A multi-channel non-contact photoelectric characteristic detection device and method for micro LED chips

Abstract

This invention discloses a multi-channel non-contact photoelectric characteristic detection device and method for micro LED chips. The device includes: a laser input module for inputting multiple laser beams into a microscope; a microscope for focusing the multiple laser beams and simultaneously irradiating multiple groups of chips under test (DUTs) corresponding to a current region on a wafer; a support module, mounted on the microscope, for supporting the wafer on the objective lens imaging plane of the microscope and for moving the wafer so that the laser irradiates multiple groups of DUTs in different regions of the wafer; a data acquisition module, connected to the DUTs on the wafer via a conductive thin film, for acquiring photocurrent signals of the DUTs corresponding to each thin film array in the conductive thin film; and a spectral information analysis module for acquiring fluorescence signals of the DUTs and outputting spectral analysis data. This solution enables simultaneous excitation and detection of photoelectric signals from multiple micro LED chips, achieving non-contact photoelectric characteristic detection of batches of LED chips.

Description

Technical Field

[0001] This invention relates to the field of wafer inspection technology, specifically to a multi-channel non-contact photoelectric characteristic detection device and a multi-channel non-contact photoelectric characteristic detection method for micro LED chips. Background Technology

[0002] LED (Light Emitting Diode) is a semiconductor device that converts electricity into light. Due to its advantages such as small size, long lifespan, low power consumption, fast response speed, bright colors, and environmental friendliness, it has been widely used in display, lighting, communication, medical, biological, and security fields, becoming one of the most promising new light sources in the world today.

[0003] Before LED wafers are diced, the photoelectric properties of each chip need to be tested to determine their quality. Generally, testing methods can be divided into contact testing and non-contact testing. Contact testing methods typically involve contacting the LED chip electrodes with a probe and applying electricity, then using instruments such as a spectrometer, ammeter / voltmeter, etc., to detect the photoelectric properties. Non-contact testing methods do not require the probe to directly contact the LED chip; they generally use induction or laser excitation to make the chip emit light.

[0004] For micron-sized LED chips, the electrode size is too small, making it difficult to ensure accurate alignment of the probe with the LED chip's electrodes when using contact detection methods. This process also carries the risk of contamination or damage to the chip. Furthermore, contact detection methods are relatively slow. Existing non-contact detection technologies commonly use photoexcitation or electric field induction / coupling for LED chip photoelectric detection. For example, some non-contact detection methods utilize the photovoltaic effect of pn junctions, using modulated lasers to excite photofluorescence signals of a specific wavelength in the LED chip. These signals are then received by a sensor, ultimately extracting the defect distribution map of the tested LED sample. Alternatively, other non-contact detection methods employ inductance to extract the photocurrent generated by the LED chip's self-emission under excitation light, simultaneously capturing the chip's self-emission information to achieve LED chip detection. Alternatively, in other non-contact detection methods, a micro-electrode array can be set on a conductive planar substrate through high-frequency electric field coupling, forming coupling capacitors corresponding to the positive and negative terminals of the LED under test. The LED is then driven to light up by feeding it with an AC power source, thereby collecting luminous information and achieving non-contact detection.

[0005] When using non-contact testing methods, a photomask matching the chip size is typically fabricated and placed on top of the wafer to shield areas that do not require excitation. However, this method requires specially designed photomasks for chips of different sizes, resulting in high costs and inflexibility. In practical applications, methods using induction coils to extract excitation current are difficult to implement for batch testing of miniature LEDs due to the large size of the coils. Displacement current generated by electrically exciting LED chips via electric field coupling does not flow through the chip electrodes, failing to reflect the actual performance of the chip electrodes. Furthermore, it requires a miniature electrode array, necessitating precise alignment with the LED chip electrodes during operation, impacting efficiency and accuracy.

[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0007] This invention provides a multi-channel non-contact photoelectric characteristic detection device and a multi-channel non-contact photoelectric characteristic detection method for micro LED chips, which can effectively overcome the defects existing in the prior art.

[0008] Other features and advantages of the invention will become apparent from the following detailed description, or may be learned in part by practice of this disclosure.

[0009] According to a first aspect of the present invention, a multi-channel non-contact photoelectric characteristic detection device for a micro LED chip is provided, the device comprising:

[0010] The laser input module is used to input multiple laser beams into the microscope;

[0011] A microscope is used to focus multiple laser beams and simultaneously illuminate multiple sets of chips under test corresponding to the current area on a wafer;

[0012] The support module is movably mounted on the microscope and is used to support the wafer on the imaging plane of the microscope objective lens. The wafer can be moved so that the laser can irradiate multiple sets of chips under test in different areas of the wafer.

[0013] The data acquisition module is connected to the chip under test on the wafer through a conductive thin film and is used to acquire the photocurrent signal of the chip under test corresponding to each thin film array in the conductive thin film.

