Method for testing electrical performance of flip LED based on electron beam

Abstract

The invention discloses a method for testing the electrical performance of a flip LED based on an electron beam, and the method comprises the following steps: sample pretreatment: carrying out the flattening of a flip or normal Mi cro LED chip, manufacturing a test circuit and electrode protection metal of the chip, connecting all N poles, and arranging a pin at the corner of the region; test device construction: constructing a test device comprising a vacuum unit, an electron beam deflection unit, a test unit and a signal analysis unit; test operation: when the electron beam scans the electrode protection metal, the acceleration voltage of the electron beam is adjusted to test the forward current IF and the reverse leakage current IR of the Mi cro LED chip; processing after the test: after the test is completed, restoring the chip to an initial state; the Mi cro LED electrical performance testing method solves the problems that a traditional probe contact type measuring method is low in testing speed, short in probe service life, prone to chip abrasion and the like, meanwhile, the forward current IF and the reverse leakage current IR can be measured, and efficient, low-cost and accurate Mi cro LED electrical performance testing is achieved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly relates to a method for testing the electrical properties of flip-chip LEDs based on electron beam testing, which is particularly suitable for the electroluminescence (EL) testing of Micro LED chips. Background Art

[0002] With the continuous development of LED technology, the size of LEDs is getting smaller and smaller, and Micro LEDs emerge as the times require. In the production process of Micro LEDs, it is crucial to accurately test their electrical properties; however, when facing the electroluminescence (EL) testing of Micro LEDs, the traditional probe contact measurement method exposes many problems; on the one hand, the number of chips to be tested on a single wafer is extremely large, and using the method of sequentially contacting the PN two electrodes with a probe, the testing speed is extremely slow, seriously affecting production efficiency; on the other hand, the reduction of the chip size makes the probe diameter also decrease, the strength of the probe itself decreases, and then the stability of the probe testing becomes worse, the service life is shortened, increasing the testing cost and error risk.

[0003] The electron beam absorption current (EBAC) characterization method has been widely used in the failure analysis of integrated circuit advanced process chips, with precise positioning and not limited to the same layer analysis; but there is currently no mature solution to effectively apply its principle to the electrical property testing of Micro LEDs; at the same time, although the existing electron beam EL testing system (such as the technology of a detection device and method for the electrical properties of an LED chip with patent number 201910777375.1) solves some problems of probe contact testing, it can only measure parameters such as the forward operating current IF of the chip, and cannot measure the reverse leakage current IR of the LED at the same time; if IR is to be tested, a set of ion gun design needs to be added to the equipment or the redistribution lithography process needs to be increased, which undoubtedly greatly increases the testing cost and operation complexity; in addition, the scheme of using an ion beam to scan the chip electrodes not only easily causes the problem of ion contamination of the chip electrodes, but also the ion source is expensive and difficult to be widely used in actual production. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for testing the electrical properties of flip-chip LEDs based on electron beam testing, so as to solve the problems of slow testing speed, short probe life, easy chip wear, etc. existing in the traditional probe contact measurement method, and at the same time overcome the defect that the existing electron beam testing technology cannot measure the forward current IF and the reverse leakage current IR at low cost simultaneously, and realize efficient, low-cost and accurate electrical property testing of Micro LEDs.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A method for testing the electrical properties of flip-chip LEDs based on electron beam testing, comprising the following steps:

[0007] S1, Sample pretreatment: The flip-chip or face-up Micro LED chips are planarized with a temporary material, and the test circuit and electrode (P-pole and N-pole) protection metals of the chips are fabricated through photolithography evaporation process. All N-poles within a specific area are connected together, and a pin is set at the corner of this area;

[0008] S2, Setup of the test device: Construct a test device including a vacuum unit, an electron beam deflection unit, a test unit, and a signal analysis unit;

[0009] Among them, the vacuum unit is used to create an internal vacuum environment for the electron beam flight area to avoid interference of molecules in the air on the electrons;

[0010] The electron beam deflection unit is used to precisely control the electron beam to sequentially scan the entire Micro LED chip array area;

[0011] The test unit includes an electron gun and a test circuit. The electron gun is used to generate an electron beam, and the test circuit is used to collect the electrical signals in the circuit when the loop is connected and the optical signals generated by the Micro LED when it emits light;

[0012] The signal analysis unit is used to analyze and process the electrical signals collected by the test unit, and then judge the relevant performance of the Micro LED chips;

