CN114725276A - Micro-LED discrete device - Google Patents
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
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- H01L33/36—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes
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- H—ELECTRICITY
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Abstract
The invention relates to a Micro-LED discrete device, comprising: a passive backplane having a cathode contact and a plurality of anode contacts disposed therein; the first bonding layer is located on the passive backboard, the light-emitting assembly is bonded with the passive backboard through the first bonding layer and comprises a plurality of light-emitting structures which are arranged in a stacked mode, the lower layer of the light-emitting structures in two adjacent layers of the light-emitting structures extends out in the first direction relative to the upper layer of the light-emitting structures to form a step structure, at least part of an N-type semiconductor layer of the light-emitting structure located at the top layer is exposed, at least part of the N-type semiconductor layer of the rest light-emitting structures is exposed at the step structure, the N-type semiconductor layers exposed in multiple layers are electrically connected with each other, and ohmic contact layers of the light-emitting structures are respectively and electrically connected with the anode contacts in a one-to-one correspondence mode. The device provided by the application can be used for realizing the integrated integration of the three primary colors Micro-LED discrete devices.
Description
Technical Field
The application relates to the technical field of display, in particular to a Micro-LED discrete device.
Background
Compared with the existing Display technologies such as Liquid Crystal Displays (LCDs), Organic Light-Emitting displays (OLEDs), and the like, the Micro Light-Emitting Diode (Micro-LED) Display has many advantages, is generally considered as the core of the next generation Display technology, and has a great application prospect in various fields such as watches, televisions, projection, virtual reality, augmented reality, mixed reality, and the like.
In the Micro-LED field, the colorizing display technology is a great problem, and the mainstream Micro-LED colorizing technology at present comprises the following steps: the realization of the colorized display is mostly based on the construction of a three-primary-color display device with a planar structure, the occupied space is large, and most of the three-primary-color display devices are transferred by single pixels in sequence when a large amount of transfer is carried out, so that the transfer efficiency is low.
Disclosure of Invention
Based on this, there is a need to provide a vertically stacked Micro-LED discrete device that addresses the problems in the prior art.
A Micro-LED discrete device comprising:
a passive backplane having a cathode contact and a plurality of anode contacts disposed therein;
a first bonding layer on a side of the passive backplane proximate to the anode contact;
a light emitting assembly bonded to the passive backplane through the first bonding layer, the light emitting assembly including a plurality of stacked light emitting structures, a lower layer of the light emitting structures in two adjacent layers of the light emitting structures extending in a first direction relative to an upper layer of the light emitting structures to form a step structure, an N-type semiconductor layer of the light emitting structure at a top layer being at least partially exposed and an N-type semiconductor layer of the remaining light emitting structure being at least partially exposed at the step structure, wherein,
the multiple layers of exposed N-type semiconductor layers are electrically connected to the cathode contact, and the ohmic contact layers of the multiple layers of light-emitting structures are electrically connected with the multiple anode contacts in a one-to-one correspondence mode; the light emitting structures have different light emitting colors, and the first direction is perpendicular to the stacking direction of the light emitting structures.
In one embodiment, the light emitting assembly comprises a first light emitting structure, a second bonding layer, a second light emitting structure, a third bonding layer and a third light emitting structure which are arranged in a stacked manner, wherein an ohmic contact layer of the first light emitting structure is positioned on the first bonding layer, and an ohmic contact layer of the second light emitting structure is positioned on the second bonding layer; the ohmic contact layer of the third light emitting structure is on the third bonding layer.
In one embodiment, in the first direction, one end of the first light emitting structure protrudes relative to the second bonding layer to form a first step structure, and one end of the second light emitting structure protrudes relative to the third bonding layer to form a second step structure, wherein at least a portion of the N-type semiconductor layers of the first light emitting structure, the second light emitting structure and the third light emitting structure in the first step structure are interconnected with each other.
In one embodiment, the plurality of anode contacts includes a first anode contact, a second anode contact and a third anode contact, the first bonding layer is connected with the first anode contact in a metal bridging manner, and the second bonding layer is connected with the second anode contact in a metal bridging manner; the third bonding layer is connected with the third anode contact in a metal bridging mode, and each bonding layer is a metal layer.