[0014] The spectral information analysis module is used to acquire the fluorescence signal of the chip under test and output the spectral analysis data corresponding to the fluorescence signal; wherein, the fluorescence signal is the light signal of the chip under test after being excited by laser and returning along the original laser optical path.

[0015] In some exemplary embodiments, the laser input module includes:

[0016] A laser, used to emit laser light;

[0017] A beam expander is used to expand the laser beam emitted by a laser device.

[0018] A digital micromirror device (DMD) is used to deflect the expanded laser beam and output multiple parallel laser beams to a microscope; each laser beam corresponds one-to-one with multiple sets of chips under test in the current area of ​​the wafer.

[0019] In some exemplary embodiments, the bearer module includes:

[0020] A wafer tray is used to hold a conductive thin film and place a wafer on the conductive thin film; wherein the conductive thin film is in close contact with the electrode pins of the chip under test on the wafer;

[0021] A three-dimensional stage is movably mounted on the microscope to support the wafer tray and moves the wafer tray when the three-dimensional stage is moved, so that multiple laser beams can irradiate different areas on the wafer.

[0022] The ejector pin, with its bottom fixed to the base and its top penetrating the three-dimensional stage, is used to apply pressure to the wafer tray;

[0023] A base is mounted on the microscope.

[0024] In some exemplary embodiments, the data acquisition module includes: a conductive thin film, a matrix switch, and a voltmeter connected in sequence; wherein the conductive thin film is in close contact with the electrode pins of the chip under test on the wafer, for drawing out the photocurrent of the chip under test caused by laser irradiation, and measuring it using the voltmeter.

[0025] In some exemplary embodiments, the conductive thin film includes multiple thin film arrays with uniformly distributed resistance arranged in an array, and each thin film array is insulated from the others; each thin film array corresponds one-to-one with the optical path of multiple laser beams; wherein, the column electrode leads of each thin film array are respectively connected to the column electrode bus; and the row electrode leads of each thin film array are respectively connected to the matrix switch.

[0026] In some exemplary embodiments, the chip under test is a same-side structure electrode chip, and the conductive surface of the conductive film is in contact with the positive and negative electrode pins of the same-side structure electrode chip.

[0027] In some exemplary embodiments, the chip under test is a vertical structure electrode chip, with one side electrode pin contacting the lower conductive substrate and the other side electrode pin contacting the upper thin film array.

[0028] In some exemplary embodiments, the spectral information analysis module includes: a dichroic mirror, a filter, and a hyperspectral imager; wherein,

[0029] The dichroic mirror is positioned in the optical path of the expanded laser beam incident on the microscope, and is used to reflect the photoluminescence signal of the chip under test on the wafer to the filter.

[0030] The filter is used to filter out the excitation laser generated by the laser input module that propagates along the same optical path as the fluorescence signal;

[0031] A hyperspectral imager is used to perform multi-channel spectral synchronous detection of fluorescence signals after they have been filtered by filters, and to output multi-channel spectral analysis data.

[0032] According to a second aspect of the present invention, a method for multi-channel non-contact photoelectric characteristic detection of a micro LED chip is provided, using the apparatus described in any of the above embodiments, the method comprising:

[0033] The laser output module is controlled to output parallel multi-channel lasers to the microscope, and the multi-channel lasers illuminate multiple sets of chips under test corresponding to the current area of ​​the wafer on the imaging plane of the microscope objective lens.

[0034] After the chip under test is lit, the control data acquisition module measures the photocurrent signal data of the chip under test corresponding to each thin film array of the conductive thin film; and

[0035] The spectral information analysis module is used to collect the fluorescence signal of the chip under test excited by laser and output the spectral analysis data corresponding to the fluorescence signal.

[0036] In some exemplary embodiments, the method further includes:

[0037] Adjust the deflection angle of the micromirrors of the digital micromirror device in the laser output module to control the irradiation area of ​​each laser on the wafer; and / or adjust the position of the three-dimensional stage in the carrier module to move the wafer to control the irradiation area of ​​each laser on the wafer.

[0038] The multi-channel non-contact photoelectric characteristic detection device for micro LED chips provided in this invention emits multiple laser beams into a microscope via a laser input module and supports the wafer on the imaging plane of the microscope's objective lens using a carrier module, thereby achieving multi-channel synchronous excitation of multiple sets of chips under test. A data acquisition module allows the conductive thin film to directly contact the electrodes of the chip under test, drawing photocurrent from the electrodes to more accurately reflect the chip's photoelectric performance. Simultaneously, it protects the electrodes of the chip under test from damage during testing, avoiding false detections caused by photocurrent not flowing through the electrodes in the coupling method. A spectral information analysis module acquires the photoluminescence information of the chip under test, enabling multi-channel synchronous photoelectric characteristic detection of the LED chips. This achieves synchronous excitation and detection of photoelectric signals from multiple micro LED chips, enabling non-contact photoelectric characteristic detection of batches of LED chips.

