JPH08195505A - Semiconductor light-emitting element and manufacture thereof - Google Patents

Abstract

PURPOSE: To manufacture a semiconductor light-emitting element enabling efficient takeout of an emitted light. CONSTITUTION: A resist 5 is patterned on a GaP substrate 1 whereon a p-n junction 2 is formed, and then the resist 5 is made to reflow by heating and formed in a semispherical shape. In a dry etching process after this resist reflow process, a dry etching treatment is applied to the GaP substrate 1 whereon the semispherical resist 5 is formed, and thereby the shape of the resist 5 is transferred onto the p-n junction 2 so that this junction be formed in the semispherical shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device, which is a GaP light emitting diode having a pn junction formed on a GaP substrate, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In manufacturing such a GaP light emitting diode, a pn junction is formed on a GaP substrate by using liquid phase epitaxy, and at this time, the surface of the pn junction is formed to be substantially smooth.

Since such a light emitting diode has a smooth surface, the light emitted at the pn junction is extracted to the outside only as light having a component close to the vertical component with respect to the pn junction surface. Has become.

That is, the light component oblique to the pn-junction surface is reflected on the pn-junction surface due to the difference in refractive index between GaP and air, and is not extracted to the outside. Therefore, sufficient light emission intensity cannot be obtained for use as a light emitting element.

On the other hand, in order to increase the surface area of the light emitting surface, G
In manufacturing an aP-based light emitting diode, a GaP substrate is melted to form an uneven surface on the GaP substrate by using melting having a property of dissolving GaP.

However, even if the surface of the GaP substrate is formed in a concavo-convex shape in this way, the concavo-convex shape is irregular because it merely melts the GaP substrate.
It is difficult to efficiently extract the light emitted from the n-junction portion.

[0007]

As described above, in the light emitting diode, since the surface thereof is formed to be smooth, the light extracted to the outside is only the light having a component close to the vertical component with respect to the pn junction surface, which is sufficient. The emission intensity cannot be obtained.

Further, even if irregularities are formed on the surface of the GaP substrate, the irregularities are irregular and it is difficult to extract light efficiently. Therefore, an object of the present invention is to provide a semiconductor light emitting device that can efficiently extract emitted light. Another object of the present invention is to provide a method for manufacturing a semiconductor light emitting device that can efficiently extract emitted light.

[0009]

According to the first aspect of the present invention, since it is a semiconductor light emitting device in which a pn junction having a curved concave and convex shape is formed on a GaP substrate, the light emitted at the pn junction is uneven. It is efficiently taken out through the shape.

According to the second aspect, by forming the pn junction in a hemispherical shape, most of the light emitted at the pn junction portion travels almost perpendicularly to the hemispherical surface, which results in efficiency. It is often taken out.

According to the third aspect, since a large number of pn junctions formed on the minute hemispherical protrusions are assembled, the light emitted at the pn junction portion is efficiently extracted to the outside through the large number of hemispherical protrusions. .

According to the fourth aspect of the present invention, in the method for manufacturing a semiconductor light emitting device, the resist is patterned on the GaP substrate on which the pn junction is formed in the resist forming step, and the resist is heated and reflowed in the next resist reflow step. The resist is formed into a hemispherical shape, and after this registry flow step, the GaP substrate on which the hemispherical resist is formed in the dry etching step is dry-etched to transfer the shape of the resist to the pn junction. To form a hemisphere.

According to the fifth aspect, in the dry etching step in the method for manufacturing a semiconductor light emitting device, chlorine or a mixed gas system of oxygen and a gas containing chlorine is used as an etching gas.

According to a sixth aspect of the present invention, in the method for manufacturing a semiconductor light emitting device, the resist is patterned on the GaP substrate on which the pn junction is formed in the resist forming step, and the resist is heated and reflowed in the next resist reflow step. This resist is formed into a hemispherical shape, and after this registry flow step, a dry etching process on the resist and a dry etching process on the GaP substrate are alternately repeated in the dry etching process to form Ga.
The pn junction portion of the P substrate is formed stepwise, and in the next wet etching step, the stepwise pn junction portion is subjected to wet etching to form the pn junction portion in a hemispherical shape.

