JPH08250770A - Manufacturing of light-emitting device - Google Patents

Abstract

PURPOSE: To make high the luminance of a light-emitting device without concentrating an electric field between both electrodes as well as to make wide the allowable range of the breakdown voltage of the device by a method wherein a pair of electrodes are formed on an insulative substrate, an external electrode is provided in such a way as to encircle the periphery of an internal electrode and moreover, the external electrode is continuously provided. CONSTITUTION: An n-type GaN layer and an i-type GaN layer are laminated in order on a sapphire substrate. Then, the i-type GaN layer is etched to the n-type GaN by an ion-beam etching and one part of the n-type GaN layer is made to expose. Then, one pair of electrodes are formed on the substrate to the i-type and n-type GaN layers. An external electrode on the i-type GaN layer is formed in such a way as to encircle an internal electrode provided on the n-type GaN layer. The external electrode is continuously provided. The distance between the outer peripheral parts of the internal electrode on the n-type GaN layer and the external electrode, which encircles the outer peripheral parts, on the i-type GaN layer is equal, an applying voltage spreads uniformly to the GaN layers without concentrating an electric field between both electrodes and a light-emitting device emits effectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode structure of a semiconductor light emitting device, and more particularly to an electrode structure for obtaining a light emitting device having excellent emission brightness and reliability.

[0002]

2. Description of the Related Art Various compound semiconductors have been proposed as materials for blue light emitting devices. Recently, it has been clarified that gallium nitride-based compound semiconductors have the highest brightness among them, and they are attracting attention.

In general, a blue light emitting device having a gallium nitride-based compound semiconductor has a Ga _X Al _X-1 N ( 0 ≦ X ≦ 1) crystals are n-type and p-type
It can be obtained by stacking a mold, or n-type and i-type.

In a red light emitting device or a green light emitting device having a compound semiconductor such as GaAlAs or GaP, when an electrode is taken out from a p-type or n-type semiconductor crystal, since the substrate is already a semiconductor compound and has conductivity, the electrode Are usually taken out from above and below as shown in FIG.

However, for example, in a blue light emitting device having a gallium nitride-based compound semiconductor, since the pn junction or in junction crystal is grown on the insulating substrate as described above, it is not possible to take out the electrodes from above and below. It is impossible. Therefore, the electrodes are generally taken out as a structure as shown in FIGS.

FIG. 4 is a cross-sectional view of a blue light emitting device. Forming an electrode on the side surface of an n-type layer as shown in this figure requires a very fine work, which results in poor yield and production. It is technically very difficult.

FIG. 5 is also a sectional view of a blue light emitting device. As shown in this figure, it is easy to take out the electrode from above, and it is advantageous because it is excellent in production technology.

[0008]

A plan view of the blue light emitting device of FIG. 5 is shown in FIG. As shown in FIG. 6, in a light emitting device having an insulating substrate, when the electrodes are taken out from above, it is common to form the electrodes symmetrically.

However, in the left-right symmetric type electrode as shown in FIG. 6, a large electric field is concentrated between both electrodes, which causes the following problems.

The breakdown of the device occurs with a relatively small applied voltage. Since the electric field is locally concentrated, crystal deterioration occurs and the life is short. The area of the light emitting portion is smaller than the chip area.

[0011]

The present invention has been made in view of such circumstances, and by changing the shape (pattern) and the position of the electrode, the electric field spreads as much as possible in the chip and the electric field is concentrated. It is intended to provide an electrode structure for a light emitting device that prevents it from happening. That is, in the electrode structure of the light emitting device of the present invention, the semiconductor layer is laminated on the insulating substrate, and the pair of electrodes is formed on the same surface side of the semiconductor layer.

Furthermore, in the electrode structure of the light emitting device of the present invention, a plurality of semiconductor layers are laminated on the insulating substrate. A part of the semiconductor layer on the surface of the stacked semiconductor layers is removed by etching to expose the semiconductor layer on the inner surface. A pair of electrodes is formed on the exposed semiconductor layer on the inner surface and the semiconductor layer on the surface.