[0039] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0040] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0041] Figure 1 This schematic diagram illustrates a multi-channel non-contact photoelectric characteristic detection device for a micro LED chip according to an exemplary embodiment of the present invention.

[0042] Figure 2 This schematic diagram illustrates an exemplary embodiment of the present invention, showing the optical path of multiple laser beams corresponding to multiple sets of chips under test within a current area.

[0043] Figure 3 This schematic diagram illustrates a lens arrangement structure of a DMD device according to an exemplary embodiment of the present invention.

[0044] Figure 4 This schematic diagram illustrates the structure of a carrier module in an exemplary embodiment of the present invention.

[0045] Figure 5 This schematic diagram illustrates the structure of a same-side electrode chip and a conductive thin film in an exemplary embodiment of the present invention.

[0046] Figure 6 This schematic diagram illustrates the structure of a vertical electrode chip according to an exemplary embodiment of the present invention.

[0047] Figure 7 This schematically illustrates a top view of a conductive thin-film array structure using a vertically structured electrode chip in an exemplary embodiment of the present invention.

[0048] Figure 8 The diagram illustrates an equivalent circuit of a same-side electrode chip according to an exemplary embodiment of the present invention.

[0049] Figure 9 The diagram illustrates a method for detecting the multi-channel non-contact photoelectric characteristics of a micro LED chip according to an exemplary embodiment of the present invention. Detailed Implementation

[0050] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0051] Furthermore, the accompanying drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0052] To address the shortcomings and deficiencies of existing technologies, this example embodiment provides a multi-channel non-contact photoelectric characteristic detection device for micro LED chips. This device can be applied to the synchronous excitation and detection of photoelectric signals from multiple micro LED chips, enabling non-contact photoelectric characteristic detection of batch LED chips.

[0053] Specifically, the device includes: a laser input module, a microscope, a carrier module, a data acquisition module, and a spectral information analysis module. The laser input module inputs multiple laser beams into the microscope. The microscope focuses these multiple laser beams and simultaneously illuminates multiple groups of chips under test (DUTs) corresponding to the current region on the wafer. The carrier module is movably mounted on the microscope, supporting the wafer on the objective imaging plane of the microscope and allowing the wafer to be moved so that the laser illuminates multiple groups of DUTs in different regions of the wafer. The data acquisition module, connected to the DUTs on the wafer via a conductive thin film, acquires photocurrent signals from the DUTs corresponding to each thin film array in the conductive thin film. The spectral information analysis module acquires fluorescence signals from the DUTs and outputs spectral analysis data corresponding to the fluorescence signals; wherein the fluorescence signal is the light signal from the DUTs excited by the laser and returning along the original laser path.

[0054] For example, refer to Figure 1 As shown, the laser input module includes a laser 1, a beam expander 2, and a digital micromirror device 3. The laser 1 emits a laser beam; the beam expander 2 expands the laser beam emitted by the laser; and the digital micromirror device 3 deflects the expanded laser beam, outputting multiple parallel laser beams to the microscope. Each laser beam corresponds one-to-one with multiple sets of chips under test in the current region of the wafer.

[0055] In this system, laser 1 emits a laser beam, which is then expanded by beam expander 2 and enters a digital micromirror device (DMD) 3. Adjusting the deflection directions of the mirrors in the DMD allows for the formation of multiple parallel laser beams. (Reference) Figure 2 As shown, multiple laser beams are focused by the microscope objective and simultaneously illuminate multiple sets of chips under test. (Reference) Figure 3 As shown, the digital micromirror 3 contains multiple regularly arranged micromirrors 18. By rotating the micromirrors in different areas, the deflected multi-path lasers can correspond to the size and spacing of the chip under test, thereby achieving flexible multi-path laser beam splitting and synchronous excitation of the chip under test.

[0056] For example, the support module includes: a wafer tray 10, a push pin 11, a base 12, and a three-dimensional stage 13. The wafer tray 10 supports a conductive film 9 and places a wafer 8 on the conductive film 9; the conductive film 9 is in close contact with the electrode pins of the chip under test on the wafer. The three-dimensional stage 13 is movably mounted on the microscope 7, supporting the wafer tray 10, and moving the wafer tray 10 when the three-dimensional stage 13 is moved, so that multiple laser beams irradiate different areas on the wafer 8. The bottom of the push pin 11 is fixed to the base 12, and the top of the push pin 11 penetrates the three-dimensional stage 13, applying pressure to the wafer tray 10. The base 12 is mounted on the microscope.

