JP2015168600A - Apparatus and method for manufacturing group iii nitride single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for manufacturing a group III nitride single crystal, capable of obtaining the group III nitride single crystal having desired optical absorption properties.SOLUTION: An apparatus 1 for manufacturing a single crystal, capable of growing an AlN single crystal 2 in a predetermined region 4a of a seed crystal 4 using a sublimation recrystallization method comprises: a first crucible 10 including a vessel body 11 having a storing space 101 for storing a raw material 3 and a lid body 12 for holding the seed crystal 4 so as to face the predetermined region 4a to the raw material 3; and an impurity getter 30 provided inside the vessel body 11 and for reducing concentrations of at least one of oxygen and carbon. The impurity getter 30 is cylindrical and has a first opening 311 facing the predetermined region 4a and a second opening 312 facing the raw material 3.

Description

  The present invention relates to a manufacturing apparatus and a manufacturing method for manufacturing a group III nitride single crystal such as an aluminum nitride (AIN) single crystal by a sublimation recrystallization method.

  An apparatus for producing an aluminum nitride single crystal by heating a raw material in a crucible formed from a reaction product such as tungsten or tantalum having high heat resistance or corrosion resistance and sublimating the raw material is known (for example, Patent Document 1).

JP 2011-132079 A

  In the above technique, the concentration of impurities such as carbon and oxygen in the manufactured single crystal is increased due to the purity of the raw material used and the influence of oxygen around the single crystal during single crystal growth. There is a problem that it may not be possible to obtain a single crystal.

  The problem to be solved by the present invention is to provide a group III nitride single crystal production apparatus and production method capable of obtaining a group III nitride single crystal having desired light absorption characteristics.

  [1] A group III nitride single crystal manufacturing apparatus according to the present invention is a group III nitride single crystal manufacturing apparatus for manufacturing a group III nitride single crystal in a predetermined region on a base substrate using a sublimation recrystallization method. A crucible having a container body having a storage space for storing the raw material, a lid for holding the base substrate so that the predetermined region faces the raw material, and provided in the storage space, oxygen or An impurity getter that reduces the concentration of at least one of the carbons, and the impurity getter has a cylindrical shape having a first opening facing the predetermined region and a second opening facing the raw material. It is characterized by having.

  [2] In the above invention, the impurity getter may have a tapered cylindrical shape whose inner diameter is reduced from the second opening toward the first opening, or the inner diameter of the first opening and the second opening. The opening may have a straight cylinder shape that is substantially the same as the inner diameter of the opening.

  [3] In the above invention, the impurity getter may contain zirconium.

  [4] In the above invention, the lid body has a lid member for covering the upper opening of the container body and holding the base substrate, and the lid member has a through-opening corresponding to the predetermined region. You may have.

  [5] In the above invention, the lid body may cover an upper opening of the container body, and the base substrate may be attached to the inner side surface of the lid body.

  [6] A manufacturing method of a group III nitride single crystal according to the present invention is a manufacturing method of manufacturing a group III nitride single crystal in a predetermined region on a base substrate using a sublimation recrystallization method, A container main body having an accommodating space for accommodating; a crucible having a lid for holding the base substrate so that the predetermined region faces the raw material; and at least one of oxygen and carbon provided in the accommodating space A first step of preparing a manufacturing apparatus including an impurity getter for reducing the concentration; and heating the crucible to cause sublimation gas generated from the raw material to reach the predetermined region via the impurity getter. And a second step of growing the group III nitride single crystal.

  According to the present invention, the cylindrical impurity getter having the first opening facing the predetermined region of the base substrate is provided in the crucible housing space. For this reason, it is possible to remove impurities from the sublimation gas during the growth of the group III nitride single crystal, and the impurity concentration in the group III nitride single crystal to be manufactured can be reduced. A group III nitride single crystal having the following can be obtained.

FIG. 1 is a schematic configuration diagram showing a group III nitride single crystal manufacturing apparatus according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a first crucible, a second crucible and an impurity getter of the group III nitride single crystal production apparatus according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view showing a first crucible, an impurity getter and a support part of a group III nitride single crystal production apparatus according to a second embodiment of the present invention. FIG. 4 is a cross-sectional view showing a modification of the group III nitride single crystal manufacturing apparatus in the first embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<< first embodiment >>
FIG. 1 is a schematic configuration diagram showing a group III nitride single crystal manufacturing apparatus in the present embodiment, and FIG. 2 is a cross-sectional view showing a crucible and an impurity getter in the present embodiment.

