Patent Description:
The disclosure relates to the field of display technology, and in particular relates to a display backboard and a manufacturing method thereof, and a display device.

A Micro-Light Emitting Diode (abbreviated as Micro-LED or µLED) display technology is used to reduce a size of an existing LED to be less than <NUM>, which has a size of about <NUM>% of that of the existing LED. The micron-sized Micro-LEDs of RGB three-colors are transferred to a driving substrate by a mass transfer technology, such that Micro-LED displays with various sizes are manufactured.

Each Micro-LED pixel can be addressed and independently driven to emit light, and a distance between adjacent pixels is reduced from millimeter level to micrometer level. The Micro-LED has the advantages of self-luminescence, high brightness, high contrast, ultrahigh resolution and color saturation, long service life, high response speed, energy conservation, wide application range in environment and the like. The Micro-LED display technology can cover a range from micro display such as Augmented Reality (abbreviated as AR) or Virtual Reality (abbreviated as VR), medium-sized display such as mobile phone and television, to large-screen display in cinema.

<CIT>, <CIT> and <CIT> disclose insert bonding tip configurations according to the prior art.

In one aspect, a display backboard is provided to include: a driving substrate; a plurality of driving electrodes on the driving substrate; a plurality of connection structures on the plurality of driving electrodes respectively, an orthographic projection of each of the plurality of connection structures on the driving substrate being within an orthographic projection of a corresponding driving electrode on the driving substrate, wherein the connecting structure includes: at least one conductive component on the driving electrode, wherein an area of a first cross-section of the at least one conductive component is negatively correlated to a distance between the first cross-section and a surface of the driving substrate, and the first cross-section is parallel to the surface of the driving substrate; and a restriction component on a side of the driving electrode provided with the at least one conductive component and at least in a part of a peripheral region of the at least one conductive component, wherein the restriction component protrudes from the driving electrode and has a first height in a direction perpendicular to the driving substrate.

In some embodiments, a difference between the first height and a second height of the at least one conductive component in a direction perpendicular to the driving substrate is in a range of about <NUM> microns to about <NUM> microns.

In some embodiments, the restriction component is made of a conductive material.

In some embodiments, the at least one conductive component is spaced from the restriction component.

In some embodiments, the connection structure further includes a conductive connection component on the driving electrode and between the at least one conductive component and the restriction component.

In some embodiments, each of the at least one conductive component includes a main body on the driving electrode and a conductive layer covering an entire surface of the main body; and the conductive connection component, the restriction component, and the conductive layer are made of a same conductive material.

In some embodiments, each of the at least one conductive component includes a main body on the driving electrode and a conductive layer covering the entire surface of the main body except for a part of the surface of the main body distal to the driving electrode; and the conductive connection component, the restriction component, and the conductive layer are made of a same conductive material.

In some embodiments, the at least one conductive component is in direct contact with the restriction component on a surface of the driving electrode.

In some embodiments, each of the at least one conductive component includes a main body on the driving electrode and a conductive layer covering an entire surface of the main body; and the restriction component and the conductive layer are made of a same conductive material.

In some embodiments, each of the at least one conductive component includes a main body on the driving electrode and a conductive layer covering an entire surface of the main body except for a part of the surface of the main body distal to the driving electrode; and the restriction component and the conductive layer are made of a same conductive material.

In some embodiments, a height of the conductive layer in a direction perpendicular to the driving substrate is approximately equal to a height of the restriction component in the direction perpendicular to the driving substrate.

In some embodiments, a material of the main body is copper, aluminum, or nickel, and a material of the conductive layer is molybdenum or copper.

In some embodiments, the restriction component surrounds the at least one conductive component, and an orthographic projection of the restriction component on the driving substrate is a hollow closed pattern.

In some embodiments, the closed pattern is circular or rectangular, and the restriction component has a thickness in a range of about <NUM> microns to about <NUM> microns in a direction parallel to a plane in which the driving substrate is located.

In some embodiments, the at least one conductive component has a shape of pyramid.

In some embodiments, the at least one conductive component has a shape of cone.

In some embodiments, the driving substrate is provided with a plurality of driving transistors; each of the plurality of driving transistors includes a source, a drain, a gate, and an active layer, and the driving transistor is configured to control a corresponding driving electrode by its drain being coupled to the driving electrode.

In another aspect, a display device is provided to include the display backboard above and a plurality of micro light emitting diodes, wherein each of the plurality of micro light emitting diodes includes a first electrode and a second electrode, which are respectively coupled to two adjacent connection structures on the display backboard.

In some embodiments, the restriction components of the two adjacent connection structures are provided at least on opposite sides of the two adjacent connection structures.

In some embodiments, the plurality of micro light emitting diodes are arranged in an array of multiple rows and columns; the display backboard includes connecting structures of multiple rows and columns corresponding to the plurality of micro light emitting diodes; the restriction components of two adjacent connecting structures in a same column are at least provided on opposite sides of the two adjacent connecting structures; and the restriction components of two adjacent connection structures in a same row are at least provided on opposite sides of the two adjacent connection structures.

