Sample testing method and system for GaAs chip

Abstract

The invention discloses a sample testing system of a GaAs chip, which belongs to the technical field of chip testing, and comprises a source measuring unit for applying bias voltage to a sample; the tunable light source module provides a stable single-mode light beam with continuously adjustable wavelength; the optical coupling module couples the single-mode light beam to a sample; the photoelectric detection and conversion module is used for collecting photocurrent signals of the sample under single-mode light beams with different wavelengths and converting the photocurrent signals into voltage signals; the data acquisition and processing module acquires each voltage signal and the corresponding wavelength and draws a photocurrent spectrum curve; and the band gap energy analysis module analyzes the band gap energy of the current sample according to the photocurrent spectrum curve. The light source wavelength is controlled to detect the light current change of the chip after photoelectric response, the light current change is converted into the voltage signal change which is obvious in data and convenient to record to draw the light current spectrum curve, and the band gap energy of the chip is efficiently and accurately analyzed.

Description

Technical Field

[0001] The present invention relates to the technical field of chip testing, and in particular to a sample testing method and system for a GaAs chip. Background Art

[0002] Semiconductor materials occupy a vital position in the modern electronics and optoelectronics industries. Gallium arsenide (GaAs), as a direct bandgap semiconductor material, is widely used in radio frequency devices, photodetectors, solar cells, and optical fiber communications due to its excellent optoelectronic properties, high-speed switching characteristics, and outstanding thermal stability.

[0003] According to the invention patent with application number CN202310230390.0, a chip testing system is provided, which includes chip appearance test, RF power inspection, chip current test, reliability test, conversion speed performance index test and test learning terminal, but cannot provide bandgap energy test for semiconductor chips.

[0004] Bandgap energy is a basic physical parameter of semiconductor materials, which determines the minimum energy required for electrons to jump from the valence band to the conduction band in the semiconductor band structure. For II and IV compound semiconductors such as GaAs, the bandgap width is about 1.42eV, which directly affects its application design in the fields of photoelectric conversion, microelectronics and optoelectronics. For example, in solar cells, the bandgap energy determines what wavelength of photons the material can absorb and convert into charge carriers; in lasers or light-emitting diodes, it is related to the operating wavelength and efficiency of the device.

[0005] The actual band gap energy of GaAs chips that can be actually prepared may deviate from the theoretical value due to uneven doping or defects. By performing spectral testing on the chip and calculating the band gap energy, the chip quality and the stability and maturity of the related manufacturing process can be evaluated. Therefore, a testing method and system for testing the band gap energy of the chip are needed. Summary of the invention

[0006] In order to solve the technical problems existing in the prior art, the present invention provides a sample testing system for GaAs chips, comprising: a control center, a fixing module, a source measurement unit, a tunable light source module, an optical coupling module, a photoelectric detection and conversion module, a data acquisition and processing module and a bandgap energy analysis module;

[0007] A fixing module, used for fixing the GaAs chip sample and electrically connecting the electrodes of the GaAs chip sample with the source measurement unit;

[0008] A source measurement unit, used to apply bias voltage to the GaAs chip sample;

[0009] A tunable light source module is used to provide a stable single-mode light beam with continuously adjustable wavelength;

[0010] An optical coupling module, used for coupling the single-mode light beam to a GaAs chip sample;

[0011] Photoelectric detection and conversion module, used to collect the photocurrent signal of GaAs chip samples under single-mode light beams of different wavelengths and convert it into voltage signal;

[0012] A data acquisition and processing module, used to collect and record the voltage signals output by the photoelectric detection and conversion module and the wavelength of the corresponding single-mode light beam output by the tunable light source module, and draw a photocurrent spectrum curve;

[0013] The bandgap energy analysis module is used to analyze the bandgap energy E of the current GaAs chip sample according to the photocurrent spectrum curve drawn by the data acquisition and processing module, specifically:

[0014] Identify the cutoff wavelength λ according to the photocurrent spectrum curve, and analyze the band gap energy E of the current GaAs chip sample according to the cutoff wavelength λ; E=h*c / λ; wherein h represents Planck's constant and c represents the speed of light;

[0015] The cut-off wavelength λ is a wavelength corresponding to an inflection point position where a voltage signal increases sharply as the wavelength decreases in the photocurrent spectrum curve.

