Miniature light emitting diode and miniature light emitting diode chip

Abstract

The present invention provides a micro light emitting diode, comprising: a light emitting mesa configured to emit light; and a mirror layer configured to reflect light from the light emitting mesa, where the mirror layer has an atomic layer deposition layer on a side facing the light emitting mesa, the atomic layer deposition layer configured to block metal diffusion in the mirror layer. According to the invention, metal diffusion and oxidation in the reflector layer can be effectively inhibited.

Description

Technical Field

[0001] The present invention generally relates to the field of semiconductors, and more specifically to a micro light emitting diode. In addition, the present invention also relates to a micro light emitting diode chip. Background Art

[0002] Micro Light Emitting Diode (MLD) is a new type of LED structure obtained by thin-filming, miniaturizing and arraying the original LED structure. It integrates arrayed micron-level LED units on an active addressing drive panel to realize the lighting and individual control of the LED units, thereby outputting the desired display image. The core structure of a micro-LED is a PN junction diode, which is composed of direct bandgap semiconductor materials. When the upper and lower electrodes apply a forward bias to the micro-LED to cause current to pass through, electrons and holes recombine in the active region (Active region) and emit single-color light photons at the same time.

[0003] The reflector layer in the micro-LED is located under or around the chip. It is a special structural layer whose main function is to reflect photons to prevent light from being absorbed or lost inside the micro-LED chip, thereby improving light output efficiency.

[0004] The reflector layer is usually made of metal materials. Common materials include aluminum (Al), silver (Ag), etc. These metals have the characteristics of high reflectivity and can effectively reflect light. For example, aluminum has a high reflectivity in the visible light band, and its cost is relatively low and it is easy to process, so it is widely used in many micro-LED products. The reflectivity of silver is even higher than that of aluminum in some bands, but silver is easy to oxidize and diffuse, so special protection treatment is required. Otherwise, if silver is oxidized, the reflectivity of silver will decrease, affecting the performance of the reflector layer, or if silver diffuses into other semiconductor structures, it is easy to cause short circuits or affect their performance.

[0005] Currently, a reflector structure that can suppress metal diffusion and oxidation is needed in micro-LED chips. Summary of the invention

[0006] Based on the prior art, the object of the present invention is to provide a micro light emitting diode and a micro light emitting diode chip, by which metal diffusion and oxidation in the reflector layer can be effectively suppressed.

[0007] In a first aspect of the present invention, the aforementioned object is solved by a micro-light emitting diode, the micro-light emitting diode comprising:

[0008] a light-emitting table configured to emit light; and

[0009] A reflector layer is configured to reflect light from the light emitting mesa, wherein the reflector layer has an atomic layer deposition layer on a side facing the light emitting mesa, and the atomic layer deposition layer is configured to block metal diffusion in the reflector layer.

[0010] In one embodiment of the present invention, the upper surface of the light-emitting mesa is larger than the lower surface thereof, and the reflector layer comprises:

[0011] a side reflector layer covering at least a portion of a side surface of the light-emitting mesa, wherein the side reflector layer has an inclined surface on a side facing the light-emitting mesa to reflect light from the light-emitting mesa upward; and

[0012] The bottom reflector layer covers at least a portion of the bottom surface of the light-emitting mesa, wherein the bottom reflector layer has an atomic layer deposition layer on a side facing the light-emitting mesa.

[0013] In another embodiment of the present invention, the upper surface of the light-emitting mesa is smaller than the lower surface thereof, and the reflector layer covers the bottom surface of the light-emitting mesa.

[0014] In another embodiment of the present invention, the reflector layer includes, starting from the side facing the light-emitting mesa:

[0015] an atomic layer deposition layer, the material of which is selected from one or more of the following: nickel, platinum, titanium, and tantalum;

[0016] A reflective metal layer, wherein the material of the reflective metal layer is selected from one or more of the following: silver, aluminum, and gold;

[0017] A first barrier layer comprising at least first and second barrier layers, wherein the materials of the first and second barrier layers are respectively selected from one or more of the following: platinum, titanium, and tantalum; and

[0018] The second barrier layer is made of a material selected from one or more of the following: platinum, titanium, and tantalum.

[0019] In another embodiment of the present invention, the material of the second barrier layer is different from the material of the first barrier layer.

[0020] In another embodiment of the present invention, it is provided that:

[0021] The ALD layer material is nickel;

[0022] The material of the reflective metal layer is silver;

[0023] The materials of the first and second barrier layers are titanium and platinum, respectively; and

[0024] The material of the second barrier layer is titanium.

[0025] In another embodiment of the present invention, it is provided that:

[0026] The thickness of the ALD layer is 3 to 8 angstroms;

[0027] The thickness of the reflective metal layer is 800 to 1200 angstroms;

[0028] The first barrier layer has a thickness of 100 to 300 angstroms, and the second barrier layer has a thickness of 400 to 600 angstroms; and

[0029] The second barrier layer has a thickness of 100 to 300 angstroms.

[0030] In another embodiment of the present invention, the reflector layer includes N first barrier layers and N second barrier layers that are alternately arranged with each other, wherein N is an integer, and N=2-5.

[0031] In another embodiment of the present invention, the micro light emitting diode further comprises:

[0032] The insulating layer includes a recess in which at least a portion of the epitaxial layer is disposed.

[0033] In another embodiment of the present invention, the micro light emitting diode further comprises:

[0034] A passivation layer is arranged between the side reflector layer and the insulating layer.

[0035] In another embodiment of the present invention, the light-emitting table comprises:

[0036] A first epitaxial layer extending beyond the recess of the insulating layer and electrically contacting the light emitting layer;

[0037] a light emitting layer in the recess and between the first epitaxial layer and the second epitaxial layer; and

[0038] A second epitaxial layer is in the recess and is in electrical contact with the light emitting layer and the first through-hole contact.

[0039] In another embodiment of the present invention, the material of the passivation layer is selected from one or more of the following:

[0040] Aluminum oxide, silicon oxide, and silicon nitride.

[0041] In another embodiment of the present invention, the micro light emitting diode further comprises:

[0042] a through-hole contact arranged at the bottom of the epitaxial layer to electrically connect the epitaxial layer with a driving circuit; and

[0043] An etching buffer layer is arranged between the reflective mirror layer and the via contact to prevent the via contact from being over-etched.

[0044] In another embodiment of the present invention, the micro light emitting diode further comprises:

[0045] A bottom transparent conductive layer is disposed between the mirror layer and the via contact to electrically connect the epitaxial layer to the via contact.

[0046] In a second aspect of the present invention, the aforementioned object is solved by a micro-light emitting diode chip, the micro-light emitting diode comprising:

[0047] A plurality of light emitting diodes according to the present invention, wherein the light emitting diodes further comprise:

[0048] a first electrode electrically connected to the through-hole contact portion;

[0049] a passivation layer disposed between the side reflector layer and the insulating layer;

[0050] a top transparent conductive layer disposed on and in electrical contact with the first epitaxial layer; and

[0051] A second electrode is disposed on a surface of the top transparent conductive layer; and

[0052] A driving circuit having a metal layer on its surface, a plurality of through-hole contacts being arranged on the driving circuit, the through-hole contacts being electrically connected to the metal layer, the micro light-emitting diode being connected (e.g., bonded) to the driving circuit via a bottom conductive bonding layer, and each light-emitting mesa corresponding to one of the through-hole contacts, and the light-emitting mesa comprising a first epitaxial layer, a light-emitting layer, and a second epitaxial layer deposited in sequence.

[0053] In one embodiment of the present invention, the second electrode is a ring-shaped reflective electrode, which is arranged around the light-emitting mesa.

[0054] In another embodiment of the present invention, the polarity of the second electrode is opposite to that of the first electrode.

[0055] In another embodiment of the present invention, the material of the second epitaxial layer is a material layer of the second conductivity type containing at least two or more elements of Ga, N, As, Al, In, and P, and the first epitaxial layer is a material layer of the first conductivity type containing at least two or more elements of Ga, N, As, Al, In, and P, wherein the first conductivity type is different from the second conductivity type.

[0056] In another embodiment of the present invention, the light emitting layer comprises a multi-quantum well layer, wherein the multi-quantum well layer is an InGaN / GaN multi-quantum well layer, an InGaN / AlGaN multi-quantum well layer, an InGaAs / AlGaAs multi-quantum well layer, or an AlGaInP multi-quantum well layer.

[0057] In another embodiment of the present invention, an electron blocking layer is disposed on a first side of the light-emitting layer, wherein the first side refers to a side along which electrons migrate out of the light-emitting layer.

[0058] In another embodiment of the present invention, the material of the metal layer is an alloy of one or more of the following metals: Ni, Al, Ti, Ni, Pt, Au.

[0059] In another embodiment of the present invention, the material of the passivation layer is Si3N4 film, SiO2 film or Al2O3 film.

[0060] In another embodiment of the present invention, the micro-LED chip further comprises a micro-lens, and the micro-lens comprises:

[0061] a lens portion, which is on the outermost side; and

[0062] The spacer is between the lens portion and the light emitting mesa.

[0063] In a third aspect of the present invention, the aforementioned object is solved by a micro light emitting diode chip, the micro light emitting diode chip comprising:

[0064] The upper stack comprises:

[0065] a first insulating layer accommodating the light emitting mesa and the first via contact;

[0066] A light-emitting mesa that emits light, wherein the top surface area of ​​the light-emitting mesa is larger than the bottom surface area of ​​the light-emitting mesa;

[0067] a reflector layer, wherein the reflector layer covers at least a portion of a side surface and / or at least a portion of a bottom surface of the light emitting mesa, and has an atomic layer deposition layer on a side facing the light emitting mesa, wherein the atomic layer deposition layer is configured to block metal diffusion in the reflector layer; and

[0068] a first through-hole contact portion electrically connected to the bottom of the light-emitting mesa and passing through the first insulating layer; and

[0069] The lower stack comprises:

[0070] a second insulating layer accommodating a second through-hole contact;

[0071] a second through-hole contact passing through the second insulating layer; and

[0072] The driving back plate is electrically connected to the second via contact, wherein the lower stack is bonded to the upper stack by hybrid bonding, so that the first via contact is bonded to the second via contact, and the first insulating layer is bonded to the second insulating layer.

