JP2024040414A - Gallium nitride-based sintered body and its manufacturing method - Google Patents

Abstract

An object of the present invention is to manufacture a sputtering target for a gallium nitride thin film that is of high quality and can be used for various color light emitting diodes and power devices. [Solution] A gallium nitride-based sintered material having a content of one or more Group 13 elements selected from the group consisting of boron, aluminum, and indium is 0.001 atm% or more and 25 atm% or less and an oxygen content of 1 atm% or less. Provides cohesion. [Selection diagram] None

Description

Gallium nitride has attracted attention as a raw material for the light-emitting layer of blue light emitting diodes (LEDs) and blue laser diodes (LDs), and in recent years has been used in the form of thin films and substrates for a variety of applications such as white LEDs and blue LDs. It is also attracting attention as a material for applications such as power devices in the future. Currently, gallium nitride thin films are generally manufactured by metal organic chemical vapor deposition (MOCVD). The MOCVD method is a method of growing crystals by impregnating a carrier gas with the vapor of a raw material, transporting it to the surface of a substrate, and decomposing the raw material by reaction with the heated substrate.

A sputtering method can be mentioned as a method for producing a thin film other than the MOCVD method. In this sputtering method, positive ions such as Ar ions physically collide with a target placed on the cathode, and the material that makes up the target is released by the collision energy, and the material that makes up the target is placed on a substrate placed opposite to it. There are direct current sputtering method (DC sputtering method) and high frequency sputtering method (RF sputtering method).

Until now, a metal gallium target has been used as a method for forming a gallium nitride thin film by sputtering (see, for example, Patent Document 1). However, when using a metallic gallium target, since metallic gallium has a melting point of approximately 29.8°C, it melts during sputtering, resulting in a gallium nitride film with highly stabilized properties such as crystallinity and transparency. To prevent this, methods have been proposed in which an expensive cooling device is installed and the film is formed at lower power, but this reduces productivity and increases the amount of oxygen incorporated into the film. The problem was that it was easy.

Also, a high-density sintered gallium nitride has been proposed (for example, see Patent Document 2), but according to this example, it becomes dense under extremely high pressure conditions of 58 Kbar (5.8 GPa). Equipment that applies such pressure is extremely expensive and cannot produce large sintered bodies. Therefore, the sputtering target used in the sputtering method itself is very expensive, and since it is difficult to increase the size of the sputtering target, there has been a problem that the film tends to have poor homogeneity.

Furthermore, as a method for reducing the amount of oxygen contained, a method has been proposed in which a sintered gallium nitride body containing oxygen is subjected to a nitriding treatment to reduce the amount of oxygen (see, for example, Patent Document 3). However, there has been a problem in that when the amount of oxygen is reduced beyond a certain level, cracks may occur in the sintered body.

Furthermore, when using the DC sputtering method, the sputtering target is required to have low resistivity. As a method for this, a method has been proposed in which the resistivity of the sputtering target is reduced by infiltrating metallic gallium into a gallium nitride molded product (see, for example, Patent Document 4). However, although this method reduces resistance, there is a problem that metal gallium precipitates during bonding or sputtering, reacts with solder materials such as indium, and peels off the gallium nitride molded product, making it impossible to perform stable discharge. there were. As a countermeasure, a method has been proposed to suppress the precipitation of metallic gallium by lining it with a thin tungsten film (see, for example, Patent Document 5), but this method increases the number of target production steps, becomes complicated, and is expensive. There was a problem in that it required the use of a special material called tungsten material.

Furthermore, in recent years, studies have been progressing on forming gallium nitride films on large silicon substrates, and even larger sputtering targets will be needed in the future, but such targets currently do not exist.

In addition, gallium nitride-based LEDs are required to have not only blue but also green and red colors, which requires them to contain aluminum and indium, but such sputtering targets have not been available so far. Ta.

Japanese Patent Application Publication No. 11-172424 Japanese Patent Application Publication No. 2005-508822 Japanese Patent Application Publication No. 2012-144424 Japanese Patent Application Publication No. 2014-159368 Japanese Patent Application Publication No. 2014-91851

An object of the present invention is to provide a gallium nitride-based sintered body containing a Group 13 element such as aluminum that has high strength and is free from cracking, and a sputtering target using the same.

