JP6153489B2 - Crystal growth equipment - Google Patents

Description

  The present invention relates to a crystal growth apparatus for causing a group III nitride crystal to vapor-phase grow on a substrate by reacting a group III halide gas and a nitrogen source gas while heating the substrate disposed in a reaction vessel. .

  Group III nitride semiconductor crystals such as aluminum nitride, gallium nitride, and indium nitride have a wide range of band gap energy values, which are about 6.2 eV, about 3.4 eV, and about 0.7 eV, respectively. Degree. These group III nitride semiconductors can form mixed crystal semiconductors having an arbitrary composition, and can take values between the above band gaps depending on the mixed crystal composition.

  Therefore, by using a group III nitride semiconductor crystal, it is possible in principle to produce a wide range of light emitting elements from infrared light to ultraviolet light. In particular, in recent years, development of light-emitting elements using aluminum-based group III nitride semiconductors (mainly aluminum gallium nitride mixed crystals) has been vigorously advanced. By using an aluminum-based group III nitride semiconductor, it is possible to emit light with a short wavelength in the ultraviolet region, an ultraviolet light emitting diode for a white light source, an ultraviolet light emitting diode for sterilization, a laser that can be used for reading and writing of a high-density optical disk memory, and a communication laser A light emitting light source such as can be manufactured.

  A light-emitting element using a group III nitride semiconductor (for example, an aluminum-based group III nitride semiconductor) is a semiconductor single crystal thin film (specifically, a thickness of about several microns on a substrate, like a conventional semiconductor light-emitting element). The thin film can be formed by sequentially stacking an n-type semiconductor layer, a light-emitting layer, and a p-type semiconductor layer. Such a thin film of a semiconductor single crystal can be formed using a crystal growth method such as a molecular beam epitaxy (MBE) method or a metalorganic vapor phase epitaxy (MOVPE) method. Thus, it has been attempted to form a laminated structure suitable as a light emitting device by adopting such a method for the group III nitride semiconductor light emitting device.

  Currently, in the manufacture of group III nitride semiconductor light-emitting devices, a sapphire substrate is generally employed from the viewpoint of crystal quality, ultraviolet light transparency, mass productivity, and cost as a substrate. However, when a group III nitride is grown on a sapphire substrate, there is a difference in lattice constant, thermal expansion coefficient, etc. between the sapphire substrate and the group III nitride (such as aluminum gallium nitride) forming the semiconductor laminated film. As a result, crystal defects (misfit dislocations), cracks, and the like occur, causing the light emitting performance of the device to deteriorate.

  In order to solve these problems, it is desirable to use a substrate having a lattice constant close to that of the semiconductor multilayer film and a thermal expansion coefficient close to that of the semiconductor multilayer film when forming the semiconductor multilayer film. . As a substrate on which the group III nitride semiconductor thin film is formed, a group III nitride single crystal substrate is most suitable. For example, an aluminum nitride single crystal substrate or an aluminum gallium nitride single crystal substrate is optimal as a substrate on which an aluminum-based group III nitride semiconductor thin film is formed. Therefore, development of a method capable of mass-producing a large area and homogeneous group III nitride single crystal substrate is desired.

  In order to use a group III nitride single crystal as a substrate, a thickness of at least 100 μm is necessary from the viewpoint of mechanical strength. However, the MBE method and the MOVPE method have a problem that the film forming speed is low. A hydride vapor phase epitaxy (HVPE) method is known as a method for growing a group III nitride single crystal having a high deposition rate (see Patent Documents 1 to 3). The HVPE method is not suitable for precisely controlling the film thickness as compared with the MBE method or the MOVPE method, but a single crystal with good crystallinity can be grown at a high film formation rate. It can be said that it is suitable for mass production of crystal substrates. In the growth of a group III nitride single crystal by the HVPE method, a group III halide gas (for example, aluminum halide gas) that is a group III element source gas and a nitrogen source gas (for example, ammonia gas) are supplied into the reactor. The two gases are reacted on a heated substrate.

  For example, in Patent Document 3, as a method for producing an aluminum-based group III nitride by the HVPE method, a group III halide gas containing an aluminum halide gas and a nitrogen source gas are reacted on a substrate held in a reaction zone. In the method of producing an aluminum-based group III nitride by vapor growth on a substrate, both reaction gases are caused to flow into the reaction zone with a barrier gas interposed between the group III halide gas and the nitrogen source gas. Then, it is disclosed that both reaction gases are brought into contact with each other on the substrate to be reacted.

JP 2003-303774 A JP 2006-073578 A JP 2006-114845 A

  However, as a result of further investigation by the present inventors, when a group III nitride single crystal is grown by a HVPE method on a wide (large diameter) substrate using a conventionally known vapor phase growth apparatus, It has been found that there is a large difference in growth rate between the center and the edge. If there is a large difference in the growth rate between the central portion and the end portion, the quality of the single crystal substrate may be different between the central portion and the end portion. In addition, if the difference in thickness between the center portion and the end portion of the single crystal after growth is large, the subsequent processing may be adversely affected.

  An object of the present invention is to provide a crystal growth apparatus capable of improving the uniformity of the growth film thickness when a group III nitride is grown on a wide substrate by the HVPE method. In addition, a method for producing a group III nitride using the crystal growth apparatus is provided.

