JPH098348A - Light emitting diode and method of manufacturing the same - Google Patents

Abstract

(57) [Abstract] [Purpose] In this type of conventional light emitting diode,
When the Zn is diffused in the GaAsP layer, the SiNx film, which is a diffusion prevention film, is likely to be peeled or cracked, which causes problems such as a decrease in product yield and a decrease in luminous efficiency. According to the present invention, a SiO ₂ film 3a having excellent adhesion and crack resistance but a little inferior diffusion performance is used as a first layer, and a SiNx film having excellent diffusion prevention performance but poor adhesion and crack resistance. By making the diffusion prevention layer 3 having 3b as the second layer, both films complement each other in adhesion, crack resistance, and diffusion prevention, and improve all of them, and solve the problems. To do.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode which is a semiconductor light emitting element, and more particularly to a structure of the light emitting diode and a manufacturing method thereof.

[0002]

2. Description of the Related Art FIG. 5 shows an example of the structure of a conventional light emitting diode 90 of this type. The surface of a wafer 91, on which a GaAsP layer 91b is epitaxially grown on a GaAs substrate 91a, is formed by a plasma CVD method or the like. SiNx
A film 92 is formed, and a diffusion pattern 93 is opened in the SiNx film 92 by photolithography.

Subsequently, Zn is thermally diffused from the diffusion pattern 93 to form a P layer 94, and the GaAsP layer 91b is formed.
A PN junction 94a is formed between and. Further, a P electrode 95 is formed of Al on the diffusion pattern 93, and an N electrode 96 is formed of Au on the back surface of the wafer 91.

The structure described above is formed on the wafer 91.
A plurality of units are provided, and each of them is divided into chips in the subsequent steps, and further mounted on a lead frame or the like on the N electrode 96 side, and then the P electrode 95 of Au wire is mounted. The element shape is obtained by bonding.

[0005]

However, in the light emitting diode 90 having the above-described conventional structure, the SiNx film 92 used as the diffusion preventing film is the GaAsP layer 9
It has poor adhesion to 1b, is liable to peel, and has high internal stress of the film itself.
It is apt to cause cracks during the process of heating at ~ 500 ° C.

This means that Zn is entangled from a portion exfoliated at the time of diffusion of the P layer 94 by thermal diffusion of Zn as described above, or Zn is infiltrated from cracks to cause PN junction 94a. Is lost and the luminous efficiency is reduced, which causes problems in performance.

Further, as shown in FIG. 6, when the P electrode 95 is formed, the SiNx film 92 also insulates the P electrode 95 from the GaAsP layer 91b, so that the SiNx film 92 is peeled off. When a crack is generated, the P electrode 95 and the GaAsP layer 91b come into contact with each other, and a short circuit or a leak occurs between the PN junction 94a.

Therefore, when a short circuit occurs in the PN junction 94a, the light emitting diode 90 becomes a non-defective complete defect, which causes a production problem such as a decrease in yield. When a leak occurs, the light emitting diode 90 is parallel to the PN junction 94a. A resistance circuit is connected, and a current value increases, resulting in a decrease in light emission efficiency, which causes a performance problem, and it is a problem to solve these problems.

[0009]

The present invention provides GaAsP as a concrete means for solving the above-mentioned conventional problems.
A method of manufacturing a light emitting diode, comprising forming a diffusion prevention film on a layer, forming a diffusion pattern having an opening in the diffusion prevention film, and thermally diffusing Zn from the diffusion pattern to form a PN junction. The diffusion prevention film is formed by forming a SiO ₂ film as a first layer that adheres to the GaAsP layer, and as a second layer by laminating a SiNx film on the SiO ₂ film. The problem is solved by providing a method for manufacturing a light emitting diode, which is characterized by forming a diffusion pattern.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described in detail based on an embodiment shown in the drawings. The method for manufacturing the light emitting diode 1 according to the present invention will be described below in the order of steps. First, as shown in FIG. 1, plasma CVD is performed on a wafer 2 in which a GaAsP layer 2b is epitaxially grown on a GaAs substrate 2a.
Of the SiO ₂ film 3a by a film forming method such as a sputtering method or a sputtering method.
It is formed as a first layer with a film thickness of 00 to 500Å.

