JP2003301170A - Phosphor thin film, production process therefor, and el panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prepare a phosphor thin film which dispenses with the use of a filter because of high luminance and good color purity, has a long luminance life and is suitable particularly for each element of RGB for a full color EL panel. <P>SOLUTION: The phosphor thin film contains a base material and a luminescent center, wherein the base material comprises a sulfide containing at least an alkaline earth element, Ga and/or In and sulfur (S), and optionally also Al, or an oxysulfide containing oxygen (O) in addition to those elements, and wherein the atomic ratio B/A of B standing for the Ga, In and Al in the base material to A standing for the alkaline earth element therein satisfies the formula: B/A=(2.1 to 3.5). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor thin film used for a light emitting layer of an inorganic EL device, a method for manufacturing the same, and an EL panel using the same.

[0002]

2. Description of the Related Art In recent years, thin-film EL devices have been actively researched as small-sized or large-sized lightweight flat panel displays. A monochrome thin film EL display using a phosphor thin film of manganese-doped zinc sulfide that emits yellow-orange light has already been put into practical use with a double insulating structure using thin film insulating layers 2 and 4 as shown in FIG. In FIG. 2, the substrate 1
A lower electrode 5 having a predetermined pattern is formed thereon, and a first insulating layer 2 is formed on the substrate 1 on which the lower electrode 5 is formed. Further, the light emitting layer 3 and the second insulating layer 4 are sequentially formed on the first insulating layer 2, and the lower electrode 5 and the matrix circuit are formed on the second insulating layer 4. The upper electrode 6 is formed in a predetermined pattern.

Further, for a personal computer as a display,
Colorization is indispensable to support TV and other displays. Thin-film EL displays using sulfide phosphor thin films have excellent reliability and environmental resistance, but at present, the characteristics of EL phosphors that emit light in the three primary colors of red, green, and blue are not sufficient. , Is not suitable for color. The blue light emitting phosphor is Sr as a base material.
S, SrS: Ce or Zn using Ce as an emission center
S: Tm, ZnS: Sm, Ca as the red light emitting phosphor
S: Eu, ZnS: Tb, Ca as a green light emitting phosphor
S: Ce is a candidate and research is continuing.

These phosphor thin films which emit light in the three primary colors of red, green and blue have problems in emission brightness, efficiency and color purity, and at present, a color EL panel has not been put into practical use. In particular, blue has a relatively high luminance obtained by using SrS: Ce, but as blue for a full-color display, the luminance is insufficient and the chromaticity is shifted to the green side. Development of a good blue light emitting layer is desired.

To solve these problems, Japanese Unexamined Patent Publication No. 7-
122364, JP-A-8-134440,
SrGa ₂ S ₄ : Ce, CaG, as described in Technical Bulletin EID 98-113, pages 19-24, and Jpn.J.Appl.Phys.Vol.38, (1999) pp. L1291-1292.
Blue phosphors based on thiogallate or thioaluminate such as a ₂ S ₄ : Ce and BaAl ₂ S ₄ : Eu have been developed. These thiogallate-based phosphors have no problem in terms of color purity, but have low brightness and particularly have a multi-component composition, and thus it is difficult to obtain a thin film having a uniform composition. It is considered that a high quality thin film cannot be obtained due to poor crystallinity due to poor composition controllability, generation of defects due to sulfur depletion, inclusion of impurities, etc., and therefore brightness cannot be increased. In particular, thioaluminate is extremely difficult to control the composition.

In realizing a full color EL panel,
A stable, low-cost process for producing blue, green, and red phosphor thin films is required, but as mentioned above, the chemical or physical properties of the phosphor thin film host material and emission center material are The manufacturing method differs depending on the type of the phosphor thin film, because it differs depending on the individual material. Therefore,
If the film forming conditions are set so that high brightness can be obtained with a phosphor thin film having a specific composition, high brightness cannot be achieved with phosphor thin films of other colors. Therefore, in order to manufacture a full-color EL panel, a plurality of types of film forming apparatuses are required, which complicates the manufacturing process and increases the panel manufacturing cost.

Further, the EL spectra of the blue, green and red EL phosphor thin films described above are all broad, and when used in a full-color EL panel, the RGB required for the panel is filtered using the EL phosphors. It must be excised from the EL spectrum of the thin film. The use of the filter not only complicates the manufacturing process, but the most serious problem is the decrease in brightness. When RGB is extracted using a filter, the brightness of the blue, green, and red EL phosphor thin films is 10% to 5%.
Since 0% or more is lost, the brightness of the panel is reduced and it is not practical.

In order to put it into practical use as an EL panel, it is necessary that the brightness be maintained for a long period of time, that is, the brightness life be long.

In order to solve the above-mentioned problems, a red, green, and blue phosphor thin film which has high luminance and does not need to use a filter because of its good color purity and has a long luminance life is required. Has been. Further, it is required that such red, green, and blue phosphor thin films can be manufactured using the same film forming method and film forming apparatus.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to have a high brightness and, in addition, a good color purity, which makes it unnecessary to use a filter, has a long brightness life, and is a full color E
It is an object of the present invention to provide a phosphor thin film that is particularly suitable for each RGB element for an L panel. Another object of the present invention is to provide a full-color EL panel using such a phosphor thin film,
It is possible to manufacture at low cost by a simple process.

