A detection method for Micro LEDs

Abstract

The present invention discloses a detection method for Micro LEDs, comprising the following steps: processing an Si-COMS driving substrate to obtain a transient driving substrate; processing a gallium nitride epitaxial wafer to obtain a common cathode architecture Micro LED array substrate; realizing the bonding of the transient driving substrate and the common cathode architecture Micro LED array substrate; applying power to the transient driving substrate to perform visual inspection based on automatic optical inspection; after the test is completed, separating the transient driving substrate and the common cathode architecture Micro LED array substrate. By connecting the anode contact points of the Si-COMS driving substrate with a metal material to form a common anode structure, and then bonding it with the original common cathode architecture to the LED array, and evenly applying power to the pixel array of the Si-COMS driving substrate to ensure that each Micro LED on the LED array receives uniform current, correct LED emission data can be obtained.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and more particularly, to a method for detecting Micro LEDs. Background Art

[0002] Micro LED display technology refers to a display technology in which self-luminous LED pixels in the micron range (less than 50 microns) are assembled onto a driving panel to form a high-density LED array. When used for display, the number of chips in a Micro LED reaches millions or even tens of millions. During the production process, it is necessary to promptly detect and remove or repair defective pixels in the display chips. For example, for the display screen of a 4K TV, 4K * 2K * 3 = 24M Micro LED chips are required. The conventional detection and sorting speed is on the order of 10K / hour, and the detection and sorting time for Micro LEDs on an ordinary 4-inch wafer will also reach more than 1000 hours. Therefore, it is an urgent problem to quickly and accurately detect Micro LED display chips.

[0003] Currently, the commonly used LED display chip detection technologies include photoluminescence testing (PL) and electroluminescence testing (EL). The former can test LED chips without contact and damage, but the detection effect is slightly inferior compared to EL testing and cannot truly detect all defects, which may reduce the subsequent production yield. On the contrary, EL testing is performed by energizing the LED chips and can detect more defects, but it may cause chip damage due to contact. For Micro LEDs, due to their extremely small chip size, it is difficult to apply traditional testing equipment, and the difficulty of EL detection is quite high, while PL testing may miss some defects, resulting in poor detection efficiency.

[0004] Regarding the problems in the related art, no effective solution has been proposed yet. Summary of the Invention

[0005] Regarding the problems in the related art, the present invention proposes a method for detecting Micro LEDs, which uses the structure of a carrier substrate and an integration layer to introduce current and test LED components. According to the test results, the yield of known good wafers can be simulated, and Micro LEDs with normal display functions can be displayed, thereby improving the yield of massive transfer of Micro LEDs and overcoming the above-mentioned technical problems existing in the related art.

[0006] To this end, the specific technical solution adopted by the present invention is as follows:

[0007] A method for detecting Micro LEDs, the detection method comprising the following steps:

[0008] S1. Process the pre-prepared Si-COMS driving substrate to obtain a transient driving substrate;

[0009] S2. Process the pre-prepared gallium nitride epitaxial wafer to obtain a common cathode architecture Micro LED array substrate;

[0010] S3. Move the wafer stage to achieve the bonding of the transient driving substrate and the common cathode architecture Micro LED array substrate;

[0011] S4. Apply power to the transient driving substrate and perform visual inspection based on automatic optical inspection;

[0012] S5. After the test is completed, separate the transient driving substrate and the common cathode architecture Micro LED array substrate.

[0013] Further, the process of processing the pre-prepared Si-COMS driving substrate to obtain a transient driving substrate includes the following steps:

[0014] S11. Prepare the Si-COMS driving substrate and perform an insulating layer covering treatment;

[0015] S12. Continuously perform exposure / development and etching treatments based on the material of the insulating layer, and remove the material on the top via metal;

[0016] S13. Cover a photoresist on the top of the insulating layer after the S12 treatment;

[0017] S14. Perform exposure / development treatment again to separate the cathode contact points and anode contact points on the transient driving substrate;

[0018] S15. Deposit a conductive metal material on the top of the transient driving substrate after the re-exposure / development treatment;

[0019] S16. Perform a photoresist removal treatment to separate the cathode contact points and anode contact points on the transient driving substrate;

[0020] S17. Define the position for the second deposition of the conductive metal material and perform the second deposition of the conductive metal material;

[0021] S18. Perform a photoresist removal treatment again to obtain the transient driving substrate.