[0057] For example, refer to Figure 4 As shown, the base 12 can be fixed to the microscope and is located directly below the lens emitting the laser. A three-dimensional platform 13 is positioned above the base. A slide rail can be installed on the side closest to the microscope body, allowing the three-dimensional platform 13 to move horizontally, backward, and vertically under the microscope lens; for example, moving in an xyz coordinate system. The middle of the three-dimensional platform 13 can be hollowed out, allowing the bottom of the ejector pin 11 to be fixed to the base 12, while the upper part of the ejector pin 11 passes through the three-dimensional platform and contacts the wafer tray 10. When the three-dimensional platform 13 is moved, the ejector pin 11 remains in place, and the wafer tray 10 moves with the three-dimensional platform 13, allowing the laser to irradiate other areas of the wafer. The ejector pin acts on the wafer tray, indirectly applying pressure to the contact points between the chip electrodes and the conductive film, ensuring a stable and reliable electrical circuit.

[0058] For example, the data acquisition module includes a conductive thin film 9, a matrix switch 14, and a voltmeter 15 connected in sequence. The conductive thin film 14 is in close contact with the electrode pins of the chip under test on the wafer 8, used to draw out the photocurrent induced by laser irradiation from the chip under test, which is then measured using the voltmeter 15.

[0059] For example, the conductive thin film 9 includes multiple thin film arrays with uniformly distributed resistance arranged in an array, and each thin film array is insulated from the others; each thin film array corresponds one-to-one with the optical path of multiple laser beams; wherein, the column electrode leads of each thin film array are respectively connected to the column electrode bus; and the row electrode leads of each thin film array are respectively connected to the matrix switch 14.

[0060] Specifically, refer to Figure 5 As shown, the thin film arrays of conductive thin film 9 are insulated from each other and have no electrical connection. The column electrode leads of each thin film array are combined to form a column electrode bus, which is connected to the matrix switch 14 and then to the voltmeter 15, respectively, along with the row electrode leads of each array. Each array forms an independent loop through its own row and column electrode leads, synchronously extracting the photocurrents excited by multiple lasers. In addition, the conductive thin film is made of conductive materials, including but not limited to conductive materials such as tin-doped indium trioxide (ITO), fluorine-doped tin oxide (FTO), and aluminum-doped zinc oxide (AZO).

[0061] For example, the spectral information analysis module includes: a two-way mirror 4, a filter 5, and a hyperspectral imager 6. The two-way mirror 4 is positioned in the optical path of the expanded laser beam incident on the microscope 7, and is used to reflect the photoluminescence signal of the chip under test on the wafer to the filter. The filter 5 is used to filter out the excitation laser generated by the laser input module that propagates along the same optical path as the fluorescence signal. The hyperspectral imager 6 is used to perform multi-channel spectral detection on the fluorescence signal filtered by the filter and output spectral analysis data.

[0062] Specifically, the hyperspectral imager 6 can be located on one side of the microscope 7, with the light-collecting direction aligned with the dichroic mirror 4 and the filter 5.

[0063] The conductive film 9 is disposed on the wafer tray 10, and the wafer 8 is placed on the conductive film 9, ensuring that the conductive film 9 is in close contact with the wafer 8 and makes contact with the LED chip electrode pins on the wafer. Furthermore, the wafer is located on the imaging plane of the microscope objective lens and is coaxially opposite to the objective lens. (Reference) Figure 2 As shown, there can be a one-to-one correspondence between multiple laser beams, multiple chips under test in the current area of ​​the wafer, and multiple thin film arrays on the conductive thin film. That is, the multiple excitation beams adjusted by the DMD illuminate the current area of ​​the wafer and correspond to the arrangement of each thin film array, with each thin film array corresponding to a laser-excited scanning area.

[0064] For example, the laser emitted by the laser is expanded by a beam expander and then enters the DMD. By adjusting the different deflection directions of the mirrors in the DMD, multiple parallel laser beams are formed. These multiple laser beams are focused by the microscope objective and simultaneously illuminate multiple groups of chips under test on the wafer. The deflection angle of the DMD mirrors can be adjusted according to the chip spacing to achieve precise focusing of the multiple laser beams. The fluorescence emitted by each chip by the laser returns along the original optical path, is reflected by a dichroic mirror, and filtered by a filter before being collected by a hyperspectral imager. Simultaneously, a voltmeter connected to a conductive thin film measures the photocurrent signal data of each chip under test.

[0065] For example, the chip under test is a same-side structure electrode chip, and the conductive surface of the conductive film is in contact with the positive and negative electrode pins of the same-side structure electrode chip.

[0066] For example, refer to Figure 5 As shown, the positive and negative electrodes of the same-side structure electrode chip 16 are both located on the same side of the chip substrate 17, and the conductive surface of the conductive film 9 is in contact with the positive and negative electrode pins of the same-side structure electrode chip 16.

[0067] For example, the chip under test is a vertical structure electrode chip, with one side electrode pin in contact with the lower conductive substrate and the other side electrode pin in contact with the upper thin film array.

