CN118937944A - A device and method for detecting multi-channel non-contact photoelectric characteristics of micro LED chips - Google Patents

Abstract

The present invention discloses a device and method for detecting multi-channel non-contact photoelectric characteristics of micro LED chips. The device includes: a laser input module for inputting multiple laser beams into a microscope; a microscope for focusing multiple laser beams and synchronously irradiating multiple groups of chips to be tested corresponding to the current area on the wafer; a carrying module, which is arranged on the microscope and is used to carry the wafer on the objective imaging plane of the microscope, and can move the position of the wafer so that the laser irradiates multiple groups of chips to be tested in different areas of the wafer; a data acquisition module, which is connected to the chip to be tested on the wafer through a conductive film, and is used to collect data on the photocurrent signal of the chip to be tested corresponding to each film array in the conductive film; a spectral information analysis module, which is used to collect the fluorescence signal of the chip to be tested and output spectral analysis data. This scheme can realize the synchronous excitation and detection of photoelectric signals of multiple micro LED chips, and realize non-contact photoelectric characteristic detection of batch LED chips.

Description

Device and method for detecting multipath non-contact photoelectric characteristics of miniature LED chip

Technical Field

The invention relates to the technical field of wafer detection, in particular to a device and a method for detecting multipath non-contact photoelectric characteristics of miniature LED chips.

Background

An LED (LIGHT EMITTING Diode) is a semiconductor device capable of converting electricity into light. Because of the advantages of small volume, long service life, low energy consumption, high response speed, bright color, environmental protection and the like, the light source is widely applied to the fields of display, illumination, communication, medical treatment, biology, security protection and the like, and becomes one of the most potential novel light sources in the world.

The LED wafer needs to detect the optoelectronic characteristics of each chip before dicing to determine its quality. In general, detection methods can be divided into: contact detection and non-contact detection. The contact detection method is to make contact with the electrode of the LED chip through a probe and then detect the photoelectric characteristics by using a spectrometer, a current/voltage meter and other instruments. The non-contact detection method does not need a probe to directly contact the LED chip, and the chip is generally excited to emit light by induction or laser.

For micro-scale-sized micro LED chips, because the electrode size is too small, when a contact detection method is used, in the process of electrifying the LED chips by using a traditional probe, the accurate alignment of the probe to the electrode of the LED chips is difficult to ensure, and meanwhile, the process has the risk of polluting or damaging the chips. In addition, the speed of the chip detected by the contact detection method is low. In the existing non-contact detection technology, the photoelectric detection of the LED chip is usually carried out by a light excitation or electric field induction/coupling mode. For example, in some non-contact detection methods, the LED chip may be irradiated with laser light to excite a photo-fluorescent signal with a certain wavelength according to the photovoltaic effect of the p-n junction, and the photo-fluorescent signal is received by the sensor, so as to extract a defect distribution diagram of the tested LED sample. Or in other non-contact detection methods, the self-luminous information of the chip can be captured simultaneously by leading out the photo-generated current generated by the self-luminous of the LED chip under the excitation light through induction coil mutual inductance, so that the detection of the LED chip is realized. Or in other non-contact detection methods, a microelectrode array is arranged on the conductive plane substrate in a high-frequency electric field coupling mode, coupling capacitors are respectively formed corresponding to the positions of the positive electrode and the negative electrode of the LED to be detected, and the LED is driven to be lightened in a mode of feeding power to the LED through an alternating current power supply, so that luminous information is collected to realize non-contact detection.

When using a non-contact inspection method, a mask is typically placed on top of the wafer to mask areas that do not need to be excited, which is fabricated to match the chip size. However, such a method requires a special design of the corresponding mask when facing different sized chips, which is costly and inflexible. In the practical application process, the excitation current is LED out through the induction coil, and the volume of the induction coil is large, so that batch test of the miniature LED is difficult to realize. The displacement current for electrically exciting the LED chip in the electric field coupling mode does not flow through the chip electrode, the actual performance of the chip electrode cannot be reflected, the microelectrode array is required to be arranged, and the displacement current and the LED chip electrode are required to be accurately aligned during operation, so that the efficiency and the accuracy are affected.

It should be noted that the information disclosed in the above background section is only for enhancing understanding of the background of the invention and thus may include information that does not form the prior art that is already known to those of ordinary skill in the art.

Disclosure of Invention

The invention provides a multipath non-contact photoelectric characteristic detection device of a miniature LED chip, and a multipath non-contact photoelectric characteristic detection method of the miniature LED chip, which can effectively overcome the defects in the prior art.

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

According to a first aspect of the present invention, there is provided a micro LED chip multi-path non-contact photoelectric characteristic detection device, the device comprising:

The laser input module is used for inputting a plurality of laser beams to the microscope;

The microscope is used for focusing a plurality of laser beams and synchronously irradiating a plurality of groups of chips to be tested corresponding to the current area on the wafer;

The bearing module is movably arranged on the microscope and is used for bearing the wafer on an objective imaging plane of the microscope and moving the position of the wafer so that laser irradiates a plurality of groups of chips to be tested in different areas of the wafer;

The data acquisition module is connected with the chip to be detected on the wafer through the conductive film and is used for acquiring data of photocurrent signals of the chip to be detected corresponding to each film array in the conductive film;

The spectrum information analysis module is used for collecting fluorescent signals of the chip to be detected and outputting spectrum analysis data corresponding to the fluorescent signals; the fluorescence signal is an optical signal which is returned along the original laser path after the chip to be detected is excited by laser.

