JP5162895B2 - Aluminum nitride crystal manufacturing method, aluminum nitride crystal, aluminum nitride crystal substrate, and semiconductor device - Google Patents

Description

  The present invention relates to an aluminum nitride (AlN) crystal manufacturing method, an AlN crystal, an AlN crystal substrate, and a semiconductor device, and more particularly to an AlN crystal manufacturing method, an AlN crystal, and an AlN crystal capable of obtaining a semiconductor device having good characteristics. The present invention relates to a semiconductor device manufactured using a substrate and its AlN crystal substrate.

Since the AlN crystal substrate has an energy band gap of 6.2 eV, a thermal conductivity of about 3.3 WK ⁻¹ cm ⁻¹ and a high electric resistance, it is attracting attention as a substrate for semiconductor devices such as optical devices and electronic devices. Has been.

The AlN crystal substrate is manufactured by an AlN crystal grown on the surface of a seed crystal substrate such as a Si (silicon) crystal substrate or a SiC (silicon carbide) crystal substrate by a sublimation method, HVPE (Hydride Vapor Phase Epitaxy) method, or the like. be able to.
B. Raghothamachar, M. Dudley, JCRojo, K. Morgan and LJ Schowalter, “X-ray characterization of bulk AIN single crystals grown by the sublimation technique”, Journal of Crystal Growth, vol.250, March 2003, p.244 X.Hu et al, “AlGaN / GaN heterostructure field-effect transistors on single-crystal bulk AlN”, Applied physics letters, vol.82, No.8, 2003, pp.1299-1301

  In order to reduce the manufacturing cost of a semiconductor device, it is possible to vapor-phase grow a nitride semiconductor single crystal layer on an AlN crystal substrate having as large a surface as possible to obtain as many semiconductor devices as possible from one AlN crystal substrate. It is valid.

  However, characteristics of a semiconductor device manufactured using such an AlN crystal substrate may deteriorate, and development of an AlN crystal substrate for obtaining a semiconductor device having good characteristics is desired.

  Accordingly, an object of the present invention is to provide an AlN crystal manufacturing method capable of obtaining a semiconductor device having good characteristics, an AlN crystal, an AlN crystal substrate, and a semiconductor device manufactured using the AlN crystal substrate. is there.

The present invention is an AlN crystal grown from an at least part of a range of 2 mm or more and 60 mm or less from the surface of the SiC seed crystal substrate to the AlN crystal side by growing an AlN crystal on the surface of the SiC seed crystal substrate. Has a surface of 10 cm ² or more and a dislocation density of 2 × 10 ⁴ pieces / cm ² or more and 5 × 10 ⁵ pieces / cm ² or less, and is selected from the group consisting of screw dislocations, edge dislocations, and mixed dislocations. The ratio of the dislocation density of the screw dislocation to the dislocation density is 0.2 or less, the dislocation density of the screw dislocation is 1 × 10 ⁴ pieces / cm ² or less, and the SiC seed crystal The AlN crystal has a substrate thickness of 150 μm or more and 400 μm or less.

The present invention also includes a step of growing an AlN crystal on the surface of an SiC seed crystal substrate having a thickness of 150 μm or more and 400 μm or less, and a range of 2 mm or more and 60 mm or less from the surface of the SiC seed crystal substrate to the AlN crystal side. A step of taking out at least a part of the AlN crystal, an area of the taken-out AlN crystal is 10 cm ² or more, and a dislocation density is 2 × 10 ⁴ pieces / cm ² or more and 5 × 10 ⁵ pieces / cm ² or less, It includes at least one dislocation selected from the group consisting of screw dislocations, edge dislocations, and mixed dislocations, the ratio of dislocation density of screw dislocations to dislocation density is 0.2 or less, and the dislocation density of screw dislocations is 1 And a step of growing an aluminum nitride crystal on a surface of 10 ⁴ pieces / cm ² or less .

In the method of manufacturing the AlN crystal of the present invention, it is preferred that the temperature of the SiC seed crystal substrate when growing the AlN crystal on the surface of the SiC seed crystal substrate is 1650 ° C. or higher.

In the method of manufacturing the AlN crystal of the present invention, it is preferable to carry out the growth of the AlN crystal onto the surface of the SiC seed crystal substrate by sublimation method.

