High light efficiency flip LED chip and preparation method thereof

Abstract

The application discloses a high-light-efficiency flip LED chip and a preparation method thereof. The chip structure comprises, from bottom to top, a sapphire pattern substrate, a GaN nucleation layer, an n-GaN layer, a current expansion layer, a quantum well light-emitting layer, an electron blocking layer, a p-GaN layer, a light-reflecting layer, a transparent conductive layer, an electrode layer one, a high-reflectivity DBR layer, and an electrode layer two. The light-reflecting layer is made of a GaN / AlN superlattice structure. The application grows a GaN / AlN superlattice light-reflecting layer on the p-type gallium nitride, and etches the light-reflecting layer to form a periodic pattern. The p-GaN layer is exposed in the area where the light-reflecting layer is etched, so that the Ohmic contact between the transparent conductive layer and the p-GaN layer is not affected. The structure partially reflects the light directed to the p-GaN layer, increases the light reflection, reduces the light absorption of the material when the light passes through the transparent conductive layer and the electrode, and reflects the other part of the light directed to the electrode again by the high-reflectivity DBR layer, so that the light-emitting efficiency of the flip LED chip is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of LED chip, especially a high light efficiency flip chip LED and a preparation method thereof. BACKGROUND

[0002] The flip chip LED structure is proposed for the normal structure. The flip chip LED is to flip the normal LED chip on the high thermal conductivity support substrate, so as to improve the heat dissipation performance of the LED. The series and parallel connection between the light emitting units is realized on the flip chip substrate, and the wiring on the flip chip substrate is simple and flexible, and the process difficulty of the interconnection climbing between the isolated units in the normal product is broken through.

[0003] Due to the special structure of the flip chip, the flip chip has special requirements in some preparation processes. In terms of the substrate, the light emitting surface is on one side of the sapphire, so before the epitaxial growth, the appropriate patterned substrate is made, which will help to improve the light emitting efficiency; in terms of the epitaxial structure growth, the light emitting surface is changed, and the light absorption of each layer is different from that of the normal chip, so the thickness and doping concentration of the buffer layer, the n-type gallium nitride layer, the multi-quantum well layer and the p-type gallium nitride layer need to be adjusted to meet the requirements of the flip chip light emitting, improve the light emitting efficiency and meet the needs of the ohmic contact of the flip chip manufacturing process; in terms of the chip manufacturing, there needs to be a high reflection layer between the epitaxial layer and the electrode, so that the light emitted to the electrode direction of the chip can be reflected back to the sapphire side as much as possible to ensure good light emitting efficiency.

[0004] The flip chip LED in the prior art has the problem of low light emitting efficiency. SUMMARY

[0005] The present application provides a high light efficiency flip chip LED and a preparation method thereof, which effectively improves the light emitting efficiency of the flip chip LED.

[0006] Technical scheme: The present application discloses a high light efficiency flip chip LED, which comprises the following structures from bottom to top: a sapphire patterned substrate, a GaN nucleation layer, an n-GaN layer, a current expansion layer, a quantum well light emitting layer, an electron blocking layer, a p-GaN layer, a reflective layer, a transparent conductive layer, an electrode layer, a high reflectivity DBR layer and an electrode layer two.

[0007] Further, the material of the reflective layer is GaN / AlN material, and the GaN / AlN material is periodically and alternately grown to form a distributed Bragg reflector.

[0008] Further, the growth period of the GaN / AlN material is 5-20 periods, and the first layer and the last layer are both GaN material.

[0009] Further, the thickness of each cycle of GaN / AlN is calculated and optimized according to the distributed Bragg reflection law, and the total thickness is 250-1000A.

[0010] The application also discloses a preparation method of the high-light-efficiency flip LED chip. The flip LED chip is prepared on an epitaxial wafer with a complete epitaxial structure which is obtained by growing in a MOCVD device.

[0011] Further, the preparation steps of the epitaxial wafer are as follows:

[0012] 1) growing a GaN nucleation layer on a sapphire patterned substrate;

[0013] 2) growing an n-GaN layer at high temperature on the GaN nucleation layer;

[0014] 3) growing a current spreading layer on the n-GaN layer, the current spreading layer being a low-doped n-type GaN;

[0015] 4) growing an InGaN / GaN quantum well light-emitting layer on the current spreading layer;

[0016] 5) growing an electron blocking layer of AlGaN material on the InGaN / GaN quantum well light-emitting layer;

[0017] 6) growing a p-GaN layer on the electron blocking layer;

[0018] 7) growing a GaN / AlN light-reflecting layer on the p-GaN layer.

