JP2008156495A - Fluorophor thin film and method of forming the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorophor thin film favorable for use in an inorganic EL and a PDP, high in color purity and giving high luminance, and to provide a method of forming the same in high speed. <P>SOLUTION: The fluorophor thin film is formed from a sulfide represented by the following compositional formula: Zn<SB>x0</SB>Ba<SB>x1</SB>Al<SB>x2</SB>S<SB>x3</SB>Eu<SB>x4</SB>(wherein, x0 to x4 satisfy the expressions (1) to (5)) constituted of zinc, barium, aluminum, sulfur and europium, wherein the compound texture of the thin film is characterized by comprising a compound phase represented by compositional formula: BaAl<SB>2</SB>S<SB>4</SB>:Eu. The expressions are as follows: (1) 0.005≤x0≤0.3, (2) x1+x4=1, (3) 2.01≤x2≤3.0, (4) 4.0<x3≤4.3, and (5) 0.03≤x4≤0.10. The fluorophor thin film is produced by the following process: A BaAlEu alloy layer is additionally subjected to sputtering film formation on a film-formed zinc sulfide layer, followed by annealing the resultant film-formed layers while keeping the layers at 500-700°C in a hydrogen sulfide atmosphere. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a phosphor thin film and a film forming method thereof, and more specifically, can emit light only from a compound whose composition formula is represented by BaAl ₂ S ₄ : Eu, that is, to increase the emission wavelength of fluorescence to a long wavelength. Phosphorous thin film with good color purity and high brightness, good for inorganic EL (electroluminescence) and PDP (plasma display panel), having a small shift and high emission intensity, and efficiently transforming it into a large substrate The present invention relates to a film forming method that can be formed.

In recent years, inorganic EL elements have been actively developed as display elements for computer monitors and portable devices. Among them, a method for performing full-color display using a high-luminance blue phosphor as a phosphor thin film of an inorganic EL element has been proposed, and its practical application has attracted attention. As a promising phosphor thin film developed so far, a thin film mainly composed of a compound whose composition formula is represented by BaAl ₂ S ₄ : Eu is cited. This is obtained by substituting an element (Eu) serving as a light emission center by using a semiconductor material whose composition formula is represented by BaAl ₂ S ₄ as a base material. For example, a phosphor thin film in which EuS corresponding to 0.03-0.10 atomic% of Ba lattice position is added to a base material made of BaAl ₂ S ₄ has good color purity, and is expected as a phosphor for inorganic EL. ing.

As a method for producing such a phosphor thin film, a reactive sputtering method in which hydrogen sulfide gas is contained in a sputtering gas, a reactive vapor deposition method in which a vapor gas containing each constituent element is supplied to form a film, molecular beam epitaxy And chemical vapor deposition have been performed (see, for example, Patent Document 1). In addition, using a sintered body target composed of a compound whose composition formula is represented by BaAl ₂ S ₄ : Eu (hereinafter sometimes referred to as “BaAl ₂ S ₄ : Eu compound”), argon and hydrogen sulfide A method of sputtering in a mixed gas is proposed (for example, see Patent Document 2).
In addition, the composition formula includes at least a divalent metal element such as barium, a trivalent metal element such as aluminum, and a base material that can be represented by sulfur and an emission center material, and the oxygen content ratio is 5% by mass or less. Furthermore, a method is disclosed in which zinc is evaporated during sputtering by using a target containing zinc sulfide and sulfur is filled in the film (for example, see Patent Document 3).
Further, a method is disclosed in which an alloy target whose composition can be expressed by a divalent metal element such as barium or a trivalent metal element such as aluminum is sputtered in hydrogen sulfide (Patent Document 4).

  By the way, with the recent increase in the size of display screens, a phosphor thin film with good color purity and high brightness is desired by a sputtering method that is easy to increase in size. Therefore, it is suitable for film formation of such a phosphor thin film. There is a need for a suitable film formation method.

