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Semiconductor light emitting element and wafer


Title: Semiconductor light emitting element and wafer.
Abstract: There are provided a semiconductor light emitting element which allows an improvement in light extraction efficiency without increasing the number of fabrication steps, and a wafer. In a semiconductor light emitting element 1 formed by laminating a compound semiconductor layer 3 on a single crystal substrate, and dividing the single crystal substrate into pieces, the side faces 21 to 24 of each of substrate pieces 2 as the divided single crystal substrate are formed such that the side face 21 used as the reference of the substrate piece 2 forms an angle of 15° with respect to the (1-100) plane, and that the side faces 21 to 24 are formed of planes different from cleaved planes of a crystalline structure in the single crystal substrate. ...



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USPTO Applicaton #: #20100187565 - Class: 257103 (USPTO) - 07/29/10 - Class 257 
Inventors: Hidenori Kamei, Syuuichi Shinagawa

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The Patent Description & Claims data below is from USPTO Patent Application 20100187565, Semiconductor light emitting element and wafer.

CROSS-REFERENCE TO RELATED APPLICATIONS

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This application is a Divisional of U.S. application Ser. No. 12/298,664, filed on Oct. 27, 2008, which is a U.S. National Phase under 35 U.S.C. §371 of International Application No. PCT/JP2007/059562, filed Apr. 27, 2007, claiming priority of Japanese Patent Application No. 2006-123258, filed on Apr. 27, 2006, and Japanese Patent Application No. 2007-115554, filed Apr. 25, 2007, the entire contents of each of which are hereby incorporated by reference.

TECHNICAL FIELD

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The present invention relates to a semiconductor light emitting element in which a compound semiconductor layer is laminated on a single crystal substrate, and to a wafer.

BACKGROUND ART

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As a technology for increasing the efficiency of light extraction from a semiconductor light emitting element, and improving brightness, there is one described in Patent Document 1. In a gallium nitride-based compound semiconductor element described in Patent Document 1, the side faces of a substrate, or the side faces of the gallium nitride-based compound semiconductor element laminated on the substrate have been each formed into a concave and convex configuration by etching.

By thus forming the emission faces from which light is emitted into concave and convex faces, the degree to which light from the inside is totally reflected by the surfaces thereof can be reduced compared with the case where the emission faces are formed into flat and smooth faces, so that an improvement in light extraction efficiency is expected. Patent Document 1: Japanese Laid-Open Patent Publication No. 2004-6662

DISCLOSURE OF THE INVENTION

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Problems to be Solved by the Invention

However, in the gallium nitride-based compound semiconductor element described in Patent Document 1, the side faces of the substrate or the side faces of a gallium nitride-based compound semiconductor laminated on the substrate have been each formed into the concave and convex configuration by etching. Therefore, after the gallium nitride-based compound semiconductor is laminated on the substrate in a fabrication step thereof, it is necessary to add an etching step. This not only complicates the fabrication steps, but also increases fabrication cost. Additionally, in this method, concaves and convexes are reduced as the depth of etching is increased so that it is difficult to form the concave and convex configuration over the entire surfaces.

It is therefore an object of the present invention to provide a semiconductor light emitting element which allows an improvement in light extraction efficiency by forming concaves and convexes over the entire side faces of the semiconductor light emitting element without increasing the number of fabrication steps, and a wafer.

Means for Solving the Problems

A semiconductor light emitting element of the present invention is a semiconductor light emitting element formed by laminating a compound semiconductor layer on a single crystal substrate, and dividing the single crystal substrate into pieces, wherein the single crystal substrate has a hexagonal structure, and the side faces of the divided single crystal substrate are formed of planes different from the cleaved planes of the single crystal substrate.

A wafer of the present invention is a wafer which is a single crystal substrate on which a compound semiconductor layer forming a semiconductor light emitting element is laminated, wherein the single crystal substrate has a hexagonal structure, and an OF (Oriented Flat) surface indicative of the crystal direction of the single crystal substrate is formed of a plane different from cleaved planes.

