JPH0851233A - Light emitting diode - Google Patents

Abstract

PURPOSE:To lessen the scattering of brightness or reliability by arranging the constitution such that the width of a double hetero layer is smaller than the widths of other layers, and that the edge of the double hetero layer is indented from the edges of other layers. CONSTITUTION:A double hetero structure of light emitting part is made by stacking an n-type GaAs buffer layer 9, an n-type semiconductor multilayer reflector 8, an n-type clad layer 7, an active layer 6, a p-type clad layer 5 on a GaAs substrate 10 in order, and further a p-type AlGaAs window layer 4, a p-type AlGaInP etching stop layer 3, a p-type GaAs contact layer 2 are stacked. And, the double hetero layer including the active layer 6 is made smaller by 3mum than the upper and lower layers by performing etching in etchant of HCl:H2O=6:4 at 30 deg.C, for removal of the side damage of p layer of the double hetero layer. Hereby, a light emitting diode, which is hardly subjected to the damage to the active layer and is small in dispersion of brightness and high in reliability, can be manufactured.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a structure of a light emitting diode using a compound semiconductor material.

[0002]

2. Description of the Related Art Light emitting diodes (LEDs) are used in many fields as display materials and optical communication materials.
Al for the purpose of obtaining high brightness light emission from green to red
In a GaInP-based LED, it is difficult to dope the P-type cladding layer and it is difficult for the current to spread. Therefore, the light emitting region is not expanded and the light emitting efficiency is reduced. Such AlGaIn
In the P-based LED, a window layer or a current diffusion layer is formed on the double hetero layer that is the light emitting portion to improve the light extraction efficiency to the outside.

In the manufacturing process of such an LED, in the conventional technique, dicing or mesa etching is often used in the element isolation process of a light emitting diode manufactured on a semiconductor substrate. When elements are separated by mesa etching, the diameter of the chip becomes smaller toward the surface of the light emitting diode, resulting in the structure shown in FIG. Further, in the conventional element isolation by dicing, a part of the side surface is etched off in order to remove the side surface damage after dicing. However, in the double hetero layer of the light emitting diode thus manufactured, the widths of the upper and lower layers are almost the same, and the structure is as shown in FIG.

[0004]

In such a structure, the side surface of the double hetero layer is likely to come into contact with the outside and the double hetero layer is easily damaged again in the process of molding the light emitting diode chip into a product. .
This causes stress and damage to the double hetero layer, and causes problems such as reduced brightness and reduced reliability.

The present invention solves the above-mentioned problems and is less susceptible to damage to the double hetero layer in the process of producing a light emitting diode chip into a product, and there is little decrease in brightness from the original brightness and deterioration in reliability. Another object of the present invention is to provide a light emitting diode with less variation in brightness and reliability.

[0006]

The present invention focuses on the fact that the etching rate after element isolation by dicing is different depending on whether the group V element is an As-based or P-based element. The width of the double hetero layer was reduced by increasing the etching amount. H ₂ SO ₄ + H ₂ O ₂ + H ₂ O is used as an etchant with an As-based etching rate higher than the P-based etching rate.
System, NH ₃ + H ₂ O ₂ + H ₂ O type etchant and the like. Further, HCl + H ₂ O is used as an etchant having a P-based etching rate higher than the As-based etching rate.
_{There are 2} + H ₂ O type etchants. Etching is performed by combining one or both of such etchants, and the etching amount of the double hetero layer is made larger than that of the upper and lower layers. It is characterized by being made smaller. That is, the end surface of the double hetero layer is slightly smaller than the end surfaces of the upper and lower layers when seen through, and the area of the double hetero layer is smaller than the area of the upper and lower layers.

[0007]

According to the present invention, in the process of making a light emitting diode chip into a light emitting diode of a product, the active layer is less likely to be damaged, and the decrease or variation in brightness due to the presence or absence of damage is small, and the reliability of the light emitting diode is high. Can be manufactured.

