JP2008121091A - Sputtering target for depositing fluorescent film for electroluminescent element, causing little generation of particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sputtering target for depositing a fluorescent film for an electroluminescent element, the sputtering target causing little generation of particles during sputtering. <P>SOLUTION: The target has a composition comprising, by mass, 20 to 50% Al, 1 to 10% Eu and ≤1.5% oxygen, and the balance Ba with inevitable impurities, and has a structure composed of intermetallic compound phases of Ba and Al in which Eu is solid-soluted. The intermetallic compound phases of Ba and Al in which Eu is solid-soluted are composed of a BaAl<SB>4</SB>intermetallic compound phase and a Ba<SB>7</SB>Al<SB>13</SB>intermetallic compound phase, wherein Eu is solid-soluted in Ba in the BaAl<SB>4</SB>intermetallic compound and the Ba<SB>7</SB>Al<SB>13</SB>intermetallic compound, respectively. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to a sputtering target for forming a phosphor film constituting an electroluminescence element used for displays of various electronic devices and information devices by sputtering, and in particular, a europium-added barium thioaluminate phosphor film. The present invention relates to a sputtering target for forming a phosphor film in an electroluminescence device with less generation of particles when (BaAl ₂ S ₄ : Eu) is formed by a reactive sputtering method performed in an atmosphere containing H ₂ S gas. .

In recent years, electroluminescence elements have been used for displays of various electronic devices and information devices, and phosphor films have been used for the electroluminescence elements. In general, an electroluminescent element is formed by forming a lower transparent electrode on a glass substrate, forming a first insulating film on the lower transparent electrode, and forming a phosphor film on the first insulating film. A second insulating film is formed on the film so that the phosphor film is surrounded by the second insulating film and the first insulating film, and an upper electrode is formed on the second insulating film. This structure is well known.
As one of the phosphor films used in this electroluminescence element, a europium-doped barium thioaluminate phosphor film (BaAl ₂ S ₄ : Eu) is known. This europium-added barium thioaluminate phosphor film has a matrix component made of barium thioaluminate (BaAl ₂ S ₄ ) and an impurity that becomes a light emission center made of europium (Eu). The phosphor film is formed by first forming an amorphous phase thin film by a dual pulse electron beam evaporation method using a BaS pellet to which Al ₂ S ₃ pellet and EuF ₃ are added as an evaporation source, and then performing a heat treatment in an annealing furnace. It is made by making it. However, according to this method, the phosphor film needs to be heat-treated in the final step, and since this heat treatment needs to be heated to a high temperature of 900 ° C. or higher, it adversely affects the electrodes and insulating layers constituting the electroluminescent element. Therefore, it was difficult to obtain barium thioaluminate added with fully crystallized Eu.
Recently, triethylaluminum (Al (C ₂ H ₅ ) ₃ ), trimethylaluminum (Al (CH ₃ ) ₃ ) or triisobutylaluminum (Al (i-C ₄ H ₉ ) ₃ ) organometallic material, metal By using one of barium (Ba), metal europium (Eu), europium chloride (EuCl ₃ ), and europium fluoride (EuF ₃ ) and hydrogen sulfide (H ₂ S) as raw materials, an electron beam (EB) deposition method is used. A method for producing a europium-added barium thioaluminate phosphor film has been developed and proposed (see Patent Document 1). Furthermore, although there is no description of the europium-added barium thioaluminate phosphor film (BaAl ₂ S ₄ : Eu) itself, it is generally known that a phosphor film in an electroluminescence element is formed by a multi-source sputtering method (patent) References 2 and 3).
JP 2001-297877 A JP 2001-118677 A JP-A-8-138867

  In recent years, displays have become increasingly larger, and therefore, the electroluminescent elements used in these large displays have also become larger. However, in order to produce a large area europium-doped barium thioaluminate phosphor film by the above-described deposition method. In recent years, it is more advantageous to form a thin film with a larger area by sputtering rather than vapor deposition. Therefore, in recent years, a large area of europium-doped barium thiol used for large electroluminescence devices has been used. Studies have been made on producing aluminate phosphor films by multi-source sputtering.