[0011]

The above objects are achieved by the present invention described in (1) to (11) below. (1) A base material containing a base material and an emission center,
A sulfide that contains at least an alkaline earth element, Ga and / or In, and sulfur (S) and may further contain Al, or oxysulfide containing oxygen (O) in addition to these. In the host material, the alkaline earth element is represented by A, and Ga, In, and Al are represented by B.
The phosphor thin film having an atomic ratio B / A of more than 2 and not more than 3.5 when expressed by. (2) The phosphor thin film according to (1) above, wherein B / A = 2.05 to 3.0. (3) In the host material, the atomic ratio O / (S + O) of oxygen to the total of oxygen and sulfur is O / (S + O) = 0.01 to 0.85, which is the above (1) or (2). Phosphor thin film. (4) In the matrix material, the atomic ratio O / (S + O) of oxygen with respect to the total of oxygen and sulfur is O / (S + O) = 0.1 to 0.85, which is the above (1) or (2). Phosphor thin film. (5) The phosphor thin film according to any one of (1) to (4) represented by the following composition formula. Formula _{A x B y O z S w} : M [ where, M represents a metal element to be a luminescent center, A is M
At least one element selected from g, Ca, Sr, and Ba, B is at least one element selected from Ga, In, and Al, and B is Ga and / or
Or In is always included. x = 1 to 5, y = 1 to 1
5, z = 3 to 30, w = 3 to 30] (6) The emission center is a rare earth element (1) to
The phosphor thin film according to any one of (5). (7) An EL panel having the phosphor thin film according to any one of (1) to (6) above. (8) A method for producing the phosphor thin film according to any one of (1) to (6), which comprises forming a sulfide thin film and then performing annealing treatment in an oxidizing atmosphere to form an oxysulfide thin film. A method of manufacturing a phosphor thin film having the following. (9) A method for producing the phosphor thin film according to any one of (1) to (6) above, which comprises an alkaline earth element sulfide or metal as an evaporation source, Ga sulfide and / or Alternatively, a method for producing a phosphor thin film, comprising a step of forming an oxysulfide thin film by a reactive vapor deposition method using at least an In sulfide-containing one and using oxygen gas as a reactive gas. (10) A method for producing the phosphor thin film according to any one of (1) to (6) above, which comprises an alkaline earth element sulfide or metal as an evaporation source, Ga sulfide and / or Alternatively, a method for producing a phosphor thin film, which includes a step of forming a sulfide thin film by an evaporation method using at least an In sulfide-containing material, and then performing an annealing treatment in an oxidizing atmosphere to form an oxysulfide thin film. (11) The method for producing a phosphor thin film according to the above (9) or (10), wherein the luminescence center is contained in the evaporation source containing alkaline earth sulfide.

[0012]

[Function] First, the inventors of the present invention, alkaline earth thiogallate whose composition is easier to control than alkaline earth thioaluminate,
Alkaline earth thioindates were thinned as a phosphor for EL. An EL device was produced using the obtained thin film, but desired light emission could not be obtained. The emission brightness of the obtained thin film was at most 2 cd / m ² , and it was necessary to increase the brightness for application to an EL panel.

Based on these results, as a result of repeated research on the phosphor thin film of this composition system, the present invention has been achieved. That is, in the host material mainly composed of alkaline earth thiogallate or alkaline earth thioindate, by controlling the atomic ratio of Ga or In to the alkaline earth element to be within a predetermined range, a critically high brightness can be obtained. I found that I could be. It has also been found that by adding a predetermined amount of oxygen to the base material to form an oxysulfide, the brightness is dramatically increased and the brightness life is remarkably extended.

In the present invention, by adding various luminescent centers corresponding to the luminescent color to such a base material, a phosphor thin film which emits red, green and blue light with high color purity with high brightness is obtained. can get. Moreover, these phosphor thin films are
Since any of them can be formed by using the reactive vapor deposition method, the present invention is effective in reducing the cost of the full-color EL panel.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below.

The phosphor thin film of the present invention contains a base material and an emission center. This host material is a sulfide that contains an alkaline earth element, Ga and / or In, and sulfur (S), and may further contain Al,
Alternatively, it is an oxysulfide containing oxygen (O) in addition to these elements.

The phosphor thin film of the present invention is preferably crystallized, but may be in an amorphous state having no definite crystal structure. As a crystal contained in the phosphor thin film of the present invention, when A represents an alkaline earth element and B represents Ga, In and Al, A ₅ B ₂ S ₈ , A ₄ B ₂ S ₇ , A ₂ B ₂
S ₅ , AB ₂ S ₄ , AB ₄ S ₇ , A ₄ B ₁₄ S ₂₅ , AB ₈ S
₁₃ and AB ₁₂ S ₁₉ are preferably used alone or in combination of two or more, and particularly preferably include AB ₂ S ₄ crystals.
In the phosphor thin film, O may replace a part of S in the crystal.

In the present specification, the alkaline earth element means
It is one of Be, Mg, Ca, Sr, Ba and Ra. Among these, Mg, Ca, Sr and Ba are preferable, and Ba and Sr are particularly preferable.

The element to be combined with the alkaline earth element is Ga and / or In, or Al in addition to Ga and / or In, and the combination of these elements is arbitrary.

The phosphor thin film of the present invention is preferably represented by the composition formula A _x B _y O _{z Sw} : M. In the above composition formula, M represents a metal element serving as an emission center, and A represents M
represents at least one element selected from g, Ca, Sr, and Ba, B is at least one element selected from Ga, In, and Al, and B is Ga and / or
Or In is always included. That is, B is Ga and / or In, Ga and Al, In
And Al, or Ga, In, and Al.

The atomic ratio of Al in the element B is 0.3.
The following is preferable. If the atomic ratio of Al is too large, it becomes difficult to control the composition of the phosphor thin film, and the effect of the present invention is to obtain high brightness and long life by optimizing the composition of alkaline earth thiogallate or alkaline earth thioindate. Will be insufficient.

