CN217361616U - Thin film LED chip with vertical structure and micro LED array - Google Patents
Thin film LED chip with vertical structure and micro LED array Download PDFInfo
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- CN217361616U CN217361616U CN202220238762.5U CN202220238762U CN217361616U CN 217361616 U CN217361616 U CN 217361616U CN 202220238762 U CN202220238762 U CN 202220238762U CN 217361616 U CN217361616 U CN 217361616U
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Abstract
The utility model provides a vertical structure's film LED chip, include: the epitaxial light-emitting structure is provided with a first main surface and a second main surface which are opposite, and comprises an N-type epitaxial layer, a light-emitting layer and a P-type epitaxial layer which are sequentially stacked, and the epitaxial light-emitting structure is provided with a first step structure penetrating to the surface of the N-type epitaxial layer; the N electrode is arranged on the first step structure of the N-type epitaxial layer and comprises a main body part and an extension part, the N electrode is electrically contacted with the upper surface of the first step structure through the main body part, and the extension part is formed around the side wall of the N-type epitaxial layer; and a P-electrode provided on the first main surface of the epitaxial light-emitting structure. The utility model also provides a miniature LED array. The thin film LED chip can solve the problems that the current spreading uniformity of the peripheral edge in the existing chip structure is poor, the current spreading uniformity and the reflection effective area of the chip are improved, and the light emitting efficiency of the chip is improved to the greatest extent.
Description
Technical Field
The utility model belongs to semiconductor device and manufacturing field especially relate to a vertical structure's film LED chip.
Background
The Light Emitting Diode (LED) has the advantages of small volume, high efficiency, long service life and the like, and is widely applied to the fields of traffic indication, outdoor full color display and the like. In particular, the semiconductor solid-state lighting can be realized by using high-power light-emitting diodes, which has led to the revolution of the human lighting history, and thus has gradually become a research hotspot in the field of electronics at present.
The existing LED chips can be classified into: flip chip structure, vertical chip structure and face up chip structure. In the vertical LED chip structure, two electrodes are positioned at the upper end and the lower end of the epitaxial layer, and the current distribution in the chip structure is uniform, the light-emitting area is large and the brightness is high. However, the manufacturing process of the vertical thin film LED chip is relatively complicated and requires high technology, resulting in low yield of the chip. As LED chip sizes continue to shrink, the difficulty and cost of scale-up production of thin film chips is further increased. In addition, the light side leakage of the existing LED structure is also serious, so that the light emitting efficiency is reduced.
Therefore, it is an urgent need to solve the above-mentioned problems by those skilled in the art to provide an improved structure of a vertical thin film LED chip.
SUMMERY OF THE UTILITY MODEL
In view of the above shortcomings of the prior art, an object of the present invention is to provide a thin film LED chip with a vertical structure, for solving the problems in the prior art that the current spreading effect of the local area of the thin film chip is still relatively poor, especially the current at the peripheral edge of the LED chip is not uniform, the chip leakage current and the manufacturing process are complicated, and the yield and the reliability need to be improved.
To achieve the above and other related objects, the present invention provides a thin film LED chip of a vertical structure, which includes: the epitaxial light-emitting structure is provided with a first main surface and a second main surface which are opposite, and comprises an N-type epitaxial layer, a light-emitting layer and a P-type epitaxial layer which are sequentially stacked, and the epitaxial light-emitting structure is provided with a first step structure penetrating through the surface of the N-type epitaxial layer; the electrode structure comprises an N electrode, the N electrode is arranged on a first step structure of the N-type epitaxial layer and comprises a main body part and an extension part, the N electrode is in electrical contact with the upper surface of the first step structure through the main body part, and the extension part is formed around the side wall of the N-type epitaxial layer; and the P electrode is arranged on the first main surface of the epitaxial light-emitting structure, and is formed into a reflecting electrode so that the thin film LED chip has an N-surface light-emitting structure.
Optionally, the epitaxial light emitting structure further includes an N-side ohmic contact layer covering an upper surface and a sidewall of the first step structure, and the first step structure is formed around the epitaxial light emitting structure.
