KR20070094652A - Container for easily oxidizable or hygroscopic substance, and method for heating and pressuring treatment of easily oxidizable or hygroscopic substance - Google Patents

Abstract

Provided is a container (1) for holding an easily oxidizable or hygroscopic substance (10) to be treated at a high temperature or under pressure in a non-oxidizing atmosphere. The container (1) has an opening (4), and a sealing means (5) which seals the opening (4) air-tightly, and, under a heating or pressuring condition, allows the opening (4) to communicate with a non-oxidizing atmosphere. The sealing means (5) is fused and/or deformed under a heating condition and is ruptured or separated from the container (1) under a pressuring condition.

Description

CONTAINER FOR EASILY OXIDIZABLE OR HYGROSCOPIC SUBSTANCE, AND METHOD FOR HEATING AND PRESSURING TREATMENT OF EASILY OXIDIZABLE OR HYGROSCOPIC SUBSTANCE

The present invention relates to a container for an easily oxidizable or hygroscopic material such as Na flux and a method for heating and pressurizing an easily or easily hygroscopic material.

Gallium nitride thin film crystals have attracted attention as excellent blue light emitting devices, have been put to practical use in light emitting diodes, and are expected to be used as blue violet semiconductor laser devices for optical pickup. As a method of growing a gallium nitride single crystal by the Na flux method, for example, "Jpn. J. Appl. Phys. Vol. Page 42, (2003) In L4-L6, the atmosphere pressure is 50 atm when using only nitrogen, and the total pressure is 5 atm when using a mixed gas atmosphere of 40% ammonia and 60% nitrogen.

For example, Japanese Patent Laid-Open No. 2002-293696 uses 10 to 100 atmospheres by using a mixed gas of nitrogen and ammonia. In Japanese Unexamined Patent Publication No. 2003-292400, the atmospheric pressure at the time of growth is 100 atm or less, and in the examples, it is 2, 3, 5 MPa (about 20 atm, 30 atm, 50 atm). Moreover, also in any prior art, the growth temperature is all 1000 degrees C or less, and all are 850 degrees C or less in an Example.

On the other hand, the applicant of Japanese Patent Application No. 2004-103092 discloses a method of growing a gallium nitride single crystal efficiently under specific conditions by using a hot isostatic press (HIP) apparatus.

However, when crystal growth is carried out by the flux method using such a heating and pressurizing device, it has been found that the following problems arise newly. That is, in the growth using a conventional muffle, the raw material is weighed in a glove box, filled into a crucible, and then sealed in a stainless steel sealed container with a valve, and then the sealed container is taken out of the glove box. Was not exposed to the atmosphere, and oxidation of the raw material by oxygen in the atmosphere and reaction with moisture in the atmosphere could be prevented. However, it is not possible to use a closed container with the above valve in a HIP device. Since the lid is closed after opening the lid of the pressure vessel of the HIP and placing the crucible directly into the vessel, there is a problem that the raw material is exposed to the atmosphere during operation and oxidized or absorbed.

As a result, dissolution of nitrogen at the flux liquid level is inhibited, gallium nitride rate is lowered, and black colored gallium nitride single crystal is obtained.

SUMMARY OF THE INVENTION An object of the present invention is to provide a container suitable for heating and pressurizing an easily oxidizing and hygroscopic material such as Na flux in a non-oxidizing atmosphere, whereby unnecessary oxidation and moisture absorption prior to treatment of the easily oxidizing and hygroscopic material. To prevent.

The present invention is a container for accommodating an easily oxidizing or hygroscopic material which is heated and pressurized in a non-oxidizing atmosphere, the opening being provided, and the opening is hermetically sealed before the treatment, and the opening is scattered when heated and pressurized. According to the container of the easily oxidizing or moisture-absorbing substance which is provided with the sealing means which communicates with a chemical atmosphere.