[0073] The present invention has at least the following technical effects:

[0074] (1) By adding an atomic layer deposition layer made of a barrier metal on the side of the reflector layer facing the light-emitting mesa, it is possible to better prevent the metal in the reflector from diffusing into the light-emitting mesa through the bottom transparent conductive layer arranged between the reflector layer and the light-emitting mesa, causing the performance degradation or failure of the light-emitting mesa, and inhibit the oxidation of the reflective metal, thereby inhibiting the reduction of the reflection efficiency caused by oxidation;

[0075] (2) The present invention significantly improves the metal barrier effect by changing the number of alternating metal stacks (e.g., alternating stacks of platinum layers and titanium layers) in the reflector layer; in addition, a second and a third barrier layer made of barrier metal are also provided on the side of the reflector layer facing away from the light-emitting mesa, which can effectively inhibit the diffusion of easily diffusible metals such as silver in the reflector layer into the insulating layer, thereby avoiding short circuit or failure of the insulating layer caused by diffusion;

[0076] (3) The present invention makes the first epitaxial layer on the upper surface of the light-emitting table protrude out of the recess of the insulating layer, so that the surface area of ​​the first epitaxial layer is not limited by the recess opening, thereby significantly increasing the area and thickness of the first epitaxial layer; in addition, since the recess only needs to accommodate the light-emitting layer and the second epitaxial layer, these two layers have a larger area and thickness compared with the structure of the prior art that needs to accommodate three layers, thereby better increasing the area and thickness of the epitaxial layer and improving the light emission. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] The present invention will be further described below in conjunction with specific embodiments with reference to the accompanying drawings.

[0078] Figure 1 A first embodiment of a mirror layer according to the invention is shown;

[0079] Figure 2 A second embodiment of a mirror layer according to the invention is shown;

[0080] Figure 3 shows a first application scenario of the reflector layer according to the present invention; and

[0081] Figure 4 A second application scenario of the mirror layer according to the present invention is shown. DETAILED DESCRIPTION

[0082] In the following description, the present invention is described with reference to various embodiments. However, those skilled in the art will recognize that the embodiments may be implemented without one or more specific details or with other alternative and / or additional methods, materials or components. In other cases, well-known structures, materials or operations are not shown or described in detail to avoid obscuring the inventive points of the present invention. Similarly, for the purpose of explanation, specific numbers, materials and configurations are described to provide a comprehensive understanding of the embodiments of the present invention. However, the present invention is not limited to these specific details.

[0083] It should be noted that the components in the figures may be shown exaggeratedly for the sake of illustration and are not necessarily true to scale. In the figures, identical or functionally identical components are provided with the same reference numerals.

[0084] In the present invention, unless otherwise specified, "arranged on...", "arranged above..." and "arranged above..." do not exclude the existence of an intermediate between the two. In addition, "arranged on or above..." merely indicates the relative positional relationship between two components, and in certain cases, such as after reversing the product direction, it can also be converted into "arranged below or below...", and vice versa.

[0085] In the present invention, each embodiment is only intended to illustrate the aspects of the present invention and should not be construed as limiting.

[0086] In the present invention, unless otherwise specified, the quantifiers "a", "an" and "an" do not exclude the presence of a plurality of elements.

[0087] In the present invention, the term “connected” may refer to both being directly connected or being indirectly connected via an intermediate element.

[0088] In the present application, the term "configuration" refers to the setting of the shape, structure, material and / or function of the target object to achieve the desired technical effect, wherein "configuration" includes a variety of alternative technical means for achieving the technical effect, which become obvious under the teaching of the present application.

[0089] In this specification, reference to "one embodiment" or "the embodiment" means that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present invention. The phrase "in one embodiment" appearing in various places in this specification does not necessarily all refer to the same embodiment.

[0090] It should be noted that the embodiments of the present invention describe the process steps in a specific order, but this is only for the purpose of illustrating the specific embodiment, rather than limiting the order of the steps. On the contrary, in different embodiments of the present invention, the order of the steps can be adjusted according to the adjustment of the process.

[0091] In the present invention, the term "upper part of the light-emitting mesa" refers to the part of the light-emitting mesa facing the microlens or the light-emitting side, and the term "lower part of the light-emitting mesa" refers to the part of the light-emitting mesa facing the driving backplane or the anode. Similarly, the term "upper surface or top surface of the light-emitting mesa" refers to the surface of the light-emitting mesa facing the microlens or the light-emitting side, and the term "lower surface or bottom surface of the light-emitting mesa" refers to the surface of the light-emitting mesa facing the driving backplane or the anode.

[0092] Figure 1 A first embodiment of a mirror layer 200 according to the invention is shown.

[0093] like Figure 1 The reflector layer 200 according to the present invention includes, from top to bottom, an atomic layer deposition layer 201, a reflective metal layer 202, a first barrier layer 203, and a second barrier layer 204, wherein the upper side of the reflector layer 200 faces the light-emitting mesa or epitaxial layer of the micro-light-emitting diode, and the lower side of the reflector layer 200 faces away from the light-emitting mesa or epitaxial layer of the micro-light-emitting diode or faces the bottom transparent conductive layer. Each layer is described below.

[0094] ·Atomic layer deposition layer 201, which is arranged at the uppermost layer, i.e., the outermost layer toward the light-emitting mesa or epitaxial layer. The material of the atomic layer deposition layer 201 may include nickel, platinum, titanium, and tantalum, for example. The material of the atomic layer deposition layer 201 is preferably nickel. The thickness of the atomic layer deposition layer is 3 to 8 angstroms, preferably 5 angstroms. 1 angstrom = 10^(-10) meters. The function of the atomic layer deposition layer 201 is to deposit a certain thickness of barrier metal (e.g., nickel) on the outer side of the reflective metal layer 201 through an atomic layer deposition (ALD) process, and the barrier metal can effectively block or at least inhibit the outward diffusion of the reflective metal layer 201, for example, preventing it from diffusing through the transparent conductive layer into the light-emitting mesa or epitaxial layer disposed thereon.

[0095] A reflective metal layer 202 is disposed between the atomic layer deposition layer 201 and the first barrier layer 203 and is configured to reflect light. The material of the reflective metal layer 202 may include silver, aluminum, and gold, for example.

[0096] Aluminum (Al): Aluminum is a commonly used optical reflective material. It has a high reflectivity, which can reach about 80%-90% in the visible light range. In addition, the cost of aluminum is relatively low, and it is easy to form reflectors of various shapes. Aluminum also has a certain reflective ability in the ultraviolet and infrared regions, but its reflective performance will change with the change of wavelength.

[0097] Silver (Ag): The reflectivity of silver is higher than that of aluminum in the visible light band, reaching more than 95%, especially in the blue and green light bands, where its reflectivity is even better. However, silver is easily oxidized, and the reflectivity of oxidized silver decreases. In addition, silver is easy to diffuse. In view of the fact that silver is easy to diffuse and oxidize, the inventors can better prevent the diffusion and oxidation of the reflective metal layer made of silver by arranging an atomic layer deposition layer 201 before the silver layer.

[0098] Gold (Au): Gold has good reflective properties in the infrared band, and its reflectivity in the infrared region can be as high as 98% or more. However, the reflectivity of gold in the visible light band is relatively low, and the color is golden yellow, so gold is mainly used for light reflection of infrared micro-LEDs.

[0099] The material of the reflective metal layer 201 is preferably a metal with high reflectivity, such as silver. The thickness of the reflective metal layer can be, for example, 800 to 1200 angstroms, preferably 1000 angstroms.

[0100] The principle of metal reflection light is as follows: when light shines on the metal surface, the free electrons in the metal will be forced to vibrate under the action of the electric field of the light. These vibrating electrons will radiate electromagnetic waves with the same frequency as the incident light. This is the source of the reflected light.

[0101] The penetration depth of light in metal (also called skin depth) is a physical quantity related to the material properties of the metal and the frequency of light. It represents the distance that light penetrates when the intensity of light decays to 1 / e (about 37%) of the surface intensity. For metals, the penetration depth of light is usually at the nanometer level. In other words, light can penetrate a certain depth (e.g. 200 nanometers) at the nanometer level on the metal surface.

[0102] In view of this, the atomic layer deposition layer 201 is constructed to be as thin as possible, for example, not more than 10 angstroms, such as 3 to 8 angstroms, preferably 5 angstroms, so that the light from the light-emitting table can penetrate the surface atomic layer deposition layer 201 as unimpeded as possible, and be reflected by the reflective metal layer 202 with high reflectivity arranged therebehind. On the other hand, if the atomic layer deposition layer 202 is too thin, it will affect the metal barrier function, so the inventors uniquely set the layer thickness to 3 to 8 angstroms, preferably 5 angstroms, so that both good metal barrier is achieved and the high reflectivity of the reflective metal layer 202 is taken into account.

[0103] A first barrier layer 203, which is arranged between the reflective metal layer 202 and the second barrier layer 204 and includes at least a first barrier layer 203A and a second barrier layer 203B. The first barrier layer 203A and the second barrier layer 203B may include platinum, titanium, and tantalum, for example, respectively. The thickness of the first barrier layer is 100 to 300 angstroms, preferably 200 angstroms, and the thickness of the second barrier layer is 400 to 600 angstroms, preferably 500 angstroms. For example, the first barrier layer 203A is preferably made of titanium, and the second barrier layer 203B is preferably made of platinum. In addition, the first barrier layer 203 may be repeated, for example, the reflector layer 200 may include a plurality of first barrier layers 203 arranged one after another, for example, including 2, 3, 4, 5 or other number of first barrier layers 203. The first barrier layer 203 is configured to perform metal blocking on the reflective metal layer 202 from the back side and prevent it from being oxidized, and in particular, it may block metal atoms of the reflective metal layer such as silver from entering the insulating layer to affect its insulation. In particular, when the first and second barrier layers 203A and 203B are titanium and platinum, respectively, the stack of titanium and platinum has the following technical effects:

[0104] (1) The stacking of titanium and platinum can effectively prevent the reflective layer material from being oxidized or corroded by chemicals. In the reflective layer, if the base reflective material (such as silver) is oxidized, its reflectivity will drop significantly. Titanium and platinum have high chemical stability and can prevent oxygen and other chemicals that may cause the reflective layer material to deteriorate from contacting the core material of the reflective layer, such as silver, thereby ensuring that the reflective performance remains stable during long-term use.

