JP2014241417A - Aluminum-containing nitride intermediate layer manufacturing method, nitride layer manufacturing method and nitride semiconductor element manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a nitride layer having excellent crystallinity on an aluminum-containing nitride intermediate layer.SOLUTION: A nitride semiconductor layer manufacturing method comprises: a step of arranging a sapphire substrate having a c-plane as a principal surface and an aluminum-containing target at a distance of not less than 100 mm and not more than 250 mm from each other; a step of forming an aluminum-containing nitride intermediate layer composed of an aggregate of columnar crystals of aligned crystal grains which extend in a normal direction of a growth surface of the substrate on a surface of the substrate by a DC magnetron sputtering method performed by application of a voltage by a DC-continuous method to between the substrate and the target; and a step of forming a nitride semiconductor on the aluminum-containing nitride intermediate layer. In the step of arranging the substrate and the target, the substrate and the target are arranged in a manner such that the target tilts to the substrate.

Description

  The present invention relates to a method for producing an aluminum-containing nitride intermediate layer, a method for producing a nitride layer, and a method for producing a nitride semiconductor device.

  Since the III-V compound semiconductor (group III nitride semiconductor) containing nitrogen has a band gap corresponding to the energy of light having a wavelength in the infrared to ultraviolet region, the wavelength in the infrared to ultraviolet region is changed. It is useful as a material for a light emitting element that emits light having a wavelength and a light receiving element that receives light having a wavelength in the region.

  In addition, group III nitride semiconductors have strong bonds between atoms constituting group III nitride semiconductors, high dielectric breakdown voltage, and high saturation electron velocity. Therefore, electronic devices such as high temperature resistance, high output, and high frequency transistors It is also useful as a material.

  Furthermore, group III nitride semiconductors are attracting attention as materials that are hardly harmful to the environment and are easy to handle.

  In order to produce a practical nitride semiconductor device using a group III nitride semiconductor, which is an excellent material as described above, a group III nitride semiconductor comprising a group III nitride semiconductor thin film on a predetermined substrate The layers need to be stacked to form a predetermined device structure.

  Here, as the substrate, it is most preferable to use a substrate made of a group III nitride semiconductor having a lattice constant or a thermal expansion coefficient capable of directly growing a group III nitride semiconductor on the substrate. As the substrate made of a nitride semiconductor, for example, a gallium nitride (GaN) substrate is preferably used.

  However, the GaN substrate is not practical because its size is currently as small as 2 inches in diameter and is very expensive.

  Therefore, at present, a sapphire substrate, a silicon carbide (SiC) substrate, or the like that has a large lattice constant difference and a large thermal expansion coefficient difference from the group III nitride semiconductor is used as a substrate for manufacturing a nitride semiconductor element.

  There is a lattice constant difference of about 16% between the sapphire substrate and GaN, which is a typical group III nitride semiconductor. Further, there is a lattice constant difference of about 6% between the SiC substrate and GaN. When such a large lattice constant difference exists between the substrate and the group III nitride semiconductor grown thereon, it is generally difficult to epitaxially grow a group III nitride semiconductor crystal on the substrate. It is. For example, when a GaN crystal is directly epitaxially grown on a sapphire substrate, there is a problem that a three-dimensional growth of the GaN crystal is inevitable and a GaN crystal having a flat surface cannot be obtained.

  Therefore, a so-called buffer layer for eliminating a lattice constant difference between the substrate and the group III nitride semiconductor is generally formed between the substrate and the group III nitride semiconductor. Yes.

For example, Patent Document 1 describes a method of growing a group III nitride semiconductor made of Al _x Ga _1-x N after forming a buffer layer of AlN on a sapphire substrate by MOVPE.

However, even in the method described in Patent Document 1, it is difficult to obtain an AlN buffer layer having a flat surface with good reproducibility. This is presumably because when an AlN buffer layer is formed by the MOVPE method, trimethylaluminum (TMA) gas and ammonia (NH ₃ ) gas used as source gases are easily reacted in the gas phase.

Therefore, in the method described in Patent Document 1, a high-quality group III nitride semiconductor composed of Al _x Ga _1-x N having a flat surface and a low defect density is reproducibly formed on an AlN buffer layer. It was difficult to grow well.

Further, for example, Patent Document 2 discloses a method of forming an Al _x Ga _1-x N (0 <x ≦ 1) buffer layer on a sapphire substrate by a high-frequency sputtering method in which a DC bias is applied.

However, the Group III nitride semiconductor formed on the Al _x Ga _1-x N (0 <x ≦ 1) buffer layer by the method described in Patent Document 2 is disclosed in paragraph [0004] of Patent Document 3 and Patent As described in paragraph [0004] of Document 4, it did not have excellent crystallinity.

  Therefore, Patent Document 3 proposes a method for heat-treating a buffer layer made of a group III nitride semiconductor formed by DC magnetron sputtering in an atmosphere of a mixed gas of hydrogen gas and ammonia gas. Document 4 proposes a method of forming a buffer layer made of a group III nitride semiconductor having a thickness of 50 Å or more and 3000 Å or less on a sapphire substrate heated to 400 ° C. or more by DC magnetron sputtering. .

  Patent Document 5 proposes a method of forming a buffer layer made of AlN columnar crystals on a sapphire substrate heated to 750 ° C. by high-frequency sputtering.

Japanese Patent No. 3026087 Japanese Patent Publication No. 5-86646 Japanese Patent No. 3440873 Japanese Patent No. 3700492 JP 2008-34444 A

  However, it has excellent crystallinity even when a buffer layer made of a group III nitride semiconductor is formed by the method described in Patent Documents 3 to 5 and a group III nitride semiconductor layer is formed on the buffer layer. The group III nitride semiconductor layer could not be formed with good reproducibility, and as a result, a nitride semiconductor device having good characteristics could not be produced with good reproducibility.

  In view of the above circumstances, an object of the present invention is to provide an aluminum-containing nitride intermediate layer manufacturing method capable of forming a nitride layer having excellent crystallinity above it with good reproducibility, and manufacturing the nitride layer It is an object to provide a method and a method for manufacturing a nitride semiconductor device using the nitride layer.

  According to the first aspect of the present invention, a voltage is applied between the substrate and the target by a DC-continuous method in which the substrate and the target containing aluminum are arranged at a distance of 100 mm to 250 mm. And a step of forming an aluminum-containing nitride intermediate layer on the surface of the substrate by a DC magnetron sputtering method performed in this manner.

  Here, in the method for producing an aluminum-containing nitride intermediate layer according to the first aspect of the present invention, the substrate and the target are disposed between the step of arranging the substrate and the target and the step of forming the aluminum-containing nitride intermediate layer. It is preferable to further include a step of introducing nitrogen gas between the target and the target.

  Moreover, in the manufacturing method of the aluminum containing nitride intermediate | middle layer of the 1st aspect of this invention, in the process of arrange | positioning a board | substrate and a target, it is preferable to incline a target with respect to a board | substrate and to arrange | position a board | substrate and a target. .

  According to the second aspect of the present invention, the step of arranging the substrate and the target containing aluminum at an interval, the step of introducing nitrogen gas between the substrate and the target, and the space between the substrate and the target And a step of forming an aluminum-containing nitride intermediate layer on the surface of the substrate by a DC magnetron sputtering method performed by applying a voltage by a DC-continuous method. be able to.

  Here, in the method for manufacturing the aluminum-containing nitride intermediate layer according to the second aspect of the present invention, in the step of arranging the substrate and the target, the substrate and the target may be arranged by tilting the target with respect to the substrate. preferable.

  Further, according to the third aspect of the present invention, the step of placing the substrate and the target containing aluminum at an interval with respect to the substrate and the DC-continuous method between the substrate and the target. And a step of forming an aluminum-containing nitride intermediate layer on the surface of the substrate by a DC magnetron sputtering method performed by applying a voltage.

  According to the fourth aspect of the present invention, a voltage is applied between the substrate and the target by a DC-continuous method in which the substrate and the target containing aluminum are arranged at a distance of 100 mm or more and 250 mm or less. A step of forming an aluminum-containing nitride intermediate layer on the surface of the substrate by a DC magnetron sputtering method and a step of forming a nitride layer on the aluminum-containing nitride intermediate layer. A method can be provided.

  Here, in the method for manufacturing the nitride layer according to the fourth aspect of the present invention, between the step of arranging the substrate and the target and the step of forming the aluminum-containing nitride intermediate layer, the gap between the substrate and the target. It is preferable that the method further includes a step of introducing nitrogen gas.

  In the method for manufacturing a nitride layer according to the fourth aspect of the present invention, in the step of arranging the substrate and the target, it is preferable that the substrate and the target are arranged by tilting the target with respect to the substrate.

  According to the fifth aspect of the present invention, the step of arranging the substrate and the target containing aluminum at an interval, the step of introducing nitrogen gas between the substrate and the target, and the space between the substrate and the target A step of forming an aluminum-containing nitride intermediate layer on the surface of the substrate by a DC magnetron sputtering method applied with a voltage by a DC-continuous method, and a step of forming a nitride layer on the aluminum-containing nitride intermediate layer A method for manufacturing a nitride layer can be provided.

  Here, in the method for manufacturing a nitride layer according to the fifth aspect of the present invention, in the step of arranging the substrate and the target, it is preferable that the substrate and the target are arranged by tilting the target with respect to the substrate.

  According to the sixth aspect of the present invention, the step of placing the substrate and the aluminum-containing target at an interval with respect to the substrate and the DC-continuous method between the substrate and the target. A step of forming an aluminum-containing nitride intermediate layer on the surface of the substrate by a DC magnetron sputtering method that is performed by applying a voltage, and a step of forming a nitride layer on the aluminum-containing nitride intermediate layer. A method for manufacturing a nitride layer can be provided.

  According to the seventh aspect of the present invention, the voltage is applied between the substrate and the target by a DC-continuous method in which the substrate and the target containing aluminum are arranged at a distance of 100 mm to 250 mm. A step of forming an aluminum-containing nitride intermediate layer on the surface of the substrate by a DC magnetron sputtering method performed by applying a voltage; and a step of forming a nitride semiconductor layer on the aluminum-containing nitride intermediate layer. A method for manufacturing a semiconductor device can be provided.

  Here, in the method for manufacturing a nitride semiconductor device according to the seventh aspect of the present invention, the substrate and the target are placed between the step of arranging the substrate and the target and the step of forming the aluminum-containing nitride intermediate layer. It is preferable to further include a step of introducing nitrogen gas between them.

  In the method for manufacturing a nitride semiconductor device according to the seventh aspect of the present invention, in the step of arranging the substrate and the target, it is preferable that the substrate and the target are arranged with the target inclined with respect to the substrate.

  Moreover, according to the 8th aspect of this invention, the process of arrange | positioning the board | substrate and the target containing aluminum at intervals, the process of introducing nitrogen gas between a board | substrate and a target, a board | substrate, a target, A step of forming an aluminum-containing nitride intermediate layer on the surface of the substrate by a DC magnetron sputtering method performed by applying a voltage by a DC-continuous method, and a nitride semiconductor layer on the aluminum-containing nitride intermediate layer A method of manufacturing a nitride semiconductor device, including a step of forming the nitride semiconductor device.

  Here, in the method for manufacturing a nitride semiconductor device according to the eighth aspect of the present invention, in the step of arranging the substrate and the target, it is preferable that the substrate and the target are arranged by tilting the target with respect to the substrate.

