Testing equipment for testing electrical performance of LED based on electron ion beam

Abstract

The invention discloses test equipment for testing LED electrical performance based on electron ion beams. The test equipment comprises a data transmission system, a vacuum system, a computer control system, a data collecting and processing system, a power supply system, an automatic loading system, a high-precision platform system, an electron or ion optical column system and an auxiliary photoelectric test system, the computer control system is electrically connected with the data transmission system, the vacuum system, the data collecting and processing system, the power supply system, the automatic loading system, the high-precision platform system, the electron or ion optical column system and the auxiliary photoelectric test system respectively and realizes control instruction transmission; the data transmission system respectively forms a bidirectional data interaction channel with the auxiliary photoelectric test system, the data collection and processing system and the computer control system; the Mi cro LED electrical performance testing method solves the problems that a traditional probe contact type measuring method is low in testing speed, short in probe service life, prone to chip abrasion and the like, and efficient, low-cost and accurate Mi cro LED electrical performance testing is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor optoelectronic device testing, in particular to a test equipment for testing electrical performance of LED based on electron ion beam, which is especially suitable for efficient and high-precision synchronous testing of electrical and optical performance of Micro LED chips. BACKGROUND

[0002] With the rapid development of display technology, Micro LED, as the core device of the new generation of display technology, has significant advantages such as self-luminescence, high brightness, low power consumption and long service life, and is widely used in high-definition display, smart wear, AR / VR and other fields; In the mass production process of Micro LED, the electrical performance (such as forward voltage, reverse leakage current and luminous efficiency) of wafer-level chips needs to be tested point by point to screen qualified chips and analyze failure reasons.

[0003] The existing test technology mainly adopts probe contact type measurement: a micron-level probe is driven by a precision mechanical arm to contact the PN electrode of the chip, and the current and light-emitting signal are detected after applying voltage; This technology has the following defects:

[0004] Low test efficiency: a single 4-6 inch wafer can integrate millions to tens of millions of Micro LED chips, and the probe needs to be tested point by point, so the single test time is as long as several hours, which is difficult to meet the mass production demand;

[0005] Serious equipment loss: the probe diameter is usually less than 8 μm, and repeated contact can easily cause probe wear and deformation, not only increasing the cost of consumables, but also affecting the test accuracy due to poor contact;

[0006] Risk of chip damage: mechanical contact between the probe and the chip electrode may cause electrode falling off and lattice damage, reducing product yield;

[0007] Poor compatibility: for chips with different substrates (such as sapphire, Si, GaN) or packaging forms (vertical, flip-chip), the probe module needs to be replaced or the test light path needs to be adjusted, and the universality of the equipment is limited.

[0008] Electron beam / ion beam test technology has been applied in the field of semiconductor detection (such as electron beam lithography, ion beam etching) due to its non-contact and high-resolution advantages, but it has not formed a complete test system for the electrical performance of Micro LED, especially lacking an integrated design of synchronous acquisition of electrical and optical signals.

[0009] Therefore, it is an urgent need in the industry to develop a test equipment that is efficient, low-damage and compatible with multiple types of chips. SUMMARY

[0010] The application aims to provide a test device for testing electrical performance of LED based on electron ion beam, so as to solve the problems of slow test speed, short service life of probe, easy wear of chip and the like in the traditional probe contact type measurement method, overcome the defects of the existing electron beam test technology that cannot simultaneously measure forward current IF and reverse leakage current IR at low cost, and realize efficient, low-cost and accurate Micro LED electrical performance test.

[0011] To solve the above technical problems, the application adopts the technical scheme of:

[0012] A test device for testing electrical performance of LED based on electron ion beam, comprising a data transmission system, a vacuum system, a computer control system, a data collection and processing system, a power supply system, an automatic wafer loading system, a high-precision platform system, an electron or ion optical column system and an auxiliary photoelectric test system.

[0013] The computer control system serves as a core control unit and is electrically connected with the data transmission system, the vacuum system, the data collection and processing system, the power supply system, the automatic wafer loading system, the high-precision platform system, the electron or ion optical column system and the auxiliary photoelectric test system to realize transmission of control instructions.

[0014] The data transmission system forms a bidirectional data interaction channel with the auxiliary photoelectric test system, the data collection and processing system and the computer control system.

[0015] The power supply system is electrically connected with all the other systems to provide adaptive working voltage for each system.

[0016] All the execution systems feed back working state signals to the computer control system through the data transmission system.

[0017] In a preferred scheme, the electron or ion optical column system is fixed to the top of the cavity of the vacuum system, and its beam output port is in communication with the inside of the cavity; it is connected with the computer control system through a control cable to receive beam intensity, beam spot diameter and scanning path instructions; its high-voltage power supply end is connected with the high-voltage module of the power supply system; and its working enable signal is linked with the vacuum degree signal of the vacuum system, and the beam emission is started only when the vacuum degree meets the standard.

