Micro-LED packaging structure and manufacturing method thereof

Abstract

The present application relates to the technical field of semiconductor packaging, and particularly relates to a Micro-LED packaging structure and a manufacturing method thereof. The packaging structure comprises, from bottom to top, a substrate, a color filtering layer, a color conversion layer, an inorganic layer, a chip bonding layer, a micro light emitting diode layer, a first filling layer, a reflective layer and a second filling layer. The substrate is ground, thinned, cut and split to form independent discrete devices. By setting the reflective layer covering the packaging structure and the discontinuous chip bonding layer, the light emitted by the quantum dots and the micro light emitting diodes is reflected by the reflective layer, avoiding light crosstalk between the packaging structures. The first filling layer with a slope surface is arranged between the reflective layer and the micro light emitting diodes, so that the side light path avoids the micro light emitting diode body, improving the light efficiency. The micro light emitting diodes are arranged in a bias layout, preventing top damage during transfer packaging. The packaging structure has the advantages of preventing light crosstalk and facilitating laser cutting while improving light efficiency and preventing damage.

Description

Technical Field

[0001] This invention relates to the field of semiconductor packaging technology, and in particular to a Micro-LED packaging structure and its fabrication method. Background Technology

[0002] In traditional technologies, to utilize high-efficiency blue Micro-LEDs (Micro Light Emitting Diode Displays, also known as Micro LEDs or simply "micro-light-emitting diodes"), blue Micro-LEDs are combined with quantum dot color conversion layers to convert some blue light into red and green light. The blue Micro-LEDs and quantum dots are fabricated separately, and an adhesive organic material is used to integrate the LEDs and quantum dots. Alternatively, the quantum dots and Micro-LEDs can be packaged together using bonding of an entire surface of organic material. However, during the fabrication of large-sized wafers, the products are susceptible to warping due to temperature variations. The manufacturing process also presents challenges such as complex cutting processes, high costs, low yield rates, low mass production feasibility, and difficulties in commercialization.

[0003] In the prior art, such as the technical solution disclosed in Chinese Patent No. CN120344065A entitled "Anti-crosstalk Light Emitting Unit and its Manufacturing Method", the problem of light crosstalk between light emitting units is solved, product quality is improved and mass production is enhanced by setting a reflective layer and a discontinuous bonding layer.

[0004] However, problems with this structure in practice include:

[0005] First, the light emitted by Micro-LEDs is partly emitted from the front and partly reflected from the side before being emitted again. Among them, the side light of Micro-LEDs is reflected by the reflective layer, and part of the light passes through the LED body, resulting in light loss, while the other part is truly emitted from the side. The proportion of light emitted from the side after being reflected is greater than that emitted from the front, resulting in low light emission efficiency of Micro-LEDs from the front. After experimental analysis, the front light emission efficiency of independent Micro-LED packaging structures is only 35% of that before the laser lift-off process (only about 35% of the light from Micro-LEDs can pass through when it enters the chip bonding layer), which still needs improvement.

[0006] Secondly, the packaged Micro-LED chip structure is transferred to a carrier substrate using a die bonder. The die bonder uses a pin with a diameter of tens of micrometers to lift the packaged Micro-LED chip structure and then holds the chip in place using a vacuum nozzle. The entire process is completed in a short time, taking no more than 10ms. The packaged Micro-LED chip structure is subjected to very high instantaneous pressure, which can easily damage the fragile GaN epitaxial layer, causing it to become brittle and crack, resulting in the entire chip breaking (i.e., "die bonding damage"), which seriously affects the yield. Existing solutions mostly focus on improving the die bonding process or equipment, such as using blunt-tipped pins, changing the way the chip is attached to the blue film, or flipping the chip. These methods have limited effectiveness and are costly.

[0007] To address the problems in the existing technology, this invention provides a Micro-LED packaging structure and its fabrication method. Summary of the Invention

[0008] The purpose of this invention is to provide a Micro-LED packaging structure and its manufacturing method to solve the technical problems of low light extraction efficiency and low yield of micro-LED packaging structures in the prior art, which result in low product mass production capability.

[0009] The technical solution of the present invention is: a Micro-LED packaging structure, which includes, from bottom to top, a substrate, a color filter layer, a color conversion layer, an inorganic layer, a chip bonding layer, a micro-light-emitting diode layer, and a reflective layer;

[0010] The inorganic layer continuously covers the exposed surface of the substrate, the uncovered surface of the color filter layer, and the surface and sides of the color conversion layer.

[0011] The projected area of ​​the micro-LED layer is no larger than that of the chip bonding layer;

[0012] A trapezoidal first filler layer is provided above the color conversion layer. The first filler layer covers the surface and sides of the chip bonding layer except for the reserved electrode area on the surface of the micro light-emitting diode layer.

