CN114284402B

CN114284402B - LED device, manufacturing method thereof, display device and light-emitting device

Info

Publication number: CN114284402B
Application number: CN202111614594.1A
Authority: CN
Inventors: 刘召军; 黄炳铨; 张珂
Original assignee: Shenzhen Stan Technology Co Ltd
Current assignee: Shenzhen Stan Technology Co Ltd
Priority date: 2021-12-27
Filing date: 2021-12-27
Publication date: 2024-03-29
Anticipated expiration: 2041-12-27
Also published as: CN114284402A

Abstract

The application provides a preparation method of an LED device, the LED device, a display device and a light-emitting device. The preparation method of the LED device comprises the following steps: forming an array of LED chips on a substrate; a passivation layer is integrally arranged above the LED chip array, and electrode contact holes are formed in the passivation layer to expose part of the electrode layer; a bonding layer is arranged in the electrode contact hole; wherein the bonding layer comprises a conductive layer and a solder layer, and the conductive layer is positioned between the electrode layer and the solder layer; the conductive layer is made of a high-melting-point conductive material; and bonding the LED chip array and the driving substrate through the bonding layer, and stripping the substrate to obtain the LED device. According to the preparation method of the LED device and the LED device prepared by the preparation method, the bonding layer with the double-layer structure is adopted, and the conducting layer is made of the high-melting-point conducting material, so that the chip is effectively prevented from falling off due to melting of solder in the laser stripping process.

Description

LED device, manufacturing method thereof, display device and light-emitting device

Technical Field

The application relates to the field of display, in particular to a preparation method of an LED device, the LED device, a display device and a light-emitting device.

Background

Micro Light-Emitting Diode (Micro-LED) based on third generation wide bandgap semiconductor GaN material has the characteristics of self-luminescence, low power consumption, high brightness, high contrast, high resolution and the like, and a Micro-LED display screen has a high-density pixel array, wherein the size of a single pixel is often tens of micrometers or even several micrometers. The display screen can be applied to AR, VR, MR, miniature projection and wearable equipment with high resolution and brightness requirements, and can even integrate illumination and display, so that the display screen has high commercial application value and considerable development prospect.

In order to obtain better light-emitting efficiency and reduce light crosstalk, the prior art generally adopts a laser lift-off (LLO) technology to lift off a Micro-LED substrate, but a Micro-LED using indium solder with a lower melting point is singly used, when the substrate is lifted off by laser, the Micro-LED is lifted off a driving plate or a temporary bonding substrate due to the thermal effect of the laser, so that the yield of laser lift-off is reduced, and the cost is increased.

Disclosure of Invention

In order to solve at least one of the above technical problems, the application provides a preparation method of an LED device, the LED device, a display device and a light-emitting device. The LED device prepared by the method can effectively avoid the falling of the chip during laser stripping, effectively improve the yield of laser stripping and reduce the cost.

In order to achieve the above object, the present application provides a method for manufacturing an LED device, including the steps of: forming an array of LED chips on a substrate; a passivation layer is integrally arranged above the LED chip array, and electrode contact holes are formed in the passivation layer to expose part of the electrode layer; a bonding layer is arranged in the electrode contact hole; wherein the bonding layer comprises a conductive layer and a solder layer, and the conductive layer is positioned between the electrode layer and the solder layer; the conductive layer is made of a high-melting-point conductive material; and bonding the LED chip array and the driving substrate through the bonding layer, and stripping the substrate to obtain the LED device. The application adopts the bonding layer with the double-layer structure, and the bottom conductive layer adopts the high-melting-point conductive material, so that the chip is effectively prevented from falling off due to melting of solder in the laser stripping process, and meanwhile, the bonding temperature is effectively reduced, and the process cost is reduced.

Optionally, the forming the LED chip array on the substrate includes: etching the epitaxial structure on the substrate to expose part of the first semiconductor layer; providing a current diffusion layer on the second semiconductor layer of the epitaxial structure; arranging electrode layers on the current diffusion layer and the first semiconductor layer to obtain the LED chip array; the electrode layer comprises a first electrode arranged on the periphery of the LED chip array, a second electrode arranged on the current diffusion layer and metal grid lines arranged between the epitaxial structures. According to the LED chip array, the common electrode design is adopted, namely the LED chip array shares the first electrode, and current collection and transmission are realized through the metal grid lines and/or the first semiconductor layer, so that current uniformity is effectively improved.

Optionally, the width of the metal grid lines is narrower than the first electrode and/or the second electrode. The arrangement of the metal grid lines effectively improves the current uniformity on one hand, and on the other hand, the area of the metal grid lines covering the first semiconductor layer is smaller, so that the light-emitting area of the LED device is effectively increased, and the light-emitting efficiency of the device is improved.

Optionally, the passivation layer comprises silicon nitride and/or silicon oxide.

