Micro light-emitting diode and display device thereof

Abstract

The invention discloses a micro light-emitting diode and a display device thereof, the micro light-emitting diode is provided with a semiconductor layer sequence, the semiconductor layer sequence comprises a back side and a front side, a first type semiconductor layer and a second type semiconductor layer are sequentially arranged from the front side, an active layer is located between the first type semiconductor layer and the second type semiconductor layer, and the back side of the semiconductor layer sequence is provided with a groove. The groove penetrates through the second type semiconductor layer and the active layer and exposes the first type semiconductor layer, and the back side of the semiconductor layer sequence comprises a first table top in the groove, a second table top on the second type semiconductor layer and a groove side wall located between the first table top and the second table top. A first metal electrode electrically connected with the first type of semiconductor layer and a second metal electrode electrically connected with the second type of semiconductor layer are arranged on the back side of the semiconductor layer sequence, the first metal electrode and the second metal electrode are used for being bonded with an external power supply, and the chromium content of the first metal electrode is larger than that of the second metal electrode; the problem that chromium of the second metal electrode is easy to migrate is solved.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor manufacturing, and in particular relates to a micro light emitting diode and a display device. Background Art

[0002] Micro LED (mLED) is the next generation display light source that is currently being hotly researched. It has the advantages of low power consumption, high brightness, ultra-high resolution and color saturation, fast response speed, low energy consumption, and long life. In addition, its power consumption is about 10% of LCD and 50% of OLED. Compared with OLED, which is also self-luminous, the brightness is many times higher, and the resolution can reach a high pixel density. These obvious advantages of mLED make it likely to replace the current OLED and LCD and become the light source for the next generation of displays. mLED cannot be mass-produced at present because there are still many technical difficulties to be overcome. One of the important technical difficulties is how to improve the yield of micron-level micron core particles. Summary of the invention

[0003] In order to improve the yield of micron-scale core particles, the present invention provides a micro light-emitting diode, which has a semiconductor layer sequence, wherein the semiconductor layer sequence includes a back side and a front side, and includes a first type semiconductor layer and a second type semiconductor layer in sequence from the front side, with an active layer located therebetween. The back side of the semiconductor layer sequence has a groove, and the groove penetrates the second type semiconductor layer and the active layer to expose the first type semiconductor layer. The back side of the semiconductor layer sequence includes a first table in the groove, a second table on the second type semiconductor layer and a groove sidewall located therebetween. The back side of the semiconductor layer sequence is provided with a first metal electrode electrically connected to the first type semiconductor layer and a second metal electrode electrically connected to the second type semiconductor layer. The chromium content of the first metal electrode is greater than that of the second metal electrode. The length of the second metal electrode is 2μm to 30μm. By reducing or eliminating the chromium content of the second metal electrode, leakage of chromium metal can be avoided under the micron-scale electrode structure.

[0004] The present invention also provides a display device, comprising a plurality of micro-LEDs and a substrate, wherein the micro-LEDs are arranged on the substrate, characterized in that the micro-LEDs are sealed by epoxy resin, the micro-LEDs have a semiconductor layer sequence, the semiconductor layer sequence comprises a back side and a front side, and comprises a first type semiconductor layer and a second type semiconductor layer in sequence from the front side, an active layer is located between the two, the back side of the semiconductor layer sequence has a groove, the groove penetrates the second type semiconductor layer and the active layer, and exposes the first type semiconductor layer, the back side of the semiconductor layer sequence comprises a first table in the groove, a second table on the second type semiconductor layer and a groove sidewall located between the two, the back side of the semiconductor layer sequence is provided with a first metal electrode electrically connected to the first type semiconductor layer and a second metal electrode electrically connected to the second type semiconductor layer, characterized in that the chromium content of the first metal electrode is greater than that of the second metal electrode, and the length of the second metal electrode is 2μm to 30μm. Under the epoxy resin sealing condition, due to the large stress of the epoxy resin, the chromium component may leak, and by eliminating the chromium component of the second metal electrode, the risk of chromium leakage is reduced.

