Light emitting diode capable of improving transfer yield, preparation method thereof and display panel
By forming a recessed structure at the first surface and side wall of the epitaxial layer and filling the cladding layer, the problem that the epitaxial layer is difficult to accurately detach the substrate during laser peeling is solved, and the transfer yield of the light emitting diode is improved.
Patent Information
- Application Number
- CN202411947399.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-27
- Publication Date
- 2025-05-13
AI Technical Summary
During the laser peeling process, it is difficult for the epitaxial layer to accurately detach the substrate, and the passivation layer residues affect the transfer yield.
A recessed structure is formed at the connection between the first surface of the epitaxial layer and the side wall, and a cladding layer is formed in the recessed structure to fill the recessed structure to reduce the connection area between the epitaxial layer and the substrate and improve the reliability of laser peeling.
By reducing the connection area between the epitaxial layer and the substrate, the epitaxial layer is more likely to fall off the substrate, and the disconnection of the cladding layer avoids falling off the residue, and improves the transfer yield of the light emitting diode.
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Figure CN119997681A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of optoelectronic manufacturing technology, and in particular to a light emitting diode with improved transfer yield, a preparation method thereof, and a display panel. Background Art
[0002] Light Emitting Diode (LED) is an extremely influential new product in the optoelectronics industry. It has the characteristics of small size, long service life, rich colors and low energy consumption. It is widely used in lighting, display screens, signal lights, backlight sources, toys and other fields.
[0003] In the related art, a light emitting diode generally includes a substrate, an epitaxial layer and a passivation layer, wherein the epitaxial layer and the passivation layer are sequentially stacked on the surface of the substrate. Usually, the passivation layer is also located on the sidewall of the epitaxial layer and the surface of the substrate, that is, the passivation layer covers the epitaxial layer.
[0004] However, during laser stripping of the substrate, the passivation layer attached to the substrate is not easy to absorb laser decomposition, which causes the epitaxial layer to pull the passivation layer covering the substrate during the process of detaching from the substrate. This makes it difficult for the light-emitting diode to accurately fall to the corresponding position on the circuit board after it falls off the substrate, and some residues of the passivation layer will also fall on the circuit board, affecting the transfer yield of the light-emitting diode. Summary of the invention
[0005] The embodiments of the present disclosure provide a light emitting diode with improved transfer yield, a method for manufacturing the same, and a display panel, which can reduce the difficulty of laser stripping the epitaxial layer from the substrate and improve the transfer yield of the light emitting diode. The technical solution is as follows:
[0006] An embodiment of the present disclosure provides a light-emitting diode, which includes: an epitaxial layer and a cladding layer, the epitaxial layer having a first surface and a second surface opposite to each other, and a side wall connecting the first surface and the second surface, and a recessed structure at a connection between the first surface and the side wall of the epitaxial layer; the cladding layer is located on the second surface, the side wall of the epitaxial layer and the recessed structure, and fills the recessed structure.
[0007] In another implementation of the embodiment of the present disclosure, the recessed structure is recessed toward the middle of the epitaxial layer, and the recessed depth of the recessed structure is 3 μm to 6 μm.
[0008] In another implementation of the embodiment of the present disclosure, the recessed structure surrounds the epitaxial layer.
[0009] In another implementation of the embodiment of the present disclosure, the sidewall of the epitaxial layer is inclined to the first surface, and the angle between the first surface and the sidewall of the epitaxial layer is less than 90 degrees.
[0010] In another implementation of the embodiment of the present disclosure, the coating layer includes at least one of a silicon oxide layer, a silicon nitride layer and a titanium oxide layer.
[0011] In another implementation of the embodiment of the present disclosure, the epitaxial layer includes a first semiconductor layer, a multi-quantum well layer, and a second semiconductor layer stacked in sequence, and the recessed structure is located at least on a side wall of the first semiconductor layer.
[0012] An embodiment of the present disclosure provides a method for preparing a light-emitting diode, the method comprising: forming an epitaxial layer on a substrate, the epitaxial layer having a first surface and a second surface opposite to each other, and a side wall connecting the first surface and the second surface, the first surface being located on the substrate; forming a recessed structure at a connection point between the side wall of the epitaxial layer and the first surface; forming a coating layer on the second surface, the side wall of the epitaxial layer and the recessed structure, the coating layer filling the recessed structure.