Optionally, the electrode contact hole is disposed above the first electrode and the second electrode.

Optionally, disposing a bonding layer in the electrode contact hole includes: sequentially depositing the conductive layer and the solder layer in the electrode contact hole; and (3) after the reflow treatment, melting and solidifying the solder layer to obtain the solder bump.

Optionally, the depositing the conductive layer and the solder layer in the electrode contact hole sequentially includes: depositing the conductive layer in the electrode contact hole, and forming a concave part in the middle of the conductive layer; and depositing the solder layer in the concave part.

Optionally, a middle portion of the solder layer forms another recess.

Optionally, the reflow process includes: the reflux treatment is carried out under vacuum or in an oxygen-free atmosphere, wherein the peak reflux temperature is between 156 and 260 ℃; and refluxing for 5-300s at the reflux peak temperature.

Optionally, the reflow treatment employs a eutectic reflow oven.

Optionally, the high-melting-point conductive material is a high-melting-point metal conductive material or a high-melting-point nonmetal conductive material.

Optionally, the melting point of the solder layer is lower than the melting point of the conductive layer.

Optionally, the high melting point conductive material is a high melting point solder.

Optionally, the conductive layer is made of gold-tin alloy, and the solder layer is made of indium metal.

Optionally, the thickness ratio of the conductive layer to the solder layer is 1:3-2:1.

Alternatively, the stripping is a laser stripping method.

Optionally, the LED chip array is a Micro-LED chip array.

The application also provides an LED device, wherein the LED device is prepared by the preparation method of the LED device.

Optionally, the LED device includes an LED chip array, a passivation layer, and a bonding layer, where the LED chip array includes a plurality of LED chips, and the LED chips include a first semiconductor layer, a multiple quantum well structure, a second semiconductor layer, a current diffusion layer, and an electrode layer that are stacked from bottom to top; the passivation layer covers the LED chip array; the passivation layer is provided with an electrode contact hole, the bonding layer is arranged in the electrode contact hole, and the bonding layer is of a double-layer structure.

Optionally, the bonding layer includes a conductive layer and a solder layer, the conductive layer is located between the electrode layer and the solder layer, and the conductive layer is made of a high-melting-point conductive material.

Optionally, a concave part is arranged in the middle of the conductive layer, and the solder layer is arranged in the concave part; the cross section of the concave part is square, inverted triangle or inverted trapezoid.

Optionally, the electrode layer includes a first electrode disposed at the periphery of the LED chip array, a second electrode disposed on the current diffusion layer, and metal grid lines disposed between the LED chips, where the metal grid lines are electrically connected to the first electrode.

Optionally, the width of the metal grid lines is narrower than the first electrode and/or the second electrode.

Optionally, the bonding layer is disposed on the first electrode and the second electrode.

Optionally, the LED chip array is a Micro-LED chip array.

The application also provides a display device, wherein the display device comprises the LED device.

The application also provides a light-emitting device, wherein the light-emitting device comprises the LED device.

According to the preparation method of the LED device and the LED device prepared by the preparation method, the bonding layer with the double-layer structure is adopted, and the conductive layer is made of the high-melting-point conductive material, so that the chip is effectively prevented from falling off due to melting of the solder in the laser stripping process, in addition, the conductive layer is made of the high-melting-point conductive material, the melting point of the solder layer is lower than that of the conductive layer, the bonding temperature is effectively reduced, and the process cost is reduced. In addition, the common electrode design is adopted, namely the LED chip array shares the first electrode, and current collection and transmission are realized through the metal grid lines and/or the first semiconductor layer, so that current uniformity is effectively improved, and photoelectric performance of the device is improved.

Drawings

The above, as well as additional purposes, features, and advantages of exemplary embodiments of the present application will become readily apparent from the following detailed description when read in conjunction with the accompanying drawings. Several embodiments of the present application are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar or corresponding parts and in which:

fig. 1 shows a flow chart of a method of manufacturing an LED device according to one embodiment of the present application;

FIGS. 2 a-2 d illustrate a schematic process flow diagram of the fabrication of an LED device according to a preferred embodiment of the present application;

fig. 3 shows a schematic cross-sectional structure of an LED device according to an embodiment of the present application.

Detailed Description

It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other. The technical solutions of the present application will be described in detail below with reference to the accompanying drawings in combination with embodiments. The drawings described herein are for illustration purposes only and are not intended to be limiting.

It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. 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.

Spatially relative terms, such as "above … …," "above … …," "upper surface at … …," "above," and the like, may be used herein for ease of description to describe a spatial location of one device or feature relative to another device or feature as illustrated in the figures, either directly or indirectly via an intervening medium. It will be understood that the spatially relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "over" other devices or structures would then be oriented "below" or "beneath" the other devices or structures. Thus, the exemplary term "above … …" may include both orientations of "above … …" and "below … …". The device may also be oriented 90 degrees or at other orientations and the spatially relative descriptors used herein interpreted accordingly.

