Light-emitting structure and preparation method thereof
By directly preparing the color conversion structure on the luminescent chip wafer and cutting it into a single luminescent chip grain for single chip bonding with the driver chip grain, the problem of difficult and poor quality of single chip bonding process of small and medium-sized display screens in the prior art is solved, and a high-quality and excellent performance luminescent structure is achieved.
Patent Information
- Application Number
- CN202510584328.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-07
- Publication Date
- 2025-06-17
AI Technical Summary
In the small and micro-size display screens, the single-chip bonding process has high requirements for equipment and process control, and it is easy to cause excessive bonding and bonding, resulting in poor product quality and poor performance.
The method of directly preparing the color conversion structure on the luminescent chip wafer is adopted, and then the luminescent chip wafer is cut into a single luminescent chip die and bonded with the driver chip die. The overall process is relatively difficult to ensure product quality and performance.
Through one-time single chip bonding, the accumulation of alignment deviation is avoided, process difficulty is reduced, and the high quality and excellent performance of the luminescent structure are ensured.
Smart Images
Figure CN120166825A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, and particularly to a light-emitting structure and a method for preparing the same. Background Art
[0002] The emerging display technology of Micro-LED displays has been widely used due to advantages such as high brightness, low power consumption, long lifespan, and high contrast. According to the size of the screen, Micro-LED displays are generally divided into several categories, such as small micro-size, small and medium-size, medium and large-size, large-size, and extra-large-size. Among them, small micro-size displays are generally prepared by a single (chip) bonding process. The single-chip bonding process has high requirements for equipment and process control, and it is very easy to have a large cumulative bonding alignment deviation, so that the quality of the final product may not be good and the performance is poor. Summary of the Invention
[0003] The purpose of this application is to provide a light-emitting structure and a method for preparing the same, with relatively low process difficulty and good product quality.
[0004] To achieve the above purpose, this application provides the following technical solutions:
[0005] This application provides a method for preparing a light-emitting structure, and the preparation method includes:
[0006] Preparing a light-emitting chip wafer, the light-emitting chip wafer includes a substrate, an epitaxial layer above the substrate, and light-emitting chips above the epitaxial layer. The number of the light-emitting chips is multiple, and there is an isolation structure between the light-emitting chips. The bottom of the isolation structure contacts the substrate, and the epitaxial layer below adjacent light-emitting chips is disconnected;
[0007] Preparing a color conversion structure on the light-emitting chip wafer;
[0008] Cutting the light-emitting chip wafer into light-emitting chip grains;
[0009] Separately preparing driving chip grains, and bonding the light-emitting chip grains and the driving chip grains to obtain the required light-emitting structure.
[0010] In an embodiment, preparing a light-emitting chip wafer includes:
[0011] Providing a substrate with an epitaxial layer, or providing a substrate and then preparing an epitaxial layer on the substrate;
[0012] Preparing the isolation structure for the epitaxial layer, the bottom of the isolation structure contacts the substrate, and the epitaxial layer is divided into multiple light-emitting regions;
[0013] The light-emitting chips are fabricated on the epitaxial layer, and the number of the light-emitting chips is multiple. One light-emitting chip is formed on one light-emitting region.
[0014] In one embodiment, a color conversion structure is fabricated on the light-emitting chip wafer, including:
[0015] A temporary substrate is provided separately, and a temporary bonding adhesive is spin-coated on the temporary substrate. The temporary substrate is bonded to the light-emitting chip wafer.
[0016] The substrate is removed.
[0017] The epitaxial layer is thinned, and a black glue with a blank area is fabricated on the thinned epitaxial layer.
[0018] Red quantum dots and green quantum dots are filled in the blank area, and the red quantum dots and the green quantum dots constitute the color conversion structure.
[0019] In one embodiment, fabricating a black glue with a blank area on the thinned epitaxial layer includes:
[0020] The thinned epitaxial layer is coated with black glue, and a blank area is formed through a photolithography process.