In the above formula, x, y, z and w represent the molar ratio of the elements A, B, O and S. x, y, z and w
Is preferably x = 1 to 5 y = 1 to 15 z = 3 to 30 w = 3 to 30.

Alkaline earth elements are represented by A, and Ga, In
And Al is represented by B, the atomic ratio B / A of the total of Ga, In and Al to the alkaline earth element in the host material is more than 2 and 3.5 or less, preferably 3.
It is 0 or less. By setting B / A within this range, extremely high brightness can be obtained critically. However, in order to reduce the luminance variation due to the composition variation (B / A variation), B / A is preferably 2.05 or more, and more preferably 2.1 or more.

The atomic ratio O / (S + O) of oxygen to the total of oxygen and sulfur in the host material, that is, z / (w + z) in the above composition formula, is preferably 0.01 to.
0.85, more preferably 0.01 to 0.5, still more preferably 0.05 to 0.5, and most preferably 0.1 to 0.5.
It is 0.4. By controlling the amount of oxygen in this way, the luminance life can be critically extended and high luminance can be obtained.

When A _x B _y O _{z Sw} is a compound having a stoichiometric composition, this compound has x {A (O, S)} and (y
/ 2) {B ₂ (O, S) ₃ }. Therefore, the stoichiometric composition is almost obtained when z + w = x + 3y / 2. The composition of the phosphor thin film is preferably near the stoichiometric composition in order to obtain high-luminance light emission, and specifically, 0.9 ≦ (x + 3y / 2) / (z + w) ≦ 1.1. Is preferred.

The composition of the phosphor thin film is determined by fluorescent X-ray analysis (XR
F), X-ray photoelectron analysis (XPS), TEM-EDS (Tr
ansmission Electron Microscopy-Energy Dispersive
It can be confirmed by X-ray Spectroscopy).

Oxygen has the effect of dramatically increasing the emission brightness of the phosphor thin film. In addition, the light emitting element has a lifetime because the luminance deteriorates with the elapse of the light emitting time, but by adding oxygen, the lifetime characteristic can be improved and the luminance deterioration can be prevented. When oxygen is added to sulfides, crystallization is promoted during film formation of this host material or during post-treatment such as annealing after film formation, and the luminescence centers such as rare earth elements make effective transitions in the compound crystal field. Therefore, it is considered that high luminance and stable light emission can be obtained. Also, the base material itself is more stable in air than pure sulfide. It is considered that this is because the stable oxide component protects the sulfide component in the film from the atmosphere.

The element M contained as the luminescent center is M
Examples include one or more elements selected from transition metal elements such as n and Cu, rare earth metal elements, Pb, and Bi. The rare earth element is at least Sc,
Y, La, Ce, Pr, Nd, Gd, Tb, Ho, E
It is selected from r, Tm, Lu, Sm, Eu, Dy and Yb. Eu and Ce are used as the blue phosphor, Eu, Ce, Tb and Ho are used as the green phosphor, and red phosphor is used as the red phosphor. One of Pr, Eu, Sm, Yb and Nd is preferable. Among these, Eu, Pr, Tb and Sm are preferable in combination with the base material, Eu and Sm are more preferable, and Eu is most preferable. The emission center is 0.1 to 1 for alkaline earth elements.
It is preferable to add 0 atom%.

As described above, it is considered that in the phosphor thin film to which oxygen is added, the luminescence center of a rare earth element or the like has an effective transition in the compound crystal field, and stable light emission with high brightness can be obtained. This effect is remarkable only in the luminescence center sensitive to the crystal field, and is particularly remarkable when the luminescence center is Eu ²⁺ .

As the alkaline earth thiogallate,
Although SrGa ₂ S ₄ : Ce has been studied as a phosphor for blue, Ce is a problem in SrS: Ce, and Ce ³⁺ and Ce ⁴⁺ coexist in the matrix material. I will end up. Therefore, since the emission spectrum does not have a single peak, color control is difficult. On the other hand, when Eu is added, a single emission peak is obtained. It is considered that the fact that the effect of improving the brightness by adding oxygen is low when Ce is added is related to the coexistence of Ce ³⁺ and Ce ⁴⁺ .

In order to obtain such a phosphor thin film, for example, the following method is preferable. Here, Ba
_{x Ga y O z S w:} Eu phosphor thin film as an example will be described.

In the first method, barium gallate pellets to which Eu is added are used as a vapor deposition source, and H _{2 is used} as a reactive gas.
A phosphor thin film is formed by reactive vapor deposition using S gas. Here, H ₂ S gas is used to introduce sulfur into the film.

In the second method, a multi-source vapor deposition method is used. Examples of the multi-source deposition method include (1) binary reactive deposition using Eu-added barium oxide pellets and gallium oxide pellets as evaporation sources and H ₂ S gas as a reactive gas; (2) evaporation Binary vacuum deposition using barium sulfide pellets and gallium oxide pellets with Eu added as a source and no reactive gas; (3) Using barium oxide pellets and gallium sulfide pellets with Eu added as an evaporation source, the reaction Binary vacuum vapor deposition without using a reactive gas; (4) It is possible to use barium sulfide pellets and gallium sulfide pellets to which Eu is added as evaporation sources, and binary reactive vapor deposition using O ₂ gas as a reactive gas. preferable.

Further, in place of the Eu-added barium oxide pellets in the above method (1) and the Eu-added barium sulfide pellets in the above method (4), metal Eu and metal Ba are used as evaporation sources. Good.

