting layer 4, a second insulating layer 5, and a back electrode layer 6 are sequentially laminated on the glass substrate 1.

The transparent electrode layer 2 is, for example, a vapor-deposited or sputtered thin film of indium tin oxide (ITO). For the first insulating layer 3 and the second insulating layer 5, thin films of silicon dioxide, silicon nitride and other metal oxides are used. Usually, the insulating layers are symmetrically arranged with the EL light emitting layer 4 sandwiched therebetween, because they are driven and emitted by an AC voltage applied between the transparent electrode layer 2 and the back electrode layer 6. The second insulating layer 5 completely covers the side surface of the EL light emitting layer 4, the conductive carrier in the EL light emitting layer 4 is not supplied from the outside, and the brightness characteristics are stable. Shield from outside air, EL
A long service life is achieved because the deterioration of the device is prevented.

The back electrode layer 6 is a vapor-deposited or sputtered thin film of metal such as aluminum. Each electrode layer is often patterned according to the purpose of display. EL light emitting layer 4
Is a IIa-VIb group or IIb-VIb group compound semiconductor as a base material, a rare earth element is added in the case of a IIa-VIb group compound semiconductor as an emission center, and a IIb-VIb group compound semiconductor is a base material. Manganese (Mn) is often added.

An AC voltage is applied to the transparent electrode layer 2 and the back electrode layer 6 to raise the voltage, and the electric field of the EL light emitting layer 4 is increased to about 10 ^6.
Light emission starts when the light emission starting electric field of V / cm is reached, and the light emission luminance is saturated at an electric field slightly higher than that. The conditions for the EL light emitting layer are that the light emission starting electric field is low and the brightness is high. It is known that EL light emission occurs by the following mechanism. Electrons emitted from the trap position existing at the boundary with the insulating layer due to an electric field higher than the light emission starting electric field are accelerated by the electric field in the EL light emitting layer to become hot electrons,
It collides with the added luminescence center. After the electrons at the luminescence center are excited by this collision, EL light emission occurs when returning to the original tilted position. This is because the EL light emitting layer base material is ZnS (II
b-VIb group compound semiconductor), and the added emission center is Mn.

Another mechanism is recombination emission of electrons ionized from the emission center hit by hot electrons with holes, and the base material is a IIa-VIb group compound semiconductor,
This is the case where the added luminescence center is a rare earth element. Typical example is Sr
S: Ce. In any case, in order for electric field excitation to be performed efficiently, it is necessary to obtain as high energy as possible from the electric field without causing hot electrons to collide with defects other than the emission center. This can be achieved by the fact that there are few defects other than the emission center and the conduction electron source in the host crystal.

The EL light emitting layer 4 has a thickness of about 0.5 μm IIa-
A thin film of a VIb group or IIb-VIb group compound semiconductor,
Although there are several kinds of film forming methods, the electron beam vapor deposition method and the sputtering method are mainly used at the manufacturing level because it is easy to add impurities and to form a large area film. Since the gas pressure of the VIb group element is higher than that of the group II element, in any of the film formation methods, measures are taken to prevent the dissociation of the VIb group element, but the defects due to the VIb group element deficiency should be completely eliminated. Is impossible. Immediately after the film formation, the EL emission layer is composed of Group II element and VI.
Not only defects of stoichiometric difference with group elements (insufficient VIb group elements) but also crystal grains of the amorphous layer and fine crystals generated from the amorphous layer due to film formation on materials with different crystal types I also have a world. Therefore, the light emission starting electric field is high and the light emission luminance is low. Since the amorphous layer does not emit EL light, it is called dead layer. In addition to this, oxygen taken into the light emitting layer during the film formation by the above method acts as a trap for electrons and deteriorates the light emitting property.

In order to solve the problems of high light emission starting electric field and low light emission luminance after film formation, attempts have been made to improve the film formation method and heat treat the EL light emitting layer immediately after film formation to improve the crystallinity. ing. The heat treatment of the EL light emitting layer in a vacuum or in an inert gas atmosphere does not improve the crystallinity due to the generation of vacancies due to the dissociation of the Group VI element from the compound semiconductor base material. In order to prevent the dissociation of the VIb group element during the heat treatment, the heat treatment atmosphere and the treatment conditions are set to 700 ° C. in a sulfur gas or an inert gas containing sulfur gas or hydrogen sulfide, as proposed in JP-A 1-272093. 5h, or JP-A-4-121
As proposed in 995, it has been attempted to set the temperature at 650 ° C. for 4 hours in a sulfide gas. However, in the latter case,
The target is an EL light emitting layer to which an additive other than the luminescent center is added.