According to a seventh aspect of the present invention, the dry etching step in the method for manufacturing a semiconductor light emitting device uses a dry etching process for a GaP substrate using chlorine or a gas containing chlorine as an etching gas and oxygen as an etching gas. The dry etching process for the resist is alternately repeated. According to the eighth aspect, aqua regia is used in the wet etching step in the method for manufacturing a semiconductor light emitting device.

[0016]

【Example】

(1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a process diagram of a method for manufacturing a GaP light emitting diode. First, the pn junction 2 is formed on the GaP substrate 1 by liquid phase epitaxy. The pn junction 2 has a P-type GaP3 formed on the GaP substrate 1 and an n-type GaP4 formed thereon.

Next, the resist forming process is performed. In this resist forming step, a resist 5 is applied on the surface of the pn junction 2 on the GaP substrate 1, and the resist 5 is exposed / developed by a lithography technique in accordance with a predetermined resist pattern.

As the material of the resist 5, for example, a cresol novolac positive resist is used.
By this exposure / development process, the resist 5 is patterned according to a predetermined resist pattern as shown in FIG.

Next, the registry flow process is started. In this registry flow step, the GaP substrate 1 on which the resist pattern is formed is placed on a hot plate set at 180 ° C. for about 10 minutes and heated.

By this heating, the resist 5 on the GaP substrate 1 is reflowed and formed into a hemispherical shape as shown in FIG. Next, the dry etching process is performed.

In this dry etching process, a dry etching process is performed on the GaP substrate 1 on which the hemispherical resists 5 are formed. That is, a reactive ion etching apparatus is used, the GaP substrate 1 is placed in the chamber of this etching apparatus, and the flow rate of etching gas in this chamber is controlled by the mass flow controller.

This etching gas is a mixed gas system of chlorine or a gas containing chlorine and oxygen, for example, BCl.
₃ : Cl ₂ : O ₂ is used, and each flow rate is BCl ₃ : O _2.
Cl ₂ : O ₂ = 80: 20: 30 sccm and the pressure is set to 15 Pa.

When dry etching is performed by such a reactive ion etching apparatus, the GaP substrate 1
As shown in FIG. 7C, the resist 5 recedes as the etching progresses and the n-type GaP4 and P-type GaP
P3 is also etched.

That is, at the same time as etching of GaP, O
The action of ₂ also advances the retreat of the resist 5. As a result, the hemispherical shape of the resist 5 is transferred to the pn junction 2 to change the surface shape, and the pn junction 2 is formed into a hemispherical shape.

As described above, in the first embodiment,
The resist 5 is patterned on the GaP substrate 1 on which the pn junction 2 is formed, and then the resist 5 is heated and reflowed to form the resist 5 in a hemispherical shape. After the registry flow step, the hemisphere is formed in a dry etching step. Since the GaP substrate 1 on which the resist 5 having a circular shape is formed is dry-etched to transfer the shape of the resist 5 to the pn junction 2 to form a hemispherical shape, the pn junction 2 is formed into a hemispherical shape. The GaP light emitting diode described above can be manufactured. With such a light emitting diode, most of the light emitted from the pn junction 2 travels almost perpendicularly to the hemispherical surface, and the efficiency is improved. Light can be well extracted to the outside, and sufficient emission intensity can be obtained. This emission intensity can be improved by, for example, about 20%.

In the first embodiment, the pn junctions 2 may be formed by collecting a large number of minute hemispherical projections. In this case, since the shape of the pn junction 2 is formed as a minute hemispherical projection, the patterning shape of the resist 5 is formed by forming a large number of cylinders each having a small diameter.
Thereafter, similarly to the above, if a resist forming step, a resist reflow step, and then a dry etching step are sequentially performed, a large number of pn junctions formed on minute hemispherical protrusions can be formed.