[0005] Other beneficial effects of the present invention will be gradually described through embodiments and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, some of the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0007] Figure 1 and Figure 2 They are cross-sectional schematic diagrams of a micro light emitting diode chip and a micro display device in the prior art respectively; Figure 3 and Figure 4 They are respectively a cross-sectional schematic diagram and a top schematic diagram of a first embodiment of the present invention; Figure 5 is a cross-sectional schematic diagram of a second embodiment of the present invention; Figure 6 Schematic cross-sectional view of the third and fourth embodiments of the present invention.

[0008] Symbols in the figure: 110, semiconductor layer sequence; 111, first type semiconductor layer; 112, second type semiconductor layer; 113, active layer; 210, first metal electrode; 211, first layer of first metal electrode; 220, second metal electrode; 221, first layer of second metal electrode; 222, second layer of second metal electrode; 300, passivation layer; 400, transparent conductive layer; 500, substrate; C1, micro-light-emitting diode; G1, groove; K1, first opening; K2, second opening; K12, first electrode hole; K22, second electrode hole; M1, first table; M2, second table; P1, silicone; P2, epoxy resin; S1, groove sidewall; L1, length of second metal electrode; L2, length of first layer of second metal electrode. DETAILED DESCRIPTION

[0009] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; the technical features designed in different implementation modes of the present invention described below can be combined with each other as long as they do not conflict with each other; 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.

[0010] In some embodiments, a micro-light-emitting diode is provided, which has a semiconductor layer sequence, wherein the semiconductor layer sequence includes a back side and a front side, and includes a first type semiconductor layer and a second type semiconductor layer in sequence from the front side, with an active layer located therebetween. The back side of the semiconductor layer sequence has a groove, and the groove penetrates the second type semiconductor layer and the active layer to expose the first type semiconductor layer. The back side of the semiconductor layer sequence includes a first table in the groove, a second table on the second type semiconductor layer, and a groove sidewall located therebetween. The back side of the semiconductor layer sequence is provided with a first metal electrode electrically connected to the first type semiconductor layer and a second metal electrode electrically connected to the second type semiconductor layer. Metal migration depends on high temperature and high humidity conditions. Under the catalysis of water vapor, ions carrying chromium migrate. A high electric field is provided on the second metal electrode. The chromium of the second metal electrode is more easily migrated than the chromium of the first metal electrode. The chromium content of the first metal electrode is set to be greater than that of the second metal electrode. The length of the second metal electrode is 2μm to 30μm. As the size of the second metal electrode continues to shrink, the metal coating decreases, and chromium leakage is prone to occur. Reducing the chromium of the second metal electrode helps reduce the risk of chromium leakage.

[0011] In some embodiments, the first metal electrode contacts the first type semiconductor layer through chromium, and the second metal electrode does not contain chromium, that is, is not connected to the second type semiconductor layer through chromium, or is not connected to the transparent conductive layer through chromium.

[0012] In some embodiments, the length of the second metal electrode is 5 μm to 30 μm. Increasing the minimum length of the second metal electrode compensates for the loss of adhesion due to the reduction of chromium content and reduces the risk of the second metal electrode falling off.

[0013] In some embodiments, the first metal electrode is completely disposed in the groove, and the groove is a non-closed step; three of the four sides of the groove are exposed, and the other side is the groove sidewall, or two of the four sides of the groove are exposed, and the other two sides are the groove sidewalls.

[0014] In some embodiments, the first metal electrode covers from the inside of the groove to the second terrace, and the height of the sidewall of the groove is 0.5 μm to 2 μm.

[0015] In some embodiments, the projected area of ​​the back surface of the first metal electrode and / or the second metal electrode is 25 μm 2 Up to 100 μm 2 The projected area of ​​the back surface of the first layer of the second metal electrode is 30 μm 2 Up to 100 μm 2 The area of ​​the first layer of the second metal electrode is increased as much as possible to increase the electrode adhesion.

[0016] In some embodiments, a distance between the first metal electrode and the second metal electrode is 4 μm to 10 μm.