[0009]

However, in such a heat treatment method, since the sulfur gas concentration is low not only when sulfur gas is not added but also when sulfur gas is added, the oxygen in the EL thin film is reduced. Are not sufficiently removed and the crystallinity is not improved, the substrate temperature for the heat treatment is high, the heat treatment time is long, and the substrate may be deformed or the transparent electrode may be deteriorated. Further, since a stable control method of sulfur gas has not been established, the effect of heat treatment is not always sufficient, and high brightness cannot be obtained or the life of brightness may be short.

An object of the present invention is to provide a manufacturing method and a manufacturing apparatus which can eliminate the above-mentioned drawbacks and can keep the effect of heat treatment constant.

[0011]

According to the first invention, II
In a method of manufacturing an electroluminescent thin film, wherein a thin film containing a-VIb group or IIb-VIb group compound semiconductor is heat-treated in a gas atmosphere, the heat treatment includes two consecutive steps, the first step is the above in a gas atmosphere. This is a process to keep the thin film at a constant temperature, and the atmospheric gas in the first step was decomposed at a given temperature into a carrier gas consisting of at least one of inert gas, hydrogen gas or group VIb hydrogen compound gas. The second step is to contain the VIb group element gas, the second step is a step of keeping the thin film at a constant temperature in a gas atmosphere and then lowering the temperature, and the atmosphere gas of the second step is hydrogen gas or a VIb group hydrogen compound. It shall consist of at least one of the gases.

According to a second invention, in the manufacturing method according to the first invention, the VIb group element gas is a carrier gas.
It shall be contained in the carrier gas by bubbling into the VIb group element melt. According to a third invention, in the manufacturing method according to the first invention, the decomposed VIb group element gas in the first step is sulfur and the VIb group hydrogen compound is hydrogen sulfide.

According to the fourth invention, in the manufacturing method according to the third invention, when the carrier gas in the first step is an inert gas, the decomposition temperature of sulfur is 600 ° C. or more and 1200 ° C. or less. Shall be According to the fifth invention, in the manufacturing method according to the third invention, when the carrier gas in the first step is hydrogen gas or VIb group hydrogen compound gas, the decomposition temperature of sulfur is 200 ° C. or more and 1200 ° C. or more. It shall be below ℃.

According to the sixth invention, in the manufacturing method according to the third invention, it is assumed that the total pressure of the atmospheric gas is 0.7 atm or more and 2 atm or less. According to the seventh invention,
The method for producing an electroluminescent thin film according to the third aspect, wherein the molar ratio of the sulfur gas to the carrier gas is 0.1 or more and 1.0 or less in terms of S ₈ molecules.

According to the eighth invention, in the manufacturing method according to the third invention, when the IIa-VIb group compound semiconductor is strontium sulfide, the constant holding temperature of the first step and the second step is maintained. Is 550 ° C. or higher and 800 ° C. or lower. According to a ninth invention, in the manufacturing method according to the third invention, when the IIb-VIb group compound semiconductor is zinc sulfide, the first step and the second step
It is assumed that the constant holding temperature in the above step is 400 ° C or more and 600 ° C or less.

According to the tenth aspect of the invention, the electroluminescent thin film manufacturing apparatus is a hermetic container having a gas inlet, a gas outlet, a substrate holder, and a substrate loading / unloading lid.
A gas supply device that supplies multiple types of carrier gas to the bubbler independently by opening and closing valves, and after bubbling these carrier gases into the VIb group element melt, the carrier gas containing the VIb group element gas is used as the above gas. A bubbler leading to the inlet and a heating device for decomposing the VIb group element gas contained in the carrier at a predetermined temperature are provided.