In a preferred embodiment, a plane of the single crystal substrate on which the compound semiconductor layer is laminated is a (0001) plane.

In another preferred embodiment, a plane of the single crystal substrate on which the compound semiconductor layer is laminated is an a-plane, and a c-plane and an m-plane each orthogonal to the a-plane are the cleaved planes of the single crystal substrate. The a-plane indicates a plane with a (11-20) plane orientation, or a (1-210) plane or a (−2110) plane which is equivalent to the (11-20) plane. The c-plane indicates a plane with a (0001) orientation. The m-plane indicates a plane with a (1-100) plane orientation, or a (01-10) plane or a (10-10) plane which is equivalent to the (1-100) plane. More strictly, the sign of a numeral representing a plane orientation is different at a top side plane than at a back side plane. However, it is assumed in the present invention that, e.g., the (11-20) plane indicates both of the (11-20) plane and a (−1-120) plane. The c-plane is in orthogonal relation to all the a-planes and the m-planes. As combinations in each of which the a-plane is orthogonal to the m-plane, there are three combinations in which the a-planes and the m-planes are (11-20) and (1-100), (1-210) and (10-10), and (-2110) and (01-10), respectively. In the present invention, the three combinations in which the a-planes and the m-planes are orthogonal to each other will be mentioned hereinbelow.

Effect of the Invention

In the present invention, it is sufficient that the side faces of the single crystal substrate are formed of planes different from the cleaved planes. Accordingly, it is unnecessary to add a new fabrication step in order to improve light extraction efficiency. Therefore, a semiconductor element with high brightness efficiency can be provided without increasing fabrication cost.

BRIEF DESCRIPTION OF THE DRAWINGS

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FIG. 1 is a cross-sectional view showing a semiconductor light emitting element according to Embodiment 1;

FIG. 2 is a view showing a wafer according to Embodiment 1, and a compound semiconductor layer and electrodes each formed on the wafer;

FIG. 3 is a perspective view showing the wafer according to Embodiment 1;

FIG. 4(A) is a view showing the surface roughness of a side face of a semiconductor light emitting element according to Example 1, and FIG. 4(B) is a view showing the surface roughness of a side face of Comparative Example 1 as a conventional semiconductor light emitting element;

FIG. 5 is a view showing a conventional wafer according to Comparative Example 1, and a compound semiconductor layer and electrodes each formed on the wafer;

FIG. 6(A) is a drawing-substitute photograph in which a side face of the semiconductor light emitting element according to Example 1 is enlarged, FIG. 6(B) is a drawing-substitute photograph in which another side face of the semiconductor light emitting element according to Example 1 is enlarged, FIG. 6(C) is a drawing-substitute photograph in which a side face of Comparative Example 1 as the conventional semiconductor light emitting element is enlarged, and FIG. 6(D) is a drawing-substitute photograph in which another side face of the conventional semiconductor light emitting element of Comparative Example 1 is enlarged;

FIG. 7 a cross-sectional view showing a semiconductor light emitting element according to Embodiment 2;

FIG. 8 is a view showing a wafer according to Embodiment 2, and a compound semiconductor layer and electrodes each formed on the wafer;

FIG. 9 is a perspective view showing the wafer according to Embodiment 2;

FIG. 10(A) is a view showing the surface roughness of a side face of a semiconductor light emitting element according to Example 2, and FIG. 10(B) is a view showing the surface roughness of a side face of Comparative Example 2 as a conventional semiconductor light emitting element; and

FIG. 11 is a view showing a conventional wafer according to Comparative Example 2, and a compound semiconductor layer and electrodes each formed on the wafer.