In view of this background, the present inventors have conducted extensive studies. As a result, by processing gallium nitride powder with a low oxygen content using a hot press mold that has an appropriate holding time and coefficient of thermal expansion in line with gallium nitride sintering, we have achieved high density, large-scale nitriding with a low oxygen content. It was discovered that a gallium-based sintered body can be produced, and the present invention was completed.

That is, the aspects of the present invention are as follows.
(1) Gallium nitride-based sinter in which the content of one or more Group 13 elements selected from the group consisting of boron, aluminum, and indium is 0.001 atm% or more and 25 atm% or less, and the oxygen content is 1 atm% or less body.
(2) The gallium nitride-based sintered body according to (1), wherein the oxygen content is less than 0.3 atm%.
(3) As described in (1) or (2), the total impurity amount of the elements Si, Ge, Sn, Pb, Be, Mg, Ca, Sr, Ba, Zn, and Cd is contained less than 10 wtppm. Gallium nitride based sintered body.
(4) The gallium nitride-based sintered body according to any one of (1) to (3), characterized in that the total amount of impurities of Mg and Si is less than 5 wtppm.
(5) The gallium nitride-based sintered body according to any one of (1) to (4), which contains less than 1 wtppm of Si impurities.
(6) The gallium nitride-based sintered body according to any one of (1) to (5), which has a density of 3.0 g/cm ³ or more and 5.4 g/cm ³ or less.
(7) Any one of (1) to (6), characterized in that the maximum value of the peak attributable to gallium metal in the X-ray diffraction peak of the sintered body is 10% or less of the maximum value of the gallium nitride peak. A gallium nitride-based sintered body described in .
(8) The gallium nitride-based sintered body according to any one of (1) to (7), wherein the average grain size of the sintered body is 1 μm or more and 150 μm or less.
(9) A method for producing a gallium nitride-based sintered body by a hot pressing method, comprising gallium nitride powder with an oxygen content of 1 atm% or less and one or more Group 13 elements selected from the group consisting of boron, aluminum, and indium. The material described in any one of (1) to (8), wherein the difference between the coefficient of linear thermal expansion in the direction perpendicular to the pressing direction of the hot press mold and the coefficient of linear expansion of the raw material is within 15%. A method for manufacturing a gallium nitride-based sintered body.
(10) The method for producing a gallium nitride-based sintered body according to (9), which is a hot press mold for producing a disk, and the number of divisions of the sleeve is three or more.
(11) A sputtering target characterized by using the gallium nitride-based sintered body according to any one of (1) to (8).
(12) The sputtering target according to (11), characterized in that there is no layer containing tungsten between the target member and the bonding layer.
(13) A method for producing a gallium nitride thin film, characterized by using the sputtering target described in (11) or (12).

The gallium nitride-based sintered body of the present invention is characterized in that the total content of one or more group 13 elements selected from the group consisting of B, Al, and In is 0.001 atm% or more and 25 atm% or less, It is preferably .01 atm% or more and 25 atm% or less, more preferably 0.1 atm% or more and 25 atm% or less. By obtaining such a gallium nitride-based sintered body containing B, Al, and In, it becomes possible to use the gallium nitride-based thin film as a sputtering target and as a thin film for green or red LEDs or as a thin film for power devices after deposition. .

The gallium nitride-based sintered body of the present invention preferably has an area of 150 cm ² or more, more preferably 175 cm ² or more, particularly preferably 200 cm ² or more. By obtaining a large-area gallium nitride-based sintered body, it is possible to increase the size of a substrate on which a film can be formed.

It is also characterized by an oxygen content of 1 atm% or less, preferably 0.5 atm% or less, more preferably less than 0.3 atm%, still more preferably 0.2 atm% or less, and still more preferably 0. .1 atm% or less. By reducing the oxygen content in the gallium nitride-based sintered body, when used as a sputtering target, it is possible to reduce the inclusion of oxygen as an impurity during film formation and obtain a film with higher crystallinity. .