[0017] In some embodiments, the second mesa is located on a side of the second type semiconductor layer away from the active layer, a passivation layer is disposed on the second mesa, the passivation layer covers at least from the second mesa to the first mesa, the passivation layer has a first opening on the first mesa, the passivation layer has a second opening on the second mesa, the first metal electrode is electrically connected to the first type semiconductor layer through the first opening, the second metal electrode is electrically connected to the second type semiconductor layer through the second opening, and a transparent conductive layer is disposed between the second metal electrode and the second type semiconductor layer.

[0018] In some embodiments, the maximum aperture of the second opening is 2 μm to 20 μm, ensuring that the second metal electrode and the second type semiconductor layer have sufficient connection strength to compensate for the adhesion loss due to the reduction or elimination of chromium content.

[0019] In some embodiments, the passivation layer is disposed between the second metal electrode and the second type semiconductor layer, and the second metal electrode is connected from the second opening to the upper surface of the back side of the passivation layer. The thickness of the passivation layer is 0.5 μm to 3 μm.

[0020] In some embodiments, the second metal electrode is not disposed between the passivation layer and the second type semiconductor layer, or the second metal electrode is not disposed between the passivation layer and the transparent conductive layer.

[0021] In some embodiments, the back surface of the first metal electrode corresponding to the first opening has a first electrode hole, and the back surface of the second metal electrode corresponding to the second opening has a second electrode hole, wherein the opening area of ​​the first electrode hole is smaller than the opening area of ​​the second electrode hole, thereby increasing the opening area of ​​the second electrode hole. Since the first metal electrode extends from the groove to the second table, the effective area for contact is limited. This embodiment increases the contact area between the second metal electrode and the second type semiconductor layer or transparent conductive layer on its positive side, and at the same time increases the bonding area when the first metal electrode is bonded to the outside, thereby reducing the risk of bonding detachment.

[0022] In some embodiments, the opening area of ​​the first electrode hole accounts for 10% to 40% of the back surface area of ​​the first metal electrode, and the opening area of ​​the second electrode hole accounts for 15% to 50% of the back surface area of ​​the second metal electrode, thereby increasing the bonding area when the first metal electrode is bonded to the outside and reducing the risk of bonding detachment.

[0023] In some embodiments, the first metal electrode and the second metal electrode have n metal stack layers, n is an integer greater than or equal to 2, the first layer of the first metal electrode is close to the first table side and contains chromium, and is used to connect to the first type semiconductor layer; the first layer of the second metal electrode is close to the second table side and does not contain chromium, and is in contact with a transparent conductive layer, and the transparent conductive layer is electrically connected to the second type semiconductor layer.

[0024] In some embodiments, the length of the first layer of the second metal electrode is greater than 2 μm to 25 μm. The first layer of the second metal electrode serves as a contact layer with the second type semiconductor layer or the transparent conductive layer. The material includes, for example, nickel, aluminum, titanium, platinum, gold or any alloy of the above. The adhesion to the second type semiconductor layer and the transparent conductive layer is lower than that of chromium. Therefore, increasing the length is beneficial to improving the overall adhesion of the second metal electrode.

[0025] In some embodiments, the first layer of the second metal electrode includes titanium, which has relatively high adhesion and is not easily migrated under an electric field.

[0026] In some embodiments, the first metal electrode is an N-type electrode, and the second metal electrode is a P-type electrode.

[0027] In some embodiments, the micro-LED is sealed by epoxy resin, and the micro-LED has a semiconductor layer sequence, the semiconductor layer sequence includes a back side and a front side, and includes a first type semiconductor layer and a second type semiconductor layer in sequence from the front side, and an active layer is located between the two. The back side of the semiconductor layer sequence has a groove, and the groove runs through the second type semiconductor layer and the active layer to expose the first type semiconductor layer. The back side of the semiconductor layer sequence includes a first table in the groove, a second table on the second type semiconductor layer, and a groove sidewall located between the two. The back side of the semiconductor layer sequence is provided with a first metal electrode electrically connected to the first type semiconductor layer and a second metal electrode electrically connected to the second type semiconductor layer. The chromium content of the first metal electrode is greater than that of the second metal electrode, and the length of the second metal electrode is 2μm to 30μm. Since the stress of the epoxy resin is large, chromium leakage in the second metal electrode is likely to occur, so reducing or eliminating the chromium content of the first electrode is conducive to improving the product yield.