The first aspect of the present invention is:
A reactor having a reaction zone for growing a group III nitride on a substrate by reacting a group III halide gas and a nitrogen source gas;
A group III halide gas supply means for supplying the group III halide gas to the reaction zone;
In a crystal growth apparatus having nitrogen source gas supply means for supplying the nitrogen source gas to the reaction zone,
The reactor has a support base in the reaction zone for rotatably supporting the substrate,
The group III halide gas supply means is arranged to blow out the group III halide gas from the upper side of the support base toward the upper side of the support base.
The group III halide gas supply means has a first blow-out port from which the group III halide gas flows out and a second blow-out port through which the barrier gas flows out, and the second blow-out port is a first blow-out port. It is placed around the mouth,
The first air outlet has a shape in which the maximum width in the Y direction is larger than the maximum width in the vertical direction, and the Y direction is a horizontal direction and is the outermost one of the first air outlets in a top view. It is the direction perpendicular to the midpoint of the line segment connecting the end and the other outermost end and the straight line passing through the center of rotation of the upper surface of the support base, the one outermost end and the other outermost end in top view, The straight line passing through the rotation center is a contact point that contacts the outermost opening of the first outlet from the outside,
The crystal growth apparatus is characterized in that a ratio a / D between the maximum width a in the Y direction of the first outlet and the maximum width D of the support base is 0.05 or more and 2 or less.

  According to a second aspect of the present invention, there is provided a group III nitride production method in which a group III nitride single crystal is grown on a heated substrate by reacting a group III halide gas and a nitrogen source gas. A group III nitride manufacturing method is characterized in that a group III nitride single crystal is manufactured using the crystal growth apparatus according to the first aspect of the present invention.

  With the crystal growth apparatus according to the first aspect of the present invention, it is possible to improve the uniformity of the growth film thickness when a group III nitride is grown on a wide substrate by the HVPE method.

  According to the method for producing a group III nitride according to the second aspect of the present invention, it is possible to improve the uniformity of the grown film thickness even when the group III nitride is grown on a wide substrate. .

It is a figure which illustrates typically crystal growth device 100 concerning one embodiment of the present invention. It is an A-A 'arrow line view of FIG. FIG. 3 is a view taken along the line B-B ′ of FIG. 1, and is a view of a nozzle portion of the group III halide gas supply unit 30 as viewed from the front in the X direction. FIG. 3 is a diagram corresponding to FIG. 2 in another embodiment of the present invention. FIG. 4 is a diagram corresponding to FIG. 3 in another embodiment of the present invention. FIG. 4 is a diagram corresponding to FIG. 3 in another embodiment of the present invention. FIG. 4 is a diagram corresponding to FIG. 3 in another embodiment of the present invention. FIG. 4 is a diagram corresponding to FIG. 3 in another embodiment of the present invention. FIG. 4 is a diagram corresponding to FIG. 3 in another embodiment of the present invention. FIG. 4 is a diagram corresponding to FIG. 3 in another embodiment of the present invention. It is the figure which looked at the nozzle part of the conventional group III halide gas supply means used by the comparative example 1 from the front, and is a figure corresponding to FIG. It is the graph which plotted the result of Examples 1-2 and the comparative example 1. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawing, some symbols may be omitted. In the present specification, “A to B” for the numerical values A and B means “A or more and B or less” unless otherwise specified. In the notation, when the unit of the numerical value A is omitted, the unit attached to the numerical value B is applied as the unit of the numerical value A. In addition, the form shown below is an illustration of this invention and this invention is not limited to these forms.

<1. Crystal growth equipment>
The crystal growth apparatus according to the first aspect of the present invention will be described. FIG. 1 is a schematic diagram of a crystal growth apparatus 100 according to an embodiment of the present invention. The crystal growth apparatus 100 includes a reactor 10 having a reaction zone 20 for growing a group III nitride on a substrate by reacting a group III halide gas and a nitrogen source gas, and a group III halide gas in the reaction zone 20. A group III halide gas supply means 30 and a nitrogen source gas supply means 40 for supplying a nitrogen source gas to the reaction zone 20.

  The reactor 10 has an outer chamber 11 and an inner chamber 12 formed inside the outer chamber 11, and the inner chamber 12 has a reaction zone 20 inside the inner chamber 12. A support base (susceptor) 22 is installed in the reaction zone 20, and the support base 22 is connected to a rotary drive shaft 23 to rotatably support the substrate 21. The rotary drive shaft 23 transmits power from an electric motor (not shown) to the support base 22, and rotates the support base 22 at an appropriate rotational speed. The reactor 10 further has a heating means 24 such as a high-frequency coil for heating the support base 22. In addition, as long as the support base 22 can be heated appropriately as a heating means 24, a well-known heating means other than a high frequency coil can be employ | adopted.

  The group III halide gas supply means 30 is arranged to blow out the group III halide gas from the upper side of the support table 22 toward the upper side of the support table 22. The group III halide gas supply means 30 has a first outlet 31 through which the group III halide gas flows out and a second outlet 32 through which the barrier gas flows out. The second air outlet 32 is provided so as to surround the first air outlet.

The nitrogen source gas supply means 40 is a nitrogen source from above the support base 22 and from above the first blowout port 31 and the second blowout opening 32 of the group III halide gas supply means 30 to above the support stand 22. It arrange | positions so that gas may be blown out.
By disposing the nitrogen source gas supply means 40 above the group III halide gas supply means 30, the nitrogen source gas can be uniformly supplied onto the support base 22. Further, the nitrogen source gas supply means 40 is preferably disposed above the group III halide gas supply means 30, but when ammonia gas is used as the nitrogen source gas, the ammonia gas is relatively diffused. Since it is easy, the nitrogen source gas supply means 40 can be disposed below the group III halide gas supply means 30.

  In this embodiment, since the inner chamber 12 of the reactor 10 has the reaction zone 20 inside, it may be composed of a heat-resistant and acid-resistant nonmetallic material such as quartz glass, alumina, sapphire, and heat-resistant glass. Preferably, the group III halide gas supply means 30 and the nitrogen source gas supply means 40 are also made of the same material. The outer chamber 11 may be made of the same material as the inner chamber 12. However, since the outer chamber 11 is not in direct contact with the reaction zone 20, it can be made of a general metal material such as stainless steel.