  The single crystal manufacturing apparatus 1 in this embodiment is an apparatus for manufacturing an aluminum nitride (AIN) single crystal 2 (hereinafter referred to as AIN single crystal 2) by a sublimation recrystallization method (an improved Rayleigh method). Specifically, the AIN single crystal 2 is manufactured by heating and sublimating the raw material in the high temperature region and recondensing the sublimation gas on the seed crystal 4 provided in the low temperature region. The seed crystal 4 in the present embodiment corresponds to an example of a base substrate in the present invention, and the single crystal manufacturing apparatus 1 in the present embodiment corresponds to an example of a group III nitride single crystal manufacturing apparatus in the present invention.

  As shown in FIG. 1, the single crystal manufacturing apparatus 1 is provided in a first crucible 10 that houses a first crucible 10 that houses a raw material 3, a second crucible 20 that houses a first crucible 10, and the like. The impurity getter 30, the heat insulating container 40 covering the second crucible 20, the crystal growth furnace 50 containing the first and second crucibles 10 and 20 covered by the heat insulating container 40, and the crystal growth furnace 50 A gas supply device 60 for supplying nitrogen gas to the substrate, a decompression device 70 for decompressing the inside of the crystal growth furnace 50, an induction coil 80 arranged outside the crystal growth furnace 50, and a first temperature measuring device for measuring the temperatures of the crucibles 10 and 20. 1 thermometer 91 and a second thermometer 92.

  As shown in FIG. 2, the first crucible 10 includes a container body 11 and a lid body 12. The container main body 11 has a housing space 101 formed by a cylindrical tube portion 111 and a bottom portion 112 that closes a lower end of the tube portion 111. The cylindrical portion 111 is composed of a lower cylindrical portion 111a and an upper cylindrical portion 111b having an upper opening 113 at the upper end. Between the lower cylindrical portion 111a and the upper cylindrical portion 111b, a flange of the impurity getter 30 is formed. The part 32 is sandwiched. The lower cylinder portion 111a and the upper cylinder portion 111b in the present embodiment have substantially the same inner diameter and thickness, but the upper and lower cylinder portions 111a and 111b may have different inner diameters and thicknesses. Good. The raw material 3 is stored in the storage space 101 of the container body 11. Specific examples of the raw material 3 include aluminum nitride powder and sintered bodies.

  The lid body 12 in this embodiment includes a first lid member 13 that covers the upper opening 113 of the first crucible 10 and a second lid provided above the first lid member 13 with the seed crystal 4 interposed therebetween. And a lid member 14.

  The first lid member 13 has a flat plate donut shape with a circular through-opening 131 provided in the center, and is placed on the container body of the first crucible 10 so as to cover the upper opening 113 of the first crucible 10. Is provided. The first lid member 13 is merely placed on the container main body 11, and the region closed by the container main body 11 and the first lid member 13 has a semi-sealed structure in which fluid can easily enter and exit. It has become. For this reason, nitrogen gas or the like introduced into the crystal growth furnace 50 can flow into the region. The first lid member 13 holds the seed crystal 4 on the upper surface of the first lid member 13, and at the time of manufacturing the AlN single crystal, as shown in FIG. The AlN single crystal 2 is formed in a corresponding region (hereinafter also referred to as a predetermined region 4a). The first lid member 13 in the present embodiment corresponds to an example of the lid member of the present invention.

  The second lid member 14 has a disk shape with a diameter corresponding to the container body 11 and is provided so as to cover the upper surface of the seed crystal 4. Note that the second lid member 14 may be omitted, and in this case, only the seed crystal 4 is placed on the first lid member 13 so as to cover the through opening 131 of the first lid member 13. Will be.

  In the present embodiment, the material constituting the first crucible 10 is preferably a material that is not subject to corrosion by the sublimation gas of aluminum nitride during the crystal growth of the AlN single crystal 2 (about 2000 [° C.]). Examples of such materials include molybdenum, tungsten, tantalum, molybdenum nitride, tungsten nitride, tantalum nitride, molybdenum carbide, tungsten carbide, tantalum carbide, and the like.

  The seed crystal 4 has a disk shape having an outer diameter larger than the diameter of the through opening 131 of the first lid member 13, and is placed on the first crucible 10 so as to close the through opening 131. . The second lid member 14 and the seed crystal 4 are supported by the first lid member 13, and the predetermined region 4 a of the seed crystal 4 faces the raw material 3 through the through-opening 131 of the first lid member 13. doing.

  Specific examples of the seed crystal 4 include an AlN single crystal and a crystal having a buffer layer (for example, an AlN / SiC single crystal (AlN single crystal film having a thickness of about 200 to 500 [μm] is grown on the SiC single crystal). And a plate-like or disk-like substrate composed of a single crystal)) or the like. In addition, it is preferable that the kind of seed crystal 4 is the same kind as the group III nitride single crystal to produce.