[0013] The reflective layer covers the exposed surface of the inorganic layer, the surface and sides of the first leveling layer that are not covered; a second leveling layer is provided on the surface of the reflective layer;

[0014] Electrodes are disposed on the surface of the micro-light-emitting diode layer. The electrodes extend outward through the first filler layer, the reflective layer and the second filler layer in sequence to form an extended electrode. The external extended electrode is disposed on the second filler layer.

[0015] Preferably, the cross-sectional shape of the first filling layer is set as an isosceles trapezoid with a lower base angle of 45°-90°.

[0016] Preferably, the maximum width of the first filler layer is set between the width of the color conversion layer and the width of the chip bonding layer, and the width of the bottom edge of the first filler layer is greater than the width of the micro light-emitting diode, so as to fully cover the exposed surface of the chip bonding layer.

[0017] Preferably, in the entire package of the Micro-LED package structure, the orthographic projection of each micro-LED layer arranged within the same package avoids the area of ​​10% around the geometric center point of the package.

[0018] Preferably, at least one micro-light-emitting diode of a single color is provided in one of the Micro-LED package structures; or, at least two micro-light-emitting diodes of different colors are provided in one of the Micro-LED package structures.

[0019] Preferably, the orthographic projection of the color conversion layer falls within the region where the color filter layer is located; the thickness of the color filter layer is 1-5 μm; and the thickness of the color conversion layer is 3-7 μm.

[0020] The chip bonding layer corresponds to the color conversion layer of each package structure, and the orthographic projection of the chip bonding layer falls within the area where the color conversion layer is located, and the orthographic projection of the micro light-emitting diode layer falls within the area where the chip bonding layer is located; the thickness of the chip bonding layer is no greater than 2μm.

[0021] Preferably, the first leveling layer is an organic material, including colorless polyimide;

[0022] The second leveling layer is made of organic material, including photolithographic polyimide material or acrylic photoresist material;

[0023] The projected area of ​​the second leveling layer is not less than the projected area of ​​the color filter layer.

[0024] A method for fabricating a Micro-LED packaging structure, applicable to the fabrication of the aforementioned Micro-LED packaging structure, includes:

[0025] A color filter layer and a color conversion layer are sequentially fabricated on the substrate from bottom to top;

[0026] A continuous inorganic layer is fabricated on the exposed surface of the substrate, the surface of the color filter layer that is not covered, and the surface and sides of the color conversion layer.

[0027] Fabricating discontinuous chip bonding layers on inorganic layers;

[0028] A blue micro-light-emitting diode layer is transferred and fabricated on the chip bonding layer, and the arrangement of all micro-light-emitting diodes in the entire package avoids the area of ​​10% around the geometric center point of the Micro-LED package structure.

[0029] A trapezoidal first leveling layer is fabricated on the color conversion layer, and the first leveling layer covers the exposed surface and sides of the chip bonding layer and the exposed surface and sides of the micro light-emitting diode.

[0030] A reflective layer is formed on the surface and sides of the inorganic layer that are not covered, and on the surface and sides of the first leveling layer that are not covered; a second leveling layer is formed on the surface of the reflective layer;

[0031] Except for the area used to fabricate electrodes, the exposed surface of the micro-LED layer is covered by the first filler layer. The electrodes on the surface of the micro-LED layer extend longitudinally and are laid on the surface of the second filler layer to form extended electrodes.

[0032] The substrate is subjected to operations including grinding and thinning, laser cutting and splitting to form independent discrete devices.

[0033] Preferably, at least one set of light-emitting units is fabricated simultaneously on a substrate, and one set of light-emitting units includes one or three of the aforementioned encapsulation structures;

[0034] During laser cutting, one or three encapsulation structures are grouped together. The reflective layer, inorganic layer and substrate between adjacent units are cut off, and the light-emitting unit is divided into independent encapsulation structures.

[0035] Preferably, the three encapsulation structures of the color filter layers in each group of light-emitting units correspond one-to-one with the first yellow filter, the second yellow filter, and the blue filter; the three micro light-emitting diodes in each group of light-emitting units are independent and discontinuous with each other;

[0036] A color conversion layer is fabricated on the top surface of the blue filter, the first yellow filter, and the second yellow filter of the color filter layer using photolithography. This layer includes an RQD layer, a GQD layer, and a blank layer.

[0037] Compared with the prior art, the advantages of the present invention are:

[0038] (1) By setting a colorless and transparent first filler layer between the reflective layer and the micro light-emitting diode, the side light emitted by the micro light-emitting diode is reflected by the slope at the junction of the first filler layer and the reflective layer, and the light path of the emitted light avoids the micro light-emitting diode body and is emitted directly from the front. This avoids light loss, improves the front light emission efficiency, and improves the overall light efficiency of the chip, while avoiding light crosstalk between packaging structures.