[0018] In a preferred scheme, the auxiliary photoelectric test system comprises a micro-nano probe system, an optical system, a secondary electron detector and a probe cleaning table; the micro-nano probe system and the optical system are connected with the data collection and processing system through a signal cable via the data transmission system to unidirectionally transmit electrical signals and optical signals; the secondary electron detector is bidirectionally connected with the data transmission system through an image transmission cable to transmit detection images and receive acquisition parameter instructions; and the probe cleaning table is connected with the computer control system through a driving module to receive cleaning control instructions.

[0019] In a preferred embodiment, the driving mechanism of the micro / nano probe system is connected with the position encoder signal of the high-precision platform system; when the high-precision platform system is displaced, the position encoder feeds back coordinates to the computer control system through the data transmission system, and the computer control system synchronously drives the micro / nano probe system so that the probe tip thereof keeps a preset contact state with the electrode of the LED wafer.

[0020] In a preferred embodiment, the high-precision platform system is nested in the vacuum system cavity, and the stage surface is vertically corresponding to the beam bombardment point of the electron or ion optical column system; the X / Y / Z axis driving motor thereof is connected with the computer control system through a servo controller to receive displacement control pulses; the position feedback sensor thereof forms a closed-loop feedback with the computer control system through the data transmission system; and the light transmission region thereof is coaxially corresponding to the optical system collection port of the auxiliary photoelectric testing system.

[0021] In a preferred embodiment, the mechanical arm path of the automatic loading system is corresponding to the loading port space of the vacuum system cavity, and the execution end thereof is in isolable communication with the cavity through a vacuum valve; the control unit thereof is connected with the computer control system through an industrial bus to receive loading and unloading instructions; the wafer positioning sensor thereof is connected with the stage positioning groove of the high-precision platform system to ensure that the placement deviation is less than or equal to ±5 μm.

[0022] In a preferred embodiment, the data collection and processing system comprises a signal conditioning module, an A / D conversion module and a data analysis unit; the signal conditioning module is connected with the micro / nano probe system and the optical system through the data transmission system to filter and amplify the original signal; the output end of the A / D conversion module is connected with the data analysis unit; and the data analysis unit is bidirectionally connected with the computer control system through an Ethernet to receive test parameters and feed back processing results.

[0023] In a preferred embodiment, the power supply system comprises a main power module, a high-voltage power module, a precision low-voltage module and a power supply monitoring unit; the main power module is connected with the external power grid to supply power to other modules; the high-voltage power module is connected with the electron or ion optical column system through a shielded cable to output an adjustable voltage of 0-50 kV; the precision low-voltage module outputs to each system through multiple channels to provide stable voltages of ±12 V, ±5 V and 3.3 V; and the power supply monitoring unit is connected with the computer control system through an I2C bus to transmit voltage and current parameters.

[0024] In a preferred embodiment, the vacuum system comprises a vacuum cavity, a molecular pump, a mechanical pump, a vacuum valve and a vacuum degree sensor; the molecular pump and the mechanical pump are connected with the cavity through the vacuum valve; the vacuum degree sensor is connected with the computer control system through the data transmission system to transmit vacuum degree data; and the control end of the vacuum valve is connected with the computer control system to receive switching instructions and is interlocked with the mechanical arm action of the automatic loading system.

[0025] In a preferred solution, the data transmission system adopts a hybrid architecture: an industrial Ethernet bus connects the computer control system with the automatic wafer mounting system and the high-precision platform system to transmit control instructions; a PCIe interface connects the computer control system with the data collection and processing system to transmit high-speed signals; an RS485 bus connects the computer control system with the power monitoring unit and the vacuum sensor to transmit low-voltage signals; and all lines are shielded and spatially isolated from the power supply lines.

[0026] Compared with the prior art, the beneficial effects of the present application are as follows:

[0027] The test device for testing the electrical performance of an LED based on an electron / ion beam has the following advantages:

[0028] 1. Test efficiency is improved by 3-5 times: electron / ion beam scanning is used to replace point-by-point contact of a probe, combined with an automatic wafer mounting system, and the test time of a single 6-8 inch wafer is shortened to 30-60 minutes, meeting the demand for mass production.

[0029] 2. Equipment loss is reduced by 90%: non-contact beam bombardment reduces probe wear and tear, and the probe replacement cycle is extended from 10,000 times to more than 100,000 times, reducing consumable costs.

[0030] 3. Test accuracy is improved: a secondary electron detector calibrates the position in real time (deviation <1 μm), and a signal conditioning module reduces noise (signal-to-noise ratio >80 dB), and the repeatability error of test data is <1%.

[0031] 4. Compatibility is enhanced: the high-precision platform has a light-transmitting design and an angle adjustment function, and is suitable for sapphire, Si, GaN substrates and flip-chip, vertical chip, without the need to replace the core module.