[0022] Further, the material of the insulating layer is SiOx inorganic material or organic photoresist material.

[0023] Further, the step of defining the position for the second deposition of the conductive metal material and performing the second deposition of the conductive metal material includes the following steps:

[0024] Perform photoresist coating and exposure / development processes on the transient driving substrate after removing the photoresist, and define the positions for the second deposition of the conductive metal material;

[0025] Deposit the second conductive metal material at the positions for the second deposition of the conductive metal material.

[0026] Furthermore, processing the pre-prepared gallium nitride epitaxial wafer to obtain a common cathode architecture MicroLED array substrate includes the following steps:

[0027] S21. Prepare a gallium nitride epitaxial wafer, and define the LED pattern through an exposure / development / etching process;

[0028] S22. Deposit indium tin oxide, and define the anode contact points through an exposure / development / etching process;

[0029] S23. Deposit a SiOx insulating layer to repair and protect the sidewalls of the LEDs;

[0030] S24. Use an etching process method to perform an opening process on the top of the SiOx insulating layer to define the anode / cathode contact points;

[0031] S25. Perform a photoresist coating process, and define the patterns of the conductive metal material and the anode contact points through exposure / development;

[0032] S26. Deposit the conductive metal material based on the patterns of the conductive metal material and the anode contact points;

[0033] S27. Perform a photoresist removal process to obtain a common cathode architecture Micro LED array substrate.

[0034] Furthermore, the deposition of the SiOx insulating layer is achieved by using atomic vapor deposition technology and chemical vapor deposition technology.

[0035] Furthermore, the process of using an etching process method to perform an opening process on the top of the SiOx insulating layer includes the following steps:

[0036] Etch the SiOx insulating layer to achieve the opening process on the top of the SiOx insulating layer;

[0037] Clean the etched SiOx insulating layer.

[0038] Furthermore, the process of moving the wafer stage to achieve the bonding of the transient driving substrate and the common cathode architecture Micro LED array substrate includes the following steps:

[0039] Fix one end of the wafer stage and move the other end of the wafer stage to realize the fitting of the transient driving substrate and the common cathode structure Micro LED array substrate.

[0040] Furthermore, when the transient driving substrate is powered on, the vision inspection based on automatic optical inspection includes the following steps:

[0041] S41. After the metal materials of the transient driving substrate and the common cathode structure Micro LED array substrate are in contact, power on the transient driving substrate;

[0042] S42. The common cathode structure Micro LED array substrate emits light to realize the vision inspection based on automatic optical inspection.

[0043] Furthermore, after the test is completed, separating the transient driving substrate and the common cathode structure Micro LED array substrate further includes the following steps: After the separation is completed, prepare the next common cathode structure Micro LED array substrate and perform a power-on test on it.

[0044] The beneficial effects of the present invention are as follows:

[0045] 1) By processing the Si-COMS driving substrate into a transient driving substrate for LED array quality screening, connecting the anode contact points of the Si-COMS driving substrate with metal materials to form a common anode structure, matching the original common cathode structure and then fitting it with the LED array, and uniformly powering the pixel array of the Si-COMS driving substrate, it is ensured that each Micro LED on the LED array receives uniform current, and correct LED emission data can be obtained.

[0046] 2) The Micro LED device of the present invention provides the Micro LED anode endpoints through the top vias of the driving substrate. Each top via represents a pixel anode signal providing endpoint. After connecting the high-density pixel anode electrodes together through a conductive material and then fitting it with the LED array chip, it can be determined that each independent anode endpoint in the LED array can receive the same voltage / current when powered on, thereby effectively detecting the light-emitting characteristics of each independent Micro LED chip in the LED array.

