High-brightness flip LED chip and preparation method thereof

Abstract

The invention discloses a high-brightness flip LED chip and a preparation method thereof, and relates to the technical field of semiconductors, and the preparation method comprises the following steps: depositing a reflection base layer on a light emitting surface of a wafer with a plurality of flip LED chip main bodies; a plurality of groove structures are formed in the surface of the reflection base layer in an etching mode, the groove structures correspond to the flip LED chip bodies one to one, the groove walls of the groove structures serve as reflection enclosing walls, and the groove bottom areas of the groove structures serve as anti-reflection areas; a reflecting metal film is deposited along the surface of the reflecting wall; a light sieve layer is deposited and formed along the surfaces of the reflective metal film and the anti-reflection area; a plurality of round holes are formed in the light sieve layer in the anti-reflection area in an etching mode, and the surface of the anti-reflection area is exposed. According to the invention, the reflection wall, the anti-reflection area, the reflection metal film and the light sieve layer with the round holes are formed on the light-emitting surface of the chip, so that the side light leakage can be effectively reduced, and the axial light-emitting efficiency can be improved, thereby facilitating the improvement of the overall brightness.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a high-brightness flip-chip LED chip and a preparation method thereof. Background Art

[0002] Flip-chip LED chips generally use DBR structure and Ag as a reflective film layer to improve the reflectivity of light, thereby increasing the brightness of the flip-chip LED chip. However, after the light is emitted from the quantum well layer, it will first be reflected inside the chip and then emitted from the sapphire substrate; in this process, it is difficult to avoid that some light will be emitted from the sapphire substrate at a larger angle (>120°), which can easily cause light leakage from the side of the flip-chip LED chip, resulting in a decrease in the axial light output efficiency of the flip-chip LED chip and a decrease in the overall brightness. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art. The present invention provides a high-brightness flip-chip LED chip and a preparation method thereof. By forming a reflective wall, a transmittance-enhancing area, a reflective metal film and a light screen layer with circular holes on the light-emitting surface of the flip-chip LED chip body, not only can the side light leakage of the flip-chip LED chip be effectively reduced, but also the axial light-emitting efficiency of the flip-chip LED chip can be improved, thereby facilitating improving the overall brightness of the flip-chip LED chip.

[0004] The present invention provides a method for preparing a high-brightness flip-chip LED chip, comprising the following steps:

[0005] S11, depositing a reflective base layer on the light-emitting surface of the wafer having a plurality of flip-chip LED chip bodies;

[0006] S12, etching a plurality of groove structures on the surface of the reflective base layer, wherein the groove structures correspond to the flip-chip LED chip bodies one by one, the groove walls of the groove structures serve as reflective walls, and the groove bottom areas of the groove structures serve as anti-reflection areas;

[0007] S13, depositing a reflective metal film along the surface of the reflective wall;

[0008] S14, depositing a light screening layer along the surface of the reflective metal film and the anti-reflection area;

[0009] S15, etching a plurality of circular holes on the light screening layer in the anti-reflection region, wherein the plurality of circular holes expose the surface of the anti-reflection region.

[0010] Specifically, the material of the reflective base layer is SiO2 or SiN x , the thickness of the reflective base layer is 5000 to 20000 angstroms.

[0011] Specifically, the reflective base layer is formed by deposition using a plasma enhanced chemical vapor deposition technique, the deposition power ranges from 90 to 150 W, and the deposition temperature ranges from 120 to 150° C.

[0012] Specifically, the angle between the side wall of the reflective enclosure and the surface of the anti-reflection area is an obtuse angle, and the angle range of the obtuse angle is 120° to 160°.

[0013] Specifically, the thickness of the reflective base layer in the anti-reflection zone is H1, 1000 angstroms < H1 < 5000 angstroms, H1 = 1100*N angstroms, N ≥ 1 and N is an integer.

