JP2001223387A - Manufacturing method of iii nitride compound semiconductor light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide element isolation of a III nitride compound semiconductor light-emitting element, electrode formation, and manufacture of an end-surface reflection mirror with no use of etching technology to a III nitride compound semiconductor where etching is difficult to be performed. SOLUTION: There are provided a first process where a dielectrics film is formed in a pattern on a light-emitting element board or on a substrate where a III nitride semiconductor film is formed on its surface, a second process where a III nitride compound semiconductor film is grown selectively in a region of the III nitride semiconductor film except for the dielectrics film, and a third process where a multilayer structure is formed which comprises at least a III nitride semiconductor light-emitting layer and a p-type III nitride compound semiconductor layer on the III nitride compound semiconductor film. Here, multilayer structure is thinner than the dielectrics film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode using a thin film laminated structure containing a group III nitride compound semiconductor.
The present invention relates to a method for manufacturing a group III nitride compound semiconductor light emitting device such as a semiconductor laser (hereinafter referred to as an LED).

[0002]

2. Description of the Related Art Conventionally, blue light emitting devices have been II-VI
Studies have been made using group ZnSe, group IV-IV SiC, group III-V GaN, etc.
Group III nitride-based compound semiconductors have been shown to emit light at high efficiency at room temperature, and have been receiving attention.

[0003] As described above, despite the expectation of a device using a group III nitride-based compound semiconductor that emits light with high efficiency, the major cause of the failure to make progress in the research is the group III nitride nitride. That there is no suitable substrate material having the same lattice constant or thermal expansion coefficient for growing the compound semiconductor layer.

In recent years, organometallic compound chemical vapor deposition (M
A method of growing a group III nitride compound semiconductor layer on a sapphire substrate by an OCVD method has been reported.
That is, a buffer layer such as GaN or AlN as a group III nitride compound semiconductor layer is grown on a sapphire substrate at a relatively low temperature, and GaN is grown on the buffer layer. It has been reported that the non-doped GaN epilayer has a remarkably improved and low background carrier concentration and good electrical characteristics. In addition, the thus formed Ga with good crystallinity is formed.
Adding Mg as a p-type impurity to N or AlGaN,
It has been reported that a low-resistance P-type layer can be obtained by performing electron beam irradiation or heat treatment.

With the progress of these crystal growth techniques and valence electron control techniques, blue LEDs using a double heterostructure using AlGaN and InGaN exceed 1 (cd) and have a SiC
A device that is about 100 times brighter than a conventional device commercialized as a blue LED using a LED has been developed.

As described above, a GaN-based compound semiconductor has been used to develop a blue LED having a sufficient luminosity, which can withstand outdoor use, and has been developed for a full-color display combined with red and green LEDs. Expectations for applications are growing.

FIG. 11 shows the structure of a blue LED using a GaN-based compound semiconductor currently manufactured.

In FIG. 11, a GaN buffer layer 3, an n-type GaN growth layer 4, an n-type A
lGaN cladding layer 5, InGaN light emitting layer 6, p-type Al
A GaN cladding layer 7 and a p-type GaN contact layer 8 are sequentially grown. A p-side electrode 10 is formed on the p-type GaN contact layer 8, and both ends of each growth layer up to the middle of the n-type GaN growth layer 4 are etched to form an n-type Ga
An n-side electrode 13 is formed on the N growth layer 4. From the above,
A blue LED using a GaN-based compound semiconductor is formed.

As described above, since the GaN-based compound semiconductor grows on the sapphire substrate 11 which is an insulator,
In order to form the p-side or n-side electrodes 10 and 13 of the LED, it is necessary to form both electrodes 10 and 13 from the surface side of the growth layer. It is necessary to etch and remove each growth layer halfway through the type GaN growth layer 4. In addition, when the LED is divided into individual chips, damages are caused by the InGaN light emitting layer 6.
In order not to affect the active layer, it is necessary to etch the joint end face.

As described above, the etching technique is indispensable when manufacturing a light emitting device or an electronic element using a GaN-based compound semiconductor. If a short-wavelength semiconductor laser from the blue to the ultraviolet region can be realized, great application development is expected in the future multimedia era, for example, by increasing the storage capacity of an optical disk.
In order to realize such a semiconductor laser, it is necessary to form a resonator structure in the device. In a semiconductor laser using a GaAs group III-V semiconductor, the GaAs crystal used for the substrate has a cleavage plane along a specific crystal plane. Thus, a vertical cavity reflecting mirror can be easily formed. However, the sapphire substrate generally used in the growth of GaN-based compound semiconductors has the above-mentioned G
Since there is no cleavage plane such as an aAs crystal, it is necessary to form a mirror having a mirror surface perpendicular to the substrate by a method such as etching in order to manufacture a semiconductor laser.

[0011]

Although the above-mentioned etching technique is very important, the etching is very difficult because the group III nitride compound semiconductor is a very chemically stable material. It is known. Although there is a report on wet etching of GaN using phosphoric acid or the like, it is very difficult to etch a specific shape with a good controllability by this wet etching method.
The production of ED has been a practical problem in terms of yield, reliability, and the like.

