JPH10178201A - Manufacture of semiconductor light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-luminance LED or LD by a method wherein, in a semiconductor light-emitting element, a light-emitting part and a layer for a substrate whose composition is expressed by a formula are laminated on a seed substrate in this order. SOLUTION: As a seed substrate, a substrate which is composed of various materials such as sapphire, SiC, MnO and the like can be used. A light-emitting part and a layer for the substrate are constituted of at least one kind out of various semiconductor compounds expressed by a formula of InXGaYAlZN (wherein 0<=X<=1, 0<=Y<=1, 0<=Z<=1, and X+Y+Z=1). As the shape of the light-emitting part, a homojunction structure, a heterostructure such as a single heterostructure, a double heterostructure or the like, a multiple quantum well structure, a single quantum well structure and the like are enumerated, but the double heterostructure is particularly preferable. The light- emitting part is composed of a multilayer of two or more layers. A first layer of it may be laminated directly on the seed substrate, a buffer layer which relaxes a lattice mismatch is first formed on the seed substrate as required, and the first layer may be laminated on it. The thickness of the layer for the substrate is set at about 10 to 1000μm, but it is set particularly preferably at about 50 to 300μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a GaN-based semiconductor light emitting device.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for a semiconductor device capable of emitting high-intensity blue light due to a demand for multicolor display in a light-emitting display and a demand for improving data density in communication and recording. Has been requested. As a material used for manufacturing a semiconductor element that emits blue light, a GaN-based compound has attracted attention. GaN-based compounds have a direct transition-type band structure, and can emit light with high efficiency.
Further, since it has a large band gap at room temperature, it is a material suitable for a blue light-emitting element capable of meeting the above requirements. However, since the GaN-based compound has a high melting point and a high vapor pressure of nitrogen near the melting point, it is extremely difficult to grow a bulk crystal from the melt. For this reason, the production of the GaN-based compound is performed on the sapphire substrate or on the sapphire substrate.
A buffer layer made of a material having good lattice matching with a GaN-based material such as 1N or ZnO is formed, and Ga
At present, a crystal thin film of an N-based compound is grown.

However, since the sapphire substrate is an insulator, the placement of the electrodes is limited to a specific position, and there is a problem that the degree of freedom in the structural design of the light emitting element is limited as described below. FIG. 1 shows a conventional L using GaN.
It is an example of a sectional structure figure of ED. In the figure, 1 is a p-side electrode, 2 is an n-side electrode, 4 is an n-type GaN-based semiconductor, and 6 is a p-type GaN-based semiconductor. The p-side electrode 1 and the n-side electrode 2
Since the sapphire substrate S is an insulator, the sapphire substrates S cannot be opposed to each other with the substrate interposed therebetween like an LED using a conductive substrate. Thus, as shown, both electrodes are
Both have to be provided on the same surface side of the sapphire substrate S. The structure for forming these electrodes has various problems in terms of manufacturing and mounting of the light emitting element, and is disadvantageous in terms of the light emitting area. Also, in the case of manufacturing a GaN-based LD, there is a problem similar to that of the LED at the electrode formation position, and there is a disadvantage that sapphire has no cleavage property, so that a resonator surface cannot be formed by cleavage.

[0004]

In view of the above, an object of the present invention is to solve the above-mentioned problems of the conventional GaN-based semiconductor light emitting device using a sapphire substrate, in particular, a small light emitting area and fabrication of a resonator surface by cleavage. G that the impossible problem was solved
An object of the present invention is to provide a method for manufacturing an aN-based semiconductor light emitting device.

[0005]

The present invention has the following features. (1) an In on a seed substrate _X Ga _Y Al _Z N (here 0 ≦ X
≦ 1, 0 ≦ Y ≦ 1, 0 ≦ Z ≦ 1, X + Y + Z = 1), a light emitting unit laminating step of stacking a light emitting unit, and In _X Ga _Y Al _Z N (where 0 ≦ X ≦ 1, 0 ≦ Y ≦
1. A method for manufacturing a semiconductor light emitting device, comprising: a substrate laminating step of forming a substrate layer consisting of 1, 0 ≦ Z ≦ 1, X + Y + Z = 1) and a seed substrate removing step of removing a seed substrate. (2) The method for manufacturing a semiconductor light-emitting device according to (1), wherein the n-layer of the light-emitting portion is stacked before the p-layer. (3) The production of the semiconductor light emitting device according to the above (1), wherein the buffer layer is composed of an oxide of an element of Group 2 of the periodic table, and the p layer of the light emitting section is stacked before the n layer. Method. (4) The method for manufacturing a semiconductor light emitting device according to any one of (1) to (3), wherein the seed substrate is made of sapphire or SiC.

