JP2003179257A - Method of manufacturing gallium nitride compound semiconductor including indium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the content of indium and to improve crystal quality. <P>SOLUTION: The third layer 10 of the GaN layer of a single crystal is formed and a polycrystalline GaN layer 20' whose film thickness is 50 nm is formed at a temperature of 500°C. The temperature is raised to 1,080°C, and a second layer 20 obtained by keeping the temperature at 1,080°C for five minutes, thermally heating it and making the layer 20' into the single crystal is formed. The first layer 30 of the GaInN layer whose thickness is 50 nm is formed at 700°C. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a gallium nitride-based compound semiconductor containing indium, which is used as a material for a light emitting device.

[0002]

BACKGROUND OF THE INVENTION In general formula _{B x Al y Ga 1-xyz} In z N
The gallium nitride-based compound semiconductor described by (0 ≦ x ≦ 1,0 ≦ y ≦ 1,0 ≦ z ≦ 1) has attracted attention as an excellent material for a light emitting element that emits ultraviolet, blue, green, and yellow light. ing. Generally, a high-efficiency light emitting device has a laminated structure including at least a p-type gallium nitride compound semiconductor and an n-type gallium nitride compound semiconductor. Since the gallium nitride-based compound semiconductor has a wide band gap, it is also very useful as a material for an environment-resistant electron transit device. When a light emitting element is manufactured using a gallium nitride compound semiconductor, a gallium nitride compound semiconductor containing indium is used as a light emitting layer. The band gap of a gallium nitride-based compound semiconductor containing indium changes depending on the composition ratio of indium, and the emission wavelength can be changed from ultraviolet to visible light region. In general, a gallium nitride-based compound semiconductor containing indium has a relatively low equilibrium vapor pressure of indium nitride (InN). Therefore, the crystal growth temperature for containing indium is set to a gallium nitride-based compound semiconductor containing no indium. Need to be lower. However, when the crystal growth temperature is lowered, there is a problem that the crystal quality is deteriorated and the light emitting efficiency is lowered in the light emitting device.

[0003]

To grow a gallium nitride compound semiconductor containing indium, the crystal growth temperature is set lower than the temperature at which a gallium nitride compound semiconductor containing no indium is grown. The maximum content of indium is roughly determined by the crystal growth temperature, and is 900 ° C. or less in the metal organic chemical vapor deposition method (sometimes referred to as MOCVD method). On the other hand, for high-quality crystal growth of a gallium nitride-based compound semiconductor containing no indium, it is preferable that the temperature is 1000 ° C. or higher in the metal organic chemical vapor deposition method, for example. That is, it is desirable to increase the crystal growth temperature in order to improve the crystal quality, but there is a trade-off relationship that the crystal growth temperature must be decreased in order to increase the indium content.

In the case of a light emitting device, the influence of the crystal quality is not small, and if the crystal quality is poor, the luminous efficiency is deteriorated, and
It adversely affects the reliability and electrical characteristics of the device. Therefore,
An object of the present invention is to provide a method for producing a gallium nitride-based compound semiconductor containing indium, which can increase the content of indium and has high crystal quality of the gallium nitride-based compound semiconductor containing indium. is there.

[0005]

According to the present invention, B_x
Al_yGa_1-xyzIn_zN (0 ≦ x ≦ 1, 0 ≦ y ≦
Amorphous film on the third layer consisting of 1,0 <z ≦ 1)
Or polycrystalline B_xAl_yGa_1-xyzIn_zN (0
≦ x ≦ 1,0 ≦ y ≦ 1,0 ≦ z ≦ 1), and
Amorphous or polycrystalline form after heat treatment
B_xAl_yGa _1-xyzIn_zSingle crystal of N layer
As a second layer, B on the second layer_xAl _yGa
_1-xyzIn_zN (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦
A first layer consisting of 1) is formed.

As the first layer, B _x Al _y Ga _1-xyz
In _z N (0 ≦ x ≦ 1,0 ≦ y ≦ 1,0 <z ≦ 1) and B
_{x Al y Ga 1-xyz In} z N (0 ≦ x ≦ 1,0 ≦ y ≦
It may be a layer composed of 1,0 ≦ z ≦ 1).

