LED chip and preparation method thereof

Abstract

The present invention provides an LED chip and a preparation method thereof, wherein etching is performed in a local area of ​​an epitaxial stack to a part of the N-type semiconductor layer, so that the epitaxial stack forms an N-electrode manufacturing area and a first table; a P-electrode manufacturing area is provided on the surface of the first table, and a plurality of holes are provided on the edge of the first table, each of the holes extending from the P-type semiconductor layer through the active area to a part of the N-type semiconductor layer; a light-transmitting insulating material is filled inside each of the holes, and each of the holes is filled at least to the same horizontal surface as the active area; and then, under the condition that the driving current of the LED chip is constant, the current density is effectively improved to achieve the effect of enhancing the internal quantum efficiency of the LED chip; at the same time, light can be emitted through the side walls of the holes, the light emission area is increased, and the external quantum efficiency of the LED chip is further improved; thereby, the light extraction rate of the LED chip is effectively improved.

Description

Technical Field

[0001] The invention relates to the field of light emitting diodes, and in particular to an LED chip and a preparation method thereof. Background Art

[0002] With the rapid development of LED technology and the gradual improvement of LED light efficiency, the application of LED is becoming more and more extensive, and people are paying more and more attention to the development prospects of LED in the lighting market. As the core component of LED lamps, the function of LED chips is to convert electrical energy into light energy. Specifically, they include epitaxial wafers and N-type electrodes and P-type electrodes respectively arranged on the epitaxial wafers. The epitaxial wafer includes a P-type semiconductor layer, an N-type semiconductor layer, and an active layer located between the N-type semiconductor layer and the P-type semiconductor layer. When current passes through the LED chip, the holes in the P-type semiconductor and the electrons in the N-type semiconductor will move to the active layer and recombine in the active layer, so that the LED chip emits light.

[0003] However, the existing LED chips have low light extraction efficiency due to the relatively low current density in the light emitting area at the edge of the chip. Therefore, how to improve the light extraction efficiency of semiconductor chips of light emitting diodes has become one of the most important topics in today's scientific research field.

[0004] In view of this, the inventor specially designed an LED chip and a method for preparing the same, which resulted in this case. Summary of the invention

[0005] The object of the present invention is to provide an LED chip and a preparation method thereof, so as to solve the problem in the prior art that the light emitting efficiency of the LED chip is low due to the relatively low current density in the light emitting area at the edge of the LED chip.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] An LED chip, comprising:

[0008] substrate;

[0009] An epitaxial stack is arranged on the surface of the substrate, the epitaxial stack comprises an N-type semiconductor layer, an active region and a P-type semiconductor layer stacked in sequence along a first direction, and a local region of the epitaxial stack is etched to a portion of the N-type semiconductor layer, so that the epitaxial stack forms an N-electrode manufacturing region and a first table; a P-electrode manufacturing region is arranged on the surface of the first table, and a plurality of holes are arranged at the edge of the first table, each of the holes extending from the P-type semiconductor layer through the active region to a portion of the N-type semiconductor layer; a light-transmitting insulating material is filled inside each of the holes, and each of the holes is filled at least to the same horizontal surface as the active region; the first direction is perpendicular to the substrate and points from the substrate to the epitaxial stack;

[0010] A current spreading layer, which is stacked on the surface of the first table and covers each of the holes;

[0011] An N-type electrode, which is stacked on the N-electrode manufacturing area;

[0012] A P-type electrode is stacked on a surface of the current spreading layer that is away from the epitaxial stack and is located directly above the P-electrode fabrication area.

[0013] Preferably, a current blocking layer is provided in the P-electrode fabrication area, and the current spreading layer surrounds the current blocking layer and covers each of the holes;

[0014] The P-type electrode is stacked on a surface of the current blocking layer that is away from the epitaxial stack.

[0015] Preferably, the holes are uniform in size, and their diameters are d; and the adjacent holes on the same horizontal line are arranged at equal intervals, and their intervals are L, then L≥4*d;

[0016] The sum of the surface areas of the holes is S, and the laying area of ​​the current spreading layer is A, then S ≤ A / 10.

[0017] Preferably, the surrounding height of the current spreading layer is higher than that of the current blocking layer, forming a groove and a second mesa; and the P-type electrode is stacked inside the groove and extends to the second mesa.