In recent years, there have been reports on the etching of group III nitride compound semiconductors by dry etching such as reactive ion etching (RIE) using a chlorine-based gas. However, these are not yet well-established technologies, and in particular, at present, it is not possible to obtain a vertical mirror surface used for a reflection mirror of a semiconductor laser. This is one of the major reasons why light emitting devices such as semiconductor lasers using Group III nitride compound semiconductors that emit light with high efficiency have been expected, but have not yet been realized. Was.

A technique for forming electrodes and separating elements without using such an etching technique is disclosed in Japanese Patent Application Laid-Open No. 56-15 / 1981.
No. 0880 discloses a device using a conductive polycrystalline gallium nitride thin film formed on an insulating thin film.

However, in this method shown in FIG. 12, the single-crystal GaN growth layer 4 provided on the sapphire substrate 11
On the side of the polycrystalline conductive thin film 5 formed on alumina
1 can be applied only to the MIS type light emitting element, and has recently been developed for a pn junction or DH.
In the case of a high-brightness LED having a structure, this conductive thin film comes into contact with the pn junction interface, and its adaptation was impossible.

On the other hand, as a method of selectively forming a GaN thin film, a sapphire substrate partially covered with SiO _x is deposited on a sapphire substrate.
What can be achieved by growing GaN through the 1N buffer layer (Hiroshi Amano: Nagoya University doctoral dissertation, 1)
989). Also, a pn junction type LED is manufactured by selectively growing a p-type GaN growth layer on an n-type GaN growth layer (substrate is sapphire) partially covered with SiO _2. Reported in document EFM-90-23 p.57).

However, there is no mention of obtaining a vertical mirror such as that used for an end face mirror of a semiconductor laser, and these methods cannot be realized.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems. It is an object of the present invention to provide a method for separating a group III nitride-based compound semiconductor light emitting device without using an etching technique for a group III nitride-based compound semiconductor which is difficult to etch. It is an object of the present invention to provide a method of manufacturing a group III nitride compound semiconductor light emitting device capable of forming an electrode and manufacturing an end face reflection mirror.

[0018]

According to the present invention, there is provided a group III nitride compound semiconductor light emitting device comprising a dielectric film formed on a substrate or a substrate having a group III nitride compound semiconductor film formed on a surface thereof. A first step of forming a pattern;
A second step of selectively growing a group III nitride-based compound semiconductor film in a region of the group III nitride-based compound semiconductor film other than the dielectric film; and forming at least a group III nitride on the group III nitride-based compound semiconductor film. A third step of forming a multilayer structure including a compound-based compound semiconductor light-emitting layer and a p-type group III nitride-based compound semiconductor layer, the method comprising the steps of: The thickness is smaller than the thickness of the dielectric film, thereby achieving the above object.

The operation of the above configuration will be described below.

The device forming technique of the present invention is used for growing a group III nitride-based compound semiconductor by a vapor phase growth method or a molecular beam epitaxy method or the like. When a dielectric thin film is preliminarily formed in a pattern on a substrate on which a nitride-based compound semiconductor has been grown, a group III nitride-based compound semiconductor single crystal thin film does not grow on this dielectric thin film, and This is based on the fact that a group III nitride-based compound semiconductor thin film grows only on a non-existing substrate.

The present inventors have applied such a selective growth technique to, for example, use a substrate on which a relatively thick dielectric thin film has been partially formed in advance, and apply a method to a region having no dielectric thin film.
By growing a layer thinner than the dielectric thin film of the group III nitride compound semiconductor, the interface between this dielectric thin film and the group III nitride compound semiconductor thin film is electrically inactive and very stable. It was found that a perfect interface was formed. Such a stable interface can be used as it is as a separation layer at the time of element isolation.

It is a relatively easy technique to obtain a vertical mirror surface in the cross section of the dielectric thin film. However, by using this vertical mirror dielectric thin film for selective growth, the dielectric thin film and the group III nitride It has also been found that a vertical mirror surface applicable to a reflection mirror of a light emitting device such as a semiconductor laser can be obtained at an interface with a compound semiconductor growth layer. By using this vertical mirror surface, a light emitting device such as a group III nitride compound semiconductor laser, which has not been realized conventionally, can be realized for the first time.

Therefore, in the present invention, it is possible to separate a group III nitride compound semiconductor device, form an electrode, and manufacture an end face reflection mirror without using an etching technique for a group III nitride compound semiconductor which is difficult to etch. As a result, the reliability of these devices can be greatly improved, and the manufacturing process can be simplified. Therefore, the practical use of these devices will be advanced.

[0024]

Embodiments of the present invention will be described below. Note that the group III nitride-based compound semiconductor described below is (Al _x Ga _{1 -x} ) _y In _{1 -y} N (0 ≦ x ≦ 1,
It shows a compound semiconductor represented by 0 ≦ y ≦ 1).

(First Embodiment) In this embodiment,
This is a case where a blue LED is manufactured by forming an AlGaN / InGaN double heterostructure on a SiC substrate, and a group III nitride-based compound semiconductor thin film is grown by metal organic chemical vapor deposition (MOCVD). It is. FIG. 1 is a sectional view showing the structure of a group III nitride compound semiconductor blue LED according to the first embodiment of the present invention.