Optionally, the N electrode is disposed on the N-side ohmic contact layer, and the main portion and the extending portion of the N electrode are integrally formed in a ring shape by the first step structure.
Optionally, the N-type epitaxial layer includes an intrinsic epitaxial portion and an N-type doped portion located between the intrinsic epitaxial portion and the light emitting layer, and the N-electrode and the main body portion form an electrical contact with the N-type doped portion disposed on the upper surface of the first step structure.
Optionally, the epitaxial light emitting structure further includes a P-side ohmic contact layer disposed on a portion of the surface of the P-type epitaxial layer to form a second step structure.
Optionally, the P electrode includes a first reflective layer, the second reflective layer is disposed on the P-side ohmic contact layer, and the second reflective layer includes a metal reflective layer having a multilayer structure.
Optionally, the N electrode includes a second reflective layer, and the first reflective layer includes one of a metal reflective layer or a metal dielectric composite reflective layer.
Optionally, the thin film LED chip further includes a passivation layer disposed on the sidewall of the epitaxial light emitting structure and covering the second step structure, and the passivation layer includes SiO 2 Layer, Si 3 N 4 Layer, SiON layer, Al 2 O 3 Layer or Al 2 O 3 The laminated layer of the layer and the AlN layer, or the composite layer of the inorganic medium layer and polyimide or benzocyclobutene.
The utility model also provides a miniature LED array, miniature LED array includes: the light-emitting device comprises at least one first light-emitting unit and a plurality of second light-emitting units, wherein the first light-emitting unit and the second light-emitting units are uniformly arranged on a conductive substrate to form a light-emitting unit array, and each light-emitting unit in the light-emitting unit array is the thin film LED chip with the vertical structure; and the common electrode is arranged on the second main surface of the light-emitting epitaxial structure and is electrically connected with the extension part of the N electrode.
Optionally, the first light emitting unit includes a pad on the second main surface of the epitaxial light emitting structure and a current blocking layer on the first main surface and the sidewall of the epitaxial light emitting structure, and the common electrode is electrically connected to an external lead through the pad.
Optionally, the diffusion barrier layer of each light emitting unit is bonded to an electrode on the conductive substrate through a metal bonding layer disposed between the diffusion barrier layer and the conductive substrate.
Optionally, an insulating gap is disposed between adjacent light emitting cells, and the insulating gap is filled with an insulating material.
As described above, the utility model discloses a vertical structure's thin film LED chip and miniature LED array has following beneficial effect:
1) in the thin film LED chip with the vertical structure, the N electrode comprises the main body part and the extension part, the N electrode is electrically contacted with the upper surface of the electrode step through the main body part, and the extension part is formed around the side wall of the electrode step, so that the current injection uniformity is improved, the reduction of the chip resistance is facilitated, and the light intensity is improved;
2) in the thin film LED chip with the vertical structure, the metal medium composite reflecting layer or the metal reflecting layer is arranged on the side wall of the electrode step by surrounding the electrode step of the epitaxial light-emitting structure, so that the light-emitting efficiency of the N surface can be greatly improved by obviously improving the effective area of reflection, the external quantum efficiency of the chip is improved, and the high light efficiency can be achieved;
3) in the micro LED array, the surface of the exposed epitaxial light-emitting structure of each chip is provided with the passivation layer, and the adjacent chips are provided with the insulation gaps, so that the electric leakage of the chips can be obviously reduced, and the photoelectric performance of the chips can be improved;
4) the utility model discloses an among the miniature LED array, adopt the miniaturized array of chip, can set up insulating clearance in adjacent chip interval region to can promote the stability and the reliability of chip.
Drawings
Fig. 1 is a schematic cross-sectional view of a vertical-structure thin-film LED chip according to a first embodiment of the present invention.
Fig. 2 is a flowchart illustrating a method for manufacturing a micro LED array according to a second embodiment of the present invention.
