TWI881580B - Display apparatus with array of light emitting diodes and method of manufacturing the same - Google Patents

Abstract

A display apparatus includes a substrate having a plurality of electrical controlling devices, an array of light-emitting diodes having a semiconductor layer and a plurality of light-emitting units disposed on the semiconductor layer, a plurality of first electrodes disposed on the semiconductor layer, an adhesive layer disposed between the substrate and the array of light-emitting diodes, and a plurality of wavelength converting elements disposed on the semiconductor layer and spaced apart from each other, wherein the wavelength converting elements and the light-emitting units are disposed at different sides of the semiconductor layer, and the wavelength converting elements are positioned correspondingly to the light-emitting units.

Description

Display device with light-emitting diode array and manufacturing method thereof

The present invention relates to a display and a manufacturing method thereof, and in particular to a display having a light-emitting diode array and a manufacturing method thereof.

With the maturity and evolution of light-emitting diode (LED) technology, the technology of full-color LED display or micro LED display that directly uses LED to achieve self-luminous display pixels is also booming. Its application field is wider than TFT-LCD, including flexible and transparent displays. It is a highly feasible next-generation flat-panel display technology. However, in commercialization, there are still many cost and technical bottlenecks that need to be overcome. For example, a display with an active light-emitting diode array is known, which uses contacts (bumps) on the electrodes to electrically connect a driving substrate and a light-emitting diode array. However, this connection method is not only difficult to process, but also difficult to align the contacts with the electrodes of the light-emitting diodes. Furthermore, there is no substrate supporting the driving substrate and the LED array, so the substrate (such as a sapphire substrate) used to form the LED array cannot be removed. The presence of the substrate will affect the optical signal between pixels, causing cross-talk and affecting the display quality.

The present invention relates to a display having a light-emitting diode array and a manufacturing method thereof. In an embodiment, a bonding layer is formed between a driving substrate and a light-emitting diode array, so that the crystal growth substrate originally used to form the light-emitting diode array can be removed after the bonding layer is set, thereby solving the problem of mutual interference of optical signals between pixels.

According to one embodiment, a display is provided, comprising a substrate having a plurality of electronically controlled elements; a light emitting diode array (LED array), comprising a semiconductor layer and a plurality of light emitting units formed on the semiconductor layer; a plurality of first electrodes formed on the semiconductor layer; a bonding layer formed between the substrate and the light emitting diode array; and a plurality of wavelength conversion elements formed on the semiconductor layer and located on different sides of the semiconductor layer from the light emitting units, the positions of the wavelength conversion elements corresponding to the positions of the light emitting units, wherein the wavelength conversion elements are separated from each other by a distance.

According to one embodiment, a display is provided, comprising: a substrate having a plurality of electronic control elements; a light-emitting diode array (LED array), comprising a semiconductor layer and a plurality of light-emitting units formed on the semiconductor layer; a plurality of first electrodes formed on the semiconductor layer; and a bonding layer, comprising a bonding material and a plurality of connecting metals located in the bonding material, the bonding material is filled between the substrate and the light-emitting diode array, and the connecting metal comprises: a plurality of first portions corresponding to the light-emitting units, and a plurality of second portions corresponding to at least a portion of the first electrodes, wherein the height of the first portions is different from the height of the second portions.

According to an embodiment, a method for manufacturing a display is provided, comprising: providing a substrate having a plurality of electric control elements; forming a plurality of connecting conductors on the substrate, wherein the connecting conductors include a plurality of first portions and a plurality of second portions; providing a light-emitting diode array, wherein the light-emitting diode array includes a semiconductor layer and a plurality of light-emitting units formed on the semiconductor layer; assembling the light-emitting diode array and the substrate; forming a bonding layer between the substrate and the light-emitting diode array; and forming a plurality of wavelength conversion elements on the semiconductor layer, wherein the wavelength conversion elements and the light-emitting units are located on different sides of the semiconductor layer, wherein the positions of the wavelength conversion elements correspond to the positions of the light-emitting units, and the wavelength conversion elements are spaced a distance from each other. The aforementioned step of forming the bonding layer can be performed before or after the step of assembling the LED array and the substrate.

In order to better understand the above and other aspects of the present invention, the following is a specific example and a detailed description with the attached drawings as follows:

21: Substrate

22: Pad

221: First control pad

222: Second control pad

31: LED array

LU: Light emitting unit

310: Crystal growth substrate

311, 313: semiconductor layer

311a: first surface

311b: Second surface

313a: Surface of the second conductive semiconductor layer

312:Active stack

315: Insulation layer

316: First electrode

316P: Conductive pad

316C:Connection part

3161, 3162: Routing

317: Second electrode

40, 50: bonding layer

41, 51: bonding materials

42, 52: Connecting metal

421, 521: Part 1

422, 522: Part 2

d1: Height of the first part

d2, d2’: Height of the second part

45: Wavelength conversion element

45R: Red wavelength conversion element

45G: Green wavelength conversion element

45B: Blue wavelength conversion element

46: Waterproof layer

410: Non-conductive colloid

420: Conductive particles

PR: Photoresist

PR’: Patterned photoresist

OM: Opaque material

Figure 1 shows a top view of a light-emitting diode array and electrodes according to an embodiment of the present invention.

Figure 2 is a schematic cross-sectional view of a display according to an embodiment of the present invention, wherein the LED array and the electrode are depicted along the cross-sectional line 2-2 of Figure 1.

Figures 3A-3E illustrate a method for manufacturing a display according to an embodiment of the present invention.

Figures 4A-4C show an example of a method for manufacturing a wavelength conversion element in an embodiment of the present invention.

