CN111128942B - Micro light-emitting diode display substrate and preparation method thereof - Google Patents
Micro light-emitting diode display substrate and preparation method thereof Download PDFInfo
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- CN111128942B CN111128942B CN201911229951.5A CN201911229951A CN111128942B CN 111128942 B CN111128942 B CN 111128942B CN 201911229951 A CN201911229951 A CN 201911229951A CN 111128942 B CN111128942 B CN 111128942B
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- H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
- H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
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- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
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- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
- H01L21/4814—Conductive parts
- H01L21/4846—Leads on or in insulating or insulated substrates, e.g. metallisation
- H01L21/485—Adaptation of interconnections, e.g. engineering charges, repair techniques
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- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/48—Manufacture or treatment of parts, e.g. containers, prior to assembly of the devices, using processes not provided for in a single one of the subgroups H01L21/06 - H01L21/326
- H01L21/4814—Conductive parts
- H01L21/4846—Leads on or in insulating or insulated substrates, e.g. metallisation
- H01L21/486—Via connections through the substrate with or without pins
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- H01L25/00—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof
- H01L25/16—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof the devices being of types provided for in two or more different main groups of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. forming hybrid circuits
- H01L25/167—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof the devices being of types provided for in two or more different main groups of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. forming hybrid circuits comprising optoelectronic devices, e.g. LED, photodiodes
Abstract
The application discloses a micro light-emitting diode display substrate and a preparation method thereof. According to the preparation method, the Micro LED structure and the receiving substrate are fixed through an organic adhesive, electrodes are arranged on two sides of the Micro LED structure, an undercut structure is arranged on the electrodes, and an undercut structure is also arranged on the receiving substrate, so that a top electrode and a self-aligned wire for connecting the electrodes between the Micro LED structure and the receiving substrate can be obtained only by depositing electrode materials through an open mask plate, and good insulativity is achieved between the electrodes; the connection between corresponding electrodes between all Micro LED structures and the receiving substrate can be completed at one time, the difference of the connection between each Micro LED structure and the receiving substrate can be avoided, and the device manufacturing yield is improved.
Description
Technical Field
The application relates to the technical field of display, in particular to a micro light-emitting diode display substrate and a preparation method thereof.
Background
A Light Emitting Diode (LED) is a semiconductor element that can convert electric energy into Light in a specific wavelength range. The light emitting principle of the light emitting diode is that the energy difference of electrons moving between an N-type semiconductor and a P-type semiconductor is released in the form of light. The light emitting diode has the advantages of low power consumption, small size, high brightness, easy matching with an integrated circuit, high reliability and the like, and is widely applied as a light source at present. As LED technology matures, LED displays or Micro light emitting diode (Micro LED) displays that directly use LEDs as dot pixels are gradually developed.
The Micro LED display is a self-luminous display which realizes image display by taking a high-density Micro-small-size LED array integrated on a substrate as display pixels, and like an outdoor LED display screen with a large size, each pixel can be addressed and independently driven to be lightened, can be regarded as a reduced version of the outdoor LED display screen, and reduces the distance between pixel points from a millimeter level to a micron level. In the manufacturing process of the Micro LED display, a plurality of Micro LED particles which are miniaturized, thinned and arrayed are grown on a supply substrate (such as a sapphire substrate) by a molecular beam epitaxy method, and then the Micro LED particles are transferred from the supply substrate to a receiving substrate for forming a display panel to be arrayed into a display array.
However, transferring Micro LED particles involves problems of precise transfer, precise binding, etc. of huge and tiny light emitting diodes. In the currently known electrode connection Bonding (Bonding) scheme between the Micro LED and the TFT array substrate (i.e., the receiving substrate), most of the methods are to transfer the Micro LED to the TFT array substrate, and perform electrode Bonding with a pre-patterned Bonding material on the substrate. The electrode is bonded and bound by adopting similar low-melting-point metals such as AuSn and InSn, the bonding and binding are carried out by relating to binding material solid-liquid-solid phase conversion, the binding process is complex, the reliability is low, poor binding is easy to cause, and the repair cost is increased.
Therefore, how to simplify the bonding operation when transferring Micro LED particles, improve the bonding reliability, and improve the device manufacturing yield becomes a technical problem that needs to be improved in the development of the existing Micro LED display technology.
