JP2004096021A - Iii-group nitride semiconductor crystal, manufacturing method therefor, and iii-group nitride semiconductor epitaxial wafer - Google Patents

Iii-group nitride semiconductor crystal, manufacturing method therefor, and iii-group nitride semiconductor epitaxial wafer Download PDF

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JP2004096021A
JP2004096021A JP2002258344A JP2002258344A JP2004096021A JP 2004096021 A JP2004096021 A JP 2004096021A JP 2002258344 A JP2002258344 A JP 2002258344A JP 2002258344 A JP2002258344 A JP 2002258344A JP 2004096021 A JP2004096021 A JP 2004096021A
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nitride semiconductor
group iii
iii nitride
substrate
semiconductor crystal
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JP3991823B2 (en
Inventor
Mineo Okuyama
Takenori Yasuda
奥山 峰夫
安田 剛規
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Showa Denko Kk
昭和電工株式会社
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a III-group nitride semiconductor crystal whereby the high-quality nitride semiconductor crystal can be formed on a substrate, in a process having a comparably little change in temperature, by utilizing a semiconductor-crystal growing method using the substrate having an irregularly processed surface. <P>SOLUTION: By feeding a III-group raw material to a substrate having an irregularly processed surface while adopting a V/III ratio not larger than 1,000 (inclusive of the case of the V/III ratio being zero), a III-group nitride semiconductor (the III-group nitride semiconductor is represented by InGaAlN) is formed. Thereafter, the vapor-phase epitaxy of a III-group nitride semiconductor crystal is performed by using the III-group raw material and a nitrogen raw material. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a group III nitride semiconductor having good crystallinity used for manufacturing a light emitting diode (LED), a laser diode (LD), an electronic device, and the like (hereinafter, a group III nitride semiconductor is represented by InGaAlN). )) It relates to a crystal and a method for producing the crystal. In particular, the present invention relates to a method for manufacturing a group III nitride semiconductor crystal that can be suitably used for epitaxially growing a group III nitride semiconductor crystal having good crystallinity on a sapphire substrate.
[0002]
[Prior art]
A group III nitride semiconductor has a direct transition band gap of energy corresponding to a visible light to an ultraviolet light region and can emit light with high efficiency, and thus has been commercialized as an LED or LD. In addition, at the heterojunction interface between aluminum gallium nitride (AlGaN) and gallium nitride (GaN), a two-dimensional electron layer is developed due to a piezoelectric effect characteristic of a group III nitride semiconductor. It has the potential to obtain characteristics that cannot be obtained with group III compound semiconductors.
[0003]
However, group III nitride semiconductors have a dissociation pressure of nitrogen of 2000 atm at the temperature for growing single crystals, making it difficult to grow single crystals, and are used for epitaxial growth like other group III-V compound semiconductors. At present, it is difficult to use the group III nitride semiconductor single crystal substrate as the substrate. Therefore, the substrate used for epitaxial growth is sapphire (Al 2 O 3 A substrate made of a different material such as a single crystal or a silicon carbide (SiC) single crystal is used.
[0004]
A large lattice mismatch exists between a substrate made of these different materials and a group III nitride semiconductor crystal epitaxially grown thereon. For example, sapphire (Al 2 O 3 ) And gallium nitride (GaN), there is a 16% lattice mismatch between SiC and gallium nitride. In general, when such a large lattice mismatch exists, it is difficult to directly epitaxially grow a crystal on a substrate, and a crystal having good crystallinity cannot be obtained even when the crystal is grown. Therefore, when a group III nitride semiconductor crystal is epitaxially grown on a sapphire single crystal substrate or a SiC single crystal substrate by metal organic chemical vapor deposition (MOCVD), a low-temperature buffer layer made of aluminum nitride (AlN) or AlGaN is used. In general, a method of depositing a layer referred to as a layer on a substrate and epitaxially growing a group III nitride semiconductor crystal thereon at a high temperature has been generally performed (for example, see Patent Documents 1 and 2).
[0005]
In addition to the above-mentioned growth method using the low-temperature buffer layer, there is also a method of forming an AlN layer grown at a high temperature range of about 900 ° C. to 1200 ° C. on a substrate and growing gallium nitride thereon. It is disclosed (for example, see Patent Document 3 and Non-Patent Document 1).
[0006]
Under such circumstances, the present applicant supplies a Group III raw material with a V / III ratio of 1000 or less (including a case where the V / III ratio is 0) on a substrate to form a Group III nitride semiconductor. A method for producing a group III nitride semiconductor crystal comprising a first step and a second step of vapor phase growing a group III nitride semiconductor crystal on the substrate using a group III raw material and a nitrogen raw material has been developed. , The manufacturing process of a group III nitride semiconductor epitaxial wafer is shortened, the cost is reduced, and the uniformity of the epitaxial layer in the wafer plane is improved.
[0007]
On the other hand, as a method for reducing the dislocation of a semiconductor crystal, a method of forming irregularities on a substrate surface and growing a semiconductor crystal thereon is known. For example, in the case of a group III nitride semiconductor, a stripe-shaped groove is formed on the surface of a sapphire substrate, a buffer layer made of GaN is formed on the substrate at a low temperature, and a group III nitride semiconductor crystal is epitaxially grown thereon at a high temperature. It is disclosed that the dislocation density of the epitaxial layer can be reduced by performing the method (for example, see Patent Document 4 and Non-Patent Document 2).
[0008]
[Patent Document 1]
Japanese Patent No. 3026087
[Patent Document 2]
JP-A-4-297023
[Patent Document 3]
JP-A-9-64477
[Patent Document 4]
JP-A-2002-164296
[Non-patent document 1]
P. Kung, et al., Applied Physics Letters, 1995, Vol. 66, p. 2958
[Non-patent document 2]
K. Tadatomo, et al., Japanese Journal of Applied Physics, 2001, Vol. 40, p. L583-L585
[0009]
[Problems to be solved by the invention]
The present invention utilizes a method of growing a semiconductor crystal using a substrate whose surface is processed into an uneven shape, and is capable of forming a high-quality group III nitride semiconductor crystal on a substrate in a step with a relatively small temperature change. Provided is a possible method for producing a group III nitride semiconductor crystal. In particular, it is an object of the present invention to provide a method of manufacturing a group III nitride semiconductor crystal capable of epitaxially growing a high quality group III nitride semiconductor crystal on a sapphire substrate having a surface processed in an uneven shape. The present invention also provides a high-quality group III nitride semiconductor crystal manufactured by the above manufacturing method, and a group III nitride semiconductor epitaxial wafer using the group III nitride semiconductor crystal.
[0010]
[Means for Solving the Problems]
The present invention
(1) A group III raw material is supplied on a substrate whose surface is processed into an uneven shape with a V / III ratio of 1000 or less (including a case where the V / III ratio is 0), and a group III nitride semiconductor (hereinafter, referred to as III) A group III nitride semiconductor is represented by InGaAlN.), And then a group III nitride semiconductor crystal is vapor-phase grown on the substrate using a group III raw material and a nitrogen raw material. A method for producing a group III nitride semiconductor crystal, comprising a second step.