[0018] Preferably, the diameter of each of the holes ranges from 0.5 um to 3 um, including endpoint values.

[0019] Preferably, the LED chip further comprises a passivation protection layer, which covers the surface of the epitaxial stack and exposes the surfaces of the N-type electrode and the P-type electrode.

[0020] Preferably, the light-transmitting insulating material filled in each of the holes includes, but is not limited to, one or more of silicon dioxide and epoxy resin.

[0021] The present invention also provides a method for preparing an LED chip, the method comprising the following steps:

[0022] (a) providing a substrate;

[0023] (b), stacking an epitaxial stack on the surface of the substrate, the epitaxial stack comprising an N-type semiconductor layer, an active region, and a P-type semiconductor layer stacked in sequence along a first direction, wherein the first direction is perpendicular to the substrate and points from the substrate to the epitaxial stack;

[0024] (c) etching a local area of ​​the epitaxial stack to a portion of the N-type semiconductor layer, so that the epitaxial stack forms an N-electrode manufacturing area and a first table; the surface of the first table is provided with a P-electrode manufacturing area;

[0025] (d) etching the edge of the first mesa to form a plurality of holes, each of the holes extending from the P-type semiconductor layer through the active region to a portion of the N-type semiconductor layer;

[0026] (e) filling the interior of each of the holes with a light-transmitting insulating material, and each of the holes is filled at least to the same level as the active area;

[0027] (f), stacking a current spreading layer on the surface of the first mesa and covering each of the holes;

[0028] (g), stacking an N-type electrode in the N-electrode fabrication area;

[0029] (h) A P-type electrode is stacked on a surface of the current spreading layer that is away from the epitaxial stack and is located directly above the P-electrode fabrication region.

[0030] Preferably, the step (f) comprises:

[0031] Step 1, providing a current blocking layer in the P electrode manufacturing area;

[0032] Step 2, stacking the current spreading layer on the surface of the first mesa, and the current spreading layer surrounds the current blocking layer and covers each of the holes;

[0033] Then, the step (h) comprises: stacking the P-type electrode on the surface of the current spreading layer which is away from the epitaxial stack and is located directly above the P-electrode manufacturing area.

[0034] Preferably, the holes are uniform in size, and their diameters are d; and the adjacent holes on the same horizontal line are arranged at equal intervals, and their intervals are L, then L≥4*d;

[0035] The sum of the surface areas of the holes is S, and the laying area of ​​the current spreading layer is A, then S ≤ A / 10.

[0036] Preferably, the surrounding height of the current spreading layer is higher than that of the current blocking layer, forming a groove and a second mesa; and the P-type electrode is stacked inside the groove and extends to the second mesa.

[0037] Through the above technical solution, it can be known that the LED chip provided by the present invention is provided with an epitaxial stack arranged on the surface of the substrate, the epitaxial stack includes an N-type semiconductor layer, an active area and a P-type semiconductor layer stacked in sequence along a first direction, and a local area of ​​the epitaxial stack is etched to part of the N-type semiconductor layer, so that the epitaxial stack forms an N-electrode manufacturing area and a first table; a P-electrode manufacturing area is provided on the surface of the first table, and a plurality of holes are provided on the edge of the first table, each of which extends from the P-type semiconductor layer through the active area to part of the N-type semiconductor layer; a light-transmitting insulating material is filled inside each of the holes, and each of the holes is filled to at least the same horizontal surface as the active area; the first direction is perpendicular to the substrate and points from the substrate to the epitaxial stack; a current spreading layer is stacked on the surface of the first table and covers each of the holes; an N-type electrode is stacked on the N-electrode manufacturing area; a P-type electrode is stacked on the surface of the current spreading layer away from the epitaxial stack and is located directly above the P-electrode manufacturing area. A light-transmitting hole is set at the edge of the first table (i.e., the light-emitting area of ​​the LED chip), so that when the driving current of the LED chip is constant, the current density is effectively increased to enhance the internal quantum efficiency of the LED chip; at the same time, light can be emitted through the side wall of the hole, increasing the light-emitting area and further improving the external quantum efficiency of the LED chip; thereby effectively improving the light extraction rate of the LED chip.

