JPH059003A - Method for producing perovskite type complex oxide thin film - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a target from a material that is a precursor of a perovskite complex oxide or a mixture thereof without passing through complicated steps of sintering, pulverizing and sintering. Another object of the present invention is to provide a method for directly producing a perovskite type complex oxide thin film on a base material. [Structure] A precursor of perovskite type complex oxide, for example, barium bis (oxalic acid) titanium (IV) oxide, which is one of the precursors of barium titanate, is directly barium titanate on a substrate by thermal plasma spraying. Form a thin film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a perovskite type complex oxide thin film. More specifically, the present invention relates to a method for producing a perovskite-type complex oxide thin film having excellent characteristics as a ferroelectric thin film such as a capacitor, a piezoelectric thin film, or a protective film for a solid resistor.

[0002]

2. Description of the Related Art Conventionally, perovskite type complex oxide thin films used for ferroelectric thin films and the like are sintered and crushed from materials such as precursors obtained by solid phase method and coprecipitation method. There is known a method in which a raw material of a perovskite type complex oxide powder is obtained through the above, and further, a binder is mixed and then a green sheet is formed by a wet method, and the thin film is formed by sintering, and an electrode and the like are added to produce the thin film. These manufacturing methods require a large amount of energy when sintering the material such as the precursor and the raw material, and there is a possibility that impurities may be mixed in at the time of crushing after the sintering and crystal strain due to physical force occurs. There are various problems such as possibility. Further, in the case of the above method, the production cost of a material such as a precursor to be produced is also problematic, and in general, except for the metal compound represented by the present invention, the production cost of an organometallic compound such as a chelate compound is low. It has become relatively high and much research has been done at the laboratory level, but it has not yet been industrialized.

On the other hand, a hydrothermal synthesis method and a sol-gel method for obtaining a perovskite type composite oxide powder without a sintering and crushing process were also devised, and using this as a material, a perovskite type composite oxide thin film was formed as described above. Methods of manufacturing are also known. However, the production of the perovskite-type composite oxide powder by the hydrothermal synthesis method involves a process that requires reaction conditions of approximately several tens of atmospheric pressure and 200 ° C. or more, which complicates the apparatus and the latter sol. In the method of producing a perovskite-type composite oxide powder by the gel method, since each constituent element needs to be an alkoxide, the production method is not easy and expensive.

When a perovskite type complex oxide thin film is produced by a sintering method, a process of once obtaining a perovskite type complex oxide powder by various methods, mixing a binder, molding, sintering, and further adding an electrode and the like. Therefore, the manufacturing process is complicated and the cost is high.

[0005]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention The present inventors have found the drawbacks in the conventional perovskite type complex oxide thin film production,
That is, in order to overcome the drawbacks that a large amount of energy is required for sintering and crushing, the apparatus and handling become complicated, and the cost becomes high, as a result of diligent studies, it is a known method in multiple steps. Using the plasma spray method, perovskite-type complex oxides such as ferroelectrics can be obtained without the complicated steps of sintering and crushing materials such as precursors or a mixture thereof, further sintering, and adding electrodes. It has been found that a thin film can be directly produced on a substrate such as an electrode and continuously.

Examples of the base material used as the target include various phenol base materials, glass epoxy base materials, ceramic base materials, solid-state resistors, and the like. When the perovskite type complex oxide thin film is manufactured, the base material temperature rise is suppressed. Therefore, by spraying a non-combustible material for cooling the base material onto the front surface or the back surface of the base material toward the base material, the temperature of the base material can be suppressed as low as around 100 ° C. Perovskite-type composite oxide thin films can be produced even on inferior paper phenolic substrates.

The present inventors have completed the present invention as a result of further studies based on the above findings.

[0008]

Means for Solving the Problems That is, the present invention is directed to a target substrate by thermal plasmas from a material that is a precursor of a substance represented by the following general formula (1) or a mixture thereof. The present invention provides a method for producing a perovskite-type composite oxide thin film, which comprises spraying onto a perovskite-type composite oxide thin film. General formula (1) ABO ₃

In the present invention, the above-mentioned A element is, for example, Cu, Mg, Ca, Sr, Ba, Zn, Cd, Sc,
Y, La, Ce, Pr, Nd, Sm, Eu, Gd, T
b, Dy, Ho, Er, Tm, Yb, Lu, Pb, B
Examples thereof include i, Fe, Co and Ni, and more preferable examples include Mg, Ca, Sr, Ba and Pb, but the present invention is not limited thereto. . Examples of the B element include Ti, Zr, Hf, Sn, and S.
b etc. can be mentioned.