(2) The method for producing a group III nitride semiconductor crystal according to the above (1), wherein the shape of the unevenness on the substrate surface is a stripe shape.
(3) The method according to the above (1) or (2), wherein the width of the concave portion and the convex portion of the unevenness on the substrate surface are each 3 μm or less, and the depth of the unevenness is 2/3 or less of the width of the concave portion. A method for producing a group III nitride semiconductor crystal.
(4) Sapphire (Al) 2 O 3 The method for producing a group III nitride semiconductor crystal according to any one of the above (1) to (3), wherein
(5) The method for producing a group III nitride semiconductor crystal according to the above (1) to (4), wherein the group III raw material supplied in the first step contains at least Al.
(6) The group III nitride semiconductor crystal according to the above (1) to (5), wherein the group III nitride semiconductor crystal to be vapor-phase grown on the substrate in the second step is made of GaN. Production method.
(7) In the second step, ammonia (NH 3 The method for producing a group III nitride semiconductor crystal according to any one of the above (1) to (6), wherein
(8) In at least one of the first step and the second step, the vapor phase growth is performed by a metal organic chemical vapor deposition (MOCVD) method. A method for producing a group III nitride semiconductor crystal as described above.
(9) The method for producing a group III nitride semiconductor crystal according to any one of the above (1) to (8), wherein the group III nitride semiconductor formed in the first step is an island crystal mass.
(10) The method for producing a group III nitride semiconductor crystal according to the above (1) to (9), wherein the group III nitride semiconductor formed in the first step is a columnar crystal.
(11) The method for producing a group III nitride semiconductor crystal according to the above (10), wherein the columnar crystal is attached on the substrate such that a side surface thereof is substantially perpendicular to the substrate surface.
It is.
[0011]
Also, the present invention
(12) A method of manufacturing a group III nitride semiconductor crystal, in which a first group III nitride semiconductor is formed on a substrate processed into an uneven shape, and a second group III nitride semiconductor crystal is formed thereon. A method for producing a group III nitride semiconductor crystal, wherein the group III nitride semiconductor according to 1 is an aggregate of columnar crystals or island-like crystals.
(13) The method for producing a group III nitride semiconductor crystal according to the above (12), wherein the columnar crystal is attached on the substrate such that a side surface thereof is substantially perpendicular to the substrate surface.
It is.
[0012]
Also, the present invention
(14) A group III nitride semiconductor crystal produced by the method according to (1) to (13).
It is.
[0013]
Also, the present invention
(15) A group III nitride semiconductor epitaxial wafer further comprising a group III nitride semiconductor crystal layer formed on the group III nitride semiconductor crystal according to (14).
It is.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
According to the method for producing a group III nitride semiconductor crystal of the present invention, a group III raw material is supplied on a substrate whose surface is processed into an uneven shape with a V / III ratio of 1000 or less (including a case where the V / III ratio is 0). A first step of forming a group III nitride semiconductor, and then a second step of vapor-phase growing a group III nitride semiconductor crystal on the substrate using a group III raw material and a nitrogen raw material. According to the method for manufacturing a group III nitride semiconductor crystal having the above first and second steps, a group III nitride semiconductor crystal having good crystallinity can be formed on a substrate. In the present invention, the group III nitride semiconductor is represented by InGaAlN.
[0015]
Compared with the conventional method for manufacturing a group III nitride semiconductor crystal using a low-temperature buffer layer, the method of the present invention can reduce the rise and fall of the substrate temperature, shorten the process, and reduce power consumption. As a result, the manufacturing process can be shortened and cost can be reduced. Further, since the change in the temperature of the substrate is small, the warpage of the substrate can be minimized, and the uniformity of the epitaxial layer in the wafer surface is improved.
[0016]
In the present invention, glass, SiC, Si, GaAs, GaP, GaN, AlN, sapphire, or the like can be used as the substrate. Here, in the present invention, particularly, the substrate is made of sapphire (Al 2 O 3 ) Is desirable. When the substrate is sapphire, there is an advantage that a high-quality substrate can be obtained at low cost. As the plane orientation of the sapphire substrate, m-plane, a-plane, c-plane and the like can be used, but among them, c-plane ((0001) plane) is preferable, and the vertical axis of the substrate surface is shifted from the <0001> direction to a specific direction. It is desirable to be inclined. The substrate used in the present invention is preferably subjected to a pretreatment such as organic cleaning or etching before being used in the first step, because the state of the substrate surface can be kept constant.
[0017]
Various shapes such as a stripe shape and a hexagonal column shape can be used for the shape of the unevenness formed on the substrate surface in the present invention. Among them, there is an advantage that processing is easy if the unevenness is formed in a stripe shape. Further, the arrangement of the unevenness can be made to coincide with the plane orientation of the sapphire substrate or can be shifted intentionally. The width of the concave and convex portions and the depth of the concave and convex portions formed on the substrate surface can be arbitrarily selected. However, in order to flatten the surface of the group III nitride semiconductor crystal grown thereon, the width of the concave portion and the width of the convex portion are each 3 μm or less, and the depth of the concave and convex portions is 2/3 or less of the width of the concave portion. It is desirable.
[0018]
In the present invention, trimethyl aluminum, triethyl aluminum, tertiary butyl aluminum, trimethyl gallium, triethyl gallium, tertiary butyl gallium, trimethyl indium, triethyl indium, tertiary butyl indium, and cyclopentane are used as group III raw materials supplied in the first step. Dienyl indium and the like can be used. In addition, when the group III raw material contains at least Al, such as trimethylaluminum, triethylaluminum, tertiarybutylaluminum, etc., since the nitride containing aluminum has a high decomposition temperature, decomposition or sublimation hardly occurs even at high temperatures, and It is particularly preferable because it has an effect that a crystal is easily grown.
[0019]
In the first step of the present invention, a group III nitride semiconductor can be formed by supplying a group V material such as ammonia, an alkylamine, or a hydrazine simultaneously with a group III material. In the present invention, the V / III ratio at the time of supplying the group III raw material in the first step is 1000 or less. It is more preferably at most 500, more preferably at most 100. By setting the V / III ratio in such a manner, there is an effect that a compound semiconductor crystal having an excess of metal is easily generated on the substrate.
[0020]
In the first step of the present invention, the V / III ratio may be 0, that is, the supply amount of the group V raw material may be 0. However, in this case, even if the intentionally supplied group V raw material is 0, ammonia (NH 3 ), Etc. to form a group III nitride semiconductor, or a group III nitride semiconductor is formed by nitrogen supplied from the decomposition of deposits attached to the walls, top plate, susceptor, etc. of the reactor. It is necessary to In the latter case, it is necessary to appropriately control the composition and amount of the deposits attached to the wall of the reactor, the top plate, the susceptor, and the like. Specifically, the baking time and temperature of the reaction furnace after the growth is finished are adjusted, or the operation itself is stopped. In addition, a process called thermal cleaning, which is a general technique for growth using the low-temperature buffer method, adjusts the time and temperature or stops performing the process itself.