Here, atm% has the same meaning as at%, and is expressed as the ratio of the number of atoms of a specific element to the number of atoms of all contained elements. For example, in gallium nitride containing oxygen, if gallium, nitrogen, and oxygen are each contained in wt%, the oxygen content (atm%) is calculated as follows: oxygen content (atm%) = (oxygen content (wt%) )/Oxygen atomic weight)/((Gallium content (wt%)/Gallium atomic weight)+(Nitrogen content (wt%)/Nitrogen atomic weight)+(Oxygen content (wt%)/Oxygen atomic weight))).

In order to make it possible to control the gallium nitride-based sintered body of the present invention into p-type and n-type semiconductors, Si, Ge, Sn, Pb, Be, Mg, and Ca must be present in the gallium nitride-based sintered body. , Sr, Ba, Zn, and Cd, the total amount of impurities is preferably less than 10 wtppm, more preferably 5 wtppm or less, and particularly preferably 3 wtppm or less.

Among the impurities, the total amount of Mg and Si, which have a high activation rate, is preferably contained in a total amount of 5 wtppm or less, more preferably 2 wtppm or less, and particularly preferably 1 wtppm. Furthermore, it is preferable that the amount of Si impurities is 1 wtppm or less.

The gallium nitride-based sintered body of the present invention preferably has a bending strength of 50 MPa or more, more preferably 60 MPa or more, and still more preferably 70 MPa or more. With such strength, it is possible to fabricate large-area sintered bodies without cracking, and even when used as a sputtering target, the sintered bodies are free from stress during the bonding process. It also becomes possible to withstand stress.

The gallium nitride-based sintered body of the present invention preferably has a density of 3.0 g/cm ³ or more and 5.4 g/cm ³ or less, more preferably 3.5 g/cm ³ or more and 5.4 g/cm ³ or less. , particularly preferably 4.0 g/cm ³ or more and 5.4 g/cm ³ or less. The density of the gallium nitride-based sintered body described here refers to the density including open pores. Such a gallium nitride-based sintered body can be used as a sputtering target.

The gallium nitride-based sintered body of the present invention preferably has an average particle diameter (D50) of 1 μm or more and 150 μm or less, more preferably 5 μm or more and 100 μm or less, particularly preferably 9 μm or more and 80 μm or less. With such a particle size, it becomes possible to obtain a gallium nitride-based sintered body with a lower oxygen content and high strength. The average particle diameter (D50) here refers to the 50% particle diameter in the area of primary particles observed with a scanning electron microscope or the like.

Further, it is preferable that the sintered body contains little metal gallium. In particular, the maximum value of the peak due to gallium metal in the X-ray diffraction peak is preferably 10% or less of the maximum value of the gallium nitride peak, more preferably 5% or less, and still more preferably 1% or less. . When metallic gallium is present in a sintered body, it becomes alloyed with one or more group 13 elements selected from the group consisting of B, Al, and In, lowers the melting point, and liquefies, making it impossible for the sintered body to maintain its shape. , or cracks may occur. Furthermore, when used as a sputtering target, Ga-(B, Al, In) alloy precipitates during sputtering, making stable film formation difficult.

Next, a method for manufacturing a gallium nitride-based sintered body according to the present invention will be explained.

In order to obtain a large, low-oxygen sintered body without causing cracks in the gallium nitride-based sintered body, it is necessary to sinter the gallium nitride-based sintered body without applying stress.

That is, the method for producing a gallium nitride-based sintered body of the present invention is a method for producing a gallium nitride-based sintered body by a hot pressing method, and comprises gallium nitride powder having an oxygen content of 1 atm% or less and boron, aluminum, and indium. The raw material is powder of one or more group 13 elements selected from the group consisting of: The difference between the coefficient of linear thermal expansion in the direction perpendicular to the pressing direction of the hot press mold and the coefficient of linear expansion of the raw material is within 15%. shall be.

Below, the method for manufacturing a gallium nitride-based sintered body of the present invention will be explained in more detail.