[0032] 5. Multi-function integration: electrical and optical signals are collected simultaneously, and multi-dimensional parameters such as voltage, current, luminous intensity, wavelength, etc. can be obtained in one test, reducing the test process. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the following specific embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0034] Figure 1 is a structural block diagram of a test device for testing the electrical performance of an LED based on an electron / ion beam.

[0035] Figure 2 Figure 1 is a structural schematic diagram of a test device for testing electrical performance of an LED based on an electron ion beam according to the present application;

[0036] In the figure, 1 is a computer control system; 2 is an electron or ion optical column system; 3 is an auxiliary photoelectric test system; 4 is a high-precision platform system; 5 is a vacuum system; 6 is an automatic wafer loading system; 7 is a data collection and processing system; 8 is a power supply system; and 9 is a data transmission system. DETAILED DESCRIPTION

[0037] In order to enable persons skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by persons skilled in the art without creative work should fall within the scope of protection of the present application.

[0038] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to the process, method, product or device.

[0039] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", and the like indicate the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not intended to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0040] In addition, in addition to indicating the orientation or positional relationship, the above-mentioned part of the terms can also be used to indicate other meanings, for example, the term "upper" can also be used to indicate a certain attachment relationship or connection relationship in some cases. For persons skilled in the art, the specific meaning of these terms in the present application can be understood according to the specific circumstances.

[0041] Furthermore, the terms "mounting", "arrangement", "provided with", "connected", "linked", "sleeved" should be interpreted broadly. For example, it can be fixed connection, detachable connection, or integral structure; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium, or internal communication between two devices, elements or components. The specific meaning of the above terms in the present application can be understood according to the specific circumstances by those skilled in the art.

[0042] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with embodiments.

[0043] Embodiment one

[0044] Please refer to Figure 1 The present application provides a test device for testing the electrical performance of LED based on electron / ion beam, which includes nine systems, the composition, function and connection relationship of each system are as follows:

[0045] 1, computer control system 1

[0046] As the core control unit of the device, it includes main controller (industrial CPU), motion control card, I / O interface card and human-computer interaction unit (touch screen + upper computer software). The main controller connects the motion control card and the I / O interface card through the PCI bus, realizes the multi-axis motion control and the on-off signal processing; the human-computer interaction unit is connected with the main controller through HDMI interface, supports the test parameter configuration (such as beam intensity, scanning path, signal acquisition frequency), real-time state monitoring and test result visualization display.

[0047] This system is connected with all other systems through electrical signal, and works with other systems through pre-installed control software. It is responsible for the timing linkage of all systems, including: controlling the automatic wafer loading and unloading system 6 to complete the automatic wafer loading and unloading; driving the high-precision platform system 4 to move according to the preset path, realizing the switching of different areas of the wafer; adjusting the beam size, beam spot diameter, scanning path and other parameters of the electron / ion optical column; triggering the signal collection of the auxiliary photoelectric test system 3 (such as starting the micro-nano probe and integrating sphere synchronously); receiving the feedback of the data collection and processing system 7, and adjusting the test parameters in real time (such as starting the scanning electron microscope mode calibration when the signal is found to be abnormal).

[0048] 2, electron or ion optical column system 2

[0049] Fixed on the top of the vacuum chamber, including electron gun / ion source, condenser lens, deflection coil, objective lens, deceleration electrode and diaphragm assembly; the electron / ion beam with adjustable energy (0.5-30keV) is emitted by the electron gun / ion source, focused into a beam spot with a diameter of 50-500nm by the condenser lens, the beam flow is controlled by the deflection coil to move along a preset path (such as line-by-line scanning, dot matrix scanning), the objective lens further reduces the beam spot and accurately positions it to the chip electrode, and the deceleration electrode reduces the beam energy (as low as 100eV) by applying a reverse voltage, thereby reducing the thermal effect during bombardment.

[0050] The system is connected with the motion control card of the computer control system 1 through a control cable to receive beam parameters and scanning instructions; and the high-voltage power supply end is connected with the high-voltage module of the power supply system 8 through a shielded cable to ensure stable power supply.

[0051] The system is the "test core" of the device, responsible for generating and controlling the electron / ion beam to bombard the chip. The ion optical column and the electron optical column have similar functions, and can be replaced according to the test requirements. For example, if higher bombardment energy is required or the electrode needs to be charged in reverse after bombardment, an ion beam such as He ion, Ga ion, Ar ion, etc. can be selected.