[0019] Further optimization, the preparation steps of the epitaxial wafer are as follows:

[0020] 1) using a MOCVD device, performing surface cleaning treatment on a sapphire patterned substrate under high temperature conditions;

[0021] 2) growing a GaN nucleation layer on the sapphire patterned substrate subjected to high temperature treatment in the MOCVD device;

[0022] 3) growing an n-GaN layer on the GaN nucleation layer in the MOCVD device, the Si doping concentration of the n-GaN layer being 5×10 18 cm -3 ~5×10 19 cm -3 ;

[0023] 4) growing a current spreading layer on the n-GaN layer in the MOCVD device, the current spreading layer being a low-doped n-type GaN, and the Si doping concentration of the current spreading layer being 1×10 17 cm -3 ~5×10 17 cm-3 ;

[0024] 5) In the MOCVD equipment, the quantum well light emitting layer is grown on the current spreading layer, the multi-quantum well structure is the alternating growth of well layer InGaN and barrier layer GaN, and the growth period is 5-15;

[0025] 6) In the MOCVD equipment, the electron blocking layer is grown on the quantum well light emitting layer, the electron blocking layer material is AlGaN, and the thickness is 200-1000 Å;

[0026] 7) In the MOCVD equipment, the p-GaN layer is grown on the electron blocking layer, the p-GaN layer thickness is 200-1000 Å, and the Mg doping concentration of the p-GaN layer is 5×10 19 cm -3 ~5×10 20 cm -3 After the entire LED epitaxial structure is grown, the epitaxial wafer is rapidly annealed to activate the doping of the p-GaN layer; and the p-GaN layer ohmic contact is facilitated;

[0027] 8) In the MOCVD equipment, the light reflecting layer is grown on the p-GaN layer, the light reflecting layer material is GaN / AlN, and the GaN / AlN is periodically and alternately grown to form a distributed Bragg reflector layer; thus, the epitaxial wafer with complete epitaxial structure is obtained.

[0028] Further, the preparation steps of the flip chip LED are as follows:

[0029] 1) Etching is performed on the prepared epitaxial wafer, the GaN / AlN light reflecting layer is etched into a regular arrangement pattern, and the p-GaN layer is exposed in the area where the GaN / AlN light reflecting layer is etched away;

[0030] 2) The transparent conductive layer is deposited on the epitaxial wafer with the etched GaN / AlN light reflecting layer, and the material of the transparent conductive layer is indium tin oxide;

[0031] 3) The electrode layer one is evaporated on the transparent conductive layer, the material of the electrode layer one is an alloy combination of Cr / Al / Ti / Pt / Au, and the electrode shape is optimized according to requirements;

[0032] 4) The high reflectivity DBR layer is evaporated on the electrode layer one, and the DBR layer structure is periodically and alternately grown by SiO2 / TiO2;

[0033] 5) The electrode layer two is evaporated again on the high reflectivity DBR layer, the material of the electrode layer two is an alloy combination of Cr / Al / Ti / Pt / Au; the high reflectivity DBR layer has a reserved through hole, the electrode layer two and the electrode layer one are metal interconnected, and finally the flip chip LED chip with high light efficiency is obtained.

[0034] Further optimization, the preparation steps of the flip LED are as follows:

[0035] 1) etching is carried out on the prepared epitaxial wafer, the GaN / AlN light reflection layer is etched into a regular arrangement pattern, the p-GaN layer is exposed in the area where the GaN / AlN light reflection layer is etched away, and the size of the regular arrangement pattern is 1-2 um, and the interval is 1-2 um;

[0036] 2) a transparent conductive layer is deposited on the epitaxial wafer after etching the GaN / AlN light reflection layer, the material of the transparent conductive layer is indium tin oxide, and the thickness is 300-2000 angstroms;

[0037] 3) an electrode layer one is evaporated on the transparent conductive layer, the material of the electrode layer one is an alloy combination of Cr / Al / Ti / Pt / Au, and the electrode shape is optimized according to requirements;

[0038] 4) a DBR layer with high reflectivity is evaporated on the electrode layer one, the DBR layer structure is periodically alternately grown in SiO2 / TiO2, the growth period is 20-50 periods, and the total thickness is 1-5 um;

[0039] 5) an electrode layer two is evaporated again on the high reflectivity DBR layer, the material of the electrode layer two is an alloy combination of Cr / Al / Ti / Pt / Au; the high reflectivity DBR layer is provided with a reserved through hole for connecting the electrode layer two and the electrode layer one; and finally, the flip LED chip with high light efficiency is obtained.