[0017]

As described above, the manufacturing method of the present invention includes two steps. In the heat treatment of the first step, II
A thin film containing a-VIb group or IIb-VIb group compound semiconductor is used as a carrier gas consisting of at least one gas of hydrogen gas, a VIb group hydrogen compound gas or an inert gas, and a VIb group element gas whose partial pressure can be controlled by decomposition. By performing heat treatment in a gas containing and, the partial pressure of the VIb group element gas can be made higher than that in an atmosphere containing no decomposed VIb group element gas, so that it has the effect of filling the pores of the VIb group element. Not only does it work strongly, but oxygen is also replaced by Group VIb elements.

By increasing the decomposition temperature, the VIb group element gas contains a large amount of diatomic molecules having a size smaller than that of polyatomic molecules of 4 atoms or more, so that it enters deeply into the light emitting layer in a short time and causes a reaction. Cheap. In the heat treatment of the second step following the heat treatment of the first step,
Since the constant temperature is maintained and the temperature is lowered to take out the substrate in the atmosphere which does not contain the VIb group element gas excessively,
The thin film of the VIb group element which is generated by the temperature lowering in the atmospheric gas in the step is not formed.

By bubbling the carrier gas into the melt of the VIb group element, the carrier gas is filled with an amount of VIb group element gas molecules corresponding to the saturated gas pressure at the temperature of the melt. In the electroluminescence thin film manufacturing equipment, the hydrogen compound gas of the VIb group element, the hydrogen gas or the inert gas is independently supplied by the valve, and these gases are bubbled in the VIb group element melt to generate the VIb group element gas. Filling the carrier gas, controlling and heating the VIb group element gas to a desired temperature with a heater to decompose it, and flowing the decomposed VIb group element gas onto the light emitting layer on the substrate simultaneously and continuously. It can be carried out.

[0020]

EXAMPLES The electroluminescent thin film used in the examples of the heat treatment in the atmosphere of the present invention was formed in the following steps. On a glass substrate having a thickness of 1 μm, a transparent electrode of indium-tin oxide (ITO) having a thickness of 0.2 μm, a first insulating layer of silicon nitride oxide having a thickness of 0.3 μm, a light emitting layer described below, The first insulating layer is a second insulating layer of silicon nitride oxide with the same thickness of 0.3 μm, and the final thickness is 0.5 μm.
The back electrode layers of aluminum of m 2 were laminated in this order. After stacking up to the light emitting layer, heat treatment in an atmosphere according to the present invention described later was performed to improve the light emitting characteristics. The film formation after the heat treatment was performed in order to evaluate the degree of improvement in the light emission characteristics.

In this embodiment, strontium sulfide (SrS) and zinc sulfide (Z
nS) was used. In the case of SrS, cerium chloride (CeCl ₃ ) was added as an emission center impurity. In the case of ZnS, manganese (Mn) was added as an emission center impurity. The light emitting layer is formed by a resistance heating vapor deposition method, an electron beam (EB) vapor deposition method, a reactive sputtering method, or a MOC.
Although there are various methods such as the VD method, in this embodiment, the EB vapor deposition method is used because it is easy to control the amount of added impurities. When the EL thin film is strontium sulfide, the evaporation source is CeCl ₃ of 0.1 to 0.1.
A pellet of SrS added with 0.5 mol% was used. E
When the L thin film is zinc sulfide, the evaporation source has Mn of 0.1 to 0.
A pellet of ZnS added with 5 mol% was used. In either case, the film formation rate was 0.04 μm / min and the film thickness was 0.8.
Film was formed up to μm.

Next, a schematic sectional view of the heat treatment apparatus of the present invention is shown in FIG. The chamber 11 for heat treatment is made of quartz,
The entire chamber is heated by the chamber heater 12 so that the decomposed VIb element gas is not condensed on the chamber wall surface at the same time when the EL substrate 10 on the stage (not shown) is heated. The chamber 11 is provided with a nozzle 13 for introducing a heat treatment atmosphere gas and an exhaust valve for controlling the exhaust speed. A decomposition heater 14 is wound around the opening of the nozzle 13 to heat and decompose the VIb element gas carried by the carrier gas. Due to the shape of the opening of the nozzle 13, the gas flowing out from the nozzle 13 flows in parallel on the surface of the EL substrate 10.