In another aspect, a method for manufacturing a display backboard is provided to include: forming a plurality of driving electrodes on a driving substrate; forming a connection structure on each of the plurality of driving electrodes, such that an orthographic projection of the connection structure on the driving substrate is within an orthographic projection of the corresponding driving electrode on the driving substrate, wherein the forming a connection structure on each of the plurality of driving electrodes includes: forming at least one conductive component on the driving electrode, such that an area of a first cross-section of the at least one conductive component is negatively correlated to a distance between the first cross-section and a surface of the driving substrate, and the first cross-section is parallel to the surface of the driving substrate; and forming a restriction component on a side of the at least one conductive component provided with the driving electrode and at least in a part of a peripheral region of the at least one conductive component, wherein the restriction component protrudes from the driving electrode and has a first height in a direction perpendicular to the driving substrate.

In some embodiments, the forming at least one conductive component on the driving electrode includes: forming a first photoresist pattern on the driving substrate provided with the driving electrode, to form a first via hole exposing the driving electrode at a position on the driving electrode where the at least one conductive component is to be formed; forming a metal pillar in the first via hole; forming a second photoresist pattern on the metal pillar such that the second photoresist pattern has a diameter smaller than that of the metal pillar; and performing an etching process on the metal pillar to form at least one conductive component by using the second photoresist pattern as a mask, wherein the forming a restriction component on a side of the at least one conductive component provided with the driving electrode and at least in a part of the peripheral region of the at least one conductive component includes: removing the first photoresist pattern and the second photoresist pattern; forming a restriction structure on the driving electrode at least in the part of the peripheral region of the at least one conductive component; depositing a metal material on an exposed sidewall of the restriction structure to form the restriction component at least in the part of the peripheral region of the at least one conductive component, wherein the forming a restriction structure on the driving electrode at least in the part of the peripheral region of the at least one conductive component includes: sequentially forming a planarization layer and a first metal layer on the driving substrate from which the first photoresist pattern and the second photoresist pattern are removed, such that a height of the planarization layer in a direction perpendicular to the driving substrate is greater than that of the at least one conductive component; forming a third photoresist pattern on the first metal layer, and performing an etching process on the first metal layer to form a first metal pattern; and performing an etching process on the planarization layer by using the first metal pattern as a mask, such that a surface of the at least one conductive component distal to the driving electrode and the exposed sidewall on which the restriction component is to be formed are exposed, thereby forming the restriction structure.

In some embodiments, the depositing a metal material on an exposed sidewall of the restriction structure to form the restriction component at least in the part of the peripheral region of the at least one conductive component includes: removing the third photoresist pattern, and forming a second metal layer on a sidewall of the planarization layer, a surface of the at least one conductive component distal to the driving electrode and the exposed driving electrode; coating a fourth photoresist layer on the entire surface of the driving substrate provided with the second metal layer; performing a plasma treatment on the fourth photoresist layer in an oxygen atmosphere to thin the fourth photoresist layer to a selected thickness, to expose an entire top surface of the second metal layer and a part of the side surface proximal to the top surface of the second metal layer, and to maintain the fourth photoresist covering the at least one conductive component or maintain a top of the at least one conductive component exposed by the fourth photoresist layer; and etching away a part of the second metal layer uncovered by the fourth photoresist layer and the first metal layer pattern such that the at least one conductive component is prevented from being etched, wherein a part of the second metal layer on the sidewall of the planarization layer and covered by the fourth photoresist layer functions as the restriction component.

The drawings are used to provide a further understanding of the present disclosure, and constitute a part of the specification, together with the following specific embodiments to explain the present disclosure, but do not constitute a limitation of the present disclosure. In the drawings:.

The specific embodiments of the present disclosure will be described in detail below with reference to the drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

A size of each Micro-LED in a Micro-LED display device is typically less than or equal to <NUM> micrometers (µm). A distance between two adjacent Micro-LEDs in the Micro-LEDs arranged in an array is also in micrometer level. Therefore, how to improve bonding efficiency and reliability of the Micro-LED and the corresponding driving electrode in the display backboard has become a very important issue in the process of transferring each Micro-LED onto the display substrate.

For this purpose, according to one aspect of the present disclosure, a display backboard is provided. As shown in <FIG> the display backboard includes: a driving substrate <NUM>; a plurality of driving electrodes <NUM> on the driving substrate <NUM>; and a plurality of connection structures respectively on the plurality of driving electrodes <NUM>. An orthogonal projection of each of the plurality of connection structures on the driving substrate <NUM> is within an orthogonal projection of the corresponding driving electrode <NUM> on the driving substrate <NUM>. The connection structure includes at least one conductive component <NUM> and a restriction component <NUM>. The at least one conductive component <NUM> is provided on the driving electrode <NUM>. An area of a first cross-section of the at least one conductive component <NUM> is negatively correlated to a distance between the first cross-section and a surface of the driving substrate <NUM>. The first cross-section is parallel to the surface of the driving substrate. The restriction component <NUM> is on a side of the driving electrode <NUM> provided with the at least one conductive component <NUM> and at least in a part of peripheral region of the at least one conductive component <NUM>. The restriction component <NUM> protrudes from the driving electrode <NUM> and has a first height in a direction perpendicular to the driving substrate <NUM>. In some embodiments, an included angle between the restriction component <NUM> and a plane where the driving substrate <NUM> is located is in a range of <NUM>° to <NUM>°. In this case, the restriction component <NUM> can also be considered to be almost perpendicular to the driving substrate <NUM>.