[0021] The black glue is pre-cured with ultraviolet light under low-temperature conditions.
[0022] A temporary substrate is bonded to the surface of the black glue at high temperature, and the black glue is completely cured at the same time.
[0023] The temporary substrate is removed.
[0024] In one embodiment, the low-temperature condition is: 100°C - 160°C, and the high-temperature condition is: 160°C - 250°C.
[0025] In one embodiment, after filling red quantum dots and green quantum dots in the blank area, it further includes:
[0026] A transparent glass sheet is attached to the black glue, the red quantum dots, and the green quantum dots.
[0027] The temporary substrate is removed.
[0028] In one embodiment, after removing the temporary substrate, it further includes:
[0029] The light-emitting chip wafer is cleaned.
[0030] In one embodiment, fabricating a driving chip die separately includes:
[0031] Fabricating a driving chip wafer;
[0032] Deposit an adhesion metal layer on the top metal of the driving chip wafer;
[0033] Deposit solder on the electrodes of the driving chip wafer;
[0034] Cut the driving chip wafer to obtain driving chip dies.
[0035] In one embodiment, bonding the light-emitting chip die and the driving chip die to obtain a desired light-emitting structure, including:
[0036] Perform reflow on the driving chip die to bond the light-emitting chip die and the driving chip die to obtain the light-emitting structure.
[0037] This application also provides a light-emitting structure, which is prepared by the preparation method as described above.
[0038] Compared with the prior art, the technical solution of this application has the following beneficial effects:
[0039] For the light-emitting structure and its preparation method of this application, first directly prepare a color conversion structure on the light-emitting chip wafer, and finally slice the light-emitting chip wafer into individual light-emitting chip dies, and perform single-chip bonding on the light-emitting chip dies and the driving chip dies. There is only one single-chip bonding process throughout, and the alignment is not prone to cumulative deviation. The overall process difficulty is relatively low, which can ensure that the prepared light-emitting structure has good product quality and performance. Among them, preparing the color conversion structure on the light-emitting chip wafer means that the color conversion structure is directly prepared on the light-emitting chip wafer by a wafer-level process; correspondingly, each light-emitting chip has a color conversion structure, and the alignment is relatively easy to be accurate, and the process difficulty is relatively low, which also improves the product quality.
[0040] This application prepares an isolation structure on the epitaxial layer of the light-emitting chip wafer. The bottom of the isolation structure contacts the substrate, disconnecting the epitaxial layers under each light-emitting chip from each other, that is, dividing the epitaxial layer into multiple light-emitting regions, and each light-emitting chip corresponds to one light-emitting region. When the substrate is removed subsequently, the stress in each light-emitting region (epitaxial layer) is relatively small, and it is easy to be released completely, and it is not easy to be damaged, further improving the product quality.
[0041] When preparing the black glue of the color conversion structure in this application, instead of directly curing at high temperature, it is first pre-cured with ultraviolet light at low temperature, and then bonded to the temporary substrate. The high temperature during bonding is used to complete the curing of the black glue. Moreover, when bonding (and curing), the temporary substrate can also support the black glue and the light-emitting region (epitaxial layer), further reducing the risk of damage to the light-emitting region (epitaxial layer) and improving the product quality.
[0042] When the last light-emitting chip die and the driving chip die are singulated and bonded, solder is deposited on the driving chip die and reflowed on the driving chip die, which can avoid the color conversion structure (prepared on the light-emitting chip die) being affected by high temperature during reflow if the solder is deposited on the light-emitting chip die, further improving the product quality. BRIEF DESCRIPTION OF THE DRAWINGS
[0043] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative efforts.