Figure 5 is a schematic cross-sectional view of a display of another embodiment of the present invention.

Figure 6 is a cross-sectional schematic diagram of a display of another embodiment of the present invention.

Figure 7 is a cross-sectional schematic diagram of a display of another embodiment of the present invention.

Figures 8A and 8B illustrate a bonding process of an embodiment of the present invention.

Figure 9 is a schematic cross-sectional view of a display according to another embodiment of the present invention.

Figures 10A-10F illustrate one method of manufacturing the display shown in Figure 9.

Figures 11A-11G illustrate another method of manufacturing the display shown in Figure 9.

Figure 12 shows a top view of a light-emitting diode array and electrodes according to another embodiment of the present invention.

FIG. 13 is a schematic cross-sectional view of a display device according to an embodiment of the present invention, wherein the LED array and the electrode are depicted along the cross-sectional line 13-13 of FIG. 12.

In an embodiment of the disclosure, a display having an LED array and a manufacturing method thereof are provided, wherein a bonding layer is formed between a driving substrate (e.g., a CMOS substrate) and an LED array. The bonding layer includes a connecting metal and a bonding material. The connecting metal can provide an electrical connection between the driving substrate and the LED array, while the bonding material fills the gap between the driving substrate and the LED array and provides support. Therefore, in the display of the embodiment, the crystal growth substrate (such as a sapphire substrate) originally used to form the LED array can be removed after the bonding layer is set, and then, if required by the application, a wavelength conversion layer (such as a wavelength conversion element including quantum dot fluorescent powder) can be formed on the semiconductor layer on a surface different from the surface where the light-emitting unit is located to achieve full color. Therefore, compared with the traditional structure, the display proposed in the embodiment not only has a bonding material that can provide support between the driving substrate and the LED array, but also improves the reliability of the overall structure. Since the crystal growth substrate is removed, in addition to reducing the overall thickness of the display, the flexibility of the display can also be increased, making it more widely used. If applied to the manufacture of micro-LED arrays (for example, each micro-LED corresponds to a sub-pixel), the display structure without a crystal growth substrate as proposed in the embodiment can avoid cross talk of optical signals between sub-pixels. Furthermore, the manufacturing method proposed in the embodiment can be applied to the filling and electrical conduction between LEDs with the same or different electrode horizontal positions (/horizontal heights) (especially N-electrodes and P-electrodes with different horizontal positions/horizontal heights) and the driving substrate, and the formation of the connecting metal and the bonding material in the bonding layer will not cause damage to the related layers and components in the structure, and there is no need to adopt time-consuming and expensive manufacturing procedures. Therefore, the structure and manufacturing method proposed in the embodiment are suitable for mass production.

The embodiments of this disclosure have a wide range of applications. The following embodiments are illustrated using a display having a micro-LED array, but the disclosure is not limited to these aspects. The following are related embodiments, with illustrations to illustrate in detail the related structures and manufacturing methods of the display proposed in the disclosure. Furthermore, the same or similar numbers in the embodiments are used to indicate the same or similar parts for the sake of clarity. However, the description of the proposed implementation aspects, such as detailed structures, process steps, and material applications, etc., are only for illustrative purposes, and the scope of protection of the disclosure is not limited to the described aspects. This disclosure does not show all possible embodiments. People in the relevant field may change and modify the structure and process of the embodiments within the spirit and scope of this disclosure to meet the needs of actual applications. Therefore, other embodiments not proposed in this disclosure may also be applicable. Furthermore, the drawings have been simplified to facilitate the clear description of the contents of the embodiments, and the size ratios in the drawings are not drawn in proportion to the actual products. Therefore, the instructions and illustrations are only used to describe the embodiments, and are not used to limit the scope of protection of this disclosure.

Furthermore, the ordinal numbers used in the specification and the claim, such as "first", "second", etc., are used to modify the elements of the claim. They do not imply or represent any previous ordinal numbers of the claim element, nor do they represent the order of one claim element and another claim element, or the order of the manufacturing method. The use of these ordinal numbers is only used to make a claim element with a certain name clearly distinguishable from another claim element with the same name. In addition, when it is mentioned that a first material layer is located on, above or above a second material layer, unless specifically defined, it may include the situation where the first material layer and the second material layer are in direct contact. Alternatively, there may be a situation where there are one or more other material layers in between, in which case the first material layer and the second material layer may not be in direct contact.

Figure 1 is a top view of a light-emitting diode array and electrodes according to an embodiment of the present invention. In this embodiment, a light-emitting diode array arranged in a matrix is proposed, such as but not limited to a micro-LED array, with a plurality of light-emitting units LU as shown in the figure, and the N electrode is made into a metal grid (n-metal). grid) is an example; the N electrode, for example, includes: a plurality of conductive pads 316P (for example, N pads, four conductive pads 316P are used as an example in FIG. 1, but not limited thereto) located outside the light-emitting diode array, and a plurality of extensions located between adjacent light-emitting units LU, including metal traces 3161 extending along a first direction D1 (for example, X direction), and metal traces 3162 extending along a second direction D2 (for example, Y direction), and these extensions are electrically connected to the corresponding conductive pads 316P. The grid-shaped N electrode can reduce the series resistance value and make the series resistance value of each pixel current path reach nearly the same. However, the present disclosure is not limited to this N electrode state.

In addition, in actual manufacturing, the LED array can be cut from a wafer (LED wafer) containing LEDs. For example, to produce a 1K*1K LED array, 1000 LEDs need to be placed in both directions of the array. After cutting, the array is then connected to a driving substrate (such as a CMOS substrate). Of course, the present disclosure is not limited to this. In another manufacturing example, a whole wafer (LED wafer) containing LEDs can also be connected to a driving substrate (such as a CMOS substrate). In FIG. 1, the periphery of the LED array, such as the four corners, is formed with cross-shaped alignment marks for alignment when the driver substrate is connected to the wafer with the LEDs; in this example, the alignment marks are formed, for example (but not limited to), at the end of the conductive pad 316P.

