An Inverted BLU Light-Emitting Diode Chip and Its Manufacturing Method

Abstract

The present invention belongs to the technical field of semiconductor devices, and particularly relates to an inverted BLU light-emitting diode chip and a preparation method thereof. The chip includes a substrate, an epitaxial layer, a first Bragg reflection layer, and a second Bragg reflection layer. The epitaxial layer is disposed on the substrate, and the first Bragg reflection layer is disposed on a side of the substrate facing away from the epitaxial layer for reflecting light with an angle between 45° and 90° with respect to the substrate. The second Bragg reflection layer is disposed on a side of the first Bragg reflection layer facing away from the substrate for reflecting light with an angle between 0° and 45° with respect to the substrate. A through hole of the second Bragg reflection layer penetrating through the first Bragg reflection layer is provided at the center of the second Bragg reflection layer. The present invention can enhance the side light emission of the light-emitting diode chip, increase the central light intensity, and make the light emission of the center and the edge of the light-emitting diode chip uniform.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor devices, and particularly relates to an inverted BLU light-emitting diode chip and a preparation method thereof. Background Art

[0002] Existing inverted BLU chips generally provide a section of Bragg reflection layer on the back surface of the inverted light-emitting diode chip substrate, so as to increase the side light emission of the chip and increase the light-emitting angle of the light-emitting diode; for existing inverted BLU chips, if you want to further increase the light-emitting angle, you need to increase the reflectivity of the Bragg reflection layer. However, after the reflectivity is increased, the central light intensity of the light-emitting diode chip will be weakened, resulting in an abnormal situation where the edge light emission is strong and the center is weak. Summary of the Invention

[0003] In order to solve the above problems, the present invention provides an inverted BLU light-emitting diode chip and a preparation method thereof.

[0004] The present invention adopts the following technical solutions: An inverted BLU light-emitting diode chip, the chip includes a substrate, an epitaxial layer, a first section of Bragg reflection layer, and a second section of Bragg reflection layer. The epitaxial layer is disposed on the substrate, and the first section of Bragg reflection layer is disposed on the side of the substrate facing away from the epitaxial layer for reflecting light with an angle between 45° and 90° with the substrate. The second section of Bragg reflection layer is disposed on the side of the first section of Bragg reflection layer facing away from the substrate for reflecting light with an angle between 0° and 45° with the substrate. A through hole of the second section of Bragg reflection layer penetrating through to the first section of Bragg reflection layer is provided at the center of the second section of Bragg reflection layer.

[0005] Compared with the prior art, the beneficial effects of the present invention are as follows: By providing two sections of Bragg reflection layers on the back surface of the substrate and controlling the thicknesses of the two sections of Bragg reflection layers, the first section of Bragg reflection layer can reflect light with an angle between 45° and 90° with the substrate, and the second section of Bragg reflection layer can reflect light with an angle between 0° and 45° with the substrate, thereby enhancing the side light emission of the light-emitting diode chip and increasing the light-emitting angle of the light-emitting diode; moreover, the second section of Bragg reflection layer is hollowed out in the central area to form a through hole of the second section of Bragg reflection layer, so that the light with an angle between 0° and 45° with the substrate in the central area is released, increasing the central light intensity and making the light emission of the center and the edge of the light-emitting diode chip uniform.

[0006] Preferably, the first section of Bragg reflection layer is formed by a material group in which 6 to 10 groups of SiO2 layers and Ti3O5 layers are alternately stacked, the physical thickness of the SiO2 layer is between 60 and 85 nm, and the physical thickness of the Ti3O5 layer is between 33 and 50 nm.

[0007] Preferably, the second Bragg reflection layer is formed by a material group in which 6 to 10 groups of SiO2 layers and Ti3O5 layers are alternately stacked. The physical thickness of the SiO2 layer is between 85 and 100 nm, and the physical thickness of the Ti3O5 layer is between 50 and 60 nm.

[0008] Preferably, the positive projection area of the first Bragg reflection layer on the substrate is the same as the area of the substrate.

[0009] Preferably, the boundary area of the positive projection of the second Bragg reflection layer on the substrate is the same as the area of the substrate, and the bottom area of the through hole of the second Bragg reflection layer accounts for 10% to 70% of the area of the substrate.

[0010] Preferably, at least one through hole is provided in the second Bragg reflection layer, and its shape is one or more of a circle, a square, and an irregular shape.