[0028] In some embodiments, the first metal electrode contacts the first type semiconductor layer through chromium, and the second metal electrode does not contain chromium.

[0029] See also Figure 1 and Figure 2 In the prior art, silica gel P1 is usually used as a packaging material. Silica gel P1 has a technical effect of low stress. The micro light emitting diode includes: a semiconductor layer sequence 110, the semiconductor layer sequence 110 has a first type semiconductor layer 111, a first type semiconductor layer 112, an active layer 113 is located therebetween, a first metal electrode 210 is electrically connected to the first type semiconductor layer 111, and a second metal electrode 220 is electrically connected to the first type semiconductor layer 112.

[0030] On the one hand, in order to replace the existing technology, when the client uses epoxy resin as the packaging material, the stress of the packaging glue increases, causing the chromium in the first layer 221 of the second metal electrode 220 to leak more easily. On the other hand, since the size of the micro-LED chip is micron-level and significantly smaller than the traditional LED chip, the size of the second metal electrode 220 also needs to be continuously reduced. The first layer 221 of the second metal electrode 220 is usually used as a contact layer to provide adhesion. The second layer or above of the second metal electrode 220 is used as a protective layer to cover the first layer 221 of the second metal electrode 220 to prevent the first layer 221 of the second metal electrode 220 from leaking. As the size of the second metal electrode 220 continues to shrink, the coating effect of the second layer 222 of the second metal electrode 220 is reduced, and the first layer 221 of the second metal electrode 220 is more likely to leak.

[0031] See also Figure 3 and Figure 4In a first embodiment of the present invention, a micro-LED is provided. The micro-LED is rectangular, the short side length of the micro-LED is 10 μm to 30 μm, and the long side length of the micro-LED is 15 μm to 40 μm. For example, the size of the micro-LED is 10 μm*25 μm. The micro-LED has a semiconductor layer sequence 110. The semiconductor layer sequence 110 includes a back side and a front side. Starting from the front side, the semiconductor layer 111 and the first type semiconductor layer 112 are sequentially included. An active layer 113 is located between the two. The first type semiconductor layer 111 of the micro-LED is at least partially removed from the front side, for example, by substrate stripping and epitaxial thinning processes. The back side of the semiconductor layer sequence 110 has a groove G1, which is used as a Mesa groove to provide a window for making an electrode. The groove G1 penetrates the first type semiconductor layer 112 and the active layer 113 to expose the first type semiconductor layer 111. The back side of the semiconductor layer sequence 110 includes a first table M1 in the groove G1, a second table M2 on the first type semiconductor layer 112, and a side wall S1 of the groove G1 located therebetween. The back side of the semiconductor layer sequence 110 is provided with a first metal electrode 210 electrically connected to the first type semiconductor layer 111 and a second metal electrode 220 electrically connected to the first type semiconductor layer 112. The chromium content of the first metal electrode 210 is greater than that of the second metal electrode 220. The first metal electrode 210 and the second metal electrode 220 are used for bonding with an external power source, and the length L1 of the second metal electrode 220 is 2 μm to 30 μm. In this embodiment, the semiconductor layer sequence 110 is gallium nitride-based, the first type semiconductor layer 111 is an N-type semiconductor layer, the first type semiconductor layer 112 is a P-type semiconductor layer, the first metal electrode 210 is an N-type electrode, and the second metal electrode 220 is a P-type electrode.

[0032] In some implementations of this embodiment, the length L1 of the second metal electrode 220 is 5 μm to 30 μm.

[0033] In some implementations of this embodiment, the projection area of ​​the back surface of the first metal electrode 210 and / or the second metal electrode 220 is 25 μm 2 Up to 100 μm 2 .

[0034] In some implementations of this embodiment, the second metal electrode 220 is not plated with chromium metal, for example, the chromium content of the second metal electrode 220 is zero. The distance between the first metal electrode 210 and the second metal electrode 220 is 4 μm to 10 μm.

[0035] In this embodiment, the first metal electrode 210 extends from the groove G1 to the second mesa M2 on the first type semiconductor layer 112. Two of the four sides of the groove G1 are exposed, and the other two sides are the sidewalls S1 of the groove G1. The height of the sidewalls S1 of the groove G1 is 0.5 μm to 2 μm.

