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CN-122028559-A - Mini red light emitting diode and preparation method thereof

CN122028559ACN 122028559 ACN122028559 ACN 122028559ACN-122028559-A

Abstract

The invention relates to the technical field of LED chip manufacturing, in particular to a Mini red light emitting diode and a preparation method thereof. According to the invention, an epitaxial structure is grown by an MOCVD method, a substrate is replaced by bonding, after a table surface and an ISO isolation channel are prepared by etching, an Al 2 O 3 protective layer and an SiO 2 auxiliary protective layer are sequentially deposited, DBR reflecting layers of two groups of laminated layers are evaporated, and an Al-free electrode pad is prepared on the ISO isolation channel by etching, so that a Mini red light emitting diode is obtained. The Mini red light emitting diode electrode prepared by the preparation method has good coverage of each layer, can effectively block water vapor erosion, radically improves electrochemical stability of the electrode by optimizing the laminated metal structure design of the electrode, avoids electrode migration failure, ensures stable photoelectric performance of the device in a harsh environment for 72 hours, and greatly improves reliability and light-emitting efficiency of outdoor flip-chip application.

Inventors

  • XIAO HEPING
  • WU XIANGLONG
  • YAN BAOHUA

Assignees

  • 山东浪潮华光光电子股份有限公司

Dates

Publication Date
20260512
Application Date
20260325

Claims (10)

  1. 1. The preparation method of the Mini red light emitting diode is characterized by comprising the following steps of: (1) Growing an epitaxial wafer on a GaAs substrate, wherein the epitaxial wafer sequentially comprises a GaAs buffer layer, a GaInP corrosion stop layer, an N-GaAs ohmic contact layer, an N-AlGaInP current expansion layer, an N-AlInP limiting layer, an MQW multiple quantum well layer, a P-GaP current expansion layer and a P-GaP ohmic contact layer from bottom to top; (2) Coarsening the surface of the P-GaP ohmic contact layer, depositing SiO 2 , thinning, and carrying out active bonding on the SiO 2 surface and the permanent substrate; (3) Etching with ICP from N Etching the GaAs ohmic contact layer to P The GaP current expansion layer is alloyed to form P ohmic contact; (4) Etching an isolation channel on the epitaxial wafer by adopting an ICP method, and sequentially depositing an Al 2 O 3 layer and an SiO 2 layer; (5) Evaporating two groups of laminated DBR layers on the surface of the epitaxial wafer obtained in the step (4); (6) Etching the DBR layer right above the P ohmic contact and the N ohmic contact by adopting an ICP method to respectively form a P conductive hole and an N conductive hole, and respectively manufacturing an electrode without Al and an electrode pad above the P conductive hole and the N conductive hole; (7) Thinning the permanent substrate, and cutting and splitting to obtain the Mini red light emitting diode.
  2. 2. The method for manufacturing a Mini red light emitting diode according to claim 1, wherein in the step (2), the thickness residual amount of the thinned SiO 2 is 0.8-1 μm, and the Ra value is less than 5nm.
  3. 3. The method for preparing a Mini red light emitting diode according to claim 1, wherein in the step (2), the activated bonding is to clean the SiO 2 surface and the permanent substrate surface by using a strong acid with a ratio of sulfuric acid to hydrogen peroxide to water of 6:2:1, and then bonding for 40-60 min under a pressure of 10000-12000 Kg and a temperature of 400-450 ℃.
  4. 4. The method for preparing a Mini red light emitting diode according to claim 1, wherein in the step (4), the deposition method of the Al 2 O 3 layer is selected from any one of atomic layer deposition, chemical vapor deposition, physical vapor deposition or oxidation method, the thickness is 100-120 nm, and the deposition method of the SiO 2 layer is selected from any one of chemical vapor deposition, atomic layer deposition, physical vapor deposition or thermal oxidation method, and the thickness is 400-500 nm.
  5. 5. The method of claim 1, wherein in the step (5), the first group of two groups of DBR layers is a periodic SiO 2 /Nb 2 O 5 layer, the second group of two groups of DBR layers is a periodic SiO 2 /TiO 2 layer, the vapor deposition method is an ion-assisted deposition method, and the overall thickness is 3-4 μm.
  6. 6. The method of claim 5, wherein the first group of stacked layers has a thickness of 60-90 nm for SiO 2 layers and a thickness of 100-120 nm for Nb 2 O 5 layers, and the periodic logarithm of the group of stacked layers is 6-10 pairs, and the second group of stacked layers has a thickness of 65-90 nm for SiO 2 layers and a thickness of 100-120 nm for TiO 2 layers, and the periodic logarithm of the group of stacked layers is 8-12 pairs.
  7. 7. The method for manufacturing a Mini red light emitting diode according to claim 1, wherein in the step (6), the flow ratio of CF 4 to O 2 in the ICP formulation is (90-96): (10-4), the DBR etching angle is 40-45 degrees, and the size of the conductive hole is 6-10 μm.
  8. 8. The method of claim 1, wherein in the step (7), the electrode is made of Ti/Ni/Pt/Ti/Ni/Au, and the material vapor deposition method is E-beam method.
  9. 9. The method for preparing a Mini red light emitting diode according to claim 8, wherein the thickness of the fifth layer Ni in the material of the electrode is 600-800 nm, and the thicknesses of the other layers are 100-150 nm.
  10. 10. A Mini red light emitting diode, characterized in that it is manufactured by the manufacturing method of Mini red light emitting diode according to any one of claims 1 to 9.