[0011] Preferably, the epitaxial layer includes an N-type semiconductor layer, an active light-emitting layer, and a P-type semiconductor layer; the chip further includes a current blocking layer, a current spreading layer, a conductive metal layer, an insulating protective layer, and a pad layer;

[0012] The conductive metal layer includes an N-type conductive metal layer and a P-type conductive metal layer. The N-type conductive metal layer is electrically connected to the N-type semiconductor layer, and the P-type conductive metal layer is electrically connected to the current spreading layer.

[0013] Preferably, the current spreading layer is an ITO layer.

[0014] Preferably, the insulating protective layer is provided with an N-type insulating protective layer through hole and a P-type insulating protective layer through hole. The pad layer includes an N-type pad layer and a P-type pad layer. The N-type pad layer is electrically connected to the conductive metal layer through the N-type insulating protective layer through hole, and the P-type pad layer is electrically connected to the conductive metal layer through the P-type insulating protective layer through hole.

[0015] The present invention also provides a method for manufacturing a flip-chip BLU light-emitting diode chip. The manufacturing method is used to manufacture the flip-chip BLU light-emitting diode chip described in the above technical solution. The manufacturing method includes:

[0016] Providing a substrate, and preparing an epitaxial layer on the substrate. The epitaxial layer includes an N-type semiconductor layer, an active light-emitting layer, and a P-type semiconductor layer;

[0017] Fabricating a current blocking layer on the P-type semiconductor layer;

[0018] Fabricating a current spreading layer on the current blocking layer;

[0019] A conductive metal layer is fabricated on the current spreading layer, and the conductive metal layer includes an N-type conductive metal layer and a P-type conductive metal layer;

[0020] An insulating protective layer is fabricated on the conductive metal layer, and the insulating protective layer is etched to form an N-type insulating protective layer through hole and a P-type insulating protective layer through hole;

[0021] A pad layer is fabricated on the insulating protective layer, and the pad layer includes an N-type pad layer and a P-type pad layer;

[0022] The substrate is thinned, and a first Bragg reflector layer is fabricated on the back surface of the substrate;

[0023] A second Bragg reflector layer is fabricated on the back surface of the first Bragg reflector layer, and a central region of the second Bragg reflector layer is hollowed out to form a second Bragg reflector layer through hole.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: in this preparation method, two Bragg reflector layers are provided on the back surface of the substrate, and by adjusting the thicknesses of the two Bragg reflector layers, the first Bragg reflector layer can reflect light with an angle between 45° and 90° with respect to the substrate, and the second Bragg reflector layer can reflect light with an angle between 0° and 45° with respect to the substrate, thereby enhancing the side light emission of the light-emitting diode chip and increasing the light-emitting angle of the light-emitting diode; moreover, the second Bragg reflector layer is hollowed out in the central region to form a second Bragg reflector layer through hole, so that the light with an angle between 0° and 45° with respect to the substrate in the central region is released, increasing the central light intensity and making the light emission of the center and the edge of the light-emitting diode chip uniform. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0026] Figure 1 It is a schematic cross-sectional structure diagram of the first embodiment of the present invention;

[0027] Figure 2 It is a flow chart of the preparation method of the flip-chip BLU light-emitting diode chip in the first embodiment of the present invention;

[0028] Figure 3 It is a schematic cross-sectional structure diagram of the second embodiment of the present invention.

[0029] Description of the Reference Numerals:

[0030] 11 Substrate, 12 Epitaxial layer, 121 N-type semiconductor layer, 122 Active light-emitting layer, 123 P-type semiconductor layer, 13 Current blocking layer, 14 Current spreading layer, 15 Conductive metal layer, 151 N-type conductive metal layer, 152 P-type conductive metal layer, 16 Insulating protective layer, 161 N-type insulating protective layer through hole, 162 P-type insulating protective layer through hole, 17 Pad layer, 171 N-type pad layer, 172 P-type pad layer, 18 First Bragg reflection layer, 19 Second Bragg reflection layer, 191 Second Bragg reflection layer through hole. Detailed implementation manners

[0031] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are intended to explain the embodiments of the present invention, and should not be construed as limiting the present invention.

[0032] In the description of the embodiments of the present invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.

