Sputtering target

Abstract

The present application provides a gallium nitride-based gallium sputtering target that has a low oxygen concentration, is less likely to crack during sputtering, and has a high film formation rate based on sputtering. The sputtering target 1 is formed of a gallium nitride-based crystal 2 composed of a plurality of gallium nitride-based single crystal particles 3 oriented in a c-axis orientation in a normal direction to a prescribed surface 2a. The total oxygen concentration of the gallium nitride-based crystal 2 is 150 mass ppm or less, and the measured value of the oxygen concentration of the gallium nitride-based single crystal particles 3 based on a dynamic SIMS method is 2 x 10 17 cm ‑3 or less.

Description

TECHNICAL FIELD

[0001] The present application relates to a sputtering target formed of a gallium nitride-based crystal. BACKGROUND

[0002] As a method of forming a gallium nitride thin film, a sputtering method can be cited. In the sputtering method, a sputtering target using, for example, gallium nitride composed of a raw material has been investigated. As the sputtering target, a target produced by sintering a gallium nitride powder (for example, Patent Literature 1), a polycrystal target produced by a hydride vapor deposition method or the like (for example, Patent Literature 2, Non-Patent Literature 1) has been proposed.

[0003] PRIOR ART DOCUMENTS

[0004] NON-PATENT LITERATURE

[0005] Non-Patent Literature 1: "Synthesis of dense polycrystalline GaN of high purity by the chemical vapor reaction process" (Journal of Crystal Growth Volume 286, Issue 1, 1 January 2006, Pages 50-54)

[0006] PATENT LITERATURE

[0007] Patent Literature 1: WO2016 / 158651

[0008] Patent Literature 2: Japanese Patent Application Publication No. 2018-119171 SUMMARY

[0009] In the case of forming a sintered body obtained from a gallium nitride powder as a sputtering target, the surface of the raw material gallium nitride powder is easily oxidized, and oxygen is released from the target at the start of sputtering, and gallium oxide is easily formed. In addition, there is a problem that since gaps exist between the sintered particles, the density of the target is not easily increased.

[0010] In the case of a sputtering target composed of a polycrystal formed by a hydride vapor deposition method or a flux method, a target with a high density is easily obtained. However, regarding the formation of a gallium nitride polycrystal, a production method is considered in which, for example, as described in Patent Literature 2, a dissimilar material substrate having a large difference in crystal structure and lattice constant from gallium nitride is used as a base substrate, or a film is formed without using a low-temperature buffer layer. In this case, impurities such as oxygen are easily introduced, and it is difficult to obtain a low oxygen concentration required for a sputtering target.

[0011] On the other hand, in Non-Patent Literature 1, it is reported that polycrystalline gallium nitride having a lower oxygen concentration and a high density is synthesized by a vapor phase growth method, i.e., a CVPR method, using a chloride raw material (NH4CI). However, it is considered that the obtained crystal is not oriented in a specific crystal orientation, and the quality is inhomogeneous, and thus, erosion occurs during sputtering (the target is unevenly evaporated), and the target life is shortened.

[0012] The inventors of the present application have also investigated the use of a gallium nitride single crystal substrate as a sputtering target. However, the single crystal substrate is easily cracked during sputtering, and in addition, there is a problem that the film formation speed during sputtering is very slow.

[0013] The object of the present application is to provide a gallium nitride-based gallium sputtering target having a low oxygen concentration and which is not easily cracked during sputtering.

[0014] The present application relates to a sputtering target formed of a gallium nitride-based crystal body composed of a plurality of gallium nitride-based single crystal particles oriented in a c-axis direction in a normal direction to a prescribed surface,

[0015] The sputtering target is characterized in that

[0016] The total oxygen concentration of the gallium nitride-based crystal body is 150 mass ppm or less, and the measured value of the oxygen concentration of the gallium nitride-based single crystal particles based on a dynamic SIMS method is 2 x 10 17 cm -3 or less.

[0017] Effects of the Invention

[0018] The inventors of the present application have used a polycrystalline gallium nitride-based crystal body composed of a plurality of gallium nitride-based single crystal particles oriented in a c-axis direction as a sputtering target. Accordingly, the quality is easily made uniform, erosion during sputtering (a phenomenon in which the target is unevenly evaporated) is suppressed, and the target life is lengthened. On this premise, further, by reducing the total oxygen concentration of the gallium nitride-based crystal body, it is possible to reduce the oxygen concentration of a gallium nitride-based crystal film obtained by sputtering, and in addition, to stabilize it. The inventors of the present application have attempted to further reduce the oxygen concentration of the gallium nitride-based crystal body for the above-mentioned purpose.

