Glue filling method and preparation method of micro light-emitting diode

Abstract

The invention provides a glue filling method and a preparation method of a miniature light emitting diode, and belongs to the technical field of semiconductor preparation. The glue filling method comprises the following steps: providing a glue filling device, wherein the glue filling device is provided with an accommodating cavity; pouring the glue solution into the accommodating cavity; putting a display sample into the accommodating cavity, so that the display sample is immersed in the glue solution; the display sample is defoamed through the glue filling device, so that air in the display sample overflows from the side edge gap of the display sample, and the glue solution is immersed into the display sample from the side edge gap of the display sample. According to the invention, the yield and efficiency of glue filling can be improved.

Description

Technical Field

[0001] The present disclosure belongs to the field of semiconductor manufacturing technology, and in particular relates to a glue filling method and a method for preparing a micro light emitting diode. Background Art

[0002] Micro LED (Micro Light Emitting Diode) is a new type of semiconductor display device.

[0003] In related technologies, the production of micro-LEDs requires thermal bonding between the wafer die and the circuit substrate. During the thermal bonding process, the wafer die and the circuit substrate pads are first positioned and docked. Heat is then applied to melt the metal electrode solder between the die and pad, which solidifies after cooling to form a display sample. Glue is then applied between the wafer and the circuit substrate. Finally, the wafer's epitaxial substrate is removed.

[0004] However, during the glue filling process, the glue can only slowly penetrate into the interior of the display sample, that is, the gap between each grain, through the gap between the wafer substrate and the circuit board under capillary action. Therefore, the whole process is very slow, and it is easy to have problems such as incomplete glue filling and holes, resulting in a decrease in the yield of glue filling. Summary of the Invention

[0005] The embodiments of the present disclosure provide a method for filling glue and a method for preparing a micro-light-emitting diode, which can improve the yield and efficiency of filling glue. The technical solution is as follows:

[0006] In one aspect, an embodiment of the present disclosure provides a method for filling glue, comprising:

[0007] A glue filling device is provided, wherein the glue filling device has a receiving cavity;

[0008] pouring glue into the accommodating cavity;

[0009] placing a display sample into the accommodating cavity so that the display sample is immersed in the glue;

[0010] The display sample is defoamed by the glue filling device, so that the air inside the display sample overflows from the side edge gaps of the display sample, and the glue penetrates into the interior of the display sample from the side edge gaps of the display sample.

[0011] In one implementation of the present disclosure, debubbling the display sample using the glue filling device includes:

[0012] reducing the air pressure in the accommodating chamber to below a threshold pressure, where the threshold pressure is lower than standard atmospheric pressure;

[0013] After no bubbles overflow from the side edge gaps of the display sample, the display sample is allowed to stand.

[0014] In one implementation of the present disclosure, the threshold pressure is 1*10 -5 pa.

[0015] In one implementation of the present disclosure, the display sample is left to stand for 8 to 12 minutes.

[0016] In one implementation of the present disclosure, before pouring the glue into the accommodating cavity, the process includes:

[0017] Prepare the glue solution;

[0018] The glue solution is placed in a vacuum degassing machine for degassing.

[0019] In one implementation of the present disclosure, after the display sample is debubbled by the glue filling device, the following steps are included:

[0020] Taking the display sample out of the accommodating cavity;

[0021] Clean the glue remaining on the outer surface of the display sample.

[0022] In one implementation of the present disclosure, after cleaning the glue remaining outside the display sample, the method includes:

[0023] heating the display sample to solidify the glue inside the display sample;

[0024] The cured adhesive residue on the outer surface of the display sample is removed.

[0025] In another aspect, an embodiment of the present disclosure provides a method for manufacturing a micro light emitting diode, comprising:

[0026] preparing wafers;

[0027] providing a circuit substrate;

[0028] thermally bonding the wafer to the circuit substrate to obtain a display sample;

[0029] Filling the display sample with glue using the glue filling method described in the previous aspect;

[0030] The substrate of the wafer is peeled off.