As an example, after performing the thermal cleaning at 600 ° C. for 10 minutes without performing the baking after the previous growth, the substrate is set to 1000 ° C. as the first step, and the metal-containing compound of the group III raw material is used. Only, the supply amount of the group V raw material was set to 0, and then the crystal growth was performed in the second step. As a result, a good group III nitride semiconductor crystal could be produced.
[0021]
Another condition for obtaining a good Group III nitride semiconductor crystal even when the V / III ratio in the first step is 0 is that the carrier gas contains N 2 At a temperature close to 1000 ° C. 2 There is a method in which a nitrogen (N) atom generated by slight decomposition of is used as a nitrogen source.
[0022]
In the first step of the present invention, a single gas or a mixed gas such as hydrogen, a rare gas, or nitrogen can be used as an atmosphere gas. As described above, when nitrogen is used as the atmospheric gas, the nitrogen gas may also function as a source gas.
[0023]
The pressure of the atmosphere at the time of performing the first step is 1000 to 1 × 10 5 Pa can be used. Preferably, 1 × 10 5 Pa or less, more preferably 1 × 10 4 Pa or less. When the pressure in the first step is low, the surface of the metal-excessive group III nitride semiconductor layer to be manufactured becomes flat, and the surface of the second group III nitride semiconductor layer grown thereon is also easily flattened. There is.
[0024]
In the present invention, the temperature of the substrate at the time of performing the first step and the temperature of the substrate at the time of performing the second step are not particularly defined, but the temperature of the substrate at the time of performing the first step is the second temperature. It is desirable that the temperature of the substrate is equal to or higher than the temperature of the substrate when performing the step. When the first step is performed at a temperature equal to or higher than the temperature of the substrate at the time of performing the second step, the decomposition of the organometallic compound molecule, which is the group III source gas, is performed efficiently, and the formed crystal is formed. There is an advantage that impurities such as undecomposed alkyl groups are not mixed therein.
[0025]
The group III nitride semiconductor formed in the first step of the present invention is made into an island-shaped crystal mass. That is, an island-shaped crystal cluster having a width of 1 nm to 500 nm and a height of about 5 nm to 100 nm is densely formed. It is thought that by making the group III nitride into an island crystal, a large number of grain boundaries are generated in the crystal layer, so that metal crystals and liquid droplets are more likely to remain there, and the effect of functioning as a layer containing more metal is obtained. It is. Further, the structure may be such that the distribution of the island-shaped crystals is not so dense and the substrate surface can be seen between the crystal lump. In this case, since regions having different crystal growth rates are mixed on the surface, the density of threading dislocations is reduced by the effect of selective growth, and a better crystal can be manufactured.
[0026]
Alternatively, the group III nitride semiconductor formed in the first step of the present invention is made to be a columnar crystal. That is, a columnar crystal in which columnar particles having a width of about 0.1 nm to 100 nm and a height of about 10 nm to 500 nm are collected. It is considered that by forming the group III nitride into a columnar crystal, a large number of grain boundaries are generated in the crystal layer, so that metal crystals and liquid droplets are more likely to remain there, thereby obtaining an effect of functioning as a layer containing more metal. .
[0027]
In the second step of the present invention, a group III nitride semiconductor crystal is vapor-phase grown on the substrate on which the group III nitride semiconductor has been formed in the first step, using a group III raw material and a nitrogen raw material. When the group III nitride semiconductor crystal to be grown is GaN, GaN is easily grown two-dimensionally among the group III nitride semiconductors, so that it is easy and preferable to form a flat epitaxial layer of a GaN crystal. Once a flat and good epitaxial layer is formed by GaN, it becomes easy to manufacture a semiconductor device structure using a group III nitride semiconductor crystal layer of various compositions thereon.
[0028]
In the first step, the second step, or both steps of the present invention, metal organic chemical vapor deposition (MOCVD) or vapor phase epitaxy (VPE) is used as a vapor phase growth method. be able to. Of these, the MOCVD method is preferable because the decomposition rate of the group III raw material can be adjusted and the growth rate is appropriate. Further, according to the MOCVD method, various element structures having good characteristics can be formed on a flat group III nitride semiconductor crystal without removing the substrate on the crystal without taking the substrate out of the reaction furnace. .
[0029]
In growing the group III nitride semiconductor crystal by MOCVD in the second step, the temperature of the substrate is from 950 ° C. to 1200 ° C., and the pressure of the atmosphere is from 1000 Pa to 1 × 10 5 It is preferably Pa.
[0030]
In addition, as a nitrogen source used in the second step, ammonia (NH 3 Is preferred because it is gaseous and easy to handle, is distributed in large numbers on the market and is inexpensive. As group III raw materials, trimethyl aluminum, triethyl aluminum, tertiary butyl aluminum, trimethyl gallium, triethyl gallium, tertiary butyl gallium, trimethyl indium, triethyl indium, tertiary butyl indium, and cyclopentadienyl indium can be used. . Further, the V / III ratio at the time of growing the group III nitride semiconductor crystal in the second step is preferably from 500 to 20,000, more preferably from 2,000 to 20,000.
[0031]
According to the present invention, the method of manufacturing a group III nitride semiconductor crystal having the first and second steps has a high uniformity on a substrate processed into an uneven shape by a power-saving process in a short time, and has a high crystallinity. A group III nitride semiconductor crystal with good properties can be formed. Therefore, by further forming a group III nitride semiconductor crystal layer on the above group III nitride semiconductor crystal, a group III nitride having a laminated structure used for manufacturing a light emitting diode, a laser diode, an electronic device, or the like A semiconductor epitaxial wafer can be manufactured.
[0032]
【Example】
Hereinafter, the present invention will be specifically described based on examples.
(Example 1)
A method for producing a gallium nitride-based compound semiconductor crystal according to the present invention will be described.
In the first embodiment, a sapphire substrate having a (0001) surface is used. The shape of the unevenness formed on the surface of the sapphire substrate is a stripe shape in which concave-shaped lines having a width of 3 μm and a depth of 1.5 μm and convex-shaped spaces having a width of 3 μm are alternately arranged in a straight line. did. The direction of the stripe was parallel to the <1-100> direction of the sapphire substrate. As a first step on the sapphire substrate on which the irregularities have been formed, a gas containing a mixture of a vapor of trimethylaluminum (TMAl) and a vapor of trimethylgallium (TMGa) at a molar ratio of 1: 2 and ammonia (NH) 3 In the second step, gallium nitride was grown by flowing TMGa and ammonia to form a GaN layer made of gallium nitride crystals on a sapphire substrate processed into an uneven shape. The V / III ratio under the conditions used in the first step is about 85.
[0033]
The preparation of the sample including the GaN layer was performed by the following procedure using the MOCVD method.
