Light-emitting element with cantilever electrode, display panel and display device having the same

Abstract

The present invention relates to a light-emitting element having a cantilever electrode, a display panel having the same, and a display device. According to one embodiment, the light-emitting element comprises: at least one LED stack; an electrode pad arranged on the LED stack; and cantilever electrodes arranged on the electrode pads, respectively, wherein each cantilever electrode has a fixed end fixed to the electrode pad and a free end separated from the electrode pad.

Description

Technical Field

[0001] The invention relates to a light emitting diode display panel, a display device having the light emitting diode display panel and a manufacturing method thereof. Background Art

[0002] Light-emitting diodes (LEDs) are inorganic light sources that are used in a variety of fields, including display devices, vehicle lamps, and general lighting. LEDs have the advantages of long life, low power consumption, and fast response speed, and are therefore rapidly replacing existing light sources.

[0003] In addition, conventional light emitting diodes are mainly used as backlight sources in display devices. However, recently, LED displays that directly realize images using light emitting diodes are being developed.

[0004] Display devices generally use a mixture of blue, green and red to achieve a variety of colors. In order to achieve a variety of images, display devices include a plurality of pixels, each pixel is equipped with blue, green and red sub-pixels, and the color of a specific pixel is determined by the colors of these sub-pixels, and an image is achieved by combining these pixels.

[0005] LEDs can emit light of various colors depending on their materials, so that a display device can be provided by arranging individual LED chips emitting blue, green, and red colors on a two-dimensional plane.

[0006] LEDs used in existing large electronic screens are packaged and arranged in pixel units, so individual packages are mounted on a circuit board. However, in order to achieve clear image quality, displays of small electronic products such as smart watches or mobile phones or VR helmets or AR glasses, or displays of TVs, etc., require micro LEDs that are smaller than existing LED packages.

[0007] Since small-sized LEDs are difficult to handle, they are difficult to mount individually on a circuit substrate. Therefore, a method is being studied of forming a plurality of LEDs using a semiconductor layer grown on a substrate and collectively transferring these to a display circuit substrate corresponding to the pixel spacing. However, during the collective transfer of the plurality of LEDs, defects may occur in some of the LEDs. In particular, due to the difference in thermal expansion coefficients between the display circuit substrate and the supporting substrate that supports the LEDs, the transferred LEDs may not all be electrically connected to the pads on the display circuit substrate. In this case, the defective LEDs need to be replaced individually with good LEDs, but the small size of the LEDs makes it extremely difficult to replace the defective LEDs. Therefore, there is a need for a display device that can safely transfer collectively transferred LEDs to a circuit substrate without defects.

[0008] In addition, since the sub-pixels are arranged on a two-dimensional plane, the area occupied by a pixel including blue, green and red sub-pixels becomes relatively large. Therefore, in order to arrange the sub-pixels within a limited area, the area of ​​each LED chip must be reduced. However, reducing the size of the LED chip may make it difficult to mount the LED chip, thereby reducing the light-emitting area. Summary of the invention

[0009] Technical issues

[0010] An object of the present invention is to provide a light emitting element suitable for collective transfer onto a circuit board.

[0011] Another problem to be solved by the present invention is to provide an LED display panel capable of safely transferring a plurality of light-emitting elements to a circuit substrate, and a display device having the LED display panel.

[0012] Another problem to be solved by the present invention is to provide an LED display panel capable of reinforcing the electrical connection between the light emitting element and the pad of the circuit substrate, and a display device having the LED display panel.

[0013] Another problem to be solved by the present invention is to provide a method of safely transferring a light-emitting element for display, which can increase the area of ​​each sub-pixel within a limited pixel area, and a display device.

[0014] Technical Solution

[0015] According to one embodiment of the present invention, a light-emitting element includes: at least one LED stack; an electrode pad arranged on the LED stack; and cantilever electrodes arranged on the electrode pads, respectively, wherein each cantilever electrode has a fixed end fixed to the electrode pad and a free end separated from the electrode pad.

[0016] A display panel according to an embodiment of the present invention includes: a circuit substrate having a pad; a light-emitting element electrically connected to the pad and arranged on the circuit substrate; and an adhesive layer arranged between the circuit substrate and the light-emitting element to bond the circuit substrate and the light-emitting element, wherein the light-emitting element respectively includes: at least one LED stack; an electrode pad arranged on the LED stack; and cantilever electrodes arranged on the electrode pads, wherein each cantilever electrode has a fixed end fixed to the electrode pad and a free end separated from the electrode pad, and the free end is electrically connected to the pad of the circuit substrate.