In addition, the present invention is a method for heating and pressurizing an easily oxidizing or hygroscopic material under a non-oxidizing atmosphere, wherein an opening is provided in a container, the opening is hermetically sealed, and the opening is closed under a non-oxidizing atmosphere. An easily oxidizing or easily absorbing substance, characterized by using a container having a sealing means for communicating with the furnace, containing an easily oxidizing or hygroscopic substance in the container, and subsequently heating and pressurizing the container under a non-oxidizing atmosphere. According to the heating and pressure treatment method.

According to the present invention, an opening is provided in a container of an easily oxidizable or easily hygroscopic material, and the opening is hermetically sealed. Thereby, in the step before heating and pressurizing in a non-oxidizing atmosphere, contact with the oxidizing atmosphere, especially air | atmosphere, of an easily oxidizing or easily hygroscopic material can be prevented. In addition, since the sealing means is released when the container is heated and pressurized in a non-oxidizing atmosphere, it becomes possible to perform a predetermined heating and pressurization treatment on an easily oxidizable or easily hygroscopic substance in the container.

BRIEF DESCRIPTION OF THE DRAWINGS The sectional drawing which shows schematically the container 1 which can be used in embodiment of this invention.

2 is a cross-sectional view schematically showing a container 1A usable in the embodiment of the present invention.

FIG. 3 is a view showing a state in which the container of FIG. 1 (or FIG. 2) is set in the HIP apparatus. FIG.

In the present invention, the type of non-oxidizing atmosphere is not particularly limited, and inert gas atmospheres such as nitrogen and argon, and reducing atmospheres such as carbon monoxide and hydrogen are included, but are particularly suitable for the nitrogen-containing atmosphere. The nitrogen-containing atmosphere may consist only of nitrogen, but may contain a non-oxidizing gas other than nitrogen, such as an inert gas such as argon or a reducing gas.

In addition, in this invention, the apparatus for heating and pressurizing an easily oxidizing property and an easily hygroscopic material is not specifically limited. Although a hot isotropic pressure press apparatus is preferable, this apparatus may be an atmospheric pressurized heating furnace other than that.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail, referring drawings suitably. Each drawing below is demonstrated centering on the example which applied this invention with respect to the single crystal flux raw material.

As shown to FIG. 1, FIG. 2, the crucible 9 is equipped with the crucible main body 8 and the lid 7 which coat | covers the main body 8. As shown in FIG. The crucible 9 is encapsulated in a glove box of a non-oxidizing atmosphere and encapsulated in a container 1 (or 1A) of the present invention under a non-oxidizing atmosphere. This container 1 (1A) is provided with the main body 2 and the cover 3. As shown in FIG. On the upper edge of the main body 2, an elongated flange 2a is formed. The substantially annular flange 3a protrudes also from the lower side of the cover 3, and the creepage distance is lengthened by the flanges 2a and 3a contacting each other.

In the example of FIG. 1, the opening 4 is formed in the predetermined | prescribed point of the lid | cover 3, and the sealing means 5 is being fixed inside each opening 4. As shown in FIG. In the example of FIG. 2, 5 A of sealing means is fixed to the outer side of each opening 4. As shown in FIG. Each container is hermetically sealed from the atmosphere outside the containers 1 and 1A by the sealing means 5 and 5A. In this state, the containers 1 and 1A are taken out of the glove box and are then installed in the crystal growth apparatus as it is.

For example, in the example shown in FIG. 3, the jacket 13 is fixed in the pressure vessel 12 of the HIP (hot isostatic pressure press) apparatus 11, and the container 1 of this invention (1A) in the jacket 13 is shown. Install). Outside the pressure vessel 12, a mixture gas bombe (not shown) is provided. The mixed gas cylinder is filled with a mixed gas having a predetermined composition. The mixed gas is compressed by a compressor to a predetermined pressure, and supplied to the pressure vessel 12 through the supply pipe 15 as shown by arrow A. Nitrogen becomes a nitrogen source in this atmosphere, and inert gas, such as argon gas, suppresses evaporation of a flux. This pressure is monitored by a pressure gauge, not shown. The heater 14 is provided around the container 1 (1A), and the growth temperature in a crucible can be controlled.

