MicroLED wafer array testing device and method

Abstract

The invention discloses a device and a method for testing a MicroLED wafer array. The device comprises a wafer slide holder, a MicroLED test device and a photometric integrating sphere, a MicroLED wafer is arranged on the wafer slide holder; the MicroLED wafer is provided with a MicroLED wafer array, and the MicroLED wafer array is provided with a plurality of The MicroLED wafer array is composed of a plurality of MicroLEDs which are distributed in an array form; the MicroLED test equipment comprises a flexible electrode and a TFT (Thin Film Transistor) addressing circuit; the wafer slide holder is used for enabling a MicroLED wafer to be aligned with the MicroLED test equipment so as to enable the MicroLED to be lightened, and visible light emitted after the MicroLED is lightened is transmitted to the photometric integrating sphere through the MicroLED test equipment; the photometric integrating sphere is used for testing optical parameters of the MicroLED; the optical parameters comprise optical power and wavelength; and the TFT addressing circuit is used for providing current, voltage and position parameters of the MicroLED. According to the device and the method, the optical parameters and the position of each MicroLED in the MicroLED wafer array can be rapidly tested in a lossless and high-throughput manner.

Description

Technical Field

[0001] This application relates to the field of MicroLED technology, and in particular to a testing device and method for MicroLED wafer arrays. Background Technology

[0002] As a core component of next-generation display technology and silicon photonics integrated visible light sources, the efficiency and accuracy of wafer-level testing in the manufacturing process of MicroLEDs directly determine the yield and cost of end products. However, traditional testing methods suffer from physical damage, insufficient detection accuracy, and low efficiency, failing to meet the demands of MicroLED industrialization. Developing a rapid, non-destructive, and high-throughput array testing method is crucial to overcoming current technological bottlenecks.

[0003] Existing MicroLED wafer testing methods mainly face three major problems: physical contact damage, limitations of non-contact detection, and efficiency bottlenecks. These problems severely restrict the industrialization and large-scale production of MicroLED technology.

[0004] Physical contact damage issues: 1) Destructive nature of traditional rigid probes: Traditional testing methods use rigid probes for electroluminescence (EL) testing, applying excessive pressure (usually exceeding 10 MPa), which can easily scratch the metal pads and semiconductor structure on the surface of MicroLED wafers. MicroLED chips are tiny (usually less than 50 micrometers) and fragile; rigid contact can cause irreversible physical damage, increasing the risk of wafer scrapping; 2) Probe wear and lifespan limitations: Rigid probes need to be replaced after approximately 100,000 uses due to wear, which not only increases equipment maintenance costs but also significantly impacts testing efficiency due to downtime caused by replacement.

[0005] Limitations of non-contact inspection: 1) Insufficiency of photoluminescence (PL) testing: Although PL testing has the advantage of being non-contact, allowing for testing without direct contact with the chip, it can only evaluate limited parameters such as external quantum efficiency and cannot simulate photoelectric performance under actual working conditions. Its detection effect is slightly inferior to EL testing, and it cannot accurately detect all defects, which may lead to a false negative rate as high as 15%-20%, failing to meet the requirements of high-quality applications; 2) Insufficiency of visual inspection: Pure visual methods can only identify visible surface defects (such as cracks and missing parts), and are powerless against microscopic defects (such as electrode oxidation and internal cracks) and optical parameter abnormalities (wavelength non-uniformity and insufficient brightness), resulting in a high false positive rate.

[0006] Testing efficiency bottleneck: Low efficiency of single-point sequential testing: Traditional methods typically employ single-point sequential testing, which can take hours or even days when dealing with massive quantities of MicroLED chips (each wafer contains millions to tens of millions of chips). For example, testing the 25 million MicroLED chips required for a 4K display could take more than 40 hours just for the testing phase, making it unsuitable for large-scale production.

[0007] Lack of standardized testing procedures: The industry has long lacked unified testing standards, with different manufacturers using custom testing conditions and parameters. This makes it difficult to compare and mutually recognize test results, increasing supply chain complexity and costs. Consequently, it is difficult to guarantee the consistency and reliability of MicroLED product quality, hindering the commercialization of the technology.