[0052] 3. Auxiliary photoelectric test system 3

[0053] It contains four components:

[0054] Micro-nano probe system: composed of a tungsten probe with a diameter of 1-5μm and a three-dimensional driving platform (accuracy ±0.1μm), the probe collects current signals by contacting the chip's N or P electrodes, and transmits the signals to the data collection and processing system 7 through a signal amplifier. It needs to be supplemented that the Micro LED wafer will use the RDL rewiring process to connect the P or N electrodes together in advance;

[0055] Optical system: composed of an integrating sphere (diameter 50-200mm), a filter wheel (containing 400-700nm band filter) and an optical fiber spectrometer, the integrating sphere is installed on the side or bottom of the vacuum chamber through an adjustable bracket, collects the light emission signals of the chip, filters them through the filter wheel, and then transmits them to the spectrometer through the optical fiber for conversion into electrical signals;

[0056] Secondary electron detector: installed inside the vacuum chamber, receives the secondary electrons generated by the beam bombardment, generates a surface image with a resolution of 10-50nm, and is used for calibrating the probe position and identifying chip defects;

[0057] Probe cleaning station: with built-in polytetrafluoroethylene cleaning pad, connected with the computer control system 1 through a driving module, regularly cleans the residual contaminants on the surface of the probe.

[0058] The system is connected with the computer control system 1 and the data collection and processing system 7 through the data transmission system 9, realizes bidirectional transmission of signals, is responsible for signal collection, calibration and probe maintenance, and is a "source end" of test data.

[0059] 4. High-precision platform system 4

[0060] Nested in the bottom of the vacuum cavity, a marble base + multi-layer motion structure is adopted, a built-in DC motor drives a ball screw, and a high-precision linear guide is used to guarantee the axial accuracy of the motion, the height and the plane inclination angle of the workpiece table are adjusted through the fine adjustment feet, X / Y axis translation (stroke 0-300mm, accuracy ±0.1μm), Z axis lifting (stroke 0-50mm, accuracy ±0.5μm) and θ axis rotation (±30°, accuracy ±0.001°) are supported; a hollow area with a diameter of 150mm or a quartz glass light transmission window (light transmission rate >90%) is arranged in the center of the platform, which is suitable for the bottom optical signal collection of flip-chip; a clamping or locking mechanism is arranged on the surface of the stage to fix the wafer and realize stable fixing of the wafer.

[0061] The driving motor of the system is connected with the motion control card of the computer control system 1 through a servo controller, and the position feedback sensor (grating ruler) feeds back coordinates to the computer in real time through the data transmission system 9 to form a closed-loop control; the motion trajectory and the beam scanning path of the electron-optical column are realized through coordinate mapping algorithm.

[0062] The system carries the wafer and realizes multi-degree-of-freedom high-precision motion (such as X / Y axis translation, Z axis lifting and θ axis rotation), and the accuracy needs to reach the level of ±0.1μm. Specific functions:

[0063] In cooperation with the scanning range of the electron / ion beam, different "test fields" (regions containing multiple chips) of the wafer are moved to the beam bombardment area in turn;

[0064] Adjust the posture according to different substrate types: when the sapphire substrate (translucent) is used, the middle of the platform is hollow or made of a light-transmitting material, which is convenient for the bottom integrating sphere to collect light; when the Si-based substrate (not translucent) is used, the platform is inclined (such as 15°), so that the integrating sphere is located above the wafer to collect light;

[0065] In cooperation with the automatic wafer loading system 6, the wafer moved by the mechanical arm is accurately received and fixed.

[0066] 5. Vacuum system 5

[0067] The vacuum system 5 includes a vacuum cavity (stainless steel material, volume 1-2m 3 ), a molecular pump (pumping speed 500-1000L / s), a mechanical pump (pumping speed 20-50L / s), a vacuum valve (pneumatic gate valve) and a vacuum degree sensor (measurement range 1×10 -7 -1×105 pa); molecular pump and mechanical pump are connected in series through vacuum pipeline, connected with the cavity through vacuum valve, realizing staged vacuumizing; vacuum degree sensor is installed on the side wall of the cavity, monitoring the vacuum environment in real time.

[0068] The valve control end of the system is connected with the I / O interface card of the computer control system 1, and the vacuumizing time sequence is controlled by the computer; the vacuum degree signal is fed back to the computer through the data transmission system 9, and when the vacuum degree reaches 1x10 -5 pa above, triggering the electron optical column system to start.

[0069] The role is: to avoid the collision between gas molecules in the air and the electron / ion beam, to ensure the stability of the beam and the bombardment accuracy; to prevent the residual gas from forming pollution on the chip surface and affecting the test accuracy; to provide a normal working environment for the electron gun, ion gun and other devices (the electron / ion beam can be effectively accelerated and focused under vacuum).

[0070] 6、Automatic wafer loading system 6

[0071] It is composed of a six-axis mechanical arm (repeat positioning accuracy ±5μm), a 6-inch wafer box (compatible with 4-12-inch wafers), and a carrier disc positioning mechanism. The mechanical arm end is provided with an electrostatic chuck; the carrier disc positioning mechanism adopts visual alignment (resolution 1μm) to ensure the alignment accuracy of the wafer and the high-precision platform.