Further, the present invention is an AlN crystal AlN crystal substrate made of any one of the above AlN crystals or manufactured by any one of the above AlN crystal manufacturing methods .
Furthermore, the present invention is a semiconductor device manufactured using the above AlN crystal substrate.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the AlN crystal which can obtain the semiconductor device which has a favorable characteristic, the semiconductor device produced using the AlN crystal and the AlN crystal substrate, and the AlN crystal substrate can be provided.

  Embodiments of the present invention will be described below. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

Conventionally, in order to improve the characteristics of a semiconductor device, it has been considered that the lower the dislocation density of the AlN crystal that constitutes the AlN crystal substrate, the better. It has been found that the characteristics of a semiconductor device are deteriorated even if the dislocation density of the constituent AlN crystal is too low. Then, the inventors of the present invention, in an AlN crystal substrate made of a large AlN crystal having a surface with an area of 10 cm ² or more, have a dislocation density of the AlN crystal constituting the AlN crystal substrate of 1 × 10 ³ pieces / cm ² or more. It has been found that the characteristics of the semiconductor device are improved by setting it to 1 × 10 ⁶ pieces / cm ² or less, and the present invention has been completed.

That is, a semiconductor device was fabricated by sequentially depositing a semiconductor film on an AlN crystal substrate made of AlN crystal having a surface with an area of 10 cm ² or more and a dislocation density of less than 1 × 10 ³ pieces / cm ² . In this case, the characteristics of the semiconductor device are deteriorated. Further, a semiconductor device was fabricated by sequentially depositing a semiconductor film on an AlN crystal substrate made of AlN crystal having an area of 10 cm ² or more and a dislocation density higher than 1 × 10 ⁶ pieces / cm ² . Even in this case, the characteristics of the semiconductor device deteriorate.

The present inventors also have an AlN crystal substrate comprising an AlN crystal having a surface with an area of 10 cm ² or more and a dislocation density of 2 × 10 ⁴ pieces / cm ² or more and 5 × 10 ⁵ pieces / cm ² or less. It has also been found that the characteristics of the semiconductor device are particularly good when a semiconductor device is fabricated by sequentially depositing semiconductor films on the substrate.

The reason why the characteristics of the semiconductor device deteriorate when the dislocation density of the AlN crystal constituting the AlN crystal substrate is too low, less than 1 × 10 ³ pieces / cm ^2, is not clear, but is estimated as follows. That is, the dislocations in the AlN crystal substrate function as getters (suction ports) for the precipitates caused by impurities in the AlN crystal substrate and the composition deviation of the AlN crystal substrate. Therefore, the dislocation density of the AlN crystal constituting the AlN crystal substrate If it is too low, the function as a getter will not be sufficiently exhibited. For this reason, the above-mentioned impurities and precipitates remain in the portion of the AlN crystal constituting the AlN crystal substrate where there are few dislocations, the crystallinity of the portion where the dislocation is small is lowered, and the portion is grown on the portion where the dislocation does not exist. It is considered that the crystallinity of the semiconductor film is also lowered. Thereby, when the dislocation density of the AlN crystal constituting the AlN crystal substrate is too low as less than 1 × 10 ³ pieces / cm ^2, it is considered that the characteristics of the semiconductor device are deteriorated.

  In addition, the AlN crystal constituting the AlN crystal substrate may include at least one dislocation selected from the group consisting of screw dislocations, edge dislocations, and mixed dislocations in which screw dislocations and edge dislocations are mixed. Here, the ratio of the dislocation density of screw dislocations to the density of all dislocations of the AlN crystal (that is, the dislocation density of the AlN crystal referred to above) is preferably 0.2 or less. When a semiconductor device is fabricated by sequentially depositing a semiconductor film on the surface of an AlN crystal substrate made of an AlN crystal having a ratio of dislocation density of screw dislocations to a density of the entire dislocation of 0.2 or less, the semiconductor Device characteristics tend to be good.

In addition, the present inventors manufactured a semiconductor device by sequentially depositing a semiconductor film on the surface of an AlN crystal substrate made of an AlN crystal having a screw dislocation density of 1 × 10 ⁴ pieces / cm ² or less. In some cases, the characteristics of the semiconductor device tend to be further improved, and it has been found that such a tendency is also present when there is no screw dislocation in the AlN crystal constituting the AlN crystal substrate.