[0013] In another implementation of the embodiment of the present disclosure, forming a recessed structure at the junction of the side wall of the epitaxial layer and the first surface includes: placing the substrate formed with the epitaxial layer in a mixed solution of phosphoric acid and sulfuric acid, soaking for 10 to 20 minutes, and controlling the temperature of the mixed solution to 200°C to 300°C to form the recessed structure on the side wall of the epitaxial layer.
[0014] In another implementation of the embodiment of the present disclosure, forming a coating layer on the second surface, the side wall of the epitaxial layer and the recessed structure includes: etching the second surface of the epitaxial layer so that the side wall of the epitaxial layer is inclined to the first surface, and the angle between the first surface and the side wall of the epitaxial layer is less than 90 degrees; forming the coating layer on the second surface, the side wall of the epitaxial layer and the recessed structure.
[0015] An embodiment of the present disclosure provides a display panel, which includes a light-emitting functional layer and a driving backplane. The light-emitting functional layer is located on the driving backplane and is electrically connected to the driving backplane. The light-emitting functional layer includes a plurality of light-emitting diodes as described above.
[0016] The beneficial effects brought by the technical solution provided by the embodiments of the present disclosure include at least:
[0017] The light-emitting diode provided by the embodiment of the present disclosure includes an epitaxial layer and a coating layer, and the connection between the first surface of the epitaxial layer and the side wall has a recessed structure, and the coating layer covers the epitaxial layer and fills the recessed structure. In the process of preparing the light-emitting diode, the first surface of the epitaxial layer is located on the substrate. That is, the first surface of the epitaxial layer and the substrate are separated during laser stripping. By setting a recessed structure at the connection between the first surface and the side wall, firstly, the connection area between the epitaxial layer and the substrate can be reduced, so that the epitaxial layer can be more easily removed from the substrate; secondly, the coating layer is filled in the recessed structure, that is, the coating layer located in the recessed structure is stacked, and the coating layer stacked in the recessed structure itself has a bend, so the coating layer filled in the recessed structure is easier to break during laser stripping, so that the epitaxial layer can be more easily removed from the substrate. This avoids the problem that the epitaxial layer will pull the coating layer covering the substrate during the process of detaching from the substrate, and enables the light-emitting diode to accurately fall to the corresponding position on the circuit board after laser stripping. Furthermore, the coating layer will not produce debris that falls on the circuit board due to tearing, thereby affecting the transfer yield of the light-emitting diodes. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0019] Figure 1 It is a schematic diagram of laser lift-off of a light-emitting diode provided by the related technology;
[0020] Figure 2 is a structural schematic diagram of a light emitting diode provided by an embodiment of the present disclosure;
[0021] Figure 3 is a flow chart of a method for preparing a light emitting diode provided by an embodiment of the present disclosure;
[0022] Figure 4 It is a schematic diagram of laser lift-off of a light-emitting diode provided in an embodiment of the present disclosure.
[0023] The descriptions of the marks in the figure are as follows:
[0024] 10. Substrate;
[0025] 20. epitaxial layer; 21. first semiconductor layer; 22. multi-quantum well layer; 23. second semiconductor layer;
[0026] 201, first surface; 202, second surface; 203, recessed structure;
[0027] 30, coating; 31, debris;
[0028] 40. Transparent conductive layer;
[0029] 50. Electrode;
[0030] 60. Circuit board. DETAILED DESCRIPTION
[0031] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.
[0032] Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons with ordinary skills in the field to which the present disclosure belongs. The words "first", "second", "third" and similar words used in the patent application specification and claims of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not indicate a quantity limitation, but indicate the existence of at least one. Words such as "include" or "comprise" and similar words mean that the elements or objects appearing before "include" or "comprise" include the elements or objects listed after "include" or "comprise" and their equivalents, and do not exclude other elements or objects. Words such as "connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right", "top", "bottom" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.
[0033] Figure 1 FIG. 1 is a schematic diagram of laser lift-off of a light-emitting diode provided by the related art. Figure 1 As shown, in the related art, the light emitting diode includes a substrate 10, an epitaxial layer 20 and a passivation layer, and the epitaxial layer 20 and the passivation layer are sequentially stacked on the surface of the substrate 10, and the passivation layer covers the epitaxial layer 20. An electrode 50 is also provided on the surface of the passivation layer, and the electrode 50 is connected to the epitaxial layer 20 through a through hole on the passivation layer.
