JPH086174B2 - Method for preparing raw material powder of sputtering target for producing oxide thin film and method for producing the same - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention provides that at least one component is a metal powder. II.
TECHNICAL FIELD The present invention relates to a raw material powder preparation method for a sputtering target for producing a Group A-III Group B-copper oxide thin film and a method for producing the sputtering target.

2. Description of the Related Art In recent years, attempts have been made to manufacture IIA group-IIIB group-copper oxide thin films by the sputtering method. That is, this is a method of performing sputtering in an argon-oxygen atmosphere using a sputtering target in which at least one component of the IIA group element, the IIIB group element and copper is a metal powder.

However, the sputtering target obtained by the conventional manufacturing method has a problem that cracks easily form in the manufacturing process, and thus the cracked target becomes powder in a few minutes or a few days at the earliest. . As a conventional mixing method of starting materials for producing a target, a dry mixing method or a wet mixing method has been adopted. However, in the dry mixing method,
If particles having a particle diameter of about 1 μm or less are used, the particles agglomerate with each other during the mixing to form large particles, and it is difficult to uniformly mix them, and the mixing takes a long time.
In the wet mixing method, water or alcohol is generally used as a solvent, but since these solvents react with the metal powder, the reaction product becomes soluble in the solvent, enters the filtrate, or evaporates the solvent. However, the compositional distribution of the powder is not uniform, which is not preferable.

When starting materials are mixed by the above-mentioned conventional mixing method and sintered to manufacture a sputtering target, the metal powder is rapidly oxidized during mixing of the raw materials, molding or sintering, and intense heat generation occurs. With that, the volume changes,
For this reason, there has been a problem that the molded product obtained by molding the starting material and the sputtering target obtained by sintering are self-destructed.

The present invention covers the surface of a metal powder with an oxide film by forming an oxide on the surface of the metal powder in a mixing step with another raw material to form a molded article and spattering by rapid oxidation of the metal powder. Provided are a method for preparing a raw material powder capable of preventing the self-destructive action of a sintered product for a target, and a method for producing a sputtering target.

Means and Actions for Solving Problems The first invention is a novel raw material powder preparation method for a sputtering target for group IIA-group IIIB-copper oxide thin film production.

The second invention is a novel method for producing a sputtering target using the above-mentioned raw material powder.

A first invention comprises a Group II A element, a Group III B element and copper as main components, at least one of the components is a metal powder, and the other components are oxides or oxides by heating. Each component that is a powder of the compound is mixed in an inert solvent under an atmosphere of oxygen or air, and the mixture is dried under an atmosphere of oxygen or air, whereby the metal powder is gradually surface-oxidized with other components. A method for preparing a raw material powder of a sputtering target for group IIA-group IIIB-copper oxide thin film production, which is characterized by mixing.

The inert solvent used in the present invention is a solvent which does not react with the respective components of the starting material and does not substantially dissolve the respective components, and examples thereof are as follows. benzene,
They are aromatic hydrocarbon solvents such as toluene and xylene, aliphatic hydrocarbon solvents such as hexane, heptane and octane, and ketone solvents such as acetone and methyl ethyl ketone.

Solvents having an active functional group such as alcohol solvents,
It is not suitable for use in the present invention because it reacts with the metal powder in the starting material.

In addition, a solvent that dissolves or partially dissolves at least one of the components causes problems such as a difference between the composition ratio of the starting raw material and the composition ratio of the obtained target raw material powder. Not suitable for use in the invention.

The present invention is characterized in that the surface of the metal powder is oxidized by mixing and drying the raw material powder in an oxygen or air atmosphere, and it is possible to prevent self-destruction of the molded product and the sputtering target due to the rapid oxidation of the metal powder. Is to have.

Mixing and drying requires gradual progress of surface oxidation of the metal powder, so that the temperature applicable to both the mixing and drying steps is 10 ° C to 80 ° C. The oxygen partial pressure may be 80 Torr or more. When the temperature is lower than 10 ° C. or the oxygen pressure or the oxygen partial pressure is lower than 80 Torr, the oxidation takes too long, which is not desirable. When the temperature is higher than 80 ° C, the oxidation rapidly progresses and it becomes difficult to control the degree of the oxidation, and the oxidation proceeds to the inside of the metal powder, causing the particles to collapse. Also, reduction during sintering will be difficult.