[0014] Specifically, the step of depositing a reflective metal film along the surface of the reflective fence includes:

[0015] Depositing Cr or Ti along the surface of the reflective wall to form a bottom film layer;

[0016] Depositing one or more of Ag, Al, Cu, Au, and Pt along the surface of the base film layer to form a reflective layer;

[0017] The base film layer and the reflective layer constitute the reflective metal film.

[0018] Specifically, the thickness of the base film layer ranges from 25 to 50 angstroms, the thickness of the reflective layer ranges from 100 to 5000 angstroms, and the reflective layer is a single-layer structure or a laminated structure.

[0019] Specifically, the material of the light screening layer is SiO2, SiN x , SiC or AlN, the light screening layer is a single-layer structure or a stacked structure, the thickness of the light screening layer is H2, 1000 angstroms < H2 < 10000 angstroms, H2 = 1100*M angstroms, M≥1 and M is an integer.

[0020] Specifically, the diameter of the circular holes ranges from 2 to 15 micrometers, the center distance between two adjacent circular holes ranges from 25 to 50 micrometers, and the multiple circular holes are arranged at equal intervals.

[0021] The present invention also provides a high-brightness flip-chip LED chip, and the high-brightness flip-chip LED chip is prepared by the preparation method of the high-brightness flip-chip LED chip.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The preparation method of the high-brightness flip-chip LED chip of the present invention forms a plurality of groove structures on the light-emitting surface of a wafer having a plurality of flip-chip LED chip bodies based on a reflective base layer, the groove structures correspond to the flip-chip LED chip bodies one by one, the groove walls of the groove structures serve as reflective walls, which can reflect the large-angle light emission of the flip-chip LED chip, thereby increasing the axial light emission of the flip-chip LED chip; the groove bottom area of ​​the groove structure serves as a transmittance-enhancing area, which can increase the light transmission effect and is also conducive to increasing the axial light emission of the flip-chip LED chip; a reflective metal film is deposited on the surface of the reflective wall, which can further increase the reflection efficiency of the reflective wall; the light screen layer can insulate and protect the reflective metal film on the reflective wall on the one hand, and can guide the light to be emitted from the axial direction of the flip-chip LED chip on the other hand, which can further improve the axial light emission efficiency of the flip-chip LED chip; the plurality of circular holes in the light screen layer can enhance the light guiding ability of the light screen layer, so that the light is emitted from the axial direction of the flip-chip LED chip as much as possible, and can also further improve the axial light emission efficiency of the flip-chip LED chip; therefore, the preparation method of the high-brightness flip-chip LED chip of the present invention can effectively improve the overall brightness of the flip-chip LED chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 1 is a schematic diagram of a first process of a method for preparing a high-brightness flip-chip LED chip according to an embodiment of the present invention;

[0026] Figure 2 is a schematic diagram of a three-dimensional structure of a reflective base layer formed by deposition in an embodiment of the present invention;

[0027] Figure 3 is a schematic cross-sectional structure diagram of a reflective base layer formed by deposition in an embodiment of the present invention;

[0028] Figure 4 is a schematic diagram of a three-dimensional structure in which a plurality of groove structures are formed by etching in an embodiment of the present invention;

[0029] Figure 5 is a schematic cross-sectional structure diagram of etching to form a plurality of groove structures in an embodiment of the present invention;

[0030] Figure 6 is a schematic diagram of a three-dimensional structure of a reflective metal film deposited in an embodiment of the present invention;

[0031] Figure 7is a schematic cross-sectional structure diagram of a reflective metal film formed by deposition in an embodiment of the present invention;

[0032] Figure 8 is a schematic diagram of a three-dimensional structure of a light screening layer formed by deposition in an embodiment of the present invention;

[0033] Fig. 9 is a schematic diagram of the cross-sectional structure of a light screening layer formed by deposition in an embodiment of the present invention;

[0034] Fig.10 is a schematic diagram of a three-dimensional structure in which a plurality of circular holes are formed by etching in an embodiment of the present invention;

[0035] Fig.11 is a schematic cross-sectional structure diagram of etching to form a plurality of circular holes in an embodiment of the present invention;