It is a precursor of a metal compound having at least one element selected from the element A and at least one element selected from the element B, that is, a precursor of a perovskite type complex oxide. Any of a metal compound having two or more kinds of metal elements such as a hydrate, an inorganic acid salt, an ammonium salt and an organic acid salt, or a mixture of at least two kinds of metal compounds having one kind of metal element may be used, but it is preferable. Is a hydroxide as a hydrate,
Oxyhydroxide, nitrate, carbonate, phosphate, sulfate as inorganic acid salt, formate, oxalate, acetate, propionate, succinate, malate, tartaric acid as organic acid salt Salt, citrate, adipate, mutinate, benzoate, salicylate, phthalate, isophthalate, terephthalate, trimellitate, sebacate, pyromellitoate or stearate Examples thereof include, but are not limited to, oxalate, citrate, and tartrate. . However, the metal elements in the present invention include Group IB, Group IIA, and Group IIB of the Periodic Table of Elements.
Group IIIA, group IIIA, group IVA, group IVB, group VB, group VIII.

As an example of a metal compound having two kinds of metal elements such as a precursor of a perovskite type complex oxide, bis (oxalic acid) titanium (IV) oxide barium, bis (oxalic acid) titanium (IV) oxide are exemplified. Strontium, magnesium bis (oxalate) titanium oxide (IV), bis (oxalic acid) titanium oxide (IV) calcium, titanium citrate (IV) barium, titanium citrate (IV) strontium, titanium citrate (IV) ) Calcium, titanium (IV) oxide citrate, titanium (IV) tartrate barium oxide, strontium (IV) titanium oxide tartrate, titanium (IV) tartrate calcium oxide, titanium (IV) tartrate magnesium oxide, etc. , But is not limited to this.

Examples of the respective metal compounds include barium oxalate, strontium oxalate, calcium oxalate, magnesium oxalate, barium hydroxide, strontium hydroxide, calcium hydroxide, magnesium hydroxide, potassium oxalate titanate, and oxalic acid. Examples thereof include, but are not limited to, tin and zirconium nitrate.

The above-mentioned metal compound having two or more kinds of metal elements, that is, a metal compound which is a precursor of a perovskite type complex oxide, is a compound composed of an element capable of substituting the element A or the element B during the preparation of the metal compound. For example, a metal compound in which a part of the metal compound is substituted by adding an oxide or the like may be used, and the metal compound may be prepared by previously mixing mixed acids such as oxalic acid and citric acid. Further, various metal oxides or glass may be added to and mixed with the metal compound. In the case of this addition and blending, various metal oxides or glass may be added at the time of preparing the above-mentioned metal compound and mixed in the metal compound.

A perovskite type composite comprising a metal compound having at least one element selected from the element A and one or more elements selected from the element B, or a mixture of metal compounds of the respective elements. A material such as an oxide precursor is introduced into thermal plasma and sprayed onto a target substrate to give a perovskite-type composite having high crystallinity represented by the following general formula (1). An oxide thin film can be obtained. General formula (1) ABO ₃

The thermal plasma source used is preferably high-frequency induction plasma, microwave induction plasma or DC arc plasma, but is not limited to this.

[0016]

When the thin film is formed on the base material using the perovskite-type complex oxide powder as the feed material for the thermal plasma spray to produce the perovskite-type complex oxide thin film, structural change or vitrification is caused in the thermal plasma. The perovskite type complex oxide thin film having high crystallinity and good dielectric properties cannot be obtained as a result of the simultaneous occurrence of the supply of the raw material to the.

However, as a feedstock for the thermal plasma spray as in the present invention, metal compounds such as hydrates, inorganic acid salts, ammonium salts and organic acid salts which are precursors of perovskite type complex oxides, such as water. Oxide, oxyhydroxide, nitrate, carbonate, phosphate, sulfate, formate, oxalate, acetate, propionate, succinate, malate, tartrate, citrate, adipine Acid salts, mucin salts, benzoates, salicylates, phthalates, isophthalates, terephthalates, trimellitates, sebacates, pyromellites, stearates, etc. or mixtures thereof If you do,
When ultra-high temperature is applied in thermal plasma, the thermal decomposition reaction of the metal compound and the decomposition or vitrification reaction of the perovskite type complex oxide generated by thermal decomposition occur before and after, but the thermal decomposition reaction of the metal compound The perovskite-type complex oxide that is being generated is protected from the ultra-high temperature due to thermal plasma due to the decomposition of the metal compound itself, so that decomposition that causes a structural change is suppressed, and the crystallinity and dielectric properties are suppressed. It is presumed that a thin film with good characteristics will be produced.

[0018]

According to the present invention, a perovskite type complex oxide thin film having a good dielectric property comparable to that obtained by a conventional method such as a sintering step is directly and continuously formed on a target substrate. Can be manufactured in a simple manner. Furthermore, by using a spray of non-combustible material for cooling the substrate,
Since the temperature rise of the base material during thermal spraying can be suppressed to a low level, the thin film can be formed directly not only on a ceramic base material but also on a glass epoxy or various phenolic printed circuit board that is inferior in heat resistance. It is also possible. This can contribute to labor saving and energy saving in the field of manufacturing capacitors and the like and manufacturing solid-state resistors using a ferroelectric thin film as a protective film.

Therefore, according to the present invention, it is possible to directly and continuously produce a perovskite type complex oxide thin film from a material which is a precursor of a perovskite type complex oxide using a thermal plasma spray apparatus. What has come to be done is to provide a thin film with a simple process and at a low cost, and its effect is extremely large.

