Reversed-polarity LED chip and manufacturing method thereof

Abstract

The invention relates to the technical field of semiconductors, in particular to a reversed-polarity LED chip and a manufacturing method thereof. The reversed-polarity LED chip comprises a patterned silicon substrate, a reflector covering layer, a silicon dioxide leveling layer, a transparent conductive adhesive layer, a window layer, a P-type laminated layer, a light-emitting layer and an N-type laminated layer which are sequentially arranged from bottom to top; the upper surface of the patterned silicon substrate is provided with a plurality of circular-truncated-cone-shaped bulges; the reflecting mirror covering layer covers the whole surface of the side, provided with the circular-truncated-cone-shaped protrusions, of the patterned silicon substrate, a plurality of through holes are formed in the lower surface of the silicon dioxide leveling layer, and the through holes are matched with the reflecting mirror convex face portion in a sleeved mode. And the upper end surface of the convex surface part of the reflecting mirror is directly contacted and electrically connected with the lower surface of the transparent conductive adhesive layer. According to the preparation method of the reversed-polarity LED chip, the manufacturing process is simple, the manufacturing cost is low, and the performance of the reversed-polarity LED chip is reliable and stable.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a reverse polarity LED chip and a manufacturing method thereof. Background Art

[0002] Reverse polarity LED chips, with a flip-chip structure design, have higher luminous efficiency, long service life, and are green, energy-saving, and environmentally friendly. They are widely used in daily life, such as lighting, traffic signal display, and later outdoor large-screen display. With the continuous expansion of the scope and scenarios of application, higher requirements are placed on the reliability of chips. At the same time, it is hoped that the chip production process can be simplified and the cost can be reduced as much as possible to meet customer demand for low-cost and high-reliability reverse polarity LED chip products. The present invention aims to achieve the production of reverse polarity LED chips with simple procedures, low costs, and high reliability. Summary of the invention

[0003] The purpose of the present invention is to provide a reverse polarity LED chip and a manufacturing method thereof, which can effectively improve the reliability of the reverse polarity LED chip, simplify the LED manufacturing procedure, and realize low-cost chip manufacturing.

[0004] In order to solve the above problems, the technical solution provided by the present invention is: The present invention provides a reverse polarity LED chip, comprising a patterned silicon substrate, a reflector cover layer, a silicon dioxide leveling layer, a transparent conductive adhesive layer, a window layer, a P-type stack, a light-emitting layer and an N-type stack arranged in sequence from bottom to top; The upper surface of the patterned silicon substrate has a plurality of truncated cone-shaped protrusions; The reflector cover layer covers the entire surface of the patterned silicon substrate on the side having the truncated cone-shaped protrusion, so that the reflector cover layer forms a reflector plane portion and a reflector convex portion on the patterned silicon substrate; The silicon dioxide leveling layer has a plurality of through holes, the through holes are fitted with the convex portion of the reflector, and the upper surface of the silicon dioxide leveling layer is flush with the upper surface of the frustum of the reflector; The upper end surface of the convex portion of the reflector is in direct contact with the lower surface of the transparent conductive adhesive layer to form an electrical connection.

[0005] Furthermore, the chip further comprises a front electrode and a back electrode, wherein the front electrode is arranged in the middle of the upper surface of the N-type stack; and the back electrode is arranged on the lower surface of the patterned silicon substrate; The truncated cone-shaped protrusions are evenly distributed around the outer sides directly below the front electrode.

[0006] Furthermore, the angle between the side wall of the truncated cone-shaped protrusion and the horizontal line is 30° to 60°.

[0007] Furthermore, the number of the truncated cone-shaped protrusions is 4 to 20.

[0008] Furthermore, the height of the truncated cone-shaped protrusion is 4 μm to 10 μm.

[0009] Furthermore, the preparation material of the reflector cover layer includes Ti, Pt, Au, Ti, Pt and Au deposited sequentially from bottom to top; The thickness of the reflector cover layer is 3 μm to 4 μm.