[0036] Fig.12 Schematic diagram of the distribution pattern of circular holes in an embodiment of the present invention;

[0037] Fig.13 1 is a second flow chart of the method for preparing a high-brightness flip-chip LED chip according to an embodiment of the present invention;

[0038] Fig.14 is a schematic structural diagram of a first flip-chip LED chip wafer in an embodiment of the present invention;

[0039] Fig.15 is a schematic diagram of a bonding structure between a first flip-chip LED chip wafer and a temporary supporting substrate in an embodiment of the present invention;

[0040] Fig.16 is a schematic diagram of the structure of a sapphire substrate after grinding and polishing in an embodiment of the present invention;

[0041] Fig.17 3 is a schematic diagram of a third process of the method for preparing a high-brightness flip-chip LED chip in an embodiment of the present invention;

[0042] Fig.18 is a schematic structural diagram of a second flip-chip LED chip wafer in an embodiment of the present invention;

[0043] Fig.19 Schematic diagram of the structure of the core particle in the embodiment of the present invention.

[0044] In the accompanying drawings, 1. sapphire substrate; 2. N-GaN layer; 3. multi-quantum well MQW layer; 4. P-GaN layer; 5. current diffusion layer; 6. Ag reflection layer; 7. first passivation protection layer; 8. first metal connection layer; 9. second passivation protection layer; 10. P electrode; 11. N electrode; 12. temporary support substrate; 13. bonding glue; 100. reflection base layer; 110. reflection fence; 120. anti-reflection area; 200. reflection metal film; 300. light screening layer; 310. circular hole. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Example 1

[0047] The present invention provides a method for preparing a high-brightness flip-chip LED chip. Figure 1 The first process diagram of the method for preparing a high-brightness flip-chip LED chip in an embodiment of the present invention is shown, and the method comprises the following steps:

[0048] S11, depositing a reflective base layer on the light-emitting surface of the wafer having a plurality of flip-chip LED chip bodies;

[0049] Figure 2 A schematic diagram of a three-dimensional structure of a reflective base layer formed by deposition in an embodiment of the present invention is shown. Figure 3 A schematic cross-sectional structure diagram of a reflective base layer formed by deposition in an embodiment of the present invention is shown.

[0050] The reflective base layer 100 is the basis for the subsequent formation of the groove structure. The material of the reflective base layer 100 is SiO2 or SiN x The thickness of the reflective base layer 100 is 5000 to 20000 angstroms. Preferably, the reflective base layer 100 is made of SiO2, which is more brittle than SiN. x The reflective base layer 100 is weak and is not easy to break during subsequent processing.

[0051] The reflective base layer 100 is formed by deposition using plasma enhanced chemical vapor deposition technology, with a deposition power ranging from 90 to 150 W and a deposition temperature ranging from 120 to 150° C., which is not easy to damage the flip-chip LED chip body.

[0052] S12, etching a plurality of groove structures on the surface of the reflective base layer, wherein the groove structures correspond to the flip-chip LED chip bodies one by one, the groove walls of the groove structures serve as reflective walls, and the groove bottom areas of the groove structures serve as anti-reflection areas;

[0053] Figure 4 A schematic diagram of a three-dimensional structure of a plurality of groove structures formed by etching in an embodiment of the present invention is shown. Figure 5 A schematic cross-sectional structure diagram of etching to form a plurality of groove structures in an embodiment of the present invention is shown.

[0054] The groove wall of the groove structure serves as a reflective wall 110, which surrounds the light-emitting surface of the flip-chip LED chip body (the reflective wall 110 corresponds to the preset cutting paths around the flip-chip LED chip body), and can reflect the large-angle light of the flip-chip LED chip as much as possible, thereby increasing the axial light output of the flip-chip LED chip; the groove bottom area of ​​the groove structure serves as a transmittance-enhancing area 120, which can increase the light transmission effect and is also beneficial to increase the axial light output of the flip-chip LED chip.