[0072] The control unit of the system is connected with the computer control system 1 through industrial Ethernet, receiving the loading and unloading instructions; the mechanical arm movement path of the system is spatially corresponding to the loading port of the vacuum cavity (with a pneumatic sealing door), and is interlocked with the opening and closing state of the vacuum valve (only when the valve is closed, the mechanical arm can move).

[0073] The system realizes the automatic loading and unloading of wafers, including:

[0074] Mechanical arm: according to the computer instructions, it grabs the wafer from the wafer box and moves it to the carrier disc of the high-precision platform system 4; after the test is completed, it moves the wafer from the carrier disc back to the wafer box;

[0075] Carrier disc: it fixes the wafer through mechanical clamping or electrostatic chuck, ensuring the stability of the wafer position during the test, and its core role is to reduce manual intervention and improve test efficiency, adapting to the continuous test demand in mass production scenarios.

[0076] 7、Data collection and processing system 7

[0077] It includes signal conditioning module (low noise amplifier, filter), A / D conversion module (sampling rate 1-10 MHz, resolution 16 bits) and data analysis unit (GPU accelerated processor); the signal conditioning module filters and amplifies the electrical signal (0-10 mA) of the micro-nano probe and the photocurrent signal (0-10 μA) of the optical system, and after A / D conversion into digital signals, the data analysis unit processes them through algorithms (such as fast Fourier transform, peak detection) to generate parameters such as forward voltage, reverse leakage current, peak wavelength and luminous intensity.

[0078] The system is connected with the computer control system 1 through the PCIe interface, and transmits raw data and processing results in real time, supports local data storage (capacity 1 TB) and external export.

[0079] The system is responsible for signal reception, conversion and analysis; specifically including: receiving the electrical signal (such as current, voltage) transmitted by the micro-nano probe, converting it into a processable digital signal through an amplifier; receiving the optical signal (converted into an electrical signal through an optical fiber and an optical-electrical converter) transmitted by the optical system; analyzing the signal through an algorithm to generate electrical performance parameters (such as forward voltage, reverse leakage current) and optical performance parameters (such as luminous intensity, wavelength) of the chip; storing raw data and processing results to provide a basis for subsequent chip screening and failure analysis.

[0080] 8, power supply system 8

[0081] It contains a main power module (input AC 220V), a high-voltage power module (output 0-50kV, ripple <0.1%), a precision low-voltage module (output ±12V, ±5V, 3.3V, noise <1mV) and a power monitoring unit; the high-voltage module is specially designed for electronic / ion optical column power supply, the low-voltage module is for probe system, detector, servo motor and other equipment power supply, and the monitoring unit collects voltage and current data of each module in real time through I2C bus and feeds back to the computer control system 1.

[0082] The system is connected with all other systems through power supply cables to provide stable power support for all components of the equipment, and is the "energy source" for the operation of each system, with overvoltage, overcurrent and overtemperature protection functions, which automatically cut off the power supply to the corresponding module when an abnormality is detected.

[0083] Specifically including: providing high-voltage power supply for electron / ion gun (accelerating electron / ion beam); providing low-voltage DC power supply for the drive motor of the high-precision platform system 4 and the mechanical arm of the automatic film loading system 6; providing stable voltage power supply for precision devices such as signal amplifier and secondary electron detector (to avoid voltage fluctuation affecting signal accuracy); providing continuous power supply for the computer control system 1 and the data transmission system 9.

[0084] 9, data transmission system 9

[0085] The mixed transmission architecture is adopted: the industrial Ethernet (transmission rate 1 Gbps) connects the computer control system 1 and the automatic wafer loading system 6, the high-precision platform, and transmits control instructions; the PCIe 3.0 interface (transmission rate 8 Gbps) connects the computer and the data collection and processing system 7, and transmits high-speed signals; the RS485 bus (transmission rate 115200 bps) connects the computer and the power monitoring unit, the vacuum degree sensor, and transmits state parameters; all lines are designed with a shielding layer, and are kept at a distance of more than 5 cm from the power supply line to avoid electromagnetic interference.

[0086] The system is mainly responsible for data interaction between internal systems of the equipment and external data output, specifically including: transmitting the electrical signals (micro-nano probe) and optical signals (integrating sphere) collected by the auxiliary photoelectric test system 3 to the data collection and processing system 7; transmitting the instructions of the computer control system 1 (such as platform movement parameters, electron beam scanning path) to the high-precision platform 4, electron or ion optical column system 2, etc. execution system; transmitting the processed test results (such as chip electrical performance parameters, optical spectrum data) to external storage or display equipment, and the core function is to ensure the real-time and accurate flow of data between modules.