[0017] A display device according to an embodiment of the present invention includes a display panel, wherein the display panel includes: a circuit substrate having a pad; a light-emitting element electrically connected to the pad and arranged on the circuit substrate; and an adhesive layer arranged between the circuit substrate and the light-emitting element to bond the circuit substrate and the light-emitting element, wherein the light-emitting element respectively includes: at least one LED stack; an electrode pad arranged on the LED stack; and cantilever electrodes arranged on the electrode pads, wherein each cantilever electrode has a fixed end fixed to the electrode pad and a free end separated from the electrode pad, and the free end is electrically connected to the pad of the circuit substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 FIG. 1 is a schematic perspective view for explaining a display device according to an embodiment of the present invention.

[0019] Figure 2 FIG. 1 is a schematic plan view for explaining a display panel according to an embodiment of the present invention.

[0020] Figure 3 is along Figure 2 A schematic enlarged cross-sectional view taken along the cutting line AA.

[0021] Figure 4a is a schematic plan view for explaining a light emitting element according to an embodiment of the present invention, Figure 4b In order to explain the light emitting element according to one embodiment of the present invention, Figure 4a A schematic cross-sectional view taken along the cutting line BB.

[0022] Figure 5 FIG. 1 is a schematic cross-sectional view for explaining a cantilever electrode of a light emitting element according to an embodiment of the present invention.

[0023] Figure 6 is a schematic circuit diagram for explaining a light emitting element according to an embodiment of the present invention.

[0024] Figure 7 is a schematic circuit diagram for explaining a light emitting element according to still another embodiment of the present invention.

[0025] Figure 8a and Figure 8b It is a schematic cross-sectional view for explaining a method for manufacturing a light emitting element according to an embodiment of the present invention.

[0026] Figure 9a , Figure 9b and Fig.9c is a schematic cross-sectional view for explaining a method of manufacturing a display panel according to an embodiment of the present invention.

[0027] Best Mode for Carrying Out the Invention

[0028] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to fully convey the idea of ​​the present invention to those skilled in the art to which the present invention belongs, the embodiments described below are provided as examples. Therefore, the present invention is not limited to the embodiments described below, and it can be embodied in other forms. In addition, in the accompanying drawings, the width, length, thickness, etc. of the constituent elements may also be exaggerated for convenience. Moreover, when it is recorded that a constituent element is located "on" or "on" another constituent element, it includes not only the situation that each part is "directly" located "on" or "on" the other parts, but also the situation that another constituent element is sandwiched between each constituent element and another constituent element. Throughout the specification, the same figure numerals represent the same constituent elements.

[0029] According to one embodiment of the present invention, a light-emitting element includes: at least one LED stack; an electrode pad arranged on the LED stack; and cantilever electrodes arranged on the electrode pads, respectively, wherein each cantilever electrode has a fixed end fixed to the electrode pad and a free end separated from the electrode pad.

[0030] By adopting the cantilever electrode, a plurality of light emitting elements can be transferred to a circuit board more safely than the conventional transfer of light emitting elements using solder or bump pads.

[0031] The free end of the cantilever electrode may be bent in a direction away from the at least one LED stack, thereby providing a sharp point, through which a stable electrical connection can be achieved.

[0032] Furthermore, the cantilever electrode may include at least two metal layers having different thermal expansion coefficients, and the difference in thermal expansion coefficients can be used to induce bending of the cantilever electrode.

[0033] In addition, the at least one LED stack may include: a first LED stack; a second LED stack and a third LED stack, and the light-emitting element may include: a first bonding layer, sandwiched between the first LED stack and the second LED stack; and a second bonding layer, sandwiched between the second LED stack and the third LED stack, wherein the first LED stack to the third LED stack can emit light of different wavelengths, and the electrode pad can be electrically connected to the first LED stack to the third LED stack to independently drive the first LED stack to the third LED stack.

[0034] The maximum width of the light-emitting element may be less than 100 μm, further less than 50 μm, and particularly less than 10 μm. Light-emitting elements with a width of less than 10 μm and small size are difficult to transfer to a circuit substrate using solder or a bump pad. The cantilever electrode of the present invention is particularly helpful for collectively transferring small light-emitting elements.

[0035] A display panel according to an embodiment of the present invention includes: a circuit substrate having a pad; a light-emitting element electrically connected to the pad and arranged on the circuit substrate; and an adhesive layer arranged between the circuit substrate and the light-emitting element to bond the circuit substrate and the light-emitting element, wherein the light-emitting element respectively includes: at least one LED stack; an electrode pad arranged on the LED stack; and cantilever electrodes arranged on the electrode pads, wherein each cantilever electrode has a fixed end fixed to the electrode pad and a free end separated from the electrode pad, and the free end is electrically connected to the pad of the circuit substrate.