DESCRIPTION OF NUMERALS

1, 1′ Semiconductor Light Emitting Elements

2, 2′ Substrate Pieces

3, 3′ Compound Semiconductor Layers

4, 4′ n-Electrodes

5, 5′ p-Electrodes

10, 10′ Wafers

11, 12 OF Surfaces

11′, 12′ OF Surfaces

20, 20′ Lamination Planes

21 to 28 Side Faces

21′ to 28′ Side Faces

31, 31′ n-Type Semiconductor Layers

32, 32′ Light Emitting Layers

33, 33′ p-Type Semiconductor Layers

BEST MODE FOR CARRYING OUT THE INVENTION

Before a description is given to the best modes, the outline of the embodiments will be described.

A semiconductor light emitting element in an embodiment of the present application is a semiconductor light emitting element formed by laminating a compound semiconductor layer on a single crystal substrate, and dividing the single crystal substrate into pieces, wherein the single crystal substrate has a hexagonal crystalline structure in which a (0001) plane is a lamination plane on which the compound semiconductor is laminated, and a (1-100) plane, a (0-110) plane, a (−1010) plane, a (−1100) plane, a (01-10) plane, and a (10-10) plane are cleaved planes, and all side faces of each of substrate pieces as the divided single crystal substrate are formed of planes different from the cleaved planes of the single crystal substrate. The notation of planes is given herein using Miller indices, and it is assumed that the sign—present in the notation of planes overlies a numeral subsequent to the sign—.

By dividing a crystal at the cleaved planes thereof, the resulting division planes become flat and smooth. By forming the side faces of the single crystal substrate of planes different from the cleaved planes of the crystalline structure in the single crystal substrate, the side faces of the substrate pieces as the divided single crystal substrate do not become flat and smooth faces but become faces with extremely small concaves and convexes. Therefore, when the single crystal substrate is divided in a fabrication step, it is sufficient to form the side faces of the substrate pieces of planes different from the cleaved planes. As a result, it is unnecessary to add a new fabrication step in order to improve light extraction efficiency.

In the semiconductor light emitting element mentioned above, the lamination plane of the substrate piece may also be formed in a generally rectangular shape, and one side face of the substrate piece may also form an angle of not less than 5° and not more than 25° with respect to any of the cleaved planes.

The angle formed between the individual cleaved planes which are the (1-100) plane, the (0-110) plane, the (−1010) plane, the (−1100) plane, the (01-10) plane, and the (10-10) plane of the hexagonal columnar crystalline structure is 60°. Therefore, when the substrate pieces are formed by dividing a lamination plane of the single crystal substrate into generally rectangular shapes, it is possible form each of the side surfaces of the substrate pieces of a plane different from the cleaved planes by performing the division such that each of the resulting division planes forms a predetermined angle with respect to any of the cleaved planes. Additionally, by adjusting the predetermined angle to a value of not less than 5° and not more than 25°, it is possible to ensure 5° or more for each of the side faces of the substrate piece as an angle formed thereby with respect to the cleaved plane. Therefore, by thus regulating the angle, it is possible to prevent the single crystal substrate from cracking first at the cleaved plane when the division is performed while circumventing the cleaved planes, and reliably form concaves and convexes in the side face.

The lamination plane of the substrate piece may also be formed in a generally rectangular shape, and one side face of the substrate piece may form an angle of not less than 10° and not more than 20° with respect to any of the cleaved planes.

By dividing the single crystal substrate such that one side face of the substrate piece forms an angle of not less than 10° and not more than 20° with respect to any of the cleaved planes, it is possible to ensure 10° or more for each of the side faces of the substrate piece as an angle formed thereby with respect to the cleaved plane. Therefore, by thus regulating the angle, it is possible to more reliably prevent the single crystal substrate from being cracked first at the cleaved plane when the division is performed while circumventing the cleaved planes, and form a larger number of concaves and convexes. This allows a further increase in light extraction efficiency.

The single crystal substrate may also be formed of any of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, a silicon carbide compound semiconductor, and an aluminum nitride-based compound semiconductor.