In one embodiment, the area of the first bonding layer is larger than the area of the first light emitting structure, the area of the second bonding layer is larger than the area of the second light emitting structure, and the area of the third bonding layer is larger than the area of the third light emitting structure, wherein the area is a projected area projected on a geometric plane parallel to the first direction.
In one embodiment, the device further comprises:
a first insulating layer on the light emitting assembly, the first insulating layer having a plurality of open grooves to expose at least a portion of the N-type semiconductor layer of each of the light emitting structures;
the conductive layer is positioned on the first insulating layer, and the conductive columns are positioned in the grooves, wherein the conductive layer and the conductive columns are mutually interconnected, so that the plurality of layers of exposed N-type semiconductor layers are mutually and electrically connected.
In one embodiment, the thicknesses of the first insulating layer covering the corresponding regions of the light emitting devices are all equal.
In one embodiment, the thicknesses of the first insulating layer in the corresponding regions of the stepped structures are different, and the top surface of the first insulating layer is parallel to the passive backplane.
In one embodiment, a cross-section of the stepped structure parallel to the passive backplate is one of square, circular, elliptical, triangular, and polygonal.
In one embodiment, the Micro-LED discrete device further comprises:
a second insulating layer on a side of the passive backplane proximate to the anode contact.
In one embodiment, the passive backplane is one of a printed circuit backplane, a sapphire backplane, or a glass backplane.
In one embodiment, each of the light emitting structures includes: the light-emitting diode comprises a P-type ohmic contact layer, a P-type semiconductor layer, a quantum well layer, an N-type semiconductor layer and a buffer layer which are sequentially stacked, wherein doping parameters in the quantum well layer in each light-emitting structure are different.
According to the Micro-LED discrete device, the plurality of anode contacts are arranged in the passive back plate, the light emitting assemblies comprising the plurality of light emitting structures which are arranged in a stacked mode are formed on the passive back plate, the plurality of light emitting structures with different light emitting colors are vertically stacked and form the plurality of stepped structures, the N-shaped semiconductor layers of the light emitting structures are partially exposed to realize common cathode connection, the ohmic contact layers of the plurality of light emitting structures are electrically connected with the plurality of anode contacts in a one-to-one correspondence mode, the vertical stacking connection of the plurality of light emitting structures can be realized, the space utilization rate of the device is improved, the size of the Micro-LED discrete device is favorably reduced, and the effect of integration of the plurality of light emitting structures is achieved. Furthermore, when the method is applied to mass transfer, the transfer process is simplified, and the transfer efficiency is improved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a cross-sectional view of a Micro-LED discrete device provided in an embodiment;
FIG. 2 is a top view of a substrate provided in an embodiment;
FIG. 3 is a cross-sectional view of a substrate provided in one embodiment;
fig. 4 is an internal structural view of a light emitting structure provided in an embodiment;
FIG. 5 is a block diagram of Micro-LED discrete devices provided in an embodiment;
FIG. 6 is a block diagram of Micro-LED discrete devices provided in an embodiment;
FIG. 7 is a cross-sectional view of a Micro-LED discrete device provided in an embodiment;
fig. 8 is a cross-sectional view of a Micro-LED discrete device provided in an embodiment;
FIG. 9 is a cross-sectional view of a Micro-LED discrete device provided in an embodiment;
FIG. 10 is a block diagram of a substrate provided in one embodiment;
fig. 11 is a top view of a Micro-LED discrete device provided in another embodiment.
Description of reference numerals:
10-substrate, 100-passive backplane, 101-first anode contact, 102-second anode contact, 103-third anode contact, 104-second insulating layer, 105-cathode contact, 20-first bonding layer, 30-light emitting component, 301-first light emitting structure, 3011-P-type ohmic contact layer, 3012-P-type semiconductor layer, 3013-quantum well layer, 3014-said N-type semiconductor layer, 3015-buffer layer, 3016-substrate layer, 302-second light emitting structure, 303-third light emitting structure, 304-second bonding layer, 305-third bonding layer, 40-first insulating layer, 50-conductive layer, 60-conductive pillar, 70-transparent electrode.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Embodiments of the present application are set forth in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that when an electrode or layer is referred to as being "on," "adjacent to," "connected to" other electrodes or layers, it can be directly on, adjacent to, connected to the other electrodes or layers, or intervening electrodes or layers may be present. In contrast, when an electrode is referred to as being "directly on", "directly adjacent to", or "directly connected to" other electrodes or layers, there are no intervening electrodes or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various electrodes, structures, films, regions, layers, doping types, these electrodes, structures, films, layers, doping types, and/or portions should not be limited by these terms. These terms are only used to distinguish one electrode, structure, region, layer, doping type or section from another electrode, structure, region, layer, doping type or section. Thus, the first anode contact, first light emitting structure, first bonding layer discussed below may be represented as a second anode contact, second light emitting structure, second bonding layer without departing from the teachings of the present invention.