Further, in the electrode structure of the light emitting device of the present invention, the electrodes provided on the inner semiconductor layer and the front semiconductor layer have a unique structure. That is, a pair of electrodes is arranged so that one electrode is surrounded by the other electrode. Furthermore, the electrodes surrounding the periphery of one electrode are continuously provided.

[0014]

1 is a plan view of a blue light emitting device according to an embodiment of the present invention, and FIG. 2 is a sectional view of the same.
The light emitting device in this figure has a pair of electrodes formed on an i-type GaN layer and an n-type GaN layer. The electrode of the i-type GaN layer is formed so as to surround the electrode provided on the n-type GaN layer. Since the outer peripheral portion of the electrode of the n-type GaN layer has the same distance from the electrode of the i-type GaN layer surrounding it, electric field concentration is unlikely to occur between both electrodes, and the applied voltage should be spread uniformly over the GaN layer. Ga can be effectively
The N layer can emit light.

The present invention will be described below in detail based on an embodiment with reference to the drawings.

[0016]

EXAMPLE The manufacturing process of the electrode structure of the light emitting device of the present invention is shown in FIGS. As shown in the cross-sectional view of FIG. 7, an n-type GaN layer and an i-type GaN layer are sequentially laminated by MOCVD on a sapphire substrate which is an insulating substrate, and a plurality of semiconductor layers are laminated.

Further, as shown in the plan view of FIG. 8 and the sectional view of FIG. 9, a photoresist is formed on the surface of the i-type GaN layer which is the semiconductor layer on the surface to form an etching pattern. As shown in FIGS. 8 and 9, the photoresist is provided on the entire outer peripheral portion of the semiconductor layer, leaving the central portion.

By ion beam etching, i in the circle
The n-type GaN layer to the n-type GaN layer. In this step, a part of the i-type GaN layer which is the semiconductor layer on the surface is etched and removed, and a part of the n-type GaN layer on the inner surface is exposed. A cross-sectional view after etching is shown in FIG.

Next, after removing the photoresist with an organic solvent, a pattern for providing electrodes with the photoresist was similarly formed as shown in the plan view of FIG. 11 and the sectional view of FIG.

Finally, Al was vapor-deposited on the photoresist to form an electrode, and then the wafer was again immersed in an organic solvent to remove the photoresist, whereby the electrode of the blue light emitting device of the present invention could be formed. . The plan view is FIG. 1 and the cross-sectional view is FIG.

The light emitting device manufactured by the above process is
Although the electrode structure shown in the plan view of FIG. 1 is used, the electrode structure of the present invention is not limited to the circular shape shown in the embodiment, and may have a polygonal shape as shown in FIG. Not to mention good things.

[0022]

As described above, the electrode structure of the present invention is
Since the voltage can be applied under uniform conditions without concentrating the electric field between both electrodes, the emission brightness can be increased and the allowable range of the breakdown voltage is increased, so that a higher voltage can be applied. Can be operated. Further, the size of the chip can be reduced, which leads to cost reduction.

Furthermore, in the electrode structure of the light emitting device according to the present invention, a part of the semiconductor layer on the surface is removed by etching to expose the semiconductor layer on the inner surface, and the semiconductor layer on the inner surface and the semiconductor layer on the surface are electroded. Since the above-mentioned structure is provided, a feature that a pair of electrodes can be easily provided in an ideal shape continuously in the central portion and its periphery is also realized.

[Brief description of drawings]

FIG. 1 is a plan view showing an electrode structure of a light emitting device according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an electrode structure of a light emitting device according to an embodiment of the present invention.

FIG. 3 is a sectional view showing an electrode structure of a conventional light emitting device.

FIG. 4 is a sectional view showing an electrode structure of a conventional blue light emitting device.

FIG. 5 is a cross-sectional view showing an electrode structure of a conventional blue light emitting device.

FIG. 6 is a plan view showing an electrode structure of a conventional blue light emitting device.

FIG. 7 is a sectional view of an element obtained in one step of the present invention.

FIG. 8 is a plan view of an element obtained in one step of the present invention.

9 is a sectional view of FIG.

FIG. 10 is a sectional view of an element obtained in one step of the present invention.

FIG. 11 is a plan view of an element obtained in one step of the present invention.

FIG. 12 is a sectional view of FIG.