[0068] For example, refer to Figure 6 As shown, the positive and negative electrodes of the vertical structure electrode chip 22 are located on opposite sides of the chip substrate. One electrode pin of the vertical structure electrode chip 22 is in contact with the lower conductive substrate 23, and the other electrode pin is in contact with the upper thin film array 24. (Reference) Figure 7 As shown, the upper thin-film array 24 is composed of multiple square thin-film arrays arranged in a regular pattern. The scanning areas of the multiple excitation optical paths after DMD adjustment correspond to each thin-film array. The lower electrode pins of all chips in the detection area of ​​each array are in contact with the lower conductive plate 23. Column electrode buses are led out from the lower conductive plate 23 and connected to the matrix switch 14, and then to the voltmeter 15. The upper thin-film arrays 24 are mutually insulated and have no electrical connection. The upper row electrode leads 25 of each array are connected to the matrix switch 14 and then to the voltmeter 15.

[0069] The device provided by this invention enables multi-channel synchronous excitation and synchronous photoelectric characteristic detection. By adjusting the beams of the DMD (Digital Micromirror) to illuminate the chip under test (DUT), the LED chip is synchronously excited due to the photoelectric effect, generating photocurrents and extracting electrical signals from the conductive thin-film array. Simultaneously, a hyperspectral imager acquires the photoluminescence information of the DUT, achieving multi-channel synchronous photoelectric characteristic detection of the LED chip. Furthermore, the DMD micromirrors can be flexibly adjusted according to the size of the DUT, ensuring that the spacing of each laser beam corresponds to the area of ​​the LED chip under test. This allows for precise adjustment of the laser spacing and synchronous excitation of the LED chip without the need for a photomask. By using a conductive thin film in direct contact with the chip electrodes, photocurrent is extracted from the electrodes, more accurately reflecting the chip's photoelectric performance. Simultaneously, it protects the LED chip electrodes from damage during testing, avoiding false detections caused by photocurrent not flowing through the electrodes in the coupling method.

[0070] This example embodiment provides a method for multi-channel non-contact photoelectric characteristic detection of micro-LED chips, which can be applied to the above-described multi-channel non-contact photoelectric characteristic detection of micro-LED chips. (Reference) Figure 9 As shown, the method includes:

[0071] Step S11: Control the laser output module to output parallel multi-channel lasers to the microscope, and make the multi-channel lasers illuminate the multiple sets of chips under test corresponding to the current area of ​​the wafer on the objective imaging plane of the microscope.

[0072] Step S12: After the chip under test is lit, the data acquisition module is controlled to measure the photocurrent signal data of the chip under test corresponding to each thin film array of the conductive thin film; and

[0073] Step S13: Use the spectral information analysis module to collect the fluorescence signal of the chip under test excited by the laser, and output the spectral analysis data corresponding to the fluorescence signal.

[0074] For example, the wafer can first be placed on a conductive thin film on a wafer tray. The laser can be adjusted to control the laser beam expansion via a beam expander and beam splitting via a DMD, so that the multiple laser beams are focused by the objective lens of a microscope and then illuminate the wafer. Each laser beam illuminates a chip under test (DUT) within a thin film array region on the conductive thin film. After the DUT is illuminated, a voltmeter sequentially measures and records the electrical signal data corresponding to each thin film array via a matrix switch. The photoluminescence signal of the DUT is then reflected by a dichroic mirror and filtered by a filter before being acquired by a hyperspectral imager. The hyperspectral imager can acquire the two-dimensional spectral information of each DUT and calculate the corresponding optical power, chromaticity, and other parameters based on the two-dimensional spectral information.

[0075] For example, the method further includes: adjusting the deflection angle of the micromirrors of the digital micromirror device in the laser output module to control the irradiation area of ​​each laser on the wafer; and / or adjusting the position of the three-dimensional stage in the carrier module to move the wafer to control the irradiation area of ​​each laser on the wafer.

[0076] For example, for the current area of ​​the wafer, the deflection direction of one or more lenses in the DMD can be adjusted to control the direction and irradiation range of each laser beam, and move to other chips under test in the current area of ​​the wafer for irradiation. The voltmeter measures and records the electrical signal data corresponding to each thin film array at this time, and at the same time, the photoluminescence information of the chip under test is obtained by using a hyperspectral imager.

[0077] In addition, the position of the wafer can be moved by controlling a movable three-dimensional stage, thereby changing the measurement area of ​​the conductive thin film on the wafer. This process is repeated until all chips under test in each area of ​​the wafer have been inspected.