FIG. 2 is a schematic cross-sectional view of a display according to an embodiment of the present invention, wherein the LED array and the electrodes are shown along the section line 2-2 of FIG. 1. A display according to an embodiment includes a LED array 31 bonded to a substrate 21 having a plurality of electronically controlled elements. The substrate 21 is, for example, a complementary metal oxide semiconductor backplane (CMOS backplane) or any substrate having a control circuit, which is electrically connected to the LED array to control the current of each pixel. The LED array 31 has a semiconductor layer 311 and a plurality of light emitting units LU formed on the semiconductor layer 311; and a plurality of first electrodes 316, for example, N electrodes (N electrodes) are formed on the semiconductor layer 311. The display of the embodiment further includes an adhesive layer 40 formed between the substrate 21 and the LED array 31. As shown in FIG. 2, the adhesive layer 40 includes an adhesive material 41 (e.g., a non-conductive gel) and a plurality of connecting metals 42 located in the adhesive material 41. The adhesive material 41 fills the gap between the substrate 21 and the LED array 31, and can provide support after the substrate 21 and the LED array 31 are joined, and can properly prevent moisture from corroding the electrode and entering the material layer of the LED.

In an embodiment, the connection metal 42 may include a first portion 421 corresponding to the light-emitting unit LU, and a second portion 422 corresponding to at least a portion of the first electrode 316. As shown in FIG. 2, the connection metal 42 includes a plurality of first portions 421 corresponding to the light-emitting units LU, and a plurality of second portions 422 corresponding to the conductive pads 316P located outside the light-emitting diode array 31 in the first electrode 316. That is, the second portion 422 of the connection metal 42 corresponds to the conductive pads 316P. The height d1 of the first portion 421 is different from the height d2 of the second portion 422.

Furthermore, the display of the embodiment further includes a plurality of second electrodes 317, such as P electrodes (P electrodes) formed on each light-emitting unit LU, wherein the first portion 421 of the connection metal 42 is connected to the second electrode 317. In this example of the micro light-emitting diode array, the P electrode (such as the second electrode 317) is formed on each light-emitting unit LU, and the N electrode (such as the first electrode 316) is shared by a plurality of light-emitting units LU. The materials of the first electrode 316 and the second electrode 317 can be transparent conductive materials or metal materials. Transparent conductive materials include but are not limited to indium tin oxide (ITO), indium oxide (InO), tin oxide (SnO), cadmium tin oxide (CTO), antimony tin oxide (ATO), aluminum zinc oxide (AZO), tin zinc oxide (ZTO), gallium zinc oxide (GZO), indium tungsten oxide (IWO), zinc oxide (ZnO), aluminum gallium arsenide (AlGaAs), gallium nitride (GaN), gallium phosphide (GaP), gallium arsenide (GaAs), gallium arsenide phosphide (GaAsP), indium zinc oxide (IZO), and diamond-like carbon (DLC). Metal materials include but are not limited to aluminum (Al), chromium (Cr), copper (Cu), tin (Sn), gold (Au), nickel (Ni), titanium (Ti), platinum (Pt), lead (Pb), zinc (Zn), cadmium (Cd), antimony (Sb), cobalt (Co), and alloys thereof.

In this example, the substrate 21 (having the control circuit) has, for example, a plurality of pads 22. The other end of the connection metal 42 of the bonding layer 40 is connected to the pad 22 on the substrate 21. As shown in FIG. 2, the pads of the substrate 21 may include a plurality of first control pads 221 and a plurality of second control pads 222, wherein each first portion 421 of the connection metal 42 is electrically connected to the first control pad 221 and the second electrode (e.g., P electrode) 317, respectively, and each second portion 422 of the connection metal 42 is electrically connected to the second control pad 222 and the conductive pad 316P (i.e., the first electrode 316, e.g., N electrode) located outside the LED array 31. In this example, the conductive pad 316P also has a connecting portion 316C, so the second portion 422 of the connecting metal 42 is electrically connected to the conductive pad 316P (i.e., the first electrode 316) through the connecting portion 316C. Furthermore, in this example, the thickness of the connecting portion 316C may be equal to or different from the thickness of the second electrode 317; for example, as shown in FIG. 2, the thickness of the connecting portion 316C is slightly greater than the thickness of the second electrode 317, but the present disclosure does not specifically limit this.

In addition, in this example, the horizontal position of the first electrode 316 such as the conductive pad 316P is different from the horizontal position of the second electrode 317 (for example, the horizontal position of the conductive pad 316P is closer to the semiconductor layer 311), and the connecting portion 316C on the conductive pad 316P is also closer to the semiconductor layer 311 than the second electrode 317. Therefore, in the bonding layer 40 shown in Figure 2, the height d1 of the first portion 421 of the connecting metal 42 is smaller than the height d2 of the second portion 422. However, the electrode configuration of the light-emitting diode applicable in the embodiment is not limited to the example of Figure 2. The height d1 of the first part 421 of the connection metal 42 and the height d2 of the second part 422 will be adjusted according to the changes in the electrode configuration and the thickness of the relevant layers in actual application. The embodiment disclosed in this disclosure is actually applicable to any structural configuration with different or even the same height d1 and d2. Furthermore, although the connection portion 316C is formed as an example in this embodiment, in other embodiments, the first electrode (for example, the conductive pad 316P) may not have the connection portion 316C, and this disclosure does not impose any restrictions on this.