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1A shows the steps of the manufacturing method of the present invention, and FIG. 1B shows the manufacturing state in each step, and FIG. 2 shows a schematic cross section of an example of the manufactured gallium nitride-based compound semiconductor. Formation of Third Layer First, the third layer 10
To form. The third layer 10 has the general formula B _x Al _y Ga
_{1-xy- z} In _z N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦
It is a gallium nitride semiconductor represented by 1). The third layer 10 is formed on the substrate by metalorganic vapor phase epitaxy, molecular beam epitaxy (sometimes referred to as MBE), hydride vapor phase epitaxy (HVPE), sublimation, liquid phase epitaxy, etc. grow up. Alternatively, B _x Al _y on the substrate by HVPE method
It is also possible to grow a thick film of Ga _{1 -xyz} In _z N and then remove the substrate to form the third layer 10 as a single crystal single substance. The addition of impurities to the third layer 10 does not matter. That is, the third layer 10 may be close to an intrinsic semiconductor. As the third layer 10, a commercially available gallium nitride compound semiconductor single crystal may be used.

[0008] Amorphous or polycrystalline form on the forming the third layer 10 of gallium nitride compound semiconductor layer of amorphous or polycrystalline form of the general formula _{B x Al y Ga 1-x-} yz In z N (0 ≦ x ≦ 1,0 ≦
A layer 20 of y ≦ 1, 0 ≦ z ≦ 1) is grown and formed. This layer is formed by metalorganic vapor phase epitaxy, molecular beam epitaxy,
Although it depends on a hydride vapor phase epitaxy method, a sublimation method, a liquid phase epitaxy method, etc., in order to obtain an amorphous or polycrystal state, the temperature is set to be much lower than a normal crystal growth temperature. For example, in the case of an organic metal or a vapor phase growth method, if the temperature is in a range higher than the decomposition temperature of the raw material, it can be made amorphous or polycrystalline by adjusting the crystal growth temperature and the crystal growth rate (volumetric velocity of the raw material gas). it can. Whether it is amorphous or polycrystalline can be confirmed by, for example, reflection high-energy electron diffraction (sometimes referred to as RHEED). Layer 20 '
Regarding the film thickness, the upper limit is 0.5 μm, and the lower limit is not particularly limited, but the film thickness is so thin that it is not thermally decomposed during the next heat treatment. If the film thickness is more than 0.5 μm, the subsequent heat treatment causes excessive unevenness, which may adversely affect the flatness of the film grown on the second layer 20. The addition of impurities to the layer 20 'does not matter. Heat treatment The amorphous or polycrystalline layer 20 'is heat treated to be single crystallized to form the second layer 20. Due to this single crystallization, the density of the layer 20 'becomes high, and the portions which are not single crystallized are elevated to form gaps, that is, the second layer 2 having irregularities.
Change to 0. The heat treatment temperature is preferably a normal crystal growth temperature or higher, but is not particularly limited as long as it is a temperature at which irregularities are formed. Specifically, it is preferably 800 ° C. or higher in the metal organic chemical vapor deposition method. The temperature holding time for heat treatment depends on the heat treatment temperature, but it is 1 minute or more 3
0 minutes or less is preferable. More preferably, it is 5 minutes or more and 10 minutes or less. If it is shorter than 1 minute, the unevenness may not be formed, and if it is longer than 30 minutes, the second layer 20 may be thermally decomposed and excessive unevenness may be formed, whereby the effect of the present invention may not be obtained. Formula B _x Al _y G containing indium on the first formation of the layer the second layer 20
a _1-xyz In _z N (0 ≦ x ≦ 1,0 ≦ y ≦ 1,0 <z
A first layer 30 of gallium nitride-based compound semiconductor represented by ≦ 1) is grown and formed. Also for the growth formation of the first layer 30, a metal organic vapor phase epitaxy method, a molecular beam epitaxy method, a hydride vapor phase epitaxy method, a sublimation method, a liquid phase epitaxy method, or the like can be used. The film thickness of the first layer 30 and the addition of impurities to the first layer 30 do not matter.

