JP2003273014A - Aluminum oxide evaporated sapphire single-crystal substrate and semiconductor light-emitting device substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum oxide evaporated sapphire single-crystal substrate, where a superior gallium nitride film can be formed, and to provide a semiconductor light-emitting device substrate. <P>SOLUTION: An amorphous aluminum film 3 is evaporated on the surface of a sapphire single-crystal substrate 2, and when the sapphire single-crystal substrate 2 where the evaporated film 3 is formed is thermally treated, the amorphous evaporated film 3 is turned into a single crystal. A proper gallium nitride layer 5, which is hardly affected by flaws 2a in the surface of the sapphire single crystal substrate 2 is formed thereon. <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 sapphire substrate for a semiconductor light emitting device and a substrate for a semiconductor light emitting device. Gallium nitride film (GaN film)
The present invention relates to a sapphire single crystal substrate and a substrate for a semiconductor light emitting device capable of forming a film.

[0002]

2. Description of the Related Art A sapphire single crystal substrate is a single crystal lump grown mainly by the HM method (heat exchange method), the Cz method (Czochralski method), or the like so that its end face becomes a C plane. It is manufactured by processing into a cylindrical shape having a diameter, cutting along the end face, and polishing the substrate.

[0003]

However, as shown in FIG.
As shown in (a), scratches 21a are easily formed on the polished surface of the sapphire single crystal substrate 21, and when gallium nitride 22 is epitaxially grown on the surface of the sapphire single crystal substrate 21, as shown in FIG. As shown in (4), there is a problem that the gallium nitride 22a abnormally grows due to scratches on the polished surface and becomes polycrystalline or the smoothness of the gallium nitride surface cannot be maintained.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an aluminum oxide vapor-deposited sapphire single crystal substrate and a semiconductor light emitting device capable of forming a good gallium nitride film (GaN film). A substrate for use is provided.

[0005]

[Means for Solving the Problems] As a result of earnest research for solving the above problems, as a result, an amorphous aluminum oxide vapor-deposited film was formed on the surface of a sapphire single crystal substrate, and after heat treatment, the aluminum oxide vapor-deposited film was formed on the vapor-deposited aluminum oxide film. Gallium nitride film (GaN
It was found that a good gallium nitride layer which is not affected by scratches on the surface of the sapphire single crystal substrate grows when the film is formed.

As a result of further research by the present inventor, when aluminum oxide was vapor-deposited at a high temperature during the vapor deposition of aluminum oxide, the aluminum oxide was polycrystallized and the gallium nitride layer was formed on the sapphire single crystal substrate. We found that abnormal growth is likely to occur reflecting surface scratches.
On the other hand, when non-single-crystallized amorphous aluminum oxide is vapor-deposited and then the sapphire single-crystal substrate on which the amorphous vapor-deposited film is formed is heat-treated, the amorphous vapor-deposited film is formed. It was found that a good gallium nitride layer that grows into a single crystal and is not affected by scratches on the surface of the sapphire single crystal substrate grows.

The invention according to claim 1 completed based on the above findings is an aluminum oxide vapor-deposited sapphire single crystal substrate in which a vapor-deposited film of amorphous aluminum oxide is formed on the surface of the sapphire single crystal substrate.

The amorphous aluminum oxide vapor deposition method (method of forming a vapor deposition film) is a vacuum vapor deposition method, a sputtering method, an ion plating method, a chemical vapor deposition method (a CVD method) under the condition that a single crystal is not formed. ). Any method such as the sol-gel method may be used.

According to the second aspect of the present invention, the vapor-deposited film of amorphous aluminum oxide formed on the surface of the sapphire single crystal substrate is heat-treated in an atmosphere selected from the atmosphere, oxygen and nitrogen. It is an aluminum oxide vapor-deposited sapphire single crystal substrate characterized by being subsequently single crystallized.

According to a third aspect of the present invention, the vapor deposition film of amorphous aluminum oxide formed on the surface of the sapphire single crystal substrate is subjected to heat treatment in a nitrogen atmosphere, and then single crystallized and single crystallized. The aluminum oxide single-crystal sapphire single-crystal substrate is characterized in that a single-crystal layer of aluminum nitride is formed on the surface of the vapor-deposited aluminum oxide film.

