JP6831536B2 - Manufacturing method of aluminum nitride crystal - Google Patents

Description

The present invention relates to an aluminum nitride crystal and a method for producing the same.

International Publication No. 2010/084863 (Patent Document 1) describes a crucible for arranging raw materials inside in order to produce a nitride semiconductor crystal having durability and suppressing contamination of impurities from the outside of the crucible. A heating portion arranged on the outer periphery of the crucible to heat the inside of the crucible and a covering portion arranged between the crucible and the heating portion are provided, and the covering portion is formed on the side facing the crucible and is a raw material. Nitride semiconductor crystal containing a first layer made of a metal having a melting point higher than the melting point of the first layer and a second layer made of a carbide of a metal formed on the outer peripheral portion of the first layer and forming the first layer. The production apparatus of the above, a method for producing a nitride semiconductor crystal using the same, and a nitride semiconductor crystal produced by them are disclosed.

International Publication No. 2010/084863

In the nitride semiconductor crystal manufacturing apparatus and manufacturing method disclosed in International Publication No. 2010/084863 (Patent Document 1), since there is a covering portion arranged between the pit and the heating portion, the nitride to be manufactured is produced. As the size of the product semiconductor crystal increases, the inner diameter of the coating part increases, the weight of the coating part increases due to the increase in size of the manufacturing equipment, and the coating part deteriorates severely due to repeated elevating and lowering temperatures. There was a problem in the reproducibility of the nitride semiconductor crystal.

Therefore, it is an object of the present invention to provide a high crystal quality aluminum nitride crystal having a small amount of silicon and carbon, which are impurity elements, which can be produced without using a production apparatus having a complicated structure such as a coating portion, and a method for producing the same.

Aluminum nitride crystal according to one aspect of the present invention, as the impurity element, 1 × and 10 ¹⁹ cm ^-3 than silicon, 1 × 10 ¹⁹ cm ^-3 less carbon, 1 × 10 ¹⁶ cm ^-3 or more tantalum And, including.

In the method for producing an aluminum nitride crystal according to one aspect of the present invention, a pit for arranging an aluminum nitride raw material and a base substrate inside, a heating body for heating the pit, and a pit and a heating body are arranged inside. A step of preparing a manufacturing apparatus equipped with a reaction vessel for silicon, a step of arranging an aluminum nitride raw material and a base substrate in a pit, and a step of sublimating the aluminum nitride raw material to grow aluminum nitride crystals on the base substrate. , The pit is coated with at least one of Ta ₂ C and Ta ₅ Si ₃ , and the heating body and reaction vessel do not contain silicon and carbon.

According to the above, it is possible to provide an aluminum nitride crystal having high crystal quality and low in silicon and carbon, which are impurity elements, which can be produced without using a production apparatus having a complicated structure such as a coating portion, and a method for producing the same.

FIG. 1 is a flowchart showing a method for producing an aluminum nitride crystal according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing an example of a manufacturing apparatus used for manufacturing an aluminum nitride crystal according to an aspect of the present invention.

[Explanation of Embodiments of the Present Invention]
First, embodiments of the present invention will be listed and described.

[1] Aluminum nitride crystal according to an embodiment of the present invention, as the impurity element, and 1 × 10 ¹⁹ cm ^-3 than silicon, and less than 1 × 10 ¹⁹ cm ^-3 carbon, 1 × 10 ¹⁶ cm ^- Includes ³ or more tantalum and. The aluminum nitride crystal of the present embodiment has high crystal quality because of its low content of silicon and carbon.

[2] The aluminum nitride crystal according to the present embodiment can further contain oxygen of less than 1 × 10 ¹⁷ cm ^-3 as an impurity element. Such aluminum nitride crystals have a high thermal conductivity and a high Young's modulus due to the low oxygen content.

[3] In the aluminum nitride crystal according to the present embodiment, the half width of the maximum diffraction peak for the (0002) plane in the rocking curve measurement of X-ray diffraction can be set to less than 100 arcsec. Such an aluminum nitride crystal has a high crystal quality because the half width of the maximum diffraction peak is small.