The first layer 30 may have a multi-layer structure. For example, as shown in FIG. 2, the general formula B _x Al _y Ga
_1-xyz In _z N (0 ≦ x ≦ 1,0 ≦ y ≦ 1,0 <z ≦
Formula B a gallium nitride-based compound semiconductor layer 32 containing indium consisting _{1) x Al y Ga 1-} xyz In z N
The structure is sandwiched by gallium nitride-based compound semiconductor layers 31 and 33 of (0 ≦ x ≦ 1,0 ≦ y ≦ 1,0 ≦ z ≦ 1). Generally, the general formula B _x Al _y Ga _1-xyz In
_{z N (0 ≦ x ≦ 1,0} ≦ y ≦ 1,0 <z ≦ 1) General and gallium nitride containing indium formed of a compound semiconductor layer 32 type _{B x Al y Ga 1-xyz} In z N (0 ≦ x ≦ 1,
It may be repeatedly laminated with the gallium nitride-based compound semiconductor layer 31 of 0 ≦ y ≦ 1, 0 ≦ z ≦ 1), and the lamination order and the number of laminations are not particularly limited.

When the first layer 30 is formed on the second layer 20 on which the unevenness is formed, the first layer 30 is formed in comparison with the case where the first layer 30 is formed on the second layer having no unevenness at the same growth temperature. The indium content of Embodiment An embodiment of the present invention will be described below with reference to FIGS. The following examples are based on the metal organic chemical vapor deposition method. The gas used is ammonia (NH ₃ ), hydrogen (H ₂ ) and nitrogen (N ₂ ) as carrier gases, trimethylgallium (TMG), trimethylindium (TM).
I), trimethyl aluminum (TMA), monosilane (SiH ₄ ), cyclopentadienyl magnesium (C
P ₂ Mg). Example 1 FIG. 4 shows a cross section of a semiconductor manufactured by the method of this example. Formation of Third Layer 10 The cleaned c-plane sapphire substrate 11 was placed in a reaction furnace, and the substrate was thermally cleaned at a substrate temperature of 1100 ° C. while flowing H ₂ . Substrate temperature is 500 ° C
And supply TMG and NH ₃ to form a 30 nm thick GaN film.
Layer 12 was deposited on the c-plane of sapphire substrate 11. Subsequently, the substrate temperature is set to 1080 ° C., TMG and NH ₃ are supplied to grow an undoped GaN layer 13 having a film thickness of 2 μm on the GaN layer 12 to form a _third substrate including the substrate 11, the GaN layer 12 and the GaN layer 13. Layer 10 was formed. The substrate temperature for forming the second layer was set to 500 ° C., TMG and NH ₃ were supplied, and a GaN layer 20 ′ having a film thickness of 50 nm was deposited on the third layer 10. Reflection high-energy electron diffraction (RHEED) of this layer 20 '
The pattern showed a ring pattern, and it was confirmed that the GaN layer 20 'was polycrystalline. Subsequently, the temperature was raised to 1080 ° C. while supplying NH ₃ , and heat treatment was performed for 5 minutes at 1080 ° C. to form the second layer 20. NH here
This is because, if ₃ is not supplied, the GaN layer may become a Ga layer or a GaN layer in which the N component is reduced. The substrate temperature for forming the first layer is set to 700 ° C., and TMG and TM are used as reaction gases.
I and NH ₃ were supplied to grow a first layer 30 of a GaInN layer having a thickness of 50 nm.