Among the second methods, a particularly preferable method is to dispose at least a gallium sulfide vaporization source and a barium sulfide vaporization source added with an emission center in a vacuum chamber, and introduce O ₂ gas into them. This is a method in which gallium sulfide and barium sulfide are evaporated from each of the evaporation sources, and oxygen is combined when the evaporation material is deposited on the substrate to obtain an oxysulfide thin film.

In the third method, oxygen is introduced into the phosphor thin film by annealing. That is, after forming the sulfide thin film, annealing treatment is performed in an oxidizing atmosphere to form an oxysulfide thin film.

As a vapor deposition method used in the third method, for example, (1) a _binary reaction using barium sulfide pellets and gallium sulfide pellets to which Eu is added as an evaporation source and H ₂ S gas as a reactive gas Vapor deposition, (2) Binary reactive vapor deposition using barium sulfide pellets and gallium sulfide pellets with Eu added as an evaporation source and no reactive gas, (3) Barium thiogallate with Eu added as an evaporation source Binary vacuum vapor deposition using pellets, (4) Binary reactive vapor deposition using barium thiogallate pellets with Eu added as an evaporation source and H ₂ S gas as a reactive gas is preferable.

Further, in place of the Eu-added barium sulfide pellets in the above methods (1) and (2), metal Eu and metal Ba may be used as the evaporation source.

The annealing in the third method is performed in an oxidizing atmosphere such as oxygen or air. The oxygen concentration in the annealing atmosphere is preferably equal to or higher than the oxygen concentration in air. Further, the annealing temperature is preferably 500 ° C. or higher.
The temperature is set to 1000 ° C., more preferably 600 ° C. to 800 ° C. By this annealing, oxygen is introduced into the phosphor thin film, and the crystallinity of the phosphor thin film is significantly improved.

Of the third methods, the method using the above method (1) or (2) is particularly preferable.

Of the above methods, the third method is most preferable.
Is the method. In the third method, the amount of oxygen in the phosphor thin film can be easily controlled, and a phosphor thin film having high crystallinity can be easily obtained.

The element of the emission center is added to the evaporation source in the form of metal, fluoride, oxide or sulfide. Since the luminescent center content of the evaporation source and the luminescent center content in the thin film formed using the evaporation source are different, the luminescent center content in the evaporation source should be adjusted so that the desired content in the thin film is obtained. adjust.

In each of the above methods, the luminescence center is preferably added to the alkaline earth sulfide, and in particular, in the alkaline earth sulfide (eg BaS) evaporation source, the luminescence center is a sulfide (eg EuS). It is preferably present. It is possible to uniformly add luminescence centers of several mol% or less to the alkaline earth sulfide. Evaporating pellets, powders, green compacts, lumps, etc. made of alkaline earth sulfide to which luminescence centers are added, the luminescence centers become
Since it evaporates with the alkaline earth sulfide and reaches the substrate, a small amount of luminescence centers can be added with good controllability to the thin film formed. That is, since the alkaline earth sulfide acts as a carrier for the impurity substance (emission center), 1 m in the thin film
It is possible to add luminescence centers of ol% or less accurately and uniformly.

Although the alkaline earth sulfide used as the evaporation source may be deviated by about 10% with respect to the stoichiometric composition, it emits light when an emission center is added to the alkaline earth sulfide to prepare an evaporation source. To improve the accuracy of the central addition amount,
It is preferable that the composition is as close to the stoichiometric composition as possible.

In each of the above methods, the substrate temperature during vapor deposition is room temperature to 600 ° C, preferably 100 ° C to 300 ° C.
And it is sufficient. When the substrate temperature is too high, the surface of the thin film of the base material becomes rough, pinholes are generated in the thin film, and a current leakage problem occurs in the EL element. Also, the thin film may turn brown. Therefore, the above temperature range is preferable.

The formed oxysulfide thin film is preferably a highly crystalline thin film. The crystallinity can be evaluated by, for example, X-ray diffraction. In order to increase the crystallinity, the substrate temperature should be as high as possible. In addition, the annealing is not limited to the above-mentioned annealing in an oxidizing atmosphere, and N _{2 in} vacuum.
Annealing in medium, Ar, S vapor, or H ₂ S is also effective for improving the crystallinity.

The thickness of the phosphor thin film is not particularly limited, but if it is too thick, the driving voltage increases, and if it is too thin, the luminous efficiency decreases. Specifically, depending on the phosphor material, it is preferably 100 to 2000 nm, particularly 150
It is about 700 nm.

The pressure during vapor deposition is preferably 1.33 × 10 5.
^{-4 to} 1.33 x 10 ^-1 Pa (1 x 10 ^-6 to 1 x 10 ^-3
A Torr), O ₂ gas for adding oxygen, to adjust both the introduction amount of H ₂ S gas for promoting sulfide, pressure 6.65 × 10 ^-3 ~6.65 × 10 ^{- 2} Pa (5 x 1
It is more preferable to keep it at 0 ^{−5 to} 5 × 10 ⁻⁴ Torr).
If the pressure is higher than this, the operation of the E gun becomes unstable, and composition control becomes extremely difficult. H ₂ S gas,
Alternatively, the amount of O ₂ gas introduced is preferably 5 to 200 SCCM, particularly preferably 10 to 30 SCCM, depending on the capacity of the vacuum system.

If necessary, the substrate may be moved or rotated during vapor deposition. By moving and rotating the substrate, the film composition becomes uniform and variations in the film thickness distribution are reduced.

When the substrate is rotated, the rotation speed of the substrate is preferably 10 times / min or more, more preferably 10 to 50 times / min, and especially about 10 to 30 times / min. If the rotation speed of the substrate is further increased, it becomes difficult to seal the vacuum chamber to keep it airtight. On the other hand, if it is too slow, composition unevenness occurs in the film thickness direction in the tank, and the characteristics of the prepared phosphor thin film deteriorate. The rotating means for rotating the substrate can be configured by a known rotating mechanism using a power transmission mechanism, a reduction mechanism, and the like in which a power source such as a motor and a hydraulic rotating mechanism is combined with a gear, a belt, a pulley, and the like.

