JP2003347226A - Method of manufacturing iii-v compound semiconductor and compound semiconductor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To grow a III-V compound semiconductor that is improved in surface characteristic on a sapphire substrate by a vapor phase method. <P>SOLUTION: When a GaN layer 3 which is the III-V compound semiconductor expressed by a general formula of In<SB>x</SB>Ga<SB>y</SB>Al<SB>z</SB>N (wherein x+y+z=1, 0≤x≤1, 0≤y≤1, and 0≤z≤1) is grown on the sapphire substrate in a crystallized state, the sapphire substrate 1 formed so that an absolute value (off angle) between the surface 1A and the C-face of the substrate 1 becomes ≤0.5° is prepared. After the surface 1A of the substrate 1 is vapor-phase etched by using HCl, the GaN layer 3 is grown on the surface 1A in a crystallized state by the MOVPE method. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a nitride group 3-5 compound semiconductor and a compound semiconductor device.

[0002]

2. Description of the Related Art As a material for a light emitting device such as an ultraviolet, blue or green light emitting diode or an ultraviolet, blue or green laser diode, a general formula In _x called a nitride-based group III-V compound semiconductor or the like is used. Ga _y Al _z N (provided that, x + y + z = 1,0 ≦ x ≦ 1,0 ≦ y ≦ 1,0 ≦
A group 3-5 compound semiconductor represented by z ≦ 1) is known. In the general formula, x, y, and z each represent a composition ratio with respect to nitrogen (N), and x may be referred to as an InN mixed crystal ratio, y may be referred to as a GaN mixed crystal ratio, and z may be referred to as an AlN mixed crystal ratio. .

[0003] As a method for producing a nitride-based group III-V compound semiconductor represented by the above general formula, a molecular beam epitaxy (hereinafter sometimes referred to as MBE) method, a metal organic chemical vapor deposition (hereinafter referred to as MOVPE). And hydride vapor phase epitaxy (hereinafter sometimes referred to as HVPE).

[0004] Since it is difficult to produce a crystal substrate of the compound semiconductor that can be used as a substrate for vapor phase growth, the compound semiconductor is prepared using a vapor phase growth method such as MOVPE, HVPE or MBE. In the case of manufacturing, a substrate using a material other than a nitride-based group III-V compound semiconductor such as sapphire or SiC is used. In particular, the sapphire substrate has the same hexagonal system as that of the compound semiconductor and is widely used at present because of its stability at the growth temperature and growth atmosphere used for the compound semiconductor.

In the case of a nitride-based group III-V compound semiconductor, unlike other group III-V compound semiconductors such as a GaAs-based compound, simply doping a p-type dopant by vapor phase growth by MOVPE method, It is known that it is difficult to obtain a good p-type crystal.

For this reason, conventionally, (1) a nitride-based group III-V compound semiconductor layer doped with a p-type dopant using hydrogen as a carrier gas is vapor-phase grown on a substrate, and then substantially A heat treatment at 700 to 1000 ° C. in an atmosphere of nitrogen gas or the like containing no hydrogen to reduce the concentration of hydrogen in the crystal to reduce the resistance (p-type) (JP-A-5-183189); (2) A nitride-based group III-V compound semiconductor layer doped with a p-type dopant using hydrogen as a carrier gas is vapor-phase grown on a substrate, and in a subsequent cooling step, up to 700 ° C. in an ammonia atmosphere. And a method of lowering the resistance (p-type) by cooling in a nitrogen gas atmosphere at a temperature of 700 ° C. or lower (Japanese Patent Application Laid-Open No. 9-199758).

[0007]

Therefore, when a nitride-based group III-V compound semiconductor is vapor-phase grown on a conventionally used substrate, the state of the surface of the substrate may be increased depending on the state of the surface of the substrate. It is known that the specularity of the surface of the grown nitride-based group III-V compound semiconductor changes. When a nitride-based group III-V compound semiconductor is epitaxially grown on a substrate and various epitaxial crystal thin films are further formed thereon to manufacture a compound semiconductor device of a light emitting device, the epitaxial crystal growth is performed. If the surface roughness of the layer is large, the crystallinity of the device layer formed thereon is impaired, and the electrical characteristics of various finally obtained semiconductor elements are adversely affected. I have.

