CN108389938B

CN108389938B - Non-photoetching preparation method of GaAs-based LED chip

Info

Publication number: CN108389938B
Application number: CN201710063966.3A
Authority: CN
Inventors: 李晓明; 王建华; 闫宝华; 刘琦; 徐现刚
Original assignee: Shandong Inspur Huaguang Optoelectronics Co Ltd
Current assignee: Shandong Inspur Huaguang Optoelectronics Co Ltd
Priority date: 2017-02-03
Filing date: 2017-02-03
Publication date: 2021-01-26
Anticipated expiration: 2037-02-03
Also published as: CN108389938A

Abstract

A non-photoetching preparation method of a GaAs-based LED chip comprises the following steps: (1) growing an epitaxial layer on the GaAs substrate; (2) preparing a patch on which electrode holes are arranged; (3) pasting the patch prepared in the step (2) on the GaAs-based LED epitaxial layer prepared in the step (1); (4) depositing an Au film on the patch by evaporation, wherein the Au film at the electrode hole is in contact with the epitaxial layer to form a P electrode; (5) taking down the patch and carrying out annealing treatment to obtain a P electrode; (6) and thinning the GaAs substrate and growing an N electrode. According to the method, the patch with the electrode hole is designed, the patch and the GaAs-based LED epitaxial wafer are attached together to prepare the P electrode, the P electrode is obtained by directly performing electrode evaporation without photoetching, the problem of electrode size fluctuation caused by chemical corrosion or photoresist in the prior art of photoetching preparation of the P electrode of the GaAs-based LED chip is solved, photoelectric parameter fluctuation is avoided, the production efficiency is improved, the process is simple and convenient, and the method is suitable for large-scale production.

Description

Non-photoetching preparation method of GaAs-based LED chip

Technical Field

The invention relates to a preparation method of a GaAs-based LED chip without photoetching, belonging to the technical field of photoelectrons.

Background

The LED is used as a new illumination light source in the 21 st century, and under the same brightness, the power consumption of a semiconductor lamp is only l/10 of that of a common incandescent lamp, but the service life of the semiconductor lamp can be prolonged by 100 times. The LED device is a cold light source, has high light efficiency, low working voltage, low power consumption and small volume, can be packaged in a plane, is easy to develop light and thin products, has firm structure and long service life, does not contain harmful substances such as mercury, lead and the like in the light source, does not have infrared and ultraviolet pollution, and does not generate pollution to the outside in production and use. Therefore, the semiconductor lamp has the characteristics of energy conservation, environmental protection, long service life and the like, and like the transistor replaces the electron tube, the semiconductor lamp replaces the traditional incandescent lamp and the traditional fluorescent lamp, and the trend is also great. From the viewpoint of saving electric energy, reducing greenhouse gas emission and reducing environmental pollution, the LED serving as a novel lighting source has great potential for replacing the traditional lighting source.

In the last 50 s of the century, group III-V semiconductors, typified by GaAs, have rapidly risen in the field of semiconductor light emission under the efforts of a number of well-known Research institutes, typified by IBM Thomas j. With the advent of Metal Organic Chemical Vapor Deposition (MOCVD) technology, high quality III-V semiconductor growth has broken through the technological barrier, and semiconductor light emitting diode devices of various wavelengths have been in the market in succession. Compared with the existing light-emitting devices, the semiconductor light-emitting diode has the characteristics of high efficiency, long service life, strong mechanical impact resistance and the like, and is considered as a new generation of lighting device worldwide. However, since the refractive index of group III-V semiconductors is generally high (GaP: 3.2), this results in that the light emitted by the light emitting region of the LED is subject to the phenomenon of total interfacial reflection when exiting through the chip surface into the air, and only a very small fraction of the light can exit to the outside of the device (GaP is about 2.4%). The low external quantum efficiency of the LED caused by the interface total reflection phenomenon is a main reason for restricting the LED to replace the existing lighting device.

The GaAs-based LED chip P electrode is generally prepared by a wet etching method, the wet etching method is easy to generate electrode lateral etching, the size of an electrode pattern can generate certain fluctuation, the light emitting efficiency difference at different positions is large due to the unstable size of the P electrode, and large-area test is needed to confirm related photoelectric parameters.