In FIG. 1, a case is formed on a 6H-SiC substrate 1.
SiO as a dielectric thin film_TwoFilm 2 is about 4 μm thick
Provided with SiO_TwoOn the 6H-SiC substrate 1 in the lattice of the film 2
A group III nitride-based compound semiconductor thin film having a thickness of about 2
GaN buffer layer 3 of 0 nm, n-type with a thickness of about 2.5 μm
GaN growth layer 4, about 200 nm thick n-type Al_0.lGa_0
.9N clad layer 5, 50 nm thick In_0.06Ga_0.94N
Emitting layer 6, Al having a thickness of about 200 nm_0.lGa_0.9N crush
Layer 7, and a GaN contact layer 8 having a thickness of 300 nm.
Are sequentially provided. Thus, the group III nitride compound
Semiconductor thin film is made of SiO_TwoIt can be selectively grown in the lattice of the film 2
Ri SiO_TwoNo film grows on the film 2 and SiO 2 _TwoLattice of membrane 2
3.25 μm II only on the 6H-SiC substrate 1
Double hetero-stacked structure using group I nitride compound semiconductor
Is configured.

Further, on the back surface of the 6H-SiC substrate 1, n
An ohmic electrode 9 is provided as a side electrode, and a GaN layer 8 is provided.
An ohmic electrode 10 as a p-side electrode is provided thereon. As described above, the blue LED according to the present embodiment is configured.

This blue LED can be manufactured as follows.

First, after surface polishing, the surface is oxidized.
6 of the n-type (0001) Si surface from which the damaged layer on the surface has been removed
H-SiC substrate 1 is used to form S
iO _TwoThe film 2 is formed. This SiO_TwoThe thickness of the film 2 is about 4 μ
m.

Next, by a conventional photolithography in the SiO ₂ film 2, SiO ₂ of 250μm as shown in FIG. 2
A region 21 without the film 2 and a SiO ₂ layer (region leaving the SiO ₂ film 2) 22 patterned in a grid pattern with a width of 50 μm
To form Buffered hydrofluoric acid was used for etching the SiO ₂ film 2. The 6H-SiC substrate 1 on which the pattern of the SiO ₂ layer 22 was formed was set in a reactor of a MOCVD apparatus, and after sufficiently replacing the reactor with hydrogen, the temperature was increased to 110 ° C. while flowing hydrogen, and held for 20 minutes. 6H-of the region 21 without the SiO ₂ film 2
The surface of the SiC substrate 1 is cleaned.

Thereafter, the temperature is lowered to 500 ° C., and in addition to hydrogen, 5 liters of ammonia (NH ₃ ) per minute and 3 × 10 ^{-5 of} trimethylgallium (hereinafter referred to as TMG) per minute are added.
The GaN buffer layer 3 is grown to a thickness of about 20 nm by holding the film for 3 minutes while flowing in a molar flow. Thereafter, the flow of TMG is stopped and the temperature is increased to 1050 ° C. When the temperature stabilizes at 1050 ° C., TMG and silane (SiH
₄ ) at a flow rate of 0.3 cc / min, and about 2.5
A μm n-type GaN growth layer 4 is grown.

Subsequently, these NH3, TMG and trimethylaluminum (hereinafter referred to as TMA) were added at 6 × 10 ^-6 per minute.
A mole of silane (SiH ₄ ) is flowed at 0.3 cc per minute, and an n-type Al _0.1 Ga _0.9 N clad layer 5 of about 200 nm is grown by film growth for 5 minutes. The electron concentration of this cladding layer is 2 × 10 ¹⁸ cm ⁻³ .

Further, these TMG, TMA, SiH ₄
Is stopped and the temperature is lowered to 800 ° C. When the temperature is stabilized at 800 ° C., TMG and trimethylindium (hereinafter referred to as TMI) are flowed at 8 × 10 ^-5 mol / min, and diethyl zinc (hereinafter referred to as DEZ) at 1 × 10 ^-8 mol / min. The In _0.06 Ga _0.94 N light emitting layer 6 is grown. Zn forms a deep acceptor level in the In _0.06 Ga _0.94 N light emitting layer 6, and becomes an active light emitting layer having the acceptor level as a light emitting center. The emission peak wavelength at room temperature from this active light emitting layer is about 450 nm.

Further, these TMD, TMI, DEZ
Is stopped and the temperature is raised again to 1050 ° C.
When the temperature is stabilized at 1050 ° C., TMG, TMA and biscyclopentadienyl (Cp ₂ Mg) are added at 5 × 10 5 / min.
^-6 mol, and about 200 nm of Al _0.1
A Ga _0.9 N cladding layer 7 is grown. Then, TMA
Is stopped, magnesium is added, and a GaN contact layer 8 of 300 nm is grown by film growth for 7.5 minutes.

By the above-described film growth of each layer, as shown in FIG.
Sea urchin_Two6H-SiC substrate 1 in region 21 without film 2
On top of 3.25 μm group III nitride compound semiconductor
Thus, a double hetero laminated structure can be formed. With this film growth
Is a lattice-shaped SiO that can be selectively grown._TwoOn layer 22
The film does not grow. The wafer obtained in this way is
And heat treatment in a nitrogen atmosphere at 700 ° C for 20 minutes.
By performing the treatment, the magnesium-added Al_0.l
Ga_0.9N cladding layer 7 and GaN contact layer 8
Reduce the resistance to p-type. With this treatment, the hole concentration in both layers is
About 1 × 10¹⁸cm ^-3It became.