Description

Mini red light emitting diode and preparation method thereof Technical Field The invention relates to the technical field of LED chip manufacturing, in particular to a Mini red light emitting diode and a preparation method thereof. Background The Mini red light emitting diode has become a core light emitting device of an outdoor high-definition flip chip COB display panel by virtue of the advantages of small size, high brightness and high consistency, and is widely applied to display scenes such as outdoor Gao Qingda screens, vehicle-mounted display screens, industrial control screens and the like. The flip chip COB display panel adopts the direct flip chip bonding and integrated packaging process, and has the characteristics of high heat dissipation efficiency, strong structural reliability, adaptation to outdoor severe complex working conditions and the like. In the industry, a high-pressure cooking reliability test (PCT) is generally adopted to verify chips and packaging devices, the test conditions are generally 100-120 ℃, 1-2 standard atmospheric pressures and 100% relative humidity, the devices are required to maintain stable photoelectric performance after continuous test for 72 hours, and the test can intuitively reflect electrode conduction stability, metal interface bonding reliability and chip overall structure tolerance in a damp and hot environment. The electrode structure of the existing Mini red light emitting diode mostly adopts a Ti/Al/Ni/Pt/Au system, and can meet the basic electrical performance requirements under the conventional use environment, wherein Al has the characteristic of high reflectivity, can also improve the light output of a chip, and is a common component in the electrode. In the outdoor long-term damp-heat service process, the electrode has obvious reliability defects that on one hand, external water vapor easily penetrates through gaps between the packaging layer and the chip to invade the inside, electrochemical reaction and ion migration of electrode metal are caused, so that a cavity, a concave or even a broken circuit is formed in the electrode layer, a device dark spot and a dead lamp are directly caused to fail, on the other hand, the interface binding force between the traditional electrode and the epitaxial layer and the bonding layer of the chip is weak, the water vapor easily invades the inside of the device, interlayer stripping and contact degradation are caused, and the failure risk of the device is further aggravated. Aiming at the outdoor severe service environment with high temperature, high pressure and high humidity, the existing Mini red light emitting diode device generally adopts conventional means such as depositing an inorganic oxide passivation layer on the surface of an epitaxial wafer, integrally packaging and protecting the device, and the like to improve the reliability, and part of the prior art is matched with auxiliary protecting means such as depositing an antioxidant film on the surface of a metal electrode. The traditional packaging technology has the problems that the packaging adhesive is easy to age and crack, debond with a chip interface and the like under the working conditions of long-term damp-heat circulation and temperature impact, and the water vapor can still infiltrate into the device along packaging defects to cause electrode ion migration and interface contact degradation. The prior art can not effectively block the water vapor intrusion path, is difficult to inhibit electrode metal migration, is difficult to meet the long-term high-reliability use requirement of the flip chip COB display panel, and becomes a core technical bottleneck for restricting the outdoor application of Mini red light LEDs. Disclosure of Invention Aiming at the technical problems that the existing Mini red light emitting diode is easy to generate electrochemical reaction and metal migration in the outdoor flip-chip application environment with high temperature, high humidity and high pressure, and water vapor is easy to invade the inside of a device, so that the photoelectric performance of the whole device is reduced and even the whole device is completely disabled, the invention provides the Mini red light emitting diode and a preparation method thereof. The technical scheme of the invention is as follows: in a first aspect, the present invention provides a method for preparing a Mini red light emitting diode, including the following steps: (1) Sequentially growing a GaAs buffer layer, a GaInP corrosion stop layer, an N-GaAs ohmic contact layer, an N-AlGaInP current expansion layer, an N-AlInP limiting layer, an MQW multiple quantum well layer, a P-GaP current expansion layer and a P-GaP ohmic contact layer on a GaAs substrate by adopting an MOCVD (metal organic vapor deposition) method, wherein the P-GaP ohmic contact layer is doped with carbon to obtain an epitaxial wafer; (2) The method comprises the steps of roughening the surface of a P-GaP o