In some exemplary embodiments, the laser input module includes:

the laser is used for emitting laser;

The beam expander is used for expanding the laser emitted by the laser;

A digital micromirror device (Digital Micromirror Device, DMD) for deflecting the expanded laser beam in a direction and outputting a plurality of parallel laser beams to a microscope; wherein, each laser corresponds to a plurality of groups of chips to be tested in the current area of the wafer one by one.

In some exemplary embodiments, the carrier module includes:

The wafer tray is used for bearing the conductive film and placing a wafer on the conductive film; wherein; the conductive film is tightly contacted with electrode pins of the chip to be tested on the wafer;

The three-dimensional objective table is movably arranged on the microscope and is used for bearing the wafer tray and driving the wafer tray to move when the three-dimensional objective table is moved so as to irradiate a plurality of laser beams to different areas on a wafer;

The bottom of the thimble is fixed on the base, and the top of the thimble penetrates through the three-dimensional objective table and is used for applying pressure to the wafer tray;

And the base is arranged on the microscope.

In some exemplary embodiments, the data acquisition module includes: the conductive film, the matrix switch and the voltmeter are connected in sequence; the conductive film is closely contacted with electrode pins of the chip to be measured on the wafer, and is used for leading out photocurrent of the chip to be measured caused by laser irradiation and measuring by utilizing a voltmeter.

In some exemplary embodiments, the conductive film includes a plurality of film arrays with uniformly distributed resistors arranged in an array, and the film arrays are insulated from each other; each thin film array corresponds to the light paths of a plurality of laser beams one by one; wherein, the column electrode leads of each film array are respectively connected with the column electrode bus; the row electrode leads of each thin film array are respectively connected with the matrix switch.

In some exemplary embodiments, the chip to be tested is a same-side structure electrode chip, and the conductive surface of the conductive film is in contact with positive and negative electrode pins of the same-side structure electrode chip.

In some exemplary embodiments, the chip to be tested is a vertical structure electrode chip, one side electrode pin of the vertical structure electrode chip is in contact with the underlying conductive substrate, and the other side electrode pin is in contact with the upper thin film array.

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

The two-direction mirror is arranged in the light path of the laser after beam expansion, which is incident to the microscope and is used for reflecting photoluminescence signals of the chip to be tested on the wafer to the optical filter;

The optical filter is used for filtering excitation laser generated by the laser input module and transmitted by the same optical path as the fluorescent signal;

And the hyperspectral imager is used for carrying out multi-path spectrum synchronous detection on the fluorescent signals filtered by the optical filters and outputting multi-path spectrum analysis data.

According to a second aspect of the present invention, there is provided a method for detecting multipath non-contact photoelectric characteristics of a micro LED chip, using the apparatus according to any one of the above embodiments, the method comprising:

controlling a laser output module to output parallel multipath lasers to a microscope, and enabling the multipath lasers to irradiate a plurality of groups of chips to be tested corresponding to the current area of the wafer on an objective imaging plane of the microscope;

After the chip to be tested is lightened, the control data acquisition module measures photocurrent signal data of the chip to be tested corresponding to each film array of the conductive film; and

And collecting fluorescent signals excited by the laser of the chip to be tested by utilizing the spectrum information analysis module, and outputting spectrum analysis data corresponding to the fluorescent signals.

In some exemplary embodiments, the method further comprises:

The deflection angle of a micro lens of a digital micro lens device in the laser output module is regulated so as to control each path of laser to irradiate an area of a wafer; and/or adjusting the position of the three-dimensional object stage in the bearing module to be used for moving the wafer so as to control the irradiation area of each path of laser on the wafer.

According to the multichannel non-contact photoelectric characteristic detection device for the miniature LED chips, provided by the embodiment of the invention, the laser input module is arranged to emit a plurality of laser beams into the microscope, and the bearing module is used for bearing the wafer on the imaging plane of the objective lens of the microscope, so that multichannel synchronous excitation of a plurality of groups of chips to be detected is realized. Through setting up data acquisition module for conductive film and the electrode direct contact of awaiting measuring the chip, draw forth photocurrent from the electrode, thereby embody the photoelectricity performance of chip more accurately, the protection awaits measuring the chip electrode and not being damaged simultaneously in the test process, avoid coupling mode photocurrent not to flow through the false detection that the electrode produced. And meanwhile, the photoluminescence information of the chip to be tested is obtained by utilizing the spectrum information analysis module, so that the multipath synchronous photoelectric characteristic detection of the LED chip is realized. Therefore, synchronous excitation and synchronous detection of photoelectric signals of the multipath miniature LED chips are realized, and non-contact photoelectric characteristic detection of the batch LED chips is realized.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the disclosure and together with the description, serve to explain the principles of the disclosure. It will be apparent to those of ordinary skill in the art that the drawings in the following description are merely examples of the disclosure and that other drawings may be derived from them without undue effort.