[0019] However, it was unexpectedly found that if the oxygen concentration in the gallium nitride-based crystal body is reduced, the sputtering target is easily cracked during sputtering. The reason is not clear, but it is considered that by significantly reducing the oxygen concentration in the gallium nitride-based crystal body, the regularity of the arrangement of the single crystal particles constituting the gallium nitride-based crystal body is increased, and approaches a single crystal, and thus, cracking easily occurs.

[0020] Specifically, by making the total oxygen concentration of the gallium nitride-based crystal 150 mass ppm or less, the oxygen concentration of the gallium nitride-based crystal film obtained by sputtering can be reduced, thereby stabilizing the quality. At the same time, it was found that by keeping the measured value of the oxygen concentration of the gallium nitride-based single crystal grains constituting the gallium nitride-based crystal based on the dynamic SIMS method at 2 x 10 17 cm -3 The above enables suppression of cracking of the sputtering target during sputtering, thereby achieving the present application. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a schematic view showing the sputtering target 1.

[0022] Figure 2 shows the X-ray diffraction pattern obtained in the example. DETAILED DESCRIPTION

[0023] Hereinafter, the present application will be described in detail with appropriate reference to the accompanying drawings.

[0024] As Figure 1 schematically shown, the sputtering target 1 of the present application is formed of a gallium nitride-based crystal 2 composed of a plurality of gallium nitride-based single crystal grains 3 oriented in the c-axis direction in the substantially normal direction N with respect to a prescribed face 2a.

[0025] That is, the gallium nitride-based crystal 2 is a polycrystal composed of a plurality of gallium nitride-based single crystal grains 3. Also, the prescribed face 2a of the gallium nitride-based crystal is used for sputtering. Furthermore, when viewed from the normal direction N with respect to the prescribed face, the crystal orientation L of each gallium nitride-based single crystal grain 3 is substantially the c-axis direction.

[0026] In the preferred embodiment, the half-value width of the (002) plane reflection of the X-ray rocking curve of the gallium nitride-based crystal is 1000 seconds or less. By using a gallium nitride-based crystal having a high c-axis orientation as such, the quality of the obtained gallium nitride-based crystal is further improved. From this viewpoint, the half-value width of the (002) plane reflection of the X-ray rocking curve of the gallium nitride-based crystal is more preferably 800 seconds or less.

[0027] The gallium nitride-based crystal 2 described above can also be regarded as a collection of single crystal grains observed as single crystals when viewed from the normal direction N and observed as columnar structures having grain boundaries when viewed in a cross section in the horizontal direction. Here, the "columnar structure" is defined to include various shapes such as a horizontally long shape, a trapezoidal shape, and a shape obtained by reversing the trapezoidal shape, and is not limited to only a typical vertically long columnar shape. However, as described above, the gallium nitride-based crystal can be a structure having a crystal orientation that is uniform to some extent in the normal direction or a direction similar to the normal direction, and does not necessarily have to be a columnar structure in the strict sense.

[0028] The total oxygen concentration of the gallium nitride-based crystal constituting the sputtering target of the present application is 150 ppm by mass or less, and the measured value of the oxygen concentration of the gallium nitride-based single crystal particle based on the dynamic SIMS method is 2 x 10 17 cm -3 or more.

[0029] Here, the total oxygen concentration of the gallium nitride-based crystal can be measured using elemental analysis, and specifically, can be measured using an oxygen-nitrogen simultaneous analysis device (for example, EMGA-650W (manufactured by HORIBA Corporation)). Here, the total oxygen concentration of the gallium nitride-based crystal is made to be 150 ppm by mass or less, and more preferably 50 ppm by mass or less.

[0030] The lower the total oxygen concentration of the gallium nitride-based crystal, the lower the oxygen concentration of the gallium nitride-based crystal film obtained by sputtering, and the more stable. However, the present inventors have actually attempted to investigate, and when the oxygen concentration of the gallium nitride-based crystal is too low, cracking of the sputtering target tends to occur at the time of sputtering. From the viewpoint of suppressing such cracking of the target at the time of sputtering, it was ascertained that a small amount of oxygen needs to be contained.