  In FIG. 1, the left-right direction on the paper is the X direction, the vertical direction on the paper is the Z direction, and the direction perpendicular to the paper is the Y direction. The first outlet 31 has a shape in which the maximum width in the Y direction is larger than the maximum width in the vertical direction (that is, the Z direction). 2 is a top view of the group III halide gas supply means 30 and the support base 22 shown in FIG. 1 (a view taken along the line A-A 'in FIG. 1). In FIG. 2, for the convenience of explanation, only the first outlet 31 and the group III halide gas flow path of the group III halide gas supply means 30 are shown, and the second outlet 32 and the flow of the barrier gas are shown. The road is omitted from the figure. The Y direction will be further described with reference to FIG.

In FIG. 2, one outermost end P of the first blowing port 31 has a straight line passing through the rotation center C of the support base 22 outside the one outermost opening 31 a of the first blowing port 31 ( In FIG. 2, the contact point is the contact point from the side where the absolute value of the angle formed by the straight line passing through the rotation center C and the X direction increases. The other outermost end Q of the first outlet 31 is a contact point where a straight line passing through the rotation center C of the support base 22 contacts the other outermost opening 31b of the first outlet 31 from the outside. is there.
In FIG. 2, the Y direction is a direction orthogonal to the straight line MC passing through the midpoint M of the line segment PQ and the rotation center C of the support base 22. In FIG. 2, the Y direction is the same as the vertical direction of the paper surface, and in FIG. 1, the Y direction is the same as the direction perpendicular to the paper surface.

The maximum width a in the Y direction of the first outlet 31 and the maximum width D of the support base 22 are also shown in FIG. In the crystal growth apparatus 100 of the present invention, the value of the ratio a / D needs to be 0.05 to 2, preferably 0.1 or more, more preferably 0.3 or more, and preferably 1 .8 or less, more preferably 1.5 or less.
When the value of the ratio a / D is 0.05 to 2, the group III halide gas can be uniformly supplied onto the support base 22.

FIG. 3 is a BB ′ arrow view of FIG. 1, and is a view of the nozzle of the group III halide gas supply means 30 as viewed from the front in the X direction. The nozzle of the group III halide gas supply means 30 will be further described with reference to FIG.
The nozzle of the group III halide gas supply means 30 has a first outlet 31 through which the group III halide gas flows out and a second outlet 32 through which the barrier gas flows out. The first outlet 31 has two openings 31a and 31b, which are defined by the partition walls 31w _a and 31w _b and separated in the Y direction, from which the group III halide gas flows out. The two openings 31a and 31b do not have overlapping portions in a top view (Z direction). The outer wall 30w surrounds the two openings 31a and 31b and the partition walls 31w _a and 31w _b , so that the second outlet 32 is located between the outer wall 30w and the partition walls 31w _a and 31w _b. Is provided so as to surround. In other words, the second outlet 32 is constituted by one opening provided so as to surround the entire circumference of the first outlet 31. The first outlet 31 has a shape in which the maximum width a in the Y direction is larger than the maximum width b in the vertical direction (Z direction).

In FIG. 3, for two adjacent openings 31 a and 31 b of the first outlet 31, the distance d _ab between which the two openings 31 a and 31 b are separated in the horizontal direction (Y direction), and the 2 The ratio of each of the openings 31a and 31b to the maximum horizontal width c _a and c _{b in} the horizontal direction (Y direction): the values of d _ab / c _a and d _ab / c _b are both 0.1 to 10 Preferably there is. The lower limit is more preferably 0.2 or more, still more preferably 0.5 or more, and the upper limit is more preferably 5 or less, still more preferably 3 or less.
Opening 31a, III Group halide gas discharged from 31b is to be discharged radiate, the value of the ratio _(d ab / _{c a} and _d ab / _{c b)} is 0.1 to 10 Thus, the group III halide gas can be efficiently supplied onto the support table 22 (on the substrate 21).

  The group III halide gas supply means 30 has a single group III halide gas supply pipe 30a, and a single III group is provided in any of the plurality of openings 31a and 31b of the first outlet 31. The group III halide gas is guided through the group halide gas supply pipe 30a (see FIG. 2). According to such a configuration, the configuration of the apparatus can be simplified.

According to the crystal growth apparatus of the present invention, it is possible to improve the uniformity of the growth film thickness when the group III nitride is grown on a wide substrate by the HVPE method. The reason is guessed as follows. That is, when the nozzle of the group III halide gas supply means is flat and has the predetermined a / D ratio, the supply amount of the group III halide gas on the growth surface of the substrate and the nitrogen source gas on the growth surface of the substrate It is thought that both the supply amount and the supply amount become more uniform, and as a result, unevenness in the generation rate of the group III nitride depending on the position on the substrate is reduced.
Therefore, the crystal growth apparatus of the present invention can be suitably used for crystal growth on a substrate having a large diameter, for example, a substrate having a longest diameter of 20 mm or more. The crystal growth apparatus of the present invention can also be suitably used when a plurality of substrates are arranged on the support base 22 and crystals are grown on the respective substrates.