[4] The aluminum nitride crystal according to the present embodiment can have an arithmetic average roughness Ra of the main surface of less than 1 nm. Since such an aluminum nitride crystal has a small arithmetic mean roughness Ra of the main surface, it is possible to form a high-quality epitaxial film by using such a main surface, and also to form a strong bond in bonding with different materials. Is possible.

[5] The aluminum nitride crystal according to this embodiment, as the impurity element, 1 and silicon less than × 10 ¹⁹ cm ^-3, and less than 1 × 10 ¹⁹ cm ^-3 carbon, less than 1 × 10 ¹⁷ cm ^-3 It contains oxygen and tantalum of 1 × 10 ¹⁶ cm ^-3 or more, and the half-value width of the maximum diffraction peak for the (0002) plane in the rocking curve measurement of X-ray diffraction is set to less than 100 arcsec, and the arithmetic average roughness of the main surface is set. Ra can be less than 1 nm. Such aluminum nitride crystals have high crystal quality, particularly high thermal conductivity and high Young's modulus.

[6] In the method for producing an aluminum nitride crystal according to an embodiment of the present invention, a pit for arranging an aluminum nitride raw material and a base substrate inside, a heating body for heating the pit, and a pit and a heating body are used. A step of preparing a manufacturing apparatus including a reaction vessel for arranging inside, a step of arranging an aluminum nitride raw material and a base substrate in a pit, and a step of sublimating the aluminum nitride raw material to form an aluminum nitride crystal on the base substrate. With a step of growing, the pit is coated with at least one of Ta ₂ C and Ta ₅ Si ₃ , and the heater and reaction vessel are silicon and carbon free. The method for producing an aluminum nitride crystal of the present embodiment can stably produce an aluminum nitride crystal having a low content of silicon and carbon and high crystal quality with good reproducibility.

[Details of Embodiments of the present invention]
<Aluminum nitride crystal>
AlN (aluminum nitride) crystal according to the present embodiment, as the impurity element, and 1 × 10 ¹⁹ cm ^-3 of less than Si (silicon), less than 1 × 10 ¹⁹ cm ^-3 and C (carbon), 1 × 10 Includes Ta (tantal) of ¹⁶ cm ^-3 or more. The AlN crystal of the present embodiment has high crystal quality because the Si and C contents are as small as less than 1 × 10 ¹⁹ cm ^-3, respectively.

(Silicon content)
The content of Si (silicon) in the AlN crystal is less than 1 × 10 ¹⁹ cm ^-3 , preferably 1 × 10 ¹⁸ cm ^-3 or less, preferably 1 × 10 ¹⁷ cm ^-3 or less, from the viewpoint of high crystal quality. Is more preferable. The content of Si in the AlN crystal is measured by dynamic SIMS (secondary ion mass spectrometry).

(Carbon content)
The content of C (carbon) in the AlN crystal is less than 1 × 10 ¹⁹ cm ^-3 , preferably 1 × 10 ¹⁸ cm ^-3 or less, preferably 1 × 10 ¹⁷ cm ^-3 or less, from the viewpoint of high crystal quality. Is more preferable. The C content in the AlN crystal is measured by dynamic SIMS.

(Tantalum content)
The Ta (tantalum) content in the AlN crystal is based on the manufacturing method described later and has almost no adverse effect on the semiconductor characteristics of the AlN crystal. Therefore, the Ta content is 1 × 10 ¹⁶ cm ^-3 or more. There may be. The content of Ta in the AlN crystal is preferably 1 × 10 ¹⁹ cm ^-3 or less, and more preferably 1 × 10 ¹⁸ cm ^-3 or less, from the viewpoint of maintaining high crystal quality. The Ta content in the AlN crystal is measured by dynamic SIMS.

(Oxygen content)
The content of O (oxygen) in the AlN crystal is preferably less than 1 × 10 ¹⁷ cm ^-3 from the viewpoint of high thermal conductivity and Young's modulus. The content of O in the AlN crystal is measured by dynamic SIMS.

(Half width of maximum diffraction peak in X-ray diffraction locking curve measurement)
From the viewpoint of high crystal quality, the full width at half maximum of the maximum diffraction peak for the (0002) plane in the X-ray diffraction locking curve measurement is preferably less than 100 arcsec, and more preferably 70 arcsec or less.