[0031] In one implementation of the present disclosure, thermally bonding the wafer to the circuit substrate to obtain a display sample includes:

[0032] Positioning and docking the metal electrodes of the wafer and the pads of the circuit substrate;

[0033] heating and melting the metal electrode solder between the wafer and the circuit substrate;

[0034] The metal electrode solder between the wafer and the circuit substrate is cooled and solidified.

[0035] In one implementation of the present disclosure, positioning and docking the metal electrodes of the wafer and the pads of the circuit substrate includes:

[0036] A gap is left between the substrate of the wafer and the circuit board, and an opening of the gap is located at the side edge of the wafer to form a side edge gap.

[0037] The beneficial effects of the technical solutions provided by the embodiments of the present disclosure include at least:

[0038] The glue filling method provided by the embodiment of the present disclosure can fill the display sample with glue so that the glue is injected into the internal space of the display sample. During the glue filling process, first, the glue is poured into the receiving cavity of the glue filling device to prepare for the subsequent glue filling step. Then, the display sample is placed in the receiving cavity, and it is ensured that the display sample is immersed in the glue. Finally, the display sample is debubbled by the glue filling device. During the debubbling process, the air inside the display sample overflows from the side edge gaps of the display sample. Since the air inside the display sample overflows, the glue can quickly penetrate into the interior of the display sample through the side edge gaps of the display sample.

[0039] That is to say, the glue filling method provided in the embodiment of the present disclosure actively discharges the air inside the display sample, so that the glue can quickly and fully penetrate into the interior of the display sample through the side edge gaps of the display sample, thereby improving the efficiency and yield of the glue filling.

[0040] In addition, during the glue filling process, there is no need to open additional glue filling holes or similar structures on the display sample, which is conducive to improving the efficiency of the glue filling operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the description of the embodiments. 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 any creative work.

[0042] Figure 1 is a flow chart of a glue filling method provided by an embodiment of the present disclosure;

[0043] Figure 2 is a flow chart of another glue filling method provided by an embodiment of the present disclosure;

[0044] Figure 3 is a cross-sectional view of a glue filling device provided in an embodiment of the present disclosure;

[0045] Figure 4 This is a flow chart of a method for preparing a micro light-emitting diode provided in an embodiment of the present disclosure.

[0046] The symbols in the figure mean the following:

[0047] 10. Glue filling device;

[0048] 110, accommodating cavity; 120, air extraction port; 130, adhesive;

[0049] 20. Display samples;

[0050] 210 , wafer; 211 , substrate; 212 , crystal grain; 220 , circuit board; 230 , side edge gap.

[0051] The above drawings illustrate specific embodiments of the present disclosure, which will be described in more detail below. These drawings and textual descriptions are not intended to limit the scope of the present disclosure in any way, but rather to illustrate the concepts of the present disclosure to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0052] 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.

[0053] In order to better understand the glue filling method and the method for preparing a micro light emitting diode provided by the embodiments of the present disclosure, the micro light emitting diode and the glue filling method in the related art are first introduced below.

[0054] Micro LED displays have attracted significant attention due to their unique properties, including high brightness, long lifespan, and high resolution. These displays utilize ultra-small vertical LED chips (3-20 μm in size) thermally bonded to specific integrated circuits. These devices can achieve resolutions exceeding 2.5K and brightness exceeding hundreds of thousands or even millions of nits within a display area less than 1 inch. These displays can meet the specific brightness and resolution requirements of applications such as VR / AR, projection, and automotive lighting.

[0055] When manufacturing micro-LEDs, the wafer die and the circuit substrate must be thermally bonded, a process commonly known in the industry as die-to-wafer. This thermal bonding method allows the circuit substrate and wafer to be made of the same substrate type, such as sapphire or silicon. During the thermal bonding process, the wafer die and the circuit substrate pad are first aligned and docked. Heat is then applied to melt the metal electrode solder between the die and pad, which solidifies upon cooling. Glue is then applied between the wafer and the circuit substrate. Finally, the epitaxial substrate is removed from the wafer.