[0055] Specifically, the angle between the side wall of the reflective wall 110 and the surface of the anti-reflection area 120 is an obtuse angle, and the angle range of the obtuse angle is 120° to 160°, that is, the angle range between the side wall of the reflective wall 110 and the vertical plane is 30° to 70°, which can effectively reflect the large-angle light output of the flip-chip LED chip.

[0056] Furthermore, the thickness of the reflective base layer 100 of the anti-reflection zone 120 is H1, 1000 angstroms < H1 < 5000 angstroms, H1 = 1100*N angstroms, N ≥ 1 and N is an integer, and the light transmission effect is good.

[0057] S13, depositing a reflective metal film along the surface of the reflective wall;

[0058] Figure 6 FIG. 1 shows a schematic diagram of a three-dimensional structure of a reflective metal film deposited in an embodiment of the present invention. Figure 7 A schematic cross-sectional structure diagram of a reflective metal film formed by deposition in an embodiment of the present invention is shown.

[0059] The reflective metal film 200 has good reflective effect, and can further increase the reflective efficiency of the reflective wall 110 .

[0060] Specifically, the deposition of the reflective metal film 200 along the surface of the reflective wall 110 includes:

[0061] Cr or Ti is deposited along the surface of the reflective wall 110 to form a base film layer having good adhesion, so that the subsequent reflective layer can be stably attached to the surface of the reflective wall 110;

[0062] Depositing one or more of Ag, Al, Cu, Au, and Pt along the surface of the base film layer to form a reflective layer with high reflection efficiency;

[0063] The base film layer and the reflective layer constitute the reflective metal film 200 .

[0064] Furthermore, the thickness of the base film layer ranges from 25 to 50 angstroms, with good adhesion; the thickness of the reflective layer ranges from 100 to 5000 angstroms, with good reflection; the reflective layer is a single-layer structure or a laminated structure. Preferably, the reflective layer is a laminated structure with high structural stability, density, few defects and high reflection efficiency.

[0065] S14, depositing a light screening layer along the surface of the reflective metal film and the anti-reflection area;

[0066] Figure 8 A schematic diagram of the three-dimensional structure of a light screening layer formed by deposition in an embodiment of the present invention is shown. Fig. 9 A schematic cross-sectional structure diagram of a light screening layer formed by deposition in an embodiment of the present invention is shown.

[0067] The light screening layer 300 can insulate and protect the reflective metal film 200 on the reflective fence 110 , and can guide the light to be emitted from the axial direction of the flip-chip LED chip, thereby further improving the axial light emission efficiency of the flip-chip LED chip.

[0068] Specifically, the material of the light screening layer 300 is SiO2, SiN x , SiC or AlN, the light screening layer 300 is a single-layer structure or a stacked structure, the thickness of the light screening layer 300 is H2, 1000 angstroms < H2 < 10000 angstroms, H2 = 1100*M angstroms, M≥1 and M is an integer, which can play a good role in guiding light.

[0069] Preferably, M is 1, 2, 3 or 4. If M is greater than 4, the process time and cost required to form the light screening layer 300 will increase rapidly.

[0070] S15, etching a plurality of circular holes on the light screening layer in the anti-reflection region, wherein the plurality of circular holes expose the surface of the anti-reflection region;

[0071] Fig.10 FIG. 1 is a schematic diagram showing a three-dimensional structure in which a plurality of circular holes are formed by etching in an embodiment of the present invention. Fig.11 A schematic cross-sectional structure diagram of etching to form a plurality of circular holes in an embodiment of the present invention is shown.

[0072] The circular hole 310 can enhance the light guiding capability of the light screen layer 300 so that the light can be emitted from the axial direction of the flip-chip LED chip as much as possible, and can also further improve the axial light extraction efficiency of the flip-chip LED chip.

[0073] Specifically, the diameter of the circular holes 310 ranges from 2 to 15 microns, the center distance between two adjacent circular holes 310 ranges from 25 to 50 microns, and the multiple circular holes 310 are arranged at equal intervals, which greatly enhances the light guiding capability.