FIG. 13 is a plan view showing an electrode structure of a light emitting device according to another embodiment of the present invention.

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[Procedure amendment]

[Submission date] December 28, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title: Method for manufacturing light emitting device

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a semiconductor light emitting device .
Relates to a manufacturing method, in particular light-emitting luminance, and excellent reliability Germany
The present invention relates to a method for manufacturing a light emitting device having a special electrode structure.

[0002]

2. Description of the Related Art Various compound semiconductors have been proposed as materials for blue light emitting devices. Recently, it has been clarified that gallium nitride-based compound semiconductors have the highest brightness among them, and they are attracting attention.

In general, a blue light emitting device having a gallium nitride-based compound semiconductor has a Ga _X Al _X-1 N ( 0 ≦ X ≦ 1) crystals are n-type and p-type
It can be obtained by stacking a mold, or n-type and i-type.

In a red light emitting device or a green light emitting device having a compound semiconductor such as GaAlAs or GaP, when an electrode is taken out from a p-type or n-type semiconductor crystal, since the substrate is already a semiconductor compound and has conductivity, the electrode Are usually taken out from above and below as shown in FIG.

However, for example, in a blue light emitting device having a gallium nitride-based compound semiconductor, since the pn junction or in junction crystal is grown on the insulating substrate as described above, it is not possible to take out the electrodes from above and below. It is impossible. Therefore, the electrodes are generally taken out as a structure as shown in FIGS.

FIG. 4 is a cross-sectional view of a blue light emitting device. Forming an electrode on the side surface of an n-type layer as shown in this figure requires a very fine work, which results in poor yield and production. It is technically very difficult.

FIG. 5 is also a sectional view of a blue light emitting device. As shown in this figure, it is easy to take out the electrode from above, and it is advantageous because it is excellent in production technology.

[0008]

A plan view of the blue light emitting device of FIG. 5 is shown in FIG. As shown in FIG. 6, in a light emitting device having an insulating substrate, when the electrodes are taken out from above, it is common to form the electrodes symmetrically.

However, in the left-right symmetric type electrode as shown in FIG. 6, a large electric field is concentrated between both electrodes, which causes the following problems.

The breakdown of the device occurs with a relatively small applied voltage. Since the electric field is locally concentrated, crystal deterioration occurs and the life is short. The area of the light emitting portion is smaller than the chip area.

[0011]

The present invention has been made in view of such circumstances, and by changing the shape (pattern) and the position of the electrode, the electric field spreads as much as possible in the chip and the electric field is concentrated. Light emitting device to prevent it from happening
The present invention provides a method for manufacturing the same. That is, the method of manufacturing the light emitting device of the present invention, a semiconductor layer laminated on the insulating substrate, to form a pair of electrodes on the same side of the semi-conductor layer
It

Further, the method of manufacturing the light emitting device of the present invention
Is laminated semiconductor layer of a plurality of layers on an insulating substrate, the surface
Part of the semiconductor layer of the etched to expose the semiconductor layer of the inner surface was removed and a semiconductor layer of the inner surface of exposed, to form a pair of electrodes on the semiconductor layer surface.

Further, the method for manufacturing the light emitting device of the present invention
Is an electrode provided on the semiconductor layer of the inner surface of the semiconductor layer and the surface and unique structure. That is, a pair of electrodes is arranged so that one electrode is surrounded by the other electrode. Furthermore, the electrodes surrounding the one electrode is set kicked continuously
It is .

[0014]

1 is a plan view of a blue light emitting device according to an embodiment of the present invention, and FIG. 2 is a sectional view of the same.
The light emitting device in this figure has a pair of electrodes formed on an i-type GaN layer and an n-type GaN layer. The electrode of the i-type GaN layer is formed so as to surround the electrode provided on the n-type GaN layer . Since the outer peripheral portion of the electrode of the n-type GaN layer has the same distance from the electrode of the i-type GaN layer surrounding it, electric field concentration is unlikely to occur between both electrodes, and the applied voltage should be spread uniformly over the GaN layer. Therefore, the GaN layer can effectively emit light.

The present invention will be described below in detail based on an embodiment with reference to the drawings.