[0056] However, during the glue filling process, the glue can only slowly penetrate into the interior of the display sample, that is, the gap between each grain, through the gap between the wafer substrate and the circuit board under capillary action. Therefore, the whole process is very slow, and it is easy to have problems such as incomplete glue filling and holes, resulting in a decrease in the yield of glue filling.

[0057] In order to solve the above technical problems, the present disclosure provides a method for filling glue. Figure 1 For a flow chart of the glue filling method, see Figure 1 In this embodiment, the glue filling method includes:

[0058] Step 101 : Provide a glue filling device 10 , wherein the glue filling device 10 has a receiving cavity 110 .

[0059] Step 102 : Pour the glue 130 into the accommodating cavity 110 .

[0060] Step 103 : placing the display sample 20 into the accommodating cavity 110 , such that the display sample 20 is immersed in the glue 130 .

[0061] Step 104 : Degas the display sample 20 by using the glue filling device 10 , so that the air inside the display sample 20 overflows from the side edge gap 230 of the display sample 20 , and the glue 130 penetrates into the interior of the display sample 20 from the side edge gap 230 of the display sample 20 .

[0062] It is worth noting that the side edge gap 230 of the display sample 20 has one end opening at the side edge of the display sample 20 and the other end opening communicating with the internal gap of the display sample 20. The internal gap of the display sample 20 is located between the substrate 211 of the wafer 210 and the circuit board 220, and is located between the individual dies 212 of the wafer 210.

[0063] Before the glue is filled, there is air in the internal space of the display sample 20 . The glue filling device 10 can make the air inside the display sample 20 overflow from the side edge gap 230 of the display sample 20 .

[0064] By means of the glue filling method provided by the embodiment of the present disclosure, the display sample 20 can be glue filled so that the glue 130 is injected into the internal space of the display sample 20. During the glue filling process, first, the glue 130 is poured into the receiving cavity 110 of the glue filling device 10, thereby preparing for the subsequent glue filling step. Then, the display sample 20 is placed into the receiving cavity 110, and it is ensured that the display sample 20 is immersed in the glue 130. Finally, the display sample 20 is debubbled by the glue filling device 10. During the debubbling process, the air inside the display sample 20 overflows from the side edge gap 230 of the display sample 20. Since the air inside the display sample 20 overflows, the glue 130 can quickly penetrate into the interior of the display sample 20 through the side edge gap 230 of the display sample 20.

[0065] That is to say, the filling method provided in the embodiment of the present disclosure actively discharges the air inside the display sample 20 so that the glue 130 can quickly and fully penetrate into the interior of the display sample 20 through the side edge gap 230 of the display sample 20, thereby improving the efficiency and yield of the filling.

[0066] In addition, during the glue filling process, there is no need to open additional glue filling holes or similar structures on the display sample 20, which is beneficial to improving the efficiency of the glue filling operation.

[0067] Figure 2 A flowchart of another method for filling glue provided in the embodiment of the present disclosure is provided. Figure 2 In this embodiment, the glue filling method includes:

[0068] Step 201 : Provide a glue filling device 10 , wherein the glue filling device 10 has a receiving cavity 110 .

[0069] Figure 3 is a cross-sectional view of the glue filling device 10, combined with Figure 3 In this embodiment, the top of the accommodating chamber 110 is provided with an air extraction port 120 , which is connected to an external vacuum pump. The air pressure in the accommodating chamber 110 can be reduced by the vacuum pump.

[0070] The size of the accommodating cavity 110 can be adjusted according to actual needs. If more display samples 20 need to be accommodated, the size of the accommodating cavity 110 is increased. If fewer display samples 20 need to be accommodated, the size of the accommodating cavity 110 is reduced.

[0071] Step 202: Prepare glue solution 130 and place the glue solution 130 into a vacuum degassing machine for degassing.