By polishing the back surface of the n-type 6H-SiC substrate 1 to remove growth deposits on the back surface of the substrate,
n-side electrode 9 of ohmic electrode on n-type 6H-SiC substrate 1
Nickel is partially formed, and gold (Au) is formed by vacuum evaporation as the p-side electrode 10 of the ohmic electrode on the p-type GaN contact layer 8 to form an LED chip wafer as shown in FIG. Is done. Finally, in order to divide the LED into individual chips, dicing is performed from the lattice-shaped SiO ₂ layer 22 having no group III nitride-based compound semiconductor growth layer to divide the elements.

In the LED chip obtained as described above, the group III nitride compound semiconductor growth layer and the SiO ₂
A stable interface is formed between the layer 22 and -5V
Leakage current at an applied voltage of 1 nA or less, and DC
The light output was reduced by 30% or less even in the reliability test using the 20 mA drive and in 10,000 hours.

(Second Embodiment) In this embodiment,
A blue LED is manufactured by fabricating a double heterostructure of AlGaN / InGaN on the SiC substrate 1. What is different from the first embodiment is the SiO 2 used for selective growth.
_{2 This is a case where the} film 2 has a thickness of 0.4 μm and is thinner than the total thickness of the group III nitride compound semiconductor layer to be grown.

FIG. 4 shows a second embodiment of the present invention.
It is sectional drawing which shows the structure of a group III nitride compound semiconductor blue LED.

In FIG. 4, on a 6H-SiC substrate 1,
SiO ₂ as a dielectric thin film similar to that of the first embodiment
Using a substrate obtained by patterning the film 2 in a lattice pattern, a group III nitride-based compound semiconductor thin film is formed by a metal organic chemical vapor deposition method (MOCVD method) in exactly the same procedure as in the first embodiment. Grew. In the present embodiment, the group III nitride-based compound semiconductor thin film layer is grown thicker than the lattice-patterned SiO ₂ layer.
In a region larger than the film thickness of the O ₂ layer, the film grows slightly slightly.

In the LED chip obtained as described above, the leakage current at an applied voltage of -5 V is 1 nA.
The light output was reduced by 30% or less even in the reliability test using the DC 20 mA drive in 10,000 hours.

Further, in this LED, since both ends of the active light-emitting layer are not perfectly parallel but have an oblique angle, the resonator structure is formed despite the flat end face being formed. Not done. This makes it possible to form a superluminescent LED in which only the emission intensity increases in a stable LED mode without oscillation even if the injection current is increased. Therefore, it is advantageous to use the LED obtained in this embodiment at a high driving current by pulse driving.

(Third Embodiment) In the present embodiment,
This is a case in which a blue LED is manufactured by manufacturing a double heterostructure of AlGaN / InGaN on a sapphire substrate in which the surface state and crystallinity of the growth layer are significantly improved, and which is manufactured by metalorganic chemical vapor deposition (MOCVD). This is a case where a group III nitride compound semiconductor thin film is grown.

FIG. 5 shows a third embodiment of the present invention.
It is sectional drawing which shows the structure of a group III nitride compound semiconductor blue LED.

In FIG. 5, on a sapphire substrate 11
As a group III nitride compound semiconductor thin film, a GaN buffer layer 3, an n-type GaN growth layer 4, an n-type AlGaN cladding layer 5, an InGaN light-emitting layer 6, a p-type AlGaN cladding layer 7, and a p-type GaN contact layer 8 are sequentially provided. ing.
Si is contacted with both end faces of the InGaN light emitting layer 6.
_{A 3} N ₄ film 12 is provided, and an electrode layer 13 is provided on the sapphire substrate 11 so as to be in contact with both end surfaces of the n-type GaN growth layer 4. Blue LE as above
D is configured.

This blue LED can be manufactured as follows.

First, a spatter is placed on a sapphire C-plane substrate 11.
SiO as a dielectric pair film by the _TwoFilm 2, further Si_Three
N_FourThe film 12 is formed continuously. This SiO_TwoFilm thickness of film 2
Is 2 μm, Si_ThreeN_FourThe thickness of the film 12 was 2 μm. Next
The case shown in FIG.
It is formed in a child pattern. Here, a width of 200 μm
Si_ThreeN_Four/ SiO_TwoRegion 31 without
Width Si_ThreeN_Four/ SiO_TwoLattice pattern area (Si
O_TwoFilm 2 / Si_ThreeN_Four(Region leaving film 12) 32
Was. This Si_ThreeN_FourUse phosphoric acid to etch film 12
And also SiO_TwoBuffered for etching of film 2
Hydrofluoric acid was used. This Si_ThreeN_Four/ SiO_TwoThe grid of pa
The sapphire substrate 11 having the turn regions 32 formed thereon is
Set it in the reactor of the VD device,
After replacing well with hydrogen, the temperature is reduced to 1 while flowing ammonia.
Raise to 100 ° C. and hold for 20 minutes,_ThreeN_Four/ S
iO_TwoOf the surface of the sapphire substrate 11 in the region 31 without
An oxide film is formed.