[0008] The principle of rigid probe EL testing is: electrical contact measurement, which has the advantage of high measurement accuracy, but causes physical damage and wears out quickly. It is suitable for the R&D stage and sampling inspection. The principle of photoluminescence (PL) testing is: laser excitation of light, which has the advantages of non-contact and non-destructive, but has a high false negative rate and cannot measure electrical characteristics. It is suitable for initial screening and is used in conjunction with EL. The principle of visual surface inspection is: image recognition of defects, which can quickly identify macroscopic defects, but cannot detect optical parameters and has a high false positive rate. It is suitable for surface quality inspection. The principle of new flexible probe EL testing is: flexible contact and adaptive deformation, which has the advantages of non-destructive and long lifespan. However, the technology is not yet widespread and the cost is high. It is suitable for high-end manufacturing and full inspection. Summary of the Invention

[0009] To address the problems of physical contact damage, limitations of non-contact detection, and efficiency bottlenecks in existing MicroLED wafer testing methods, this application provides a testing device and method for MicroLED wafer arrays. This method is a fast, non-destructive, and high-throughput MicroLED wafer array testing method, which improves testing efficiency and production capacity and enables full-process yield control.

[0010] This application discloses a testing apparatus for a MicroLED wafer array, comprising a wafer stage, a MicroLED testing device, and a photometric integrating sphere. A MicroLED wafer is disposed on the wafer stage. A MicroLED wafer array is disposed on the MicroLED wafer. The MicroLED wafer array consists of multiple MicroLEDs distributed in an array. The MicroLED testing device includes flexible electrodes and a TFT addressing circuit. The wafer stage is used to align the MicroLED wafer with the MicroLED testing device, thereby illuminating the MicroLED. The visible light emitted by the illuminated MicroLED is transmitted to the photometric integrating sphere through the MicroLED testing device. The photometric integrating sphere is used to test the optical parameters of the MicroLED, including optical power and wavelength. The TFT addressing circuit provides the current, voltage, and position parameters of the MicroLED.

[0011] Furthermore, the MicroLED testing equipment is located above the MicroLED wafer; the wafer stage moves in three-dimensional space to move the MicroLED wafer in three-dimensional space, so that the electrodes of the MicroLED on the MicroLED wafer come into contact with the flexible electrodes, thereby illuminating the MicroLED.

[0012] Furthermore, the MicroLED testing equipment also includes a driving circuit and a control unit; the driving circuit is used to scan each MicroLED on the MicroLED wafer line by line and record the position information of each MicroLED; the control unit is used to control the operation of the driving circuit so that the driving circuit can realize line-by-line scanning.

[0013] Furthermore, the MicroLED testing equipment also includes a transparent glass substrate and a TFT addressing circuit; the transparent glass substrate is located above the TFT addressing circuit; the TFT addressing circuit is distributed on the transparent glass substrate in the form of a grid; each flexible electrode is located at each intersection on the grid corresponding to the TFT addressing circuit; the TFT addressing circuit is used to control the current flowing to each MicroLED.

[0014] Furthermore, the flexible electrode is positioned below the TFT addressing circuit; when the optical parameters of the MicroLED are tested, the position of the MicroLED wafer stage is adjusted so that the distance between the flexible electrode and the MicroLED wafer is less than the distance between the transparent glass substrate and the MicroLED wafer.

[0015] Furthermore, it also includes a moving device, which is used to move the MicroLED testing equipment in three-dimensional space so that the MicroLED testing equipment can move closer to or further away from the MicroLED wafer.

[0016] Furthermore, it also includes a gripping device for gripping the MicroLED wafer and placing it on the MicroLED wafer.

[0017] Furthermore, the spacing between the flexible electrodes in the MicroLED testing equipment is equal to the spacing between the MicroLEDs on the MicroLED wafer.

[0018] This application improves testing efficiency and capacity, enables end-to-end yield control, and reduces costs.