[0039] (2) After the entire pixel process is completed, when laser cutting and chip splitting are performed, since the chip bonding layer and filler layer are discontinuous and no organic layer is set at the splitting position, the number of laser processes can be reduced, thus improving mass production efficiency. Furthermore, removing the organic layer can greatly avoid the occurrence of chip twinning problems and improve product yield.

[0040] (3) In the packaging structure provided by the present invention, the layout of the micro-LEDs avoids the area of ​​10% around the geometric center of the entire package; when the Micro-LED package structure is transferred by the die bonder, the pin application position of the die bonder is limited to the area of ​​10% around the geometric center of the package, avoiding the risk of chip damage (cracking) and improving the transfer yield. It avoids optical crosstalk, improves luminous efficiency, prevents chip damage, and is suitable for commercial mass production.

[0041] (4) The packaging structure provided by the present invention improves light efficiency and prevents damage while maintaining excellent anti-light crosstalk characteristics and mass production advantages that facilitate laser cutting. Attached Figure Description

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0043] Figure 1 This is a cross-sectional schematic diagram of the optical conversion layer with a continuous inorganic layer as described in this invention;

[0044] Figure 2 This is a schematic cross-sectional view of the micro-light-emitting diode fabricated on the chip bonding layer of the present invention.

[0045] Figure 3 This is a schematic cross-sectional view of the electrode and the first filler layer fabricated on the micro light-emitting diode described in this invention.

[0046] Figure 4 This is a cross-sectional view of the packaging structure described in this invention;

[0047] Figure 5 This is a schematic diagram comparing the side light emission paths of the packaging structure described in this invention with those of existing packaging structures;

[0048] Figure 6 This is a schematic diagram of the force application area of ​​the ejector pin during the transfer of the packaging structure described in this invention;

[0049] Figure 7 This is a schematic diagram of the layout of multiple monochromatic micro-light-emitting diodes according to the present invention;

[0050] Figure 8 This is a schematic diagram showing the layout of the three micro-light-emitting diodes of the three colors described in this invention;

[0051] Figure 9 This is a schematic diagram comparing the layout of the micro-light-emitting diodes and electrodes in the packaging structure described in this invention with that in existing packaging structures;

[0052] Figure 10 This is a schematic diagram of the visible light transmittance curves of different filters described in this invention.

[0053] Wherein: 100, substrate; 200, color filter layer; 300, color conversion layer; 400, inorganic layer; 500, chip bonding layer; 600, micro light-emitting diode layer; 700, reflective layer; 800, second leveling layer; 900, extended electrode; 1000, first leveling layer;

[0054] 201, First yellow filter; 202, Second yellow filter; 203, Blue filter; 301, RQD layer; 302, GQD layer; 303, Blank layer; 601, First blue micro-LED; 602, Second blue micro-LED; 603, Third blue micro-LED. Detailed Implementation

[0055] The present invention will be further described in detail below with reference to specific embodiments:

[0056] In existing technologies, such as the technical solution disclosed in Chinese Patent Publication No. CN120344065A entitled "An Anti-Crosstalk Light Emitting Unit and Its Manufacturing Method," the problem of optical crosstalk between light-emitting units is solved, product quality is improved, and mass production capability is enhanced by setting a reflective layer and a discontinuous bonding layer. However, some light rays from the side of the micro-LED are reflected by the reflective layer and then pass through the micro-LED body, causing light loss and resulting in low overall light extraction efficiency. This invention further improves upon the solution disclosed in this patent, increasing the front-side light extraction efficiency and improving the overall luminous efficacy of the chip.

[0057] This invention provides a method for fabricating a Micro-LED packaging structure, as detailed below:

[0058] Step 1: Fabricate a color filter layer 200 on a sapphire or glass substrate 100.

[0059] Sapphire or glass substrates are typically 4-6 inches in size and 300-1300 μm thick.

[0060] In one or other embodiments, the color filter layer 200 is configured as a combination of a red filter, a green filter, and a blue filter.

[0061] In another embodiment or other implementation, as shown in the appendix Figure 1 As shown, the color filter layer 200 is configured as a combination of a first yellow filter 201, a second yellow filter 202, and a blue filter 203. The thickness of the constructed color filter layer 200 is 1-5 μm.

[0062] See attached document Figure 10The provided schematic diagram of visible light transmittance curves for different filters shows that the red / green / yellow filters have a transmittance of <1% for blue light (445-470nm). The red filter has a transmittance of >80% for red light. The green filter has a transmittance of >80% for green light, and the yellow filter has a transmittance of >80% for both red and green light.