[0008]

1 is a sectional view showing a schematic structure of a light emitting diode according to an embodiment of the present invention. That is, an n-type semiconductor multilayer film reflection mirror is provided on an GaAs substrate via an n-type GaAs buffer layer, and an n-type clad layer (Al
_{0.7 Ga 0.3) 0.5 In 0. 5} P 0.5, undoped as an active layer _{(Al 0.2 Ga 0.8) 0.5 In} 0.5 P, a p-type cladding layer (Al _0.7 Ga _0.3) to double by laminating a _0.5 an In _0.5 P in order A light emitting portion having a terror structure is formed, and a p-type AlGaAs window layer and a p-type AlGaInP etching stop layer are formed as (Al _0.7 Ga _0.3 ) _0.5 In _0.5.
It is a stack of P and p type GaAs contact layers.

The layer thickness is n-type GaAs buffer layer 0.5.
μm, n-type semiconductor multilayer film reflecting mirror 2.4 μm, n-type clad layer 1.0 μm, undoped active layer 0.5 μm, p-type clad layer 1.0 μm, p-type AlGaAs window layer 4.0 μm
m, p-type AlGaInP etching stop layer 0.05
μm, p-type GaAs contact layer 0.3 μm.

On the contact layer, p made of AuBe
A side electrode is formed, and an n-side electrode made of AuGe is formed under the substrate.

Hereinafter, a method of etching the light emitting diode chip after all dicing from the substrate with a dicer will be described. First, in order to remove the side surface damage of the As-based layer such as the window layer and the reflection layer, H ₂ SO ₄ : H ₂ O ₂ : H _{2 at} 40 ° C.
Etching is performed for 15 seconds with an etching solution of O = 3: 1: 1. Next, etching was performed for 3 minutes with an etching solution of HCl: H ₂ O = 6: 4 at 30 ° C. for the purpose of removing the side damage of the P-based layer of the double hetero layer. As a result of the above etching, a structure was obtained in which the width of the double hetero layer including the active layer was 3 μm smaller than the upper and lower layers.

A light emitting diode was manufactured by mounting and molding the light emitting diode chip obtained by the above method. At the same position on the same wafer, a light emitting diode was manufactured by the above method and a conventional method, and the luminance was measured using an integrating sphere. The brightness and variations are shown in Table 1.
As described above, the light emitting diode obtained by the present invention has less variation in luminance than the light emitting diode obtained by the conventional technique. It is considered that this is because the active layer or the double hetero layer of some chips was damaged during the handling until the light emitting diode chips were molded, and the brightness was deteriorated.

[0013]

[Table 1]

The above embodiments have been described using the AlGaInP-based double heterostructure epitaxial substrate.
However, the reflective layer below the double hetero layer shown in this embodiment may be omitted. The double hetero layer is made of AlGaIn.
Not only the P-based material but also other substance-based materials may be selected, and the appropriate etching solution and time and temperature for the upper and lower sides may be selected.
The width of the double hetero layer may be smaller than that of the upper and lower layers.

[0015]

As described above, according to the present invention, in the process of manufacturing a light emitting diode chip into a product, the active layer is less likely to be damaged, there is little variation in luminance depending on the presence or absence of damage, and highly reliable light emission is achieved. It becomes possible to fabricate a diode.

[Brief description of drawings]

FIG. 1 is a sectional view of a light emitting diode according to the present invention.

FIG. 2 is a sectional view of a light emitting diode having a conventional structure in which elements are separated by dicing.

FIG. 3 is a cross-sectional view of a light emitting diode having a conventional structure in which elements are separated by mesa etching.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 electrode 2 p-type GaAs contact layer 3 p-type AlGaInP etching stop layer 4 p-type AlGaAs window layer 5 p-type clad layer 6 active layer 7 n-type clad layer 8 semiconductor multilayer film reflective mirror 9 n-type GaAs buffer layer 10 n-type GaAs Substrate 11 electrode

Claims (3)

[Claims] 1. A light emitting diode having a double hetero structure in which an active layer formed on a semiconductor substrate is sandwiched by clad layers, wherein the width of the double hetero layer is smaller than the width of other layers and the double hetero layer. A light emitting diode having a double hetero structure, characterized in that the end face has a structure retracted from the end faces of other layers. 2. The light emitting diode having a double hetero structure according to claim 1, wherein the double hetero layer is made of an AlGaInP-based material, and one of the layers above the double hetero layer is a layer containing As. 3. The double-heterostructure light emitting diode according to claim 1, wherein the width of the double hetero layer is smaller than the width of other layers above and below it by 5 μm or more.