[0036] The light emitting elements may be arranged at a pitch of 100 μm or less, further may be arranged at a pitch of 50 μm or less, and particularly may be arranged at a pitch of 10 μm or less.

[0037] In some embodiments, a free end of at least one of the cantilever electrodes may extend outward from the at least one LED stacking region. In another embodiment, the cantilever electrode may be located within the at least one LED stacking region.

[0038] In one embodiment, the cantilever electrode may include at least two metal layers with different thermal expansion coefficients, and the difference in thermal expansion coefficients of the metal layers may be used to induce bending of the cantilever electrode.

[0039] The metal layer may be selected from Ni, Co, Cu, Ti, Al or Pt, for example; however, the metal layer of the present invention is not limited thereto.

[0040] The at least one LED stack may include: a first LED stack; a second LED stack and a third LED stack, and the light-emitting element may include: a first bonding layer, sandwiched between the first LED stack and the second LED stack; and a second bonding layer, sandwiched between the second LED stack and the third LED stack, wherein the first LED stack to the third LED stack can emit light of different wavelengths, and the electrode pad can be electrically connected to the first LED stack to the third LED stack to independently drive the first LED stack to the third LED stack.

[0041] Furthermore, the light emitting element may emit light generated in the first to third LED stacks through the third LED stack.

[0042] In addition, the third LED stack may be separated from the growth substrate. That is, the light emitting element may not include the growth substrate used to grow the third LED stack.

[0043] The bonding layer may partially cover the side surface of the light emitting element and may be formed by using a curable resin.

[0044] A display device according to an embodiment of the present invention includes a display panel, wherein the display panel includes: a circuit substrate having a pad; a light-emitting element electrically connected to the pad and arranged on the circuit substrate; and an adhesive layer arranged between the circuit substrate and the light-emitting element to bond the circuit substrate and the light-emitting element, wherein the light-emitting element respectively includes: at least one LED stack; an electrode pad arranged on the LED stack; and cantilever electrodes arranged on the electrode pads, wherein each cantilever electrode has a fixed end fixed to the electrode pad and a free end separated from the fixed end, and the free end is electrically connected to the pad of the circuit substrate.

[0045] The light emitting elements may be arranged at a pitch of 100 μm or less, further may be arranged at a pitch of 50 μm or less, and particularly may be arranged at a pitch of 10 μm or less.

[0046] The cantilever electrodes may respectively include at least two metal layers having thermal expansion coefficients different from each other.

[0047] The at least one LED stack may include a first LED stack, a second LED stack and a third LED stack respectively, the first LED stack to the third LED stack emit light of different wavelengths, and the light-emitting element emits the light generated in the first LED stack to the third LED stack through the third LED stack.

[0048] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0049] Figure 1 FIG. 1 is a schematic perspective view for explaining a display device according to an embodiment of the present invention.

[0050] The light-emitting element of the present invention is not particularly limited, but in particular, it can be used in a smart watch 1000a, a VR display device such as a virtual reality helmet (VR headset) 1000b, or an AR display device such as an augmented reality glasses 1000c. In particular, for AR display devices, the pixel spacing is very small, about 10μm, and the light-emitting element of the present invention is suitable for solving the problems that occur in such display devices with narrow-pitch pixels. However, the light-emitting element of the present invention is not limited to display devices with narrow-pitch pixels, and can be applied to display devices with relatively wider-pitch pixels.

[0051] In addition, a display panel for displaying images is mounted inside the display device. Figure 2 is a schematic plan view for illustrating a display panel 1000 according to an embodiment of the present invention, Figure 3 is along Figure 2 A cross-sectional view taken along the cutting line AA.

[0052] Reference Figure 2 and Figure 3 The display panel includes a circuit substrate 1001 , a light emitting element 100 and a bonding layer 1005 .

[0053] The circuit substrate 1001 or panel substrate may include a circuit for passive matrix driving or active matrix driving. In one embodiment, the circuit substrate 1001 may include wiring and resistors inside. In another embodiment, the circuit substrate 1001 may include wiring, transistors and capacitors. The circuit substrate 1001 may also have a pad 1003 on the upper surface for allowing electrical connection to the circuit arranged inside.

[0054] A plurality of light emitting elements 100 are arranged on a circuit substrate 1001. The light emitting element 100 may be a small light emitting element having a micro unit size, and the width W1 may be about 100 μm or less, and further may be about 50 μm or less, and in particular may be about 10 μm or less. The light emitting element 100 may, for example, have a size of 100 μm×100 μm or less, and further may have a size of 10 μm×10 μm or less. In one embodiment, in the direction in which the light emitting elements 100 are arranged, the interval L1 between the light emitting elements 100 may be greater than the width W1 of the light emitting element 100 in the direction. However, the present invention is not limited thereto, and the interval L1 may also be smaller than the width W1 of the light emitting element 100. The spacing may be expressed as the sum of the width W1 and the spacing L1. The spacing of the light emitting elements 100 may be about 100 μm or less, and further may be about 50 μm or less, and in particular may be about 10 μm or less.