[0016] Further, the fixing module includes a sample stage and an electrode connection module; the electrode connection module includes a probe card and a source measurement unit interface;

[0017] The sample stage is used to carry and fix the GaAs chip sample; the probe card is used to accurately contact the metal probe to the electrode on the chip to achieve electrical contact; the source measurement unit interface is used to connect the output port of the source measurement unit.

[0018] Furthermore, the tunable light source module adopts a tunable laser; the tunable laser includes a laser source, a wavelength adjustment unit, a power adjustment unit and a temperature adjustment unit;

[0019] The laser source is used to emit a light beam; the wavelength adjustment unit is used to adjust the output wavelength; the power adjustment unit is used to stabilize the output light intensity; and the temperature adjustment unit is used to stabilize the output wavelength.

[0020] Further, the photoelectric detection and conversion module includes a photoelectric detector, a transimpedance amplifier and an analog-to-digital converter;

[0021] The photodetector is used to collect photocurrent signals of GaAs chip samples under single-mode light beams of different wavelengths;

[0022] The transimpedance amplifier is used to convert the photocurrent signal into a voltage signal and then amplify it;

[0023] The analog-to-digital converter is used to convert the amplified analog voltage signal into a digital voltage signal.

[0024] Furthermore, the photocurrent spectrum curve is plotted with the wavelength of the single-mode light beam as the abscissa and the digital voltage signal as the ordinate.

[0025] Furthermore, it also includes an abnormal alarm module for determining whether the band gap energy E of the current GaAs chip sample is abnormal; if |E-1.42|> the set threshold, it indicates that the band gap energy of the current GaAs chip sample is abnormal, and an alarm message is issued.

[0026] Furthermore, it also includes a temperature control module for controlling the test environment of the GaAs chip sample during the test process to maintain it between 20 and 30 degrees Celsius.

[0027] Furthermore, it also includes a surface defect detection module, which is in communication connection with the control center and is used to perform surface defect detection on GaAs chip samples;

[0028] The surface defect detection module includes: an image acquisition module, a preprocessing module, a segmentation module and a defect judgment module;

[0029] The image acquisition module is used to obtain a color image of the surface of the GaAs chip sample;

[0030] The preprocessing module is used to convert the color image into a grayscale image;

[0031] The segmentation module is used to convert the grayscale image into a first binary image by setting a first threshold value, and to convert the preprocessed grayscale image into a second binary image by setting a second threshold value;

[0032] The white area of ​​the first binary image is the first normal area, and the black area is the first suspected defect area; the black area of ​​the second binary image is the second normal area, and the white area is the second suspected defect area;

[0033] The defect judgment module is used to judge whether the current GaAs chip sample has surface defects.

[0034] Furthermore, the defect judgment module judges whether the current GaAs chip sample has surface defects, specifically:

[0035] The first suspected defect area and the second suspected defect area are judged by a judgment model storing a black area S1 of a first binary image of a normal GaAs chip and a white area S2 of a second binary image; if the area A1 of the first suspected defect area is greater than S1, and / or the area A2 of the second suspected defect area is greater than S2, it is judged that the current GaAs chip sample has a surface defect and an alarm message is sent to a control center;

[0036] If (A1-S1)+(A2-S2) is greater than the set defect area threshold, the control center will no longer perform bandgap energy testing on the current GaAs chip sample and prompt to replace the GaAs chip sample.

[0037] The present invention also provides a GaAs chip sample testing method, comprising the following steps:

[0038] Fixing the GaAs chip sample on the fixing module, and electrically connecting the electrodes of the GaAs chip sample to the source measurement unit;

[0039] The source measurement unit applies a bias voltage to the GaAs chip sample;

[0040] The tunable light source module emits a single-mode light beam which is irradiated onto the GaAs chip sample through the optical coupling module;

[0041] The photocurrent signal of the GaAs chip sample under the single-mode light beam is collected and converted into a voltage signal, and then the tunable light source module is notified to adjust the wavelength of the light beam, and the single-mode light beam is re-sent to the GaAs chip sample;

[0042] Collect and record each voltage signal and the corresponding wavelength of the single-mode light beam in real time, and draw the photocurrent spectrum curve;

[0043] The cutoff wavelength λ is identified according to the photocurrent spectrum curve, and the band gap energy E of the current GaAs chip sample is analyzed according to the cutoff wavelength λ; E=h*c / λ; wherein hb represents Planck's constant and c represents the speed of light.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] By controlling the wavelength of the light source to detect the photocurrent changes after the photoelectric response of the chip, and converting it into a voltage signal change with obvious data and easy to record, the photocurrent spectrum curve is drawn to analyze the band gap energy of the chip efficiently and accurately.