Fig. 3 to 11 show steps 1) to 7) of the method for manufacturing a micro LED array according to the second embodiment of the present invention, wherein fig. 3B shows a top view of the structure shown in fig. 3A, fig. 5B shows a top view of the structure obtained by the step shown in fig. 5A, fig. 7B shows a top view of the structure obtained by the step shown in fig. 7A, fig. 8B shows a top view of the structure obtained by the step shown in fig. 8A, fig. 9B shows a top view of the structure obtained by the step shown in fig. 9A, fig. 10B shows a top view of the structure obtained by the step shown in fig. 10A, and fig. 11B shows a top view of the structure obtained by the step shown in fig. 11A.
Description of component reference numerals
100 Al 2 O 3 Substrate
200 epitaxial light emitting structure
200a first main surface
200b second main surface
201N type GaN layer
202 light-emitting layer
203P type GaN layer
211 first step structure
213 second step structure
300 micro LED array
310 first light-emitting unit
320 second light emitting unit
402 passivation layer
501 diffusion barrier layer
601 metal bonding layer
602 conductive substrate
701 Current Barrier layer
710 common electrode
720 welding plate
801P electrode
802N electrode
802a body portion
802b extension
812 insulation gap
Detailed Description
The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will be readily apparent to those skilled in the art from the disclosure herein. The present invention can be implemented or applied by other different specific embodiments, and various details in the present specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.
As used herein, although the terms "first," "second," "third," etc. may describe various elements, components, regions, layers and/or sections, none of them is limited by these terms. These terms are only used to distinguish one element, component, region, material, layer or section from another element, component, region, material, layer or section without prior distinction.
Also, the terms "upper", "lower", "above", "below", "middle" and "a" are used herein for the sake of clarity only, and are not intended to limit the scope of the present invention, and the relative relationship between the terms and the corresponding parts should be changed or adjusted without substantial change in the technical content. Further, in the context of this application, a structure described as having a first feature "above" a second feature may include embodiments where the first and second features are formed in direct contact, and may also include embodiments where additional features are formed between the first and second features, such that the first and second features may not be in direct contact.
Please refer to fig. 1-11. It should be noted that the drawings provided in the present embodiment are only schematic and illustrative of the basic idea of the present invention, and although the drawings only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation, the form, quantity and proportion of the components in actual implementation may be changed at will, and the layout of the components may be more complicated.
Example one
The present embodiment provides a vertical-structured thin film LED chip, which may include an epitaxial light emitting structure, an electrode structure, and a reflective layer, and which is a GaN-based LED chip, an AlGaInP-based LED chip, and a GaAs-based LED chip, but is not meant to limit the chip type of the present invention thereto. Hereinafter, the thin film LED chip will be described in detail by taking a GaN-based LED chip as an example.
Referring to fig. 1, the epitaxial light emitting structure 200 has first and second main surfaces 200a and 200b opposite to each other, and includes an N-type GaN layer 201, a light emitting layer 202, and a P-type GaN layer 203 stacked in this order. The N-type GaN layer 201 may be heteroepitaxially grown from a growth substrate. For example, the growth substrate is Al 2 O 3 A substrate. The light emitting layer 202 is on the N-type GaN layer 201, and the P-type GaN layer 203 is on the light emitting layer. As an example, the N-type GaN layer 201 includes an intrinsic epitaxial portion epitaxially grown from a growth substrate and an N-type doped portion between the intrinsic epitaxial portion and the light emitting layer 202. The N-type doped portion includes an upper section having a first lateral dimension and a lower section having a second lateral dimension, the first lateral dimension being less than the second lateral dimension. The epitaxial light emitting structure 200 may have a first step structure 211 penetrating to the surface of the N-type GaN layer, and the upper surface of the first step structure 211 is N-type doped GaN material, so that the N-electrode 802 is mainly electrically contacted by the main body portion 802a and the N-type doped portion, or the N-electrode 802 is almost completely electrically contacted by the main body portion 802a and the N-type doped portion on the upper surface of the first step structure 211.