[0063] By replacing the red and green filters with a yellow filter, the transmittance of red or green light can be guaranteed while filtering out blue light that quantum dots cannot convert, thereby improving the color purity of the emitted light.

[0064] Step 2: Create a color conversion layer 300 on the color filter layer 200.

[0065] On the first yellow filter 201, the second yellow filter 202, and the blue filter 203, parallel and independent RQD layers 301 (red quantum dots, abbreviated as "RQD"), GQD layers 302 (green quantum dots, abbreviated as "GQD"), and blank layers 303 (blank without quantum dots, abbreviated as "Blank layer") are fabricated by photolithography. The thickness of the color conversion layer 300 is 3-7 μm.

[0066] The RQD layer 301 and GQD layer 302 contain red and green quantum dot materials for color conversion, while the blank layer 303 (corresponding to the blue filter) does not contain quantum dot materials.

[0067] The downward projected area of ​​the RQD layer 301, GQD layer 302, and blank layer 303 is no greater than the top surface area of ​​the corresponding first yellow filter 201, second yellow filter 202, and blue filter 203 at the bottom.

[0068] Step 3: Fabricate the inorganic layer 400. The width of the color conversion layer 300 is larger than that of the bonding layer, and the width of the color conversion layer 300 ranges from 50-70 μm. Figure 3 In the provided examples, the value is 70 μm.

[0069] The width of the color filter layer 200 is not less than the width of the color conversion layer 300, and the width of the color filter layer 200 ranges from 60-90 μm. Figure 3 In the provided examples, the value is 80 μm.

[0070] An inorganic layer 400 is fabricated on the surface and sides of the color filter layer 200 and the color conversion layer 300, as well as on the exposed surface of the substrate 100, using CVD and ALD equipment. The inorganic layer 400 is made of one or more composite materials selected from SiO2, Al2O3, and TiO2, serving as a barrier against water and oxygen. The inorganic layer 400 is an encapsulation layer with a thickness of 20-2000 nm. The fabrication results are shown in the attached figure. Figure 1 As shown.

[0071] Step 4: Fabricate the chip bonding layer 500.

[0072] A chip bonding layer 500 is fabricated on the inorganic layer 400, within the color filter layer 200 and the color conversion layer 300. The thickness of the chip bonding layer 500 is no greater than 2 μm. The width of the chip bonding layer 500 ranges from 40 to 42 micrometers. (See attached image.) Figure 3 In the provided example, the value is 42μm.

[0073] The chip bonding layer 500 is made of an organic material, such as photoresist, including photolithographic polyimide or acrylic photoresist. A discontinuous bonding layer is formed by exposure and development, covering the inorganic layer 400.

[0074] The projected area of ​​the chip bonding layer 500 is no greater than the top surface area of ​​the bottom color conversion layer 300.

[0075] Step 5: Transfer the fabrication of the micro-light-emitting diode layer 600 onto the chip bonding layer 500.

[0076] The micro-LED layer 600 includes independent first blue micro-LEDs 601, second blue micro-LEDs 602, and third blue micro-LEDs 603, which correspond to the corresponding color filter layer 200 and color conversion layer 300 at the bottom, respectively. (See attached diagram.) Figure 2 As shown, the projected area of ​​each blue micro-LED is no greater than the top surface area of ​​the corresponding chip bonding layer 500 at the bottom.

[0077] like Figure 6 As shown, the two micro-LEDs are offset to both sides to ensure that the bonding force F of the die-bonding pin (not shown in the figure) acts on the area with higher chip structure strength, rather than the fragile center of the GaN epitaxial layer, thereby effectively preventing top damage.

[0078] See attached document Figure 7 As shown, a schematic diagram of the layout of multiple tri-color micro-light-emitting diodes in the package structure is provided; (Attached) Figure 8 A schematic diagram of the layout of three micro-light-emitting diodes of three colors in the package structure is provided.

[0079] Therefore, when transferring the micro-LEDs to the chip bonding layer 500, the placement of all micro-LEDs avoids the area within 10% of the geometric center of the package. This facilitates the subsequent transfer of the packaged chip structure and prevents the chip from being damaged or broken. The shape of this "forbidden zone" is not particularly restricted; typically, the tip of the ejector pin is nearly circular, so this area is correspondingly set as a circular region.

[0080] Step 6: Create the first leveling layer of 1000mm.

[0081] Above the color conversion layer 300, a first leveling layer 1000 is fabricated using photolithography. The overall cross-sectional shape of the first leveling layer 1000 is trapezoidal. The material of the first leveling layer 1000 is a transparent organic material, such as colorless polyimide (CPI adhesive). The fabrication result is shown in the attached figure. Figure 3 As shown. Preferably, the cross-sectional shape of the first filling layer 1000 is an isosceles trapezoid, with the lower base angle ranging from 45° to 90°.