(Arithmetic Mean Roughness Ra on the main surface)
The Arithmetic Mean Roughness Ra of the main surface of the AlN crystal is preferably less than 1 nm, preferably 0.7 nm or less, from the viewpoint of forming a high-quality epitaxial film and / or forming a strong bond with different materials. More preferred. Here, the arithmetic mean roughness Ra of the main surface refers to the arithmetic average roughness Ra defined in JIS B0601: 2013, and is measured by an AFM (atomic force microscope).

(Thermal conductivity)
The AlN crystal preferably has a thermal conductivity of 150 W · m ^-1 · K ^-1 or more, preferably 160 W · m ^-1 · K, from the viewpoint of enhancing heat dissipation when manufacturing a light emitting device or an electronic device using the AlN crystal as a substrate. ^-1 or more is more preferable. The thermal conductivity of AlN crystals can be increased by reducing the O content. Thermal conductivity is measured by laser flash method.

(Young's modulus)
The Young's modulus of the AlN crystal is preferably 150 GPa or more, more preferably 170 GPa or more, from the viewpoint of enhancing the robustness when producing a light emitting device or an electronic device using the AlN crystal as a substrate. The Young's modulus of the AlN crystal can be increased by reducing the O content. Young's modulus is measured by the resonance method.

<Manufacturing method of aluminum nitride crystal>
With reference to FIGS. 1 and 2, the method for producing an AlN (aluminum nitride) crystal according to the present embodiment is for heating the pit 23 for arranging the AlN raw material 15 and the base substrate 10 inside, and the pit 23 for heating the pit 23. Step S10 for preparing the manufacturing apparatus 20 including the heating body 25, the pit 23, and the reaction vessel 21 for arranging the heating body 25 inside, and arranging the AlN raw material 15 and the base substrate 10 in the pit 23. A step S20 and a step S30 of sublimating the AlN raw material 15 to grow the AlN crystal 11 on the base substrate 10 are provided, and the 坩 堝 23 is covered with at least one of Ta ₂ C and Ta ₅ Si ₃ . The heating body 25 and the reaction vessel 21 do not contain Si (silicon) and C (carbon). The method for producing an aluminum nitride crystal of the present embodiment can stably produce an aluminum nitride crystal having a low Si and C content and high crystal quality with good reproducibility.

(Process to prepare manufacturing equipment)
In the step S10 of preparing the manufacturing apparatus, the crucible 23 for arranging the AlN raw material 15 and the base substrate 10 inside, the heating body 25 for heating the crucible 23, and the crucible 23 and the heating body 25 are arranged inside. A manufacturing apparatus 20 including a reaction vessel 21 for the purpose is prepared.

The crucible 23 has Ta ₂ C and Ta ₂ C from the viewpoint of stably growing an AlN crystal having high crystal quality and suppressing the uptake of O during the growth of the AlN crystal to reduce the content of O in the AlN crystal. It is coated with at least one of Ta ₅ Si ₃ . The thickness of the Ta ₂ C coating layer and the Ta ₅ Si ₃ coating layer is not particularly limited, but from the viewpoint of stably growing an AlN crystal having high crystal quality and reducing the content of O in the growing AlN crystal. From the viewpoint of the above, 100 μm or more and 1000 μm or less are preferable, and 200 μm or more and 800 μm or less are more preferable. Here, whether the material forming the coating layer is Ta ₂ C or Ta ₅ Si ₃ is identified by X-ray diffraction. The thickness of the coating layer is measured by the X-ray reflectivity method.

The method for forming the Ta ₂ C coating layer that covers the surface of the crucible 23 is not particularly limited. For example, a carbon (C) source is introduced into a crucible made of Ta or a Ta alloy and 0.15 Pa or more and 0.30 Pa or less. Heat treatment is performed at an atmospheric temperature of 2050 K or more and 2600 K or less in the vacuum atmosphere of. Here, the carbon source is not particularly limited, and amorphous carbon, graphite, or the like is used. In this way, Ta steel or Ta on the surface of the alloy crucible Ta ₂ C coating layer and TaC coating layer are formed in this order. Then, the Ta ₂ C coating layer located on the outermost surface is removed by grinding, polishing, and / or etching, so that the Ta ₂ C coating layer appears on the outermost surface.