[0074] Further, the plurality of circular holes 310 are arranged at equal intervals in an A-sided polygonal pattern, where A ≥ 3 and A is an integer; Fig.12 A schematic diagram of the distribution pattern of circular holes in an embodiment of the present invention is shown, wherein the distribution pattern of an equilateral triangle pattern (the centers of the three circular holes 310 are located at the vertices of the equilateral triangle) is the smallest arrangement unit, and other polygonal patterns are arranged on the basis of the equilateral triangle pattern, such as a prismatic pattern arrangement (four circular holes 310, two equilateral triangles), a regular hexagonal pattern arrangement (seven circular holes 310, six equilateral triangles), and so on.

[0075] Preferably, A is 3, 4, 5 or 6. If A≥6, the circular holes 310 are arranged closely, and the line width of photolithography and etching is difficult to control.

[0076] The method for preparing a high-brightness flip-chip LED chip of the present invention forms a plurality of groove structures on the light-emitting surface of a wafer having a plurality of flip-chip LED chip bodies based on a reflective base layer 100, wherein the groove structures correspond to the flip-chip LED chip bodies one by one, and the groove walls of the groove structures serve as reflective walls 110, which can reflect the large-angle light emitted by the flip-chip LED chips, thereby increasing the axial light emitted by the flip-chip LED chips; the groove bottom area of ​​the groove structure serves as a transmittance-enhancing area 120, which can increase the light transmission effect and is also beneficial to increasing the axial light emitted by the flip-chip LED chips; a reflective metal film 200 is deposited on the surface of the reflective walls 110, which can further increase the reflective The reflective efficiency of the reflective wall 110 can be improved; the light screen layer 300 can, on the one hand, insulate and protect the reflective metal film 200 on the reflective wall 110, and on the other hand, can guide the light to be emitted from the axial direction of the flip-chip LED chip, thereby further improving the axial light output efficiency of the flip-chip LED chip; the multiple circular holes 310 in the light screen layer 300 can enhance the light guiding ability of the light screen layer 300, so that the light is emitted from the axial direction of the flip-chip LED chip as much as possible, thereby further improving the axial light output efficiency of the flip-chip LED chip; therefore, the preparation method of the high-brightness flip-chip LED chip of the present invention can effectively improve the overall brightness of the flip-chip LED chip.

[0077] Example 2

[0078] Fig.13 The second process diagram of the method for preparing a high-brightness flip-chip LED chip in an embodiment of the present invention is shown. Before step S11 of implementation 1, the following steps are also included:

[0079] S21, preparing a first flip-chip LED chip wafer, wherein the first flip-chip LED chip wafer comprises a sapphire substrate and a plurality of flip-chip LED chip bodies distributed on the sapphire substrate;

[0080] Fig.14 A schematic structural diagram of a first flip-chip LED chip wafer in an embodiment of the present invention is shown.

[0081] Specifically, an N-GaN layer 2, a multi-quantum well MQW layer 3 and a P-GaN layer 4 are sequentially grown on a sapphire substrate 1 to obtain an epitaxial layer structure; the sapphire substrate 1 is a patterned substrate;

[0082] A plurality of first pits are formed by etching in a preset area of ​​the epitaxial layer structure, wherein the first pits extend from the P-GaN layer 4 to the N-GaN layer 2; a portion of the first pits are used as MESA holes, and another portion of the first pits are used as cutting paths;

[0083] Depositing ITO as a current diffusion layer 5 on the P-GaN layer 4 in the non-first pit region of the epitaxial layer structure, and performing rapid thermal annealing (RTA) to improve its current spreading performance;

[0084] A Ag reflective layer 6 is deposited on the current diffusion layer 5, and the total thickness of the Ag reflective layer 6 ranges from 3500 to 20000 angstroms; the Ag reflective layer 6 includes a silver base layer and a surface protection layer stacked on the silver base layer, the silver base layer serves as a main reflective mirror surface, and the thickness of the silver base layer ranges from 750 to 1500 angstroms; the material of the surface protection layer includes one or more of Ti, Ni, W, Pt, and Au, and the surface protection layer is a laminated structure;