However, the conventional phosphor thin film forming method in which a sintered body target made of a BaAl ₂ S ₄ : Eu compound or a BaAl: Eu alloy target is sputtered in hydrogen sulfide has a technical problem to be solved. Has been.
For example, BaAl ₂ S _4: when sputtering a target containing Eu compound, BaAl in the target ₂ S _4: Eu compound leaves sulfur is decomposed by argon plasma. Therefore, it is necessary to add ZnS to the hydrogen sulfide gas or the target. In the target to which ZnS is added, ZnS decomposes to supplement S of the BaAl ₂ S ₄ : Eu compound. As a result, ZnS contained in the target is difficult to reach the film. For this reason, in order to increase the S concentration in the film to the stoichiometric composition, the ZnS content in the target is increased. However, when the ZnS content in the target is increased, the amount of BaAl ₂ S ₄ reaching the substrate is decreased, so that the film formation rate is decreased. Furthermore, when ZnS decomposes in the target, zinc is generated and zinc is mixed into the film. Thereby, when the zinc concentration in the film increases, the emission luminance of the film decreases.

As a countermeasure, the above-mentioned problems can be improved by using a binary simultaneous sputtering method of a ZnS target and a BaAl ₂ S ₄ : Eu compound target. This method is necessary. However, a thin large substrate such as a TV is difficult to rotate because the substrate is too large. Therefore, it has been difficult to form a film at high speed without uneven composition. In order to solve this, it is necessary to manufacture by a passing film forming method in which a film is formed by passing over a square target.

  In addition, in the method of sputtering an alloy target whose composition is expressed by a divalent metal element such as barium or a trivalent metal element such as aluminum in hydrogen sulfide, hydrogen sulfide is added by argon plasma because hydrogen sulfide is added during sputtering. The decomposed and generated sulfur contaminates the chamber and the vacuum system. In particular, if sulfur adheres to the piping, vacuum ion gauge, and vacuum valve, the vacuum exhaust speed is reduced, the ion gauge is disconnected, and the gas leakage of the vacuum valve occurs, resulting in poor maintainability and difficulty in mass production. Also, the film formation rate is slow.

From the above situation, a phosphor thin film with high color purity and high brightness, which mainly contains a compound represented by the composition formula BaAl ₂ S ₄ : Eu, and a film that can be uniformly formed on a large substrate. There is a need for a method.

Japanese Patent Application Laid-Open No. 07-122364 (first page, second page) Japanese Patent Application Laid-Open No. 08-134440 (pages 1 to 3) JP 2001-118677 A (first page, second page) WO 2005/085493 A1 (pages 14-17)

An object of the present invention is to make it possible to emit light only from a compound whose composition formula is represented by BaAl ₂ S ₄ : Eu in view of the above-mentioned problems of the prior art, that is, there is a shift of the emission wavelength of fluorescence to a long wavelength. A phosphor thin film that is small and has high emission intensity, is suitable for inorganic EL (electroluminescence) and PDP (plasma display panel), has good color purity and high brightness, and efficiently forms it on a large substrate. An object of the present invention is to provide a film forming method that can perform the above process.

In order to achieve the above-mentioned object, the present inventor has made extensive studies on a phosphor thin film containing a compound phase represented by a composition formula: BaAl ₂ S ₄ : Eu and a film forming method thereof, particularly a sulfurization method. As a result, in a sulfide thin film having a compound structure consisting only of a compound phase represented by a composition formula: BaAl ₂ S ₄ : Eu having a film composition represented by a specific composition formula, the composition formula is BaAl ₂ S ₄ : It has been found that a blue phosphor thin film having good color purity and high brightness can be obtained because it can emit light only from Eu compounds, and has a characteristic that the shift of the emission wavelength of fluorescence to a long wavelength is small and the emission intensity is high. It was. The “phase” described here means, for example, that “BaAl ₂ S ₄ phase” is a precipitated phase composed of a compound whose composition formula is represented by BaAl ₂ S ₄ .

Further, in the film formation method, when sputtering film formation is performed, first, a zinc sulfide film is formed at a specific substrate temperature using a target made of a sintered body of zinc sulfide, and then on the zinc sulfide film. In addition, an alloy film composed of barium, aluminum, and europium is formed at a specific substrate temperature using an alloy target composed of barium, aluminum, and europium and represented by a specific composition, and then annealed under specific conditions. The present inventors have found that a sulfide thin film having the above-mentioned characteristics is formed by controlling the zinc concentration in the film, and a blue phosphor thin film with good color purity and high luminance can be obtained. The present invention has been completed based on these findings.