When the single crystal substrate is formed of any of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, a silicon carbide compound semiconductor, and an aluminum nitride-based compound semiconductor, and divided such that a lamination plane on which the compound semiconductor is laminated is the (0001) plane and formed in a generally rectangular shape, and each of the resulting division planes forms a predetermined angle with respect to any of the cleaved planes, it is possible to form all the side faces of the divided substrate pieces of planes different from the cleaved planes because each of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, a silicon carbide compound semiconductor, and an aluminum nitride-based compound semiconductor has a hexagonal crystalline structure in which the (1-100) plane, the (0-110) plane, the (−1010) plane, the (−1100) plane, the (01-10) plane, and the (10-10) plane are cleaved planes.

The compound semiconductor layer laminated on the single crystal substrate may also be formed of any of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, and an aluminum nitride-based compound semiconductor.

The compound semiconductor layer can be formed of any of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, and an aluminum nitride-based compound semiconductor. In particular, when the single crystal substrate is made of any of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, and an aluminum nitride-based compound semiconductor, the compound semiconductor layer can be laminated in the same crystal orientation as that of the crystal substrate. As a result, when the single crystal substrate is divided into pieces, the side faces of the compound semiconductor layer are also formed of planes different from the cleaved planes. This allows an improvement in light extraction efficiency.

A wafer in an embodiment of the present application is a wafer which is a single crystal substrate on which a layer of a compound semiconductor forming a semiconductor light emitting element is laminated, wherein the single crystal substrate has a hexagonal crystalline structure in which a (0001) plane is a lamination plane on which the compound semiconductor is laminated, and a (1-100) plane, a (0-110) plane, a (−1010) plane, a (−1100) plane, a (01-10) plane, and a (10-10) plane are cleaved planes, and an OF surface indicative of a crystal direction of the single crystal substrate is formed of a plane different from the cleaved planes.

By forming the OF surface serving as a reference when the wafer is divided or an electrode pattern is formed of a plane different from the cleaved planes of the single crystal substrate, it is possible to form the side faces of the divided single crystal substrate (substrate pieces) of planes different from the cleaved planes when the compound semiconductor is laminated on the wafer, and patterned on the wafer as the single crystal substrate such that the side faces of the rectangular light emitting element are parallel with or perpendicular to the OF surface, and the wafer is divided therealong. By forming the side faces of the substrate pieces of planes different from the cleaved planes, the side faces do not become flat and smooth faces, but faces with extremely small concaves and convexes. Therefore, it is sufficient to form the side faces of the substrate pieces of planes different from the cleaved planes when the single crystal substrate is divided in a fabrication step. As a result, it is unnecessary to add a new fabrication step in order to improve light extraction efficiency.

In the wafer mentioned above, the OF surface may also form an angle of not less than 5° and not more than 25° with respect to any of the cleaved planes.

When it is assumed that the single crystal substrate has a hexagonal crystalline structure in which the (0001) plane is a lamination plane on which the compound semiconductor is laminated, and the (1-100) plane, the (0-110) plane, the (−1010) plane, the (−1100) plane, the (01-10) plane, and the (10-10) plane are the cleaved planes, the angle formed by one of the (1-100) plane, the (0-110) plane, the (−1010) plane, the (−1100) plane, the (01-10) plane, and the (10-10) plane with respect to another is 60° . Therefore, by forming the OF surface serving as a reference when the wafer is divided or an electrode pattern is formed of a plane forming a predetermined angle with respect to any of the cleaved planes, it is possible to form each of the side faces of the divided single crystal substrate (substrate pieces) of a plane different from the cleaved planes when the compound semiconductor is laminated on the wafer, and patterned on the wafer as the single crystal substrate such that the side faces of the rectangular light emitting element are parallel with or perpendicular to the OF surface, and the wafer is divided therealong. Additionally, by adjusting the predetermined angle to a value of not less than 5° and not more than 25°, it is possible to ensure 5° or more for each of the side faces of the substrate pieces as an angle formed thereby with respect to the cleaved plane. As a result, it is possible to prevent the wafer from being cracked first at the cleaved plane when the division is performed while circumventing the cleaved planes, and reliably form concaves and convexes in the side face.