[0078] For example, the photocurrent generated by the photoluminescence of an LED chip mainly flows through the conductive film between the two leads of the chip: the LED chip emits photocurrent, which flows out from the positive electrode of the LED chip, enters the conductive film through the positive electrode lead, then flows through the conductive film into the negative electrode lead, and finally returns to the negative electrode of the LED chip. The voltage signal measured by the voltmeter is the voltage value of the conductive film between the two leads of the LED chip. The equivalent circuit of this loop is as follows: Figure 8 As shown. The LED chip under test generates photocurrent under laser irradiation. Considering the influence of the chip's own pin resistance, the chip is equivalent to a series structure of an ideal constant current source and an internal resistance r, with an output photocurrent of I. LED The output voltage at both ends is U LED Effective contact resistance R of conductive thin film tR1 represents the resistance of the conductive film through which the photocurrent flows between the positive and negative electrode pins of the LED chip on the thin film; R2 represents the resistance of the conductive film between the positive pin of the LED chip and the row electrode lead on the thin film; and R3 represents the resistance of the conductive film between the negative pin of the LED chip and the column electrode lead on the thin film. The internal resistance of the voltmeter is R. v The product of the current flowing through the voltmeter and its internal resistance is the voltmeter reading U. v .

[0079] The voltage U across the LED chip LED Substituting and simplifying, we get I LED The expression is as follows:

[0080]

[0081] Comparison of orders of magnitude (R) t <<R v The above formula can be simplified to:

[0082]

[0083] Similarly, U LED The expression can be simplified to:

[0084]

[0085] Therefore, when the internal resistance of the voltmeter is much greater than the sum of the resistances of the conductive thin films between the two electrodes of the chip and their respective lead ends, i.e., R1 + R2 << R v At that time, it can be considered that:

[0086]

[0087] U LED =U v

[0088] For example, when the chip under test is a same-side electrode chip, the positive and negative electrodes of the same-side electrode chip 16 are both located on the same side of the chip substrate 17, and the conductive surface of the conductive film 9 is in contact with the positive and negative electrode pins of the same-side electrode chip 16. The ejector pin 11 applies pressure to the wafer tray 10 to ensure close contact between the chip electrodes and the conductive film 9. The wafer 8 is placed on the imaging plane below the objective lens of the microscope 7. The DMD splits the laser beam expanded by the beam expander 2 and reflects it into the microscope 7, which then focuses it onto the wafer 8 through the objective lens. To avoid the chip substrate 17 affecting the focusing of the microscope 7 and the light collection of the hyperspectral imager 6, the chip substrate 17 needs to be polished to a transparent material.

[0089] The conductive thin film 9 is composed of multiple square thin film arrays arranged in a regular pattern. The multi-path excitation light path after DMD adjustment corresponds to the arrangement of the thin film array 19, with each thin film array corresponding to a laser-excited scanning area. The conductive thin film arrays 9 are insulated from each other and have no electrical connection. The column electrode leads of each array are combined to form a column electrode bus 21, which is connected to the matrix switch 14 and then to the voltmeter 15, respectively, along with the row electrode leads 20. Each array forms an independent loop through its own row and column electrode leads, synchronously extracting the photocurrent excited by multiple lasers. The hyperspectral imager 6 is located on one side of the device, with its light-collecting direction aligned with the dichroic mirror 4 and the filter 5. The filter 5 is positioned between the dichroic mirror 4 and the hyperspectral imager 6. The filter 5 helps to filter out the excitation laser generated by the laser 1, leaving the light emission signal of the chip.

[0090] During testing, laser 1 emits a single laser beam, which is expanded by beam expander 2 and then split by DMD. The split laser beams are focused by the objective lens of microscope 7 and then irradiate the wafer 8. Each laser beam irradiates the LED chip under test within its corresponding square area of ​​thin film array 19. After the chip under test is lit, matrix switch 14 controls the row electrode leads 20 of each thin film area to be connected to voltmeter 15 in sequence, thereby measuring and recording the electrical signal data of the LED chip in each thin film array 19. The LED chip in each thin film array 19 generates photoluminescence by laser excitation. This light signal is reflected by dichroic mirror 4 and filtered by filter 5 before being captured and detected by hyperspectral imager 6.

[0091] Specifically, laser 1 emits a single laser beam, which passes through beam expander 2 to enlarge the laser spot. The expanded laser beam then passes through digital micromirror device 3, and only the laser beam illuminating the flipped micromirror 18 is reflected into microscope 7, achieving laser beam splitting. The split laser beams are focused by the objective lens of microscope 7 and then shine through transparent chip substrate 17 onto LED chips. Each laser beam illuminates the LED chip within its corresponding square area of ​​thin film array 19. Due to the photoelectric effect, the LED chip emits light and generates photocurrent. Matrix switch 14 sequentially controls the selection of each thin film array 19 with voltmeter 15, measuring and recording the electrical signal data of the LED chips within each thin film array 19. The light signal is reflected along the original optical path by dichroic mirror 4, and then filtered by filter 5 to remove the excitation light from laser 1. The optical information of the LED chips within the array area is captured and obtained by hyperspectral imager 6. Taking the detection of a chip on a square thin film in thin film array 19 as an example, multiple laser beams illuminate the chip under test, and the chip under test generates photocurrent due to the photovoltaic effect. The voltmeter 15 measures and acquires the voltage signal, which is the output voltage at both ends of the LED chip. The ratio of this voltage signal to the contact resistance of the conductive film is the photocurrent under photoluminescence of the LED chip.