For the drying, the raw material powder uniformly dispersed in an inert solvent is filtered to form a cake, which is dried. Also, the solvent may be volatilized by bubbling oxygen or air while stirring in an inert solvent or after stirring.

The second invention is II group II-II obtained by the first invention.
Group IB-Sputtering target raw material powder for copper-based oxide thin film production, shaped into a predetermined shape, oxide thin film production characterized by sintering at 600 ~ 950 ℃ under oxygen partial pressure of 10 Torr or less It is a method of manufacturing a sputtering target.

Sputtering target for oxide thin film production of the present invention is a group IIA element, IIIB group elements, copper and oxygen as a main component, these components relative to the total weight of the sputtering target. It accounts for at least 70% by weight. Examples of the IIA group element include Be, Mg, Ca, Sr, Ba and Ra, and examples of the IIIB group element include lanthanide, lanthanum and yttrium.

Examples of the compound which becomes an oxide by heating include a group IIA element, a group IIIB element, copper carbonate and the like, and a compound which changes into an oxide at the sintering temperature.

At least one of the components of the IIA group element, the IIIB group element, and the copper is metal powder. This is because it is easy to adjust the composition of the obtained oxide thin film by controlling the oxygen partial pressure in the oxygen mixed gas (O ₂ -Ar) introduced into the reaction vessel during sputtering, and the accumulation of charges on the target. , To prevent heat accumulation. The accumulation of electric charges changes the sputtering condition, and the accumulation of heat causes thermal deformation and destruction of the target.

For forming the raw material powder into a predetermined shape, a mold and a compression molding machine which are commonly used can be used. The obtained molded product is
It is sintered at a temperature of 600 to 950 ° C. under an oxygen partial pressure of 10 Torr or less. If the oxygen partial pressure during sintering is higher than 10 Torr, reduction of the surface-oxidized metal powder does not proceed, which is not desirable. When the sintering temperature is lower than 600 ° C, sufficient sintering does not proceed, and when the temperature is higher than 950 ° C, the sputtering target melts. Sintering may be performed by heating at the same time as molding and sintering.

EFFECTS OF THE INVENTION The present invention adjusts the raw material powder for sputtering target in which at least one component is a metal powder, and oxidizes the surface of the metal powder in the steps of mixing and drying each component. It is easy to handle and very efficient. That is, there is no heat generation during the mixing and molding of the respective components, the handling thereof is easy and safe, and there is an excellent effect that there is no self-destruction due to the oxidation of the metal of the obtained molded product or sintered product.

Example 1 Y ₂ O ₃ powder 139.5 g, BaO powder 567.9 g, Cu powder 392.7 g as starting materials, toluene 2 as an inert solvent, and ceramic milling balls 3 were placed in a plastic container having an internal volume of 5, Wet mixing was performed for 6 hours at room temperature under air atmosphere.

The milling balls were removed from the obtained suspension, and then most of the toluene was removed by filtration, and the suspension was dried at room temperature under an air atmosphere to obtain a raw material powder for a sputtering target.

This raw material powder was uniaxially molded and then molded using a hydrostatic pressing machine.

The obtained molded product was stable without causing heat generation or self-destruction even when left in the air.

Using a vacuum sintering furnace, this molded product was sintered in air at a pressure of 1 to 2 Torr under the conditions of 880 ° C. for 6 hours to obtain a diameter of 1
A disk-shaped sputtering target for manufacturing a superconducting thin film having a thickness of 10 mm and a thickness of 5 mm was manufactured.

The element ratio of Y, Ba, and Cu of this sputtering target was equal to the element ratio of the starting material, the distribution of the element ratio was uniform, and the electric resistance was 10 mΩ · cm.

Example 2 A raw material powder for a sputtering target prepared in the same manner as in Example 1 was uniaxially molded and then sintered in the same manner as in Example 1 without using a hydrostatic press. A sputtering target was obtained.

Example 3 Starting materials were mixed in the same manner as in Example 1, and after mixing,
Instead of passing the obtained suspension, air was blown into the suspension at room temperature to evaporate toluene to obtain a dry sputtering target material powder for sintering.

When this raw material powder was molded in the same manner as in Example 1, it was stable even if it was left in the air without causing heat generation or self-destruction.

