JPH0736024A - Production of substrate - Google Patents

Abstract

PURPOSE:To produce a light-transmissive substrate without alkali ion being diffused from the surface at a low cost. CONSTITUTION:An Al2O3 film 1b is formed on at least one surface of a soda- lime glass substrate 1a at 300-450 deg.C, preferably 350-400 deg.C, substrate temp. by the thermal decomposition of Al(i-OC3H7)3 and beat-treated at 1-760Torr for 10-60min in the atmosphere of the gaseous oxygen contg. 1-15% O3, hence the good-quality Al2O3 film 1b having 50-500nm thickness is obtained, and a light- transmissive substrate 1 without alkali ion being diffused is produced at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a substrate in which an ion barrier layer is formed on the surface of a glass substrate on which constituent members of a display element are formed.

[0002]

2. Description of the Related Art Generally, a liquid crystal display device and a thin film E have been conventionally used.
A glass substrate is used as a translucent substrate for a display element such as an L (electroluminescence) element. These display elements include constituent members formed of a semiconductor material such as Si (silicon) and ZnS (zinc sulfide) among constituent members formed on a glass substrate. Therefore, when a glass material containing a large amount of movable alkali ions, such as soda glass, is used as the glass substrate, alkali ions such as sodium ions are transferred from the glass substrate to the semiconductor by a process such as heat treatment in the manufacturing process of the display element. There is a problem that the display characteristics of the display element are deteriorated in a relatively short time because the material permeates and diffuses into the material.

Therefore, for these display elements, a non-alkali glass substrate which is realized by barium boron silicate or aluminosilicate containing no alkali ions is used. However, since non-alkali glass is much more expensive than soda glass, it causes an increase in the manufacturing cost of the display device.

Correspondingly, soda glass, which is inexpensive and has excellent smoothness, is used as the glass substrate for the display element to prevent the alkali ions from permeating and diffusing into the constituent members formed on the glass substrate. As a technology of
No. 7-28198, JP-A-61-128225 and JP-A-2-56894, a SiO ₂ film, an S ₂
It has been proposed to form an ion barrier layer realized by an i ₃ N ₄ film or the like. A SiO ₂ film having a film thickness of 100 to 200 nm is widely used as an ion barrier layer, and a sol-gel method such as a DIP method which is an inexpensive film forming method is used for a liquid crystal display element.

[0005]

However, in the manufacturing process of a liquid crystal display element and a thin film EL element using a TFT (thin film transistor), the strain point of soda glass to 5
A heat treatment of about 05 ° C. is performed. This heat treatment is
In the case of a liquid crystal display element using, the impurities implanted for forming the semiconductor thin film are electrically activated to eliminate defects generated at the time of implanting the impurities. Further, in the case of a thin film EL element, it is carried out for the purpose of improving the crystallinity of the vapor-deposited ZnS: Mn film and improving and stabilizing the luminous efficiency. Further, the structure of the thin film is densified by the heat treatment, and the adhesion between the thin film and the base substrate is improved.

FIG. 8 shows a SiO ₂ film, an Al ₂ O ₃ film and an S film.
i is a characteristic diagram showing the thermal diffusion condition of alkali ions into ₃ N ₄ film. FIG. 8A shows a state of thermal diffusion of alkali ions into the SiO ₂ film formed by the DIP method,
Similarly, FIG. 8B shows an Al ₂ film formed by a sputtering method.
FIG. 8 shows the thermal diffusion of alkali ions into the O ₃ film.
(C) shows the state of thermal diffusion of alkali ions into the Si ₃ N ₄ film formed by the sputtering method. The SiO ₂ film,
The Al ₂ O ₃ film and the Si ₃ N ₄ film are formed on a soda glass substrate to a film thickness of 150 nm, respectively, at 500 ° C.
After the heat treatment for 2 hours, the alkali ion composition in the film thickness direction of the sample from the film surface was measured by IMA (ion microprobe analyzer).

As a result, as shown in FIG.
SiO ₂ film formed by the P method, 500 ° C., after 2 hours heat treatment, sodium ions are detected until the surface layer close, as shown in FIG. 8 (b), Al by sputtering ₂
In the O ₃ film, alkali ions were detected up to almost the middle position in the film thickness direction. On the other hand, as shown in FIG.
In the Si ₃ N ₄ film formed by the sputtering method, sodium ions hardly diffuse into the Si ₃ N ₄ film, and soda glass and Si
It remains near the interface with the ₃ N ₄ film. In this way, the diffusion preventing effect of alkali ions is obtained by the sputtering method Si ₃ N ₄ film>
Sputtering method Al ₂ O ₃ film> DIP method SiO ₂ film are excellent in that order, and the alkali ion diffusion preventing effect of the DIP method SiO ₂ film is insufficient as an ion barrier layer for TFT liquid crystal display elements and thin film EL elements. found.

