JPH06326352A - Semiconductor light emitting device and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] (Modified) [Objective] To provide a method for manufacturing a semiconductor light-emitting device, which can prevent deterioration of characteristics of pellets, improve yield, and simplify the manufacturing process. [Structure] An n-type GaAs substrate side and a GaAlAs current diffusion layer side of an epitaxial wafer 10 in which an InGaAlP double heterojunction layer and a GaAlAs current diffusion layer 5 are grown on an n-type GaAs substrate 1 by the MOCVD method, respectively. After forming the electrode 11 and the p-type electrode 12 and forming a protective film on the GaAlAs current diffusion layer 5 and the p-type electrode 12, at least the n-type GaAs substrate, the InGaAlP double heterojunction layer and the G
The aAlAs current diffusion layer was subjected to a dicing process for separating each element, the entire dicing surface after the dicing process was etched by 2 μm or more with a bromine-based etching solution, and then the protective film was removed.

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 element such as a light emitting diode (LED) used for a stop lamp of an automobile, a traffic light, an information display board in a station, and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art A light emitting diode that emits light by recombination of excess electron-hole pairs can obtain a light amount proportional to its bias current by applying a forward bias.

Conventionally, as a method of manufacturing such a light emitting diode, for example, there is one shown in FIG.

FIGS. 5A to 5F are views showing a conventional LED pelletizing process.

First, as shown in FIG. 1A, n-type Ga
On the As substrate 101, n-type In0.5 (Ga _1-x Al _x) 0.5
P-type cladding layer (x = 0.7) 102 and n-type In0.5 (Ga _1-y)
Al _y ) 0.5P active layer (0 ≦ y <0.5) 103,
p-type In0.5 (Ga _1-z Al _z ) 0.5P cladding layer (z = 0.7
) 104 and a p-type Ga _1-u Al _u As current spreading layer (0.7
≦ u ≦ 0.8) in order, followed by metalorganic vapor phase method (MOCVD
Method) to grow a crystal to form an epitaxial wafer 11
Form 0. Here, the InGaAlP clad layer 10
2 and InGaAlP active layer 103 and InGaAl
A double heterojunction structure is formed with the P clad layer 104.

Next, as shown in FIG. 5B, n-type GaA
AuGe (weight ratio 3% Ge) on the entire back surface of the substrate 101
Forming the n-type electrode 111 of p-type GaAlAs
A p-type electrode (140 μm ^φ ) 112 of AuZn (weight ratio 3% Zn) 112 is formed on the surface of 105 and sintered (heat treatment).
Depending on the process, ohmic contact is made.

Then, as shown in FIG. 5C, a resist or a CVD film 113 of SiO2 or SiNx is formed.
After being formed as a protective film for etching on the light extraction surface of the p-type GaAlAs 105 and the p-type electrode 112, the p-type Ga is wet-etched by dry etching or an HCl-based wet solution.
AlAs current spreading layer 105, InGaAlP clad layer 104, InGaAlP active layer 103, and In
The GaAlP clad layer 102 is etched.

After that, as shown in FIG. 5 (d), after cutting into individual chips (elements) by using a dicing machine in a dicing process, in order to remove the remaining crushed layer, as shown in FIG. 5 (e). As shown, the side surface of the n-type GaAs substrate 101 is etched by about 0.5 to 1.0 μm with an NH ₄ OH-based wet etching solution. And FIG.
As shown in (f), the protective film 13 is removed and the pelletizing step is completed.

[0009]

However, in the conventional LED pelletizing process, the crushing layer remaining on the GaAs substrate 101 on the side of the pellet during the dancing is etched as described above, but the dicing machine itself used in the dicing process is used. Vibration shake and the state of the blade,
For example, the depth of the crushed layer may change due to variation factors such as chips adhering to the blade, and the crushed layer may not be completely removed with an etching amount of about 1 μm.

On the other hand, since products such as LED lamps are manufactured by molding pellets with a lens-shaped resin, stress due to the resin acts on the pellets. Therefore, if a fractured layer remains on the side surface of the pellet as described above, crystal dislocation (sliding of crystals; disorder of the regularity of the arrangement of crystal lattices) occurs from that point, and this causes the dislocation from the pellet during energization. Light intensity drops rapidly (deterioration of characteristics)
Will be done.

Therefore, when the etching amount is set to be large in consideration of the variation in the depth of the fractured layer, for example, 2 μm.
When the etching is performed to have a thickness of m or more, an uneven portion is generated at the interface between the n-type InGaAlP cladding layer 102 and the n-type GaAs substrate 101. Also in this case, when the pellets are resin-molded, crystal dislocations start from the uneven portions of the interface, which causes deterioration of the characteristics of the pellets. From such a point, it is difficult to control the pelletizing process in the related art, and it is difficult to improve the yield of pellets.