[0040] Advantages: the present application has the following advantages:

[0041] By growing the GaN / AlN superlattice light reflection layer on the p-type gallium nitride and etching the light reflection layer to form a periodic arrangement pattern, the p-GaN layer exposed in the area where the light reflection layer is etched away forms a good ohmic contact with the transparent conductive layer; such a structure first reflects part of the light directed to the p-GaN layer, not only increases the light reflection, but also reduces the light absorption of the material when the light passes through the transparent conductive layer and the electrode, and the other part of the light directed to the electrode is reflected again by the high reflectivity DBR layer, thereby effectively improving the light efficiency of the flip LED chip. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 It is a structure schematic diagram of the flip LED chip with high light efficiency in the embodiment of the present application;

[0043] Figure 2 It is a growth method flow chart of the epitaxial structure of the flip LED chip in the embodiment of the present application;

[0044] Figure 3 It is a chip preparation method flow chart of the flip LED chip in the embodiment of the present application;

[0045] Among them: 01-sapphire substrate, 02-GaN nucleation layer, 03-n-GaN layer, 04-current spreading layer, 05-quantum well light-emitting layer, 06-electron blocking layer, 07-p-GaN layer, 08-reflective layer, 09-transparent conductive layer, 10-electrode layer one, 12-high reflectivity DBR layer, 13-electrode layer two. Detailed Implementation

[0046] Please refer to Figures 1-3 As shown, this invention provides a high-efficiency flip-chip LED and its fabrication method. The chip structure is as follows: Figure 1 As shown, from bottom to top, it includes: sapphire patterned substrate 01, GaN nucleation layer 02, n-GaN layer 03, current spreading layer 04, quantum well light-emitting layer 05, electron blocking layer 06, p-GaN layer 07, reflective layer 08, transparent conductive layer 09, electrode layer 10, high reflectivity DBR layer 12, and electrode layer 2 13; wherein the reflective layer 08 is a superlattice structure composed of GaN / AlN material.

[0047] Specifically, the reflective layer 08 is a distributed Bragg reflector layer formed by the periodic alternating growth of GaN / AlN. Based on the required LED emission wavelength, the Bragg reflector calculation uses the fractional law to optimize the growth thickness of each GaN / AlN layer. The GaN / AlN growth cycle is 5-20 cycles, with both the first and last layers being GaN material. The total growth thickness of the reflective layer 08 is ultimately 250-1000 Å. This reflective layer 08 is epitaxially grown on the p-GaN layer and then etched to form a periodically arranged pattern. The etched area of ​​the reflective layer 08 exposes the p-GaN layer, while the transparent conductive layer and the p-GaN layer still maintain good ohmic contact. This structure partially reflects light directed towards the p-GaN layer, increasing light reflection and reducing light absorption by the materials when passing through the transparent conductive layer and electrodes. The light directed towards the electrodes is reflected again by the high-reflectivity DBR layer, effectively improving the light extraction efficiency of the flip-chip LED.

[0048] In the fabrication method of high-efficiency flip-chip LEDs, this embodiment specifically provides the following process flow.

[0049] For epitaxial growth methods of high-efficiency flip-chip LEDs, please refer to [reference needed]. Figure 2 The process flow diagram is shown below:

[0050] 1) Using an MOCVD device, the sapphire patterned substrate 01 is surface cleaned under high temperature conditions. Optionally, the chamber temperature is raised to 1050°C in a hydrogen atmosphere and held for 10 minutes.

