JPH06169104A - Emiconductor light-emitting device and manufacture thereof - Google Patents

Abstract

PURPOSE:To increase the current-passing area on a P-N junction surface by a method wherein the groove, formed in the direction in parallel with the array direction where a plurality of lightemitting parts are arranged, is formed in mesa shape, adjacently- located light-emitting part separating groove is formed in forward mesa shape from the light-emitting surface to the P-N junction, and the part deeper than the P-N junction is formed in inverted mesa shape. CONSTITUTION:A p-type GaAs layer 13 is formed by growing an n-type GaAs layer 12 on a (100) n-type GaAs substrate 11 and by diffusing Zn. The photoresit, to be used for formation of a groove in the direction vertical to the array direction to be used for isolation of each light-emitting part from the array direction, is patterned in such a manner that the column direction where light-emitting parts are arranged in line is brought in parallel with the crystal axis in <0-11> direction, and when an etching treatment is conducted for formation of a groove deeper than the P-N junction surface using the above-mentioned photoresit as a mask, the groove in the direction of <0-11> is brought into forward mesa shape. The groove in direction <0-11> between light-emitting parts is formed in forwards mesa shape from the light emitting surface of the P-N junction surface 14, the part deeper than that is formed into inverted mesa shape, and the P-N junction surface 14 can be made wider.

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 such as a monolithic light emitting diode array.

[0002]

2. Description of the Related Art Conventionally, light emitting diode arrays have been used in various devices such as used as a light source for display devices and LED printer devices. Then, in a monolithic light-emitting diode array in which a plurality of light-emitting portions (light-emitting diode portions) are formed in rows on the surface of a compound semiconductor composed of each layer epitaxially grown on a single crystal substrate, each light-emitting portion has a selective diffusion method or a mesa. They are separated by a die etching method or the like. Then, for example, when the light emitting portion of the compound semiconductor in which the GaAsP layer is epitaxially grown on the GaAs substrate is separated by the selective diffusion method, the epitaxially grown GaAs is used.
The method of diffusing Zn at the boundary of each light emitting portion of the P layer is often adopted, but this method uses a diffusion mask and GaAs.
There is a drawback that Zn easily diffuses at the interface with the surface of the P layer, resulting in a poor production yield.

Therefore, a mesa type etching method is widely used in which unevenness is formed on the substrate surface to separate each light emitting portion. This mesa type etching method will be described with reference to FIGS. FIG. 4 is a perspective view showing a conventional light emitting diode array,
5 is a partially enlarged view showing the AA cross section, and FIG. 6 is a partially enlarged view also showing the BB cross section.

The light emitting diode array shown in FIG.
0) An n-type GaAsP layer 2 is epitaxially grown on the n-type GaAs substrate 1 by VPE (vapor phase epitaxy) or the like, and Zn is formed on the n-type GaAsP layer 2 by a sealed tube method.
To form a p-type GaAsP layer 3. Then, an etching mask of SiO ₂ , SiN or the like is provided on this, and patterning is performed so as to form an array in the direction of the crystal axis as shown in the figure. When deep etching is performed, the light emitting portions are separated as shown in FIGS.

Generally, the III-V compound semiconductor crystal has a strong anisotropy in the etching direction, and when the (1 0 0) plane is mesa-etched to form a groove in the <0 1 1> direction, the groove is formed. The ridge angle on the side surface of the groove is an acute angle (reverse mesa), and when the mesa etching is performed to form a groove in the <0 -11> direction, the ridge angle on the side surface of the groove is an obtuse angle (forward mesa).
Becomes Therefore, in this example, since the crystal axis in the column direction (array direction) in which the light emitting portions are arranged is the <0 -11> direction, the groove etched in the direction parallel to this column is shown in FIG.
As shown in FIG. 5, the etching groove is a forward mesa type, and in the direction perpendicular to this groove, the crystal axis is in the <0 1 1> direction. Therefore, the groove etched between them in order to separate each light emitting portion is shown in FIG. As shown in FIG. 4, the etching groove is an inverted mesa type. Then, a protective film 5 of SiO ₂ , SiN or the like is provided over the entire surface, a through hole 6 is provided in an electrode contact portion on the light emitting surface, and then an ohmic electrode 7 of Al or the like is laid on the forward mesa type etching groove. (Perpendicular to the array direction). Further, after a protective film 8 of SiO ₂ , SiN or the like is attached to the entire surface, the back surface side of the n-type GaAs substrate 1 is polished and an n-type electrode 9 is attached. The electrode 7 is provided on the forward mesa type etching groove because the metal may be vapor-deposited on the reverse mesa type etching groove to cause breakage.