[0087] Each system works cooperatively through a "control-execution-feedback" closed loop, and the core association is as follows:

[0088] I. Control chain with computer control system 1 as the core

[0089] After the machine is turned on, the vacuum system 5 is vacuumed, and the electron / ion gun is in a preheating state; after the wafer is loaded, the computer control system 1 sends the "load wafer" instruction to the automatic wafer loading system 6 → the automatic wafer loading system 6 evacuates the loading cavity, and after the vacuum is up to standard, the mechanical hand moves the wafer to the high-precision platform system 4 → the computer controls the high-precision platform system 4 to move to the test position → after the vacuum is up to standard, the control electron / ion optical column emits beam, and triggers the auxiliary photoelectric test system 3 to collect signals → the data collection and processing system 7 feeds back the results to the computer, and if the signal is abnormal, the computer controls the secondary electron detector to start calibration observation.

[0090] II. Coordination relying on vacuum environment

[0091] The vacuum system 5 needs to complete vacuumization before the electron optical column works (otherwise the beam will be disturbed by gas); the probe of the auxiliary photoelectric test system 3 contacts the chip, and the secondary electron detection operation needs to be carried out in a vacuum environment (to avoid air affecting the signal or contaminating the chip).

[0092] III. Data flow chain

[0093] The auxiliary photoelectric test system 3 (micro-nano probe + optical system) collects the original signal, the data transmission system 9 sends the signal to the data collection and processing system 7, the processed results are fed back to the computer control system 1 through the data transmission system 9, and the computer adjusts the test parameters (such as beam size and platform position) according to the results.

[0094] IV. Support relationship between power supply and motion system

[0095] The power supply system 8 supplies power for all systems: provides high voltage for the electron optical column to generate the beam, provides power for the motors of the high-precision platform system 4 and the automatic film loading system 6, and provides stable voltage for the signal detector; the movement of the high-precision platform system 4 needs to be coordinated with the scanning path of the electron optical column (the platform movement is synchronized with the beam scanning), to ensure that each chip is accurately tested.

[0096] V. Association between probe maintenance and test accuracy

[0097] The probe cleaning table of the auxiliary photoelectric test system 3 regularly cleans the probe, which ensures the accuracy of the micro-nano probe signal collection, the data collection and processing system 7 generates reliable results based on clean signals, and the computer control system 1 does not need to be frequently calibrated, thereby improving the test efficiency.

[0098] Through the unified scheduling of the computer control system 1, based on the vacuum environment, through data transmission and power support, the whole process automation test of "film loading-positioning-irradiation-signal collection-processing-feedback" is realized, and finally the efficient and high-precision test of Micro LED is achieved.

[0099] Embodiment two

[0100] The application specifically provides a test equipment for testing the electrical performance of LED based on an electron ion beam, and the parameters of each system are as follows:

[0101] Electron optical column system: electron gun acceleration voltage 0.5-20kV, beam spot diameter 50-1000nm, scanning speed expressed by frequency 50-100MHz, the faster the scanning speed, the faster the test speed;

[0102] Auxiliary photoelectric test system 3: probe diameter 2μm, integrating sphere diameter 100mm, filter wheel containing 450nm, 520nm, 630nm filters, secondary electron detector resolution 20nm;

[0103] High-precision platform system 4: X / Y axis travel 200mm, positioning accuracy ±0.5μm, θ axis rotation range ±15°;

[0104] Vacuum system 5: ultimate vacuum degree 5×10 -6 Pa, vacuum time <10 minutes;

[0105] Automatic wafer loading system 6: maximum load of mechanical arm 5 kg, wafer positioning accuracy ±3 μm;

[0106] Data collection and processing system 7: A / D sampling rate 5 MHz, data analysis delay <10 ms.

[0107] Take the test of 6-inch sapphire substrate flip-chip Micro LED blue chip wafer as an example, the specific steps are as follows:

[0108] S1, initialization preparation: the operator sets the test parameters (beam current intensity 100 μA, scanning step 1 μm, signal sampling rate 1 MHz) through the man-machine interaction unit, the power supply system 8 is started and self-checked, and after the voltages of each module are stabilized, the “ready” signal is fed back to the computer control system 1;

[0109] S2, vacuumizing: the computer control system 1 opens the vacuum valve, the mechanical pump first draws the vacuum degree of the cavity to below 1 Pa, and then the molecular pump is started, and the vacuum degree is raised to 5×10 -6 Pa within 10 minutes; the vacuum degree sensor feeds back data in real time, and triggers the preheating of the electron optical column system after reaching the standard;

[0110] S3, automatic wafer loading: after the wafer box is manually loaded into the loading cavity, the loading cavity is vacuumized, the computer control system 1 instructs the mechanical arm of the automatic wafer loading system 6 to grab the wafer from the wafer box, and after visual positioning, it is transferred to the loading port of the vacuum cavity; the loading port sealing door is opened, the mechanical arm places the wafer on the loading disc of the high-precision platform, the loading disc electrostatic adsorption disc is opened or the locking structure is started to fix the wafer, and the mechanical arm exits, and then the sealing door is closed;