Si ₃ N _{4 formed} by the sputtering method
The film and the Al ₂ O ₃ film show an effective effect of preventing alkali ion diffusion as an ion barrier layer, but a glass substrate of soda glass is generally manufactured as a large-area continuous plate glass by using the float method. Therefore, the film formation by the sputtering method is inappropriate. Although a CVD method (vapor phase growth method) is effective as a film forming method on a large-area glass substrate, in order to form an Si ₃ N ₄ film on the substrate by using the CVD method, The substrate temperature must be 900 ° C. or higher. In contrast, soda glass has a strain point of about 50.
Since it is as low as 0 ° C., it is not possible to form a film using this method.

On the other hand, for the Al ₂ O ₃ film, other than the sputtering method, J.
A.Aboaf: "Deposition And Properties of Aluminum Oxid
e Obtained by Pyrolytic Deposition of anAluminum A
lkoxide ", J. Electrochem. Soc., 114, (1967) 948. The film can be formed by the thermal CVD method using an Al alkoxide. When the film thickness is low, the film thickness distribution is excellent, but undecomposed matter remains in the film and the film quality is poor.On the other hand, when the substrate temperature during film formation is high, a good quality Al ₂ O ₃ film can be obtained. At that time, the substrate temperature must be 500 ° C. or higher, and the film thickness distribution is significantly deteriorated.
The l ₂ O ₃ film has hardly been studied as an ion barrier layer.

An object of the present invention is to provide a method for producing a transparent substrate which is inexpensive and has high smoothness, and which is capable of producing a transparent substrate without alkali ion diffusion.

[0011]

According to the present invention, there is provided a step of forming an Al ₂ O ₃ film on at least one surface of a glass substrate by a vapor phase growth method using aluminum alkoxide as a raw material, and said Al ₂ O ₃ film. _The glass substrate on which ₃ films are formed,
And a step of performing a heat treatment in a mixed gas atmosphere of ozone and oxygen.

The present invention is also characterized in that the aluminum alkoxide is selected from Al (i-OC ₃ H ₇ ) ₃ .

Further, the present invention is characterized in that the substrate temperature at the time of forming the Al ₂ O ₃ film is selected in the range of 300 to 450 ° C.

Furthermore, the present invention is characterized in that the temperature of the heat treatment carried out in a mixed gas atmosphere of ozone and oxygen is selected in the range of 400 to 500 ° C.

In the present invention, the thickness of the Al ₂ O ₃ film is 5
It is characterized in that it is selected in the range of 0 to 500 nm.

[0016]

According to the invention, was formed an Al ₂ O ₃ film by a vapor deposition method using aluminum alkoxide as a raw material on at least one surface of the glass substrate, the Al ₂ O ₃
Since the glass substrate on which the film is formed is heat-treated in a mixed gas atmosphere of ozone and oxygen, a dense and pinhole-free Al ₂ O ₃ film is formed on the glass substrate. Al ₂ O ₃
Since the film is excellent in alkali ion diffusion preventive property, even if inexpensive and highly smooth soda glass is used as the glass substrate, alkali ions in the soda glass are contained in the constituent members of the element formed on the substrate. It is possible to prevent the diffusion. This makes it possible to reduce the manufacturing cost of the substrate and improve the reliability of stable operation of the element formed by forming the constituent members on the substrate.

Further, according to the present invention, since the aluminum alkoxide is selected as Al (i-OC ₃ H ₇ ) ₃ , the film forming rate of Al ₂ O _{3 formed} on the glass substrate is high and the productivity is high. Membrane treatment can be performed.

Further, according to the present invention, since the substrate temperature at the time of forming the Al ₂ O ₃ film is selected in the range of 300 to 450 ° C., Al ₂ O ₃ having a high film forming rate and a uniform film thickness is formed. Can be membrane.

Further in accordance with the present invention, said Al ₂ O ₃
Since the substrate on which the film is formed is subjected to heat treatment in the range of 400 to 500 ° C. in a mixed gas atmosphere of ozone and oxygen, it is possible to obtain a dense Al ₂ O ₃ film with few pinholes and good film quality. it can.

According to the invention, the Al ₂ O ₃ film is
Since the film is formed in the range of 50 to 500 nm, Al
It is possible to prevent the diffusion of alkali ions in the substrate through the ₂ O ₃ film, and it is possible to prevent the diffusion of alkali ions into the member formed on the substrate.