Furthermore, the applicable LED structural aspects in the embodiments include the number and configuration of the relevant semiconductor layers and quantum well layers, the electrode settings, the materials of each layer, and the color of light emitted after the materials are excited, etc. The present disclosure does not impose any restrictions, and FIG. 2 simply illustrates one of the applicable LED structural aspects. As shown in FIG. 2, an example semiconductor layer 311 is, for example, a first conductivity type semiconductor layer, and each light emitting unit LU includes an active stack 312 (e.g., multiple quantum wells (MQW)) and a second conductivity type semiconductor layer 313 formed on the active stack 312, wherein the second electrode 317 is formed on the second conductivity type semiconductor layer 313 of each light emitting unit LU. In an example, the first conductivity type and the second conductivity type are, for example, N-type and P-type, respectively.

In an embodiment, the first conductive semiconductor layer 311 and the second conductive semiconductor layer 313 are, for example, cladding layers or confinement layers, which can provide electrons and holes respectively, so that the electrons and holes are combined in the active stack 312 to emit _light . The first conductive semiconductor layer 311, the active stack 312, and the second conductive semiconductor layer 313 can include III-V semiconductor materials, such as _{AlxInyGa (1-xy)} N or _AlxInyGa (1- _{xy )} P, where 0≦x, y≦1; (x+y)≦1. Depending on the material of the active stack 312, the light emitting unit LU can emit red light with a peak between 580nm and 700nm, green light with a peak between 530nm and 570nm, blue light with a peak between 450nm and 490nm, or UV light with a peak between 380nm and 420nm, such as 400nm. In one example, the first conductive semiconductor layer 311 is N-GaN, the active stack 312 is a multiple quantum well (MQW), and the second conductive semiconductor layer 313 is P-GaN. Each light-emitting unit LU emits blue light with a peak value between 450nm and 490nm. Full colorization can then be achieved through the provision of wavelength conversion elements such as red wavelength conversion elements and green wavelength conversion elements including quantum dot phosphors (QD phosphors).

Furthermore, in one example, the display further includes an insulating layer 315 covering the semiconductor layer 311 and the light-emitting unit LU, and the insulating layer 315 exposes a portion of the surface 313a of the second conductive type semiconductor layer 313 of each light-emitting unit LU, and each second electrode 317 (e.g., P electrode) is formed on the surface 313a and contacts the second conductive type semiconductor layer 313, wherein the first portion 421 of the connection metal 42 of the bonding layer 40 is respectively connected to the second electrode 317 of each light-emitting unit LU, as shown in FIG. 2.

According to the embodiment disclosed in the present invention, in addition to the connection metal 42 in the bonding layer 40 providing electrical connection between the substrate 21 and the LED array 31, the bonding material 41 in the bonding layer 40 fills the gap between the substrate 21 and the LED array 31 to provide support. Therefore, the crystal growth substrate (such as a sapphire substrate) originally used to form the LED array can be removed after forming the bonding layer 40 (including forming the connection metal 42), and then a wavelength conversion element 45, such as quantum dot phosphors (QD phosphors), can be formed on the semiconductor layer 311 on a surface different from the light-emitting unit LU to complete full colorization. The following is a method for manufacturing a display for example.

Figures 3A-3E illustrate a method for manufacturing a display according to an embodiment of the present invention. The same reference numerals are used for the same components as those in Figure 2 for the sake of clarity. As shown in Figure 3A, a substrate 21 (e.g., a CMOS backplane) and a light-emitting component (e.g., an LED wafer) are provided, respectively. The light-emitting component includes a crystal growth substrate 310 and the aforementioned light-emitting diode array 31, an insulating layer 315, a first electrode 316, and a second electrode 317. For the details of the configuration of the components included in the substrate 21 and the light-emitting diode array 31, please refer to the above content and will not be repeated here. In one example, the crystal growth substrate 310 is, for example, a patterned sapphire substrate, and an epitaxial layer including, for example, gallium nitride (GaN) can be grown using, for example, metal organic chemical-vapor deposition (MOCVD).

Afterwards, a bonding layer 40 is formed, including bonding material 41 and a plurality of connection metals 42, between the substrate 21 and the light-emitting diode array 31, as shown in FIG. 3B. The connection metal 42 includes a first portion 421 corresponding to the light-emitting unit LU, and a second portion 422 corresponding to the first electrode, such as the conductive pad 316P. For the configuration details of the connection metal 42, please refer to the above content, which will not be elaborated here.

After the substrate 21 and the light-emitting component (such as an LED wafer) including the light-emitting diode array 31 are bonded, the bonding material 41 fills the gap between the substrate 21 and the light-emitting component for support. Then, as shown in FIG. 3C , the crystal growth substrate 310 can be removed. In one example, the crystal growth substrate 310 can be removed by laser lift-off.