[0006]

In the conventional light emitting diode array, since the groove for separating each light emitting portion is an inverted mesa-shaped etching groove as shown in FIG. 5, each light emitting portion is deepened as the etching groove is deepened. The current passing area at the pn junction surface becomes smaller and the resistance becomes larger, resulting in a decrease in light emission output. Particularly, in a light emitting diode array in which light emitting portions are formed with a narrow pitch of about 10 μm, an abnormally high current density is obtained by simply passing a current of several mA per dot, and the resulting heat generation results in a lifetime of several hundred hours. I couldn't get it. Therefore, the present invention provides a semiconductor light emitting device in which the current passing area at the pn junction surface is increased and the resistance of each light emitting portion is decreased, and a manufacturing method thereof.
It is an object of the present invention to extend the life and increase the output of a light emitting diode array in which light emitting portions are formed with a narrow pitch.

[0007]

As means for achieving the above object, in a semiconductor light emitting device in which a plurality of light emitting portions made of a compound semiconductor having a pn junction are formed in rows on a substrate. The grooves formed in the direction parallel to the array direction in which the light emitting portions are arranged are formed in a regular mesa shape,
The groove separating the adjacent light emitting portions has a forward mesa shape from the light emitting surface of each light emitting portion to the pn junction surface.
A semiconductor light emitting device characterized in that a portion deeper than the junction surface is formed in an inverted mesa shape, and a semiconductor light emitting device in which a plurality of light emitting portions made of a compound semiconductor having a pn junction are formed in rows on a substrate. And a step of forming a compound semiconductor having a pn junction on a substrate, and performing etching with phosphoric acid / hydrogen peroxide or an aqueous solution thereof to perform a step in a direction parallel to an array direction in which the plurality of light emitting portions are arranged. A mesa-shaped groove is formed, and a mesa-shaped groove is formed from the light-emitting surface of each light-emitting portion to the pn junction surface in a direction perpendicular to the adjacent array direction, and an inverted mesa-shaped groove is formed in a portion deeper than the pn junction surface. An object of the present invention is to provide a method for manufacturing a semiconductor light emitting device, which comprises the steps of forming and separating each of the light emitting portions, and providing each of the light emitting portions with an electrode. That.

[0008]

If the groove that is etched in the direction parallel to the array direction of the light emitting portions of the light emitting diode array is a forward mesa type etching groove and the groove that separates each light emitting portion has a wide pn junction surface. The above-mentioned problems are solved.
When an n-type GaAsP semiconductor in which Zn is diffused is etched with phosphoric acid / hydrogen peroxide mixture of phosphoric acid and hydrogen peroxide solution or an aqueous solution thereof, the groove etched in the <0 -11> direction is a forward mesa type etching groove. And <0 1 1>
It was found that the groove etched in the direction has a forward mesa shape in the p-type portion into which Zn is diffused and has an inverted mesa shape in the n-type portion. Therefore, if the grooves separating the light emitting portions are parallel to the <0 1 1> direction and etched by the above-described method, the grooves separating the light emitting portions from the light emitting surface to the pn junction surface are forward mesa. In the shape, the deeper portion becomes an inverted mesa shape and the pn junction surface becomes wider.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A semiconductor light emitting device and a method of manufacturing the same according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a light emitting diode array which is an embodiment of a semiconductor light emitting device of the present invention, FIG. 2 is a partially enlarged view showing an AA cross section thereof, and FIG. 3 is a BB cross section thereof. It is a partially enlarged view shown. First, a method of manufacturing the light emitting diode array will be described below with reference to the drawings. On the (100) n-type GaAs substrate 11, the n-type GaAsP layer 12 is grown to 80 μm by VPE (vapor phase epitaxy). Next, Zn is diffused by the sealed tube method,
P-type GaAsP layer (diffusion layer) from the surface to a depth of 2 μm
13 is formed. Then, a groove is formed in a direction perpendicular to the array direction and the array direction for separating each light emitting part so that the column direction (array direction) in which the light emitting parts are arranged is parallel to the crystal axis in the <0 −1 1> direction. Patterning the photoresist for forming the n-type Ga
In order to form a groove deeper than the pn junction surface 14 which is a boundary surface between the AsP layer 12 and the p-type GaAsP layer 13, when etching is performed with phosphoric acid / hydrogen peroxide up to a depth of 3 μm from the surface, it becomes parallel to the array direction. Grooves formed in the <0 -1 1> direction have a forward mesa shape as shown in FIG. 3, and grooves formed in the <0 1 1> direction between the respective light emitting portions are formed from the light emitting surface to the pn junction surface as shown in FIG. Up to 14 is a normal mesa shape, and a deeper portion is an inverted mesa shape, and the pn junction surface 14 is widened.