[0013] S3, Test operation: When the electron beam scans the electrode protection metal, by adjusting the electron beam acceleration voltage, the charge state on the surface of the P-pole protection metal of the Micro LED chip is changed to achieve the test of the forward current IF and reverse leakage current IR of the Micro LED chip and the collection of optical data;

[0014] S3.1, When the electron beam acceleration voltage is adjusted to be between V1 and V2, positive charges are formed on the surface of the P-pole protection metal of the Micro LED chip. The N-pole is connected to the negative pole of the power supply through the protection metal prepared by photolithography and the probe, and a forward current IF is generated between the PN poles of the Micro LED chip. At this time, the forward current IF is tested, and the optical signal of the chip during normal operation is collected simultaneously;

[0015] S3.2, When the electron beam acceleration voltage is adjusted to be lower than V1 or higher than V2, negative charges are formed on the surface of the P-pole protection metal of the Micro LED chip. The N-pole is connected to the positive pole of the power supply through the protection metal prepared by photolithography and the probe, and a reverse leakage current IR is generated between the PN poles of the Micro LED chip. At this time, the reverse leakage current IR is tested;

[0016] S4, Post - test processing: After the test is completed, use an alkaline solution to remove the test circuit and the electrode - protecting metal, and then remove the temporary material for planarization to restore the chip to its initial state.

[0017] In a preferred embodiment, in step S1, the planarization process uses photoresist as the temporary material to form a planarization layer, wherein the thickness range of the photoresist in the planarization layer is 5μm - 15μm.

[0018] In a preferred embodiment, in step S1, the materials of the test circuit and the electrode - protecting metal are made of conductive materials, and their thickness is 0.1μm - 2μm; the size range of the pins is 1μm×1μm - 100μm×100μm.

[0019] In a preferred embodiment, the vacuum degree range of the vacuum unit is 10 -4 Pa - 10 -8 Pa.

[0020] In a preferred embodiment, in the electron - beam deflection unit, the beam - current intensity fluctuation range of the electron beam is controlled within ±1%, and the scanning - position accuracy of the electron beam is controlled within ±0.1μm.

[0021] In a preferred embodiment, the test accuracy of the test unit for the forward current IF is ±0.5%, and the test accuracy for the reverse leakage current IR is ±1%.

[0022] In a preferred embodiment, when the signal - analysis unit analyzes and processes the collected electrical signals, the analysis algorithms used include, but are not limited to, the Fourier - transform algorithm and the wavelet - analysis algorithm, which are used to extract the characteristic parameters of the current signal to judge the performance of the Micro LED chip.

[0023] In a preferred embodiment, in step S3, the value range of the electron - beam acceleration voltage V1 is 3kV - 6kV, and the value range of the electron - beam acceleration voltage V2 is 8kV - 12kV.

[0024] In a preferred embodiment, in step S3, the electron beam is focused into a fine beam by an electromagnetic field and deflected and scanned under the action of the electromagnetic field, and is sequentially irradiated onto the P - poles of each Micro LED chip. At the same time, the N - poles are connected to the power supply through the conductive material prepared by lithography and the probes to form a loop.

[0025] In a preferred embodiment, in step S4, the alkaline solution uses TMAH or KOH solution, the treatment temperature range is 20℃ - 50℃, and the treatment time range is 5min - 20min; the temporary material for planarization is removed by a stripping solution or other organic solvents, the treatment temperature range is 30℃ - 60℃, and the treatment time range is 10min - 30min.

[0026] Due to the application of the above technical solution, the beneficial effects of this application compared with the prior art are as follows:

[0027] A method for testing the electrical properties of flip-chip LEDs based on electron beam has the following advantages:

[0028] 1. Low cost: Compared with the prior art where an ion gun design needs to be added or a complex re-wiring lithography process is carried out to test the reverse leakage current IR, the present invention can measure the forward current IF and the reverse leakage current IR only by adjusting the electron beam acceleration voltage, a simple operation, without the need for additional expensive equipment or complex processes, greatly reducing the test cost.

[0029] 2. High efficiency and accuracy: The electron beam has a fast scanning speed and can quickly complete the testing of a large number of Micro LED chips, improving the test efficiency. At the same time, it avoids the direct contact between the probe and the chip, reducing the test errors caused by contact wear and ensuring the accuracy of the test results.