[0111] S4, position calibration: the high-precision platform moves to the initial test position, the secondary electron detector is started, the wafer surface image is collected and transmitted to the computer, and the reference point of the chip array is positioned through image recognition; the computer control system 1 calibrates the correspondence between the electron beam scanning path and the chip electrode according to the reference point coordinates;

[0112] S5, signal acquisition:

[0113] The electron optical column emits an electron beam, scans the chip N pole on the wafer surface according to the preset path, and the deceleration electrode applies a 500 V reverse voltage to reduce the beam energy;

[0114] The micro-nano probe directly stabs the P electrode, collects the forward current signal (0-1 mA) flowing through the chip, and transmits it to the data collection and processing system 7 after being amplified by the signal conditioning module;

[0115] The integrating sphere collects the chip light emission signal from the bottom of the wafer (through the hollow area of the platform), filters it through a 450 nm filter, and then transmits it to the spectrometer through an optical fiber to convert it into an electrical signal;

[0116] The data collection and processing system 7 synchronously analyzes the electrical signal and the optical signal to generate the forward voltage (Vf), the luminous intensity (Iv), and the peak wavelength (λp) of each chip;

[0117] When the reverse leakage current IR needs to be tested, the ion optical column generates an ion beam to scan the N electrode on the wafer surface according to a preset path, so that the N electrode is positively charged, the micro-nano probe contacts the P electrode of the chip, at this time, there is a reverse voltage between the PN electrodes of the chip to be tested, and the micro-nano probe can collect the reverse leakage current IR.

[0118] S6, dynamic adjustment: if the signal of a certain area is abnormal (such as sudden change of current), the computer control system 1 pauses scanning, starts the secondary electron detector to shoot the image of the area, and confirms whether there is an electrode defect; if there is a defect, the chip is automatically skipped or the scanning path is adjusted to the adjacent effective electrode;

[0119] S7, probe cleaning: every 100 million or 1 billion chips are tested, the computer control system 1 instructs the micro-nano probe system to move to the cleaning table, and the probe surface is wiped to remove contaminants through the cleaning pad, and the cleaning time is 5 seconds;

[0120] S8, whole wafer testing: the high-precision platform moves according to a preset step (10 mm / step), and the electron beam scans field by field until the whole wafer testing is completed; the testing data is stored in the data collection and processing system 7 in real time, and is displayed on the human-computer interaction unit at the same time;

[0121] S9, unload wafer: after the testing is completed, the mechanical arm moves the wafer from the loading disc back to the wafer box, the loading port sealing door is opened, the vacuum valve of the loading cavity where the wafer box is located is opened to release the cavity pressure, and the testing process is completed.

[0122] Different chip adaptation schemes for different substrates:

[0123] Si-based substrate (not transparent): the computer control system 1 instructs the high-precision platform to rotate 15° around the X axis, and the integrating sphere is moved from the side of the cavity to 10 mm above the wafer, and the side-emitted light is collected through the inclination angle;

[0124] Vertical chip (electrode on the upper surface): the electrodes at one end of the vertical chip are connected together through the conductive substrate, the micro-nano probe system pierces the conductive substrate, the upper surface electrode is bombarded by the electron beam ion beam, and the signal is collected by applying voltage through the probe.

[0125] The embodiment realizes efficient and high-precision testing of the Micro LED wafer through non-contact scanning of the electron beam and cooperation of multiple systems, the repeatability error of the testing data is less than 0.5%, and the chip damage rate is less than 0.01%, which is significantly better than the traditional probe contact type testing equipment.

[0126] Finally, it should be noted that the above is only the preferred embodiment of the present application, and is not intended to limit the present application, although the foregoing embodiments of the present application are described in detail, for those skilled in the art, it can still be modified to the technical solutions described in the foregoing embodiments, or part of the technical features are equivalent to replace, as long as within the spirit and principles of the present application, any modification, equivalent replacement, improvement, etc. made, should be included within the scope of the present application.

Claims

1. A testing device for testing the electrical performance of LEDs based on electron ion beam, characterized in that, The application relates to a data transmission system, a vacuum system, a computer control system, a data collection and processing system, a power supply system, an automatic wafer loading system, a high-precision platform system, an electron or ion optical column system and an auxiliary photoelectric testing system. The computer control system serves as a core control unit and is electrically connected with the data transmission system, the vacuum system, the data collection and processing system, the power supply system, the automatic wafer loading system, the high-precision platform system, the electron or ion optical column system and the auxiliary photoelectric testing system to realize control instruction transmission. The data transmission system forms a bidirectional data interaction channel with the auxiliary photoelectric testing system, the data collection and processing system and the computer control system. The power supply system is connected with all the other systems to provide adaptive working voltage for the systems. All the execution systems feed back working state signals to the computer control system through the data transmission system. The electron or ion optical column system is fixed on the top of a cavity of the vacuum system and is connected with the inside of the cavity through a beam output port; the system is connected with the computer control system through a control cable to receive beam intensity, beam spot diameter and scanning path instructions; a high-voltage supply end of the system is connected with a high-voltage module of the power supply system; and the working enable signal of the system is linked with the vacuum degree signal of the vacuum system, and the beam emission is started only when the vacuum degree reaches the standard.

