CN109755367B

CN109755367B - Coarsening method of reversed polarity AlGaInP quaternary LED chip

Info

Publication number: CN109755367B
Application number: CN201711081003.2A
Authority: CN
Inventors: 李晓明; 闫宝华; 刘琦; 汤福国; 陈康; 郑兆河; 肖成峰
Original assignee: Shandong Inspur Huaguang Optoelectronics Co Ltd
Current assignee: Shandong Inspur Huaguang Optoelectronics Co Ltd
Priority date: 2017-11-07
Filing date: 2017-11-07
Publication date: 2021-01-05
Anticipated expiration: 2037-11-07
Also published as: CN109755367A

Abstract

A coarsening method of a reversed polarity AlGaInP quaternary LED chip comprises the following steps: a) etching off the GaAs substrate and etching off the epitaxially grown barrier layer GaInP; b) evaporating a GeAu film, and photoetching to obtain an ohmic contact electrode pattern; c) removing the positive photoresist to obtain an N-surface ohmic contact pattern; d) a coarsening protection pattern is prepared through photoetching; e) forming an N-type coarsening layer; f) and carrying out wet coarsening on the N-type AlGaInP layer, and removing the positive photoresist to obtain an N-type AlGaInP coarsened surface. The substrate and the barrier layer of the AlGaInP quaternary LED chip which is bonded are all corroded and removed, the surface is coated with a GeAu film serving as an N-type ohmic contact electrode in an evaporation mode, a coarsening protection pattern is prepared on the surface, the N-type AlGaInP layer without coarsening protection is subjected to surface coarsening treatment in an ICP (inductively coupled plasma) etching and wet coarsening mode under the action of the coarsening protection pattern, the problem of unstable coarsening effect of the reversed polarity AlGaInP quaternary LED chip is solved, the light emitting efficiency is increased, and the quality of the chip is improved.

Description

Coarsening method of reversed polarity AlGaInP quaternary LED chip

Technical Field

The invention relates to the technical field of photoelectrons, in particular to a coarsening method of a reverse polarity AlGaInP quaternary LED chip.

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.

AlGaInP material systems were originally used to fabricate visible light laser diodes and were first proposed by japanese researchers in the mid-eighties of the twentieth century. In the LED and LD devices in that period, ga0.5in0.5p matched with a GaAs substrate is generally used as an active light emitting region, and the light emitting wavelength is 650 nm, and the LED and LD devices are widely used in a quaternary laser pen, a DVD, and a player. Later, researchers found that introducing an Al component into GaInP could shorten the emission wavelength further, but if the Al content is too high, the emission efficiency of the device would be decreased sharply, because AlGaInP becomes an indirect bandgap semiconductor when the Al content in GaInP exceeds 0.53, so AlGaInP materials are generally used only to prepare LED devices with emission wavelengths above 570 nm. In 1997, AlGaInP-based LEDs of the first Multiple Quantum Well (MQW) composite bragg reflector (DBR) structure were produced in the world, and LED devices designed based on this structure still occupied a large share of the low-end market of LEDs to date.

The method comprises the steps of preparing an ohmic contact pattern at the present stage by adopting a chemical corrosion method, corroding the heavily doped layer by using Au film corrosive liquid to cause that an n-type layer part is exposed in the air to cause oxidation, and finally causing coarsening fluctuation of the n-type layer, so that the influence of the part is reduced, and the n-type coarsening effect of the reverse polarity quaternary LED chip is more stable to be the main problem at the present stage.

Chinese patent document CN101494272 provides a manufacturing method capable of coarsening the surface of a P-GaN layer of an LED, which comprises the steps of firstly growing an n-GaN layer, a quantum well layer, a P-GaN layer and a non-doped coarsening GaN layer on a semiconductor substrate in sequence, and then etching the non-doped coarsening GaN layer by adopting an ICP (inductively coupled plasma) or an ion dry method to transfer the shape of the coarsening surface of the non-doped coarsening GaN layer to the P-GaN layer, so that the surface of the P-GaN layer is coarsened. However, the method is suitable for roughening the surface of the P-GaN, and the chip may leak electricity and the yield is reduced due to the fact that the method completely depends on ICP etching roughening.