[0010] Furthermore, the preparation material of the reflector cover layer also includes an aluminum oxide layer, and the aluminum oxide layer is arranged on the surface away from the patterned silicon substrate; and at least part of the aluminum oxide layer is missing from the upper end surface of the truncated cone-shaped protrusion, so that an electrical connection is formed between the reflector cover layer and the transparent conductive adhesive layer; The thickness of the aluminum oxide layer is 80 angstroms to 100 angstroms.

[0011] Furthermore, the transparent conductive adhesive layer is made of a material selected from transparent polymer polyurethane or polyacrylate containing conductive fillers, and the conductive fillers are carbon nanotubes; The thickness of the transparent conductive adhesive layer is 1 μm to 1.5 μm.

[0012] Furthermore, the chip further comprises a passivation layer, and the passivation layer covers the surface of the chip cutting path.

[0013] The present invention also provides a method for manufacturing the above-mentioned reverse polarity LED chip, the manufacturing method comprising: S1, providing a GaAs substrate as a reverse polarity epitaxial structure growth substrate; S2, sequentially growing an N-type stack, a light-emitting layer, a P-type stack and a window layer on a GaAs substrate, wherein the N-type stack includes a roughening layer, a current spreading layer and an N-type limiting layer, to prepare an epitaxial wafer; S3, taking the patterned silicon substrate for organic cleaning, and completing the evaporation of the reflector cover layer material by electron beam evaporation; S4, cleaning the surface of the reflector cover layer with an organic solution, and depositing a SiO2 dielectric film by PECVD; S5, grinding and polishing the SiO2 dielectric film by CMP method until Au metal is exposed, thereby completing the preparation of the silicon dioxide leveling layer; S6, cleaning the epitaxial wafer with an acid-base solution, and coating a transparent conductive adhesive layer on the surface of the epitaxial wafer by spin coating; S7, attaching the epitaxial wafer transparent conductive adhesive layer and the Si wafer after CMP together, and placing them in a pressing fixture to complete the bonding of the two; S8, removing the GaAs substrate from the bonded source sheets by chemical etching to expose the N-type stacked layer; S9, through negative photolithography, lift-off is used to complete the front electrode production and high-temperature fusion; S10, using positive resist to make cutting path patterns, and using dry etching to etch the cutting paths; S11, using positive resist to make a roughening protection pattern, and roughening the surface of the N-type stack by wet etching; S12, depositing a passivation layer material by PECVD, and completing the preparation of the passivation layer by photolithography and etching; S13, thinning the patterned silicon substrate, making the back electrode, laser cutting, and testing to complete the LED core particle production.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The reflector cover layer is deposited by electron beam evaporation directly on the patterned silicon substrate, the pattern of the patterned silicon substrate is adapted to the required P-side current conduction channel, the SiO2 dielectric film is deposited by PECVD, and then the SiO2 dielectric film is ground and polished by CMP to expose the reflector cover layer on the upper end face of the truncated cone-shaped protrusion until the surface Au layer is exposed. The above process does not require wet etching. While completing the surface flattening, the metal on the truncated cone-shaped protrusion is exposed. The transparent conductive adhesive layer is coated on the surface of the epitaxial wafer by spin coating, and the transparent conductive adhesive layer of the epitaxial wafer and the Si wafer after CMP are attached together to complete the bonding of the two. The above operation is simple, and the epitaxial wafer and the Si wafer are combined by the transparent conductive adhesive layer to achieve electrical connection between the transparent conductive adhesive layer and the metal of the reflector cover layer. The manufacturing process provided by the present application does not require multiple metal evaporation, multiple solution corrosion and wet etching processes of the traditional process, and the process is simple, reliable and easy.