Any heating means for heating the evaporation source or the substrate may be used as long as it has a predetermined heat capacity, reactivity and the like, and examples thereof include a tantalum wire heater, a sheath heater and a carbon heater. The heating temperature by the heating means is preferably 1
About 0 to 1400 ℃, the accuracy of temperature control is 1000 ℃
Is ± 1 ° C, preferably ± 0.5 ° C.

One example of the constitution of the apparatus for forming the light emitting layer of the present invention is shown in FIG. Here, a method of producing oxygen-added barium thiogallate: Eu while introducing oxygen with gallium sulfide and barium sulfide as evaporation sources is taken as an example. In the figure, a substrate 12 on which a light emitting layer is formed and EB evaporation sources 14 and 15 are arranged in a vacuum chamber 11.

The EB (electron beam) evaporation sources 14 and 15 which serve as evaporation means for gallium sulfide and barium sulfide,
It has "crucibles" 40, 50 in which gallium sulfide 14a and barium sulfide 15a added with an emission center are housed, and electron guns 41, 51 containing filaments 41a, 51a for electron emission. A mechanism for controlling the beam is built in each of the electron guns 41 and 51. AC power supplies 42 and 52 and bias power supplies 43 and 53 are connected to the electron guns 41 and 51.

An electron beam is controlled from the electron guns 41 and 51, and the crucible 4 is controlled with a preset power.
It is possible to evaporate the gallium sulfide 14a and the barium sulfide 15a, which are irradiated with 0 and 50 and have the luminescence center added, at a predetermined ratio. Further, a method called a multi-source pulse deposition method in which multi-source simultaneous deposition is performed with one E gun may be used.

The vacuum chamber 11 has an exhaust port 11a,
By exhausting from the exhaust port, the inside of the vacuum chamber 11 can be made to have a predetermined vacuum degree. The vacuum chamber 11 also has a reactive gas introduction port 11b for introducing oxygen gas or hydrogen sulfide gas.

The substrate 12 is fixed to the substrate holder 12a, and the rotating shaft 12b of the substrate holder 12a is rotatably fixed from the outside while maintaining the degree of vacuum in the vacuum chamber 11 by a rotating shaft fixing means (not shown). There is. And
If necessary, it can be rotated at a predetermined rotation speed by a rotating means (not shown). Further, the heating means 13 constituted by a heater wire or the like is adhered and fixed to the substrate holder 12a so that the substrate can be heated and held at a desired temperature.

Using such a device, the EB evaporation source 14,
Gallium sulfide vapor and barium sulfide vapor evaporated from 15 are deposited on the substrate 12 and are combined with the introduced oxygen to form an oxysulfide thin film. At that time, by rotating the substrate 12 as necessary, the composition and film thickness distribution of the deposited thin film can be made more uniform. In the above example, the case where two EB evaporation sources are used has been described, but the evaporation source is not limited to the EB evaporation source, and other evaporation sources such as a resistance heating evaporation source may be used depending on the materials and conditions used. You may use.

As described above, according to the phosphor thin film material and the manufacturing method by vapor deposition of the present invention, it is possible to easily form a phosphor thin film which emits light with high brightness and has a long life.

In order to obtain an inorganic EL element using the phosphor thin film of the present invention, for example, the structure shown in FIG. 2 may be used.

FIG. 2 is a perspective view showing an element having a double insulating structure which is an example of an inorganic EL element using the phosphor thin film of the present invention in the light emitting layer 3. In FIG. 2, a lower electrode 5 having a predetermined pattern is formed on a substrate 1, and a thick first insulating layer (thick film dielectric layer) 2 is formed on the lower electrode 5. A light emitting layer 3 and a second insulating layer (thin film dielectric layer) 4 are sequentially formed on the first insulating layer 2, and the lower electrode 5 and the matrix are formed on the second insulating layer 4. The upper electrode 6 is formed in a predetermined pattern so as to form a circuit.

Between the substrate 1, the electrodes 5 and 6, the first insulating layer 2 and the second insulating layer 4, a layer for improving adhesion, a layer for relieving stress, and preventing reaction. An intermediate layer such as a layer may be provided. The thick film surface may be polished or a flattening layer may be used to improve the flatness.

The substrate has a heat resistant temperature or melting point of 600 ° C. or higher, preferably 700 ° C. or higher, particularly 80 ° C., which can withstand the thick film forming temperature, the light emitting layer forming temperature, and the light emitting layer annealing temperature.
The material is not particularly limited as long as it is made of a material having a temperature of 0 ° C. or higher and can maintain a predetermined strength. Specifically, glass substrates, alumina (Al ₂ O ₃ ), forsterite (2MgO · SiO ₂ ), steatite (Mg)
O ・ SiO ₂ ), mullite (3Al ₂ O ₃・ 2SiO)
₂ ), beryllia (BeO), aluminum nitride (Al
N), silicon nitride (Si ₃ N ₄ ), silicon carbide (Si
A ceramic substrate such as C + BeO) and a heat resistant glass substrate such as crystallized glass can be used. Of these, an alumina substrate and a crystallized glass substrate are particularly preferable,
Substrates made of beryllia, aluminum nitride or silicon carbide are preferred when thermal conductivity is required.