Disclosure of Invention
An object of the application is to provide a Micro light emitting diode display substrate and a preparation method thereof, aiming at the problems existing in the prior art, the bonding operation during the transfer of Micro LED particles can be simplified, the difference of the connection between the Micro LED and a TFT array substrate is avoided, the bonding reliability is improved, and the device manufacturing yield is improved.
In order to achieve the above object, the present application provides a method for manufacturing a micro light emitting diode display substrate, comprising the following steps: providing a substrate base plate; forming a pixel definition layer on the substrate and patterning the pixel definition layer to form a binding hole; forming a bottom electrode layer on the pixel defining layer, wherein the bottom electrode layer comprises a first bottom electrode and a second bottom electrode which are insulated from each other; forming an adhesive layer on the bottom electrode layer corresponding to the binding holes; providing a transfer substrate, wherein the transfer substrate comprises at least one stripping layer and at least one micro light-emitting diode structure, the micro light-emitting diode structure is fixedly connected with the transfer substrate through the stripping layer, the micro light-emitting diode structure comprises a first side electrode and a second side electrode, and the stripping layer and the micro light-emitting diode structure form a first undercut structure at the second side electrode; bonding the micro light emitting diode structure with the bonding layer, and peeling off the transfer substrate; forming a top electrode layer on the peeling layer, wherein the top electrode layer comprises a top electrode, a first self-aligned wire and a second self-aligned wire, and the top electrode is insulated from the second self-aligned wire; the top electrode is connected and bound with the first side electrode and the first bottom electrode through the first self-aligned lead, and the second side electrode is connected and bound with the second bottom electrode through the second self-aligned lead.
In order to achieve the above object, the present application also provides a micro light emitting diode display substrate, including: a substrate base plate; the pixel definition layer is arranged on the substrate base plate and is provided with a binding hole; the bottom electrode layer is arranged on the pixel defining layer and comprises a first bottom electrode and a second bottom electrode which are insulated from each other; the bonding layer is arranged on the bottom electrode layer and corresponds to the binding holes; a micro-LED structure embedded in the adhesive layer, the micro-LED structure including a first side electrode and a second side electrode; the peeling layer is arranged on the micro light-emitting diode structure and forms a first undercut structure with the micro light-emitting diode structure at the second side electrode; the top electrode layer is arranged on the stripping layer and comprises a top electrode, a first self-aligned wire and a second self-aligned wire, and the top electrode is insulated from the second self-aligned wire; the top electrode is connected and bound with the first side electrode and the first bottom electrode through the first self-aligned lead, and the second side electrode is connected and bound with the second bottom electrode through the second self-aligned lead.
The application has the advantages that: the Micro LED structure and the receiving substrate are fixed through an organic adhesive, electrodes are arranged on two sides of the Micro LED structure, and an undercut structure is arranged on the electrodes; the receiving substrate is also provided with a bottom cutting structure, the top electrode and the self-alignment lead for connecting the Micro LED structure and the receiving substrate can be obtained only by adopting an open type mask plate to deposit electrode materials, the operation is relatively simple, good insulativity is achieved between the electrodes, an accurate metal mask plate film deposition technology is not needed, and the production cost is effectively saved. By adopting the preparation method, the connection between all the Micro LED structures and the corresponding electrodes of the receiving substrate can be completed at one time, the difference of the connection between each Micro LED structure and the receiving substrate can be avoided, and the device manufacturing yield is improved. Meanwhile, due to the undercut structure, the formed pixels are effectively ensured to be mutually insulated.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a flow chart of a method for fabricating a micro light emitting diode display substrate according to the present application;
FIGS. 2-14 are flow charts illustrating the fabrication of one embodiment of a micro-LED display substrate according to the present invention;
fig. 15A-15E are flow charts illustrating a method for fabricating a micro led structure according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar components or components having the same or similar functions throughout. The terms "first," "second," "third," and the like in the description and in the claims of the present application, and in the drawings, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the objects so described are interchangeable under appropriate circumstances. Furthermore, the terms "comprising" and "having," as well as any variations thereof, are intended to cover a non-exclusive inclusion. The directional phrases referred to in this application, for example: up, down, left, right, front, rear, inner, outer, lateral, etc., are simply directions with reference to the drawings.
The embodiments described below by referring to the drawings and directional terms used are exemplary only for explaining the present application and are not to be construed as limiting the present application. In addition, examples of various specific processes and materials are provided herein, but one of ordinary skill in the art may recognize applications of other processes and/or use of other materials.