Afterwards, as shown in FIG. 3D, due to the support of the bonding material 41, a wavelength conversion element 45 can be formed on the semiconductor layer 311 on the surface where different light-emitting units LU are located. The material thereof is, for example, a quantum dot (QD, which is a highly efficient fluorescent light-emitting crystal). In one example, when the QD is excited by short-wavelength (high-energy) blue light, it will emit long-wavelength (low-energy) photons. The emitted photons have a narrow spectrum distribution and an adjustable peak value. The size of the QD can be controlled by controlling the process, and the peak value and size distribution can be adjusted to have a narrow spectrum distribution characteristic, thereby achieving conversion of different light colors. For example, in an example where the light-emitting unit LU includes a blue light GaN layer, a plurality of red wavelength conversion elements 45R and a plurality of green wavelength conversion elements 45G can be included. A red wavelength conversion element 45R (emitting red light with a peak value between 580nm and 700nm) is arranged on a light-emitting unit LU, a green wavelength conversion element 45G (emitting green light with a peak value between 530nm and 570nm) is arranged on a light-emitting unit LU, and a light-emitting unit LU without a wavelength conversion element thereon (the blue light GaN layer emits blue light with a peak value between 450nm and 490nm) constitutes an RGB pixel, thereby forming multiple RGB pixels to achieve full-color display. In one example, the semiconductor layer 311 has a first surface 311a and a second surface 311b (i.e., upper and lower surfaces) facing each other, wherein the first surface 311a faces the substrate 21; and the light-emitting unit LU is formed on the first surface 311a, and the wavelength conversion element 45 (e.g., the red wavelength conversion element 45R and the green wavelength conversion element 45G) is formed on the second surface 311b and corresponds to the positions of different light-emitting units LU, respectively, wherein the wavelength conversion elements 45 are separated from each other by a distance. According to the embodiment, the display structure without a crystal growth substrate can avoid cross talk between pixels, and can also reduce the overall thickness of the display and increase flexibility.

Next, as shown in FIG. 3E , a waterproof layer 46 is formed on the second surface 311b of the semiconductor layer and covers the wavelength conversion element 45 (45R/45G). In one example, the wavelength conversion element 45 is, for example, a quantum dot (QD) fluorescent powder material layer, and the waterproof layer 46 is a transparent waterproof film, the material of which is, for example, epoxy or other materials with high light transmittance (for example, the transmittance coefficient of the light emitted by the light-emitting unit is greater than 90%) that can block water vapor, so as to protect the quantum dot fluorescent powder material whose characteristics are easily affected by water vapor.

Furthermore, in the above-mentioned step as shown in FIG. 3D, a wavelength conversion element can be formed by a lithography process. Please refer to FIG. 4A-4C, which illustrates a method for manufacturing a wavelength conversion element in an embodiment of the present invention. As shown in FIG. 4A, a photoresist PR is formed on the semiconductor layer 311; then, a patterned photoresist PR' is formed by exposure and development, as shown in FIG. 4B. Among them, the patterned photoresist PR' includes an opening corresponding to the position of the subsequent formation of the red wavelength conversion element 45R. Then, the red wavelength conversion element 45R is formed and the patterned photoresist PR' is removed, as shown in FIG. 4C. Similarly, the green wavelength conversion element 45G can be formed by the steps of FIG. 4A-4C to complete the manufacture of the wavelength conversion element 45 shown in FIG. 3D.

In addition, although in the above examples, the light-emitting unit LU includes a blue light GaN layer and forms a red wavelength conversion element 45R and a green wavelength conversion element 45G as an example for explanation (such as Figures 2, 3A-3E), the present disclosure is not limited to this state. In actual applications, the wavelength conversion element is appropriately set according to the color of light emitted by the light-emitting unit LU. For example, in an application example, if the light-emitting unit LU includes an ultraviolet (UV) LED, a blue wavelength conversion element is required to convert non-visible UV light into blue light. Figure 5 is a cross-sectional schematic diagram of a display of another embodiment of the present invention. The same components in Figure 5 and Figure 3D are marked with the same numbers for the sake of clarity, and the contents of these components are referred to above and will not be repeated here. As shown in the example of Figure 5, a red wavelength conversion element 45, a green wavelength conversion element 45G, and a blue wavelength conversion element 45B are formed on the semiconductor layer 311, thereby forming RGB pixels to achieve full-color display.

Furthermore, in some embodiments, a low-light-transmittance material or a non-light-transmittance material, such as an opaque material, may be formed on the periphery of the wavelength conversion element. FIG. 6 is a cross-sectional schematic diagram of a display of another embodiment of the present invention. The same components in FIG. 6 and FIG. 3D are labeled with the same reference numerals for the sake of clarity, and the contents of these components are referred to above and are not repeated here. As in the example of FIG. 6, an opaque material OM is formed on the periphery of the wavelength conversion elements on the semiconductor layer 311, such as around the red wavelength conversion element 45R and the green wavelength conversion element 45G, to reduce light cross-talk. Opaque materials are, for example, black, white or other opaque materials, such as black pigment, white pigment, black pigment materials such as carbon black, white pigment materials such as titanium oxide, silicon dioxide, aluminum oxide, magnesium oxide, zinc oxide, zinc sulfide, zirconium oxide.

In addition, FIG. 7 is a cross-sectional schematic diagram of a display according to another embodiment of the present invention. The same or similar components in FIG. 7 and FIG. 2 are labeled with the same or similar reference numerals for the sake of clarity. In this example, the horizontal position of the first electrode 316 (such as the conductive pad 316P) is different from the horizontal position of the second electrode 317 (for example, the horizontal position of the conductive pad 316P is closer to the semiconductor layer 311). In this example, the connection portion 316C is not formed above the first electrode, for example, on the conductive pad 316P, so the second portion 422 of the connection metal 42 shown in FIG. 7 directly connects the conductive pad 316P (i.e., the first electrode) and the second control pad 222 of the substrate 21; in other words, the height d2' of the second portion 422 in FIG. 7 is greater than the height d2 of the second portion 422 in FIG. 2. Of course, the configuration of the first portion 421 and the second portion 422 of the connection metal 42 that can be applied in the embodiment, and the relative horizontal position of the first electrode 316 and the second electrode 317 are not limited to the examples shown in FIGS. 2 and 7. The heights d1 and d2 of the connection metal are different or close, and the horizontal positions of the first electrode 316 and the second electrode 317 are different or close, which are all applicable structural forms of the disclosed embodiment. However, for the structural form in which the horizontal positions of the first electrode 316 and the second electrode 317 have a significant difference (i.e. the heights d1 and d2 of the connection metal are different), the manufacturing method proposed in the embodiment can ensure the electrical conduction between the substrate 21 and the electrodes of the light-emitting diode array. The following is an example of a manufacturing method of one of the bonding layers.