In addition to this, a quartz substrate or a thermally oxidized silicon wafer can be used, and a metal substrate of titanium, stainless steel, Inconel, iron or the like can also be used. When a conductive substrate made of metal or the like is used, a structure in which an insulating thick film having a lower electrode inside is formed on the substrate is preferable.

For the thick film dielectric layer (first insulating layer), it is preferable to use a material having a relatively large dielectric constant selected from known dielectric thick film materials. As such materials,
For example, lead titanate-based materials, lead niobate-based materials, barium titanate-based materials and the like are preferable.

The resistivity of the thick film dielectric layer is 10 ⁸ Ω
-Cm or more, especially about 10 ¹⁰ to 10 ¹⁸ Ω · cm. The relative dielectric constant ε is preferably ε = 100 to
It is about 10,000. The film thickness is preferably 5 to 50 μm, particularly preferably 10 to 30 μm.

The method for forming the thick film dielectric layer is not particularly limited, but a method that can relatively easily obtain a film having a thickness of 10 to 50 μm, such as a sol-gel method or a printing and firing method, is preferable.

In the case of the printing and firing method, the grain size of the material is appropriately adjusted and mixed with a binder to obtain a paste having an appropriate viscosity. Using this paste, a coating film is formed on the substrate by a screen printing method and dried. The coating film is baked at an appropriate temperature to obtain a thick film.

The constituent material of the thin film dielectric layer (second insulating layer) is, for example, silicon oxide (SiO ₂ ), silicon nitride (SiN), tantalum oxide (Ta ₂ O ₅ ), strontium titanate (SrTiO ₃ ). , Yttrium oxide (Y ₂ O ₃ ), barium titanate (BaTiO ₃ ),
Lead titanate (PbTiO ₃ ), lead zirconate titanate (PZT), zirconia (ZrO ₂ ), silicon oxynitride (SiON), alumina (Al ₂ O ₃ ),
Lead niobate, Pb (Mg _1/3 Ni _2/3 ) O ₃ and PbTiO ₃
A mixture with (PMN-PT) is preferred. The thin film dielectric layer may have a structure of a single layer or a multilayer of layers containing at least one of these. As a method of forming the thin film dielectric layer, an existing method such as a vapor deposition method, a sputtering method or a CVD method may be used. The thickness of the thin film dielectric layer is preferably 50 to 1000 nm, particularly 100 to 500 nm.
It is about nm.

The lower electrode is formed between the substrate and the first insulating layer or in the first insulating layer. The lower electrode is exposed to high temperature during annealing of the light emitting layer, and is also exposed to high temperature during formation of the first insulating layer when the first insulating layer is formed of a thick film. Therefore, it is preferable that the lower electrode constituent material is excellent in heat resistance. Specifically, as a main component, palladium, rhodium, iridium, rhenium, ruthenium, platinum, tantalum, nickel, chromium, titanium, etc.
It is preferable to contain one kind or two or more kinds.

Further, the upper electrode is preferably a transparent electrode having a light-transmitting property in a predetermined light emission wavelength range because light emission is usually taken out from the side opposite to the substrate. The transparent electrode may be used for the lower electrode as long as the substrate and the insulating layer have a light-transmitting property, since emitted light can be extracted from the substrate side.
In this case, it is particularly preferable to use a transparent electrode such as ZnO or ITO. ITO usually contains In ₂ O ₃ and SnO in a stoichiometric composition, but the amount of O may be slightly deviated from this. The mixing ratio of SnO ₂ to In ₂ O ₃ is preferably 1 to 20% by mass, more preferably 5 to 12% by mass. The mixing ratio of ZnO to In ₂ O ₃ in IZO is usually about 12 to 32% by mass.

Further, the electrode may contain silicon as a main component. This silicon electrode is amorphous (a-S) even if it is polycrystalline silicon (p-Si).
i) may be used, and if necessary, single crystal silicon may be used.

The silicon electrode is doped with impurities in order to secure conductivity in addition to the main component silicon. The dopant used as an impurity may be any dopant that can ensure a predetermined conductivity, and a normal dopant used in silicon semiconductors can be used. Specifically, B, P, As, Sb and Al are preferable. The dopant concentration is preferably about 0.001 to 5 at%.

As a method of forming an electrode with these materials, existing methods such as a vapor deposition method, a sputtering method, a CVD method, a sol-gel method, and a printing and baking method may be used. In particular, an electrode is provided inside a substrate. When the structure is provided with the thick film described above, the same method as for the dielectric thick film is preferable.

The preferred resistivity of the electrode is 1 Ω · cm or less, particularly 0.
003 to 0.1 Ω · cm. The thickness of the electrode depends on the material to be formed, but is preferably 50 to 2000 nm,
Particularly, it is about 100 to 1000 nm.

The phosphor thin film of the present invention can be applied to various EL panels, and is suitable for, for example, a full-color panel for display, a multi-color panel, and a partial color panel that partially displays three colors.

[0076]

EXAMPLES The present invention will be described in more detail below by showing specific examples of the present invention.

[0077]Example 1 An EL device using the phosphor thin film of the present invention was produced. Basis
BaTiO, which is the same material for both the plate and the thick film insulating layer₃ System invitation
Using an electric material (dielectric constant 5000), P as the lower electrode
A d electrode was used. First, make a green sheet of the substrate
Then, screen print the lower electrode and thick film dielectric layer on top of this.
After that, the whole was baked. The surface is then polished to 30
A substrate with a thick dielectric layer having a thickness of μm was obtained. Furthermore, on this
BaTiO ₃ The film is sputtered to a thickness of 400 nm
Form and anneal in air at 700 ° C to form a composite substrate
It was

On this composite substrate, an Al ₂ O ₃ film (50 nm
Thickness) / ZnS film (200 nm thickness) / phosphor thin film (300 nm)
Thickness) / ZnS film (200 nm thickness) / Al ₂ O ₃ film (50 nm)
(Thickness) was formed. Each thin film provided on both sides of the phosphor thin film is for stably emitting light as an EL element.