Exemplary embodiments according to the present application will now be described in more detail with reference to the accompanying drawings. These exemplary embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It should be appreciated that these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of these exemplary embodiments to those skilled in the art, that in the drawings, thicknesses of layers and regions are exaggerated for clarity, and identical reference numerals are used to denote identical devices, and thus descriptions thereof will be omitted.

One embodiment of the application provides a method for manufacturing an LED device. Referring to fig. 1, the method of manufacturing the LED device includes the following steps S101 to S104.

Step S101: an array of LED chips is formed on a substrate.

According to the embodiments of the present application, any method of forming an LED chip array on a substrate in the prior art may be applied to the technical solutions of the present application, and is not particularly limited herein. The material of the substrate can be selected according to actual needs, and for example, the substrate can comprise any one of sapphire, aluminum nitride, silicon carbide, gallium nitride single crystal material and the like; the structure, size, number, arrangement, etc. of the LED chips in the LED chip array may be set according to actual needs, and the application is not particularly limited.

As a preferred embodiment, forming the LED chip array on the substrate may include the steps of:

etching the epitaxial structure on the substrate to expose part of the first semiconductor layer;

providing a current diffusion layer on the second semiconductor layer of the epitaxial structure;

arranging electrode layers on the current diffusion layer and the first semiconductor layer to obtain the LED chip array;

the electrode layer comprises a first electrode arranged on the periphery of the LED chip array, a second electrode arranged on the current diffusion layer and metal grid lines arranged between the epitaxial structures.

As shown in fig. 2a, an epitaxial structure is disposed on a substrate 101, the epitaxial structure includes a first semiconductor layer 102, a multiple quantum well structure 103, and a second semiconductor layer 104 which are sequentially stacked from bottom to top, and the epitaxial structure on the substrate 101 is etched to a depth equal to or slightly greater than the sum of the thicknesses of the second semiconductor layer 104 and the multiple quantum well structure 103 so as to expose a portion of the first semiconductor layer 102; depositing a current diffusion layer 105 over the second semiconductor layer 104, wherein the current diffusion layer 105 may be a single or multiple metal layers, or may be an Indium Tin Oxide (ITO) layer; an electrode layer 106 is deposited over the current spreading layer 105 and the first semiconductor layer 102 to obtain the LED chip array 100 (shown in dashed line), wherein the electrode layer 106 includes a first electrode 1061 disposed at the periphery of the LED chip array 100, a second electrode 1062 disposed on the current spreading layer 105, and metal grid lines 1063 disposed between the epitaxial structures. It should be understood that the number of LED chips shown in fig. 2a is merely exemplary and is not limiting herein.

Preferably, the current diffusion layer 105 is an ITO layer; the current spreading layer 105 may be annealed prior to depositing the electrode layer 106, in particular, the current spreading layer 105 is provided on the second semiconductor layer 104 of the epitaxial structure and then subjected to a temperature O of 500-800 c (preferably 600 c) ₂ Treating in a gaseous atmosphere for 200-400s (preferably 300 s) to oxidize ITO, and then exposing to N at 600-800 deg.C (preferably 750 deg.C) ₂ The ITO alloy is processed for 25 to 40 seconds (preferably 30 seconds) in a gas environment, so that the conductivity of the ITO is effectively improved.

In this application, the substrate is used as the bottom layer, that is, "upper" means a side far from the substrate, and "disposing the B layer on the a layer" means that the B layer is disposed on a side far from the substrate. The structures, materials, thicknesses, etc. of the first electrode 1061, the second electrode 1062, and the metal grid lines 1063 may be the same or different, and are not particularly limited herein; if the structures, materials, thicknesses, etc. of the first electrode 1061, the second electrode 1062, and the metal grid lines 1063 are different, the deposition may be performed by a fractional photolithography stripping method, which is not described herein.

Preferably, the LED chip array is a Micro-LED chip array, and the LED chip array 100 includes a plurality of LED chips with the same size and structure, which are arranged at equal intervals according to rows and columns; the size of each LED chip is preferably 1-50 μm; the width of the metal grid lines 1063 is narrower than the first electrode 1061 and the second electrode 1062, and the width of the metal grid lines 1063 is preferably 0.5-5 μm. The metal grid lines 1063 are electrically connected to the first electrode 1061 for collecting and transmitting current, and the process, material, structure, etc. of the metal grid lines can be consistent with those of the first electrode 1061 and the second electrode 1062, and other metals with better conductivity, such as silver, copper, gold, etc. can be selected.

The preferred embodiment adopts a common electrode design, namely the LED chip array shares the first electrode, and realizes current collection and transmission through the metal grid lines, thereby effectively improving the current uniformity and the photoelectric performance of the device. In addition, the area of the metal grid lines 1063 covering the first semiconductor layer is smaller, so that the light emitting area is effectively increased, the utilization rate of the epitaxial wafer is improved, and the light emitting efficiency of the LED device is improved.