[0044] Figure 1 It is a schematic flowchart of a method for preparing a light-emitting structure provided by the first embodiment of the present application;
[0045] Figures 2 - 9 respectively are Figure 1 Schematic structural diagrams of the light-emitting structures formed in each step of the shown preparation method. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application. It should be noted that the description order of the following embodiments does not limit the preferred order of the embodiments of the present application. And in the following embodiments, each embodiment is described with emphasis. For parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.
[0047] Please refer to Figure 1 As shown, the first embodiment of the present application provides a method for preparing a light-emitting structure, and the preparation method includes:
[0048] Preparing a light-emitting chip wafer, the light-emitting chip wafer includes a substrate, an epitaxial layer above the substrate, and a light-emitting chip above the epitaxial layer. The number of the light-emitting chips is multiple, and an isolation structure is provided between adjacent light-emitting chips. The bottom of the isolation structure contacts the substrate, disconnecting the epitaxial layer below adjacent light-emitting chips;
[0049] Preparing a color conversion structure on the light-emitting chip wafer;
[0050] Cutting the light-emitting chip wafer into light-emitting chip dies;
[0051] Prepare a driving chip die separately, bond the light-emitting chip die and the driving chip die to obtain the required light-emitting structure.
[0052] First, briefly explain that the light-emitting chip wafer refers to a wafer containing multiple light-emitting chips, the light-emitting chip die refers to a die containing a single light-emitting chip, the driving chip die refers to a die containing a single driving chip, and the driving chip wafer to be described later refers to a wafer containing multiple driving chips. Naming with the light-emitting chip wafer and the driving chip wafer is mainly to more intuitively reflect that the corresponding steps are in the wafer-level process; naming with the light-emitting chip die and the driving chip die is mainly to more intuitively reflect that the corresponding steps are in the single-chip process. In addition, after preparing the color conversion structure on the light-emitting chip wafer, the light-emitting chip wafer already has the color conversion structure, and in subsequent steps, the light-emitting chip wafer is still referred to mainly to simplify the description.
[0053] In the preparation method of the present application, first directly prepare the color conversion structure on the light-emitting chip wafer, and finally cut the light-emitting chip wafer into single light-emitting chip dice, and perform single-chip bonding on the light-emitting chip dice and the driving chip dice. There is only one single-chip bonding process in the whole process, and the alignment is not easy to have cumulative deviation, and the overall process difficulty is low, which can ensure that the prepared light-emitting structure product has good quality and performance. Among them, preparing the color conversion structure on the light-emitting chip wafer means that the color conversion structure is directly prepared on the light-emitting chip wafer by the wafer-level process; correspondingly, each light-emitting chip has a color conversion structure, and the alignment is relatively easy to be accurate, and the process difficulty is low, which also improves the product quality.
[0054] The following will be combined with a specific embodiment Figures 2 - 9 to elaborate in detail on the preparation method of the present application.
[0055] In one embodiment, preparing a light-emitting chip wafer includes:
[0056] Provide a substrate with an epitaxial layer, or provide a substrate and then prepare an epitaxial layer on the substrate;
[0057] Prepare the isolation structure on the epitaxial layer, and the bottom of the isolation structure contacts the substrate;
[0058] Prepare the light-emitting chips on the epitaxial layer, and the number of the light-emitting chips is multiple.
[0059] Among them, the substrate can be purchased with an epitaxial layer already on it, or the purchased substrate can have only a single substrate structure, and then an epitaxial layer is prepared on it separately during the preparation process of this application. The light-emitting chip of this application is prepared on the epitaxial layer (also called the buffer layer) on the substrate to improve the product quality. The material of the epitaxial layer can be GaN, and the substrate can be a sapphire substrate, a silicon substrate, or a silicon carbide substrate.