[0047] 3) The present invention directly uses a CMOS driving substrate and processes it to provide the signals required to light up the LED array, and can realize the reuse of the transient driving substrate, so that it can be reused after the fitting power-on test is completed. Description of the Drawings

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0049] Figure 1 is a schematic flow chart of a detection method for Micro LED according to an embodiment of the present invention;

[0050] Figure 2 is a schematic structural diagram of the top layer of the COMS driving substrate in a detection method for Micro LED according to an embodiment of the present invention;

[0051] Figure 3 is a schematic diagram of the Si-COMS driving substrate covering the insulating layer in a detection method for Micro LED according to an embodiment of the present invention;

[0052] Figure 4 is a schematic diagram of the removal of materials on the top layer via metal in a detection method for Micro LED according to an embodiment of the present invention;

[0053] Figure 5 is a schematic diagram of covering photoresist in a detection method for Micro LED according to an embodiment of the present invention;

[0054] Figure 6 is a schematic diagram after exposure / development processing in a detection method for Micro LED according to an embodiment of the present invention;

[0055] Figure 7 is a schematic diagram of depositing a conductive metal material during the production process of the transient driving substrate in a detection method for Micro LED according to an embodiment of the present invention;

[0056] Figure 8 is a schematic diagram of removing the photoresist to separate the cathode contact point and the anode contact point of the transient driving substrate in a detection method for Micro LED according to an embodiment of the present invention;

[0057] Figure 9 is a schematic diagram of defining the position for depositing the second conductive metal material in a detection method for Micro LED according to an embodiment of the present invention;

[0058] Figure 10 is a schematic diagram of depositing the second conductive metal material in a detection method for Micro LED according to an embodiment of the present invention;

[0059] Figure 11Schematic diagram of a transient driving substrate in a Micro LED detection method according to an embodiment of the present invention;

[0060] Figure 12 Schematic diagram of the structure of a GaN EPI Wafer in a Micro LED detection method according to an embodiment of the present invention;

[0061] Figure 13 Schematic diagram of defining an LED pattern in a Micro LED detection method according to an embodiment of the present invention;

[0062] Figure 14 Schematic diagram of defining an anode contact point in a Micro LED detection method according to an embodiment of the present invention;

[0063] Figure 15 Schematic diagram of depositing a SiOx insulating layer in a Micro LED detection method according to an embodiment of the present invention;

[0064] Figure 16 Schematic diagram of defining anode / cathode contact points in a Micro LED detection method according to an embodiment of the present invention;

[0065] Figure 17 Schematic diagram of defining a conductive metal material and an anode contact point pattern in a Micro LED detection method according to an embodiment of the present invention;

[0066] Figure 18 Schematic diagram of depositing a conductive metal material in a common cathode architecture Micro LED array substrate in a Micro LED detection method according to an embodiment of the present invention;

[0067] Figure 19 Schematic diagram of a common cathode architecture Micro LED array substrate in a Micro LED detection method according to an embodiment of the present invention;

[0068] Figure 20 Schematic diagram of the bonding of a transient driving substrate and a common cathode architecture Micro LED array substrate in a Micro LED detection method according to an embodiment of the present invention;

[0069] Figure 21 Schematic diagram of the contact of the conductive metal materials of a transient driving substrate and a common cathode architecture Micro LED array substrate in a Micro LED detection method according to an embodiment of the present invention. Detailed implementation manners

[0070] To further illustrate the embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. These drawings mainly illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, those of ordinary skill in the art should be able to understand other possible implementation manners and the advantages of the present invention. The components in the drawings are not drawn to scale, and similar component symbols are usually used to represent similar components.