According to a fourth aspect of the present invention, in addition to the configuration of the first aspect of the present invention, the vapor deposition film of aluminum oxide is formed to have a thickness of 1 nm or more and 1 μm or less. It is an aluminum oxide vapor-deposited sapphire single crystal substrate.

The thickness of the vapor deposition film of aluminum oxide is 1 nm
The above is because when it is less than 1 nm, it is not possible to cover the scratch on the surface of the sapphire single crystal substrate and it is impossible to grow a good gallium nitride layer. Also,
The thickness of the deposited film is set to 1 μm or less because if it exceeds 1 μm, the deposited film is polycrystallized during the heat treatment and a good gallium nitride layer cannot be grown.

The thickness of the vapor deposition film of aluminum oxide is preferably 10 nm or more and 100 nm or less. This is because if it is within this range, the vapor deposition film is likely to be single-crystallized by the heat treatment.

A fifth aspect of the present invention is characterized in that a gallium nitride film is formed on the single crystallized aluminum oxide vapor-deposited sapphire single crystal substrate according to any of the second to fourth aspects. It is a substrate for a semiconductor light emitting element.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIG. 1 (b), a semiconductor light emitting device substrate 4 according to an embodiment of the present invention has a sapphire single crystal substrate 2 on which a single crystallized aluminum oxide vapor deposition film 3 is formed. And the gallium nitride film 5 is formed on the surface of the vapor-deposited film 3 of aluminum oxide.

As described above, the single crystallized vapor deposition film 3 is formed between the sapphire single crystal substrate 2 and the gallium nitride film 5 without forming the gallium nitride film 5 directly on the surface of the sapphire single crystal substrate 2. By doing so, it is possible to obtain a good semiconductor light emitting device substrate 4 that does not affect the scratches (including latent scratches) 2a existing on the surface of the sapphire single crystal substrate 2.

Next, the manufacturing process of the semiconductor light emitting device substrate 4 will be described.

<Polishing Step> For example, the surface of the sapphire single crystal substrate 2 manufactured by the EFG method is polished to smooth the surface of the sapphire single crystal substrate 2.

<Evaporation Step> Next, as shown in FIG. 1 (a), aluminum oxide is vapor-deposited at a low temperature on the C surface, which is the surface of the sapphire single crystal substrate 2 smoothed by polishing, to make it amorphous. A deposited film 3 of high quality aluminum oxide is formed.
Here, the vapor deposition method may be performed by any method such as vacuum vapor deposition method, sputtering method, ion plating method, chemical vapor deposition method (CVD method), and sol-gel method, as long as it is not a single crystal. .

The film thickness of the vapor deposition film 3 of aluminum oxide is formed within the range of 1 nm or more and 1 μm or less. This is because if the thickness of the deposited film 3 is less than 1 nm, the scratches (including latent scratches) 2a on the surface of the sapphire single crystal substrate 2 cannot be covered and a good gallium nitride layer cannot be grown. Because. Further, when the film thickness of the vapor deposition film 3 exceeds 1 μm, the vapor deposition film 3 is polycrystallized during the heat treatment described later, and the good gallium nitride film 5 cannot be grown.

The deposited film 3 of aluminum oxide is 1
It is preferably formed in the range of 0 nm to 100 nm. This is because if it is within this range, the vapor-deposited film 3 is likely to be single-crystallized by a heat treatment described later.

By the above vapor deposition process, the vapor deposition film 3 of amorphous aluminum oxide is formed on the surface of the sapphire single crystal substrate 2, so that the aluminum oxide vapor deposited sapphire single crystal substrate 1 is obtained.

<Heat Treatment Step> Next, the aluminum oxide vapor deposition sapphire single crystal substrate 1 on which the amorphous aluminum oxide vapor deposition film 3 is formed is heat treated to single crystallize the amorphous aluminum oxide vapor deposition film 3. Let This heat treatment is performed in an atmosphere selected from the atmosphere, oxygen and nitrogen. As described above, by single-crystallizing the amorphous vapor-deposited film 3, the aluminum oxide vapor-deposited sapphire single crystal substrate 1 on which the single-crystallized aluminum oxide vapor-deposited film 3 is formed can be obtained.