First, before introducing the sapphire substrate whose surface has been processed into an uneven shape, the deposits that had adhered to the inside of the reactor during the previous growth performed by the same apparatus were heated and nitrided in a gas containing ammonia and hydrogen. To make it more difficult to disassemble. After waiting for the reaction furnace to cool to room temperature, the sapphire substrate was subsequently introduced into a quartz reaction furnace set in an RF coil of an induction heater. The sapphire substrate was mounted on a carbon susceptor for heating in a glove box purged with nitrogen gas. After introducing the sample, the inside of the reactor was purged by flowing nitrogen gas.
After flowing nitrogen gas for 10 minutes, the induction heater was operated to raise the substrate temperature to 1170 ° C. over 10 minutes. While the substrate temperature was maintained at 1170 ° C., the substrate surface was left for 9 minutes while flowing hydrogen gas and nitrogen gas to carry out thermal cleaning of the substrate surface.
During the thermal cleaning, a hydrogen carrier gas was supplied to the piping of a container (bubbler) containing trimethylgallium (TMGa) as a raw material and a container (bubble) containing trimethylaluminum (TMAl) connected to the reactor. It circulated and started bubbling. The temperature of each bubbler was constantly adjusted using a thermostat for adjusting the temperature. Until the growth step was started, the vapors of TMGa and TMAl generated by the bubbling were circulated together with the carrier gas to the piping to the abatement apparatus, and discharged out of the system through the abatement apparatus.
After the completion of the thermal cleaning, the nitrogen carrier gas valve was closed, and the supply of gas into the reaction furnace was made only with hydrogen.
[0034]
After the switching of the carrier gas, the temperature of the substrate was lowered to 1150 ° C. After confirming that the temperature was stabilized at 1150 ° C., the valve of the ammonia pipe was opened, and the flow of ammonia into the furnace was started. Subsequently, the valves for the TMGa and TMAl pipes were simultaneously switched to supply a gas containing the vapors of TMGa and TMAl into the reaction furnace to start the first step of depositing the group III nitride semiconductor on the sapphire substrate. The mixing ratio of TMGa and TMAl to be supplied was adjusted so that the molar ratio became 2: 1 with a flow rate controller installed in the piping for bubbling, and the amount of ammonia was adjusted so that the V / III ratio became 85.
After the treatment for 6 minutes, the valves of the pipes for TMGa and TMAl were simultaneously switched to stop supplying the gas containing the vapors of TMGa and TMAl into the reactor. Subsequently, the supply of ammonia was also stopped, and the temperature was maintained for 3 minutes.
[0035]
After annealing for 3 minutes, the valve of the ammonia gas pipe was switched, and the supply of ammonia gas into the furnace was started again. Ammonia was allowed to flow for 4 minutes. Meanwhile, the flow rate of the flow rate regulator of the TMGa pipe was adjusted. After 4 minutes, the TMGa valve was switched to start supplying TMGa into the furnace together with ammonia, thereby starting GaN growth.
After the growth of the GaN layer for about 3 hours, the valve of the TMGa pipe was switched, the supply of the raw material to the reactor was stopped, and the growth was stopped.
After the growth of the GaN layer was completed, the power supply to the induction heating heater was stopped, and the temperature of the substrate was lowered to room temperature over 20 minutes. During the cooling, the atmosphere in the reaction furnace was composed of ammonia, nitrogen, and hydrogen in the same manner as during the growth, but after confirming that the temperature of the substrate reached 300 ° C., the supply of ammonia and hydrogen was stopped. Thereafter, the substrate temperature was lowered to room temperature while flowing nitrogen gas, and the sample was taken out into the atmosphere.
[0036]
A sample in which a metal-excess III-nitride semiconductor layer having a columnar structure was formed on a sapphire substrate having an uneven surface by the above steps, and a GaN layer having a thickness of 6 μm was epitaxially grown thereon by undoping. Was prepared. The removed substrate had a somewhat metallic blackish color, indicating that the Group III nitride semiconductor layer formed at the interface with the substrate was metal-rich stoichiometric. The growth surface of the GaN layer was a mirror surface.
[0037]
Next, an X-ray rocking curve (XRC) measurement of the undoped GaN layer grown by the above method was performed. The measurement was performed on a (0002) plane, which is a symmetric plane, and a (10-12) plane, which is an asymmetric plane, using a Cuβ-ray X-ray source as a light source. Generally, in the case of a gallium nitride-based compound semiconductor, the XRC spectrum half width of the (0002) plane is an index of crystal flatness (mosaicity), and the XRC spectrum half width of the (10-12) plane is dislocation density (twist). Is an indicator of
As a result of this measurement, the undoped GaN layer produced by the method of the present invention showed a half width of 220 seconds in the measurement of the (0002) plane and a half width of 300 seconds in the (10-12) plane.
[0038]
The outermost surface of the GaN layer was observed using a general atomic force microscope (AFM). As a result, no growth pits were found on the surface, and a good morphological surface was observed.
[0039]
When a cross section of this sample was observed with a transmission electron microscope (TEM), an AlN film having a number of grain boundaries in a direction substantially perpendicular to the substrate surface was observed at the interface between the sapphire substrate and the gallium nitride layer. The film thickness was about 60 nm, and the distance between the grain boundaries was 5 nm to 50 nm. This layer is considered to be a layer composed of an aggregate of vertically elongated columnar crystals. According to elemental analysis, this film contained about 20% of Ga.
[0040]
(Example 2)
In Example 2, an experiment was performed using the same process as in Example 1 except that the time for growing the group III nitride semiconductor in the first process was changed to 2 minutes. Also in this case, the surface of the removed wafer was mirror-like. The color was colorless and transparent.
[0041]
When the cross section of this sample was observed with a transmission electron microscope (TEM), it was confirmed that an island-like AlN crystal mass was present at the interface between the sapphire substrate and the gallium nitride layer. According to elemental analysis, this crystal mass contained about 15% of Ga.
[0042]
The same growth as in this experimental process was performed, and the process was stopped before growing the gallium nitride layer, a sample was taken out of the growth furnace, and the morphology of the surface was observed with an atomic force microscope (AFM). However, on the sapphire surface, aluminum nitride crystal lump having a hexagonal shape with a rounded shape and a trapezoidal cross section as seen from above was scattered.
[0043]
(Example 3)
In Example 3, after the previous experiment, a sapphire substrate whose surface was processed into an uneven shape without performing baking before growth was introduced into the reaction furnace after the previous experiment, and trimethylaluminum (TMAl In the second step, gallium nitride was grown by flowing TMGa and ammonia to produce a GaN layer made of gallium nitride crystals on a sapphire substrate. Although the intended V / III ratio in the first step of this embodiment is 0, a small amount of N atoms is supplied onto the substrate due to decomposition of the deposits attached to the walls and the top plate of the reactor. ing.
[0044]
The preparation of the sample including the GaN layer was performed by the following procedure using the MOCVD method.
First, a sapphire substrate similar to that of Example 1 was introduced into a quartz reactor set in an RF coil of an induction heater. The sapphire substrate was placed on a heating carbon susceptor in a glove box replaced with nitrogen gas. After introducing the sample, the inside of the reactor was purged by flowing nitrogen gas.