Chinese patent document CN104078535 provides a method for roughening a side wall of a reversed-polarity AlGaInP-based LED, which comprises exposing and developing a mesa patterned epitaxial wafer of the reversed-polarity AlGaInP-based LED by using a conventional photolithography process to form a periodic edge pattern around the mesa patterned epitaxial wafer; reuse of saturated Br-containing compounds₂The epitaxial wafer developed by the deionized water is corroded, and after the corrosion is finished, cleaning and photoresist removing are carried out according to a conventional process, so that the side wall of the LED is coarsened.

The AlGaInP-based LED with a roughened GaP surface and the manufacturing method thereof disclosed in chinese patent document CN 105428485a are obtained by directly immersing an epitaxial wafer in a roughening solution to roughen the surface of an exposed p-type GaP window layer, thereby achieving the effect of roughening the surface of the p-type GaP window layer by wet etching; an ITO film was deposited as a current spreading layer. The method is mainly used for coarsening the GaP of the epitaxial layer, has higher requirements on epitaxial growth and the surface of the epitaxial layer, and is not easy for large-scale production.

Disclosure of Invention

In order to overcome the defects of the technology, the invention provides the coarsening method of the reversed polarity AlGaInP quaternary LED chip, which has simple manufacturing process, effectively improves the light extraction efficiency and is more stable.

The technical scheme adopted by the invention for overcoming the technical problems is as follows:

a coarsening method of a reversed polarity AlGaInP quaternary LED chip comprises the following steps:

a) etching off the GaAs substrate and etching off the epitaxially grown barrier layer GaInP of the AlGaInP quaternary LED chip after bonding;

b) evaporating a GeAu film on the AlGaInP quaternary LED chip processed in the step a) in an electron beam evaporation mode, coating positive photoresist on the surface of the GeAu film, and photoetching to obtain an ohmic contact electrode pattern;

c) removing the positive photoresist to obtain an N-surface ohmic contact pattern;

d) coating positive photoresist on the surface of the AlGaInP quaternary LED chip processed in the step c), and preparing a coarsening protection pattern by photoetching;

e) removing the heavily doped layer without the coarsening protection region of the AlGaInP quaternary LED chip by ICP etching and etching the heavily doped layer to the N-type AlGaInP layer to form an N-type coarsening layer;

f) and carrying out wet coarsening on the N-type AlGaInP layer, and removing the positive photoresist to obtain an N-type AlGaInP coarsened surface.

Preferably, the etching solution used in the etching treatment of the GaAs substrate in step a) is a mixed solution of ammonia water, hydrogen peroxide, and water, where the ammonia water: hydrogen peroxide: the volume ratio of water is 1:2: 6.

Preferably, in the step a), during the GaInP etching treatment of the barrier layer, the GaInP etching solution is hydrochloric acid: 5:3 water volume ratio.

Preferably, the GaAs substrate etching time in the step a) is 20-40 minutes, and the GaInP etching time is 1 minute, 30 seconds and 3 minutes.

Preferably, the AlGaInP quaternary LED chip in the step a) is washed in pure water after the GaAs substrate is etched off, and then washed clean, and then put in a GaInP corrosive liquid to etch off GaInP.

Preferably, the thickness of Ge in the GeAu film in the step b) is 0.01-0.02 μm, and the thickness of Au is 0.4-0.55 μm.

Preferably, the temperature of the GeAu plating film in the step b) is 150-250 ℃.

Preferably, the thickness of the positive photoresist coated on the surface of the GeAu film in the step b) is 0.9-1.8 μm, and the thickness of the positive photoresist coated on the surface of the AlGaInP quaternary LED chip in the step d) is 3.5-4.5 μm.

Preferably, the wet roughening of the N-type AlGaInP layer in step f) comprises:

f1) preparing a roughening solution by using phosphoric acid with the mass concentration of 96%, hydrochloric acid with the mass concentration of 36.5% and pure water according to the volume ratio of 1:3:5 or 2:5: 10;

f2) and placing the AlGaInP quaternary LED chip into roughening liquid to roughen the N-type AlGaInP layer exposed from the roughening protection region, removing residual heavily-doped layer particles under the action of phosphoric acid, and removing the positive photoresist to obtain an N-type AlGaInP roughened surface.