The display backboard of the present disclosure includes a plurality of connection structures, and each connection structure is configured to be coupled to an electrode pin of an electronic device for controlling the electronic device. The connection structure in the display backboard of the present disclosure includes a conductive component for an electrical connection and a restriction component. The conductive component is made of a conductive material to be electrically coupled to an electrode pin of an electronic device. The restriction component is provided in the periphery of the conductive component and restricts a bonding material for electrically coupling the conductive component to the pin of the electronic device. When the conductive component on the display backboard is electrically coupled to the electrode pin of the electronic device (e.g., a Micro-LED) by the above configuration, the bonding material is blocked by the restriction component and is restricted in a predetermined area without overflowing, such that a short circuit can be avoided, as shown in <FIG>.

The at least one conductive component <NUM> on the driving electrode <NUM> may include one or more conductive components <NUM>. <FIG>, <FIG>, <FIG>, <FIG> each are a perspective view of a restriction component <NUM> surrounding one conductive component <NUM>. <FIG>, <FIG>, <FIG>, and <FIG> are top views of <FIG>, <FIG>, <FIG>, <FIG>, respectively. <FIG>, <FIG> are cross-sectional views of <FIG>, <FIG>, <FIG> along lines A-A', B-B', C-C', D-D', E-E', and F-F', respectively. <FIG>, <FIG> each are perspective views of a restriction component <NUM> surrounding three conductive components <NUM>. Of course, the number of conductive components <NUM> surrounded by the restriction component <NUM> can be set as required.

The fact that the orthographic projection of each of the plurality of connection structures on the driving substrate <NUM> is located within the orthographic projection of the corresponding driving electrode <NUM> on the driving substrate <NUM> means that the orthographic projection of each of the connection structures on the driving substrate <NUM> substantially entirely falls into the orthographic projection of the corresponding driving electrode <NUM> on the driving substrate <NUM>; or the orthographic projection of each of the connection structures on the driving substrate <NUM> at least partially falls into the orthographic projection of the corresponding driving electrode <NUM> on the driving substrate <NUM>, and there is a partial overlap between the orthographic projections of each of the connection structures and of the corresponding driving electrode <NUM>.

The fact that the restriction component <NUM> is located in at least a part of the peripheral region of the at least one conductive component <NUM> means that the restriction component <NUM> is provided at least in a part of the peripheral region of the conductive component <NUM>. For example, as shown in <FIG>, in two adjacent connection structures corresponding to two electrodes (P and N) of an LED chip <NUM>, the restriction components <NUM> of the two connection structures are only provided on opposite sides of the two adjacent connection structures, so as to avoid a short circuit caused by a contact of the overflowed bonding material when bonding the two electrodes. For example, when the driving electrode <NUM> has a shape of a rectangle and the conductive component <NUM> provided on the driving electrode has a shape of cone, the restriction component <NUM> may be a columnar protrusion provided only on one edge side of the rectangle. <FIG> shows that the restriction components <NUM> of two adjacent connecting structures are respectively columnar protrusions on the adjacent edges of the two adjacent driving electrodes, which are similar to two dams. During bonding, the two retaining walls restrict the bonding material corresponding to the two electrodes on the respective driving electrodes without laterally overflowing onto the adjacent driving electrodes, so as to effectively avoid short circuit caused by undesired bonding material contact. As shown in <FIG>, the restriction component <NUM> should have a size in a direction perpendicular to an arrangement direction of two adjacent driving electrodes, which is generally equal to or greater than a size of the conductive component in a direction perpendicular to the arrangement direction to effectively realize bonding isolation.

Optionally, as shown in <FIG>, for the driving electrodes arranged in multiple rows, it also takes into consideration of a bonding isolation between the electrodes of two LED chips adjacent in a column direction when the connection structures are provided on the driving electrodes. At this time, as shown in <FIG>, the restriction components of the connection structures are provided not only on the opposite sides of the connection structures adjacent in the row direction but also on the opposite sides of the connection structures adjacent in the column direction. In <FIG>, the restriction component <NUM> includes three parts on three edges of a rectangular driving electrode, which semi-encloses the conductive component therein. The three parts may be coupled end to end, as shown in <FIG>. Optionally, the three parts may not be in contact with each other but isolated from each other. As described above, the restriction component <NUM> is a protrusion extruding from the surface of the driving electrode and having a first height. There is a gap between the restriction component and the conductive component inside the restriction component, which can be used to contain the bonding material during bonding. The bonding material for each electrode is restricted in the gap formed by its corresponding connecting structure, thereby avoiding an undesired short circuit due to overflowing of the bonding material to the adjacent connecting structure in the row direction or the column direction.

Of course, as shown in <FIG>, <FIG>, <FIG>and <FIG>, the restriction component may be provided around the entire periphery of the at least one conductive component <NUM>, resulting in a best bonding isolation. The structures shown in <FIG> and <FIG> occupy less area of the surface of the driving electrode.