  According to the ninth aspect of the present invention, the step of placing the substrate and the aluminum-containing target at an interval with respect to the substrate and the DC-continuous method between the substrate and the target. A step of forming an aluminum-containing nitride intermediate layer on the surface of the substrate by a DC magnetron sputtering method that is performed by applying a voltage, and a step of forming a nitride semiconductor layer on the aluminum-containing nitride intermediate layer. A method for manufacturing a nitride semiconductor device can be provided.

  According to the present invention, a method for producing an aluminum-containing nitride intermediate layer, a method for producing the nitride layer, and a nitride layer capable of forming a nitride layer having excellent crystallinity thereon with good reproducibility are provided. A method for manufacturing the nitride semiconductor device used can be provided.

1 is a schematic cross-sectional view of a nitride semiconductor light-emitting diode element according to Embodiment 1, which is an example of the nitride semiconductor element of the present invention. 5 is a schematic cross-sectional view illustrating a part of the manufacturing process in the example of the method for manufacturing the nitride semiconductor light-emitting diode element according to the first embodiment. FIG. It is a typical block diagram of an example of the DC magnetron sputtering apparatus used for laminating | stacking an aluminum containing nitride intermediate | middle layer on the surface of a board | substrate. It is a typical block diagram of another example of the DC magnetron sputtering apparatus used for laminating | stacking an aluminum containing nitride intermediate | middle layer on the surface of a board | substrate. It is a typical block diagram of another example of the DC magnetron sputtering apparatus used for laminating | stacking an aluminum containing nitride intermediate | middle layer on the surface of a board | substrate. 5 is a schematic cross-sectional view illustrating a part of the manufacturing process in the example of the method for manufacturing the nitride semiconductor light-emitting diode element according to the first embodiment. FIG. 5 is a schematic cross-sectional view illustrating a part of the manufacturing process in the example of the method for manufacturing the nitride semiconductor light-emitting diode element according to the first embodiment. FIG. 5 is a schematic cross-sectional view illustrating a part of the manufacturing process in the example of the method for manufacturing the nitride semiconductor light-emitting diode element according to the first embodiment. FIG. 2 is a schematic cross-sectional view of an example of a light emitting device using the nitride semiconductor light emitting diode element of Embodiment 1. FIG. FIG. 10 is a schematic cross-sectional view of a nitride semiconductor laser element according to Embodiment 2, which is another example of the nitride semiconductor element of the present invention. 12 is a schematic cross-sectional view illustrating a part of the manufacturing process in an example of the method for manufacturing the nitride semiconductor laser element of the second embodiment. FIG. 12 is a schematic cross-sectional view illustrating a part of the manufacturing process in an example of the method for manufacturing the nitride semiconductor laser element of the second embodiment. FIG. It is typical sectional drawing of the nitride semiconductor transistor element of Embodiment 3 which is another example of the nitride semiconductor element of this invention. 12 is a schematic cross-sectional view illustrating a part of the manufacturing process in an example of the method for manufacturing the nitride semiconductor transistor element of the third embodiment. FIG. 16 is a schematic cross-sectional view illustrating a part of the manufacturing process of the method for manufacturing the nitride semiconductor light-emitting diode element of Experimental Examples 1 to 15. FIG. It is a typical block diagram of the DC magnetron sputtering apparatus used for formation of the AlN buffer layer of Experimental Examples 1-8 and 13-15. 16 is a schematic cross-sectional view illustrating a part of the manufacturing process of the method for manufacturing the nitride semiconductor light-emitting diode element of Experimental Examples 1 to 15. FIG. 16 is a schematic cross-sectional view illustrating a part of the manufacturing process of the method for manufacturing the nitride semiconductor light-emitting diode element of Experimental Examples 1 to 15. FIG. 16 is a schematic cross-sectional view illustrating a part of the manufacturing process of the method for manufacturing the nitride semiconductor light-emitting diode element of Experimental Examples 1 to 15. FIG. 16 is a schematic cross-sectional view illustrating a part of the manufacturing process of the method for manufacturing the nitride semiconductor light-emitting diode element of Experimental Examples 1 to 15. FIG. 16 is a schematic cross-sectional view illustrating a part of the manufacturing process of the method for manufacturing the nitride semiconductor light-emitting diode element of Experimental Examples 1 to 15. FIG. It is a typical block diagram of the DC magnetron sputtering apparatus used for formation of the AlN buffer layer of Experimental Examples 9-12. The relationship between the half-value width (arcsec) of the X-ray rocking curve on the (004) plane of the GaN underlayer in Experimental Examples 1 to 8 and the shortest distance d (mm) between the center of the Al target surface and the c plane of the sapphire substrate. FIG.

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

<Embodiment 1>
FIG. 1 is a schematic cross-sectional view of a nitride semiconductor light-emitting diode element according to Embodiment 1 which is an example of the nitride semiconductor element of the present invention.

  Here, the nitride semiconductor light-emitting diode device 100 of the first embodiment is formed on the surface of the substrate 1, the aluminum-containing nitride intermediate layer 2 placed in contact with the surface of the substrate 1, and the surface of the aluminum-containing nitride intermediate layer 2. Nitride semiconductor underlayer 3 placed in contact, n-type nitride semiconductor contact layer 4 placed in contact with the surface of nitride semiconductor underlayer 3, and in contact with the surface of n-type nitride semiconductor contact layer 4 The n-type nitride semiconductor clad layer 5 installed, the nitride semiconductor active layer 6 placed in contact with the surface of the n-type nitride semiconductor clad layer 5, and the surface of the nitride semiconductor active layer 6 The p-type nitride semiconductor cladding layer 7, the p-type nitride semiconductor contact layer 8 placed in contact with the surface of the p-type nitride semiconductor cladding layer 7, and the surface of the p-type nitride semiconductor contact layer 8 Installed And a translucent electrode layer 9, and a. The n-side electrode 11 is disposed so as to be in contact with the exposed surface of the n-type nitride semiconductor contact layer 4, and the p-side electrode 10 is disposed so as to be in contact with the surface of the translucent electrode layer 9. .

  Hereinafter, an example of a method for manufacturing the nitride semiconductor light-emitting diode element 100 of the first embodiment will be described.

  First, as shown in the schematic cross-sectional view of FIG. 2, the aluminum-containing nitride intermediate layer 2 is laminated on the surface of the substrate 1. Here, the aluminum-containing nitride intermediate layer 2 is formed by a DC magnetron sputtering method performed by applying a voltage between the substrate 1 and the target by a DC-continuous method.

  FIG. 3 shows a schematic configuration of an example of a DC magnetron sputtering apparatus used for laminating the aluminum-containing nitride intermediate layer 2 on the surface of the substrate 1.

  Here, the DC magnetron sputtering apparatus includes a chamber 21, a heater 23 installed below the inside of the chamber 21, a cathode 28 installed so as to face the heater 23, and a gas inside the chamber 21. And an exhaust port 25 for discharging to the outside.

  The heater 23 is supported by a heater support member 24. Further, the cathode 28 has an Al target 26 made of aluminum and a magnet 27 supported by a magnet support material 29. The chamber 21 is connected to an Ar gas supply pipe 30 for supplying argon gas into the chamber 21 and an N2 gas supply pipe 31 for supplying nitrogen gas into the chamber 21.

  In laminating the aluminum-containing nitride intermediate layer 2 on the surface of the substrate 1, first, the substrate 1 is placed on the heater 23 in the DC magnetron sputtering apparatus having the above-described configuration. The substrate 1 is arranged with a predetermined distance d so that the growth surface of the substrate 1 (surface on which the aluminum-containing nitride intermediate layer 2 is grown) faces the surface of the Al target 26.

As the substrate 1, for example, a sapphire (Al ₂ O ₃ ) single crystal, spinel (MgAl ₂ O ₄ ) single crystal, ZnO single crystal, LiAlO ₂ having an exposed surface such as a-plane, c-plane, m-plane or r-plane. A substrate made of a single crystal, LiGaO ₂ single crystal, MgO single crystal, Si single crystal, SiC single crystal, GaAs single crystal, AlN single crystal, GaN single crystal, or a boride single crystal such as ZrB ₂ can be used. In addition, the plane orientation of the growth surface of the substrate 1 is not particularly limited, and a just substrate, a substrate with an off angle, or the like can be used as appropriate, and among them, a sapphire substrate made of a sapphire single crystal is used as the substrate 1. When the aluminum-containing nitride intermediate layer 2 to be described later is formed on the c-plane of the sapphire substrate, the aluminum-containing nitride intermediate layer 2 having a good crystallinity made of an aggregate of columnar crystals with uniform crystal grains is used. It is preferable at the point that the tendency which can be laminated | stacked becomes large.

  The distance d means the shortest distance between the center of the surface of the Al target 26 and the growth surface of the substrate 1, and the distance d is preferably 100 mm or more and 250 mm or less, It is more preferably 120 mm or more and 210 mm or less, and further preferably 150 mm or more and 180 mm or less. This is because, when the aluminum-containing nitride intermediate layer 2 is deposited by the DC magnetron sputtering method, high energy reactive species are supplied to the substrate 1, but when the distance d is 100 mm or more, The damage caused by the reactive species on the growth surface of the substrate 1 can be reduced. When the distance d is 250 mm or less, plasma discharge is likely to occur and the formation rate of the aluminum-containing nitride intermediate layer 2 is increased. Therefore, a favorable crystalline aluminum-containing nitride intermediate layer 2 made of an aggregate of columnar crystals with aligned crystal grains extending in the normal direction (vertical direction) of the growth surface of the substrate 1 can be stacked. It is in. Therefore, by growing a nitride layer on the surface of such a good crystalline aluminum-containing nitride intermediate layer 2, a nitride layer having a low dislocation density and excellent crystallinity (in this embodiment, a nitride layer). The semiconductor underlayer 3) can be obtained with good reproducibility, and thus a nitride semiconductor device having good characteristics can be produced with good reproducibility.

  Further, when the distance d is set to 120 nm or more and 210 nm or less, particularly 150 nm or more and 180 nm or less, the aluminum-containing nitride intermediate layer 2 having better crystallinity can be laminated. On the surface of the aluminum-containing nitride intermediate layer 2, a nitride layer having a lower dislocation density and excellent crystallinity is more likely to be grown with good reproducibility, and thus a nitride semiconductor device having even better characteristics is obtained. The tendency to be able to produce with good reproducibility increases.

Next, argon gas and nitrogen gas are supplied between the substrate 1 and the Al target 26 by supplying argon gas from the Ar gas supply pipe 30 into the chamber 21 and supplying nitrogen gas from the N ₂ gas supply pipe 31. Is introduced. Then, a plasma of argon gas and nitrogen gas between the substrate 1 and the Al target 26 is generated by applying a voltage between the substrate 1 and the Al target 26 by a DC-continuous method. As a result, the Al target 26 is sputtered, whereby the aluminum-containing nitride intermediate layer 2 made of a compound of aluminum and nitrogen is laminated on the surface of the substrate 1. The DC-continuous method is a method in which a DC voltage having a predetermined magnitude (a voltage whose direction does not change with time) is continuously applied between the substrate 1 and the Al target 26 during the sputtering of the Al target 26. is there.