[0082] The first leveling layer 1000 covers all surface areas except for the exposed surface and sides of the chip bonding layer 500 and the reserved electrode area on the surface of the micro-LED layer 600.

[0083] The maximum width of the first filling layer is 1000 (see attached) Figure 3 In the corresponding embodiment, the width of the bottom edge is set between the width of the color conversion layer 300 and the width of the chip bonding layer 500, which can fully cover the exposed surface of the chip bonding layer 500. For example, the width of the first leveling layer 1000 is set to 65 μm.

[0084] The width of the bottom edge of the first filler layer 1000 is greater than the width of the micro-LED layer 600.

[0085] See attached document Figure 5 As shown, attached Figure 5 Figure (a) shows a schematic diagram of the packaging structure and a schematic diagram of the light path emanating from the side of a Chinese patent with publication number CN120344065A and patent title "An Anti-Crosstalk Light Emitting Unit and Its Manufacturing Method"; Appendix Figure 5 Figure (b) is a schematic diagram of the packaging structure provided by the present invention and a schematic diagram of the light path of the side light emission. As can be seen from the comparative example figure, due to the setting of the first leveling layer 1000, the light path of the side light emission is changed, so that the light emission path of the side light of the micro light-emitting diode avoids the body of the micro light-emitting diode, thereby improving the front light emission efficiency.

[0086] Step 7: Create the reflective layer 700.

[0087] A reflective layer 700 is fabricated on the uncovered surface and sides of the inorganic layer 400, and on the exposed surface and sides of the first leveling layer 1000. (See attached diagram.) Figure 3As shown, the reflective layer 700 is configured to continuously cover the surface of the target structure; or the reflective layer 700 is configured discontinuously, with breaks between adjacent package structures (to facilitate cutting and separating into independent devices).

[0088] The reflective layer 700 adopts a DBR (Distributed Bragg Reflector) structure, which can be directly fabricated using commercial DBR coating machines, with a thickness of 1-3μm.

[0089] Using TiO2 / SiO2 as the repeating unit structure, with a TiO2 unit thickness of 50-110 nm and a SiO2 unit thickness of 70-140 nm, repeating 5 to 20 pairs, more than 99% of light reflection can be achieved.

[0090] The reflective layer 700 is designed as a metal reflector, and its fabrication method is as follows:

[0091] First, a SiO2 layer is fabricated as an insulator; second, a Ti-Al metal layer is fabricated on the SiO2 layer.

[0092] Ti, with a thickness of 1-5 nm, is used to improve the adhesion of the SiO2 film surface; Al metal, with a thickness of 50-200 nm, is used to reflect light. The SiO2 structure can be fabricated using CVD, while the metal can be fabricated using electron beam evaporation equipment.

[0093] Step 8: Create a second leveling layer 800 on the surface of the reflective layer 700.

[0094] The second leveling layer 800 uses an organic material; generally, photolithographic polyimide is used, or acrylic photoresist is employed. (See attached document.) Figure 3 As shown, the second filler layer 800 is a discontinuous coverage filling form, which fills and covers the surface of the reflective layer 700, exposing the electrode area of ​​each micro-light-emitting diode surface of the micro-light-emitting diode layer 600, which facilitates the subsequent fabrication of extended electrodes.

[0095] The second filler layer 800 mainly fills the gaps between adjacent package structures. In addition to filling the gaps between adjacent package structures, the second filler layer 800 also provides support for the extension electrode 900. Typically, the area of ​​the extension electrode 900 is as large as possible to increase the area between the chip and the external PCB board, making the connection more stable. Therefore, the surface area of ​​the second filler layer 800 is as large as possible. In the specific implementation of this embodiment, the maximum width of the cross-section of the second filler layer 800 is constrained to be no less than the width of the color filter layer 200. For example, the width of the second filler layer is 82μm.

[0096] Step 9: Fabricate extended electrodes 900 on the surface of the second filling layer 800.

[0097] Each micro-light-emitting diode (LED) in the micro-LED layer 600 has a base electrode fabricated on its surface. These electrodes are electrically connected to the micro-LED layer 600. An extension electrode 900 is fabricated based on the base electrode. (See attached diagram.) Figure 3 As shown, the base electrode extends outward through the first filler layer 1000, the reflective layer 700 and the second filler layer 800 to form an extended electrode 900. The external extended electrode 900 is disposed on the second filler layer 800 to expand the electrode and facilitate the bonding of the chip to the PCB substrate.

[0098] The first leveling layer 1000 and the second leveling layer 800 together form a planarization layer, providing planar support for the flat fabrication of the extended electrode 900 on the chip surface.