[0034] like Figure 1 As shown, the light emitting diode is suspended above the circuit board 60 , and the electrode 50 of the light emitting diode faces the circuit board 60 .
[0035] like Figure 1As shown, during the laser lift-off process, the laser is irradiated at the junction of the substrate 10 and the epitaxial layer 20, and the bonding material between the epitaxial layer 20 and the substrate 10 is decomposed by the laser, so that the epitaxial layer 20 and the substrate 10 are peeled off. The epitaxial layer 20 is peeled off from the substrate 10, and the epitaxial layer 20 is accurately dropped to the set position of the circuit board 60, so that the electrode 50 is connected to the corresponding position of the circuit board 60.
[0036] like Figure 1 As shown, in addition to covering the epitaxial layer 20, part of the epitaxial layer 20 extends to the surface of the substrate 10. Since the passivation layer attached to the substrate 10 is not easy to absorb laser decomposition, the epitaxial layer 20 will pull the passivation layer covering the substrate 10 during the process of separating from the substrate 10, making it difficult for the light-emitting diode to fall accurately to the corresponding position on the circuit board 60 after falling off from the substrate 10, and part of the residue 31 of the passivation layer will also fall on the circuit board 60, affecting the transfer yield of the light-emitting diode.
[0037] To this end, an embodiment of the present disclosure provides a light emitting diode. Figure 2 Schematic diagram of the structure of a light emitting diode provided by an embodiment of the present disclosure. Figure 2 As shown, the light emitting diode comprises: an epitaxial layer 20 and a cladding layer 30. The epitaxial layer 20 has a first surface 201 and a second surface 202 opposite to each other, and a side wall connecting the first surface 201 and the second surface 202. The connection between the first surface 201 and the side wall of the epitaxial layer 20 has a recessed structure 203.
[0038] like Figure 2 As shown, the cladding layer 30 is located on the second surface 202 , the sidewall of the epitaxial layer 20 and in the recessed structure 203 , and the cladding layer 30 fills the recessed structure 203 , that is, the cladding layer 30 contacts the surface of the recessed structure 203 .
[0039] The light-emitting diode provided by the embodiment of the present disclosure includes an epitaxial layer 20 and a cladding layer 30. The connection between the first surface 201 of the epitaxial layer 20 and the side wall has a recessed structure 203. The cladding layer 30 covers the epitaxial layer 20 and fills the recessed structure 203. In the process of preparing the light-emitting diode, the first surface 201 of the epitaxial layer 20 is located on the substrate 10. That is, during laser lift-off, the first surface 201 of the epitaxial layer 20 and the substrate 10 are separated. By providing a recessed structure 203 at the connection point between the first surface 201 and the side wall, firstly, the connection area between the epitaxial layer 20 and the substrate 10 can be reduced, so that the epitaxial layer 20 can be more easily removed from the substrate 10; secondly, the cladding layer 30 is filled in the recessed structure 203, that is, the cladding layer 30 located in the recessed structure 203 is stacked, and the cladding layer 30 stacked in the recessed structure 203 itself has a bend, so the cladding layer 30 filled in the recessed structure 203 is more likely to be broken during laser stripping, so that the epitaxial layer 20 can be more easily removed from the substrate 10. This avoids the problem that the epitaxial layer 20 will pull the cladding layer 30 covering the substrate 10 during the process of detaching from the substrate 10, and enables the light-emitting diode to fall accurately to the corresponding position on the circuit board after laser stripping. In addition, the cladding layer 30 will not produce debris falling on the circuit board due to tearing, which will affect the transfer yield of the light-emitting diode.
[0040] Optionally, the recessed structure 203 is recessed toward the middle of the epitaxial layer 20 , and the recessed depth of the recessed structure 203 is 3 μm to 6 μm.
[0041] For example, Figure 2 As shown, the recess depth of the recess structure 203 refers to the maximum length of the recess structure 203 recessed toward the central area of the epitaxial layer 20 in a direction parallel to the substrate 10 .
[0042] As an example, in the embodiment of the present disclosure, the recessed depth of the recessed structure 203 is 5 μm.