[0030] 3. Avoiding contamination: Compared with the scheme of using an ion beam to scan the chip electrodes, the present invention uses an electron beam for testing, which will not cause the problem of ion contamination of the chip electrodes, ensuring the quality and performance of the chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0032] Figure 1 It is a flowchart of a method for testing the electrical properties of flip-chip LEDs based on electron beam of the present invention;

[0033] Figure 2 It is a schematic diagram of the principle of electron beam EL testing;

[0034] Figure 3 It is a schematic diagram showing the change trend of the electron beam acceleration voltage of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] In order to enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the protection scope of this application.

[0036] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances for the embodiments of this application described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products, or devices.

[0037] In this application, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", etc. is based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit that the indicated device, element, or component must have a specific orientation, or be constructed and operated in a specific orientation.

[0038] Moreover, in addition to being able to represent the orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0039] In addition, the terms "install", "set", "provided with", "connect", "connected", "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there can also be internal communication between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments may be combined with each other. The following will detail this application with reference to the drawings and in combination with the embodiments.

[0041] Embodiment 1

[0042] Please refer to Figure 1 , this application provides a method for testing the electrical performance of flip-chip LEDs based on electron beam, including the following steps:

[0043] S1, Sample pretreatment: Use photoresist as a temporary material to planarize the flip-chip or face-up Micro LED chip to form a planarization layer. The thickness range of the photoresist in the planarization layer is 5μm - 15μm, and use photolithography evaporation process to fabricate the test circuit and electrode (P pole and N pole) protection metal of the chip, and connect all N poles together in a specific area, and set a pin at the corner of this area; The materials of the test circuit and electrode protection metal are made of conductive materials such as Al or conductive amorphous silicon or polycrystalline silicon materials, and its thickness is 0.1μm - 2μm; The size range of the pin is 1μm×1μm - 100μm×100μm;

[0044] S2, Test device setup: Construct a test device including a vacuum unit, an electron beam deflection unit, a test unit, and a signal analysis unit;

[0045] Among them, the vacuum unit is used to create an internal vacuum environment for the electron beam flight area to avoid interference of air molecules on the electrons; The vacuum degree range of the vacuum unit is 10 -4 Pa - 10 -8 Pa;

[0046] The electron beam deflection unit is used to accurately control the electron beam to sequentially scan the entire Micro LED chip array area; The beam current intensity fluctuation range of the electron beam in the electron beam deflection unit is controlled within ±1%, and the scanning position accuracy of the electron beam is controlled within ±0.1μm;

[0047] The test unit includes an electron gun and a test circuit. The electron gun is used to generate an electron beam, and the test circuit is used to collect the electrical signals in the circuit when the loop is turned on and the optical signals generated by the Micro LED emission; The test accuracy of the test unit for the forward current IF is ±0.5%, and the test accuracy for the reverse leakage current IR is ±1%;

[0048] The signal analysis unit is used to analyze and process the electrical signals collected by the test unit, and then judge the relevant performance of the Micro LED chip; when the signal analysis unit analyzes and processes the collected electrical signals, the analysis algorithms used include but are not limited to the Fourier transform algorithm and the wavelet analysis algorithm, which are used to extract the characteristic parameters of the current signal to judge the performance of the Micro LED chip;

[0049] S3. Testing operation: When the electron beam scans the electrode protection metal, the electron beam is focused into a fine beam by the electromagnetic field and deflected and scanned under the action of the electromagnetic field, and sequentially irradiates the P poles of each Micro LED chip; by adjusting the electron beam acceleration voltage, the charge state on the surface of the P pole protection metal of the Micro LED chip is changed to realize the testing of the forward current IF and the reverse leakage current IR of the Micro LED chip; the value range of the electron beam acceleration voltage V1 is 3 kV - 6 kV, and the value range of the electron beam acceleration voltage V2 is 8 kV - 12 kV;

[0050] S3.1. When the electron beam acceleration voltage is adjusted to be between V1 and V2, positive charges are formed on the surface of the P pole protection metal of the Micro LED chip, and the N pole is connected to the negative pole of the power supply through the protection metal prepared by photolithography and the probe. A forward current IF is generated between the PN poles of the Micro LED chip. At this time, the forward current IF is tested, and the optical signals during normal operation of the chip, such as wavelength, half-wave width, color coordinates, etc., are collected;

[0051] S3.2. When the electron beam acceleration voltage is adjusted to be lower than V1 or higher than V2, negative charges are formed on the surface of the P pole protection metal of the Micro LED chip, and the N pole is connected to the positive pole of the power supply through the protection metal prepared by photolithography and the probe (the positive and negative poles of the external power supply are switched by computer control). A reverse leakage current IR is generated between the PN poles of the Micro LED chip. At this time, the reverse leakage current IR is tested;