Fig. 1 schematically illustrates a schematic diagram of a micro LED chip multi-channel non-contact photoelectric characteristic detection device according to an exemplary embodiment of the present invention;

Fig. 2 schematically illustrates a schematic optical path diagram of multi-path laser corresponding to irradiation of multiple groups of chips to be tested in a current area according to an exemplary embodiment of the present invention;

Fig. 3 schematically illustrates a schematic diagram of a mirror arrangement of a DMD device in accordance with an exemplary embodiment of the present invention;

fig. 4 schematically shows a structural schematic of a load bearing module in an exemplary embodiment of the invention;

fig. 5 schematically illustrates a schematic structural diagram of an electrode chip and a conductive film with a same side structure in an exemplary embodiment of the present invention;

fig. 6 schematically illustrates a schematic structure of a vertical structure electrode chip in an exemplary embodiment of the present invention;

FIG. 7 schematically illustrates a top view of an array of conductive thin films using a vertical structure electrode chip in an exemplary embodiment of the invention;

Fig. 8 schematically illustrates an equivalent circuit diagram of an electrode chip with a same-side structure in an exemplary embodiment of the present invention;

fig. 9 schematically illustrates a method for detecting multipath non-contact photoelectric characteristics of a micro LED chip according to an exemplary embodiment of the present invention.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings. However, the exemplary embodiments may be embodied in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example 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.

Furthermore, the drawings are merely schematic illustrations of the present disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus a repetitive description thereof will be omitted. Some of the block diagrams shown in the figures are functional entities and do not necessarily correspond to physically or logically separate entities. These functional entities may be implemented in software or in one or more hardware modules or integrated circuits or in different networks and/or processor devices and/or microcontroller devices.

Aiming at the defects and shortcomings of the prior art, the embodiment provides the multichannel non-contact photoelectric characteristic detection device for the miniature LED chips, which can be applied to synchronous excitation and synchronous detection of photoelectric signals of the multichannel miniature LED chips and realize non-contact photoelectric characteristic detection of batch LED chips.

Specifically, the device comprises: the system comprises a laser input module, a microscope, a bearing module, a data acquisition module and a spectrum information analysis module. The laser input module is used for inputting a plurality of laser beams to the microscope. The microscope is used for focusing a plurality of laser beams and synchronously irradiating a plurality of groups of chips to be tested corresponding to the current area on the wafer. The bearing module is movably arranged on the microscope and is used for bearing the wafer on an objective imaging plane of the microscope and moving the position of the wafer so that laser irradiates a plurality of groups of chips to be tested in different areas of the wafer. The data acquisition module is connected with the chip to be detected on the wafer through the conductive film and is used for acquiring data of photocurrent signals of the chip to be detected corresponding to each film array in the conductive film. The spectrum information analysis module is used for collecting fluorescent signals of the chip to be detected and outputting spectrum analysis data corresponding to the fluorescent signals; the fluorescence signal is an optical signal which is returned along the original laser path after the chip to be detected is excited by laser.

Illustratively, referring to fig. 1, the laser input module includes: a laser 1, a beam expander 2 and a digital micromirror device 3. Wherein the laser 1 is used for emitting laser light; the beam expander 2 is used for expanding the laser emitted by the laser; the digital micro-mirror device 3 is used for deflecting the laser after beam expansion in the direction and outputting a plurality of parallel lasers to a microscope; wherein, each laser corresponds to a plurality of groups of chips to be tested in the current area of the wafer one by one.

The laser 1 emits laser, the laser enters a Digital Micromirror Device (DMD) 3 after being expanded by a beam expander 2, and multiple parallel outgoing lasers can be formed by adjusting different deflection directions of each lens of the DMD, and as shown in fig. 2, multiple lasers are focused by a microscope objective and synchronously irradiate multiple groups of chips to be tested. Referring to fig. 3, the digital micromirror 3 includes a plurality of regularly arranged micromirrors 18, and by rotating the micromirrors in different areas, the deflected multiple laser beams can be corresponding to the size and the distance of the chip to be tested, so as to realize flexible laser multiplexing and synchronous excitation of multiple laser beams of the chip to be tested.

Illustratively, the load bearing module includes: the wafer tray 10, the thimble 11, the base 12 and the three-dimensional object stage 13, wherein the wafer tray 10 is used for bearing the conductive film 9 and placing the wafer 8 on the conductive film 9; wherein; the conductive film 9 is closely contacted with electrode pins of the chip to be tested on the wafer. The three-dimensional objective table 13 is movably disposed on the microscope 7, and is configured to carry the wafer tray 10, and drive the wafer tray 10 to move when the three-dimensional objective table 13 is moved, so that multiple laser beams irradiate different areas on the wafer 8. The bottom of the thimble 11 is fixed on the base 12, and the top of the thimble 11 penetrates through the three-dimensional objective table 13, so as to apply pressure to the wafer tray 10. A base 12 is provided on the microscope.