[0020]

EXAMPLES The present invention will be specifically described with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

Examples 1 to 2 300 g of pure water was charged into a 1 liter flask equipped with a stirrer and a dropper, and 150 g of titanium tetrachloride was added dropwise over 1 hour while stirring well while maintaining the temperature at 30 to 35 ° C. After that, stirring was continued for 30 minutes. The solution in the flask was charged with 320 g of oxalic acid which had been charged in advance and pure water 680.
It was added to a 5 liter flask kept at 65 ° C. over 1 hour. After the dropping, a solution prepared by dissolving 215 g of barium chloride in 450 g of pure water in advance was dropped into the flask over 1 hour to form a precipitate.

A precipitate of barium bis (oxalic acid) titanium (IV) oxide produced by the reaction was separated by filtration, washed, and dried in vacuum to obtain a barium titanate precursor material. Further sieving was performed to obtain powder having a particle size of 63 to 90 μm.

Next, a thermal plasma is generated, and the powder sieved previously is supplied to this thermal plasma flame at 5 to 10 g / min to form a perovskite-type composite on a copper plate serving as an electrode of 20 mm × 20 mm × 0.5 mm. A thin film of barium titanate, which is an oxide, was formed. The dielectric constant of this barium titanate thin film was measured in the shape of FIG. 2 and listed in Table 1. Table 1 shows the conditions for generating thermal plasma when the method was carried out. A comparison between the X-ray diffraction pattern of the thin film and the standard diffraction peak position pattern in the JCPDS database is shown in FIG.

Example 3 A commercially available barium titanate powder manufactured by Yamanaka Semiconductor was purchased, sieved to a particle size of 25 to 53 μm, and a barium titanate thin film was formed by thermal plasma spraying as described above. The thermal plasma generation conditions are shown in Table 1, and the X-ray diffraction pattern of the thin film is shown in FIG.

The characteristics of the perovskite type complex oxide thin films in Examples 1 to 3 were measured by the following methods.

1. Dielectric constant YHP company IMPE DANCE-GAIN PHASE
Using ANALYZER 4194A, frequency 1kHz
The dielectric constant was calculated from the electrostatic capacity at z.

2. Identification of thin film The X-ray diffraction experimental apparatus JDX-8030 manufactured by JEOL Ltd. was used to obtain the diffraction pattern between 2θ = 10 to 90 degrees, and compared with the standard diffraction peak position in the JCPDS database to identify the thin film. I did.

[0028]

[Table 1]

[0029]

[Brief description of drawings]

FIG. 1 is an X-ray diffraction pattern.

[Figure 1]

FIG. 2 is an outline drawing of a sample for measuring the dielectric constant.

[Fig. 2]

[0031]

[Explanation of symbols]

1. Copper plate electrode 2. Perovskite type complex oxide thin film 3. Lead

Continued front page    (72) Inventor Yusuke Mitsuyoshi             2-3-13, Kyobashi, Chuo-ku, Tokyo Toyo             Nki Manufacturing Co., Ltd.

Claims (6)

[Claims] 1. (I) At least one kind of metal compound having two or more kinds of metal elements, (II) At least one kind of metal compound having one kind of metal element, (I) and / or (II) ( However, in the case of only (II), a perovskite-type composite oxide is characterized in that a perovskite-type composite oxide film is formed by directly spraying a mixture of two or more kinds of metal elements) on a substrate by thermal plasma. Method for manufacturing thin film. 2. In the perovskite type complex oxide represented by the general formula (1), the metal element A is a group IB, group IIA, group IIB, group IIIA or group IVB of the periodic table of the elements. , First
At least one selected from Group VB and Group VIII, and the metal element of B is Group IVA or Group IVB of the Periodic Table of Elements.
The method for producing a perovskite-type complex oxide thin film according to claim 1, wherein at least one kind selected from Group VB and Group VB is used. General formula (1) ABO ₃ 3. In the general formula (1), the metal element A is at least one selected from Group IIA and Group IVB of the Periodic Table of Elements, and the metal element B is the group of the Periodic Table of Elements. The method for producing a perovskite complex oxide thin film according to claim 1, wherein at least one selected from the group consisting of IVA, IVB, and VB is used. 4. The method for producing a perovskite complex oxide thin film according to claim 1, wherein the metal compound is a hydrate, an inorganic acid salt, an ammonium salt or an organic acid salt. 5. The metal compound is hydroxide, oxyhydroxide, nitrate, carbonate, phosphate, sulfate, formate, oxalate, acetate, propionate, succinate, malic acid. Salt, tartrate, citrate, adipate, mutinate, benzoate, salicylate, phthalate, isophthalate, terephthalate, trimellitate, sebacate, pyromellitate or The method for producing a perovskite-type complex oxide thin film according to any one of claims 1 to 3, which is a stearate. 6. The method for producing a perovskite type complex oxide thin film according to claim 1, wherein high frequency induction plasma, microwave induction plasma or direct current arc plasma is used as the thermal plasma source.