The OF surface may also form an angle of not less than 10° and not more than 20° with respect to any of the cleaved planes.

By forming the OF surface serving as a reference when the wafer is divided or an electrode pattern is formed of a plane forming an angle of not less than 10° and not more than 20° with respect to any of the cleaved planes, it is possible to ensure 10° or more for each of the side faces of the divided single crystal substrate (substrate pieces) as an angle formed thereby with respect to the cleaved plane when the compound semiconductor is laminated on the wafer, and patterned on the wafer as the single crystal substrate such that the side faces of the rectangular light emitting element are parallel with or perpendicular to the OF surface, and the wafer is divided therealong. As a result, it is possible to more reliably prevent the wafer from being cracked first at the cleaved plane when the division is performed while circumventing the cleaved planes, and form a larger number of concaves and convexes. This allows a further increase in light extraction efficiency.

The single crystal substrate may also be formed of any of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, a silicon carbide compound semiconductor, and an aluminum nitride-based compound semiconductor.

When the single crystal substrate is formed of any of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, a silicon carbide compound semiconductor, and an aluminum nitride-based compound semiconductor, and divided such that a lamination plane on which the compound semiconductor is laminated is the (0001) plane and formed in a generally rectangular shape, and each of the resulting division planes forms a predetermined angle with respect to any of the cleaved planes, it is possible to form all the side faces of the divided substrate pieces of planes different from the cleaved planes because each of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, a silicon carbide_compound semiconductor, and an aluminum nitride-based compound semiconductor has a hexagonal crystalline structure in which the (1-100) plane, the (0-110) plane, the (−1010) plane, the (−1100) plane, the (01-10) plane, and the (10-10) plane are cleaved planes.

A semiconductor light emitting element in another embodiment of the present application is a semiconductor light emitting element formed by laminating a compound semiconductor layer on a single crystal substrate, and dividing the single crystal substrate into pieces, wherein the single crystal substrate has a hexagonal crystalline structure in which an a-plane is a lamination plane on which the compound semiconductor is laminated, and a c-plane and an m-plane each orthogonal to the a-plane are cleaved planes, and all side faces of each of substrate pieces as the divided single crystal substrate are formed of planes different from the cleaved planes of the single crystal substrate.

By dividing a crystal at the cleaved planes thereof, the resulting division planes become flat and smooth. By forming the side faces of the single crystal substrate of planes different from the cleaved planes of the crystalline structure in the single crystal substrate, the side faces of the substrate pieces as the divided single crystal substrate do not become flat and smooth faces but become faces with extremely small concaves and convexes. Therefore, when the single crystal substrate is divided in a fabrication step, it is sufficient to form the side faces of the substrate pieces of planes different from the cleaved planes. As a result, it is unnecessary to add a new fabrication step in order to improve light extraction efficiency.

In the semiconductor light emitting element mentioned above, the lamination plane of the substrate piece may also be formed in a generally rectangular shape, and one side face of the substrate piece may also form an angle of not less than 5° and not more than 85° with respect to either of the c-plane and the m-plane which are the cleaved planes.

In the substrate having the hexagonal crystalline structure in which the a-plane forms a surface thereof, the c-plane and the m-plane serving as the cleaved planes are each perpendicular to the surface of the substrate, and the angle formed therebetween is 90°.Accordingly, when the substrate pieces are formed by dividing the lamination plane of the single crystal substrate into generally rectangular shapes, the division is performed such that each of the resulting division planes forms a predetermined angle with respect to either of the c-plane and the m-plane to allow each of the side faces of the substrate pieces to be formed of a plane different from the cleaved planes. Additionally, by adjusting the predetermined angle to a value of not less than 5° and not more than 85°, it is possible to ensure 5° or more for each of the side faces of the substrate pieces as an angle formed thereby with respect to the cleaved plane. Therefore, it is possible to prevent the substrate from cracking first at the cleaved plane when the division is performed while circumventing the cleaved planes, and reliably form concaves and convexes in the side face.