[0099] See attached document Figure 9 As shown, attached Figure 9 Figure (c) shows a schematic diagram of the distribution of micro-light-emitting diodes and electrodes on the surface of the package structure disclosed in Chinese Patent No. CN120344065A, entitled "Anti-crosstalk Light-Emitting Unit and its Manufacturing Method"; Appendix Figure 9 Figure (d) is a schematic diagram of the micro-light-emitting diodes and electrodes on the surface of the packaging structure provided by the present invention; as can be seen from the comparative example figure, the chip damage caused by the die-bonding pins is prevented by arranging the micro-light-emitting diode chips in a non-central manner.

[0100] Step 10: Grind and thin the substrate.

[0101] The initial length of the substrate 100 is typically 4-6 inches, and the thickness is 300-1300μm.

[0102] For example, all fabrication processes are performed on a 4-inch sapphire substrate. The original thickness of the sapphire is 600-700 μm, and the final size of a single package structure is 80-400 μm. Therefore, after the layer structure is fabricated, the sapphire substrate is thinned, but the thinning thickness should not exceed the package structure size. Thinning is performed using a grinding process, grinding and thinning the sapphire substrate to below 120 μm.

[0103] Step 11: Laser cutting to form an independent packaging structure.

[0104] The thinned substrate 100 is bonded to a blue film. In one embodiment, the three packaging structures are treated as a whole and laser-cut, cutting the inorganic layer 400 and the substrate (including the reflective layer 700 if it is continuously arranged). In another embodiment, each packaging structure is cut as an independent device, the second leveling layer 800 between adjacent packaging structures is discontinuous, and the reflective layer 700 may be continuous or discontinuous, as shown in the attached figure. Figure 3In the middle, the reflective layer 700 between adjacent encapsulation structures is continuous, while the second leveling layer 800 is discontinuous.

[0105] After laser cutting, the material is further split using a conventional cleaver, ultimately forming individual discrete components. See the attached image for the result of fabricating an individual light-emitting device. Figure 4 As shown.

[0106] Cutting operations are typically performed using lasers. If the laser cutting point only contains an inorganic film layer, the same laser parameters can be used for cutting. For example, a picosecond laser with a wavelength of 1064nm and an energy power of 0.1–1W.

[0107] If the cutting area consists of a composite of organic and inorganic layers, multiple laser cutting methods are required. For example, 355nm and 532nm wavelengths with energies of 0.03 and 0.05W are used to cut organic adhesives. Therefore, the substrate needs to be switched between different laser devices, and laser alignment is crucial, making the actual operation very complex. Furthermore, if the cutting area includes an organic layer, the organic layer may not be completely cut through by the laser, leading to chip adhesion during the splitting process and reduced yield.

[0108] In this embodiment, except for the inorganic layer 400 which is continuous, the rest can be discontinuous and set independently according to each packaging structure. In particular, setting the chip bonding layer 500 and the second leveling layer 800 to be discontinuous can reduce the substrate warping problem caused by temperature rise and fall during large-size manufacturing. When cutting, a single laser parameter is used for cutting, which is simple and efficient.

[0109] After completing the entire pixel process, during laser cutting and chip splitting, the absence of an organic layer and the discontinuous arrangement of most structural layers reduce the number of laser cutting operations, improving efficiency. Furthermore, removing the organic layer significantly reduces the occurrence of twin cells.

[0110] The structure of a single package is shown in the attached diagram. Figure 4 As shown, the cross-sectional width is as follows: from top to bottom, the width of each micro-LED in the micro-LED layer 600 is the smallest, for example, 40μm, and the width of the chip bonding layer 500 is not less than the width of the micro-LED, for example, 40-42μm.

[0111] The inorganic layer 400 (encapsulation layer) continuously covers the surface of the substrate 100. The width of the color conversion layer 300 is not less than that of the chip bonding layer 500, for example, the thickness is 50-70μm, and the width of the color filter layer 200 is not less than that of the color conversion layer, set to 60-90μm.

[0112] A trapezoidal first leveling layer 1000 is formed by covering a portion of the surfaces of the micro-LED layer 600, the chip bonding layer 500, and the inorganic layer 400. A reflective layer 700 is then covered on the surfaces of the inorganic layer 400 and the first leveling layer 1000. This ensures that only a portion of the P and N electrodes on the surface of the micro-LED layer 600 are exposed in the entire micro-LED package structure, guaranteeing electrode expansion in subsequent processes. See Appendix. Figure 3 As shown, except for some electrode areas, the entire area is covered by a reflective layer to avoid optical crosstalk between adjacent packaging structures.

