JPH06177486A - Light-emitting element and manufacture thereof - Google Patents

Abstract

PURPOSE:To reduce the number of manufacturing processes by enabling the integration of a light-emitting element such as a semiconductor laser diode, a light-emitting diode, etc., in the light-emitting element. CONSTITUTION:At least a first clad layer 2, an active layer 3 and a second clad layer 4 are formed onto a base body 1, a micro-trench 7 is formed while being oppositely faced to an optical outgoing end face 10 consisting of an etching end face, and the side face 7S of the micro-trench 7 is used as an external reflecting mirror.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a surface emitting semiconductor laser diode (LD) and a light emitting diode (L).
The present invention relates to a light emitting device such as ED) and a manufacturing method thereof.

[0002]

2. Description of the Related Art Semiconductor laser diodes and light emitting diodes have been widely put to practical use as optical sources for optical disks, optical fiber communication, etc., and further improved in characteristics such as higher coherence and higher output, and functional devices such as optical modulators. Monolithic integration with is being promoted. In recent years, in particular, in consideration of application to parallel optical information processing in optical computers or the like, or large-capacity parallel optical transmission, realization of large-scale two-dimensional integration is desired.

However, the semiconductor laser of the conventional structure cannot be monolithically integrated because the cavity facet is formed by cleavage, and when the cavity facet is formed by etching, the cavity facet is perpendicular to the cavity facet. Cleavage is required to take out the light to the outside, and integration cannot be performed similarly. On the other hand, as a semiconductor laser that can be two-dimensionally integrated, a surface-emitting type laser that emits laser light in a direction perpendicular to the surface of the substrate is drawing attention.

As such a surface emitting laser, for example, a mirror surface is provided facing the light emitting end surface of a normal semiconductor laser and forming an angle of 45 ° with respect to the substrate. The structure is taken out in a direction perpendicular to the body surface. In order to form such a surface emitting laser as a monolithic structure, anisotropic dry etching such as RIE (reactive ion etching), RIBE (reactive ion beam etching), or ion milling is generally used. For example, the laser light emitting end surface and the mirror surface are formed by performing anisotropic etching twice on the semiconductor layer formed on the base body in a direction perpendicular to the base body and in an oblique direction of about 45 °. As a result, a surface emitting laser monolithically integrated can be obtained.

However, according to this method, after the light emitting end face is formed by etching, a selective mask is formed and
Since the second crystal growth and selective etching are required, the number of steps is large, the productivity is poor, and the yield is reduced, which is a cause of hindering optical integration.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a light emitting device such as a semiconductor laser diode or a light emitting diode.
Provided are a structure that can be integrated and a manufacturing method thereof.

[0007]

According to the present invention, as shown in a schematic enlarged cross-sectional view of an example thereof, at least a first cladding layer 2, an active layer 3 and a second cladding are formed on a substrate 1. The layer 4 is provided, the microtrench 7 is formed so as to face the light emitting end surface 10 formed of the etching end surface, and the side surface 7S of the microtrench 7 is configured as an external reflection mirror.

According to the present invention, in the above structure, at least a part of the external reflection mirror is formed by a curved surface.

Further, according to the present invention, as shown in an enlarged schematic sectional view of an example thereof, the transparent material 9 is embedded in the micro-trench 7 in the above-mentioned configuration.

Further, according to the present invention, as shown in FIGS. 3A to 3C, which are manufacturing process diagrams of an example thereof, after forming at least the first cladding layer 2, the active layer 3 and the second cladding layer 4 on the substrate 1. The mask layer 6 is used to perform etching in a predetermined pattern, the micro-trench 7 is formed so as to face the etching end face, and the side surface 7S of the micro-trench 7 is configured as an external reflection mirror.