[0060] Before preparing the light-emitting chip in this application, an isolation structure is first prepared on the epitaxial layer. The isolation structure can be a shallow trench isolation structure (STI) or a local oxidation of silicon isolation structure (LOCOS), and the corresponding process methods are well-known to those skilled in the art. The bottom of the isolation structure contacts the substrate, dividing the epitaxial layer into multiple light-emitting regions, and the states of all light-emitting regions are completely disconnected. In this way, when preparing the light-emitting chip on the epitaxial layer later, although multiple light-emitting chips are prepared simultaneously, in fact, any light-emitting chip corresponds to a light-emitting region, that is, a light-emitting chip is formed on one light-emitting region. The specific process method used to prepare the light-emitting chip can be the same as that in the existing scheme, which will not be elaborated here. Through processes such as photolithography, etching, and coating, a microdisplay pixel array with a total of N horizontal structures, that is, multiple light-emitting chips, is finally obtained.
[0061] Please refer to Figure 2 As shown, for simplicity, Figure 2 only one light-emitting chip wafer and two of the light-emitting chips are schematically shown therein. The light-emitting chip wafer has a substrate 1, and the epitaxial layer 2 (light-emitting region 21) above the substrate 1 is disconnected and not connected between the two light-emitting chips. Figure 2 In the figure, it is shown as blank. Substantially, there are at least two parts of structures between the two light-emitting chips. One is the aforementioned isolation structure, and the other is a non-conductive dielectric material formed above the isolation structure in the subsequent steps (finally, this will be cut here to form individual light-emitting chip grains). Each light-emitting chip above the epitaxial layer 2 (light-emitting region 21) includes: an N-type layer 3, a multi-quantum well 4, a P-type layer 5, a current diffusion layer 6, an electrode 7 stacked in sequence at the middle position, a pad layer 8 at the periphery and electrodes 7 above and below the pad layer 8. The electrode 7 below the pad layer 8 contacts the light-emitting region 21, and a passivation layer 9 that wraps the aforementioned structures and only exposes the upper electrode 7. Among them, the N-type layer 3, the multi-quantum well 4, and the P-type layer 5 constitute the core light-emitting unit, and other structures are all used for electrical connection. At this time, each light-emitting region 21 also actually serves as a part of each light-emitting chip and participates in electrical connection. In this application, an isolation structure is prepared on the epitaxial layer 2, and the bottom of the isolation structure contacts the substrate, dividing the epitaxial layer 2 into multiple light-emitting regions 21. The states of all light-emitting regions 21 are completely disconnected to reduce the risk of the epitaxial layer 2 being damaged due to stress when removing the substrate 1 later.
[0062] After the preparation of the light-emitting chip wafer is completed, a color conversion structure can be directly prepared thereon. In one embodiment, preparing a color conversion structure on the light-emitting chip wafer includes:
[0063] Providing a temporary substrate separately, spin-coating a temporary bonding adhesive on the temporary substrate, and bonding the temporary substrate and the light-emitting chip wafer;
[0064] Removing the substrate;
[0065] Thinning the epitaxial layer, and preparing a black glue with blank areas on the thinned epitaxial layer;
[0066] Filling red quantum dots and green quantum dots in the blank areas, and the red quantum dots and the green quantum dots constitute the color conversion structure.
[0067] Please refer to Figure 3 As shown, the temporary substrate 10 is mainly used to temporarily support the light-emitting chip wafer to remove the substrate 1, and there is no substantial structure on it that needs to be aligned with the light-emitting chips on the light-emitting chip wafer. Therefore, when bonding, there is no need to consider the difficult problem of one-to-one alignment, and only overall alignment is required, and the process difficulty is very low. And the temporary bonding adhesive 11 includes an adhesion layer 111 and a release layer 112 for easy removal in the subsequent process.