Spatial relational terms, such as "under," "below," "under," "over," and the like may be used herein to describe one electrode or feature's relationship to another electrode or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, electrodes or features described as "below" or "beneath" other electrodes or features would then be oriented "above" the other electrodes or features. Thus, the exemplary terms "under" and "under" can encompass both an orientation of above and below. In addition, the device may also include additional orientations (e.g., rotated 90 degrees or other orientations) and the spatial descriptors used herein interpreted accordingly.
As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Also, in this specification, the term "and/or" includes any and all combinations of the associated listed items.
Embodiments of the invention are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments of the invention, such that variations from the shapes shown are to be expected, for example, due to manufacturing techniques and/or tolerances. Thus, embodiments of the invention should not be limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing techniques. The regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present invention.
Referring to fig. 1, the present invention provides a Micro-LED discrete device, which includes a passive backplane 100, a first bonding layer 20, and a light emitting assembly 30.
A passive backplane 100, the passive backplane 100 having a cathode contact 105 and a plurality of anode contacts disposed therein.
In the embodiment of the present application, the description will be made taking the case where the anode contacts include the first anode contact 101, the second anode contact 102, and the third anode contact 103 as an example. It should be noted that the first anode contact 101, the second anode contact 102, and the second anode contact 103 are arranged in a group, that is, the anode contact group includes the first anode contact 101, the second anode contact 102, and the second anode contact 103. An anode contact group is correspondingly arranged on one Micro-LED discrete device. In this embodiment of the application, when there are a plurality of Micro-LED discrete devices, a plurality of anode contact sets may be further disposed in the passive backplane 100, where the number of the anode contact sets may be set according to actual requirements, and is not limited herein.
The passive backplane 100 is a backplane without a driver, such as a printed circuit backplane, a sapphire backplane, and a glass backplane. As shown in fig. 2 and 3, the cathode contact 105 and the plurality of anode contacts 101, 102, 103 in the passive backplane may be "i" shaped metal pads penetrating through the passive backplane 100 to realize electrical interconnection between the upper surface and the lower surface of the passive backplane 100.
In addition, the light emitting direction of each light emitting structure in the Micro-LED device can be adaptively adjusted according to whether the back plate 100 is transparent or not. For example, when the passive back-plate 100 has light transmittance, the light emitting direction of each light emitting structure may be directed toward the passive back-plate 100; when the passive back-plate 100 does not have light transmittance, the light emitting direction of each light emitting structure may be away from the passive back-plate 100. In the embodiment of the present application, the passive backplane 100 is taken as the printed circuit backplane, and the light emitting direction of each light emitting structure deviates from the printed circuit backplane.
A first bonding layer 20 on a side of the passive backplane 100 adjacent to the anode contact. The first bonding layer 20 may be a metal thin film, such as a thin film made of one or more of gold, nickel, tin, indium, aluminum, copper, silver, and alloys thereof. The first bonding layer 20 has a bonding function, and may have the capabilities of conducting, reflecting, dissipating heat, and the like, and the first bonding layer 20 is disposed on the whole surface.
A light emitting component 30 bonded to the passive backplane 100 through the first bonding layer 20. The light emitting assembly 30 includes a plurality of light emitting structures disposed in a stack. The light-emitting structures have different light-emitting colors and are one of three primary colors. The light-emitting structure of the next layer in the two adjacent layers of light-emitting structures extends out in the first direction relative to the light-emitting structure of the previous layer to form a step structure, the N-type semiconductor layer of the light-emitting structure at the top layer is at least partially exposed, and the N-type semiconductor layer of the rest light-emitting structure is at least partially exposed at the step structure. The uppermost layer of each light emitting structure is an N-type semiconductor, the lowermost layer of each light emitting structure is an ohmic contact layer, and the light emitting structures are vertically stacked to form a step structure as shown in fig. 1. Wherein the plurality of exposed N-type semiconductor layers are electrically connected with each other. Illustratively, the multiple exposed N-type semiconductor layers are electrically connected to each other by metal bridging to the cathode contact to achieve a common cathode connection. And ohmic contact layers of the multiple layers of light-emitting structures are respectively and correspondingly electrically connected with the anode contacts one by one, so that the anode connection of the device is realized. Wherein the first direction is perpendicular to a stacking direction of the light emitting structures.