Thereafter, the temperature was lowered to 500 ° C., and the GaN buffer layer 3 was maintained for about 1 minute while flowing 5 liters of ammonia (NH ₃ ) per minute and 3 × 10 ^-5 mol of trimethylgallium (TMG) per minute. It is grown to a thickness of 20 nm. Subsequent film growth is performed in exactly the same manner as in the first embodiment, so that the same n-type GaN growth layers 4 and n as in FIG.
Growth layers of the p-type AlGaN cladding layer 5, the InGaN light emitting layer 6, the p-type AlGaN cladding layer 7, and the p-type GaN contact layer 8 are obtained in this order. Since the sapphire substrate 11 is insulative, the ohmic electrode 1
3 also needs to be formed from the upper surface side of the substrate. The process of forming the ohmic electrode 13 will be described below.

As shown in FIG. 7, the Si ₃ N ₄ film 12 is partially etched. At this time, the active light-emitting layer InG
The part of the Si ₃ N ₄ film 12 in contact with the aN light emitting layer 6 is about 20 μm.
It is left as a protective layer having a width of m. The lower SiO ₂
The film 2 is entirely removed by wet etching using buffered hydrofluoric acid, and the n-type GaN growth layer 4 is
Aluminum is formed as an n-side electrode 13 of an ohmic electrode by vacuum evaporation. Further, gold (Au) is formed as a p-side electrode 10 of an ohmic electrode on the p-type GaN layer 8 by vacuum deposition, whereby the LED wafer shown in FIG. 5 is formed. Finally, in order to divide the LED into individual chips, dicing is performed on the aluminum electrode layer 13 to complete all the steps.

In the LED chip obtained as described above, the group III nitride based compound semiconductor growth layer and the Si ₃ N ₄
A stable interface is formed with the layer, the leakage current at an applied voltage of −5 V is 1 nA or less, and DC 2
The light output was reduced by 30% or less even in the reliability test using the 0 mA drive and in 10,000 hours.

(Fourth Embodiment) In this embodiment, the S
This is a case where an AlGaN / GaN double heterostructure is formed on an iC substrate to produce an ultraviolet LD, and a group III nitride-based compound semiconductor thin film is grown by metal organic chemical vapor deposition (MOCVD). It is.

FIG. 8A is a sectional view showing the structure of a group III nitride compound semiconductor ultraviolet LD according to a fourth embodiment of the present invention, and FIG. 8B is a plan view thereof.

8A and 8B, 6H-Si
On a C substrate 1, a GaN buffer layer 3, an n-type GaN growth layer 4, an n-type A
lGaN cladding layer 5, GaN light emitting layer 61, p-type AlG
An aN cladding layer 7 and a p-type GaN contact layer 8 are sequentially provided. An SiO ₂ layer 22 having a lattice pattern of an SiO ₂ film 2 as a dielectric layer is provided so as to be in contact with both end faces of the group III nitride compound semiconductor layer. An Al ₂ O ₃ film 14 is provided on the p-type GaN contact layer 8 and the SiO ₂ layer 22 as a protective film. A p-side electrode 15 made of an Au / Ni laminated film is provided on the Al ₂ O ₃ film 14, and the p-side electrode 15 made of the Au / Ni laminated film is a stripe formed on the Al ₂ O ₃ film 14. Directly contact the GaN contact layer 8 through the gate electrode. On the back surface of the 6H-SiC substrate 1, an n-side electrode 9 of an ohmic electrode is provided on the entire surface. The ultraviolet LD is configured as described above.

This ultraviolet LD can be manufactured as follows.

First, a 6H-SiC substrate 1 which was turned off by 5 degrees in the <1120> direction from the n-type (0001) C plane from which the damaged layer was removed by oxidation treatment after surface polishing was used, and 6H-SiC was formed by sputtering. SiO on the substrate 1
_{2 A} film 2 is formed. The thickness of this SiO ₂ film 2 was about 4 μm.

Next, the same pattern as that shown in FIG. 2 is formed on the SiO ₂ film 2 by ordinary photolithography. As shown in FIG. 2, a region 21 having no 250 μm SiO ₂ film 2 and a SiO ₂ layer 2 having a grid pattern having a width of 50 μm.
Form 2 In the LD fabrication according to the present embodiment, the interface between the group III nitride compound semiconductor layer formed by selective growth and the SiO ₂ layer 22 is used as a reflection mirror. is important. The direction of the etched surface of the dielectric layer such as SiO ₂ from the results of various experiments study on selective growth III
It has been found that a layer having the most flat interface between the group III nitride compound semiconductor layer and the dielectric layer in the (1100) direction, which is one side of the hexagonal crystal which is the crystal form of the group nitride compound semiconductor crystal, is obtained. . Therefore, here, the etched surface of the SiO ₂ film 2 was obtained in parallel with the (110) direction of the 6H-SiC substrate 1. The SiO ₂ film 2 was etched by RIE using CF ₄ gas to obtain an SiO ₂ etched surface having excellent perpendicularity. This SiO ₂ film 2
6H formed with a SiO ₂ layer 22 which is a lattice pattern of
Sets -SiC substrate 1 to the reactor of the MOCVD apparatus, after replacing well the reactor with hydrogen, the temperature was raised to 1300 ° C. under a stream of hydrogen and maintained for 20 minutes, 6H of the SiO ₂ film 2 without areas 21 -SiC substrate 1
Clean the surface.