<Epitaxial growth step> Next, referring to FIG.
As shown in (b), metal organic chemical vapor deposition (MOCVD method)
The aluminum oxide vapor deposition sapphire single crystal substrate 1 on which the vapor deposited film 3 of single crystallized aluminum oxide is formed by
Gallium nitride is epitaxially grown on the surface of the deposited film 3 of FIG.

Through the above steps, the gallium nitride film 5 is
Since the growth is performed without being affected by scratches (including latent scratches) 2a existing on the surface of the sapphire single crystal substrate 2, the smoothness of the surface of the gallium nitride film 5 is improved. This makes it possible to obtain a good semiconductor light emitting device substrate 4 in which the surface smoothness of the gallium nitride film 5 is improved.

In this embodiment, the case where the vapor deposition film 3 is formed on the C surface of the sapphire single crystal substrate 2 has been described.
The present invention is not limited to this, and the vapor deposition film 3 may be formed on the a-face and other faces.

When the above heat treatment process is performed in a nitrogen atmosphere, as shown in FIG. 2 (a), the surface of the single crystallized aluminum oxide vapor deposition film 3 is formed on the aluminum oxide vapor deposition sapphire single crystal substrate 6. A single crystal layer 7 of aluminum nitride that has been single crystallized is formed. Then, as shown in FIG. 2B, gallium nitride is epitaxially grown on the surface of the single crystal layer 7 of single-crystallized aluminum nitride to obtain the semiconductor light emitting device substrate 8.

[0028]

EXAMPLES Example 1 A vapor deposition film of amorphous aluminum oxide was formed on the C-plane of a sapphire single crystal substrate having a thickness of 2 inches and a thickness of 500 μm by the ion plating method.
The film thickness of this vapor deposition film was formed to about 50 nm. As a result of examining this vapor-deposited film by X-ray diffraction and electron diffraction,
The vapor deposition film was amorphous. Next, regarding the substrate on which this amorphous aluminum oxide is deposited,
Heat treatment was performed for 30 minutes in an atmosphere of 000 ° C. to promote crystallization of the amorphous vapor-deposited film and promote single crystallization. Then, gallium nitride was epitaxially grown on the aluminum oxide vapor-deposited sapphire single crystal substrate by a metal organic chemical vapor deposition method (MOCVD method) to obtain a semiconductor light emitting device substrate.

A gallium nitride film was observed with a confocal microscope on this semiconductor light emitting device substrate.
No abnormal growth due to the wound was found. As a result of examining the boundary between the sapphire single crystal substrate and the gallium nitride layer by electron diffraction, no amorphous layer of aluminum oxide was observed. Further, a cross-section material was prepared and observed with a transmission electron microscope (TEM) and a lattice image was observed, but an amorphous layer could not be confirmed. From this, it was confirmed that the vapor-deposited film produced was aligned with the sapphire single crystal substrate by heat treatment to be single crystallized.

Example 2 The same substrate as that of Example 1 on which amorphous aluminum oxide was vapor-deposited was heat-treated in a vacuum atmosphere at 600 ° C. for 120 minutes, and the obtained substrate for semiconductor light emitting device was used in Example. When the same observation as in Example 1 was carried out, no abnormal growth due to scratches was found as in Example 1.

Example 3 The same substrate as that of Example 1 on which amorphous aluminum oxide was deposited was heat-treated in a nitrogen atmosphere at 600 ° C. for 120 minutes, and the obtained substrate for semiconductor light emitting device was used as an example. When the same observation as in Example 1 was carried out, no abnormal growth due to scratches was found as in Example 1.

Comparative Example 1 As shown in FIG. 2 (a), gallium nitride was epitaxially grown directly on the surface of a sapphire single crystal substrate similar to that of Example 1 by a metal organic chemical vapor deposition method (MOCVD method). However, as shown in FIG. 2B, a gallium nitride film affected by scratches (including latent scratches) on the substrate surface was formed. When the produced gallium nitride film was observed with a confocal microscope, abnormal growth that was considered to be caused by scratches was confirmed.