[0015] 2. The reverse polarity LED chip structure provided in the present application utilizes a patterned silicon substrate with truncated cone-shaped protrusions, covers a layer of reflector material according to the shape of the patterned silicon substrate to form a reflector covering layer, and then uses a silicon dioxide leveling layer to fill and level it. The structure uses a patterned silicon substrate covered with a mirror metal layer to achieve direct contact between the reflector covering layer and the transparent conductive adhesive layer. The P-side current conduction effect is stable and reliable. The structure does not need to be prepared by wet etching. The interface between the reflector covering layer and the silicon dioxide leveling layer has high flatness, which is also beneficial to improving light reflection.

[0016] 3. In the present application, the angle between the side wall of the truncated cone-shaped protrusion and the horizontal line is set to 30° to 60°, so as to facilitate the uniform deposition of the reflector cover layer on the surface of the truncated cone-shaped protrusion, thereby obtaining a highly reliable and stable P-face current conduction effect, and ensuring the flatness of the metal layer on the surface of the truncated cone-shaped protrusion to ensure a good light reflection effect.

[0017] 4. The reflector cover layer material of the present application is selected from Ti, Pt, Au, Ti, Pt, Au and Al2O3 which are sequentially deposited. It not only has good light reflection effect, but also has stable and reliable performance. Al2O3 can play an adhesion role and enhance the bonding force between the silicon dioxide leveling layer and the reflector metal material. The transparent conductive adhesive layer has transparency, conductivity and good bonding effect. The epitaxial wafer and the Si wafer after CMP can be attached together through the transparent conductive adhesive layer to complete the bonding of the two. The epitaxial wafer and the Si wafer are combined through the transparent conductive adhesive layer to achieve electrical connection, and it has good light transmittance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 This is a schematic diagram of the epitaxial structure of a reverse polarity LED chip shown in some embodiments of the present application; Figure 2 This is a schematic diagram of a patterned silicon substrate structure shown in some embodiments of the present application; Figure 3 A schematic diagram of a structure for forming a reflector cover layer on a patterned silicon substrate according to some embodiments of the present application; Figure 4 It is a schematic structural diagram of another viewing angle of forming a reflector cover layer on a patterned silicon substrate as shown in some embodiments of the present application; Figure 5 This is a schematic diagram of a structure in which a silicon dioxide dielectric film is formed on a patterned silicon substrate as shown in some embodiments of the present application; Figure 6 This is a schematic diagram of a structure for forming a silicon dioxide leveling layer on a patterned silicon substrate as shown in some embodiments of the present application; Figure 7 for Figure 6 A partial enlarged schematic diagram of the A part; Figure 8 This is a schematic diagram of the structure of a reverse polarity LED chip shown in some embodiments of the present application; Fig. 9 This is a schematic structural diagram of another viewing angle of the reverse polarity LED chip shown in some embodiments of the present application; Description of the drawings: 1. GaAs substrate; 2. N-type stack; 3. Light-emitting layer; 4. P-type stack; 5. Window layer; 6. Patterned silicon substrate; 61. Concave-conical protrusion; 7. Reflector covering layer; 71. Reflector plane portion; 72. Reflector convex portion; 73. Mirror metal layer; 74. Aluminum oxide layer; 8. Silicon dioxide leveling layer; 81. Through hole; 9. Transparent conductive adhesive layer; 10. Front electrode; 11. Passivation layer; 12. Back electrode. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0020] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present application. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so that once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0021] In the description of the present application, it should be understood that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present application.