[0033] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0034] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "mounted", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0035] Embodiment 1

[0036] Refer to Figure 1, a flip-chip BLU light-emitting diode chip, which includes a substrate 11, an epitaxial layer 12, a first Bragg reflection layer 18, and a second Bragg reflection layer 19. The epitaxial layer 12 is disposed on the substrate 11, and the first Bragg reflection layer 18 is disposed on the side of the substrate 11 facing away from the epitaxial layer 12 for reflecting light with an angle between 45° and 90° with respect to the substrate 11. The second Bragg reflection layer 19 is disposed on the side of the first Bragg reflection layer 18 facing away from the substrate 11 for reflecting light with an angle between 0° and 45° with respect to the substrate 11. A through hole 191 of the second Bragg reflection layer penetrating through to the first Bragg reflection layer is provided at the center of the second Bragg reflection layer 19.

[0037] In the present invention, by providing two Bragg reflection layers on the back surface of the substrate 11 and controlling the thickness of the two Bragg reflection layers, the first Bragg reflection layer 18 can reflect light with an angle between 45° and 90° with respect to the substrate 11, and the second Bragg reflection layer 19 can reflect light with an angle between 0° and 45° with respect to the substrate 11, thereby enhancing the side light emission of the light-emitting diode chip and increasing the light-emitting angle of the light-emitting diode. Moreover, the second Bragg reflection layer 19 is hollowed out in the central region to form a through hole 191 of the second Bragg reflection layer, so that the light with an angle between 0° and 45° with respect to the substrate 11 in the central region is released, increasing the central light intensity and making the light emission of the light-emitting diode chip uniform at the center and the edge.

[0038] In this embodiment, the first Bragg reflection layer 18 is formed by a material group of 7 alternating layers of SiO2 layer and Ti3O5 layer, where the physical thickness of the SiO2 layer is 73 nm and the physical thickness of the Ti3O5 layer is 41 nm. The second Bragg reflection layer 19 is also formed by a material group of 7 alternating layers of SiO2 layer and Ti3O5 layer, where the physical thickness of the SiO2 layer is 93 nm and the physical thickness of the Ti3O5 layer is 55 nm.

[0039] The positive projection area of the first Bragg reflection layer 18 on the substrate is the same as the area of the substrate 11. The boundary area of the positive projection of the second Bragg reflection layer 19 on the substrate is the same as the area of the substrate 11, and the bottom area of the through hole 191 of the second Bragg reflection layer accounts for 40% of the area of the substrate 11. By controlling the thickness of the second Bragg reflection layer 19 and the area of the through hole 191 of the second Bragg reflection layer, the half-intensity angle of the light-emitting diode chip can be controlled under the condition of ensuring uniform light emission. In this embodiment, there is one through hole 191 of the second Bragg reflection layer, and its shape is square.

[0040] The epitaxial layer 12 includes an N-type semiconductor layer 121, an active light-emitting layer 122, and a P-type semiconductor layer 123; the chip further includes a current blocking layer 13, a current spreading layer 14, a conductive metal layer 15, an insulating protective layer 16, and a pad layer 17; the current spreading layer 14 is an ITO layer; the conductive metal layer 15 includes an N-type conductive metal layer 151 and a P-type conductive metal layer 152, the N-type conductive metal layer 151 is electrically connected to the N-type semiconductor layer 121, and the P-type conductive metal layer 152 is electrically connected to the current spreading layer 14; the insulating protective layer 16 is provided with an N-type insulating protective layer through hole 161 and a P-type insulating protective layer through hole 162, the pad layer 17 includes an N-type pad layer 171 and a P-type pad layer 172, the N-type pad layer 171 is electrically connected to the conductive metal layer 15 through the N-type insulating protective layer through hole 161, and the P-type pad layer 172 is electrically connected to the conductive metal layer 15 through the P-type insulating protective layer through hole 162.

[0041] Referring to Figure 2 , the present invention also provides a method for manufacturing a flip-chip BLU light-emitting diode chip, which is used to manufacture the flip-chip BLU light-emitting diode chip described in the above embodiments. The manufacturing method includes:

[0042] S1: Provide a substrate 11, and prepare an epitaxial layer 12 on the substrate 11. The epitaxial layer 12 includes an N-type semiconductor layer 121, an active light-emitting layer 122, and a P-type semiconductor layer 123;

[0043] S2: Fabricate a current blocking layer 13 on the P-type semiconductor layer 123;

[0044] S3: Fabricate a current spreading layer 14 on the current blocking layer 13;

[0045] S4: Fabricate a conductive metal layer 15 on the current spreading layer 14. The conductive metal layer 15 includes an N-type conductive metal layer 151 and a P-type conductive metal layer 152;