High-purity argon, hydrogen, and hydrogen sulfide carrier gases are independently supplied to the respective carrier gas cylinders 1.
The flow rate is controlled by the mass flow meter 18 from 5 to 17, and the molten VIb element melt 21 in the bubbler 19 heated to a predetermined temperature is bubbled to convey the VIb element gas and to convey the heat in the heat treatment chamber 11. Sent to the nozzle 13. The VIb element gas is further heated at the opening of the nozzle 13 and decomposed into a diatomic molecular gas, a tetraatomic molecular gas, etc., and flows into the exhaust hole while reacting with the EL light emitting layer on the EL substrate 10. The pipes 22 before and after the bubbler 19 are also heated to the same temperature as the bubbler 19 by the pipe heater 23.

The heat treatment of this invention is performed as follows. The glass substrate on which the light emitting layer has been formed is immediately placed on a substrate holder (not shown in FIG. 1) in the heat treatment apparatus immediately after the film formation. After the heat treatment chamber 11 is evacuated and gas is discharged at a temperature lower than the heat treatment temperature, a carrier gas described in the following examples is introduced and the temperature is raised. The valve is switched so that the carrier gas passes through the bubbler 19 immediately before the target heat treatment temperature is reached,
The decomposition heater 12 has already been heated to the target temperature.
After the EL substrate 10 reaches the target heat treatment temperature and is maintained at that temperature for a predetermined time, the carrier gas is switched to hydrogen gas or hydrogen sulfide gas that does not pass through the bubbler 19. Of the steps up to this point, the constant temperature holding section of the EL substrate 10 is referred to as a first step.

After the gas exchange, the EL substrate 10 is kept at a constant temperature and then the temperature is lowered to room temperature. This is the second step. In order to evaluate the brightness characteristics, the back electrode must be laminated. After the heat treatment was completed, the EL substrate 10 was taken out, and the second insulating layer and the back electrode were immediately formed so as to prevent oxidation or contamination in the atmosphere.

The brightness characteristic is 5 kHz for the transparent electrode and the back electrode.
The AC voltage was applied to measure the luminance with respect to the applied voltage. Example 1 A substrate in which strontium sulfide was laminated as described above was subjected to heat treatment using a mixed gas of argon and sulfur as an atmosphere gas in the first step, and the effect of decomposing sulfur gas was examined. The flow rate of argon was 5 sccm and the molar ratio of sulfur was kept constant at 0.3. The temperature of the piping was kept constant at 200 ° C. The decomposition temperature was varied from 200 to 1200 ° C. Substrate temperature is 60
The total pressure in the heat treatment chamber was 0 ° C. and 1 atmosphere. First
The constant temperature holding time of the step was 0.5 h. The atmosphere gas in the second step was hydrogen sulfide gas, the constant temperature holding time was 0.5 h, and the temperature lowering time to room temperature was 1 h.

The reason why the second step is required will be described below. If the atmosphere gas in the second step is the same as that in the first step, an extremely thin film of sulfur alone may be formed on the EL thin film surface. Since this ultra-thin film is an insulator, it is possible to stack the second insulating layer and the back electrode on the ultra-thin film and measure the EL characteristics. Therefore, it is possible to evaluate the effect of the heat treatment in the first step. However, it has been found that this ultra-thin film has a problem in adhesion and peeling of the second insulating layer occurs during the peeling back electrode patterning step of the second insulating layer or after various thermal tests.

A luminance-voltage characteristic diagram corresponding to the decomposition temperature of sulfur is shown in FIG. In the figure, the EL thin film name, the atmosphere gas name of the first step, the corresponding decomposition temperature is added to each curve, and the characteristic curve when no heat treatment is performed is also added for comparison. Decomposition temperature is 800 to 1200
Low emission voltage and high brightness could be achieved at 60 ℃, but 60
None were sufficient below 0 ° C. Example 2 The first step was the same as that in Example 1, only the atmosphere gas in the second step was changed to hydrogen gas, and the other conditions were the same as in Example 1. The degree of removal of the ultrathin film of sulfur and the brightness characteristics were the same as the results of Example 1. Example 3 A substrate in which strontium sulfide was laminated as described above was subjected to heat treatment using a mixed gas of argon and sulfur as an atmosphere gas in the first step, and an appropriate range of substrate temperature was obtained. The flow rate of argon was 5 sccm and the molar ratio of sulfur was kept constant at 0.3. The temperature of the pipe was 200 ° C. and the decomposition temperature was 800 ° C. The substrate temperature was changed from 200 to 650 ° C. The total pressure was 1 atm. The constant temperature holding time in the first step was 0.5 h. The second step was the same as in Example 1.