[0043] like Figure 2 As shown, the recessed structure 203 is concave, and the cross-sectional shape of the recessed structure 203 in a direction perpendicular to the substrate 10 is a triangle.
[0044] By controlling the recess depth of the recess structure 203 within the above range, it can be ensured that the recess depth of the recess structure 203 is large enough to ensure that the cladding layer 30 filled in the recess structure 203 can be stacked multiple times in the recess structure 203. In this way, the cladding layer 30 filled in the recess structure 203 has multiple bends, so that the cladding layer 30 in the recess structure 203 is easier to break during laser stripping, thereby allowing the epitaxial layer 20 to more easily fall off from the substrate 10.
[0045] Optionally, the recessed structure 203 surrounds the epitaxial layer 20. That is, the recessed structure 203 circumferentially surrounds the epitaxial layer 20. Such provision of the recessed structure 203 can minimize the contact area between the epitaxial layer 20 and the substrate 10, thereby making it easier for the epitaxial layer 20 to fall off from the substrate 10.
[0046] Optionally, the recess structure 203 includes a plurality of holes circumferentially arranged at intervals on the sidewall of the epitaxial layer 20 .
[0047] Alternatively, if Figure 2 As shown, the sidewall of the epitaxial layer 20 is inclined to the first surface 201 , and the angle between the first surface 201 and the sidewall of the epitaxial layer 20 is less than 90 degrees.
[0048] In the embodiment of the present disclosure, the side wall of the epitaxial layer 20 is inclined to the first surface 201, which is perpendicular to the first surface 201 compared to the side wall of the epitaxial layer 20. In this way, when the cladding layer 30 is subsequently formed, the preparation material of the cladding layer 30 is easily attached to the side wall of the epitaxial layer 20, and when the preparation material of the cladding layer 30 is attached to the side wall of the epitaxial layer 20 close to the edge of the recessed structure 203, as the preparation material of the cladding layer 30 accumulates, the preparation material of the cladding layer 30 naturally easily enters the recessed structure 203 to fill the recessed structure 203, so that the preparation material of the cladding layer 30 contacts the surface of the recessed structure 203. In this way, the preparation material of the cladding layer 30 is stacked multiple times in the recessed structure 203, rather than a whole film layer that is continuously grown. Such a cladding layer 30 is easier to break during laser stripping, so that the epitaxial layer 20 is easier to fall off from the substrate 10.
[0049] Optionally, the coating layer 30 includes at least one of a silicon oxide layer, a silicon nitride layer, and a titanium oxide layer.
[0050] For example, the cladding layer 30 may be a silicon oxide layer. The silicon oxide layer has good insulation properties, and can effectively prevent the epitaxial layer 20 from contacting other film layers and causing short circuits, thereby improving the reliability of the light-emitting diode.
[0051] Illustratively, the thickness of the silicon oxide layer may be 2000 angstroms to 5000 angstroms.
[0052] Alternatively, if Figure 2 As shown, the epitaxial layer 20 includes a first semiconductor layer 21 , a multi-quantum well layer 22 , and a second semiconductor layer 23 which are stacked in sequence, and the recessed structure 203 is at least located on the side wall of the first semiconductor layer 21 .
[0053] For example, Figure 2As shown, the recessed structure 203 is located on the side wall of the first semiconductor layer 21. In this way, the multi-quantum well layer 22 will not be removed when the recessed structure 203 is formed. Since the multi-quantum well layer 22 is a film layer used for emitting light on the light-emitting diode, the recessed structure 203 is only located on the side wall of the first semiconductor layer 21, which can ensure the light-emitting effect of the light-emitting diode.
[0054] For example, Figure 2 As shown, the recessed structure 203 can also be located on the sidewall of the first semiconductor layer 21 and the sidewall of the multi-quantum well layer 22 at the same time. That is, the height of the recessed structure 203 is greater than the thickness of the first semiconductor layer 21. In this way, more of the first semiconductor layer 21 can be removed to further reduce the contact area between the epitaxial layer 20 and the substrate 10, thereby facilitating the epitaxial layer 20 to quickly fall off from the substrate 10.
[0055] In the embodiment of the present disclosure, one of the first semiconductor layer 21 and the second semiconductor layer 23 is an n-type layer, and the other of the first semiconductor layer 21 and the second semiconductor layer 23 is a p-type layer.