[0072] In step 202, a beaker is provided, and a glue solution 130 is prepared in a fixed ratio in the beaker and fully stirred and mixed using a stirrer or manually. Afterwards, the glue solution 130 is placed in a vacuum degassing machine for degassing to eliminate bubbles generated during the preparation process.

[0073] Exemplarily, the glue is a silicon-based or epoxy resin-based electronic potting glue.

[0074] In addition, the capacity of the glue 130 can also be adjusted according to actual needs. If more display samples 20 need to be soaked, the capacity of the glue 130 is increased. If fewer display samples 20 need to be soaked, the capacity of the glue 130 is reduced.

[0075] Step 203 : Pour the glue 130 into the accommodating cavity 110 .

[0076] In step 203 , during the process of pouring the glue 130 , the pouring speed of the glue 130 should be appropriately slowed down in order to avoid the generation of bubbles.

[0077] Step 204 : Degassing the display sample 20 by using the glue filling device 10 .

[0078] In the above implementation, the display sample 20 is debubbled by the glue filling device 10 , and the air inside the display sample 20 overflows from the side edge gap 230 of the display sample 20 , and the glue 130 penetrates into the interior of the display sample 20 from the side edge gap 230 of the display sample 20 .

[0079] In this embodiment, step 204 includes:

[0080] Step 2041: Reduce the air pressure in the accommodating chamber 110 to below a threshold pressure, where the threshold pressure is lower than standard atmospheric pressure.

[0081] In step 2041, the vacuum pump of the adhesive filling device 10 is activated to reduce the pressure within the receiving chamber 110 to below a threshold pressure. Because the threshold pressure is lower than standard atmospheric pressure, the air (at standard atmospheric pressure) within the display sample 20 will escape through the side edge gaps 230 of the display sample 20. Simultaneously, the adhesive 130 can penetrate into the interior of the display sample 20 through the side edge gaps 230 of the display sample 20.

[0082] For example, the threshold pressure is 1*10 -5 pa.

[0083] Setting the threshold pressure to the above value can ensure that the air inside the display sample 20 overflows from the side edge gap 230 of the display sample 20 at a faster speed.

[0084] Step 2042: After no bubbles overflow from the side edge gap 230 of the display sample 20, the display sample 20 is allowed to stand.

[0085] In step 2042, the side edge gaps 230 of the display sample 20 are inspected for bubbles. If no bubbles are present, the air inside the display sample 20 has been substantially expelled. The display sample 20 is then allowed to stand for a period of time until the adhesive 130 in the accommodating cavity 110 has fully penetrated the interior of the display sample 20 through the side edge gaps 230 of the display sample 20.

[0086] Exemplarily, the display sample 20 is left to stand for 8 to 12 minutes.

[0087] By setting the standing time of the display sample 20 to the above value, it is possible to ensure that the glue 130 in the accommodating cavity 110 is fully immersed in the interior of the display sample 20 .

[0088] Step 205 : Take the display sample 20 out of the accommodating cavity 110 and clean the residual glue 130 on the outer surface of the display sample 20 .

[0089] In step 205, since the display sample 20 is taken out from the accommodating cavity 110, some excess glue 130 is inevitably brought out. After the display sample 20 is taken out, the residual glue 130 on the outer surface of the display sample 20 is cleaned to effectively prepare for the subsequent steps.

[0090] Exemplarily, the outer surface of the chip sample is wiped with a disposable cotton swab to clean the glue 130 remaining on the outer surface of the display sample 20 .

[0091] It is worth noting that, when erasing the glue 130 , special attention should be paid to completely erasing the glue 130 remaining on the wiring pads of the circuit substrate 220 .

[0092] Step 206 : heating the display sample 20 to solidify the glue 130 inside the display sample 20 .

[0093] Exemplarily, the display sample 20 is placed on a hot plate to perform high-temperature curing on the glue 130 inside the display sample 20 .

[0094] For example, during the heat curing process, curing is performed at 100° C. for 1 hour.