Figures 8A and 8B illustrate a bonding process of an embodiment of the present invention. Figure 8A shows the state before heating in the bonding process, and Figure 8B shows the state after heating in the bonding process. Furthermore, the same components in Figures 8A and 8B and Figures 3A and 3B are labeled with the same reference numerals for the sake of clarity. In this example, a self-assembly conductive paste (SAP) is used in the bonding process.

As mentioned above, a self-assembled conductive gel (SAP) is filled between a substrate 21 (e.g., a CMOS backplane) and a light-emitting component (e.g., an LED wafer, including a crystal growth substrate 310, a light-emitting diode array 31, an insulating layer 315, a first electrode 316, a second electrode 317, etc.). The self-assembled conductive gel (SAP) includes a non-conductive gel 410 and a plurality of conductive particles 420. Before heating, the conductive particles 420 are approximately uniformly dispersed in the non-conductive gel 410, as shown in FIG. 8A; that is, the distribution density of the conductive particles 420 in the non-conductive gel 410 corresponding to the first electrode 316 and the second electrode 317 is similar to the distribution density of the area outside the corresponding electrodes. Next, the assembly is heated during the bonding process, for example, it is rapidly heated (for example, for about 30 seconds to 3 minutes) in a low temperature range (for example, a temperature of about 140°C to 180°C), and the conductive particles 420 are melted and connected to the electrodes. As shown in FIG. 8B , the conductive particles 420 are gathered between the corresponding first electrode 316/second electrode 317 and the control pad 221/222, and form the first part 421 and the second part 422 of the connection metal 42 as described in the above embodiment. The non-conductive colloid 410 and the conductive particles 420 that do not form the connection metal 42 form the bonding material 41 of the bonding layer 40 as described in the above embodiment. The non-conductive colloid 410 after the bonding process is also solidified by heating.

錫球粒徑

50μm)。但該些數值僅 提出做為舉例說明，而非用以限制本揭露之用。 The conductive particles 420 include a metal material having a melting point lower than 300° C. The metal material may be an element, a compound, or an alloy, such as bismuth (Bi), tin (Sn), silver (Ag), indium (In), or an alloy thereof (e.g., tin-bismuth-silver alloy). When the conductive particles 420 are alloys, the melting point of the conductive particles 420 refers to the eutectic point of the alloy. The non-conductive colloid 410 may be a thermosetting polymer, such as epoxy, silicone, polymethyl methacrylate, and episulfide. The non-conductive colloid 410 may be cured at a curing temperature. In an example, the melting point of the conductive particles 420 is, for example, lower than the curing temperature of the non-conductive colloid 410. As shown in FIG. 8A , before the heating step, the particle size of the conductive particle 420 is defined as the diameter of the conductive particle 420, and the shortest distance between two adjacent second electrodes 317 is preferably more than twice the particle size of the conductive particle 420. In one example, the conductive particle 420 is, for example, a solder ball; in one example, the particle size of the solder ball is in the range of 1 μm to 50 μm (1 μm

Tin ball diameter

50 μm). However, these values are only provided as examples and are not intended to limit the present disclosure.

For the structural state in which the horizontal positions of the first electrode 316 and the second electrode 317 are different (the heights d1 and d2 of the connecting metal are different), if anisotropic conductive film (ACF) is used for pressing to respectively join the first electrode 316/the second electrode 317 with the control pads 221/222 on the substrate 21, the first electrode 316 and the second electrode 317 of different heights may be subjected to uneven force during pressing, resulting in poor conduction between the second electrode 317 and the control substrate. Therefore, compared with the traditional method of plating contacts (bumps) on the electrodes or using anisotropic conductive film (ACF) for bonding, the bonding layer manufacturing method proposed in the embodiment, such as using the above-mentioned SAP (the characteristic of self-assembly after heating, without pressure), can ensure the electrical conduction between the substrate 21 and the LED electrode, and avoid the phenomenon of uneven force, especially the structural state where the horizontal positions of the first electrode 316 and the second electrode 317 are different (the heights d1 and d2 of the connecting metal are different). Furthermore, because SAP has the characteristic of self-assembly after heating, there is no problem of difficult alignment of traditional contacts, and the manufacturing is also fast and easy, so it is suitable for mass production.

In addition to the self-organized anisotropic conductive glue as in the above example, other materials and manufacturing methods can also be used to complete the setting of the bonding layer 40 of the embodiment. FIG. 9 is a cross-sectional schematic diagram of a display of another embodiment of the present invention. The same or similar components in FIG. 9 and FIG. 2 use the same or similar labels, and the description of the same components is referred to above, which is not repeated here. As shown in FIG. 9, in this example, the bonding layer 50 may include a bonding material 51 and a plurality of connecting metals 52, and the connecting metal 52 includes a plurality of first parts 521 and a plurality of second parts 522, wherein the first part 521 corresponds to the light-emitting unit LU (the second electrode 317), and the second part 522 corresponds to the conductive pad 316P (the first electrode 316). For details of the connection and setting method, please refer to the first part 421 and the second part 422 shown in Figure 2. In one embodiment shown in Figure 2, the connecting metal 42 is formed by, for example, melting and aggregating the conductive particles 420 in a heating step. In one embodiment shown in Figure 9, the connecting metal 52 is formed by, for example, a metal body or other conductive body by exposure and development. The connecting metal 52 of the applicable bonding layer 50 is, for example, a metal body (metal dots, such as indium (In), tin (Sn)) or other conductive bodies (such as columns, particles, etc., conductive bodies of unlimited shapes), and the bonding material 51 of the bonding layer 50 is, for example, a polymer with high light transmittance, such as benzocyclobutene (BCB)-based polymers or resins. BCB-type polymers are thermosetting polymers with low dielectric properties. They have excellent bonding ability, chemical corrosion resistance, and good bonding strength. Resin materials include thermosetting polymers and flux, and thermosetting polymers are epoxy resins. Other materials with high light transmittance (for example, the transmittance coefficient of the light emitted by the light-emitting unit is greater than 90%) and bonding properties can also be used, not limited to BCB-type polymers or resins.