The method for forming the Ta ₅ Si ₃ coating layer that covers the surface of the crucible 23 is not particularly limited, and for example, the Ta ₂ C coating layer and the Ta C coating layer are formed on the surface of the crucible made of Ta or Ta alloy by the above method. It is formed in this order. Next, the Ta ₂ C coating layer and the Ta C coating layer are heat-treated at an atmospheric temperature of 2275 K in a vacuum atmosphere of 10 Pa or less by introducing a silicon (Si) source into the crucible formed in this order. Here, the silicon source is not particularly limited, and amorphous silicon, polycrystalline silicon, single crystal silicon, and the like are used. Thus, is formed Ta ₅ Si ₃ coating layer on the TaC coating layer, Ta ₅ Si ₃ coating layer appears on the outermost surface.

The crucible 23 preferably has an exhaust port 23c. Impurities inside the crucible 23 can be removed through the exhaust port 23c, and the mixing of impurities into the AlN crystal can be reduced.

The heating body 25 and the reaction vessel 21 are made of a material that does not contain Si (silicon) and C (carbon) from the viewpoint of stably growing AlN crystals having high crystal quality. The term "free of Si and C" means that it is substantially free of Si and C except for those contained as unavoidable impurities. Specifically, the respective contents of Si and C are 1 × 10 ¹⁷ It means that it is less than cm ^-3 . The contents of Si and C contained as unavoidable impurities in the heating body 25 and the reaction vessel 21 are not particularly limited, but can be measured by dynamic SIMS.

Examples of the material for forming the heating body 25 include W (tungsten) and Ta (tantalum) as materials that do not contain Si and C, and graphite and the like as materials that contain C. Examples of the material forming the reaction vessel 21 include stainless steel, alumina (Al ₂ O ₃ ), spinel (Mg Al ₂ O ₄ ) as a material containing no Si and C, and quartz as a material containing Si. (SiO _2), mullite _{(3Al 2 O 3 · 2SiO 2} ~2Al 2 O 3 · SiO 2) , and the like.

At the end of the reaction vessel 21, a carrier gas introduction port 21a and a carrier gas discharge port 21b for flowing a carrier gas to the outside of the crucible 23 of the reaction vessel 21, and a temperature of the lower surface and the upper surface of the crucible 23 are measured. A radiation thermometer 29 is provided. By flowing the carrier gas, impurities in the reaction vessel 21 can be removed, and the mixing of impurities in the AlN crystal can be reduced. As the carrier gas, N ₂ (nitrogen) gas is suitable.

In the manufacturing apparatus 20, the method of heating the heating body 25 for heating the crucible 23 is not particularly limited, and is an induction heating method using a high-frequency induction heating coil (not shown) and a resistor using a resistor (not shown). A heating method and the like are preferable.

(Process of arranging aluminum nitride raw material and base substrate)
In the step S20 of arranging the AlN (aluminum nitride) raw material and the base substrate, the AlN raw material 15 and the base substrate 10 are arranged in the crucible 23.

From the viewpoint of reducing contamination of the AlN crystal 11 grown on the base substrate 10, the AlN raw material 15 is not particularly limited, but is preferably an AlN polycrystal, and is separately used using the same manufacturing apparatus 20. It is more preferable that the AlN polycrystal is obtained by sublimating the AlN raw material by arranging only the AlN raw material in the pit and raising the temperature to 2300K to 2600K. The purity of the AlN raw material 15 is not particularly limited, but is preferably 99.99% by mass or more, more preferably 99.999% by mass or more, from the viewpoint of suppressing contamination with the grown AlN crystal 11. The purity of the AlN raw material 15 is measured by ICP-MS (inductively coupled plasma-mass spectrometry).

The base substrate 10 is not particularly limited, but a 4H-SiC (silicon carbide) substrate, a 6H-SiC substrate, an AlN template on an Al ₂ O ₃ substrate, or the like is preferable from the viewpoint of growing an AlN crystal 11 having high crystal quality. Can be mentioned.