[0055] The light emitting element 100 may include an electrode pad 101 and a cantilever electrode 103. The cantilever electrode 103 may be electrically connected to the pad 1003 on the circuit substrate 1001. For example, the cantilever electrode 103 may have a free standing edge, and the free standing edge is electrically connected to the pad 1003 exposed on the circuit substrate 1001.

[0056] The electrode pads 101 may have the same size or different sizes. The electrode pads 101 may have a relatively large area, and the cantilever electrodes 103 may be formed on the electrode pads 101 , respectively.

[0057] The adhesive layer 1005 bonds the light emitting element 100 to the circuit substrate 1001. The adhesive layer 1005 is disposed between the light emitting element 100 and the circuit substrate 1001, thereby preventing the cantilever electrode 103 from being separated from the pad 1003 of the circuit substrate 1001. Furthermore, the adhesive layer 1005 may cover the circuit substrate 1001 in the region between the light emitting elements 100.

[0058] The adhesive layer 1005 may cover the cantilever electrode 103 and the electrode pad 101 and be connected to the lower surface of the light emitting element 100. The upper surface of the adhesive layer 1005 is substantially below the lower surface of the light emitting element 100. A portion of the adhesive layer 1005 may partially cover the side surface of the light emitting element 100.

[0059] As bonding layer 1005 materials, various bonding materials can be used, especially, can utilize heat curing or ultraviolet curing adhesive to form. And bonding layer 1005 can utilize material transparent to light to form, yet the present invention is not limited to this. For example, bonding layer 1005 can reflect light or absorb light, for this reason, can contain light-reflecting material or light-absorbing material in bonding layer 1005. For example, in bonding layer 1005, can contain light-absorbing material such as carbon black, or light-scattering material such as silicon dioxide.

[0060] In addition, although Figure 2 and Figure 3 Although not shown, a light-blocking material layer may be disposed in the region between the light-emitting elements 100. The light-blocking material layer absorbs or reflects light, thereby preventing light interference between the light-emitting elements from occurring, thereby improving the contrast of the display.

[0061] In this embodiment, each light emitting element 100 may constitute a pixel. For example, each light emitting element 100 may include blue, green and red sub-pixels.

[0062] Reference Figure 4a , Figure 4b , Figure 5 and Figure 6 The specific structure of the light emitting element 100 will be described. Figure 4a and Figure 4b 1 is a schematic plan view and a cross-sectional view for illustrating a light emitting element 100 according to an embodiment of the present invention. Figure 5 1 is a schematic cross-sectional view for explaining a cantilever electrode 103 of a light emitting element 100 according to an embodiment of the present invention. Figure 6 FIG. 1 is a schematic circuit diagram for illustrating a light emitting element 100 according to an embodiment of the present invention. Figure 4a and Figure 4b FIG. 1 illustrates and describes the case where the cantilever electrodes 103: 103a, 103b, 103c, 103d are arranged on the upper side, but the light emitting element 100 is Figure 3 As shown, the circuit board 1001 is flip-chip bonded, and in this case, the cantilever electrodes 103: 103a, 103b, 103c, 103d are arranged on the lower side.

[0063] First, refer to Figure 4a and Figure 4b The light emitting element 100 may include a first LED stack 23, a second LED stack 33, a third LED stack 43, a first bonding layer 30, a second bonding layer 40, a first insulating layer 51, electrode pads 101a, 101b, 101c, 101d and cantilever electrodes 103a, 103b, 103c, 103d.

[0064] The first LED stack 23, the second LED stack 33, and the third LED stack 43 may be formed using semiconductor layers grown on different growth substrates, respectively, and the growth substrates may be completely removed from the first LED stack 23, the second LED stack 33, and the third LED stack 43. Therefore, the light emitting element 100 may not include a substrate used to grow the first LED stack 23, the second LED stack 33, and the third LED stack 43. However, the present invention is not necessarily limited thereto, and at least one growth substrate may be left without being removed.

[0065] In the embodiment of the present invention, the first LED stack 23, the second LED stack 33, and the third LED stack 43 are stacked in a vertical direction. The first LED stack 23, the second LED stack 33, and the third LED stack 43 each include a first conductive semiconductor layer 23a, 33a, 43a, a second conductive semiconductor layer 23c, 33c, 43c, and an active layer 23b, 33b, 43b disposed therebetween. The active layer may have a multi-quantum well structure.