After flowing nitrogen gas for 10 minutes, the induction heater was operated to raise the substrate temperature to 600 ° C. over 10 minutes. While maintaining the substrate temperature at 600 ° C., the substrate was left for 9 minutes while flowing hydrogen gas.
In the meantime, a hydrogen carrier gas is passed through piping of a container (bubbler) containing trimethylgallium (TMGa) as a raw material and a container (bubbler) containing trimethylaluminum (TMAl), which are connected to the reaction furnace, to perform bubbling. Started. The temperature of each bubbler was constantly adjusted using a thermostat for adjusting the temperature. Until the growth step was started, the vapors of TMGa and TMAl generated by the bubbling were circulated together with the carrier gas to the piping to the abatement apparatus, and discharged out of the system through the abatement apparatus.
Thereafter, the nitrogen carrier gas valve was closed, and the supply of hydrogen gas into the reactor was started.
[0045]
After switching the carrier gas, the temperature of the substrate was raised to 1150 ° C. After confirming that the temperature was stabilized at 1150 ° C., the valve of the TMAl pipe was switched, and a gas containing TMAl vapor was supplied into the reactor. At this time, it is considered that a small amount of N was supplied to the substrate at the same time as TMAl due to the decomposition of the deposits attached to the wall surface and the top plate of the reactor.
After the treatment for 9 minutes, the valve of the TMAl pipe was simultaneously switched to stop supplying the gas containing the vapor of TMAl into the reaction furnace, and held for 3 minutes.
[0046]
After annealing for 3 minutes, the valve of the ammonia gas pipe was switched, and the supply of ammonia gas into the furnace was started.
Ammonia was allowed to flow for 4 minutes. Meanwhile, the flow rate of the flow rate regulator of the TMGa pipe was adjusted. After 4 minutes, the TMGa valve was switched to start supplying TMGa into the furnace together with ammonia, thereby starting GaN growth.
After the growth of the GaN layer for about 3 hours, the valve of the TMGa pipe was switched, the supply of the raw material to the reactor was stopped, and the growth was stopped.
After the growth of the GaN layer was completed, the power supply to the induction heating heater was stopped, and the temperature of the substrate was lowered to room temperature over 20 minutes. During the cooling, the atmosphere in the reaction furnace was composed of ammonia, nitrogen and hydrogen in the same manner as during the growth, but after confirming that the substrate temperature reached 300 ° C., the supply of ammonia and hydrogen was stopped. Thereafter, the substrate temperature was lowered to room temperature while flowing nitrogen gas, and the sample was taken out into the atmosphere.
[0047]
Through the above steps, a sample was prepared in which a metal-excess Group III nitride semiconductor layer having a columnar structure was formed on the sapphire substrate in the first step, and an undoped GaN layer having a thickness of 6 μm was formed thereon. . The taken out substrate has a somewhat metallic blackish color as in Example 1, and the Group III nitride semiconductor formed at the interface with the substrate is a metal-rich stoichiometric one. Was shown. The growth surface was a mirror surface.
[0048]
Next, XRC measurement was performed on the undoped GaN layer grown by the above method. The measurement was performed on a (0002) plane, which is a symmetric plane, and a (10-12) plane, which is an asymmetric plane, using a Cuβ-ray X-ray source as a light source. As a result of the measurement, the undoped GaN layer produced by the method of the present invention showed a half-width of 260 seconds in the measurement of the (0002) plane and a half-width of 300 seconds in the (10-12) plane.
[0049]
The outermost surface of the GaN layer was observed using a general atomic force microscope (AFM). As a result, no growth pits were found on the surface, and a good morphological surface was observed.
[0050]
When a cross section of this sample was observed with a transmission electron microscope (TEM), an AlN film having a number of grain boundaries in a direction substantially perpendicular to the substrate surface was observed at the interface between the sapphire substrate and the gallium nitride layer. The film thickness was about 20 nm, and the distance between grain boundaries was 10 nm to 50 nm. This layer is considered to be a layer composed of an aggregate of vertically elongated columnar crystals. According to elemental analysis, this film contained about 5% Ga.
[0051]
(Example 4)
In the fourth embodiment, as a first step, a vapor of trimethylaluminum (TMAl) and a vapor of trimethylindium (TMIn) are formed in a molar ratio on a sapphire substrate whose surface has been processed into an uneven shape as in the first embodiment. A gas containing a gas mixed at a ratio of 2: 1 is passed using nitrogen as a carrier gas, and then, as a second step, TMGa and ammonia are passed to grow gallium nitride, and gallium nitride is grown on the sapphire substrate. GaN layer was prepared. It is considered that in the first step, the nitrogen gas serving as the carrier gas was slightly decomposed and supplied a small amount of nitrogen atoms.
[0052]
The preparation of the sample including the GaN layer was performed by the following procedure using the MOCVD method.
First, before introducing the sapphire substrate processed into an uneven shape, the deposits attached to the inside of the reaction furnace in the previous growth performed by the same apparatus were heated and nitrided in a gas containing ammonia and hydrogen, It did not disassemble. After waiting for the reactor to cool to room temperature, the sapphire substrate was subsequently introduced into a quartz reactor placed in the RF coil of the induction heater. The sapphire substrate was placed on a carbon susceptor for heating in a glove box purged with nitrogen gas. After introducing the sample, the inside of the reactor was purged by flowing nitrogen gas.
After flowing nitrogen gas for 10 minutes, the induction heater was operated to raise the substrate temperature to 1170 ° C. over 10 minutes. With the substrate temperature kept at 1170 ° C., the substrate surface was left for 9 minutes while flowing hydrogen gas to perform thermal cleaning of the substrate surface.
During the thermal cleaning, a container (bubbler) containing trimethylgallium (TMGa) and a container (bubbler) containing trimethylaluminum (TMAl) and trimethylindium (TMIn), which are raw materials connected to the reactor, were used. Bubbling was started by flowing a hydrogen carrier gas through the piping of the container (bubble) containing the hydrogen carrier gas. The temperature of each bubbler was constantly adjusted using a thermostat for adjusting the temperature. The vapors of TMGa, TMAl and TMIn generated by the bubbling were circulated together with the carrier gas to the piping to the abatement apparatus until the growth step was started, and were discharged outside the system through the abatement apparatus.
After the completion of the thermal cleaning, the hydrogen carrier gas valve was closed, and instead, the nitrogen gas supply valve was opened, and the gas supply into the reaction furnace was changed to nitrogen.
[0053]
After the switching of the carrier gas, the temperature of the substrate was lowered to 1150 ° C. After confirming that the temperature was stabilized at 1150 ° C., the valves of the TMIn and TMAl pipes were simultaneously switched, and a gas containing the vapors of TMIn and TMAl was supplied into the reaction furnace, and the first step was performed on the sapphire substrate. A process for attaching a group III nitride semiconductor was started. The mixing ratio of TMIn and TMAl to be supplied was adjusted so that the molar ratio was 1: 2 by a flow rate controller installed in the piping for bubbling.