However, when a europium-added barium thioaluminate phosphor film is manufactured by a multi-source sputtering method, a large target made of Ba, Al, and Eu elements is sputtered to simultaneously sputter Ba, Al, and Eu elements. Therefore, the sputtering apparatus must be enlarged.
Therefore, each element powder of Ba, Al, and Eu is blended so that it contains Al: 20 to 50% by mass and Eu: 1 to 10% by mass determined from the film characteristics, and the balance is composed of Ba. A mixed powder is prepared by mixing, press-molding the mixed powder, a target is prepared by sintering or hot pressing in vacuum, and europium-added barium is sputtered in a hydrogen sulfide atmosphere using the target. Studies have been made to form a thioaluminate phosphor film (BaAl ₂ S ₄ : Eu).
However, when the europium-added barium thioaluminate phosphor film is formed by sputtering in a hydrogen sulfide atmosphere using a target having this component composition, there is a drawback that abnormal discharge is likely to occur during sputtering, and thus particles are likely to be generated. there were.

Accordingly, the present inventors have studied to develop a sputtering target for forming a phosphor film in an electroluminescence element that generates less particles during sputtering. as a result,
(A) Oxygen contained in the sputtering target for forming the phosphor film greatly affects the generation of particles during sputtering, so that the generation of particles during sputtering can be reduced by sputtering for forming the phosphor film. It is preferable to reduce oxygen contained in the target as much as possible, and oxygen contained in the sputtering target for forming the phosphor film is preferably 1.5% by mass or less,
(B) In order to reduce the oxygen contained in the sputtering target for forming the phosphor film to 1.5% by mass or less, an ingot is produced by melting and casting in an inert gas, and the ingot is made into the inert gas. The component of the sputtering target for forming the phosphor film obtained in this way can be achieved by pulverizing in to produce an alloy powder and filling this graphite powder into a graphite mold in an inert gas atmosphere. The composition contains Al: 20 to 50% by mass, Eu: 1 to 10% by mass, oxygen: 1.5% by mass or less, with the balance being composed of Ba and inevitable impurities,
(C) The sputtering target with less generation of particles for forming the phosphor film is composed of a structure having an intermetallic compound phase of Ba and Al in which Eu is dissolved, and the metal of Ba and Al in which Eu is dissolved. The intermetallic phase is composed of an intermetallic compound phase in which Eu is solid-dissolved in Ba of the BaAl ₄ intermetallic compound and an intermetallic compound phase in which Eu is solid-solved in Ba of the Ba ₇ Al ₁₃ intermetallic compound. The research results were obtained.

The present invention has been made based on such research results,
(1) Al: 20 to 50% by mass, Eu: 1 to 10% by mass, oxygen: 1.5% by mass or less, the balance of Ba and inevitable impurities, and Ba and Al in which Eu is dissolved A sputtering target with less generation of particles for forming a phosphor film in an electroluminescence device composed of a structure having an intermetallic compound phase of
(2) The intermetallic compound phase of Ba and Al in which Eu is solid-solved includes the intermetallic compound phase in which Eu is solid-solved in Ba in the BaAl ₄ intermetallic compound and the Eu in Ba in the Ba ₇ Al ₁₃ intermetallic compound. This is characterized by a sputtering target with less generation of particles for forming a phosphor film in the electroluminescence device according to (1), which comprises an intermetallic compound phase in which is dissolved.

  In order to produce a sputtering target with less generation of particles for forming the phosphor film of the present invention, first, as a raw material, metal Ba, metal Al and metal Eu are prepared, and these raw materials are charged into an alumina crucible, Melting in an inert gas atmosphere such as Ar using a high-frequency vacuum melting furnace, casting the resulting molten metal in a mold in an inert gas atmosphere to produce an ingot, and placing the resulting ingot in a high-purity argon gas blow To prepare a powder having a particle size of 500 μm or less by pulverizing with, and filling this powder in an inert gas into a graphite mold, and then maintaining the temperature at 500 to 800 ° C. and pressure: 10 to 50 MPa for 1 to 8 hours A hot-pressed body was produced by performing hot pressing, and the fluorescence in the electroluminescence device was cut by cutting the hot-pressed body. It can be manufactured particles less sputtering target of occurrence for forming a film. The oxygen content contained in the sputtering target with less generation of particles for forming the phosphor film thus obtained is preferably as low as possible, and is 1.5% by mass or less (more preferably 1.0%). It is preferable to be less than 0.2% by mass, but it is not impossible to reduce it to less than 0.2% by mass, but it is expensive.