  In the above description regarding the present invention, as shown in FIG. 2, the group III halide gas supply means 30 has a single group III halide gas supply pipe 30a, and a plurality of openings of the first outlet 31 are provided. In both 31a and 31b, the crystal growth apparatus 100 in which the group III halide gas is guided through the single group III halide gas supply pipe 30a is illustrated, but the present invention is not limited to this form. The group III halide gas supply means has a plurality of group III halide gas supply pipes including a first group III halide gas supply pipe and a second group III halide gas supply pipe, and the first blowout A plurality of openings in the mouth include a first opening through which a group III halide gas is introduced through a first group III halide gas supply pipe, and a group III halide gas through a second group III halide gas supply pipe. It is also possible to have a form having at least a second opening through which is guided. A diagram corresponding to FIG. 2 in such another embodiment is shown in FIG. In FIG. 4, the group III halide gas is introduced into the first opening 31a of the first outlet 31 through the first group III halide gas supply pipe 30a, and the second opening 31b is supplied with the second opening 31a. The group III halide gas is led through the group III halide gas supply pipe 30b. According to such a configuration, the flow rate control device is individually provided for each of the plurality of group III halide gas supply pipes 30a and 30b, thereby improving the uniformity of the supply amount of the group III halide gas on the substrate. Becomes easier.

In the above description relating to the present invention, the crystal growth apparatus 100 in a form in which the plurality of openings 31a and 31b of the first outlet 31 of the group III halide gas supply means 30 do not have overlapping portions in a top view (FIG. However, the present invention is not limited to this form. It is also possible to provide a crystal growth apparatus having a configuration in which the plurality of openings of the first outlet included in the group III halide gas supply means have overlapping portions in a top view. FIG. 5 shows a view of the nozzle of the group III halide gas supply means 30 ′ viewed from the front in the X direction according to another embodiment. FIG. 5 corresponds to FIG. The nozzle of the group III halide gas supply means 30 ′ shown in FIG. 5 has a first outlet 31 ′ through which the group III halide gas flows out and a second outlet 32 ′ through which the barrier gas flows out. The first outlet 31 ′ has two openings 31 _a ′ and 31 _b ′ defined by the partition walls 31 w _a ′ and 31 w _b ′ and spaced apart in the Y direction, from which the group III halide gas flows out. . The two openings 31a ′ and 31b ′ have overlapping portions in a top view (Z direction). The second opening 31a ′, 31b ′ and the partition walls 31w _a ′, 31w _b ′ are surrounded by the outer wall 30w ′, so that the second outlet is provided between the outer wall 30w ′ and the partition walls 31w _a ′, 31w _b ′. 32 'is provided so as to surround the first outlet 31'. The effect of the present invention can also be achieved by a crystal growth apparatus provided with a group III halide gas supply means having the first blowout port 31 'and the second blowout port 32' having such a configuration.

In the above description regarding the present invention, the plurality of openings of the first outlet 31 of the group III halide gas supply means 30, that is, the first opening 31a and the second opening 31b are separated from each other. the partition wall 31w _a and 31w _b crystal growth apparatus 100 forms are separated by a mainly exemplified, but the present invention is not limited to this embodiment. It is also possible to provide a crystal growth apparatus in which the partition walls that separate the plurality of openings of the first outlet are integrally formed. FIG. 6 shows a view of the nozzle of the group III halide gas supply means 30 ″ according to another embodiment as viewed from the front in the X direction. FIG. 6 corresponds to FIG. In FIG. 6, the nozzle of the group III halide gas supply means 30 ″ has a first outlet 31 ″ through which the group III halide gas flows out and a second outlet 32 ″ through which the barrier gas flows out. Have. The first outlet 31 '' is defined by a single integral partition wall 31w _ab is and spaced in the Y direction, the two openings 31a of group III halide gas flows out '', the 31b '' Have. The two openings 31a '' and 31b '' do not have overlapping portions in the top view (Z direction). The outer wall 30w '' surrounds the two openings 31a '' and 31b '' and the partition wall 31w _ab , so that the second outlet 32 '' is formed between the outer wall 30w '' and the partition wall 31w _ab . Is provided so as to surround the outlet 31 ''. As shown in FIG. 6, the maximum width (c _a , c _b ) in the Y direction of each opening (31a ″, 31b ″) of the first outlet is the first outlet (31 ″). ) May be different from the maximum width (b) in the vertical direction (Z direction). According to such a form, in the reaction zone 20, the nitrogen source gas and the group III halide gas are easily mixed and the reaction efficiency is improved.

In the above description related to the present invention, the crystal growth apparatus 100 in the form in which the second blowing port 32 is configured by one opening provided so as to surround the entire circumference of the first blowing port 31 is mainly exemplified. However, the present invention is not limited to this form. The second blow-out port of the group III halide gas supply means is configured by a plurality of openings through which the barrier gas flows out so as to surround each of the plurality of openings of the first blow-out port. It is also possible to provide a crystal manufacturing apparatus of a certain form. FIG. 7 shows a view of the nozzle of the group III halide gas supply means 30 ′ ″ as seen from the front in the X direction according to another embodiment. FIG. 7 corresponds to FIG. In FIG. 7, the nozzle of the group III halide gas supply means 30 ′ ″ includes a first outlet 31 ′ ″ through which the group III halide gas flows out and a second outlet 32 ″ through which the barrier gas flows out. 'And have. The first outlet 31 ′ ″ has two openings 31a ′ ″ defined by the partition walls 31w _a ′ ″ and 31w _b ′ ″ and separated from each other in the Y direction, from which a group III halide gas flows out. , 31b ′ ″. The two openings 31a ′ ″ and 31b ′ ″ do not have overlapping portions in the top view (Z direction). The outer wall 30w _a ′ ″ surrounds the opening 31a ′ ″ and the partition wall 31w _a ′ ″ of the first outlet 31 ′ ″, so that the outer wall 30w _a ′ ″ and the partition wall 31w _a ′ ″ In the middle, the opening 32a ′ ″ of the second outlet 32 ′ ″ is provided so as to surround the opening 31a ″ ′ of the first outlet 31 ′ ″. 'The outer wall 30 w _b' first outlet 31 '''opening 31b of the''' and the partition wall 31w _{b ''} by surrounding the 'also' and partition wall 31w _{b 'outer} wall 30 w _b' 'and'' In the meantime, the opening 32b ′ ″ of the second outlet 32 ′ ″ is provided so as to surround the opening 31b ′ ″ of the first outlet 31 ′ ″. The two openings 32a ′ ″ and 32b ′ ″ of the second outlet 32 ′ ″ are spaced apart in the Y direction by partition walls 30w _a ′ ″ and 30w _b ′ ″. In this way, the second outlet 32 ′ ″ is provided so as to surround each of the plurality of openings 31a ′ ″ and 31b ′ ″ of the first outlet 31 ′ ″. In addition, a plurality of openings 32a ′ ″ and 32b ′ ″ through which the barrier gas flows out are configured.