GaIn was formed by the photoluminescence method.
The peak wavelength, half width, and relative peak intensity of the light emitted from the N layer (first layer) 30 were measured. The smaller the half-value width, the better the crystallinity, and the higher the relative peak intensity, the better the crystallinity.
As a result, orange light emission having a peak wavelength of 580 nm, a half width of 80 nm and a relative peak intensity of 200 μV was obtained. [Example 2] The first GaInN layer was formed in the same manner as in Example 1 except that the growth substrate temperature of the first layer 30 was 760 ° C.
Layer 30 was grown. By photoluminescence method,
When the emission peak from the GaInN layer 30 was measured,
Green light emission having a peak wavelength of 520 nm, a half width of 40 nm and a relative peak intensity of 1000 μV was obtained. By increasing the growth substrate temperature of the first layer 30, the In content of the first layer 30 was decreased, and the peak wavelength was shortened. [Example 3] The deposition substrate temperature of the second layer 20 'was set to 350 ° C.
The first layer 30 of the GaInN layer was grown in the same manner as in Example 2 except for the above. The RHEED pattern of the second layer 20 'showed a halo pattern, confirming that the GaN layer 20' was amorphous.

GaIn was formed by the photoluminescence method.
When the emission peak from the first layer 30 of the N layer was measured, green emission having a peak wavelength of 520 nm, a half value width of 40 nm and a relative peak intensity of 1000 μV was obtained. [Comparative Example 1] The first layer 3 of the GaInN layer was formed in the same manner as in Example 1 except that the deposition and heat treatment of the second layer 20 'were omitted.
Grew to zero. By the photoluminescence method, GaI
When the emission peak from the nN layer was measured, the peak wavelength was 520 nm, the half width was 60 nm, and the relative peak intensity was 100 μ.
A green emission of V was obtained. First layer 30 as compared to Example 1
The wavelength is short because the In content of is small. Example 4 FIG. 5 shows a cross section of a semiconductor manufactured by the method of Example 4. Formation of Third Layer The cleaned c-plane sapphire substrate 11 was placed in a reaction furnace, and the substrate was thermally cleaned at a substrate temperature of 1100 ° C. while flowing H ₂ . Substrate temperature is 500 ° C
And supply TMG and NH ₃ to form a 30 nm thick GaN film.
Layer 12 was deposited on the c-plane of substrate 11. Subsequently, the substrate temperature is set to 1080 ° C., TMG and NH ₃ are supplied, and GaN is supplied.
An undoped GaN layer 13 having a film thickness of 2 μm was grown on the layer 12 to form a third layer 10 including the substrate 11, the GaN layer 12, and the GaN layer 13. The substrate temperature for forming the second layer 20 was set to 500 ° C., TMG and NH ₃ were supplied, and a GaN layer 20 ′ having a film thickness of 50 nm was deposited on the third layer 10. Subsequently, the temperature was raised to 1080 ° C. while supplying NH ₃ , and heat treatment was performed for 5 minutes at 1080 ° C. to form the second layer 20. The substrate temperature of the first layer is 700 ° C., N ₂ is used as a carrier gas, and TMG, TMI, and NH ₃ are supplied as reaction gases to form a well layer 32 of GaInN having a thickness of 3 nm as a second layer. 20 and then the supply amount of TMI is reduced to 1/6, and a mixed gas of N ₂ and H ₂ (N ₂ is used as a carrier gas).
₂ : H ₂ = 9: 1) and Ga _0.99 I with a film thickness of 10 nm.
A barrier layer 33 made of n _0.01 N was grown. This operation is repeated four times to form a first multiple quantum well layer of four periods.
Layer 30 was grown.

GaIn was formed by the photoluminescence method.
When the emission peak from the first layer 30 of the N layer was measured, orange emission having a peak wavelength of 580 nm, a half width of 70 nm and a relative peak intensity of 15000 μV was obtained. Although the wavelength was the same as in Example 1, the relative peak was remarkably large and the crystallinity was improved as compared with Example 1. [Example 5] Growth of first layer 30 A first layer 30 composed of a multi-quantum well layer having four periods was grown in the same manner as in Example 4 except that the substrate temperature was 760 ° C. When the emission peak from the first layer 30 of the GaInN layer was measured by the photoluminescence method, green emission having a peak wavelength of 520 nm, a half value width of 50 nm and a relative peak intensity of 20000 μV was obtained. [Example 6] A first layer 30 of a multi-quantum well layer having four periods was grown in the same manner as in Example 5 except that the substrate temperature for depositing the second layer was 350 ° C.