[0051] 2) In the MOCVD equipment, GaN nucleation layer 02 is grown on the high-temperature treated sapphire pattern substrate 01, the GaN nucleation layer 02 first experiences three-dimensional large particle growth, and then transitions to two-dimensional high-quality thin film growth, to obtain a GaN thin film layer with low defect density;

[0052] 3) In the MOCVD equipment, n-GaN layer 03 is grown on the GaN nucleation layer 02 at high temperature, optionally, the growth temperature of the n-GaN layer 03 is 1050°C, the growth thickness is about 2um, and the Si doping concentration is 5×10 18 cm -3 ~5×10 19 cm -3 ;

[0053] 4) In the MOCVD equipment, current spreading layer 04 is grown on the n-GaN layer 03, optionally, the material of the current spreading layer 04 is low-doped n-type GaN, the thickness of the current spreading layer 04 is 0.2um~0.5um, and the Si doping concentration is 1×10 17 cm -3 ~5×10 17 cm -3 ;

[0054] 5) In the MOCVD equipment, quantum well light-emitting layer 05 is grown on the current spreading layer 04, the multi-quantum well structure is the alternating growth of well layer InGaN and barrier layer GaN, optionally, the thickness of the well layer InGaN is 20Å~50Å, the thickness of the barrier layer GaN is 80Å~150Å, and the alternating growth period is 5~15;

[0055] 6) In the MOCVD equipment, electron blocking layer 06 is grown on the quantum well light-emitting layer 05, optionally, the material of the electron blocking layer 06 is AlGaN, the Al content is 10%~30%, and the growth thickness of the electron blocking layer 06 is 200~1000Å;

[0056] 7) In the MOCVD equipment, p-GaN layer 07 is grown on the electron blocking layer 06, optionally, the thickness of the p-GaN layer 07 is 200~1000Å, the Mg doping concentration is 5×10 19 cm -3 ~5×10 20 cm -3 , and after the entire LED epitaxial structure is grown, rapid annealing is required to activate the doping of the p-GaN layer 07, which is conducive to improving the ohmic contact of the p-GaN layer 07;

[0057] 8) In the MOCVD equipment, a light reflection layer 08 is grown on the p-GaN layer 07, the material of the light reflection layer 08 is GaN / AlN, the GaN / AlN is periodically grown to form a distributed Bragg reflection layer, and the first layer and the last layer are both GaN materials; optionally, the growth period of GaN / AlN is 5-20 periods, the thickness of each period of GaN / AlN is calculated and optimized according to the distributed Bragg reflection law, and the total growth thickness of the light reflection layer 08 is 250-1000 Å.

[0058] Next, the chip preparation method of the high-efficiency flip LED chip is shown in the process flow chart of Figure 3 , and the specific steps are as follows:

[0059] 1) The prepared epitaxial wafer is subjected to MESA etching to the n-GaN layer to etch the mesa of the n-electrode. The specific method is to first clean the epitaxial wafer to remove surface dirt, then perform uniform coating, exposure and development in the yellow light area to obtain a mask layer of MESA on the surface of the epitaxial wafer, and then use an ICP device for dry etching to etch the region without a mask layer to the n-GaN layer, thereby obtaining the mesa of the n-electrode and the cutting channel between the core particles. After etching, the surface is cleaned to remove the remaining photoresist and mask layer;

[0060] 2) The GaN / AlN light reflection layer 08 on the above epitaxial wafer is etched to form a regular arrangement pattern, and the p-GaN layer is exposed in the region where the GaN / AlN light reflection layer 08 is etched. The specific method is to perform uniform coating, exposure and development in the yellow light area to first form a required pattern mask layer on the surface of the epitaxial wafer, i.e., the light reflection layer 08, and then use an ICP device to etch the light reflection layer 08 to obtain a preset pattern; optionally, the regular arrangement pattern can be a conical pattern, a cylindrical pattern or other patterns. In this embodiment, a conical pattern is selected, and the size of the regular arrangement pattern is 1-2 um and the pitch is 1-2 um. Then, the mask layer is removed by cleaning;

[0061] 3) Deposition of transparent conductive layer 09 on the epitaxial wafer etched GaN / AlN reflective layer 08, optionally, the material of the transparent conductive layer is indium tin oxide, the thickness is 300A~2000A, the specific preparation method is that the ITO film layer is evaporated by using a vacuum magnetron sputtering device to obtain a transparent conductive layer 09 with a predetermined thickness; then uniform glue, exposure and development are carried out in the yellow light area to obtain the required pattern on the transparent conductive layer 09, the mesa and core particle cutting path of the n electrode are exposed, the ITO layer on the mesa and core particle cutting path of the n electrode is removed by wet etching, and then cleaning is carried out to remove the residual mask layer on the surface. After the above steps, the core particle is obtained, the p electrode mesa is covered by the ITO layer, and the area where the p-GaN layer 07 and the ITO layer 09 contact forms a good ohmic contact; because there are regularly arranged reflective layers 08 above the p-GaN layer 07, the area where the p-GaN layer 07 and the ITO layer 09 contact is also regularly arranged, which is also conducive to the uniform expansion of the current;