That is, according to the first invention of the present invention, the following composition formula consisting of zinc, barium, aluminum, sulfur and europium:
Zn _x0 Ba _x1 Al _x2 S _x3 Eu _x4
(In the formula, x0 to x4 satisfy the requirements shown in the following (1) to (5).)
A phosphor thin film formed from a sulfide represented by:
A phosphor thin film characterized in that the compound structure is composed of a compound phase represented by a composition formula: BaAl ₂ S ₄ : Eu is provided.
(1) 0.005 ≦ x0 ≦ 0.3
(2) x1 + x4 = 1
(3) 2.01 ≦ x2 ≦ 3.0
(4) 4.0 <x3 ≦ 4.3
(5) 0.03 ≦ x4 ≦ 0.10

  According to the second invention of the present invention, a zinc sulfide layer is formed while maintaining the substrate temperature at 300 to 600 ° C. in an argon gas atmosphere using the following sintered body target (A), Subsequently, a BaAlEu alloy layer was formed by sputtering on the zinc sulfide layer using the following alloy target (B) in an argon gas atmosphere while maintaining the substrate temperature at 400 to 650 ° C. There is provided a phosphor thin film forming method according to the first invention, characterized in that annealing is performed in hydrogen sulfide while maintaining the substrate temperature at 500 to 700 ° C.

  According to a third aspect of the present invention, there is provided the phosphor thin film according to the second aspect, wherein the annealing is maintained in hydrogen sulfide having a gas pressure of 0.1 to 1 Pa for 30 to 90 minutes. A deposition method is provided.

As is clear from the above, the phosphor thin film of the present invention has a film composition represented by a predetermined composition formula in the first invention, and the compound structure is the composition formula: BaAl ₂ S ₄ : Eu. Since the sulfide thin film is composed of the compound phase represented by formula (1), light is emitted only from the compound represented by the composition formula BaAl ₂ S ₄ : Eu, the shift of the fluorescence emission wavelength to a long wavelength is small, and the emission intensity Has high characteristics and good color purity. Further, since the zinc concentration is low, the ZnS phase and the ZnAl ₂ S ₄ phase are not detected, so that the blue phosphor thin film has high luminance.

  Further, according to the second and third aspects of the phosphor thin film deposition method of the present invention, a ZnS layer is deposited under the above deposition conditions using a ZnS sintered body target, and then the ZnS layer is formed. On top of this, a BaAlEu alloy layer is formed using a BaAlEu alloy target, and then these two layers are annealed under the above conditions, whereby the ZnS layer and the BaAlEu alloy film react with each other, and the sulfide is evaporated and the zinc is evaporated. Since the above-mentioned thin film can be formed by controlling the zinc concentration, a phosphor thin film having good color purity and high luminance can be obtained which is favorable for inorganic EL and PDP.

That is, by separating sputtering film formation and annealing, the film thickness control of the ZnS layer and the BaAlEu alloy layer and the annealing conditions are optimized, there is no zinc residue, and the zinc concentration in the film decreases. In addition, the film formation rate is increased and stable film formation can be performed.
Furthermore, since hydrogen sulfide gas is not added during sputtering, safety measures for the sputtering apparatus are reduced. Further, since sulfur is not generated due to decomposition of hydrogen sulfide by plasma during sputtering, contamination of the sputtering chamber and the vacuum exhaust pipe by sulfur can be eliminated. From these things, the industrial value is very large.

Hereinafter, the phosphor thin film and the film forming method of the present invention will be described in detail.
1. Phosphor thin film The phosphor thin film of the present invention has the following composition formula composed of zinc, barium, aluminum, sulfur and europium: Zn _x0 Ba _x1 Al _x2 S _x3 Eu _x4 (wherein _{x0 to x4} are the following) (1) to the phosphor thin film formed from the sulfide represented by (5), wherein the compound structure is a compound represented by the composition formula: BaAl ₂ S ₄ : Eu. It consists of phases.
(1) 0.005 ≦ x0 ≦ 0.3
(2) x1 + x4 = 1
(3) 2.01 ≦ x2 ≦ 3.0
(4) 4.0 <x3 ≦ 4.3
(5) 0.03 ≦ x4 ≦ 0.10

In the phosphor thin film of the present invention, it is important that the compound structure of the thin film is composed of a compound phase represented by the composition formula: BaAl ₂ S ₄ : Eu. As a result, a phosphor thin film having good color purity and good for inorganic EL and PDP can be obtained.