[0038] Secondly, by providing a current blocking layer in the P-electrode manufacturing area, and the current spreading layer surrounds the current blocking layer and covers each of the holes, the light absorption problem of the electrode can be effectively solved.

[0039] Thirdly, by setting the size of each hole to be uniform, with a diameter of d; and the adjacent holes on the same horizontal line are arranged at equal intervals, with a spacing of L, then L≥4*d; the sum of the surface areas of each hole is S, and the laying area of ​​the current expansion layer is A, then S≤A / 10. Not only can the effective light output area of ​​the horizontal surface of the epitaxial stack be guaranteed, but the current density can also be effectively improved through the coordination of the holes, and the light output area can be increased through the side walls of the holes, further improving the light extraction efficiency.

[0040] Then, by setting the surrounding height of the current expansion layer higher than the current blocking layer, a groove and a second table are formed; the P-type electrode is stacked inside the groove and extends to the second table, which can effectively enhance the adhesion effect of the P-type electrode and prevent it from falling off.

[0041] Finally, the LED chip also includes a passivation protection layer, which covers the surface of the epitaxial stack and exposes the surface of the N-type electrode and the P-type electrode, effectively protecting the transparent conductive layer, the P-type electrode and the N-type electrode to prevent them from reacting with acids and alkalis in the external environment, thereby improving the reliability of the chip.

[0042] Through the above technical solutions, it can be known that the preparation method of the LED chip provided by the present invention has a simple and convenient process and realizes the setting of a light-transmitting hole on the edge of the first table (that is, the light-emitting area of ​​the LED chip), thereby effectively improving the current density under the condition of a certain driving current of the LED chip to achieve the effect of enhancing the internal quantum efficiency of the LED chip; at the same time, light can be emitted through the side walls of the hole, thereby increasing the light-emitting area and further improving the external quantum efficiency of the LED chip; thereby effectively improving the light extraction rate of the LED chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] 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 embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0044] Figure 1 A schematic diagram of the structure of an LED chip provided by an embodiment of the present invention;

[0045] Figure 2.1 to Figure 2.7 A schematic structural diagram corresponding to the steps of the method for preparing an LED chip provided in an embodiment of the present invention;

[0046] Explanation of symbols in the figure: 1. Substrate, 2. Epitaxial stack, 2-1. N-type semiconductor layer, 2-2. Active area, 2-3. P-type semiconductor layer, 3. N-electrode manufacturing area, 4. First table, 5. P-electrode manufacturing area, 6. Hole, 7. Current blocking layer, 8. Current spreading layer, 9. N-type electrode, 10. P-type electrode, 11. Passivation protection layer, 12. Groove, 13. Second table. DETAILED DESCRIPTION

[0047] To make the content of the present invention clearer, the content of the present invention is further described below in conjunction with the accompanying drawings. The present invention is not limited to this specific embodiment. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0048] like Figure 1 As shown, an LED chip comprises:

[0049] Substrate 1;

[0050] An epitaxial stack 2 is arranged on the surface of a substrate 1, the epitaxial stack 2 includes an N-type semiconductor layer 2-1, an active region 2-2 and a P-type semiconductor layer 2-3 stacked in sequence along a first direction, and a local area of ​​the epitaxial stack 2 is etched to a part of the N-type semiconductor layer 2-1, so that the epitaxial stack 2 forms an N-electrode manufacturing region 3 and a first table 4; a P-electrode manufacturing region 5 is arranged on the surface of the first table 4, and a plurality of holes 6 are arranged at the edge of the first table 4, each hole 6 extends from the P-type semiconductor layer 2-3 through the active region 2-2 to a part of the N-type semiconductor layer 2-1; a light-transmitting insulating material is filled inside each hole 6, and each hole 6 is filled at least to the same horizontal surface as the active region 2-2; the first direction is perpendicular to the substrate 1, and points from the substrate 1 to the epitaxial stack 2;

[0051] A current spreading layer 8, which is stacked on the surface of the first mesa 4 and covers each hole 6;

[0052] N-type electrode 9, which is stacked on the N-electrode manufacturing area 3;

[0053] The P-type electrode 10 is stacked on the surface of the current spreading layer 8 which is away from the epitaxial stack 2 and is located directly above the P-electrode manufacturing region 5 .