In this embodiment, the first step structure 211 penetrates through the surface of the N-type GaN layer, and the main portion 802a and the extension portion 802b of the N-electrode are integrally formed in a ring shape by the first step structure.
The thin film LED chip further comprises an electrode structure, wherein the electrode structure comprises a P electrode 801 and an N electrode 802. The P-electrode 801 is disposed on the first main surface 200a of the epitaxial light emitting structure, and the P-electrode may be formed as a reflective electrode so that the thin film LED chip has a P-surface light emitting structure. As an example, the P electrode 801 may include a metal reflective layer of a multi-layer structure, such as a Ni/Ag mirror. The N electrode 802 is disposed on the first step structure 211 of the N-type GaN layer. The N-electrode 802 includes a main body portion 802a through which the N-electrode makes electrical contact with the upper surface of the first stepped structure 211, and an extension portion 802b formed around the sidewall of the N-type GaN layer 201.
In this embodiment, the epitaxial light emitting structure 200 further includes a P-side ohmic contact layer (not shown) disposed on a portion of the surface of the P-type GaN layer to form the second step structure 213, the P-side ohmic contact layer being located between the P-electrode 801 and the P-type GaN layer 203. For example, the P-side ohmic contact layer includes an Indium Tin Oxide (ITO) transparent electrode layer. The ITO layer is arranged under the reflecting electrode to serve as a current expanding layer, so that the transverse current expanding effect can be increased; meanwhile, the first step structure 211 forms the N-electrode 802 which is annular as a whole, so that the current spreading uniformity at the peripheral edge of the chip can be further improved, thereby resulting in low resistance and improved light extraction intensity. An N-side ohmic contact layer (not shown) is further formed on the first step structure 211, and the N-side ohmic contact layer is located between the N-type GaN layer 201 and the N electrode 802 and covers the upper surface and the sidewall of the first step structure. As an example, the P electrode includes a first reflective layer disposed on the P-side ohmic contact layer, and the first reflective layer includes a metal reflective layer of a multilayer structure including, but not limited to, an Ag-based mirror, for example, a Ni/Ag, Ni/Ag/Ni/Au or Ni/Ag/Ni mirror. A diffusion barrier layer is also disposed on the second reflective layer, which may cover the P-electrode to provide protection to the reflective layer, particularly to inhibit metal migration from the reflective layer. The N-electrode 802 is a reflective electrode, and the N-electrode includes a second reflective layer, which includes but is not limited to a metal reflective layer, or a metal dielectric composite reflective layer. The epitaxial light-emitting structure is provided with the reflective electrode surrounding the side wall, so that the effective area of reflection can be obviously increased, the external quantum efficiency of a chip is improved, and the blue leakage problem caused by light emitting from the side wall of the chip is avoided.
As an example, the thin film LED chip further includes a passivation layer 402 disposed on the P-side ohmic contact layer; that is, the passivation layer is disposed on the epitaxial light emitting structure 200The second step structure 213 is covered on the sidewall to reduce the leakage current of the LED device and increase the light output power thereof. Likewise, the passivation layer 402 may also cover the exposed portion of the first step structure 211. In some examples, the passivation layer 402 may be selected from SiO 2 Layer, Si 3 N 4 Layer, SiON layer, Al 2 O 3 A layer or similar inorganic dielectric layer, or a stack of such layers; preferably, the passivation layer 402 may be Al 2 O 3 A stack of layers and an AlN layer. In other examples, the passivation layer 402 may be a composite layer of the inorganic dielectric layers and the organic insulating material layer, the organic insulating material may be selected from the materials commonly used for filling semiconductor trenches, and the inorganic dielectric layers are filled with the organic insulating material for filling and fixing. For example, the passivation layer is Al 2 O 3 And a composite layer with Polyimide (PI) or benzocyclobutene (BCB).