[0031] However, in the method of measuring the total oxygen content in the gallium nitride-based crystal using the oxygen-nitrogen simultaneous analysis device, it was ascertained that the measurement limit is approached, and the amount of oxygen required to suppress cracking of the target cannot be captured. Therefore, a method of quantifying the oxygen concentration in each gallium nitride-based single crystal particle using the dynamic SIMS method was attempted to be investigated. This is a method of quantifying the oxygen concentration of a fine region at a prescribed surface of the gallium nitride-based crystal. As a result, it was found that by making the measured value of the oxygen concentration of the gallium nitride-based single crystal particle based on the dynamic SIMS method to be 2 x 10 17 cm -3 or more, the cracking of the target at the time of sputtering can be significantly suppressed.

[0032] Note that the measured value of the oxygen concentration of the gallium nitride-based single crystal particle based on the dynamic SIMS method is preferably 3 x 10 19 / cm 3 or more, and more preferably 1 x 10 19 / cm 3 or more, and particularly preferably 5 x 10 18 / cm 3 or more.

[0033] The measurement of the oxygen concentration of the gallium nitride-based single crystal particle based on the dynamic SIMS method is performed as follows.

[0034] That is, with respect to the prescribed surface of the gallium nitride-based crystal, the oxygen concentration is measured using the dynamic SIMS for a square field of 200 μm x 200 μm. This measurement is performed for 9 fields, and the average value is calculated.

[0035] Gallium nitride-based crystalline body x Ga 1-x N, In x Ga 1-x N indicates, in this case, x is preferably 0.5 or less, more preferably 0.2 or less. x can be 0.

[0036] In the preferred embodiment, the gallium nitride-based crystalline body has a measured value of relative density based on the Archimedes method of 98.0% or more, preferably 99.0% or more, more preferably 99.5% or more. With such a high density of the gallium nitride-based crystalline body, erosion and oxidation are less likely to occur during sputtering.

[0037] In the preferred embodiment, the sputtering target has a thickness of 1 mm or more. The thickness is preferably 2 mm or more, more preferably 4 mm or more. In practice, 8 mm or less is preferable.

[0038] In the preferred embodiment, the sputtering target has a diameter of 50 mm or more. The diameter is preferably 75 mm or more, more preferably 100 mm or more. In practice, 160 mm or less is preferable.

[0039] In the preferred embodiment, the sputtering target does not have light transmittance. That is, the sputtering target has been colored. It is believed that this coloring occurs due to light absorption by defects such as nitrogen vacancies. By having such defects, the film formation rate during sputtering is increased.

[0040] In the preferred embodiment, the gallium nitride-based single crystal particle has a measured value of carbon concentration based on the dynamic SIMS method of 1 x 10 16 cm -3 or less. Thereby, the quality of the gallium nitride-based crystalline body produced by sputtering is further improved.

[0041] In the preferred embodiment, the gallium nitride-based single crystal particle has a measured value of germanium concentration based on the dynamic SIMS method of 1 x 10 18 cm -3 or less. Thereby, a sputtering target having electrical conductivity in which the resistivity of the target material is somewhat reduced can be obtained. From this viewpoint, the gallium nitride-based single crystal particle has a measured value of germanium concentration based on the dynamic SIMS method of 5 x 10 18 cm -3 or less is more preferable.

[0042] From the viewpoint of preventing erosion, it is preferable to perform polishing processing on the prescribed surface of the gallium nitride-based crystalline body constituting the sputtering target. From this viewpoint, the prescribed surface of the gallium nitride-based crystalline body preferably has an arithmetic mean roughness Ra of 0.1 μm or less.

[0043] The gallium nitride-based crystal constituting the sputtering target can be doped with an n-type dopant and / or a p-type dopant, and as such a dopant, zinc, calcium, iron, beryllium, magnesium, strontium, cadmium, scandium, silicon, germanium, tin can be cited.

[0044] As the sputtering method using the sputtering target of the present application, a DC sputtering method, an RF sputtering method, an AC sputtering method, a DC magnetron sputtering method, an RF magnetron sputtering method, an ion beam sputtering method, or the like can be appropriately selected.

[0045] The gas pressure at the time of sputtering is preferably 0.05 to 7.0 Pa. In addition, the gas at the time of sputtering is preferably a mixed gas of argon (Ar) and nitrogen (N2).

[0046] In addition, the temperature at the time of sputtering is preferably 100 to 1000°C.

[0047] Example

[0048] (Example 1)

[0049] (Making of sputtering target)

[0050] A gallium nitride crystal was made substantially in accordance with the method described in WO 2017-145803A1.

[0051] Specifically, on an oriented polycrystalline alumina sinter having a diameter of 2 inches and a thickness of 0.5 inches, a seed film containing gallium nitride having a thickness of 2 μm was formed by the MOCVD method, to obtain a seed substrate.