[0062] 4) Evaporation of electrode layer one 10 (p electrode and n electrode respectively) on the transparent conductive layer 09, optionally, the material of the electrode layer one is an alloy combination of Cr / Al / Ti / Pt / Au, and the electrode shape can be optimized according to the requirements, the specific method is to carry out uniform glue, exposure and development in the yellow light area to form the required electrode pattern on the transparent conductive layer 09, and then the electrode layer one is evaporated by using a magnetron sputtering device, and then the gold is torn off to obtain the electrode layer one 10 (p electrode and n electrode respectively) with a preset pattern;

[0063] 5) Evaporation of DBR layer 12 with high reflectivity on the surface of the wafer obtained above, optionally, the structure of the DBR layer 12 is periodic alternation growth of SiO2 / TiO2 material, the growth period is 20~50 periods, and the total thickness is 1um~5um, the specific method is that the high reflectivity DBR layer 12 is evaporated by using a LED multilayer optical DBR film coating vacuum device; after the DBR film layer is coated, uniform glue, exposure and development are carried out in the yellow light area, ICP dry etching is used, and then the residual mask layer on the surface is cleaned to obtain the through hole reserved on the above p electrode and n electrode for metal interconnection with the electrode layer two;

[0064] 6) Electrode layer two 13 (p-pad and n-pad respectively) is evaporated on the high reflectivity DBR layer 12, and the material of the electrode layer two is an alloy combination of Cr / Al / Ti / Pt / Au, and the specific method is that the electrode pattern is formed on the DBR layer 12 by performing uniform coating, exposure and development in the yellow light area, the film layer of the electrode layer two is evaporated by using the magnetron sputtering equipment, and then the electrode layer two 10 (p-pad and n-pad respectively) with the preset pattern is obtained after the gold tearing and the glue removing, and the electrode layer two and the electrode layer one form a good metal interconnection through the through hole reserved on the high reflectivity DBR layer 12.

[0065] The application grows the GaN / AlN superlattice light-reflecting layer on the p-type gallium nitride, and etches the light-reflecting layer to form a periodic pattern, and the p-GaN layer exposed in the area where the light-reflecting layer is etched forms a good ohmic contact with the transparent conductive layer; such a structure first reflects part of the light towards the p-GaN layer, not only increases the light reflection, but also reduces the light absorption of the material when the light passes through the transparent conductive layer and the electrode, and the other part of the light towards the electrode is reflected by the high reflectivity DBR layer again, thereby effectively improving the light extraction efficiency of the flip LED chip.

Claims

1. A method for fabricating a high light efficiency flip-chip LED chip, characterized in that: First, the epitaxial wafer with complete epitaxial structure is obtained by growing in MOCVD equipment, and then the preparation of flip LED chip is carried out on the epitaxial wafer; the chip structure includes the following structures from bottom to top: sapphire patterned substrate, GaN nucleation layer, n-GaN layer, current spreading layer, quantum well light emitting layer, electron blocking layer, p-GaN layer, light reflection layer, transparent conductive layer, electrode layer one, high reflectivity DBR layer, electrode layer two; The preparation steps of the epitaxial wafer are as follows: 1) growing GaN nucleation layer on the sapphire patterned substrate; 2) growing n-GaN layer on the GaN nucleation layer at high temperature; 3) growing current spreading layer on the n-GaN layer, and the current spreading layer is low-doped n-type GaN; 4) growing InGaN / GaN quantum well light emitting layer on the current spreading layer; 5) growing AlGaN material electron blocking layer on the InGaN / GaN quantum well light emitting layer; 6) growing p-GaN layer on the electron blocking layer; 7) growing GaN / AlN light reflection layer on the p-GaN layer; The preparation steps of the flip LED are as follows: 1) etching the prepared epitaxial wafer to etch the GaN / AlN light reflection layer into a regular pattern, and the p-GaN layer is exposed in the area where the GaN / AlN light reflection layer is etched off; 2) depositing transparent conductive layer on the epitaxial wafer after etching the GaN / AlN light reflection layer, and the material of the transparent conductive layer is indium tin oxide; 3) evaporating electrode layer one on the transparent conductive layer, and the material of the electrode layer one is an alloy combination of Cr / Al / Ti / Pt / Au; 4) evaporating high reflectivity DBR layer on the electrode layer one, and the DBR layer structure is periodically alternately grown by SiO2 / TiO2; 5) evaporating electrode layer two on the high reflectivity DBR layer again, and the material of the electrode layer two is an alloy combination of Cr / Al / Ti / Pt / Au; the high reflectivity DBR layer has a reserved through hole, and the electrode layer two and the electrode layer one are metal interconnected, and finally the flip LED chip with high light efficiency is obtained.