Thereafter, the temperature was lowered to 500 ° C., and the GaN buffer layer 3 was maintained for about 3 minutes while flowing 5 liters of ammonia (NH ₃ ) per minute and 3 × 10 ^-5 mol of trimethylgallium (TMG) per minute. It is grown to a thickness of 20 nm. Further, the flow of TMG is stopped and the temperature is increased to 1050.
Increase to ° C. When the temperature stabilizes at 1050 ° C, TM
G, NH ₃ , and silane (SiH ₄ ) were flowed at 0.3 cc per minute,
An n-type GaN growth layer 4 of about 2.5 μm is grown by film growth for one hour.

Subsequently, in addition to NH ₃ and TMG, trimethylaluminum (TMA) was flowed at a rate of 6 × 10 ^-6 mol / min, and silane (SiH ₄ ) was flowed at a rate of 0.3 cc / min. An Al _0.15 Ga _0.85 N clad layer 5 is grown. The electron concentration of this cladding layer 5 is 2 × 10 ¹⁸ cm
It is ^-3 .

Further, the flow of NH ₃ and SiH ₄ is stopped.
The GaN light emitting layer 61 having a thickness of 50 nm is grown by performing the film growth for one minute. This non-doped GaN light emitting layer 6 becomes an active layer of the LD. The oscillation wavelength at room temperature is about 366 nm.

Further, TMA and Cp ₂ Mg were added at a rate of 5
A p-type Al _0.15 Ga _0.85 N cladding layer 7 of about 1 μm is grown by flowing the film at a ^{rate of} × 10 ^-6 mol for 25 minutes. Subsequently, the flow of TMA is stopped, and the film is grown for 7.5 minutes for 300 minutes.
A GaN contact layer 8 of nm is grown.

As shown in FIG.
On the 6H-SiC substrate 1 in the region 21 where the iO ₂ film 2 is not formed, a double hetero laminated structure made of a group III nitride-based compound semiconductor having a total of 4.85 μm can be formed. In this film growth, the group III nitride compound semiconductor can be selectively grown on the region 21 where the SiO ₂ film 2 is not provided, and the group III nitride compound semiconductor film is formed on the SiO ₂ layer 22 having a lattice pattern. Does not grow. The wafer thus obtained is taken out of the apparatus and subjected to a heat treatment at a temperature of 700 ° C. for 20 minutes in a nitrogen atmosphere to thereby obtain a magnesium-added Al.
_The resistance of the _0.15 Ga _0.85 N cladding layer 7 and the GaN contact layer 8 is reduced to a p-type. This treatment resulted in a hole concentration of about 1 × 10 ¹⁸ cm ^{−3 in} both layers.

Further, Al ₂ was used as a protective film on the epi layer.
An O ₃ film 14 is formed by electron beam evaporation and has a width of 3 μm.
Is formed as an electrode, and an Au / Ni laminated film 15 is formed so as to directly contact the GaN contact layer 8 via the stripe. Furthermore, (110
0) In order to use the interface between the SiO ₂ film 2 formed along the direction and the group III nitride compound semiconductor laminated film as a reflection mirror, the SiO ₂ layer 22 in this portion is removed by etching leaving a width of 20 μm. I do. Further, after the growth deposits on the back surface of the 6H-SiC substrate 1 are polished and removed, Ni is vapor-deposited on the entire surface of the substrate as the n-side electrode 9 of the ohmic electrode, whereby the semiconductor laser device shown in FIG. 8 can be formed.

When a current was passed through the semiconductor laser device thus formed, it was found to be 80 mA (about 1 × 10 ⁴ A / m ^2).
Laser current in the ultraviolet region of 366 nm was observed at a current density of 366 nm. As a comparative example, when the reflection mirror was formed by etching using the same wafer without using the selective growth method, laser oscillation was not observed even when a larger current was applied. It is considered that the favorable formation of the reflection mirror by the selective growth as described above is the cause of the achievement of laser oscillation.

Therefore, by using a substrate in which a relatively thick dielectric thin film is partially formed in a lattice pattern in advance, a region having no dielectric thin film has a layer thickness greater than that of a group III nitride compound semiconductor dielectric thin film. By growing a thin layer of
An electrically stable and very stable interface is formed at the interface between the dielectric thin film and the group III nitride compound semiconductor thin film. Such a stable interface can be used as it is as a separation layer at the time of element isolation. It is a relatively easy technique to obtain a vertical mirror surface in the cross section of the dielectric thin film. However, by using this vertical mirror dielectric thin film during selective growth, the dielectric thin film and the group III nitride compound can be obtained. A vertical mirror surface applicable to the reflection mirror of the light emitting element is obtained at the interface with the semiconductor growth layer.

As described above, according to the present embodiment, it becomes possible to perform element isolation, electrode formation, and fabrication of an end face mirror of a group III nitride compound semiconductor element without using an etching technique. The reliability can be greatly improved, and the manufacturing process can be simplified, so that the practical use of these devices is advanced.