The arrangement structure of the AlN raw material 15 and the base substrate 10 is not particularly limited, and may be a face-down structure (see FIG. 2) in which the AlN raw material 15 is arranged in the lower part of the crucible 23 and the base substrate 10 is arranged in the upper part. , A face-up structure (not shown) may be used in which the base substrate is arranged in the lower part of the crucible and the AlN raw material is arranged in the upper part.

(Step of growing aluminum nitride crystals)
In the step S30 for growing AlN (aluminum nitride) crystals, the AlN raw material 15 is sublimated to grow AlN crystals on the base substrate 10. From the viewpoint of efficiently growing AlN crystals with high crystal quality, the temperature on the AlN raw material 15 side of the pit 23 is set to 2200K to 2500K, and the temperature on the base substrate 10 side of the pit 23 is set to AlN. It is preferable that the temperature is 1K to 100K lower than the temperature on the raw material 15 side. Further, from the viewpoint of reducing the mixing of impurities into the AlN crystal, when the AlN crystal grows, N ₂ gas is used as a carrier gas on the outside of the crucible 23 in the reaction vessel 21, and the gas partial pressure is about 101.3 hPa to 1013 hPa. It is preferable to flow so that

(Example I)
In Example I, the following studies were carried out in order to select a suitable coating material for the crucible surface in order to stably grow AlN crystals having high crystal quality with good reproducibility.

First, three cylindrical Ta crucibles capable of accommodating a wafer having a diameter of 2 inches were prepared. By introducing graphite as a carbon source into the first Ta crucible and heat-treating it at an ambient temperature of 2300 K in a vacuum atmosphere of 0.20 Pa, the surface of the Ta crucible is coated with a Ta ₂ C layer having a thickness of 100 μm and a thickness of 100 μm. The TaC crucible was coated with a 100 μm TaC layer in this order to form a TaC crucible in which the outermost surface of the Ta crucible was coated with a TaC layer having a thickness of 100 μm (Example I-1). The second of Ta crucible, after forming the a TaC crucible coated in this order in the TaC layer of Ta ₂ C layer and thickness 100 [mu] m of the surface thickness of 100 [mu] m of Ta crucible in the same manner, a thickness of 100 [mu] m TaC by removing the layers by grinding and polishing to expose the surface of the Ta ₂ C layer of the thickness of 100 [mu] m, forming a Ta ₂ C crucible outermost surface covered with Ta ₂ C layer having a thickness of 100 [mu] m of Ta crucible (Example I-2). In the third Ta crucible, a Ta C crucible whose surface is coated with a Ta ₂ C layer having a thickness of 100 μm and a Ta C layer having a thickness of 100 μm in this order is formed in the same manner as above, and then amorphous silicon is used as a silicon source. Was introduced and heat-treated at an ambient temperature of 2275 K in a vacuum atmosphere of 1.0 Pa to form a Ta ₅ Si ₃ crucible whose outermost surface was covered with a Ta ₅ Si ₃ layer having a thickness of 100 μm. (Example I-3).

Next, in each of the crucibles obtained in Examples I-1 to I-3, a 2 inch diameter 4H-SiC substrate, which is a base substrate, is placed on the upper part which becomes a low temperature part, and in the lower part which becomes a high temperature part. AlN raw material powder having a purity of 99.99% by mass was placed. The molar ratio of each component at the time of placement (initial) was AlN: SiC: α-Al ₂ O ₃ (oxidizing component in the AlN raw material): coating material = 3: 1: 0.03: 10.

Each crucible on which the base substrate and the AlN raw material powder are arranged and a W (tungsten) heater are placed in a TaC reaction vessel, and N ₂ gas is introduced into the reaction vessel as a carrier gas to create an atmospheric pressure. Was maintained at 90 kPa, the temperature was raised to 2500 K, and the temperature was maintained for 20 hours to grow AlN crystals on the underlying substrate.