The phosphor thin film was formed by the following procedure using the vapor deposition device having the structure shown in FIG. However, EB evaporation source 1
In place of 4, a resistance heating evaporation source was used.

An EB evaporation source 15 containing SrS powder containing 5 mol% of EuS and a resistance heating evaporation source (14) containing Ga ₂ S ₃ powder were provided in a vacuum chamber 11 into which H ₂ S gas was introduced. A phosphor thin film was formed on the substrate which was evaporated from each source at the same time, heated to 400 ° C. and rotated. The evaporation rate of each evaporation source is 1 nm / s for the film formation rate of the phosphor thin film.
Adjusted to be ec. The rate of introduction of H ₂ S gas is 20
SCCM. The laminated structure including the phosphor thin film thus formed was annealed in air at 750 ° C. for 10 minutes.

In order to measure the composition, the laminated structure was formed on the Si substrate and then annealed. The conditions for forming and annealing the laminated structure were the same as those for the laminated structure in the EL element. As a result of composition analysis of the phosphor thin film in this laminated structure by fluorescent X-ray analysis, atomic ratio (arbitrary unit) of Sr: 5.91, Ga: 18.93, O: 11.52, S: 48.81. , Eu: 0.33. _{That, Sr x Ga y O z S} w: atomic ratio in Eu is, Ga / Sr = y / x = 3.20, O / (S + O) = z / (w + z) = 0.191, (x + 3y / 2) /(Z+w)=1.04.

Further, an ITO transparent electrode having a film thickness of 200 nm was formed on the laminated structure by an RF magnetron sputtering method using an ITO oxide target at a substrate temperature of 250 ° C. to complete an EL device.

Between the two electrodes of the obtained EL element, 1 kHz
By applying an electric field with a pulse width of 50 μs of
A green emission luminance of 00 cd / m ² was obtained with good reproducibility. Figure 3
Shows the emission spectrum.

Example 2 In Example 1, when Tb was used instead of Eu, green light emission with a luminance of 53 cd / m ² was obtained.

Example 3 In Example 1, instead of Sr, or together with Sr, one or more of Mg, Ca and Ba were used, respectively, and substantially the same result was obtained. In this case, blue-green light emission was obtained.

In the phosphor thin films formed in Examples 2 to 3, y / x in the above composition formula is 2.2.
Is in the range of 3.0 to 3.0, and z / (w + z) is 0.13 to
Within the range of 0.33, (x + 3y / 2) / (z + w)
Was in the range of 0.9 to 1.1.

Example 4 An EL device was prepared in the same manner as in Example 1 except that a phosphor thin film was formed by the following procedure using In instead of Ga.

In the vapor deposition apparatus of FIG. 1, the EB evaporation source 14
Was replaced by a resistance heating evaporation source. An EB evaporation source 15 containing SrS powder added with 5 mol% of Eu and a resistance heating evaporation source (14) containing In ₂ S ₃ powder are provided in a vacuum chamber 11 into which O ₂ gas is introduced, and each source is provided. Further, it was evaporated at the same time, heated to 400 ° C., and a phosphor thin film was formed on the rotated substrate. The evaporation rate of each evaporation source was adjusted so that the film formation rate of the thin film was 1 nm / sec. The introduction rate of O ₂ gas was 10 SCCM. Annealed at 750 ° C N ₂
Done in gas for 10 minutes.

In order to measure the composition, a laminated structure containing a phosphor thin film was formed on a Si substrate and then annealed. The formation conditions and annealing conditions of this laminated structure were the same as those of the laminated structure in the EL element. As a result of composition analysis of the phosphor thin film in this laminated structure by fluorescent X-ray analysis, Sr: 5.48, In: 16.81, O: 6.65, S: 52.84 in atomic ratio (arbitrary unit). , Eu: 0.28. _{That, Sr x In y O z S} w: atomic ratio in Eu is, Ga / Sr = y / x = 3.07, O / (S + O) = z / (w + z) = 0.111, (x + 3y / 2) /(Z+w)=0.94.

When the light emitting characteristics of the obtained EL device were measured in the same manner as in Example 1, a red light emission luminance of 30 cd / m ² was obtained with good reproducibility. The emission spectrum is shown in FIG.

Example 5 When annealing a phosphor thin film, by changing at least one of temperature, atmosphere and humidity, O / (S +
An EL device was produced in the same manner as in Example 1 except that O) was controlled to have the values shown in Table 1.

These EL devices were continuously driven under the same conditions as in Example 1, and the initial luminance and the time until the luminance decreased to half (luminance half life) were examined. The results are shown in Table 1.

[0093]

[Table 1]

From Table 1, it can be seen that when O / (S + O) is 0.1 or more, the initial luminance is particularly high and the light emission life is sufficiently long. Incidentally, the phosphor thin film of the EL element, composition formula _{Sr x Ga y O z S w} : in Eu, y
/ X is 2.2 to 2.7, and (x + 3y / 2) / (z
+ W) was 0.9 to 1.1. The composition of the phosphor thin film was measured by analyzing the cross section of the device with TEM-EDS after evaluating the brightness.

Example 6 An EL device was prepared in the same manner as in Example 1 except that the phosphor thin film was formed so that the atomic ratio Ga / Sr became the value shown in FIG. The atomic ratio Ga / Sr was changed by controlling the evaporation rate from the EB evaporation source. The brightness of these EL devices was measured in the same manner as in Example 1. The results are shown in Table 2 and FIG.