First, the gallium nitride powder used as a raw material needs to have an oxygen content of 1 atm % or less. More preferably, it is less than 0.5 atm%, still more preferably less than 0.3 atm%, even more preferably 0.2 atm% or less, still more preferably 0.1 atm% or less. In order to reduce oxygen, it is necessary to suppress surface oxidation, so the specific surface area of the powder is preferably small, more preferably from 0.01 m ² /g to 1.5 m 2 /g, and even more preferably from 0.01 m 2 /g to 1.5 m ² /g. is 0.01 m ² /g or more and less than 0.8 m ² /g. If the specific surface area is smaller than 0.01 m ² /g, the crystal grains are too large and the adhesion between the grains is weak, making it difficult to retain the shape during final firing. As the sinterability deteriorates, firing becomes difficult.

In addition, in order to obtain a gallium nitride-based sintered body with sufficient strength as a sputtering target, the light bulk density of the raw material gallium nitride powder must be 1.0 g/cm ³ or more and less than 3.0 g/cm ³ is preferable, and more preferably 1.4 g/cm ³ or more and less than 3.0 g/cm ³ . Note that the light bulk density is a value obtained by filling a container with a constant volume with powder without applying a load such as vibration, and dividing the volume of the filled powder by the volume of the container. If the light bulk density is higher than 3.0 g/ ^cm3 , the strength of the granules that make up the powder will become too high, and the granules will remain unbroken during molding and firing, resulting in a significant decrease in the strength of the gallium nitride-based sintered body. descend.

Moreover, it is preferable that the average particle diameter (D50) of the gallium nitride powder used as a raw material is 1 μm or more and 150 μm or less. Furthermore, it is preferably 5 μm or more and 100 μm or less, and even more preferably 9 μm or more and 80 μm or less. By using such powder, it is possible to produce a gallium nitride-based sintered body that has both high strength and low oxygen content. In particular, for gallium nitride, the sintering start temperature and decomposition temperature are close, the sintering temperature range is narrow, and large grains do not grow during sintering, so the distribution of primary particles before sintering is similar to that of gallium nitride sintered bodies. make a big impact. In addition, the particle size of the primary particle refers to the diameter of the smallest unit particle observed by SEM, and the average particle size is measured by the diameter method, and after measuring at least 100 particles, the value at 50% particle size is calculated. refers to Here, the average particle diameter is measured for gallium nitride particles. In the case of molded products using powder in this range, the particle size is larger than conventional ones and the adhesion force is small, so if there are open pores that can be immersed, the bonding force between the particles is relatively weak, so Ga If immersion is performed, cracks will occur due to stress generated during immersion and differences in thermal expansion coefficients caused by heating and sputtering.

Note that it is preferable to use a gallium nitride powder containing as few impurities as possible as a raw material, since the semiconductor properties change due to obtaining high crystallinity of the sputtered film and adding elements. However, in order to make it a p-type or n-type semiconductor, the total impurity of the elements Si, Ge, Sn, Pb, Be, Mg, Ca, Sr, Ba, Zn, and Cd is added to the gallium nitride powder as impurity elements. The content is preferably less than 10 wtppm, more preferably 5 wtppm or less, particularly preferably 3 wtppm or less.

Among the impurities, the total amount of Mg and Si, which have a high activation rate, is preferably contained in a total amount of 5 wtppm or less, more preferably 2 wtppm or less, and particularly preferably 1 wtppm. Furthermore, it is preferable that the amount of Si impurities is 1 wtppm or less.

Similarly, it is preferable to use boron, aluminum, and indium that contain as few impurities as possible. The purity is preferably 99 wt% or more, more preferably 99.9 wt% or more with respect to metal impurities.

The form of boron, aluminum, and indium to be contained is not particularly limited, and it is preferable that they contain as little oxygen as possible and other metal elements, so metal boron, boron nitride, metal aluminum, aluminum nitride, metal indium , preferably indium nitride. More preferred are metal aluminum, aluminum nitride, metal indium, and indium nitride. The amount of oxygen contained in the raw material is preferably 3 atm% or less, more preferably 1.5 atm% or less, and still more preferably 1 atm% or less. By doing so, it becomes possible to obtain a gallium nitride-based sintered body with a suppressed amount of oxygen.

As the firing method, a hot press method is used. The hot press method is a method that advances sintering by applying temperature while pressurizing the powder. By applying uniaxial pressure during heating, it assists diffusion during firing, making it possible to create materials with low diffusion coefficients that are difficult to sinter. This is a firing method that enables sintering.