[0052] S4. Post-test processing: After the test is completed, use an alkaline solution such as TMAH or KOH solution to remove the test circuit and the electrode protection metal Al, or use XeF gas to remove the conductive amorphous silicon. The processing temperature range is 20°C - 50°C, and the processing time range is 5 min - 20 min; then use a degluing solution or other organic solvents to remove the temporary materials for planarization. The processing temperature range is 30°C - 60°C, and the processing time range is 10 min - 30 min to restore the chip to its initial state.

[0053] Embodiment 2

[0054] Specifically, a method for testing the electrical performance of flip-chip LEDs based on an electron beam is further provided, including the following steps:

[0055] S1, Sample pretreatment:

[0056] Select chips: Select a batch of flip-chip LED chips with a size of 100μm×100μm from COW wafer sources. These chips are gallium nitride (GaN)-based Micro LED chips and are applied to the field of high-resolution displays.

[0057] Planarization treatment: Place the chips on a spin coater and rotate them at a speed of 3000r / min for 30s to uniformly coat a layer of photoresist with a thickness of 10μm as the planarization layer. The viscosity of the photoresist is 20cP to ensure the flatness of the chip surface and provide a good foundation for subsequent processes.

[0058] Lithography and evaporation: Use a lithography machine to perform lithography operations on the chips coated with photoresist. The lithography resolution is 1μm, and the exposure dose is 100mJ / cm 2 , and the development time is 60s to form the patterns of the test circuit and the N-pole protection metal.

[0059] Evaporate Al as the test circuit and the N-pole protection metal through an electron beam evaporation coating device. The thickness of the Al layer is 1μm, and the vacuum degree reaches 10 -6 Pa during evaporation, and the evaporation rate is controlled at 0.5nm / s to ensure uniform coating quality.

[0060] Connect all the N-poles of the Micro LED chips in the same area together with Al wires, and fabricate a pin PAD with a size of 20μm×20μm at the corner of this area for subsequent connection with the probe.

[0061] S2, Test device setup:

[0062] Vacuum unit: Start the vacuum unit and pump air through the combination of a mechanical pump and a molecular pump to adjust the vacuum degree of the test chamber to 5×10 -5 Pa to minimize the interference of air molecules on electrons in the electron beam flight area and provide a good environment for the stable flight of the electron beam.

[0063] Electron beam deflection unit: Set the scanning parameters of the electron beam deflection unit. The scanning speed is 100μm / s, and the scanning step is 1μm, so that the electron beam can scan the entire Micro LED chip array area row by row to ensure accurate testing of each chip.

[0064] Electron gun parameters: Adjust the electron gun parameters so that the initial acceleration voltage of the electron beam is 5kV, the beam current intensity is 10μA, and the electron beam spot diameter is 0.5μm to ensure that the electron beam has sufficient energy and focus for testing.

[0065] S3.1 Forward current IF test

[0066] Connecting Probe: Electrically connect the probe connected to the power supply to the pin PAD. The probe is a tungsten probe with a diameter of 50μm and a contact resistance less than 1Ω to ensure good electrical connection.

[0067] Adjusting the Accelerating Voltage: Adjust the accelerating voltage of the electron beam to 7kV and the beam current to 100μA. At this time, the electron beam scans the surface of the P-pole protection metal of the chip to form positive charges. The N-pole is connected to the power supply through the redistribution line and the probe, and a forward current is generated and the Micro LED chip lights up.

[0068] Signal Collection and Analysis: The current sensor in the test unit collects the electrical signal in the circuit, with a measurement range of 0 - 100mA and an accuracy of ±0.1mA. At the same time, the photodetector collects the optical signal generated by the light emission of the Micro LED chip, with a spectral response range of 380 - 780nm and a sensitivity of 0.5A / W.

[0069] The signal analysis unit processes the collected electrical and optical signals, uses the Fourier transform algorithm to extract the frequency components of the current signal, analyzes the value of the forward current IF and related optical parameters such as luminous intensity, peak wavelength, etc., and records the test results.

[0070] S3.2 Reverse Leakage Current IR Test

[0071] Adjusting the Accelerating Voltage: Keeping other conditions unchanged, adjust the accelerating voltage of the electron beam to 10kV. Negative charges are formed on the surface of the P-pole protection metal of the chip, and a reverse leakage current IR is generated in the Micro LED chip.

