JPH0641373B2 - Method for producing raw material powder of perovskite and its solid solution - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a method for producing a raw material powder of easily sinterable perovskite and its solid solution by combining a wet method and a dry method, and particularly for reducing malfunction of a semiconductor. The present invention relates to a method for producing a raw material powder of perovskite and a solid solution thereof which can be used as a filler for low melting point glass suitable as a sealing agent for semiconductor devices.

<Prior Art> Perovskites and solid solutions thereof (both are referred to as perovskite solid solutions for convenience hereinafter) are widely used as functional ceramics such as piezoelectric materials, optoelectronic materials, dielectric materials, semiconductors, and sensors.

By the way, a dry method and a wet method are known as a method for producing a raw material powder of a perovskite solid solution.

The dry method is a method in which the compounds of the constituent raw material components are dry mixed and calcined.

On the other hand, the wet method is a method in which a mixed solution of all constituent raw materials is prepared, added to a precipitation forming solution to coprecipitate, and the coprecipitate is dried and calcined (hereinafter referred to as coprecipitation method).

It is known that a semiconductor sometimes malfunctions. For example, a low melting point glass is used as a sealing material for hermetically sealing a semiconductor device. There is a phenomenon that causes a malfunction of the property, and radioactive α particles generated from the semiconductor device have been pointed out as the cause thereof, and various studies have been made to prevent such α particles from entering the semiconductor device.

For example, in JP-A-59-169955, in order to reduce the occurrence of memory error, the content of radioisotope as a non-devitrifying low melting point glass powder is set to less than 20 ppb and the count number of radioactive α particles is 0.1 CPH / cm. ^{2 and} below.

<Problems to be Solved by the Invention> As described above, the dry method and coprecipitation are known as the production methods of the perovskite raw material powder, but the former is difficult to obtain a raw material powder having a uniform composition, and the sinterability is also high. It had the drawback of not being enough. On the other hand, the latter has a drawback in that raw material powder having excellent uniformity can be obtained, but particles of the particles coagulate to form secondary particles, which makes it difficult to easily sinter. Further, the coprecipitation method has a drawback that it is difficult to obtain a raw material powder having a desired composition due to the difference in the precipitation forming ability of each component because the concentration of the precipitation forming liquid is constant. Furthermore, lead is used as the A component in the perovskite solid solution,
Very many components simultaneously contain titanium as the B component, and in the case of industrially producing such a component, it is desirable to use inexpensive titanium tetrachloride as the titanium compound. However, when this was used in the coprecipitation method, titanium ions could not be used because chlorine ions in titanium tetrachloride react with lead ions to form a white precipitate. Therefore, it is necessary to use expensive titanium oxynitrate or the like instead of titanium tetrachloride, which is not practical for industrial production.

Further, as described above, as a sealing material for a semiconductor device, in a low melting point glass consisting of a non-devitrifying low melting point glass powder and a filler, a non-devitrifying low melting point glass for preventing an adverse effect due to a conventional radioisotope. A method to reduce the count of radioactive α particles per powder to 0.1 CPH / cm ² or less has been developed, but no filler has been studied and it is possible to completely prevent the occurrence of memory errors in semiconductor devices. There wasn't.

The present invention has been made in view of the above circumstances, and solved the drawbacks of the prior art, easy sintering, uniformity, high bulk density, raw powder of a perovskite solid solution satisfying the four requirements of low cost The present invention provides a method for manufacturing the same. INDUSTRIAL APPLICABILITY The present invention is particularly suitable for producing a raw material powder applied to a semiconductor or a device thereof, for example, a raw material powder of a perovskite solid solution which can be used as a filler for a low melting point glass suitable as a sealing agent for a semiconductor device.

<Means for Solving Problems> That is, the present invention provides a compound represented by the general formula ABO ₃ (where A is one or more oxygen 12-coordinated metal elements, and B is one oxygen 6-coordinated metal element or 2 In the method for producing a raw material powder of a perovskite solid solution, which represents at least one kind and the sum of the numbers of the A component and the B component is 3 or more.), At least one of the A component and the B component (hereinafter referred to as X for convenience). The remaining aqueous solution or alcoholic solution of the component compounds except for the components) is precipitated by a precipitation forming liquid, and the obtained precipitate is heated at 120 to 1200 ° C.
The radioactive α particles are counted at 0.1 CPH / c, which is characterized in that it is dried and calcined at 40 ° C., then the above-mentioned component, that is, the component X compound is mixed, and then calcined at 400 to 1200 ° C.
The present invention relates to a method for producing a raw material powder of a perovskite solid solution having a size of m ² or less.