A driving transistor is provided on the driving substrate <NUM>, and is coupled to the driving electrode <NUM> for supplying an electric signal to the driving electrode. Specifically, in some embodiments, as shown in <FIG>, the driving substrate <NUM> includes a base <NUM>; a buffer layer <NUM> on the base <NUM>; an active layer <NUM> on the buffer layer <NUM>; a gate insulating layer <NUM> on the active layer <NUM> and on the buffer layer <NUM>; a gate <NUM> on the gate insulating layer <NUM> corresponding to the active layer <NUM>; a dielectric layer <NUM> on the gate <NUM> and the gate insulating layer <NUM>; a source <NUM> and a drain <NUM> on the dielectric layer <NUM>, which are coupled to the active layer <NUM> through via holes in the gate insulating layer <NUM> and the dielectric layer <NUM>, respectively; a planarization layer <NUM> on the source <NUM>, the drain <NUM>, and the dielectric layer <NUM>; and a passivation layer <NUM> on the planarization layer <NUM>. The driving electrode <NUM> is coupled to the drain <NUM> through the via hole in the planarization layer <NUM> and the passivation layer <NUM>. In the embodiment, the driving transistor is a top gate transistor. The present application is not limited thereto, and a bottom gate transistor may be used. Of course, the driving electrodes <NUM> may be provided on other types of substrates as required.

As shown in <FIG>, when the LED chip <NUM> is bonded by the bonding material <NUM> by using the connection structure of the present disclosure, the LED chip <NUM> may be bonded to the driving substrate <NUM> by using the combined structure of the conductive component <NUM> and the restriction component <NUM> of the present disclosure. First, the top of the conductive component <NUM> is aligned with the bonding material <NUM> at the position of the electrodes (P and N) of the LED chip <NUM> in a vertical direction. The bonding material <NUM> is usually a soft metal such as indium or tin, and the bonding material <NUM> is usually prepared on the LED chip <NUM> by thermal evaporation. Then, the top of the conductive component <NUM> is penetrated into the bonding material <NUM> at the position of electrode (P and N) of the LED chip <NUM>. After the top of the conductive component <NUM> is penetrated into the bonding material <NUM>, the bonding material <NUM> overflows laterally and spreads to the periphery of the top of the conductive component <NUM>. The spreading bonding material <NUM> is blocked by the restriction component <NUM> and enters the gap formed by the conductive component <NUM> and the restricting component <NUM>. Then, a low-temperature treatment (for example, a low-temperature treatment for <NUM> minutes) is performed in a vacuum atmosphere at a temperature of about <NUM> below a melting point of the metal of the bonding material <NUM>, such that an inter-diffusion between the metal in the bonding material <NUM> and the metal in the conductive component <NUM> and the restriction component <NUM> occurs. Due to the presence of the restriction component <NUM>, the bonding materials <NUM> at the positions of the N electrode and the P electrode of the LED chip <NUM> can be prevented from contacting each other when a lateral overflow of the bonding material <NUM> occurs, thereby preventing a short circuit from occurring between the N electrode and the P electrode of the LED chip <NUM>. In this way, even if the pitch between the pins of the two electrodes of each LED chip <NUM> or the electrodes of the two adjacent LED chips <NUM> is very small, the bonding material <NUM> can be restricted by the restriction component and the conductive component of the connection structure in the embodiment of the present application, and no overflow occurs, thereby solving the problem of bonding short circuit due to a small pitch. Therefore, the connection structure of the present disclosure is particularly suitable for micro light emitting diodes.

In some embodiments, a difference between a second height of the conductive component <NUM> in a direction perpendicular to the driving substrate <NUM> and the first height of the restriction component <NUM> in the direction perpendicular to the driving substrate <NUM> is in a range from about <NUM> micrometers to about <NUM> micrometers. As shown in <FIG>, and <FIG>, the second height of the conductive component <NUM> is equal to the first height of the restriction component <NUM>. As shown in <FIG>, and <FIG>, the second height of the conductive component <NUM> is greater than the first height of the restriction component <NUM>. In some examples, the height of the conductive component <NUM> may be in a range of <NUM> to <NUM> micrometers, and the height of the restriction component <NUM> may be in a range of <NUM> to <NUM> micrometers. In one specific example, the height of the conductive component <NUM> may be <NUM> micrometers, and the height of the restriction component <NUM> may be <NUM> micrometers.

In some embodiments, the restriction component <NUM> may be made of a conductive material just like the conductive component <NUM>, such that both the surface of the conductive component <NUM> and the surface of the restriction component <NUM> can be in electrical contact with the bonding material <NUM>, thereby increasing the electrical contact area, reducing the resistance, and reducing the power consumption. However, the present application is not limited thereto, and the restriction component <NUM> introduced in the present application is intended to avoid short circuit between the bonding materials corresponding to the adjacent connecting structures, and all structures that restrict the overflow of the bonding materials therein are within the scope of the present application. For example, the restriction component <NUM> is not limited to being made of a conductive material, but may be made of an insulating material, in which case the restriction component <NUM> is only used to avoid short circuit between the bonding materials corresponding to the adjacent connection structures and cannot affect the electrical connection of the driving electrodes <NUM> and the electrodes (P and N) of the LED chip <NUM>.

In some embodiments, the conductive component <NUM> is spaced apart from the restriction component <NUM>. As shown in <FIG>, the conductive component <NUM> is not in contact with the restriction component <NUM> on the surface of the driving electrode <NUM>.