[0071] According to an embodiment of the present invention, a method for detecting Micro LEDs is provided. In the prior art, in a common cathode architecture, due to insufficient input points for the anode test signal, the impedance of the anode trace is not matched, resulting in poor lighting effects (bright / slightly bright / not bright) of the LED array. Each circuit in the equalization circuit of the Si-COMS driving substrate display area drives one LED. The concept of the present invention is to process the Si-COMS driving substrate to make a transient substrate for screening the quality of the LED array. Mainly connect the anode contact points of the Si-COMS driving substrate with a metal material to form a common anode structure, and cooperate with the original common cathode architecture to fit with the LED array. After evenly supplying power to the pixel array of the Si-COMS driving substrate, ensure that each Micro LED on the LED array receives uniform current, and correct LED emission data can be obtained.

[0072] In the present invention, the Micro LED device is provided with a top via on the driving substrate to supply power to the Micro LED anode end point. Each top via represents an anode signal supply end point for a pixel. After connecting the high-density pixel anode electrodes together through a conductive material and then fitting with the LED array chip, when powered on, it can be ensured that each independent anode end point in the LED array can receive the same voltage / current, thereby effectively detecting the light-emitting characteristics of each independent micro led chip in the LED array.

[0073] The key points of the present invention include not only the LED chip manufacturing process, but also directly using a CMOS driving substrate and processing it to provide the signals required to light up the LED array. And this driving substrate can be reused. After the power-on test is completed after fitting, it can be reused.

[0074] Specifically, the present invention will be further described in conjunction with the accompanying drawings and specific embodiments. As Figures 1 - 21 shown, a method for detecting Micro LEDs according to an embodiment of the present invention includes the following steps:

[0075] S1. Process the pre-prepared Si-COMS driving substrate to obtain a transient driving substrate;

[0076] Among them, the processing of the pre-prepared Si-COMS driving substrate to obtain a transient driving substrate includes the following steps:

[0077] S11. Prepare a Si-COMS driving substrate and perform an insulating layer covering treatment (as Figure 3 shown); specifically, the material of the insulating layer is SiOx inorganic material or organic photoresist material.

[0078] S12. Continuously perform exposure / development and etching treatment based on the material of the insulating layer, and remove the material on the top layer via-hole metal (as Figure 4 shown);

[0079] S13. Cover a photoresist on the top of the insulating layer after the S12 treatment (as Figure 5 shown);

[0080] S14. Perform exposure / development treatment again to separate the cathode contact points and anode contact points on the transient driving substrate (as Figure 6 shown);

[0081] S15. Deposit a conductive metal material on the top of the transient driving substrate after the re-exposure / development treatment; (as Figure 7 shown)

[0082] S16. Perform a photoresist removal treatment to separate the cathode contact points and anode contact points on the transient driving substrate (as Figure 8 shown);

[0083] S17. Define the position for the second deposition of the conductive metal material and perform the second deposition of the conductive metal material (as Figures 9 - 10 shown);

[0084] Specifically, the defining the position for the second deposition of the conductive metal material and performing the second deposition of the conductive metal material includes the following steps:

[0085] Perform photoresist coating and exposure / development treatment on the transient driving substrate after removing the photoresist to define the position for the second deposition of the conductive metal material;

[0086] Perform the second deposition of the conductive metal material at the position for the second deposition of the conductive metal material.

[0087] S18. Perform a photoresist removal treatment again to obtain the transient driving substrate (as Figure 11 shown).

[0088] S2. Process the pre-prepared gallium nitride epitaxial wafer to obtain a common cathode architecture Micro LED array substrate;

[0089] Specifically, the processing of the pre-prepared gallium nitride epitaxial wafer to obtain a common cathode architecture MicroLED array substrate includes the following steps:

[0090] S21. Prepare a gallium nitride epitaxial wafer (GaN EPI Wafer) (as Figure 12 shown), and define the LED pattern through an exposure / development / etching process (as Figure 13 shown);

[0091] S22. Deposit indium tin oxide and define the anode contact points through an exposure / development / etching process (as Figure 14 shown);

[0092] S23. Deposit a SiOx insulating layer to repair and protect the sidewalls of the LED; specifically, the deposition of the SiOx insulating layer is achieved by using atomic layer deposition (ALD) and chemical vapor deposition (CVD) techniques (as Figure 15 shown).