[0021]

EXAMPLE FIG. 1 is a sectional view showing the structure of a thin film EL element 7 using a substrate 1 manufactured according to the method of manufacturing a substrate of the present invention. As shown in FIG. 1, the substrate 1 is formed by forming an Al ₂ O ₃ film 1b on a translucent glass substrate 1a made of soda lime glass or the like. The Al
_{The 2} O ₃ film 1b is formed on the surface of the glass substrate 1a as follows. About 90 to 130 depending on the thermostat
The liquid Al (i-OC ₃ H ₇ ) ₃ is vaporized from a bubbling container kept at a temperature of ℃ by using an inert gas such as He, N ₂ and Ar as a carrier gas and a bubbling gas. It is supplied on the surface of the substrate 1a.
The glass substrate 1a is heated to a substrate temperature of 350 ° C., and Al (i-OC) supplied on the glass substrate 1a.
₃ H ₇ ) ₃ is thermally decomposed on the surface of the glass substrate 1a to form an Al ₂ O ₃ film 1b. The film forming rate of the Al ₂ O ₃ film 1b at this time is about 10 nm / min, and the Al ₂ O ₃ film 1b having a film thickness of 150 nm is formed on the glass substrate 1a in a film forming time of 15 minutes.

The substrate 1 on which the Al ₂ O ₃ film 1b is formed as described above is heated to 480 ° C., and the atmospheric pressure is 100 Pa, 1
Heat treatment is performed for 30 minutes in an O ₂ gas atmosphere containing ˜15% O ₃ . As a result, undecomposed substances in the Al ₂ O ₃ film are decomposed, and the film thickness of the Al ₂ O ₃ film 1b is reduced to 120 nm.

On the substrate 1, an ITO film (indium tin oxide film) is laminated as an Al ₂ O ₃ film 1b to form a transparent electrode 2 in a stripe shape in the left-right direction in FIG. Further laminated on the ITO film, for example _{SiO 2, Si 3 N 4,} Ta 2 O 5, the lower insulating layer 3 made of an insulating material such as SrTiO ₃ is formed by sputtering or the like, are laminated in this ZnS : Mn light emitting layer 4 is formed.

The light emitting layer 4 is formed by an electron beam evaporation method in order to investigate whether the effect of preventing diffusion of alkali ions of the Al ₂ O ₃ film 1b is changed by forming the light emitting layer 4 through different heat treatments. The film was formed by the CVD method. The light emitting layer 4 formed by the electron beam evaporation method has a substrate temperature of 2
The temperature is maintained at 50 to 300 ° C., and ZnS: Mn pellets to which 0.5% by weight of Mn is added are evaporated by electron beam heating using an evaporation source. As a result, a ZnS: Mn vapor deposition film is formed to 500
Formed to a film thickness of 0-7000Å and further 480 in vacuum
It can be obtained by heat treatment at ℃ for 2 hours.

In the light emitting layer 4 formed by the CVD method, the substrate temperature is kept at 480 ° C. (450 to 500 ° C.), and 800 to 10
Vapor from ZnS powder heated to 00 ° C. is carried on the substrate by H ₂ gas. At the same time, HCl + H ₂ mixed gas is caused to act on the metal Mn heated to 600 to 700 ° C.
By supplying Mn on the substrate as nCl ₂ ,
It is obtained by forming a ZnS: Mn film on a substrate. The time for forming the ZnS: Mn film by such a CVD method is set to 2 hours, and the heat treatment after the film formation is not performed.

An upper insulating layer 5 similar to the lower insulating layer 3 is formed by laminating on the light emitting layer 4. Stacked on this, a striped back electrode 6 is formed in a direction orthogonal to the transparent electrode 2 formed of the ITO film, that is, in a direction perpendicular to the paper surface of FIG. The back electrode 6 is realized by an Al vapor deposition film or the like. In the thin film EL element 7 described above, when an AC electric field is applied between the transparent electrode 2 and the back electrode 6, the light emitting layer 4 of the picture element where the electrodes cross each other emits light.

The Al ₂ O ₃ film 1b is formed on the soda lime glass 1a by vapor phase growth using Al (i-0C ₃ H ₇ ) ₃ as the Al alkoxide. The Al
_As a raw material for forming the ₂ O ₃ film 1b by the vapor phase growth method, any Al alkoxide may be used. _{However, Al (i-0C 3 H} 7) 3 has a high deposition rate, and substrate temperature of giving a uniform film thickness distribution because the temperature range suitable for a soda glass substrate 1a, as Al alkoxide Al ( i-0C ₃ H _{7) 3} is preferable to use.