After the treatment for 6 minutes, the valves of the TMIn and TMAl pipes were simultaneously switched to stop supplying the gas containing the vapors of TMIn and TMAl into the reaction furnace, and held for 3 minutes.
[0054]
After annealing for 3 minutes, the valve of the ammonia gas pipe was switched, and the supply of ammonia gas into the furnace was started.
Ammonia was allowed to flow for 4 minutes. Meanwhile, the flow rate of the flow rate regulator of the TMGa pipe was adjusted. After 4 minutes, the TMGa valve was switched to start supplying TMGa into the furnace together with ammonia, thereby starting GaN growth.
After the growth of the GaN layer for about 1 hour, the valve of the TMGa pipe was switched, the supply of the raw material to the reactor was stopped, and the growth was stopped.
After the growth of the GaN layer was completed, the power supply to the induction heating heater was stopped, and the temperature of the substrate was lowered to room temperature over 20 minutes. During the cooling, the atmosphere in the reaction furnace was composed of ammonia, nitrogen and hydrogen in the same manner as during the growth, but after confirming that the substrate temperature reached 300 ° C., the supply of ammonia and hydrogen was stopped. Thereafter, the substrate temperature was lowered to room temperature while flowing nitrogen gas, and the sample was taken out into the atmosphere.
[0055]
A sample in which a metal-excess III-nitride semiconductor layer having a columnar structure was formed on a sapphire substrate having an uneven surface by the above steps, and a 6 μm-thick GaN layer was formed thereon by undoping. Was prepared. The substrate taken out was colorless and transparent. The growth surface was a mirror surface.
[0056]
Next, XRC measurement was performed on the undoped GaN layer grown by the above method. The measurement was performed on a (0002) plane, which is a symmetric plane, and a (10-12) plane, which is an asymmetric plane, using a Cuβ-ray X-ray source as a light source.
As a result of this measurement, the undoped GaN layer produced by the method of the present invention showed a half-width of 350 seconds in the (0002) plane measurement and a half-width of 400 seconds in the (10-12) plane.
[0057]
Further, the outermost surface of the GaN layer was observed using a general atomic force microscope (AFM). As a result, no growth pits were found on the surface, and a good morphological surface was observed.
[0058]
When the cross section of this sample was observed with a transmission electron microscope (TEM), an AlInN film having many grain boundaries in a direction substantially perpendicular to the substrate surface was observed at the interface between the sapphire substrate and the gallium nitride layer. The film thickness was about 10 nm, and the distance between grain boundaries was 5 nm to 50 nm. This layer is considered to be a layer composed of an aggregate of vertically elongated columnar crystals.
[0059]
(Example 5)
Example 5 In Example 5, a method for manufacturing a gallium nitride-based compound semiconductor light emitting device using the method for manufacturing a group III nitride semiconductor crystal of the present invention will be described.
In the fifth embodiment, a flat low-Si-doped GaN crystal is manufactured under the same conditions as in the third embodiment, and a group III nitride semiconductor crystal layer is further formed thereon. An epitaxial wafer having an epitaxial layer structure for a device was manufactured. The epitaxial wafer shown in FIG. 1 has a metal-excess AlN layer 8 having a columnar structure formed on a sapphire substrate 9 having a c-plane by the same growth method as described in Example 3, and then sequentially from the substrate side. , 1 × 10 17 cm -3 2 μm low Si-doped GaN layer 7 having an electron concentration of 1 × 10 19 cm -3 1.8 μm high Si-doped GaN layer 6 having an electron concentration of 1 × 10 17 cm -3 Indium cladding layer 5 having an electron concentration of 100 °, GaN barrier layer 3 beginning with GaN barrier layer 3 and GaN barrier layer 3 having a thickness of 70 ° and five non-doped layers having a thickness of 20 ° Non-doped Al having a multiple quantum well structure 20 and 30 ° formed by alternately stacking InGaN well layers 4 0.2 Ga 0.8 N diffusion prevention layer 2, 8 × 10 17 cm -3 And a structure in which a 0.15 μm Mg-doped GaN layer 1 having a hole concentration of
[0060]
The epitaxial wafer having the epitaxial layer structure for the semiconductor light emitting device was manufactured by the following procedure using the MOCVD method.
Until the AlN layer 8 having a columnar structure was formed on the sapphire substrate 9, the same procedure as described in Example 3 was used.
After the AlN layer 8 having a columnar structure was formed on the sapphire substrate, the flow rate of the flow rate regulator of the TMGa pipe was adjusted while continuing the flow of ammonia. In addition, Si 2 H 6 Started to be distributed to pipes. Until the growth of the low Si-doped GaN layer begins, 2 H 6 Was circulated together with the carrier gas to a pipe to the abatement apparatus, and released out of the system through the abatement apparatus. Then TMGa and Si 2 H 6 Switch the valve of TMGa and Si 2 H 6 And the growth of the low-Si-doped GaN layer 7 was started, and the growth of the low-Si-doped GaN layer 7 was performed for about 2 hours and 30 minutes. SiH 4 Is determined in advance, and the electron concentration of the low-Si-doped GaN layer 7 is 1 × 10 17 cm -3 It was adjusted to be.
Thus, a low Si-doped GaN layer 7 having a thickness of 5 μm was formed.
[0061]
Furthermore, a high Si-doped n-type GaN layer 6 was grown on the low Si-doped GaN layer 7. After growing the low-Si-doped GaN layer 7, TMGa and Si 2 H 6 Supply to the furnace was stopped. Meanwhile, Si 2 H 6 Was changed. The amount to be circulated is considered in advance, and the electron concentration of the high Si-doped GaN layer 6 is 1 × 10 19 cm -3 It was adjusted to be. Ammonia continued to be supplied into the furnace at the same flow rate.
After stopping for 1 minute, TMGa and Si 2 H 6 Supply was resumed and growth continued for one hour. By this operation, a highly Si-doped GaN layer 6 having a thickness of 1.8 μm was formed.
[0062]
After growing the high Si-doped GaN layer 6, TMGa and Si 2 H 6 The supply of these raw materials into the furnace was stopped by switching the valves. While passing the ammonia as it was, the valve was switched to change the carrier gas from hydrogen to nitrogen. Thereafter, the temperature of the substrate was reduced from 1160 ° C to 820 ° C.
While waiting for the temperature change in the furnace, 2 H 6 Was changed. The amount to be circulated is considered in advance, and the electron concentration of the Si-doped InGaN cladding layer 5 is 1 × 10 17 cm -3 It was adjusted to be. Ammonia continued to be supplied into the furnace at the same flow rate.
In addition, the flow of the carrier gas to the bubbler of trimethylindium (TMIn) and triethylgallium (TEGa) was started in advance. Si 2 H 6 The gas and the vapors of TMIn and TEGa generated by bubbling were circulated together with the carrier gas to the piping to the harm removal device until the cladding layer growth process was started, and were discharged out of the system through the harm removal device.