(Fifth Embodiment) In the present embodiment,
This is a case of a blue-violet LD in which a double heterostructure of AlGaN / InGaN is formed on a sapphire substrate 11, and a case where a group III nitride-based compound semiconductor thin film is grown by metal organic chemical vapor deposition (MOCVD). .

FIG. 9A is a sectional view showing the structure of a group III nitride compound semiconductor blue-violet LD according to a fifth embodiment of the present invention, and FIG. 9B is a plan view thereof.

9A and 9B, a group III nitride compound semiconductor thin film is provided on a sapphire substrate 11, and an n-side electrode is formed on an n-type GaN growth layer 4 below the group III nitride compound semiconductor thin film. 13 are provided. An Al ₂ O ₃ film 14 is provided as a protective film on the GaN contact layer 8 above the group III nitride compound semiconductor thin film. The p-side electrode 10 is provided on the Al ₂ O ₃ film 14, and the p-side electrode 10 is in direct contact with the GaN contact layer 8 via the stripe of the Al ₂ O ₃ film 14. A blue-violet LD is formed as described above.

This blue-violet LD can be manufactured as follows.

First, the (0001) plane sapphire substrate 1
1 was set in the reactor of the MOCVD apparatus, and after sufficiently replacing the reactor with hydrogen, the temperature was increased to 1200 ° C. while flowing ammonia and hydrogen, and held for 10 minutes.
The surface of the sapphire substrate 11 is nitrided.

Thereafter, the temperature was lowered to 500 ° C., and 5 minutes of ammonia (NH ₃ ) and 3 × 10 ^{-5 of} trimethylgallium (TMG) were flowed per minute and held for 3 minutes to hold the GaN buffer layer 3 at about 3 minutes. It is grown to a thickness of 20 nm. Further, the flow of TMG is stopped and the temperature is increased to 1050 ° C. When the temperature stabilizes at 1050 ° C, TM
In addition to G, silane (SiH ₄ ) is flowed at 0.3 cc / min, and an n-type GaN growth layer 4 of about 2.5 μm is grown by 1 hour of film growth.

Thereafter, the n-type GaN growth layer 4 is
The grown sapphire substrate 11 is taken out of the MOCVD apparatus, introduced into a sputtering apparatus, and a 1.5 μm-thick SiO ₂ film 2 is formed by a sputtering method. This Si
The thickness of the O ₂ film 2 of 1.5 μm is larger than the total thickness of the subsequently grown group III nitride compound semiconductor multilayer film.

Next, as shown in FIG. 2, a region 21 without the SiO ₂ film 2 having a width of 250 μm and a SiO ₂ film having a grid pattern having a width of 50 μm are formed on the SiO ₂ film 2 by RIE.
_{The two} layers 22 are formed. In this case, the etched section of the SiO ₂ film 2 could be formed at 90 ° ± 1 ° with respect to the substrate surface.

The sapphire substrate 11 on which the n-type GaN growth layer 4 on which the SiO ₂ layer 22 is formed in a lattice pattern is grown to a thickness of 2.5 μm is introduced again into the reactor of the MOCVD apparatus, and the reactor is sufficiently replaced with hydrogen. NH ₃ , T
MG, trimethylaluminum (TMA) at 6 × 1 per minute
0 ^-6 mol, silane (SiH ₄₎ was flowed min 0.3 cc,
After growing the film for 12 minutes, about 500 nm of n-type Al _0.1 Ga _0.9
The N cladding layer 5 is grown. The electron concentration of the cladding layer 5 is 2 × 10 ¹⁸ cm ⁻³ .

Further, these TMG, TMA, SiH ₄
Is stopped and the temperature is lowered to 800 ° C. When the temperature is stabilized at 800 ° C., 4 × 10 ⁻⁴ mol of TMG and trimethylindium (TMI) are flowed per minute, and a 10 nm In _0.25 Ga _0.75 N light emitting layer 6 is grown by film growth for 12 seconds. The emission peak wavelength at room temperature from the light emitting layer 6 is about 432 nm. Further, the flow of TMG and TMI is stopped, and the temperature is raised again to 1050 ° C. When the temperature is stabilized at 1050 ° C., 5 × 10 ^-6 mol per minute is flowed, and Al _{0.1 having} a thickness of about 500 nm is grown by film growth for 12 minutes.
A Ga _0.9 N cladding layer 7 is grown. Then, TMA
Is stopped, magnesium is added, and a GaN contact layer 8 of 300 nm is grown by film growth for 7.5 minutes.

[0076] By the above Group III nitride compound semiconductor thin film growth, the region with no SiO ₂ film 2 as shown in FIG. 10 2
On the n-type GaN growth layer 4, a double hetero-stacked structure made of a group III nitride compound semiconductor having a total of 1.31 μm can be grown. In this film growth, selective growth is possible, and a group III nitride-based compound semiconductor film does not grow on the SiO ₂ layer 22 having a lattice pattern. The wafer thus obtained is taken out of the apparatus, and placed in a nitrogen atmosphere.
By performing a heat treatment at 0 ° C. for 20 minutes, the Al _0.1 Ga _0.9 N clad layer 7 _containing magnesium and the Ga
The resistance of the N contact layer 8 is reduced to a p-type. As a result of this treatment, the hole concentration of both layers became about 1 × 10 ¹⁸ cm ⁻³ .