Then, after removing the photoresist, a protective film 15 of SiN is formed by plasma CVD to a thickness of 1000 A (angstrom), and through holes 16 are formed in the light emitting surface of each light emitting portion by plasma etching. Al17 is applied to a thickness of 8000 A by a vapor deposition method. Further, the pattern of the electrode wiring is patterned on the Al 17 with a photoresist, and the Al 17 is plasma-etched with a chlorine-based gas using this as a mask, and then the photoresist is removed to form a forward mesa formed in parallel with the array direction. A p-type electrode is formed that is drawn through the shaped groove. After that, a SiN protective film 18 is applied to the entire surface. Finally, the back surface of the n-type GaAs substrate 11 is polished, and then AuGeNi alloy 19 is vapor-deposited at 5000 A and heat-treated to form an n-type electrode, whereby a light emitting diode array as shown in FIG. 1 can be manufactured.

Since the light emitting diode array having such a structure has a large current passing area at the pn junction surface 14 of each light emitting portion, the resistance here becomes low and the light emitting output can be improved. Further, since the resistance at the pn junction surface 14 is low, even if the light emitting portions are formed with a narrow pitch, the heat generation does not increase, and the life can be extended. Further, since the portion of each light emitting portion below the pn junction surface 14 has an inverted mesa shape, light emitted downward from the pn junction surface 14 can also be reflected from this surface and extracted from the light emitting surface. .
As a result, it becomes possible to manufacture a light-emitting diode array having a narrower pitch that can be practically used. The present invention is also applicable to a semiconductor light emitting device made of a compound semiconductor material other than GaAsP used in the above embodiments.

[0012]

According to the semiconductor light emitting device of the present invention, the groove formed in the direction parallel to the array direction in which a plurality of light emitting portions are arranged is formed in a forward mesa shape, and the groove for separating adjacent light emitting portions is each light emitting portion. From the light emitting surface to the pn junction surface in a normal mesa shape
Since the portion deeper than the n-junction surface is formed in an inverted mesa shape, it is possible to increase the current passing area at the pn-junction surface of each light emitting portion and prevent a decrease in light emission output due to an increase in resistance. . In addition, as a result of suppressing the resistance at the pn junction surface to be low, heat generation does not increase even when the light emitting portions are formed with a narrow pitch, so that the life and output can be extended. The semiconductor light-emitting device manufacturing method of the present invention can easily manufacture a semiconductor light-emitting device having the above-described effects and can manufacture a light-emitting diode array having a narrower pitch. .

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a semiconductor light emitting device of the present invention.

2 is a partially enlarged view showing an AA cross section of the embodiment of the present invention shown in FIG.

3 is a partially enlarged view showing a B-B cross section of the embodiment of the present invention shown in FIG. 1. FIG.

FIG. 4 is a perspective view showing an example of a conventional semiconductor light emitting device.

5 is a partially enlarged view showing an AA cross section of the conventional example shown in FIG.

FIG. 6 is a partially enlarged view showing a BB cross section of the conventional example shown in FIG.

[Explanation of symbols]

 1,11 n-type GaAs substrate 2,12 n-type GaAsP layer 3,13 p-type GaAsP layer (diffusion layer) 4,14 pn junction surface 5,8,15,18 protective film 6,16 through-hole 7,9,17 , 19 electrodes

Claims (2)

[Claims] 1. A semiconductor light emitting device in which a plurality of light emitting portions made of a compound semiconductor having a pn junction are formed in a row on a substrate, and a groove formed in a direction parallel to an array direction in which the plurality of light emitting portions are arranged. Is formed in a normal mesa shape, and the groove separating the adjacent light emitting portions is a normal mesa shape from the light emitting surface of each light emitting portion to the pn junction surface.
A semiconductor light emitting device characterized in that a portion deeper than the bonding surface is formed in an inverted mesa shape. 2. A method for manufacturing a semiconductor light emitting device, comprising: forming a plurality of light emitting portions made of a compound semiconductor having a pn junction on a substrate in a row; and forming a compound semiconductor having a pn junction on a substrate. , Etching with phosphoric acid / hydrogen peroxide or its aqueous solution,
A groove having a forward mesa shape is formed in a direction parallel to the array direction in which the plurality of light emitting portions are arranged, and a normal mesa shape is formed from a light emitting surface of each light emitting portion to the pn junction surface in a direction perpendicular to the adjacent array direction. A semiconductor light emitting device characterized by comprising a step of forming an inverted mesa-shaped groove in a portion deeper than the pn junction surface to separate each light emitting portion, and a step of providing an electrode in each light emitting portion. Method.