Alternatively, the substrate 101 may be sapphire, the first semiconductor layer 102 may be N-type gallium nitride (N-GaN), the multiple quantum well structure 103 may be an indium gallium nitride/gallium nitride (InGaN/GaN) multiple quantum well layer, the second semiconductor layer 104 may be P-type gallium nitride (P-GaN), the current diffusion layer may be ITO, and the first electrode 1061, the second electrode 1062, and the metal grid line 1063 may be a titanium/aluminum/titanium/gold multilayer structure. The buffer layer 107 and the undoped gallium nitride (U-GaN) layer 108 may be further included between the substrate 101 and the first semiconductor layer 102, where the buffer layer 107 may be made of gallium nitride or aluminum nitride, and the buffer layer 107 and the U-GaN layer 108 are disposed, which is beneficial to reducing lattice mismatch and thermal stress mismatch between the chip epitaxial structure and the substrate.

Preferably, the first electrode 1061 and the second electrode 1062 have a titanium/aluminum/titanium/Jin Duoceng structure, and the electrodes of the multilayer structure may not only function as electrode layers to achieve current transmission of the LED device, but also function as adhesion layers/diffusion barrier layers/wetting layers. Specifically, the titanium can play a role of an adhesion layer and/or a diffusion barrier layer so as to realize adhesion between the electrode layer and the current diffusion layer, and can effectively prevent the bonding layer from diffusing to the bottom metal of the electrode layer; the hardware fitting has good wettability, so that the hardware fitting can play a role of a wetting layer to have good wetting with a bonding layer, and the welding reliability is effectively improved.

It may be appreciated that in the embodiment of the disclosure, the electrode layer may include only a first electrode disposed at the periphery of the LED chip array and a second electrode disposed on the current diffusion layer, and the LED chips are connected to each other and electrically connected to the first electrode through a first semiconductor layer (i.e., an N-type semiconductor layer). The arrangement method of the first electrode and the second electrode, and the structure, material, size, etc. thereof may be the same as or similar to those of the first electrode 1061 and the second electrode 1062, and will not be described herein.

Step S102: and a passivation layer is integrally arranged above the LED chip array, and electrode contact holes are formed in the passivation layer to expose part of the electrode layer.

According to the embodiment of the application, the passivation layer is arranged above the LED chip array, so that the LED chips are wrapped, mutual isolation among the LED chips is realized, short circuits are effectively avoided, and interconnection among the LED chips is realized through the first semiconductor layer and the metal grid lines; and exposing a portion of the electrode layer by providing an electrode contact hole on the passivation layer so that a bonding layer is subsequently provided in the electrode contact hole.

In this application, the term "integrally disposed" refers to that the passivation layer covers not only each LED chip in the LED chip array and the first semiconductor layer and the metal grid lines exposed between the LED chips, but also the first semiconductor layer and the first electrode exposed at the periphery of the LED chip array.

As a preferred embodiment, electrode contact holes are provided only in the passivation layer over the first electrode and the second electrode; the size of the electrode contact hole can be set according to actual needs; the cross-sectional shape of the electrode contact hole may be square, inverted trapezoid or inverted triangle, and the top projection shape of the electrode contact hole may be set according to actual needs, for example, square, circle, triangle, quadrilateral, star or hexagon.

As shown in fig. 2b, a passivation layer 109 is integrally disposed over the LED chip array, and the passivation layer 109 over the first electrode 1061 and the second electrode 1062 is perforated to obtain an electrode contact hole 110. It should be understood that the number of LED chips shown in fig. 2b is merely exemplary and is not limiting herein.

Alternatively, the passivation layer 109 may employ silicon nitride and/or silicon oxide, preferably silicon nitride.

Step S103: a bonding layer is arranged in the electrode contact hole; wherein the bonding layer comprises a conductive layer and a solder layer, and the conductive layer is positioned between the electrode layer and the solder layer; the conductive layer is made of a high-melting-point conductive material.

According to the embodiment of the disclosure, the bonding layer with the double-layer structure is adopted, and the conductive layer is made of the high-melting-point conductive material, so that the chip is effectively prevented from falling off due to melting of solder in the laser stripping process, and the product yield is effectively improved.

As a preferred embodiment, the disposing the bonding layer in the electrode contact hole may include the steps of:

sequentially depositing the conductive layer and the solder layer in the electrode contact hole;

and (3) after the reflow treatment, melting and solidifying the solder layer to obtain the solder bump.