Further, in the above-mentioned conventional pelletizing step, as shown in FIGS. 5 (c), (d) and (e), an etching step is required before and after the dicing process for separating each element, As a result, the process was complicated.

The present invention has been made in order to solve the above-mentioned conventional problems, and an object thereof is to prevent deterioration of characteristics of pellets and improve yield, and to simplify the manufacturing process. It is an object of the present invention to provide a semiconductor light emitting device that can be realized and a manufacturing method thereof.

[0014]

In order to achieve the above object, a feature of the first invention is that MOC is formed on an n-type GaAs substrate.
InGaAlP double heterojunction layer and GaAlAs current diffusion layer formed by VD method, and the n-type GaAs
In a semiconductor light emitting device, which has an n-type electrode and a p-type electrode formed on the substrate side and the GaAlAs current diffusion layer side, respectively, and is pelletized through a dicing process for separating into devices, the dicing process is performed at least This is performed on the wafer-shaped n-type GaAs substrate, the InGaAlP double heterojunction layer, and the GaAlAs current diffusion layer, and the entire surface of the dicing surface after the dicing process is etched by bromine-based etching solution to a depth of 2 μm or more to form pellets. There is something I did.

The second aspect of the present invention is characterized in that the InGaAlP double heterojunction layer and the GaAlAs current diffusion layer are grown on the n-type GaAs substrate by the MOCVD method, on the n-type GaAs substrate side and the GaA side of the epitaxial wafer.
An electrode forming step of forming an n-type electrode and a p-type electrode on the lAs current diffusion layer side, and a protective film on the GaAlAs current diffusion layer and the p-type electrode, and then at least the n-type GaAs substrate and the InGaAlP double layer. A dicing step of performing a dicing process for separating the heterojunction layer and the GaAlAs current diffusion layer for each element, and etching the entire dicing surface after the dicing process with a bromine-based etching solution for 2 μm or more, and then the protective film. That is, the etching step for removing is removed.

[0016]

According to the above-mentioned structure, in the first invention, even when the crushed layer remains on the dicing surface when the epitaxial wafer is separated into the elements by performing the dancing process, Since the entire surface of the dicing surface is etched by at least 2 μm or more using a bromine-based etching solution, the crushed layer is completely removed. further,
At that time, the bromine-based etching solution is GaAs or InGaA.
Since the difference in etching rate between IP and GaAlAs is small, the GaAs-InGaAlP interface and I
No unevenness occurs at the nGaAlP-GaAlAs interface. Therefore, even when the pellet is resin-molded, crystal dislocation unlike the conventional case does not occur.

According to the second aspect of the invention, after the n-type electrode and the p-type electrode are formed, the InGaAlP double heterojunction layer and the GaAlAs current diffusion layer of the epitaxial wafer are not subjected to etching treatment as in the conventional case, and element isolation is performed. The dicing process is performed. As a result, the elements are separated into pellets, and then the etching process is performed to etch the entire surface of the dicing surface by at least 2 μm using a bromine-based etching solution, thereby reducing the number of etching processes as compared with the conventional method.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1A to 1F are LEs embodying the present invention.
It is a manufacturing-process figure which shows the pelletization process of D.

First, as shown in FIG.
N-type In0.5 (Ga) was formed on the As substrate 1 by MOCVD.
_1-x Al _x) 0.5 P cladding layer 2 and n-type In 0.5 (Ga
And _1-y Al y) 0.5P active layer 3, p-type In0.5 (Ga
_1-z Al _z ) 0.5P cladding layer 4 and p-type Ga _1-u Al _u
As current diffusion layer 5 and 1 μm, 0.6 μm,
Crystal growth is sequentially performed to 1 μm and 7 μm to form the epitaxial wafer 10.

This MOCVD method is one of vapor phase growth methods and utilizes thermal decomposition of an organometallic compound. For example, in the case of a III-V group compound as described above, a III group (A
The organic metal of (1, Ga, In) and the hydrogen compound of group V (P, As) are reacted at a high temperature to obtain many kinds of compounds and their mixed crystals (substitution solid solution). According to this MOCVD method, a uniform thin film can be obtained.

The three layers of the clad layer 2, the active layer 3 serving as a light emitting layer and the clad layer 4 have a double heterojunction structure.