In this embodiment, through set up a plurality of anode contacts in the passive backplate to form the light-emitting component who includes a plurality of range upon range of light-emitting structure that sets up on the passive backplate, and a plurality of light-emitting structure that have different luminous colour pile up perpendicularly and form a plurality of stair structure, make each light-emitting structure's N shape semiconductor layer all exposes in order to realize the common cathode and connect, multilayer light-emitting structure's ohmic contact layer respectively with a plurality of anode contact one-to-one electricity is connected, can realize the independent control to each light-emitting structure, has improved the space utilization in the device preparation process, is favorable to reducing the size of Micro-LED discrete device, has reached the integrative integrated effect of a plurality of light-emitting structure. Furthermore, when the method is applied to mass transfer, the transfer process is simplified, and the transfer efficiency is improved.
In one embodiment, the light emitting structure may be a plurality of different wafers, and the wafers may be first, second, and third generation compound semiconductor materials or semi-finished and finished devices, including optoelectronic devices, laser type devices, micro-machines, power electronics, and power rf devices, and may also be low micro-material devices, such as quantum dots. Specifically, taking the first light emitting structure 301 as an example, as shown in fig. 4, the wafer includes a P-type ohmic contact layer 3011, a P-type semiconductor layer 3012, a quantum well layer 3013, the N-type semiconductor layer 3014, a buffer layer 3015, and a substrate layer 3016, which are sequentially stacked. Wherein doping parameters in the quantum well layers in each of the light emitting structures are different. And the light emitting structure emits light with different wavelengths and correspondingly emits light with different colors by changing the doping parameters of the quantum well layer. When the wafer is bonded to the passive backplane 100, the P-type ohmic contact layer 3011 of the wafer is connected to the passive backplane 100 through the first bonding layer 20.
In this embodiment, by selecting a wafer as the light emitting structure, doping of different parameters can be performed on a quantum well layer in the light emitting structure, so as to emit light of different colors.
In one embodiment, with continued reference to fig. 1, the light emitting assembly 30 includes a first light emitting structure 301, a second bonding layer 304, a second light emitting structure 302, a third bonding layer 305, and a third light emitting structure 303 stacked on top of each other.
The first light emitting structure 301 is connected to the passive backplane 100 through the first bonding layer 20, the second light emitting structure 302 is connected to the first light emitting structure 301 through the second bonding layer 304, the third light emitting structure 303 is connected to the second light emitting structure 302 through the third bonding layer 305, and the first light emitting structure 301, the second light emitting structure 302, and the third light emitting structure 303 are sequentially stacked.
Considering from the light emitting principle, the light emitting wavelength of each of the light emitting structures is gradually shortened from bottom to top, and preferably, the light emitting color of the first light emitting structure 301 may be red (with a wavelength of 620nm), the light emitting color of the second light emitting structure 302 may be green (with a wavelength of 525nm), and the light emitting color of the third light emitting structure 303 may be blue (with a wavelength of 460 nm). In addition, when the structure is applied to non-Micro-LED display technology, the structure can also be integrated by wafer arrangement and bonding of the same wavelength.
The structure that the first light emitting structure 301 is bonded to the passive backplane 100 through the first bonding layer 20 is shown in fig. 5, and after bonding is completed, the wafer substrate layer 3016 in the light emitting structure needs to be removed. For example, when the substrate layer 3016 is a sapphire substrate, it can be removed by laser lift-off, and when the substrate layer 3016 is a silicon substrate, a silicon carbide substrate, a gallium nitride substrate, a gallium arsenide substrate, or the like, it can be removed by chemical liquid removal or polishing, and if necessary, the buffer layer 3015 can be thinned.