[0105] (2) The stacking of titanium and platinum can adjust the optical constants of the reflective layer to make it better suited to different reflective metals. Different optical devices have different requirements for the optical parameters of the reflective layer (such as refractive index, extinction coefficient, etc.). Titanium and platinum have specific optical properties in the optical frequency band. By adjusting the thickness and number of layers of the stacking, the optical properties of the reflective metal layer can be fine-tuned to meet the needs of a specific optical system. In particular, when the number of stacking layers is 3, it has better reflective properties for the light of the light-emitting table of the micro-LED, and at the same time has better metal blocking ability and anti-oxidation ability for the silver reflective metal layer.

[0106] A second barrier layer 204 is arranged on the outermost side of the reflector layer 200 toward the bottom transparent conductive layer. The material of the second barrier layer 204 may include platinum, titanium, and tantalum, preferably titanium. The thickness of the second barrier layer may be, for example, 100 to 300 angstroms, preferably 200 angstroms. The second barrier layer 204 has metal blocking and anti-oxidation effects on one hand, and can prevent the oxidation of the reflective metal layer and block its metal diffusion on the other hand. On the other hand, it can participate in the fine-tuning of the reflective characteristics of the reflective metal layer, for example, forming a titanium-platinum-titanium fine-tuning stacked layer with the first and second barrier layers of the first barrier layer 203. In this case, the material of the second barrier layer 204 is preferably different from that of the first barrier layer, for example, both are titanium.

[0107] Figure 2 A second embodiment of a mirror layer 200 according to the invention is shown.

[0108] The reflector layer 200 of the second embodiment is basically different from the reflector layer 200 of the first embodiment, and the main difference is that in the second embodiment, the material of the atomic layer deposition layer is nickel with a thickness of 5 angstroms, the material of the reflective metal layer is silver with a thickness of 1000 angstroms, the materials of the first and second barrier layers are titanium and platinum with thicknesses of 200 and 500 angstroms respectively, and the material of the second barrier layer is titanium with a thickness of 200 angstroms; in addition, the number of layers of the first barrier layer 203 is 3.

[0109] In this embodiment, an atomic layer deposition layer 201 made of nickel is disposed on the front side of the silver metal reflective layer 202, and a first barrier layer 202 composed of three titanium layers and platinum layers is disposed behind the silver metal reflective layer 202, so that titanium and platinum appear alternately, and a second barrier layer 204 made of titanium is arranged behind the first barrier layer 202. In this way, the arrangement of three stacked pairs can improve the blocking and anti-oxidation effects on the silver reflective metal layer, and can also fine-tune the optical reflection characteristics of silver. In addition, the second barrier layer made of titanium and the first barrier layer 204 constitute a titanium-platinum-titanium stacked pair, which further fine-tunes the reflection characteristics of silver.

[0110] Figure 3 The first application scenario of the reflector layer 200 according to the present invention is shown. In this application scenario, the light-emitting table or epitaxial layer of the micro-LED chip 600 has an inverted trapezoidal structure, that is, the light-emitting table has a large upper surface and a small lower surface, so the reflector layer 200 is arranged to surround all sides of the light-emitting table in the insulating layer and cover its bottom surface, thereby maximizing the light reflection area and improving the light efficiency of the micro-LED.

[0111] The various components of the micro-LED chip 600 are described in detail below.

[0112] like Figure 3As shown, the micro-LED chip 600 according to the present invention comprises an upper stack 600A and a lower stack 600B, wherein the upper stack 600A and the lower stack 600B are hybrid-bonded at the interface A to form a complete micro-LED chip 600. The structures and components of the upper stack 600A and the lower stack 600B are described in detail below.

[0113] Upper layer

[0114] The upper stack 600A includes a first insulating layer 611A, a light emitting mesa 601, a transparent conductive layer 608, a first electrode 604 (cathode), a first via contact 602, a second electrode 610 (anode), a first bonding mark 609A, and a microlens 605. Each component is described below.

[0115] A first insulating layer 611A, which is configured to accommodate at least a portion of the light-emitting mesa 601 and provide electrical insulation therefor. Here, the first electrical insulating layer 611A has a recess 607, which is configured to accommodate the light-emitting layer and the second epitaxial layer of the light-emitting mesa 601 and the auxiliary structure of the light-emitting mesa 601. For a detailed description of the light-emitting mesa 601 and its auxiliary structures (such as the passivation layer 612, the reflector layer 615, etc.), reference can be made to the light-emitting mesa 601 and its description. Here, it should be noted that the recess 607 can be formed after the light-emitting mesa 601, that is, the light-emitting mesa 601 and its auxiliary structures are first formed on the temporary substrate, and then the first insulating layer 611A surrounding them is formed on the light-emitting mesa 601 and its auxiliary structures. The material of the first insulating layer 611A can be, for example, silicon dioxide, silicon nitride, a high dielectric constant material (such as hafnium oxide, aluminum oxide, etc.), etc. The first insulating layer 611A can be formed by thermal oxidation, chemical vapor deposition (CVD), etc. The thickness of the first insulating layer 611A is, for example, 1 to 3 μm, preferably 2 μm, and more preferably 0.6 to 1.4 μm. In addition, the first insulating layer 611A may be planarized at the interface A (eg, by chemical mechanical polishing (CMP)) to facilitate hybrid bonding with the second insulating layer 611B.

[0116] The first insulating layer 611A is transparent to the light emitted from the light emitting mesa 601. In some embodiments, the first insulating layer 611A is made of a dielectric material such as a solid inorganic material or a plastic material. In some embodiments, the solid inorganic material includes silicon dioxide (SiO2), aluminum oxide (Al2O3), silicon nitride (Si3N4), silicon carbonitride (SiCN), hafnium oxide (HfO2), tantalum pentoxide (Ta2O5), titanium dioxide (TiO2), zirconium oxide (ZrO2), lanthanum oxide (La2O3), magnesium oxide (MgO), phospho-silicate glass (PSG), boro-phospho-silicate glass (BPSG), or any combination thereof. In some embodiments, the plastic material includes a polymer such as SU-8, PermiNex, benzocyclobutene (BCB), or a transparent plastic (resin) including spin-on glass (SOG), or an adhesive microresist BCL-1200, or any combination thereof. In some embodiments, the first insulating layer 611A can facilitate the passage of light emitted from the light-emitting mesa 601. In some embodiments, the first insulating layer 611A can include multiple parts, such as three embedded dielectric parts and two bonding dielectric parts. The embedded dielectric part refers to the dielectric layer surrounding each light-emitting diode structure; and the bonding dielectric part refers to the dielectric layer between two light-emitting diode structures. The embedded dielectric part and the bonding dielectric part may have the same or different compositions.

[0117] A light-emitting mesa 601, which emits light, wherein the top surface area of ​​the light-emitting mesa 601 is larger than the bottom surface area of ​​the light-emitting mesa, and is in an "inverted trapezoidal" shape. The inclination angle of the light-emitting mesa 601 can be, for example, 10° to 85°, preferably 30° to 70°, and especially 35° to 50°. The light-emitting mesa 601 includes a first epitaxial layer 601A, a light-emitting layer 601B, and a second epitaxial layer 601C, wherein the first epitaxial layer 601A is arranged on the top of the light-emitting mesa, that is, on the side facing the light-emitting surface, the light-emitting layer 601B is arranged in the recess 607 and arranged between the first epitaxial layer 601A and the second epitaxial layer 601C, and the second epitaxial layer 601C is arranged at the bottom of the light-emitting mesa 601, that is, on the side facing the driving backplane 606. The light-emitting layer 601B, for example, includes a multi-quantum well layer and an electron blocking layer. In one embodiment of the present invention, the first epitaxial layer 601A is an N-type GaN layer or an N-type AlGaN layer, and the second epitaxial layer 601C is a P-type GaN layer or a P-type AlGaN layer, that is, the material of the second epitaxial layer 601C can be a material layer of the second conductivity type including at least two or more elements of Ga, N, As, Al, In, and P, and the first epitaxial layer 601A can be a material layer of the first conductivity type including at least two or more elements of Ga, N, As, Al, In, and P. The multi-quantum well layer is an InGaN / GaN multi-quantum well layer or an InGaN / AlGaN multi-quantum well layer or an InGaAs / AlGaAs multi-quantum well layer. The electron blocking side is arranged on the first side of the light-emitting layer, and the first side refers to the side along which the electrons migrate out of the light-emitting layer. In another embodiment of the present invention, the first epitaxial layer can also be a P-type GaN layer or a P-type AlGaN layer, and the second epitaxial layer can be an N-type GaN layer or an N-type AlGaN layer. The top width of the light-emitting mesa 601 is, for example, 0.5 to 3 μm, preferably 1.0 to 2.0 μm. The thickness of the first epitaxial layer 601A is, for example, 4000 to 5000 angstroms, the thickness of the light-emitting layer 601B is, for example, 3500 to 4000 angstroms, and the thickness of the second epitaxial layer 601C is, for example, 2500 to 3500 angstroms. 1 angstrom = 10^(-10) meters. Figure 3It can be seen that the first epitaxial layer 601A is located outside the recess 607, while the light-emitting layer 601B and the second epitaxial layer 601C are located inside the recess 607. In this way, the surface area of ​​the first epitaxial layer 601A is not limited by the opening area of ​​the recess 607, but can be significantly larger than the opening area of ​​the recess 607, thereby significantly increasing the area and thickness of the first epitaxial layer 601A; in addition, since the recess 607 only needs to accommodate the light-emitting layer 601B and the second epitaxial layer 601C, these two layers have a larger area and thickness compared with the structure of the prior art that needs to accommodate three layers, thereby better increasing the area and thickness of the epitaxial layer 601 and improving the light emission. It can also be seen here that the first epitaxial layer 601A passes through the first electrode 604 from below the first electrode 604 (here, the cathode), so that the first epitaxial layers 601A of adjacent light-emitting mesas 601 can be connected to each other, so that in the case of a common cathode structure (i.e., the first epitaxial layers of all micro-LEDs in the same array are connected to a common cathode), the conductivity between the cathode 604 and the first epitaxial layer 601A can be significantly enhanced compared to the case where the cathode 604 is connected only by the transparent conductive layer 608 covering it, thereby increasing its power supply. In addition, the contact cross section between the first epitaxial layer 601A and the cathode 604 at the edge is partially flat and partially inclined. Compared with the vertical surface, the inclined surface increases the contact area between the first epitaxial layer 601A and the cathode 604, thereby increasing the conductivity.