The method for preparing the P electrode on the GaAs-based light-emitting diode chip disclosed in Chinese patent document CN 105006507A is to coat a negative photoresist on the GaP rough surface of a GaAs-based epitaxial wafer, then carry out photoetching, reserve an electrode pattern of the negative photoresist on the surface, evaporate an Au film on the surface of the GaAs-based epitaxial wafer, strip the metal except the electrode pattern off, and obtain the P electrode on the GaAs-based light-emitting diode chip.

In a method for preparing a p-electrode of an LED chip by chemical plating, which is disclosed in chinese patent document CN102332509A, nano metal particles are prepared on a p-GaN layer of an LED epitaxial wafer at intervals, and the p-GaN layer is etched, so that the surface of the p-GaN layer is of a nano structure; plating an activation solution on the activation region of the LED epitaxial wafer by using a mask to activate the activation region of the LED epitaxial wafer, and then removing the mask; placing the LED epitaxial wafer into chemical plating solution, and chemically plating metal in the activation region of the LED epitaxial wafer while dissolving the nano metal particles outside the activation region to form a metal substrate; the metal is a metal capable of inducing reduction of gold; and placing the LED epitaxial wafer into a chemical gold plating solution, and automatically depositing gold on the metal substrate to obtain the p electrode. The method mainly adopts a chemical coating mode to prepare the P electrode of the LED chip, and the nano metal particles are easy to remain in the rough surface to influence light, so that the electrode preparation of the GaAs-based LED chip can not be realized.

The method for manufacturing the GaN-based LED electrode by twice photoetching with ITO as the P electrode, disclosed in Chinese patent document CN1885569, is a method for manufacturing the P electrode on the GaN-based LED by ITO, and is mainly suitable for manufacturing the GaN-based LED electrode, and has great influence on the batch production efficiency due to the difference between a GaN-based LED chip and a GaAs-based LED chip by twice photoetching.

Disclosure of Invention

Aiming at the problem that the P electrode in the existing GaAs-based LED chip is easy to damage in the preparation process of the P electrode, the invention provides a preparation method of the GaAs-based LED chip without photoetching.

The invention discloses a non-photoetching preparation method of a GaAs-based LED chip, wherein the GaAs-based LED chip comprises an N electrode, a GaAs substrate, an epitaxial layer and a P electrode, and the method comprises the following steps:

(1) growing an epitaxial layer on the GaAs substrate;

(2) preparing a patch on which electrode holes are arranged;

(3) pasting the patch prepared in the step (2) on the GaAs-based LED epitaxial layer prepared in the step (1);

(4) depositing an Au film on the patch by evaporation, wherein the Au film at the electrode hole is in contact with the epitaxial layer to form a P electrode;

(5) taking down the patch and carrying out annealing treatment to obtain a P electrode;

(6) and thinning the GaAs substrate and growing an N electrode.

The diameter of the electrode hole in the step (2) is 70-100 μm.

And (3) in the step (2), the electrode hole is a conical hole. Therefore, the evaporated metal can not be evaporated on the side wall of the electrode hole, the patch can be simply taken off subsequently, the patch can be repeatedly utilized, and a better stable and consistent P electrode pattern can be obtained.

The thickness of the patch in the step (2) is 80-200 μm.

The Au film deposition in the step (4) is carried out at the temperature of 100-200 ℃.

The thickness of the Au film in the step (4) is 1.5-3 μm.

The annealing temperature in the step (5) is 450-550 ℃.

In the step (6), the steps of thinning the GaAs substrate and growing the N electrode are as follows:

firstly, thinning the GaAs substrate to the thickness of 150-220 mu m;

and secondly, growing an Au film with the thickness of 0.35-0.6 mu m on the back of the thinned GaAs substrate to be used as an N electrode.

The invention adopts a method different from the traditional process to prepare the P electrode, designs the paster with orderly arranged electrode holes, pastes the paster and the GaAs-based LED epitaxial wafer together, prepares the P electrode through the electrode holes on the paster, directly carries out electrode evaporation to obtain the P electrode without photoetching, avoids the problem of electrode size fluctuation caused by chemical corrosion or photoresist in the P electrode of the GaAs-based LED chip prepared by photoetching in the prior art, improves the production efficiency, avoids the influence of photoelectric parameter fluctuation caused by electrode size fluctuation in the electrode preparation process by adopting a conventional method, avoids the damage to the electrode surface in the electrode preparation process, ensures that the electrode graph is easier to weld wires, has simple and convenient flow and is suitable for large-scale production.

Drawings

Fig. 1 is a schematic structural view of a GaAs-based LED chip.

Figure 2 is a cross-sectional view of a patch of the present invention having electrode holes.