[0022] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0023] The present application is further described in detail below with reference to specific embodiments: Example 1 The reverse polarity LED chip provided in this embodiment, Figure 8 This is a schematic diagram of the structure of a reverse polarity LED chip shown in some embodiments of the present application; Fig. 9 This is a schematic diagram of the structure of the reverse polarity LED chip from another perspective shown in some embodiments of the present application; specifically, the structure provided by the present application is as follows, please refer to Figure 8 and Fig. 9 A reverse polarity LED chip includes a patterned silicon substrate 6, a reflector cover layer 7, a silicon dioxide leveling layer 8, a transparent conductive adhesive layer 9, a window layer 5, a P-type stack 4, a light-emitting layer 3 and an N-type stack 2, which are arranged in sequence from bottom to top; the upper surface of the patterned silicon substrate 6 has a plurality of truncated cone-shaped protrusions 61 (see Fig. 9 The reflector cover layer 7 covers the entire surface of the patterned silicon substrate 6 on the side having the truncated cone-shaped protrusion 61, so that the reflector cover layer 7 forms a reflector plane portion 71 and a reflector convex portion 72 on the patterned silicon substrate 6 (the structure of the reflector plane portion 71 and the reflector convex portion 72 can be further referred to). Figure 3 and Figure 4 The silicon dioxide leveling layer 8 has a plurality of through holes 81, and the through holes 81 are fitted with the convex portion 72 of the reflector, and the upper surface of the silicon dioxide leveling layer 8 is flush with the upper surface of the convex portion 72 of the reflector (the structure of the through holes 81 and the convex portion 72 of the reflector can be further referred to Figure 6 ); The upper surface of the reflector convex portion 72 is in direct contact with the lower surface of the transparent conductive adhesive layer 9 and forms an electrical connection.

[0024] The reverse polarity LED chip structure provided by the present application utilizes a patterned silicon substrate 6 with a truncated cone-shaped protrusion 61, and a layer of reflector material is covered according to the shape of the patterned silicon substrate 6 to form a reflector covering layer 7, and then a silicon dioxide leveling layer 8 is used to fill and level the upper end surface of the reflector convex portion 72 to expose the metal, thereby achieving direct contact with the lower surface of the transparent conductive adhesive layer 9, and serving as a P-side current channel to achieve P-side current conduction. The P-side current conduction channel is directly realized through the patterned silicon substrate 6 covered with a mirror metal layer 73, without the need for wet etching. The P-side current conduction effect is stable and reliable, the interface between the reflector covering layer 7 and the silicon dioxide leveling layer 8 has high flatness, and is also beneficial to improving light reflection.

[0025] According to some preferred embodiments, the chip also includes a front electrode 10 and a back electrode 12, the front electrode 10 is arranged in the middle of the upper surface of the N-type stack (the front electrode 10 covers a partial area of ​​the upper surface of the N-type stack, the front electrode 10 is arranged at the very center of the upper surface of the N-type stack, the shape of the front electrode 10 can be circular, and the surrounding areas outside the area covered by the front electrode 10 are light-emitting areas); the back electrode 12 is arranged on the lower surface of the patterned silicon substrate 6; the truncated cone-shaped protrusions 61 are evenly distributed around the outer side directly below the front electrode 10, so as to facilitate the uniform distribution of current around the front electrode 10 and avoid the current gathering under the front electrode 10.

[0026] According to some preferred embodiments, the angle between the side wall of the truncated cone-shaped protrusion 61 and the horizontal line is 30° to 60°, so as to facilitate the uniform deposition of the reflector cover layer 7 on the surface of the truncated cone-shaped protrusion 61, obtain a P-face current conduction effect with high reliability and stability, and ensure the flatness of the metal layer on the surface of the truncated cone-shaped protrusion 61 to facilitate a good light reflection effect. As a specific implementation, the angle between the side wall of the truncated cone-shaped protrusion 61 and the horizontal line is 45°.

[0027] According to some preferred embodiments, the number of the truncated cone-shaped protrusions 61 is 4 to 20. Providing an appropriate number of truncated cone-shaped protrusions 61 is conducive to obtaining a more appropriate P-side current conduction effect. As some specific implementations, the number of the truncated cone-shaped protrusions 61 is 12.

[0028] According to some preferred embodiments, the height of the truncated cone-shaped protrusion 61 is 4 μm to 10 μm.