[0019] This application also discloses a testing method for MicroLED wafer arrays, applicable to the aforementioned testing apparatus for MicroLED wafer arrays, comprising: The gripping device places the MicroLED wafer on the wafer carrier stage, the moving device places the MicroLED testing equipment above the MicroLED wafer and faces the MicroLED wafer with the flexible electrode; and the photometric integrating sphere is placed above the MicroLED testing equipment. By moving the wafer stage, the MicroLED wafer located on the wafer stage is aligned with the MicroLED testing equipment, and at the same time, the MicroLED on the MicroLED wafer can make contact with the flexible electrode on the MicroLED testing equipment. The control circuit of the MicroLED testing equipment controls the drive circuit to scan each MicroLED on the MicroLED wafer line by line and light it up one by one. The visible light emitted by the MicroLED after it is lit up is transmitted through the MicroLED testing equipment to the photometric integrating sphere. The photometric integrating sphere tests the optical parameters of the visible light and records the optical parameters of the MicroLED and the position information obtained by line-by-line addressing.

[0020] Furthermore, the moving device drives the MicroLED testing equipment to move upward, and the wafer stage moves on the horizontal plane so that the untested MicroLEDs on the MicroLED wafer come into contact with the flexible electrodes on the MicroLED testing equipment. The control circuit of the MicroLED testing equipment controls the driving circuit to scan each MicroLED on the MicroLED wafer line by line and light it up one by one. The visible light emitted by the MicroLED after it is lit up is transmitted through the MicroLED testing equipment to the photometric integrating sphere. The photometric integrating sphere tests the optical parameters of the visible light and records the optical parameters of the MicroLED and the position information obtained by line by line. This process continues until the optical parameters of all MicroLEDs on the MicroLED wafer have been tested.

[0021] Due to the adoption of the above technical solution, this application has the following advantages: 1. Improved testing efficiency and throughput: The array testing method adopts the principle of parallel testing, which can simultaneously perform electroluminescence (EL) testing on tens of thousands of MicroLED chips, reducing the testing time from tens of hours to just a few minutes, and significantly increasing the testing throughput. This high-throughput testing capability is a necessary condition for realizing the large-scale mass production of MicroLEDs, enabling the production line to meet the huge future market demand for MicroLED displays and optical interconnect components.

[0022] 2. Achieve end-to-end yield control: Rapid array testing can be performed online at multiple manufacturing stages (such as before mass transfer, after bonding, and before packaging), providing real-time wafer quality data to guide process adjustments. For example, removing defective dies before mass transfer can prevent defective chips from being transferred to the display backplane, reducing subsequent repair costs and material waste. This is crucial for yield improvement and cost control. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in the embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0024] Figure 1 This is a schematic diagram of a testing device for a MicroLED wafer array according to an embodiment of this application; Figure 2 This is a top view of the MicroLED testing equipment according to an embodiment of this application; Figure 3 This is a schematic diagram showing the positions of the wafer stage and the MicroLED wafer in a three-dimensional Cartesian coordinate system according to an embodiment of this application. Reference numerals: 1-Integrating sphere for light measurement, 2-MicroLED test card, 3-MicroLED wafer, 4-Wafer stage, 5-TFT addressing circuit, 6-Flexible electrode, 7-Transparent glass substrate. Detailed Implementation

[0025] The present application will be further described in conjunction with the accompanying drawings and embodiments. The described embodiments are only some, not all, of the embodiments of the present application. All other embodiments obtained by those skilled in the art should fall within the protection scope of the embodiments of the present application.