Example two
Referring to fig. 2, the present embodiment provides a micro LED array and a method for manufacturing the same, where the method includes the following steps:
1) providing a growth substrate, forming an epitaxial light-emitting structure on the growth substrate, wherein the epitaxial light-emitting structure comprises an N-type epitaxial layer, a light-emitting layer and a P-type epitaxial layer which are sequentially formed, and performing an etching process to form a first step structure;
2) etching to the surface of the growth substrate along the dicing streets to define individual chip particles;
3) forming a current blocking layer and a passivation layer on the surface of the epitaxial light-emitting structure, and forming a P electrode on the first main surface of the epitaxial light-emitting structure;
4) forming an N electrode on the first step structure;
5) providing a conductive substrate with a bonding layer formed on the upper surface, and transferring the light-emitting unit array onto the conductive substrate;
6) peeling the growth substrate from the second main surface of the epitaxial light-emitting structure;
7) and forming a common cathode on the second light emitting unit.
Similarly, hereinafter, the method of manufacturing the thin film LED chip will be specifically described taking a GaN-based LED chip as an example.
Referring to step S1 in fig. 2, step 1) is performed, which includes: 1-1) providing a growth substrate, and growing an epitaxial light-emitting structure on the growth substrate. Referring to fig. 3A and 3B, the epitaxial light emitting structure 200 has opposing first and second major surfaces 200a, 200B. For example, the growth substrate may be Al 2 O 3 A substrate 100. As an example, in the case of Al 2 O 3 The substrate epitaxial growth epitaxial light emitting structure 200 includes at least: in Al 2 O 3 An N-type GaN layer 201, a quantum well layer 202 and a P-type GaN layer 203 are sequentially grown on the substrate 100, and the N-type GaN layer, the quantum well layer and the P-type GaN layer form a laminated structure. The N-type GaN layer 201 includes an intrinsic epitaxial portion epitaxially grown from a growth substrate and an N-type doped portion between the intrinsic epitaxial portion and the light emitting layer 202. Specifically, step 1) includes: after the epitaxial light emitting structure 200 is epitaxially grown, step 1-2) is performed to penetrate through the first step structure 211 on the surface of the N-type GaN layer 201 by an etching process, as shown in fig. 4. Preferably, the etching process stops at an N-doped portion of the N-type GaN layer, such that the N-doped portion includes an upper section having a first lateral dimension and a lower section having a second lateral dimension, the first lateral dimension being smaller than the second lateral dimension.
Then, step 2) is performed, etching is performed to the surface of the growth substrate along the scribe lines to define single chip particles. Referring to step S2 in fig. 2, a photolithography process may be used to etch the N-type GaN layer 201 along the scribe lines to the surface of the growth substrate to define at least one first light emitting unit 310 and a plurality of second light emitting units 320, which are uniformly arranged in the light emitting unit array 300, and the resulting structure is shown in fig. 5A and 5B. The etching process is, for example, a dry etching process.
After step 2), referring to step S3 in fig. 2, step 3) includes: 3-1) depositing a current blocking layer 701 on the at least one light emitting cell 310 on the growth substrate; 3-2) forming a P-side ohmic contact layer on the first and second light emitting cells 310 and 320, and forming a P-side ohmic contact layer on the P-sideForming a P electrode on the ohmic contact layer; 3-3) depositing a passivation layer on the epitaxial light-emitting structure. In this embodiment, in step 3-1), a current blocking layer 701 is deposited on the first main surface and the sidewalls of the epitaxial light emitting structure, as shown in fig. 6. The current blocking layer 701 may be a dielectric layer, such as SiO, formed by a process including, but not limited to, a chemical vapor deposition process or a passivation process 2 Layer, or Si 3 N 4 And (3) a layer. Specifically, in step 3-2), a P-side ohmic contact layer is formed on a portion of the surface of the P-type GaN layer to form a second step structure 213; forming a P electrode on the P-surface ohmic contact layer, wherein the P electrode is formed as a reflecting electrode; after the step 3-2), a step 3-3) is performed to integrally form a passivation layer 402 on the first step structure 301 and the second step structure 302, wherein the passivation layer is further disposed on the sidewall of the epitaxial light emitting structure, as shown in fig. 7A and 7B. For example, the P-side ohmic contact layer may be an ITO layer to improve the uniformity of current spreading. As an example, the P electrode can be a metal reflective layer, which can be a multilayer structured reflective layer including, but not limited to, Ag-based mirrors, such as Ni/Ag, Ni/Ag/Ni/Au, or Ni/Ag/Ni mirrors. In some examples, the passivation layer 402 may be selected from SiO 2 Layer, Si 3 N 4 Layer, SiON layer, Al 2 O 3 A layer or similar inorganic dielectric layer, or a stack of such layers; preferably, the passivation layer 402 may be Al 2 O 3 A stack of layers and an AlN layer. In other examples, the passivation layer 402 may be a composite layer of the above inorganic dielectric layers and organic insulating material layers, the organic insulating material may be selected from common materials for filling semiconductor trenches, and the organic insulating material is filled between the inorganic dielectric layers for filling and fixing. For example, the passivation layer is Al 2 O 3 And a composite layer with Polyimide (PI) or benzocyclobutene (BCB). The passivation layer 402 may be formed by processes including, but not limited to, the following: plasma Enhanced Chemical Vapor Deposition (PECVD), electron beam evaporation process, or the like. Preferably, Al is used 2 O 3 A passivation layer 402 is made of a stack with AlN.