[0046] S5: Fabricate an insulating protective layer 16 on the conductive metal layer 15, and etch the insulating protective layer 16 to form an N-type insulating protective layer through hole 161 and a P-type insulating protective layer through hole 162;

[0047] S6: Fabricate a pad layer 17 on the insulating protective layer 16. The pad layer 17 includes an N-type pad layer 171 and a P-type pad layer 172;

[0048] S7: Thin the substrate 11, and fabricate a first Bragg reflector layer 18 on the back surface of the substrate 11;

[0049] S8: Fabricate a second Bragg reflector layer 19 on the back surface of the first Bragg reflector layer 18, and hollow out the central area of the second Bragg reflector layer 19 to form a second Bragg reflector layer through hole 191.

[0050] Specifically, the steps of the flip-chip BLU light-emitting diode chip preparation method shown in this embodiment specifically include:

[0051] Provide a substrate 11, and prepare an epitaxial layer 12 on the substrate 11. The epitaxial layer 12 includes an N-type semiconductor layer 121, an active light-emitting layer 122, and a P-type semiconductor layer 123;

[0052] On the above basis, deposit a SiO2 layer by plasma chemical vapor deposition technology, and then use photolithography and plasma chemical etching processes to remove part of the SiO2 layer to form a current blocking layer 13;

[0053] On the above basis, deposit an ITO layer by magnetron sputtering or electron beam evaporation process, and then use photolithography and wet chemical etching processes to remove part of the ITO layer to form a current spreading layer 14;

[0054] On the above basis, use photolithography to preset the pattern of the conductive metal layer, then deposit Cr metal by electron beam evaporation process, and then use the Lift-Off process to remove the metal layer outside the conductive metal layer to form a conductive metal layer 15. The conductive metal layer 15 includes an N-type conductive metal layer 151 and a P-type conductive metal layer 152;

[0055] On the above basis, deposit a stack of SiO2 layer and Ti3O5 layer by magnetron sputtering or electron beam evaporation process, and then use photolithography and plasma etching processes to remove part of the stack of SiO2 layer and Ti3O5 layer to form an insulating protective layer 16, as well as an N-type insulating protective layer through hole 161 and a P-type insulating protective layer through hole 162;

[0056] On the above basis, use photolithography to preset the pattern of the pad layer, then deposit Al metal by electron beam evaporation process, and then use the Lift-Off process to remove the metal layer outside the pad layer to form a pad layer 17. The pad layer 17 includes an N-type pad layer 171 and a P-type pad layer 172;

[0057] Thin the substrate 11, and then deposit a first-stage Bragg reflector 18 on the back of the substrate by electron beam evaporation process;

[0058] Deposit a second-stage Bragg reflector 19 at the bottom of the first-stage Bragg reflector 18, and then use photolithography and plasma chemical etching processes to form a central hollowed-out area, or use the Lift-OFF process to remove the second-stage Bragg reflector 19 in the central area to be hollowed out to complete the central hollowed-out setting and form a second-stage Bragg reflector through hole 191.

[0059] The flip-chip BLU light-emitting diode chip prepared by the preparation method of this embodiment has the same chip size specifications as the chip prepared in the control example. After being tested by a testing instrument, its half-intensity angle of emission is 160°, and the central luminous intensity is 52.3%. Specifically, it is shown in Table 1.

[0060] Example Two

[0061] Refer to Figure 3 , the difference between this embodiment and Embodiment 1 is that: the number of layers of the first Bragg reflection layer material group in this embodiment is 6 layers, the physical thickness of the SiO2 layer in the first Bragg reflection layer material group is 60 nm, the number of layers of the second Bragg reflection layer material group is 6 layers, and the bottom area of the through holes in the second Bragg reflection layer accounts for 10% of the substrate area; there are four through holes 191 in the second Bragg reflection layer, and their shapes are circular; specifically in implementation, the adjacent through holes 191 in the second Bragg reflection layer can also be interconnected.

[0062] The flip-chip BLU light-emitting diode chip prepared by the preparation method of this embodiment has the same chip size specifications as the chip prepared in the control example. After being tested by a testing instrument, its half-intensity angle of emission is 158°, and the central luminous intensity is 53.7%. Specifically, it is shown in Table 1.

[0063] Example Three

[0064] The difference between this embodiment and Embodiment 1 is that: the number of layers of the second Bragg reflection layer material group in this embodiment is 9 layers.