Further, with respect to the point of lowering the resistance, there is a problem that the lowering of the resistance is not sufficient even by the above-mentioned conventional methods (1) and (2). Therefore, the nitride-based group III-V compound semiconductor layer doped with a p-type dopant is vapor-phase grown on a substrate by using an inert gas containing substantially no hydrogen as a carrier gas, so that the resistance is reduced at once. (P-type) semiconductor, and in a subsequent cooling step, up to 600 ° C. in an ammonia atmosphere,
Cooling is performed in a nitrogen gas atmosphere at a temperature of not more than ℃.
No. 325094) has also been proposed. However, even with this method, lowering the resistance has not always been satisfactory.

An object of the present invention is to provide a method of manufacturing a Group 3-5 compound semiconductor and a compound semiconductor device which can solve the above-mentioned problems in the prior art.

An object of the present invention is to provide a method for producing a Group 3-5 compound semiconductor capable of vapor-phase growing a Group 3-5 compound semiconductor having improved surface characteristics on a substrate, and a compound using the same. It is to provide a semiconductor device.

Another object of the present invention is to provide a method of manufacturing a Group III-V compound semiconductor and a compound semiconductor device capable of forming a Group III-V compound semiconductor on a substrate with good productivity. It is in.

Another object of the present invention is to provide a method for producing a nitride-based group III-V compound semiconductor having excellent p-type electric characteristics.

It is still another object of the present invention to provide a compound semiconductor device having excellent electrical characteristics, particularly as a light emitting device.

[0014]

Means for Solving the Problems The present inventors have repeatedly studied the relationship between the surface structure of a substrate and the surface characteristics of a group III-V compound semiconductor formed thereon based on various experimental results. ,
When a group 3-5 compound semiconductor is crystal-grown on a substrate by an appropriate vapor phase epitaxy method, the substrate surface is subjected to vapor phase etching using a gas containing a halogen element in a molecule, and further, the substrate surface and the C surface are etched. The absolute value of the angle (off angle) is 0.
It has been found that when a substrate larger than 5 degrees is used, the surface roughness of the group 3-5 compound semiconductor is increased, and conversely, when a substrate having a temperature of 0.5 degrees or less is used, the surface roughness is reduced. Was.

That is, the present invention is the invention described below.

According to the first aspect of the present invention, the general formula In _x Ga _y Al _z N (where x + y + z = 1, 0 ≦
A method for producing a Group 3-5 compound semiconductor by growing a crystal of a Group 3-5 compound semiconductor represented by x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1). A substrate having an absolute value of an angle of 0.5 degrees or less is prepared, the substrate surface of the substrate is subjected to vapor phase etching using a gas containing a halogen element in a molecule, and then a 3- There has been proposed a method of manufacturing a Group 3-5 compound semiconductor, which comprises growing a Group 5 compound semiconductor by a vapor phase growth method.

According to the invention of claim 2, generally on the substrate type In _x Ga _y Al _z N (provided that, x + y + z = 1,0 ≦
A method for producing a Group 3-5 compound semiconductor by growing a crystal of a Group 3-5 compound semiconductor represented by x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1). A substrate having an absolute value of 0.5 ° or less is prepared, and the substrate surface of the substrate is subjected to gas phase etching using a gas containing a halogen element in a molecule, and then the substrate surface of the substrate is A method for manufacturing a Group 3-5 compound semiconductor, characterized in that after stacking a buffer layer, a Group 3-5 compound semiconductor is grown by vapor phase epitaxy.

According to the invention of claim 3, according to claim 1 or 2,
In the invention of the above, the gas containing a halogen element in the molecule is H
A method for producing a Group 3-5 compound semiconductor characterized by being Cl is proposed.

According to a fourth aspect of the present invention, there is provided the method of manufacturing a group 3-5 compound semiconductor according to the first, second or third aspect, wherein the substrate is sapphire.

According to the invention of claim 5, claims 1, 2,
In the invention according to 3 or 4, there is proposed a method for producing a Group 3-5 compound semiconductor, wherein the vapor phase growth method is an organometallic vapor phase epitaxy method.

According to the sixth aspect of the present invention, the first, second,
3- obtained by the production method described in 3, 4 or 5
Group 5 compound semiconductors are proposed.

In the vapor phase growth process of a nitride-based group III-V compound semiconductor doped with a p-type dopant, the present inventors used an inert gas containing substantially no hydrogen as a carrier gas, In the cooling step after the growth, it was found that by stopping the supply of ammonia when the temperature reached a specific temperature, a nitride-based group III-V compound semiconductor exhibiting good p-type electrical characteristics could be obtained. Invented the invention.