In the present invention, examples of the oxygen-12-coordinated metal element which is the component A of the general formula include rare earth elements such as Pb, Ba, Ca, Sr and La. Examples of the oxygen hexacoordinated metal element that is the B component include, for example, Ti, Zr, Mg, Sc, Hf, W, Nb, Ta, Cr, Mo, and M.
Examples include n, Fe, Co, Ni, Zn, Cd, Al, Sn, As and Bi.

Examples of the compound for preparing a water or alcohol solution of the compounds of the components A and B, which are the components of the perovskite solid solution, include the oxides, hydroxides, carbonates, nitrates, acetates of the components A and B, Examples thereof include formates, oxalates, metals, and the like, but are not limited to these.

Further, the compound of the component X has a large difference in precipitation forming ability from the compounds of the other constituents, or is an aqueous solution or alcohol, and when mixed with other constituents,
It is desirable to select a substance that causes precipitation or a substance that reacts with an aqueous solution or alcohol solution of a compound of other constituents.

In many cases, it is preferable that the compound of the component X is an oxide, but it may be the above-mentioned salts, and if the component X is two or more, it may be a coprecipitate thereof or a calcined product thereof. .

In the present invention, since the count number of radioactive α particles generated from radioisotopes such as U and Th in the raw material powder of the obtained perovskite solid solution is set to 0.1 CPH / cm ² or less, radioisotopes as unavoidable impurities are used. The components A and B containing the element are dissolved in highly pure concentrated nitric acid, and U,
Radioactive isotopes such as Th are used as complex anions, and the concentration of free nitric acid is adjusted to 5 to 10 mol with pure water or alcohol (radioactive isotope adsorption efficiency is good in this concentration range), and then anion exchange is performed. It is desirable to use an aqueous solution or alcohol solution which has been subjected to cleaning treatment with a resin and has adsorbed and removed radioisotopes such as U and Th.

When the X component contains the above-mentioned radioisotope, it is preferable to use a solution obtained by adding the purified solution to the precipitation-forming solution, allowing the precipitate to dry, and then calcining it if necessary. Of course, titanium tetrachloride and the like may be purified by distillation, and the radioisotope in the component A and component B compounds may be removed by other known means.

In the present invention, the precipitation-forming liquid may be an aqueous solution or an alcohol solution of ammonia, ammonium carbonate, caustic alkali, oxalic acid, ammonium oxalate, amines or the like.

Next, a method for producing the raw material powder of the perovskite solid solution of the present invention will be described.

First, the remaining aqueous solution or alcohol solution of the components A and B except the component X is added to the precipitation forming solution with stirring, or conversely, the precipitation forming solution is added to the above solution to form a precipitate.

Incidentally, in the precipitation formation, it is of course possible to add an aqueous solution or an alcohol solution of all the component compounds except the component X to the precipitation forming solution at the same time, or if necessary, to add each solution sequentially.

In addition to the components A and B, when a trace amount component is added to control the sinterability and other characteristics of the perovskite,
You may add when preparing each solution of A component and B component.

The precipitate thus obtained is washed with alcohol or the like if necessary, dried at 120 to 1200 ° C., and calcined.

Then, after mixing the X component compound with this, 400 to 1
Calcination at 200 ° C. gives a uniform and easily sinterable raw material powder of the perovskite solid solution.

If the calcination temperature is lower than 400 ° C., the solid-phase reaction of the mixed powder is insufficient, while if it exceeds 1200 ° C., the powder becomes coarse and the sinterability deteriorates.

The present invention is to produce the raw material powder of the perovskite solid solution as described above, but according to the present invention, since the raw powder having a radioactive α particle count of 0.1 CPH / cm ² or less is obtained, such a perovskite solid solution is obtained. The raw material powder can be applied to a semiconductor or its device, and can be suitably used as, for example, a filler of low melting point glass used as a sealing agent for sealing semiconductor devices. In particular, PZT using Pb as the A component and Ti and Zr as the B component is suitable as the filler because of its low expansion property.

<Effects of the Invention> According to the method of the present invention, easily sinterable fine particles having a high bulk density and having little secondary particles formed in the coprecipitation process and the calcination process of the mixture of the coprecipitate and the X component compound are obtained. .

Further, when a compound having a different ability to form a precipitate from other constituent compounds, or an aqueous solution or an alcohol solution,
A compound that causes precipitation by reacting with an aqueous solution or an alcoholic solution of other constituent compounds is an X-component compound, so that the target perovskite composition is perfect because it is simply mixed with other coprecipitated constituents and calcined. Since the selection range of the X component compound is widened, an inexpensive raw material such as titanium tetrachloride or titanium oxide obtained by thermal oxidative decomposition of titanium tetrachloride can be selected and used.