Then, the crucible containing the coating material, the remaining AlN raw material powder, the base substrate, and the grown AlN crystals were crushed by a ball mill. The type and mole fraction of each component of the obtained powder were identified and calculated by XRD (X-ray diffraction). The results are summarized in Table 1.

With reference to Table 1, in Example I-1, 3C-SiC was produced. From this, it is considered that in the TaC pit whose surface is coated with TaC, a 3C-SiC phase (cubic crystal) having a different crystal system from the AlN crystal (hexagonal crystal) is generated, so that the crystal quality of the AlN crystal is deteriorated. It was. In Example I-2, TaC was generated. From this, in the Ta ₂ C crucible whose surface is coated with Ta ₂ C, C generated by partial decomposition of the 4H-SiC substrate which is the base substrate is absorbed, and a part of Ta ₂ C becomes Ta C. It was considered that AlN crystals having high crystal quality could be stably grown with good reproducibility. Furthermore, it was expected that Ta generated when a part of Ta ₂ C became Ta C could be reduced by reducing oxide impurities (for example, α-Al ₂ O ₃ ) in the AlN raw material. In Example I-3, Ta ₂ C and Ta Si ₂ were produced. Therefore, the Ta ₅ Si ₃ crucible surface covered with Ta ₅ Si _3, absorbs C generated by some decomposition of 4H-SiC substrate as the base substrate, a part of Ta ₅ Si ₃ is Ta _Since it became ₂ C, it was considered that an AlN crystal having high crystal quality could be stably grown with good reproducibility. Furthermore, Ta generated when a part of Ta ₅ Si ₃ becomes Ta ₂ C or Ta Si ₂ can be reduced by reducing oxide impurities (for example, α-Al ₂ O ₃ ) in the AlN raw material. I was expected. From the above results, it was found that the coating materials for the crucible, in which AlN crystals with high crystal quality can grow stably and with good reproducibility, are Ta ₂ C and Ta ₅ Si ₃ .

(Example II)
In Example II and the following Example III, the following studies were carried out in order to select suitable heating materials and reaction vessel materials for stable and reproducible growth of AlN crystals having high crystal quality. ..

Seven cylindrical Ta crucibles capable of accommodating 2-inch diameter wafers were prepared. For these Ta crucibles, a Ta ₂ C crucible was formed in which the outermost surface of the Ta crucible was covered with a Ta ₂ C layer having a thickness of 100 μm in the same manner as in Example I-2 of Example I. These Ta ₂ C crucibles were repeatedly evaluated for elevating temperature resistance under the following conditions using a manufacturing apparatus composed of the heating method shown in Table 2, the heating body material, and the reaction vessel material (Example II-). 1-Example II-7). The temperature of the crucible was repeatedly raised and lowered by raising the temperature of the crucible in 2 hours until the high temperature portion reached 2373 K, holding it for 10 hours, and lowering the temperature in 2 hours until it reached room temperature (300 K). In the evaluation of repeated elevating temperature resistance, the number of elevating temperatures until deterioration of the crucible (cracking and / or peeling of the coating material) is examined, and those with an elevating temperature less than 10 times are low, and the number of elevating temperatures is 10. Those having a temperature of 50 times or more were defined as medium, and those having a temperature increase / decrease of 50 times or more were rated high. The results are summarized in Table 2.

(Example III)
Seven cylindrical Ta crucibles capable of accommodating 2-inch diameter wafers were prepared. For these Ta crucibles, a Ta ₅ C ₃ crucible was formed in which the outermost surface of the Ta crucible was coated with a Ta ₅ Si ₃ layer having a thickness of 100 μm in the same manner as in Example I-3. These Ta ₅ Si ₃ crucibles were repeatedly evaluated for elevating temperature resistance in the same manner as in Example II (Examples III-1 to III-7). The results are summarized in Table 3.

With reference to Tables 2 and 3, Examples II-6, Example II-7, Example III-6 and Example III-7 using a manufacturing apparatus in which the heating body and reaction vessel do not contain Si and C are Ta ₂ The repeated ascending / descending temperature resistance of the C crucible and the Ta ₅ Si ₃ crucible was high. From this, it was found that the heated body and reaction vessel capable of stably growing AlN crystals having high crystal quality with good reproducibility do not contain Si and C.