[0093] S24. Use an etching process method to perform an opening process on the top of the SiOx insulating layer to define the anode / cathode contact points (as Figure 16 shown);

[0094] Specifically, the use of the etching process method to perform an opening process on the top of the SiOx insulating layer includes the following steps:

[0095] Etch the SiOx insulating layer to achieve an opening process on the top of the SiOx insulating layer;

[0096] Clean the etched SiOx insulating layer.

[0097] S25. Perform a photoresist coating process and define the conductive metal material and anode contact point pattern through exposure / development (as Figure 17 shown);

[0098] S26. Deposit the conductive metal material based on the conductive metal material and anode contact point pattern (as Figure 18 shown);

[0099] S27. Perform a photoresist removal process to obtain a common cathode architecture Micro LED array substrate (as Figure 19 shown).

[0100] S3. Move the wafer stage to achieve the bonding of the transient drive substrate and the common cathode architecture Micro LED array substrate;

[0101] Among them, the moving of the wafer stage to achieve the bonding of the transient drive substrate and the common cathode architecture Micro LED array substrate includes the following steps:

[0102] Fix one end of the wafer stage and move the other end of the wafer stage (either the upper or lower stage is fixed and the other is movable) to achieve the fitting of the transient driving substrate and the common cathode structure Micro LED array substrate before testing (as Figure 20 shown).

[0103] S4. Apply power to the transient driving substrate for visual inspection based on automatic optical inspection;

[0104] Among them, applying power to the transient driving substrate for visual inspection based on automatic optical inspection includes the following steps:

[0105] S41. After the metal materials of the transient driving substrate and the common cathode structure Micro LED array substrate come into contact, apply power to the transient driving substrate (as Figure 21 shown);

[0106] S42. The common cathode structure Micro LED array substrate emits light to achieve visual inspection based on automatic optical inspection.

[0107] S5. After the test is completed, separate the transient driving substrate and the common cathode structure Micro LED array substrate.

[0108] Among them, separating the transient driving substrate and the common cathode structure Micro LED array substrate after the test is completed further includes the following steps: After the separation is completed, prepare the next common cathode structure Micro LED array substrate and perform power-on testing on it.

[0109] In summary, by means of the above technical solutions of the present invention, the Si-COMS driving substrate is processed into a transient driving substrate for LED array quality screening. The anode contact points of the Si-COMS driving substrate are connected with metal materials to form a common anode structure, which is combined with the original common cathode structure and then fitted with the LED array. After uniformly powering the pixel array of the Si-COMS driving substrate, it is ensured that each Micro LED on the LED array receives uniform current, and correct LED emission data can be obtained.

[0110] In addition, the Micro LED device of the present invention provides the Micro LED anode endpoints through the via holes on the top layer of the driving substrate. Each top layer via hole represents a pixel anode signal providing endpoint. After connecting the high-density pixel anode electrodes together through a conductive material and then fitting with the LED array chip, it can be determined that each independent anode endpoint in the LED array can receive the same voltage / current when powered on, thereby effectively detecting the light emission characteristics of each independent Micro LED chip in the LED array.

[0111] In addition, the present invention directly uses a CMOS driving substrate for processing to provide signals required for lighting the LED array, enabling the reuse of the transient driving substrate, so that it can be reused after the fitting power supply test is completed.

[0112] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A detection method for Micro LED, characterized in that, The detection method includes the following steps: S1. Process the pre-prepared Si-COMS driving substrate to obtain a transient driving substrate; S2. Process the pre-prepared gallium nitride epitaxial wafer to obtain a common cathode architecture Micro LED array substrate; S3. Move the wafer stage to realize the bonding of the transient driving substrate and the common cathode architecture Micro LED array substrate; S4. Apply power to the transient driving substrate and perform visual inspection based on automatic optical inspection; S5. After the test is completed, separate the transient driving substrate and the common cathode architecture Micro LED array substrate.