  In the present invention, the dislocation density of the AlN crystal is determined by etching the surface of the AlN crystal for 30 minutes using a mixed melt of KOH and NaOH at 250 ° C. (KOH mass: NaOH mass = 1: 1). And the density of etch pits appearing on the surface is measured.

  In the present invention, whether the dislocation in the AlN crystal corresponds to an edge dislocation, a screw dislocation, or a mixed dislocation in which these dislocations are mixed depends on the size of the etch pits appearing on the surface of the AlN crystal substrate by the above method. Can be determined. Etch pits corresponding to screw dislocations have a maximum diameter of 10 μm to 15 μm, and etch pits corresponding to edge dislocations have a maximum diameter of 1 μm to 5 μm. In the present invention, the “maximum diameter” means the length of the longest line segment connecting two points existing on the periphery of the etch pit.

  The AlN crystal of the present invention is obtained by, for example, growing an AlN crystal on a seed crystal substrate such as a Si crystal substrate or a SiC crystal substrate by a sublimation method, and in the process of lengthening the AlN crystal by the growth of the AlN crystal. Most of the dislocations are propagated in directions other than the c-axis, and the dislocation density of the AlN crystal is considered to decrease as the distance from the seed crystal substrate increases, and this can be used for manufacturing.

For example, first, as shown in the schematic cross-sectional view of FIG. 1, an SiC seed crystal substrate 3 having a surface with an area of 10 cm ² or more is prepared as a seed crystal substrate, and an AlN crystal is formed on the surface of the SiC seed crystal substrate 3. 8 is grown by sublimation.

  Next, as shown in the schematic cross-sectional view of FIG. 2, a range 8a from the surface of the SiC seed crystal substrate 3 to the nitrided AlN crystal 8 side of 2 mm to 60 mm, preferably 3 mm to 20 mm (shaded portion in FIG. 2). At least a part of the AlN crystal 8b (here, a part obtained by cutting the broken line part in FIG. 2) is taken out.

The AlN crystal 8b thus produced has a surface with an area of 10 cm ² or more and a dislocation density of 1 × 10 ³ / cm ² or more and 1 × 10 ⁶ / cm ² or less, preferably a dislocation density. The AlN crystal is 2 × 10 ⁴ pieces / cm ² or more and 5 × 10 ⁵ pieces / cm ² or less.

Also, an AlN crystal substrate made of the AlN crystal 8b produced as described above is used as a seed crystal substrate, and an AlN crystal is grown on the surface of the AlN crystal substrate to be a seed crystal substrate by a sublimation method. And also by taking out at least a part of the grown AlN crystal, it has a surface with an area of 10 cm ² or more, and the dislocation density is 1 × 10 ³ pieces / cm ² or more and 1 × 10 ⁶ pieces / cm ² or less, preferably Can produce an AlN crystal having a dislocation density of 2 × 10 ⁴ pieces / cm ² or more and 5 × 10 ⁵ pieces / cm ² or less.

  In the above, the thickness of the SiC seed crystal substrate 3 serving as the seed crystal substrate is preferably 150 μm or more and 400 μm or less, more preferably 150 μm or more and 350 μm or less, and most preferably 150 μm or more and 300 μm or less. . By setting the thickness of the SiC seed crystal substrate 3 to the above thickness, an AlN crystal having the dislocation density shown above can be easily obtained.

  In the above description, the temperature of SiC seed crystal substrate 3 when aluminum nitride crystal 8 is grown on the surface of SiC seed crystal substrate 3 is preferably 1650 ° C. or higher. By using the SiC seed crystal substrate 3 having a lattice constant of about 1% different from that of the AlN crystal 8, lattice relaxation occurs at a few μm from the SiC seed crystal substrate 3, and most of the screw dislocations loop and disappear. It is conceivable to reduce the screw dislocation by utilizing this fact. Further, at the initial growth stage of the AlN crystal 8, the dislocation density can be reduced by growing the AlN crystal 8 under the condition that the step flow growth is performed so as not to generate the tensile stress due to the combination of vacancies and crystal grains. Such a dislocation behavior can be clearly observed when the temperature of the SiC seed crystal substrate 3 when the aluminum nitride crystal 8 is grown on the surface of the SiC seed crystal substrate 3 is 1650 ° C. or higher.