[0026] See Figure 1This application provides an embodiment of a testing apparatus for a MicroLED wafer array, comprising a wafer stage 4, a MicroLED testing device, and a photometric integrating sphere 1; a MicroLED wafer 3 is disposed on the wafer stage 4; a MicroLED wafer array is disposed on the MicroLED wafer 3; the MicroLED wafer array consists of multiple MicroLEDs distributed in an array; the MicroLED testing device includes a flexible electrode 6 and a TFT addressing circuit 5; the wafer stage 4 is used to align the MicroLED wafer 3 with the MicroLED testing device, thereby illuminating the MicroLED; the visible light emitted by the illuminated MicroLED is transmitted to the photometric integrating sphere 1 through the MicroLED testing device; the photometric integrating sphere 1 is used to test the optical parameters of the MicroLED; the optical parameters include optical power and wavelength; the TFT addressing circuit 5 is used to provide the current, voltage, and position parameters of the MicroLED. The MicroLED testing device can be a MicroLED test card 2.

[0027] In this embodiment, the MicroLED testing equipment is located above the MicroLED wafer 3; the wafer stage 4 moves in three-dimensional space to drive the MicroLED wafer 3 to move in three-dimensional space, so that the electrodes of the MicroLED on the MicroLED wafer 3 come into contact with the flexible electrode 6, thereby illuminating the MicroLED.

[0028] In this embodiment of the application, the MicroLED testing equipment further includes a driving circuit and a control unit; the driving circuit is used to scan each MicroLED on the MicroLED wafer 3 line by line and record the position information of each MicroLED; the control unit is used to control the operation of the driving circuit so that the driving circuit can realize line-by-line scanning.

[0029] In this embodiment of the application, the MicroLED testing equipment further includes a transparent glass substrate 7 and a TFT addressing circuit 5; the transparent glass substrate 7 is located above the TFT addressing circuit 5; the TFT addressing circuit 5 is distributed on the transparent glass substrate 7 in the form of a grid; each flexible electrode 6 is located at each intersection on the grid corresponding to the TFT addressing circuit 5; the TFT addressing circuit 5 is used to control the current flowing to each MicroLED.

[0030] In this embodiment, the flexible electrode 6 is disposed below the TFT addressing circuit 5; when the optical parameters of the MicroLED are tested, the position of the MicroLED wafer stage is adjusted so that the distance between the flexible electrode 6 and the MicroLED wafer 3 is less than the distance between the transparent glass substrate 7 and the MicroLED wafer 3.

[0031] In this embodiment of the application, a mobile device is also included, which is used to drive the MicroLED testing equipment to move in three-dimensional space so that the MicroLED testing equipment moves closer to or further away from the MicroLED wafer 3.

[0032] In this embodiment of the application, a gripping device is also included, which is used to grip the MicroLED wafer 3 and place it on the MicroLED wafer 3.

[0033] In this embodiment of the application, the spacing between the flexible electrodes 6 in the MicroLED testing equipment is equal to the spacing between the MicroLEDs on the MicroLED wafer 3.

[0034] In the above embodiments, the substrate of the MicroLED test card is a transparent glass substrate, which is transparent to visible and infrared light. The light emitted during MicroLED testing can pass through the glass and be measured by the integrating sphere above it to determine its optical power and wavelength. The glass substrate for fabricating the MicroLED test card can be an 8-inch or 12-inch glass wafer, on which a standard TFT driving circuit is fabricated. The wiring of the TFT driving circuit uses transparent ITO material so that the MicroLED optical fiber can pass through to reach the test integrating sphere.

[0035] The period of the flexible electrodes distributed at the TFT addressing nodes is the same as the period of the MicroLED wafer. The fabricated glass-based TFT two-dimensional array addressing test unit is diced, and multiple MicroLED test cards can be fabricated from a single glass wafer.

[0036] Flexible electrodes are fabricated at the nodes of TFT addressing circuit 5, and the distribution period of the flexible electrodes is the same as that of the MicroLED wafer array under test. For MicroLED array, one The test card can cover 360,000 MicroLEDs, if the MicroLED size is... This can cover 1 million MicroLEDs.

[0037] The completed glass-based TFT two-dimensional array addressing test unit is connected to the interface of the TFT addressing circuit 5 to form a complete TFT two-dimensional array addressing test card (MicroLED test card).