The application provides a Micro light-emitting diode display substrate design, wherein a Micro LED structure and a receiving substrate are fixed through an organic adhesive, electrodes are arranged on two sides of the Micro LED structure, and an undercut structure is arranged on the electrodes; the receiving substrate is also provided with a bottom cutting structure, the top electrode and the self-alignment conducting wire for connecting the Micro LED structure and the electrode between the receiving substrates can be obtained only by adopting an Open Mask (Open Mask) to deposit electrode materials, the operation is relatively simple, the insulation performance between the electrodes is good, an accurate Metal Mask (Fine Metal Mask) film deposition technology is not needed, and the production cost is effectively saved. By adopting the preparation method, the connection between all the Micro LED structures and the corresponding electrodes of the receiving substrate can be completed at one time, the difference of the connection between each Micro LED structure and the receiving substrate can be avoided, and the device manufacturing yield is improved. Meanwhile, due to the undercut structure, the formed pixels are effectively ensured to be mutually insulated.
Referring to fig. 1 and fig. 2 to fig. 14, fig. 1 is a flowchart illustrating a method for manufacturing a micro light emitting diode display substrate according to the present application, and fig. 2 to fig. 14 are flowcharts illustrating a method for manufacturing a micro light emitting diode display substrate according to an embodiment of the present application.
The preparation method comprises the following steps: s11: providing a substrate base plate; s12: forming a pixel definition layer on the substrate and patterning the pixel definition layer to form a binding hole; s13: forming a bottom electrode layer on the pixel defining layer, wherein the bottom electrode layer comprises a first bottom electrode and a second bottom electrode which are insulated from each other; s14: forming an adhesive layer on the bottom electrode layer corresponding to the binding holes; s15: providing a transfer substrate, wherein the transfer substrate comprises at least one peeling layer and at least one micro light-emitting diode structure, a first surface of the micro light-emitting diode structure is fixedly connected with the transfer substrate through the peeling layer, the micro light-emitting diode structure comprises a first side electrode and a second side electrode, and the peeling layer and the micro light-emitting diode structure form a first undercut structure at the second side electrode; s16: bonding the second surface of the micro light emitting diode structure with the bonding layer, and peeling off the transfer substrate; and S17: and forming a top electrode layer on the stripping layer, wherein the top electrode layer comprises a top electrode, a first self-aligned wire and a second self-aligned wire, and the top electrode is insulated from the second self-aligned wire. The top electrode is connected and bound with the first side electrode and the first bottom electrode through the first self-aligned lead, and the second side electrode is connected and bound with the second bottom electrode through the second self-aligned lead.
Regarding step S11: a substrate is provided, and refer to fig. 1 and fig. 2-5. In this embodiment, the substrate includes a TFT layer, that is, the substrate is a TFT array substrate. Specifically, the TFT layer is prepared by the following process:
1) an active layer 211 of the TFT is formed on a first substrate 201 as shown in fig. 2. In one embodiment, an oxide semiconductor film may be deposited on a Glass substrate (Glass) having a Buffer layer (Buffer) and patterned to form an oxide active layer. The oxide semiconductor film layer can be made of the following materials: IGZO, IZO, IGO, IGTO, IGZTO, etc.
2) A gate insulating layer (GI)202 and a Gate Electrode (GE)212 of the TFT are sequentially formed on the first substrate 201, as shown in fig. 3. In one embodiment, a gate insulating material may be deposited and patterned on the first substrate 201 to form the gate insulating layer 202; the gate insulating layer 202 may be a SiOx layer, a SiNx layer, an AlOx layer, or a SiNx/SiOx stack. In one embodiment, a gate metal electrode material may be deposited and patterned on the gate insulating layer 202 to form the gate electrode 212. The grid can be a Cu/Mo lamination, a Cu/MoTi lamination, a Cu/Ti lamination, an Al/Mo lamination, a CuNb alloy and the like.
3) An intermediate dielectric layer (ILD)203 is formed on the first substrate 201, and an opening is performed to form a source drain contact hole 2031, where the intermediate dielectric layer 203 covers the gate electrode 212 and the gate insulating layer 202, as shown in fig. 4. In an embodiment, an intermediate dielectric material may be deposited on the first substrate 201 to form the intermediate dielectric layer 203, and openings may be formed on the intermediate dielectric layer 203 corresponding to two ends of the active layer 211 to form the source/drain contact holes 2031. The intermediate dielectric layer 203 may be a SiOx layer, a SiNx stack, or a SiOx/SiNx stack, etc.