[0118] The light-emitting mesa 601 further includes auxiliary structures such as passivation layers 612 and 613, a reflector layer 615, a bottom transparent conductive layer 618, etc. The passivation layer 612 is arranged between the light-emitting mesa 601 and the reflector layer 615, and optionally extends on the upper surface of the first insulating layer 611A, while the passivation layer 613 is arranged between the inner wall of the recess 607 and the reflector layer 615, and optionally extends on the upper surface of the first insulating layer 611A. In another embodiment, only one of the passivation layers 612 and 613 extends on the upper surface of the first insulating layer 611A, or both of them do not extend on the upper surface of the first insulating layer 611A, instead, they only extend to the upper surface of the first insulating layer 611A, and the upper surface of the first insulating layer 611A is covered by another insulating layer or a dielectric layer. The role of the passivation layers 612 and 613 is not only to reduce the current leakage at the sidewall, but also to passivate the sidewall defects, and prevent water, oxygen, etc. from damaging the light-emitting mesa during operation, and also to prevent the metal in the reflector layer 615, cathode 604, etc. from diffusing into the first insulating layer 611 or the light-emitting mesa 601. The passivation layers 612 and 613 can be formed by depositing SiO2 material using a CVD process, or by depositing Al2O3 material using an ALD process. The bottom transparent conductive layer 618 is arranged between the second epitaxial layer 601C and the reflector layer 615. The bottom transparent conductive layer 618 is configured to electrically connect the second epitaxial layer 601C of the light-emitting mesa 601 to the reflector layer 615 and then electrically connect to the through-hole contact 602. The material of the bottom transparent conductive layer 618 is, for example, a metal oxide, such as indium tin oxide ITO, zinc oxide ZnO, etc., and its formation method includes, for example, physical vapor deposition (PVD), chemical vapor deposition (CVD), sol-gel method, solution coating method, etc.

[0119] The reflector layer 615 is configured to reflect upward the light from the light emitting mesa 601. To this end, the reflector layer 615 has an inclined surface on the side facing the light emitting mesa 601, and its inclination angle is, for example, the same as the inclination angle of the light emitting mesa, which is 10° to 85°, preferably 30° to 70°, and especially 35° to 50°.

[0120] Here, the reflector layer 615 has a side reflector layer 615A and a bottom reflector layer 615B. The side reflector layer 615 covers at least a portion of the side of the light-emitting mesa 601. Both the side reflector layer 615A and the bottom reflector layer 615B are configured to reflect light from the light-emitting mesa 601 upward, and the bottom reflector layer 615B is also configured to electrically connect the bottom transparent conductive layer 618 to the first through-hole contact 602. In this embodiment, the side reflector layer 615 covers the side of the light-emitting mesa 601 in the recess 607, and the side reflector layer 615 is formed between the passivation layer 612 and the inner wall of the recess 607 of the insulating layer. Due to the presence of the passivation layer 612, the side reflector 615 may or may not have an atomic layer deposition layer on the side facing the light-emitting mesa 601. In the case of having an atomic layer deposition layer, the metal in the reflector layer 615 can be further prevented from penetrating into the light-emitting mesa 601 through the passivation layer 612. The side reflector layer 615A has an inclined surface on the side facing the light-emitting mesa 601 to reflect the light from the light-emitting mesa upward, and its inclination angle is, for example, the same as the inclination angle of the light-emitting mesa 601, which is 10° to 85°, preferably 30° to 70°, and especially 35° to 50°. The bottom reflector layer 615B covers at least a portion of the bottom surface of the light-emitting mesa 601. In this embodiment, the bottom reflector 615B covers the bottom transparent conductive layer 618 of the light-emitting mesa 601. The bottom reflector layer 615B has an atomic layer deposition layer on the side facing the light-emitting mesa 601. The atomic layer deposition layer can block the metal from the reflective metal layer to prevent its diffusion without substantially affecting the reflection of light. For the specific structure of the reflector layer 615, please refer to Figure 1 and Figure 2 and its description.

[0121] The reflector layer 200 includes an atomic layer deposition layer 201, a reflective metal layer 202, a first barrier layer 203, and a second barrier layer 204 from top to bottom (i.e., from facing the light-emitting mesa 601 to facing away from the light-emitting mesa 601), wherein the upper side of the reflector layer 200 faces the light-emitting mesa or epitaxial layer of the micro-light-emitting diode, and the lower side of the reflector layer 200 faces away from the light-emitting mesa or epitaxial layer of the micro-light-emitting diode or faces the bottom transparent conductive layer.

[0122] For example, the stacked structure of the reflector layer 615 is as follows (in order from close to the light-emitting mesa to far away from the light-emitting mesa):

[0123] Atomic layer deposition layer 201, made of nickel, with a thickness of 5 angstroms;

[0124] The reflective metal layer 202 is made of silver and has a thickness of 1000 angstroms;

[0125] The first and second barrier layers 203A and 203B are made of titanium and platinum, respectively, and have thicknesses of 200 and 500 angstroms, respectively;

[0126] The second barrier layer 204 is made of titanium and has a thickness of 200 angstroms.

[0127] In addition, the number of layers of the first barrier layer 203 is three.

[0128] The reflector layer 615 can be formed, for example, by evaporation, sputtering, chemical vapor deposition (CVD), etc., wherein the atomic layer deposition layer 201 of the reflector layer 615 is formed by atomic layer deposition. The thickness of the passivation layer 612 between the reflector layer 612 and the light-emitting table 601 is 800 to 2000 angstroms, preferably 6000 to 1600 angstroms. The thickness of the passivation layer 613 between the reflector layer 615 and the inner wall of the recess 607 is 200 to 800 angstroms, preferably 300 to 600 angstroms.

[0129] A top transparent conductive layer 608, which is arranged on the first epitaxial layer 601A and electrically connects the first electrode 604 (cathode) to the first epitaxial layer 601A. Here, the top transparent conductive layer 608 extends on the first epitaxial layer 601A and completely covers the first epitaxial layer 601A, thereby providing a more uniform power supply for the first epitaxial layer 601A. In other embodiments, the top transparent conductive layer 608 may also only partially cover the first epitaxial layer 601A. In addition, the top transparent conductive layer 608 also extends under the first electrode 604, which is the cathode in this case, so that the transparent conductive layer 608 extends continuously on the first epitaxial layer 601A of the adjacent light-emitting mesa 601A, thereby increasing the coverage area of ​​the first epitaxial layer 601A. The material of the top transparent conductive layer 608 is, for example, a metal oxide, such as indium tin oxide ITO, zinc oxide ZnO, etc., and its formation method includes, for example, physical vapor deposition (PVD), chemical vapor deposition (CVD), sol-gel method, solution coating method, etc.

[0130] The first electrode 604, here a cathode, is arranged to surround the light-emitting mesa 604. The cathode 604 and its connecting parts can be made of materials such as metal (such as copper, silver or aluminum), graphene, ITO, aluminum-doped zinc oxide (AZO) or fluorine-doped tin oxide (FTO) or any combination of the above materials. In another embodiment of the present invention, the cathode 604 and its connecting parts can be made of non-transparent or transparent conductive materials, such as indium tin oxide (ITO). In a preferred embodiment, the cathode 604 is made of a reflective metal (such as copper, silver or aluminum), so that the cathode 604 can reflect light from the light-emitting mesa 601 while optically isolating adjacent light-emitting mesas 601 from each other, for example, reflecting the light upward to the microlens 605, thereby increasing the light output. In another embodiment, a reflective layer, such as a silver layer, can be coated on the surface of the cathode 604 to provide a reflective capability. Here, the surface of the cathode 604 facing the light-emitting mesa 601A is an inclined surface, and is inclined toward both sides (i.e., inclined toward both sides starting from the bottom surface), thereby reflecting the light falling thereon upward, i.e., toward the light-emitting side. In addition, the cathode 604 can be divided into an edge cathode 604A and a middle cathode 604B, wherein the edge cathode 604A is arranged between the second electrode 610 (here, the anode) and the edgemost light-emitting mesa 601, wherein a portion of the edge cathode 604A is arranged on the passivation layer 612, and another portion is arranged on the transparent conductive layer 608, and the middle cathode 604B is arranged between adjacent light-emitting mesas 601, wherein the middle cathode 604B is arranged on the transparent conductive layer 608. In this way, the edge cathode 604A can completely cover the side of the first epitaxial layer 601A and be in electrical contact with it, thereby increasing the electrical contact area between the cathode 604 and the first epitaxial layer 601A.