That is, normally, in the sputtering of sulfide, when the target composition and the film composition are compared, the ratio of Ba and Al varies greatly. For example, when the Al / Ba molar ratio of the target is 2.2, the Al / Ba molar ratio of the film varies from about 2.05 to 2.10. Thus, when the composition ratio of Ba and Al in the film is on the Al-excess side, a BaAl ₄ S ₇ phase is formed in the film, so that the fluorescence peak wavelength is shifted to the long wavelength side by about 5 nm, and the emission intensity is further increased. Is also about 20% lower.

On the other hand, since the compound structure of the thin film of the present invention has only the compound phase represented by the composition formula: BaAl ₂ S ₄ : Eu, light can be emitted only from the BaAl ₂ S ₄ : Eu phase.

The composition of the thin film is represented by a composition formula: Zn _x0 Ba _x1 Al _x2 S _x3 Eu _x4 , and _{x0 to x4} in the formula satisfy the following relational expressions (1) to (5). It is important to. As a result, since the zinc concentration in the film is low, a phosphor thin film having particularly high luminance, which is good for inorganic EL and PDP, can be obtained.
(1) 0.005 ≦ x0 ≦ 0.3
(2) x1 + x4 = 1
(3) 2.01 ≦ x2 ≦ 3.0
(4) 4.0 <x3 ≦ 4.3
(5) 0.03 ≦ x4 ≦ 0.10

First, the composition ratio (x0) of zinc satisfies the relational expression of 0.005 ≦ x0 ≦ 0.3. Within this range, a particularly bright film is formed. That is, when the composition ratio of zinc exceeds 0.3, since the amount of zinc remaining in the thin film is large, a ZnS phase is formed in addition to the ZnAl ₂ S ₄ phase. Become. On the other hand, when the composition ratio of zinc is less than 0.005, it cannot react with all of the excess Al, so that BaAl ₄ S ₇ : Eu is formed in the film, and the fluorescence peak wavelength shifts to the longer wavelength side.

The composition ratio (x1) of barium and the composition ratio (x4) of europium satisfy the relational expressions x1 + x4 = 1 and 0.03 ≦ x4 ≦ 0.10. That is, europium is an element that emits fluorescence of the phosphor thin film, and replaces the lattice position of Ba of the base material whose composition formula is represented by BaAl ₂ S ₄ . Europium (Eu) is added so that the composition ratio is 0.03 to 0.10 with respect to barium (Ba). If the composition ratio of Eu is less than 0.03, the fluorescence intensity becomes low, which is not preferable. On the other hand, if the Eu composition ratio exceeds 0.10, the crystallinity of the base material deteriorates, such being undesirable.

The composition ratio (x2) of aluminum is 2.01 ≦ x2 ≦ 3.0. That is, when the Al composition ratio is less than 2.01, a compound phase having a high Ba content ratio represented by Ba ₂ Al ₂ S ₅ is generated in the phosphor thin film, and the fluorescence peak wavelength is longer. Therefore, the color purity is deteriorated. On the other hand, when the Al composition ratio exceeds 3.0, a compound phase represented by the composition formula BaAl ₄ S ₇ is generated in the phosphor thin film, the emission intensity of the base material is lowered, and the luminance is deteriorated.

  Moreover, the composition ratio (x3) of sulfur is 4.0 <x3 ≦ 4.3. That is, the composition ratio is greater than 4 which is the stoichiometric composition. When the composition ratio of sulfur is 4.0 or less, it becomes difficult to form the base material. On the other hand, if the sulfur composition ratio exceeds 4.3, it becomes easy to form Ba polysulfide in which sulfur is precipitated in the film, so the formation of the compound structure of the thin film is not stable.