Preferably, the temperature for wet coarsening in step f) is between 28 and 36 ℃ and the time is between 1 minute and 30 seconds and 2 minutes and 30 seconds.

The invention has the beneficial effects that: the substrate and the barrier layer of the AlGaInP quaternary LED chip which is bonded are all corroded and removed, the surface is coated with a GeAu film serving as an N-type ohmic contact electrode in an evaporation mode, a coarsening protection pattern is prepared on the surface, the N-type AlGaInP layer without coarsening protection is subjected to surface coarsening treatment in an ICP (inductively coupled plasma) etching and wet coarsening mode under the action of the coarsening protection pattern, the problem of unstable coarsening effect of the reversed polarity AlGaInP quaternary LED chip is solved, the light emitting efficiency is increased, and the quality of the chip is improved. Through conventional ICP etching and preparation of roughening solution of phosphoric acid and hydrochloric acid, N-type AlGaInP can be roughened, residual particles in a heavily doped layer can be removed, the operation is simple and convenient, a more stable roughened surface can be obtained, and the method is suitable for large-scale production.

Drawings

FIG. 1 is a cross-sectional view of a reverse polarity LED quad-chip made in accordance with the present invention;

FIG. 2 is a cross-sectional view of a reverse polarity LED quad-chip made in step a) of the present invention;

FIG. 3 is a cross-sectional view of a reverse polarity LED quad-chip made in step b) of the present invention;

FIG. 4 is a cross-sectional view of a reverse polarity LED quad-chip made in step c) of the present invention;

in the figure, 1, a substrate, 2, a bonding layer, an epitaxial layer, 3, an N-type AlGaInP layer, 4, a heavily doped layer, 5, a GeAu film, 6, a coarsening protection pattern, 7 and residual particles of the heavily doped layer are shown.

Detailed Description

The invention will be further described with reference to fig. 1 to 4.

a) the bonded AlGaInP quaternary LED chip with the substrate 1, the bonding layer and the epitaxial layer 2 is etched to remove the GaAs substrate and the epitaxially grown barrier layer GaInP, as shown in fig. 2.

b) Evaporating a GeAu film 5 on the AlGaInP quaternary LED chip processed in the step a) in an electron beam evaporation mode, coating positive photoresist on the surface of the GeAu film, and photoetching to obtain an ohmic contact electrode pattern. As shown in fig. 3.

c) And removing the positive photoresist to obtain an N-surface ohmic contact pattern.

d) Coating positive photoresist on the surface of the AlGaInP quaternary LED chip processed in the step c), and photoetching to obtain a coarsening protection pattern 6.

e) The heavily doped layer 4 without the coarsening protection region of the AlGaInP quaternary LED chip is removed through ICP etching and etched to the N-type AlGaInP layer 3 to form an N-type coarsening layer, as shown in figure 4.

f) The N-type AlGaInP layer 3 is roughened by a wet method, and the positive photoresist is removed to obtain an N-type AlGaInP roughened surface, as shown in figure 1.

The substrate and the barrier layer of the AlGaInP quaternary LED chip which is bonded are all corroded and removed, a GeAu film is evaporated on the surface to be used as an N-type ohmic contact electrode, a coarsening protection pattern is prepared on the surface, the N-type AlGaInP layer 3 without coarsening protection is subjected to surface coarsening treatment in an ICP (inductively coupled plasma) etching and wet coarsening mode under the action of the coarsening protection pattern 6, the problem of unstable coarsening effect of the reversed polarity AlGaInP quaternary LED chip is solved, the light emitting efficiency is increased, and the quality of the chip is improved. Through conventional ICP etching and preparation of roughening solution of phosphoric acid and hydrochloric acid, N-type AlGaInP can be roughened, residual particles 7 of a heavily doped layer in the heavily doped layer 4 can be removed, the operation is simple and convenient, a more stable roughened surface can be obtained, and the method is suitable for large-scale production.