(Preparation of AlN crystal substrate)
An AlN crystal is grown on the surface of an SiC seed crystal substrate having a diameter of 2 inches and a thickness of 250 μm by the sublimation method as follows.

  FIG. 3 is a schematic cross-sectional view of an AlN crystal growth apparatus used in this example. First, an AlN raw material 2 such as AlN powder is accommodated in the lower portion of the graphite crucible 1, and an SiC seed crystal substrate 3 whose surface is processed flat is placed on the upper portion of the crucible 1. Here, for the purpose of preventing sublimation of SiC from the back surface of the SiC seed crystal substrate 3, the graphite seed crystal substrate protective material 4 is installed in close contact with the back surface of the SiC seed crystal substrate 3.

  Next, the temperature in the crucible 1 is raised by heating the heating body 7 using the high frequency heating coil 6 while flowing nitrogen gas into the reaction vessel 5. Here, the temperature on the side of the SiC seed crystal substrate 3 in the crucible 1 was kept at 2000 ° C., the temperature on the side of the AlN raw material 2 was kept at 2200 ° C., and AlN was sublimated from the AlN raw material 2 and installed on the upper part of the crucible 1. An AlN crystal film having a thickness of about 30 μm is grown on the surface of the SiC seed crystal substrate 3, and then only the temperature on the AlN raw material 2 side is increased to 2400 ° C., and the AlN crystal 8 is grown for 100 hours.

  Thereafter, the AlN crystal 8 is cooled to room temperature (25 ° C.) and taken out from the apparatus. Then, an AlN crystal 8 having a thickness of 10 mm grows on the SiC seed crystal substrate 3 having a diameter of 2 inches.

  Then, as shown in the schematic cross-sectional view of FIG. 4, slicing is started from a position 2 mm or more away from the surface of the SiC seed crystal substrate 3 of the AlN crystal 8 obtained as described above, and the (0002) plane is Ten AlN crystal substrates 9 having a diameter of 2 inches as the surface are produced. Then, the Al surfaces of these ten AlN crystal substrates 9 are mirror-polished.

  Further, as shown in the schematic cross-sectional view of FIG. 5, an AlN crystal 10 is grown on the surface of the AlN crystal substrate 9 obtained as described above by a sublimation method using the growth apparatus shown in FIG. Let

  Here, while maintaining the temperature on the AlN crystal substrate 9 side at 2000 ° C., the AlN crystal 10 raises the temperature on the AlN raw material 2 side with a constant gradient from room temperature to 2400 ° C., and sublimates AlN from the AlN raw material 2. By this, it can be grown for 100 hours.

  Thereafter, the grown AlN crystal 10 is cooled to room temperature (25 ° C.) and taken out from the growth apparatus. Thereby, the AlN crystal 10 having a diameter of slightly less than 2 inches is obtained. Then, as shown in the schematic cross-sectional view of FIG. 6, the AlN crystal substrate 11 is taken out by slicing the AlN crystal 10.

(Measurement of dislocation density)
The surface of each of the 10 AlN crystal substrates 9 taken out from the AlN crystal 8 and the arbitrary one AlN crystal substrate 11 taken out from the AlN crystal 10 is mixed with KOH and NaOH at 250 ° C. Etching is performed for 30 minutes using a liquid (KOH mass: NaOH mass = 1: 1), and etch pits corresponding to dislocations appear. By calculating the density of the etch pits, the dislocation density and distribution of each AlN crystal substrate are obtained. At this time, dislocations do not concentrate on the surface of the AlN crystal substrate, but exist uniformly throughout.

  Note that the dislocation density of the AlN crystal substrate 9 tends to be lower as the AlN crystal substrate 9 is located farther from the SiC seed crystal substrate 3.

  Further, the dislocations of the AlN crystal substrate 11 taken out from the AlN crystal 10 are substantially the same as the dislocation density and distribution of the AlN crystal substrate 9 that has become the seed crystal substrate. Therefore, the AlN crystal substrate 11 having a desired dislocation density and distribution can be obtained with good reproducibility.