2. Method for Forming Phosphor Thin Film As a film forming method for obtaining the phosphor thin film of the present invention, the substrate temperature is set to 300 to 600 ° C. in an argon gas atmosphere using the following sintered body target (A). A zinc sulfide layer is formed while maintaining, and then a BaAlEu alloy layer is formed on the zinc sulfide layer using the following alloy target (B) while maintaining the substrate temperature at 400 to 650 ° C. in an argon gas atmosphere. Then, the two layers are annealed in hydrogen sulfide while maintaining the substrate temperature at 500 to 700 ° C.
(A) It is comprised from zinc sulfide.
(B) barium, aluminum, and the composition formula consists europium: Ba _y1 Al _y2 Eu _y3 (In the formula, Y1 to Y3 are, y1 + y3 = 1,1.5 ≦ y2 ≦ 3.0,0.03 ≦ y3 ≦ 0.10 is satisfied.).

  As a result, the ZnS layer and the BaAlEu alloy layer are formed separately, and then annealed in hydrogen sulfide, so that the controllability of the composition is very good, and the inorganic thin film is composed of the sulfide thin film having the above film composition and compound structure. A phosphor thin film having good color purity and high brightness that is favorable for EL and PDP can be obtained at a high film formation rate.

  In the film forming method, for example, a means for mounting two targets of a ZnS sintered body target and a BaAlEu alloy target on two cathodes of a sputtering apparatus and sputtering them is suitable. Thus, by supplying ZnS and BaAlEu from one source to the substrate, the composition in the film and the film formation rate are stabilized, and the film can be formed with good reproducibility. Further, by annealing this film, a high-quality phosphor thin film can be formed at a high speed.

  The substrate used for the target is not particularly limited. In any substrate, a glass substrate such as an alkali-free glass for LCD or a soda-lime glass substrate for PDP, or an electrode layer and a dielectric on the glass substrate. A substrate on which body layers are stacked is used.

  As an apparatus used for the sputtering, a magnetron RF sputtering apparatus (SPF210H, manufactured by Anerva Co., Ltd.) or the like is used under a normal argon gas pressure and a normal film forming condition.

  In the above film forming method, first, a zinc sulfide layer is formed using a ZnS sintered body target while maintaining the substrate temperature at 300 to 600 ° C. in an argon gas atmosphere. This ZnS is a material suitable for film formation by sputtering because it has a high sputtering rate and hardly causes a compositional deviation. Here, since the atmosphere during sputtering is an argon gas atmosphere, there is no possibility that sulfur decomposed and generated by argon plasma will contaminate the chamber and the vacuum system as in the case of adding hydrogen sulfide.

  At this time, the substrate is heated to a temperature of 300 to 600 ° C., preferably 350 to 500 ° C. during sputtering. That is, although the ZnS film can be formed at room temperature, when the zinc sulfide film formed at room temperature is heated, ZnS crystal grains are generated and easily detached from the substrate. The detached powder adheres to the substrate and causes pinholes. By holding the substrate in the above temperature range during sputtering, the adhesion between the formed zinc sulfide film and the substrate is improved, and the separation of ZnS crystal grains from the substrate is improved.

  The method for producing the ZnS sintered body target is not particularly limited, and for example, a method of sintering zinc sulfide powder is used. The zinc sulfide powder is not particularly limited, and commercially available powder having a purity of 99.9% by weight or more and an average particle diameter of 3 to 20 μm is used. The sintering method is not particularly limited. For example, zinc sulfide powder is placed in a mold made of carbon or the like and sintered in a hot-pressed atmosphere under an argon gas atmosphere or in a tubular furnace whose atmosphere can be controlled. To do. As said sintering temperature, it is 850-1200 degreeC, Preferably it is 900-1100 degreeC. That is, when the sintering temperature is less than 850 ° C., the sintering does not proceed, so the density of the sintered body is low and the strength of the sintered body is also low, so that it is difficult to handle as a target. On the other hand, when the sintering temperature exceeds 1200 ° C., zinc sulfide is sublimated and a uniform target cannot be obtained.

  Subsequently, a BaAlEu alloy layer is formed on the zinc sulfide layer by sputtering using the BaAlEu alloy target while maintaining the substrate temperature at 400 to 650 ° C. in an argon gas atmosphere. Since this alloy target is a metal target, it can be formed by either direct current or high frequency sputtering, so that it can be formed at high speed. Here, since the atmosphere during sputtering is an argon gas atmosphere, there is no possibility that sulfur decomposed and generated by argon plasma will contaminate the chamber and the vacuum system as in the case of adding hydrogen sulfide.