Regarding the formation of the display shown in Figure 9, two of the manufacturing methods are presented below as examples.

Figures 10A-10F illustrate one method of manufacturing the display shown in Figure 9. The same reference numerals are used for the same components in Figures 10A-10F and Figures 3A-3E, and the contents of the related components can refer to the above-mentioned related paragraphs. As shown in Figure 10A, a substrate 21 (having a control circuit, such as a CMOS backplane) is first provided, on which, for example, a plurality of pads 22 (such as a first control pad 221 and a second control pad 222) are provided. Then, a photoresist PR is formed on the substrate 21, as shown in Figure 10B. The photoresist PR is exposed and developed to form a patterned photoresist PR', and a plurality of openings are formed at locations corresponding to the connection metal 52 to be formed later, as shown in Figure 10C. Afterwards, a metal body (such as indium, tin, copper, gold, aluminum, silver) or other conductive body is formed through the opening, for example, by evaporation, to form the first part 521 and the second part 522 of the connecting metal 52, and the patterned photoresist PR' is removed, as shown in FIG. 10D. Then, the structure in FIG. 10D is connected to the LED array 31, and the bonding material 51 is filled between the substrate 21 and the LED array, as shown in FIG. 10E. Then, a wavelength conversion element 45 (such as 45R/45G or 45R/45G/45B, depending on the light color of the light-emitting unit) is formed, as shown in FIG. 10F.

Figures 11A-11G illustrate another method of manufacturing the display shown in Figure 9. The same components in Figures 11A-11G and Figures 3A-3E use the same labels, and the content of the relevant components can refer to the aforementioned relevant paragraphs. As shown in Figure 11A, first, a substrate 21 (having a control circuit, such as a CMOS backplane) is provided, on which, for example, a plurality of pads 22 (such as a first control pad 221 and a second control pad 222) are provided. Then, a photoresist PR is formed above the substrate 21, as shown in Figure 11B. The photoresist PR is exposed and developed to form a patterned photoresist PR', and a plurality of openings are formed at the first portion 521 and the second portion 522 of the connecting metal 52 to be formed subsequently, as shown in Figure 11C. Afterwards, a metal body (such as indium, tin, copper, gold, aluminum, silver) or other conductive body is formed through the opening, for example, by evaporation, to form the first part 521 and the second part 522, and the patterned photoresist PR' is removed, as shown in FIG. 11D. Next, an uncured bonding material 51 is formed on the substrate 21 and covers the connecting metal 52, as shown in FIG. 11E. The structure in FIG. 11E is then connected to the light-emitting diode array 31, as shown in FIG. 11F; in this step, the first part 521 and the second part 522 are melted, so that the first part 521 and the second part 522 are respectively connected to the second electrode 317 and the connecting part 316C, for example. The bonding material 51 is cured after the first portion 521 and the second portion 522 are bonded to the second electrode 317 and the connecting portion 316C, respectively.

According to the above example, the connection metal 42/52 can be formed first, and then the bonding material 41/51 can be filled, and the bonding material 41/51 can be cured by appropriate processes (such as heating or irradiation) according to the characteristics of the selected bonding material to complete the bonding of the bonding layer 40/50 of the embodiment. The present disclosure does not specifically limit the material and setting method of the bonding layer of the embodiment, such as whether the bonding material 41/51 is set before or after the substrate 21 (with the control circuit) and the light-emitting diode array 31 are connected.

Furthermore, in the above examples, such as Figure 2-9, the side walls of the connecting metal 42/52 are drawn as straight lines for illustration. However, in actual applications, the cross-sectional shape of the connecting metal 42/52 is not limited to the straight side walls as shown in Figure 2-9. The side walls (or the outermost surface) of the connecting metal 42/52 may be curved or other shapes such as irregular shapes, depending on the material selection and/or process steps of the bonding layer. For example, when SAP is used as the bonding layer, the side walls of the connecting metal 42 formed by the conductive particles 420 being heated and melted and gathered at the electrode may be curved, or the cross-sectional shape of the connecting metal 42/52 may change when the bonding material 41/51 is cured. Therefore, the illustrations in the embodiments are for illustrative purposes only and are not intended to limit the present disclosure.

In addition, the above examples, such as Figures 2-9, use the grid-shaped N electrode shown in Figure 1 as an example to illustrate the embodiments, but the present disclosure is not limited to this. Non-grid-shaped N electrodes can also be applied to the embodiments of the present disclosure. The following is a non-grid-shaped N electrode state as another example.