FIG. 2 is an Arrhenius plot showing the relationship between the film formation rate by the general CVD method and the substrate temperature.
Generally _{Si (OC 2 H 5) 4} , Al (i-0C 3 H 7) 3 and _{Ti (i-0C 3 H 7} ) 4 alkoxides such can generate a respective oxide film by thermal decomposition. C
The temperature is the most important parameter for the film formation rate by the VD method, and the relationship between the film formation rate and the substrate temperature is shown in FIG. In FIG. 2, the vertical axis represents the film formation rate, and the horizontal axis represents the reciprocal of the absolute temperature of the substrate. As shown in FIG. 2, in the low temperature region, the reaction itself on the substrate surface becomes the rate-determining process of film formation, and the film formation rate increases as the substrate temperature rises. When the temperature becomes higher, the film formation rate becomes faster, but the temperature dependence becomes smaller. In this region, the diffusion of the reaction product generated on the substrate surface to the outside or the supply of the raw material gas becomes a rate-determining process, and the nonuniformity of the film thickness becomes remarkable. When the temperature becomes higher, solid nuclei are generated in the gas phase due to the reaction in the gas phase, and the film formation rate becomes slow. When the nuclei generated in the vapor phase are deposited on the substrate surface, the nonuniformity of the film thickness becomes more remarkable. Therefore, in order to obtain a film forming rate with a uniform film thickness distribution and good productivity, the substrate temperature during film forming is selected near the upper limit within the reaction rate-determining region.

FIG. 3 is an Arrhenius plot showing the relationship between the deposition rate of the Al ₂ O ₃ film by the thermal decomposition of Al alkoxide and the substrate temperature. In FIG. 3, the vertical axis represents the logarithmic value of the film formation rate, and the horizontal axis represents the reciprocal of the absolute temperature of the substrate. A
Al (OC ₂ H ₅ ) ₃ and Al (i-
OC ₃ H ₇ ) ₃ was used. When an Al ₂ O ₃ film is formed by thermal decomposition of Al alkoxide, as shown in FIG. 3, at a substrate temperature of 450 ° C., the film formation rate of Al (OC ₂ H ₅ ) ₃ is about 60 Å / min. On the other hand, Al (i
Deposition rate by -OC ₃ H _{7) 3} is about 800 Å / min. At a substrate temperature of 400 ° C, Al (OC ₂ H ₅ ) ₃
The film-forming speed according to is about 15Å / min. On the other hand, the deposition rate of Al (i-OC ₃ H ₇ ) ₃ is about 500Å
/ Min. As described above, it can be seen that Al (i-OC ₃ H ₇ ) ₃ has a very high film formation rate as compared with Al (OC ₂ H ₅ ) ₃ .

Further, as shown in FIG. 3, when the Al ₂ O ₃ film 1b is formed by thermal decomposition of Al alkoxide, Al
When (i-OC ₃ H ₇ ) ₃ is used, the reaction rate-determining region is in the substrate temperature range of 300 to 400 ° C., and the strain point of the glass substrate 1 a using soda lime glass is about 500 ° C. It is suitable for forming the Al ₂ O ₃ film 1b on the glass substrate 1a. When Al alkoxide is selected as Al (i-OC ₃ H ₇ ) ₃ as described above, the temperature of the substrate 1a during film formation is appropriately in the range of 300 to 450 ° C., and more preferably film formation is performed. It is performed in the reaction rate-determining region,
Moreover, the substrate temperature is not too low, 350 to 400 ° C.
The range is good. The deposition rate of the Al ₂ O ₃ film 1b at this time is 10 to 40 nm / min, and the deposition rate of the Al ₂ O ₃ film 1b is 10 nm.
The film is formed to a film thickness of 0 to 300 nm.

FIG. 4 shows a substrate temperature of 350 ° C. by the CVD method.
In a diagram showing the infrared absorption spectrum of the formed the Al ₂ O ₃ film, FIG. 5 is a diagram showing the infrared absorption spectrum of the formed the Al ₂ O ₃ film at a substrate temperature of 400 ° C. by CVD, FIG. 6 is a diagram showing an infrared absorption spectrum of an Al ₂ O ₃ film formed at a substrate temperature of 450 ° C. by the CVD method. The infrared absorption spectrum is obtained by irradiating a sample with infrared light and measuring the wavelength dependence of the intensity of transmitted light from the sample. From this infrared absorption spectrum, the substance having the specific bond can be quantified based on the absorption of the light of the specific wavelength by the specific bond in the sample.

4, 5 and 6, the horizontal axis represents the wave number (cm ^-1 ) of the irradiation light and the vertical axis represents the transmittance of the transmitted light. The spectral absorption region due to the OH groups contained in the residual undecomposed material in the Al ₂ O ₃ film 1b has a wave number of 3400.
The absorption center is in the range of up to 500 cm ⁻¹ , and the large absorption region on the long wavelength side in the figure is due to the Al—O bond.