[0011]

As described above, in the present invention, as shown in FIG. 1, the micro-trench 7 is simultaneously formed by etching at the time of forming the etching end face, and the side surface 7S thereof is configured as an external reflection mirror. It is possible to obtain a light emitting element that emits light in a direction substantially perpendicular to the substrate 1 without performing element separation, and it becomes possible to integrate such a surface emitting type light emitting element, and in manufacturing the same. Since it can be formed by one-time etching, it is possible to reduce the number of manufacturing steps, improve productivity, and improve yield.

Further, in such a structure, by forming at least a part of the side surface 7S to be the external reflection mirror as a curved surface, it is possible to obtain a light emitting element having a small directivity.

Furthermore, by depositing the transparent material 9 so as to fill the micro-trench 7, the transparent material 9 is used as, for example, a concave lens to expand the emitted light, and a light emitting element having a small directivity can be obtained. .

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, one embodiment of the present invention shown in FIG.
The manufacturing method will be described with reference to the process chart of FIG.

In this case, as shown in FIG. 3A, n-type I
On the substrate 1 made of nP or the like, for example, n-type GaIn
A first clad layer 2 made of P or the like, an active layer 3 made of AlGaInP or the like and a second clad layer 4 made of p-type GaInP or the like are sequentially epitaxially grown by MOCVD (Chemical Vapor Deposition Method using Metal Organic Metals) or the like. Further, in this case, the p-type electrode 5A made of Au or the like is deposited on the entire surface by sputtering or the like, and a mask layer 6 such as a photoresist is applied on the entire surface to be deposited.

Then, as shown in FIG. 3B, the mask layer 6 is patterned by exposure, development, etc. in a predetermined pattern covering the portion constituting the resonator, and anisotropic etching such as RIE is performed using the mask layer 6 as a mask. The electrode 5A is patterned by.

And further, as shown in FIG. 3C, electrode 5A
The second cladding layer 4 is self-aligned using
Etching the active layer 3 and the first cladding layer 2,
A light emitting end face 10 composed of an etching end face is formed, and at the same time, a micro trench 7 is formed. Then, after that, the electrode 5B is deposited on the back surface of the substrate 1 by sputtering or the like to obtain a light emitting element such as a laser diode or a light emitting diode.

The micro-trench 7 is, for example, RIB.
It can be formed by E or RIE under a high voltage. As a condition in which the micro-trench 7 is likely to occur, it is possible to use a relatively high energy beam, for example. That is, it can be realized by performing etching under a high voltage and increasing the directivity of the etching beam in the vertical direction, that is, in the direction perpendicular to the surface of the substrate 1. Further, a relatively high degree of vacuum is also required, and by carrying out etching with a small amount of introduced gas, it is possible to eliminate the scattering of ions and to increase the beam directivity.
Can be formed.

The cause of the formation of the micro-trench 7 is that the base 1 is placed in the vacuum apparatus substantially independently of other portions during etching such as RIE and RIBE. It is considered that a space charge layer is generated on the surface of the substrate 1 during generation to generate an electric potential, and the reaction gas introduced into the vacuum device acts on this to generate the electric potential. It should be noted that such microtrenches are prevented from being unnecessarily generated in the normal semiconductor device manufacturing process, but the present invention positively utilizes this phenomenon.

As for the size of the micro-trench 7, for example, since the beam spot of the emitted light of this laser diode is about 1 to 2 μmφ, the depth d is about 2 to 3 μm or more and the width is 2 to 2 μm. It is desirable that the thickness is about 3 μm or more.

In this example, the RF (high frequency) power density is 2 kW / 130 cm ² , and the introduced gas is 2 Ar.
8 cc, CH ₄ with 2 cc gas amount, vacuum degree 2.5
RIE was performed under a relatively low pressure of mTorr, and the micro-trench 7 having a depth d of about 2 to 3 μm could be formed at the same time as the light emitting end face 10 as shown in FIG.