[0029] According to some preferred embodiments, the preparation materials of the reflector covering layer 7 include Ti, Pt, Au, Ti, Pt and Au evaporated in sequence from bottom to top; the thickness of the reflector covering layer 7 is 3μm~4μm. The above-mentioned reflector covering layer 7 is made by evaporating the above-mentioned materials in sequence, which not only has a good light reflection effect, but also has stable and reliable performance.

[0030] According to some preferred embodiments, please combine Figure 7 The preparation material of the reflector cover layer 7 also includes an aluminum oxide layer 74, and the aluminum oxide layer 74 is arranged on the surface away from the patterned silicon substrate 6; and at least part of the aluminum oxide layer 74 is missing from the upper end surface of the truncated cone shaped protrusion 61, so that the reflector cover layer 7 and the transparent conductive adhesive layer 9 are electrically connected; further, the aluminum oxide layer 74 on the upper end surface of the truncated cone shaped protrusion 61 is completely removed by grinding, and the thickness of the aluminum oxide layer 74 is 80 angstroms to 100 angstroms. In the present application, the aluminum oxide layer 74 has an adhesion effect, which can enhance the bonding force between the silicon dioxide leveling layer 8 and the reflector metal material.

[0031] According to some preferred embodiments, the preparation material of the transparent conductive adhesive layer 9 is selected from transparent polymer polyurethane or polyacrylate containing conductive filler, and the conductive filler is carbon nanotube. When in use, in order to enhance the plasticity of the transparent conductive adhesive layer 9, an appropriate amount of plasticizer can be further added. The above-mentioned transparent conductive adhesive layer 9 provided in the present application has transparency, conductivity and good bonding effect, and can stick the epitaxial wafer and the Si wafer after CMP together to complete the bonding of the two. After the epitaxial wafer and the Si wafer are combined through the transparent conductive adhesive layer 9, electrical connection is achieved, and at the same time, it has good light transmittance.

[0032] The thickness of the transparent conductive adhesive layer 9 is 1 μm to 1.5 μm.

[0033] According to some preferred embodiments, the chip further comprises a passivation layer 11, and the passivation layer 11 covers the surface of the chip cutting path. Preferably, the passivation layer 11 is made of a material selected from SiN, SiO or SiN / SiO composite material. By using the above passivation material, the edge and side wall of the chip can be protected and insulated, effectively avoiding leakage.

[0034] As can be seen from the above, the reverse polarity LED chip provided in the embodiment of the present application has the following advantages: 1. The reverse polarity LED chip structure provided in the present application utilizes a patterned silicon substrate with truncated cone-shaped protrusions, covers a layer of reflector material according to the shape of the patterned silicon substrate to form a reflector covering layer, and then uses a silicon dioxide leveling layer to fill and level. The structure uses a patterned silicon substrate covered with a mirror metal layer to achieve direct contact between the reflector covering layer and the transparent conductive adhesive layer. The P-side current conduction effect is stable and reliable. The structure does not need to be prepared by wet etching. The interface between the reflector covering layer and the silicon dioxide leveling layer has high flatness, which is beneficial to improving light reflection.

[0035] 2. In the present application, the angle between the side wall of the truncated cone-shaped protrusion and the horizontal line is set to 30° to 60°, so as to facilitate the uniform deposition of the reflector cover layer on the surface of the truncated cone-shaped protrusion, thereby obtaining a highly reliable and stable P-face current conduction effect, and ensuring the flatness of the metal layer on the surface of the truncated cone-shaped protrusion to ensure a good light reflection effect.

[0036] 3. The reflector cover layer material of the present application is selected from Ti, Pt, Au, Ti, Pt, Au and Al2O3 which are sequentially deposited. It not only has good light reflection effect, but also has stable and reliable performance. Al2O3 can play an adhesion role and enhance the bonding force between the silicon dioxide leveling layer and the reflector metal material. The transparent conductive adhesive layer has transparency, conductivity and good bonding effect. The epitaxial wafer and the Si wafer after CMP can be attached together through the transparent conductive adhesive layer to complete the bonding of the two. The epitaxial wafer and the Si wafer are combined through the transparent conductive adhesive layer to achieve electrical connection, and it has good light transmittance.