Therefore, the n-type and p-type cladding layers 2,
The mixed crystal ratios x and z of 4 are transparent to the emission wavelength (having a small refractive index) and have a carrier confinement effect. Therefore, y <x ≦ 1, y <z ≦ 1 (y; active layer (Mixed crystal ratio of 3). Here, the mixed crystal ratio y of the active layer 3 serving as the light emitting layer is set to 0 ≦ y ≦ 0.5 so that the oscillation wavelength is 560 to 670 nm. The mixed crystal ratio u of the current diffusion layer 5 is set so that it is as transparent as possible with respect to the emission wavelength. After the epitaxial wafer 10 is formed in this manner, AuGe (weight ratio 3% Ge) for the n-type electrode 11 is vapor-deposited on the entire back surface of the n-type GaAs substrate 1 to a thickness of 3000 Å, and the current diffusion layer 5 is formed. Au / AuZn for the p-type electrode 12 (weight ratio 3%
Zn) / Au in order of 500Å / 2000Å / 2000
After vapor deposition to a thickness of Å, ohmic contact is made by the sintering process. In this state, the metal for the p-type electrode 12 formed on the surface of the current diffusion layer 5 is etched by using a photoetching technique so that the current diffusion layer 5 is exposed at predetermined intervals. The exposed surface of the current diffusion layer 5 serves as a light extraction surface.

Thus, as shown in FIG. 1B, n-type Ga
An n-type electrode 11 is formed on the entire back surface of the As substrate 1, and a plurality of p-type electrodes 12 are formed on the surface of the current diffusion layer 5 at predetermined intervals.

Next, as shown in FIG. 1C, a resist or a CVD film 13 of SiO2 or SiNx is protected on the exposed surface of the current diffusion layer 5 and the p-type electrode 12 during the dicing side surface etching described later. It is formed as a film, and the bottom surface of the wafer 10 in this state is stuck on the adhesive sheet 14. The adhesive sheet 14 is, for example, a vinyl chloride sheet (up to 100 μm thick) coated with an adhesive paste having a thickness of about 10 μm.

Thereafter, as shown in FIG. 1 (d), in a dicing step, after cutting into individual elements (pellets) using a dicing machine such as a diamond blade, in order to remove the remaining crushed layer, As shown in FIG. 1 (e), the entire dicing surface of each element is at least 2 μ
Etch for m or more. In this etching step, a methanol solution containing bromine of 0.1 to 5% is used as an etching solution, and the pellets are stuck on the pressure-sensitive adhesive sheet, and the pellets are immersed in the etching solution for etching for several minutes. To do. The bromine-based etching solution is GaAs, In
The difference in etching rate between the GaAlP and GaAlAs organometallic compounds is very small. When etching is performed using this etching solution, GaAs-InG
Unevenness does not occur at the aAlP interface and the InGaAlP-GaAlAs interface.

After washing the pellet group with pure water, the protective layer 13 is removed as shown in FIG. 1 (f), and the pellet group is removed to remove the chemicals remaining on the adhesive sheet 14 together with the sheet. Transfer to another pressure-sensitive adhesive sheet 14a, and the pelletizing process is completed. As a result, the adhesive sheets are arranged at intervals of 50 to 100 μm and have individual widths of 300 μm.
Some pellets are formed.

When, for example, an LED lamp is manufactured using the pellets manufactured as described above, the following resin molding process is performed. In addition, FIG.
(B), (c) is a sectional process drawing for explaining this resin molding process.

First, each pellet on the pressure-sensitive adhesive sheet 14a is removed by an automated pellet pickup device.
Pluck each one (Pellet 20
The pellet 20 is placed on a dish-shaped frame 21 having leads extending from the center (FIG. 2 (a),
(B)). Then, this pellet 20 is replaced with silver paste 23.
The p-type electrode 1 of the pellet 20 is fixed to the frame 21.
2 and the other straight frame 22 are wire-bonded with a gold wire 24.

Next, the frame 2 is wire-bonded to a predetermined position in the lens-shaped mold 25.
1, 22 are fixed, and a transparent epoxy resin 26 is injected into the mold 25 and baked. After this, mold 25
Is removed to complete the resin molding process.

As described above, in the present embodiment, in the pellet side surface etching step, the bromine-based etching solution having a small difference in etching rate with respect to each organometallic compound of GaAs, InGaAlP, and GaAlAs is used. Even when etching is performed with a large etching amount set above, the GaAs substrate 1 and the cladding layer 2 are
No unevenness is generated at the interface between the clad layer 4 and the current spreading layer 5. As a result, even if the resin molding process as described above is carried out to commercialize an LED lamp or the like, crystal dislocation does not occur, and it is possible to prevent the deterioration of the characteristics of the pellet due to this.