In the case of a GaP light emitting diode having a large number of pn junctions formed on such minute hemispherical protrusions, the light emitted at the pn junction portion passes through a large number of hemispherical protrusions and is more efficiently externally emitted. Taken out. (2) Next, a second embodiment of the present invention will be described.

FIG. 2 is a process diagram of a method for manufacturing a GaP light emitting diode. First, the pn junction 2 is formed on the GaP substrate 1 by liquid phase epitaxy. The pn junction 2 has a P-type GaP3 formed on the GaP substrate 1 and an n-type GaP4 formed thereon.

Next, the resist forming process is performed. In this resist forming step, a resist 5 is applied on the surface of the pn junction 2 on the GaP substrate 1, and the resist 5 is exposed / developed by a lithography technique in accordance with a predetermined resist pattern.

As the material of the resist 5, for example, a cresol novolac positive resist is used.
By this exposure / development process, the resist 5 is patterned according to a predetermined resist pattern as shown in FIG.

The shape of each of the cylindrical resists 5 is, for example, 8 μm in diameter and 1 to 2 μm in thickness, and the interval between the resists 5 is 2 μm.
Next, the registry flow process is performed.

In this registry flow process, the GaP substrate 1 on which the resist pattern is formed is, for example, 180 degrees Celsius.
It is placed on a hot plate set at 0 ° C. for about 10 minutes and heated.

By this heating, the resist 5 on the GaP substrate 1 is reflowed and formed into a hemispherical shape as shown in FIG. Next, the dry etching process is performed.

In this dry etching process, the dry etching process for the resist 5 and the dry etching process for the GaP substrate 1, that is, the P-type GaP3 and the n-type GaP4 are alternately repeated to form the pn junction of the GaP substrate in a stepwise manner. .

That is, a magnetron RIE (reactive ion etching) device is used.
The GaP substrate 1 is placed in the chamber of the IE apparatus, and the etching gas flow rate in this chamber is controlled.

This etching gas is a mixed gas system of chlorine or a gas containing chlorine, such as silicon tetrachloride,
Boron trichloride, carbon tetrachloride, chlorine and argon are used alone or in combination.

Specifically, BCl ₃ : Cl ₂ is used, and each flow rate thereof is BCl ₃ : Cl ₂ = 100: 20 sccm.
And the pressure is set to 1 Pa. or,
The RF (high frequency) output is set to 200W.

The dry etching by the magnetron RIE apparatus is performed for 90 seconds, for example, and the P-type GaP3 and the n-type GaP4 are dry-etched. This dry etching process is performed for P-type GaP3 and n
It proceeds in the direction perpendicular to the mold GaP4.

Following this, an RIE apparatus (without using a magnetron RIE apparatus) is used, the GaP substrate 1 is placed in the chamber of this RIE apparatus, and the etching gas flow rate in this chamber is controlled.

As this etching gas, for example, O ₂ is used, the flow rate of each is set to O ₂ = 100 sccm, the pressure is set to 15 Pa, and the RF output is set to 600 W. The dry etching by the RIE apparatus is performed for 60 seconds, for example, and the dry etching process is performed on the resist 5.

In the dry etching process for the resist 5, since the resist 5 is reflowed into a hemispherical shape and the etching pressure is high, each resist 5 is etched not only in the vertical direction but also in the horizontal direction. As shown in (), resist receding occurs.

Therefore, in this dry etching process,
BCl _3: n-type GaP4 and p-type GaP using Cl ₂
The dry etching treatment for 3 is repeated four times, while the dry etching treatment for the resist 5 using O ₂ is alternately repeated three times.

By repeating these dry etching processes, n-type GaP4 and p-type GaP3 are vertically etched in each dry etching process, and the diameter of the resist 5 is successively reduced.

As a result, the etching of the GaP substrate 1 progresses, and as shown in FIG. 2 (d), n-type GaP4 and p
The mold GaP3 is formed stepwise. The height of the stepped portion is about 6 μm.