  Here, the volume ratio (nitrogen ratio:%) occupied by nitrogen gas in the gas supplied into the chamber 21 is preferably 50% or more, more preferably 75% or more, and 100%. Most preferably, only nitrogen gas is supplied. When the nitrogen ratio is 50% or more, particularly 75% or more, the amount of impurities taken into the aluminum-containing nitride intermediate layer 2 can be suppressed. The crystallinity of can be improved. Further, when the nitrogen ratio is 100%, only nitrogen gas is supplied into the chamber 21, so that the crystallinity of the aluminum-containing nitride intermediate layer 2 can be further improved. . Thus, when a nitride layer is grown on the surface of the aluminum-containing nitride intermediate layer 2 having excellent crystallinity, a nitride layer having a low dislocation density and excellent crystallinity tends to be obtained with good reproducibility. As a result, the tendency that a nitride semiconductor device having good characteristics can be manufactured with high reproducibility is increased.

  In the above description, the case where argon gas and nitrogen gas are supplied into the chamber 21 has been described. However, the present invention is not limited to this. For example, at least part of the nitrogen gas may be replaced with ammonia gas. Of course, at least a part of the argon gas may be replaced with hydrogen gas.

  FIG. 4 shows a schematic configuration of another example of a DC magnetron sputtering apparatus used for laminating the aluminum-containing nitride intermediate layer 2 on the surface of the substrate 1. The DC magnetron sputtering apparatus having the configuration shown in FIG. 4 is characterized in that the Al target 26 is inclined with respect to the growth surface of the substrate 1 with a space between the substrate 1 and the Al target 26.

  Here, the Al target 26 is disposed so as to be inclined by an angle θ with respect to the normal direction of the growth surface of the substrate 1. Here, from the viewpoint of laminating the aluminum-containing nitride intermediate layer 2 having excellent crystallinity, the angle θ is preferably 10 ° or more and 45 ° or less, and more preferably 20 ° or more and 45 ° or less.

  As described above, in a state where the Al target 26 is inclined with respect to the growth surface of the substrate 1 with a space between the substrate 1 and the Al target 26, the DC-continuous is provided between the substrate 1 and the Al target 26. When the aluminum-containing nitride intermediate layer 2 is laminated by the DC magnetron sputtering method by applying a voltage according to the method, the substrate 1 due to the high-energy reactive species supplied to the substrate 1 when the aluminum-containing nitride intermediate layer 2 is laminated. Therefore, the aluminum-containing nitride intermediate layer 2 excellent in crystallinity tends to be laminated.

  Further, by disposing the Al target 26 so as to be inclined with respect to the growth surface of the substrate 1, the uniformity of the thickness and the crystallinity of the aluminum-containing nitride intermediate layer 2 in the growth surface of the substrate 1 are improved. Therefore, the uniformity of the characteristics of the nitride semiconductor device in the growth surface of the substrate 1 is improved, and the yield of the nitride semiconductor device tends to be improved.

  In particular, as the diameter of the growth surface of the substrate 1 increases to 100 mm (4 inches), 125 mm (5 inches), and 150 mm (6 inches), the effect of improving the above-mentioned uniformity tends to appear more remarkably.

  Also in the DC magnetron sputtering apparatus having the configuration shown in FIG. 4, the shortest distance d between the center of the surface of the Al target 26 and the growth surface of the substrate 1 is preferably 100 mm or more and 250 mm or less, and 120 mm. More preferably, it is set to 210 mm or less, and further preferably 150 mm to 180 mm. Also in the DC magnetron sputtering apparatus having the configuration shown in FIG. 4, by setting the shortest distance d as described above, the aluminum-containing nitride intermediate layer 2 having further excellent crystallinity is laminated for the above-described reason. There is a tendency to be able to.

Also in the DC magnetron sputtering apparatus having the configuration shown in FIG. 4, the volume ratio (nitrogen ratio:%) occupied by nitrogen gas in the gas supplied into the chamber 21 is preferably 50% or more, and 75% or more. More preferably, it is 100% (only nitrogen gas is supplied). Also in the DC magnetron sputtering apparatus having the configuration shown in FIG. 4, by setting the nitrogen ratio of the gas supplied into the chamber 21 as described above, the aluminum-containing nitride having further excellent crystallinity for the above-described reason. The intermediate layer 2 tends to be laminated.

  FIG. 5 shows a schematic configuration of still another example of a DC magnetron sputtering apparatus used for laminating the aluminum-containing nitride intermediate layer 2 on the surface of the substrate 1. The DC magnetron sputtering apparatus having the configuration shown in FIG. 5 includes a first cathode 28 a having a first Al target 26 a disposed so as to be inclined with respect to the growth surface of the substrate 1 at a distance from the substrate 1, and the substrate 1. And a second cathode 28b having a second Al target 26b disposed so as to be inclined with respect to the growth surface of the substrate 1 with a gap therebetween.

  Here, the first cathode 28a has a first Al target 26a and a first magnet 27a supported by a first magnet support member 29a. The second cathode 28b has a second Al target 26b and a second magnet 27b supported by a second magnet support member 29b.

  Further, the first Al target 26 a is disposed so as to be inclined by an angle θ 1 with respect to the normal direction of the growth surface of the substrate 1. Here, from the viewpoint of laminating the aluminum-containing nitride intermediate layer 2 having excellent crystallinity, the angle θ1 is preferably 10 ° or more and 45 ° or less, and more preferably 20 ° or more and 45 ° or less.

  In addition, the second Al target 26 b is disposed to be inclined by an angle θ 2 with respect to the normal direction of the growth surface of the substrate 1. Here, from the viewpoint of laminating the aluminum-containing nitride intermediate layer 2 having excellent crystallinity, the angle θ2 is preferably 10 ° to 45 °, and more preferably 20 ° to 45 °.

  From the viewpoint of laminating the aluminum-containing nitride intermediate layer 2 having excellent crystallinity, either one of the angles θ1 or θ2 is preferably set in the above range, and both θ1 and θ2 are the above. More preferably, it is set in the range.

  In addition, in FIG. 5, the DC magnetron sputtering apparatus in which two Al targets arranged to be inclined with respect to the growth surface of the substrate have been described, but from the viewpoint of improving the film formation rate of the aluminum-containing nitride intermediate layer 2. Therefore, the number of Al targets arranged to be inclined with respect to the growth surface of the substrate can be increased to three, four, five, etc., for example.

  In the DC magnetron sputtering apparatus having the configuration shown in FIG. 5, the shortest distance d1 between the center of the surface of the first Al target 26a and the growth surface of the substrate 1 is preferably 100 mm or more and 250 mm or less, and 120 mm. More preferably, it is set to 210 mm or less, and further preferably 150 mm to 180 mm. In the DC magnetron sputtering apparatus having the configuration shown in FIG. 5, by setting the shortest distance d1 as described above, the aluminum-containing nitride intermediate layer 2 having further excellent crystallinity can be stacked for the reasons described above. It tends to be possible.

  In the DC magnetron sputtering apparatus having the configuration shown in FIG. 5, the shortest distance d2 between the center of the surface of the second Al target 26b and the growth surface of the substrate 1 is preferably 100 mm or more and 250 mm or less. 120 mm to 210 mm, more preferably 150 mm to 180 mm. In the DC magnetron sputtering apparatus having the configuration shown in FIG. 6, by setting the shortest distance d2 as described above, the aluminum-containing nitride intermediate layer 2 having further excellent crystallinity can be laminated for the reasons described above. It tends to be possible.

  From the viewpoint of laminating the aluminum-containing nitride intermediate layer 2 having excellent crystallinity, it is preferable that either the shortest distance d1 or d2 is set in the above range, and both d1 and d2 are More preferably, it is set within the above range.

  Also in the DC magnetron sputtering apparatus having the configuration shown in FIG. 5, the volume ratio (nitrogen ratio:%) occupied by nitrogen gas in the gas supplied into the chamber 21 is preferably 50% or more, and 75% or more. More preferably, it is 100% (only nitrogen gas is supplied). Also in the DC magnetron sputtering apparatus having the configuration shown in FIG. 5, by setting the nitrogen ratio of the gas supplied into the chamber 21 as described above, the aluminum-containing nitride having further excellent crystallinity for the above-described reason. The intermediate layer 2 tends to be laminated.

As described above, in the present embodiment, at the time of stacking the aluminum-containing nitride intermediate layer by the DC magnetron sputtering method in which a voltage is applied between the substrate and the target by the DC-continuous method, the following (a) to ( By adopting at least one of the conditions of c), a good crystalline aluminum-containing nitride intermediate layer composed of an aggregate of columnar crystals with aligned crystal grains extending in the normal direction of the growth surface of the substrate is formed on the substrate. Laminated on the growth surface. Then, by growing a nitride layer on the surface of such a good crystalline aluminum-containing nitride intermediate layer, a nitride layer having a low dislocation density and excellent crystallinity can be obtained with good reproducibility, As a result, a nitride semiconductor device having good characteristics can be manufactured with good reproducibility.
(A) The shortest distance between the center of the surface of the target and the growth surface of the substrate is 100 mm or more and 250 mm or less, more preferably 120 mm or more and 210 mm or less, and further preferably 150 mm or more and 180 mm or less.
(B) The volume ratio (nitrogen ratio:%) occupied by nitrogen gas in the gas supplied to the DC magnetron sputtering apparatus is 50% or more, more preferably 75% or more, and even more preferably 100%. (Only nitrogen gas is supplied).
(C) The target is inclined with respect to the growth surface of the substrate.

  In order to laminate a good crystalline aluminum-containing nitride intermediate layer on the growth surface of the substrate, any one of the above conditions (a) to (c) may be employed. In order to obtain a good crystalline aluminum-containing nitride intermediate layer, it is preferable to employ any two of the above conditions (a) to (c), and the above conditions (a) to (c) Most preferably, all conditions are employed.

The aluminum-containing nitride intermediate layer 2 preferably covers the growth surface of the substrate 1 without a gap. When the growth surface of the substrate 1 is exposed from the aluminum-containing nitride intermediate layer 2, hillocks and pits may be generated in the nitride layer formed on the aluminum-containing nitride intermediate layer 2. There is.

As the aluminum-containing nitride intermediate layer 2, for example, a nitride semiconductor layer (0 ≦ x0 ≦ 1, 0 ≦ y0 ≦ 1, x0 + y0 ≠ 0) made of a nitride semiconductor represented by the formula of Al _x0 Ga _y0 N is used. From the viewpoint of obtaining a good crystalline aluminum-containing nitride intermediate layer 2 composed of an aggregate of columnar crystals with aligned crystal grains extending in the normal direction of the growth surface of the substrate 1. It is preferable to stack a nitride semiconductor layer made of a nitride semiconductor (aluminum nitride) represented by the formula of AlN.

  Further, the thickness of the aluminum-containing nitride intermediate layer 2 laminated on the growth surface of the substrate 1 is preferably 5 nm or more and 100 nm or less. When the thickness of the aluminum-containing nitride intermediate layer 2 is less than 5 nm, the aluminum-containing nitride intermediate layer 2 may not sufficiently function as a buffer layer. Further, when the thickness of the aluminum-containing nitride intermediate layer 2 exceeds 100 nm, the function as the buffer layer is not improved, and only the formation time of the aluminum-containing nitride intermediate layer 2 may be increased. Further, from the viewpoint of uniformly exhibiting the function of the aluminum-containing nitride intermediate layer 2 as a buffer layer in the plane, the thickness of the aluminum-containing nitride intermediate layer 2 is more preferably 10 nm or more and 50 nm or less.