For example, referring to fig. 4, the base 12 may be fixed to the microscope and located directly below the lens from which the laser light is emitted. The three-dimensional object carrying platform 13 is arranged above the base, and one side close to the microscope main body can be provided with a sliding rail, so that the three-dimensional object carrying platform 13 can move in the left-right direction, the front-back direction and the up-down direction under the lens of the microscope; for example in an xyz coordinate system. The middle part of the three-dimensional carrying platform 13 can be in a hollowed-out design, so that the bottom of the thimble 11 is fixed on the base 12, and the upper part of the thimble 11 passes through the three-dimensional carrying platform and contacts with the wafer tray 10. When the three-dimensional carrying platform 13 is moved, the ejector pins 11 keep the position unchanged, and the wafer tray 10 moves along with the three-dimensional carrying platform 13, so that laser can irradiate on other areas of the wafer. The thimble acts on the wafer tray, and indirectly applies pressure to the contact part of the chip electrode and the conductive film, so that the chip electrode and the conductive film are contacted to form a stable and reliable electric loop.

Illustratively, the data acquisition module includes: the conductive film 9, the matrix switch 14 and the voltmeter 15 are connected in this order. The conductive film 14 is in close contact with an electrode pin of the chip to be tested on the wafer 8, and is used for extracting photocurrent of the chip to be tested caused by laser irradiation and measuring by using the voltmeter 15.

The conductive film 9 includes a plurality of film arrays with uniformly distributed resistors arranged in an array, and the film arrays are insulated from each other; each thin film array corresponds to the light paths of a plurality of laser beams one by one; wherein, the column electrode leads of each film array are respectively connected with the column electrode bus; the row electrode leads of each thin film array are connected to matrix switch 14.

Specifically, referring to fig. 5, the thin film arrays of the conductive thin films 9 are insulated from each other and are not electrically connected. The column electrode leads of each thin film array are collected to form a column electrode bus, and the column electrode bus and the row electrode leads of each array are respectively connected to a matrix switch 14 and then connected to the voltmeter 15. Each array forms an independent loop through respective row-column electrode leads, and synchronously leads out photocurrents excited by multiple laser. In addition, the conductive thin film is made of a conductive material including, but not limited to, tin-doped Indium Trioxide (ITO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO).

Illustratively, the spectral information analysis module includes: a dichroic mirror 4, a filter 5, and a hyperspectral imager 6. The dichroic mirror 4 is arranged in a light path of the laser after beam expansion, which is incident to the microscope 7, and is used for reflecting photoluminescence signals of a chip to be tested on the wafer to the optical filter; the optical filter 5 is used for filtering excitation laser generated by the laser input module and transmitted by the same optical path as the fluorescent signal; the hyperspectral imager 6 is used for carrying out multi-path spectrum detection on the fluorescence signal filtered by the optical filter, and outputting spectrum analysis data.

Specifically, the hyperspectral imager 6 may be located on one side of the microscope 7, and the lighting direction is aligned with the dichroic mirror 4 and the optical filter 5.

The conductive film 9 is disposed on the wafer tray 10, the wafer 8 is placed on the conductive film 9, and the conductive film 9 is tightly attached to the wafer 8 and contacts with the electrode pins of the LED chip on the wafer. And the wafer is positioned on the imaging plane of the microscope objective lens and coaxially opposite to the objective lens. Referring to fig. 2, there may be a one-to-one correspondence between multiple lasers, multiple chips to be tested in the current area of the wafer, and multiple thin film arrays on the conductive thin film. That is, the multiple paths of excitation light paths adjusted by the DMD illuminate the current area of the wafer and correspond to the arrangement and distribution of the thin film arrays, each thin film array corresponding to a scanning area for laser excitation.

The laser emitted by the laser enters the DMD after being expanded by the beam expander, and forms a plurality of parallel emergent lasers by adjusting different deflection directions of each lens of the DMD, and the plurality of laser groups are focused by the microscope objective and synchronously irradiate a plurality of groups of chips to be tested on the wafer. The deflection angle of the DMD lens can be adjusted according to the chip spacing so as to realize the precise focusing of multiple paths of lasers. The fluorescence of each path of chip excited by the laser returns along the original light path, and the fluorescence information of each path of chip to be detected is collected by the hyperspectral imager after being reflected by the dichroic mirror and filtered by the optical filter. Meanwhile, a voltmeter connected with the conductive film measures photocurrent signal data of each path of chip to be measured.

The chip to be tested is an electrode chip with the same-side structure, and the conductive surface of the conductive film is in contact with the positive electrode pin and the negative electrode pin of the electrode chip with the same-side structure.

For example, referring to fig. 5, the positive and negative electrodes of the electrode chip 16 are 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 electrode chip 16.

The chip to be tested is a vertical electrode chip, and one electrode pin of the vertical electrode chip is contacted with the lower conductive substrate, and the other electrode pin of the vertical electrode chip is contacted with the upper thin film array.

For example, referring to fig. 6, the positive and negative electrodes of the vertical structure electrode chip 22 are located on both sides of the chip substrate, and one electrode lead of the vertical structure electrode chip 22 is in contact with the lower conductive substrate 23 and the other electrode lead is in contact with the upper thin film array 24. Referring to fig. 7, the upper thin film array 24 is formed by regularly arranging a plurality of square thin film arrays, and a scanning area of a plurality of excitation light paths adjusted by the DMD corresponds to each thin film array. The lower electrode pins of all chips in each array detection area are contacted with the lower conductive plate 23, and the column electrode bus led out of the lower conductive plate 23 is connected into the matrix switch 14 and then connected with the voltmeter 15. The upper thin film arrays 24 are insulated from each other and are not electrically connected. The upper row electrode leads 25 of each array are connected to the matrix switch 14 and then to the voltmeter 15.