[0046] By applying bias voltage, the photoelectric effect of GaAs chip samples is effectively activated, dark current is reduced, signal-to-noise ratio is improved, and the response sensitivity of the device to incident light is enhanced, further improving the accuracy of the final bandgap energy calculation and analysis;

[0047] The tiny photocurrent signal at the input end is directly converted into a voltage signal at the output end through a transimpedance amplifier, and a very high current gain is achieved with a fixed feedback resistor, that is, the sensitivity of the conversion to voltage is achieved. In addition, the conversion relationship can be determined to be known and constant, and photocurrents of different sizes can be accurately and stably converted, and the voltage signal can be directly used to draw the photocurrent spectrum curve, thereby calculating the band gap energy.

[0048] By adding a surface defect detection module to detect whether the sample has surface defects, the test diversity of the test system is improved. By calculating the area of ​​the surface defect region, it is determined whether to continue to perform bandgap energy detection, thereby reducing test costs and time consumption and improving system test efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a structural block diagram of the system of the present invention;

[0050] Figure 2 It is a structural block diagram of a fixed module of the system of the present invention;

[0051] Figure 3 is a block diagram of the structure of the tunable laser of the system of the present invention;

[0052] Figure 4 is a structural block diagram of an optical coupling module of the system of the present invention;

[0053] Figure 5 It is a structural block diagram of the photoelectric detection and conversion module of the system of the present invention;

[0054] Figure 6 It is a structural block diagram of the surface defect module of the system of the present invention. DETAILED DESCRIPTION

[0055] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Preferred embodiments of the present invention are provided in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0056] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0057] See also Figure 1As shown, a GaAs chip sample testing system provided by the present invention includes: a control center, a fixed module, a source measurement unit, a tunable light source module, an optical coupling module, a photoelectric detection and conversion module, a data acquisition and processing module and a bandgap energy analysis module;

[0058] The fixing module, source measurement unit, tunable light source module, optical coupling module, photoelectric detection and conversion module, data acquisition and processing module and bandgap energy analysis module are all connected to the control center for communication.

[0059] The fixing module is used to fix the GaAs chip sample and electrically connect the electrodes of the GaAs chip sample with the source measurement unit; the electrodes include a gate, a source and a drain.

[0060] See also Figure 2 As shown, the fixing module includes a sample stage and an electrode connection module;

[0061] The sample stage is used to carry and fix the GaAs chip sample, and can ensure that the sample remains stable and is not affected by mechanical stress during the test process.

[0062] The electrode connection module includes a probe card and a source measurement unit interface; the probe card is used to accurately contact the fine and sharp metal probes to the electrodes on the chip to achieve high-precision electrical contact, and the probes are positioned by pneumatic or electric control; the source measurement unit interface is used to connect to the source measurement unit output port through a wire.

[0063] Source measurement unit, used to apply bias voltage to GaAs chip samples.

[0064] The types of bias voltage include: forward bias voltage, reverse bias voltage, gate bias voltage and drain bias voltage; the control center selects the bias voltage type according to the device structure of the current GaAs chip sample;

[0065] For diode-type structures, such as PN junctions, a forward bias voltage or a reverse bias voltage is applied; for field effect transistors, such as MOSFET, MESFET, HEMT, etc., a gate bias voltage and a drain bias voltage are applied. The gate bias voltage is the voltage applied between the gate and the source of the field effect transistor; the drain bias voltage represents the voltage difference between the drain and the source of the field effect transistor.

[0066] In the scheme of the present invention, applying a bias voltage has the following effects:

[0067] 1. Activate the photoelectric effect: In semiconductor materials, electrons need enough energy to jump from the valence band to the conduction band to form free electrons and holes. Applying a bias voltage can drive carriers (electrons and holes) from the generation area to the electrode, thereby realizing the detection of photocurrent. When there is no bias voltage, even if there are photogenerated carriers, no net current may be generated because the diffusion and recombination rates are equal in the thermal equilibrium state.