  The second crucible 20 in the present embodiment has a container body 21 and a lid body 22. The container main body 21 includes a cylindrical cylindrical portion 211 and a bottom portion 212 that closes the lower side of the cylindrical portion 211. As shown in FIG. 2, the first crucible 10 described above is accommodated in the cylindrical portion 211 of the second crucible 20 and is installed on the bottom 212 of the second crucible 20.

  In addition, as shown in FIG. 2, a circular opening 212 a is provided at the bottom 212 of the second crucible 20 to secure a visual path of the first thermometer 91 described later. The lid 22 is provided with a circular opening 22a for securing a visual path of a second thermometer 92 described later. These openings 212a and 22a have the smallest possible inner diameter (for example, about 10 [mm]) in order to suppress heat radiation to the outside.

  The material constituting the second crucible 20 may be a material having heat resistance at the temperature (about 2000 [° C.]) at the time of crystal growth of the aluminum nitride single crystal. Examples of such materials include graphite, boron nitride, aluminum nitride, gallium nitride, silicon carbide, silicon nitride, molybdenum, tungsten, tantalum, molybdenum carbide, zirconium carbide, tungsten carbide, tantalum carbide, molybdenum nitride, zirconium nitride, Examples thereof include tungsten nitride and tantalum nitride. Among these, it is preferable to use graphite from heat resistance and ease of processing.

The impurity getter 30 in the present embodiment is provided in the accommodation space 101 of the container body 11 in the first crucible 10 and is made of zirconium (Zr). The material constituting the impurity getter 30 is not particularly limited to the above. For example, the impurity getter 30 may be made of zirconium oxide (ZrO ₂ ), zirconium carbide (ZrC), zirconium nitride (ZrN), or the like. Incidentally, among these, it is preferable to configure the impurity getter 30 using zirconium (Zr) from the viewpoint of the effect of collecting impurities during the production of the AlN single crystal.

  As shown in FIG. 2, the impurity getter 30 includes a cylindrical cylindrical portion 31 and a flange portion 32. The tapered cylindrical portion 31 has a first opening 311 in the upper part in FIG. 2 and a second opening 312 in the lower part, and the diameter of the first opening 311 is the second opening 312. It is smaller than the diameter. The first opening 311 faces the predetermined region 4 a of the seed crystal 4 attached to the second lid member 14 through the through-opening 131 of the first lid member 13. The first opening 311 has a circular shape corresponding to the shape of the predetermined region 4 a of the seed crystal 4.

  The tapered cylindrical portion 31 of the impurity getter 30 in the present embodiment has a conical cylindrical shape whose diameter decreases linearly from the second opening 312 toward the first opening 311. The shape of the tapered cylindrical portion 31 is not particularly limited to this, and may be, for example, a shape that decreases in a curved shape from the second opening 312 toward the first opening 311.

  The flange portion 32 of the impurity getter 30 is annularly formed on the outer side in the horizontal direction of the second opening 312 along the second opening 312 of the tapered tube portion 31, and the length of the flange portion 32 (in FIG. 2). Of the first crucible 10 is substantially equal to the width (thickness) of the cylindrical portion 111 of the first crucible 10. In the impurity getter 30 of the present embodiment, the tapered cylindrical portion 31 and the flange portion 32 are integrally formed, but the tapered cylindrical portion 31 and the flange portion 32 may be formed independently of each other.

  As shown in FIG. 2, the impurity getter 30 has a flange portion 32 sandwiched between a lower tube portion 111 a and an upper tube portion 111 b in the tube portion 111 of the first crucible 10. Thus, the first opening 311 of the impurity getter 30 is held in a state of facing the predetermined region 4 a of the seed crystal 4 through the first lid member 13, and the second opening 312 is formed in the raw material 3. It is held facing each other.

  Further, in the impurity getter 30 according to the present embodiment, the first opening 311 of the tapered cylindrical portion 31 and the first lid member 13 of the first crucible 10 are separated from each other by a predetermined distance D. As a result, during the production of the AlN single crystal, excess gas that fills the first crucible 10 after the crystal growth is transferred from between the container body 11 and the first lid member 13 of the first crucible 10. It is possible to suppress the escape to the outside and the accumulation of impurities on the surface of the AlN single crystal.

  As shown in FIG. 2, a heat insulating container 40 is provided around the second crucible 20 in the present embodiment in order to suppress heat radiation to the outside. Examples of the material constituting the heat insulating container 40 include a molded heat insulating material using carbon fiber.