(Production of semiconductor devices)
A semiconductor film and a metal film are sequentially deposited on each Al surface of ten AlN crystal substrates 22 each having a different dislocation density cut out from the AlN crystal 8 or the AlN crystal 10, and the structure shown in the schematic cross-sectional view of FIG. The field effect transistor is manufactured.

  More specifically, first, an AlN film 12 having a thickness of 0.5 μm and a GaN having a thickness of 100 nm are formed on the Al surface of the AlN crystal substrate 22 by MOCVD (Metal Organic Chemical Vapor Deposition). A film 13 and a 30 nm thick AlGaN film 14 are deposited by epitaxial growth in this order. At this time, the AlN film 12 and the GaN film 13 are each non-doped.

  Next, a Ti film 15, an Al film 16, a Ti film 17, and an Au film 18 are deposited in this order on the surface of the AlGaN film 14, thereby forming a source electrode 19 and a drain electrode 20, respectively.

  Next, a gate electrode 21 made of an Au film is formed between the source electrode 19 and the drain electrode 20 on the surface of the AlGaN film 14. At this time, the gate length is 2 μm, and the distance between the gate electrode 21 and the source electrode 19 and the distance between the gate electrode 21 and the drain electrode 20 are 10 μm, respectively.

  Then, the wafer after the formation of the gate electrode 21 is divided into chips to produce a field effect transistor having the structure shown in FIG.

(Semiconductor device evaluation)
When the breakdown voltage between the gate electrode 21 and the drain electrode 20 of the field effect transistor fabricated as described above is measured, the dislocation density is 1 × 10 ³ / cm ² or more and 1 × 10 ⁶ / cm ² or less. The breakdown voltage of a field effect transistor manufactured using an AlN crystal substrate made of a certain AlN crystal is high, and particularly when the dislocation density is 2 × 10 ⁴ / cm ² or more and 1 × 10 ⁵ / cm ² or less. A field effect transistor manufactured using an AlN crystal substrate made of an AlN crystal is stabilized at a higher breakdown voltage of 1200 to 1250V.

However, a field effect transistor manufactured using an AlN crystal substrate made of AlN crystal having a dislocation density of 1 × 10 ² pieces / cm ² and an AlN made of AlN crystal having a dislocation density of 5 × 10 ⁶ pieces / cm ^2. The breakdown voltage between the gate electrode 21 and the drain electrode 20 of the field effect transistor manufactured using the crystal substrate has a dislocation density of 2 × 10 ⁴ / cm ² or more and 1 × 10 ⁵ / cm ² or less. The breakdown voltage is as low as about 1/2 times (500 to 600 V) of a field effect transistor manufactured using an AlN crystal substrate made of AlN crystal.

Even when an AlN crystal substrate made of AlN crystal having a dislocation density of 2 × 10 ⁴ pieces / cm ² or more and 1 × 10 ⁵ pieces / cm ² or less is used, screw dislocations, edge dislocations, and mixed dislocations are used. When the ratio of the screw dislocation density of the screw dislocations to the total dislocation density of the AlN crystal is higher than 0.2, including at least one dislocation selected from the group consisting of: The breakdown voltage between the electrodes 20 is 1050 to 1100 V, and the breakdown voltage is lower than that in the case where the ratio of the dislocation density of the screw dislocation is 0.2 or less (1200 to 1250 V).

The dislocation density is 2 × 10 ⁴ pieces / cm ² or more and 1 × 10 ⁵ pieces / cm ² or less, and includes at least one kind of dislocation selected from the group consisting of screw dislocations, edge dislocations, and mixed dislocations. The ratio of the dislocation density of screw dislocations to the density of all dislocations of the AlN crystal is 0.2 or less, and the dislocation density of the screw dislocations is 1 × 10 ⁴ pieces / cm ² or less. Is used, the breakdown voltage of the field effect transistor is further increased and stabilized at around 1300V. Therefore, the dislocation density of screw dislocations in the AlN crystal substrate is preferably 1 × 10 ⁴ pieces / cm ² or less.