Then, after the condition in the furnace is stabilized, TMIn, TEGa and Si 2 H 6 Were simultaneously switched to start supplying these materials into the furnace. The supply was continued for about 10 minutes to form a Si-doped InGaN cladding layer 5 having a thickness of 100 ° on the high Si-doped GaN layer 6.
Then, TMIn, TEGa and Si 2 H 6 And the supply of these raw materials was stopped.
[0063]
Next, a multiple quantum well structure 20 composed of the barrier layer 3 made of GaN and the well layer 4 made of InGaN was manufactured. In manufacturing the multiple quantum well structure 20, the GaN barrier layer 3 was first formed on the Si-doped InGaN clad layer 5, and the InGaN well layer 4 was formed on the GaN barrier layer. After repeating this structure five times, a sixth GaN barrier layer 3 was formed on the fifth InGaN well layer 4, and the multiple quantum well structure 20 was constituted by the GaN barrier layers 3 on both sides.
That is, after the growth of the Si-doped InGaN cladding layer 5 is completed, the supply of the group III raw material is stopped for 30 seconds, and then the TEGa valve is maintained without changing the substrate temperature, the pressure in the furnace, the flow rate and type of the carrier gas. Was switched to supply TEGa into the furnace. Ammonia continued to be supplied into the furnace at the same flow rate. After supplying TEGa for 7 minutes, the valve was switched again to stop supplying TEGa, and the growth of the GaN barrier layer 3 was completed. Thus, a GaN barrier layer 3 having a thickness of 70 ° was formed.
[0064]
During the growth of the GaN barrier layer 3, the flow rate of TMIn flowing through the pipe to the exclusion facility was adjusted so as to be twice the molar flow rate as compared with the growth of the cladding layer. Oita.
After the growth of the GaN barrier layer 3 is completed, the supply of the group III raw material is stopped for 30 seconds, and then the TEGa and TMIn valves are switched while the substrate temperature, the pressure in the furnace, the flow rate and the type of the carrier gas remain unchanged. TEGa and TMIn were supplied into the furnace. Ammonia continued to be supplied into the furnace at the same flow rate. After supplying TEGa and TMIn for 2 minutes, the valve was switched again to stop supplying TEGa and TMIn, and the growth of the InGaN well layer 4 was completed. As a result, an InGaN well layer 4 having a thickness of 20 ° was formed.
[0065]
After the growth of the InGaN well layer 4 is completed, the supply of the group III raw material is stopped for 30 seconds, and then the TEGa is supplied into the furnace without changing the substrate temperature, the pressure in the furnace, the flow rate and the type of the carrier gas. After starting, the GaN barrier layer 3 was grown again.
Such a procedure was repeated five times to produce five GaN barrier layers 3 and five InGaN well layers 4. Further, the GaN barrier layer 3 was formed on the last InGaN well layer 4.
[0066]
On the multiple quantum well structure 20 ending with this GaN barrier layer 3, non-doped Al 0.2 Ga 0.8 An N diffusion preventing layer 2 was produced.
The flow of the carrier gas to the bubbler of trimethylaluminum (TMAl) has been started in advance. Until the growth step of the diffusion preventing layer 2 was started, the vapor of TMAl generated by the bubbling was circulated together with the carrier gas to the pipe to the abatement apparatus, and discharged out of the system through the abatement apparatus.
[0067]
After the pressure in the furnace was stabilized, the valves for TEGa and TMAl were switched, and the supply of these materials into the furnace was started. Thereafter, after growing for about 3 minutes, the supply of TEGa and TMAl was stopped, and the non-doped Al 0.2 Ga 0.8 The growth of the N diffusion preventing layer 2 was stopped. Thereby, non-doped Al having a thickness of 30 ° is formed. 0.2 Ga 0.8 An N diffusion preventing layer 2 was formed.
[0068]
This non-doped Al 0.2 Ga 0.8 The Mg-doped GaN layer 1 was laminated on the N diffusion preventing layer 2.
The supply of TEGa and TMAl is stopped, and the non-doped Al 0.2 Ga 0.8 After the growth of the N diffusion preventing layer 2 was completed, the temperature of the substrate was raised to 1060 ° C. over 2 minutes. Further, the carrier gas was changed to hydrogen.
In addition, biscyclopentadienyl magnesium (Cp 2 The carrier gas flow to the bubbler of Mg) was started. Cp generated by bubbling 2 Until the growth step of the Mg-doped GaN layer 1 was started, the Mg vapor was allowed to flow along with the carrier gas to the pipe to the abatement apparatus, and was discharged outside the system through the abatement apparatus.
[0069]
Wait until the pressure in the furnace stabilizes by changing the temperature and pressure, and TMGa and Cp 2 The Mg valve was switched to start supplying these raw materials into the furnace. Cp 2 The amount of Mg to be circulated has been considered in advance, and the hole concentration of the Mg-doped GaN layer 1 is 8 × 10 17 cm -3 It was adjusted to be. Then, after growing for about 6 minutes, TMGa and Cp 2 The supply of Mg was stopped, and the growth of the Mg-doped GaN layer 1 was stopped. As a result, a Mg-doped GaN layer 1 having a thickness of 0.15 μm was formed.
[0070]
After the growth of the Mg-doped GaN layer 1 was completed, the power supply to the induction heater was stopped, and the temperature of the substrate was lowered to room temperature over 20 minutes. During the temperature decrease from the growth temperature to 300 ° C., the carrier gas in the reaction furnace is composed of only nitrogen, and is 1% NH 3 in volume. 3 Was distributed. Thereafter, when it is confirmed that the substrate temperature has reached 300 ° C., NH 3 3 Was stopped and the atmosphere gas was changed to nitrogen only. After confirming that the substrate temperature had dropped to room temperature, the wafer was taken out into the atmosphere.
[0071]
By the above procedure, an epitaxial wafer having an epitaxial layer structure for a semiconductor light emitting device was manufactured. Here, the Mg-doped GaN layer 1 exhibited p-type without performing annealing treatment for activating p-type carriers.
[0072]
Next, a light emitting diode, which is a kind of semiconductor light emitting device, was manufactured using an epitaxial wafer having an epitaxial layer structure laminated on the sapphire substrate. FIG. 2 shows a plan view of the electrode structure of the semiconductor light emitting device manufactured in the fifth embodiment.
The prepared wafer is composed of only a p-electrode bonding pad 12 having a structure in which titanium, aluminum, and gold are laminated in order from the surface side on the surface 14 of the Mg-doped GaN layer 1 by known photolithography, and only Au bonded thereto. A translucent p-electrode 13 was formed to produce a p-side electrode.
Further, after that, the wafer is subjected to dry etching to expose the portion 11 of the high Si-doped GaN layer 6 where the n-side electrode is to be formed, and an n-electrode 10 composed of four layers of Ni, Al, Ti and Au is formed on the exposed portion. did. Through these operations, an electrode having a shape as shown in FIG. 2 was produced on the wafer.