By the photoluminescence method, GaIn
When the emission peak from the N layer was measured, the peak wavelength was 5
20 nm, half width 50 nm, relative peak intensity 20000
A green light emission of μV was obtained. "Comparative Example 2" Since the deposition and heat treatment of the second layer 20 'are omitted.
Except for the above, as in the case of the fourth embodiment, the multi-quantum well layer of four periods is formed.
The first layer 30 was grown. According to the photoluminescence method
Measurement of the emission peak from the first layer 30 of the GaInN layer.
When determined, the peak wavelength is 520 nm and the half width is 60 n
m, a green light emission with a relative peak intensity of 10000 μV was obtained. Example 7 A semiconductor manufactured by the method of Example 7 was cut off.
The surface is shown in FIG. Formation of third layer Installed cleaned c-plane sapphire substrate 11 in reactor
And H₂Substrate temperature is set to 1100 ℃ while flowing
Was subjected to thermal cleaning. Substrate temperature is 500 ° C
And TMG, NH₃To supply GaN with a thickness of 30 nm
Layer 12 was deposited. Then, the substrate temperature is set to 1080 ° C.,
TMG, NH₃, SiH as n-type dopant gas_FourTo
Supply and supply Si 4 × 10¹⁸cm^-3Doped film thickness 4μm
N-type GaN layer 14 is grown to form the substrate 11 and the GaN layer.
12 and n-type GaN layer 14 to form a third layer 10
did. Formation of the second layer Substrate temperature is 500 ° C, TMG, NH₃, N-type dopa
SiH as gas _FourTo supply Ga with a film thickness of 50 nm
An N layer 20 'was deposited on the third layer 10. Then NH
₃Is heated to 1080 ° C. for 5 minutes 108
A second layer of n-type GaN is formed by holding at 0 ° C and heat treatment
did. Formation of the first layer The substrate temperature is 700 ° C., and N is used as a carrier gas.₂use
Used as reaction gas, TMG, TMI, NH₃Supply
To grow a GaInN well layer 32 with a thickness of 3 nm.
Then, reduce the TMI supply by 1/6, and
N as rear gas ₂And H₂Mixed gas (N₂: H₂= 9:
1) is used to form a Ga film having a thickness of 5 nm._0.99In_{0. 01} From N
The barrier layer 33 is grown. Repeat this operation 3 times
The multi-quantum well layer 34 having three cycles was grown.

Then, as a reaction gas at 1080 ° C., T
MG, TMA, NH ₃ , CP as p-type dopant gas
₂ Mg Was used to grow a p-type Al _0.15 Ga _0.85 N layer 35 with a film thickness of 50 nm doped with Mg at 5.0 × 10 ¹⁹ cm ⁻³ on the multiple quantum well layer 34. Then, TMG, NH ₃ as a reaction gas and CP ₂ Mg as a p-type dopant gas at 1080 ° C. Is used to grow a p-type GaN layer 36 having a film thickness of 100 nm doped with 1.0 × 10 ²⁰ cm ^{−3 of} Mg on the layer 35 to form a multi-quantum well layer 34, an AlGaN layer 35, and a GaN layer 36. Layer 1 of No. 1 was formed.

Next, a predetermined region is etched by a reactive ion etching device to expose the n-type GaN layer 14, that is, a part of the third layer 10. A light emitting diode (LED) device was manufactured by forming a p-electrode on the p-type GaN layer 36, that is, the first layer 30, and an n-electrode on the exposed n-type GaN layer 14 by photolithography. When the light emitting state of the device was observed, orange light emission having a wavelength of 580 nm was obtained. The comparative intensity measured by an optical power meter was 80 μW. "Embodiment 8" The growth temperature of the quantum well layer 34 for three cycles is set to 76.
An LED element was produced in the same manner as in Example 7 except that the temperature was 0 ° C.