According to the method, the conductive layer and the solder layer are deposited in the electrode contact hole, wherein the conductive layer is made of the high-melting-point conductive material, and the high-melting-point conductive material can absorb part of laser heat in the subsequent laser stripping process, so that the solder layer can be effectively prevented from melting, and the chip is prevented from falling off. In addition, through the arrangement of the bonding layer, no soldering flux is reflowed, so that the influence of the soldering flux on the performance of the light-emitting device is effectively avoided.

Preferably, depositing the conductive layer and the solder layer in the electrode contact hole in sequence may include the steps of: depositing a conductive layer in the electrode contact hole, wherein the thickness of the conductive layer is equal to or greater than the depth of the electrode contact hole; a solder layer is deposited over the conductive layer. In the preferred embodiment, the conductive layer is arranged in the electrode contact hole to realize electrical connection with the electrode layer, and the high-melting-point conductive material is not easy to be heated and melted in the subsequent laser stripping process, and can absorb a part of laser heat, so that the solder layer is effectively prevented from being heated and melted, and the chip is prevented from falling off in the laser stripping process.

In another preferred embodiment, the sequentially depositing the conductive layer and the solder layer in the electrode contact hole includes: depositing a conductive layer in the electrode contact hole, and forming a concave part in the middle of the conductive layer; and depositing the solder layer in the concave part. Wherein, the cross section shape of the concave part can be square, inverted triangle or inverted trapezoid, preferably inverted trapezoid.

Further preferably, another recess is formed in the middle of the solder layer.

It is understood that, in the present application, the bonding layer is disposed above the first electrode and the second electrode, and corresponds to the electrode contact holes one by one, and is isolated from each other, and the "middle part of the conductive layer" refers to the middle part of the conductive layer corresponding to each electrode contact hole. In order to better distinguish between the recesses of the conductive layer and the recesses of the solder layer, the recesses of the conductive layer may also be referred to as "first recesses" and the recesses of the solder layer as "second recesses".

As shown in fig. 2c, a high-melting-point conductive material is filled in the electrode contact hole 110 to obtain a conductive layer 111, wherein the thickness of the conductive layer 111 is greater than the depth of the electrode contact hole 110, and a first concave portion 1110 is formed in the middle of the conductive layer, so that the cross-section shape of the conductive layer is inverted-delta-shaped; the first concave portion 1110 is filled with solder to obtain a solder layer 112, wherein the thickness of the solder layer 112 is greater than the depth of the first concave portion 1110, and a second concave portion 1120 is formed in the middle of the solder layer, so that the cross-section shape of the solder layer is inverted 'V' -shaped.

According to the preferred embodiment, the high-melting-point conductive material is filled in the electrode contact hole, and a concave part is formed in the middle of the conductive layer, so that the solder layer can be arranged in the concave part, and the solder can not overflow when the solder layer is subjected to reflow treatment, and the cavity rate is effectively reduced. The concave part in the middle of the solder layer enables the peripheral solder to flow back to the middle during the reflow treatment, which is not only beneficial to avoiding overflowing, but also can obtain larger solder bumps, thereby being beneficial to subsequent welding, and can effectively avoid melting and falling off in the subsequent laser stripping process.

According to the embodiment of the application, the conductive layer is mainly used for contacting with the electrode layer to realize electrical connection with the electrode layer, and the conductive layer is made of a high-melting-point conductive material, preferably a material with a high melting point (for example, more than 250 ℃), high mechanical strength and good electrical conductivity and thermal conductivity, and can be a high-melting-point metal conductive material or a high-melting-point nonmetal conductive material, for example, one of gold-tin alloy, gold, titanium, nickel, aluminum, copper, graphite and graphene; the solder layer is mainly used for bonding the LED chip array and the driving substrate, and the solder layer is preferably solder with good wettability and good electric conduction and thermal conduction, and can be one of indium, tin and silver-tin alloy. The thickness ratio of the conductive layer to the solder layer is preferably 1:3-2:1, and the thickness of the conductive layer is preferably 0.3-7 mu m, so that good electric conduction and heat conduction properties of the bonding layer can be ensured, the connection strength of the conductive layer and the electrode layer can be ensured, falling-off in the laser stripping process can be effectively avoided, and the device yield can be improved.

Further, if the high-melting-point conductive material is a high-melting-point non-metal conductive material, such as graphene, the graphene can be deposited on the electrode layer by a chemical vapor deposition method, or the graphene coating can be disposed in the electrode contact hole by a coating or filling method. The graphene not only has a high melting point, but also can be effectively prevented from melting in the laser stripping process; the LED has extremely high heat conductivity coefficient, and can effectively improve the heat dissipation efficiency of the LED device; in addition, the graphene has electrical and optical properties, which is beneficial to improving the photoelectric performance of the LED device.

Preferably, the high melting point conductive material is a high melting point solder, comprising: gold-tin alloy, gold, titanium, nickel, aluminum, copper. Preferably, the melting point of the solder layer is lower than that of the conductive layer, so that low-temperature bonding can be realized, and the process cost is effectively reduced.