Here, the airtight sealing by the sealing means 5 (5A) is released | released at some time in the step of heating and pressurizing the container 1 (1A) in the pressure container 12. As shown in FIG. In the present example, for example, the sealing means 5 (5A) is designed to be melted by high temperature, destroyed by pressure, or separated from the container 1 (1A) by pressure. In the example of FIG. 1, the unnecessary sealing means 5 becomes attached to the inner surface of the container 1 or falls downward in the container 1. In addition, in the example of FIG. 2, the sealing means 5A which became unnecessary becomes a state attached to the outer surface of the container 1A, or it is scattered apart from the container 1A. As a result, the atmosphere 6 in the container communicates with the non-oxidizing atmosphere.

In a suitable embodiment, the sealing means consists of a material which melts and / or deforms under heating. Such a material is preferably softer in that airtightness and release of airtightness are easy. As a material which melts and / or deforms under heating, a low melting point metal or a polymer material is preferable. Whether to melt or deform at a desired temperature is determined by the relationship between the processing temperature and the material of the sealing means. As the low melting point metal, an alloy (for example, solder) containing aluminum, indium, tin, lead, and one or more thereof can be exemplified. Moreover, paraffin, polyethylene, Teflon, butyl rubber can be illustrated as a polymeric material.

In the embodiment in which the sealing means is melted and deformed by heating, the form of the sealing means is not particularly limited, but may be a sheet, may be a film, or may be a plate. Although the thickness of a sealing means is not specifically limited, From a viewpoint of airtightness in a container, 0.01 mm or more is preferable and 0.05 mm or more is more preferable. Further, the thickness of the sealing means is preferably 3 mm or less, more preferably 1 mm or less from the viewpoint of ease of melting and deformation and reliability.

In the embodiment in which the sealing means is melted and deformed by heating, the method of attaching the sealing means to the container is not particularly limited, and the following can be exemplified.

Bond the sealing means to the container.

The sealing means is mechanically fixed to the container.

Furthermore, in a suitable embodiment the sealing means is broken under pressure or separated from the container. When broken, the sealing means may be broken under pressure and the through hole may be opened, or the sealing means may be broken into a plurality of fragments. In this case, at least a part of the sealing means remains attached to the container while the sealing means is broken. On the other hand, the sealing means may be designed to be separated or peeled from the container.

Specifically, the sealing means is easily formed by a material having a low breaking strength that breaks easily upon pressurization or by shaping the sealing means into a thin sheet. As such a material, aluminum foil, stainless foil, and gold foil can be illustrated.

In addition, in order for the sealing means to be easily broken at the time of pressing, the thickness of the sealing means is preferably 0.1 mm or less, and more preferably 0.05 mm or less. Moreover, it is preferable to make thickness of a sealing means 0.01 mm or more from a viewpoint of airtightness maintenance in a container by a sealing means, and it is more preferable to set it as 0.02 mm or more.

In the embodiment in which the sealing means is broken at the time of pressurization, the method of attaching the sealing means to the container is not particularly limited, and the following can be exemplified.

Bond the sealing means to the container.

The sealing means is mechanically fixed to the container.

In addition, in embodiment which a sealing means falls from a container at the time of pressurization, the adhesive force of a sealing means to a container is set low so that a sealing means may reliably separate from a container at the time of pressurization. Such an attachment method is not limited, but there are, for example, adhesion and compression methods.

The formation place of an opening is not specifically limited. For example, although it can install on the lid side of a container, it can also be provided in the container main body side, and can also be provided in both a lid side and a main body side. The number and dimensions of the openings are also not particularly limited. The opening diameter is preferably 1 mm or more, more preferably 3 mm or more from the viewpoint of promoting air permeability between the outside and the atmosphere in the container when the airtight sealing by the sealing means is released. In addition, it is preferable that an opening diameter is 10 mm or less from a viewpoint of ensuring the airtight sealing of a container inside.