[0038] The TFT two-dimensional addressable array test card control unit controls the movement and alignment of the MicroLED wafer alignment stage, controls the scanning and testing process of the MicroLED wafer array, and synchronizes the movement of the MicroLED wafer position during the testing process, while simultaneously recording the MicroLED position and photoelectric parameters.

[0039] This application also provides an embodiment of a testing method for MicroLED wafer arrays, applicable to the testing apparatus for MicroLED wafer arrays described in the above embodiments, comprising: The gripping device places the MicroLED wafer 3 on the wafer stage 4, the moving device places the MicroLED testing equipment above the MicroLED wafer 3 and makes the flexible electrode 6 face the MicroLED wafer 3; and the photometric integrating sphere 1 is placed above the MicroLED testing equipment. By moving the wafer stage 4, the MicroLED wafer 3 located on the wafer stage 4 is aligned with the MicroLED testing equipment, and at the same time, the MicroLED on the MicroLED wafer 3 can contact the flexible electrode 6 on the MicroLED testing equipment. The control circuit of the MicroLED testing equipment controls the drive circuit to scan each MicroLED on the MicroLED wafer 3 line by line and light it up one by one. The visible light emitted by the MicroLED after it is lit up is transmitted through the MicroLED testing equipment to the photometric integrating sphere 1. The photometric integrating sphere 1 tests the optical parameters of the visible light and records the optical parameters of the MicroLED and the position information obtained by line by line addressing.

[0040] In this embodiment of the application, the mobile device drives the MicroLED testing equipment to move upward, and the wafer stage 4 moves on the horizontal plane so that the untested MicroLED on the MicroLED wafer 3 comes into contact with the flexible electrode 6 on the MicroLED testing equipment. The control circuit of the MicroLED testing equipment controls the drive circuit to scan each MicroLED on the MicroLED wafer 3 line by line and light it up one by one. The visible light emitted by the MicroLED after it is lit up is transmitted through the MicroLED testing equipment to the photometric integrating sphere 1. The photometric integrating sphere 1 tests the optical parameters of the visible light and records the optical parameters of the MicroLED and the position information obtained by line by line. This process continues until the optical parameters of all MicroLEDs on MicroLED wafer 3 are tested.

[0041] See Figure 2 Two-dimensional addressing testing is implemented by driving circuit to scan MicroLEDs row by row and one by one, enabling electroluminescence (EL) testing of tens of thousands or even millions of MicroLED chips, reducing the testing time from tens of hours to a few minutes, and greatly improving the testing throughput.

[0042] See Figure 3The MicroLED wafer alignment stage can move up and down in the X, Y, and Z directions, and can rotate around the Z-axis (rotation angle is ). The wafer stage is aligned and makes contact with the TFT 2D array addressing test card. The addressing circuit of the TFT 2D array addressing test card tests each MicroLED row by row sequentially, scanning and testing to complete an entire array cell. The wafer stage descends and moves to the next test cell position, aligning and making contact with the TFT 2D array addressing test card again, scanning and testing to complete the second array cell. This step-scan test is repeated until the entire wafer is fully tested. The photoelectric parameters of all MicroLED chips are recorded.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and not to limit them. Although this application has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this application. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this application should be covered within the protection scope of the claims of this application.

Claims

1. A testing device for a MicroLED wafer array, characterized in that, It includes a wafer stage, MicroLED testing equipment, and a photometric integrating sphere; MicroLED wafers are mounted on the wafer stage; MicroLED wafer arrays are mounted on the MicroLED wafers; the MicroLED wafer arrays consist of multiple MicroLEDs distributed in an array; the MicroLED testing equipment includes flexible electrodes and TFT addressing circuits; The wafer stage is used to align the MicroLED wafer with the MicroLED testing equipment, thereby illuminating the MicroLED. The visible light emitted by the MicroLED after it is lit is transmitted to the photometric integrating sphere through the MicroLED testing equipment. The photometric integrating sphere is used to test the optical parameters of the MicroLED, including optical power and wavelength. The TFT addressing circuit is used to provide the current, voltage, and position parameters of the MicroLED.