[0096]

[Table 2]

From Table 2 and FIG. 5, it can be seen that when Ga / Sr is made larger than the stoichiometric composition of 2, high brightness can be obtained critically. Incidentally, the phosphor thin film of the EL element, composition formula _{Sr x Ga y O z S w} : in Eu,
z / (w + z) is 0.14 to 0.27, and (x + 3
y / 2) / (z + w) was 0.9 to 1.1. For the composition of the phosphor thin film, the element cross section was TEM-ED after luminance evaluation.
It was measured by analyzing with S.

As a result of analysis by TEM-EDS,
The phosphor thin films formed in this example and the above examples were crystallized, and the main crystal phase was AB ₂ S ₄ .

[0099]

The phosphor thin film of the present invention can emit red, green, and blue light, and can obtain good color purity. Therefore, when it is applied to a full-color EL panel or a multi-color EL panel, it is a filter. No need to use. Further, in the present invention,
Remarkably high brightness can be realized by controlling the atomic ratio of Ga or In to the alkaline earth element in the phosphor thin film. Furthermore, in the present invention, by controlling the oxygen content in the phosphor thin film, the brightness can be increased and the brightness life can be lengthened. Therefore, the present invention realizes an EL panel having high brightness, long life, and low cost, and thus the present invention has great industrial utility value.

Since the phosphor thin film of the present invention contains alkaline earth thiogallate and / or alkaline earth thioindate, whose composition is easier to control than alkaline earth thioaluminate, as a main component, high brightness can be obtained with good reproducibility. In addition, there is little variation in brightness and the yield is high.

Further, according to the present invention, a phosphor thin film which emits red, green and blue colors can be obtained by using materials having similar chemical or physical properties. Therefore, since the phosphor thin films of each color can be formed by using the same film forming method or film forming apparatus, the manufacturing process of the full-color EL panel can be simplified and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a configuration example of a vapor deposition device used in a manufacturing method of the present invention.

FIG. 2 is a perspective view showing a part of an inorganic EL element having a double insulating structure by cutting out.

FIG. 3 is a graph showing an emission spectrum of the EL device of Example 1.

FIG. 4 is a graph showing an emission spectrum of the EL device of Example 4.

FIG. 5 is a graph showing the relationship between the atomic ratio Ga / Sr of the phosphor thin film and the luminance of the EL device manufactured in Example 6.

[Explanation of symbols]

1 substrate 2 First insulating layer (thick film dielectric layer) 3 light emitting layer 4 Second insulating layer (thin film dielectric layer) 5 Lower electrode 6 Upper electrode (transparent electrode) 11 vacuum chamber 12 substrates 13 Heating means 14 EB evaporation source 15 EB evaporation source

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05B 33/14 H05B 33/14 ZF term (reference) 3K007 AB02 AB04 AB11 AB18 BA06 DA02 DA05 DB01 DC04 EC02 FA01 4H001 CA04 CF02 XA08 XA12 XA13 XA16 XA20 XA31 XA38 XA49 XA56 YA00

Claims (11)

[Claims] 1. A host material and a luminescent center are contained, the host material contains at least an alkaline earth element, Ga and / or In, and sulfur (S), and further Al
Is a sulfide that may contain, or is an oxysulfide that further contains oxygen (O) in addition to these. In the base material, the alkaline earth element is represented by A, and Ga, In, and Al are represented by B. When represented by, the atomic ratio B / A is more than 2 and 3.
A phosphor thin film having a thickness of 5 or less. 2. B / A = 2.05-3.0 The phosphor thin film according to claim 1, wherein 3. The fluorescent material according to claim 1, wherein the atomic ratio O / (S + O) of oxygen to the total of oxygen and sulfur in the host material is O / (S + O) = 0.01 to 0.85. Body thin film. 4. The fluorescent material according to claim 1, wherein the atomic ratio O / (S + O) of oxygen to the total of oxygen and sulfur in the host material is O / (S + O) = 0.1 to 0.85. Body thin film. 5. The phosphor thin film according to claim 1, which is represented by the following composition formula. Formula _{A x B y O z S w} : M [ where, M represents a metal element to be a luminescent center, A is M
At least one element selected from g, Ca, Sr, and Ba, B is at least one element selected from Ga, In, and Al, and B is Ga and / or
Or In is always included. x = 1 to 5, y = 1 to 1
5, z = 3 to 30, w = 3 to 30] 6. The phosphor thin film according to claim 1, wherein the emission center is a rare earth element. 7. An EL panel having the phosphor thin film according to claim 1. 8. A method for manufacturing a phosphor thin film according to claim 1, further comprising a step of forming a sulfide thin film and then performing annealing treatment in an oxidizing atmosphere to form an oxysulfide thin film. A method of manufacturing a phosphor thin film having the same. 9. A method for producing the phosphor thin film according to claim 1, wherein the evaporation source contains a sulfide or metal of an alkaline earth element, Ga sulfide and / or A method for producing a phosphor thin film, comprising a step of forming an oxysulfide thin film by a reactive vapor deposition method using at least an In sulfide-containing material and oxygen gas as a reactive gas. 10. The method for producing the phosphor thin film according to claim 1, wherein the evaporation source contains a sulfide or metal of an alkaline earth element, Ga sulfide and / or A method for producing a phosphor thin film, which comprises a step of forming a sulfide thin film by a vapor deposition method using at least one containing In sulfide, and then performing an annealing treatment in an oxidizing atmosphere to form an oxysulfide thin film. 11. The method for producing a phosphor thin film according to claim 9, wherein the luminescence center is contained in the evaporation source containing alkaline earth sulfide.