[0095] It is worth noting that, in order to prevent the glue 130 inside the display sample 20 from overflowing, step 205 should be executed quickly, and after step 205 is completed, step 206 should be executed immediately.

[0096] Step 207 : removing the cured adhesive residue on the outer surface of the display sample 20 .

[0097] For example, an ICP (Inductively Coupled Plasma) etching device or an oxygen plasma (oxygen plasma) etching machine is used to remove the residual glue on the display sample 20 .

[0098] Figure 4 A flowchart of a method for preparing a micro light emitting diode according to an embodiment of the present disclosure is provided. Figure 4 In this embodiment, the preparation method includes:

[0099] Step 401: Prepare wafer 210.

[0100] In this embodiment, the wafer 210 includes a substrate 211 and a die 212 located on the substrate 211 . The portion of the die 212 facing away from the substrate 211 has a metal electrode 213 .

[0101] Step 402 : Provide a circuit substrate 220 .

[0102] In this embodiment, one side of the circuit substrate 220 has a pad for thermally bonding with the metal electrode 213 of the die 212 .

[0103] Step 403 : Thermally bond the wafer 210 and the circuit substrate 220 to obtain a display sample 20 .

[0104] In step 403, the following steps are included:

[0105] First, the metal electrodes 213 of the wafer 210 and the pads of the circuit substrate 220 are positioned and connected.

[0106] During the positioning and docking process, a gap is left between the substrate 211 of the wafer 210 and the circuit board 220 , and the opening of the gap is located at the side edge of the wafer 210 to form a side edge gap 230 .

[0107] In this way, a transmission channel can be provided for the air inside the display sample 20 and the glue 130 in the accommodating cavity 110, so that the air can flow out of the gap between the substrate 211 and the circuit substrate 220 through the side edge gap 230, and the glue 130 can flow into the gap between the substrate 211 and the circuit substrate 220 through the side edge gap 230.

[0108] It is worth noting that leaving a gap between the substrate 211 of the wafer 210 and the circuit board 220 does not increase the number of manufacturing steps or the workload. Compared to the related art of opening a glue injection hole on the circuit board 220, it effectively reduces the number of manufacturing steps and helps improve manufacturing efficiency.

[0109] Then, the metal electrode solder between the wafer 210 and the circuit substrate 220 is heated and melted.

[0110] Illustratively, the display sample 20 is placed on a hot plate to melt the metal electrode solder between the wafer 210 and the circuit substrate 220 .

[0111] Finally, the metal electrode solder between the wafer 210 and the circuit substrate 220 is cooled and solidified.

[0112] In some examples, the die 212 has a metal electrode solder of one of Au and Sn, and the pad has a metal electrode solder of the other of Au and Sn, and a stable AuSn alloy can be formed after bonding.

[0113] In other examples, the die 212 has one metal electrode solder material of Au and In, and the pad has another metal electrode solder material of Au and In, which can form a stable AuIn alloy after bonding.

[0114] Step 404: Pass Figure 1 The filling method shown is used to fill the display sample 20 with glue.

[0115] By means of the glue filling method provided by the embodiment of the present disclosure, the display sample 20 can be glue filled so that the glue 130 is injected into the internal space of the display sample 20. During the glue filling process, first, the glue 130 is poured into the receiving cavity 110 of the glue filling device 10, thereby preparing for the subsequent glue filling step. Then, the display sample 20 is placed into the receiving cavity 110, and it is ensured that the display sample 20 is immersed in the glue 130. Finally, the display sample 20 is debubbled by the glue filling device 10. During the debubbling process, the air inside the display sample 20 overflows from the side edge gap 230 of the display sample 20. Since the air inside the display sample 20 overflows, the glue 130 can quickly penetrate into the interior of the display sample 20 through the side edge gap 230 of the display sample 20.