It is preferable that the difference between the coefficient of linear thermal expansion in the direction perpendicular to the pressing direction of the hot press mold and the coefficient of thermal expansion of the input raw material is within 15%, more preferably within 10%, even more preferably It is within 5%. More preferably, the coefficient of thermal expansion is +1% or less and -5% or more with respect to the coefficient of thermal expansion of the raw material. The linear thermal expansion coefficient of the hot press mold here is the value for the mold shown in FIG. In the case of producing a gallium nitride-based sintered body, it is preferably 5.0×10 ⁻⁶ /K or more and 7.0×10 ⁻⁶ /K or less. More preferably, it is 5.0×10 ⁻⁶ /K or more and 6.0×10 ⁻⁶ /K or less. By using a material with a coefficient of thermal expansion within this range, the coefficient of linear thermal expansion will be close to that of gallium nitride, making it possible to reduce stress when increasing the size. In the case of small sizes, sintering was possible because the dimensional difference was small even if the coefficients of linear thermal expansion were different, but fine cracks were included, which caused a decrease in strength. When it is 150 cm ² or more, the difference in dimensions due to the difference in thermal expansion becomes large, stress is applied during firing, and cracks occur. Specifically, when the temperature is 5.0×10 ^-6 /K or less, pressure sintering is performed at a predetermined temperature, and the shrinkage of the hot press mold is smaller than that of the gallium nitride-based sintered body when the temperature cools down, so a large tensile stress is generated. occurs, causing cracks in the gallium nitride-based sintered body.On the other hand, if the temperature is 7.0×10 ^-6 /K or higher, the shrinkage of the hot press mold is larger than that of the gallium nitride-based sintered body when the temperature is lowered. , compressive stress is generated from the outside, and the gallium nitride-based sintered body also suffers a decrease in strength and cracks due to cracks.

An example of a hot press mold is shown in FIG. 1, and it is preferable that the die, upper punch, lower punch, and sleeve in this figure be made of the same material. By using the same material, the volume changes during heating will be the same, making it possible to reduce stress during thermal expansion and contraction.

The firing temperature is 1060°C or more and less than 1200°C. In order to advance the sintering of gallium nitride, a temperature of 1060°C or higher is required, and in order to suppress the decomposition of gallium nitride into nitrogen and metallic gallium to a certain level, the temperature must be lower than 1200°C. Further, in order to improve the density of the gallium nitride-based sintered body, the pressure during firing is preferably 30 MPa or more and 100 MPa or less, more preferably 40 MPa or more and 90 MPa or less.

The firing temperature depends on the particle size of the powder used; the larger the particle size, the higher the temperature can be applied.

The holding time during firing is preferably 15 minutes or more and less than 1 hour. If the time is less than 15 minutes, particles will not stick to each other even if the density improves due to partial decomposition of gallium. If fired for longer than 1 hour, the decomposition progresses and alloys with the boron, aluminum, and indium contained, lowering the melting point, making it impossible to maintain strength even if the density improves. By firing within this range, it becomes possible to suppress decomposition while proceeding with sintering, and it is possible to obtain a gallium nitride-based sintered body with higher strength than before.

The atmosphere in the hot press is under vacuum. The degree of vacuum at the start of heating is 10 Pa or less, preferably 1×10 ⁻¹ Pa or less, more preferably 5×10 ⁻² Pa, particularly preferably 1×10 ⁻² Pa or less. This makes it possible to reduce oxygen and oxygen elements such as water mixed in from the atmosphere, and to suppress oxidation during firing.

In addition, when sintering under vacuum, the decomposition of gallium nitride powder gradually progresses from around 1060°C, but by sintering under vacuum, some of the decomposed metal gallium is mixed with nitrogen, which is the decomposition gas. It is discharged to the outside from the gallium nitride-based sintered body. For this reason, in the hot press mold, it is preferable that the clearance between the die and the upper punch be 0.2 mm or more. Alternatively, it is preferable to use a low-density material such as carbon felt between the powder and the upper and lower punches.