[0052] The seed substrate was disposed in an alumina crucible in a glove box under a nitrogen atmosphere. Next, metallic gallium and metallic sodium were filled in the crucible at Ga / Ga+Na (mol%) = 30 mol%, and covered with an alumina plate. The crucible was put in a stainless inner container, and further, put in a stainless pressure-resistant container capable of accommodating the inner container, and closed with a container lid with a nitrogen introduction tube attached. The pressure-resistant container was disposed on a rotary stage provided in a heating section in a crystal manufacturing apparatus that was pre-vacuum baked, and the pressure-resistant container was closed with a pressure-resistant container lid.

[0053] ​Next, the inside of the pressure-resistant container was evacuated to 0.1 Pa or less by a vacuum pump. Then, the upper heater, the middle heater, and the lower heater were adjusted to heat the temperature of the heating space to 880°C, while nitrogen was introduced from a nitrogen gas cylinder to 4.0 MPa, and the outer container was rotated clockwise and counterclockwise at a certain cycle at 20 rpm around the central axis. The acceleration time = 15 seconds, the holding time = 600 seconds, the deceleration time = 15 seconds, and the stop time = 1 second. Then, the state was maintained for 10 hours. After that, the upper heater, the middle heater, and the lower heater were adjusted so that the temperature of the heating space was 790°C, and the pressure-resistant container was rotated clockwise and counterclockwise at a certain cycle at a rotation speed of 20 rpm. The acceleration time = 8 seconds, the holding time = 300 seconds, the deceleration time = 8 seconds, and the stop time = 0.5 second. Then, the state was maintained for 200 hours to grow the gallium nitride crystal. However, in the present embodiment, the oxygen source in each container was excluded as much as possible, and the growth temperature of the gallium nitride crystal was reduced to, for example, 800°C or less, and the measured value based on dynamic SIMS of the total oxygen concentration of the gallium nitride crystal and the oxygen concentration of the gallium nitride single crystal particle was adjusted by periodically changing the rotation direction of the pressure-resistant container.

[0054] Next, after natural cooling to room temperature and depressurization to atmospheric pressure, the lid of the pressure-resistant container was opened, and the crucible was taken out therefrom. The solidified metal zinc in the crucible was removed, and the gallium nitride crystal ingot peeled from the seed substrate without cracks was recovered.

[0055] The surface of the ingot was polished to obtain a sputtering target formed of the gallium nitride crystal having a diameter of 4 inches and a thickness of 2 mm. However, since the concentration of each element was measured by destructive inspection, the sample for measuring the concentration of each element and the sample for sputtering experiment were prepared separately and plural.

[0056] (Measurement of the concentration of each element)

[0057] The sputtering target produced was cut into a square of 20 mm, and the oxygen concentration was measured by an oxygen-nitrogen simultaneous analysis device (EMGA-650W (manufactured by HORIBA Corporation)), and as a result, 150 mass ppm was obtained.

[0058] In addition, with respect to a prescribed surface of the sputtering target produced, the oxygen concentration of a region of 200 μm x 200 μm was measured at 9 points by dynamic SIMS, and the average value was calculated, and as a result, 2.0 x 10 17 / cm 3 .

[0059] The difference between the total oxygen concentration measured by the oxygen-nitrogen simultaneous analysis and the oxygen concentration measured by the dynamic SIMS is considered to reflect that the speed of the facet growth, which has a small amount of oxygen introduced by crystalline growth at a lower temperature than usual, is increased, thereby generating the oxygen concentration difference between the c-plane growth portion and the facet growth portion.

[0060] Further, the carbon concentration measured by the dynamic SIMS was 5 x 10 15 / cm 3 or less at the 9 measurement points.

[0061] Further, the germanium concentration measured by the dynamic SIMS was 2 x 10 16 / cm 3 or less at the 9 measurement points.

[0062] (XRC-FWHM measurement)

[0063] A 2θ-ω measurement was performed on the prescribed surface of the sputter target produced using an XRD device (D8-DISCOVER manufactured by Bruker-AXS) using Cu Kα rays as the X-ray source. A Ge (022) asymmetric reflection monochromator and a slit of w 1 mm x h 10 mm were used for the incident side optical system. The 2θ range was from 20° or more to 80° or less, and the measurement was performed at a measurement interval of 0.01° and a measurement time of 0.5 seconds. Figure 2 is a graph showing the results of the 2θ-ω measurement.