The first light emitting structure 301, the second bonding layer 304, the second light emitting structure 302, the third bonding layer 305, and the third light emitting structure 303 are sequentially bonded to form a stacked structure as shown in fig. 6. Because alignment bonding is not adopted, the nano-scale alignment precision can be realized by utilizing a semiconductor process, and the method has advantages for preparing ultra-small-sized pixels. Because the light-emitting three primary colors are integrated on a single Micro-LED device, when the Micro-LED device is applied to mass transfer, the three primary colors can be transferred together, and the transfer efficiency is improved.
The P-type ohmic contact layer of each light-emitting structure is positioned on the lowest layer of the light-emitting structure and is in contact with the corresponding bonding layer below the light-emitting structure. Specifically, the P-type ohmic contact layer of the first light emitting structure 301 is located on the first bonding layer 20, and forms a contact with the first bonding layer 20; the P-type ohmic contact layer of the second light emitting structure 302 is located on the second bonding layer 304, and forms a contact with the second bonding layer 304; the P-type ohmic contact layer of the third light emitting structure 303 is located on the third bonding layer 305, and forms a contact with the third bonding layer 305, so as to facilitate subsequent anode connection.
In one embodiment, a dielectric insulating layer may be disposed between the second bonding layer 304 and the first light emitting structure 301, and between the third bonding layer 305 and the second light emitting structure 302, respectively, and the insulating layer may be a dielectric layer such as silicon oxide.
In this embodiment, by providing a plurality of light emitting structures and a plurality of bonding layers, the plurality of light emitting structures can be connected by the bonding layer, and the plurality of bonding layers are respectively connected to the ohmic contact layers of the light emitting structures, which is beneficial to connection of anodes of the light emitting structures.
In one embodiment, please refer to fig. 1 and 7, the first direction is a direction parallel to the X-axis or the Y-axis. In the first direction, one end of the first light emitting structure 301 protrudes relative to the second bonding layer 304 to form a first step structure a, and one end of the second light emitting structure 302 protrudes relative to the third bonding layer 305 to form a second step structure B, wherein at least a portion of the N-type semiconductor layers of the first light emitting structure 301 located in the first step structure a, the second light emitting structure 302 located in the second step structure B, and the third light emitting structure 303 are interconnected with each other.
After the stacked structure is formed, a stepped structure as shown in fig. 1 and 7 may be formed by etching. Wherein fig. 1 is a cross-sectional view of the Micro-LED discrete device in a first plane parallel to the X-O-Z plane, and fig. 7 is a cross-sectional view of the Micro-LED discrete device in a second plane parallel to the Y-O-Z plane.
The N-type semiconductor layer of the first light emitting structure 301 located at the first step structure a is exposed, the N-type semiconductor layer of the second light emitting structure 302 located at the second step structure B is exposed, and the uppermost N-type semiconductor layer of the third light emitting structure 303 is exposed. Wherein a cross section of each of the stepped structures parallel to the passive backplate 100 is one of square, circular, oval, triangular, and polygonal. The present application is illustrated with the cross-section of the stair-step structure parallel to the passive backplate 100 being square.
In this embodiment, the stacked devices are etched to form the stepped structure, so that the N-type semiconductor of each light-emitting structure is exposed, which is beneficial to realizing common cathode connection of each light-emitting structure.
In one embodiment, the plurality of anode contacts includes a first anode contact 101, a second anode contact 102, and a third anode contact 103, the first bonding layer 20 is connected with the first anode contact 101 by metal bridging, and the second bonding layer 304 is connected with the second anode contact 102 by metal bridging; the third bonding layer 305 is connected to the third anode contact 103 in a metal bridging manner, wherein each bonding layer is a metal layer.
Specifically, taking the first light emitting structure 301 as an example, referring to fig. 8, the P-type ohmic contact layer of the first light emitting structure 301 is electrically connected to the first bonding layer 20, and then a conductive layer 50 is formed to connect the first bonding layer 20 and the first anode contact 101 in a metal bridging manner. Also, the P-type ohmic contact layer of the second light emitting structure 302 and the second anode contact 102 may be connected by means of metal bridging, and the P-type ohmic contact layer of the third light emitting structure 303 and the third anode contact 103 may be connected by means of metal bridging. Each bonding layer is a metal layer, such as one or more of gold, nickel, tin, indium, aluminum, copper, silver, and alloys thereof, and has not only a bonding function, but also conductivity, reflection, heat dissipation, and non-light-transmission properties.