4) A source drain layer (S/D) and a passivation layer (PV)205 are sequentially formed on the middle dielectric layer 203, the source drain layer includes a source (S)213 and a drain (D)214 of the TFT, and a power trace (VSS)215, and the source 213 and the drain 214 are respectively in contact with source/drain contact regions at two ends of the active layer 211, as shown in fig. 5. In one embodiment, a source/drain metal electrode material may be deposited and patterned on the middle dielectric layer 203 to form the source electrode 213, the drain electrode 214, and the power trace 215; the source drain electrode layer can be a Cu/Mo lamination, a Cu/MoTi lamination, a Cu/Ti lamination, an Al/Mo lamination, a CuNb alloy and the like. The passivation layer 205 may be a SiNx layer, a SiOx layer, or a SiOx/SiOx stack, etc.
Regarding step S12: a pixel defining layer is formed on the substrate and patterned to form a binding hole, please refer to fig. 1 and 6. The material of the pixel defining layer 205 may be an organic material. The binding holes 2051 are used to define the binding positions of the Micro LED structures.
In a further embodiment, the pixel definition layer 205 is patterned to form the binding holes 2051, and meanwhile, isolation grooves 2052 are respectively formed on the pixel definition layer 205 corresponding to two sides of the binding holes 2051. The isolation groove 2052 may be used to define an insulated isolation line during subsequent top electrode deposition, and a groove bottom of the isolation groove 2052 may be located in the pixel definition layer 205 or on the passivation layer 205.
Regarding step S13: a bottom electrode layer is formed on the pixel defining layer, and the bottom electrode layer includes a first bottom electrode and a second bottom electrode that are insulated from each other, please refer to fig. 1 and fig. 7. A bottom pixel electrode (PE _ bottom) material may be deposited on the pixel defining layer 205 by using a mask to form the first bottom electrode 221 and the second bottom electrode 222 which are insulated from each other.
In a further embodiment, an opening may be formed on the passivation layer 205 corresponding to the drain electrode 214 and the power trace 215, and then a bottom pixel electrode material is deposited, such that the first bottom electrode 221 is also in contact with the drain electrode 213 and the second bottom electrode 222 is also in contact with the power trace 215.
In a further embodiment, after forming the bottom electrode layer, further comprising: the pixel defining layer 205 is side-etched such that the bottom electrode layer forms a second Undercut (underrout) structure with the pixel defining layer 205 at the isolation groove 2052, i.e. the width (shown in the lateral direction) of the bottom electrode layer is greater than the width of the pixel defining layer 205 at the isolation groove 2052, as shown in fig. 8. The second undercut structure is used for forming discontinuous film formation when the top electrode is deposited at the top in the follow-up process, so that the formed pixels are effectively ensured to be mutually insulated.
In a further embodiment, the pixel defining layer 205 may be side-etched by using O2 plasma, and finally the bottom electrode layer and the pixel defining layer 205 form a chamfer (i.e. the second undercut structure), and this chamfer is used for making the formed film discontinuous when the top electrode is deposited at the top, thereby effectively ensuring that the formed pixels are insulated from each other.
Regarding step S14: an adhesive layer is formed on the bottom electrode layer corresponding to the bonding holes, please refer to fig. 1 and 9. The adhesive layer 206 serves to adhesively secure the Micro LED structure to a subsequently transferred structure. The adhesive layer 206 can be made of a thermosetting organic material, so that after the subsequent Micro LED structure is transferred onto the TFT array substrate, the adhesive layer can be reflowed by further baking with heat, thereby completing a firm adhesion to the Micro LED structure.
Regarding step S15: a transfer substrate is provided, which includes at least one peeling layer and at least one micro led structure thereon, please refer to fig. 1 and fig. 10 together. Specifically, the top of the Micro LED structure 23 is fixedly connected to the transfer substrate 300 through the Lift off layer (Lift off layer)207, and the bottom of the Micro LED structure 23 is used for bonding with the bonding layer 206. The micro led structure 23 includes a first side electrode 231 and a second side electrode 232, the peeling layer 207 forms a first undercut structure with the micro led structure 23 at the second side electrode 232, that is, the peeling layer 207 extends outward from the contact portion with the second side electrode 232 for a certain distance, and finally the peeling layer 207 forms a chamfer shape with the second side electrode 232, and this first undercut structure is used for discontinuing the formed film when the top electrode is deposited uppermost, so that the effective electrodes have good insulation. The release layer 207 serves to secure the Micro LED structures during their movement from the transfer substrate to the receiving substrate (i.e., the TFT array substrate), and is released from the transfer substrate to the receiving substrate along with the Micro LED structures by a release technique (e.g., laser 400 irradiation) after the Micro LED structures are transferred to the receiving substrate.