Thereafter, the buffered hydrofluoric acid is used to remove SiO 2
After removing the _two layers 22, aluminum is formed by vacuum evaporation as the n-side electrode 13 of the ohmic electrode on the n-type GaN growth layer 4, and then Al _{2 is} formed on the p-type GaN contact layer 8 as a protective film. An O ₃ film 14 is formed by electron beam evaporation to form an electrode stripe structure having a width of 3 μm, and the p-side electrode 10 of the ohmic electrode to the p-type GaN contact layer 8 is formed.
Gold (Au) is formed by vacuum evaporation, and an LD wafer as shown in FIG. 10 is formed. Finally, LD
Is divided into individual chips to dice a portion of the n-side electrode 13 made of aluminum or a portion of the n-type GaN growth layer 4. The group III nitride-based compound semiconductor layer after the removal of the SiO ₂ film 22 becomes a reflection mirror as it is, so that the semiconductor laser device shown in FIG. 9A and FIG.
It can be formed without etching the group III nitride compound semiconductor layer. When a current was applied to this semiconductor laser device, laser oscillation was observed at a current of 70 mA. Its oscillation wavelength is about 432 nm.

Accordingly, the SiO ₂ film 2 as a dielectric film formed in advance on the substrate 1 and patterned in a lattice pattern
As a result, by selectively growing the group III nitride-based compound semiconductor layer, element isolation, electrode formation, and end face reflection mirror can be formed on the group III nitride-based compound semiconductor layer without using an etching technique.

[0079]

As described above, according to the present invention, by using a group III nitride-based compound semiconductor growth by selective growth, a light-emitting element can be obtained without using an etching technique for a group III nitride-based compound semiconductor. Element separation in electronic elements,
An electrode can be formed, and a highly reliable light-emitting element with high yield can be obtained.

Further, since a vertical mirror surface required for a semiconductor laser device can be obtained without using an etching technique for a group III nitride compound semiconductor which is difficult to etch, a group III nitride compound semiconductor which has not been realized conventionally can be obtained. A short-wavelength semiconductor laser using a compound semiconductor can be put to practical use.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a structure of a group III nitride compound semiconductor blue LED according to a first embodiment of the present invention.

FIGS. 2A and 2B are diagrams illustrating a process of patterning a dielectric film of the blue LED of FIG. 1, wherein a is a cross-sectional view and b is a plan view thereof.

FIG. 3 is a cross-sectional view showing one manufacturing process of the blue LED wafer of FIG.

FIG. 4 is a cross-sectional view showing a structure of a group III nitride compound semiconductor blue LED according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a structure of a group III nitride compound semiconductor blue LED according to a third embodiment of the present invention.

FIGS. 6A and 6B are views showing a step of patterning the dielectric film of the blue LED of FIG. 5, wherein a is a cross-sectional view and b is a plan view.

FIG. 7 is a cross-sectional view showing one manufacturing step of the blue LED wafer of FIG. 5;

FIG. 8A is a sectional view showing a structure of a group III nitride compound semiconductor ultraviolet LD according to a fourth embodiment of the present invention, and FIG.
Is a plan view thereof.

FIG. 9A is a cross-sectional view showing a structure of a group III nitride compound semiconductor blue-violet LD according to a fifth embodiment of the present invention;
b is a plan view thereof.

10 is a cross-sectional view showing one manufacturing step of the blue-violet LD in FIG.

FIG. 11 is a cross-sectional view showing the structure of a conventional group III nitride compound semiconductor DH blue LED.

FIG. 12 is a cross-sectional view showing a structure of a conventional group III nitride compound semiconductor MIS blue LED.

[Explanation of symbols]

Reference Signs List 1 n-type SiC substrate 2 SiO ₂ film 3 GaN buffer layer 4 n-type GaN growth layer 5 n-type AlGaN cladding layer 6 InGaN light emitting layer 7 p-type AlGaN cladding layer 8 p-type GaN contact layer 9 n-side electrode 10 p-side electrode 11 Sapphire substrate 12 Si ₃ N ₄ film 13 n-side electrode 14 Al ₂ O ₃ film 15 P-side electrode 21 area where SiO ₂ film 2 is removed 22 area where SiO ₂ film 2 is left (SiO ₂ layer) 31 SiO ₂ film 2 / A region where the Si ₃ N ₄ film 12 is removed 32 SiO ₂ film 2 / A region where the Si ₃ N ₄ film 12 is left 61 GaN light emitting layer

Claims (1)

[Claims] A first step of forming a dielectric film in a pattern on a substrate or on a substrate having a group III nitride-based compound semiconductor film formed on a surface thereof; A second step of selectively growing a group III nitride-based compound semiconductor film in a region of the film other than the dielectric film; and forming at least I on the group III nitride-based compound semiconductor film.
A third step of forming a multilayer structure including a group II nitride-based compound semiconductor light emitting layer and a p-type group III nitride-based compound semiconductor layer, the method comprising the steps of: A method of manufacturing a group III nitride compound semiconductor light emitting device, wherein the thickness of the multilayer structure is smaller than the thickness of the dielectric film.