[0056] Exemplarily, the first semiconductor layer 21 is an n-type layer, and the second semiconductor layer 23 is a p-type layer.
[0057] The following is an illustrative description of each layer structure by taking the blue light epitaxial structure as an example in which the epitaxial layer 20 is an epitaxial structure of blue light. In the epitaxial structure of blue light, the p-type layer includes a p-type GaN layer.
[0058] The multi-quantum well layer 22 may include alternately grown InGaN quantum well layers and GaN quantum barrier layers. The third light emitting layer may include 3 to 8 periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.
[0059] The n-type layer includes an n-type GaN layer.
[0060] Optionally, the epitaxial layer 20 has a thickness of 2 μm to 10 μm.
[0061] Exemplarily, the thickness of the epitaxial layer 20 is 6 μm.
[0062] Alternatively, if Figure 2 As shown, the light emitting diode further includes a transparent conductive layer 40 , and the transparent conductive layer 40 is located on the surface of the second semiconductor layer 23 .
[0063] The transparent conductive layer 40 is a film layer connected to the electrode 50. The transparent conductive layer 40 can laterally expand the current injected by the electrode 50, so that the current can be injected into various regions of the epitaxial layer 20, thereby improving the luminous efficiency.
[0064] For example, the transparent conductive layer 40 may be an indium tin oxide (ITO) layer or an indium zinc oxide (IZO) layer. The indium tin oxide layer or the indium zinc oxide layer has good transmittance and low resistivity, which can allow more light to be transmitted from the transparent conductive layer 40, thereby ensuring the light output effect; at the same time, due to the low resistivity, it is also convenient for carrier conduction and improves the injection efficiency.
[0065] As an example, the thickness of the transparent conductive layer 40 may be 1000 angstroms to 5000 angstroms. For example, the thickness of the transparent conductive layer 40 is 2000 angstroms.
[0066] Alternatively, if Figure 2 As shown, the surface of the second semiconductor layer 23 has a groove exposing the first semiconductor layer 21. The cladding layer 30 is also located in the groove and on the surface of the first semiconductor layer 21, and the cladding layer 30 covers the transparent conductive layer 40.
[0067] Optionally, the coating layer 30 includes at least one of a silicon oxide layer, a silicon nitride layer, and a titanium oxide layer.
[0068] Exemplarily, the cladding layer 30 may be a silicon oxide layer.
[0069] The thickness of the silicon oxide layer may be 5000 angstroms.
[0070] Alternatively, if Figure 2 As shown, the light emitting diode further includes at least two electrodes 50, and the at least two electrodes 50 are both located on the surface of the cladding layer 30 away from the epitaxial layer 20. The surface of the cladding layer 30 has through holes that respectively expose the bottom of the groove and the transparent conductive layer 40. One of the electrodes 50 is connected to the first semiconductor layer 21 through the through hole, and the other electrode 50 is connected to the transparent conductive layer 40 through the through hole.
[0071] Optionally, the at least two electrodes 50 include a p-electrode 50 and an n-electrode 50. The p-electrode 50 is used to connect to the p-type layer, and the n-electrode 50 is used to connect to the n-type layer.
[0072] Figure 3 FIG. 1 is a flow chart of a method for preparing a light emitting diode provided by an embodiment of the present disclosure. Figure 3 As shown, the preparation method comprises:
[0073] Step S11 : forming an epitaxial layer 20 on the substrate 10 .
[0074] The epitaxial layer 20 has a first surface 201 and a second surface 202 opposite to each other, and a sidewall connecting the first surface 201 and the second surface 202 . The first surface 201 is located on the substrate 10 .
[0075] Exemplarily, the epitaxial layer 20 includes a first semiconductor layer 21 , a multi-quantum well layer 22 , and a second semiconductor layer 23 which are sequentially stacked.
[0076] Growing the epitaxial layer 20 may include: sequentially forming a first semiconductor layer 21 , a multi-quantum well layer 22 , and a second semiconductor layer 23 on the substrate 10 by using MOCVD technology.
[0077] One of the first semiconductor layer 21 and the second semiconductor layer 23 is an n-type layer, and the other of the first semiconductor layer 21 and the second semiconductor layer 23 is a p-type layer.