The SiO ₂ film 3a formed at this time
Is dense, and it is necessary to have a film quality that does not allow Zn to pass through in the diffusion step to be performed later. For example, the SiO ₂ film 3a formed by the magnetron sputtering method has a refractive index of about 1.46 and is sufficiently dense for the above purpose. It is confirmed by the result of the experiment by the inventor to make the present invention.

Next, in the present invention, as shown in FIG. 2, plasma CV is formed in a state of being in close contact with the upper surface of the SiO ₂ film 3a.
The SiNx film 3b is formed in a film thickness of 500 to 10 by a film forming method such as D method.
It is formed as a second layer with a film thickness of 00Å. Therefore, in the present invention, the diffusion preventive film 3 is composed of two layers of the SiO ₂ film 3a and the SiNx film 3b.

Subsequently, a diffusion pattern 4 is opened in the diffusion prevention film 3 by photolithography as shown in FIG. Here, since the diffusion prevention film 3 is formed by forming the SiNx film 3b on the upper surface of the SiO ₂ film 3a as described above, when the diffusion pattern 4 is formed, the above-mentioned opening surface is formed. The two-layer structure is shown as a cross section.

Then, Zn is thermally diffused from the diffusion pattern 4 to form a P layer 5, and a PN junction 5a is formed between the P layer 5 and the GaAsP layer 2b. Is formed, the N electrode 7 is formed on the back surface side of the wafer 2 by Au, and the wafer is individually cut to complete the light emitting diode 1 of the present invention as shown in FIG.

Next, the operation and effect of the light emitting diode 1 of the present invention having the above structure will be described. First, the SiO ₂ film 3 forming the diffusion prevention film 3 according to the present invention
General properties of the Si and the SiNx film 3b will be described. One of the SiO ₂ films 3a is the GaAsP layer 2b.
Although it is excellent in the adhesiveness to and the crack resistance to the ambient heat change, it tends to be slightly inferior in the diffusion prevention property when the Zn is thermally diffused.

On the other hand, the SiNx film 3b has a dense film surface and is excellent in diffusion prevention, but on the other hand, GaAsP.
The adhesion to the layer 2b is considerably poor, and peeling often occurs, and cracks tend to easily occur due to temperature changes such as heating during the process.

Therefore, as in the present invention, the GaAsP layer 2b is formed.
By providing the SiO ₂ film 3a as a first layer in close contact with, the adhesion to the GaAsP layer 2b is enhanced and peeling is prevented. The SiO ₂ film 3a is made of SiNx.
Since the adhesiveness to the film 3b is also excellent, peeling does not occur even in the SiNx film 3b formed by covering the SiO ₂ film 3a in a later step.

When the Zn is thermally diffused, the SiO ₂ film 3a and the SiNx film 3 have the function of preventing diffusion.
The b and performs an action to complement each other, even if they occur and pinholes in the SiO ₂ film 3a, with SiNx film 3b that the SiO ₂ film 3a provided covering, more excellent denseness The above-mentioned pinhole or the like is closed to prevent an abnormal state, that is, diffusion in a shape different from that of the diffusion pattern 4 from being performed.

On the other hand, the above-mentioned Si is subjected to a thermal process such as an alloying process.
Even when a crack is generated in the Nx film 3b, the SiNx
SiO ₂ provided under the film 3b and having excellent crack resistance
The film 3a prevents the progress of cracks and the cracks do not reach the GaAsP layer 2b. Therefore, also in this case, diffusion in an abnormal state is prevented.

However, when the pinhole generated in the SiO ₂ film 3a and the crack generated in the SiNx film 3b are located at the same position, the above-mentioned diffusion in an abnormal state cannot be prevented. The coincidence between the two defects is extremely low in probability, the possibility of occurrence thereof is negligible, and it is assumed that normal diffusion is performed with a significantly higher probability than in the case of a single layer of the SiNx film 3b.