The device provided by the invention can realize multipath synchronous excitation and synchronous photoelectric characteristic detection. Each path of laser after the DMD is used for adjusting beam splitting irradiates the chip to be tested, the LED chip generates photocurrent due to the multi-path synchronous excitation of photoelectric effect, and an electric signal is LED out from the conductive film array; meanwhile, photoluminescence information of the chip to be detected is obtained through a hyperspectral imager, and multi-channel synchronous photoelectric characteristic detection of the LED chip is realized. In addition, the DMD micro-mirror can be flexibly adjusted according to the size of the chip to be tested, so that the distance between each path of laser corresponds to the area of the LED chip to be tested, the accurate adjustment of the distance between multiple paths of laser is realized, the LED chip is excited synchronously, and a photomask is not required to be designed. The conductive film is in direct contact with the chip electrode, and photocurrent is LED out from the electrode, so that the photoelectric performance of the chip is more accurately reflected, the LED chip electrode is protected from being damaged in the testing process, and false detection caused by that the photocurrent in a coupling mode does not flow through the electrode is avoided.

In this exemplary embodiment, a method for detecting multiple paths of non-contact photoelectric characteristics of a micro LED chip is provided, and the method can be applied to the detection of multiple paths of non-contact photoelectric characteristics of a micro LED chip. Referring to fig. 9, the method includes:

Step S11, controlling a laser output module to output parallel multipath lasers to a microscope, and enabling the multipath lasers to irradiate a plurality of groups of chips to be tested corresponding to the current area of a wafer on an objective imaging plane of the microscope;

Step S12, after the chip to be tested is lightened, controlling a data acquisition module to measure photocurrent signal data of the chip to be tested corresponding to each film array of the conductive film; and

And S13, collecting fluorescent signals excited by laser of the chip to be tested by utilizing a spectrum information analysis module, and outputting spectrum analysis data corresponding to the fluorescent signals.

For example, the wafer may be first placed on the conductive film of the wafer tray, and the laser may be adjusted to control the beam expansion and the DMD beam splitting of the laser beam by the beam expander, so that the multiple paths of laser beams after beam splitting are focused by the objective lens of the microscope and then irradiate the wafer, and each path of laser beam irradiates the chip to be tested in a film array area on the conductive film. After the chip to be tested is lightened, the electric signal data corresponding to each film array are sequentially measured and recorded by a voltmeter through a matrix switch; after the photoluminescence signals of the chip to be detected are reflected by the dichroic mirror and filtered by the optical filter, the photoluminescence signals are obtained by a hyperspectral imager. The hyperspectral imager can collect two-dimensional spectrum information of each chip to be detected, and calculate corresponding parameters such as optical power, chromaticity and the like according to the two-dimensional spectrum information.

Illustratively, the method further comprises: the deflection angle of a micro lens of a digital micro lens device in the laser output module is regulated so as to control each path of laser to irradiate an area of a wafer; and/or adjusting the position of the three-dimensional object stage in the bearing module to be used for moving the wafer so as to control the irradiation area of each path of laser on the wafer.

For example, for the current area of the wafer, the deflection direction of one or more lenses in the DMD may be adjusted, so as to control the direction and irradiation range of each beam splitting laser, and the other chips to be measured moving to the current area of the wafer are irradiated, and the voltmeter sequentially measures and records the electrical signal data corresponding to each thin film array at this time, and simultaneously obtains the photoluminescence information of the chips to be measured at this time by using the hyperspectral imager.

In addition, the three-dimensional object stage can be controlled to move to realize the movement of the position of the wafer, and the measuring area of the conductive film on the wafer is changed. And repeating the process until the chips to be detected in each area of the wafer are detected.

Illustratively, photocurrent generated by photoluminescence of the LED chip is mainly circulated through the conductive film between the two pins of the chip: the LED chip emits photocurrent, the photocurrent flows out from the anode of the LED chip, enters the conductive film through the anode pin, flows into the cathode pin through the conductive film, and finally returns to the cathode of the LED chip. The voltage signal obtained by the voltage meter measurement is the voltage value of the conductive film between the two electrode pins of the LED chip. The equivalent circuit of this loop is shown in fig. 8. The LED chip to be tested generates photocurrent under laser irradiation, the chip is equivalent to an ideal serial structure of a constant current source and internal resistance r by considering the influence of pin resistance of the chip, the output photocurrent is I _LED, and the output voltage at two ends is U _LED; the effective contact resistance R _t of the conductive film is the resistance value of the conductive film through which photocurrent flows between the positive electrode pin and the negative electrode pin of the LED chip on the film; the resistance value of the conductive film between the positive pin of the LED chip on the film and the contact point of the row electrode lead is R ₁, and the resistance value of the conductive film between the negative pin of the LED chip on the film and the contact point of the column electrode lead is R ₂; the internal resistance value of the voltmeter is R _v, and the product of the current flowing through the voltmeter and the internal resistance is the voltmeter voltage representation U _v.