A luminance-voltage characteristic diagram corresponding to the substrate temperature is shown in FIG. Corresponding substrate temperatures are added to the respective curves in the figure, and characteristic curves when no heat treatment is performed are also added for comparison. A low emission voltage and high brightness could be achieved at a substrate temperature of 550 ° C. or higher, but neither was sufficient at a substrate temperature of 500 ° C. or lower. Example 4 A substrate in which strontium sulfide was laminated as described above was subjected to heat treatment using a mixed gas of argon and sulfur as an atmosphere gas in the first step, and the effect of the molar ratio of sulfur gas to argon was examined. The flow rate of argon was 5 sccm and the molar ratio of sulfur was 0. It was changed from 1 to 0.4. The molar ratio was controlled by changing the bubbler temperature. Pipe temperature is 200
The decomposition temperature was kept constant at 800 ° C. Substrate temperature is 6
The pressure was 00 ° C. and the total pressure was 1 atm. The constant temperature holding time in the first step was 0.5 h. The second step is the first embodiment
Same as

FIG. 4 shows a luminance-voltage characteristic diagram corresponding to the molar ratio of sulfur gas. Corresponding molar ratios are added to the respective curves in the figure, and characteristic curves when no heat treatment is performed are also added for comparison. A low emission voltage and high brightness could be achieved for the molar ratios of 0.1 to 0.4, but neither was sufficient for the molar ratios of 0 and 0.5. Example 5 On a substrate laminated with strontium sulfide as described above,
The heat treatment was performed using a mixed gas of argon and sulfur as the atmosphere gas in the first step, and the effect of the total pressure of the atmosphere gas was investigated. The flow rate of argon is 5 sccm and the molar ratio of sulfur is 0.3.
And Pipe temperature is 200 ℃, decomposition temperature is 800
The substrate temperature was 600 ° C. The total pressure was varied from 0.5 to 1.0 atmosphere. The constant temperature holding time in the first step was 0.5 h. The second step was the same as in Example 1.

FIG. 5 shows a luminance-voltage characteristic diagram corresponding to the total pressure of the atmospheric gas. The corresponding total pressures are added to the curves in the figure, and the characteristic curves when heat treatment is not performed are also added for comparison. At a total pressure of 0.7 atm or more, a low emission voltage and high brightness could be achieved, but at 0.5 atm or less, neither was sufficient. Example 6 On a substrate in which strontium sulfide was laminated as described above,
Heat treatment was performed in the first step using the atmosphere gas as a mixed gas of hydrogen sulfide gas and sulfur gas. Decomposition temperature of sulfur is 2
The effect of the heat treatment was greater at 00 ° C than when hydrogen sulfide gas alone was used, and it was the same even when the decomposition temperature was 800 ° C. Atmospheric gas pressure is 760 Torr, substrate temperature is 600
° C, the molar ratio of sulfur gas to carrier gas is 0.2,
The constant temperature holding time in the first step was 0.5 h. The second step was the same as in Example 1.

Even when the molar ratio of the sulfur gas to the carrier gas was changed, the effect of the heat treatment did not change when the molar ratio of sulfur was 0.1 to 0.4. FIG. 6 shows a luminance-voltage characteristic diagram corresponding to the decomposition temperature of sulfur. Corresponding decomposition temperatures are added to the respective curves in the figure, and characteristic curves for the case where heat treatment is not performed and the case where sulfur gas is not added are also added for comparison. Example 7 On a substrate laminated with strontium sulfide as described above,
The heat treatment was performed using the atmosphere gas in the first step as a mixed gas of hydrogen gas and sulfur gas. Decomposition temperature of sulfur is 200
The effect of the heat treatment was already greater at a temperature of ℃ than when hydrogen sulfide gas alone was used, and it was the same even when the decomposition temperature was 800 ℃. Therefore, the effect of heat treatment was examined by setting the decomposition temperature to 200 ° C. and setting the molar ratio of sulfur gas to carrier gas to 0.2 to 0.8. The atmospheric gas pressure is 760 Torr, the substrate temperature is 600 ° C., and the constant temperature holding time in the first step is 0.5.
It was set to h. The second step was the same as in Example 1 except that the atmosphere gas was hydrogen.