[0066] The second LED stack 33 is arranged below the first LED stack 23, and the third LED stack 43 is arranged below the second LED stack 33. For ease of description, in this specification, the second LED stack 33 is arranged below the first LED stack 23, and the third LED stack 43 is arranged below the second LED stack 33. However, it should be noted that the light-emitting elements can be flip-chip bonded, so the upper and lower positions of these first to third LED stacks can be interchanged.

[0067] The light generated in the first LED stack 23, the second LED stack 33, and the third LED stack 43 is finally emitted to the outside through the third LED stack 43. Therefore, the first LED stack 23 emits light with a longer wavelength than the second LED stack 33 and the third LED stack 43, and the second LED stack 33 emits light with a longer wavelength than the third LED stack 43. For example, the first LED stack 23 may be an inorganic light emitting diode that emits red light, the second LED stack 33 may be an inorganic light emitting diode that emits green light, and the third LED stack 43 may be an inorganic light emitting diode that emits blue light. The first LED stack 23 may include a well layer of the AlGaInP series, the second LED stack 33 may include a well layer of the AlGaInP series or the AlGaInN series, and the third LED stack 43 may include a well layer of the AlGaInN series.

[0068] Since the first LED stack 23 emits light of a longer wavelength than the second LED stack 33 and the third LED stack 43, the light generated in the first LED stack 23 can be emitted to the outside through the second LED stack 33 and the third LED stack 43. Furthermore, since the second LED stack 33 emits light of a longer wavelength than the third LED stack 43, the light generated in the second LED stack 33 can be emitted to the outside through the third LED stack 43.

[0069] In addition, the first conductive semiconductor layers 23a, 33a, 43a of each LED stack 23, 33, 43 are n-type semiconductor layers, and the second conductive semiconductor layers 23c, 33c, 43c can be p-type semiconductor layers. In addition, in the present embodiment, although the lower surfaces of the first LED stack 23, the second LED stack 33, and the third LED stack 43 are all first conductive semiconductor layers, and the upper surfaces are all second conductive semiconductor layers, the order of at least one LED stack can also be changed. For example, the upper surface of the first LED stack 23 can be the first conductive semiconductor layer 23a, and the upper surfaces of the second LED stack 33 and the third LED stack 43 can all be second conductive semiconductor layers 33c, 43c.

[0070] In this embodiment, the first LED stack 23, the second LED stack 33, and the third LED stack 43 overlap each other. Also, as shown in the figure, the first LED stack 23, the second LED stack 33, and the third LED stack 43 may have a light emitting area of ​​substantially the same size. However, since the first LED stack 23 and the second LED stack 33 may have through holes for allowing electrical connection, they may have a smaller area than the third LED stack 43.

[0071] The first bonding layer 30 bonds the first LED stack 23 to the second LED stack 33. The first bonding layer 30 may be disposed between the first conductive semiconductor layer 23a and the second conductive semiconductor layer 33c. The first bonding layer 30 may be formed using a transparent organic layer or a transparent inorganic layer. The organic layer may be, for example, SU8, polymethyl methacrylate (PMMA), polyimide, polyparaxylene, benzocyclobutene (BCB), etc., and the inorganic layer may be, for example, Al2O3, SiO2, SiN x In addition, the first bonding layer 30 may be formed using spin-on glass (SOG).

[0072] The second bonding layer 40 bonds the second LED stack 33 to the third LED stack 43. As shown in the figure, the second bonding layer 40 can be arranged between the first conductive semiconductor layer 33a and the second conductive semiconductor layer 43c. The second bonding layer 40 can be formed using the same material as that described above for the first bonding layer 30, and detailed description is omitted to avoid repetition.

[0073] The first insulating layer 51 may cover the first LED stack 23. Furthermore, the first insulating layer 51 may also cover the side surfaces of the first LED stack 23, the second LED stack 33, and the third LED stack 43. The first insulating layer 51 may be formed of a silicon oxide film or a silicon nitride film.

[0074] The electrode pads 101 : 101a, 101b, 101c, 101d may be arranged on the first insulating layer 51 . The electrode pads 101a, 101b, 101c, 101d may be electrically connected to the first LED stack 23 , the second LED stack 33 , and the third LED stack 43 through the first insulating layer 51 .

[0075] Cantilever electrodes 103: 103a, 103b, 103c, 103d are formed on electrode pads 101a, 101b, 101c, 101d, respectively. Cantilever electrodes 103a, 103b, 103c, 103d include fixed ends and free ends respectively coupled to electrode pads 101a, 101b, 101c, 101d. The free ends are separated from electrode pads 101a, 101b, 101c, 101d in the vertical direction, and sufficient space is provided between electrode pads 101a, 101b, 101c, 101d and the free ends of the cantilever electrodes to allow the free ends to descend in the vertical direction.