[0085] The first passivation protection layer 7 is formed by depositing the entire surface of the epitaxial layer structure formed with the Ag reflective layer 6 by plasma enhanced chemical vapor deposition technology (PECVD). The structure of the first passivation protection layer 7 can be SiO2, SiN x , single layer or stacked layer of Ti3O5;

[0086] A portion of the first passivation protection layer 7 at the bottom of the MESA hole is removed by etching to expose the N-GaN layer 2, thereby forming an N-type conductive hole; a portion of the first passivation protection layer 7 on the Ag reflective layer 6 in the P-type region is removed by etching to expose the surface protection layer of the Ag reflective layer 6, thereby forming a P-type conductive hole;

[0087] In the area outside the P-type conductive hole of the first passivation protection layer 7, a first metal connection layer 8 is plated on the entire surface by electron beam evaporation, so that the first metal connection layer 8 is connected to the N-GaN layer 2 through the N-type conductive hole; the bottom metal of the first metal connection layer 8 is Cr or Ti to ensure good ohmic contact with the N-GaN layer 2; the upper metal of the first metal connection layer 8 can be a stacked structure of metals such as Ti, Ni, Al, Pt, Au, etc., and the overall thickness of the first metal connection layer 8 ranges from 15000 to 30000 angstroms;

[0088] A second passivation protection layer 9 is deposited on the entire surface of the first metal connection layer 8. The structure of the second passivation protection layer 9 can be SiO2, SiN xThe second passivation protection layer 9 is a single layer or a stack of materials, and the total thickness of the second passivation protection layer 9 is in the range of 7000 to 20000 angstroms; the second passivation protection layer 9 on the P-type conductive hole is etched cleanly by etching to expose the Ag reflective layer 6; a part of the second passivation protection layer 9 on the first metal connection layer 8 is removed by etching to expose the first metal connection layer 8 to form an electrode connection hole;

[0089] A P electrode 10 is formed by vapor deposition in the P-type region, and the P electrode 10 fills the P-type conductive hole and the area above the P-type conductive hole, and the P electrode 10 is connected to the Ag reflective layer 6; an N electrode 11 is formed by vapor deposition in the N-type region, and the N electrode 11 fills the electrode connection hole, and the N electrode 11 is connected to the first metal connection layer 8; the structures of the P electrode 10 and the N electrode 11 are similar, and the bottom layer of the electrode structure of the two is a Cr layer or a Ti layer with a thickness range of 50 to 300 angstroms, which is mainly used to form good adhesion with the second passivation protection layer 9; the upper layer of the electrode structure of the two can be a stack of materials such as Ti, Ni, Pt, Au, Sn, etc., with a thickness range of 30,000 to 45,000 angstroms; after the electrode structure is formed, the structure of the main body of multiple flip-chip LED chips is completed.

[0090] S22, bonding a temporary support substrate to a side of the first flip-chip LED chip wafer away from the sapphire substrate;

[0091] Fig.15 A schematic diagram showing a bonding structure between a first flip-chip LED chip wafer and a temporary supporting substrate in an embodiment of the present invention is shown.

[0092] The function of the temporary support substrate 12 is to support the subsequently thinned sapphire substrate 1, to avoid stress warping and breakage caused by grinding of the sapphire substrate 1, and to provide a rigid substrate support for the subsequent photolithography and patterning process on the sapphire substrate 1. The temporary support substrate 12 can be made of high-strength materials such as sapphire sheets and glass sheets; glass sheets are preferred, as they have better light transmittance, with a light transmittance of more than 99.0%, which is beneficial to the laser transmission in the subsequent debonding process. The shape and size of the temporary support substrate 12 are consistent with those of the sapphire substrate 1, and the thickness ranges from 600 to 1000 microns. Before use, the temporary support substrate 12 is ultrasonically cleaned with acetone for 10 minutes to ensure that the dirt on the surface is cleaned.