This molded product was sintered to obtain a sputtering target for producing a superconducting thin film.

The element ratio of Y, Ba, and Cu of this sputtering target was equal to the element ratio of the starting material, the distribution of the element ratio was uniform, and the electric resistance was 10 mΩ · cm.

Example 4 A raw material powder for sputtering target sintering obtained by the same preparation method as in Example 1 was used, using a thermal compression molding machine.
Thermal compression molding was performed under the conditions of a pressure of 50 to 100 kg / cm ² and a temperature of 700 to 900 ° C.

After hot compression molding, furnace cooling was performed to obtain a disc-shaped target having a thickness of 6 mm and a diameter of 110 mm. The electrical resistance of this target was 10 mΩ · cm.

Example 5 A molded article which had been molded by the method of Comparative Example 1 and which had self-destructed after molding was again ground, and toluene was added to give a suspension.

Oxygen was blown into this suspension at room temperature for about 10 minutes to evaporate most of the solvent and then allowed to stand in the air with light stirring, and the solvent was further evaporated to obtain a dry powder in about 2 hours.

This powder was molded and sintered in the same manner as in Example 1 to prepare a target.

As a result, neither self-destruction after molding nor cracking of the target after sintering was observed, and the same target as in Example 1 was obtained.

Comparative Example 1 The starting materials were mixed in the same manner as in Example 1, and after mixing,
The obtained suspension was dried under reduced pressure with an evaporator to obtain a dry powder.

When this powder was uniaxially molded at a pressure of 50 kg / cm ² , it generated heat after molding and immediately cracked and self-destructed.

Comparative Example 2 139.5 g of Y ₂ O ₃ powder, 567.9 g of BaO powder, and 392.7 g of Cu powder were used as starting materials, and were dry-mixed by a raker machine.

The obtained mixed powder was tried to be uniaxially molded, but it generated heat immediately after molding and self-destructed in about 5 minutes.

Comparative Example 3 A raw material powder for a sputtering target was prepared in the same manner as in Example 1 except that ethanol was mixed in the starting raw material instead of toluene.

However, the suspension of the raw material powder generated heat during the wet mixing, and a candy-like deposit was found on the inner surface of the plastic container.

The obtained raw material powder was not in a uniform mixed state, and when the elemental composition was quantified by fluorescent X-ray, a decrease in Cu content was observed.

When this raw material powder was molded and sintered, cracks were found in the obtained sputtering target.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Daimon 5 Ube City, Ube City, Yamaguchi Prefecture, Kogushi 1978 5 Ube Industries, Ltd. Ube Laboratory Co., Ltd. Examiner, Ube Research Institute, Ltd. Susumu Ogawa (56) References Japanese Patent Laid-Open No. 63-248019 (JP, A)

Claims (5)

[Claims] 1. A compound containing a Group II A element, a Group III B element and copper as main components, at least one of the components being a metal powder, and the other components being oxides or oxides by heating. In the method for preparing the raw material powder of the sputtering target for producing an oxide thin film which is a powder of 1., each component is mixed in an inert solvent under an oxygen or air atmosphere, and the mixture is dried under an oxygen or air atmosphere. According to the method II, a raw material powder preparation method for a sputtering target for producing a group A-IIIB-group copper-based oxide thin film, wherein the metal powder is gradually surface-oxidized and mixed with other components. 2. The preparation method according to claim 1, wherein the oxygen pressure or the oxygen partial pressure in the air is 80 Torr or more. 3. The preparation method according to claim 1, wherein mixing and drying are performed at a temperature of 10 ° C. to 80 ° C. 4. A compound containing a Group II A element, a Group III B element and copper as main components, at least one of the components being a metal powder, and the other component being an oxide or an oxide by heating. The respective powder components are mixed in an inert solvent under an atmosphere of oxygen or air, and the mixture is dried under an atmosphere of oxygen or air to mix the metal powder with other components while gradually oxidizing the surface. IIA group-IIIB group-obtained by
Sputtering target powder for copper-based oxide thin film production, which is formed into a predetermined shape and is sintered at 600 to 950 ° C. under an oxygen partial pressure of 10 Torr or less, and is used as a sputtering target for oxide thin film production. Ring target manufacturing method. 5. The method for producing a sputtering target according to claim 4, wherein the sintering treatment is carried out while press-molding into a predetermined shape.