[0076] like Figure 4a As shown, the cantilever electrodes 103a, 103b, 103c, and 103d are arranged to be electrically isolated from each other. The cantilever electrodes 103a, 103b, 103c, and 103d may be arranged in a mutually intersecting manner, but are not limited thereto and may be arranged in various manners. The free ends of the cantilever electrodes 103a, 103b, 103c, and 103d may be connected to a circuit substrate ( Figure 3 1001), so the pads 1003 of the circuit substrate are arranged in a manner corresponding to the arrangement of the free ends.

[0077] In one embodiment, the free ends of the cantilever electrodes 103a, 103b, 103c, and 103d may all be arranged within the regions of the first LED stack 23, the second LED stack 33, and the third LED stack 43. In another embodiment, the free ends may be arranged outside the regions of the first LED stack 23, the second LED stack 33, and the third LED stack 43. Accordingly, the pad 1003 arranged on the circuit substrate 1001 may be arranged to be wider than the electrode pads 101a, 101b, 101c, and 101d.

[0078] In addition, if Figure 5 As shown, the cantilever electrode 103 may be formed of multiple metal layers 113a, 113b, and 113c. For example, the first metal layer 113a and the second metal layer 113b may have different thermal expansion coefficients, and accordingly, the free end of the cantilever electrode 103 may be bent upward. The bending of the free end of the cantilever electrode 103 generates a sharp point connected to the pad 1003 of the circuit substrate 1001. Accordingly, the sharp point of the free end scratches the surface of the pad 1003 to ensure electrical connection. In this embodiment, the angle formed by the upper surface and the side surface of the cantilever electrode 103 (that is, the angle of the sharp point of the free end) can be variously changed according to the cantilever electrode forming method. For example, in the case of forming the cantilever electrode 103 using a plating technique, the angle of the sharp point may be approximately 90 degrees, and in the case of using a lift-off technique after depositing a metal layer by an electron beam evaporation method or a sputtering technique, the angle of the sharp point may be an obtuse angle greater than 90 degrees.

[0079] In order to bend the cantilever electrode 103, the thermal expansion coefficient of the first metal layer 113a may be smaller than the thermal expansion coefficient of the second metal layer 113b. The first metal layer 113a and the second metal layer 113b may be selected from Ti, Ni, Co, Cu, Al, Pt, W, Cr, etc. For example, the first metal layer 113a may be Ti, and the first metal layer 113b may be Ni. In addition, the third metal layer 113c may be formed to protect the surface of the cantilever electrode 103, for example, it may be formed using Au.

[0080] Reference Figure 6 The cantilever electrodes 103a, 103b, and 103c may be electrically connected to the anodes of the first LED stack 23, the second LED stack 33, and the third LED stack 43, respectively, and the cantilever electrode 103d is commonly connected to the cathodes of the first LED stack 23, the second LED stack 33, and the third LED stack 43. In order to electrically connect the cantilever electrodes 103a, 103b, and 103c to the anodes of the first LED stack 23, the second LED stack 33, and the third LED stack 43, a transparent electrode may be formed on at least one of the second conductive semiconductor layers 23c, 33c, and 43c of the first LED stack 23, the second LED stack 33, and the third LED stack 43.

[0081] In addition, in this embodiment, although the cantilever electrode 103d is described as being commonly connected to the cathodes of the first LED stack 23, the second LED stack 33, and the third LED stack 43, Figure 7 As shown, the cantilever electrode 103d can also be commonly connected to the anodes of the first LED stack 23, the second LED stack 33, and the third LED stack 43. In this case, the cantilever electrodes 103a, 103b, and 103c can be connected to the cathodes of the first LED stack 23, the second LED stack 33, and the third LED stack 43, respectively.

[0082] In this embodiment, the first LED stack 23 , the second LED stack 33 , and the third LED stack 43 can be driven independently through the cantilever electrodes 103 a , 103 b , 103 c , and 103 d .

[0083] Figure 8a and Figure 8b It is a schematic cross-sectional view for explaining a method for manufacturing a light emitting element according to an embodiment of the present invention.

[0084] Reference Figure 8a , forming an LED stack on the substrate 41 ( Figure 4b The LED stacks 23, 33, 43 may be bonded to each other via the first bonding layer 30 and the second bonding layer 40.

[0085] In addition, the substrate 41 may be a growth substrate for growing the LED stack 43 , and may be, for example, a gallium nitride substrate, a SiC substrate, a sapphire substrate, or a patterned sapphire substrate.

[0086] In this embodiment, although the case where one stacked body 100a is formed on the substrate 41 is illustrated, a plurality of stacked bodies 100a may be formed on the substrate 41. In addition, the stacked body 100a may further include an insulating layer ( Figure 4b of 51).