  Moreover, it is preferable that the temperature of the board | substrate 1 at the time of lamination | stacking of the aluminum containing nitride intermediate | middle layer 2 is 300 to 1000 degreeC. When the temperature of the substrate 1 when the aluminum-containing nitride intermediate layer 2 is laminated is less than 300 ° C., the aluminum-containing nitride intermediate layer 2 cannot cover the entire growth surface of the substrate 1, and A part of the growth surface may be exposed from the aluminum-containing nitride intermediate layer 2. Further, when the temperature of the substrate 1 during the lamination of the aluminum-containing nitride intermediate layer 2 exceeds 1000 ° C., the migration of the raw material on the growth surface of the substrate 1 becomes too active, rather than an aggregate of columnar crystals. Rather, the aluminum-containing nitride intermediate layer 2 close to a single crystal film is formed, and the function of the aluminum-containing nitride intermediate layer 2 as a buffer layer may be reduced.

  Further, the pressure inside the chamber 21 when the aluminum-containing nitride intermediate layer 2 is laminated is preferably 0.2 Pa or more. When the pressure inside the chamber 21 when the aluminum-containing nitride intermediate layer 2 is stacked is less than 0.2 Pa, the amount of nitrogen inside the chamber 21 decreases, and the aluminum sputtered from the Al target 26 is nitrided. There is a possibility of adhering to the growth surface of the substrate 1 in a state where it does not become an object. Further, the upper limit of the pressure inside the chamber 21 when the aluminum-containing nitride intermediate layer 2 is laminated is not particularly limited as long as it is a pressure that can generate plasma inside the chamber 21.

Further, since it is desirable that no impurities exist inside the chamber 21 when the aluminum-containing nitride intermediate layer 2 is stacked, from the viewpoint of obtaining the aluminum-containing nitride intermediate layer 2 having good crystallinity, the chamber immediately before sputtering is used. The internal pressure of 21 is preferably 1 × 10 ⁻³ Pa or less.

  Further, the formation rate of the aluminum-containing nitride intermediate layer 2 is preferably 0.01 nm / second or more and 1 nm / second or less. When the formation rate of the aluminum-containing nitride intermediate layer 2 is less than 0.01 nm / second, the aluminum-containing nitride intermediate layer 2 spreads uniformly on the growth surface of the substrate 1 and grows in an island shape without growing. Thus, the aluminum-containing nitride intermediate layer 2 cannot uniformly cover the growth surface of the substrate 1, and the growth surface of the substrate 1 may be exposed from the aluminum-containing nitride intermediate layer 2. Further, when the formation rate of the aluminum-containing nitride intermediate layer 2 exceeds 1 nm / second, the aluminum-containing nitride intermediate layer 2 becomes amorphous, and the dislocation density is small on the aluminum-containing nitride intermediate layer 2. There is a possibility that a nitride layer having excellent crystallinity cannot be grown.

  Further, the growth surface of the substrate 1 before the lamination of the aluminum-containing nitride intermediate layer 2 may be pretreated. Here, as an example of the pretreatment of the growth surface of the substrate 1, there is a treatment in which the growth surface of the substrate 1 is hydrogen-terminated by performing RCA cleaning similar to that often performed on a silicon substrate. Thereby, it exists in the tendency which can laminate | stack the favorable crystalline aluminum containing nitride intermediate | middle layer 2 on the growth surface of the board | substrate 1 with sufficient reproducibility.

  Further, as another example of the pretreatment of the growth surface of the substrate 1, there is a treatment in which the growth surface of the substrate 1 is exposed to nitrogen gas plasma. Thereby, foreign substances such as organic substances and oxides attached to the growth surface of the substrate 1 tend to be removed, and the state of the growth surface of the substrate 1 tends to be adjusted. In particular, when the substrate 1 is a sapphire substrate, the growth surface of the substrate 1 is nitrided by exposing the growth surface of the substrate 1 to plasma of nitrogen gas, and the aluminum-containing layer stacked on the growth surface of the substrate 1 is contained. The nitride intermediate layer 2 tends to be formed uniformly in the plane.

Next, as shown in the schematic cross-sectional view of FIG. 6, the nitride semiconductor underlayer 3 is laminated on the surface of the aluminum-containing nitride intermediate layer 2 by MOCVD (Metal Organic Chemical Vapor Deposition).

Here, as the nitride semiconductor underlayer 3, for example, a nitride semiconductor layer made of a group III nitride semiconductor represented by the formula of Al _x1 Ga _y1 In _z1 N (0 ≦ x1 ≦ 1, 0 ≦ y1 ≦ 1, 0 ≦ z1 ≦ 1, x1 + y1 + z1 ≠ 0), but in order not to inherit crystal defects such as dislocations in the aluminum-containing nitride intermediate layer 2 composed of aggregates of columnar crystals, a group III element It is preferable that Ga is included. In order to prevent dislocations in the aluminum-containing nitride intermediate layer 2 from being taken over, it is necessary to loop dislocations in the vicinity of the interface with the aluminum-containing nitride intermediate layer 2, but the nitride semiconductor underlayer 3 contains Ga. In the case of a group III nitride semiconductor, a dislocation loop is likely to occur. Therefore, by using the nitride semiconductor underlayer 3 made of a group III nitride semiconductor containing Ga, the dislocations are looped and confined near the interface with the aluminum-containing nitride intermediate layer 2, and the aluminum-containing nitride intermediate layer 2 is confined. Therefore, it is possible to prevent dislocations from being transferred to the nitride semiconductor underlayer 3. In particular, when the nitride semiconductor underlayer 3 is made of a group III nitride semiconductor represented by the formula of Al _x1 Ga _y1 N (0 <x1 <1, 0 <y1 <1), particularly when made of GaN, aluminum Since dislocations can be looped and confined in the vicinity of the interface with the nitride-containing intermediate layer 2, the nitride semiconductor underlayer 3 having a low dislocation density and good crystallinity tends to be obtained.

  Further, the surface of the aluminum-containing nitride intermediate layer 2 immediately before the nitride semiconductor underlayer 3 is laminated may be heat-treated. By this heat treatment, the surface of the aluminum-containing nitride intermediate layer 2 tends to be cleaned and the crystallinity can be improved. This heat treatment can be performed in an MOCVD apparatus using, for example, the MOCVD method, and for example, hydrogen gas or nitrogen gas can be used as the atmospheric gas during the heat treatment. In order to prevent decomposition of the aluminum-containing nitride intermediate layer 2 during the heat treatment, ammonia gas may be mixed with the atmospheric gas during the heat treatment. The above heat treatment can be performed, for example, at a temperature of 900 ° C. or higher and 1250 ° C. or lower for a time period of 1 minute to 60 minutes, for example.

The nitride semiconductor underlayer 3 may be doped with an n-type dopant in the range of 1 × 10 ¹⁷ cm ⁻³ or more and 1 × 10 ¹⁹ cm ⁻³ or less, but from the viewpoint of maintaining good crystallinity. Therefore, the nitride semiconductor underlayer 3 is preferably undoped. As the n-type dopant, for example, silicon, germanium, tin, and the like can be used, and it is preferable to use silicon and / or germanium.

  The temperature of the substrate 1 when the nitride semiconductor underlayer 3 is stacked is preferably 800 ° C. or higher and 1250 ° C. or lower, and more preferably 1000 ° C. or higher and 1250 ° C. or lower. When the temperature of the substrate 1 when the nitride semiconductor underlayer 3 is stacked is 800 ° C. or higher and 1250 ° C. or lower, particularly when the temperature is 1000 ° C. or higher and 1250 ° C. or lower, the nitride semiconductor underlayer 3 having excellent crystallinity is formed. It tends to be able to grow.

  Next, as shown in the schematic cross-sectional view of FIG. 7, an n-type nitride semiconductor contact layer 4, an n-type nitride semiconductor cladding layer 5, a nitride is formed on the surface of the nitride semiconductor underlayer 3 by MOCVD. The semiconductor active layer 6, the p-type nitride semiconductor clad layer 7, and the p-type nitride semiconductor contact layer 8 are stacked in this order to form a stacked body.

Here, as the n-type nitride semiconductor contact layer 4, for example, a nitride semiconductor layer made of a group III nitride semiconductor represented by the formula of Al _x2 Ga _y2 In _z2 N (0 ≦ x2 ≦ 1, 0 ≦ y2 ≦) 1, 0 ≦ z2 ≦ 1, x2 + y2 + z2 ≠ 0) and a layer doped with an n-type dopant can be stacked.

Among these, the n-type nitride semiconductor contact layer 4 has an Al _x2 Ga _1-x2 N (0 ≦ x2 ≦ 1, preferably 0 ≦ x2 ≦ 0.5, more preferably 0 ≦ x2 ≦ 0.1) formula. A nitride semiconductor layer in which silicon is doped as a n-type dopant in a group III nitride semiconductor represented by

In addition, the doping concentration of the n-type dopant to the n-type nitride semiconductor contact layer 4 is such that the good ohmic contact with the n-side electrode 11 is maintained, the generation of cracks in the n-type nitride semiconductor contact layer 4 is suppressed, and the good concentration From the viewpoint of maintaining crystallinity, it is preferably within the range of 5 × 10 ¹⁷ cm ⁻³ or more and 5 × 10 ¹⁹ cm ⁻³ or less.

  The total thickness of the nitride semiconductor underlayer 3 and the n-type nitride semiconductor contact layer 4 is preferably 4 μm or more and 20 μm or less from the viewpoint of maintaining good crystallinity of these layers. It is more preferably 15 μm or less, and further preferably 6 μm or more and 15 μm or less. When the total thickness of the nitride semiconductor underlayer 3 and the n-type nitride semiconductor contact layer 4 is less than 4 μm, the crystallinity of these layers deteriorates or pits are formed on the surfaces of these layers. May occur. On the other hand, if the total thickness of the nitride semiconductor underlayer 3 and the n-type nitride semiconductor contact layer 4 exceeds 15 μm, the warpage of the substrate 1 becomes large, which may lead to a reduction in device yield. . Further, when the total thickness of the nitride semiconductor underlayer 3 and the n-type nitride semiconductor contact layer 4 is 4 μm or more and 15 μm or less, particularly when the thickness is 6 μm or more and 15 μm or less, the crystallinity of these layers is changed. In addition to being able to be good, the warpage of the substrate 1 is increased, and a decrease in the yield of the element can be effectively prevented. Of the total thickness of these layers, the upper limit of the thickness of n-type nitride semiconductor contact layer 4 is not particularly limited.

Further, as the n-type nitride semiconductor cladding layer 5, for example, a nitride semiconductor layer (0 ≦ x3 ≦ 1, 0 ≦ y3 ≦ 1) made of a group III nitride semiconductor represented by the formula of Al _x3 Ga _y3 In _z3 N , 0 ≦ z3 ≦ 1, x3 + y3 + z3 ≠ 0), a layer doped with an n-type dopant, or the like can be stacked. The n-type nitride semiconductor clad layer 5 may have a structure in which a plurality of nitride semiconductor layers made of a group III nitride semiconductor are heterojunction or a superlattice structure. The thickness of the n-type nitride semiconductor cladding layer 5 is not particularly limited, but is preferably 0.005 μm or more and 0.5 μm or less, more preferably 0.005 μm or more and 0.1 μm or less. The doping concentration of the n-type dopant into the n-type nitride semiconductor cladding layer 5 is 1 × 10 ¹⁷ cm ⁻³ or more and 1 × 10 ²⁰ cm ⁻³ or less from the viewpoint of maintaining good crystallinity and reducing the operating voltage of the device. Preferably, it is 1 × 10 ¹⁸ cm ⁻³ or more and 1 × 10 ¹⁹ cm ⁻³ or less.