In the above description regarding the present invention, the crystal growth apparatus 100 in which the first outlet 31 of the group III halide gas supply means 30 has the two openings 31a and 31b is mainly exemplified. It is not limited to. It is also possible to provide a crystal growth apparatus in which the first outlet of the group III halide gas supply means has three or more openings through which the group III halide gas flows out. The figure which looked at the nozzle of the group III halide gas supply means 30 ⁽⁴⁾ in other one such embodiment from the front of the X direction is shown in FIG. FIG. 8 corresponds to FIG. In FIG. 8, the nozzles of the group III halide gas supply means 30 ⁽⁴⁾ include a first outlet 31 ^{(4) through} which the group III halide gas flows out and a second outlet 32 ^{(4 ) through} which the barrier gas flows out. ⁾ . The first outlet 31 ⁽⁴⁾ has three openings 31a ⁽⁴⁾ , 31b ⁽ 31 ⁾ defined by the partition walls 31w _a ⁽⁴⁾ , 31w _b ⁽⁴⁾ , 31w _c ⁽⁴⁾ and separated in the Y direction. ⁴⁾ and 31c ⁽⁴⁾ . The three openings 31a ⁽⁴⁾ , 31b ⁽⁴⁾ , 31c ⁽⁴⁾ do not have overlapping portions in the top view (Z direction). The outer wall 30w ⁽⁴⁾ surrounds the three openings 31a ⁽⁴⁾ , 31b ⁽⁴⁾ , 31c ⁽⁴⁾ and the partition walls 31w _a ⁽⁴⁾ , 31w _b ⁽⁴⁾ , 31w _c ⁽⁴⁾ by the outer wall 30w. The second outlet 32 ⁽⁴⁾ surrounds the first outlet 31 ⁽⁴⁾ between ⁽⁴⁾ and the partition walls 31w _a ⁽⁴⁾ , 31w _b ⁽⁴⁾ , 31w _c ^(4). Is provided.
In FIG. 8, a set of two adjacent openings (that is, 31a ⁽⁴⁾ and a plurality of openings 31a ⁽⁴⁾ , 31b ⁽⁴⁾ , 31c ^{(4) included} in the first outlet 31 ^(4). 31b ⁽⁴⁾ and 31b ⁽⁴⁾ and 31c ⁽⁴⁾⁾ , the distance d (that is, d _ab ) that the two adjacent openings are separated in the Y direction when viewed from above. , D _bc ) and the respective ratios d / c ₁ and d / c ₂ of the maximum widths c ₁ and c _{2 in} the Y direction of each of the two adjacent openings (ie, d _ab / c _a and d _ab / C _b , and both d _bc / c _b and d _bc / c _c , in other words, all of d _ab / c _a , d _ab / c _b , d _bc / c _b , d _bc / c _c ) Is preferably from 0.1 to 10 and the lower limit is Preferably 0.2 or more, even more preferably 0.5 or more, its upper limit is more preferably 5 or less, more preferably 3 or less.
The number of openings through which the group III halide gas flows out of the first outlet 31 ⁽⁴⁾ is preferably 8 or less, and preferably 4 or less, so as not to impair the effects of the present invention. Is more preferable.