Regarding step S16: the micro led structure is bonded to the bonding layer, and the transfer substrate is peeled off, as shown in fig. 1 and fig. 11. In this embodiment, the Micro LED structure is moved above the TFT array substrate by a Laser (Laser) -assisted bulk transfer method, and the peeling layer 207 is peeled off from the transfer substrate 300 onto the TFT array substrate together with the Micro LED structure by irradiation of the Laser 400, so that the Micro LED structure is transferred onto the TFT array substrate. The Micro LED structure transferred to the TFT array substrate is provided with the stripping layer 207 on the top, the stripping layer 207 and the Micro LED structure form a chamfer angle at the second side electrode 232, and the formed film forming is discontinuous during the subsequent deposition of a top electrode, so that the electrode fault insulation effect is realized. In other embodiments, the Micro LED structure can be transferred to the TFT array substrate by other bulk transfer methods.
In a further embodiment, the adhesive layer 206 using a thermosetting organic material is further baked, and the adhesive layer 206 reflows, so that the Micro LED structure is embedded in the adhesive layer 206, and the Micro LED structure is firmly adhered to the substrate, as shown in fig. 12.
Regarding step S17: forming a top electrode layer on the peeling layer, wherein the top electrode layer includes a top electrode, a first self-aligned conductive line and a second self-aligned conductive line, and the top electrode is insulated from the second self-aligned conductive line, please refer to fig. 1 and fig. 13 together. In the present embodiment, an Open Mask (Open Mask) is used to deposit a top electrode material on the peeling layer 207, so that the top electrode layer including the top electrode 240, a first Self-aligned (Self-aligned) wire 241 and a second Self-aligned wire 242 can be directly formed, and the top electrode 240 and the second Self-aligned wire 242 are disconnected at the first undercut structure, thereby being insulated from each other. Meanwhile, the top electrode 240 is connected and bonded to the first side electrode 231 and the first bottom electrode 221 through the first self-aligned conductive line 241, and the second side electrode 232 is connected and bonded to the second bottom electrode 222 through the second self-aligned conductive line 242 and insulated from the top electrode 240. The top electrode material may be a transparent conductive material such as ITO, IZO, AZO, or the like, or a metal material.
The application provides a preparation method of a Micro light-emitting diode display substrate, because both a Micro LED structure and a TFT array substrate are provided with bottom cutting structures, and only an open type Mask plate is adopted to deposit an electrode material, a top electrode and a self-alignment wire for connecting the electrode between the Micro LED structure and a receiving substrate can be obtained, the operation is relatively simple, the electrode has good insulating property, an accurate Metal Mask plate (Fine Metal Mask) film deposition technology is not needed, and the production cost is effectively saved. By adopting the preparation method, the connection between all the Micro LED structures and the corresponding electrodes of the receiving substrate can be completed at one time, the difference of the connection between each Micro LED structure and the receiving substrate can be avoided, and the device manufacturing yield is improved. Meanwhile, due to the undercut structure, the formed pixels are effectively ensured to be mutually insulated.
In a further embodiment, an encapsulation layer 208 is formed to encapsulate and protect the micro led display substrate, as shown in fig. 14. The encapsulation layer 208 may be formed by depositing an organic/inorganic material on the micro light emitting diode display substrate.
Based on the same inventive concept, the application also provides a preparation method of the micro light-emitting diode structure. Referring to fig. 15A to 15E, a flow chart of an embodiment of a method for fabricating a micro light emitting diode structure according to the present application is shown. Specifically, the micro light emitting diode structure can be prepared by adopting the following manufacturing process:
1) epitaxial layers 302 of micro-led chips are epitaxially deposited on a second substrate 301 as shown in fig. 15A. The epitaxial layer 302 may be selected to be InGaAlP, InGaN, or the like, depending on the LED emission wavelength.