With continued reference to S4 in FIG. 2And step 4), forming an N electrode on the first step structure. Specifically, step 4) includes: 4-1) removing a part of the passivation layer through a photolithography etching process to expose the surface of the N-type GaN layer on the upper surface of the first step structure 211 and expose the P-electrode 801 on the second step structure 213. In this embodiment, referring to fig. 8A and 8B, step 4) includes: after the step 4-1), performing a step 4-2) to form an N electrode 802 on the N-type GaN layer exposed by the first step structure through an evaporation process; 4-3) forming a diffusion barrier layer 501 on the exposed P-electrode 801 to avoid the influence of humidity from the external environment and to cut off the migration path of Ag or other metals in the reflective layer. The N-electrode 802 may be a metal reflective layer or a metal dielectric composite reflective layer. In some examples, the N-electrode may be a metal dielectric composite reflective layer including a low refractive index dielectric layer and a high light reflection metal layer, such as an Ag-based mirror and SiO 2 、SiN x Or a composite layer of SiON.
Referring to S5 in fig. 2, step 5) is performed to provide a conductive substrate with a bonding layer formed on an upper surface thereof, and transfer the light emitting cell array onto the conductive substrate. Specifically, step 5) includes: 5-1) providing a conductive substrate 602 with a metal bonding layer 601 formed on the upper surface; 5-2) bonding the light emitting cell array 300 to the conductive substrate 602 so that the P-electrode 801 of each light emitting cell is electrically connected to a corresponding electrode on the conductive substrate 602. Specifically, in step 5-2), each light emitting cell in the light emitting cell array 300 is bonded to the conductive substrate 502 through the metal bonding layer 601 for electrically connecting the single chip with the conductive substrate. For example, the metal bonding layer 601 includes, but is not limited to, Au or In. The light emitting unit array in the embodiment is transferred and bonded to the conductive substrate at one time, so that the preparation process can be greatly simplified, and the obtained light emitting unit array can have improved yield and reliability.
After step 5), referring to S6 in fig. 2, step 6) is performed to peel off the growth substrate from the second main surface 200B of the epitaxial light emitting structure, and a bottom schematic view of the chip structure after peeling is shown in fig. 9B. Specifically, step 6) includes: 6-1) stripping the growth substrate by a chemical stripping process; 6-2) forming an insulation gap between adjacent light emitting cells. Compared with the LED chip manufacturing process of peeling the growth substrate by adopting the laser peeling process, the laser peeling process is easy to cause the damage of the grown epitaxial layer, the electric leakage of the device and the deterioration of the performance of the device can be caused, the chemical peeling technology is adopted in the embodiment, the damage of the epitaxial layer caused by the laser peeling process can be avoided, the manufacturing cost of the thin film LED device can be reduced, and the quality of the device is improved. As an example, in step 6-2), an insulating material is filled between adjacent light emitting cells, and the resulting structure is shown in fig. 10A and 10B. For example, the insulating material may be a fluorine-based resin material.