[0037] Example 2 Please combine Figures 1 to 9 This embodiment provides a method for manufacturing a reverse polarity LED chip, the manufacturing method comprising: Step 1: Please combine Figure 1 , Figure 1 Schematic diagram of the epitaxial structure of the reverse polarity LED chip shown in some embodiments of the present application; a GaAs substrate 1 is provided as a growth substrate for the reverse polarity epitaxial structure; an N-type stack 2, a light-emitting layer 3, a P-type stack 4 and a window layer 5 are sequentially grown on the GaAs substrate 1, and the N-type stack 2 includes a roughening layer, a current spreading layer and an N-type limiting layer, to prepare an epitaxial wafer; As some preferred embodiments, the window layer 5 is made of GaP material with a thickness of 0.5 μm to 1.0 μm, and the surface doping thickness is about 0.3 μm; Step 2: Please combine Figures 2 to 4 , Figure 2 This is a schematic diagram of a patterned silicon substrate structure shown in some embodiments of the present application; Figure 3 A schematic diagram of a structure for forming a reflector cover layer on a patterned silicon substrate according to some embodiments of the present application; Figure 4 Another perspective structural schematic diagram of forming a reflector cover layer on a patterned silicon substrate shown in some embodiments of the present application; the prepared patterned silicon substrate 6 is organically cleaned, and the evaporation of the reflector cover layer 7 material is completed by electron beam evaporation; the thickness of the patterned silicon substrate 6 used in the present application can be 200μm to 300μm, and the height of the truncated cone-shaped protrusion 61 set on its surface is 4μm to 10μm; As some preferred embodiments, the reflector cover layer 7 is made of Ti / Pt / Au / Ti / Pt / Au / Al2O3 arranged in sequence, with a total thickness of 3 μm to 4 μm, wherein the thickness of Al2O3 is 100 angstroms; Step 3: Please combine Figure 5 , Figure 5 Schematic diagram of the structure of forming a silicon dioxide dielectric film on a patterned silicon substrate 6 shown in some embodiments of the present application; the surface of the reflector cover layer 7 is cleaned with an organic solution, and a SiO2 dielectric film is deposited by PECVD, and the SiO2 dielectric film is deposited to a thickness of 8 μm to 10 μm; Step 4: Please combine Figure 6 and Figure 7 , Figure 6 This is a schematic diagram of a structure for forming a silicon dioxide leveling layer on a patterned silicon substrate as shown in some embodiments of the present application; Figure 7 for Figure 6 A partial enlarged schematic diagram of the middle A portion; using the CMP method, the SiO2 dielectric film and the aluminum oxide layer 74 on the upper end surface of the truncated cone-shaped protrusion 61 are ground and polished to remove until the Au metal on the outside is exposed, completing the preparation of the silicon dioxide leveling layer 8; Please combine the following steps 5 to 12 Figure 8 and Fig. 9 , Figure 8 This is a schematic diagram of the structure of a reverse polarity LED chip shown in some embodiments of the present application; Fig. 9 This is a schematic structural diagram of another viewing angle of the reverse polarity LED chip shown in some embodiments of the present application; Step 5: Clean the epitaxial wafer with an acid-base solution, and apply a transparent conductive adhesive layer 9 on the surface of the epitaxial wafer by spin coating. The specific method of spin coating is to spin coat the surface of the epitaxial wafer at a speed of 1000 r / s for 5 seconds, then at a speed of 3000 r / s for 30 seconds, and then post-bake in a nitrogen-filled furnace at a post-bake temperature of 100° C. for 15 minutes. As some preferred embodiments, the thickness of the transparent conductive adhesive layer 9 is 1.0 μm to 1.5 μm; Step 6: Paste the epitaxial wafer transparent conductive adhesive layer 9 and the Si wafer after CMP together, place them in a special pressing fixture, put them into a pressing machine, and complete the bonding of the two at a high temperature and low pressure of 350°C and a low pressure of 2000Kg; Step 7: Place the bonded source wafers into a mixed solution of ammonia and hydrogen peroxide, remove the GaAs substrate 1 by chemical etching, and expose the N-type stack 2; Step 8: The front electrode 10 is fabricated by negative photolithography in combination with lift-off and then fused at 300°C; Step 9: Use positive resist to make cutting path patterns, and use dry etching to etch the cutting paths until 2000 angstroms remain in the window layer 5; Step 10: Use positive resist to make a roughening protection pattern, and use wet etching to roughen the surface of the N-type stack 2, with a phosphoric acid solution as the wet etching solution; Step 11: using PECVD to deposit the material of the passivation layer 11, the material of the passivation layer 11 is SiN, and photolithography and etching are performed to complete the preparation of the passivation layer 11; Step 12: Thin the patterned silicon substrate 6, make the back electrode 12, laser cut, and test to complete the LED core production.