[0054] A current blocking layer 7 is provided in the P electrode fabrication area 5, and a current spreading layer 8 surrounds the current blocking layer 7 and covers each hole 6;

[0055] The P-type electrode 10 is stacked on a surface of the current blocking layer 7 that is away from the epitaxial stack 2 .

[0056] The size of each hole 6 is uniform, and its diameter is d; and the adjacent holes 6 on the same horizontal line are arranged at equal intervals, and the interval is L, then L≥4*d;

[0057] The sum of the surface areas of the holes 6 is S, and the laying area of ​​the current spreading layer 8 is A, then S≤A / 10.

[0058] The surrounding height of the current spreading layer 8 is higher than that of the current blocking layer 7 , forming a groove 12 and a second mesa 13 ; the P-type electrode 10 is stacked inside the groove 12 and extends to the second mesa 13 .

[0059] The diameter of each hole 6 ranges from 0.5 um to 3 um, including the end values.

[0060] The LED chip further includes a passivation protection layer 11 , which covers the surface of the epitaxial stack 2 and exposes the surfaces of the N-type electrode 9 and the P-type electrode 10 .

[0061] The light-transmitting insulating material filled in each hole 6 includes, but is not limited to, one or more of silicon dioxide and epoxy resin.

[0062] like Figure 2.1 to Figure 2.7 As shown, this embodiment also provides a method for preparing an LED chip, the preparation method comprising the following steps:

[0063] (a) providing a substrate 1;

[0064] (b) stacking an epitaxial stack 2 on the surface of the substrate 1, wherein the epitaxial stack 2 includes an N-type semiconductor layer 2-1, an active region 2-2, and a P-type semiconductor layer 2-3 stacked in sequence along a first direction, wherein the first direction is perpendicular to the substrate 1 and points from the substrate 1 to the epitaxial stack 2;

[0065] (c) etching a local area of ​​the epitaxial stack 2 to a portion of the N-type semiconductor layer 2-1, so that the epitaxial stack 2 forms an N-electrode manufacturing area 3 and a first mesa 4; a P-electrode manufacturing area 5 is provided on the surface of the first mesa 4;

[0066] (d) etching the edge of the first mesa 4 to form a plurality of holes 6, each hole 6 extending from the P-type semiconductor layer 2-3 through the active region 2-2 to a portion of the N-type semiconductor layer 2-1;

[0067] (e) filling each hole 6 with a light-transmitting insulating material, and each hole 6 is filled at least to the same level as the active area 2-2;

[0068] (f) stacking a current spreading layer 8 on the surface of the first mesa 4 and covering each hole 6;

[0069] (g), stacking an N-type electrode 9 in the N-electrode fabrication region 3;

[0070] (h) A P-type electrode 10 is stacked on the surface of the current spreading layer 8 that is away from the epitaxial stack 2 and is located directly above the P-electrode formation region 5 .

[0071] Wherein, step (f) comprises:

[0072] Step 1: a current blocking layer 7 is provided in the P electrode manufacturing area 5;

[0073] Step 2, stacking a current spreading layer 8 on the surface of the first mesa 4, and the current spreading layer 8 surrounds the current blocking layer 7 and covers each hole 6;

[0074] Then, step (h) includes: stacking a P-type electrode 10 on a surface of the current spreading layer 8 that is away from the epitaxial stack 2 and is located directly above the P-electrode manufacturing region 5 .

[0075] The size of each hole 6 is uniform, and its diameter is d; and the adjacent holes 6 on the same horizontal line are arranged at equal intervals, and the interval is L, then L≥4*d;

[0076] The sum of the surface areas of the holes 6 is S, and the laying area of ​​the current spreading layer 8 is A, then S≤A / 10.

[0077] The surrounding height of the current spreading layer 8 is higher than that of the current blocking layer 7 , forming a groove 12 and a second mesa 13 ; the P-type electrode 10 is stacked inside the groove 12 and extends to the second mesa 13 .