Furthermore, according to the present invention, the count number of radioactive α particles is 0.1C.
A raw material powder of a perovskite solid solution having a PH / cm ² or less is obtained, and such a raw material powder can be suitably used as a sealing agent component of a semiconductor device. Furthermore, when the count number of other radioactive α particles is large, a trouble may occur. It can be suitably applied to devices and materials.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 22.310 g of reagent grade (Pb0 99.9% or more) lead monoxide (A component compound) and reagent grade of zirconium oxynitrate (B)
12.026 g of the component compound) was dissolved in 75 ml of special grade reagent nitric acid, and 75 ml of pure water was added to obtain an aqueous solution. This aqueous solution is passed through a column packed with an anion exchange resin to adsorb and remove U, Th, etc., and then 5N ammonia water 1 is added with stirring.
To form a coprecipitate.

The coprecipitate was washed with water and dried at 120 ° C for 1 hour, then 700
It was calcined at ℃ for 1 hour. Chlorine method TiO ₂ powder (B component compound and X component compound) made by subjecting this product to a thermal oxidation reaction of a distilled and purified product of titanium tetrachloride of a reagent first grade (purity 99.95% or more, specific gravity 1.72 to 1.76) After adding 3.840 g and mixing in a ball mill, the mixture was calcined at 700 ° C. for 2 hours to obtain a raw material powder having a Pb (Zr _0.52 · Ti _0.48 ) O ₃ composition. This powder was ground with a ball mill.

The count number of radioactive α particles in this powder was measured by an α ray measuring device, and it was found to be 0.08 CPH / cm ² .

As a result of observing this powder with a scanning electron microscope,
It has a uniform particle size of about 0.3μ and βcosθ by X-ray diffraction method
As a result of plotting the relationship of sin θ (where β is the half width of diffraction line and θ is the black angle), the horizontal axis (sin θ axis)
It was confirmed that the composition was almost parallel and had a uniform composition with almost no composition fluctuation.

This powder was molded at 1.5 t / cm ² and sintered at 1200 ° C. for 2 hours in an atmosphere of lead vapor and oxygen.
And was equal to the theoretical density.

Comparative Examples of commercially available special grade Pb0, the powders of TiO ₂ and ZrO ₃ Pb (Zr _0.52
・ Ti _0.48 ) O ₃ was blended so as to have a composition, mixed in a ball mill, calcined at 800 ° C. for 2 hours, and pulverized again in the ball mill.

The count of radioactive α particles in the obtained powder was measured and found to be 3.55 CPH / cm ² .

Further, as a result of plotting the relationship of β cos θ to sin θ by X-ray diffractometry of this powder, a remarkable composition change was recognized.

This powder was molded at 1.5 t / cm ² and sintered at 1200 ° C. for 2 hours in an atmosphere of lead vapor and oxygen, and the density was 7.1.
Therefore, the density was very different from the theoretical density, and the structure was not the closest packing structure.

Claims (6)

[Claims] 1. ABO ₃ (where A represents one or more oxygen 12-coordinated metal elements, B represents one or more oxygen 6-coordinated metal elements, and A component and B The sum of the number of components is 3 or more.) In the method for producing the raw material powder of the perovskite and the solid solution thereof represented by the following, an aqueous solution or alcohol of the remaining component compounds excluding at least one component of the component A and the component B. A precipitate is formed from the solution by a precipitation forming liquid, and the obtained precipitate is 120 to 1
A perovskite having a radioactive α particle count of 0.1 CPH / cm ² or less, characterized by being dried at 200 ° C., calcined, mixed with the component compounds excepted above, and then calcined at 400 to 1200 ° C. And a method for producing a raw material powder of a solid solution thereof. 2. The aqueous solution or alcohol solution of the component A compound contains the component A compound in a free nitric acid concentration of 5 to 10 mol.
A perovskite and its solid solution raw material, which is an aqueous solution or an alcohol solution, which is dissolved in nitric acid so as to have a concentration and then purified with an anion exchange resin. Powder manufacturing method. 3. The aqueous solution or alcohol solution of the B component compound has a free nitric acid concentration of the B component compound of 5 to 10 mol.
A perovskite and its solid solution raw material, which is an aqueous solution or an alcohol solution, which is dissolved in nitric acid so as to have a concentration and then purified with an anion exchange resin. Powder manufacturing method. 4. A raw material powder for a perovskite and its solid solution according to claim 1, wherein the A component is lead, the B component is zirconium, and the removed component is titanium. Manufacturing method. 5. The compound according to claim 1, wherein the titanium compound is titanium tetrachloride or titanium oxide.
A method for producing a raw material powder of the perovskite and its solid solution according to the item (4). 6. The method of producing a raw material powder of perovskite and its solid solution according to claim 1, wherein the raw material powder is a filler for a low melting point glass for sealing a semiconductor device.