When the nitride semiconductor active layer 6 has a single quantum well (SQW) structure, for example, the nitride semiconductor active layer 6 is, for example, a group III nitride represented by the formula Ga _{1 -z 4} In _{z 4} N A nitride semiconductor layer (0 <z4 <0.4) made of a physical semiconductor may be used as a quantum well layer. The thickness of the nitride semiconductor active layer 6 is not particularly limited, but is preferably 1 nm or more and 10 nm or less, and more preferably 1 nm or more and 6 nm or less from the viewpoint of improving the light emission output.

Single quantum well in which the nitride semiconductor active layer 6 is a nitride semiconductor layer (0 <z4 <0.4) made of a group III nitride semiconductor represented by, for example, the formula Ga _{1 -z4} In _z4 N In the case of the (SQW) structure, the In composition and thickness of the nitride semiconductor active layer 6 are controlled so as to obtain a desired emission wavelength. However, if the temperature of the substrate 1 at the time of forming the nitride semiconductor active layer 6 is low, the crystallinity may be deteriorated. On the other hand, if the temperature of the substrate 1 at the time of forming the nitride semiconductor active layer 6 is high, InN sublimation. Becomes prominent, the efficiency of incorporation of In into the solid phase is reduced, and the In composition may fluctuate. Therefore, a nitride semiconductor layer having a single quantum well (SQW) structure having a nitride semiconductor layer (0 <z4 <0.4) made of a group III nitride semiconductor represented by the formula Ga _{1 -z4} In _z4 N as a well layer. The temperature of the substrate 1 when forming the physical semiconductor active layer 6 is preferably 700 ° C. or higher and 900 ° C. or lower, and more preferably 750 ° C. or higher and 850 ° C. or lower.

As the nitride semiconductor active layer 6, for example, a nitride semiconductor layer (0 <z4 <0.4) made of a group III nitride semiconductor represented by the formula Ga _{1 -z4} In _z4 N is used as a quantum well layer. Nitride semiconductor layers (0 ≦ x5 ≦ 1, 0 ≦ y5 ≦ 1, 0 ≦ z5 ≦ 1, nitride semiconductor layers represented by the formula Al _x5 Ga _y5 In _z5 N having a larger band gap than this well layer One having a multiple quantum well (MQW) structure in which x5 + y5 + z5 ≠ 0) and a quantum barrier layer are alternately stacked one by one can be used. The above quantum well layer and / or quantum barrier layer may be doped with an n-type or p-type dopant.

Further, as the p-type nitride semiconductor cladding layer 7, for example, a nitride semiconductor layer made of a group III nitride semiconductor represented by the formula of Al _x6 Ga _y6 In _z6 N (0 ≦ x6 ≦ 1, 0 ≦ y6 ≦ 1, A layer doped with a p-type dopant in 0 ≦ z6 ≦ 1, x6 + y6 + z6 ≠ 0), and in particular, a nitride semiconductor made of a group III nitride semiconductor represented by the formula of Al _x6 Ga _1-x6 N A layer doped with a p-type dopant is preferably stacked on the layer (0 <x6 ≦ 0.4, preferably 0.1 ≦ x6 ≦ 0.3). In addition, as a p-type dopant, magnesium etc. can be used, for example.

The band gap of the p-type nitride semiconductor clad layer 7 is preferably larger than the band gap of the nitride semiconductor active layer 6 from the viewpoint of optical confinement in the nitride semiconductor active layer 6. The thickness of the p-type nitride semiconductor clad layer 7 is not particularly limited, but is preferably 0.01 μm or more and 0.4 μm or less, more preferably 0.02 μm or more and 0.1 μm or less. From the viewpoint of obtaining a p-type nitride semiconductor cladding layer 7 having good crystallinity, the doping concentration of the p-type dopant in the p-type nitride semiconductor cladding layer 7 is 1 × 10 ¹⁸ cm ⁻³ or more and 1 × 10 ²¹ cm. ⁻³ or less, preferably 1 × 10 ¹⁹ cm ⁻³ or more and 1 × 10 ²⁰ cm ⁻³ or less.

Further, as the p-type nitride semiconductor contact layer 8, for example, a nitride semiconductor layer made of a group III nitride semiconductor represented by the formula of Al _x7 Ga _y7 In _z7 N (0 ≦ x7 ≦ 1, 0 ≦ y7 ≦ 1, (0 ≦ z7 ≦ 1, x7 + y7 + z7 ≠ 0), a layer doped with a p-type dopant can be stacked, and in particular, a layer in which a GaN layer is doped with a p-type dopant can be used. From the viewpoint of obtaining a good ohmic contact.

In addition, the doping concentration of the p-type dopant to the p-type nitride semiconductor contact layer 8 is the viewpoint of maintaining good ohmic contact, suppressing the occurrence of cracks in the p-type nitride semiconductor contact layer 8, and maintaining good crystallinity. Therefore, it is preferably in the range of 1 × 10 ¹⁸ cm ^{−3 to} 1 × 10 ²¹ cm ^{−3 and} preferably in the range of 5 × 10 ¹⁹ cm ^{−3 to} 5 × 10 ²⁰ cm ^−3. More preferred. The thickness of the p-type nitride semiconductor contact layer 8 is not particularly limited, but is 0.01 μm or more and 0.5 μm or less from the viewpoint of improving the light emission output of the nitride semiconductor light emitting diode element 100. It is preferably 0.05 μm or more and 0.2 μm or less.

  The n-type nitride semiconductor contact layer 4, the n-type nitride semiconductor clad layer 5, the nitride semiconductor active layer 6, the p-type nitride semiconductor clad layer 7 and the p-type nitride semiconductor contact layer 8 are each a group III nitride. When composed of a semiconductor, these layers are laminated by, for example, the MOCVD method as follows.

  That is, an organic metal source gas of at least one group III element selected from the group consisting of trimethylgallium (TMG), trimethylaluminum (TMA), and trimethylindium (TMI), for example, inside the reactor of the MOCVD apparatus, Stacking can be performed by supplying a nitrogen source gas such as ammonia and thermally decomposing and reacting them.

In addition, when doping silicon that is an n-type dopant, silicon is doped by supplying, for example, silane (SiH ₄ ) as a doping gas in addition to the above-described source gas into the reactor of the MOCVD apparatus. It is possible.

In addition, when doping with p-type dopant magnesium, biscyclopentadienyl magnesium (CP ₂ Mg), for example, is added as a doping gas to the inside of the reactor of the MOCVD apparatus and supplied. Thus, it is possible to dope magnesium.

  Next, as shown in the schematic cross-sectional view of FIG. 8, a translucent electrode layer 9 made of, for example, ITO (Indium Tin Oxide) is formed on the surface of the p-type nitride semiconductor contact layer 8, and then translucency. A p-side electrode 10 is formed on the surface of the electrode layer 9. Thereafter, a part of the stacked body after the formation of the p-side electrode 10 is removed by etching, so that a part of the surface of the n-type nitride semiconductor contact layer 4 is exposed.

  Thereafter, as shown in FIG. 1, by forming n-side electrode 11 on the exposed surface of n-type nitride semiconductor contact layer 4, nitride semiconductor light-emitting diode device 100 of the first embodiment can be manufactured. it can.

  In the nitride semiconductor light-emitting diode device 100 of the first embodiment manufactured as described above, as described above, the columnar shape with aligned crystal grains extending in the normal direction (vertical direction) of the growth surface of the substrate 1 is used. A nitride semiconductor underlayer 3, an n-type nitride semiconductor contact layer 4, an n-type nitride semiconductor clad layer 5, and a nitride semiconductor are formed on the surface of a good crystalline aluminum-containing nitride intermediate layer 2 made of an aggregate of crystals. Since the active layer 6, the p-type nitride semiconductor cladding layer 7 and the p-type nitride semiconductor contact layer 8 are laminated in this order, these layers laminated on the surface of the aluminum-containing nitride intermediate layer 2 are dislocations. The density is low and the crystallinity is excellent. Therefore, the nitride semiconductor light-emitting diode element 100 of the first embodiment formed from such a layer having excellent crystallinity is an element having a low operating voltage and a high light-emission output.

  FIG. 9 is a schematic cross-sectional view of an example of a light-emitting device using the nitride semiconductor light-emitting diode element 100 of the first embodiment. Here, the light-emitting device 200 having the configuration shown in FIG. 9 has a configuration in which the nitride semiconductor light-emitting diode element 100 of the first embodiment is installed on the first lead frame 41. The p-side electrode 10 of the nitride semiconductor light-emitting diode element 100 and the first lead frame 41 are electrically connected by the first wire 45 and the n-side electrode 11 of the nitride semiconductor light-emitting diode element 100. And the second lead frame 42 are electrically connected by a second wire 44. Further, the nitride semiconductor light-emitting diode element 100 is molded with a transparent mold resin 43, so that the light-emitting device 200 has a shell shape.

  Since the light-emitting device having the configuration shown in FIG. 9 uses the nitride semiconductor light-emitting diode element 100 according to Embodiment 1, it can be a light-emitting device having a low operating voltage and a high light-emission output.

<Embodiment 2>
The present embodiment is characterized in that a nitride semiconductor laser element is manufactured instead of the nitride semiconductor light emitting diode element.

  FIG. 10 is a schematic cross-sectional view of a nitride semiconductor laser element according to Embodiment 2, which is another example of the nitride semiconductor element of the present invention.

  In the nitride semiconductor laser device of the second embodiment, an aluminum-containing nitride intermediate layer 2, a nitride semiconductor underlayer 3, an n-type nitride semiconductor cladding layer 54, and an n-type nitride semiconductor light are formed on the surface of the substrate 1. The guide layer 55, the nitride semiconductor active layer 56, the nitride semiconductor protective layer 57, the p-type nitride semiconductor optical guide layer 58, the p-type nitride semiconductor cladding layer 59, and the p-type nitride semiconductor contact layer 60 are stacked in this order. Has been. An insulating film 61 is formed so as to cover the upper surface of the p-type nitride semiconductor cladding layer 59 and the side surface of the p-type nitride semiconductor contact layer 60. The n-side electrode 11 is disposed so as to be in contact with the exposed surface of the n-type nitride semiconductor cladding layer 54, and the p-side electrode 10 is disposed so as to be in contact with the exposed surface of the p-type nitride semiconductor contact layer 60. Has been.

  An example of the method for manufacturing the nitride semiconductor laser element according to the second embodiment will be described below. First, as shown in the schematic cross-sectional view of FIG. 11, the aluminum-containing nitride intermediate layer 2 and the nitride semiconductor underlayer 3 are stacked in this order on the growth surface of the substrate 1 as in the first embodiment. After that, the n-type nitride semiconductor clad layer 54, the n-type nitride semiconductor optical guide layer 55, the nitride semiconductor active layer 56, the nitride semiconductor protective layer 57, the p-type nitride semiconductor optical guide layer 58, p are formed by MOCVD. The type nitride semiconductor clad layer 59 and the p type nitride semiconductor contact layer 60 are laminated in this order to form a laminate.

Here, as the n-type nitride semiconductor clad layer 54, for example, a nitride semiconductor layer (0 ≦ x8 ≦ 1, 0 ≦ y8 ≦ 1) made of a group III nitride semiconductor represented by the formula of Al _x8 Ga _y8 In _z8 N , 0 ≦ z8 ≦ 1, x8 + y8 + z8 ≠ 0), and a layer doped with an n-type dopant can be stacked.