  In this example, the evaluation of the semiconductor device was evaluated by the breakdown voltage between the gate electrode and the drain electrode of the field effect transistor. However, the other semiconductor devices in which the crystallinity of the semiconductor film affects the characteristics are also described above. It is considered that the same evaluation can be obtained.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  Using the AlN crystal substrate of the present invention, light emitting elements (light emitting diodes, laser diodes, etc.), electronic devices (rectifiers, bipolar transistors, field effect transistors, HEMTs, etc.), semiconductor sensors (temperature sensors, pressure sensors, radiation sensors, or visible) A semiconductor device such as an ultraviolet light detector, a SAW device (Surface Acoustic Wave Device), an acceleration sensor, a MEMS (Micro Electro Mechanical Systems) component, a piezoelectric vibrator, a resonator, or a piezoelectric actuator can be manufactured.

It is typical sectional drawing illustrating a part of manufacturing process of an example of the manufacturing method of the AlN crystal | crystallization of this invention. It is typical sectional drawing illustrating other one part of the manufacturing process of an example of the manufacturing method of the AlN crystal | crystallization of this invention. It is typical sectional drawing of the growth apparatus of the AlN crystal | crystallization used in the Example of this invention. It is typical sectional drawing illustrating an example of the method of obtaining an AlN crystal substrate from an AlN crystal in the Example of this invention. It is typical sectional drawing illustrating an example of the method of growing an AlN crystal | crystallization on the surface of an AlN crystal substrate in the Example of this invention. It is typical sectional drawing illustrating another example of the method of obtaining an AlN crystal substrate from an AlN crystal in the Example of this invention. It is typical sectional drawing which shows the structure of the field effect transistor produced in the Example of this invention.

Explanation of symbols

  1 crucible, 2 AlN raw material, 3 SiC seed crystal substrate, 4 seed crystal substrate protective material, 5 reaction vessel, 6 high frequency heating coil, 7 heating element, 8, 8b, 10 AlN crystal, 8a range, 9, 11, 22 AlN Crystal substrate, 12 AlN film, 13 GaN film, 14 AlGaN film, 15, 17 Ti film, 16 Al film, 18 Au film, 19 source electrode, 20 drain electrode, 21 gate electrode.

Claims (6)

An aluminum nitride crystal grown on the surface of the SiC seed crystal substrate and extracted from at least part of the range of 2 mm to 60 mm from the surface of the SiC seed crystal substrate toward the aluminum nitride crystal; It has a surface with an area of 10 cm ² or more and a dislocation density of 2 × 10 ⁴ pieces / cm ² or more and 5 × 10 ⁵ pieces / cm ² or less,
Including at least one dislocation selected from the group consisting of a screw dislocation, an edge dislocation, and a mixed dislocation, and a ratio of the dislocation density of the screw dislocation to the dislocation density is 0.2 or less,
The dislocation density of the screw dislocations is 1 × 10 ⁴ pieces / cm ² or less,
An aluminum nitride crystal , wherein the SiC seed crystal substrate has a thickness of 150 μm or more and 400 μm or less . A step of growing an aluminum nitride crystal on the surface of the SiC seed crystal substrate having a thickness of 150 μm or more and 400 μm or less, and at least one in the range of 2 mm or more and 60 mm or less from the surface of the SiC seed crystal substrate to the aluminum nitride crystal side The step of taking out the aluminum nitride crystal of the portion, the area of the taken out aluminum nitride crystal is 10 cm ² or more, and the dislocation density is 2 × 10 ⁴ pieces / cm ² or more and 5 × 10 ⁵ pieces / cm ² or less, Including at least one dislocation selected from the group consisting of a screw dislocation, an edge dislocation, and a mixed dislocation, and a ratio of the dislocation density of the screw dislocation to the dislocation density is 0.2 or less, dislocation density and a step of growing aluminum nitride crystal on the surface is 1 × 10 ⁴ / cm ² or less, the aluminum nitride crystal Manufacturing method. The method for producing an aluminum nitride crystal according to claim 2 , wherein the temperature of the SiC seed crystal substrate when the aluminum nitride crystal is grown on the surface of the SiC seed crystal substrate is 1650 ° C or higher. 4. The method for producing an aluminum nitride crystal according to claim 2 , wherein the growth of the aluminum nitride crystal on the surface of the SiC seed crystal substrate is performed by a sublimation method. Made of aluminum nitride crystal according to claim 1 or claim 2 consisting of aluminum nitride crystal produced by the method for producing the aluminum nitride crystal according to any one of 4, an aluminum nitride crystal substrate. A semiconductor device manufactured using the aluminum nitride crystal substrate according to claim 5 .

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