According to the seventh aspect of the present invention, a p-type dopant is doped by a metal organic chemical vapor deposition method using an inert gas substantially free of hydrogen as a carrier gas and using ammonia as a group V raw material. formula In _x Ga _y A
l _z N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1, x + y
+ Z = 1), after the growth of the group 3-5 compound semiconductor represented by the formula (1), the supply of ammonia is stopped in the range of 1100 ° C. to 700 ° C. in the cooling step. Is proposed.

According to an eighth aspect of the present invention, there is provided the method of the seventh aspect, wherein the hydrogen concentration in the inert gas substantially containing no hydrogen is 0.5% by volume or less.

According to the ninth aspect, the seventh or eighth aspect is provided.
In the invention, the inert gas is helium, argon,
A production method is proposed which is at least one selected from nitrogen.

According to the tenth aspect, the seventh and eighth aspects are provided.
Alternatively, in the invention according to the ninth aspect, a manufacturing method in which the p-type dopant is Mg is proposed.

[0027] According to the eleventh aspect, the seventh aspect has
In the invention of 8, 9 or 10, a production method in which the temperature at which the supply of ammonia is stopped is in the range of 1000 ° C to 800 ° C is proposed.

According to the twelfth aspect, the seventh aspect is
A compound semiconductor obtained by the manufacturing method described in 8, 9, 10 or 11 is proposed.

According to a thirteenth aspect of the present invention, there is provided a compound semiconductor device using the compound semiconductor according to the twelfth aspect.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an example of an embodiment of the present invention will be described in detail.

[0031] Group III-V compound semiconductor to which the present invention have the general formula In _x Ga _y Al _z N (provided that, x + y + z
= 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1). In the following description, a Group 3-5 compound semiconductor represented by the above general formula may be abbreviated as a nitride 3-5 compound semiconductor or simply a semiconductor.

FIG. 1 is a process explanatory view for explaining an example of an embodiment in the case of forming a nitride group III-V compound semiconductor on a sapphire substrate according to the present invention. Substrates that can be used in the present invention include S
iC, Si, ZrB _{2 and the} like. This embodiment will be described with reference to FIG.
As shown in (1), a sapphire substrate 1 having appropriate dimensions is prepared. The surface of the sapphire substrate 1 is mirror-polished,
The angle (off angle) between the substrate surface (front surface) 1A and the C surface is set to 0.430 degrees. The off angle may be 0.5 degrees or less, and the off angle of 0.430 degrees is merely an example. When the sapphire substrate 1 having an off angle of 0.5 degrees or less is prepared, organic cleaning for removing oil and moisture is performed. As a cleaning liquid for organic cleaning, a conventionally known cleaning liquid can be used.

After cleaning, the sapphire substrate 1 is
In an OVPE reactor, HC was added to the MOVPE reactor.
By introducing and flowing 1 gas, the surface 1A of the sapphire substrate 1 is etched and its surface is modified. The substrate temperature at this time may be about 1000 ° C. Etching is performed by removing impurities adhering to surface 1A or surface 1A.
The oxides and the like deposited on the surface are removed, whereby the surface 1A
This is considered to be a process for reforming. Specific examples of the etching gas containing a halogen element in a molecule other than HCl that can be used in the present invention include AsC.
l _3, PCl _3, HBr, such as HI, and the like.

Next, the temperature of the sapphire substrate 1 is set to 500 ° C.
And trimethylgallium (TMG) and ammonia are supplied into the MOVPE reactor, and Ga on the surface 1A.
The buffer layer 2 is formed by growing the N layer to a predetermined thickness (FIG. 1B). The thickness of the buffer layer 2 can be set to 500 °. As a buffer layer, besides GaN, besides Al
N, AlGaN, SiC or a laminated structure of these can be used. These buffer layers can be used by appropriately controlling the growth conditions, composition, film thickness, and structure according to the substrate to be used.

After the buffer layer 2 is formed on the sapphire substrate 1 in this manner, a source gas obtained by adding silane (SiH ₄ ) as a dopant to TMG and ammonia as a dopant is supplied into the MOVPE reactor, and the substrate temperature is set to 1040.
The temperature is raised to about ° C., thereby forming a GaN layer 3 which is a crystalline thin film layer of an n-type nitride group 3-5 compound semiconductor layer.