Furthermore, the fact that the diffusion preventing film 3 is formed in two layers is effective for the P electrode 6 provided after Zn is diffused, and the surface of the P layer 5 is formed. The P electrode 6 provided over the top and the diffusion prevention film 3 is
When the diffusion prevention film 3 comes into contact with the GaAsP layer 2b due to a pinhole, a crack, or the like, a short circuit or a leak occurs between the PN junction 5a.

Here, as described above, the diffusion prevention film 3 is made of Si.
Since it is formed of two layers of the O ₂ film 3a and the SiNx film 3b, and the pinholes and cracks generated in one film are complemented by the other film and no penetration occurs in the entire diffusion prevention film 3, This will almost completely prevent the occurrence of short circuits and leaks.

The prevention of the above-mentioned short circuit is effective in improving the yield in the production process of the light emitting diode 1, and the prevention of the leakage is caused by the leakage caused by the crack which is more or less generated in the conventional diffusion prevention film. This is effective in preventing the deterioration of the luminous efficiency and improving the performance of the light emitting diode 1.

According to the results of trial production and experiments by the inventor of the present invention, the diffusion barrier film 3 is formed of two layers, that is, the SiO ₂ film 3a and the SiNx film 3b. It has been confirmed that the impact resistance is also improved and, for example, the number of accidents such as the diffusion prevention film 3 being destroyed by the impact when the Au wire is bonded to the P electrode 6 is reduced.

[0025]

As described above, according to the present invention, a SiO ₂ film having excellent adhesion and crack resistance, but slightly inferior in diffusion prevention performance is used as the first layer, and excellent diffusion prevention performance but adhesion By using the SiNx film, which is inferior in crack resistance, as the diffusion prevention layer having the second layer, both films complement each other in adhesion, crack resistance, and diffusion prevention.
All of them are to be improved, accurate diffusion can be performed at the time of diffusion, and short-circuiting and leakage due to cracks and the like at the time of forming the P electrode are prevented, which is extremely excellent in yield improvement and performance improvement. It has a great effect.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a SiO ₂ film forming step in a diffusion preventing film forming step in a light emitting diode according to the present invention.

FIG. 2 is an explanatory diagram showing a SiNx film forming step during a diffusion preventing film forming step in the same example.

FIG. 3 is an explanatory diagram showing a diffusion pattern forming process in the same embodiment.

FIG. 4 is a sectional view showing an embodiment of a light emitting diode according to the present invention.

FIG. 5 is a cross-sectional view showing a conventional example.

FIG. 6 is an explanatory diagram showing a laid state of a P electrode in a light emitting diode of this type.

[Explanation of symbols]

1 ...... emitting diode 2 ...... wafer 2a ...... GaAs substrate 2b ...... GaAsP layer 3 ...... diffusion preventing film 3a ...... SiO ₂ film 3b ...... SiNx film 4 ...... diffusion pattern 5 ...... P layer 6 ...... P Electrode 7 ... N electrode

Claims (2)

[Claims] 1. A diffusion barrier film is formed on a GaAsP layer,
In a method for manufacturing a light emitting diode, which comprises forming a diffusion pattern having an opening in the diffusion prevention film and thermally diffusing Zn from the diffusion pattern to form a PN junction, the diffusion prevention film is adhered to the GaAsP layer. SiO ₂ as first layer
A film is formed, and SiN is formed on the SiO ₂ film as the second layer.
A method of manufacturing a light emitting diode, comprising forming x films by laminating and forming the diffusion pattern on the diffusion prevention film by a photolithography method. 2. A diffusion preventive film formed on a GaAsP layer, and a diffusion pattern layer Zn formed in the diffusion preventive film.
In the light emitting diode, wherein the diffusion prevention film is the G
a first layer of a SiO ₂ film that adheres to the aAsP layer, and
A light emitting diode comprising a second layer of a SiNx film adhered on an O ₂ film, which is laminated.