[0131] A first through-hole contact 602, which is electrically connected to the bottom of the light-emitting mesa 601 and passes through the first insulating layer 611A. The first through-hole contact 602 is used for hybrid bonding with the second through-hole contact 603, and thereby electrically connects the bottom of the light-emitting mesa 601, especially the second epitaxial layer 601C, to the second electrode 610 (here, the anode). The first through-hole contact 602 is preferably a cylindrical through-hole, and the inner wall and / or the middle space are filled with a conductor, such as metal copper. The diameter of the first through-hole contact 602 is 0.3 to 2 μm, preferably 0.6 to 1.4 μm. The first through-hole contact 602 can be planarized at the interface A (for example, by chemical mechanical polishing CMP) to facilitate hybrid bonding with the second through-hole contact 603. In addition, in order to promote the bonding strength between the first through-hole contact 602 and the second through-hole contact 603 and improve the conductivity, a first interface metal layer may be arranged at the first opening of the first through-hole contact 602, and the area of ​​the first interface metal layer is larger than the area of ​​the first opening. Similarly, a second interface metal layer may be arranged at the second opening of the second through-hole contact, and the area of ​​the second interface metal layer is larger than the area of ​​the second opening. The areas of the first interface metal layer and the second interface metal layer may be equal, or the area of ​​the first interface metal layer may be larger than or smaller than the area of ​​the second interface metal layer. When the first interface metal layer and the second interface metal layer 202 are bonded to each other, the bonding surface formed is larger than the bonding surface formed by directly bonding the first opening of the first through-hole contact 602 and the second opening 204 of the second through-hole contact 603, thereby increasing the bonding strength and improving the conductivity between the first through-hole contact 602 and the second through-hole contact 603. The first interface metal layer 201 and the second interface metal layer 202 are made of, for example, a conductive metal, such as copper. The formation method thereof may include, for example, physical vapor deposition (PVD), chemical vapor deposition (CVD), electroplating, chemical plating, etc. The formation method of the first through-hole contact portion 603 may be, for example, as follows: a light-emitting mesa 601 and a first insulating layer 611A are formed on a temporary substrate, and then the first insulating layer 611A is etched to form a through hole leading to the bottom of the light-emitting mesa 601, and then a metal is deposited in the through hole, and finally the opening of the through hole is planarized to form a bonding surface.

[0132] In addition, the first through-hole contact 602 is used to electrically connect the driving circuit 606 to the bottom (here, the reflector layer 607) of the epitaxial layer 601 (or the light-emitting mesa) of the micro-LED array after bonding with the second through-hole contact 603, thereby connecting the epitaxial layer 601 to the anode 610. Here, a first metal barrier layer 617 is provided between the through-hole contact 602 and the reflector layer 607. The first metal barrier layer 617 can prevent the metal in the first through-hole contact 602 from diffusing into the epitaxial layer 601 or the insulating layer 611A or preventing oxidation thereof through the reflector layer 607 and other layers that may be arranged therebetween (e.g., the bottom transparent electrode layer). If the metal in the first through-hole contact 602 diffuses into the epitaxial layer 601, the light-emitting performance of the epitaxial layer 601 will be affected; if it diffuses into the insulating layer 611A, it will affect the insulating effect of the insulating layer 611A, thereby causing leakage current or even short circuit; if the metal in the through-hole contact 602 is oxidized, it may cause poor contact between the first through-hole contact 602 and the reflector layer 607, or even cause the electrical circuit to the epitaxial layer 601 to be broken. It can be seen that by providing the first through-hole contact 602 according to the present invention, the diffusion of the metal in the first through-hole contact 602 can be better avoided, thereby effectively preventing the risks of reduced light-emitting performance, short circuit, and open circuit of the micro-LED. The combination of the first metal barrier layer 617 and the first and second barrier layers 203 and 204 of the reflector layer can further enhance the metal barrier and anti-oxidation effects.

[0133] The second electrode 610, which is an anode in this case, is electrically connected to the driving backplane 606 through a third through-hole contact 614 that passes through the first insulating layer 611A and the second insulating layer 611B. The anode 610 can be connected to an external power source or a control source, for example, to power or control the micro-LED chip 600. Here, the third through-hole contact 614 can include a plurality of through-hole contacts, so as to connect the second epitaxial layer 601C of the plurality of light-emitting mesas to the anode 610. Here, it is exemplarily shown that the third through-hole contact 614 includes two through-hole contacts, but this is merely exemplary, and other numbers of through-hole contacts 614 are also conceivable. The third through-hole contact 614 can be formed either before or after hybrid bonding. If the third through-hole contact 614 is formed before hybrid bonding, the upper and lower parts of the third through-hole contact 614 are first formed in the upper stack 600A and the lower stack 600B, respectively, and then the two are connected through the through-hole contact after hybrid bonding, and then the first insulating layer 611A is etched from above to form the anode 610 on the third through-hole contact 614. If the third through-hole contact 614 is formed after hybrid bonding, the first insulating layer 611A is etched from above to form a through hole leading to the driving backplane 606, and then metal is deposited in the through hole, and then the third through-hole contact 614 is etched to form a recess, and then metal is deposited in the recess to form the anode 610. The anode 610 and its connecting parts can be made of materials such as metal (such as copper, silver or aluminum), graphene, ITO, aluminum-doped zinc oxide (AZO) or fluorine-doped tin oxide (FTO) or any combination of the above materials.

[0134] · A first bonding mark 609A, which is disposed in the first insulating layer 611A and exposes a first mark surface, i.e., an opening of the first bonding mark. The first bonding mark 609A in the upper stack 600A serves as a mark for alignment with the second bonding mark 609B in the lower stack 600B, thereby achieving precise hybrid bonding, wherein the second bonding mark 609B is disposed in the second insulating layer 600B and exposes a second mark surface, i.e., an opening of the second bonding mark. The first bonding mark 609A and the second bonding mark 609B are aligned in such a way that, during hybrid bonding, the first mark surface is aligned and attached to the second mark surface, at which point the upper stack 600A and the lower stack 600B are aligned, and then hybrid bonding can be performed. The first bonding mark 609A and the second bonding mark 609B can be metal vias, and the two can be bonded at the interface. In addition, the first bonding mark 609A and the second bonding mark 609B may have enlarged openings and / or the openings may be coated with a metal layer to facilitate identification of their positions and increase bonding strength.

[0135] A microlens 605 is disposed above the light-emitting mesa 601 to shape the light emitted therefrom, such as converging or collimating. The microlens includes a lens portion 605A and a spacer portion 605B. The lens portion 605A is disposed at the outermost side, i.e., the uppermost side, and is configured to shape the light from the light-emitting mesa 601. The spacer portion 605B is disposed between the lens portion 605A and the light-emitting mesa 601 to adjust the focal position of the lens portion 605A. For example, the focal point of the lens portion 605A can be exactly located in the light-emitting mesa 601 of the micro-LED by adjusting the thickness of the spacer portion 605B and the curvature of the lens portion 605A. The width of the microlens 605 is, for example, 0.8 to 4 μm, preferably 1 to 3 μm. The distance between the lens portion 605A and the cathode 604 is, for example, 0.05 to 4 μm, preferably 0.1 to 0.3 μm. The microlens 605 corresponds to the light-emitting mesa 601 one by one. Meanwhile, in this embodiment, there is a gap between adjacent microlenses 605 and the bottoms thereof are connected to each other. The bottom of the gap is higher than the top of the light-emitting mesa 601, or higher than the bottom of the light-emitting layer 601B of the light-emitting mesa 601, and the lens portion 604A is located above the cathode 604. The microlenses 605 can be formed by multiple depositions. In the process of forming the microlenses, a SiO2 film layer needs to be deposited first, and then ion etching is performed. The microlenses are formed on the surface of the transparent conductive layer 608 at positions corresponding to each light-emitting mesa 601.

[0136] Lower stack

[0137] The lower stack 600B includes a second insulating layer 611B, a second through-hole contact 603, a driving back plate 606, and a second bonding mark 609B. Each component is described below.

[0138] A second insulating layer 611B is arranged on the driving backplate 606 and is configured to accommodate the second through-hole contact 603. The material of the second insulating layer 611B can be, for example, silicon dioxide, silicon nitride, a high dielectric constant material (such as hafnium oxide, aluminum oxide, etc.), etc. The second insulating layer 611B can be formed on the driving backplate 606 by, for example, thermal oxidation, chemical vapor deposition (CVD), etc. The thickness of the second insulating layer 611B is, for example, 1 to 3 μm, preferably 2 μm, and more preferably 0.6 to 1.4 μm. In addition, the second insulating layer 611B can be planarized at the interface A (for example, by chemical mechanical polishing CMP) to promote hybrid bonding with the first insulating layer 611A.

[0139] The second insulating layer 611B may be transparent to the light emitted from the light emitting mesa 601. In some embodiments, the second insulating layer 611B is made of a dielectric material such as a solid inorganic material or a plastic material. In some embodiments, the solid inorganic material includes silicon dioxide (SiO2), aluminum oxide (Al2O3), silicon nitride (Si3N4), silicon carbonitride (SiCN), hafnium oxide (HfO2), tantalum pentoxide (Ta2O5), titanium dioxide (TiO2), zirconium oxide (ZrO2), lanthanum oxide (La2O3), magnesium oxide (MgO), phospho-silicate glass (PSG), boro-phospho-silicate glass (BPSG), or any combination thereof. In some embodiments, the plastic material includes a polymer such as SU-8, PermiNex, benzocyclobutene (BCB), or a transparent plastic (resin) including spin-on glass (SOG), or an adhesive microresist BCL-1200, or any combination thereof. In some embodiments, the second insulating layer 611B can facilitate the passage of light emitted from the light-emitting mesa 601. In some embodiments, the second insulating layer 611B can include multiple parts, such as three embedded dielectric parts and two bonding dielectric parts. The embedded dielectric part refers to the dielectric layer surrounding each light-emitting diode structure; and the bonding dielectric part refers to the dielectric layer between two light-emitting diode structures. The embedded dielectric part and the bonding dielectric part may have the same or different compositions.