Optionally, the conducting layer adopts gold-tin alloy, and the solder adopts indium metal, wherein Jin Zhanbi in the gold-tin alloy is preferably 80%, and the eutectic point of the gold-tin alloy is 280 ℃ in the proportion, so that the thermal conductivity and the reliability are excellent; the reflow process may include: the reflux treatment is carried out under vacuum or in an oxygen-free atmosphere, wherein the peak reflux temperature is between 156 and 260 ℃; and refluxing for 5-300s at the reflux peak temperature. The reflow treatment preferably employs a eutectic reflow oven.

According to the embodiment of the application, the gold-tin alloy is preferably used as a conductive layer material, and the indium is used as a solder layer material, wherein the gold-tin alloy has strong mechanical strength and good heat and electric conduction performance, and the indium is low-temperature solder with excellent performance, has good ductility, high heat conductivity, good wettability and plastic deformation, and can effectively avoid falling off due to solder melting in the laser stripping process by adopting the gold-tin alloy/indium bonding layer, and meanwhile, the bonding temperature is effectively reduced, and the process cost is reduced. The melting point of indium is low, so that the temperature of a reflow peak can be low during reflow treatment, and the energy consumption is effectively reduced; in addition, due to the arrangement of the bonding layer, the use amount of indium can be moderately reduced, so that the reflow time can be shortened, and the reflow energy consumption is further reduced.

In another preferred embodiment, after sequentially depositing the conductive layer and the solder layer in the electrode contact hole, the solder layer is not reflowed. In the present preferred embodiment, the solder layer is preferably indium. The conductive layer and the electrode layer form reliable contact, while the indium is softer in texture and has good plastic deformation, and when the LED chip and the circuit substrate are bonded later, the indium can be directly heated to soften or be in a molten state to be bonded with the circuit substrate, so that the process steps are simplified.

Preferably, a conductive layer is deposited in the electrode contact hole, and a concave part is formed in the middle of the conductive layer; and depositing the solder layer in the concave part, and forming another concave part in the middle of the solder layer. Wherein, the cross section shape of the concave part can be square, inverted triangle or inverted trapezoid, preferably inverted trapezoid.

In the preferred embodiment of the present disclosure, the conductive layer is disposed in the electrode contact hole and is electrically connected to the electrode layer; the solder layer is arranged in the concave part of the conductive layer, so that the contact area between the conductive layer and the solder layer is effectively increased, and in the subsequent laser stripping process, the high-melting-point conductive material of the conductive layer can absorb part of laser heat, so that the solder layer can be effectively prevented from melting, and further the chip is prevented from falling off; and the middle part of the solder layer is provided with another concave part, so that when the LED chip array is bonded with the circuit substrate later, the solder layer is softened or melted into the concave part in the middle part of the solder layer, and the short circuit caused by overflow of the solder can be effectively avoided.

Step S104: and bonding the LED chip array and the driving substrate through the bonding layer, and stripping the substrate to obtain the LED device.

Embodiments of the present application preferably use a laser lift-off process to lift off the substrate. The bonding layer with the double-layer structure is arranged, so that the chip is effectively prevented from falling off due to melting of solder in the laser stripping process, the bonding temperature is effectively reduced, and the process cost is reduced.

As shown in fig. 2d, after the LED chip array 100 (shown by a dotted line frame) is bonded to the driving substrate 113, the substrate 101, the buffer layer 107, and the U-GaN layer 108 are peeled off by a laser lift-off method, thereby obtaining an LED device. It should be understood that the number of LED chips shown in fig. 2d is merely exemplary and is not limiting herein.

Another embodiment of the present application provides an LED device, which is obtained by using the method for manufacturing an LED device provided in the foregoing embodiments of the present application.

As shown in fig. 3, the LED device 300 includes an LED chip array 100 (shown by a dashed box), a passivation layer 109, a bonding layer, and a driving substrate 113, wherein the LED chip array 100 includes a plurality of LED chips including a first semiconductor layer 102, a multiple quantum well structure 103, a second semiconductor layer 104, a current diffusion layer 105, and an electrode layer 106 stacked from bottom to top; the passivation layer 109 covers the LED chip array 100; an electrode contact hole 110 is formed in the passivation layer 109, and a bonding layer is arranged in the electrode contact hole 110 and is of a double-layer structure; the driving substrate 113 is bonded to the LED chip array 100 and disposed on a side of the LED chip array 100 away from the first semiconductor layer 102. The LED device adopts the bonding layer with the double-layer structure, thereby effectively avoiding falling off due to melting of solder in the laser stripping process and effectively improving the product yield. It should be understood that the number of LED chips shown in fig. 3 is merely exemplary and is not limiting herein.