[0073]
With respect to the wafer on which the p-side and n-side electrodes were formed in this manner, the back surface of the sapphire substrate was ground and polished to obtain a mirror-like surface. Thereafter, the wafer was cut into 350 μm square chips, mounted on a TO-18 stem with the electrodes facing upward, and gold wires were connected to the electrodes to form bare chip light emitting diodes.
When a forward current was applied between the p-side and n-side electrodes of the bare chip light emitting diode manufactured as described above, the forward voltage at a current of 20 mA was 3.5V. Observation of light emission through the p-side translucent electrode revealed that the emission wavelength was 400 nm and the emission output was 4.5 mW. Such characteristics of the light emitting diode were obtained without variation for the light emitting diode manufactured from almost the entire surface of the manufactured wafer.
[0074]
【The invention's effect】
When the method for producing a group III nitride semiconductor crystal of the present invention is used, the temperature rise and fall are small, so that the time required for the process is short and the power consumption is small. As a result, the manufacturing process can be shortened and cost can be reduced. Further, since the change in temperature is small, the warpage of the substrate can be minimized, and the uniformity of the epitaxial layer in the wafer surface is improved. Furthermore, by using a substrate whose surface is processed into an uneven shape, the dislocation of the group III nitride semiconductor crystal can be reduced.
As a result, when a semiconductor light-emitting device using a gallium nitride-based compound semiconductor is manufactured by using the method for manufacturing a group III nitride semiconductor crystal of the present invention, a light-emitting diode having high brightness and substantially uniform characteristics in a wafer surface is obtained. Can be made.
[0075]
Further, according to the method described in the present invention, as compared with a conventional method using AlN grown at a high temperature, the columnarity is small, the dislocation density is small, and the element structure formed on the crystal shows good element characteristics. Can be produced.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a cross section of an epitaxial wafer for a semiconductor light emitting device according to a fifth embodiment of the present invention.
FIG. 2 is a plan view showing an electrode structure of a semiconductor light emitting device according to Embodiment 5 of the present invention.
[Explanation of symbols]
1 Mg-doped GaN layer
2 Al 0.2 Ga 0.8 N diffusion prevention layer
3 GaN barrier layer
4 InGaN well layer
5 InGaN cladding layer
6 High Si-doped GaN layer
7 Low Si doped GaN layer
8 AlN layer
9 Sapphire substrate
10 n electrode
11 Portion of n-side electrode of high Si doped GaN layer
12 p electrode bonding pad
13 Transparent p-electrode
14 Surface of Mg-doped GaN layer
20 Multiple quantum well structure

Claims (15)

  1. A group III raw material is supplied on a substrate whose surface is processed into an uneven shape with a V / III ratio of 1000 or less (including a case where the V / III ratio is 0), and a group III nitride semiconductor (hereinafter, group III nitride) A semiconductor is represented by InGaAlN), and then a second step of vapor-phase growing a group III nitride semiconductor crystal on the substrate using a group III raw material and a nitrogen raw material. A method for producing a group III nitride semiconductor crystal having a step.
  2. The method for producing a group III nitride semiconductor crystal according to claim 1, wherein the shape of the unevenness on the substrate surface is a stripe shape.
  3. 3. The group III nitride semiconductor crystal according to claim 1, wherein the width of the concave portion and the convex portion of the unevenness on the substrate surface are each 3 μm or less, and the depth of the unevenness is 2/3 or less of the width of the concave portion. Manufacturing method.
  4. 4. The method according to claim 1, wherein sapphire (Al 2 O 3 ) is used as the substrate. 5.
  5. 5. The method for producing a group III nitride semiconductor crystal according to claim 1, wherein the group III raw material supplied in the first step contains at least Al.
  6. 6. The method for producing a group III nitride semiconductor crystal according to claim 1, wherein the group III nitride semiconductor crystal grown in a vapor phase on the substrate in the second step is made of GaN.
  7. 7. The method for producing a group III nitride semiconductor crystal according to claim 1, wherein ammonia (NH 3 ) is used as a nitrogen source in the second step.
  8. 8. The group III nitride semiconductor according to claim 1, wherein in at least one of the first step and the second step, vapor phase growth is performed by metal organic chemical vapor deposition (MOCVD). Method for producing crystals.
  9. 9. The method for producing a group III nitride semiconductor crystal according to claim 1, wherein the group III nitride semiconductor formed in the first step is an island crystal mass.
  10. 10. The method for producing a group III nitride semiconductor crystal according to claim 1, wherein the group III nitride semiconductor formed in the first step is a columnar crystal.
  11. The method for producing a group III nitride semiconductor crystal according to claim 10, wherein the columnar crystal is attached on the substrate such that a side surface thereof is substantially perpendicular to the substrate surface.
  12. In the method for manufacturing a group III nitride semiconductor crystal in which a first group III nitride semiconductor is formed on a substrate processed into an uneven shape, and a second group III nitride semiconductor crystal is formed thereon, A method for producing a group III nitride semiconductor crystal, wherein the group III nitride semiconductor is an aggregate of columnar crystals or island-like crystals.
  13. 13. The method for producing a group III nitride semiconductor crystal according to claim 12, wherein the columnar crystal is attached on the substrate such that a side surface thereof is substantially perpendicular to the substrate surface.
  14. A group III nitride semiconductor crystal produced by the method according to claim 1.
  15. A group III nitride semiconductor epitaxial wafer further comprising a group III nitride semiconductor crystal layer formed on the group III nitride semiconductor crystal according to claim 14.
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WO2005109478A1 (en) * 2004-05-12 2005-11-17 Showa Denko K.K. P-type group iii nitride semiconductor and production method thereof
JP2006229219A (en) * 2004-05-12 2006-08-31 Showa Denko Kk P-type group iii nitride semiconductor and production method thereof
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WO2007129773A1 (en) * 2006-05-10 2007-11-15 Showa Denko K.K. Iii nitride compound semiconductor laminated structure
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US7655491B2 (en) 2004-05-12 2010-02-02 Showa Denko K.K. P-type Group III nitride semiconductor and production method thereof
JP2006229219A (en) * 2004-05-12 2006-08-31 Showa Denko Kk P-type group iii nitride semiconductor and production method thereof
WO2005109478A1 (en) * 2004-05-12 2005-11-17 Showa Denko K.K. P-type group iii nitride semiconductor and production method thereof
JP2007128925A (en) * 2004-09-23 2007-05-24 Philips Lumileds Lightng Co Llc Growth of group iii light-emitting device on textured substrate
WO2007129773A1 (en) * 2006-05-10 2007-11-15 Showa Denko K.K. Iii nitride compound semiconductor laminated structure
JPWO2007129773A1 (en) * 2006-05-10 2009-09-17 昭和電工株式会社 Group III nitride compound semiconductor multilayer structure
US8148712B2 (en) 2006-05-10 2012-04-03 Showa Denko K.K. Group III nitride compound semiconductor stacked structure
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