[0078] Exemplarily, the epitaxial layer 20 includes an n-type GaN layer, a multi-quantum well layer 22 , and a p-type GaN layer stacked in sequence.
[0079] Optionally, the thickness of the n-type GaN layer may be 0.5 μm to 3 μm.
[0080] The growth temperature of the n-type GaN layer may be 1000° C. to 1100° C., and the growth pressure of the n-type GaN layer may be 100 torr to 300 torr.
[0081] Optionally, the multi-quantum well layer 22 includes alternately grown InGaN quantum well layers and GaN quantum barrier layers. The multi-quantum well layer 22 may include 3 to 8 periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.
[0082] When growing the multi-quantum well layer 22, the pressure of the MOCVD reaction chamber is controlled at 200 torr. When growing the InGaN quantum well layer, the temperature of the reaction chamber is 760° C. to 780° C. When growing the GaN quantum barrier layer, the temperature of the reaction chamber is 860° C. to 890° C.
[0083] As an example, in the embodiment of the present disclosure, the multi-quantum well layer 22 includes five periods of alternately stacked InGaN quantum well layers and GaN quantum barrier layers.
[0084] Optionally, the thickness of the multi-quantum well layer 22 may be 150 nm to 200 nm.
[0085] Optionally, the p-type GaN layer may have a thickness of 0.5 μm to 3 μm.
[0086] When growing the p-type GaN layer, the growth pressure of the p-type GaN layer may be 200 Torr to 600 Torr, and the growth temperature of the p-type GaN layer may be 800° C. to 1000° C.
[0087] After growing the epitaxial layer 20 , step S12 may further include: etching the surface of the second semiconductor layer 23 to form a groove that at least exposes the multi-quantum well layer 22 .
[0088] Specifically, it may include: forming a mask on the surface of the second semiconductor layer 23 by photolithography, and then forming a groove on the surface of the second semiconductor layer 23 by plasma etching through the mask.
[0089] During the etching process, the upper power of the etching equipment is controlled to be 300W to 600W, and the lower power is controlled to be 100W to 300W.
[0090] Exemplarily, the groove depth of the recess is 1 μm to 2 μm.
[0091] Before executing step S12, the method may also include: using an infrared laser to perform front-side scribing according to a preset chip position, with a scribing depth of 5 μm to 10 um to form an isolation groove, separating the epitaxial layer 20 on the substrate 10 through the isolation groove, and the width of the isolation groove is less than or equal to 10 um.
[0092] Step S12 : forming a recess structure 203 at the junction of the sidewall of the epitaxial layer 20 and the first surface 201 .
[0093] Specifically, the method may include placing the substrate 10 formed with the epitaxial layer 20 in a mixed solution of phosphoric acid and sulfuric acid for 10 to 20 minutes, and controlling the temperature of the mixed solution to be 200° C. to 300° C. to form a recessed structure 203 on the side wall of the epitaxial layer 20 .
[0094] For example, if the recessed structure 203 to be formed is only located on the sidewall of the first semiconductor layer 21 , the liquid level of the mixed solution can be controlled to be less than or equal to the thickness of the first semiconductor layer 21 to prevent the mixed solution from corroding other film layers.
[0095] After the recessed structure 203 is formed in step S12 , the method further includes: forming a transparent conductive layer 40 on a surface of the second semiconductor layer 23 away from the first semiconductor layer 21 .
[0096] Exemplarily, the transparent conductive layer 40 may be an indium tin oxide or indium zinc oxide layer.
[0097] As an example, the thickness of the transparent conductive layer 40 may be 1000 angstroms to 5000 angstroms. For example, the thickness of the transparent conductive layer 40 is 2000 angstroms.
[0098] Step S13 : forming a cladding layer 30 on the second surface 202 , the sidewall of the epitaxial layer 20 and in the recess structure 203 .
[0099] The coating layer 30 fills the recessed structure 203 .
[0100] Step S13 may specifically include: first, etching the second surface 202 of the epitaxial layer 20 , so that the sidewall of the epitaxial layer 20 is inclined to the first surface 201 .
[0101] Exemplarily, the angle between the first surface 201 and the sidewall of the epitaxial layer 20 is less than 90 degrees.