With continuing reference to step S7 in fig. 2 and with continuing reference to fig. 11A and 11B, step 7) is performed to form a common cathode over the second light-emitting unit. In this embodiment, step 7) includes: 7-1) defining a graphical area through a photoetching process; 7-2) forming a common cathode 710 and a bonding pad 720 in the patterned region by an evaporation process, wherein the common cathode is arranged at the passage of the epitaxial light-emitting structure to define a light window, and the bonding pad covers the second main surface of the epitaxial light-emitting structure for electrically connecting with an external lead.
The micro LED array shown in fig. 11A can be obtained by the manufacturing method of this embodiment, and this embodiment further provides a micro LED array including at least one first light emitting unit 310 and a plurality of second light emitting units 320, where the first light emitting unit and the second light emitting units are uniformly arranged on a conductive substrate 502 to form a light emitting unit array 300, each light emitting unit in the light emitting unit array is a thin film LED chip with a vertical structure as in the first embodiment, where each light emitting unit includes a first step structure 211 penetrating through to the surface of an N-type epitaxial layer, an N electrode 802 includes a main body portion 802a and an extension portion 802b, and the main body portion is in electrical contact with the upper surface of the first step structure 211. The micro LED array further comprises a common electrode 710, which is arranged on the second main surface 200b of the light emitting epitaxial structure and is electrically connected with the extension 802 of the N-electrode.
In the present embodiment, the first light emitting unit 310 includes a pad 720 on the second main surface 200b of the epitaxial light emitting structure, through which the common electrode is electrically connected to an external lead, and a current blocking layer 701 on the first main surface 200a and the sidewall of the epitaxial light emitting structure. The first light emitting unit 310 includes a current blocking layer disposed on the first main surface and the sidewall of the epitaxial light emitting structure for preventing current concentration caused by electrode introduction from the first light emitting unit and chip damage caused thereby. In addition, each light emitting unit on the light emitting unit array further includes a diffusion barrier layer 501, and the diffusion barrier layer is bonded to the electrode on the conductive substrate through a metal bonding layer arranged between the diffusion barrier layer and the conductive substrate.
In summary, as mentioned above, the thin film LED chip of the present invention has the following advantages:
1) in the thin film LED chip with a vertical structure of the present invention, the N electrode includes a main body portion and an extension portion, the N electrode is in electrical contact with the upper surface of the electrode step through the main body portion, and the extension portion is formed around the sidewall of the electrode step, which helps to realize the uniformity of current expansion, improves the uniformity of current injection, helps to reduce the chip resistance, and improves the light intensity;
2) in the thin film LED chip with the vertical structure, the metal medium composite reflecting layer or the metal reflecting layer is arranged on the side wall of the electrode step by surrounding the electrode step of the epitaxial light-emitting structure, so that the light-emitting efficiency of the N surface can be greatly improved by obviously improving the effective area of reflection, the external quantum efficiency of the chip is improved, and the high light efficiency can be achieved;
the utility model also provides a miniature LED array has following beneficial effect:
3) in the micro LED array, the surface of the exposed epitaxial light-emitting structure of each chip is provided with the passivation layer, and the adjacent chips are provided with the insulation gaps, so that the electric leakage of the chips can be obviously reduced, and the photoelectric performance of the chips can be improved;
4) the utility model discloses an among the miniature LED array, adopt the miniaturized array of chip, can set up insulating gap in adjacent chip interval region to can promote the stability and the reliability of chip.
Therefore, the utility model effectively overcomes various defects in the prior art and has high industrial utilization value.
The above embodiments are merely illustrative of the principles and effects of the present invention, and are not to be construed as limiting the invention. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which may be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.