[0065] The flip-chip BLU light-emitting diode chip prepared by the preparation method of this embodiment has the same chip size specifications as the chip prepared in the control example. After being tested by a testing instrument, its half-intensity angle of emission is 170°, and the central luminous intensity is 46.2%. Specifically, it is shown in Table 1.

[0066] Example Four

[0067] The difference between this embodiment and Embodiment 1 is that: the physical thickness of the Ti3O5 layer in the first Bragg reflection layer material group in this embodiment is 33 nm, the physical thickness of the SiO2 layer in the second Bragg reflection layer material group is 100 nm, and the physical thickness of the Ti3O5 layer in the second Bragg reflection layer material group is 50 nm.

[0068] The flip-chip BLU light-emitting diode chip prepared by the preparation method of this embodiment has the same chip size specifications as the chip prepared in the control example. After being tested by a testing instrument, its half-intensity angle of emission is 162°, and the central luminous intensity is 49.3%. Specifically, it is shown in Table 1.

[0069] Example Five

[0070] The difference between this embodiment and Embodiment 1 is that: the number of layers of the first Bragg reflection layer material group in this embodiment is 10 layers, the number of layers of the second Bragg reflection layer material group is 10 layers, and the physical thickness of the SiO2 layer in the second Bragg reflection layer material group is 85 nm.

[0071] The flip-chip BLU light-emitting diode chip prepared by the preparation method of this embodiment has the same chip size specifications as the chip prepared in the control example. After being tested by a testing instrument, its half-intensity angle of emission is 175°, and the central luminous intensity is 47.1%. Specifically, it is shown in Table 1.

[0072] Embodiment Six

[0073] The difference between this embodiment and Embodiment 1 is that: the physical thickness of the SiO2 layer in the first Bragg reflection layer material group of this embodiment is 85 nm, the physical thickness of the Ti3O5 layer in the first Bragg reflection layer material group is 50 nm, the physical thickness of the Ti3O5 layer in the second Bragg reflection layer material group is 60 nm, and the bottom area of the through hole in the second Bragg reflection layer accounts for 70% of the substrate area.

[0074] The flip-chip BLU light-emitting diode chip prepared by the preparation method of this embodiment has the same chip size specifications as the chip prepared in the control example. After being tested by a testing instrument, its half-intensity angle of emission is 163°, and the central luminous intensity is 54.4%. Specifically, it is shown in Table 1.

[0075] Control Example

[0076] This control example uses a flip-chip BLU light-emitting diode chip of the prior art, which includes a substrate and a Bragg reflection layer deposited on the lower end face of the substrate, an epitaxial layer, a current blocking layer, a current spreading layer, a conductive metal layer, an insulating protective layer, and a pad layer deposited in sequence on the upper end face of the substrate. Among them, only one section of the Bragg reflection layer is provided, which is formed by a material group in which 12 groups of SiO2 layers and Ti3O5 layers are alternately stacked. The physical thickness of the SiO2 layer is 70 nm, and the physical thickness of the Ti3O5 layer is 40 nm. By testing the chip with a testing instrument, the half-intensity angle of emission of this chip is 151°, and the central luminous intensity is 43.6%. The specific results are shown in Table 1.

[0077] Table 1

[0078]

[0079] As can be seen from Table 1, the half-intensity angle and central luminous intensity of each embodiment of the present invention are better than those of the control example.

[0080] In summary, for the flip-chip BLU light-emitting diode chip prepared by the above embodiments, two Bragg reflection layers are provided on the back surface of the substrate 11. By controlling the thicknesses of the two Bragg reflection layers, the first Bragg reflection layer 18 can reflect the light with an angle between 45° and 90° with respect to the substrate 11, and the second Bragg reflection layer 19 can reflect the light with an angle between 0° and 45° with respect to the substrate 11, thereby enhancing the side light emission of the light-emitting diode chip and increasing the light-emitting angle of the light-emitting diode. Moreover, the second Bragg reflection layer 19 is hollowed out in the central region to form a second Bragg reflection layer through-hole 191, so that the light with an angle between 0° and 45° with respect to the substrate 11 in the central region is released, increasing the central light intensity and making the light emission of the center and the edge of the light-emitting diode chip uniform.

[0081] On the premise of no conflict, those skilled in the art can freely combine and superimpose the above additional technical features.