Preferably, the hot press mold includes a split sleeve. More preferably, the number of divisions of the sleeve is 3 or more, and even more preferably 4 or more. The maximum number of divisions is preferably six or less. By dividing the sleeve in this manner, the gallium nitride-based sintered body can be easily taken out, and cracking and chipping can be prevented.

Further, in order to reduce oxygen adsorbed in the hot press mold, it is preferable to perform dry firing once before firing. By doing so, it becomes possible to reduce moisture adsorbed on the hot press equipment and mold before firing.

It is preferable that the obtained gallium nitride-based sintered body has a disk shape. The disk shape allows thermal expansion and contraction to be uniform in the circumferential direction, making it possible to suppress stress applied to the gallium nitride-based sintered body.

The obtained gallium nitride-based sintered body may be processed into predetermined dimensions depending on the use, such as a sputtering target. Although the processing method is not particularly limited, a surface grinding method, a rotary grinding method, a cylindrical grinding method, or the like can be used.

The gallium nitride-based sintered body may be fixed (bonded) to a flat or cylindrical support using an adhesive such as a solder material and used as a sputtering target, if necessary. It is preferable that the sputtering target does not include a layer containing tungsten between the target member and the bonding layer. Costs are reduced by not using an expensive metal tungsten target, and productivity is improved because a tungsten film formation process is no longer necessary.

Further, in the sputtering target of the present invention, it is preferable to use a tin-based solder material, an indium-based solder material, or a zinc-based solder material as the bonding layer. Among these, indium solder is particularly preferred because it has high electrical conductivity and thermal conductivity, and is soft and easily deformed.

Further, in the sputtering target of the present invention, a metal such as Cu, SUS, or Ti is preferably used as a support because of its high thermal conductivity and high strength. As for the shape of the support, it is preferable to use a flat support for a flat molded product, and to use a cylindrical support for a cylindrical molded product.

Next, a method for manufacturing a sputtering target of the present invention will be explained.

The sputtering target of the present invention is manufactured by bonding a gallium nitride-based sintered body to a support via a bonding layer. Tin-based solder material, indium-based solder material, zinc-based solder material, etc. can be used for the bonding layer. When using indium-based solder material, the indium wettability to the gallium nitride-based sintered body must be adjusted. In order to improve the wettability, a layer for improving wettability may be formed between the gallium nitride-based sintered body and the solder material. It is preferable that the material of the layer is inexpensive and has high wettability to indium; for example, it is preferable to use a nickel-based material or a chromium-based material. This layer is preferably formed uniformly over the entire interface with the solder material. The method for forming such a barrier layer is not particularly limited, and sputtering, vapor deposition, coating, etc. can be used.

The gallium nitride-based sintered body of the present invention is suitable for use as a sputtering target for LED thin films of various colors.

Hot press mold used in Examples and Comparative Examples Four-part sleeve used in the example

The present invention will be explained below using examples, but is not limited thereto.
(light bulk density)
The measurement was performed using a powder tester PT-N type (manufactured by Hosokawa Micron).
(Density of gallium nitride-based sintered body)
The density of the gallium nitride-based sintered body was determined according to the bulk density measurement method in JISR1634.
(oxygen content)
The oxygen content was measured using an oxygen/nitrogen analyzer (manufactured by LECO).
(Measurement of average particle diameter (D50))
The average particle diameter (D50) was measured using the diameter method from the observed image with the SEM over at least three fields of view, and after measuring 100 or more particles, 50% particle diameter was taken as the average particle diameter. The measurement targets were only gallium nitride powder and gallium nitride particles in a gallium nitride sintered body.
(flexural strength)
The bending strength of the sintered body was measured in accordance with JIS R 1601 after processing the sintered body into appropriate dimensions.
(Impurity analysis)
Impurities other than gas components were analyzed using GDMS (glow discharge mass spectrometry).
(Confirmation of crystal phase, measurement method of intensity ratio)
For normal measurements, a general powder X-ray diffraction device (device name: Ultima III, manufactured by Rigaku Corporation) was used. The conditions for XRD measurement are as follows.