[0068] For removing the substrate 1, for a sapphire substrate, it can be removed by laser lift-off, and for a silicon-based substrate, it can be removed by grinding or other methods. Just for removing the substrate 1 at this time, in the present application, the epitaxial layer 2 has been separated into multiple small light-emitting regions 21 through an isolation structure. Since the sizes of the light-emitting regions 21 are relatively small, the stress in each light-emitting region 21 is relatively small after the substrate 1 is removed and is easily released completely. Therefore, each light-emitting region 21 is not easily damaged, thus ensuring that each light-emitting chip has good quality. If the epitaxial layer 2 is not separated but remains as a whole epitaxial layer 2, due to the large size of the epitaxial layer 2, the stress in it is large after the substrate 1 is removed and is difficult to release completely quickly, which is likely to cause damage at a certain position, thus affecting the quality of the light-emitting chip.
[0069] After removing the substrate 1, the epitaxial layer 2 is thinned, and then the color conversion structure can be prepared. The epitaxial layer 2 can be thinned by dry etching, and it should be noted that the epitaxial layer 2 is not completely etched away.
[0070] Next, a black glue with blank areas is prepared on the thinned epitaxial layer. In one embodiment, preparing a black glue with blank areas on the thinned epitaxial layer includes:
[0071] Coating black glue on the thinned epitaxial layer, and forming blank areas through a lithography process;
[0072] Pre-cure the black glue with ultraviolet light under low-temperature conditions;
[0073] Bond a temporary substrate on the surface of the black glue at high temperature while completely curing the black glue;
[0074] Remove the temporary substrate.
[0075] Please refer to Figures 4 - 5 As shown, apply black glue 12 on the thinned epitaxial layer 2. The black glue 12 can be a photoresist. After the lithography process, a blank area 13 is formed, which is also well-known to those skilled in the art. However, after the lithography process, the black glue 12 needs to be cured (the black glue 12 is in a soft and wet fluid state before curing and in a hard solid state after curing) before subsequent steps can be carried out. Generally, at this time, the curing can be considered to directly cure the black glue 12 with high temperature to improve efficiency. However, in this application, first pre-cure the black glue 12 with ultraviolet light under low-temperature conditions, and then bond a temporary substrate 14 on the surface of the black glue 12 (such as Figure 5As shown. Since the bonding needs to be carried out at high temperature, the high temperature during the bonding of the temporary substrate 14 can also completely cure the black glue 12 at the same time; and during the bonding (and curing), the temporary substrate 14 can also support the black glue 12 and the light-emitting region 21 (epitaxial layer 2), further reducing the risk of damage to the light-emitting region 21 (epitaxial layer 2) and improving the product quality. Incidentally, the low temperature and high temperature here are relative to each other. The low temperature condition in this application can be: 100°C - 160°C, and the high temperature condition can be: 160°C - 250°C. In a specific embodiment, the low temperature is 100°C, 104°C, 110°C, 117°C, 120°C, 123°C, 130°C, 135°C, 140°C, 148°C, 150°C, 152°C or 160°C, and the high temperature is 160°C, 163°C, 170°C, 174°C, 180°C, 185°C, 190°C, 196°C, 200°C, 202°C, 210°C, 213°C, 220°C, 228°C, 230°C, 231°C, 240°C, 245 or 250°C. The temporary substrate 14 is mainly used to temporarily support the black glue 12 and the light-emitting region 21, and there is no any substantial structure on it that needs to be aligned with the light-emitting chips on the light-emitting chip wafer. Therefore, when bonding, there is no need to consider the difficult problem of one-to-one alignment, and only overall alignment is required, and the process difficulty is very low. After the black glue 12 is completely cured, the temporary substrate 14 can be removed. When bonding the temporary substrate 14, a temporary bonding adhesive 11 including an adhesion layer 111 and a release layer 112 can also be used as in the previous bonding of the temporary substrate 10, so that the temporary substrate 14 and the adhesion layer 111 can be easily removed by removing the release layer 112 at this time. In order to ensure that the temporary substrate 14 and the temporary bonding adhesive 11 are removed completely, cleaning can be carried out after removing the temporary substrate 14. The cleaning uses an organic solution, and NMP (N-methyl-2-pyrrolidone), DMSO (dimethyl sulfoxide), IPA (isopropyl alcohol) or acetone, etc. can be used. The state after removing the temporary substrate 14 (and the black glue 12 is completely cured) returns to Figure 4 the appearance shown.