In the above description of the present invention, the first outlet 31 of the group III halide gas supply means 30, one or more partition walls _31w a, spaced in the Y direction by 31w _b, group III halide gas flows out 2 Although the crystal growth apparatus 100 having the form having the two openings 31a and 31b is mainly exemplified, the present invention is not limited to the form. The first blowout port of the group III halide gas supply means has a protrusion provided so as to narrow the flow path of the group III halide gas at least at the opening of the first blowout port, The opening of the air outlet connects the first region, the second region separated from the first region in the Y direction, the first region and the second region, and the first region and the second region. It is also possible to provide a crystal growth apparatus that includes a third region that is narrower in the vertical direction than this region. FIG. 9 shows a view of the nozzle of the group III halide gas supply means 30 ^{(5) according} to another embodiment as viewed from the front in the X direction. FIG. 9 corresponds to FIG. In FIG. 9, the nozzles of the group III halide gas supply means 30 ⁽⁵⁾ include a first outlet 31 ^{(5) through} which the group III halide gas flows out and a second outlet 32 ^{(5 ) through} which the barrier gas flows out. ⁾ . The first outlet 31 ⁽⁵⁾ is separated from the second outlet 32 ⁽⁵⁾ by an integral partition wall 31w ⁽⁵⁾ , and the outer wall 30w ⁽⁵⁾ surrounds the partition wall 31w ⁽⁵⁾ . The second outlet 32 ⁽⁵⁾ is provided so as to surround the entire circumference of the first outlet 31 ⁽⁵⁾ . The partition wall 31w ⁽⁵⁾ has protrusions 31p and 31p provided so as to narrow the flow path of the group III halide gas at the opening of the first outlet 31 ⁽⁵⁾ . Due to the presence of the protrusions 31p, 31p, the opening of the first outlet 31 ⁽⁵⁾ has a first region 31R1, a second region 31R2 separated from the first region 31R1 in the Y direction, and a second region 31R2. The first region 31R1 and the second region 31R2 are connected to each other, and the third region 31R3 is narrower in the vertical direction (Z direction) than the first region 31R1 and the second region 31R2. The effect of the present invention can also be achieved by such a form. In such an embodiment, the width of the opening of the first outlet 31 ⁽⁵⁾ is 80% in the vertical direction (Z direction) with respect to the maximum width b in the vertical direction (Z direction) (b in FIG. 9). when the width of the Y direction of _th) is less than or equal parts as _{c narrow,} it is preferable _{c narrow} is 10 to 90% of the maximum width a of the Y direction of the opening of the first outlet ^{31 (5)} . Furthermore, when c _narrow satisfies 10 to 90% of the maximum width a in the Y direction of the opening of the first outlet 31 ⁽⁵⁾ , the third region 31R3 is 1 as shown in FIG. It may be a place, or a plurality of places as shown in FIG. FIG. 10 is a view corresponding to FIG. 9, and the partition wall 31 w ⁽⁶⁾ in FIG. 10 is provided so as to narrow the group III halide gas flow path at the opening of the first outlet 31 ^(6). Projecting portions 31p ′, 31p ′, 31p ′, 31p ′ (hereinafter sometimes simply referred to as “31p ′”). Due to the presence of the protruding portion 31p ′, the opening of the first outlet 31 ⁽⁶⁾ has a first region 31R1 ′ and a second region 31R2 ′ separated from the first region 31R1 ′ in the Y direction. The third region 31R3 ′ connecting the first region 31R1 ′ and the second region 31R2 ′ and having a narrower width in the vertical direction (Z direction) than the first region 31R1 ′ and the second region 31R2 ′ Further, the first region 31R1 ″ separated from the second region 31R2 ′ in the Y direction, the first region 31R1 ″ and the second region 31R2 ′ are connected, and the first region 31R1 ″ and the first region And a third region 31R3 ″ having a narrower width in the vertical direction (Z direction) than the second region 31R2 ′. As shown in FIG. 10, when there are a plurality of third regions (for example, 31R3 ′ and 31R3 ″ in FIG. 10), c _narrow is a total width thereof (for example, c _narrow ¹ + c _narrow in FIG. 10). ² ). In addition, when there are a plurality of third regions, there are three or more regions other than the third region (that is, the first region and / or the second region). In this case, The number of regions other than the third region (that is, the number of the third regions + 1, for example, 2 in FIG. 9 and 3 in FIG. 10) is 8 so as not to impair the effects of the present invention. Or less, more preferably 4 or less.
9 and 10, the protruding portions 31p are provided on both the upper and lower sides of the inner walls of the partition walls 31w ⁽⁵⁾ and 31w ⁽⁶⁾ , but may be provided only on one side.

  1 to 10 exemplify the embodiment of the present invention, among which the first outlet 31 and the second outlet 32 of the group III halide gas supply means 30 are symmetrical (that is, normal to the YZ plane). It is preferable that the projection is symmetrical with respect to the Z axis. Specifically, in a view of the nozzle portion of the group III halide gas supply means 30 as viewed from the front in the X direction (ie, orthogonal projection onto the YZ plane), FIG. 3, FIG. 6, FIG. 7, FIG. As shown in FIG. 10, it is preferable that the first outlet 31 and the second outlet 32 of the group III halide gas supply means 30 are symmetrical (that is, symmetrical about the Z axis). By making the first blowout port 31 and the second blowout port 32 bilaterally symmetric, the group III halide gas and the nitrogen source gas can be supplied more uniformly onto the support base 22 (on the substrate 21). It becomes.

<2. Method for Producing Group III Nitride>
A method for producing a group III nitride according to the second aspect of the present invention will be described. The method for producing a group III nitride according to the present invention is a method for producing a group III nitride by an HVPE method, wherein a group III nitride single crystal is produced using the crystal growth apparatus according to the first aspect of the present invention. It is characterized by growing.

  The group III halide gas flowing out from the group III halide gas supply means 30 in the crystal growth apparatus 100 (FIG. 2) includes aluminum halides such as aluminum trichloride and aluminum tribromide; gallium trichloride, gallium monochloride, etc. A group III halide gas such as indium halide such as indium trichloride or the like can be used without particular limitation. When producing a mixed crystal, a mixed gas containing a plurality of group III halide gases is used. In general, when an aluminum halide gas having a high reaction rate is used, the crystal growth apparatus of the present invention contains aluminum as a group III element because unevenness in the growth rate is likely to occur, particularly depending on the location on the substrate. It can be particularly preferably used when growing a single crystal of a group III nitride (hereinafter sometimes referred to as “Al group III nitride”), and is most preferably used when growing a single crystal of aluminum nitride. it can. From this viewpoint, in the Group III nitride production method of the present invention, the Group III halide gas preferably contains an aluminum halide gas, and the Group III halide gas is particularly preferably an aluminum halide gas.

  The barrier gas flowing out from the group III halide gas supply means 30 in the crystal growth apparatus 100 is inactive, and the diffusion of the group III halide gas or nitrogen source gas into the barrier gas is slow due to its large molecular weight ( Nitrogen gas, argon gas, or a mixed gas thereof can be preferably used in terms of a high barrier effect. However, in order to adjust the effect of the barrier gas, nitrogen gas or argon gas or a mixed gas thereof is inert to hydrogen gas, helium gas, neon gas, etc. (ie, does not react with group III halide gas and nitrogen source gas) ) Low molecular weight gas may be mixed.