  As shown in FIG. 1, the heat insulating container 40 includes a cylindrical tube portion 41, a bottom portion 42 that closes the lower end of the tube portion 41, and a lid portion 43 that covers the upper portion of the tube portion 41. The inner diameter of the cylindrical portion 41 is larger than the outer diameter of the second crucible 20, and the height of the cylindrical portion 41 is higher than the height of the second crucible 20. Thereby, the cylinder part 41 of the heat insulation container 40 covers the cylinder part 211 of the second crucible 20, and the bottom part 42 of the heat insulation container 40 directly covers the bottom part 212 of the second crucible 20. Further, the lid portion 43 of the heat insulating container 40 covers the lid body 22 of the second crucible 20 at a distance, and there is a gap between the lid portion 43 of the heat insulating container 40 and the lid body 22 of the second crucible 20. S is formed. By providing such an interval S, it is possible to achieve uniform heat dissipation of the seed crystal 4 through the opening 431 (described later).

  A circular opening 421 for securing a visual path of a first thermometer 91 described later is formed in the bottom 42 of the heat insulating container 40. The opening 421 has an inner diameter as small as possible (for example, about 10 [mm]) in order to suppress heat radiation to the outside.

  A circular opening 431 for securing a visual path of a second thermometer 92 described later is also formed in the lid portion 43 of the heat insulating container 40. In addition, it is preferable that the inner diameter of the opening 431 is as small as possible in order to suppress heat radiation to the outside (for example, about 10 [mm]).

As shown in FIG. 1, the 1st and 2nd crucibles 10 and 20 covered with the heat insulation container 40 are being fixed in the crystal growth furnace 50 through the fixing means not shown. The crystal growth furnace 50 is composed of, for example, a double-structured transparent quartz tube, and a gas inlet 51 is provided in the upper part thereof, and a gas outlet 52 is provided in the lower part thereof. A gas supply device 60 capable of supplying nitrogen (N ₂ ) gas or the like is connected to the gas inlet 51. On the other hand, a decompression device 70 such as a vacuum pump is connected to the gas discharge port 52 via a pressure regulating valve (not shown). By driving the gas supply device 60 and the decompression device 70, the atmosphere in the crystal growth furnace 50 can be adjusted to a predetermined pressure.

  An induction coil 80 is disposed around the crystal growth furnace 50. The induction coil 80 surrounds the first and second crucibles 10 and 20 in the crystal growth furnace 50. When the induction coil 80 is energized with a high frequency current, the crucibles 10 and 20 are self-heated. The raw material 3 and the AlN single crystal 2 are heated to a desired temperature. Instead of the induction coil 80, a heating means using resistance heating or infrared heating may be used.

  Two thermometers 91 and 92 are disposed outside the crystal growth furnace 50. Specific examples of the first and second thermometers 91 and 92 include a radiation thermometer. The radiation thermometers 91 and 92 detect the temperature of the crucible 10 by measuring the intensity of infrared light and visible light emitted from the first crucible 10 through the transparent wall surface of the crystal growth furnace 50.

  The first thermometer 91 is connected to the bottom of the first crucible 10 in the crystal growth furnace 50 through the opening 421 formed in the lower part of the heat insulating container 40 and the opening 212 a formed in the lower part of the second crucible 20. The temperature of the lower part of the crucible 10 can be measured.

  On the other hand, the second thermometer 92 is connected to the first crucible 10 in the crystal growth furnace 50 through the opening 431 of the lid portion 43 of the heat insulating container 40 and the opening 22a formed in the upper part of the second crucible 20. It arrange | positions so that the upper surface of the 2nd cover member 14 may be opposed, and it is possible to measure the temperature of the upper part of the said crucible 10 concerned. That is, in this embodiment, the temperature of the raw material 3 is measured by the first thermometer 91, and the temperature of the seed crystal 4 is measured by the second thermometer 92.

  Next, a method for manufacturing the AlN single crystal 2 using the single crystal manufacturing apparatus 1 described above will be described.

  First, in the container main body 21 of the second crucible 20, the bottom part 112 and the lower cylinder part 111 a in the container main body 11 of the first crucible 10 are installed. Next, the raw material 3 such as aluminum nitride powder is set in the first crucible 10. At this time, the height of the upper surface of the raw material 3 is set to be equal to or lower than the upper end of the lower cylindrical portion 111a. Next, the impurity getter 30 is installed so that the flange portion 32 is positioned on the lower cylinder portion 111 a, and the upper cylinder portion 111 b is installed on the flange portion 32. Subsequently, after the first lid member 13 is installed on the upper cylinder portion 111 b, the second lid member 14 to which the seed crystal 4 is attached is installed on the first lid member 13. Thereby, the raw material 3 is accommodated in the first crucible 10, and the seed crystal 4 is held in the first crucible 10 so as to face the raw material 3.