[0076] After the formed black glue 12 (with a blank area 13) is completely cured, red quantum dots and green quantum dots can be filled in the blank area 13, and the red quantum dots and the green quantum dots constitute a color conversion structure. Please refer to Figure 6 as shown in Figure 6 only two light-emitting chips are schematically shown in which only red quantum dots 15 are filled and no green quantum dots are filled, and there are still some blank areas 13 remaining vacant. These can all be designed according to the actual different pixel light-emitting purpose requirements. Those skilled in the art know that different red quantum dots 15 or green quantum dots or left blank can be filled in the corresponding different blank areas 13 according to different actual requirements. The filling of red quantum dots and green quantum dots can adopt a photolithography process or an inkjet printing method.
[0077] After filling the blank area with red quantum dots and green quantum dots, that is, after preparing and forming the color conversion structure, in one embodiment, it further includes:
[0078] Bond a transparent glass sheet onto the black glue, the red quantum dots, and the green quantum dots;
[0079] Remove the temporary substrate.
[0080] Please refer to Figure 7 As shown, the transparent glass sheet 16 is bonded onto the black glue 12, the red quantum dots 15, and the green quantum dots, which can protect the black glue 12, the red quantum dots 15, and the green quantum dots and improve the product quality. Moreover, the transparent glass sheet 16 is mainly used to protect the black glue 12, the red quantum dots 15, and the green quantum dots as a whole, and there is no substantial structure on it that needs to be aligned with the light-emitting chips on the light-emitting chip wafer. Therefore, when bonding, there is no need to consider the difficult problem of one-to-one alignment, and only overall alignment is required, and the process difficulty is very low. When bonding, glue 17 can be used for bonding to ensure stable bonding and improve the product quality. In a specific embodiment, the glue 17 can be a thermosetting dehydrating or thermoplastic glue. Note that the thickness of the glue should be as thin as possible to avoid increased crosstalk between pixels caused by excessive thickness.
[0081] Please refer to Figure 8 As shown, after the transparent glass sheet 16 is stably bonded, the temporary substrate 10 can be removed. As described above, the temporary bonding glue 11 including the adhesion layer 111 and the release layer 112 is used when bonding the temporary substrate 10. At this time, the temporary substrate 10 can be easily debonded by removing the release layer 112, thereby removing the temporary substrate 10 and the adhesion layer 111. To ensure that the temporary substrate 10 and the temporary bonding glue 11 are removed completely, the light-emitting chip wafer can be cleaned after removing the temporary substrate 10. The cleaning uses an organic solution, and NMP (N-methyl-2-pyrrolidone), DMSO (dimethyl sulfoxide), IPA (isopropyl alcohol), or acetone, etc. can be used. The state after removing the temporary substrate 10 is as Figure 8 shown.
[0082] After the light-emitting chip wafer is prepared, the light-emitting chip wafer is cut, and by laser cutting and scribing, light-emitting chip dies can be formed, which is well-known to those skilled in the art.
[0083] After introducing the preparation of the light-emitting chip dies above, the preparation of the driving chip dies will be introduced next. In one embodiment, the driving chip dies are prepared separately, including:
[0084] Prepare a driving chip wafer;
[0085] Deposit an adhesion metal layer on the top metal of the driving chip wafer;
[0086] Deposit solder on the electrodes of the driving chip wafer;
[0087] Cut the driving chip wafer to obtain driving chip dies.