The easily oxidizing and hygroscopic substances to which the present invention can be applied are not particularly limited. Easiness of oxidation and moisture absorption means the substance which the oxidation and moisture absorption are observed easily, when contacted with air | atmosphere at normal temperature, for example, the substance which oxidation and moisture absorption are observed within 1 minute. Easiness of oxidation and moisture absorption material may be a mixture of powder, and a molded object may be sufficient as it.

In suitable embodiments, the easily oxidizing and hygroscopic materials are flux raw materials for single crystal (especially nitride single crystal) growth. It is preferable to contain at least 1 type of metal selected from the group which consists of an alkali metal and alkaline-earth metal in this flux. As this metal, sodium, lithium, calcium are especially preferable, and sodium is the most preferable.

In addition, the following metals can be added to this flux other than the said metal, for example.

Potassium, Rubidium, Cesium, Magnesium, Strontium, Barium, Tin

By the growth method of the present invention, for example, the following single crystals can be appropriately grown.

GaN, AlN, InN, these mixed crystals (AlGaInN), BN The heating temperature and pressure in the present invention are not particularly limited because they are selected depending on the type of easily oxidizing and easily absorbing materials. Heating temperature can be 800-1200 degreeC, for example. In addition, there is no particular upper limit, but in the case of the flux method, for example, the upper limit can be 1500 ° C or lower. Moreover, although a pressure is not specifically limited, either, In embodiment which breaks or removes a sealing means by pressure, it is preferable that it is 1 MPa or more, and it is more preferable that it is 5 MPa or more. Although the upper limit of pressure is not specifically defined, In the case of a flux method, it can be 200 MPa or less, for example.

The material of a container is not specifically limited, What is necessary is just an airtight material which is durable in the target heating and pressurization conditions. Examples of such a material include metals and ceramics, and heat-resistant alloys such as stainless steel, iron, tinplate and inconel, alumina and nitride ceramics are preferable.

Hereinafter, more specific single crystal and its growth order are illustrated.

(Growth example of gallium nitride single crystal)

Using the present invention, a gallium nitride single crystal can be grown using a flux containing at least sodium metal. This flux is mixed with gallium raw materials. Although a gallium single metal, a gallium alloy, and a gallium compound can be used as a gallium raw material, a gallium single metal is suitable for handling.

This flux can contain metals other than sodium, such as lithium. Although the ratio of gallium raw material and flux raw material such as sodium may be appropriate, it is generally considered to use an excess of Na. Of course, this is not limiting.

In this embodiment, a gallium nitride single crystal is grown under a pressure of at least 300 atm and at least 2000 atm under an atmosphere composed of a mixed gas containing nitrogen gas. By setting the total pressure to 300 atm or higher, for example, high-quality gallium nitride single crystals can be grown in a high temperature region of 900 ° C or higher, more preferably in a high temperature region of 950 ° C or higher. Although this reason is not clear, it is assumed that nitrogen solubility rises with temperature rise and nitrogen dissolves efficiently in a growth solution. If the total pressure of the atmosphere is 2000 atmospheres or more, since the density of the high pressure gas and the density of the growth solution are very close to each other, it is not preferable because the growth solution becomes difficult to maintain in the crucible.

Density of Various Materials (g / cm 3) Sodium metal nitrogen argon 800 ° C and 1 atmosphere 0.75 0.0003 0.004 927 degrees Celsius, 300 atmospheres 0.08 0.11 927 degrees Celsius, 1000 atmospheres 0.21 0.33 927 ℃, 2000 atmospheres 0.3 (estimated) 0.5 (estimated)

In suitable embodiment, nitrogen partial pressure is made into 100 atmospheres or more and 2000 atmospheres or less in a growth time atmosphere. By setting this nitrogen partial pressure to 100 atm or more, dissolution of nitrogen into the flux can be promoted, for example, in a high temperature region of 1000 ° C. or higher, and a good quality gallium nitride single crystal can be grown. From this point of view, the nitrogen partial pressure of the atmosphere is more preferably at least 200 atm. In addition, it is preferable to make nitrogen partial pressure into 1000 atmosphere or less practically.