  The seed crystal 4 to be attached to the second lid 14 of the lid 12 is mirror-polished by CMP (Chemical Mechanical Polishing) or the like on the lower main surface (the main surface facing the raw material 3) in FIG. It is preferable that both the upper and lower main surfaces in FIG. 2 are mirror-polished.

  Then, after installing the first and second crucibles 10 and 20 on the bottom 42 of the heat insulating container 40, the lid 43 is pushed toward the cylinder part 41 so that the fluid in the heat insulating container 40 can easily enter and exit. Keep sealed.

  Next, the first and second crucibles 10 and 20 covered with the heat insulating container 40 are installed in the crystal growth furnace 50 (first step). Then, the decompression device 70 is driven to remove the atmosphere in the crystal growth furnace 50 through the gas discharge port 52, and the inside of the crystal growth furnace 50 is evacuated. Next, the gas supply device 60 is driven, nitrogen gas is introduced into the crystal growth furnace 50 through the gas introduction port 51 to increase the pressure in the crystal growth furnace 50 to about 450 [torr], and the seed crystal 4 is increased to 1000 The surface of the seed crystal 4 is cleaned by heating at [° C.] for about 1 hour.

  Next, a high-frequency current is passed through the induction coil 80 to cause the crucible 20 to generate heat, thereby heating the raw material 3 and the seed crystal 4 and increasing the pressure in the crystal growth furnace 50. The temperature of the seed crystal 4 at this time is preferably 1700 [° C.] to 2300 [° C.], and the pressure is preferably 450 [torr] to 760 [torr].

  At this time, the upper and lower temperatures of the first crucible 10 are measured by the first and second thermometers 91 and 92, respectively, and the upper temperature of the first crucible 10 (that is, the temperature of the seed crystal 4). However, the lower temperature of the first crucible 10 (that is, the temperature of the raw material 3) is set to be lower by about 30 [° C.]. Such temperature adjustment is performed by adjusting the position of the induction coil 80 with respect to the first crucible 10, for example.

  When the temperature of the first crucible 10 reaches the above set temperature, the pressure in the crystal growth furnace 50 is reduced to 100 [torr] to 600 [torr] by the pressure reducing device 70. By this decompression, the growth of the AlN single crystal 2 starts. For example, at the time of manufacturing an aluminum nitride single crystal, as shown in the following formulas (1) and (2), a temperature gradient set between the upper and lower portions of the first and second crucibles 10 and 20 described above. As a result, the sublimation gas generated from the raw material 3 is transferred toward the predetermined region 4a of the seed crystal 4 and recrystallized on the seed crystal 4 to grow the AlN single crystal 2 (second step).

2AlN (s) → 2Al (g) + N ₂ (g) (1)
2Al (g) + N ₂ (g) → 2AlN (s) (2)

In general, the standard generation energy of zirconium oxide (ZrO ₂ ) is smaller than the standard generation energy of aluminum oxide (Al ₂ O ₃ ) at the temperature in the first crucible 10 when growing the AlN single crystal 2. For this reason, the following equation (3) proceeds in the first crucible 10, and the amount of aluminum oxide (Al ₂ O ₃ ) contained in the sublimation gas reaching the predetermined region 4 a of the seed crystal 4 can be reduced. (Oxygen absorption effect).
Zr + O ₂ → ZrO ₂ (3)

In addition, at the temperature in the first crucible 10 when the AlN single crystal 2 is grown, the standard generation energy of zirconium carbide (ZrC) is smaller than the standard generation energy of aluminum carbide (Al ₄ C ₃ ). For this reason, the following equation (4) proceeds in the first crucible 10, and the amount of aluminum carbide (Al ₄ C ₃ ) contained in the sublimation gas reaching the predetermined region 4 a of the seed crystal 4 can be reduced. (Carbon absorption effect).
Zr + C → ZrC (4)

Due to these oxygen absorption effect and carbon absorption effect, the amount of impurities (Al ₂ O ₃ , Al ₄ C ₃ ) contained in the produced AlN single crystal is reduced, and an AlN single crystal having desired light absorption characteristics is produced. Can do.

  In particular, in the present embodiment, as shown in FIG. 2, the impurity getter 30 is provided in the accommodation space 101 of the container body 11 in the first crucible 10. The impurity getter 30 has a tapered cylindrical portion 31 whose diameter is reduced from the second opening 312 toward the first opening 311, and the first opening 311 faces the predetermined region 4 a of the seed crystal 4. doing. The first opening 311 has a shape corresponding to the predetermined region 4 a of the seed crystal 4. Thereby, since the sublimation gas from the raw material 3 at the time of manufacturing the AlN single crystal rises along the shape of the tapered cylindrical portion 31 of the impurity getter 30, the oxygen absorption effect and the carbon absorption effect can be efficiently achieved.