(Example IV)
As shown in Table 4, Ta ₂ C crucible and TaC crucibles used in Example I, heated material, and using a reaction vessel were grown AlN crystals. First, the purity was disposed only 99.95 wt% of AlN raw material powder into Ta ₂ C crucible (eg in IV-8 TaC crucible). N ₂ gas is introduced as a carrier gas into the reaction vessel in which the Ta ₂ C crucible is arranged, the atmospheric pressure is maintained at 90 kPa, the high temperature portion is raised to 2500 K, and the low temperature portion is raised to 2300 K and held for 10 hours. As a result, AlN polycrystals were precipitated in the low temperature part of the Ta ₂ C crucible. Next, using the manufacturing apparatus in which the above-mentioned Ta ₂ C crucible (eg, Ta C crucible in IV-8), the heater and the reaction vessel are arranged, N ₂ gas is introduced into the reaction vessel as a carrier gas to reduce the atmospheric pressure. AlN crystals were grown on the underlying substrate by holding at 90 kPa, raising the temperature to 2500 K in the high temperature part and 2300 K in the low temperature part, and holding for 20 hours (Examples IV-1 to IV-8).

For the obtained AlN crystal, the half-value width of the maximum diffraction peak of the (0002) plane, the arithmetic mean roughness Ra of the main surface, the thermal conductivity, and the Young's coefficient are measured by the above-mentioned method in the rocking curve measurement of X-ray diffraction. (Example IV-1 to Example IV-8). The results are summarized in Table 4.

Table 4 See, as shown in Example IV-6 and Example IV-7, Ta ₂ C crucible surface is coated with Ta ₂ C, by using a heating material and a reaction vessel containing no Si and C , Si content less than 1 × 10 ¹⁹ cm ^-3 , C content less than 1 × 10 ¹⁹ cm ^-3 , Ta content 1 × 10 ¹⁶ cm ^-3 or more High crystal quality AlN crystal was gotten.

(Example V)
As shown in Table 5, AlN crystals were grown in the same manner as in Example IV using the Ta ₅ Si ₃ diffracted and TaC diffracted, heating material, and reaction vessel used in Example I. The half-value width of the maximum diffraction peak of the (0002) plane, the arithmetic mean roughness Ra of the main surface, the thermal conductivity, and the Young's ratio were measured in the rocking curve measurement of the X-ray diffraction of the AlN crystal (Examples V-1 to Example V). -8). The results are summarized in Table 5.

Table 5 with reference to, as shown in Example V-6 and Example V-7, the surface coated Ta ₅ Si ₃ crucible Ta ₅ Si _3, using a heating material and a reaction vessel containing no Si and C As a result, the Si content is less than 1 × 10 ¹⁹ cm ^-3 , the C content is less than 1 × 10 ¹⁹ cm ^-3 , and the Ta content is 1 × 10 ¹⁶ cm ^-3 or more. AlN crystals were obtained.

The embodiments and examples disclosed this time should be considered as exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the embodiments and examples described above, and is intended to include meaning equivalent to the scope of claims and all modifications within the scope.

10 Base substrate 11 AlN crystal 15 AlN raw material 20 Manufacturing equipment 21 Reaction vessel 21a Carrier gas introduction port 21b Carrier gas discharge port 23 坩 堝 23c Exhaust port 25 Heater 29 Radiation thermometer S10 Process of preparing manufacturing equipment S20 Aluminum nitride raw material and base Step of arranging the substrate S30 Step of growing aluminum nitride crystal

Claims (1)

Prepare a manufacturing apparatus including a crucible for arranging the aluminum nitride raw material and the base substrate inside, a heating body for heating the crucible, and a reaction vessel for arranging the crucible and the heating body inside. And the process of
A step of arranging the aluminum nitride raw material and the base substrate in the crucible, and
A step of sublimating the aluminum nitride raw material to grow aluminum nitride crystals on the base substrate is provided.
The crucible is coated with at least one of Ta ₂ C and Ta ₅ Si ₃ .
A method for producing aluminum nitride crystals in which the heater and the reaction vessel do not contain silicon and carbon.

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