Although gases other than nitrogen in atmosphere are not limited, Inert gas is preferable and argon, helium, and neon are especially preferable. The partial pressure of gas other than nitrogen is the value except the nitrogen gas partial pressure from the total pressure.

In a suitable embodiment, the growth temperature of a gallium nitride single crystal is 950 degreeC or more, It is more preferable to set it as 1000 degreeC or more, and even a high quality gallium nitride single crystal can be grown. Moreover, since growth at high temperature is possible, there is a possibility of improving the productivity.

Although there is no upper limit in particular of the growth temperature of a gallium nitride single crystal, when a growth temperature is too high, since a crystal becomes hard to grow, it is preferable to set it as 1500 degrees C or less, and it is more preferable to set it as 1200 degrees C or less from this viewpoint.

The growth substrate for epitaxially growing gallium nitride crystals is not limited, but sapphire, AlN template, GaN template, silicon single crystal, SiC single crystal, Mg0 single crystal, spinel (MgAl ₂ O ₄ ), LiAlO ₂ , LiGaO ₂ , LaAlO _3, LaGaO _3, NdGaO _3, such as the page lobe can be exemplified Sky agent (perovskite) type compound oxide. In addition, the composition formula _{[A l -y (Sr 1 -} x Ba x) y] [(Al 1 -z Ga z) 1-u · D u] O 3 (A is a rare earth element; D is a group consisting of niobium and tantalum At least one element selected from the group consisting of: y = 0.3 to 0.98; x = 0 to 1; z = 0 to 1; u = 0.15 to 0.49; x + z = 0.1 to 2) Can be used. SCAM (ScMMgO ₄ ) can also be used.

(Example of growth of AlN single crystal)

The present invention was confirmed to be effective in growing AlN single crystals by pressurizing a melt containing at least aluminum and a flux containing alkaline earth in a nitrogen-containing atmosphere under specific conditions.

Example

(Example 1)

Using the container 1 shown in FIG. 1, the gallium nitride single crystal film was grown in this order.

An AlN template 2 inches in diameter was used as seed crystal. AlN template refers to an AlN single crystal epitaxial thin film prepared on a sapphire single crystal substrate. The film thickness of the AlN thin film at this time was 1 micron. Metal gallium and sodium metal were weighed into a glove box at a molar ratio of 27:73 and placed in a crucible (9). Thereafter, the crucible 9 was placed in the container 1 and sealed with a lid 3. The material of the container 1 was stainless steel. The opening 4 was provided in two places. The diameter of each opening was 2 mm. An aluminum tape 5 (about 4 to 5 mm in diameter) having a thickness of 100 μm was adhered to the back surface of the lid 3 to close each opening 4.

The sealed container 1 was taken out of the glove box and accommodated in a yoke frame type HIP (hot isostatic press) apparatus as shown in FIG. After replacing the atmosphere in the HIP pressure vessel 12 with nitrogen gas, the temperature was elevated and pressurized at 1000 ° C and 35 MPa and maintained for 24 hours. After cooling to room temperature, when the container 1 was taken out from the pressure container 12, the aluminum tape 5 used to cover the cover was released, and the opening 4 was exposed, and nitrogen gas was introduced into the container. It was confirmed. In addition, since there was no change in the shape of the container, it was confirmed that a hole was opened at the time of pressurization and nitrogen gas was introduced into the container.

By comparing the weight of the crucible 9 before and after the experiment, it was found that approximately 100% of gallium was nitrided when the amount of gallium nitrided was estimated. Further, gallium nitride single crystal with high transparency could be obtained.

(Example 2)

Using the container 1A shown in FIG. 2, the gallium nitride single crystal film was grown in this order.