Alternatively, the bonding layer includes a conductive layer 111 and a solder layer 112, the conductive layer 111 is located between the electrode layer 106 and the solder layer 112, and the conductive layer 111 is made of a high melting point conductive material. Preferably, the thickness ratio of the conductive layer 111 to the solder layer 112 is 1:3-2:1.

Alternatively, the high-melting-point conductive material may be a high-melting-point metallic conductive material or a high-melting-point nonmetallic conductive material, preferably any one of gold-tin alloy, gold, titanium, nickel, aluminum, copper, graphite, graphene.

Alternatively, the high-melting-point conductive material is a high-melting-point solder, preferably any one of gold-tin alloy, gold, titanium, nickel, aluminum, copper.

Optionally, the melting point of the solder layer is lower than the melting point of the conductive layer; the solder layer is preferably any one of indium, tin and silver-tin alloy.

Alternatively, the conductive layer is gold-tin alloy and the solder layer is indium metal. According to the embodiment of the application, the gold-tin alloy is preferably used as a conductive layer material, and the indium is used as a solder layer material, wherein the gold-tin alloy has strong mechanical strength and good heat and electric conduction performance, and the indium is low-temperature solder with excellent performance, has good ductility, high heat conductivity and good wettability and plastic deformation, and the gold-tin alloy/indium bonding layer can effectively prevent a chip from falling off due to melting of the solder in a laser stripping process, and simultaneously effectively reduce bonding temperature, bonding pressure, process cost and bonding reliability. The melting point of indium is low, so that the temperature of a reflux peak can be low when the reflux treatment is carried out in the preparation process, and the energy consumption is effectively reduced; in addition, due to the arrangement of the bonding layer, the use amount of indium can be moderately reduced, so that the reflow time can be shortened, and the reflow energy consumption is further reduced.

Optionally, a recess 1110 is provided in the middle of the conductive layer 111, and the solder layer 112 fills the recess 1110; the cross-sectional shape of the recess 1110 is square, inverted triangle, or inverted trapezoid. The arrangement of the concave part of the conducting layer can effectively avoid overflow of solder of the solder layer during reflow and can effectively reduce the void ratio.

Optionally, the electrode layer 116 includes a first electrode 1161 disposed on the periphery of the LED chip array 100, a second electrode 1062 disposed on the current diffusion layer 105, and metal grid lines 1063 disposed between the LED chips, where the metal grid lines 1063 are electrically connected to the first electrode 1161. The preferred embodiment adopts a common electrode design, namely the LED chip array shares the first electrode, and realizes current collection and transmission through the metal grid lines, thereby effectively improving the current uniformity and the photoelectric performance of the device. In addition, the area of the metal grid lines 1063 covering the first semiconductor layer is smaller, so that the light emitting area is effectively increased, the utilization rate of the epitaxial wafer is improved, and the light emitting efficiency of the LED device is improved.

Optionally, the width of the metal grid lines 1063 is narrower than the first electrode 1061 and/or the second electrode 1062.

Optionally, a bonding layer is disposed on the first electrode 1061 and the second electrode 1062.

Alternatively, the LED chip array 100 is a Micro-LED chip array.

Optionally, a driving control circuit is disposed on the driving substrate 113, and the driving control circuit is electrically connected to a plurality of LED chips.

The LED device provided by the embodiment of the application adopts the bonding layer with the double-layer structure, and the bottom conductive layer adopts the high-melting-point conductive material, so that the chip is effectively prevented from falling off due to melting of the solder in the laser stripping process, in addition, the melting point of the solder layer is lower than that of the conductive layer, and the bonding temperature and the bonding pressure are effectively reduced, the process cost is reduced, and the bonding reliability is improved. In addition, the common electrode design is adopted, namely the LED chip array shares the first electrode, and current collection and transmission are realized through the metal grid lines, so that the current uniformity is effectively improved, and the photoelectric performance of the device is improved. On the other hand, as the area of the metal grid lines covering the first semiconductor layer is smaller, the light emitting area is effectively increased, and the light emitting efficiency of the LED device is improved.

Another embodiment of the present application also provides a display apparatus, which includes the LED device described herein.

The display device provided by the embodiment of the application can realize high PPI and has good device quality, and the display device can be a display screen applied to electronic equipment. The electronic device may include: smart phones, smart watches, notebook computers, tablet computers, automobile recorders, navigator, virtual Reality (VR)/Augmented Reality (AR) displays, and the like.

Another embodiment of the present application also provides a light emitting device. The light emitting device comprises the LED device. The light emitting means may be, for example, a lighting means and an indicating means. The lighting means may be, for example, various lamps for lighting. The indication device may be, for example, various indication lamps for indication, or may be an illumination lamp having a display function.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.