As the n-type nitride semiconductor light guide layer 55, for example, Al _x9 Ga _y9 In _z9 N nitride semiconductor layer made of a Group III nitride semiconductor represented by the formula (0 ≦ x9 ≦ 1,0 ≦ y9 ≦ 1 , 0 ≦ z9 ≦ 1, x9 + y9 + z9 ≠ 0), and a layer doped with an n-type dopant can be stacked.

As the nitride semiconductor active layer 56, for example, a nitride semiconductor layer (0 ≦ x10 ≦ 1, 0 ≦ 0) made of a group III nitride semiconductor having a composition different from each other and represented by the formula of Al _x10 Ga _y10 In _z10 N Nitride semiconductor layer (0 ≦ x11 ≦ 1, 0 ≦ y11 ≦ 1) composed of a group III nitride semiconductor represented by the formula of Al _x11 Ga _y11 In _z11 N and y10 ≦ 1, 0 ≦ z10 ≦ 1, x10 + y10 + z10 ≠ 0) 1, 0 ≦ z11 ≦ 1, x11 + y11 + z11 ≠ 0) can be stacked one by one.

Further, as the nitride semiconductor protective layer 57, for example, a nitride semiconductor layer made of a group III nitride semiconductor represented by the formula of Al _x12 Ga _y12 In _z12 N (0 ≦ x12 ≦ 1, 0 ≦ y12 ≦ 1, 0 ≦ z12 ≦ 1, x12 + y12 + z12 ≠ 0), and the like can be stacked.

As the p-type nitride semiconductor light guide layer 58, for example, Al _x13 Ga _y13 In _z13 N nitride semiconductor layer made of a Group III nitride semiconductor represented by the formula (0 ≦ x13 ≦ 1,0 ≦ y13 ≦ 1 , 0 ≦ z13 ≦ 1, x13 + y13 + z13 ≠ 0), a layer doped with a p-type dopant, or the like can be stacked.

As the p-type nitride semiconductor cladding layer 59, for example, a nitride semiconductor layer made of a group III nitride semiconductor represented by the formula of Al _x14 Ga _y14 In _z14 N (0 ≦ x14 ≦ 1, 0 ≦ y14 ≦ 1, A layer doped with a p-type dopant in 0 ≦ z14 ≦ 1, x14 + y14 + z14 ≠ 0, or the like can be stacked.

Further, as the p-type nitride semiconductor contact layer 60, for example, a nitride semiconductor layer made of a group III nitride semiconductor represented by the formula of Al _x15 Ga _y15 In _z15 N (0 ≦ x15 ≦ 1, 0 ≦ y15 ≦ 1, A layer doped with a p-type dopant in 0 ≦ z15 ≦ 1, x15 + y15 + z15 ≠ 0, or the like can be stacked.

  Next, as shown in the schematic cross-sectional view of FIG. 12, a part of each of the p-type nitride semiconductor cladding layer 59 and the p-type nitride semiconductor contact layer 60 of the stacked body shown in FIG. 11 is removed by etching or the like. As a result, a part of the surface of the p-type nitride semiconductor cladding layer 59 is exposed, and a part of the surface of the n-type nitride semiconductor cladding layer 54 is removed by removing a part of the stacked body shown in FIG. To expose.

  Thereafter, as shown in FIG. 10, an insulating film 61 made of, for example, silicon oxide is formed so as to cover the exposed surface of the p-type nitride semiconductor cladding layer 59 while exposing the surface of the p-type nitride semiconductor contact layer 60. To do. Then, the n-side electrode 11 is formed on the exposed surface of the n-type nitride semiconductor cladding layer 54, and the p-side electrode 10 in contact with the p-type nitride semiconductor contact layer 60 is formed on the insulating film 61. The nitride semiconductor laser element of the second embodiment can be manufactured.

  Here, also in the nitride semiconductor laser device of the second embodiment, as in the first embodiment, an aluminum-containing nitride intermediate by DC magnetron sputtering method in which a voltage is applied between the substrate and the target by a DC-continuous method. By adopting at least one of the above conditions (a) to (c) at the time of laminating the layer 2, the layer 2 is composed of an aggregate of columnar crystals with aligned crystal grains extending in the normal direction of the growth surface of the substrate 1. A good crystalline aluminum-containing nitride intermediate layer 2 is laminated on the growth surface of the substrate 1. A nitride semiconductor underlayer 3, an n-type nitride semiconductor clad layer 54, an n-type nitride semiconductor optical guide layer 55, a nitride are formed on the surface of the aluminum-containing nitride intermediate layer 2 having such good crystallinity. The semiconductor active layer 56, the nitride semiconductor protective layer 57, the p-type nitride semiconductor light guide layer 58, the p-type nitride semiconductor cladding layer 59, and the p-type nitride semiconductor contact layer 60 are grown in this order.

  Therefore, also in the nitride semiconductor laser element of the second embodiment, each layer stacked on the surface of the aluminum-containing nitride intermediate layer 2 can be made to have a high crystallinity by reducing the dislocation density. Therefore, an element having a low operating voltage and a high light emission output can be obtained.

<Embodiment 3>
The present embodiment is characterized in that a nitride semiconductor transistor element, which is an example of an electronic device, is manufactured instead of a light emitting device such as a nitride semiconductor light emitting diode element or a nitride semiconductor laser element.

  FIG. 13 is a schematic cross-sectional view of a nitride semiconductor transistor element according to Embodiment 3, which is another example of the nitride semiconductor element of the present invention.

  Here, in the nitride semiconductor transistor element of the third embodiment, the aluminum-containing nitride intermediate layer 2 and the nitride semiconductor underlayer 3 are stacked in this order on the growth surface of the substrate 1, and the nitride semiconductor A nitride semiconductor electron transit layer 71 made of undoped GaN or the like is laminated on the surface of the underlayer 3, and an n-type nitride semiconductor electron supply layer 72 made of n-type AlGaN or the like is placed on the surface of the nitride semiconductor electron transit layer 71. Are stacked. A source electrode 74, a drain electrode 75, and a gate electrode 73 are formed on the surface of the n-type nitride semiconductor electron supply layer 72.

  Hereinafter, an example of a method for manufacturing the nitride semiconductor transistor element of the third embodiment will be described. First, in the same manner as in the first embodiment, the aluminum-containing nitride intermediate layer 2 and the nitride semiconductor underlayer 3 are stacked in this order on the growth surface of the substrate 1.

  Next, as shown in the schematic cross-sectional view of FIG. 14, a nitride semiconductor electron transit layer 71 is laminated on the surface of the nitride semiconductor underlayer 3 by MOCVD, and the nitride semiconductor electron transit layer 71 is formed on the surface. An n-type nitride semiconductor electron supply layer 72 is stacked on the substrate.

  Thereafter, as shown in FIG. 13, the source electrode 74, the drain electrode 75, and the gate electrode 73 are formed on the surface of the n-type nitride semiconductor electron supply layer 72, respectively, so that the nitride semiconductor transistor of the third embodiment is formed. An element can be manufactured.

  Here, also in the nitride semiconductor transistor element of the third embodiment, as in the first embodiment, an aluminum-containing nitride intermediate layer by a DC magnetron sputtering method in which a voltage is applied between a substrate and a target by a DC-continuous method. By adopting at least one of the above conditions (a) to (c) at the time of laminating the layer 2, the layer 2 is composed of an aggregate of columnar crystals with aligned crystal grains extending in the normal direction of the growth surface of the substrate 1. A good crystalline aluminum-containing nitride intermediate layer 2 is laminated on the growth surface of the substrate 1. The nitride semiconductor underlayer 3, the nitride semiconductor electron transit layer 71, and the n-type nitride semiconductor electron supply layer 72 are arranged in this order on the surface of the aluminum-containing nitride intermediate layer 2 having such good crystallinity. Growing up.

  Therefore, also in the nitride semiconductor transistor element of the third embodiment, each layer laminated on the surface of the aluminum-containing nitride intermediate layer 2 can be a layer having a low dislocation density and excellent crystallinity. Thus, an element with improved characteristics such as electron mobility can be obtained.

<Experimental example 1>
First, the sapphire substrate 101 shown in the schematic cross-sectional view of FIG. 15 was placed on the heater 23 inside the chamber 21 of the DC magnetron sputtering apparatus performed by applying a voltage by the DC-continuous method shown in FIG.

  Here, the sapphire substrate 101 is installed so that the c-plane of the sapphire substrate 101 faces the surface of the Al target 26 and the shortest distance d between the center of the surface of the Al target 26 and the c-plane of the sapphire substrate 101 is 50 mm. did. Thereafter, the sapphire substrate 101 was heated to a temperature of 500 ° C. by the heater 23.

  Next, after supplying only nitrogen gas into the chamber 21 of the DC magnetron sputtering apparatus at a flow rate of 20 sccm, the temperature of the sapphire substrate 101 was maintained at 500 ° C.

  Then, a 3000 W bias voltage was applied between the sapphire substrate 101 and the Al target 26 by a DC-continuous method to generate nitrogen plasma. Subsequently, the internal pressure of the chamber 21 is kept at 0.5 Pa, and nitrogen gas (the volume ratio of the nitrogen gas to the whole gas is 100%) is supplied into the chamber 21 at a flow rate of 20 sccm, so that the DC-continuous As shown in the schematic cross-sectional view of FIG. 17, the columnar crystal of aluminum nitride (AlN) is formed on the c-plane of the sapphire substrate 101 by reactive sputtering using DC magnetron sputtering performed by applying a voltage according to the method. An AlN buffer layer 102 made of an aggregate and having a thickness of 25 nm was stacked. The formation speed of the AlN buffer layer 102 at this time was 0.04 nm / second.

Note that the magnet 27 in the cathode 28 of the DC magnetron sputtering apparatus shown in FIG. 16 was swung in both cases of nitriding the c-plane of the sapphire substrate 101 and laminating the AlN buffer layer 102. The AlN buffer layer 102 is stacked for a predetermined time according to the AlN buffer layer 102 deposition rate measured in advance, and the nitrogen plasma is stopped when the thickness of the AlN buffer layer 102 reaches 25 nm. Thus, the temperature of the sapphire substrate 101 was lowered. The pressure inside the chamber 21 immediately before sputtering was 1 × 10 ⁻⁴ Pa or less.

  Next, the sapphire substrate 101 on which the AlN buffer layer 102 was laminated was taken out from the chamber 21 of the DC magnetron sputtering apparatus and installed in the reactor of the MOCVD apparatus. Here, the sapphire substrate 101 after the lamination of the AlN buffer layer 102 was placed on a susceptor made of graphite in order to be heated by a high frequency induction heating type heater. When the sapphire substrate 101 after the AlN buffer layer 102 is stacked is heated with a resistance heater, the sapphire substrate 101 after the AlN buffer layer 102 is stacked is made of quartz placed on a susceptor made of graphite. Installed on the tray.

  Thereafter, the temperature of the sapphire substrate 101 was raised to 1125 ° C. over about 15 minutes while supplying nitrogen gas and hydrogen gas as carrier gases while supplying ammonia gas into the reactor. Here, the internal pressure of the reaction furnace was normal pressure, and the flow rate ratio of hydrogen gas and nitrogen gas (carrier gas flow rate / nitrogen gas flow rate) as carrier gas was 50/50. Then, after confirming that the temperature of the sapphire substrate 101 was stabilized at 1125 ° C., the supply of TMG gas into the reactor was started, and as shown in the schematic cross-sectional view of FIG. A GaN foundation layer 103 made of undoped GaN having a thickness of 5 μm was laminated on the surface of the substrate by MOCVD. The ammonia gas was supplied into the reactor so that the molar ratio of the group V element to the group III element (number of moles of group V element / number of moles of group III element) was 1500.