[0036] In some implementations of this embodiment, the second mesa M2 is rectangular, and the single side size of the second mesa M2 is 5 μm to 35 μm. Experiments have shown that the rectangle helps to improve the current density of the product at a small size, thereby improving the brightness of the product.

[0037] In some implementations of this embodiment, the first metal electrode 210 is completely disposed in the groove G1 , and the groove G1 is a non-closed step; three of the four side surfaces of the groove G1 are exposed, and the other side surface is a side wall S1 of the groove G1 .

[0038] In this embodiment, the second mesa M2 is located on a side of the first type semiconductor layer 112 away from the active layer 113, a passivation layer 300 is provided on the second mesa M2, the passivation layer 300 covers at least from the second mesa M2 to the first mesa M1, the passivation layer 300 has a first opening K1 on the first mesa M1, the passivation layer 300 has a second opening K2 on the second mesa M2, the first metal electrode 210 is electrically connected to the first type semiconductor layer 111 through the first opening K1, the second metal electrode 220 is electrically connected to the first type semiconductor layer 112 through the second opening K2, and the maximum aperture of the second opening K2 is 2 μm to 20 μm. A transparent conductive layer 400 is provided between the second metal electrode 220 and the first type semiconductor layer 112.

[0039] The material of the passivation layer 300 includes silicon dioxide, silicon nitride, aluminum oxide or titanium oxide, which mainly serves the purpose of electrical insulation. In some cases, a DBR structure can also be used to increase the reflected light. The passivation layer 300 is arranged between the second metal electrode 220 and the first type semiconductor layer 112. The second metal electrode 220 is connected from the second opening K2 to the upper surface of the back side of the passivation layer 300. The thickness of the passivation layer 300 is 0.5μm to 3μm. In this embodiment, the second metal electrode 220 is not arranged between the passivation layer 300 and the first type semiconductor layer 112, or the second metal electrode 220 is not arranged between the passivation layer 300 and the transparent conductive layer 400.

[0040] In this embodiment, the back surface of the first metal electrode 210 corresponding to the first opening K1 has a first electrode hole K12, and the back surface of the second metal electrode 220 corresponding to the second opening K2 has a second electrode hole, wherein the opening area of ​​the first electrode hole K12 is smaller than the opening area of ​​the second electrode hole. The opening area of ​​the first electrode hole K12 accounts for 10% to 40% of the back surface area of ​​the first metal electrode 210, and the opening area of ​​the second electrode hole accounts for 15% to 50% of the back surface area of ​​the second metal electrode 220. It should be noted that, due to the different shapes of the groove G1, the first electrode hole K12 is caused by the first opening K2 and the groove G1, and there may be no completely closed boundary, and sufficient bonding area is required, which does not affect the implementation of this embodiment.

[0041] See also Figure 5 In the second embodiment of the present invention, the difference from the first embodiment is that the first metal electrode 210 and the second metal electrode 220 have n metal stacks, n is an integer greater than or equal to 2, the first layer 211 of the first metal electrode 210 is close to the first mesa M1 side and contains chromium, and is used to connect with the first type semiconductor layer 111; the first layer 221 of the second metal electrode 220 is close to the second mesa M2 side and does not contain chromium, and is in contact with a transparent conductive layer 400, and the transparent conductive layer 400 is electrically connected to the first type semiconductor layer 112. In this embodiment, the first type semiconductor layer 111 is an N-type semiconductor layer, the first type semiconductor layer 112 is a P-type semiconductor layer, the first metal electrode 210 is an N-type electrode, and the second metal electrode 220 is a P-type electrode.

[0042] The length L2 of the first layer 221 of the second metal electrode 220 is greater than 2 μm to 25 μm. The first layer 221 of the second metal electrode 220 serves as a contact layer with the first type semiconductor layer 112 or the transparent conductive layer 400. The material includes, for example, nickel, aluminum, titanium, platinum, gold or any alloy of the above. The adhesion to the first type semiconductor layer 112 and the transparent conductive layer 400 is lower than that of chromium. Therefore, increasing the length L2 is beneficial to improving the overall adhesion of the second metal electrode 220. In this embodiment, titanium is preferably used for the first layer 221 of the second metal electrode 220. The transparent conductive layer 400 is, for example, ITO. In this embodiment, the length L2 of the first layer 221 of the second metal electrode 220 refers to the longest dimension.