The impurity getter 30 is made of a divalent oxide such as calcium oxide (CaO), magnesium oxide (MgO), yttrium oxide (Y ₂ O ₃ ), strontium oxide (SrO), or barium oxide (BaO). An additive such as at least one kind of material selected from the above may be included. In this case, high toughness can be imparted to the impurity getter 30, volume change of the impurity getter 30 accompanying temperature change can be reduced, and generation of cracks in the impurity getter 30 can be suppressed.

  When stopping the growth of the AlN single crystal 2, nitrogen gas is supplied from the gas inlet 51 into the crystal growth furnace 50 to raise the pressure in the crystal growth furnace 50 to about 700 [torr], and then the induction coil 80. The material 3 and the seed crystal 4 are naturally cooled to room temperature or cooled at a constant rate (for example, 100 [° C./hr]), and the grown AlN single crystal 2 is taken out from the first crucible 10.

<< Second Embodiment >>
FIG. 3 is a cross-sectional view showing the first crucible, the impurity getter, and the support part in the present embodiment. The single crystal manufacturing apparatus according to the second embodiment is different from the oxygen getter 30 of the first embodiment except that the shape of the impurity getter 30B is different from that of the oxygen getter 30 of the first embodiment and that the impurity getter 30B is supported by the support portion 33 in the accommodation space 101. This is the same as in the first embodiment described above. For this reason, only the parts different from the first embodiment will be described, and the same parts as those of the first embodiment will be denoted by the same reference numerals as those of the first embodiment, and the description thereof will be omitted.

  As shown in FIG. 3, the impurity getter 30B in the present embodiment has a straight cylindrical shape in which the inner diameter of the first opening 311 and the inner diameter of the second opening 312B are substantially the same, and the openings 311 and 312B. Between the two, it has a substantially constant thickness. The impurity getter 30B is made of the same material as the impurity getter 30 described in the first embodiment. The first opening 311 of the impurity getter 30B is opposed to the predetermined region 4a of the seed crystal 4 through the first lid member 13, and has a circular shape corresponding to the predetermined region 4a of the seed crystal 4. ing. On the other hand, the second opening 312B of the impurity getter 30B faces the raw material 3.

  Also in the impurity getter 30 </ b> B in the present embodiment, the first opening 311 and the first lid member 13 of the first crucible 10 are separated from each other by a predetermined distance D. Thereby, it can suppress that an impurity is laminated | stacked on the surface of an AlN single crystal. The impurity getter 30 </ b> B is installed on the support portion 33.

  The support portion 33 has a flat plate donut shape with an opening 331 formed at the center, and is formed of, for example, the same material as that of the first crucible 10. The diameter of the opening 331 corresponds to the inner diameter of the second opening 312B in the impurity getter 30B, and the outer diameter of the support portion 33 corresponds to the diameter of the container body 11 of the first crucible 10. The support portion 33 is sandwiched and held between the lower tube portion 11a and the upper tube portion 11b of the first crucible 10.

  When manufacturing the AlN single crystal 2 using the single crystal manufacturing apparatus in the present embodiment, first, the bottom 112 and the lower cylindrical portion 111a in the container body 21 of the second crucible 20 are installed. Next, the raw material 3 such as aluminum nitride powder is set in the first crucible 10. At this time, the height of the upper surface of the raw material 3 is set to be equal to or lower than the upper end of the lower cylindrical portion 111a. Next, after the support portion 33 is installed on the lower cylinder portion 111 a, the impurity getter 30 </ b> B is installed on the support portion 33. At this time, the opening 331 of the support portion 33 is disposed so as to correspond to the second opening 312B of the impurity getter 30B. Subsequently, the upper cylinder portion 111 b is installed on the support portion 33. Thereafter, the AlN single crystal 2 is manufactured in the same manner as the single crystal manufacturing apparatus 1 described in the first embodiment.

  Also in the single crystal manufacturing apparatus in this embodiment, when the sublimation gas from the raw material 3 at the time of manufacturing the AlN single crystal passes through the impurity getter 30B, an oxygen absorption effect and a carbon absorption effect can be exhibited. For this reason, the AlN single crystal 2 which has a desired light absorption characteristic can be manufactured.