[0006]

The light emitting portion and the substrate layer are made of In _X G having good conductivity.
a _Y Al _Z no lattice mismatch problem because it is constituted from N, can Thus laminated form crystalline good conductivity substrate layer on top of the light emitting portion. Next, when the seed substrate used first in the seed substrate removing step is removed, a GaN-based semiconductor light emitting device having the above-described conductive substrate is obtained.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Sapphire, S
iC, GaAs, Si, MgAl ₂ O ₄ , ZnO, Mn
Substrates made of various materials such as O, CaO, MgO, LiGaO ₃ and LiAlO ₃ can be used.

In the present invention, the light emitting portion and the substrate layer are both composed of at least one of various semiconductor compounds represented by the following general formula (1). Hereinafter, various semiconductor compounds represented by the general formula (1) are abbreviated as GaN-based compounds. In _X Ga _Y Al _Z N (1) (where 0 ≦ X ≦ 1, 0 ≦ Y ≦ 1, 0 ≦ Z ≦ 1, X + Y
+ Z = 1). Examples of GaN compounds include GaN, G
aAlN, InGaAlN and the like.

The light emitting portion may be formed in a homostructure, a heterostructure such as a single hetero or double hetero, a multiple quantum well structure (MQW), or a single quantum well structure (SQ).
W). Above all, a double hetero structure is particularly preferred. The constituent materials of each layer and the substrate layer included in the light emitting section may be the same or different from each other as long as they are GaN-based compounds.

In the light emitting section laminating step of the present invention, the light emitting section is stacked on the seed substrate. As described above, the light emitting unit
Usually, since it is composed of two or more layers, these layers are sequentially laminated, but the first layer may be directly laminated on the seed substrate if possible. A suitable buffer layer to mitigate the lattice mismatch may be provided first on the seed substrate and laminated thereon. From the second layer of the light emitting part to the lamination of the substrate layer, all layers have no problem of lattice mismatch with the already-formed layer, so they should be stacked on the already-formed layer without passing through a buffer layer etc. Can be.

There are no particular restrictions on the method of forming the buffer layer, each layer of the light emitting section, and the layer for the substrate. Examples of the method for growing the buffer layer include sputtering, MOCVD (organic metal vapor phase epitaxy), HVPE (hydride vapor phase epitaxy), MBE (molecular epitaxy), and P-CVD (plasma-chemistry). Vapor deposition). As a method of forming the layers of the light emitting section and the layer for the substrate, HVPE, MOCVD, M
The BE method can be exemplified, and the HVPE method is particularly preferable.

Sapphire, SiC, GaAs as seed substrate
In the case where s, Si, LiGaO ₃ , LiAlO _3, or the like is used, as a constituent material of the buffer layer, a conventionally well-known material, for example, oxides of Group II elements of the periodic table, AlN, G
Examples thereof include aN, AlGaN, and InGaN. Of these, Group 2 element oxides, which are easily removed by etching, from the seed substrate removing step described later are preferable. Examples of the Group 2 element oxides include ZnO, MgO, MnO, and Ca.
Oxides such as O, MgAlO, LiGaO ₃ , LiA
A complex or complex oxide such as 10 ₃ is shown. The thickness of the buffer layer is about 0.001 to 5 μm, particularly 0.01
About 0.5 μm.