In FIG. 4, the solid line P1 shows the actual absorption spectrum of the Al ₂ O ₃ film, and the broken line P2 shows the absorption spectrum when undecomposed products of Al alkoxide are not contained in the film. In addition, the portion where the spectrum is absorbed is shown by hatching. As shown by the solid line P1 in FIG.
The Al ₂ O ₃ film formed at ℃ showed a relatively large spectral absorption in the region centered on the wave number of 3400 cm ⁻¹ ,
It can be seen that a considerable amount of undecomposed Al alkoxide remains in the Al ₂ O ₃ film.

Further, in FIG. 5, the solid line Q is the same as in FIG.
1 shows the absorption spectrum of an actual Al ₂ O ₃ film, and the broken line Q
2 shows the absorption spectrum when the undecomposed product of Al alkoxide is not contained in the film. As shown by the solid line Q1 in FIG. 5, the absorption of the spectrum is observed in the region centered on the wave number of 3400 cm ⁻¹ even in the Al ₂ O ₃ film formed at the substrate temperature of 400 ° C. However, in this case, it can be seen that the percentage of absorption is smaller in FIG. 5 compared to the absorption shown in FIG.

Further, as shown by the solid line R in FIG. 6, in the Al ₂ O ₃ film formed at the substrate temperature of 450 ° C., the wave number is 3
No spectral absorption is seen in the region centered at 400 cm ^-1 . Thus, when the substrate temperature during film formation is low, a large amount of undecomposed Al alkoxide remains in the Al ₂ O ₃ film, that is, the film quality is poor, and the higher the substrate temperature during film formation, the higher the Al ₂ O ₃ content. There are few undecomposed substances of Al alkoxide in the film,
That is, it is understood that the film quality is good.

On the other hand, when the substrate temperature during film formation becomes higher and the diffusion rate-controlled region is 450 ° C. or higher, as can be seen from the Arrhenius plots shown in FIGS. 2 and 3, the diffusion reaction on the substrate surface is The film becomes vigorous and the film-forming particles once formed on the surface of the substrate diffuse into the gas phase, and the film-forming rate becomes slower than the reaction rate of the Al alkoxide on the substrate surface.
Further, once the film-forming particles are separated from the surface of the substrate by a certain distance or more, a depletion distribution in which the particles are not supplied to the surface of the substrate starts to occur again, and a uniform film thickness distribution cannot be obtained.
Therefore, the Al ₂ O ₃ film is formed in the reaction rate-determining region, and the subsequent heat treatment can decompose and oxidize the remaining undecomposed material in the film to obtain a uniform and good-quality Al ₂ O ₃ film. It is thought to be possible.

The substrate 1 having the Al ₂ O ₃ film 1b formed on the glass substrate 1a is heated to a substrate temperature of 450 to 500 ° C., 10 to 1.01 × 10 ⁵ Pa, and 1 to 15% of O _3. The heat treatment is performed for 10 to 60 minutes in an O ₂ gas atmosphere containing. Undegraded product in the Al ₂ O ₃ film 1b is thermally decomposed at a temperature higher than the substrate temperature when the Al ₂ O ₃ film 1b is deposited, A
Isopropyl alcohol, H ₂ O, etc. are diffused from the l ₂ O ₃ film 1b and diffused, and are oxidized in an O ₂ atmosphere. As a result, the thickness of the Al ₂ O ₃ film 1b is reduced to 85 to 90%, and the absorption of OH groups in the infrared absorption spectrum disappears.

A formed at a substrate temperature of 350 to 400 ° C.
If the l ₂ O ₃ film 1b is heat-treated at a substrate temperature of 450 ° C. or higher for 30 minutes, the absorption of OH groups in the infrared absorption spectrum due to undecomposed substances remaining in the Al ₂ O ₃ film 1b disappears. Has been confirmed. In addition, A
The leak current due to the undecomposed material in the l ₂ O ₃ film 1b is eliminated, and the insulating properties of the Al ₂ O ₃ film 1b are improved. Furthermore, by adding O ₃ during the heat treatment, the leakage current is reduced and the insulating characteristics are further improved, as compared with the case where the heat treatment is performed in an O ₂ atmosphere, so that the effect of O ₃ is confirmed. From these results, it is confirmed that the residual undecomposed matter was decomposed.

As described above, the Al ₂ O ₃ film 1b formed at the substrate temperature of 350 to 400 ° C. is decomposed and removed by the heat treatment at 450 ° C. or higher, and the undecomposed matter remaining in the Al ₂ O ₃ film 1b is decomposed and removed. Thus, an Al ₂ O ₃ film 1b having no pinhole is obtained. Since soda lime glass has a large shrinkage ratio due to temperature change and the strain point of soda lime glass is approximately 500 ° C., the upper limit of the substrate temperature for the heat treatment is selected to be 500 ° C.
When the Al ₂ O ₃ film 1b is formed at a substrate temperature of 300 to 450 ° C., it is necessary to perform heat treatment in the temperature range of 450 to 500 ° C.