  In addition, when the impurity getter 30B includes the above-described additives such as calcium oxide (CaO), the impurity getter 30B can be provided with high toughness, and the volume change of the impurity getter 30B accompanying a temperature change can be reduced. And it can suppress that a crack generate | occur | produces in the impurity getter 30B.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, as shown in FIG. 4, the first lid member 13 may be omitted from the single crystal manufacturing apparatus 1 described in the first embodiment. In this case, with the seed crystal 4 attached to the inner side surface 141 of the second lid member 14 of the first crucible 10 with an adhesive, the upper opening 113 of the upper cylindrical portion 111b of the first crucible 10 is opened. The second lid member 14 is installed on the upper cylinder portion 111b so as to directly cover. Examples of such adhesives include resins, inorganic compound ceramics, and high temperature adhesives mainly composed of graphite. Even in this case, the same effects as those of the first embodiment can be obtained.

  Further, for example, a crucible structure composed of only the first crucible 10 may be adopted by omitting the second crucible 20, or a triple crucible structure in which the second crucible 20 is accommodated in a third crucible. May be adopted.

  In the above-described embodiment, an apparatus and a method for manufacturing an aluminum nitride (AlN) single crystal as a group III nitride single crystal have been described. However, the present invention is not particularly limited thereto, and the gallium nitride (GaN) single crystal, nitride The present invention may be applied to an apparatus and method for manufacturing aluminum gallium (AlGaN) and indium nitride (InN) single crystals.

  In the above-described embodiment, the apparatus and method for producing a group III nitride single crystal using the seed crystal 4 attached to the second lid 14 of the lid 12 in the first crucible 10 have been described. However, it is not particularly limited to this. For example, instead of the seed crystal 4, a base substrate made of a surface material different from the group III nitride single crystal to be manufactured is attached to the second lid 14, and the group III nitride single crystal is attached on the base substrate. The present invention may be applied to a growing apparatus and method.

  Below, the effect of the present invention was confirmed by examples and comparative examples that further embody the present invention. The following examples and comparative examples are for confirming the oxygen absorption effect and the carbon absorption effect in the above-described embodiment.

<Example 1>
In Example 1, a single crystal manufacturing apparatus as shown in FIG. 1 described in the first embodiment was manufactured.

  Specifically, tantalum carbide was used as the material constituting the first crucible 10 and high-purity graphite was used as the material constituting the second crucible 20. The seed crystal 4 was an aluminum nitride single crystal substrate on a disc having a diameter of 25 mm and having a (0001) plane as a growth surface. Zirconium (Zr) is used as a material constituting the impurity getter 30, and the tapered cylindrical portion 31 has a shape in which the first opening 311 is a circular opening having a diameter of 26 mm and the second opening 312 is a circle having a diameter of 50 mm. The opening was shaped and the height was 4 mm.

  When growing the AlN single crystal, first, the inside of the crystal growth furnace 50 was sufficiently evacuated, then a process gas such as nitrogen gas was introduced, and the pressure was set to 100 to 600 [torr]. After the pressure is stabilized, the temperature of the seed crystal 4 is set to 1700 to 2200 [° C.] and the temperature of the raw material 3 is set to 1800 to 2200 [° C.] by induction heating with the induction coil 80, and after 100 hours of growth, Then, it was gradually cooled to room temperature, and an AlN single crystal was grown to a thickness of 5 mm. The rate of temperature increase was 30 [° C./min], and the rate of temperature decrease was 10 [° C./min]. The AlN single crystal thus obtained was used as an evaluation sample.

About the evaluation sample of Example 1 demonstrated above, the carbon concentration and the oxygen concentration were measured. For measurement of the carbon concentration and the oxygen concentration, SIMS (Secondary Ion Mass Spectrometry, manufactured by CAMECA) was used. In this example, Cs ⁺ was used as the primary ion species, and the distribution amount of the elements (C, O) on the surface of the AlN single crystal was measured under the condition that the acceleration voltage of the primary ions was 14.5 [kV].

<Example 2>
In Example 2, a single crystal manufacturing apparatus was manufactured in the same manner as Example 1 except that the impurity getter 30B having the shape as shown in FIG. 3 described in the second embodiment and the support portion 33 were used. Zirconium (Zr) was used as a material constituting the impurity getter 30 </ b> B, and tantalum carbide was used as the support portion 33. The shape of the impurity getter 30B was a cylindrical shape in which the inner diameters of the first and second openings 311 and 312B were 26 mm and the height was 4 mm.

  For the evaluation sample (AlN single crystal) produced using this single crystal production apparatus, the carbon concentration and the oxygen concentration were measured in the same manner as in Example 1.

<Example 3>
In Example 3, a single crystal manufacturing apparatus was manufactured in the same manner as in Example 1 except that zirconium nitride (ZrN) was used as the material of the impurity getter.