An AlN template 2 inches in diameter was used as seed crystal. Metal gallium and sodium metal were weighed into a glove box at a molar ratio of 27:73 and placed in a crucible (9). Thereafter, the crucible 9 was placed in the container 1A and sealed with a lid 3. The material of the container 1A was stainless steel. The opening 4 was provided in two places. The diameter of each opening was 2 mm. An aluminum tape 5A (about 4 to 5 mm in diameter) having a thickness of 100 µm was adhered to the surface side of the lid 3 to close each opening 4.

The sealed container 1 was taken out of the glove box and accommodated in a yoke frame type HIP (hot isostatic press) device as shown in FIG. After replacing the atmosphere in the HIP pressure vessel 12 with nitrogen gas, the temperature was elevated and pressurized at 1000 ° C and 35 MPa and maintained for 24 hours. After cooling to room temperature, when taken out from the vessel 1 pressure vessel 12, the aluminum tape 5A used to cover the cover was released, and the opening 4 was exposed, and nitrogen gas was introduced into the vessel. It was confirmed. In addition, since there was no change in the shape of the container, it was confirmed that a hole was opened at the time of pressurization and nitrogen gas was introduced into the container.

By comparing the weight of the crucible 9 before and after the experiment, it was found that approximately 100% of gallium was nitrided when the amount of gallium nitrided was estimated. Further, gallium nitride single crystal with high transparency could be obtained.

(Comparative Example 1)

Single crystals were grown in the same manner as in Example 1. However, the crucible was taken out of the glove box without using the container of FIG. 1, FIG. 2, and it installed in the HIP pressure container as it was. The working time was approximately 5 minutes, during which the crucible was exposed to the atmosphere. When the experiment was conducted in the same manner as in the following examples, only about 30 to 40% by weight of gallium was nitrided. In addition, a black colored gallium nitride single crystal could be obtained.

Claims (11)

A container for containing an easily oxidizing or hygroscopic material which is heated and pressurized in a non-oxidizing atmosphere, An opening is provided, and sealing means for hermetically sealing the opening before the heating and pressurizing treatment and for communicating the opening to the non-oxidizing atmosphere during the heating and pressurizing treatment is provided. Or a container of hygroscopic material. The container of the easily oxidizing or hygroscopic material according to claim 1, wherein the easily oxidizing or hygroscopic material is a raw material of the flux for nitride single crystal growth. 3. The container of an easily oxidizing or hygroscopic material according to claim 2, wherein the flux contains at least one metal selected from the group consisting of alkali metals and alkaline earth metals. The container of any one of claims 1 to 3, wherein the sealing means is made of a material that is melted and / or deformed during the heating and pressurizing treatment. The container of any one of claims 1 to 3, wherein the sealing means is broken from the container or separated from the container during the heating and pressurizing treatment. A method of heating and pressurizing an easily oxidizing or hygroscopic material under a non-oxidizing atmosphere, An opening is provided in the container, and the opening is hermetically sealed, and a container having sealing means for communicating the opening to the non-oxidizing atmosphere during the heating and pressurizing treatment is used. A method for heating and pressurizing an easily oxidizing or hygroscopic material, characterized in that the container contains the easily oxidizing or hygroscopic material, and then the container is heated and pressurized under the non-oxidizing atmosphere. The method of claim 6, wherein the easily oxidizing or hygroscopic material is a raw material of a flux for nitride single crystal growth. 8. The method of claim 7, wherein the flux contains at least one metal selected from the group consisting of alkali metals and alkaline earth metals. The heating and pressurizing treatment method according to any one of claims 6 to 8, wherein the sealing means is made of a material that is melted and / or deformed during the heating and pressurizing treatment. . 9. A method according to any one of claims 6 to 8, wherein said sealing means breaks off or separates from said container during said heating and pressurizing treatment. The heating and pressurizing treatment method according to any one of claims 6 to 8, wherein the heating and pressurizing treatment is performed in a hot isostatic press apparatus.

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