Comparative Example 2 A vapor-deposited film of aluminum oxide was formed at a high temperature on the surface of a sapphire single crystal substrate similar to that of Example 1 and crystallized by a metal organic chemical vapor deposition method (MOCVD method). When gallium nitride was epitaxially grown on the surface, a gallium nitride film affected by scratches (including latent scratches) on the substrate surface was formed as shown in FIG. 2 (b). When the produced gallium nitride film was observed with a confocal microscope, abnormal growth that was considered to be caused by scratches was confirmed.

[0034]

The invention according to any one of claims 1 to 5 is a gallium nitride film (GaN) that is not affected by scratches or latent scratches remaining on the surface of a sapphire single crystal substrate.
This has the effect of being able to form a film.

That is, when gallium nitride is epitaxially grown on the surface of the vapor-deposited film of single crystallized aluminum oxide or the surface of single crystallized aluminum nitride, the gallium nitride film has scratches existing on the surface of the sapphire single crystal substrate. Since it grows without being affected by or latent damage, the smoothness of the surface of gallium nitride is improved. As a result, it is possible to obtain a good substrate for semiconductor light emitting device in which the surface smoothness of the gallium nitride film is improved.

According to the present invention, in the method for manufacturing a substrate for a semiconductor light emitting device, a vapor deposition step of forming a vapor deposited film of amorphous aluminum oxide on the surface of a sapphire single crystal substrate,
A step of heat-treating the deposited film in an atmosphere selected from the atmosphere, oxygen and nitrogen to single crystallize the deposited film; and a step of epitaxially growing a gallium nitride film on the surface of the single crystallized deposited film It can also be regarded as a method for manufacturing a substrate for a semiconductor light emitting device, which includes:

Further, in the vapor deposition step, the film thickness of the vapor deposited film of aluminum oxide may be formed to be 1 nm or more and 1 μm or less, which can be regarded as a method for manufacturing a semiconductor light emitting device substrate.

[Brief description of drawings]

FIG. 1A is a sectional view of an aluminum oxide vapor-deposited sapphire single crystal substrate according to the present embodiment, and FIG. 1B is a sectional view of a semiconductor light emitting device according to the present embodiment.

2A is a cross-sectional view of an aluminum oxide vapor-deposited sapphire single crystal substrate according to the present embodiment, and FIG. 2B is a cross-sectional view of a semiconductor light emitting device according to the present embodiment.

3A is a cross-sectional view of a conventional sapphire single crystal substrate, and FIG. 3B is a cross-sectional view of a conventional semiconductor light emitting device.

[Explanation of symbols]

1. Aluminum oxide vapor deposition sapphire single crystal substrate 2 Sapphire single crystal substrate 3 Aluminum oxide vapor deposition film 4 Semiconductor light emitting device substrate 5 gallium nitride film 6 Aluminum oxide vapor deposition sapphire single crystal substrate 7 Aluminum nitride single crystal layer 8 Semiconductor light emitting device substrate

Claims (5)

[Claims] 1. An aluminum oxide vapor-deposited sapphire single crystal substrate having an amorphous aluminum oxide vapor deposition film formed on the surface of the sapphire single crystal substrate. 2. A vapor deposition film of amorphous aluminum oxide formed on the surface of a sapphire single crystal substrate,
An aluminum oxide vapor-deposited sapphire single crystal substrate, which is heat-treated in an atmosphere selected from any of nitrogen and then single-crystallized. 3. A vapor-deposited film of amorphous aluminum oxide formed on the surface of a sapphire single-crystal substrate is heat-treated in a nitrogen atmosphere and then single-crystallized, and a vapor-deposited film of aluminum oxide single-crystallized. An aluminum oxide vapor-deposited sapphire single crystal substrate, characterized in that a single crystal layer of aluminum nitride is formed on the surface of. 4. The aluminum oxide vapor-deposited sapphire single crystal substrate according to claim 1, wherein the thickness of the aluminum oxide vapor-deposited film is 1 nm or more and 1 μm or less. . 5. A substrate for semiconductor light emitting device, wherein a gallium nitride film is formed on the single crystallized aluminum oxide vapor-deposited sapphire single crystal substrate according to any one of claims 2 to 4.