  For the evaluation sample (AlN single crystal) produced using this single crystal production apparatus, the carbon concentration and the oxygen concentration were measured in the same manner as in Example 1.

<Comparative Example 1>
In Comparative Example 1, a single crystal is manufactured in the same manner as in Example 1 except that a pseudo getter having the same shape as the impurity getter 30 is manufactured using tantalum carbide and the pseudo getter is installed instead of the impurity getter 30. A device was made.

  For the evaluation sample (AlN single crystal) produced using this single crystal production apparatus, the carbon concentration and the oxygen concentration were measured in the same manner as in Example 1.

Table 1 shows the measurement results of Example 1, Example 2, Example 3, and Comparative Example 1.

  According to the results shown in Table 1, it was found that in the evaluation sample of Example 1, the carbon concentration and the oxygen concentration were significantly reduced as compared with the evaluation sample of Comparative Example 1. Moreover, in the evaluation samples of Example 2 and Example 3, it was found that the oxygen concentration was significantly reduced as compared with the evaluation sample of Comparative Example 1.

  As described above, it was confirmed that carbon and oxygen as impurities were reduced in the AlN single crystal manufactured by the single crystal manufacturing apparatus in Example 1. In addition, it was confirmed that oxygen as impurities was reduced in the AlN single crystals produced by the single crystal production apparatuses in Example 2 and Example 3, respectively.

DESCRIPTION OF SYMBOLS 1 ... Single crystal manufacturing apparatus 2 ... Aluminum nitride single crystal 3 ... Raw material 4 ... Seed crystal 4a ... Predetermined area | region 10 ... 1st crucible 11 ... Container main body 111 ... -Tube part 112 ... Bottom part 113 ... Upper opening 12 ... Lid 13 ... First lid member 131 ... Through-opening 14 ... Second lid member 141 ... Inner side surface DESCRIPTION OF SYMBOLS 20 ... 2nd crucible 21 ... Container main body 211 ... Cylindrical part 212 ... Bottom part 22 ... Cover body 30, 30B ... Impurity getter 31 ... Tapered cylindrical part 311 ... 1st opening 312, 312B ... 2nd opening 32 ... Flange part 33 ... Supporting part 40 ... Thermal insulation container 50 ... Crystal growth furnace 60 ... Gas supply apparatus 70 ... Pressure reducing device 80 ... induction coil 91 ... first thermometer 92 ... second Degree meter

Claims (6)

A group III nitride single crystal manufacturing apparatus for manufacturing a group III nitride single crystal in a predetermined region on a base substrate using a sublimation recrystallization method,
A crucible having a container body having a storage space for storing a raw material, and a lid for holding the base substrate so that the predetermined region faces the raw material;
An impurity getter that is provided in the housing space and reduces the concentration of at least one of oxygen and carbon;
The group III nitride single crystal manufacturing apparatus, wherein the impurity getter has a cylindrical shape having a first opening facing the predetermined region and a second opening facing the raw material. It is the group III nitride single-crystal manufacturing apparatus of Claim 1,
The impurity getter has a tapered cylindrical shape whose inner diameter is reduced from the second opening toward the first opening, or the inner diameter of the first opening and the inner diameter of the second opening are substantially equal. And a group III nitride single crystal manufacturing apparatus characterized by having a straight cylindrical shape identical to each other. The group III nitride single crystal production apparatus according to claim 1 or 2,
The group III nitride single crystal manufacturing apparatus, wherein the impurity getter contains zirconium. It is a group III nitride single-crystal manufacturing apparatus of any one of Claims 1-3,
The lid body has a lid member for covering the upper opening of the container body and holding the base substrate,
The III-nitride single crystal manufacturing apparatus, wherein the lid member has a through-opening corresponding to the predetermined region. It is a group III nitride single-crystal manufacturing apparatus of any one of Claims 1-3,
The lid covers an upper opening of the container body;
The group III nitride single crystal manufacturing apparatus according to claim 1, wherein the base substrate is attached to an inner surface of the lid. A manufacturing method for manufacturing a group III nitride single crystal in a predetermined region on a base substrate using a sublimation recrystallization method,
A container main body having a storage space for storing the raw material, a crucible having a lid for holding the base substrate so that the predetermined region faces the raw material, and provided in the storage space, at least of oxygen or carbon A first step of preparing a manufacturing apparatus including an impurity getter for reducing one concentration;
And a second step of growing the group III nitride single crystal by causing the sublimation gas generated from the raw material by heating the crucible to reach the predetermined region via the impurity getter. A method for producing a group III nitride single crystal.

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