[0113] Based on the above manufacturing method, the present invention also discloses a Micro-LED packaging structure, such as... Figure 3 As shown, a set of light-emitting units includes three encapsulation structures; each encapsulation structure includes, from bottom to top, a color filter layer 200, a color conversion layer 300, an inorganic layer 400, a chip bonding layer 500, a micro light-emitting diode layer 600, and a reflective layer 700 fabricated on a substrate 100.

[0114] The projected area of ​​the color conversion layer 300 falls within the area of ​​the color filter layer 200; the inorganic layer 400 continuously covers the exposed surface of the substrate 100, the exposed side of the color filter layer 200, and the exposed side and surface of the color conversion layer 300.

[0115] The chip bonding layer 500 is discontinuous and corresponds to the color conversion layer 300 of each package structure. The orthographic projection area of ​​the chip bonding layer 500 falls within the area where the color conversion layer 300 is located. The orthographic projection of each micro-light-emitting diode of the micro-light-emitting diode layer 600 falls within the area where the chip bonding layer 500 is located.

[0116] A trapezoidal first filling layer 1000 is provided above the color conversion layer. The first filling layer 1000 covers the exposed surface and side surface of the chip bonding layer 500 and the surface and side surface of the micro light-emitting diode layer 600, excluding the reserved electrode area.

[0117] A second leveling layer 800 is disposed on the surface of the reflective layer 700. The second leveling layer 800 covers the surface of the reflective layer 700 and includes filling the gaps between adjacent encapsulation structures. It is not disposed continuously and is interrupted at least at the laser-cut location. The maximum width of the cross-section of the second leveling layer 800 is not less than the width of the color filter layer 200.

[0118] Electrodes are disposed on the surface of the micro-LED layer 600 and a reserved area is reserved for the placement of the extension electrode 900; the extension electrode 900 extends outward and is disposed on the surface of the second filler layer 800 to connect the chip and the external PCB board.

[0119] The reflective layer 700 covers the exposed surface of the inorganic layer 400, the uncovered surface of the first filling layer 1000, and its sides; see attached figure. Figure 3 As shown, except for the area on the surface of the micro-LED layer 600 used to fabricate the extended electrode, the entire surface is covered by the first leveling layer 1000.

[0120] In the packaging structure of the light-emitting packaging structure provided by the present invention, since the reflective layer 700 extends beyond the chip bonding layer 500 and the inorganic layer 400 (without an organic layer), it can cover and block the exposed surfaces of the color conversion layer 300 and the color filter layer 200. After packaging, the chip structure has no light crosstalk problem, and the light reflected back by the reflective layer 700 can only pass through the color conversion layer 300 and the color filter layer 200 before being emitted, which is equivalent to strengthening the emitted light and improving the light efficiency.

[0121] The discontinuous reflective layer 700, the second leveling layer 800, and the chip bonding layer 500 facilitate chip dicing and can avoid warping problems caused by temperature during chip fabrication.

[0122] Furthermore, since a trapezoidal, colorless, and transparent first leveling layer 1000 is provided between the reflective layer 700 and the micro-light-emitting diode layer 600 above the color conversion layer 300, it is equivalent to extending the inner wall of the reflective layer 700 outward. This changes the path of the light emitted from the side to the reflective layer 700, allowing the light emitted from the side of the micro-light-emitting diode to directly illuminate the sloping surface at the junction of the first leveling layer 1000 and the reflective layer 700. After reflection, the light avoids the micro-light-emitting diode body and is emitted from the front, directly illuminating the color conversion layer 300, thus avoiding light loss and improving the front light emission efficiency.

[0123] Furthermore, in this packaging structure, the layout of the micro-LEDs avoids the 10% area around the geometric center of the entire package; when the Micro-LED package structure is transferred by the die bonder, the pin position of the die bonder is limited to the 10% area around the geometric center of the package, avoiding the risk of chip damage (cracking) and improving the transfer yield.

[0124] Furthermore, the first filling layer 1000 is an organic layer, the reflective layer 700 is an inorganic layer, and the second filling layer 800 is an organic layer. Therefore, through the organic-inorganic composite film structure, it is possible to offset part of the impact force brought by the die bonding pin during die bonding and avoid damage to the micro light-emitting diode layer 600.

[0125] The above embodiments are merely illustrative of the technical concept and features of the present invention, intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be construed as limiting the scope of protection of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and thus all changes falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention.