2. The testing apparatus for MicroLED wafer arrays according to claim 1, characterized in that, The MicroLED testing equipment is located above the MicroLED wafer; the wafer stage moves in three-dimensional space to move the MicroLED wafer in three-dimensional space, so that the electrodes of the MicroLED on the MicroLED wafer come into contact with the flexible electrodes, thereby lighting up the MicroLED.

3. The testing apparatus for MicroLED wafer arrays according to claim 1, characterized in that, The MicroLED testing equipment also includes a driving circuit and a control unit; the driving circuit is used to scan each MicroLED on the MicroLED wafer line by line and record the position information of each MicroLED; the control unit is used to control the operation of the driving circuit so that the driving circuit can perform line-by-line scanning.

4. The testing apparatus for MicroLED wafer arrays according to claim 1, characterized in that, The MicroLED testing equipment also includes a transparent glass substrate and a TFT addressing circuit. The transparent glass substrate is located above the TFT addressing circuit. The TFT addressing circuit is distributed on the transparent glass substrate in a grid pattern. Each flexible electrode is located at each intersection on the grid corresponding to the TFT addressing circuit. The TFT addressing circuit is used to control the current flowing to each MicroLED.

5. The testing apparatus for MicroLED wafer arrays according to claim 4, characterized in that, The flexible electrode is positioned below the TFT addressing circuit. When testing the optical parameters of the MicroLED, the position of the MicroLED wafer stage is adjusted so that the distance between the flexible electrode and the MicroLED wafer is less than the distance between the transparent glass substrate and the MicroLED wafer.

6. The testing apparatus for MicroLED wafer arrays according to claim 1, characterized in that, It also includes a moving device, which is used to move the MicroLED testing equipment in three-dimensional space so that the MicroLED testing equipment can move closer to or further away from the MicroLED wafer.

7. The testing apparatus for MicroLED wafer arrays according to claim 1, characterized in that, It also includes a gripping device for gripping MicroLED wafers and placing them on the MicroLED wafers.

8. The testing apparatus for MicroLED wafer arrays according to claim 1, characterized in that, The spacing between the flexible electrodes in the MicroLED testing equipment is equal to the spacing between the MicroLEDs on the MicroLED wafer.

9. A testing method for a MicroLED wafer array, applicable to the testing apparatus for the MicroLED wafer array according to any one of claims 1-8, characterized in that, include: The gripping device places the MicroLED wafer on the wafer carrier stage, the moving device places the MicroLED testing equipment above the MicroLED wafer and faces the MicroLED wafer with the flexible electrode; and the photometric integrating sphere is placed above the MicroLED testing equipment. By moving the wafer stage, the MicroLED wafer located on the wafer stage is aligned with the MicroLED testing equipment, and at the same time, the MicroLED on the MicroLED wafer can make contact with the flexible electrode on the MicroLED testing equipment. The control circuit of the MicroLED testing equipment controls the drive circuit to scan each MicroLED on the MicroLED wafer line by line and light it up one by one. The visible light emitted by the MicroLED after it is lit up is transmitted through the MicroLED testing equipment to the photometric integrating sphere. The photometric integrating sphere tests the optical parameters of the visible light and records the optical parameters of the MicroLED and the position information obtained by line-by-line addressing.

10. The testing method for MicroLED wafer arrays according to claim 9, characterized in that, The moving device drives the MicroLED testing equipment to move upward, and the wafer stage moves on the horizontal plane so that the untested MicroLEDs on the MicroLED wafers come into contact with the flexible electrodes on the MicroLED testing equipment. The control circuit of the MicroLED testing equipment controls the driving circuit to scan each MicroLED on the MicroLED wafer line by line and light it up one by one. The visible light emitted by the MicroLED after it is lit up is transmitted through the MicroLED testing equipment to the photometric integrating sphere. The photometric integrating sphere tests the optical parameters of the visible light and records the optical parameters of the MicroLED and the position information obtained by line by line. This process continues until the optical parameters of all MicroLEDs on the MicroLED wafer have been tested.

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