Radiation source: CuKα radiation (λ=0.15418nm)
Measurement mode: 2θ/θ scan
Measurement interval: 0.01°
Divergence slit: 0.5deg
Scattering slit: 0.5deg
Light receiving slit: 0.3mm
Measurement time: 1.0 seconds
Measurement range: 2θ=20°~80°
For the identification analysis of the XRD pattern, XRD analysis software (trade name: JADE7, manufactured by MID) was used. The hexagonal crystal is JCPDS No. The gallium nitride crystal phase was confirmed with reference to 00-050-0792, and the metal gallium was determined by, for example, JCPDS No. The ratio between the highest peaks was confirmed using 00-005-0601 as a reference.
Peak intensity ratio (%) = Metallic gallium maximum peak intensity/Gallium nitride maximum peak intensity (Examples 1 to 6)
600g of gallium nitride powder to which elements were added in the proportions shown in Table 1 was used in Example 1 and 120g in Examples 2 to 6, and the powder was charged into a carbon mold having the coefficient of thermal expansion of the die shown in Table 2 and hot pressed. I invested in it. Firing was started under the conditions shown in Table 2, and the temperature was increased at a rate of 200°C/h, and finally reached the temperature shown in Table 2. The pressure conditions were raised to the pressure shown in Table 2 while maintaining the maximum temperature, and the hot press treatment was performed while maintaining the temperature and pressure for 2 hours. The temperature was lowered to about 50° C., the mold was taken out, and the sintered body was recovered. Table 3 shows the results of the area, X-ray peak intensity ratio, density, oxygen content, bending strength, and average particle diameter (D50) of the obtained gallium nitride-based sintered body.

Further, Table 4 shows the results of the amount of impurities in Example 1.

(Comparative Examples 1 to 3)
Using the gallium nitride powder shown in Table 1, hot pressing was performed under the same conditions as in Example 2 except for the conditions shown in Table 2. Table 3 shows the results of intensity ratio, density, oxygen content, bending strength, and average particle diameter (D50). In Comparative Example 1, no sintered body was obtained and the area could not be measured.

1 Sleeve 2 Die 3 Upper punch 4 Lower punch

Claims (12)

A gallium nitride-based sintered body in which the content of one or more Group 13 elements selected from the group consisting of boron, aluminum, and indium is 0.001 atm% or more and 25 atm% or less, and the oxygen content is 1 atm% or less. The gallium nitride-based sintered body according to claim 1, characterized in that the oxygen content is less than 0.3 atm%. The gallium nitride-based sinter according to claim 1 or 2, characterized in that the total impurity amount of the elements Si, Ge, Sn, Pb, Be, Mg, Ca, Sr, Ba, Zn, and Cd is contained in an amount of less than 10 wtppm. body. The gallium nitride-based sintered body according to any one of claims 1 to 3, characterized in that the total amount of impurities of Mg and Si is less than 5 wtppm. The gallium nitride-based sintered body according to any one of claims 1 to 4, characterized in that it contains less than 1 wtppm of Si impurities. The gallium nitride-based sintered body according to claim 1, having a density of 3.0 g/cm ³ or more and 5.4 g/cm ³ or less. The gallium nitride according to any one of claims 1 to 6, wherein the maximum value of the peak attributable to gallium metal in the X-ray diffraction peak of the sintered body is 10% or less of the maximum value of the gallium nitride peak. system sintered body. A method for producing a gallium nitride-based sintered body by a hot pressing method, using as raw materials gallium nitride powder with an oxygen content of 1 atm% or less and powder of one or more group 13 elements selected from the group consisting of boron, aluminum, and indium. , wherein the atmosphere of the hot press is under vacuum, and the difference between the coefficient of linear thermal expansion in the direction perpendicular to the pressing direction of the hot press die and the coefficient of linear expansion of the raw material is within 15%. 7. The method for producing a gallium nitride-based sintered body according to any one of 7. 9. The method for producing a gallium nitride-based sintered body according to claim 8, wherein the method is a hot press type for producing a disk, and the number of divisions of the sleeve is three or more. A sputtering target characterized by using the gallium nitride-based sintered body according to any one of claims 1 to 7. The sputtering target according to claim 10, characterized in that there is no layer containing tungsten between the target member and the bonding layer. A method for producing a gallium nitride thin film, comprising using the sputtering target according to claim 10 or 11.