[0140] A second via contact 603, which passes through the second insulating layer 611B. The second via contact 603 is configured to be hybrid bonded with the first via contact 602 at the interface A, and thereby electrically connects the bottom of the light-emitting mesa 601, especially the second epitaxial layer 601C, to the second electrode 610 (here, the anode). The second via contact 603 is preferably a cylindrical through-hole, and the inner wall and / or the intermediate space are filled with a conductor, such as metal copper. The diameter of the second via contact 603 is 0.5 to 2.2 μm, preferably 0.8 to 1.6 μm. The second via contact 603 can be planarized at the interface A (for example, by chemical mechanical polishing CMP) to promote hybrid bonding with the first via contact 602. In addition, in order to promote the bonding strength between the second via contact 603 and the first via contact 602 and improve the conductivity, a second interface metal layer can be arranged at the second opening of the second via contact 603, and the area of ​​the second interface metal layer is larger than the area of ​​the second opening. Similarly, a first interface metal layer may be arranged at the first opening of the first through-hole contact 602, and the area of ​​the first interface metal layer is larger than the area of ​​the first opening. The areas of the first interface metal layer and the second interface metal layer may be equal, or the area of ​​the first interface metal layer may be larger than or smaller than the area of ​​the second interface metal layer. After the first interface metal layer and the second interface metal layer are bonded to each other, the bonding surface formed is larger than the bonding surface formed by directly bonding the first opening of the first through-hole contact 602 and the second opening of the second through-hole contact 603, thereby increasing the bonding strength and improving the conductivity between the first through-hole contact 602 and the second through-hole contact 603. The first interface metal layer and the second interface metal layer are, for example, made of a conductive metal, such as copper. The formation method thereof may, for example, include physical vapor deposition (PVD), chemical vapor deposition (CVD), electroplating, chemical plating, and the like. The second through hole contact portion 603 may be formed, for example, as follows: providing a driving backplane 606, then forming a second insulating layer 611B on the driving backplane 606, then etching the second insulating layer 611B to form a through hole leading to the top of the driving backplane 606, then depositing metal in the through hole, and finally flattening the opening of the through hole to form a bonding surface.

[0141] In addition, the second through-hole contact 603 is used to electrically connect the driving circuit 606 to the bottom (here, the reflector layer 607) of the epitaxial layer 601 (or the light-emitting mesa) of the micro-LED array after bonding with the first through-hole contact 603, thereby connecting the epitaxial layer 601 to the anode 610. Here, a first metal barrier layer 617 is provided between the second through-hole contact 603 and the driving circuit 607. The first metal barrier layer 617 can prevent the metal in the second through-hole contact 603 from diffusing into the driving circuit 606 or the insulating layer 611B or preventing it from being oxidized. If the metal in the second through-hole contact 602 diffuses into the driving circuit 606, the electrical performance of the driving circuit will be affected, such as a short circuit; if it diffuses into the insulating layer 611B, it will affect the insulating effect of the insulating layer 611B, thereby causing leakage current or even a short circuit; if the metal in the second through-hole contact 603 is oxidized, it may cause poor contact between the second through-hole contact 603 and the driving circuit 606, or even cause the electrical line to the driving circuit 606 to be broken. It can be seen that by providing the second through-hole contact 603 according to the present invention, the diffusion of the metal in the second through-hole contact 603 can be better avoided, thereby effectively preventing the risks of short circuit, open circuit, etc. of the driving circuit 606. The combination of the first metal barrier layer 617 and the first and second barrier layers 203 and 204 of the reflector layer can further enhance the metal barrier and anti-oxidation effects.

[0142] A driving backplane 606, which is electrically connected to the second through-hole contact 603 so as to electrically connect the second epitaxial layer 601C of the light-emitting mesa 601 to the anode 610. To this end, the driving backplane 606 has a conductive circuit layer for interconnecting each second through-hole contact 603 to the corresponding anode 610. The driving backplane 606 can be, for example, a thin film transistor TFT driving circuit, and can include a 2T1C driving circuit, a 3T1C driving circuit, and a 5T2C driving circuit. The driving backplane 606 is configured to drive the micro light-emitting diode, for example, to control the connection, disconnection and brightness of the micro light-emitting diode. The driving backplane 606 can include, for example, transistors, capacitors, a conductive circuit layer, an insulating layer, and a metal layer. The conductive circuit layer is formed on the substrate and is configured to supply power to the micro light-emitting diode array. The insulating layer is formed on the conductive circuit layer, wherein the insulating layer is provided with a through hole, and the through hole is provided with a through hole contact (for example, an IC copper column) for electrically connecting the conductive circuit layer to the micro light-emitting diode array. The metal layer is used for bonding and electrical contacting of the micro light emitting diodes. The conductive line layer, the metal layer and the insulating layer may have been formed on the substrate 601 by deposition, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD).

[0143] A second bonding mark 609B, which is disposed in the second insulating layer 611B and exposes a second mark surface, i.e., an opening of the second bonding mark. The second bonding mark 609B in the lower stack 600B serves as a mark for alignment with the first bonding mark 609A in the upper stack 600A, thereby achieving precise hybrid bonding. The alignment method of the first bonding mark 609A and the second bonding mark 609B is that during hybrid bonding, the first mark surface is aligned and attached to the second mark surface. At this time, the upper stack 600A and the lower stack 600B have been aligned, and then hybrid bonding can be performed. The first bonding mark 609A and the second bonding mark 609B can be metal through holes, and the two can be bonded at the interface. In addition, the first bonding mark 609A and the second bonding mark 609B can have an enlarged opening and / or a metal layer can be coated at the opening to facilitate identification of their positions and increase bonding strength.

[0144] After the lower stack 600A and the upper stack 600B are formed, the lower stack 600A is bonded to the upper stack 600A by hybrid bonding, so that the first through hole contact portion 602 is bonded to the second through hole contact portion 603, and the first insulating layer 611A is bonded to the second insulating layer 611B, and optionally the first bonding mark 609A is bonded to the second bonding mark 609B, and the upper and lower parts of the third through hole between the preliminary 614 are bonded to each other. The present invention solves the technical problem encountered when manufacturing an inverted trapezoidal light-emitting mesa with a large upper surface and a small lower surface, that is, the problem of electrical connection between the light-emitting mesa and the driving backplane, by separately manufacturing the upper stack 600A and the lower stack 600B and then bonding the two to each other by hybrid bonding. The present invention realizes the electrical connection from the light-emitting table 601 to the driving backplane 606 through hybrid bonding, so that the upper stack 600A and the lower stack 600B can be manufactured from the surface opposite to the hybrid bonding surface, that is, the interface A, toward the hybrid bonding surface, thereby realizing a high-quality conductive structure, such as the first to third through-hole contacts (such as IC copper pillars), and the length of the conductive structure can also be flexibly selected.

[0145] An example of a hybrid bond may include the following two parts:

[0146] (1) Dielectric-to-dielectric bonding (i.e., bonding between the first insulating layer 611A and the second insulating layer 611B): At room temperature, extremely flat and smooth dielectric surfaces obtained by chemical mechanical polishing (CMP) are activated by plasma treatment or other methods and then brought into close contact at room temperature to achieve preliminary bonding.

[0147] (2) Metal-to-metal bonding (i.e., bonding between through-hole contacts): After completing dielectric-to-dielectric bonding, the upper and lower layers are heated to 200-400°C for annealing to strengthen the dielectric bonding and promote metal-to-metal bonding, thereby achieving hybrid bonding.

[0148] Figure 4 A second application scenario of the mirror layer according to the present invention is shown.

[0149] Figure 4 The micro-LED 700 in the second application scenario is shown in FIG. Figure 3 The structure of the micro-LED chip 600 in the first application scenario is basically the same, and the main difference is that in the second application scenario, the light-emitting table 708 (or epitaxial layer) of the micro-LED chip 700 is a regular trapezoidal structure with a small upper surface and a large lower surface. Here, the reflector layer 717 according to the present invention is only arranged between the bottom transparent conductive layer 716 and the anode 713, and is not arranged on the side of the light-emitting table 708.

[0150] The various components of micro light emitting diode 700 are described in detail below.

[0151] · Driving circuit 702 (i.e., driving backplane), driving circuit 702 can be based on silicon or glass, that is, driving circuit 702 can have a silicon or glass substrate. Driving circuit 702 can be, for example, a driving circuit in various forms, such as a CMOS driving circuit or a thin film transistor TFT driving circuit, such as a 2T1C driving circuit, a 3T1C driving circuit, and a 5T2C driving circuit. Driving circuit 702 is configured to drive micro light emitting diodes, such as controlling the connection, disconnection, and brightness of the micro light emitting diodes. Driving circuit 702 can include, for example, transistors, capacitors, a conductive circuit layer, an insulating layer, and a metal layer. The conductive circuit layer is formed on the substrate and is configured to supply power to the micro light emitting diode array. The insulating layer is formed on the conductive circuit layer, wherein a through hole is provided in the insulating layer, and a through hole contact portion (e.g., an IC copper column) is provided in the through hole for electrically connecting the conductive circuit layer to the micro light emitting diode array. The metal layer is used for bonding and electrically contacting the micro light emitting diodes. The conductive circuit layer, the metal layer and the insulating layer may be formed on the driving circuit 702 by deposition, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD). According to the specific application scenario, the metal layer and the insulating layer may be patterned by photolithography and through holes may be formed thereon. In addition, the transistors and capacitors in the conductive circuit layer may be formed by deposition and etching.

[0152] In one embodiment of the present invention, the circuit may be electrically connected to each micro-LED in the micro-LED array via a separate metal interconnect. In some embodiments, each micro-LED may be electrically controlled individually by a drive circuit. In some embodiments, the drive backplane may be electrically connected to electrodes of a micro-LED chip via a metal interconnect. In some embodiments, a dielectric layer may be formed in the gaps between the micro-LEDs. In some embodiments, a dielectric layer may also be formed in the gaps between the interconnects.