To support this point, the results of the LED lamp life test are shown in FIGS. 3 and 4. The test conditions are a current value of 50 mA, a temperature of 25 ° C., and a humidity of 30%.

As shown in FIG. 3, in the conventional LED lamp using pellets, there is a defective product which is significantly deteriorated at the beginning of energization (around 20 hours), that is, the change in relative light output intensity is up to -40%. Has occurred.

On the other hand, the LED lamp using the pellets of the present example does not deteriorate significantly as shown in FIG. 4 and shows the average relative light output intensity even after 1000 hours. A good product with a change of -5% level can be stably obtained.

In the step of forming the device in pellet form from the wafer after forming the n-type electrode and the p-type electrode, conventionally, first, the InGaAlP double heterojunction layer and the GaAlAs current diffusion layer of the wafer are first etched. After performing the treatment and then the dicing process, the GaAs substrate is etched with an etching amount of about 0.5 to 1.0 μm, which requires two etching processes. After forming the electrode and the p-type electrode, a dicing process is performed, and then an etching process is performed. This reduces the number of etching steps by one compared with the conventional method. In addition, the etching amount is 2
Since it can be performed at a thickness of at least μm, a margin can be taken between the dicing process and the etching process.

[0035]

As described above, according to the first aspect of the present invention, after the dancing process, the entire dicing surface is etched by 2 μm or more with the bromine-based etching solution to be pelletized. In addition, crystal dislocation unlike the conventional one does not occur. This makes it possible to prevent the characteristic deterioration of the pellets and improve the yield.

According to the second invention, the n-type GaAs substrate side and the GaA of the epitaxial wafer in which the InGaAlP double heterojunction layer and the GaAlAs current diffusion layer are grown on the n-type GaAs substrate by the MOCVD method.
An n-type electrode and a p-type electrode are formed on the lAs current diffusion layer side, and a protective film is formed on the GaAlAs current diffusion layer and the p-type electrode, and then at least the n-type GaAs substrate and the InGaAlP double heterojunction layer are formed. And the above G
The aAlAs current diffusion layer is subjected to a dicing process for separating each element, and the entire dicing surface after the dicing process is etched by 2 μm or more with a bromine-based etching solution, and then the protective film is removed. It is possible to achieve the same effect as the first invention and simplify the manufacturing process as compared with the conventional method.

[Brief description of drawings]

FIG. 1 is a manufacturing process chart showing a pelletizing process of an LED according to the present invention.

FIG. 2 is a sectional process drawing for explaining a resin molding process of the above embodiment.

FIG. 3 is a diagram showing a result of a conventional energization life test.

FIG. 4 is a diagram showing the results of an energization life test of this example.

FIG. 5 is a diagram showing a conventional LED pelletizing process.

[Explanation of symbols]

 1 n-type GaAs substrate 2 clad layer 3 active layer 4 clad layer 5 current diffusion layer 10 epitaxial wafer 11 n-type electrode 12 p-type electrode 13 CVD film

Claims (2)

[Claims] 1. An InGaAlP double heterojunction layer and a G formed by MOCVD on an n-type GaAs substrate.
aAlAs current diffusion layer and n formed on the n-type GaAs substrate side and the GaAlAs current diffusion layer side, respectively.
A semiconductor light emitting device that has a p-type electrode and a p-type electrode and is pelletized through a dicing process for separating into elements, wherein the dicing process is performed on at least the wafer-shaped n
Type GaAs substrate, the InGaAlP double heterojunction layer, and the GaAlAs current diffusion layer. The entire dicing surface after the dicing process is etched by a bromine-based etching solution to a depth of 2 μm or more and pelletized. Semiconductor light emitting device. 2. An InGaAlP double heterojunction layer and GaAlAs on an n-type GaAs substrate by MOCVD.
An electrode forming step of forming an n-type electrode and a p-type electrode on the n-type GaAs substrate side and the GaAlAs current diffusion layer side of the epitaxial wafer on which the current diffusion layer is grown, respectively, and on the GaAlAs current diffusion layer and the p-type electrode. After forming a protective film on the substrate, at least the n-type GaAs substrate and the I
nGaAlP double heterojunction layer and the GaAlAs
A dicing step of performing a dicing process for separating the current diffusion layer for each element, and an etching step of removing the protective film after etching the entire dicing surface after the dicing process by 2 μm or more with a bromine-based etching solution. A method of manufacturing a semiconductor light emitting device, which is characterized in that the steps are sequentially performed.