In one embodiment, the area of the first bonding layer 20 is larger than that of the first light emitting structure 301, the area of the second bonding layer 304 is larger than that of the second light emitting structure 302, and the area of the third bonding layer 305 is larger than that of the third light emitting structure 303, wherein the area is a projected area projected on a geometric plane parallel to the first direction.
On a plane passing through the first direction and parallel to the passive backplane 100, a projected area of the first bonding layer 20 is larger than a projected area of the first light emitting structure 301, a projected area of the second bonding layer 304 is larger than a projected area of the second light emitting structure 302, and a projected area of the third bonding layer 305 is larger than a projected area of the third light emitting structure 303. The metal of each bonding layer is opaque, so that the area of each bonding layer is larger than the projection area of each corresponding light-emitting structure, and crosstalk caused by the fact that light of the short-wave light-emitting structure located above excites the light-emitting structure below can be avoided.
In one embodiment, referring to fig. 8 and 9, the device further includes a first insulating layer 40 on the light emitting element 30, a conductive layer 50 on the first insulating layer 40, a groove opened in the first insulating layer 40 and the conductive layer 50, and a conductive pillar 60 in the groove.
The first insulating layer 40 is used for insulating the device to prevent leakage or crosstalk between the electrodes, the insulating material of the first insulating layer 40 may be an inorganic dielectric material such as silicon oxide or silicon nitride, or an organic dielectric material such as polyimide, and the first insulating layer 40 may be deposited by a method such as chemical vapor deposition, atomic layer deposition, or sputtering. The open grooves are used for exposing at least part of the N-type semiconductor layer of each light emitting structure, so that each N-type semiconductor layer is connected with the conductive column 60 located in the open groove and further connected with the conductive layer 50, thereby realizing common cathode connection.
In this embodiment, the insulating layer covers the surface of the light emitting structure, and the insulating layer is provided with the open groove for forming the conductive pillar, so that the N-type semiconductor of each light emitting structure can be connected with the conductive layer through the conductive pillar, thereby achieving the effect of cathode interconnection.
In one embodiment, the thicknesses of the first insulating layer 40 covering the corresponding regions of the light emitting structure are all equal.
Specifically, with reference to fig. 8, on the surface of each light emitting structure, the thickness covered by the first insulating layer 40 is equal, and the first insulating layer 40 at each step structure is provided with a slot to form a conductive pillar 60, and the conductive pillar 60 is connected to the conductive layer 50 on the surface of the first insulating layer 40 to implement cathode interconnection.
In one embodiment, with reference to fig. 9, the thicknesses of the first insulating layer 40 in the corresponding regions of the step structures are not equal, and the top surface of the first insulating layer 40 is parallel to the passive backplane 100.
Specifically, the thicknesses of the first insulating layer 40 in the corresponding regions of the stepped structures are not equal, and the top surface of the first insulating layer 40 is a smooth surface and is parallel to the passive backplane 100. The first insulating layers 40 are disposed at intervals to reserve a space to form the conductive pillar 60. After the conductive column 60 is filled with the conductive electrode, a planarization process is performed at the topmost end by using methods such as etching, grinding, polishing, etc. to form a flat top surface, and a transparent electrode 70 is formed on the flat top surface, where the transparent electrode 70 may be one or more layers of indium tin oxide, zinc oxide, indium gallium zinc oxide, silver, etc., and the transparent electrode may be deposited by using methods such as sputtering, evaporation, electroplating, chemical plating, etc.
In this embodiment, the first insulating layers are arranged at intervals, a space is reserved between the first insulating layers to form the conductive pillars, and the transparent electrodes are formed at the top ends of the first insulating layers, so that the N-type semiconductors of the light emitting structures can be connected with the transparent electrodes through the conductive pillars, thereby achieving the purpose of light emission and forming pixel isolation at the same time, and preventing crosstalk between pixels.
In one embodiment, as shown in fig. 10, the Micro-LED discrete device further comprises a second insulating layer 104, wherein the second insulating layer 104 is located on the upper layer of the passive backplane 100. The second insulating layer 104 is prepared on the passive backplane 100 to form the substrate 10 of the Micro-LED discrete device.
In one embodiment, when the passive backplane 100 is a printed circuit backplane, the N-type semiconductor of each light emitting structure is connected to the cathode contact 105 through the conductive layer 50, the P-type ohmic contact layer of each light emitting structure is connected to the anode contact through the conductive layer 50 in a one-to-one correspondence, and the light emitting structures are stacked in sequence to form a Micro-LED discrete device structure as shown in fig. 11.