In some embodiments, the connection structure further includes a conductive connection component <NUM> on the driving electrode <NUM> and between the conductive component <NUM> and the restriction component <NUM>. As shown in <FIG>, the conductive component <NUM> and the restriction component <NUM> are coupled to each other on the surface of the driving electrode <NUM> by a conductive connection component <NUM>. In this case, the restriction component <NUM>, the conductive connection component <NUM> and the conductive component <NUM> may be made of a same conductive material. Optionally, the restriction component <NUM>, the conductive connection component <NUM> and the conductive component <NUM> may be integrally made of a same conductive material, resulting in a simple manufacturing process.

In some embodiments, the conductive component <NUM> includes a main body <NUM> on the driving electrode <NUM> and a conductive layer <NUM> covering the entire surface of the main body, as shown in <FIG>. The conductive connection component <NUM>, the restriction component <NUM>, and the conductive layer <NUM> may be made of a same conductive material. In this case, the main body <NUM> may be made of a non-conductive material, and the conductive connection component <NUM>, the restriction component <NUM>, and the conductive layer <NUM> may be simultaneously manufactured in one process.

In some embodiments, the conductive component <NUM> includes a main body <NUM> on the driving electrode <NUM> and a conductive layer <NUM> covering the entire surface of the main body <NUM> except for a part of the surface (e.g., the part of the tip end of the main body <NUM>) distal to the driving electrode <NUM>, as shown in <FIG>. In this case, the main body <NUM> may be made of a conductive material to increase an electrical contact area with the bonding material and reduce contact resistance. The conductive connection component <NUM>, the restriction component <NUM> and the conductive layer <NUM> may be made of a same conductive material. Optionally, the restriction component <NUM>, the conductive connection component <NUM> and the conductive layer <NUM> may be integrally formed by a same conductive material, resulting in a simple manufacturing procedure. For example, the height of the conductive layer <NUM> in a direction perpendicular to the driving substrate may be approximately equal to the first height.

In some embodiments, the conductive component <NUM> and the restriction component <NUM> may be in direct contact on the surface of the driving electrode <NUM>. In some embodiments, the conductive component <NUM> may include a main body <NUM> on the driving electrode <NUM> and a conductive layer <NUM> covering the entire surface of the main body, as shown in <FIG>. Optionally, the conductive component <NUM> includes a main body <NUM> on the driving electrode <NUM> and a conductive layer <NUM> covering the surface of the main body <NUM> except for a part of the surface (e.g., a surface of a tip end of the main body <NUM>) distal to the driving electrode <NUM>, as shown in <FIG>. The restriction component <NUM> and the conductive layer <NUM> may be made of a same conductive material. The height of the conductive layer <NUM> in <FIG> in a direction perpendicular to the driving substrate <NUM> is equal to the first height, i.e. the height of the overall conductive component <NUM> is the height of the conductive layer <NUM> in the direction perpendicular to the driving substrate <NUM>. The height of the conductive layer <NUM> in <FIG> in the direction perpendicular to the driving substrate <NUM> is approximately equal to the first height, i.e. the height of the entire conductive component <NUM> is greater than the first height.

In some embodiments, a material of the main body <NUM> is copper, aluminum or nickel, and a material of the conductive layer <NUM> is molybdenum or copper. Of course, other materials may be selected as desired to prepare the corresponding main body and conductive layer. For example, as described above, when the conductive layer is provided on the entire surface of the conductive component <NUM>, the main body inside the conductive layer may be made of a non-conductive material.

The materials of the main body, the conductive layer, and the restriction component are not limited in the present application as long as the prepared connection structure can satisfy the required strength and conductivity.

In some embodiments, when the restriction component <NUM> surrounds the at least one conductive component <NUM>, the orthographic projection of the restriction component <NUM> on the driving substrate may be a closed pattern. In a specific example, the closed pattern is a hollow circular or rectangular shape, such as a tubular structure, e.g. a circular or square tube, as shown in <FIG>. And, a thickness d of the restriction component <NUM> in a direction parallel to the plane where the driving substrate <NUM> is located is in a range of about <NUM> micrometers to about <NUM> micrometers, as shown in <FIG>.

In some embodiments, the conductive component <NUM> has a shape of pyramid. For example, as shown in <FIG>, the horizontal cross-section of the conductive component <NUM> is circular, i.e. the conductive component <NUM> has a shape of cone. However, the present disclosure is not limited thereto, and the conductive component <NUM> may also be another type of pyramid whose cross-section in a horizontal direction is rectangular, triangular, or the like.

According to one aspect of the present disclosure, there is provided a method for manufacturing the above-described display backboard. As shown in <FIG>, the method includes the following steps S110, S120, and S <NUM>.

In step S110, a plurality of driving electrodes <NUM> are formed on the driving substrate <NUM>.

For example, as shown in <FIG>, an electrode layer is formed on the driving substrate <NUM> by sputtering or deposition, and then is patterned to form a plurality of driving electrodes <NUM>.

<FIG> only schematically shows the driving substrate <NUM>. As shown in <FIG>, the driving transistor and the electrode wire are formed on the driving substrate <NUM>. The drain of the driving transistor and the electrode wire are respectively coupled to the driving electrodes formed on the surface of the driving substrate <NUM> through a conductive material in via holes.

In step S120, at least one conductive component <NUM> is formed on the driving electrode <NUM>. The area of a first cross-section of the at least one conductive component <NUM> is negatively correlated to a distance between the first cross-section and the surface of the driving substrate <NUM>. The first cross-section is parallel to the surface of the driving substrate <NUM>.