[0078] Through the above technical solution, it can be known that the LED chip provided by the present invention is provided with an epitaxial stack 2 arranged on the surface of the substrate 1, the epitaxial stack 2 includes an N-type semiconductor layer 2-1, an active region 2-2 and a P-type semiconductor layer 2-3 stacked in sequence along a first direction, and a local area of ​​the epitaxial stack 2 is etched to a part of the N type semiconductor layer 2-1, so that the epitaxial stack 2 forms an N-electrode manufacturing area 3 and a first table 4; a P-electrode manufacturing area 5 is provided on the surface of the first table 4, and a plurality of holes 6 are provided at the edge of the first table 4, each hole 6 extends from the P-type semiconductor layer 2-3 through the active area 2-2 to a portion of the N-type semiconductor layer 2-1; the interior of each hole 6 is filled with a light-transmitting insulating material, and each hole 6 is filled to at least the same horizontal surface as the active area 2-2; the first direction is perpendicular to the substrate 1 and points from the substrate 1 to the epitaxial stack 2; a current spreading layer 8, which is stacked on the surface of the first table 4 and covers each hole 6; an N-type electrode 9, which is stacked on the N-electrode manufacturing area 3; a P-type electrode 10, which is stacked on the side surface of the current spreading layer 8 away from the epitaxial stack 2 and is located directly above the P-electrode manufacturing area 5. A light-transmitting hole 6 is provided at the edge of the first table 4 (i.e., the light-emitting area of ​​the LED chip), so that when the driving current of the LED chip is constant, the current density is effectively increased to enhance the internal quantum efficiency of the LED chip; at the same time, light can be emitted through the side wall of the hole 6, the light-emitting area is increased, and the external quantum efficiency of the LED chip is further improved; thereby effectively improving the light extraction rate of the LED chip.

[0079] Secondly, by providing a current blocking layer 7 in the P-electrode manufacturing area 5 and the current spreading layer 8 surrounding the current blocking layer 7 and covering each hole 6, the light absorption problem of the electrode can be effectively solved.

[0080] Thirdly, by setting the size of each hole 6 to be uniform, with a diameter of d; and the adjacent holes 6 on the same horizontal line are arranged at equal intervals, with a spacing of L, then L≥4*d; the sum of the surface areas of each hole 6 is S, and the laying area of ​​the current expansion layer 8 is A, then S≤A / 10. Not only is the effective light-emitting area of ​​the horizontal surface of the epitaxial stack 2 guaranteed, but the current density is effectively improved through the coordination of the holes 6, and the light-emitting area can be increased through the side walls of the holes 6, further improving the light extraction efficiency.

[0081] Then, by setting the surrounding height of the current expansion layer 8 higher than the current blocking layer 7, a groove 12 and a second table 13 are formed; the P-type electrode 10 is stacked inside the groove 12 and extends to the second table 13, which can effectively enhance the adhesion effect of the P-type electrode 10 and prevent it from falling off.

[0082] Finally, the LED chip also includes a passivation protection layer 11, which covers the surface of the epitaxial stack 2 and exposes the surface of the N-type electrode 9 and the P-type electrode 10, forming an effective protection for the transparent conductive layer, the P-type electrode 10 and the N-type electrode 9 to prevent them from reacting with acids and alkalis in the external environment, thereby improving the reliability of the chip.

[0083] It can be seen from the above technical solutions that the preparation method of the LED chip provided by the present invention has a simple and convenient process and realizes the setting of a light-transmitting hole 6 at the edge of the first table 4 (that is, the light-emitting area of ​​the LED chip), thereby effectively improving the current density under the condition of a certain driving current of the LED chip to achieve the effect of enhancing the internal quantum efficiency of the LED chip; at the same time, light can be emitted through the side wall of the hole 6, thereby increasing the light emitting area and further improving the external quantum efficiency of the LED chip; thereby effectively improving the light extraction rate of the LED chip.

[0084] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other. The above description of the disclosed embodiments enables professionals and technicians in this field to implement or use the present application. Various modifications to these embodiments will be obvious to professionals and technicians in this field, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will comply with the widest range consistent with the principles and novel features disclosed herein.