[0072] Signal Collection and Analysis: The current sensor in the test unit collects the reverse leakage current electrical signal. Since the reverse leakage current is small, the measurement range of the sensor is adjusted to 0 - 1μA and the accuracy is ±1nA. The signal analysis unit analyzes and processes the reverse leakage current signal and records the value of the reverse leakage current IR.

[0073] S4, Post-Test Processing

[0074] Removing the Al Layer: Immerse the chip in a TMAH solution at 25℃ with a TMAH solution concentration of 2.38% for 15 minutes to remove the test circuit and the electrode protection metal Al. During the process, use a magnetic stirrer to stir the solution at a speed of 200r / min to ensure uniform reaction.

[0075] Removing the Photoresist: Use a photoresist remover to remove the photoresist planarization layer. Immerse the chip in the photoresist remover at 40℃ for 20 minutes, then rinse it with deionized water and dry it with nitrogen to restore the chip to its initial state.

[0076] Comparative Example

[0077] 1. Traditional probe contact testing

[0078] Testing process: Using the traditional probe contact method, the PN two electrodes of the LED chip are contacted by the probe in sequence to measure the forward current IF and the reverse leakage current IR. The probe uses a metal alloy probe with a diameter of 100μm.

[0079] Recording data: Record the test time, the wear condition of the probe, and the error range of the test results. Due to the frequent contact between the probe and the chip, the test speed is slow. The test time for each chip is about 10s. And as the number of tests increases, the probe wears significantly, and the test result error is large. The test error of the forward current can reach ±5%, and the test error of the reverse leakage current can reach ±10%.

[0080] 2. Single-mode electron beam testing

[0081] Testing operation: Use an electron beam EL testing system that can only perform single-mode testing (such as electron beam accumulation at the N pole), and measure the forward current IF of the LED chip according to its operation process. The reverse leakage current IR cannot be measured.

[0082] Comparison result: Compared with the present invention, this method has a single function, cannot comprehensively obtain the electrical performance parameters of the chip, and the test time is long. The test time for each chip is about 5s.

[0083] 3. Ion beam testing

[0084] Testing process: Adopt the testing method of ion beam scanning the chip electrodes. The ion source is an argon ion source, the ion beam energy is 10keV, and the beam current intensity is 1μA.

[0085] Result observation: Observe whether there is ion contamination on the chip electrodes during the testing process, and record the test cost (including equipment cost, consumable cost, etc.). It is found that there is obvious ion contamination on the chip electrodes, and the test cost is high. The equipment cost is about 5 million yuan, and the consumable cost for each test is about 1000 yuan, which is much higher than the testing method of the present invention.

[0086] A method for testing the electrical performance of flip-chip LEDs based on electron beam testing provided by this application has the following advantages:

[0087] 1. Low cost: Compared with the prior art that requires adding an ion gun design or performing complex re-wiring lithography process to test the reverse leakage current IR, the present invention can measure the forward current IF and the reverse leakage current IR only by simply adjusting the electron beam acceleration voltage, without additional expensive equipment or complex process, greatly reducing the test cost.

[0088] 2. High efficiency and accuracy: The electron beam has a fast scanning speed, enabling rapid completion of the testing of a large number of Micro LED chips, thereby improving the testing efficiency. At the same time, it avoids direct contact between the probe and the chip, reduces testing errors caused by contact wear, and ensures the accuracy of the testing results.

[0089] 3. Avoid contamination: Compared with the solution of using an ion beam to scan the chip electrodes, the present invention uses an electron beam for testing, which does not cause the problem of ion contamination of the chip electrodes, ensuring the quality and performance of the chips.

[0090] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. 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 method for testing the electrical properties of flip-chip LEDs based on electron beam testing, characterized in that It includes the following steps: S1. Sample pretreatment: For flip-chip or face-up Micro LED chips, a temporary material is used for planarization, and a test circuit and electrode (P electrode and N electrode) protection metal of the chip are fabricated through a photolithography evaporation process. All N electrodes within a specific area are connected together, and a pin is set at the corner of this area; S2. Test device setup: Build a test device including a vacuum unit, an electron beam deflection unit, a test unit, and a signal analysis unit; Among them, the vacuum unit is used to create an internal vacuum environment for the electron beam flight area to avoid interference of air molecules with electrons; The electron beam deflection unit is used to precisely control the electron beam to sequentially scan the entire Micro LED chip array area; The test unit includes an electron gun and a test circuit. The electron gun is used to generate an electron beam, and the test circuit is used to collect the electrical signals in the circuit when the loop is connected and the optical signals generated by the Micro LED emission; The signal analysis unit is used to analyze and process the electrical signals collected by the test unit, and then judge the relevant performance of the Micro LED chip; S3. Test operation: When the electron beam scans the electrode protection metal, by adjusting the electron beam acceleration voltage, the charge state on the surface of the P electrode protection metal of the Micro LED chip is changed to realize the test of the forward current IF and reverse leakage current IR of the Micro LED chip; S3.