[0153] The micro-LED chip includes a plurality of micro-LED arrays, each of which includes a plurality of micro-LEDs. The driving mode of the micro-LEDs is, for example, passive matrix (PM) driving, in which the cathodes of all the micro-LEDs in each array are connected to the cathode in common, and the micro-LEDs with the same number in each array are connected to the corresponding anodes respectively. Thus, the on-off and the light emitting brightness of each LED can be individually controlled by controlling the model numbers on the corresponding cathode and anode.

[0154] · A micro-LED array 703, which includes a light-emitting table 708. The micro-LED array 703 is formed on the driving circuit 702. For the specific structure of the light-emitting table, please refer to the description below. The micro-LED array 703 is bonded to the driving circuit 702 by bonding, and the bonding method includes full-surface bonding and hybrid bonding. In some embodiments, the micro-LED array may include blue micro-LEDs. In some embodiments, the pitch of the micro-LED array, that is, the minimum center-to-center distance between the micro-LEDs, may be between about 2 microns and about 50 microns. In some embodiments, the number of pixels on the micro-LED chip 100 may be between thousands and millions.

[0155] Each micro LED consists of the following components:

[0156] A light-emitting mesa 708, which is configured to emit light, wherein the area of ​​the upper surface of the light-emitting mesa 708 is smaller than the area of ​​the lower surface, i.e., it is in the shape of a regular trapezoid. The light-emitting mesa 708 includes a first epitaxial layer, a second epitaxial layer, and a light-emitting layer arranged between the first epitaxial layer and the second epitaxial layer. The light-emitting mesa 708 includes a first epitaxial layer, a light-emitting layer, and a second epitaxial layer deposited in sequence, wherein the light-emitting layer includes a multi-quantum well layer and an electron blocking layer. In one embodiment of the present invention, the first epitaxial layer is an N-type GaN layer or an N-type AlGaN layer, and the second epitaxial layer is a P-type GaN layer or a P-type AlGaN layer, i.e., the material of the second epitaxial layer can be a material layer of the second conductivity type including at least two or more elements of Ga, N, As, Al, In, and P, and the first epitaxial layer can be a material layer of the first conductivity type including at least two or more elements of Ga, N, As, Al, In, and P. The types of the first epitaxial layer and the second epitaxial layer can be interchangeable. The multi-quantum well layer is an InGaN / GaN multi-quantum well layer or an InGaN / AlGaN multi-quantum well layer or an InGaAs / AlGaAs multi-quantum well layer. The electron blocking side is arranged on the first side of the light-emitting layer, and the first side refers to the side along which the electrons migrate out of the light-emitting layer. In another embodiment of the present invention, the first epitaxial layer may also be a P-type GaN layer or a P-type AlGaN layer, and the second epitaxial layer may be an N-type GaN layer or an N-type AlGaN layer.

[0157] In one embodiment of the present invention, the first epitaxial layer (or the first type epitaxial layer) is a semiconductor material having a first conductivity type and includes a plurality of semiconductor layers. The main matrix material of the first epitaxial layer may be, but is not limited to, Ga, N, As, P, In, and includes, but is not limited to, a waveguide layer, a confinement layer, a transition layer, and a window layer; in addition, an ohmic contact layer may be formed below the window layer. In some embodiments, the second epitaxial layer (or the second type epitaxial layer for short) is a semiconductor material having a second conductivity type and includes a plurality of semiconductor layers. The main matrix material of the second epitaxial layer may be, but is not limited to, at least two or more elements of Ga, N, As, P, In, and Al. In addition, the first epitaxial layer may include, from top to bottom, but is not limited to, a confinement layer and a waveguide layer; in addition, in some embodiments, an ohmic contact layer may be formed on the confinement layer. In one embodiment of the present invention, the first epitaxial layer is an N-type GaN layer or an N-type AlGaN layer, and the second epitaxial layer is a P-type GaN layer or a P-type AlGaN layer, that is, the material of the second epitaxial layer can be a material layer of the second conductivity type containing at least two or more elements of Ga, N, As, Al, In, and P, and the first epitaxial layer can be a material layer of the first conductivity type containing at least two or more elements of Ga, N, As, Al, In, and P. In another embodiment of the present invention, the first epitaxial layer can also be a P-type GaN layer or a P-type AlGaN layer, and the second epitaxial layer can be an N-type GaN layer or an N-type AlGaN layer. In an embodiment of the present invention, the light-emitting mesa is stepped or trapezoidal.

[0158] The first electrode, here the cathode 711, is electrically connected to the first epitaxial layer of the light-emitting mesa 708 through the transparent conductive layer 709 and the cathode contact 714 passing through the passivation layer 715. The cathode 711 may also include a ring-shaped reflective electrode 712, which is arranged around the light-emitting mesa 708, which may be formed, for example, by magnetron sputtering or evaporation, and its material may be, for example, Al or Al alloy metal as a side wall reflector, and the electrode stack metal may be Ni, Al, Ti, Ni, Pt, Au and other metal materials. The passivation layer 715 is arranged between the top transparent conductive layer 709 and the light-emitting mesa 708, and its function is not only to reduce the current leakage at the side wall, but also to passivate the side wall defects and prevent water, oxygen, etc. from damaging the light-emitting mesa during operation. The passivation layer 715 may be formed by depositing SiO2 material using a CVD process, or may be formed by depositing Al2O3 material using an ALD process. The cathode 711 may be, for example, a common cathode structure, that is, an array of micro-light-emitting diodes are connected to a common cathode.

[0159] The second electrode, here the anode 713, is arranged at the bottom of the light-emitting table 708 to power the anode 713. The anode 713 of each micro-light-emitting diode of the array can be selectively connected to a signal contact (not shown). The common cathode and selective anode connection method can form a passive matrix control method to control the on, off and brightness adjustment of each micro-light-emitting diode. Additional layers, such as the passivation layer 615, the transparent conductive layer 709, the cathode 711, etc. are also provided on the light-emitting table 708 and the anode 713. It should be noted that in other embodiments, the polarity of the first electrode and the second electrode can be interchanged, that is, the cathode 711 and the anode 713 exchange.

[0160] A bottom transparent electrode layer 716, which is located between the bottom of the light-emitting mesa 708 and the reflector layer 717. The bottom transparent conductive layer 716 is configured to electrically connect the second epitaxial layer of the light-emitting mesa 701 to the reflector layer 717 and further electrically connect to the anode 713. The material of the bottom transparent conductive layer 618 is, for example, a metal oxide, such as indium tin oxide ITO, zinc oxide ZnO, etc., and its formation method includes, for example, physical vapor deposition (PVD), chemical vapor deposition (CVD), sol-gel method, solution coating method, etc.

[0161] A reflector layer 717 is arranged at the bottom of the light-emitting mesa 708 and covers the bottom transparent electrode layer 716. The reflector layer 717 is configured to reflect the light from the light-emitting mesa 708 upward to the top light outlet together with the bottom anode 713. In addition, the reflector layer 717 is also configured to electrically connect the bottom transparent conductive layer 716 with the anode 713. The reflector layer 717 has an atomic layer deposition layer on the side facing the light-emitting mesa 708. The atomic layer deposition layer can block the metal from the reflective metal layer to prevent it from diffusing without substantially affecting the reflection of light, for example, preventing it from diffusing through the bottom transparent conductive layer 716 into the light-emitting mesa 708 to affect the light-emitting efficiency of the light-emitting mesa 708. For the specific structure of the reflector layer 717, please refer to Figure 1 and Figure 2 and its description.

[0162] The reflector layer 200 includes an atomic layer deposition layer 201, a reflective metal layer 202, a first barrier layer 203, and a second barrier layer 204 from top to bottom (i.e., from facing the light-emitting mesa 708 to facing away from the light-emitting mesa 708), wherein the upper side of the reflector layer 200 faces the light-emitting mesa or epitaxial layer of the micro-light-emitting diode, and the lower side of the reflector layer 200 faces away from the light-emitting mesa or epitaxial layer of the micro-light-emitting diode or faces the bottom transparent conductive layer.

[0163] For example, the stacked structure of the reflector layer 717 is as follows (in order from close to the light-emitting mesa to far from the light-emitting mesa):

[0164] Atomic layer deposition layer 201, made of nickel, with a thickness of 5 angstroms;

[0165] The reflective metal layer 202 is made of silver and has a thickness of 1000 angstroms;

[0166] The first and second barrier layers 203A and 203B are made of titanium and platinum, respectively, and have thicknesses of 200 and 500 angstroms, respectively;

[0167] The second barrier layer 204 is made of titanium and has a thickness of 200 angstroms.

[0168] In addition, the number of layers of the first barrier layer 203 is three.

[0169] The reflector layer 717 can be formed, for example, by evaporation, sputtering, chemical vapor deposition (CVD), etc., wherein the atomic layer deposition layer 701 of the reflector layer 717 can be formed, for example, by atomic layer deposition.

[0170] A microlens 701 is disposed above the light-emitting mesa 708 to shape the light emitted therefrom, such as converging or collimating. The microlens includes a lens portion 701A and a spacer portion 701B. The lens portion 701A is disposed at the outermost side, i.e., the uppermost side, and is configured to shape the light from the light-emitting mesa 708. The spacer portion 701B is disposed between the lens portion 701A and the light-emitting mesa 708 to adjust the focal position of the lens portion 701A. For example, the focal point of the lens portion 701A can be exactly located in the light-emitting mesa 708 of the micro-LED by adjusting the thickness of the spacer portion 701B and the curvature of the lens portion 701A. The microlenses 701 correspond to the light-emitting mesa 708 one by one. Meanwhile, in this embodiment, there is a gap between adjacent microlenses 701. The bottom of the gap is flush with the top of the light-emitting mesa 708 and is higher than the bottom of the light-emitting mesa 708, and the lens portion 701A is located above the cathode 712. The microlens 701 can be formed by multiple depositions. In the process of forming the microlens, a SiO2 film layer needs to be deposited first, and then ion etching is performed. The microlens is formed on the surface of the top transparent conductive layer 709 at the position corresponding to each light-emitting mesa 708.