2. The method of claim 1, wherein the method further comprises: The material of the light reflection layer is GaN / AlN material, and the GaN / AlN is periodically alternately grown to form a distributed Bragg reflection layer.

3. The method of claim 1 or 2, wherein the method further comprises: The growth period of GaN / AlN material is 5-20 periods, and the first layer and the last layer are both GaN material.

4. The method of claim 3, wherein the method further comprises: The thickness of each period of GaN / AlN is calculated and optimized according to the distributed Bragg reflection law, and the total growth thickness of the final light reflection layer is 250-1000 Å after 5-20 periods.

5. The method of claim 1, wherein the method further comprises: forming a plurality of reflective layers on the substrate; and forming a plurality of reflective layers on the LED chip. The preparation steps of the epitaxial wafer are as follows: 1) using MOCVD equipment, the sapphire patterned substrate is subjected to surface cleaning treatment under high temperature conditions; 2) growing GaN nucleation layer on the sapphire patterned substrate subjected to high temperature treatment in the MOCVD equipment; 3) growing an n-GaN layer on a GaN nucleation layer in a MOCVD apparatus, the n-GaN layer having a Si doping concentration of 5 x 1018 cm"3 to 5 x 1020 cm"3 18 cm -3 ~5 x 1020 19 cm -3 ; 4) growing a current spreading layer on the n-GaN layer in a MOCVD apparatus, the current spreading layer being a low doped n-type GaN with a Si doping concentration of 1 x 1018cm-3 17 cm -3 ~5 x 1018cm-3 17 cm -3 ; 5) growing quantum well light emitting layer on the current spreading layer in the MOCVD equipment, and the multi-quantum well structure is alternately grown by well layer InGaN and barrier layer GaN, and the growth period is 5-15; 6) growing electron blocking layer on the quantum well light emitting layer in the MOCVD equipment, and the material of the electron blocking layer is AlGaN with a thickness of 200-1000 Å; 7) In the MOCVD equipment, a p-GaN layer is grown on the electron blocking layer, the thickness of the p-GaN layer is 200-1000 angstrom, the Mg doping concentration of the p-GaN layer is 5x1019-5x1020cm-3 19 cm -3 ~5x1019 20 cm -3 After the epitaxial structure of the whole LED is grown, the epitaxial wafer is rapidly annealed to activate the doping of the p-GaN layer; 8) In the MOCVD equipment, a light-reflecting layer is grown on the p-GaN layer, the material of the light-reflecting layer is GaN / AlN, and the GaN / AlN is periodically alternately grown to form a distributed Bragg reflector; thus, an epitaxial wafer with a complete epitaxial structure is obtained.

6. The method of claim 1, wherein the method further comprises: The preparation steps of the flip LED are as follows: 1) Etching is performed on the prepared epitaxial wafer, the GaN / AlN light-reflecting layer is etched into a regularly arranged pattern, the p-GaN layer is exposed in the area where the GaN / AlN light-reflecting layer is etched away, and the size of the regularly arranged pattern is 1um~2um and the interval is 1um~2um; 2) A transparent conductive layer is deposited on the epitaxial wafer after the GaN / AlN light-reflecting layer is etched, the material of the transparent conductive layer is indium tin oxide, and the thickness is 300Å~2000Å; 3) An electrode layer one is evaporated on the transparent conductive layer, the material of the electrode layer one is an alloy combination of Cr / Al / Ti / Pt / Au; 4) A DBR layer with high reflectivity is evaporated on the electrode layer one, the structure of the DBR layer is SiO2 / TiO2 which is periodically alternately grown, the growth period is 20~50 periods, and the total thickness is 1um~5um; 5) An electrode layer two is evaporated again on the high-reflectivity DBR layer, the material of the electrode layer two is an alloy combination of Cr / Al / Ti / Pt / Au; the high-reflectivity DBR layer is provided with a reserved through hole for connecting the electrode layer two and the electrode layer one; and finally, a flip LED chip with high light efficiency is obtained.

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