2) The epitaxial layer 302 is patterned to form at least one micro led chip 303 and a corresponding connecting plate 304, where the connecting plate 304 is formed at the bottom of the micro led chip 303, and extends from the bottom of the micro led chip 303 to two sides to form a first connecting end 3041 and a second connecting end 3042, as shown in fig. 15B. That is, the epitaxial layer 302 is patterned, so that two extending steps (i.e., a first connection end 3041 and a second connection end 3042) are formed at the bottom of the Micro LED chip.
3) An insulating protection layer 305 is formed and opened on the micro led chip 303 and the second connection end 3042, and an electrode contact hole 3051 is formed, as shown in fig. 15C. The insulating protection layer 305 may be formed by depositing a passivation material, and the material of the insulating protection layer 305 may be SiNx, SiOx, or the like.
4) A conductive material is deposited on the insulating protection layer 305 to form a first side electrode 231 and a second side electrode 232, wherein the first side electrode 231 contacts the first connection end 3041, and the second side electrode 232 contacts the micro led chip 303 through the electrode contact hole 3051, as shown in fig. 15D. That is, the top and bottom electrodes of the Micro LED are connected to the electrodes on both sides, respectively, by depositing an electrode conductive material and patterning.
After peeling the second substrate 301, at least one micro led structure 23 is obtained, wherein the micro led structure 23 has a side electrode.
In a further embodiment, the micro led structure 23 is peeled off from the second substrate 301 by Laser Lift-off (LLO) or the like, and the micro led structure 23 is transferred to a transfer substrate 300, wherein the transfer substrate 300 has a Lift-off layer (Lift off layer)207 for Laser transfer, as shown in fig. 15E. The peeling layer 207 serves to fix the micro light emitting diode structures 23 during the movement of the micro light emitting diode structures 23 from the transfer substrate 300 to the receiving substrate (i.e., the TFT array substrate), and is peeled off together with the micro light emitting diode structures 23 from the transfer substrate 300 to the receiving substrate by a peeling technique (e.g., laser irradiation) after the micro light emitting diode structures 23 are transferred to the receiving substrate.
Compared with an ordinary Micro LED, the Micro LED structure manufactured by the manufacturing method of the Micro LED structure has the advantages that the two sides are provided with the side electrodes, the top is provided with the undercut structure (the top is wider than the structure below the undercut structure), so that the top electrode and the self-aligned conducting wire can be formed by depositing the conducting material through the Open Mask, good insulating property is achieved between the electrodes through the self-aligned conducting wire, and the manufacturing yield of devices is improved.
Based on the same inventive concept, the application also provides a micro light-emitting diode display substrate. Referring to fig. 13, the micro light emitting diode display substrate includes: a substrate, a pixel definition layer 205, a bottom electrode layer, an adhesive layer 206, a micro-led structure 23, a release layer 207, and a top electrode layer.
Specifically, the substrate base plate includes: a TFT layer, the TFT layer comprising: an active layer 211 disposed on a first substrate 201; a gate insulating layer 202 disposed on the active layer 211; a gate electrode 212 disposed on the gate insulating layer 202 and corresponding to the active layer 211; an interlayer insulating layer 203 covering the gate electrode 212 and the gate insulating layer 202; and a source drain layer disposed on the interlayer insulating layer 203, the source drain layer including a source 213, a drain 214 and a power trace 215, the source 213 and the drain 214 contacting two ends of the active layer 211, respectively. The substrate base plate further includes: a passivation layer 205, wherein the passivation layer 205 covers the source electrode 213, the drain electrode 214, the power trace 215 and the interlayer insulating layer 203.
The pixel definition layer 205 is disposed on the substrate, and the pixel definition layer 205 has a binding hole 2051 and isolation grooves 2052 located at two sides of the binding hole 2051. The binding holes 2051 are used to define the binding positions of the Micro LED structures. The isolation groove 2052 may be used to define an insulated isolation line during top electrode deposition, and a groove bottom of the isolation groove 2052 may be located in the pixel definition layer 205 or on the passivation layer 205.
The bottom electrode layer is disposed on the pixel defining layer 205, and includes a first bottom electrode 221 and a second bottom electrode 222 that are insulated from each other. The first bottom electrode 221 is also in contact with the drain electrode 214, and the second bottom electrode 222 is also in contact with the power trace 215. The bottom electrode layer forms a second Undercut (underrout) structure with the pixel defining layer 205 at the isolation grooves 2052, so that the subsequently formed self-aligned conductive lines are disconnected at the corresponding isolation grooves 2052, respectively.