In step S130, the restriction component <NUM> is formed on a side of the driving electrode <NUM> provided with the at least one conductive component <NUM> to surround at least a part of the at least one conductive component <NUM>. The restriction component <NUM> protrudes from the driving electrode <NUM> and has a first height in a direction perpendicular to the driving substrate <NUM>.

The conductive component <NUM> and the restriction component <NUM> formed as described above are provided as a connection structure on the corresponding driving electrode, and the orthographic projection of the whole connection structure on the driving substrate is within the orthographic projection of the driving electrode on the driving substrate.

<FIG> is a diagram illustrating a process flow of a method for manufacturing a display backboard according to an embodiment of the disclosure, and <FIG> are schematic diagrams of structures obtained at various steps in the process flow of the method for manufacturing the display backboard according to an embodiment of the disclosure. The method for manufacturing the display backboard shown in <FIG> will be described in detail with reference to <FIG> and <FIG>.

In one embodiment, the method for manufacturing a display backboard of the present application includes steps S201 to S214.

In step S201, at least one driving electrode <NUM> is formed on the driving substrate <NUM>, as shown in <FIG>.

In step S202, a first photoresist pattern <NUM> is formed on the driving substrate <NUM> on which the at least one driving electrode <NUM> is formed, to form a first via hole <NUM> exposing the driving electrode <NUM> at a position on the driving electrode <NUM> where at least one conductive component <NUM> is to be formed. Specifically, first, a photoresist layer is coated on the entire driving substrate <NUM> on which the at least one driving electrode <NUM> is formed, and the thickness of the photoresist layer may be determined by the height of the conductive component <NUM> to be formed. For example, the height of the conductive component <NUM> to be formed is <NUM>, and the thickness of the photoresist layer may be <NUM>. Then, the photoresist layer is subjected to an exposure process and a development process to form a first photoresist pattern <NUM>, such that a first via hole <NUM> exposing the driving electrode <NUM> is formed at a position on the driving electrode <NUM> where the at least one conductive component <NUM> is to be formed, as shown in <FIG>.

In step S203, a metal pillar <NUM> is formed in the first via hole <NUM>. Specifically, as shown in <FIG>, the metal pillar <NUM> may be formed on the exposed part of the driving electrode <NUM> (i.e., in the first via hole <NUM>) by using an electroplating process. For example, Cu ions may be deposited by using an electroplating process to form a copper pillar, but the present disclosure is not limited thereto and other processes may be used to form a metal pillar of any other material (e.g., aluminum, nickel, etc.).

In step S204, a second photoresist pattern <NUM> having a diameter smaller than that of the metal pillar <NUM> is formed on the metal pillar <NUM>. Specifically, as shown in <FIG>, a photoresist pattern is coated on the metal pillar <NUM>, and the coated photoresist pattern has a size smaller than that of the metal pillar <NUM>. That is, the photoresist pattern coated on the metal pillar <NUM> completely falls into the top surface of the metal pillar <NUM>, and a center of the photoresist pattern coated on the metal pillar <NUM> and a center of the top surface of the metal pillar may be on a same vertical line. For example, if the coated photoresist pattern and the metal pillar <NUM> are both polygons similar to each other, the length of the diagonal line of the coated photoresist pattern is smaller than the length of the diagonal line of the metal pillar <NUM>; if the coated photoresist pattern and the metal pillar <NUM> are both circular, the diameter of the coated photoresist pattern is smaller than the diameter of the metal pillar <NUM>.

In step S205, the metal pillar <NUM> is etched by using the second photoresist pattern <NUM> as a mask to form the at least one conductive component <NUM>. Specifically, the metal pillar <NUM> is etched by using a wet etching process and by using the second photoresist pattern <NUM> as a taper mask (spike mask) to obtain the conductive component <NUM>, as shown in <FIG>.

In step S206, the first photoresist pattern <NUM> and the second photoresist pattern <NUM> are removed, thereby forming the conductive component <NUM>, as shown in <FIG>.

In step S207, a planarization layer <NUM> and a first metal layer <NUM> are sequentially formed on the driving substrate <NUM> from which the first and second photoresist patterns <NUM> and <NUM> are removed, and the height of the planarization layer <NUM> in a direction perpendicular to the driving substrate <NUM> is at least greater than the height of the conductive component <NUM>. Specifically, a resin is first coated to form the planarization layer <NUM>, and the thickness of the planarization layer <NUM> after being cured is ensured to be greater than the height of the conductive component <NUM>. Then, a metal (e.g., molybdenum) is deposited on the planarization layer <NUM> to form the first metal layer <NUM>, as shown in <FIG>.

In step S208, a third photoresist pattern <NUM> is formed on the first metal layer <NUM>, and the first metal layer <NUM> is etched to form a first metal pattern <NUM>'. Specifically, first, a photoresist layer is coated on the first metal layer <NUM>, and is patterned to form the third photoresist pattern <NUM>. Then, the first metal layer <NUM> is etched by using the third photoresist pattern <NUM> as a mask, thereby forming the first metal pattern <NUM>', as shown in <FIG>.