  At this time, the substrate is heated to a temperature of 400 to 650 ° C. during sputtering. That is, when the temperature of the substrate is lower than 400 ° C., it does not react with the underlying ZnS layer, so that the temperature of the subsequent annealing in hydrogen sulfide needs to be higher than 800 ° C. On the other hand, when the temperature of the substrate exceeds 650 ° C., barium in the BaAlEu alloy layer reacts to form BaS on the ZnS surface side, and vaporization of barium occurs on the other side, which is not preferable because the composition is not uniform. .

The BaAlEu alloy target is represented by a composition formula: Ba _y1 Al _y2 Eu _y3 composed of barium, aluminum, and europium, and _{y1 to y3} in the formula are y1 + y3 = 1, 1.5 ≦ y2 ≦ 3. Those satisfying the requirements of 0, 0.03 ≦ y3 ≦ 0.10 are used.
Here, regarding y2, the requirement of 1.5 ≦ y2 ≦ 3.0 is satisfied. That is, when y2 is less than 1.5, BaAl ₂ S ₄ which is a compound phase desired for the finally obtained phosphor film cannot be obtained. This is because excess aluminum evaporates as aluminum sulfide during annealing or reacts with zinc to become ZnBaAl ₂ S ₅ . However, since ZnBaAl ₂ S ₅ has little influence on the luminance, it is desirable that Al in the BaAlEu alloy layer formed on the ZnS layer has an excessive composition. On the other hand, when y2 exceeds 3.0, the luminance is lowered because the BaAl ₄ S ₇ phase remains in the finally obtained phosphor film.

  The method for producing the BaAlEu alloy target is not particularly limited, and for example, barium, aluminum, and europium are melted in a predetermined amount to be alloyed. Next, it grind | pulverizes and sifts and produces 50-200 micrometers raw material powder. This raw material powder is packed and sintered using a vacuum hot press in an argon gas atmosphere.

  Thereafter, these two layers are annealed in 30 to 90 minutes in hydrogen sulfide of about 0.1 to 1 Pa while maintaining the substrate temperature at 500 to 700 ° C. Thereby, a phosphor film having desirable characteristics is formed. That is, when the substrate temperature is less than 500 ° C., the reaction between the two layers is insufficient and a sulfide film cannot be formed. On the other hand, when the temperature exceeds 700 ° C., the reaction between the two layers does not proceed uniformly, and a trace that is partially burned is formed. Further, considering that zinc is liberated from ZnS and evaporated by reaction between two layers, 550 to 700 ° C. is more preferable.

Hereinafter, the present invention will be described in more detail by way of examples and comparative examples of the present invention, but the present invention is not limited to these examples. The sintered body and film composition used in Examples and Comparative Examples, the structure of the sintered body, and the evaluation method of the fluorescence emission wavelength and fluorescence intensity of the film obtained by sputtering are as follows.
(1) Analysis of composition of sintered body and film: ICP emission analysis was performed.
(2) Identification of the structure of the sintered body: It was carried out by X-ray diffraction (XRD).
(3) Measurement of fluorescence emission wavelength of film: Measurement was carried out with a spectrofluorescence intensity meter (FP-6500ST manufactured by Jusco) to obtain a peak wavelength.
(4) Measurement of the fluorescence intensity of the film: The fluorescence intensity distribution was measured at an excitation wavelength of 350 nm using a spectrofluorescence intensity meter (FP-6500ST manufactured by Jusco), and the peak intensity was determined.

Moreover, the sputtering method of the target used by the Example and the comparative example is as the following [Sputtering method].
[Sputtering method]
The target was attached to the cathode of a magnetron RF sputtering apparatus (manufactured by ULVAC, MB04-1055) to form a film. After pulling to 2 Pa with a rotary pump, the vacuum was further pulled to 2 × 10 ⁻⁵ Pa with a molecular turbo pump. Thereafter, Ar gas was put in and discharged under the conditions of a sputtering pressure of 0.35 Pa and a sputtering power (RF power) of 100 W.
After the attachment, the surface layer was removed by pre-sputtering for about 60 minutes. Further, the substrate was formed such that the thickness of the ZnS layer obtained by using a 2-inch silicon substrate was about 300 nm and the thickness of the BaAlEu alloy layer was about 200 nm.