Fig. 3 is a cross-sectional view of the Au film deposited in step (4) of the present invention.

In the figure: 1. GaAs substrate, 2 epitaxial layer, 3, P electrode, 4, N electrode, 5, paster, 6, electrode hole, 7 and Au film.

Detailed Description

The invention relates to a preparation method of a GaAs-based LED chip without photoetching, which is shown in figure 1 and comprises an N electrode 4, a GaAs substrate 1, an epitaxial layer 2 and a P electrode 3 from bottom to top in sequence.

The preparation method of the GaAs-based LED chip shown in FIG. 1 comprises the following specific steps.

(1) An epitaxial layer 2 is grown on a GaAs substrate 1 by a conventional Metal Organic Chemical Vapor Deposition (MOCVD) method.

(2) A patch 5 having regularly arranged (with uniform intervals, periodic arrangement of LED chips prepared as needed) electrode holes 6 is prepared, as shown in fig. 2, the electrode holes 6 being prepared by a conventional photolithography. The patch 5 has a thickness of 80-200 μm. The patch 5 is made of common PVC material.

The electrode hole 6 is a tapered hole with a small upper part and a large lower part. The diameter of the electrode hole 6 (the diameter of the upper end of the electrode hole 6) is 70 to 100 μm. The electrode holes 6 are designed in a conical shape, so that metal cannot be evaporated on the side walls of the electrode holes, and the patches 5 can be simply taken off in the subsequent step (3). The patch 5 can be repeatedly utilized, the production efficiency is greatly improved, the use of various metal corrosive liquids is reduced, the preparation cost of the LED chip is reduced, and the process is simple and convenient and is suitable for large-scale production.

(3) And (3) sticking the patch 5 with the electrode hole 6 prepared in the step (2) on the GaAs-based epitaxial layer 2 prepared in the step (1), and fixing the patch on a planet carrier of evaporation equipment through a clamp of the evaporation equipment.

(4) An Au film 7 with a thickness of 1.5-3 μm is deposited on the surface of the patch at 100-200 ℃. As shown in fig. 3.

Because of the orderly arranged electrode holes 6, the Au film 7 at the electrode holes 6 falls on the epitaxial layer 2 to form the P electrode 3, and the Au film of the rest area is evaporated on the patch 5.

(5) The patch 5 was removed and annealed at 450 ℃ -.

The P electrode 3 is prepared by the simplest method, the patches 5 with the regularly arranged electrode holes are used, the conventional metal deposition method is adopted, and the patches with the electrode holes are utilized, so that the stability of the electrode pattern is improved, the electrode pattern with better size consistency is obtained, and the damage to the surface of the electrode is avoided.

(6) The GaAs substrate is thinned and an N electrode 4 (see figure 1) is grown conventionally, and the specific steps are as follows:

conventionally thinning the GaAs substrate 2, wherein the thickness of the thinned GaAs substrate is 150-220 mu m;

and secondly, growing an Au film of 0.35-0.6 mu m on the back of the thinned GaAs substrate to serve as an N electrode 4.

Claims

1. A non-photoetching preparation method of a GaAs-based LED chip is characterized by comprising the following steps:

(1) growing an epitaxial layer on the GaAs substrate;

(2) preparing a patch with an array of electrode holes, wherein the electrode holes are conical holes, the diameter of each electrode hole is 70-100 mu m, the thickness of the patch is 80-200 mu m, and the patch is made of a common PVC material;

(3) pasting the patch prepared in the step (2) on the GaAs-based LED epitaxial layer prepared in the step (1), and fixing the patch on a planet carrier of evaporation equipment through a clamp of the evaporation equipment;

(6) and thinning the GaAs substrate and growing an N electrode.

2. The non-photolithography method for preparing GaAs-based LED chip as claimed in claim 1, wherein the Au film deposition in the step (4) is performed at a temperature of 100-200 ℃.

3. The non-photolithography method for preparing GaAs-based LED chips according to claim 1, wherein the thickness of the Au film in the step (4) is 1.5 to 3 μm.

4. The non-photoetching preparation method of GaAs-based LED chip as claimed in claim 1, wherein the annealing treatment temperature in the step (5) is 450-550 ℃.

5. The non-photoetching preparation method of a GaAs-based LED chip as claimed in claim 1, wherein in the step (6), the steps of thinning the GaAs substrate and growing the N electrode are as follows:

firstly, thinning the GaAs substrate to the thickness of 150-220 mu m;