In step S209, the planarization layer <NUM> is etched by using the first metal pattern <NUM>' as a mask to expose the entire surface of the conductive component <NUM> distal to the driving substrate <NUM> and expose the sidewall on which the restriction component is to be formed. Specifically, the planarization layer <NUM> may be etched by using the first metal pattern <NUM>' as a hard mask to form a planarization layer pattern <NUM>', thereby exposing substantially the entire surface of the conductive component <NUM> distal to the surface of the driving substrate <NUM>, as shown in <FIG>. The planarization layer <NUM> and the first metal layer <NUM> form a restriction structure where they are etched, and the restriction structure is subsequently used to form the restriction component.

In step S210, the third photoresist pattern <NUM> is removed, and a second metal layer <NUM> is formed on the entire driving substrate <NUM>. Specifically, a metal (e.g., molybdenum Mo) may be deposited by using a sputtering process to form a second metal layer <NUM> covering the entire surface of the driving substrate <NUM>, as shown in <FIG>. The second metal layer <NUM> can then be used to form the restriction component <NUM>, and the second metal layer <NUM> is required to have a thickness that is capable of maintaining a shape when the sidewall of a support on a back surface is removed. For example, when molybdenum is used to form the second metal layer <NUM>, the thickness of the side wall (i.e., in a direction parallel to the plane where the driving substrate <NUM> is located) is required to be in a range of <NUM> to <NUM>.

In step S211, a fourth photoresist layer <NUM> is coated on the entire surface of the driving substrate <NUM> on which the second metal layer <NUM> is provided, as shown in <FIG>.

In step S212, the fourth photoresist layer <NUM> is plasma-treated in an oxygen atmosphere to thin the fourth photoresist layer <NUM> to a selected thickness, so as to expose a part of the second metal layer <NUM>, and the height of a thinned fourth photoresist pattern <NUM>' is lower than that of the first metal layer pattern <NUM>'.

Specifically, the fourth photoresist layer <NUM> is directly subjected to a plasma treatment in an oxygen atmosphere to thin the thickness of the fourth photoresist layer <NUM>. By controlling the time of the plasma treatment in the oxygen atmosphere and the ion concentration, the fourth photoresist pattern <NUM>' having a selected thickness can be obtained. For example, after the fourth photoresist layer <NUM> is thinned, the top surface and a part of the side surface close to the top surface of the second metal layer <NUM> can be exposed, and it is also ensured that the height of the remaining fourth photoresist pattern <NUM>' at the exposed position of the conductive component <NUM> is greater than the height of the conductive component <NUM>, that is, the remaining fourth photoresist pattern <NUM>' covers the conductive component <NUM>, as shown in <FIG>. Optionally, in an embodiment, after the thickness of the fourth photoresist layer <NUM> is thinned, it is further ensured that the height of the conductive component <NUM> is greater than the thickness of the fourth photoresist pattern <NUM>' remaining at the exposed position of the conductive component <NUM>, i.e. the top of the conductive component <NUM> is exposed from the fourth photoresist pattern <NUM>', as shown in <FIG>.

In step S213, the second metal layer <NUM> uncovered by the fourth photoresist pattern <NUM>' and the first metal layer pattern <NUM>' under the second metal layer <NUM> are etched away, and the second metal layer <NUM> at the sidewall covered by the fourth photoresist pattern <NUM>' forms the restriction component <NUM>. Specifically, the second metal layer <NUM> and the first metal layer pattern <NUM>' that are not covered by the fourth photoresist pattern <NUM>' may be removed by using a wet etching process, as shown in <FIG>. Since the fourth photoresist pattern <NUM>' covers the second metal layer <NUM> at the sidewall, the height of the formed restriction component <NUM> is restricted by the thickness of the fourth photoresist pattern <NUM>', i.e., the fourth photoresist pattern <NUM>' achieves self-alignment of the restriction component <NUM> in height.

In step S214, the planarization layer <NUM> and the fourth photoresist layer <NUM> are removed to form a final connection structure. As shown in <FIG> and <FIG>, the height of the restriction component <NUM> of the connection structure may be in a range of <NUM> to <NUM>, and the thickness d may be in a range of <NUM> to <NUM>; the height of the conductive component <NUM> may be in a range of <NUM> to <NUM>. For example, the height of the conductive component <NUM> may be <NUM>, and the height of the restriction component <NUM> may be <NUM>. As shown in <FIG>, the top of the conductive component <NUM> is exposed from the conductive layer <NUM>, so that the conductive component <NUM> is in direct contact with for example the subsequent LED chip <NUM>. Thus, when the conductive component <NUM> is made of copper, aluminum or the like, and the conductive layer <NUM> is made of molybdenum or the like, since the resistivity of copper or aluminum is smaller than that of molybdenum, the contact resistance between the LED chip <NUM> and the connection structure can be reduced.

In the connection structure of the display backboard formed by the above process, the second metal layer <NUM> formed between the restriction component <NUM> and the conductive component <NUM> may be used as a part of the conductive layer <NUM> or the conductive connection component <NUM> to connect the restriction component <NUM> and the conductive component <NUM> together, as shown in <FIG>. Optionally, the second metal layer <NUM> may be deposited only on the above-mentioned sidewall, forming a connection structure as shown in <FIG> in which the restriction component <NUM> and the conductive component <NUM> are not connected to each other.