  Thereafter, the sapphire substrate 101 after the lamination of the GaN foundation layer 103 was taken out from the reactor. Then, the thin film X-ray diffraction method is used to measure the X-ray rocking curve of the GaN foundation layer 103, and the half-value width (arcsec) of the X-ray rocking curve on the (004) plane of the GaN foundation layer 103 from the X-ray rocking curve. Was calculated. The results are shown in Table 1. As shown in Table 1, the full width at half maximum of the X-ray rocking curve on the (004) plane of the GaN foundation layer 103 in Experimental Example 1 was 382 (arcsec).

Next, the temperature of the sapphire substrate 101 is set to 1125 ° C., and silane gas is supplied into the reaction furnace so that the Si doping concentration is 1 × 10 ¹⁹ / cm ³ , thereby showing the schematic cross-sectional view of FIG. As described above, the Si-doped n-type GaN contact layer 104 having a thickness of 3 μm was laminated on the surface of the GaN foundation layer 103 by MOCVD.

Next, after stopping the supply of TMG gas and hydrogen gas to the inside of the reactor, the temperature of the sapphire substrate 101 was lowered to 800 ° C. After confirming that the internal state of the reaction furnace is stabilized, TMG gas, TMI gas and ammonia gas as raw material gases are supplied into the reaction furnace, and the Si doping concentration is 1 × 10 ¹⁸ / By supplying silane gas to the inside of the reactor so as to be cm ³ , a Si-doped n-type In _0.01 Ga _0.99 N barrier layer having a thickness of 8 nm is formed on the surface of the n-type GaN contact layer 104 as shown in FIG. 105 were laminated.

Next, after stopping the supply of silane gas, a quantum well layer made of In _0.1 Ga _0.9 N was laminated to a thickness of 3 nm by supplying TMG gas and TMI gas.

By repeating the formation procedure of the quantum barrier layer and the quantum well layer as described above, as shown in FIG. 19, a quantum barrier layer composed of 7 layers of n-type GaN and a quantum well composed of 6 layers of In _0.1 Ga _0.9 N The MQW active layer 106 having a multiple quantum well structure in which layers are alternately stacked one by one is stacked on the surface of the n-type In _0.01 Ga _0.99 N barrier layer 105.

Next, the temperature of the sapphire substrate 101 was raised to 1100 ° C., and the carrier gas was changed from nitrogen gas to hydrogen gas. Then, TMG gas, TMA gas, and CP ₂ Mg gas were supplied to the inside of the reaction furnace and then supplied for 2 minutes, and then the supply of TMG gas and TMA gas was stopped. Thereby, as shown in FIG. 19, a Mg-doped p-type Al _0.2 Ga _0.8 N cladding layer 107 having a thickness of 20 nm was stacked on the surface of the MQW active layer 106.

Next, while maintaining the temperature of the sapphire substrate 101 at 1100 ° C., the supply of TMA gas was stopped while supplying ammonia gas into the reaction furnace. Thereafter, by changing the supply amounts of TMG gas and CP ₂ Mg gas into the reactor, the Mg-doped p-type GaN contact layer 108 having a thickness of 0.2 μm is formed into p-type Al _0.2 as shown in FIG. A Ga _0.8 N clad layer 107 was laminated on the surface.

  Immediately after the p-type GaN contact layer 108 was deposited, the energization to the heater was immediately stopped, and the carrier gas supplied into the reactor was changed from hydrogen gas to nitrogen gas. Then, after confirming that the temperature of the sapphire substrate 101 was 300 ° C. or lower, the sapphire substrate 101 after the above layers were stacked was taken out from the reactor.

  Next, as shown in FIG. 19, after forming the ITO layer 109 on the surface of the p-type GaN contact layer 108, the titanium layer, the aluminum layer, and the gold layer are laminated in this order on the surface of the ITO layer 109. Thus, the p-side bonding pad electrode 110 was formed.

  Next, as shown in the schematic cross-sectional view of FIG. 20, a part of the surface of the n-type GaN contact layer 104 is removed by removing a part of the stacked body after the p-side bonding pad electrode 110 is formed by dry etching. Was exposed.

  Thereafter, as shown in the schematic cross-sectional view of FIG. 21, an n-side bonding pad electrode is formed by laminating a nickel layer, an aluminum layer, a titanium layer, and a gold layer in this order on the exposed surface of the n-type GaN contact layer 104. 111 was formed.

  Then, after the back surface of the sapphire substrate 101 is ground and polished to form a mirror-like surface, the sapphire substrate 101 is divided into 350 μm square chips to produce the nitride semiconductor light-emitting diode element of Experimental Example 1. did.

  When a forward current of 20 mA was passed between the p-side bonding pad electrode 110 and the n-side bonding pad electrode 111 of the nitride semiconductor light-emitting diode device of Experimental Example 1 fabricated as described above, the forward current at 20 mA was The forward voltage was 3.3V. This forward voltage corresponds to the operating voltage of the nitride semiconductor light emitting diode element. Further, when the light emission of the nitride semiconductor light-emitting diode element of Experimental Example 1 was observed through the ITO layer 109, the light emission wavelength was 445 nm, and the light emission output was 22.3 mW. These results are shown in Table 1.

<Experimental Examples 2-8>
In Experimental Examples 2 to 8, the shortest distances d between the center of the surface of the Al target 26 and the c-plane of the sapphire substrate 101 are 75 mm (Experimental Example 2), 100 mm (Experimental Example 3), 150 mm (Experimental Example 4), The AlN buffer layer 102 and the GaN foundation layer 103 were formed in the same manner as in Experimental Example 1 except that the thickness was set to 180 mm (Experimental Example 5), 210 mm (Experimental Example 6), 250 mm (Experimental Example 7), and 280 mm (Experimental Example 8). Then, the half width (arcsec) of the X-ray rocking curve on the (004) plane of the GaN foundation layer 103 was calculated. The results are shown in Table 1. As shown in Table 1, the half width (arcsec) of the X-ray rocking curve on the (004) plane of the GaN foundation layer 103 in Experimental Examples 2 to 8 is 273 (Experimental Example 2), 42 (Experimental Example 3), and 40, respectively. (Experimental example 4), 34 (experimental example 5), 40 (experimental example 6), 50 (experimental example 7) and 242 (experimental example 8).

  In Experimental Examples 2 to 8, nitride semiconductor light emitting diode elements (nitride semiconductor light emitting diode elements of Experimental Examples 2 to 8) were manufactured in the same manner as Experimental Example 1 except for the above changes. Then, for each of the nitride semiconductor light emitting diode elements of Experimental Examples 2 to 8, a forward voltage, a light emission wavelength, and a light emission output at a forward current of 20 mA were measured. The results are shown in Table 1.

  As shown in Table 1, the forward voltages at the forward current of 20 mA of the nitride semiconductor light emitting diode elements of Experimental Examples 2 to 8 are 3.2 V (Experimental Example 2), 3.0 V (Experimental Example 3), 2 It was 0.9V (Experimental Example 4), 2.9V (Experimental Example 5), 3.0V (Experimental Example 6), 3.0V (Experimental Example 7), and 3.2V (Experimental Example 8).

  As shown in Table 1, the emission wavelengths of the nitride semiconductor light-emitting diode elements of Experimental Examples 2 to 8 are 447 nm (Experimental Example 2), 448 nm (Experimental Example 3), 445 nm (Experimental Example 4), 448 nm ( Experimental Example 5) 447 nm (Experimental Example 6), 448 nm (Experimental Example 7), and 450 nm (Experimental Example 8).

  As shown in Table 1, the light emission outputs of the nitride semiconductor light-emitting diode elements of Experimental Examples 2 to 8 are 23.8 mW (Experimental Example 2), 25.0 mW (Experimental Example 3), and 25.8 mW (Experimental), respectively. Example 4), 25.5 mW (Experimental Example 5), 25.1 mW (Experimental Example 6), 24.8 mW (Experimental Example 7) and 23.1 mW (Experimental Example 8).

<Experimental Examples 9 to 12>
In Experimental Examples 9 to 12, using a DC magnetron sputtering apparatus performed by applying a voltage by the DC-continuous method having the configuration shown in FIG. 22, the inclination angle θ of the Al target with respect to the normal direction of the c-plane of the sapphire substrate 101 The AlN buffer layer 102 is the same as the experimental example 1 except that the angles are set to 10 ° (experimental example 9), 20 ° (experimental example 10), 45 ° (experimental example 11) and 50 ° (experimental example 12), respectively. And the GaN foundation layer 103 was formed, and the half width (arcsec) of the X-ray rocking curve in the (004) plane of the GaN foundation layer 103 was calculated. The results are shown in Table 1. As shown in Table 1, the half width (arcsec) of the X-ray rocking curve on the (004) plane of the GaN foundation layer 103 in Experimental Examples 9 to 12 is 40 (Experimental Example 9) and 33 (Experimental Example 10), respectively. 35 (Experimental Example 11) and 180 (Experimental Example 12).

  In Experimental Examples 9-12, nitride semiconductor light-emitting diode elements (nitride semiconductor light-emitting diode elements of Experimental Examples 9-12) were produced in the same manner as Experimental Example 1 except for the above changes. Then, for each of the nitride semiconductor light-emitting diode elements of Experimental Examples 9 to 12, the forward voltage, the emission wavelength, and the emission output at a forward current of 20 mA were measured. The results are shown in Table 1.

  As shown in Table 1, the forward voltages at the forward current of 20 mA of the nitride semiconductor light emitting diode elements of Experimental Examples 9 to 12 are 3.0 V (Experimental Example 9), 2.9 V (Experimental Example 10), and 3 respectively. It was 0.0 V (Experimental Example 11) and 3.2 V (Experimental Example 12).

  As shown in Table 1, the emission wavelengths of the nitride semiconductor light-emitting diode elements of Experimental Examples 9 to 12 are 449 nm (Experimental Example 9), 451 nm (Experimental Example 10), 448 nm (Experimental Example 11), and 447 nm (respectively). Experimental example 12).

  As shown in Table 1, the light emission outputs of the nitride semiconductor light-emitting diode elements of Experimental Examples 9 to 12 were 25.0 mW (Experimental Example 9), 25.6 mW (Experimental Example 10), and 24.8 mW (experimental), respectively. Example 11) and 22.2 mW (Experimental Example 12).

<Experimental Examples 13 to 15>
In Experimental Examples 13 to 15, the AlN buffer layer 102 and the GaN were formed in the same manner as in Experimental Example 1 except that the gas supplied into the chamber 21 shown in FIG. 16 was a mixed gas of nitrogen gas and argon gas. The underlayer 103 was formed, and the half width (arcsec) of the X-ray rocking curve on the (004) plane of the GaN underlayer 103 was calculated. The results are shown in Table 1. In Experimental Examples 13 to 15, the volume ratio (nitrogen ratio) occupied by nitrogen gas in the gas supplied into the chamber 21 is 75% (Experimental Example 13), 50% (Experimental Example 14), and 25, respectively. % (Experimental Example 15). As shown in Table 1, the half width (arcsec) of the X-ray rocking curve on the (004) plane of the GaN foundation layer 103 in Experimental Examples 13 to 15 is 77 (Experimental Example 13), 222 (Experimental Example 14) and 422 (Experimental Example 15).