[0043] In some implementations of this embodiment, the projection area of ​​the back surface of the first layer 221 of the second metal electrode 220 is 30 μm 2 Up to 100 μm 2 The area of ​​the first layer 221 of the second metal electrode 220 is increased as much as possible to increase the electrode adhesion.

[0044] See also Figure 6In a third embodiment of the present invention, a display device is provided, wherein a micro-light emitting diode C1 is sealed by an epoxy resin P2, the micro-light emitting diode C1 is bonded and fixed on a substrate 500, and has a semiconductor layer sequence 110, the semiconductor layer sequence 110 includes a back side and a front side, and includes a first type semiconductor layer 111 and a first type semiconductor layer 112 in sequence from the front side, and an active layer 113 is located therebetween, and the back side of the semiconductor layer sequence 110 has a groove G1, the groove G1 penetrates the first type semiconductor layer 112 and the active layer 113, and exposes the first type semiconductor layer 111 and the first type semiconductor layer 112. The semiconductor layer sequence 110 includes a first table M1 in the groove G1, a second table M2 on the first type semiconductor layer 112, and a sidewall S1 of the groove G1 between the two. The semiconductor layer sequence 110 is provided with a first metal electrode 210 electrically connected to the first type semiconductor layer 111 and a second metal electrode 220 electrically connected to the first type semiconductor layer 112 on the back side. The chromium content of the first metal electrode 210 is greater than that of the second metal electrode 220. The length L1 of the second metal electrode 220 is 2μm to 30μm. Since the stress of the epoxy resin P2 is large, the chromium leakage in the second metal electrode 220 is likely to occur. Therefore, reducing or eliminating the chromium content of the first electrode is beneficial to improving the product yield. The micro-light emitting diode of Example 1 is used for sealing, which effectively improves the performance and yield of the overall display device.

[0045] In the fourth embodiment of the present invention, a display device is provided, which is different from the embodiment 3 in that the micro-LED chip of the embodiment 2 is used, the first metal electrode 210 contacts the first type semiconductor layer 111 through the first layer 211 of the first metal electrode chromium, and the first layer 221 of the second metal electrode 220 does not contain chromium. Thus, the performance and yield of the overall display device are improved.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A micro light emitting diode, comprising a semiconductor layer sequence, the semiconductor layer sequence comprising a back side and a front side, and comprising a first type semiconductor layer and a second type semiconductor layer in order from the front side, with an active layer located therebetween, the back side of the semiconductor layer sequence comprising a groove, the groove penetrating the second type semiconductor layer and the active layer, exposing the first type semiconductor layer, the back side of the semiconductor layer sequence comprising a first table in the groove, a second table on the second type semiconductor layer and a groove sidewall located therebetween, the back side of the semiconductor layer sequence comprising a first metal electrode electrically connected to the first type semiconductor layer and a second metal electrode electrically connected to the second type semiconductor layer, characterized in that: The chromium content of the first metal electrode is greater than that of the second metal electrode, and the length of the second metal electrode is 2 μm to 30 μm.

2. A micro light emitting diode according to claim 1, characterized in that: The first metal electrode contacts the first type semiconductor layer through chromium, and the second metal electrode does not contain chromium.

3. The micro light emitting diode according to claim 1, characterized in that: The length of the second metal electrode is 5 μm to 30 μm.

4. The micro light emitting diode according to claim 1, characterized in that: The first metal electrode is completely disposed in the groove, and the groove is a non-closed step; three of the four sides of the groove are exposed, and the other side is the groove sidewall, or two of the four sides of the groove are exposed, and the other two sides are the groove sidewalls.

5. The micro light emitting diode according to claim 1, characterized in that: The first metal electrode covers from the inside of the groove to the second terrace, and the height of the side wall of the groove is 0.5 μm to 2 μm.