[0088] Among them, the specific method for preparing the driving chip wafer can be the same as that in the existing solution, which will not be elaborated herein. Please refer to Figure 9 As shown, the driving chip 18 in the prepared driving chip wafer can be a silicon-based CMOS chip or a glass-based TFT chip. During subsequent cutting, for the silicon-based driving chip wafer, it can be thinned first and then cut, while for the glass-based driving chip wafer, it can be directly cut. The material of the adhesion metal layer can be Ti, and the materials of the solder 19 can be In and Sn. Depositing the adhesion metal layer and the solder 19 on the driving chip wafer, that is, depositing the adhesion metal layer and the solder 19 on the driving chip die, is for subsequent bonding with the light-emitting chip die.
[0089] After obtaining the light-emitting chip die and the driving chip die, bonding can be carried out. In one embodiment, bonding the light-emitting chip die and the driving chip die to obtain the required light-emitting structure, including:
[0090] Perform reflow on the driving chip die, bond the light-emitting chip die and the driving chip die to obtain the required light-emitting structure.
[0091] Bonding the light-emitting chip die and the driving chip die requires high-temperature reflow of the solder. In this application, the solder 19 is deposited on the driving chip wafer (driving chip die), so at this time, reflow is performed on the driving chip die. In this way, it can be avoided that if the solder is deposited on the light-emitting chip wafer (light-emitting chip die), then high-temperature injection needs to be performed on the light-emitting chip die, and the color conversion structure (the color conversion structure is prepared on the light-emitting chip die) may be affected by the high temperature during reflow, thereby affecting the product quality. That is, in this application, the solder 19 is deposited on the driving chip wafer (driving chip die) for bonding and high-temperature reflow, which improves the product quality.
[0092] The light-emitting structure obtained in this application also belongs to the completion by using a single-chip bonding process and can be applied to small and micro-sized display screens.
[0093] Finally, it should be added that the sequence of each step in the preparation method of this application, unless clearly stated in this article, if not clearly stated, it means that it can be adjusted arbitrarily according to the actual situation.
[0094] The second embodiment of the present application provides a light-emitting structure, which is prepared by the preparation method described above. As described above, the light-emitting structure provided by the present application is applicable to small and micro-sized display screens.
[0095] Compared with the prior art, the technical solution of the present application has the following beneficial effects:
[0096] In the light-emitting structure and its preparation method of the present application, a color conversion structure is directly prepared on the light-emitting chip wafer first, and finally the light-emitting chip wafer is sliced into individual light-emitting chip grains. The light-emitting chip grains and the driving chip grains are bonded by single-chip bonding. There is only one single-chip bonding process in the whole process, and the alignment is not easy to have cumulative deviation. The overall process difficulty is relatively low, which can ensure that the prepared light-emitting structure product has good quality and performance. Among them, the color conversion structure is prepared on the light-emitting chip wafer, that is, the color conversion structure is directly prepared on the light-emitting chip wafer by a wafer-level process; correspondingly, each light-emitting chip has a color conversion structure, and the alignment is relatively easy to be accurate, and the process difficulty is relatively low, which also improves the product quality.
[0097] In the present application, an isolation structure is prepared on the epitaxial layer of the light-emitting chip wafer. The bottom of the isolation structure contacts the substrate, and the epitaxial layers under each light-emitting chip are disconnected from each other, that is, the epitaxial layer is divided into multiple light-emitting regions, and each light-emitting chip corresponds to one light-emitting region. When the substrate is removed subsequently, the stress in each light-emitting region (epitaxial layer) is relatively small and is easily released completely, so it is not easy to be damaged, further improving the product quality.
[0098] When preparing the black glue of the color conversion structure in the present application, it is not directly cured at high temperature, but is first pre-cured by ultraviolet light at low temperature, and then bonded to the temporary substrate. The black glue is cured by the high temperature during bonding. Moreover, the temporary substrate can also support the black glue and the light-emitting region (epitaxial layer) during bonding (and curing), further reducing the risk of damage to the light-emitting region (epitaxial layer) and improving the product quality.