The lamination plane of the substrate piece may also be formed in a generally rectangular shape, and one side face of the substrate piece forms an angle of not less than 30° and not more than 60° with respect to either of the c-plane and the m-plane. The arrangement makes it possible to ensure 15° or more for each of the side faces of the substrate pieces as an angle formed thereby with respect to the cleaved plane. Therefore, it is possible to more reliably prevent the single crystal substrate from being cracked first at the cleaved plane when the division is performed while circumventing the cleaved planes, and form a larger number of concaves and convexes. This allows a further increase in light extraction efficiency.

The single crystal substrate may also be formed of any of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, a silicon carbide compound semiconductor, and an aluminum nitride-based compound semiconductor.

When the single crystal substrate is formed of any of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, a silicon carbide compound semiconductor, and an aluminum nitride-based compound semiconductor, and divided such that a lamination plane on which the compound semiconductor is laminated is the a-plane and formed in a generally rectangular shape, and each of the resulting division planes forms a predetermined angle with respect to either of the c-plane and the m-plane which are the cleaved planes, it is possible to form all the side faces of the divided substrate pieces of planes different from the cleaved planes because each of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, a silicon carbide compound semiconductor, and an aluminum nitride-based compound semiconductor has a hexagonal crystalline structure in which the c-plane and the m-plane are cleaved planes.

The compound semiconductor layer laminated on the single crystal substrate may also be formed of any of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, and an aluminum nitride-based compound semiconductor.

The compound semiconductor layer can be formed of any of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, and an aluminum nitride-based compound semiconductor. In particular, when the single crystal substrate is made of any of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, and an aluminum nitride-based compound semiconductor, the compound semiconductor layer can be laminated in the same crystal orientation as that of the crystal substrate. As a result, when the single crystal substrate is divided into pieces, the side faces of the compound semiconductor layer are also formed of planes different from the cleaved planes. This allows an improvement in light extraction efficiency.

A wafer in another embodiment of the present application is a wafer which is a single crystal substrate on which a compound semiconductor layer forming a semiconductor light emitting element is laminated, wherein the single crystal substrate has a hexagonal crystalline structure in which an a-plane is a lamination plane on which the compound semiconductor is laminated, and a c-plane and an m-plane each orthogonal to the a-plane are cleaved planes, and an OF surface indicative of a crystal direction of the single crystal substrate is formed of a plane different from the cleaved planes.

By forming the OF surface serving as a reference when the wafer is divided or an electrode pattern is formed of a plane different from the c-plane and the m-plane which are the cleaved planes of the single crystal substrate, it is possible to form the side faces of the divided single crystal substrate (substrate pieces) of planes different from the cleaved planes when the compound semiconductor is laminated on the wafer, and patterned on the wafer as the single crystal substrate such that the side faces of the rectangular light emitting element are parallel with or perpendicular to the OF surface, and the wafer is divided therealong. By forming the side faces of the substrate pieces of planes different from the cleaved planes, the side faces do not become flat and smooth faces, but faces with extremely small concaves and convexes. Therefore, it is sufficient to form the side faces of the substrate piece of planes different from the cleaved planes when the single crystal substrate is divided in a fabrication step. As a result, it is unnecessary to add a new fabrication step in order to improve light extraction efficiency.

In the wafer mentioned above, the OF surface may also form an angle of not less than 5° and not more than 85° with respect to either of the cleaved planes.