Substituting and simplifying the voltage U _LED at two ends of the LED chip to obtain an expression of I _LED as follows:

the order of comparison (R _t＜＜R_v) can reduce the above equation to:

The expression of the same reason U _LED can be simplified as:

Therefore, when the internal resistance of the voltmeter is far greater than the sum of the resistance values of the conductive films between the two electrodes of the chip and the respective lead termination contacts, i.e., R ₁+R₂＜＜R_v, it can be considered that:

U_LED＝U_v

For example, when the chip to be tested is a same-side electrode chip, the positive and negative electrodes of the same-side electrode chip 16 are located on the same side of the chip substrate 17, and the conductive surface of the conductive film 9 contacts the positive and negative electrode pins of the same-side electrode chip 16. The thimble 11 applies pressure to the wafer tray 10 to make the chip electrode and the conductive film 9 closely contact. The wafer 8 is placed on an imaging plane below an objective lens of the microscope 7, and the DMD splits and reflects the laser beam which is expanded by the beam expander 2 and enters the microscope 7, and then the laser beam is focused on the wafer 8 through the objective lens. In order to avoid the influence of the chip substrate 17 on the focusing of the microscope 7 and the lighting of the hyperspectral imager 6, the chip substrate 17 needs to be polished to be made of transparent materials.

The conductive film 9 is formed by regularly arranging a plurality of square film arrays, the multi-path excitation light path regulated by the DMD corresponds to the arrangement distribution of the film arrays 19, and each film array corresponds to a scanning area excited by laser. The arrays of conductive films 9 are insulated from each other and are not electrically connected. 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 respective row-column electrode leads, and synchronously leads out photocurrents excited by multiple laser. Wherein the hyperspectral imager 6 is located at one side of the device and the lighting direction is aligned with the dichroic mirror 4 and the optical filter 5, and the optical filter 5 is arranged between the dichroic mirror 4 and the hyperspectral imager 6. The filter 5 is beneficial to filtering out the excitation laser light generated by the laser 1, leaving the luminescence signal of the chip.

During detection, the laser 1 emits single-beam laser, the laser is expanded by the beam expander 2 and then is split by the DMD, the split multi-path laser is focused by the objective lens of the microscope 7 and then irradiates on the wafer 8, and each path of laser irradiates the LED chips to be detected in the square area of the corresponding thin film array 19. After the chip to be tested is lightened, the matrix switch 14 is controlled to enable the row electrode lead wires 20 of the film areas to be sequentially connected with the voltmeter 15, so that the electric signal data of the LED chips in the film arrays 19 are measured and recorded; the LED chips in each thin film array 19 are excited by laser light to generate photoluminescence, and the light signals are captured and detected by the hyperspectral imager 6 after laser light is filtered by the dichroic mirror 4 and the optical filter 5.

Specifically, the laser 1 is regulated to emit single-beam laser, the laser passes through the beam expander 2, and the beam expander 2 expands laser spots; the laser beam after beam expansion passes through the digital micromirror device 3, and only the laser beam irradiated on the inverted micromirror 18 can be reflected into the microscope 7, thereby realizing laser beam splitting. After being focused by the objective lens of the microscope 7, the split multiple paths of laser light irradiates on the LED chips through the transparent chip substrate 17, and each path of laser light irradiates on the LED chips in the square area of the corresponding film array 19. Due to the photoelectric effect, the LED chip photoluminescence and generates a photocurrent. The matrix switch 14 sequentially controls the gating of each thin film array 19 and the voltmeter 15, and electric signal data of the LED chips in each thin film array 19 are measured and recorded. The light signal is reflected by the dichroic mirror 4 along the original light path, and after the excitation light of the laser 1 is filtered by the optical filter 5, the light signal is captured by the hyperspectral imager 6, and the optical information of the LED chips in the array area is obtained. Taking a chip on a square film in the detection film array 19 as an example, multiple lasers irradiate the chip to be detected, and the chip to be detected generates photocurrent due to the photovoltaic effect. The voltmeter 15 measures and obtains a voltage signal, wherein the voltage signal is the output voltage of the two ends of the LED chip, and the ratio of the voltage signal to the contact resistance of the conductive film is the photocurrent of the LED chip under photoluminescence.

For example, when the chip to be tested is the vertical structure electrode chip 22, the positive and negative electrodes of the vertical structure electrode chip 22 are located at two sides of the chip, one electrode pin of the vertical structure electrode chip 22 contacts the lower conductive substrate 23, and the other electrode pin contacts the upper thin film array 24. The upper thin film array 24 is formed by regularly arranging a plurality of square thin films, and scanning areas of a plurality of excitation light paths regulated by the DMD correspond to each thin film array. The lower electrode pins of all chips in each array detection area are contacted with the lower conductive plate 23, and the column electrode bus is led out from the lower conductive plate 23, connected to the matrix switch 14 and then connected with the voltmeter 15. The laser is focused by the DMD beam splitting and the microscope 7 and irradiates the chip through the upper layer film array 24, the chip photoluminescence is realized, the luminous information of the chip is obtained by the hyperspectral imager 6, and the electric signal data of the chip is measured by the voltmeter 15 connected with the electrode lead. In order to avoid the influence of devices on the lighting of the hyperspectral imager 6, the conductive film 9 needs to be made of transparent materials so as to ensure that the focusing of the microscope 7 and the collection of the hyperspectral imager 6 are smoothly carried out.