As described above, the GaN layer 3 is considered to have been surface-modified by removing impurities and the like from its surface by etching, and the GaN layer 3 is formed on the sapphire substrate 1 having an off angle of 0.5 degrees or less by MOVPE. Since the GaN crystal thin film is formed as a crystal thin film by epitaxial vapor deposition, the specularity of the surface 3A of the GaN layer 3, that is, the surface roughness, is lower than that of the conventional method in which the etching and off-angle are not considered. It is much improved.

In this embodiment, the buffer layer 2 is formed on the sapphire substrate 1 before the GaN layer 3 is formed. However, the formation of the buffer layer 2 is not necessarily required. Even when the GaN layer 3 is formed as described above without forming the buffer layer 2, the mirror surface of the surface 3A of the GaN layer 3 can be made much more excellent than in the past. it can.

The epitaxial substrate 4 obtained as shown in FIG. 1 (C) has a well-known layer structure on the epitaxial substrate 4 because the surface 3A of the GaN layer 3 is much more excellent in specularity. When a light emitting function layer is formed and a light emitting element such as a light emitting diode is manufactured by using the light emitting functional layer, luminance and the like can be improved, and a light emitting element having excellent electric characteristics as a light emitting diode can be obtained.

FIG. 2 shows another embodiment of the present invention. The embodiment shown in FIG. 2 is an example in which a light emitting diode crystal structure manufactured by applying the method of the present invention is manufactured on a sapphire substrate 11.

The off-angle of the sapphire substrate 11 is 0.5 degrees or less, and after etching the substrate surface 11A with HCl, the low-temperature buffer layer (GaN layer) 12 and the n-type GaN layer (Si-doped) 13 are shown in FIG. The process is the same as that of the above-described embodiment up to the point where the n-type GaN layer 13 is formed in accordance with the illustrated steps and thereby forms the n-type GaN layer 13 in which the surface 13A has an extremely excellent specularity.

Accordingly, a method of forming a light emitting function layer functioning as a light emitting diode on the n-type GaN layer 13 will be described in detail below. A non-doped GaN layer 14 is further grown on the n-type GaN layer 13 at a growth temperature of 1040 ° C. by about 0.25 μm. Thereafter, the temperature was lowered to about 800 ° C., the carrier gas was nitrogen, and TE was used as a source gas.
A GaN barrier layer 15 having a thickness of 25 nm doped with Si using G, TMI, silane, and ammonia and an InGaN quantum well layer 16 having a thickness of 3 nm are repeatedly formed five times to form a multiple quantum well structure layer 17. Form. Further, on the multiple quantum well structure layer 17, an Al _0.2 Ga _0.8 N layer
Grow 5 nm.

Next, with nitrogen as the carrier gas, 1
The temperature was raised to 040 ° C., TMG and ammonia were used as raw material gases, and bisethylcyclopentadienyl magnesium [(C ₂ H ₅ C ₅ H ₄ ) ₂ M was used as a p-type dopant raw material.
g, hereinafter referred to as ECp ₂ Mg. ]Using,
A 200 nm thick p-type GaN layer 19 doped with Mg is grown. After the growth of the p-type GaN layer 19, which is a p-type nitride group 3-5 compound semiconductor, heating of the sapphire substrate 11 is stopped, and cooling is performed while flowing ammonia and a carrier gas. At this time, when the temperature of the sapphire substrate 11 reaches 900 ° C., the supply of ammonia is stopped,
After cooling the sapphire substrate 11 to room temperature as it is, the sapphire substrate 11 on which the light emitting diode crystal is formed is formed.
Take out.

The p-type GaN layer 19 thus obtained can realize a high p-type carrier concentration without post-processing.
The feature of the above-described processing that can realize a high p-type carrier concentration in this manner is that, in the vapor phase growth process of a nitride-based compound semiconductor doped with a p-type dopant by the MOVPE method, substantially as a carrier gas, In a cooling step after growth, a specific gas called an inert gas containing no hydrogen is used.
The point is that it stops when it reaches a specific temperature of ~ 700 ° C.

(Embodiment) An epitaxial substrate having a layer structure shown in FIG. 1C was fabricated by MOVPE using a spherical convex sapphire substrate as shown in FIG.

FIG. 3 shows a cross section of the sapphire substrate. The sapphire substrate has a radius of curvature R of 2000 mm, and its off-angle, that is, the angle formed between the sapphire substrate surface and the C surface ((0001) surface) is as follows. , 0 ° at the center point a of the substrate, but −0.72 ° at one end point b of the substrate,
At the other end point c, the angle is +0.72 degrees.
The off angle changes continuously with the end point c.