FIG. 7 shows an Al ₂ O ₃ film 1b having a different film forming method.
It is a figure which shows the alkali ion diffusion prevention effect of. In the graph shown in FIG. 7, an Al ₂ O ₃ film 1b having a film thickness of 150 nm is formed on the soda glass substrate 1a by the sputtering method and the CVD method of the present embodiment, and the sample is heat-treated at 500 ° C. for 2 hours. After that, IMA (ion micro probe analyzer)
Was used to measure the alkali ion composition in the film thickness direction of the sample.

The Al ₂ O ₃ film formed by the sputtering method uses a metal target Al99.999 as a target and has an atmospheric pressure of 5 × 10 ^{− in a} mixed gas atmosphere of Ar + O ₂ mixed with Ar / O ₂ = 1/1. ³ Torr, substrate temperature 20
A film was formed by a reactive sputtering method under the conditions of 0 ° C., an acceleration voltage of 2.5 KV, and a current of 450 mA.

The Al ₂ O ₃ film is formed by the CVD method using Al (i-OC ₃ H ₇ ) ₃ as the Al alkoxide, the substrate temperature is 350 ° C., the film forming speed is 10 nm / min,
An Al ₂ O ₃ film was once formed on the substrate with a film formation time of 18 minutes to a film thickness of 18 minutes.
The film was formed to a thickness of 0 nm and further heat-treated at 480 ° C. (450 ° C. for a substrate not subjected to pretreatment) for 30 minutes. At this time, the thickness of the Al ₂ O ₃ film is 150 nm ±
It was 10 nm.

The IMA performs elemental analysis by irradiating a sample with a beam of primary ions such as Cs and O, and guiding the secondary ions emitted from the sample to a magnetic field deflection type mass spectrometer for mass analysis. According to IMA, the sample is etched by the irradiation of the primary ions, so measuring the change over time in the concentration of the specific element is equivalent to measuring the change over the concentration of the specific element in the thickness direction of the sample.

In the Al ₂ O ₃ film 1b thus formed by the CVD method, sodium ions are detected at a position of about 25 nm in the film thickness direction from the interface with the soda glass. As shown in FIG. 7, excellent diffusion preventing effect of sodium ions than Al ₂ O ₃ film formed by the formed the Al ₂ O ₃ film is a sputtering method by CVD, Al ₂ O by sputtering The effect as an ion barrier layer can be exhibited with a film thickness of about half that of the _three films. Therefore, if the thickness of the Al ₂ O ₃ film 1b formed by the above-described CVD method is 50 nm or more, a sufficient alkali ion diffusion preventing property as an ion barrier layer can be obtained. Further, in consideration of the manufacturing cost, the film thickness of the Al ₂ O ₃ film is preferably in the range of 50 to 500 nm.

Since Si ⁺ ions and Ca ⁺ ions other than sodium ions have large molecular weights, Al ₂ as an ion barrier layer is used for these ions.
O ₃ film may be a dense molecular structure somewhat, the Al ₂ O ₃ film of film as shown in the Al ₂ O ₃ film and 4 also compares the the Al ₂ O ₃ film by CVD method by sputtering There is no significant difference in the ion distribution in the thickness direction. Therefore, for these ions, a sufficient ion diffusion preventing effect can be obtained even with an Al ₂ O ₃ film formed by sputtering.

[0046]

[Table 1]

Table 1 shows the aging comparison results of the thin film EL element 7 using the substrate 1 manufactured according to the present invention and other thin film EL elements. In Table 1, the thin film EL of
The device uses soda lime glass as a substrate on which the ion barrier layer is not formed. The thin film EL device of (1) uses a substrate in which a SiO ₂ film formed by the DIP method is formed as an ion barrier layer on a soda lime glass substrate. The thin film EL device of No. 1 is a substrate 1 in which an Al ₂ O ₃ film is formed by a CVD method of the present invention as an ion barrier layer on a soda lime glass substrate.
To use. The thin film EL device of is a Si ₃ N ₄ film formed by sputtering as an ion barrier layer on a soda lime glass substrate.
A substrate on which a film is formed is used. In the thin film EL device of No. 3, non-alkali glass containing no alkali ions (OA-2 manufactured by Nippon Electric Glass Co., Ltd.) is used as a substrate. Each of these thin film EL devices was aged and compared.