(Example 1)
(1) Production of sintered compact target (A) First, using ZnS powder (manufactured by Sakai Chemical), this was pulverized with a centrifugal ball mill (manufactured by Fritsch), and then vacuum hot press (manufactured by Daiya Vacuum) was used. And then sintered in argon gas at a temperature of 1050 ° C. Thereafter, the surface of the obtained sintered body was polished by 100 μm, and then a target having a diameter of 2 inches (50 mm) was produced.
(2) Manufacture of sintered compact target (B) Barium (2N made by Kemetal Co., Ltd.), aluminum (4N made by High Purity Chemical Co., Ltd.), and europium (3N made by High Purity Chemical Co., Ltd.) were melted to a predetermined amount and alloyed. Next, it was pulverized by a stamp mill and sieved to prepare a raw material powder of 50 to 200 μm. This raw material powder was packaged and sintered at a temperature of 850 ° C. in an argon gas using a vacuum hot press (manufactured by Daia Vacuum). Thereafter, the surface of the obtained sintered body was polished by 100 μm, and then a target having a diameter of 2 inches (50 mm) was produced. The composition of the target Ba _y1 Al _y2 Eu _y3 as y1 = 0.94, y2 = 2.2, was y3 = 0.06.
(3) Sputtering Using these targets, sputtering was performed according to the above [Sputtering method], a ZnS layer was formed at a substrate temperature of 400 ° C., and then a BaAlEu alloy layer was formed at a substrate temperature of 600 ° C.
(4) Annealing in hydrogen sulfide Using a sputtering apparatus, the substrate temperature is set to 600 ° C., hydrogen sulfide gas is allowed to flow at 0.5 Pa, Ar gas is further added, and gas pressure is 0.8 Pa for 60 minutes to anneal. Created. In addition, sulfur did not adhere in annealing.
Then, according to the said evaluation method, the composition of the obtained film | membrane, the structure | tissue of a film | membrane, and the peak wavelength and peak intensity of fluorescence were calculated | required. The results are shown in Tables 1 and 2 and FIG. FIG. 1 shows the peak wavelength and peak intensity of fluorescence.

(Example 2)
A phosphor film was prepared in the same manner as in Example 1 except that the annealing temperature was 550 ° C. In addition, sulfur did not adhere in annealing. The composition of the obtained film, the film structure, the peak wavelength of fluorescence and the peak intensity of fluorescence were determined. The results are shown in Tables 1 and 2 and FIG.

(Example 3)
A phosphor film was prepared in the same manner as in Example 1 except that the substrate temperature during the formation of the BaAlEu alloy layer was 550 ° C. In addition, sulfur did not adhere in annealing. The composition of the obtained film, the film structure, the peak wavelength of fluorescence and the peak intensity of fluorescence were determined. The results are shown in Tables 1 and 2 and FIG.

Example 4
A phosphor film was formed in the same manner as in Example 1 except that the substrate temperature during the formation of the ZnS layer was 500 ° C. In addition, sulfur did not adhere in annealing. The composition of the obtained film, the film structure, the peak wavelength of fluorescence and the peak intensity of fluorescence were determined. The results are shown in Tables 1 and 2 and FIG.

(Comparative Example 1)
A phosphor film was prepared in the same manner as in Example 1 except that the annealing temperature was set to 700 ° C. The film was discolored in the center and the film was thin. The composition of the obtained film and the structure of the film were determined. The fluorescence was sparse and no uniform fluorescence was observed. The results are shown in Tables 1 and 2.

(Comparative Example 2)
A phosphor film was prepared in the same manner as in Example 1 except that the annealing temperature was 400 ° C. The composition of the obtained film and the structure of the film were determined. In addition, fluorescence was not observed. The results are shown in Tables 1 and 2.

(Comparative Example 3)
A phosphor film was prepared in the same manner as in Example 1 except that the substrate temperature during the formation of the BaAlEu alloy layer was 300 ° C. The composition of the obtained film and the structure of the film were determined. In addition, fluorescence was not observed. The results are shown in Tables 1 and 2.