2. The test apparatus for testing electrical performance of an LED based on an electron beam according to claim 1, wherein, The auxiliary photoelectric testing system comprises a micro-nano probe system, an optical system, a secondary electron detector and a probe cleaning table; the micro-nano probe system and the optical system are connected with the data collection and processing system through signal cables and the data transmission system to unidirectionally transmit electric signals and optical signals; 3. The test apparatus for testing electrical performance of an LED based on an electron beam according to claim 1, wherein, The secondary electron detector is bidirectionally connected with the data transmission system through an image transmission cable to transmit detection images and receive collection parameter instructions; and the probe cleaning table is connected with the computer control system through a driving module to receive cleaning control instructions. The driving mechanism of the micro-nano probe system is linked with the position encoder signal of the high-precision platform system; when the high-precision platform system is displaced, the position encoder feeds back coordinates to the computer control system through the data transmission system, and the computer control system synchronously drives the micro-nano probe system to keep the probe tip in a preset contact state with the LED wafer electrode.

4. The test apparatus for testing electrical performance of an LED based on an electron beam according to claim 3, wherein, The high-precision platform system is nested in the cavity of the vacuum system, and a wafer table surface is vertically corresponding to the beam bombardment point of the electron or ion optical column system; 5. The test apparatus for testing electrical performance of an LED based on an electron beam according to claim 1, wherein, X / Y / Z axis driving motors of the high-precision platform system are connected with the computer control system through a servo controller to receive displacement control pulses; A position feedback sensor forms a closed-loop feedback with the computer control system through the data transmission system; A light transmission region of the high-precision platform system is coaxially corresponding to a collection port of the optical system of the auxiliary photoelectric testing system. The mechanical arm path of the automatic wafer loading system is corresponding to the loading port space of the cavity of the vacuum system, and an execution end is in isolable communication with the cavity through a vacuum valve; a control unit of the system is connected with the computer control system through an industrial bus to receive feeding and discharging instructions; a wafer positioning sensor is linked with the wafer disc positioning groove of the high-precision platform system to ensure that the placing deviation is less than or equal to 5 microns.

6. The test apparatus for testing electrical performance of an LED based on an electron beam according to claim 1, wherein, ​ 7. The test apparatus for testing electrical properties of LEDs based on electron beam according to claim 3 or 4, wherein, The data collection and processing system comprises a signal conditioning module, an A / D conversion module and a data analysis unit; the signal conditioning module is connected with the micro-nano probe system and the optical system through a data transmission system, and filters and amplifies the original signal; the output end of the A / D conversion module is connected with the data analysis unit; the data analysis unit is bidirectionally connected with the computer control system through an Ethernet, receives test parameters and feeds back processing results.

8. The test apparatus for testing electrical performance of an LED based on an electron beam according to claim 1, wherein, The power supply system comprises a main power module, a high-voltage power module, a precision low-voltage module and a power supply monitoring unit; the main power module is connected with an external power grid, and supplies power for other modules; the high-voltage power module is connected with the electron or ion optical column system through a shielded cable, and outputs an adjustable voltage of 0-50kV; the precision low-voltage module outputs to each system through multiple channels, and provides stable voltages of ±12V, ±5V and 3.3V; the power supply monitoring unit is connected with the computer control system through an I2C bus, and transmits voltage and current parameters.

9. The test apparatus for testing electrical performance of an LED based on an electron beam according to claim 1, wherein, The vacuum system comprises a vacuum cavity, a molecular pump, a mechanical pump, a vacuum valve and a vacuum degree sensor; the molecular pump and the mechanical pump are connected with the cavity through the vacuum valve; the vacuum degree sensor is connected with the computer control system through a data transmission system, and transmits vacuum degree data; the control end of the vacuum valve is connected with the computer control system, receives switch instructions, and is interlocked with the action of the mechanical arm of the automatic film loading system.

10. The test apparatus for testing electrical performance of an LED based on an electron beam according to claim 1, wherein, The data transmission system adopts a hybrid architecture: an industrial Ethernet bus is connected with the computer control system, the automatic film loading system and the high-precision platform system, and transmits control instructions; a PCIe interface is connected with the computer control system and the data collection and processing system, and transmits high-speed signals; an RS485 bus is connected with the computer control system, the power supply monitoring unit and the vacuum degree sensor, and transmits low-voltage signals; All lines adopt a shielding design, and are spatially isolated from the power supply lines.

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