After organically cleaning the surface of the sapphire substrate,
The sapphire substrate is placed in a MOVPE reactor, and HCl gas diluted with hydrogen to a concentration of 20% in a hydrogen carrier gas is supplied to the reactor.
At 100 cc / min into the MOVPE reactor,
The surface of the sapphire substrate was subjected to an etching treatment by holding at 15 ° C. for 15 minutes. The HCl gas at this time was introduced intermittently for 15 seconds every 3 minutes.

The growth of the nitride-based group III-V compound semiconductor on the sapphire substrate whose surface has been etched in this manner is performed by forming a GaN layer as a buffer layer 2 at 485 ° C. using TMG and ammonia at a thickness of 500 °. After that, TM
G, ammonia and silane as dopant (Si
Using H ₄ ), a GaN layer doped with Si was formed at 1040 ° C. with a thickness of 5.6 μm.

In order to measure the surface roughness of the surface of the Si-doped GaN layer, the sample obtained by the above method was evaluated using a stylus type surface roughness meter. The measurement was performed in the M-axis direction (parallel to the orientation flat) and the A-axis direction (perpendicular to the orientation flat) of sapphire with reference to the center position a. As shown in FIG. 3, the off angle θ at each measurement position is a distance from the center X mm, and R =
It is determined using the equation θ = sin ⁻¹ (X / R) with 2000 mm.

FIG. 4 shows that the position X is between +25 mm and −25 m.
The measurement results within the range of m are shown. It can be seen that the surface roughness Ra changes as the off-angle changes. The unit of Ra is Å. When the position farthest from the center, that is, when the off-angle is at a maximum of about 0.72 degrees, the surface roughness is at a maximum of 210 ° or more.

FIG. 5 is a graph of the measured data shown in FIG. 4, where the abscissa represents the off angle (θ),
The vertical axis indicates the surface roughness Ra (Å). FIG. 5 shows measured values along the M-axis direction (direction parallel to the orientation flat) and measured values along the A-axis direction (direction perpendicular to the orientation flat). In each case, it can be seen that when the absolute value of the off-angle is smaller than 0.5, the surface roughness Ra is much smaller than when the absolute value of the off-angle is larger. That is, by setting the off angle to 0.5 degrees or less, the surface roughness can be stably set to about 200 degrees or less.

In particular, by setting the off angle to be 0.1 ° or more and 0.4 ° or less, the surface roughness becomes approximately 100 ° or less, and a film having extremely high flatness can be obtained.

Therefore, the GaN-based nitride 3 grown on the sapphire substrate gas-phase etched with HCl gas
The specularity of the surface of the Group 5 compound semiconductor depends on the off-angle of the sapphire substrate, and the GaN-based nitride grown when the off-angle is greater than 0 degree and the absolute value is 0.5 degree or less.
The surface roughness of the group III compound semiconductor is reduced, and a flat mirror surface state is obtained.

Next, other features of the present invention will be described. Another feature of the present invention is that in the vapor phase growth process of a nitride-based compound semiconductor doped with a p-type dopant by MOVPE, a specific gas of an inert gas containing substantially no hydrogen is used as a carrier gas, In the cooling step after the growth, supply of ammonia is performed at 1100 ° C. to 7 ° C.
The point is that it stops when a specific temperature of 00 ° C. is reached.

Here, examples of the inert gas include rare gases such as helium, argon and neon, and nitrogen. Among them, helium has a high kinematic viscosity coefficient and can be suitably used as the carrier gas of the present invention. Argon and nitrogen can be suitably used because they can be used in large quantities at low cost. These inert gases can be used alone or in any combination. As the inert gas substantially containing no hydrogen, for example, the above-mentioned inert gas having a hydrogen concentration of 0.5% by volume or less is used.