  Examples of the material of the substrate 21 on which the group III nitride single crystal is deposited include, for example, sapphire, silicon, silicon carbide, zinc oxide, gallium nitride, aluminum nitride, aluminum gallium nitride, gallium arsenide, zirconium boride, and titanium boride. Can be used without restriction.

  In order to obtain a group III nitride single crystal by nitriding the group III halide gas supplied from the group III halide gas supply means 30 to the reaction zone 20, the nitrogen source gas is caused to flow out from the nitrogen source gas supply means 40. This nitrogen source gas is usually supplied in a state diluted with a carrier gas. As the nitrogen source gas, a reactive gas containing nitrogen can be used without particular limitation, but ammonia gas can be preferably used from the viewpoint of cost and ease of handling. As the carrier gas, hydrogen gas, nitrogen gas, helium gas, argon gas, or a mixed gas thereof can be used without particular limitation, and a carrier gas containing hydrogen gas is preferably used.

  Before the reaction between the group III halide gas and the nitrogen source gas, the substrate 21 is supported on the support base 22 while circulating a carrier gas containing hydrogen gas in the reaction zone 20 in order to remove organic substances adhering to the substrate 21. It is preferable to perform thermal cleaning by heating through. When a sapphire substrate is used as the substrate 21, it is generally held at 1100 ° C. for about 10 minutes. Thereafter, the group III halide gas is supplied from the group III halide gas supply means 30 to the reaction zone 20, and the nitrogen source gas is supplied from the nitrogen source gas supply means 40 to the reaction zone 20, preferably at 1000 to 1700 ° C. A group III nitride single crystal is grown on the heated substrate 21. The growth of the group III nitride in the present invention is usually performed under a pressure near atmospheric pressure.

  The supply amount of the group III halide gas may be controlled by the volume flow rate in the standard state, but it is easy to understand if it is determined by the partial pressure. That is, the ratio of the volume in the standard state of the group III halide gas to the total volume in the standard state of all gases (carrier gas, group III halide gas, nitrogen source gas, barrier gas) supplied onto the substrate is the group III halogen. The supply partial pressure of the chemical gas is used.

  A concentration range of 1 Pa to 1000 Pa is selected as the supply partial pressure of the group III halide gas. The supply amount of the nitrogen source gas is not particularly limited, but in general, a supply amount of 0.5 to 500 times that of the group III halide gas to be supplied is suitably selected. The growth time is appropriately adjusted so that a desired growth film thickness is achieved. After crystal growth for a certain time, the crystal growth is terminated by stopping the supply of the group III halide gas. Thereafter, the substrate 21 is cooled to room temperature. Through the above operation, a group III nitride single crystal can be grown on the substrate 21.

  EXAMPLES Hereinafter, although this invention is explained in full detail based on an Example and a comparative example, this invention is not limited to these Examples.

<Example 1>
An aluminum nitride single crystal was grown on a sapphire single crystal substrate by the crystal growth apparatus 100 of FIG. While rotating a square substrate having a maximum diameter of 48 mm held on the support base 22 at a speed of 10 revolutions / minute, aluminum chloride gas is supplied from the group III halide gas supply means 30 and ammonia is supplied from the nitrogen source gas supply means 40. Gas was supplied and allowed to grow for 20 minutes. The planar shape of the support base 22 was the same as that of the substrate (that is, D = 48 mm). The nozzle shape of the group III halide gas supply means 30 is as follows. In FIG. 6, a = 15 mm, b = c _a = c _b = 5 mm, d _ab = 5 mm, a / D = 0.31, d _ab / c _a = The shape was d _ab / c _b = 1. After completion of the growth, the growth film thickness was measured every 4 mm from the center of the substrate to evaluate the growth rate. The results are shown in FIG.

<Example 2>
The nozzle shape of the group III halide gas supply means 30 is as follows. In FIG. 6, a = 20 mm, b = c _a = c _b = 5 mm, d _ab = 10 mm, a / D = 0.42, d _ab / c _a = d An aluminum nitride single crystal was grown on the sapphire single crystal substrate in the same manner as in Example 1 except that the shape was _ab / c _b = 2. The results are shown in FIG.

<Comparative Example 1>
The nozzle shape of the group III halide gas supply means 30 is the conventional shape shown in FIG. 11, where a = c = b = 7.5 mm, d = 0 mm, a / D = 0.16, d / c = An aluminum nitride single crystal was grown on the sapphire single crystal substrate in the same manner as in Example 1 except that the shape was 0. The results are shown in FIG.

<Evaluation results>
As shown in FIG. 12, in contrast to Comparative Example 1 in which aluminum nitride is grown by a crystal growth apparatus in which aluminum chloride gas is supplied from a nozzle having a conventional shape, aluminum nitride is deposited by the crystal growth apparatus according to the present invention. In the grown Examples 1 and 2, the difference in growth rate due to the distance from the center of the substrate was alleviated.

  From the above results, according to the present invention, it was shown that the uniformity of the growth film thickness can be improved when a group III nitride is grown on a wide substrate by the HVPE method.