The adhesive layer 206 is disposed on the bottom electrode layer and corresponds to the binding hole 2051.
The micro led structure 23 is embedded in the adhesive layer 206, and the micro led structure 23 includes a first side electrode 231 and a second side electrode 232.
The peeling layer 207 is disposed on the micro led structure 23, and forms a first undercut structure with the micro led structure 23 at the second side electrode 232, so that the subsequent top electrode is insulated from the second self-aligned conductive line, and thus the electrodes have good insulation.
The top electrode layer is disposed on the peeling layer 207, the top electrode layer includes a top electrode 240, a first self-aligned conductive line 241 and a second self-aligned conductive line 242, and the top electrode 240 is insulated from the second self-aligned conductive line 242; the top electrode 240 is connected and bonded to the first side electrode 231 and the first bottom electrode 221 through the first self-aligned conductive line 241, and the second side electrode 232 is connected and bonded to the second bottom electrode 222 through the second self-aligned conductive line 242 and insulated from the top electrode 240, i.e., there is good insulation between the electrodes.
This application is little emitting diode display substrates, it is fixed that Micro LED structure passes through organic adhesive with the receiving substrate, Micro LED structure both sides are equipped with the electrode, have undercut structure on it, also have undercut structure on the receiving substrate, therefore, the wire of connecting electrode between Micro LED structure and receiving substrate can realize self-aligning, can avoid every Micro LED structure and receiving substrate to be connected the difference that appears, and the electrode has good insulating nature, effectively guarantee mutual insulation between the pixel that forms, improve the device preparation yield.
The above description of the embodiments is only for assisting understanding of the technical solutions and the core ideas thereof; those of ordinary skill in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications or substitutions do not depart from the spirit and scope of the present disclosure as defined by the appended claims.
Claims (6)
1. A preparation method of a micro light-emitting diode display substrate is characterized by comprising the following steps:
providing a substrate base plate;
forming a pixel definition layer on the substrate and patterning the pixel definition layer to form a binding hole, and forming isolation grooves on the pixel definition layer corresponding to two sides of the binding hole respectively;
forming a bottom electrode layer on the pixel defining layer, wherein the bottom electrode layer comprises a first bottom electrode and a second bottom electrode which are insulated from each other;
performing side etching on the pixel defining layer to enable the bottom electrode layer and the pixel defining layer to form a second undercut structure at the isolation groove, wherein the width of the bottom electrode layer at the isolation groove is larger than that of the pixel defining layer;
forming an adhesive layer on the bottom electrode layer corresponding to the binding holes;
providing a transfer substrate, wherein the transfer substrate comprises at least one peeling layer and at least one micro light-emitting diode structure, the micro light-emitting diode structure is fixedly connected with the transfer substrate through the peeling layer, the micro light-emitting diode structure comprises a first side electrode and a second side electrode, the peeling layer and the micro light-emitting diode structure form a first undercut structure at the second side electrode, and the first undercut structure is formed by that the peeling layer extends outwards for a certain distance from a contact part of the peeling layer and the second side electrode;
bonding the micro light emitting diode structure with the bonding layer, and peeling off the transfer substrate;
depositing a top electrode material on the stripping layer by using an open mask plate to form a top electrode layer, wherein the top electrode layer comprises a top electrode, a first self-aligned conducting wire and a second self-aligned conducting wire, and the top electrode is insulated from the second self-aligned conducting wire;
the top electrode is connected and bound with the first side electrode and the first bottom electrode through the first self-aligned lead, and the second side electrode is connected and bound with the second bottom electrode through the second self-aligned lead.
2. The method of claim 1, wherein the micro-led structure is further formed by:
epitaxially depositing an epitaxial layer of the micro light-emitting diode chip on a substrate;
patterning the epitaxial layer to form at least one micro light-emitting diode chip and a corresponding connecting plate, wherein the connecting plate is formed at the bottom of the micro light-emitting diode chip and extends from the bottom of the micro light-emitting diode chip to two sides to form a first connecting end and a second connecting end respectively;
forming an insulating protective layer on the micro light-emitting diode chip and the second connecting end, and opening a hole to form an electrode contact hole;
depositing a conductive material on the insulating protection layer to form a first side electrode and a second side electrode, wherein the first side electrode is in contact with the first connection end, and the second side electrode is in contact with the micro light-emitting diode chip through the electrode contact hole; and
and stripping the substrate to obtain at least one micro light-emitting diode structure.