It should be noted that the terms "first," "second," and the like in the description and claims of the present application and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that embodiments of the present application described herein may be capable of being practiced otherwise than as specifically illustrated and described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The foregoing description is only of the preferred embodiments of the present application and is not intended to limit the same, but rather, various modifications and variations may be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. The preparation method of the LED device comprises the following steps:

forming an LED chip array on a substrate, wherein the LED chip array comprises a first semiconductor layer, a multiple quantum well structure, a second semiconductor layer and a current diffusion layer, wherein the first semiconductor layer, the multiple quantum well structure and the second semiconductor layer are sequentially stacked from bottom to top, the current diffusion layer is arranged above the second semiconductor layer, and electrode layers are respectively arranged above the current diffusion layer and the first semiconductor layer;

a passivation layer is integrally arranged above the LED chip array, and electrode contact holes are formed in the passivation layer to expose part of the electrode layer;

a bonding layer is arranged in the electrode contact hole; wherein the bonding layer comprises a conductive layer and a solder layer, and the conductive layer is positioned between the electrode layer and the solder layer; the conductive layer is made of a high-melting-point conductive material;

and bonding the LED chip array and the driving substrate through the bonding layer, and stripping the substrate to obtain the LED device.

2. The method of manufacturing an LED device of claim 1, wherein said forming an array of LED chips on a substrate comprises:

3. The method of manufacturing an LED device according to claim 2, wherein the width of the metal grid lines is narrower than the first electrode and/or the second electrode.

4. The method of manufacturing an LED device according to claim 1 or 2, wherein the passivation layer comprises silicon nitride and/or silicon oxide.

5. The method of manufacturing an LED device according to claim 2, wherein the electrode contact hole is provided above the first electrode and the second electrode.

6. The method of manufacturing an LED device of claim 1, wherein said disposing a bonding layer within said electrode contact hole comprises:

7. The method of manufacturing an LED device of claim 6, wherein said sequentially depositing said conductive layer and said solder layer within said electrode contact hole comprises:

depositing the conductive layer in the electrode contact hole, and forming a concave part in the middle of the conductive layer;

and depositing the solder layer in the concave part.

8. The method of manufacturing an LED device of claim 6, wherein the reflow process comprises:

the reflux treatment is carried out under vacuum or in an oxygen-free atmosphere, wherein the peak reflux temperature is between 156 and 260 ℃; and refluxing for 5-300s at the reflux peak temperature.

9. The method of manufacturing an LED device of claim 1, wherein said high melting point conductive material is a high melting point solder.

10. The method of manufacturing an LED device of claim 1, wherein the solder layer has a melting point lower than that of the conductive layer.

11. The method for manufacturing an LED device according to claim 1, wherein the conductive layer is made of gold-tin alloy and the solder layer is made of indium metal.

12. The method of manufacturing an LED device of claim 1, wherein the thickness ratio of the conductive layer to the solder layer is 1:3-2:1.

13. The method for manufacturing an LED device according to claim 1, wherein the peeling is performed by a laser peeling method.

14. The method of manufacturing an LED device of claim 1, wherein said LED chip array is a Micro-LED chip array.

15. An LED device, wherein the LED device is prepared by the method for preparing an LED device according to any one of claims 1 to 14.

16. The LED device of claim 15, wherein the LED device comprises an LED chip array comprising a plurality of LED chips comprising a first semiconductor layer, a multiple quantum well structure, a second semiconductor layer, a current spreading layer, an electrode layer, stacked from bottom to top; the passivation layer covers the LED chip array; the passivation layer is provided with an electrode contact hole, the bonding layer is arranged in the electrode contact hole, and the bonding layer is of a double-layer structure.

17. The LED device of claim 16, wherein the bonding layer comprises a conductive layer and a solder layer, the conductive layer being located between the electrode layer and the solder layer, the conductive layer being of a high melting point conductive material.

18. The LED device of claim 17, wherein the high melting point conductive material is a high melting point solder.

19. The LED device of claim 17, wherein the solder layer has a melting point that is lower than a melting point of the conductive layer.

20. The LED device of claim 17, wherein the conductive layer is gold-tin alloy and the solder layer is indium metal.

21. The LED device of claim 17, wherein a recess is provided in a middle of the conductive layer, the solder layer being disposed in the recess.

22. The LED device of claim 16, wherein said electrode layer comprises a first electrode disposed on a periphery of said array of LED chips, a second electrode disposed on said current spreading layer, and metal gridlines disposed between said LED chips, said metal gridlines being electrically connected to said first electrode.

23. The LED device of claim 22, wherein the metal gridlines are narrower in width than the first electrode and/or the second electrode.

24. The LED device of claim 22 or 23, wherein the bonding layer is disposed on the first and second electrodes.

25. The LED device of claim 16, wherein said array of LED chips is a Micro-LED chip array.

26. A display apparatus, wherein the display apparatus comprises the LED device of any one of claims 15 to 25.

27. A light emitting apparatus, wherein the light emitting apparatus comprises the LED device of any one of claims 15 to 25.