The present invention is not limited to the above-described manufacturing method, and for example, the restriction component <NUM> may be formed by using a non-conductive material, in which case the restriction component only plays a role of restricting the bonding material.

According to one aspect of the present disclosure, a display device is provided, which includes the above-mentioned display backboard and a plurality of micro light emitting diodes. As shown in <FIG>, each of the micro light emitting diodes includes a first electrode pin N drawn from an N region and a second electrode pin P drawn from a P region, i.e., a first electrode and a second electrode. The first and second electrodes are coupled to two connection structures on the display backboard by a bonding material <NUM>, respectively, as shown in <FIG>. The display backboards in <FIG> correspond to the display backboards in <FIG>, respectively.

A plurality of pairs of driving electrodes are usually provided on the display backboard, and each pair of driving electrodes correspond to two electrode pins N and P of one micro light emitting diode, so as to ensure that each driving electrode can be electrically coupled to the corresponding electrode pin through the corresponding connecting structure. For example, the orthographic projections of the first electrode pin N and the second electrode pin P on the driving substrate are within the orthographic projection of the corresponding driving electrodes on the driving substrate.

In the embodiment, the first electrode pin N of the micro light emitting diode is electrically coupled to the drain <NUM> of the transistor on the driving backboard by the bonding material <NUM>, and the second electrode pin P is electrically coupled to the electrode wire <NUM> on the driving backboard by the bonding material <NUM>, such that the micro light emitting diode is controlled by the driving substrate. The electrode wire <NUM> may be formed by a same one patterning process and by using a same material as the source <NUM> and the drain <NUM> of the driving transistor.

As shown in <FIG>, the conductive component <NUM> serving as an electrical contact in each connection structure is configured as a conical structure with a relatively sharp end, so that when bonding is performed, the conductive component can be effectively penetrated into the bonding material coated on the corresponding electrode pin to ensure a good electrical contact between the conductive component and the corresponding electrode pin. The bonding material expands toward the periphery after the electrical contact between the conductive component and the corresponding electrode pin occurs.

In some embodiments, the restriction component <NUM> of two adjacent connection structures are at least on opposite sides of the two adjacent connection structures, i.e. the orthographic projection of the restriction component <NUM> on the driving substrate is a non-closed pattern. For example, the restriction component <NUM> may be provided only on one side of the conductive component <NUM>, that is, the restriction component <NUM> may be provided only at a position where an undesired short circuit of the bonding material may occur, as shown in <FIG>. In two adjacent connection structures, the restriction component is provided only on opposite sides (e.g., opposite sides of a and a') of the two adjacent connection structures for avoiding a short circuit of the bonding material between the two adjacent connection structures.

In some embodiments, a plurality of micro light emitting diodes are arranged in an array of multiple rows and columns. The restriction components of the connecting structures corresponding to two adjacent micro light emitting diodes on a same column each are located in the peripheral region of the at least one conductive component at least on two adjacent opposite sides of the adjacent micro light emitting diodes in the same column; and the restriction components of the connecting structures corresponding to two adjacent micro light emitting diodes on a same row each are located in the peripheral region of the at least one conductive component at least on two adjacent opposite sides of the two adjacent micro light emitting diodes in the same row. As shown in <FIG>, when the connection structures arranged in an array are included on the display backboard, the restriction components are only provided on two opposite sides (e.g., opposite sides b and b', c and c') of two adjacent connection structures in a same column or a same row for avoiding a short circuit of the bonding material between the adjacent connection structures.

In the present application, since the display device has the connection structure shown in the display backboard in <FIG>. That is, the connection structure includes the conductive component <NUM> and the restriction component <NUM> in the periphery of the conductive component <NUM>, and a gap is defined between the conductive component <NUM> and the restriction component <NUM>. When a micro light emitting diode <NUM> is bound to the display backboard by a bonding material <NUM>, the bonding material <NUM> is restricted inside the restriction component <NUM> by the restriction component <NUM>, so that the bonding material <NUM> is prevented from overflowing, the problem of a bonding short circuit caused by a small pitch between electrodes can be solved, the contact area between the bonding electrodes can be increased, the resistance is reduced, and the power consumption is reduced.

Claim 1:
A display backboard, comprising:
a driving substrate (<NUM>);
a plurality of driving electrodes (<NUM>) on the driving substrate (<NUM>);
a plurality of connection structures on the plurality of driving electrodes (<NUM>) respectively, an orthographic projection of each of the plurality of connection structures on the driving substrate (<NUM>) being within an orthographic projection of a corresponding driving electrode (<NUM>) on the driving substrate (<NUM>),
characterized in that the connecting structure comprises:
at least one conductive component (<NUM>) on the driving electrode (<NUM>), wherein an area of a first cross-section of the at least one conductive component (<NUM>) is negatively correlated to a distance between the first cross-section and a surface of the driving substrate (<NUM>), and the first cross-section is parallel to the surface of the driving substrate (<NUM>); and
a restriction component (<NUM>) on a side of the driving electrode (<NUM>) provided with the at least one conductive component (<NUM>) and at least in a part of a peripheral region of the at least one conductive component (<NUM>), wherein the restriction component (<NUM>) protrudes from the driving electrode (<NUM>) and has a first height in a direction perpendicular to the driving substrate (<NUM>).