[0082] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. An upside-down BLU light-emitting diode chip, characterized in that, The chip includes a substrate, an epitaxial layer, a first Bragg reflection layer, and a second Bragg reflection layer. The epitaxial layer is disposed on the substrate. The first Bragg reflection layer is disposed on a side of the substrate facing away from the epitaxial layer and is used to reflect light with an angle between 45° and 90° with respect to the substrate. The second Bragg reflection layer is disposed on a side of the first Bragg reflection layer facing away from the substrate and is used to reflect light with an angle between 0° and 45° with respect to the substrate. A through hole of the second Bragg reflection layer penetrating through the first Bragg reflection layer is provided at the center of the second Bragg reflection layer.

2. The flip-chip BLU light-emitting diode chip according to claim 1, wherein The first Bragg reflection layer is formed by a material group in which 6 to 10 groups of SiO2 layers and Ti3O5 layers are alternately stacked. The physical thickness of the SiO2 layer is between 60 and 85 nm, and the physical thickness of the Ti3O5 layer is between 33 and 50 nm.

3. The flip-chip BLU light-emitting diode chip according to claim 1, wherein, The second Bragg reflection layer is formed by a material group in which 6 to 10 groups of SiO2 layers and Ti3O5 layers are alternately stacked. The physical thickness of the SiO2 layer is between 85 and 100 nm, and the physical thickness of the Ti3O5 layer is between 50 and 60 nm.

4. The flip-chip BLU light-emitting diode chip according to claim 1, wherein, The forward projection area of the first Bragg reflection layer on the substrate is the same as the area of the substrate.

5. A flip-chip BLU light-emitting diode chip according to claim 1, characterized in that, The boundary area of the forward projection of the second Bragg reflection layer on the substrate is the same as the area of the substrate. The bottom area of the through hole of the second Bragg reflection layer accounts for 10% to 70% of the area of the substrate.

6. The flip-chip BLU light-emitting diode chip according to claim 1, wherein At least one through hole of the second Bragg reflection layer is provided, and its shape is one or more of a circular shape, a square shape, and an irregular shape.

7. A flip-chip BLU light-emitting diode chip according to any one of claims 1 to 6, characterized in that, The epitaxial layer includes an N-type semiconductor layer, an active light-emitting layer, and a P-type semiconductor layer. The chip further includes a current blocking layer, a current spreading layer, a conductive metal layer, an insulating protection layer, and a pad layer that are sequentially stacked on the epitaxial layer. The conductive metal layer includes an N-type conductive metal layer and a P-type conductive metal layer. The N-type conductive metal layer is electrically connected to the N-type semiconductor layer, and the P-type conductive metal layer is electrically connected to the current spreading layer.

8. A flip-chip BLU light-emitting diode chip according to claim 7, characterized in that, The current spreading layer is an ITO layer.

9. The flip-chip BLU light-emitting diode chip according to claim 7, characterized in that The insulating protection layer is provided with an N-type insulating protection layer through hole and a P-type insulating protection layer through hole. The pad layer includes an N-type pad layer and a P-type pad layer. The N-type pad layer is electrically connected to the conductive metal layer through the N-type insulating protection layer through hole, and the P-type pad layer is electrically connected to the conductive metal layer through the P-type insulating protection layer through hole.

10. A method for preparing a flip-chip BLU light-emitting diode chip, characterized in that: The preparation method is used to prepare the flip-chip BLU light-emitting diode chip according to any one of claims 1 to 9. The preparation method includes: Providing a substrate, and preparing an epitaxial layer on the substrate. The epitaxial layer includes an N-type semiconductor layer, an active light-emitting layer, and a P-type semiconductor layer. Fabricating a current blocking layer on the P-type semiconductor layer. Fabricating a current spreading layer on the current blocking layer. Fabricating a conductive metal layer on the current spreading layer. The conductive metal layer includes an N-type conductive metal layer and a P-type conductive metal layer. Fabricating an insulating protection layer on the conductive metal layer, and etching the insulating protection layer to form an N-type insulating protection layer through hole and a P-type insulating protection layer through hole. A pad layer is fabricated on the insulating protection layer, and the pad layer includes an N-type pad layer and a P-type pad layer; The substrate is thinned, and a first Bragg reflection layer is fabricated on the back surface of the substrate; A second Bragg reflection layer is fabricated on the back surface of the first Bragg reflection layer, and a central region of the second Bragg reflection layer is hollowed out to form a through hole of the second Bragg reflection layer.

Images