The substrate on which the SiO ₂ film is formed by the DIP method is commercially available as "DIP coat".
_{The two} films have a thickness of 100 nm. Substrate was formed an Al ₂ O ₃ film by the CVD method, the substrate temperature 350 ° C. at the time of film formation, is once deposited an Al ₂ O ₃ film to 110nm at a deposition rate of 10 nm / min, the film formation time 11 minutes , About 15
% O ₃ in an O ₂ gas atmosphere at a substrate temperature of 450 ° C., 3
Heat treatment was performed for 0 minutes. This gives a film thickness of about 100n
m Al ₂ O ₃ film was obtained. Furthermore, Si ₃ by sputtering method
The N ₄ film uses silicon 99.999 as a target and is formed to have a film thickness of 100 nm under the conditions of an atmospheric pressure of 5 × 10 ⁻³ Torr, a substrate temperature of 250 ° C., an acceleration voltage of 2.5 KV, and a current of 450 mA in an N ₂ gas atmosphere. did. Aging is performed by continuously applying an AC electric field of f = 500 Hz to the electrodes of the thin film EL element at a temperature of 55 ° C. for 20, 120 and 240 hours. After that, the number of break points (minute dielectric breakdown points) is counted. Further, the thin film EL element is formed in 6400 picture elements.

As shown in Table 1, in the thin film EL element, since the ion barrier layer is not formed, the number of break points is extremely large as compared with other EL elements, which is considered to be the influence of the alkali ions of the substrate. Many break points occurred along the aging time along both ends of the transparent electrode in the longitudinal direction, and the electrode was broken after 240 hours.
In the thin-film EL element of, since the SiO ₂ film is formed on the substrate by the DIP method, the occurrence of the break point can be suppressed to a considerably low level as compared with the case without the ion barrier layer, but with the aging time. The break point increased, and the electrode was broken after 240 hours.

Further, a thin-film EL device having an Al ₂ O ₃ film is formed.
The element and the thin film EL element formed with the Si ₃ N ₄ film have the same small number of break points as the thin film EL element using the non-alkali glass OA-2 as a substrate, and Al _{2 formed} by the CVD method. It was confirmed that both the O ₃ film and the Si ₃ N ₄ film formed by the sputtering method have sufficient alkali ion diffusion preventing properties as an ion barrier layer. Also,
Even when the light emitting layer 4 is formed by the electron beam vapor deposition method, A by the CVD method is used as in the case of forming the light emitting layer 4 by the CVD method.
It was confirmed that the l ₂ O ₃ film exhibited a sufficient alkali ion diffusion preventive property.

As described above, according to this embodiment, the thin film EL
In the element 7, the Al ₂ O ₃ film 1b is formed as an ion barrier layer on the glass substrate 1a having translucency, and the Al ₂ O _{3 is formed.}
The constituent members of the thin film EL element 7 are formed by laminating on the film 1b. The substrate 1 is a glass substrate 1a made of soda lime glass, and C
An Al ₂ O ₃ film 1b is formed using the VD method, and the substrate 1 is further heat-treated in an O ₂ mixed gas atmosphere containing O ₃ . Therefore, the quality of the formed Al ₂ O ₃ film is good, and even in the heat treatment in the manufacturing process of the thin film EL element 7, it is possible to prevent the diffusion of alkali ions from the soda lime glass to the constituent members, and It is possible to reduce the occurrence of minute dielectric breakdown points due to the diffusion of alkali ions.
Further, since inexpensive soda lime glass can be used as the glass substrate 1a, the manufacturing cost of the thin film EL element 7 can be reduced.

The Al alkoxide is Al (i-O
Since C ₃ H ₇ ) ₃ is selected, the deposition rate is higher than that when other Al alkoxide is used even at a relatively low temperature, and the Al ₂ O ₃ film 1b can be deposited with _high productivity.

Further, since the substrate temperature at the time of forming the Al ₂ O ₃ film 1b is selected to be 300 to 450 ° C., it is possible to form the Al ₂ O ₃ film 1b having high film thickness uniformity.

Further, since the heat treatment carried out in the atmosphere of O ₂ gas containing O ₃ is selected in the range of 400 to 500 ° C., the unheated remaining in the Al ₂ O ₃ film 1b below the allowable temperature of soda lime glass having a low strain point. Al ₂ O ₃ film with good film quality by decomposing decomposed products 1
b can be obtained.

Furthermore, the film thickness of the Al ₂ O ₃ film 1b is set to 50.
~ 500 nm is selected, so that the alkali ions diffused from the soda lime glass are thin film E from the surface of the Al ₂ O ₃ film 1b.
It is possible to prevent diffusion into the constituent members of the L element 7.