[0087] An electrode pad 101 is formed on the stack 100a. The electrode pad 101 is electrically connected to the LED stacks 23, 33, and 43. Figure 4a As shown, four electrode pads 101 may be formed on one laminated body 100 a .

[0088] Next, a sacrificial layer 102 is formed to cover the electrode pad 101. The sacrificial layer 102 may be formed using a dielectric layer such as SiO2 or a photoresist layer. The sacrificial layer 102 has an opening to expose the electrode pad 101. Figure 8a Although the opening portion for exposing one electrode pad 101 is shown in the figure, the opening portions are formed in each of the four electrode pads 101 .

[0089] Next, the cantilever electrode 103 is formed on the sacrificial layer 102 by using a lift-off technique or a deposition and etching technique. For example, the material layer for forming the cantilever electrode 103 can be deposited by electron beam deposition, sputtering or plating technology, and the deposited material layer is patterned by using a lift-off technique or an etching technique, so that the cantilever electrode 103 can be formed on the sacrificial layer 102.

[0090] Reference Figure 8b , removing the sacrificial layer 102. At this time, the cantilever electrode 103 can bend upwards without being restrained by the sacrificial layer 102. By forming the cantilever electrode 103 with a multilayer structure of metal layers having different thermal expansion coefficients, the cantilever electrode 103 can be adjusted to bend upwards.

[0091] In this embodiment, although the cantilever electrode 103 is formed on the stacked body 100a on the growth substrate 41, the cantilever electrode 103 may be formed on the supporting substrate after the stacked body 100a formed on the growth substrate 41 is separated from the substrate 41 and transferred to another supporting substrate.

[0092] Figure 9a , Figure 9b and Fig.9c is a schematic cross-sectional view for explaining a method of manufacturing a display panel according to an embodiment of the present invention.

[0093] Reference Figure 9a , a plurality of light emitting elements 100 are arranged on a support substrate 141. The light emitting element 100 includes a cantilever electrode 103. The light emitting element 100 and the reference Figure 4a and Figure 4b The same is described, so detailed description is omitted to avoid repetition.

[0094] The support substrate 141 may be a growth substrate ( Figure 8a 41), but is not limited thereto, and may also be a support substrate different from the growth substrate 41. For example, the light emitting element 100 formed on the growth substrate 41 may be separated from the growth substrate 41 and transferred to the support substrate 141. The light emitting element 100 may be arranged on the support substrate 141 according to the pixel interval.

[0095] Reference Figure 9b A circuit substrate 1001 having a pad 1003 formed thereon is provided in each pixel region. The pad 1003 may be arranged in a manner corresponding to a free end of the cantilever electrode 103 of the light emitting element 100 .

[0096] The adhesive layer 1005 is formed to cover the pad 1003. The adhesive layer 1005 can be formed using, for example, a thermosetting or ultraviolet curing resin. However, after the adhesive substance layer is applied in this step, curing is not performed.

[0097] Reference Fig.9c The light emitting elements 100 arranged on the supporting substrate 141 move closer to the circuit substrate 1001, and the cantilever electrode 103 is connected to the pad 1003. The cantilever electrode 103 is connected to the pad 1003 by penetrating the adhesive layer 1005 with the sharp tip of the free end.

[0098] Furthermore, the light emitting element 100 is pressed toward the circuit substrate 1001, so that the cantilever electrode 103 can scratch the upper surface of the pad 1003 and easily form an electrical connection. By pressing the light emitting element 100, the cantilever electrode 103 can be bent toward the light emitting element 100. The free end of the cantilever electrode 103 is sufficiently separated from the electrode pad 101, thereby preventing an electrical short circuit between the cantilever electrode 103 and the electrode pad 101.

[0099] Thereafter, the adhesive layer 1005 is cured to bond the light emitting element 100 to the circuit board 1001. The adhesive layer 1005 can be cured by thermal curing, ultraviolet curing, or the like.

[0100] Then, the support substrate 141 can be removed from the light emitting element 100 to complete the display panel ( Figure 21000). In the case where the support substrate 141 is a growth substrate such as sapphire, the light emitting element 100 can be separated from the support substrate 141 using a laser lift-off technique. Alternatively, the light emitting element 100 can be bonded to the support substrate 141 via an adhesive layer, and the support substrate 141 can be removed by separating the light emitting element 100 from the adhesive layer.

[0101] According to the embodiment of the present invention, the plurality of light emitting elements 100 can be reliably transferred onto the circuit substrate 1001 by using the cantilever electrode 103 .

[0102] Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments. Furthermore, matters or components described in one embodiment may be applied to other embodiments without departing from the technical concept of the present invention.