[0171] The microlens can be made of a variety of materials that are transparent at the wavelength emitted by a single micro-LED pixel. Examples of transparent materials used for microlenses include polymers, dielectrics, and semiconductors. In some embodiments, the dielectric material includes one or more materials, such as silicon oxide, silicon nitride, silicon carbide, titanium oxide, zirconium oxide, aluminum oxide, etc. In some embodiments, the microlens is made of photoresist. In some embodiments, the shape of the microlens is generally hemispherical. In some embodiments, the central axis of the microlens is aligned with the central axis of a single micro-LED pixel without a lens or the two are the same. It should be understood that a complete display panel includes an array consisting of many single pixels and many microlenses. In addition, there is not necessarily a one-to-one correspondence between the microlens and the pixel light source, and there is not necessarily a one-to-one correspondence between the drive circuit (not shown) and the pixel light source. The pixel light source can also be composed of multiple separate light-emitting elements, for example, a single pixel light-emitting diode connected in parallel. In some embodiments, one microlens can cover several single light-emitting diode pixels without a lens. A single microlens has a positive optical focal length, and its position can reduce the divergence or viewing angle of the light emitted by the corresponding pixel light source. For example, the light beam emitted by the pixel light source originally has a fairly wide divergence angle. In one embodiment, the initial angle of the edge ray of the light beam relative to the vertical axis perpendicular to the substrate is greater than 60°. After the light is refracted by the microlens, the divergence angle of the new edge ray is now reduced. In one embodiment, the reduced angle is less than 30°. The microlenses in the microlens array are generally identical. Examples of microlenses include spherical microlenses, aspherical microlenses, Fresnel microlenses, and cylindrical microlenses.

[0172] The size of each micro-LED chip does not exceed 1 cm, preferably does not exceed 20 microns. The micro-LED structure is formed in the micro-LED chip in an array form, with a resolution of, for example, 720*480, 640*480, 1920*1080, 1280*720, 2K or 4K. The diameter of the micro-LED structure is at the nanometer level, for example, 20nm to 100nm.

[0173] In some embodiments of the present invention, the micro-LED array may include a single layer of micro-LED structures. In some embodiments of the present invention, the micro-LED array may include multiple layers of vertically stacked micro-LED structures.

[0174] In some embodiments of the present invention, the micro-LED array may include blue micro-LEDs. In some embodiments of the present invention, the pitch of the micro-LED array, i.e., the minimum center-to-center distance between the micro-LEDs, may be between about 2 microns and about 50 microns. In some embodiments, the number of pixels on a micro-LED chip may be between thousands and millions.

[0175] Although some embodiments of the present invention have been described in this application document, it will be appreciated by those skilled in the art that these embodiments are merely shown as examples. Those skilled in the art may conceive of numerous variations, alternatives, and improvements under the teachings of the present invention without departing from the scope of the present invention. The appended claims are intended to define the scope of the present invention and thus cover methods and structures within the scope of these claims themselves and their equivalents.

Claims

1. A micro light emitting diode, comprising: Luminous table, emits light; as well as The reflector layer reflects light from the light-emitting mesa, wherein the reflector layer has an atomic layer deposition layer on a side facing the light-emitting mesa.

2. The micro-LED according to claim 1, wherein the upper surface of the light-emitting mesa is larger than the lower surface thereof, and the reflector layer comprises: a side reflector layer covering at least a portion of a side surface of the light-emitting mesa, wherein the side reflector layer has an inclined surface on a side facing the light-emitting mesa to reflect light from the light-emitting mesa upward; as well as The bottom reflector layer covers at least a portion of the bottom surface of the light-emitting mesa, wherein the bottom reflector layer has an atomic layer deposition layer on a side facing the light-emitting mesa. 3 . The micro light emitting diode according to claim 1 , wherein an upper surface of the light emitting mesa is smaller than a lower surface thereof, and the reflector layer covers a bottom surface of the light emitting mesa.

4. The micro-LED according to any one of claims 1 to 3, wherein the reflector layer comprises, starting from a side facing the light-emitting mesa: an atomic layer deposition layer, the material of which is selected from one or more of the following: nickel, platinum, titanium, and tantalum; A reflective metal layer, wherein the material of the reflective metal layer is selected from one or more of the following: silver, aluminum, and gold; A first barrier layer comprising at least first and second barrier layers, wherein the materials of the first and second barrier layers are respectively selected from one or more of the following: platinum, titanium, and tantalum; and The second barrier layer is made of a material selected from one or more of the following: platinum, titanium, and tantalum. The micro light emitting diode according to claim 4 , wherein a material of the second barrier layer is different from a material of the first barrier layer.

6. The micro light emitting diode according to claim 4, wherein: The ALD layer material is nickel; The material of the reflective metal layer is silver; The materials of the first and second barrier layers are titanium and platinum, respectively; and The material of the second barrier layer is titanium.

7. The micro light emitting diode according to claim 5, wherein: The thickness of the ALD layer is 3 to 8 angstroms; The thickness of the reflective metal layer is 800 to 1200 angstroms; The first barrier layer has a thickness of 100 to 300 angstroms, and the second barrier layer has a thickness of 400 to 600 angstroms; and The second barrier layer has a thickness of 100 to 300 angstroms. 8 . The micro light emitting diode according to claim 4 , wherein the reflector layer comprises N first barrier layers and N second barrier layers which are alternately arranged with each other, wherein N is an integer, and N=2 to 5.

9. The micro-light emitting diode according to claim 4, further comprising: The insulating layer includes a recess in which at least a portion of the epitaxial layer is disposed.

10. The micro-light emitting diode according to claim 9, further comprising: A passivation layer is arranged between the side reflector layer and the insulating layer.

11. The micro light emitting diode chip according to claim 9, wherein the light emitting mesa comprises: A first epitaxial layer extending beyond the recess of the insulating layer and electrically contacting the light emitting layer; a light emitting layer in the recess and between the first epitaxial layer and the second epitaxial layer; as well as A second epitaxial layer is in the recess and is in electrical contact with the light emitting layer and the first through-hole contact.

12. The micro light emitting diode according to claim 9, wherein the material of the passivation layer is selected from one or more of the following: Aluminum oxide, silicon oxide, and silicon nitride.

13. The micro-light emitting diode according to claim 1, further comprising: a through-hole contact at the bottom of the epitaxial layer to electrically connect the epitaxial layer to the driving circuit; as well as A buffer layer is etched between the mirror layer and the via contact.

14. The micro-light emitting diode according to claim 13, further comprising: A bottom transparent conductive layer is between the mirror layer and the via contacts to electrically connect the epitaxial layer to the via contacts.

15. A micro light emitting diode chip, comprising: A plurality of light emitting diodes according to claim 1, wherein the light emitting diodes further comprise: a first electrode electrically connected to the through-hole contact portion; a passivation layer between the side reflector layer and the insulating layer; a top transparent conductive layer on and in electrical contact with the first epitaxial layer; and A second electrode, which is on the surface of the top transparent conductive layer; and A driving circuit having a metal layer on its surface, a plurality of through-hole contacts being arranged on the driving circuit, the through-hole contacts being electrically connected to the metal layer, the micro light-emitting diode being connected to the driving circuit via a bottom conductive bonding layer, and each light-emitting mesa corresponding to one of the through-hole contacts, and the light-emitting mesa comprising a first epitaxial layer, a light-emitting layer and a second epitaxial layer deposited in sequence. 16 . The micro light emitting diode chip according to claim 15 , wherein the second electrode is a ring-shaped reflective electrode, which is arranged around the light emitting mesa.

17. The micro light emitting diode chip according to claim 15, wherein the polarity of the second electrode is opposite to that of the first electrode.

18. A micro-light emitting diode chip according to claim 15, wherein the material of the second epitaxial layer is a material layer of a second conductivity type comprising at least two or more elements of Ga, N, As, Al, In, and P, and the first epitaxial layer is a material layer of a first conductivity type comprising at least two or more elements of Ga, N, As, Al, In, and P, wherein the first conductivity type is different from the second conductivity type.

19. The micro light emitting diode chip according to claim 15, wherein the light emitting layer comprises a multi-quantum well layer, wherein the multi-quantum well layer is an InGaN / GaN multi-quantum well layer, an InGaN / AlGaN multi-quantum well layer, an InGaAs / Al GaAs multi-quantum well layer, or an Al Ga InP multi-quantum well layer. 20 . The micro light emitting diode chip according to claim 15 , wherein an electron blocking layer is disposed on a first side of the light emitting layer, wherein the first side refers to a side along which electrons migrate out of the light emitting layer.

21. The micro light emitting diode chip according to claim 15, wherein the material of the metal layer is an alloy of one or more of the following metals: Ni, Al, Ti, Ni, Pt, Au. 22 . The micro light emitting diode chip according to claim 15 , wherein the material of the passivation layer is Si 3 N 4 film, SiO 2 film or Al 2 O 3 film.

23. The micro-LED chip according to claim 15, further comprising a micro-lens, wherein the micro-lens comprises: The lens part, which is on the outermost side; as well as The spacer is between the lens portion and the light emitting mesa.

24. A micro light emitting diode chip, comprising: The upper stack comprises: a first insulating layer accommodating the light emitting mesa and the first via contact; A light-emitting mesa that emits light, wherein the top surface area of ​​the light-emitting mesa is larger than the bottom surface area of ​​the light-emitting mesa; a reflector layer, wherein the reflector layer covers at least a portion of a side surface and / or at least a portion of a bottom surface of the light emitting mesa, and has an atomic layer deposition layer on a side facing the light emitting mesa, wherein the atomic layer deposition layer is configured to block metal diffusion in the reflector layer; and a first through-hole contact portion electrically connected to the bottom of the light-emitting mesa and passing through the first insulating layer; and The lower stack comprises: a second insulating layer accommodating a second through-hole contact; a second through-hole contact passing through the second insulating layer; and The driving back plate is electrically connected to the second via contact, wherein the lower stack is bonded to the upper stack by hybrid bonding, so that the first via contact is bonded to the second via contact, and the first insulating layer is bonded to the second insulating layer.

Images