Next, the wet etching process is performed. In this wet etching step, the stepwise pn junction is wet-etched to form a hemispherical pn junction. In this wet etching process,
It is treated with aqua regia (HNO ₃ : HCl = 1: 3) for about 1 minute. As a result of this wet etching process, the stepwise pn junction is formed into a lens-like hemisphere as shown in FIG.

As described above, in the second embodiment,
A resist 5 is patterned on the GaP substrate 1 on which a pn junction is formed, the resist 5 is heated and reflowed to form a hemispherical shape, and a dry etching process for the resist 5 and a dry etching process for the GaP substrate 1 are performed in a dry etching process. And repeat alternately and Ga
Since the pn junction portion of the P substrate is formed stepwise and the stepwise pn junction portion is wet-etched to be formed in a hemispherical shape, the GaP system in which the pn junction 2 is formed in a hemispherical shape is formed. It is possible to manufacture a light emitting diode. With such a light emitting diode, most of the light emitted from the pn junction 2 travels almost perpendicularly to the hemispherical surface, and the light is efficiently emitted. It can be taken out to the outside and a sufficient emission intensity can be obtained. This emission intensity can be improved by, for example, about 20%.

When forming the pn junction 2 in a hemispherical shape, G
Dry etching treatment for aP substrate 1 and resist 5
The dry etching process is alternately repeated to form a staircase, and the wet etching process is subsequently performed using aqua regia, so that the pn junction 2 can be easily and surely formed in a hemispherical shape.

[0048]

As described above in detail, according to the present invention, it is possible to provide a semiconductor light emitting device capable of efficiently extracting emitted light. Further, according to the present invention, it is possible to provide a method for manufacturing a semiconductor light emitting device that can efficiently extract emitted light.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a method for manufacturing a semiconductor light emitting device according to the present invention.

FIG. 2 is a configuration diagram showing a second embodiment of a method for manufacturing a semiconductor light emitting device according to the present invention.

[Explanation of symbols]

1 ... GaP substrate, 2 ... pn junction, 3 ... P-type GaP, 4 ...
n-type GaP, 5 ... Resist.

Claims (8)

[Claims] 1. A pn having a curved concave-convex shape on a GaP substrate.
A semiconductor light emitting device having a junction formed. 2. The semiconductor light emitting device according to claim 1, wherein a pn junction is formed in a hemispherical shape. 3. The semiconductor light emitting device according to claim 1, wherein a large number of pn junctions formed on minute hemispherical protrusions are assembled. 4. A resist forming step of patterning a resist on a GaP substrate on which a pn junction is formed, a resist reflow step of forming the resist into a hemispherical shape by heating and reflowing the resist, and a resist reflow step. And a dry etching step of performing a dry etching process on the GaP substrate on which the hemispherical resist is formed to transfer the shape of the resist to the pn junction to form a hemispherical shape. A method for manufacturing a semiconductor light emitting device characterized by the above. 5. The method for producing a semiconductor light emitting device according to claim 4, wherein the dry etching step uses a mixed gas system of chlorine or a gas containing chlorine and oxygen as an etching gas. 6. A resist forming step of patterning a resist on a GaP substrate on which a pn junction is formed, a resist reflow step of forming the resist into a hemispherical shape by heating and reflowing the resist, and a resist reflow step. After that, a dry etching process for alternately repeating the dry etching process for the resist and the dry etching process for the GaP substrate to form a pn junction portion of the GaP substrate in a step shape, and a step of forming a pn junction portion in the step shape A wet etching step of performing a wet etching process to form the pn junction portion into a hemispherical shape. 7. The dry etching process comprises alternately repeating a dry etching process for a GaP substrate using chlorine or a gas containing chlorine as an etching gas and a dry etching process for a resist using oxygen as an etching gas. 7. The method for manufacturing a semiconductor light emitting device according to claim 6. 8. The method for manufacturing a semiconductor light emitting device according to claim 6, wherein aqua regia is used in the wet etching step.