[0102] In the embodiment of the present disclosure, the side wall of the epitaxial layer 20 is inclined to the first surface 201, compared with the side wall of the epitaxial layer 20 being perpendicular to the first surface 201. In this way, when the cladding layer 30 is subsequently formed, the preparation material of the cladding layer 30 is easily attached to the side wall of the epitaxial layer 20, and when the preparation material of the cladding layer 30 is attached to the side wall of the epitaxial layer 20 close to the edge of the recessed structure 203, as the preparation material of the cladding layer 30 accumulates, the preparation material of the cladding layer 30 naturally easily enters the recessed structure 203 to fill the recessed structure 203, so that the preparation material of the cladding layer 30 contacts the surface of the recessed structure 203.
[0103] Then, a cladding layer 30 is formed on the second surface 202 , the sidewall of the epitaxial layer 20 , and in the recess structure 203 .
[0104] Optionally, the coating layer 30 includes at least one of a silicon oxide layer, a silicon nitride layer, and a titanium oxide layer.
[0105] For example, the cladding layer 30 may be a silicon oxide layer. The silicon oxide layer has good insulation properties, and can effectively prevent the epitaxial layer 20 from contacting other film layers and causing short circuits, thereby improving the reliability of the light-emitting diode.
[0106] Illustratively, the thickness of the cladding layer 30 may be 2000 angstroms to 5000 angstroms.
[0107] Next, the cladding layer 30 is etched to form through holes exposing the transparent conductive layer 40 and the grooves on the surface of the passivation layer.
[0108] Etching can be achieved by dry etching, or by photolithography combined with wet etching, such as H 3 PO 4 / H 2 SO 4 The mixed solution is used for etching, or laser front scribing is used for implementation.
[0109] Then, an electrode 50 is formed on a surface of the cladding layer 30 away from the substrate 10 , and the electrode 50 is connected to the transparent conductive layer 40 and the first semiconductor layer 21 in the groove through the through hole.
[0110] Specifically, the method may include: manufacturing the p-electrode 50 and the n-electrode 50 by photolithography and evaporation.
[0111] The n-electrode 50 is located in the groove and connected to the n-type layer through a through hole, and the p-electrode 50 is connected to the transparent conductive layer 40 through a through hole.
[0112] Finally, the substrate 10 is laser-lifted off.
[0113] Figure 4 FIG. 1 is a schematic diagram of laser lift-off of a light emitting diode provided by an embodiment of the present disclosure. Figure 4 As shown, during the laser lift-off process, the light emitting diode is suspended above the circuit board 60 , and the electrode 50 of the light emitting diode faces the circuit board 60 .
[0114] like Figure 4 As shown, during the laser lift-off process, the laser is irradiated at the interface between the substrate 10 and the epitaxial layer 20, and the bonding material between the epitaxial layer 20 and the substrate 10 is decomposed by the laser, so that the epitaxial layer 20 and the substrate 10 are peeled off. The epitaxial layer 20 is peeled off from the substrate 10, so that the epitaxial layer 20 accurately falls to the set position of the circuit board 60, so that the electrode 50 is connected to the corresponding position of the circuit board 60.
[0115] like Figure 4 As shown, since a recessed structure 203 is provided at the junction of the epitaxial layer 20 and the substrate 10, the coating layer 30 in the recessed structure 203 is easily broken under laser irradiation. Therefore, the light-emitting diode is more likely to fall off from the substrate 10 after laser irradiation, and can accurately fall to the corresponding position on the circuit board 60. In addition, the epitaxial layer 20 will not pull the coating layer 30 covering the substrate 10 during the process of detaching from the substrate 10, and the residues 31 of the coating layer 30 are all retained on the substrate 10 and will not fall on the circuit board 60, so the transfer yield of the light-emitting diode can be effectively improved.
[0116] An embodiment of the present disclosure provides a display panel, which includes a light-emitting functional layer and a driving backplane. The light-emitting functional layer is located on the driving backplane and is electrically connected to the driving backplane. The light-emitting functional layer includes a plurality of light-emitting diodes as described above.
[0117] Optionally, the driving backplane may be a TFT (Thin Film Transistor) substrate, the driving backplane includes a plurality of driving circuits arranged in an array, and each driving circuit on the driving backplane includes at least two TFTs for controlling the light emission of the connected light emitting layer.