When the nitride-based compound semiconductor doped with a p-type dopant is vapor-phase grown by the MOVPE method, a group III raw material used is, for example, trimethylgallium [(CH ₃ ) ₃ Ga, hereinafter referred to as TMG. Sometimes. ], Triethyl gallium _{[(C 2 H 5) 3} Ga,
Hereinafter, it may be referred to as TEG. ] And other general formulas R ₁ R ₂ R
Trialkyl gallium represented by ₃ Ga (where R ₁ , R ₂ and R ₃ represent a lower alkyl group); trimethyl aluminum [(CH ₃ ) ₃ Al], triethyl aluminum [(C ₂ H ₅ ) ₃ Al, sometimes referred to as TEA hereinafter. ], Triisobutylaluminum [(i-C ₄
H ₉ ) ₃ Al], etc., wherein R ₁ R ₂ R ₃ Al (where
R ₁ , R ₂ and R ₃ represent a lower alkyl group. ); Trimethylamine alane [(CH ₃ ) ₃ N: AlH ₃ ]; trimethyl indium [(CH ₃ ) ₃ In, sometimes hereinafter referred to as “TMI”. ], Triethylindium [(C ₂ H ₅ ) ₃ In]
R ₁ R ₂ R ₃ In (where R ₁ , R ₂ , R
₃ represents a lower alkyl group. ) Trialkylindium, diethylindium chloride [(C ₂
H ₅ ) ₂ InCl] or other trialkyl indium in which one to three alkyl groups have been replaced with halogen atoms, or a general formula In such as indium chloride [InCl].
And indium halide represented by X (X is a halogen atom). These can also use two or more types.

As the Group 5 raw material, ammonia is used, but a Group 5 raw material other than ammonia may be used in combination. Examples of such group V raw materials include hydrazine, methylhydrazine, 1,1-dimethylhydrazine, 1,2-dimethylhydrazine, t-butylamine, ethylenediamine, and the like.

Further, it can be used as a p-type dopant.
Elements that can be cut include Group 2 elements, especially Be, Mg, C
a, Zn, Cd, a mixture of two or more of these, and the like.
It is. Of these, Mg is more preferred. here,
As a raw material of Mg, for example, biscyclopentadienyl
Magnesium ((C_FiveH_Five)_TwoMg), bismethylsic
Lopentadienyl magnesium ((C _FiveH_FourCH_Three)_Two
Mg), bisethylcyclopentadienyl magnesium
((C _FiveH_FourC_TwoH_Five)_TwoMg) and the like.

Further, an n-type dopant may be simultaneously doped with a p-type dopant. By simultaneously doping the n-type dopant and the p-type dopant, the activation rate of the p-type dopant may be further increased. Specific examples of the n-type dopant that can be doped simultaneously with the p-type dopant for this purpose include a Group 4 element or a 6-type dopant.
Group elements. In particular, Si and O can be suitably used. When an n-type dopant is used, the preferred n
The concentration of the p-type dopant is 5% or more of the p-type dopant concentration.
0% or less.

As a substrate for growing a nitride-based compound semiconductor, a gallium nitride-based compound semiconductor, sapphire, SiC, Si, ZrB2, or the like can be suitably used. When a nitride-based compound semiconductor is grown directly on these substrates, a crystal of sufficiently high quality may not be obtained due to lattice mismatch or the like. In such a case, GaN, Al
High quality crystals may be obtained by first growing a layer of N, SiC, etc. on a substrate as a buffer layer and then growing a nitride-based compound semiconductor. Therefore, the nitride-based compound semiconductor doped with the p-type dopant may be grown directly on the substrate or may be grown on the substrate via the buffer layer. Alternatively, it may be further laminated on a gallium nitride-based compound semiconductor grown on a substrate via a buffer layer.

By using the above raw materials,
A nitride-based compound semiconductor doped with a p-type dopant is grown by vapor phase. The growth condition is determined by a known method using an inert gas substantially containing no hydrogen as a carrier gas, for example, Japanese Patent Application Laid-Open No. H8-325094. Japanese Patent Publication No.

The concentration of the p-type impurity in the nitride-based compound semiconductor doped with the p-type dopant obtained by the vapor phase growth is preferably 5 × 10 ¹⁸ to 1 × 10 ²¹ cm ⁻³ . More preferably, 1 × 10 ^{19 to} 5 × 10 ²⁰ c
m ^-3 , more preferably 2 × 10 ¹⁹ to 2 × 10 ²⁰ cm ^-3
It is.

According to the present invention, after the nitride compound semiconductor doped with the p-type dopant is vapor-phase grown as described above, the supply of ammonia is performed at 1100 ° C. in the cooling step.
The operation is stopped when a specific temperature of up to 700 ° C. is reached. The preferred ammonia shutdown temperature is 1
000 ° C to 800 ° C. Here, if the supply of ammonia is continued even when the temperature becomes lower than 700 ° C., the p-type dopant in the compound semiconductor is inactivated, while 1100
Stopping when the temperature is higher than ° C. causes thermal degradation of the compound semiconductor.