Claims (12)
1. A thin film LED chip in a vertical structure, comprising:
the epitaxial light-emitting structure is provided with a first main surface and a second main surface which are opposite, and comprises an N-type epitaxial layer, a light-emitting layer and a P-type epitaxial layer which are sequentially stacked, and the epitaxial light-emitting structure is provided with a first step structure penetrating through the surface of the N-type epitaxial layer;
the electrode structure comprises an N electrode, the N electrode is arranged on a first step structure of the N-type epitaxial layer and comprises a main body part and an extension part, the N electrode is in electrical contact with the upper surface of the first step structure through the main body part, and the extension part is formed around the side wall of the N-type epitaxial layer; and the P electrode is arranged on the first main surface of the epitaxial light-emitting structure, and is formed as a reflecting electrode so that the thin film LED chip has an N-surface light-emitting structure.
2. The vertically structured thin film LED chip of claim 1, wherein: the epitaxial light-emitting structure further comprises an N-face ohmic contact layer covering the upper surface and the side wall of the first step structure, and the first step structure is formed around the epitaxial light-emitting structure.
3. The vertically structured thin film LED chip of claim 1, wherein: the N electrode is disposed on the N-side ohmic contact layer, and a main portion and an extension portion of the N electrode are integrally formed in a ring shape by the first step structure.
4. The vertically structured thin film LED chip of claim 1, wherein: the N-type epitaxial layer comprises an intrinsic epitaxial part and an N-type doped part positioned between the intrinsic epitaxial part and the light emitting layer, and the main body part of the N electrode is electrically contacted with the N-type doped part arranged on the upper surface of the first step structure.
5. The vertically structured thin film LED chip of claim 1, wherein: the epitaxial light-emitting structure further comprises a P-surface ohmic contact layer, and the P-surface ohmic contact layer is arranged on part of the surface of the P-type epitaxial layer to form a second step structure.
6. The vertically structured thin film LED chip of claim 5, wherein: the P electrode comprises a first reflecting layer, the first reflecting layer is arranged on the P-surface ohmic contact layer, and the first reflecting layer comprises a metal reflecting layer with a multilayer structure.
7. The vertically structured thin film LED chip of claim 1, wherein: the N electrode comprises a second reflecting layer, and the second reflecting layer comprises one of a metal reflecting layer or a metal dielectric composite reflecting layer.
8. The vertically structured thin film LED chip of claim 5, wherein: the thin film LED chip further comprises a passivation layer, the passivation layer is arranged on the side wall of the epitaxial light-emitting structure and covers the second step structure, and the passivation layer comprises SiO 2 Layer, Si 3 N 4 Layer, SiON layer、Al 2 O 3 Layer or Al 2 O 3 A lamination of the layer and an AlN layer, or a composite layer of any one of the inorganic dielectric layers and polyimide or benzocyclobutene.
9. A micro LED array, comprising:
at least one first light-emitting unit and a plurality of second light-emitting units, wherein the first light-emitting unit and the second light-emitting units are uniformly arranged on a conductive substrate to form a light-emitting unit array, and each light-emitting unit in the light-emitting unit array is a thin-film LED chip with a vertical structure according to any one of claims 1 to 8;
and the common electrode is arranged on the second main surface of the epitaxial light-emitting structure and is electrically connected with the extension part of the N electrode.
10. The micro LED array of claim 9, wherein: the first light emitting unit comprises a bonding pad positioned on the second main surface of the epitaxial light emitting structure and a current blocking layer positioned on the first main surface and the side wall of the epitaxial light emitting structure, and the common electrode is electrically connected with an external lead through the bonding pad.
11. The micro LED array of claim 9, wherein: each light-emitting unit comprises a diffusion impervious layer covering a P electrode, and the diffusion impervious layer is bonded with the electrode on the conductive substrate through a metal bonding layer arranged between the diffusion impervious layer and the conductive substrate.
12. The micro LED array of claim 9, wherein: and an insulation gap is arranged between the adjacent light-emitting units, and the insulation gap is filled with an insulation material.
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| CN114447176A (en) * | 2022-01-28 | 2022-05-06 | 上海芯元基半导体科技有限公司 | Thin film LED chip with vertical structure, micro LED array and preparation method thereof |
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