  In Experimental Examples 13 to 15, nitride semiconductor light emitting diode elements (nitride semiconductor light emitting diode elements of Experimental Examples 13 to 15) were produced in the same manner as Experimental Example 1 except for the above changes. For each of the nitride semiconductor light-emitting diode elements of Experimental Examples 13 to 15, the forward voltage, the emission wavelength, and the emission output at a forward current of 20 mA were measured. The results are shown in Table 1.

  As shown in Table 1, the forward voltages at the forward current of 20 mA of the nitride semiconductor light emitting diode elements of Experimental Examples 13 to 15 were 3.1 V (Experimental Example 13), 3.2 V (Experimental Example 14) and 3 respectively. 3 V (Experimental Example 15).

  As shown in Table 1, the emission wavelengths of the nitride semiconductor light-emitting diode elements of Experimental Examples 13 to 15 were 447 nm (Experimental Example 13), 448 nm (Experimental Example 14), and 449 nm (Experimental Example 15), respectively. .

  Moreover, as shown in Table 1, the light emission outputs of the nitride semiconductor light emitting diode elements of Experimental Examples 13 to 15 were 24.3 mW (Experimental Example 13), 22.1 mW (Experimental Example 14), and 21.5 mW (Experimental), respectively. Example 15).

(Evaluation)
As shown in Table 1, in Experimental Examples 3 to 7 where the shortest distance d (mm) between the center of the surface of the Al target 26 and the c-plane of the sapphire substrate 101 is in the range of 100 mm to 250 mm, the shortest distance d Compared with Experimental Examples 1, 2, and 8 in which the GaN is out of this range, the FWHM (arcsec) of the X-ray rocking curve in the (004) plane of the GaN foundation layer 103 is extremely narrow, and thus excellent crystallinity. It was found that a nitride semiconductor light-emitting diode device having excellent characteristics was obtained, and the forward voltage was low and the light emission output was high.

  As shown in Table 1, in Experimental Examples 4 to 6 in which the shortest distance d (mm) is in the range of 150 mm to 210 mm, Experimental Examples 3 and 7 in which the shortest distance d is outside this range In comparison, since the half width (arcsec) of the X-ray rocking curve on the (004) plane of the GaN foundation layer 103 is narrow, an excellent crystalline GaN foundation layer 103 is obtained, and the forward voltage is high. It has been found that a nitride semiconductor light-emitting diode device having excellent characteristics with low light output is obtained.

  Moreover, as shown in Table 1, in the experimental examples 4 to 5 in which the shortest distance d (mm) is in the range of 150 mm or more and 180 mm or less, compared with the experimental example 6 in which the shortest distance d is outside this range. Since the half width (arcsec) of the X-ray rocking curve on the (004) plane of the GaN underlayer 103 is narrow, an excellent crystalline GaN underlayer 103 is obtained, and the forward voltage is low. It has been found that a nitride semiconductor light-emitting diode element having excellent characteristics with high light emission output can be obtained.

  FIG. 23 shows the full width at half maximum (arcsec) of the X-ray rocking curve on the (004) plane of the GaN foundation layer 103 in Experimental Examples 1 to 8, the shortest distance d between the center of the surface of the Al target 26 and the c plane of the sapphire substrate 101. The relationship with (mm) is shown. In FIG. 23, the vertical axis represents the half width (arcsec) of the X-ray rocking curve in the (004) plane of the GaN foundation layer 103, and the horizontal axis represents the center of the surface of the Al target 26 and the c plane of the sapphire substrate 101. The shortest distance d (mm) is shown.

  As shown in FIG. 23, when the shortest distance d between the center of the surface of the Al target 26 and the c-plane of the sapphire substrate 101 is in the range of 100 mm or more and 250 mm or less, the X-ray rocking curve on the (004) plane of the GaN foundation layer 103 It can be seen that the half width (arcsec) of the GaN is extremely narrow, and the crystallinity of the GaN underlayer 103 is greatly excellent.

  Further, as shown in FIG. 23, from the viewpoint of further improving the crystallinity of the GaN foundation layer 103, the half width (arcsec) of the X-ray rocking curve on the (004) plane of the GaN foundation layer 103 is further narrowed. Thus, it is understood that the shortest distance d is preferably in the range of 150 mm to 210 mm, and particularly preferably in the range of 150 mm to 180 mm.

  As shown in Table 1, in Experimental Examples 9 to 11 in which the inclination angle θ of the Al target with respect to the normal direction of the c-plane of the sapphire substrate 101 is in the range of 10 ° to 45 °, the inclination angle θ Compared with Experimental Example 12 in which the angle is 50 °, the half-width (arcsec) of the X-ray rocking curve in the (004) plane of the GaN foundation layer 103 is extremely narrow, and thus the excellent crystalline GaN foundation layer 103 Further, it was found that a nitride semiconductor light emitting diode device having excellent characteristics with a low forward voltage and a high light emission output can be obtained.

  As shown in Table 1, in Experimental Examples 10 to 11 in which the inclination angle θ of the Al target with respect to the normal direction of the c-plane of the sapphire substrate 101 is in the range of 20 ° to 45 °, the inclination angle θ Compared with Experimental Example 9 in which the angle is 10 °, the half-value width (arcsec) of the X-ray rocking curve on the (004) plane of the GaN foundation layer 103 is narrow, so that an excellent crystalline GaN foundation layer 103 is obtained. In addition, it has been found that a nitride semiconductor light emitting diode device having excellent characteristics with a low forward voltage and a high light emission output can be obtained.

  Further, as shown in Table 1, in Experimental Examples 4 and 13 to 14 in which the nitrogen ratio of the gas supplied into the chamber 21 is in the range of 50% or more, the nitrogen ratio is not in that range. Compared to 15, the GaN underlayer 103 with excellent crystallinity is obtained because the half width (arcsec) of the X-ray rocking curve on the (004) plane of the GaN underlayer 103 is narrow, and the forward direction It was found that a nitride semiconductor light-emitting diode element having excellent characteristics with low voltage and high light emission output can be obtained.

  Further, as shown in Table 1, in Experimental Examples 4 and 13 in which the nitrogen ratio of the gas supplied into the chamber 21 is in the range of 75% or more, the Experimental Example 14 in which the nitrogen ratio is not in the range In comparison, since the half width (arcsec) of the X-ray rocking curve on the (004) plane of the GaN foundation layer 103 is narrow, an excellent crystalline GaN foundation layer 103 is obtained, and the forward voltage is high. It has been found that a nitride semiconductor light-emitting diode device having excellent characteristics with low light output is obtained.

  Further, as shown in Table 1, in the experimental example 4 in which the nitrogen ratio of the gas supplied into the chamber 21 is 100%, the GaN foundation layer 103 is compared with the experimental example 13 in which the nitrogen ratio is not 100%. Since the half-width (arcsec) of the X-ray rocking curve in the (004) plane of Nb is narrow, an excellent crystalline GaN underlayer 103 is obtained, and the forward voltage is low and the light emission output is high. It was found that a nitride semiconductor light emitting diode device having the above characteristics was obtained.

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

  The present invention can be used in a method for producing an aluminum-containing nitride intermediate layer, a method for producing a nitride layer, and a method for producing a nitride semiconductor device. In particular, the present invention may be suitably used for the manufacture of nitride semiconductor light-emitting diode elements, nitride semiconductor laser elements, nitride semiconductor transistor elements, and the like using group III nitride semiconductors.

1 substrate, 2 aluminum-containing nitride intermediate layer, 3 nitride semiconductor underlayer, 4 n-type nitride semiconductor contact layer, 5 n-type nitride semiconductor clad layer, 6 nitride semiconductor active layer, 7 p-type nitride semiconductor clad Layer, 8 p-type nitride semiconductor contact layer, 9 translucent electrode layer, 10 p-side electrode, 11 n-side electrode, 21 chamber, 23 heater, 24 heater support material, 25 exhaust port, 26 Al target, 26a 1st Al target, 26b Second Al target, 27 magnet, 27a first magnet, 27b second magnet, 28 cathode, 28a first cathode, 28b second cathode, 29 magnet support material, 29a first Magnet support material, 29b Second magnet support material, 30 Ar gas supply pipe, 31 N2 gas supply pipe, 41 First lead frame 42, second lead frame, 43 mold resin, 44 second wire, 45 first wire, 54 n-type nitride semiconductor cladding layer, 55 n-type nitride semiconductor light guide layer, 56 nitride semiconductor activity Layer, 57 nitride semiconductor protective layer, 58 p-type nitride semiconductor optical guide layer, 59 p-type nitride semiconductor clad layer, 60 p-type nitride semiconductor contact layer, 61 insulating film, 71 nitride semiconductor electron transit layer, 72 n-type nitride semiconductor electron supply layer, 73 gate electrode, 74 source electrode, 75 drain electrode, 100 nitride semiconductor light-emitting diode element, 101 sapphire substrate, 102 AlN buffer layer, 103 GaN underlayer, 104 n-type GaN contact layer, 105 n-type In _0.01 Ga _0.99 n barrier layer, 106 MQW active layer, 107 p-type Al _0.2 Ga _0.8 n cladding layer, 1 8 p-type GaN contact layer, 109 ITO layer, 110 p-side bonding pad electrode, 111 n-side bonding pad electrode 200 light-emitting device.

Claims (5)

a step of disposing a sapphire substrate having a c-plane as a main surface and a target containing aluminum at a distance of 100 mm to 250 mm;
A columnar shape with aligned crystal grains extending in the normal direction of the growth surface of the substrate on the surface of the substrate by a DC magnetron sputtering method in which a voltage is applied between the substrate and the target by a DC-continuous method. Forming an aluminum-containing nitride intermediate layer comprising an aggregate of crystals;
Forming a nitride semiconductor on the aluminum-containing nitride intermediate layer,
In the step of disposing the substrate and the target, the substrate and the target are disposed by inclining the target with respect to the substrate. a step of arranging a sapphire substrate having a c-plane as a main surface and a target containing aluminum at an interval;
Introducing nitrogen gas between the substrate and the target;
A columnar shape with aligned crystal grains extending in the normal direction of the growth surface of the substrate on the surface of the substrate by a DC magnetron sputtering method in which a voltage is applied between the substrate and the target by a DC-continuous method. Forming an aluminum-containing nitride intermediate layer comprising an aggregate of crystals;
Forming a nitride semiconductor on the aluminum-containing nitride intermediate layer,
In the step of disposing the substrate and the target, the substrate and the target are disposed by inclining the target with respect to the substrate.   The method further includes introducing nitrogen gas between the substrate and the target between the step of disposing the substrate and the target and the step of forming the aluminum-containing nitride intermediate layer. Or the manufacturing method of the nitride semiconductor of Claim 2. a step of disposing a sapphire substrate having a c-plane as a main surface and a target containing aluminum at a distance of 100 mm to 250 mm;
A columnar shape with aligned crystal grains extending in the normal direction of the growth surface of the substrate on the surface of the substrate by a DC magnetron sputtering method in which a voltage is applied between the substrate and the target by a DC-continuous method. Forming an aluminum-containing nitride intermediate layer comprising an aggregate of crystals;
Forming a nitride layer on the aluminum-containing nitride intermediate layer,
In the step of disposing the substrate and the target, the target and the target are disposed with the target being inclined with respect to the substrate.   The method further includes introducing a nitrogen gas between the substrate and the target between the step of arranging the substrate and the target and the step of forming the aluminum-containing nitride intermediate layer. The manufacturing method of the nitride layer as described in any one of.

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