FIG. 7 shows a luminance-voltage characteristic diagram corresponding to the molar ratio of sulfur gas. Corresponding molar ratios are added to the respective curves in the figure, and characteristic curves when heat treatment is not performed are also added for comparison. For a molar ratio of 0.2 or more,
It can be seen that the light emission starting voltage and the brightness are saturated. Example 8 A substrate laminated with zinc sulfide as described above was subjected to heat treatment using a mixed gas of argon and sulfur gas as an atmosphere gas, and the effect of decomposing sulfur gas was examined. Decomposition temperature is 200-8
The substrate temperature was 00 ° C and the substrate temperature was 450 ° C. The other conditions were the same as in Example 1.

A luminance-voltage characteristic diagram corresponding to the decomposition temperature of sulfur is shown in FIG. Corresponding decomposition temperatures are added to the respective curves in the figure, and characteristic curves when the heat treatment is not performed are also added for comparison. When the decomposition temperature was 600 ° C. or higher, good luminance characteristics could be obtained. Example 9 A substrate laminated with zinc sulfide as described above was subjected to a heat treatment using a mixed gas of argon and sulfur as an atmosphere gas, and the effect of the substrate temperature of sulfur gas was examined. The decomposition temperature was 800 ° C, and the substrate temperature was 200 to 600 ° C. The other conditions were the same as in Example 1.

When the substrate temperature was 400 ° C. or higher, good luminance characteristics could be obtained. Example 10 A substrate in which zinc sulfide was laminated as described above was subjected to heat treatment using an atmosphere gas as a mixed gas of hydrogen sulfide gas and sulfur gas, and the effect of the substrate temperature of sulfur gas was examined. Substrate temperature is 20
The conditions were 0 to 600 ° C., and the other conditions were the same as in Example 6. Under the same conditions as in the case of strontium sulfide, a low emission starting voltage and high brightness were obtained. Example 11 When the heat treatment was performed in the second step of Example 9 using hydrogen gas as the atmosphere gas, and the effect of the heat treatment was examined, the same results as in Example 9 were obtained.

[0036]

According to the present invention, the group IIa-VIb or
A thin film containing a IIb-VIb group compound semiconductor is formed by hydrogen gas, VI
An atmosphere containing no decomposed VIb group element gas because the heat treatment is carried out in a gas atmosphere containing a carrier gas consisting of at least one of a group b hydrogen compound or an inert gas and a decomposed VIb group simple substance gas. Compared with the above, since the partial pressure of the VIb group element gas could be increased, the reduction of VIb group vacancy defects in the light emitting layer can be achieved in a shorter time and the light emission initiation electric field can be reduced.

Further, by increasing the partial pressure of the VIb group element gas, the reducing action of the IIa and IIb group elements in the EL light emitting layer on the oxide is increased, the defects relating to oxygen are reduced, and the light emission starting electric field is reduced. You can Further, since the supply of the VIb group element gas is performed by bubbling the carrier gas into the VIb group element melt, the stable melt temperature control keeps the VIb group element gas concentration in the heat treatment atmosphere stable. Therefore, the effect of heat treatment can be stably obtained.

The lower limit of the heat treatment temperature is 550 ° C. for the SrS electroluminescent thin film and the lower limit of the heat treatment temperature is 400 ° C. for the ZnS electroluminescent thin film, so that the heat treatment effect can be obtained. According to the invention relating to the production apparatus, an apparatus for independently supplying a hydrogen compound gas or H ₂ gas of a VIb group element or an inert gas, a bubbler for bubbling these gases into a melt of a VIb group element, and a VIb group element gas are decomposed. Since the electroluminescence thin film manufacturing apparatus equipped with the device for controlling the heat treatment atmosphere, the pressure of the heat treatment atmosphere gas, the molar ratio of the VIb group element gas to the carrier gas, the heat treatment temperature, etc. can be independently and stably controlled, and as a result, stable As a result, a light emitting layer with high brightness can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a heat treatment apparatus of the present invention.

FIG. 2 is a luminance-voltage characteristic diagram corresponding to the decomposition temperature of sulfur.

FIG. 3 is a luminance-voltage characteristic diagram corresponding to the substrate temperature.