2. The detection method of a Micro LED according to claim 1, characterized in that, The process of processing the pre-prepared Si-COMS driving substrate to obtain a transient driving substrate includes the following steps: S11. Prepare the Si-COMS driving substrate and perform an insulating layer covering treatment; S12. Continuously perform exposure / development and etching treatments based on the material of the insulating layer, and remove the material on the top via-hole metal; S13. Cover a photoresist on the top of the insulating layer after the S12 treatment; S14. Perform exposure / development treatment again to separate the cathode contact points and anode contact points on the transient driving substrate; S15. Deposit a conductive metal material on the top of the transient driving substrate after the re-exposure / development treatment; S16. Perform a photoresist removal treatment to separate the cathode contact points and anode contact points on the transient driving substrate; S17. Define the position for the second deposition of the conductive metal material and perform the second deposition of the conductive metal material; S18. Perform a photoresist removal treatment again to obtain the transient driving substrate.

3. The detection method of a Micro LED according to claim 2, characterized in that, The material of the insulating layer is SiOx inorganic material or organic photoresist material.

4. A detection method for a Micro LED according to claim 2, characterized in that, The process of defining the position for the second deposition of the conductive metal material and performing the second deposition of the conductive metal material includes the following steps: Perform photoresist coating and exposure / development treatments on the transient driving substrate with the photoresist removed to define the position for the second deposition of the conductive metal material; Perform the second deposition of the conductive metal material at the position for the second deposition of the conductive metal material.

5. A detection method for a Micro LED according to claim 1, characterized in that, The process of processing the pre-prepared gallium nitride epitaxial wafer to obtain a common cathode architecture Micro LED array substrate includes the following steps: S21. Prepare the gallium nitride epitaxial wafer and define the LED pattern through an exposure / development / etching process; S22. Deposit indium tin oxide and define the anode contact points through an exposure / development / etching process; S23. Deposit a SiOx insulating layer to repair and protect the sidewalls of the LEDs; S24. Use an etching process method to perform an opening treatment on the top of the SiOx insulating layer to define the anode / cathode contact points; S25. Perform a photoresist coating treatment and define the conductive metal material and anode contact point pattern through exposure / development; S26. Deposit the conductive metal material based on the conductive metal material and anode contact point pattern; S27. Perform a photoresist removal treatment to obtain the common cathode architecture Micro LED array substrate.

6. The detection method of a Micro LED according to claim 5, characterized in that, The deposition of the SiOx insulating layer is realized by using atomic vapor deposition technology and chemical vapor deposition technology.

7. A detection method for Micro LED according to claim 5, characterized in that, The method of opening holes at the top of the SiOx insulating layer using an etching process includes the following steps: Etch the SiOx insulating layer to achieve hole opening at the top of the SiOx insulating layer; Clean the etched SiOx insulating layer.

8. A detection method for a Micro LED according to claim 1, characterized in that, The method of moving the wafer stage to achieve the bonding of the transient driving substrate and the common cathode architecture Micro LED array substrate includes the following steps: Fix one end of the wafer stage and move the other end of the wafer stage to achieve the bonding of the transient driving substrate and the common cathode architecture MicroLED array substrate.

9. The detection method of a Micro LED according to claim 1, wherein, The method of powering the transient driving substrate and performing visual inspection based on automatic optical inspection includes the following steps: S41. After the metal materials of the transient driving substrate and the common cathode architecture Micro LED array substrate come into contact, power the transient driving substrate; S42. The common cathode architecture Micro LED array substrate emits light to achieve visual inspection based on automatic optical inspection.

10. A detection method for a Micro LED according to claim 1, characterized in that, After the test is completed, separating the transient driving substrate and the common cathode architecture Micro LED array substrate further includes the following steps: After separation, prepare the next common cathode architecture Micro LED array substrate and perform power-on testing on it.

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