Example 1:

further preferably, the etching solution used in the etching treatment of the GaAs substrate in step a) is a mixed solution of ammonia water, hydrogen peroxide, and water, where the mixed solution contains: hydrogen peroxide: the volume ratio of water is 1:2: 6.

Example 2:

further preferably, in the step a), during the GaInP etching treatment of the barrier layer, the GaInP etching solution is hydrochloric acid: 5:3 water volume ratio.

Example 3:

further preferably, the etching time of the GaAs substrate in the step a) is 20-40 minutes, and the etching time of the GaInP is 1 minute, 30 seconds and 3 minutes.

Example 4:

preferably, the AlGaInP quaternary LED chip in step a) is washed in pure water after the GaAs substrate is etched away, and then washed clean, and then put in a GaInP etching solution to etch away GaInP.

Example 5:

further preferably, the thickness of Ge in the GeAu film in step b) is 0.01-0.02 μm, and the thickness of Au is 0.4-0.55 μm.

The temperature of the film plating in the GeAu in the step b) is 150-250 ℃.

Example 6:

further preferably, the thickness of the positive photoresist coated on the surface of the GeAu film in the step b) is 0.9-1.8 μm, and the thickness of the positive photoresist coated on the surface of the AlGaInP quaternary LED chip in the step d) is 3.5-4.5 μm.

Example 7:

further preferably, the wet roughening of the N-type AlGaInP layer in step f) comprises:

Example 8:

it is further preferred that the temperature for wet coarsening in step f) is 28-36 ℃ and the time is 1 min 30 s-2 min 30 s.

Claims

1. A coarsening method of a reversed polarity AlGaInP quaternary LED chip is characterized by comprising the following steps:

2. The coarsening method of the reversed polarity AlGaInP quaternary LED chip of claim 1, wherein: the etching solution used in the etching treatment of the GaAs substrate in the step a) is a mixed solution of ammonia water, hydrogen peroxide and water, wherein the ammonia water in the mixed solution is as follows: hydrogen peroxide: the volume ratio of water is 1:2: 6.

3. The coarsening method of the reversed polarity AlGaInP quaternary LED chip of claim 1, wherein: during the GaInP corrosion treatment of the barrier layer in the step a), the GaInP corrosion solution is hydrochloric acid: 5:3 water volume ratio.

4. The coarsening method of the reversed polarity AlGaInP quaternary LED chip of claim 1, wherein: in the step a), the GaAs substrate etching time is 20-40 minutes, and the GaInP etching time is 1 minute, 30 seconds to 3 minutes.

5. The method for coarsening the reversed polarity AlGaInP quaternary LED chip according to any one of claims 1 to 4, wherein: and b) after the GaAs substrate is corroded, putting the AlGaInP quaternary LED chip in the step a) into pure water for washing, and putting the AlGaInP quaternary LED chip into GaInP corrosive liquid for corroding the GaInP after the AlGaInP quaternary LED chip is washed clean.

6. The coarsening method of the reversed polarity AlGaInP quaternary LED chip of claim 1, wherein: the thickness of Ge in the GeAu film in the step b) is 0.01-0.02 μm, and the thickness of Au is 0.4-0.55 μm.

7. The coarsening method of the reversed polarity AlGaInP quaternary LED chip of claim 1, wherein: the temperature of the film plating in the GeAu in the step b) is 150-250 ℃.

8. The coarsening method of the reversed polarity AlGaInP quaternary LED chip of claim 1, wherein: the thickness of the positive photoresist coated on the surface of the GeAu film in the step b) is 0.9-1.8 μm, and the thickness of the positive photoresist coated on the surface of the AlGaInP quaternary LED chip in the step d) is 3.5-4.5 μm.

9. The coarsening method of the reversed polarity AlGaInP quaternary LED chip of claim 1, wherein: the step of carrying out wet coarsening on the N-type AlGaInP layer in the step f) comprises the following steps:

10. The coarsening method of the reversed polarity AlGaInP quaternary LED chip of claim 9, wherein: the temperature of the wet coarsening in the step f) is 28-36 ℃, and the time is 1 minute 30 seconds-2 minutes 30 seconds.