After being focused by an objective lens of a microscope 7, the multi-path laser after beam splitting irradiates on an LED chip through a transparent conductive film, and each path of laser irradiates on the LED chip in a square area corresponding to the upper film array 24; after the optical signals generated by the chips in the array area pass through the transparent conductive film along the original optical path, the optical information of the LED chips in the array area is captured and obtained by the hyperspectral imager 6 through the dichroic mirror 4 and the optical filter 5. Taking the chip under one square film of the upper film array 24 as an example, multiple lasers irradiate the chip to be tested, and the chip to be tested generates photocurrent due to the photovoltaic effect. At this time, the voltmeter 15 measures and obtains a voltage signal, wherein the voltage signal is the output voltage of the two ends of the LED chip, and the ratio of the voltage signal to the contact resistance of the conductive film is the photocurrent of the LED chip under photoluminescence.

According to the device and the method for detecting the multipath non-contact photoelectric characteristics of the miniature LED chip, provided by the embodiment of the disclosure, the digital micro-mirror device can be adjusted according to the size and the distance of the chip to be detected, so that each path of laser corresponds to the area of the chip to be detected, and the multipath laser synchronously excites the LED chip. By using the conductive film to replace the test electrode, after the LED chip generates photocurrent due to photoelectric effect, the photocurrent flows into the conductive film, and the electric signal data of the chip to be tested in each film array is measured by the voltmeter, so that the detection efficiency is improved while the chip electrode is protected. Meanwhile, the hyperspectral imager is combined to acquire the optical information of the light-emitting chip, so that the synchronous excitation and parallel detection of the multipath photoelectric signals of the LED chip are finally realized, and the accuracy of chip detection is remarkably improved.

It is noted that the above-described figures are only schematic illustrations of processes involved in a method according to an exemplary embodiment of the invention, and are not intended to be limiting. It will be readily appreciated that the processes shown in the above figures do not indicate or limit the temporal order of these processes. In addition, it is also readily understood that these processes may be performed synchronously or asynchronously, for example, among a plurality of modules.

It should be noted that although in the above detailed description several modules or units of a device for action execution are mentioned, such a division is not mandatory. Indeed, the features and functionality of two or more modules or units described above may be embodied in one module or unit in accordance with embodiments of the present disclosure. Conversely, the features and functions of one module or unit described above may be further divided into a plurality of modules or units to be embodied.

In particular, according to embodiments of the present application, the processes described below with reference to flowcharts may be implemented as computer software programs. For example, embodiments of the present application include a computer program product comprising a computer program loaded on a storage medium, the computer program comprising program code for performing the method shown in the flowchart. In such embodiments, the computer program may be downloaded and installed from a network via a communication portion of the electronic device, and/or installed from a removable medium. The computer program, when executed by a Central Processing Unit (CPU) of an electronic device, performs the various functions defined in the system of the application.

Specifically, the electronic device may be an intelligent mobile electronic device such as a mobile phone, a tablet computer or a notebook computer. Or the electronic device may be an intelligent electronic device such as a desktop computer.

It should be noted that, the storage medium shown in the embodiments of the present invention may be a computer readable signal medium or a computer readable storage medium, or any combination of the two. The computer readable storage medium can be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or a combination of any of the foregoing. More specific examples of the computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-Only Memory (ROM), an erasable programmable read-Only Memory (Erasable Programmable Read Only Memory, EPROM), a flash Memory, an optical fiber, a portable compact disc read-Only Memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer readable storage medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. In the present invention, however, the computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, with the computer-readable program code embodied therein. Such a propagated data signal may take any of a variety of forms, including, but not limited to, electro-magnetic, optical, or any suitable combination of the foregoing. A computer readable signal medium may also be any storage medium that is not a computer readable storage medium and that can transmit, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a storage medium may be transmitted using any appropriate medium, including but not limited to: wireless, wired, etc., or any suitable combination of the foregoing.

The flowcharts and block diagrams in the figures 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 the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams or flowchart illustration, and combinations of blocks in the block diagrams or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.

The units involved in the embodiments of the present invention may be implemented by software, or may be implemented by hardware, and the described units may also be provided in a processor. Wherein the names of the units do not constitute a limitation of the units themselves in some cases.

It should be noted that, as another aspect, the present application also provides a storage medium, which may be included in an electronic device; or may exist alone without being incorporated into the electronic device. The storage medium carries one or more programs which, when executed by an electronic device, cause the electronic device to implement the methods described in the embodiments below. For example, the electronic device may implement the various steps of the monitoring method shown in fig. 1.

In one embodiment, the present application provides a computer program product comprising a computer program which, when executed by a processor, implements the steps of the method embodiments described above.