3. A micro light emitting diode display substrate, comprising:
a substrate base plate;
the pixel definition layer is arranged on the substrate and provided with a binding hole and isolation grooves positioned on two sides of the binding hole;
the bottom electrode layer is arranged on the pixel defining layer and comprises a first bottom electrode and a second bottom electrode which are insulated from each other;
the bonding layer is arranged on the bottom electrode layer and corresponds to the binding holes;
a micro-LED structure embedded in the adhesive layer, the micro-LED structure including a first side electrode and a second side electrode;
a peeling layer disposed on the micro light emitting diode structure and forming a first undercut structure with the micro light emitting diode structure at the second side electrode, wherein the first undercut structure is formed by the peeling layer extending outward a distance from a contact portion with the second side electrode; and
a top electrode layer disposed on the peeling layer, the top electrode layer including a top electrode, a first self-aligned conductive line and a second self-aligned conductive line, the top electrode being insulated from the second self-aligned conductive line;
the top electrode is connected and bound with the first side electrode and the first bottom electrode through the first self-aligned lead, and the second side electrode is connected and bound with the second bottom electrode through the second self-aligned lead;
the bottom electrode layer and the pixel definition layer form a second undercut structure at the isolation groove, so that the first self-aligned conducting wire and the second self-aligned conducting wire are disconnected at the corresponding isolation groove respectively, wherein the width of the bottom electrode layer at the isolation groove is larger than that of the pixel definition layer.
4. A micro light emitting diode display substrate according to claim 3, wherein the micro light emitting diode structure comprises:
a micro light emitting diode chip;
the connecting plate is arranged at the bottom of the micro light-emitting diode chip and extends from the bottom of the micro light-emitting diode chip to two sides to form a first connecting end and a second connecting end respectively;
the insulating protective layer covers the micro light-emitting diode chip and the second connecting end, and is provided with an electrode contact hole;
the first side electrode is arranged on the insulating protective layer and is in contact with the first connecting end;
and the second side electrode is arranged on the insulating protective layer and is in contact with the micro light-emitting diode chip through the electrode contact hole.
5. The micro light emitting diode display substrate of claim 3, wherein the material of the adhesive layer is a thermally cured organic material.
6. The micro light-emitting diode display submount of claim 3, wherein the submount includes: a TFT layer, the TFT layer comprising:
an active layer disposed on a first substrate;
a gate insulating layer disposed on the active layer;
a gate electrode disposed on the gate insulating layer and corresponding to the active layer;
an interlayer insulating layer covering the gate electrode and the gate insulating layer; and
the source drain layer is arranged on the interlayer insulating layer and comprises a source electrode, a drain electrode and a power supply wire, the source electrode and the drain electrode are respectively contacted with two ends of the active layer, the first bottom electrode is also contacted with the drain electrode, and the second bottom electrode is also contacted with the power supply wire.
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| CN112071830B (en) * | 2020-09-10 | 2021-09-03 | Tcl华星光电技术有限公司 | Substrate and method for manufacturing substrate |
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| CN107170773A (en) * | 2017-05-23 | 2017-09-15 | 深圳市华星光电技术有限公司 | Micro- LED display panel and preparation method thereof |
| CN109786307A (en) * | 2017-11-15 | 2019-05-21 | 鸿富锦精密工业（深圳）有限公司 | The preparation method of miniature LED display panel |
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| US10068888B2 (en) * | 2015-12-21 | 2018-09-04 | Hong Kong Beida Jade Bird Display Limited | Making semiconductor devices with alignment bonding and substrate removal |
| CN106941108B (en) * | 2017-05-23 | 2019-09-17 | 深圳市华星光电技术有限公司 | Micro- LED display panel and preparation method thereof |
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| CN107170773A (en) * | 2017-05-23 | 2017-09-15 | 深圳市华星光电技术有限公司 | Micro- LED display panel and preparation method thereof |
| CN109786307A (en) * | 2017-11-15 | 2019-05-21 | 鸿富锦精密工业（深圳）有限公司 | The preparation method of miniature LED display panel |
| CN110520832A (en) * | 2019-07-10 | 2019-11-29 | 京东方科技集团股份有限公司 | The micro- light emitting display device of touch-control, the method for operating the micro- light emitting display device of touch-control, and the method for the manufacture micro- light emitting display device of touch-control |
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