[0093] Specifically, first, a layer of bonding glue 13 is coated on one side of the temporary support substrate 12 by spin coating; the bonding glue 13 can be selected from pyrolytic bonding glue or photolytic bonding glue, preferably photolytic bonding glue; the rotation speed of the spin coating process is controlled to be 1500-1900 rpm, and the time is 30 seconds; the thickness of the spin-coated bonding glue 13 is in the range of 20-50 microns, and the bonding glue 13 is baked on a hot plate at 90-150° C. for 5-10 minutes to dry the moisture of the bonding glue 13. The first flip-chip LED chip wafer is not coated with bonding glue 13.

[0094] Then, the glue-coated surface of the temporary support substrate 12 is placed opposite to the front side of the chip of the first flip-chip LED chip wafer (the side with the electrode structure, not the sapphire substrate 1 side), and the temporary support substrate 12 and the first flip-chip LED chip wafer are tightly bonded together by hot pressing, so that the bonding glue 13 fully fills the grooves on the chip surface. The temperature of hot pressing is controlled at 180-220°C. Too low temperature will result in loose bonding, and too high temperature will cause subsequent separation difficulties; the pressure of hot pressing is controlled at 2000-6000N. Too low pressure will result in loose bonding, and too high pressure will cause the bonding glue 13 to overflow from the side, affecting the bonding effect; at the same time, reasonable bonding temperature and pressure are conducive to reducing the risk of breakage of the temporary support substrate 12 and the first flip-chip LED chip wafer.

[0095] S23, using the temporary support substrate as a support, grinding and polishing the sapphire substrate in sequence to form a light emitting surface;

[0096] Fig.16 A schematic diagram of the structure of a sapphire substrate after grinding and polishing in an embodiment of the present invention is shown.

[0097] Specifically, the thickness of the ground sapphire substrate 1 is controlled between 20 and 80 μm, which can effectively reduce the light loss; and the ground substrate 1 is polished for 15 to 30 minutes to eliminate the grinding scratches on the surface of the sapphire substrate 1 .

[0098] Furthermore, the ground and polished surface of the sapphire substrate 1 is cleaned for 10 minutes using O2 or Ar plasma and then rinsed and dried. This is not only beneficial to improving the light extraction effect, but also beneficial to improving the adhesion stability of the subsequent reflective base layer 100 and reducing the growth defects of the reflective base layer 100.

[0099] Fig.17 The third process diagram of the method for preparing a high-brightness flip-chip LED chip in an embodiment of the present invention is shown. After step S15 of implementation 1, the following steps are further included:

[0100] S31, peeling off the temporary support substrate to obtain a second flip-chip LED chip wafer;

[0101] Fig.18A schematic structural diagram of a second flip-chip LED chip wafer in an embodiment of the present invention is shown.

[0102] Specifically, the temporary support substrate 12 is placed upward in a 365nm ultraviolet laser for 20 to 30 minutes. The bonding glue 13 will decompose after fully absorbing the laser energy, which is convenient for the peeling of the temporary support substrate 12. To ensure the laser irradiation effect, N2 can be introduced for atmosphere protection.

[0103] S32, cleaning and drying the surface of the second flip-chip LED chip wafer after peeling off the temporary supporting substrate;

[0104] Specifically, the second flip-chip LED chip wafer is immersed in a bonding adhesive 13 cleaning agent and ultrasonically cleaned for 20 to 30 minutes, then cleaned with acetone for 5 minutes, and finally dried.

[0105] S33, cutting the dried second flip-chip LED chip wafer to obtain a plurality of core particles;

[0106] Fig.19 A schematic diagram of the structure of the core particle in an embodiment of the present invention is shown.

[0107] After the core particles are processed through processes such as packaging, the finished flip-chip LED chip is obtained.