  When a phosphor film in a wide area electroluminescent device is formed by sputtering, the generation of particles can be suppressed, which can greatly contribute to the development of the display industry.

Example 1
Metal Al, metal Ba, and metal Eu are prepared as raw materials. These raw materials are blended and mixed in the proportions shown in Table 1 and charged into an alumina crucible, which is displayed in a high-purity Ar gas atmosphere using a high-frequency vacuum melting furnace. After melting at the temperature shown in 1 and maintaining the obtained molten metal at the casting temperature shown in Table 1, the ingot was produced by casting into a mold in a high purity Ar gas atmosphere. The powder was pulverized in an argon gas blow to prepare a powder having an average particle size of 70 μm, and this powder was filled into a graphite mold in the atmosphere shown in Table 1, and the temperature was 650 ° C. and the pressure was 40 MPa in an Ar gas atmosphere. The hot-press body of the present invention having the component composition shown in Table 2 by hot pressing under conditions of holding for 2 hours and having a diameter: 150 mm and thickness: 6 mm To prepare Tsu bets 1-5, these from the present invention hot-pressed body target 1-5 cut blocks subjected to X-ray diffraction, and the results are shown in Table 2. The oxygen content was measured by an infrared absorption method.

  Next, the number of particles having a size of 0.5 μm or more generated during sputtering using the hot press body targets 1 to 5 of the present invention and sputtering under the following conditions and adhering on the substrate using a particle counter. The results are shown in Table 2.

Conventional Example 1
Prepare Al powder, Ba powder and Eu powder as raw materials, mix and mix these raw materials in the proportions shown in Table 1, and charge them in an alumina crucible. 1 is melted at the temperature shown in FIG. 1, and the obtained molten metal is held at the casting temperature shown in Table 1 and then cast into a mold to produce an ingot. : 70 μm raw material powder was prepared, and these raw material powders were filled in a graphite mold in the atmosphere shown in Table 1, and subjected to hot pressing under conditions of holding at a temperature of 650 ° C. and a pressure of 40 MPa for 2 hours. The conventional hot press body targets 1 to 5 having the component composition shown in FIG. The X-ray diffraction was performed by cutting out, and the results are shown in Table 2.

  Next, using the hot-pressed body targets 1 to 5 of the present invention and the conventional hot-pressed body targets 1 to 5, using a DC magnetron sputtering apparatus, sputtering was performed under the following conditions, and adhered to the substrate using a particle counter. The number of particles having a size of 0.5 μm or more was measured, and the results are shown in Table 2.

Sputtering conditions:
Sputtering gas: Ar gas and H ₂ S mixed gas (mixed gas flow rate: 50 sccm),
Mixed gas pressure: 0.67 Pa (including H ₂ S partial pressure: 0.2 Pa)
Sputtering power: 400W (DC)
Substrate size: 125mm diameter
The distance between the target and the substrate: 70 mm,
Sputtering time: 1 minute

From the results shown in Tables 1 and 2, Al: 20 to 50% by mass, Eu: 1 to 10% by mass, oxygen: 1.5% by mass or less, the balance being Ba and inevitable impurities, and Ba The hot press target 1 to 5 of the present invention, which has a structure having a BaA1 ₄ intermetallic compound in which Eu is solid-dissolved in Eu and a Ba ₇ Al ₁₃ intermetallic compound phase in which Eu is solid-dissolved in Ba, has a conventional oxygen richer content. It can be seen that the number of particles generated during sputtering is smaller than that of the hot press target 1 to 5.

Claims (2)

Al: 20 to 50% by mass, Eu: 1 to 10% by mass, oxygen: 1.5% by mass or less, with the balance being composed of Ba and inevitable impurities, and between Ba and Al metal in which Eu is dissolved A sputtering target with less generation of particles for forming a phosphor film in an electroluminescence device, comprising a structure having a compound phase. The intermetallic compound phase of Ba and Al in which Eu is solid-solved is composed of an intermetallic compound phase in which Eu is solid-solved in Ba in the BaA1 ₄ intermetallic compound and Eu is in solid solution in Ba in the Ba ₇ Al ₁₃ intermetallic compound. 2. A sputtering target with less generation of particles for forming a phosphor film in an electroluminescence device according to claim 1, wherein the sputtering target comprises an intermetallic compound phase.