The Micro-LED discrete device prepared on the basis of the printed circuit backboard has large Pixel pitch, can obtain a passive single colorized Pixel after cutting, is suitable for a huge transfer technical route, mainly aims at low Pixel density (PPI) application and large screen application, and can be applied to the display fields of televisions, watches and the like.
In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features of the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (11)
1. A Micro-LED discrete device, comprising:
a passive backplane having a cathode contact and a plurality of anode contacts disposed therein;
a first bonding layer on a side of the passive backplane proximate to the anode contact;
a light emitting assembly bonded to the passive backplane through the first bonding layer, the light emitting assembly including a plurality of stacked light emitting structures, a lower layer of the light emitting structures in two adjacent layers of the light emitting structures extending in a first direction relative to an upper layer of the light emitting structures to form a step structure, an N-type semiconductor layer of the light emitting structure at a top layer being at least partially exposed and an N-type semiconductor layer of the remaining light emitting structure being at least partially exposed at the step structure, wherein,
the multiple layers of exposed N-type semiconductor layers are electrically connected to the cathode contact, and the ohmic contact layers of the multiple layers of light-emitting structures are electrically connected with the multiple anode contacts in a one-to-one correspondence mode; the light emitting structures have different light emitting colors, and the first direction is perpendicular to the stacking direction of the light emitting structures.
2. A Micro-LED discrete device as set forth in claim 1, wherein the light emitting assembly includes a first light emitting structure, a second bonding layer, a second light emitting structure, a third bonding layer, and a third light emitting structure in a stacked arrangement, wherein the ohmic contact layer of the first light emitting structure is on the first bonding layer and the ohmic contact layer of the second light emitting structure is on the second bonding layer; the ohmic contact layer of the third light emitting structure is on the third bonding layer.
3. A Micro-LED discrete device as recited in claim 2, wherein, in the first direction, an end of the first light emitting structure extends relative to the second bonding layer to form a first stepped structure, and an end of the second light emitting structure extends relative to the third bonding layer to form a second stepped structure, wherein at least a portion of the N-type semiconductor layers of the first light emitting structure, the second light emitting structure and the third light emitting structure are interconnected.
4. A Micro-LED discrete device as set forth in claim 3, wherein the plurality of anode contacts includes a first anode contact, a second anode contact, and a third anode contact, the first bonding layer being connected to the first anode contact by a metal bridge, the second bonding layer being connected to the second anode contact by a metal bridge; the third bonding layer is connected with the third anode contact in a metal bridging mode, and each bonding layer is a metal layer.
5. A Micro-LED discrete device as claimed in claim 4, wherein the first bonding layer has an area greater than an area of the first light emitting structure, the second bonding layer has an area greater than an area of the second light emitting structure, and the third bonding layer has an area greater than an area of the third light emitting structure, wherein the area is a projected area projected onto a geometric plane parallel to the first direction.
6. A Micro-LED discrete device according to claim 1, wherein the device further comprises:
a first insulating layer on the light emitting assembly, the first insulating layer having a plurality of open grooves to expose at least a portion of the N-type semiconductor layer of each of the light emitting structures;
the conductive layer is positioned on the first insulating layer, and the conductive columns are positioned in the grooves, wherein the conductive layer and the conductive columns are mutually interconnected, so that the plurality of layers of exposed N-type semiconductor layers are mutually and electrically connected.
7. A Micro-LED discrete device as set forth in claim 6, wherein the first insulating layer covers each of the light emitting structures at corresponding areas with equal thickness.
8. A Micro-LED discrete device as claimed in claim 6, wherein the first insulating layer has a thickness in the respective regions of the stepped structures that is not equal, and wherein a top surface of the first insulating layer is disposed parallel to the passive backplane.
9. A Micro-LED discrete device as set forth in claim 1, wherein the cross-section of the stepped structure parallel to the passive backplane is one of square, circular, oval, triangular, and polygonal.
10. A Micro-LED discrete device as set forth in claim 1, further comprising:
a second insulating layer between the passive backplane and the first bonding layer.
11. A Micro-LED discrete device as recited in claim 10, wherein the passive backplane is one of a printed circuit backplane, a sapphire backplane, or a glass backplane.
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