Furthermore, the above-described drawings are only schematic illustrations of processes included in the method according to the exemplary embodiment of the present invention, and are not intended to be limiting. It will be readily appreciated that the processes shown in the above figures do not indicate or limit the temporal order of these processes. In addition, it is also readily understood that these processes may be performed synchronously or asynchronously, for example, among a plurality of modules.

Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This application is intended to cover any adaptations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.

It is to be understood that the present disclosure is not limited to the precise arrangements and instrumentalities shown in the drawings, and that various modifications and changes may be effected without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims (10)

1. A micro LED chip multipath non-contact photoelectric characteristic detection device, characterized in that the device comprises:

The laser input module is used for inputting a plurality of laser beams to the microscope;

The microscope is used for focusing a plurality of laser beams and synchronously irradiating a plurality of groups of chips to be tested corresponding to the current area on the wafer;

The bearing module is arranged on the microscope and used for bearing the wafer on an objective imaging plane of the microscope and moving the position of the wafer so that laser irradiates a plurality of groups of chips to be tested in different areas of the wafer;

The data acquisition module is connected with the chip to be detected on the wafer through the conductive film and is used for acquiring data of photocurrent signals of the chip to be detected corresponding to each film array in the conductive film;

The spectrum information analysis module is used for collecting fluorescent signals of the chip to be detected and outputting spectrum analysis data corresponding to the fluorescent signals; the fluorescence signal is an optical signal which is returned along the original laser path after the chip to be detected is excited by laser.

2. The apparatus of claim 1, wherein the laser input module comprises:

the laser is used for emitting laser;

The beam expander is used for expanding the laser emitted by the laser;

The digital micromirror device is used for deflecting the laser after beam expansion in the direction and outputting a plurality of parallel lasers to a microscope; wherein, each laser corresponds to a plurality of groups of chips to be tested in the current area of the wafer one by one.

3. The apparatus of claim 1, wherein the carrier module comprises:

The wafer tray is used for bearing the conductive film and placing a wafer on the conductive film; wherein; the conductive film is tightly contacted with electrode pins of the chip to be tested on the wafer;

The three-dimensional objective table is movably arranged on the microscope and is used for bearing the wafer tray and driving the wafer tray to move when the three-dimensional objective table is moved so as to irradiate a plurality of laser beams to different areas on a wafer;

The bottom of the thimble is fixed on the base, and the top of the thimble penetrates through the three-dimensional objective table and is used for applying pressure to the wafer tray;

And the base is arranged on the microscope.

4. The apparatus of claim 1, wherein the data acquisition module comprises: the conductive film, the matrix switch and the voltmeter are connected in sequence; the conductive film is closely contacted with electrode pins of the chip to be measured on the wafer, and is used for leading out photocurrent of the chip to be measured caused by laser irradiation and measuring by utilizing a voltmeter.

5. The device according to claim 4, wherein the conductive film comprises a plurality of film arrays with uniformly distributed resistors arranged in an array, and the film arrays are insulated from each other; each thin film array corresponds to the light paths of a plurality of laser beams one by one; wherein, the column electrode leads of each film array are respectively connected with the column electrode bus; the row electrode leads of each thin film array are respectively connected with the matrix switch.

6. The device of claim 4, wherein the chip to be tested is a ipsilateral electrode chip, and the conductive surface of the conductive film is in contact with positive and negative electrode pins of the ipsilateral electrode chip.

7. The apparatus of claim 4, wherein the chip to be tested is a vertical electrode chip, one side electrode pin of the vertical electrode chip is in contact with the underlying conductive substrate, and the other side electrode pin is in contact with the upper thin film array.

8. The apparatus of claim 1, wherein the spectral information analysis module comprises: a dichroic mirror, an optical filter, and a hyperspectral imager; wherein,

The two-direction mirror is arranged in the light path of the laser after beam expansion, which is incident to the microscope and is used for reflecting photoluminescence signals of the chip to be tested on the wafer to the optical filter;

The optical filter is used for filtering excitation laser generated by the laser input module and transmitted by the same optical path as the fluorescent signal;

And the hyperspectral imager is used for carrying out multi-path spectrum synchronous detection on the fluorescent signals filtered by the optical filters and outputting multi-path spectrum analysis data.

9. A method for detecting multipath non-contact photoelectric characteristics of a micro LED chip, applied to the device according to any one of claims 1 to 8, characterized in that the method comprises:

controlling a laser output module to output parallel multipath lasers to a microscope, and enabling the multipath lasers to irradiate a plurality of groups of chips to be tested corresponding to the current area of the wafer on an objective imaging plane of the microscope;

After the chip to be tested is lightened, the control data acquisition module measures photocurrent signal data of the chip to be tested corresponding to each film array of the conductive film; and

And collecting fluorescent signals excited by the laser of the chip to be tested by utilizing the spectrum information analysis module, and outputting spectrum analysis data corresponding to the fluorescent signals.

10. The method according to claim 9, wherein the method further comprises:

The deflection angle of a micro lens of a digital micro lens device in the laser output module is regulated so as to control each path of laser to irradiate an area of a wafer; and/or adjusting the position of the three-dimensional object stage in the bearing module to be used for moving the wafer so as to control the irradiation area of each path of laser on the wafer.