[0064] As shown in Figure 2 , only the diffraction peaks of the (002) plane and the (004) plane equivalent to the c-plane were confirmed. Further, the (002) reflection of the X-ray rocking curve was measured, and the half-value width was calculated, and as a result, 684 arcsec was obtained. From the above results, it was found that the gallium nitride-based single crystal particles were strongly oriented in the c-axis direction.

[0065] (Sputtering test)

[0066] A sputter target was joined to a heated copper plate (backing plate) using metallic indium, thereby obtaining a joined body.

[0067] Using the joined body, a gallium nitride crystal film was formed by sputtering in an RF sputtering device, in which the chamber atmosphere was set to Ar 20 seem and N2 100 seem, the chamber pressure was set to 0.25 Pa, a 2-inch sapphire substrate was used as the substrate, the target-substrate distance was set to 150 mm, and the temperature of the substrate was set to 500°C. Further, the appearance of the sputter target after sputtering was examined.

[0068] Results: After sputtering, the sapphire substrate was removed, revealing a uniform gallium nitride (GaN) crystalline film with a thickness of 1 μm. SIMS analysis of the GaN crystalline film showed an oxygen concentration of 1 × 10⁻⁶. 17 / cm 3 the following.

[0069] In addition, no abnormalities such as cracking or fissures were observed in the appearance of the sputtering target after film formation and sputtering.

[0070] The measurement results from Example 1 are summarized in Table 1.

[0071] (Comparative Example 1)

[0072] (Construction of a splash target)

[0073] In diameter An inch-thickness oriented polycrystalline alumina sintered body is used to form a 2μm thick seed film of gallium nitride using the MOCVD method, thus obtaining a seed substrate.

[0074] The seed substrate was placed in an alumina crucible within a glove box under a nitrogen atmosphere. Next, metallic gallium and metallic sodium were filled into the crucible at a ratio of Ga / Ga+Na (mol%) = 30 mol%, and the crucible was covered with an alumina plate.

[0075] The crucible is placed in a stainless steel inner container, and then placed in a stainless steel pressure vessel capable of housing the inner container, and sealed with a container lid equipped with a nitrogen inlet pipe. The pressure vessel is then placed on a rotating table in the heating section of a pre-vacuum-calcined crystallization apparatus, and the pressure vessel is sealed with a lid.

[0076] Next, the pressure vessel was evacuated to below 0.1 Pa using a vacuum pump. Then, the upper, middle, and lower heaters were adjusted to heat the space to 880°C, while nitrogen was introduced from a nitrogen cylinder to a pressure of 4.0 MPa. The outer vessel was then rotated around its central axis at a fixed cycle of 20 rpm clockwise and counterclockwise. The acceleration time was 15 seconds, the holding time was 600 seconds, the deceleration time was 15 seconds, and the stopping time was 1 second. This state was maintained for 200 hours. Afterward, the vessel was allowed to cool naturally to room temperature and the pressure reduced to atmospheric pressure. The pressure vessel was then opened, and the crucible was removed. The gallium nitride crystal ingot peeled off from the seed substrate, but cracks were observed.

[0077] (Comparative Example 2)

[0078] Under the same conditions as Comparative Example 1, the holding time was set to 60 hours to cultivate GaN crystals. As a result, a crack-free gallium nitride crystal ingot that peeled off from the seed substrate was successfully fabricated. The specified surface of the gallium nitride crystal ingot was ground to obtain a sputtering target with a thickness of 0.8 mm.

[0079] The sputtering target produced was cut into a 20 mm square, and after polishing the surface, the total oxygen concentration was measured using an oxygen-nitrogen simultaneous analysis device (EMGA-650W (manufactured by HORIBA Corporation)), and the result was below the lower limit of measurement (10 mass ppm).

[0080] In addition, the oxygen concentration of the sputtering target produced was measured at 9 points using dynamic SIMS, and the result was 3 x 10 16 cm -3 or less.

[0081] Further, X-ray diffraction measurement was performed in the same manner as in Example 1, and as a result, only diffraction peaks of (002) and (004) planes were confirmed. Further, (002) reflection of the X-ray rocking curve was measured, and the half-value width was calculated, and as a result, 83 arcsec was obtained.

[0082] (Sputtering Experiment)

[0083] Sputtering was performed in the same manner as in Example 1, and as a result, cracking of the target occurred during sputtering, and sputtering film formation was discontinued.