When laminating the light-emitting portion, lamination may be started from either the p-type layer or the n-type layer on the seed substrate or the buffer layer. The order in which the mold layer is later is preferred. The reason is that the n-type layer is generally easier to form on the seed substrate than the p-type layer, and the p-type layer requires activation treatment such as heating or electron beam irradiation after forming the layer. This is because it is more convenient for the p-type layer to be outside in this processing. On the other hand, when the buffer layer is made of the above-described Group II element oxides, it is preferable that the p-type layer be the first and the n-type layer be the second. The reason is,
When an n-type layer is first grown on the buffer layer, the high temperature during the growth decomposes the oxide to release Group II atoms, which are mixed into the n-type layer to form a dopant in the same layer. This is because there is a problem that the amount of dopant in the n-type layer is reduced. On the other hand, if a p-type layer is first grown on the buffer layer, n
The mold layer is protected from the problem of incorporation of Group II atoms with the existing p-type layer acting as a defense. Moreover, the incorporation of Group II atoms into the p-type layer is at least harmless to the layer, and some Group II atoms, particularly Mg and Zn, are the main dopants in the p-type layer, so the contamination is welcomed. You. When a substrate layer is grown subsequent to the light-emitting portion, a method in which a p-type layer is grown first and an n-type layer is thereafter is preferable from the viewpoint that a thick film having good crystallinity can be obtained.

The p-type layer of the light emitting portion may be subjected to activation treatment by an ordinary method at any stage after the formation of all the light emitting portion layers, such as before and after a substrate laminating step and before and after a substrate removing step. In particular, it is preferable to perform it after the substrate removing step.

In the substrate laminating step, a substrate layer is formed on the uppermost layer of the light emitting section. The thickness of the substrate layer is set so that the layer can function as a substrate of the GaN-based semiconductor light-emitting device, which is the object to be manufactured according to the present invention, instead of the seed substrate. For example, about 10 to 1000 μm, particularly about 50 to 300 μm is suitable.

After the substrate laminating step, the seed substrate is removed.
The removal of the seed substrate is performed by an appropriate method such as erasing the seed substrate or separating the seed substrate from the first stacked layer of the light emitting portion. Examples of the erasing method include mechanical polishing with a diamond paste and etching with a chemical agent capable of dissolving a seed substrate. If a buffer layer, particularly a buffer layer made of the group II oxide, is interposed between the seed substrate and the light emitting part, the buffer layer is removed by chemical etching to separate the seed substrate from the light emitting part. This is preferable from the viewpoint of the removal efficiency, the cleanliness of the light emitting part surface after removal, the crystalline state, and the like. At this time, the removal of the buffer layer by etching can be performed by a method such as wet etching using an acid such as hydrochloric acid, nitric acid, sulfuric acid, or the like.

After the seed substrate is removed, electrodes are formed by a normal method on each of the surface of the GaN-based compound substrate that newly functions as a substrate and the surface of the light emitting portion exposed by removing the seed substrate. Thereby, a GaN-based LED can be manufactured. In addition, a GaN-based LD can be manufactured using a cleavage plane formed by cleaving a GaN-based compound substrate.

[0018]

The present invention will be described in more detail with reference to the following examples.

Example 1 An MgO film as a buffer layer was grown to a thickness of about 0.05 μm on a 2 inch φ sapphire C surface by sputtering. At this time, in order to reduce oxygen deficiency of MgO, oxygen gas was introduced in addition to ordinary argon gas introduction. Sapphire seed substrate having MgO film
The apparatus was set in an OCVD apparatus and heated to 500 ° C. while flowing nitrogen at 20 SLM. Next, ammonia 10SL
M, 10 SLM of hydrogen, and 10 SLM of nitrogen were flown therein, and 50 μmol / min of trimethylgallium and 1 μmol / min of cyclopentadienyl magnesium were flown therein to grow a p-GaN thin layer having a thickness of 0.1 μm. After this 10
The temperature was raised to 00 ° C., and the same flow rate was applied to the same material as above to grow a 1-μm-thick p-GaN cladding layer. Then, the temperature was lowered to 800 ° C. while flowing 10 SLM of ammonia and 10 SLM of nitrogen, and 25 μmol / min of trimethylgallium and 25 μmol / min of trimethylindium /
Then, an InGaN active layer having a thickness of 0.2 μm was grown. Next, 10SL of nitrogen and 10SL of ammonia
The temperature was raised to 1000 ° C. while flowing M and 50 μmol / min of trimethylgallium and 20 pp of silane (SiH ₄ ).
By flowing 5 cc of m, an n-GaN cladding layer having a thickness of 2 μm was grown. Then, the temperature was lowered to 700 ° C. while flowing 20 SLM of nitrogen, kept at 700 ° C. for 20 minutes, and p-
The GaN cladding layer was activated. Further, the sapphire seed substrate having the light-emitting portion is placed in a normal HVPE apparatus, and the temperature is increased to 800 ° C. while flowing 10 SLM of nitrogen and 10 SLM of ammonia, and the nitrogen and ammonia are continuously flowed at 800 ° C. Further hydrogen chloride 2
0 SCCM and 10 SCCM of silane are flowed to a thickness of 100
A μm layer for an n-GaN substrate was grown. The sapphire seed substrate having the light emitting portion and the substrate layer thus obtained was immersed in hydrochloric acid for 20 minutes to completely remove the MgO buffer layer, thereby separating the sapphire seed substrate from the GaN thin layer. Finally, a p-side electrode is placed on the GaN thin layer, while n is placed on the substrate layer.
The side electrodes were each formed in the usual way, thus producing a blue LED.