Claims

1. An LED chip, characterized in that: include: substrate; An epitaxial stack is arranged on the surface of the substrate, the epitaxial stack comprises an N-type semiconductor layer, an active region and a P-type semiconductor layer stacked in sequence along a first direction, and a local region of the epitaxial stack is etched to a portion of the N-type semiconductor layer, so that the epitaxial stack forms an N-electrode manufacturing region and a first table; a P-electrode manufacturing region is arranged on the surface of the first table, and a plurality of holes are arranged at the edge of the first table, each of the holes extending from the P-type semiconductor layer through the active region to a portion of the N-type semiconductor layer; a light-transmitting insulating material is filled inside each of the holes, and each of the holes is filled at least to the same horizontal surface as the active region; the first direction is perpendicular to the substrate and points from the substrate to the epitaxial stack; A current spreading layer, which is stacked on the surface of the first table and covers each of the holes; An N-type electrode, which is stacked on the N-electrode manufacturing area; A P-type electrode, which is stacked on a surface of the current spreading layer facing away from the epitaxial stack and is located directly above the P-electrode fabrication area; The holes are uniform in size, and their diameter is d; and the adjacent holes on the same horizontal line are arranged at equal intervals, and their interval is L, then L≥4*d; The sum of the surface areas of the holes is S, and the laying area of ​​the current spreading layer is A, then S≤A / 10; Wherein, the LED chip further includes a passivation protection layer, which covers the surface of the epitaxial stack and exposes the surfaces of the N-type electrode and the P-type electrode.

2. The LED chip according to claim 1, characterized in that: A current blocking layer is provided in the P-electrode manufacturing area, and the current spreading layer surrounds the current blocking layer and covers each of the holes; The P-type electrode is stacked on a surface of the current blocking layer that is away from the epitaxial stack.

3. The LED chip according to claim 1 or 2, characterized in that: The surrounding height of the current spreading layer is higher than that of the current blocking layer, forming a groove and a second mesa; the P-type electrode is stacked inside the groove and extends to the second mesa.

4. The LED chip according to claim 1, characterized in that: The light-transmitting insulating material filled in each of the holes includes one or more of silicon dioxide and epoxy resin.

5. A method for preparing an LED chip, characterized in that: The preparation method comprises the following steps: (a) providing a substrate; (b) stacking an epitaxial stack on the surface of the substrate, wherein the epitaxial stack comprises an N-type semiconductor layer, an active region, and a P-type semiconductor layer stacked in sequence along a first direction, wherein the first direction is perpendicular to the substrate and points from the substrate to the epitaxial stack; (c) etching a local area of ​​the epitaxial stack to a portion of the N-type semiconductor layer, so that the epitaxial stack forms an N-electrode manufacturing area and a first table; the surface of the first table is provided with a P-electrode manufacturing area; (d) etching the edge of the first mesa to form a plurality of holes, each of the holes extending from the P-type semiconductor layer through the active region to a portion of the N-type semiconductor layer; (e) filling the interior of each of the holes with a light-transmitting insulating material, and each of the holes is filled at least to the same level as the active area; (f) stacking a current spreading layer on the surface of the first mesa and covering each of the holes; (g), stacking an N-type electrode in the N-electrode fabrication area; (h) stacking a P-type electrode on a surface of the current spreading layer facing away from the epitaxial stack and directly above the P-electrode fabrication region; The holes are uniform in size, and their diameter is d; and the adjacent holes on the same horizontal line are arranged at equal intervals, and their interval is L, then L≥4*d; The sum of the surface areas of the holes is S, and the laying area of ​​the current spreading layer is A, then S≤A / 10; Wherein, the LED chip further includes a passivation protection layer, which covers the surface of the epitaxial stack and exposes the surfaces of the N-type electrode and the P-type electrode.

6. The method for preparing an LED chip according to claim 5, characterized in that: in, The step (f) comprises: Step 1, providing a current blocking layer in the P electrode manufacturing area; Step 2, stacking the current spreading layer on the surface of the first mesa, and the current spreading layer surrounds the current blocking layer and covers each of the holes; Then, the step (h) comprises: stacking the P-type electrode on a surface of the current spreading layer that is away from the epitaxial stack and is located directly above the P-electrode fabrication region.

7. The method for preparing an LED chip according to claim 6, characterized in that: The surrounding height of the current spreading layer is higher than that of the current blocking layer, forming a groove and a second mesa; the P-type electrode is stacked inside the groove and extends to the second mesa.

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