[0084] (Examples 2 to 5)

[0085] In the same manner as in Example 1, each of the gallium nitride crystal ingots and sputtering targets of Examples 2 to 5 was produced as shown in Table 1. However, on the basis of Example 1, the oxygen concentration was adjusted by adjusting the temperature of the heating space at the time of maintaining for 200 hours.

[0086] Note that, in Example 5, germanium tetrachloride was filled in the alumina crucible together with metallic gallium and metallic sodium at Ge / Ga+Na+Ge (mol%) = 0.6 mol%.

[0087] The sputtering targets of each of the examples were measured for each element concentration in the same manner as in Example 1, X-ray diffraction measurement was performed, and in addition, a sputtering experiment was performed. The results are shown in Table 1.

[0088] As a result, after the sputtering treatment, the sapphire substrate was taken out, and a gallium nitride crystal film having a thickness of 1 μm was uniformly formed. SIMS analysis was performed on the gallium nitride crystal film, and as a result, the oxygen concentration was 2 x 10 17 / cm 3 or less.

[0089] In addition, regarding the appearance of the sputtered target after film formation, no abnormality such as cracking or crazing occurred.

[0090] (Comparative Example 3)

[0091] Gallium nitride crystal ingots and sputtering targets were prepared in the same manner as in Comparative Example 2. However, based on Comparative Example 2, germanium tetrachloride was added together with metallic gallium and metallic sodium in an alumina crucible at a ratio of Ge / Ga+Na+Ge (mol%) = 0.6 mol%.

[0092] For the sputtering target of Comparative Example 3, the concentrations of each element were measured and X-ray diffraction measurements were performed in the same manner as in Example 1. In addition, sputtering experiments were conducted. The results are shown in Table 1.

[0093] In addition, sputtering was performed in the same manner as in Example 1. As a result, the target cracked during sputtering, and the sputtering film formation was stopped.

[0094] (Comparative Example 4)

[0095] Based on the description in paragraph

[0067] of WO2016-158651A1, a gallium nitride sintered body was fabricated as a sputtering target.

[0096] That is, use A graphite mold was used to press 200g of gallium nitride powder with an average particle size of 1μm at 1100℃ for 3 hours with a surface pressure of 200kgf / cm². 2 The conditions are suitable for hot pressing and firing.

[0097] The sintered body obtained in this way is ground to obtain a sputtering target with a thickness of 2.0 mm.

[0098] The total oxygen concentration of the sputtering target in this example is 800 ppm by mass. Furthermore, the X-ray diffraction results show a non-oriented state.

[0099] In addition, sputtering experiments were performed in the same manner as in Example 1. Results: After sputtering, the sapphire substrate was removed, revealing a uniform gallium nitride (GaN) crystal film with a thickness of 1 μm. SIMS analysis of the GaN crystal film showed an oxygen concentration of 2 × 10⁻⁶. 20 / cm 3 .

[0100] In addition, no abnormalities such as cracking or fissures were observed in the appearance of the target after sputtering and film formation.

[0101] [Table 1]

[0102]

Claims

1. A sputtering target formed of a gallium nitride-based crystal composed of a plurality of gallium nitride-based single crystal particles oriented in a c-axis orientation in a normal direction to a prescribed surface, the sputtering target is characterized in that The total oxygen concentration of the gallium nitride-based crystal is 150 mass ppm or less, and the measured value of the oxygen concentration of the gallium nitride-based single crystal particle based on a dynamic SIMS method is 2 x 10 17 cm -3 or less.

2. The sputtering target according to claim 1, characterized in that a measured value of a relative density of the gallium nitride-based crystal based on an Archimedes method is 98.0% or more.

3. The sputtering target according to claim 1, characterized in that a half-value width of (002) plane reflection of an X-ray rocking curve of the gallium nitride-based crystal is 1000 seconds or less.

4. The sputtering target according to any one of claims 1 to 3, characterized in that a thickness of the sputtering target is 1 mm or more.

5. The sputtering target according to any one of claims 1 to 3, characterized in that a diameter of the sputtering target is 50 mm or more.

6. The sputtering target according to any one of claims 1 to 3, characterized in that the gallium nitride-based crystal does not have a light-transmitting property.

7. The sputtering target according to any one of claims 1 to 3, characterized in that The measured value of the carbon concentration of the gallium nitride-based single crystal particle based on the dynamic SIMS method was 1 x 10 16 cm -3 The following.

8. The sputtering target according to any one of claims 1 to 3, characterized in that The measured value of the germanium concentration of the gallium nitride-based single crystal particle based on the dynamic SIMS method was 1 x 10 18 cm -3 or more above.

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