[0099] Finally, when the light-emitting chip grains and the driving chip grains are bonded by single-chip bonding, the solder is deposited on the driving chip grains and the driving chip grains are reflowed. In this way, it can be avoided that if the solder is deposited on the light-emitting chip grains, the color conversion structure (the color conversion structure is prepared on the light-emitting chip grains) may be affected by high temperature during reflow, further improving the product quality.
[0100] As described above, this is only the specific implementation manner of the present application. However, the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims. In addition, specific examples are used in the specification to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application, and the content of this specification should not be construed as a limitation to the present application.
Claims
1. A method for preparing a light-emitting structure, characterized in that: The preparation method comprises: Prepare a light-emitting chip wafer, wherein the light-emitting chip wafer comprises a substrate, an epitaxial layer above the substrate, and a light-emitting chip above the epitaxial layer, wherein the number of the light-emitting chips is multiple, and an isolation structure is provided between each light-emitting chip, wherein the bottom of the isolation structure contacts the substrate, and the epitaxial layer below adjacent light-emitting chips is disconnected; preparing a color conversion structure on the light-emitting chip wafer; Cutting the light-emitting chip wafer into light-emitting chip dies; A driving chip crystal grain is prepared separately, and the light-emitting chip crystal grain and the driving chip crystal grain are bonded to obtain a desired light-emitting structure.
2. The preparation method according to claim 1, characterized in that: Preparation of light-emitting chip wafers, including: Providing a substrate with an epitaxial layer, or providing a substrate and then preparing an epitaxial layer on the substrate; The isolation structure is prepared for the epitaxial layer, wherein the bottom of the isolation structure contacts the substrate, and the epitaxial layer is divided into a plurality of light-emitting regions; The light-emitting chip is prepared on the epitaxial layer. There are multiple light-emitting chips, and one light-emitting chip is formed on one light-emitting area.
3. The preparation method according to claim 1, characterized in that: Preparing a color conversion structure on the light-emitting chip wafer includes: A temporary substrate is separately provided, and a temporary bonding adhesive is spin-coated on the temporary substrate to bond the temporary substrate to the light-emitting chip wafer; removing the substrate; Thinning the epitaxial layer, and preparing black glue with blank areas on the thinned epitaxial layer; Red quantum dots and green quantum dots are filled in the blank area, and the red quantum dots and the green quantum dots constitute a color conversion structure.
4. The preparation method according to claim 3, characterized in that: The method comprises preparing a black glue having a blank area on the thinned epitaxial layer, comprising: Apply black glue on the thinned epitaxial layer and form a blank area through photolithography; Pre-curing the black glue by using ultraviolet light under low temperature conditions; bonding a temporary substrate to the surface of the black glue at a high temperature and completely curing the black glue; The temporary substrate is removed.
5. The preparation method according to claim 4, characterized in that: The low temperature condition is 100°C-160°C, and the high temperature condition is 160°C-250°C.
6. The preparation method according to claim 3, characterized in that: After the red quantum dots and the green quantum dots are filled in the blank area, the method further comprises: Laminating a transparent glass sheet on the black plastic, the red quantum dots, and the green quantum dots; The temporary substrate is removed.
7. The preparation method according to claim 6, characterized in that: After removing the temporary substrate, the method further comprises: The light-emitting chip wafer is cleaned.
8. The preparation method according to claim 1, characterized in that: A driver chip crystal is prepared separately, including: Preparing driver chip wafers; Depositing an adhesion metal layer on the top metal layer of the driver chip wafer; Depositing solder on electrodes of the driver chip wafer; The driver chip wafer is cut to obtain driver chip grains.
9. The preparation method according to claim 1, characterized in that: The light emitting chip crystal grain and the driving chip crystal grain are bonded to obtain the desired light emitting structure, including: The driving chip grain is reflowed, and the light-emitting chip grain and the driving chip grain are bonded to obtain the light-emitting structure.
10. A light emitting structure, characterized in that: The light-emitting structure is prepared by the preparation method according to any one of claims 1 to 9.