Claims

1. A Micro-LED packaging structure, comprising, from bottom to top, a substrate, a color filter layer, a color conversion layer, an inorganic layer, a chip bonding layer, a micro-light-emitting diode layer, and a reflective layer; characterized in that, The inorganic layer continuously covers the exposed surface of the substrate, the uncovered surface of the color filter layer, and the surface and sides of the color conversion layer. The projected area of ​​the micro-LED layer is no larger than that of the chip bonding layer; A trapezoidal first filler layer is provided above the color conversion layer. The first filler layer covers the surface and sides of the chip bonding layer except for the reserved electrode area on the surface of the micro light-emitting diode layer. The reflective layer covers the exposed surface of the inorganic layer, the surface and sides of the first leveling layer that are not covered; a second leveling layer is provided on the surface of the reflective layer; Electrodes are disposed on the surface of the micro-light-emitting diode layer. The electrodes extend outward through the first filler layer, the reflective layer and the second filler layer in sequence to form an extended electrode. The external extended electrode is disposed on the second filler layer.

2. The Micro-LED packaging structure according to claim 1, characterized in that, The cross-sectional shape of the first filling layer is set as an isosceles trapezoid with a lower base angle of 45°-90°.

3. The Micro-LED packaging structure according to claim 2, characterized in that, The maximum width of the first filler layer is set between the width of the color conversion layer and the width of the chip bonding layer. The width of the bottom edge of the first filler layer is greater than the width of the micro light-emitting diode, which can fully cover the exposed surface of the chip bonding layer.

4. The Micro-LED packaging structure according to claim 1, characterized in that, In the entire package of the Micro-LED package structure, the orthographic projection of each micro-LED layer arranged within the same package avoids the area of ​​10% around the geometric center of the package.

5. A Micro-LED packaging structure according to claim 4, characterized in that, A single-color micro-light-emitting diode is provided in one of the Micro-LED package structures; or, a two-color micro-light-emitting diode is provided in one of the Micro-LED package structures.

6. The Micro-LED packaging structure according to claim 1, characterized in that, The orthographic projection of the color conversion layer falls within the area where the color filter layer is located; the thickness of the color filter layer is 1-5 μm; the thickness of the color conversion layer is 3-7 μm; The chip bonding layer corresponds to the color conversion layer of each package structure, and the orthographic projection of the chip bonding layer falls within the area where the color conversion layer is located, and the orthographic projection of the micro light-emitting diode layer falls within the area where the chip bonding layer is located; the thickness of the chip bonding layer is no greater than 2μm.

7. A Micro-LED packaging structure according to claim 1, characterized in that, The first leveling layer is made of an organic material, including colorless polyimide; The second leveling layer is made of organic material, including photolithographic polyimide material or acrylic photoresist material; The projected area of ​​the second leveling layer is not less than the projected area of ​​the color filter layer.

8. A method for fabricating a Micro-LED packaging structure, applied to fabricating a Micro-LED packaging structure as described in any one of claims 1-7, characterized in that, include: A color filter layer and a color conversion layer are sequentially fabricated on the substrate from bottom to top; A continuous inorganic layer is fabricated on the exposed surface of the substrate, the surface of the color filter layer that is not covered, and the surface and sides of the color conversion layer. Fabricating discontinuous chip bonding layers on inorganic layers; A blue micro-light-emitting diode layer is transferred and fabricated on the chip bonding layer, and the arrangement of all micro-light-emitting diodes in the entire package avoids the area of ​​10% around the geometric center of the Micro-LED package structure. A trapezoidal first leveling layer is fabricated on the color conversion layer, and the first leveling layer covers the exposed surface and sides of the chip bonding layer and the exposed surface and sides of the micro light-emitting diode. A reflective layer is formed on the surface and sides of the inorganic layer that are not covered, and on the surface and sides of the first leveling layer that are not covered; a second leveling layer is formed on the surface of the reflective layer; Except for the area used to fabricate electrodes, the exposed surface of the micro-LED layer is covered by the first filler layer. The electrodes on the surface of the micro-LED layer extend longitudinally and are laid on the surface of the second filler layer to form extended electrodes. The substrate is subjected to operations including grinding and thinning, laser cutting and splitting to form independent discrete devices.

9. A method for fabricating a Micro-LED packaging structure according to claim 8, characterized in that, At least one set of light-emitting units are simultaneously fabricated on a substrate, and one set of light-emitting units includes one or three of the aforementioned packaging structures. During laser cutting, one or three encapsulation structures are grouped together. The reflective layer, inorganic layer and substrate between adjacent units are cut off, and the light-emitting unit is divided into independent encapsulation structures.

10. A method for fabricating a Micro-LED packaging structure according to claim 9, characterized in that, The three encapsulated color filter layers in each group of light-emitting units correspond one-to-one with the first yellow filter, the second yellow filter, and the blue filter; the three micro light-emitting diodes in each group of light-emitting units are independent and discontinuous with each other; A color conversion layer is fabricated on the top surface of the blue filter, the first yellow filter, and the second yellow filter of the color filter layer using photolithography. This layer includes an RQD layer, a GQD layer, and a blank layer.

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