Example 2 A buffer layer of about 0.05 μm was used instead of the MgO film.
A blue LED was manufactured in the same manner as in Example 1 except that a thick ZnO film was grown on a sapphire seed substrate by a sputtering method.

Example 3 A wafer having both n-side and p-side electrodes prepared in Example 1 was cleaved along its a-plane to produce a blue LD. Since all the layers of the above wafer are formed of GaN,
Clean cleavage was achieved at high yield.

Example 4 The wafer having both n-side and p-side electrodes prepared in Example 2 was cleaved along its a-plane to produce a blue LD. Since all the layers of the above wafer are formed of GaN,
Clean cleavage was achieved at high yield.

Embodiment 5 The growth order of the p and n cladding layers is reversed from that of Embodiment 1, the n-GaN cladding layer is provided first, and then the p-GaN cladding layer is provided. The substrate was placed in a normal HVPE apparatus, the temperature was raised to 800 ° C. with 10 SLM of nitrogen and 10 SLM of ammonia flowing, and 20 SCCM of hydrogen chloride and cyclopentadiene were further added with nitrogen and ammonia flowing at 800 ° C. 1 μmol / min of enylmagnesium is flowed to a thickness of 10
A 0 μm p-GaN substrate layer is grown,
A blue LED was manufactured in the same manner as in Example 1 except that the heat treatment was performed at 20 ° C. for 20 minutes.

[0024]

According to the present invention, LEDs and LDs having a conductive GaN-based substrate can be manufactured. Since the substrate is conductive, both the p and n electrodes can be formed on the upper and lower surfaces of the substrate so as to face each other so that a current flows through the substrate. Thus, a high-brightness LED or LD can be obtained. Also, a high-performance LD can be easily manufactured by utilizing the cleavage property of the GaN-based substrate.

[Brief description of the drawings]

FIG. 1 is an example of a cross-sectional view of a conventional blue LED structure.

[Explanation of symbols]

 Reference Signs List 1 p-side electrode 2 n-side electrode 4 n-type GaN-based semiconductor 6 p-type GaN-based semiconductor S sapphire substrate

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuyuki Tadomo 4-3 Ikejiri, Itami-shi, Hyogo Mitsubishi Electric Cable Industry Co., Ltd. Itami Works

Claims (4)

[Claims] An In _X Ga on the 1. A seed substrate _Y Al _Z N (here 0 ≦ X ≦ 1,0 ≦ Y ≦ 1,0 ≦ Z ≦ 1, X + Y + Z
= 1-emitting portion laminating step the light emitting portion is laminated consisting _{of), In X Ga Y Al Z} N ( here 0 ≦ X ≦ 1 on the light emitting portion,
A substrate laminating step of forming a substrate layer consisting of 0 ≦ Y ≦ 1, 0 ≦ Z ≦ 1, X + Y + Z = 1), and a seed substrate removing step of removing a seed substrate. Production method. 2. The method according to claim 1, wherein the n-layer of the light-emitting section is stacked before the p-layer. 3. The semiconductor light-emitting device according to claim 1, wherein the buffer layer is made of an oxide of an element of Group 2 of the periodic table, and the p-layer of the light-emitting section is stacked before the n-layer. Production method. 4. The method for manufacturing a semiconductor light emitting device according to claim 1, wherein the seed substrate is made of sapphire or SiC.