FIG. 4 is a luminance-voltage characteristic diagram corresponding to the molar ratio of sulfur gas.

FIG. 5: Luminance-voltage characteristic diagram corresponding to total pressure

FIG. 6 is a luminance-voltage characteristic diagram corresponding to the decomposition temperature of sulfur.

FIG. 7 is a luminance-voltage characteristic diagram corresponding to the molar ratio of sulfur gas.

FIG. 8 is a luminance-voltage characteristic diagram corresponding to the decomposition temperature of sulfur.

FIG. 9 is a sectional view of an electroluminescent device having a double insulating layer structure.

[Explanation of symbols]

 1 Glass Substrate 2 Transparent Electrode 3 First Insulating Layer 4 EL Light Emitting Layer 5 First Insulating Layer 6 Back Electrode 10 EL Substrate 11 Heat Treatment Chamber 12 Chamber Heating Heater 13 Nozzle 14 Decomposition Heater 15 Hydrogen Cylinder 16 Inert Gas Cylinder 17 VIb Group hydrogen compound cylinder 18 Mass flow meter 19 Bubbler 20 Bubbler heater 21 VIb Group element melt 22 Piping 23 Piping heater

Claims (10)

[Claims] 1. A method of manufacturing an electroluminescent thin film, wherein a thin film containing a IIa-VIb group or IIb-VIb group compound semiconductor is heat-treated in a gas atmosphere, the heat-treatment comprises two consecutive steps, the first step comprising: This is a process of maintaining the thin film at a constant temperature in a gas atmosphere, and the atmosphere gas in the first step is a predetermined gas in a carrier gas consisting of at least one of an inert gas, hydrogen gas or a VIb group hydrogen compound gas. The second step is a step of holding the thin film at a constant temperature in a gas atmosphere and then lowering the temperature. The atmosphere gas of the second step is hydrogen gas. Or VIb
A method for producing an electroluminescent thin film, comprising at least one of a group hydrogen compound gas. 2. The method according to claim 1, wherein VIb
The method for producing an electroluminescent thin film, wherein the group element gas is contained in the carrier gas by bubbling the carrier gas into the VIb group element melt. 3. The manufacturing method according to claim 1, wherein
The method for producing an electroluminescent thin film, wherein the decomposed VIb group element gas in the step is sulfur and the VIb group hydrogen compound is hydrogen sulfide. 4. The manufacturing method according to claim 3, wherein
The method for producing an electroluminescent thin film, wherein the decomposition temperature of sulfur is 600 ° C. or more and 1200 ° C. or less when the carrier gas in the step of 1) is an inert gas. 5. The manufacturing method according to claim 3, wherein
When the carrier gas in the step is hydrogen gas or VIb group hydrogen compound gas, the decomposition temperature of sulfur is 20
A method for producing an electroluminescent thin film, which is 0 ° C. or higher and 1200 ° C. or lower. 6. The method of manufacturing an electroluminescent thin film according to claim 3, wherein the total pressure of the atmospheric gas is 0.7 atm or more and 2 atm or less. 7. The method for producing an electroluminescent thin film according to claim 3, wherein the molar ratio of sulfur gas to carrier gas is 0.1 or more and 1.0 or less in terms of S ₈ molecules. . 8. The method according to claim 3, wherein IIa
A method for producing an electroluminescent thin film, characterized in that, when the —VIb group compound semiconductor is strontium sulfide, the constant holding temperature in the first step and the second step is 550 ° C. or higher and 800 ° C. or lower. 9. The manufacturing method according to claim 3, wherein IIb
-If the group VIb compound semiconductor is zinc sulfide,
And the constant holding temperature of the second step is 40
A method for producing an electroluminescent thin film, characterized in that the temperature is 0 ° C. or higher and 600 ° C. or lower. 10. A closed container having a gas inlet, a gas outlet, a substrate holder, and a substrate loading / unloading lid, and a gas supply device for independently supplying a plurality of types of carrier gas to a bubbler by opening / closing a valve, VI these carrier gases
A bubbler for introducing a carrier gas containing a VIb group element gas into the gas inlet after bubbling through the b group element melt,
An electroluminescence thin film manufacturing apparatus comprising: a heating device that decomposes a VIb group element gas contained in a carrier at a predetermined temperature.