In the substrate having the hexagonal crystalline structure in which the a-plane forms a surface thereof, the c-plane and the m-plane serving which are the cleaved planes are each perpendicular to the surface of the substrate, and the angle formed therebetween is 90°. Accordingly, by forming the OF surface serving as a reference when the wafer is divided or an electrode pattern is formed of a plane forming a predetermined angle with respect to either of the c-plane and the m-plane which are the cleaved planes, it is possible to form each of the side faces of the divided single crystal substrate (substrate pieces) of a plane different from the cleaved planes when the compound semiconductor is laminated on the wafer, and patterned on the wafer as the single crystal substrate such that the side faces of the rectangular light emitting element are parallel with or perpendicular to the OF surface, and the wafer is divided therealong. Additionally, by adjusting the predetermined angle to a value of not less than 5° and not more than 85°, it is possible to ensure 5° or more for each of the side faces of the substrate pieces as an angle formed thereby with respect to the cleaved plane. Therefore, it is possible to prevent the wafer from cracking first at the cleaved plane when the division is performed while circumventing the cleaved planes, and reliably form concaves and convexes in the side face.

The OF surface may also form an angle of not less than 30° and not more than 60° with respect to either of the c-plane and the m-plane as the cleaved planes.

By forming the OF surface serving as a reference when the wafer is divided or an electrode pattern is formed of a plane forming an angle of not less than 30° and not more than 60° with respect to either of the c-plane and the m-plane which are the cleaved planes, it is possible to ensure 30° or more for each of the side faces of the divided single crystal substrate (substrate pieces) as an angle formed thereby with respect to the cleaved plane when the compound semiconductor is laminated on the wafer, and patterned on the wafer as the single crystal substrate such that the side faces of the rectangular light emitting element are parallel with or perpendicular to the OF surface, and the wafer is divided therealong. As a result, it is possible to more reliably prevent the wafer from being cracked first at the cleaved plane when the division is performed while circumventing the cleaved planes, and form a larger number of concaves and convexes. This allows a further increase in light extraction efficiency.

The single crystal substrate may also be formed of any of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, a silicon carbide compound semiconductor, and an aluminum nitride-based compound semiconductor.

When the single crystal substrate is formed of any of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, a silicon carbide compound semiconductor, and an aluminum nitride-based compound semiconductor, and divided such that a lamination plane on which the compound semiconductor is laminated is the a-plane and formed in a generally rectangular shape, and each of the resulting division planes forms a predetermined angle with respect to either of the c-plane and the m-plane which are the cleaved planes, it is possible to form all the side faces of the divided substrate pieces of planes different from the cleaved planes because each of a gallium nitride-based compound semiconductor, a zinc oxide-based compound semiconductor, a silicon carbide compound semiconductor, and an aluminum nitride-based compound semiconductor has a hexagonal crystalline structure in which the c-plane and the m-plane are cleaved planes.

Referring to the drawings, the embodiment of the present invention will be described hereinbelow in detail. In the drawings shown below, components having substantially the same functions will be denoted by the same reference numerals for the sake of simple explanation.

Embodiment 1

A semiconductor light emitting element according to Embodiment 1 will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view showing a semiconductor light emitting element 1 according to the present embodiment. FIG. 2 is a view showing a wafer according to the present embodiment, and a compound semiconductor layer and electrodes each formed on the wafer.

As shown in FIG. 1, the semiconductor light emitting element 1 includes a substrate piece 2, a compound semiconductor layer 3, an n-electrode 4, and a p-electrode 5, and is formed by dividing a wafer-state single crystal substrate on which the compound semiconductor layer is laminated. For the substrate piece 2 which is a single crystal substrate, any substrate piece having a light transmitting property can be used. In the present embodiment, the substrate piece 2 can be formed of any of a gallium nitride-based compound semiconductor, a silicon carbide compound semiconductor, a zinc oxide-based compound semiconductor, and an aluminum nitride-based compound semiconductor.



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stats Patent Info
Application #
US 20100187565 A1
Publish Date
07/29/2010
Document #
12689759
File Date
01/19/2010
USPTO Class
257103
Other USPTO Classes
257E33013
International Class
01L33/26
Drawings
10


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