In some cases, by mixing oxygen into the cooling atmosphere, the activation rate of the p-type dopant can be increased. When oxygen is mixed, it is 0.05 to 20% of the total gas supply amount.

(Example) Hereinafter, the p-type conversion will be described in detail with reference to examples, but the p-type conversion according to the present invention is not limited to the examples described below. An embodiment in which a light emitting diode crystal having a layer structure shown in FIG. 2 is manufactured on a sapphire substrate according to the present invention will be described.
On the (0001) plane of the sapphire substrate 11, hydrogen was used as a carrier gas, and ammonia, TM
G, using silane at 550 ° C. by MOVPE method
The N layer is grown as the low-temperature buffer layer 12 by about 50 nm. Then, the n-type GaN layer 13 doped with Si is
Grown at 40 ° C. to about 3 μm and further doped with non-doped Ga
The N layer 14 is grown to about 0.25 μm. After that, about 8
The temperature was lowered to 00 ° C., the carrier gas was nitrogen, and TEG, TMI, silane, and ammonia were
-Doped 25 nm GaN barrier layer 15 and 3 nm I
The multiple quantum well structure layer 17 is formed by repeatedly forming the nGaN quantum well layer 16 five times. Further, an Al _0.2 Ga _0.8 N layer 18 is formed on the multiple quantum well structure layer 17 by 25 nm.
Let it grow.

Next, with the carrier gas being nitrogen, 1
The temperature was raised to 040 ° C., and TMG and ammonia were used as source gases, bisethylcyclopentadienyl magnesium [(C ₂ H ₅ C ₅ H ₄ ) ₂ Mg as a p-type dopant source,
Hereinafter, it may be referred to as ECp ₂ Mg. Using Mg
Is grown to a thickness of 200 nm. This p-type nitride group 3-5 compound semiconductor
After the growth of the type GaN layer 19, heating of the substrate is stopped, and cooling is performed while flowing ammonia and a carrier gas. At this time, when the temperature of the sapphire substrate 11 reaches 900 ° C., the supply of ammonia is stopped, the sapphire substrate 11 is cooled to room temperature, and the sapphire substrate 11 on which the light emitting diode crystal is formed is taken out.

The p-type GaN layer 19 thus obtained can realize a high p-type carrier concentration without post-processing.
For the sample of the example, after removing a part of the p-type GaN layer 19 by etching to expose the n-type layer under the p-type GaN layer 19, electrodes are formed on the p-type GaN layer 19 and the surface of the exposed n-type layer, respectively. Thus, an element configuration as a light emitting diode can be obtained. This light emitting diode can emit light at a low driving voltage because the p-type GaN layer 19 has a sufficient p-type carrier concentration.

On the other hand, when the carrier gas is hydrogen and M
When a light emitting diode crystal having the same layer structure as that shown in FIG. 2 was produced in the same manner as in the above-described embodiment except that a g-doped GaN layer was grown, the p-type GaN layer 19 was formed.
The p-type carrier concentration is lower than that of the above embodiment, and light emission at a low driving voltage is not sufficient, and it is difficult to manufacture a high quality light emitting diode element.

[0068]

According to the present invention, as described above, by using a sapphire substrate having an absolute value of an off angle of 0.5 degrees or less, the surface of the group III-V compound semiconductor formed on the substrate can be made specular. Can be improved. Therefore, when a semiconductor functional device is manufactured by using this, a semiconductor element having excellent electric characteristics can be obtained. Furthermore, if the surface of the sapphire substrate is modified by etching, it is possible to manufacture a group 3-5 compound semiconductor surface with even more excellent mirror surface.

Further, in the vapor phase growth step of a nitride compound semiconductor doped with a p-type dopant, a specific gas called an inert gas substantially containing no hydrogen is used as a carrier gas, and a cooling step after the growth is performed. In the above, when the supply of ammonia is stopped when the temperature reaches a specific temperature, a nitride-based group III-V compound semiconductor exhibiting good p-type electric characteristics can be obtained. As a result, it is possible to realize a light emitting element having sufficient light emission intensity and good light emission efficiency at a low driving voltage.

[Brief description of the drawings]

FIG. 1 is a process explanatory view illustrating an example of an embodiment of the present invention.