Claims

1. A light emitting element, characterized in that: include: a circuit substrate having a pad; At least one LED stack is arranged on the circuit substrate; An electrode pad is arranged on a surface of the LED stack; as well as The cantilever electrode has a fixed end and a free end, wherein the fixed end is fixed to the electrode pad and the free end is separated from the electrode pad. Wherein, the free end is arranged toward the outside of the LED stack, the fixed end and the free end include at least two metal layers with different thermal expansion coefficients, the free end is bent in a direction away from the at least one LED stack, and is electrically connected to the pad exposed by the circuit substrate arranged opposite to a surface of the at least one LED stack on which the electrode pad is arranged.

2. The light emitting element according to claim 1, characterized in that The at least one LED stack comprises: a first LED stack; a second LED stack; and The third LED stack, The light emitting element comprises: A first bonding layer is sandwiched between the first LED stack and the second LED stack; and A second bonding layer is sandwiched between the second LED stack and the third LED stack, The first LED stack to the third LED stack emit light having different wavelengths. The electrode pad is electrically connected to the first to third LED stacks in a manner of individually driving the first to third LED stacks.

3. The light emitting element according to claim 1, wherein: The maximum width of the light emitting element is less than 10 μm.

4. A display panel, characterized in that: include: a circuit substrate having a pad; A light emitting element, electrically connected to the pad and arranged on the circuit substrate; as well as an adhesive layer disposed between the circuit substrate and the light emitting element to bond the circuit substrate and the light emitting element, Wherein, the light emitting elements respectively include: at least one LED stack; An electrode pad is arranged on a surface of the LED stack; and The cantilever electrode has a fixed end and a free end, wherein the fixed end is fixed to a surface of the electrode pad, and the free end is separated from the electrode pad. The fixed end and the free end include at least two metal layers with different thermal expansion coefficients, the free end is arranged toward the outside of the LED stack, the free end is bent in a direction away from the at least one LED stack, and is electrically connected to the pad exposed by the circuit substrate arranged opposite to a surface of the at least one LED stack on which the electrode pad is arranged.

5. The display panel according to claim 4, characterized in that: The light emitting elements are arranged at a pitch of 50 μm or less.

6. The display panel according to claim 4, characterized in that: The light emitting elements are arranged at a pitch of 10 μm or less.

7. The display panel according to claim 4, characterized in that: The metal layer is selected from Ni, Co, Cu, Ti, Al or Pt.

8. The display panel according to claim 4, characterized in that: The at least one LED stack comprises: a first LED stack; a second LED stack; and The third LED stack, The light emitting element comprises: A first bonding layer is sandwiched between the first LED stack and the second LED stack; and A second bonding layer is sandwiched between the second LED stack and the third LED stack, The first LED stack to the third LED stack emit light having different wavelengths. The electrode pad is electrically connected to the first to third LED stacks in a manner of individually driving the first to third LED stacks.

9. The display panel according to claim 8, characterized in that: The light emitting element emits the light generated in the first to third LED stacks through the third LED stack.

10. The display panel according to claim 9, characterized in that: The third LED stack is separated from the growth substrate.

11. The display panel according to claim 8, characterized in that: The adhesive layer partially covers the side surfaces of the light emitting element.

12. The display panel according to claim 11, characterized in that: The bonding layer is formed using a curable resin.

13. A display device, comprising a display panel, characterized in that: The display panel comprises: a circuit substrate having a pad; a light emitting element electrically connected to the pad and arranged on the circuit substrate; and an adhesive layer disposed between the circuit substrate and the light emitting element to bond the circuit substrate and the light emitting element, Wherein, the light emitting elements respectively include: at least one LED stack; An electrode pad is arranged on a surface of the LED stack; and The cantilever electrode has a fixed end and a free end, wherein the fixed end is fixed to the electrode pad and the free end is separated from the electrode pad. The fixed end and the free end include at least two metal layers with different thermal expansion coefficients, the free end is arranged toward the outside of the LED stack, the free end is bent in a direction away from the at least one LED stack, and is electrically connected to the pad exposed by the circuit substrate arranged opposite to a surface of the at least one LED stack on which the electrode pad is arranged, The adhesive layer covers the free end and the electrode pad, and covers at least a portion of a side surface of the light emitting element.

14. The display device according to claim 13, characterized in that: The light emitting elements are arranged at a pitch of 10 μm or less.

15. The display device according to claim 13, characterized in that: The at least one LED stack includes a first LED stack, a second LED stack, and a third LED stack, wherein the first LED stack to the third LED stack emit light having different wavelengths. The light emitting element emits the light generated in the first to third LED stacks through the third LED stack.

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