[0092] For example, when the chip under test is a vertical structure electrode chip 22, the positive and negative electrodes of the vertical structure electrode chip 22 are located on both sides of the chip. One side electrode pin of the vertical structure electrode chip 22 is in contact with the lower conductive substrate 23, and the other side electrode pin is in contact with the upper thin film array 24. The upper thin film array 24 is composed of multiple square thin films arranged in a regular pattern. The scanning areas of the multiple excitation light paths after DMD adjustment correspond to each thin film array. The lower electrode pins of all chips in each array detection area are in contact with the lower conductive plate 23. A column electrode bus is led out from the lower conductive plate 23 and connected to the matrix switch 14, and then connected to the voltmeter 15. After the laser beam is split by the DMD and focused by the microscope 7, it shines through the upper thin film array 24 to illuminate the chip. The chip emits light, and the luminescence information of the chip is obtained by the hyperspectral imager 6. The electrical signal data of the chip is measured by the voltmeter 15 connected to the electrode leads. In order to avoid the device from affecting the light collection of the hyperspectral imager 6, the conductive film 9 needs to be made of transparent material to ensure the smooth focusing of the microscope 7 and the acquisition of data by the hyperspectral imager 6.

[0093] After being focused by the objective lens of microscope 7, the multi-beam lasers, after being split, illuminate the LED chip through the transparent conductive film. Each laser beam illuminates the LED chip within its corresponding square area of ​​the upper thin-film array 24. The light signal generated by the chip in the array area travels along the original optical path through the transparent conductive film, then through the dichroic mirror 4 and filter 5, and is captured by the hyperspectral imager 6 to obtain the optical information of the LED chip in the array area. Taking the chip under one square film of the upper thin-film array 24 as an example, when the multi-beam laser illuminates the chip under test, the chip under test generates a photocurrent due to the photovoltaic effect. At this time, the voltmeter 15 measures and obtains the voltage signal, which is the output voltage at both ends of the LED chip. The ratio of this voltage signal to the contact resistance of the conductive film is the photocurrent under photoluminescence of the LED chip.

[0094] This disclosure provides an apparatus and method for multi-channel non-contact photoelectric characteristic detection of micro LED chips. The digital micromirror device can be adjusted according to the size and spacing of the chip under test (DUT), ensuring that each laser beam corresponds to a region of the DUT, thus achieving simultaneous excitation of the LED chip by multiple laser beams. By using a conductive thin film instead of test electrodes, after the LED chip generates photocurrent due to the photoelectric effect, the photocurrent flows into the conductive thin film. The electrical signal data of the DUT within each thin film array is measured using a voltmeter, improving detection efficiency while protecting the chip electrodes. Simultaneously, by combining this with a hyperspectral imager to acquire the optical information of the light-emitting chip, the simultaneous excitation and parallel detection of multiple photoelectric signals of the LED chip are ultimately achieved, significantly improving the accuracy of chip detection.

[0095] It should be noted that the above figures are merely illustrative of the processes included in the method according to exemplary embodiments of the present invention, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Furthermore, it is readily understood that these processes may, for example, be executed synchronously or asynchronously in multiple modules.

[0096] It should be noted that although several modules or units for the device used to perform actions have been mentioned in the detailed description above, this division is not mandatory. In fact, according to embodiments of this disclosure, the features and functions of two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided and embodied by multiple modules or units.

[0097] In particular, according to embodiments of the present invention, the processes described below with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a storage medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via the communication portion of an electronic device, and / or installed from a removable medium. When the computer program is executed by the central processing unit (CPU) of the electronic device, it performs various functions defined in the system of this application.

[0098] Specifically, the aforementioned electronic devices can be smart mobile electronic devices such as mobile phones, tablets, or laptops. Alternatively, the aforementioned electronic devices can also be smart electronic devices such as desktop computers.

[0099] It should be noted that the storage medium shown in the embodiments of the present invention can be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable storage medium can be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, optical fiber, portable compact disc read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In the present invention, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In the present invention, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, wherein computer-readable program code is carried. Such transmitted data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. The computer-readable signal medium can also be any storage medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the storage medium can be transmitted using any suitable medium, including but not limited to wireless, wired, etc., or any suitable combination thereof.

[0100] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0101] The units described in the embodiments of the present invention can be implemented in software or hardware, and the described units can also be located in a processor. The names of these units do not necessarily limit the specific unit itself.

[0102] It should be noted that, as another aspect, this application also provides a storage medium, which may be included in an electronic device or may exist independently without being assembled into the electronic device. The aforementioned storage medium carries one or more programs, which, when executed by an electronic device, cause the electronic device to perform the methods described in the following embodiments. For example, the electronic device may perform... Figure 1 The monitoring method shown includes each step.