[0038] From the above, it can be seen that the method for manufacturing the reverse polarity LED chip provided in the embodiment of the present application has the following advantages: 1. The reflector cover layer is deposited directly on the patterned silicon substrate by electron beam evaporation. The pattern of the patterned silicon substrate is adapted to the required P-side current conduction channel. The SiO2 dielectric film is deposited by PECVD, and then the SiO2 dielectric film is ground and polished by CMP to expose the reflector cover layer on the upper end face of the truncated cone-shaped protrusion until the surface Au layer is exposed. The above process does not require wet etching. While completing the surface flattening, the metal on the truncated cone-shaped protrusion is exposed, which facilitates the subsequent electrical connection. 2. In the present application, a transparent conductive adhesive layer is coated on the surface of the epitaxial wafer by spin coating, and the transparent conductive adhesive layer of the epitaxial wafer and the Si wafer after CMP are attached together to complete the bonding of the two. The above operation is simple, and the epitaxial wafer and the Si wafer are combined through the transparent conductive adhesive layer to achieve electrical connection between the transparent conductive adhesive layer and the metal of the reflector covering layer.

[0039] 3. The manufacturing process provided by this application does not require multiple metal evaporation, multiple solution corrosion and wet etching processes of traditional processes, and the process is simple, reliable and easy.

[0040] Therefore, the method for preparing the reverse polarity LED chip provided by the present application has the advantages of simple manufacturing process and low manufacturing cost, and the prepared reverse polarity LED chip has the advantages of reliable and stable performance. Since the method for preparing the reverse polarity LED chip provided by the embodiment of the present application obtains the reverse polarity LED chip in the above embodiment 1, it also has the advantages of the reverse polarity LED chip in the above embodiment 1, which will not be described in detail here.

[0041] For content not described in this embodiment, please refer to the relevant description in the rest of this application.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application and not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present application can still be modified or some technical features can be replaced by equivalents, which should all be included in the scope of the technical solution requested for protection in this application.

Claims

1. A reverse polarity LED chip, characterized in that: It includes a patterned silicon substrate, a reflector cover layer, a silicon dioxide leveling layer, a transparent conductive adhesive layer, a window layer, a P-type stack, a light-emitting layer and an N-type stack arranged in sequence from bottom to top; The upper surface of the patterned silicon substrate has a plurality of truncated cone-shaped protrusions; The reflector cover layer covers the entire surface of the patterned silicon substrate on the side having the truncated cone-shaped protrusion, so that the reflector cover layer forms a reflector plane portion and a reflector convex portion on the patterned silicon substrate; The silicon dioxide leveling layer has a plurality of through holes, the through holes are fitted with the convex portion of the reflector, and the upper surface of the silicon dioxide leveling layer is flush with the upper surface of the frustum of the reflector; The upper end surface of the convex portion of the reflector is in direct contact with the lower surface of the transparent conductive adhesive layer to form an electrical connection.