At this time, the side surface 7S of the micro trench 7
By controlling the etching time such that the angle θ formed by the main surface of the substrate 1 is about 45 °, the emitted light such as laser light or LED light emitted from the light emitting end face 10 is emitted from the side surface 7S. reflected light L _O which is reflected as external reflection mirror, so that the emitted substantially upward direction perpendicular to the main surface of the substrate 1. In this case, it is necessary to control the depth so that at least the deepest part of the microtrench 7 reaches the first cladding layer 2 below the active layer 3. Further, the above-mentioned angle θ is preferably about 45 °, but is not limited to this.

Further, in this case, the micro trench 7
By forming at least a part of the side surface 7S of the light emitting element into a curved surface, a light emitting element with low directivity can be obtained, and by utilizing it for space transmission, for example, the light receiving range of the light emitting element can be increased. be able to.

Further, as shown in FIG. 2, a transparent material 9 is embedded in the micro-trench 7, and a concave lens is formed by forming the surface of the transparent material 9 into a concave shape, for example. An element can be formed, and similarly, a light emitting element whose light receiving range can be widened can be formed.

As a method of forming such a transparent material 9, for example, as shown in FIG. 4A, after a transparent material 9 made of photoresist or the like is entirely applied, a relatively weak exposure light is used. 4B, only the surface portion of the transparent material 9 is exposed and developed as shown by hatching, and the transparent material 9 can be embedded only in the micro trench 7 as shown in FIG. 4C. In this case, the surface is spontaneously formed into a concave shape, so that a concave lens can be formed. 4A to 4C, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and redundant description will be omitted.

As the transparent material 9, any other light-transmissive material such as resin may be used. If the surface of the transparent material 9 is naturally recessed, a light emitting element having a wide light receiving range is similarly constructed. be able to.

Although the electrode 5A is formed in the same pattern as the pattern for forming the light emitting end face 10 in the above-mentioned example, it may be formed by applying ordinary photolithography or the like after the end face 10 is formed. You can also

Further, it is needless to say that the present invention is not limited to the above-mentioned embodiment, and various modifications and changes can be made in the material constitution and the like.

[0029]

As described above, according to the present invention, the light emitting end face and the external reflection mirror can be simultaneously formed by etching, so that the number of manufacturing steps can be reduced and the productivity can be improved and the yield can be improved. You can improve.

Further, by forming at least a part of the side surface of the micro-trench forming the external reflection mirror into a curved surface, it is possible to obtain a light emitting element having a small directivity.

Furthermore, by filling the micro-trench with a transparent material, this portion can be protected, and by forming a concave lens, a light emitting element with less directivity can be obtained. By doing so, the light receiving range can be widened.

[Brief description of drawings]

FIG. 1 is a schematic enlarged cross-sectional view of an embodiment of the present invention.

FIG. 2 is a schematic enlarged cross-sectional view of an embodiment of the present invention.

FIG. 3 is a manufacturing process diagram of an example of the present invention.

FIG. 4 is a manufacturing process diagram of an example of the present invention.

[Explanation of symbols]

 1 Base 2 First clad layer 3 Active layer 4 Second clad layer 5A electrode 5B electrode 6 Mask layer 7 Micro trench 7S Side surface

Claims (4)

[Claims] 1. At least a first cladding layer on a substrate,
A light emitting device comprising an active layer and a second cladding layer, a microtrench formed opposite to a light emitting end face composed of an etching end face, and a side surface of the microtrench serving as an external reflection mirror. 2. The light emitting device according to claim 1, wherein at least a part of the external reflection mirror is formed of a curved surface. 3. The light emitting device according to claim 1, wherein a transparent material is embedded in the micro trench. 4. At least a first cladding layer on the substrate,
After forming the active layer and the second cladding layer, the mask layer is used to perform etching in a predetermined pattern,
A method of manufacturing a light emitting device, comprising forming a micro trench facing the etching end face, and using a side surface of the micro trench facing the etching end face as an external reflection mirror.