(Comparative Example 4)
A phosphor film was formed in the same manner as in Example 1 except that the substrate temperature during the formation of the BaAlEu alloy layer was set to 700 ° C. The composition of the obtained film, the film structure, the peak wavelength of fluorescence and the peak intensity of fluorescence were determined. The results are shown in Tables 1 and 2 and FIG.

(Comparative Example 5)
A phosphor film was formed in the same manner as in Example 1 except that the substrate temperature during the formation of the ZnS layer was 100 ° C. The analysis was not possible because the film was partially peeled off.

(Comparative Example 6)
A phosphor film was formed in the same manner as in Example 1 except that the substrate temperature at the time of forming the ZnS layer was 650 ° C. The composition of the obtained film and the structure of the film were determined. In addition, fluorescence was not observed. The results are shown in Tables 1 and 2.

From Tables 1 and 2, in Examples 1 to 4, the film was formed according to the method of the present invention under film forming conditions such as target, atmosphere, and substrate temperature and annealing conditions, and the compound structure of the formed film was BaAl ₂ S ₄ phase. In addition, since the composition of the film satisfies the conditions of the present invention, it can be seen that the shift of the fluorescence emission wavelength to a long wavelength is small and the emission intensity is high. Thereby, a phosphor thin film with good color purity and high brightness is achieved.

  On the other hand, in Comparative Examples 1 to 6, since the substrate temperature during film formation or annealing was not performed according to the conditions of the present invention, satisfactory results could not be obtained in the film composition or compound structure. I understand. Therefore, even if the fluorescence was observed, it was weak.

(Comparative Example 7)
Using a BaAlEu target having the same composition as in Example 1, the substrate temperature was set to 600 ° C., hydrogen sulfide gas was allowed to flow at 0.5 Pa, and Ar gas was added to form a film at a gas pressure of 0.8 Pa and an RF power of 100 W. . As a result, the film formation rate was as low as 22% compared to Example 1.
In addition, since hydrogen sulfide is decomposed by plasma, the ion gauge for measuring the vacuum cannot be turned on immediately after film formation, and there is a problem in maintenance such as sulfur adhering to the exhaust pipe when sputtering is performed for 2 hours. . That is, in the conventional sputtering method in hydrogen sulfide gas, troubles due to sulfur occurred and the film formation rate was low.

  As is clear from the above, the phosphor film of the present invention and the film formation method thereof are suitable for inorganic EL and PDP, and have a good color purity and a high brightness phosphor thin film and its film formation method.

It is a figure showing the peak wavelength and peak intensity of fluorescence.

Claims (3)

The following composition formula consisting of zinc, barium, aluminum, sulfur and europium:
Zn _x0 Ba _x1 Al _x2 S _x3 Eu _x4
(In the formula, x0 to x4 satisfy the requirements shown in the following (1) to (5).)
A phosphor thin film formed from a sulfide represented by:
The phosphor structure is composed of a compound phase represented by a composition formula: BaAl ₂ S ₄ : Eu.
(1) 0.005 ≦ x0 ≦ 0.3
(2) x1 + x4 = 1
(3) 2.01 ≦ x2 ≦ 3.0
(4) 4.0 <x3 ≦ 4.3
(5) 0.03 ≦ x4 ≦ 0.10 Using the following sintered body target (A), a zinc sulfide layer was formed while maintaining the substrate temperature at 300 to 600 ° C. in an argon gas atmosphere, and then the following alloy was formed on the zinc sulfide layer. Using the target (B), a BaAlEu alloy layer was formed by sputtering while maintaining the substrate temperature at 400 to 650 ° C. in an argon gas atmosphere. 2. The method for forming a phosphor thin film according to claim 1, wherein annealing is performed in the film.
(A) It is comprised from zinc sulfide.
(B) barium, aluminum, and the composition formula consists europium: Ba _y1 Al _y2 Eu _y3 (In the formula, Y1 to Y3 are, y1 + y3 = 1,1.5 ≦ y2 ≦ 3.0,0.03 ≦ y3 ≦ 0.10 is satisfied.).   3. The method for forming a phosphor thin film according to claim 2, wherein the annealing is held in hydrogen sulfide at a gas pressure of 0.1 to 1 Pa for 30 to 90 minutes.

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