[0118] Exemplarily, the driving circuit includes an active layer, a gate insulating layer, a gate layer, an interlayer dielectric layer and a source-drain electrode layer sequentially stacked on a substrate, and the light-emitting layer is connected to the source-drain electrode layer of the corresponding driving circuit.
[0119] The TFT of the driving backplane may be made of a variety of materials such as polysilicon and metal oxide, which is not limited in the embodiments of the present disclosure.
[0120] The display device can be any product or component with a display function, such as a mobile phone, a tablet computer, a television, a monitor, a notebook computer, a digital photo frame, a navigator, etc.
[0121] The above does not limit the present disclosure in any form. Although the present disclosure has been disclosed as above through the embodiments, it is not used to limit the present disclosure. Any technician familiar with the profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present disclosure. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present disclosure without departing from the content of the technical solution of the present disclosure still falls within the scope of the technical solution of the present disclosure.
Claims
1. A light emitting diode, characterized in that: The light emitting diode comprises: an epitaxial layer (20) and a cladding layer (30), the epitaxial layer (20) having a first surface (201) and a second surface (202) opposite to each other, and a side wall connecting the first surface (201) and the second surface (202), and a concave structure (203) at a connection point between the first surface (201) and the side wall of the epitaxial layer (20); The cladding layer (30) is located on the second surface (202), the side wall of the epitaxial layer (20) and inside the recessed structure (203), and fills the recessed structure (203).
2. The light emitting diode according to claim 1, characterized in that: The recessed structure (203) is recessed toward the middle of the epitaxial layer (20), and the recessed depth of the recessed structure (203) is 3 μm to 6 μm.
3. The light emitting diode according to claim 1, characterized in that: The recessed structure (203) surrounds the epitaxial layer (20).
4. The light emitting diode according to any one of claims 1 to 3, characterized in that: The side wall of the epitaxial layer (20) is inclined to the first surface (201), and the angle between the first surface (201) and the side wall of the epitaxial layer (20) is less than 90 degrees.
5. The light emitting diode according to any one of claims 1 to 3, characterized in that: The coating layer (30) includes at least one of a silicon oxide layer, a silicon nitride layer and a titanium oxide layer.
6. The light emitting diode according to any one of claims 1 to 3, characterized in that: The epitaxial layer (20) comprises a first semiconductor layer (21), a multi-quantum well layer (22) and a second semiconductor layer (23) which are stacked in sequence, and the recessed structure (203) is at least located on the side wall of the first semiconductor layer (21).
7. A method for preparing a light emitting diode, characterized in that: The preparation method comprises: An epitaxial layer (20) is formed on a substrate (10), wherein the epitaxial layer (20) has a first surface (201) and a second surface (202) opposite to each other, and a side wall connecting the first surface (201) and the second surface (202), wherein the first surface (201) is located on the substrate (10); forming a recessed structure (203) at a junction between a side wall of the epitaxial layer (20) and the first surface (201); A cladding layer (30) is formed on the second surface (202), the side wall of the epitaxial layer (20) and in the recessed structure (203), and the cladding layer (30) fills the recessed structure (203).
8. The preparation method according to claim 7, characterized in that: Forming a recessed structure (203) at a junction between the side wall of the epitaxial layer (20) and the first surface (201) comprises: The substrate (10) formed with the epitaxial layer (20) is placed in a mixed solution of phosphoric acid and sulfuric acid and immersed for 10 to 20 minutes, and the temperature of the mixed solution is controlled to be 200° C. to 300° C., so as to form the recessed structure (203) on the side wall of the epitaxial layer (20).
9. The preparation method according to claim 7, characterized in that: Forming a cladding layer (30) on the second surface (202), the sidewall of the epitaxial layer (20) and in the recessed structure (203) comprises: Etching the second surface (202) of the epitaxial layer (20) so that the side wall of the epitaxial layer (20) is inclined to the first surface (201), and the angle between the first surface (201) and the side wall of the epitaxial layer (20) is less than 90 degrees; The cladding layer (30) is formed on the second surface (202), the sidewall of the epitaxial layer (20) and in the recessed structure (203).
10. A display panel, characterized in that: The display panel includes a light-emitting functional layer and a driving backplane, the light-emitting functional layer is located on the driving backplane and is electrically connected to the driving backplane, and the light-emitting functional layer includes a plurality of light-emitting diodes as described in any one of claims 1 to 6.