[0056]

According to the present invention as described above, according to the present invention, on at least one surface of the glass substrate was deposited an Al ₂ O ₃ film by a vapor deposition method using aluminum alkoxide as a starting material, the Al ₂ O _The glass substrate on which the _three films are formed is heat-treated in a mixed gas atmosphere of ozone and oxygen. Since aluminum alkoxide is used as a raw material for film formation, the Al ₂ O ₃ film can be formed at a relatively low substrate temperature during film formation. Further, since the vapor deposition method is used as the film forming method, A
Since the l ₂ O ₃ film is formed through the fluid intermediate product, it is possible to form a film with excellent step coverage. Therefore, an Al ₂ O ₃ film without pinholes can be formed.
Further, as compared with the case of forming a film by the sputtering method, the deterioration of the film quality due to the incorporation of the sputtering gas into the film does not occur. Furthermore, since the glass substrate formed by the vapor phase growth method is heat-treated in a mixed gas of ozone and oxygen as an atmosphere, residual undecomposed substances in the Al ₂ O ₃ film can be decomposed and oxidized, and the film quality can be improved. A good dense and high density Al ₂ O ₃ film can be formed. This makes it possible to obtain a high effect of preventing alkali ion diffusion in the Al ₂ O ₃ film. Therefore, inexpensive and highly smooth soda lime glass can be used for the substrate, and the manufacturing cost of the substrate can be reduced.

Further, according to the present invention, since the aluminum alkoxide is selected as Al (i-OC ₃ H ₇ ) ₃ , the deposition rate of the Al ₂ O ₃ film formed on the glass substrate even at a relatively low temperature can be improved. The film forming process can be performed quickly and with good productivity.

Further, according to the present invention, since the substrate temperature at the time of forming the Al ₂ O ₃ film is selected in the range of 300 to 450 ° C., the film forming rate is high and the Al ₂ O ₃ film having a uniform film thickness is formed. Can be formed.

Still further in accordance with the present invention, said Al ₂ O ₃
Since the substrate on which the film is formed is subjected to heat treatment within a range of 400 to 500 ° C. in a mixed gas atmosphere of ozone and oxygen, undecomposed matter does not remain in the Al ₂ O ₃ film, and the pin is dense. A with few holes and excellent effect of preventing alkali ion diffusion
An l ₂ O ₃ film can be obtained.

Further, according to the present invention, since the Al ₂ O ₃ film is formed in the thickness range of 50 to 500 nm, alkali ions from the substrate are prevented from diffusing through the Al ₂ O ₃ film. can do.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a thin film EL element 7 using a substrate 1 manufactured according to a substrate manufacturing method of the present invention.

FIG. 2 is an Arrhenius plot showing a relationship between a film formation rate by a general CVD method and a substrate temperature.

FIG. 3 is an Arrhenius plot showing the relationship between the deposition rate of an Al ₂ O ₃ film by thermal decomposition of Al alkoxide and the substrate temperature.

FIG. 4 is a diagram showing an infrared absorption spectrum of an Al ₂ O ₃ film formed at a substrate temperature of 350 ° C. by a CVD method.

FIG. 5 is a diagram showing an infrared absorption spectrum of an Al ₂ O ₃ film formed at a substrate temperature of 400 ° C. by a CVD method.

FIG. 6 is a diagram showing an infrared absorption spectrum of an Al ₂ O ₃ film formed at a substrate temperature of 450 ° C. by a CVD method.

FIG. 7 is a diagram showing an alkali ion diffusion preventing effect of an Al ₂ O ₃ film 1b having a different film forming method.

FIG. 8 is a characteristic diagram showing a state of thermal diffusion of alkali ions into a SiO ₂ film, an Al ₂ O ₃ film and a Si ₃ N ₄ film.

[Explanation of symbols]

1 substrate 1a translucent glass substrate 1b Al ₂ O ₃ film 2 transparent electrode 3 lower insulating layer 4 light emitting layer 5 upper insulating layer 6 back electrode

Claims (5)

[Claims] 1. On at least one surface of a glass substrate,
A step of forming an Al ₂ O ₃ film by a vapor phase growth method using aluminum alkoxide as a raw material, and a glass substrate on which the Al ₂ O ₃ film is formed are heat-treated in a mixed gas atmosphere of ozone and oxygen. And a step of performing the method. 2. The aluminum alkoxide is Al
(I-OC ₃ H ₇₎ the production method of the substrate according to claim 1, wherein the chosen _3. 3. The substrate temperature at the time of forming the Al ₂ O ₃ film is 3
2. The range of 00 to 450 [deg.] C. is selected.
A method for manufacturing the substrate described. 4. The method of manufacturing a substrate according to claim 1, wherein the heat treatment temperature performed in a mixed gas atmosphere of ozone and oxygen is selected in the range of 400 to 500 ° C. 5. The thickness of the Al ₂ O ₃ film is 50 to 500 n.
2. The method for manufacturing a substrate according to claim 1, wherein the range is m.