DESCRIPTION OF SYMBOLS 100 Crystal growth apparatus 10 Reactor 11 Outer chamber 12 Inner chamber 20 Reaction zone 21 Substrate 22 Support stand (susceptor)
23 Rotating drive shaft 24 Heating means 30 Group III halide gas supply means 30a, 30b Group III halide gas supply pipe 30w Outer wall 31 (Group III halide gas flows out) First outlet 31a, 31b (Group III halogen) product of the gas supply means) opening _31w, 31w _a, the opening of 31w _b partition wall 31p projecting portion 31R1 (III group halide gas supply means) of the opening of the first region 31R2 (III group halide gas supply means ) Second region 31R3 Third region 32 (at the opening of the group III halide gas supply means) Second blowout port 40 (where the barrier gas flows out) Nitrogen source gas supply unit 50 Exhaust port

Claims (11)

A reactor having a reaction zone for growing a group III nitride on a substrate by reacting a group III halide gas and a nitrogen source gas;
A group III halide gas supply means for supplying the group III halide gas to the reaction zone;
In a crystal growth apparatus having a nitrogen source gas supply means for supplying the nitrogen source gas to the reaction zone,
The reactor has a support base in the reaction zone for rotatably supporting the substrate,
The group III halide gas supply means is arranged to blow out the group III halide gas from the upper side of the support base toward the upper side of the support base,
The group III halide gas supply means has a first outlet from which the group III halide gas flows out and a second outlet from which the barrier gas flows out. 1 is placed around the outlet,
The first outlet has a shape in which the maximum width in the Y direction is larger than the maximum width in the vertical direction, and the Y direction is a horizontal direction and is the top of one of the first outlets in a top view. It is a direction perpendicular to a midpoint of a line segment connecting the outer end and the other outermost end and a straight line passing through the center of rotation of the upper surface of the support base, and the one outermost end and the other outermost end are respectively viewed from above. The straight line passing through the rotation center is a contact point that contacts the outermost opening of the first outlet from the outside, and the maximum width in the Y direction of the first outlet is the top view in the top view. The length in the Y direction of the line segment connecting one outermost end of the first outlet and the other outermost end;
And a maximum width a in the Y direction of the first outlet, the ratio a / D of the maximum width D of the support base is state, and are 0.05 to 2,
The crystal growth apparatus , wherein the first outlet has a plurality of openings separated in the Y direction by one or more partition walls . The plurality of openings of the first outlet do not have overlapping portions in a top view;
The crystal growth apparatus according to claim 1 . The distance d between the two openings adjacent to each other among the plurality of openings of the first blowout opening in the horizontal direction when viewed from above, and the two Both the ratios d / c ₁ and d / c ₂ of the horizontal maximum widths c ₁ and c ₂ of the openings are 0.1 or more and 10 or less,
The crystal growth apparatus according to claim 1 . The group III halide gas supply means has a single group III halide gas supply pipe;
The group III halide gas is introduced into any of the plurality of openings of the first outlet through the single group III halide gas supply pipe.
The crystal growth apparatus in any one of Claims 1-3 . The group III halide gas supply means has a plurality of group III halide gas supply pipes including a first group III halide gas supply pipe and a second group III halide gas supply pipe;
The plurality of openings of the first outlet include a first opening through which the group III halide gas is guided through the first group III halide gas supply pipe, and a second group III halide gas. And at least a second opening through which the group III halide gas is led through a supply pipe,
The crystal growth apparatus in any one of Claims 1-3 . The second outlet is configured by one opening provided so as to surround the entire circumference of the first outlet.
The crystal growth apparatus in any one of Claims 1-5 . The second outlet is constituted by a plurality of openings provided so as to surround each of the plurality of openings of the first outlet.
The crystal growth apparatus in any one of Claims 1-5 . A reactor having a reaction zone for growing a group III nitride on a substrate by reacting a group III halide gas and a nitrogen source gas;
A group III halide gas supply means for supplying the group III halide gas to the reaction zone;
A nitrogen source gas supply means for supplying the nitrogen source gas to the reaction zone;
In a crystal growth apparatus having
The reactor has a support base in the reaction zone for rotatably supporting the substrate,
The group III halide gas supply means is arranged to blow out the group III halide gas from the upper side of the support base toward the upper side of the support base,
The group III halide gas supply means has a first outlet from which the group III halide gas flows out and a second outlet from which the barrier gas flows out. 1 is placed around the outlet,
The first outlet has a shape in which the maximum width in the Y direction is larger than the maximum width in the vertical direction, and the Y direction is a horizontal direction and is the top of one of the first outlets in a top view. It is a direction perpendicular to a midpoint of a line segment connecting the outer end and the other outermost end and a straight line passing through the center of rotation of the upper surface of the support base, and the one outermost end and the other outermost end are respectively viewed from above. The straight line passing through the rotation center is a contact point that contacts the outermost opening of the first outlet from the outside, and the maximum width in the Y direction of the first outlet is the top view in the top view. The length in the Y direction of the line segment connecting one outermost end of the first outlet and the other outermost end;
The ratio a / D between the maximum width a in the Y direction of the first outlet and the maximum width D of the support base is 0.05 or more and 2 or less,
The first outlet has a protrusion provided so as to narrow the channel of the group III halide gas at least in the opening of the first outlet;
An opening of the first blowout port connects the first region, the second region separated from the first region in the Y direction, the first region, and the second region; and a said first region and said narrow vertical width than the second region the third region, crystal growth apparatus. The nitrogen source gas supply means is disposed so as to blow out the nitrogen source gas from above the support base and from above the first blowout port and the second blowout port to above the support stand. and that the crystal growth device according to any one of claims 1-8. The group III halide gas is an aluminum halide gas;
The barrier gas includes nitrogen gas or argon gas,
The nitrogen source gas is ammonia gas;
The III nitride is a nitride aluminum,
Crystal growing apparatus according to any one of claims 1-9. A method for producing a group III nitride, wherein a group III nitride single crystal is grown on a heated substrate by reacting a group III halide gas and a nitrogen source gas,
Method of manufacturing according to claim 1, characterized in that to produce a group-III nitride single crystal using the crystal growth apparatus according to any one of 10, III-nitride.