[0103] In one embodiment, this application provides a computer program product including a computer program that, when executed by a processor, implements the steps in the above-described method embodiments.

[0104] Furthermore, the above-described figures are merely illustrative of the processes included in the method according to exemplary embodiments of the present invention and are not intended to be limiting. It is readily understood that the processes illustrated in the above-described figures do not indicate or limit the temporal order of these processes. Furthermore, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0105] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

[0106] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A multi-channel non-contact photoelectric characteristic detection device for micro LED chips, characterized in that, The device includes: The laser input module is used to input multiple laser beams into the microscope; A microscope is used to focus multiple laser beams and simultaneously illuminate multiple sets of chips under test corresponding to the current area on a wafer; The carrier module, mounted on the microscope, is used to carry the wafer on the imaging plane of the microscope's objective lens and move the wafer so that the laser irradiates multiple sets of chips under test in different areas of the wafer. The data acquisition module is connected to the chip under test on the wafer through a conductive thin film and is used to acquire the photocurrent signal of the chip under test corresponding to each thin film array in the conductive thin film. The spectral information analysis module is used to acquire the fluorescence signal of the chip under test and output the spectral analysis data corresponding to the fluorescence signal; wherein, the fluorescence signal is the light signal of the chip under test after being excited by laser and returning along the original laser optical path.

2. The apparatus according to claim 1, characterized in that, The laser input module includes: A laser, used to emit laser light; A beam expander is used to expand the laser beam emitted by a laser device. Digital micromirror devices are used to deflect the expanded laser beam and output multiple parallel laser beams to the microscope; each laser beam corresponds one-to-one with multiple sets of chips under test in the current area of ​​the wafer.

3. The apparatus according to claim 1, characterized in that, The carrier module includes: A wafer tray is used to hold a conductive film and place a wafer on the conductive film; wherein the conductive film is in close contact with the electrode pins of the chip under test on the wafer; A three-dimensional stage is movably mounted on the microscope to support the wafer tray and moves the wafer tray when the three-dimensional stage is moved, so that multiple laser beams can irradiate different areas on the wafer. The ejector pin, with its bottom fixed to the base and its top penetrating the three-dimensional stage, is used to apply pressure to the wafer tray; A base is mounted on the microscope.

4. The apparatus according to claim 1, characterized in that, The data acquisition module includes a conductive thin film, a matrix switch, and a voltmeter connected in sequence; wherein the conductive thin film is in close contact with the electrode pins of the chip under test on the wafer, and is used to draw out the photocurrent of the chip under test caused by laser irradiation, and to measure it using the voltmeter.

5. The apparatus according to claim 4, characterized in that, The conductive thin film comprises multiple thin film arrays with uniformly distributed resistance arranged in an array, and each thin film array is insulated from the others; each thin film array corresponds one-to-one with the optical path of multiple laser beams; wherein, the column electrode leads of each thin film array are respectively connected to the column electrode bus; and the row electrode leads of each thin film array are respectively connected to the matrix switch.

6. The apparatus according to claim 4, characterized in that, The chip under test is a same-side electrode chip, and the conductive surface of the conductive film is in contact with the positive and negative electrode pins of the same-side electrode chip.

7. The apparatus according to claim 4, characterized in that, The chip under test is a vertical structure electrode chip, with one side of the electrode pins in contact with the lower conductive substrate and the other side of the electrode pins in contact with the upper thin film array.

8. The apparatus according to claim 1, characterized in that, The spectral information analysis module includes: a dichroic mirror, a filter, and a hyperspectral imager; wherein... The dichroic mirror is positioned in the optical path of the expanded laser beam incident on the microscope, and is used to reflect the photoluminescence signal of the chip under test on the wafer to the filter. The filter is used to filter out the excitation laser generated by the laser input module that propagates along the same optical path as the fluorescence signal; A hyperspectral imager is used to perform multi-channel spectral synchronous detection of fluorescence signals after they have been filtered by filters, and to output multi-channel spectral analysis data.

9. A method for multi-channel non-contact photoelectric characteristic detection of a micro LED chip, applied to the device described in any one of claims 1-8, characterized in that, The method includes: The laser output module is controlled to output parallel multi-channel lasers to the microscope, and the multi-channel lasers illuminate multiple sets of chips under test corresponding to the current area of ​​the wafer on the imaging plane of the microscope objective lens. After the chip under test is lit, the control data acquisition module measures the photocurrent signal data of the chip under test corresponding to each thin film array of the conductive thin film; and The spectral information analysis module is used to collect the fluorescence signal of the chip under test excited by laser and output the spectral analysis data corresponding to the fluorescence signal.

10. The method according to claim 9, characterized in that, The method further includes: Adjust the deflection angle of the micromirrors of the digital micromirror device in the laser output module to control the irradiation area of ​​each laser on the wafer; and / or adjust the position of the three-dimensional stage in the carrier module to move the wafer to control the irradiation area of ​​each laser on the wafer.

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