2. A reverse polarity LED chip according to claim 1, characterized in that: The chip further comprises a front electrode and a back electrode, wherein the front electrode is arranged at the middle of the upper surface of the N-type stack; and the back electrode is arranged at the lower surface of the patterned silicon substrate; The truncated cone-shaped protrusions are evenly distributed around the outer sides directly below the front electrode.

3. A reverse polarity LED chip according to claim 2, characterized in that: The angle between the side wall of the truncated cone-shaped protrusion and the horizontal line is 30° to 60°.

4. The reverse polarity LED chip according to claim 3, characterized in that: The number of the truncated cone-shaped protrusions is 4 to 20.

5. The reverse polarity LED chip according to claim 1, characterized in that: The height of the truncated cone-shaped protrusion is 4 μm to 10 μm.

6. The reverse polarity LED chip according to claim 1, characterized in that: The preparation material of the reflector cover layer includes Ti, Pt, Au, Ti, Pt and Au deposited sequentially from bottom to top; The thickness of the reflector cover layer is 3 μm to 4 μm.

7. The reverse polarity LED chip according to claim 6, characterized in that: The preparation material of the reflector cover layer also includes an aluminum oxide layer, and the aluminum oxide layer is arranged on the surface away from the patterned silicon substrate; and at least part of the aluminum oxide layer is missing from the upper end surface of the truncated cone-shaped protrusion, so that an electrical connection is formed between the reflector cover layer and the transparent conductive adhesive layer; The thickness of the aluminum oxide layer is 80 angstroms to 100 angstroms.

8. The reverse polarity LED chip according to claim 1, characterized in that: The transparent conductive adhesive layer is made of a material selected from transparent polymer polyurethane or polyacrylate containing conductive fillers, and the conductive fillers are carbon nanotubes; The thickness of the transparent conductive adhesive layer is 1 μm to 1.5 μm.

9. The reverse polarity LED chip according to claim 1, characterized in that: The chip further comprises a passivation layer, and the passivation layer covers the surface of the chip cutting path.

10. A method for manufacturing a reverse polarity LED chip according to any one of claims 1 to 9, characterized in that: The production method comprises: S1, providing a GaAs substrate as a reverse polarity epitaxial structure growth substrate; S2, sequentially growing an N-type stack, a light-emitting layer, a P-type stack and a window layer on a GaAs substrate, wherein the N-type stack includes a roughening layer, a current spreading layer and an N-type limiting layer, to prepare an epitaxial wafer; S3, taking the patterned silicon substrate for organic cleaning, and completing the evaporation of the reflector cover layer material by electron beam evaporation; S4, cleaning the surface of the reflector cover layer with an organic solution, and depositing a SiO2 dielectric film by PECVD; S5, grinding and polishing the SiO2 dielectric film by CMP method until Au metal is exposed, thereby completing the preparation of the silicon dioxide leveling layer; S6, cleaning the epitaxial wafer with an acid-base solution, and coating a transparent conductive adhesive layer on the surface of the epitaxial wafer by spin coating; S7, attaching the epitaxial wafer transparent conductive adhesive layer and the Si wafer after CMP together, and placing them in a pressing fixture to complete the bonding of the two; S8, removing the GaAs substrate from the bonded source sheets by chemical etching to expose the N-type stacked layer; S9, through negative photolithography, lift-off is used to complete the front electrode production and high-temperature fusion; S10, using positive resist to make cutting path patterns, and using dry etching to etch the cutting paths; S11, using positive resist to make a roughening protection pattern, and roughening the surface of the N-type stack by wet etching; S12, depositing a passivation layer material by PECVD, and completing the preparation of the passivation layer by photolithography and etching; S13, thinning the patterned silicon substrate, making the back electrode, laser cutting, and testing to complete the LED core production.

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