[0016]

EXAMPLE A manufacturing process of a method for manufacturing a light emitting device of the present invention is shown in FIGS. As shown in the cross-sectional view of FIG. 7, an n-type GaN layer and an i-type GaN layer are sequentially laminated by MOCVD on a sapphire substrate which is an insulating substrate, and a plurality of semiconductor layers are laminated.

Further, as shown in the plan view of FIG. 8 and the sectional view of FIG. 9, a photoresist is formed on the surface of the i-type GaN layer which is the semiconductor layer on the surface to form an etching pattern. As shown in FIGS. 8 and 9, the photoresist is provided on the entire outer peripheral portion of the semiconductor layer, leaving the central portion.

By ion beam etching, i in the circle
The n-type GaN layer to the n-type GaN layer. In this step, a part of the i-type GaN layer which is the semiconductor layer on the surface is etched and removed, and a part of the n-type GaN layer on the inner surface is exposed. A cross-sectional view after etching is shown in FIG.

Next, after removing the photoresist with an organic solvent, a pattern for providing electrodes with the photoresist was similarly formed as shown in the plan view of FIG. 11 and the sectional view of FIG.

Finally, Al was vapor-deposited on the photoresist to form an electrode, and then the wafer was again immersed in an organic solvent to remove the photoresist, whereby the electrode of the blue light emitting device of the present invention could be formed. . The plan view is FIG. 1 and the cross-sectional view is FIG.

The light emitting device manufactured by the above process is
Although the electrode structure shown in the plan view of FIG. 1 is used, the electrode structure of the present invention is not limited to the circular shape shown in the embodiment, and may have a polygonal shape as shown in FIG. Not to mention good things.

[0022]

As described above , it is manufactured by the method of the present invention.
In such a light emitting device , the voltage can be applied under uniform conditions without concentrating the electric field between both electrodes, so that the light emission brightness can be increased and the allowable range of the breakdown voltage can be increased. This enables operation at a higher voltage. Further, the size of the chip can be reduced, which leads to cost reduction.

Furthermore, the light emitting device of the present invention is manufactured.
Granulation method, a part of the semiconductor layer of the surface is removed by ET etching removal
To expose the semiconductor layer of the inner surface, Runode provided with an electrode on the semiconductor layer of the inner surface of the semiconductor layer and the surface, successively Chuo portion and its surroundings, simply provided that the pair of electrodes in an ideal shape The feature that can be realized is also realized.

[Brief description of drawings]

Flat face view of the origination <br/> optical device manufactured by the method according to an embodiment of the present invention; FIG

Cross-sectional view of the origination <br/> optical device manufactured by the method according to an embodiment of the present invention; FIG

3 is a cross-sectional view showing a conventional light emitting device

Cross-sectional view illustrating a conventional blue light emitting device FIG. 4

Figure 5 is a sectional view showing a conventional blue light emitting devices

6 is a plan view illustrating a conventional blue light emitting devices

FIG. 7 is a sectional view of an element obtained in one step of the present invention.

FIG. 8 is a plan view of an element obtained in one step of the present invention.

9 is a sectional view of FIG.

FIG. 10 is a sectional view of an element obtained in one step of the present invention.

FIG. 11 is a plan view of an element obtained in one step of the present invention.

FIG. 12 is a sectional view of FIG.

[13] The light emitting device according to another embodiment of the present invention
Plan view showing the manufacturing method

Claims (1)

[Claims] 1. An electrode structure of a light emitting device, comprising: a semiconductor layer laminated on an insulating substrate; and a pair of electrodes formed on the same side of the semiconductor layer, wherein a plurality of layers are formed on the insulating substrate. Semiconductor layers are stacked,
In the stacked semiconductor layers, a part of the semiconductor layer on the surface is removed by etching to expose the semiconductor layer on the inner surface, and a pair of electrodes are formed on the semiconductor layer on the inner surface and the semiconductor layer on the surface. The electrodes provided on the semiconductor layer on the inner surface and the semiconductor layer on the surface are arranged such that one electrode is surrounded by the other electrode, and further, the electrodes surrounding the one electrode are continuous. An electrode structure of a light-emitting device, characterized in that the electrode structure is provided.