[0108] The method for preparing a high-brightness flip-chip LED chip of the present invention can ensure that the sapphire substrate 1 of the flip-chip LED chip wafer does not suffer from stress warping and fragmentation during the grinding and thinning process by bonding a temporary supporting substrate 12, and can reduce the thickness of the sapphire substrate 1 to the greatest extent, thereby reducing the light loss caused by the thickness of the sapphire substrate 1; by peeling off the temporary supporting substrate 12 through laser irradiation, it is possible to avoid wafer fragmentation caused by external force during the separation process, which is beneficial to improving the yield of core particles.

[0109] Example 3

[0110] The present invention also provides a high-brightness flip-chip LED chip, which is prepared by the high-brightness flip-chip LED chip preparation method, has high light extraction efficiency and good product yield.

[0111] The above is a detailed introduction to a high-brightness flip-chip LED chip and a preparation method thereof provided in an embodiment of the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for a person skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for preparing a high-brightness flip-chip LED chip, characterized in that: The following steps are involved: S11, depositing a reflective base layer on the light-emitting surface of the wafer having a plurality of flip-chip LED chip bodies; S12, etching a plurality of groove structures on the surface of the reflective base layer, wherein the groove structures correspond to the flip-chip LED chip bodies one by one, the groove walls of the groove structures serve as reflective walls, and the groove bottom areas of the groove structures serve as anti-reflection areas; S13, depositing a reflective metal film along the surface of the reflective wall; S14, depositing a light screening layer along the surface of the reflective metal film and the anti-reflection area; S15, etching a plurality of circular holes on the light screening layer in the anti-reflection region, wherein the plurality of circular holes expose the surface of the anti-reflection region.

2. The method for preparing a high brightness flip-chip LED chip according to claim 1, characterized in that: The material of the reflective base layer is SiO2 or SiN x , the thickness of the reflective base layer is 5000 to 20000 angstroms.

3. The method for preparing a high brightness flip-chip LED chip according to claim 1, characterized in that: The reflective base layer is formed by deposition using a plasma enhanced chemical vapor deposition technique, with a deposition power ranging from 90 to 150 W and a deposition temperature ranging from 120 to 150° C.

4. The method for preparing a high brightness flip-chip LED chip according to claim 1, characterized in that: The angle between the side wall of the reflective enclosure and the surface of the anti-reflection area is an obtuse angle, and the angle range of the obtuse angle is 120° to 160°.

5. The method for preparing a high brightness flip-chip LED chip according to claim 1, characterized in that: The thickness of the reflective base layer in the anti-reflection zone is H1, 1000 angstroms < H1 < 5000 angstroms, H1 = 1100*N angstroms, N ≥ 1 and N is an integer.

6. The method for preparing a high brightness flip-chip LED chip according to claim 1, characterized in that: The step of depositing a reflective metal film along the surface of the reflective fence comprises: Depositing Cr or Ti along the surface of the reflective wall to form a bottom film layer; Depositing one or more of Ag, Al, Cu, Au, and Pt along the surface of the base film layer to form a reflective layer; The base film layer and the reflective layer constitute the reflective metal film.

7. The method for preparing a high brightness flip-chip LED chip according to claim 6, characterized in that: The thickness of the base film layer ranges from 25 to 50 angstroms, the thickness of the reflective layer ranges from 100 to 5000 angstroms, and the reflective layer is a single-layer structure or a laminated structure.

8. The method for preparing a high brightness flip-chip LED chip according to claim 1, characterized in that: The material of the light screening layer is SiO2, SiN x , SiC or AlN, the light screening layer is a single-layer structure or a stacked structure, the thickness of the light screening layer is H2, 1000 angstroms < H2 < 10000 angstroms, H2 = 1100*M angstroms, M≥1 and M is an integer.

9. The method for preparing a high brightness flip-chip LED chip according to claim 1, characterized in that: The diameter of the circular holes ranges from 2 to 15 micrometers, the center distance between two adjacent circular holes ranges from 25 to 50 micrometers, and the multiple circular holes are arranged at equal intervals.

10. A high brightness flip-chip LED chip, characterized in that: The high-brightness flip-chip LED chip is prepared by the preparation method of the high-brightness flip-chip LED chip according to any one of claims 1 to 9.

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