1. When the electron beam acceleration voltage is adjusted to be between V1 and V2, positive charges are formed on the surface of the P electrode protection metal of the Micro LED chip. The N electrode is connected to the negative pole of the power supply through the protection metal prepared by photolithography and the probe, and a forward current IF is generated between the PN electrodes of the Micro LED chip. At this time, the forward current IF is tested, and the optical signals during the normal operation of the chip are collected simultaneously; S3.

2. When the electron beam acceleration voltage is adjusted to be lower than V1 or higher than V2, negative charges are formed on the surface of the P electrode protection metal of the Micro LED chip. The N electrode is connected to the positive pole of the power supply through the protection metal prepared by photolithography and the probe, and a reverse leakage current IR is generated between the PN electrodes of the Micro LED chip. At this time, the reverse leakage current IR is tested; S4. Post-test treatment: After the test is completed, an alkaline solution is used to remove the test circuit and electrode protection metal, and then the temporary material for planarization is removed to restore the chip to its initial state.

2. The method for testing the electrical performance of flip-chip LEDs based on electron beam testing according to claim 1, wherein: In step S1, the planarization treatment uses photoresist as the temporary material to form a planarization layer. Among them, the thickness range of the photoresist of the planarization layer is 5μm - 15μm.

3. The method for testing the electrical properties of flip-chip LEDs based on electron beam testing according to claim 1, wherein: In step S1, the materials of the test circuit and electrode protection metal are made of conductive materials, and their thickness is 0.1μm - 2μm; the size range of the pin is 1μm×1μm - 100μm×100μm.

4. The method for testing the electrical properties of flip-chip LEDs based on electron beam testing according to claim 1, wherein: The vacuum degree range of the vacuum unit is 10 -4 Pa - 10 -8 Pa.

5. The method for testing the electrical properties of flip-chip LEDs based on electron beam testing according to claim 1, wherein: In the electron beam deflection unit, the beam current intensity fluctuation range of the electron beam is controlled within ±1%, and the scanning position accuracy of the electron beam is controlled within ±0.1μm.

6. The method for testing the electrical performance of flip-chip LEDs based on electron beam testing according to claim 1, wherein: The test accuracy of the test unit for the forward current IF is ±0.5%, and the test accuracy for the reverse leakage current IR is ±1%.

7. The method for testing the electrical performance of flip-chip LEDs based on electron beam testing according to claim 1, characterized in that: When the signal analysis unit analyzes and processes the collected electrical signals, the analysis algorithms used include, but are not limited to, the Fourier transform algorithm and the wavelet analysis algorithm, which are used to extract the characteristic parameters of the current signal to judge the performance of the Micro LED chip.

8. The method for testing the electrical properties of flip-chip LEDs based on electron beam testing according to claim 1, wherein: In step S3, the value range of the electron beam acceleration voltage V1 is 3 kV - 6 kV, and the value range of the electron beam acceleration voltage V2 is 8 kV - 12 kV.

9. The method for testing the electrical properties of flip-chip LEDs based on electron beam testing according to claim 1, wherein: In step S3, the electron beam is focused into a thin beam by the electromagnetic field and deflected and scanned under the action of the electromagnetic field, sequentially irradiating the P poles of each Micro LED chip. At the same time, the N poles are connected to the power supply through the conductive material prepared by photolithography and the probes to form a loop.

10. The method for testing the electrical properties of flip-chip LEDs based on electron beam testing according to claim 1, wherein: In step S4, the alkaline solution uses TMAH or KOH solution, the treatment temperature range is 20°C - 50°C, and the treatment time range is 5 min - 20 min; the temporary material for planarization is removed by the stripping solution or other organic solvents, the treatment temperature range is 30°C - 60°C, and the treatment time range is 10 min - 30 min.

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