FIG. 2 is a layer structure diagram for explaining another embodiment of the present invention.

FIG. 3 is a sectional view of a sapphire substrate used in one embodiment of the present invention.

FIG. 4 is a view showing a measurement result of a surface roughness of one example when a Group 3-5 compound semiconductor is manufactured using the sapphire substrate shown in FIG. 3;

5 is a graph showing the measurement data shown in FIG.

[Explanation of symbols]

Reference Signs List 1 sapphire substrate 2 buffer layer 3 GaN layer 4 epitaxial substrate 11 sapphire substrate 12 low-temperature buffer layer (GaN layer) 13 n-type GaN layer 14 GaN layer 15 GaN barrier layer 16 InGaN quantum well layer 17 multiple quantum well structure layer 18 Al _0.2 Ga _0.8 N layer 19 p-type GaN layer

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Yoshinobu Ono             6th Kitahara, Tsukuba, Ibaraki Prefecture Sumitomo Chemical Co., Ltd.             In the formula company F term (reference) 5F041 AA21 AA40 CA34 CA49 CA57                       CA65                 5F045 AA04 AB14 AB18 AC07 AC08                       AC09 AC12 AC19 AD08 AF09                       BB12 BB16 CA10 CA11 CA12                       HA03 HA22                 5F073 AA55 AA74 CA17 CB05 CB14                       DA05 DA12 EA29

Claims (13)

[Claims] 1. A general formula onto a substrate In _x Ga _y Al _z N
(However, x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1,
In a method for producing a Group 3-5 compound semiconductor by growing a Group 3-5 compound semiconductor represented by 0 ≦ z ≦ 1), the absolute value of the angle between the substrate surface and the C plane is set to 0. After preparing a substrate having a temperature of 5 degrees or less, the substrate surface of the substrate is subjected to vapor phase etching using a gas containing a halogen element in a molecule, and then a group 3-5 compound semiconductor is vapor-phase grown on the substrate surface. A method for producing a Group 3-5 compound semiconductor, comprising growing a crystal. 2. A general formula onto a substrate In _x Ga _y Al _z N
(However, x + y + z = 1, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1,
In a method for producing a Group 3-5 compound semiconductor by growing a Group 3-5 compound semiconductor represented by 0 ≦ z ≦ 1), the absolute value of the angle between the substrate surface and the C plane is set to 0. After preparing a substrate having a temperature of 5 degrees or less, the substrate surface of the substrate is subjected to gas phase etching using a gas containing a halogen element in a molecule, and then a buffer layer is laminated on the substrate surface of the substrate. A method for producing a Group 3-5 compound semiconductor, comprising growing a Group 3 compound semiconductor by a vapor phase growth method. 3. A gas containing a halogen element in a molecule is HC.
3. 3-5 according to claim 1 or 2,
A method for producing a group III compound semiconductor. 4. The method according to claim 1, wherein the substrate is sapphire. 5. The method for producing a Group 3-5 compound semiconductor according to claim 1, wherein said vapor phase growth method is a metal organic vapor phase growth method. 6. A Group 3-5 compound semiconductor obtained by the method according to claim 1, 2, 3, 4, or 5. Substantially using an inert gas not containing hydrogen as claimed in claim 7 carrier gas, by a metal organic chemical vapor deposition method using ammonia as a group V material, the general formula doped with a p-type dopant an In _x Ga _y Al _z N (0 ≦ x ≦ 1, 0 ≦
3 represented by y ≦ 1, 0 ≦ z ≦ 1, x + y + z = 1)
A method for producing a p-type group 3-5 compound semiconductor, comprising: stopping the supply of ammonia at a temperature in the range of 1100 ° C. to 700 ° C. in a cooling step after growing the group 5 compound semiconductor. 8. The method according to claim 7, wherein the hydrogen concentration in the inert gas containing substantially no hydrogen is 0.5% by volume or less. 9. The gas according to claim 7, wherein the inert gas is at least one selected from helium, argon, and nitrogen.
The manufacturing method as described. 10. The method according to claim 7, wherein the p-type dopant is Mg. 11. The temperature at which the supply of ammonia is stopped is 1
The method according to claim 7, 8, 9, or 10, wherein the temperature is in the range of 000 ° C to 800 ° C. 12. A compound semiconductor obtained by the method according to claim 7, 8, 9, 10 or 11. 13. A compound semiconductor device comprising the compound semiconductor according to claim 12.