[0116] That is to say, the filling method provided in the embodiment of the present disclosure actively discharges the air inside the display sample 20 so that the glue 130 can quickly and fully penetrate into the interior of the display sample 20 through the side edge gap 230 of the display sample 20, thereby improving the efficiency and yield of the filling.

[0117] In addition, during the glue filling process, there is no need to open additional glue filling holes or similar structures on the display sample 20, which is beneficial to improving the efficiency of the glue filling operation.

[0118] Step 405 : Peeling off the substrate 211 of the wafer 210 .

[0119] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning understood by persons of ordinary skill in the field to which the present disclosure belongs. The words “first”, “second”, “third” and similar terms 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 “a” or “an” do not indicate a quantity limitation, but rather indicate the presence of at least one. Words such as “include” or “comprise” mean that the elements or objects appearing before “include” or “comprises” include the elements or objects listed after “include” or “comprises” and their equivalents, and do not exclude other elements or objects. Words such as “connect” or “connected” are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. “Up”, “down”, “left”, “right” 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.

[0120] The above description is merely an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the scope of protection of the present disclosure.

Claims

1. A glue filling method, characterized in that: include: A glue filling device (10) is provided, wherein the glue filling device (10) has a receiving cavity (110); pouring glue (130) into the accommodating cavity (110); placing a display sample (20) into the accommodating cavity (110) such that the display sample (20) is immersed in the glue (130); The display sample (20) is defoamed by the glue filling device (10), so that the air inside the display sample (20) overflows from the side edge gap (230) of the display sample (20), and the glue (130) penetrates into the interior of the display sample (20) from the side edge gap (230) of the display sample (20).

2. The glue filling method according to claim 1, characterized in that: Debubbling the display sample (20) by using the glue filling device (10) includes: reducing the air pressure in the accommodating cavity (110) to below a threshold pressure, the threshold pressure being lower than standard atmospheric pressure; After no bubbles overflow from the side edge gap (230) of the display sample (20), the display sample (20) is left to stand.

3. The glue filling method according to claim 2, characterized in that: The threshold pressure is 1*10 -5 pa.

4. The glue filling method according to claim 2, characterized in that: The display sample (20) is allowed to stand for 8 to 12 minutes.

5. The glue filling method according to claim 2, characterized in that: Before pouring the glue (130) into the accommodating cavity (110), the process includes: Prepare the glue solution (130); The glue solution (130) is placed in a vacuum degassing machine for degassing.

6. The glue filling method according to claim 1, characterized in that: After the display sample (20) is defoamed by the glue filling device (10), the method includes: Taking the display sample (20) out of the accommodating cavity (110); Clean the glue (130) remaining on the outer surface of the display sample (20).

7. The glue filling method according to claim 6, characterized in that: After cleaning the glue (130) remaining outside the display sample (20), the method includes: heating the display sample (20) so that the glue (130) inside the display sample (20) solidifies; The cured residual glue on the outer surface of the display sample (20) is removed.

8. A method for preparing a micro light emitting diode, characterized in that: include: preparing a wafer (210); Providing a circuit substrate (220); Thermally bonding the wafer (210) and the circuit substrate (220) to obtain a display sample (20); Filling the display sample (20) with glue using the glue filling method according to any one of claims 1 to 7; The substrate (211) of the wafer (210) is peeled off.

9. The preparation method according to claim 8, characterized in that Thermally bonding the wafer (210) and the circuit substrate (220) to obtain a display sample (20) comprises: Positioning and docking the metal electrode (213) of the wafer (210) and the pad of the circuit substrate (220); heating and melting the metal electrode solder between the wafer (210) and the circuit substrate (220); The metal electrode solder between the wafer (210) and the circuit substrate (220) is cooled and solidified.

10. The preparation method according to claim 8, characterized in that Positioning and docking the metal electrode (213) of the wafer (210) and the pad of the circuit substrate (220), comprising: A gap is left between the substrate (211) of the wafer (210) and the circuit board (220), and an opening of the gap is located at a side edge of the wafer (210) to form a side edge gap (230).

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