6. The micro light emitting diode according to claim 1, characterized in that: The projected area of ​​the back surface of the first metal electrode and / or the second metal electrode is 25 μm 2 Up to 100 μm 2 .

7. The micro light emitting diode according to claim 1, characterized in that: The distance between the first metal electrode and the second metal electrode is 4 μm to 10 μm.

8. The micro light emitting diode according to claim 1, characterized in that: The second mesa is located on a side of the second type semiconductor layer away from the active layer, a passivation layer is arranged on the second mesa, the passivation layer covers at least from the second mesa to the first mesa, the passivation layer has a first opening on the first mesa, the passivation layer has a second opening on the second mesa, the first metal electrode is electrically connected to the first type semiconductor layer through the first opening, the second metal electrode is electrically connected to the second type semiconductor layer through the second opening, and a transparent conductive layer is arranged between the second metal electrode and the second type semiconductor layer.

9. The micro light emitting diode according to claim 8, characterized in that: The maximum pore diameter of the second opening is 2 μm to 20 μm.

10. The micro light emitting diode according to claim 8, characterized in that: The passivation layer is arranged between the second metal electrode and the second type semiconductor layer, the second metal electrode is connected from the second opening to the upper surface of the back side of the passivation layer, the second metal electrode is not arranged between the passivation layer and the second type semiconductor layer, or the second metal electrode is not arranged between the passivation layer and the transparent conductive layer.

11. The micro light emitting diode according to claim 8, characterized in that: The thickness of the passivation layer is 0.5 μm to 3 μm.

12. The micro light emitting diode according to claim 8, characterized in that: The back surface of the first metal electrode corresponding to the first opening has a first electrode hole, and the back surface of the second metal electrode corresponding to the second opening has a second electrode hole, wherein the opening area of ​​the first electrode hole is smaller than the opening area of ​​the second electrode hole.

13. The micro light emitting diode according to claim 12, characterized in that: The opening area of ​​the first electrode hole accounts for 10% to 40% of the back surface area of ​​the first metal electrode, and the opening area of ​​the second electrode hole accounts for 15% to 50% of the back surface area of ​​the second metal electrode.

14. The micro light emitting diode according to claim 1, characterized in that: The first metal electrode and the second metal electrode have n metal stacks, where n is an integer greater than or equal to 2. The first layer of the first metal electrode is close to the first table side and contains chromium, and is used to connect to the first type semiconductor layer; the first layer of the second metal electrode is close to the second table side and does not contain chromium, and is in contact with a transparent conductive layer, and the transparent conductive layer is electrically connected to the second type semiconductor layer.

15. The micro light emitting diode according to claim 14, characterized in that: The length of the first layer of the second metal electrode is greater than 2 μm to 25 μm.

16. The micro light emitting diode according to claim 14, characterized in that: The first layer of the second metal electrode includes nickel, aluminum, titanium, platinum, gold or any alloy thereof.

17. The micro light emitting diode according to claim 1, characterized in that: The first metal electrode is an N-type electrode, and the second metal electrode is a P-type electrode.

18. A display device, comprising a plurality of micro-LEDs and a substrate, wherein the micro-LEDs are arranged on the substrate, characterized in that: The micro-light emitting diode is sealed by epoxy resin. The micro-light emitting diode has a semiconductor layer sequence. The semiconductor layer sequence includes a back side and a front side. Starting from the front side, it includes a first type semiconductor layer and a second type semiconductor layer in sequence, and an active layer is located between the two. The back side of the semiconductor layer sequence has a groove. The groove penetrates the second type semiconductor layer and the active layer to expose the first type semiconductor layer. The back side of the semiconductor layer sequence includes a first table in the groove, a second table on the second type semiconductor layer and a groove sidewall located therebetween. The back side of the semiconductor layer sequence is provided with a first metal electrode electrically connected to the first type semiconductor layer and a second metal electrode electrically connected to the second type semiconductor layer, characterized in that: the chromium content of the first metal electrode is greater than that of the second metal electrode, and the length of the second metal electrode is 2μm to 30μm.

19. A display device according to claim 18, characterized in that: The first metal electrode contacts the first type semiconductor layer through chromium, and the second metal electrode does not contain chromium.

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