Observation of the light emission state of the device revealed that the wavelength of 5
20 nm green emission was obtained. The comparative intensity measured by an optical power meter was 100 μW. [Example 9] An LED element was produced in the same manner as in Example 8 except that the deposition temperature of the second layer 20 'was 350 ° C. Observing the light emission of the device, wavelength 520nm
Green light emission was obtained. The comparative intensity measured by an optical power meter was 100 μW. "Comparative Example 3" An LED element was produced in the same manner as in Example 7 except that the deposition of the second layer 20 'and the heat treatment were omitted. When the light emission state of the device was observed, green light emission with a wavelength of 520 nm was obtained. The comparative intensity measured by an optical power meter was 40 μW.

The method of the present invention can be applied not only to the material of the light emitting device but also to a method of forming a gallium nitride compound semiconductor layer containing indium on a gallium nitride compound semiconductor in general.

[0019]

According to the present invention, since the growth substrate temperature can be raised in order to obtain the desired indium composition, the crystal quality of the gallium nitride-based compound semiconductor containing indium can be improved, and the device Can be improved in performance.

[Brief description of drawings]

FIG. 1A is a process diagram showing an embodiment of a manufacturing method of the present invention, and B is a diagram showing a manufacturing state in each process.

FIG. 2 is a schematic cross-sectional view of a semiconductor manufactured by an embodiment of the method of the present invention.

FIG. 3 is a schematic cross-sectional view of a semiconductor manufactured by another mode of the method of the present invention.

FIG. 4 is a schematic cross-sectional view of a semiconductor manufactured by the method of Example 1.

5 is a schematic cross-sectional view of a semiconductor manufactured by the method of Example 4. FIG.

FIG. 6 is a schematic cross-sectional view of a semiconductor manufactured by the method of Example 7.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takashi Egawa             Gokisho-cho (Showa-ku, Nagoya, Aichi Prefecture)             Shi) Inside Nagoya Institute of Technology (72) Inventor Takashi Jimbo             Gokisho-cho (Showa-ku, Nagoya, Aichi Prefecture)             Shi) Inside Nagoya Institute of Technology (72) Inventor Hisao Saiki             Two stocks at 1260, Ueho, Itonuki-cho, Motosu-gun, Gifu Prefecture             Ceremony Company Sanyo Denki Seisakusho Inuki Factory (72) Inventor Junichi Iwama             Two stocks at 1260, Ueho, Itonuki-cho, Motosu-gun, Gifu Prefecture             Ceremony Company Sanyo Denki Seisakusho Inuki Factory F-term (reference) 5F041 AA11 AA40 CA04 CA05 CA34                       CA40 CA73                 5F045 AA05 AB14 AB19 AC01 AC08                       AC12 AC15 AC19 AD07 AD11                       AD14 AF09 HA16

Claims (3)

[Claims] 1. A step of forming an amorphous or polycrystalline layer of gallium nitride-based compound semiconductor on a third layer made of a single crystal of gallium nitride-based compound semiconductor, and a step of heat-treating the amorphous or polycrystalline layer to form a single layer. A step of crystallizing to form a second layer, a step of forming a first layer of a single crystal of a gallium nitride compound semiconductor containing indium on the second layer, and a step of forming a gallium nitride containing indium Manufacturing method of compound semiconductor. 2. The method for producing a gallium nitride-based compound semiconductor containing indium according to claim 1, wherein the heat treatment is performed at 800 ° C. or higher, and the thickness of the second layer is set to 0.5 μm or less. 3. A gallium nitride-based compound semiconductor B _x Al _y Ga _{1 -xyz} I containing indium as the first layer.
_{n z N (0 ≦ x ≦} 1,0 ≦ y ≦ 1,0 <z ≦ 1) layer and the gallium nitride-based compound _{semiconductor, B x Al y Ga 1-} xyz
The multilayer structure of one cycle or more is formed with a layer of In _z N (0 ≦ x ≦ 1,0 ≦ y ≦ 1,0 ≦ z ≦ 1), and indium is contained according to claim 1. Method of manufacturing gallium nitride compound semiconductor.