FIG. 12 is a top view of an array of light-emitting diodes and electrodes according to another embodiment of the present invention. FIG. 13 is a cross-sectional view of a display according to an embodiment of the present invention, wherein the array of light-emitting diodes and electrodes are depicted along the section line 13-13 of FIG. 12. Please refer to FIG. 12 and FIG. 13 simultaneously. The same or similar components in FIG. 12 and FIG. 13 and FIG. 1 and FIG. 2 are marked with the same or similar reference numerals, and the description of the same components is referred to above, and will not be repeated here. Different from the grid-shaped first electrode (e.g., N electrode) in FIG. 1, the first electrode shown in FIG. 12 includes a conductive pad 316P (e.g., N pad) located outside the LED array, and does not have an extension portion such as metal traces 3161, 3162 extending along the first direction D1 and the second direction D2 (e.g., X and Y directions) as shown in FIG. 1. Therefore, in the LED array shown in FIG. 13, there is no extension portion between two adjacent light-emitting units LU. Although the non-grid-shaped N electrode shown in FIG. 12 has a greater resistance value than the grid-shaped N electrode in FIG. 1, it is also one of the N electrode forms that can be applied in the present disclosure. The present disclosure does not impose many restrictions on the applicable N electrode forms.

According to the above, the embodiment proposes a display with a light-emitting diode array, including a driving substrate (such as a CMOS substrate), a light-emitting diode array and a bonding layer formed therebetween, wherein the bonding layer includes a connection metal and a bonding material, the connection metal can provide electrical connection between the driving substrate and the light-emitting diode array, and the bonding material is filled in the gap between the driving substrate and the light-emitting diode array to provide support, and can properly block moisture from corroding the electrode and entering the material layer of the light-emitting diode. Accordingly, the crystal growth substrate (such as a sapphire substrate) originally used to form the light-emitting diode array can be removed after the bonding layer is set, so the display of the embodiment does not have a crystal growth substrate. If applied to the manufacture of micro-LED arrays, each micro-LED corresponds to a sub-pixel, then the display structure without a crystal growth substrate as proposed in the embodiment can avoid mutual interference of optical signals between sub-pixels. Moreover, the absence of a crystal growth substrate can also reduce the overall thickness of the display, increase the flexibility of the display, and make the application more extensive. Furthermore, the manufacturing method proposed in the embodiment is particularly suitable for filling and electrical conduction between LEDs with different electrode horizontal positions (/horizontal heights) and driving substrates, and the formation of connecting metals and bonding materials in the bonding layer will not cause damage to the relevant layers and components in the structure, and there is no need to adopt time-consuming and expensive manufacturing procedures. Therefore, the structure and manufacturing method proposed in the embodiment are suitable for mass production.

The structures and steps shown in the above diagrams are used to describe some embodiments or application examples of the present disclosure. The present disclosure is not limited to the scope and application of the above structures and steps. Other embodiments with different structural aspects, such as known components of different internal components, may be applicable, and the exemplified structures and steps may be adjusted according to the actual application conditions or material selection. Therefore, the illustrated structure is only for illustrative purposes, not for limitation. Generally speaking, the knowledgeable person should know that the relevant structures and step processes of the present disclosure, such as the configuration of related components and layers such as light-emitting diode arrays, electrodes, control substrates, or manufacturing steps, may be adjusted and changed accordingly according to the actual application requirements.

In summary, although the present invention has been disclosed as above by the embodiments, it is not intended to limit the present invention. Those with common knowledge in the technical field to which the present invention belongs can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of the patent application attached hereto.

21: Substrate

221: First control pad

31: LED array

311, 313: semiconductor layer

311b: Second surface

312:Active stack

316: First electrode

3162: Routing

317: Second electrode

41: Bonding material

421: Part 1

d1: Height of the first part

45: Wavelength conversion element

45G: Green wavelength conversion element

22: Pad

222: Second control pad

LU: Light emitting unit

311a: first surface

313a: Surface of the second conductive semiconductor layer

315: Insulation layer

316P: Conductive pad

316C:Connection part

40: Adhesive layer

42: Connecting metal

422: Part 2

d2: Height of the second part

45R: Red wavelength conversion element

Claims (9)

A display comprises: A substrate having a plurality of pads; A light-emitting diode array located on the substrate, comprising: A first semiconductor layer, a plurality of active layers formed separately from each other under the first semiconductor layer, and a plurality of second semiconductor layers formed correspondingly under the plurality of active layers; A first electrode formed under the first semiconductor layer and electrically connected to the first semiconductor layer; and A plurality of second electrodes formed correspondingly under the plurality of second semiconductor layers; A bonding layer formed between the substrate and the light-emitting diode array; A plurality of wavelength conversion elements are formed separately from each other on the light-emitting diode array and cover at least part of the plurality of active layers; and an opaque material layer is formed on the light-emitting diode array to separate the plurality of wavelength conversion elements. A display as described in claim 1, wherein there is no crystal growth substrate between the light emitting diode array and the plurality of wavelength conversion elements. A display as described in claim 1, wherein the bonding layer includes a bonding material and a plurality of connection metals, and the plurality of connection metals are surrounded by the bonding material. A display as described in claim 3, wherein the bonding material is filled between the plurality of connection metals, the substrate, and the light-emitting diode array. The display as described in claim 1 further includes a transparent layer located above the plurality of wavelength conversion elements. A display as described in claim 1, wherein the plurality of active layers has an active layer that is not covered by the plurality of wavelength conversion elements. The display as described in claim 1 further includes a metal wiring formed between two adjacent active layers among the plurality of active layers and located under the first semiconductor layer. The display as described in claim 1 further includes a plurality of connection metals, which respectively cover the plurality of pads; wherein at least two of the plurality of connection metals have different heights. A display as described in claim 1, wherein the first electrode and the plurality of second electrodes have different electrical properties, and the first electrode has a greater thickness than the plurality of second electrodes.