[0068] 2. Improve the signal-to-noise ratio: By applying a bias voltage, the dark current, that is, the current when there is no light, can be reduced, and the signal-to-noise ratio of the device can be improved. At the same time, it helps to control non-intrinsic currents, such as thermal electron emission currents or tunnel currents, to ensure that the measured current is mainly caused by physical phenomena related to the band gap, reducing noise sources.

[0069] 3. Enhanced sensitivity and speed: Applying a bias voltage can enhance the device's response sensitivity to incident light and affect its response time.

[0070] In the scheme of the present invention, the bias voltage is applied by a source measure unit (SMU), which can improve the voltage control accuracy and stability. At the same time, the source measure unit supports independent control of multiple channels. Through multi-channel synchronous operation, different bias voltages can be applied to different regions or different types of contact points under the same test conditions, thereby more comprehensively characterizing the energy band structure of the device.

[0071] The tunable light source module is used to provide a stable single-mode light beam with continuously adjustable wavelength.

[0072] The tunable light source module adopts a tunable laser;

[0073] See also Figure 3 As shown, the tunable laser includes a laser source, a wavelength adjustment unit, a power adjustment unit and a temperature adjustment unit;

[0074] The wavelength adjustment unit adopts a current regulator or a Fabry-Perot cavity length regulator; the current regulator controls the magnitude and frequency of the current injected into the laser diode, thereby adjusting the output wavelength; the Fabry-Perot cavity length regulator adjusts the output wavelength by changing the cavity length;

[0075] The power adjustment unit is used to stabilize the light intensity output by the laser;

[0076] The temperature regulating unit is used to maintain the operating temperature of the laser to stabilize the wavelength of the output light beam.

[0077] The optical coupling module is used to accurately couple the single-mode light beam to the GaAs chip sample and adjust the spot size to match the effective area of ​​the GaAs chip sample.

[0078] See also Figure 4 As shown, the optical coupling module includes a focusing and collimating unit, a fiber coupling unit and a filtering unit.

[0079] The focusing and collimating unit is used to collimate and focus the single-mode light beam to ensure that the laser spot can be accurately irradiated onto the GaAs chip sample and the spot size matches the effective area of ​​the current GaAs chip sample.

[0080] The optical fiber coupling unit is used to reduce the loss during the optical path transmission process and improve the energy utilization rate of the light beam, so as to more accurately measure the response of the chip to light of different wavelengths.

[0081] The filtering unit is used to filter light of other wavelength bands according to the currently required light beam wavelength parameter to prevent the single-mode light beam emitted by the tunable laser from having stray light.

[0082] The photoelectric detection and conversion module is used to collect the photocurrent signals of GaAs chip samples under single-mode light beams of different wavelengths and convert them into voltage signals.

[0083] See also Figure 5 As shown, the photoelectric detection and conversion module includes a photoelectric detector, a transimpedance amplifier and an analog-to-digital converter;

[0084] The photodetector is used to collect photocurrent signals of GaAs chip samples under single-mode light beams of different wavelengths;

[0085] The transimpedance amplifier is used to convert the photocurrent signal into a voltage signal and then amplify it;

[0086] Specifically, the working principle of the transimpedance amplifier (TIA) is a current-to-voltage conversion process, in which the current at the input end is directly converted into the voltage at the output end through a feedback resistor; and when the transimpedance amplifier converts the photocurrent into a voltage signal, the ratio of the current-to-voltage conversion is the transimpedance gain, which is equal to the resistance value of the feedback resistor. The transimpedance amplifier uses a fixed feedback resistor, so the conversion relationship of the transimpedance amplifier converting the photocurrent into a voltage signal is known and constant.

[0087] The analog-to-digital converter is used to convert the amplified analog voltage signal into a digital voltage signal.

[0088] The data acquisition and processing module is used to collect and record the voltage signals output by the photoelectric detection and conversion module and the wavelength of the corresponding single-mode light beam output by the tunable light source module, and draw a photocurrent spectrum curve.

[0089] Specifically, since the solution of the present invention adopts a transimpedance amplifier, the conversion relationship of the photocurrent into the voltage signal is known and constant, so the collected digital voltage signal can directly reflect the size of the photocurrent. The photocurrent spectrum curve is drawn with the single-mode light beam wavelength as the horizontal axis and the digital voltage signal as the vertical axis.

[0090] The bandgap energy analysis module is used to identify the cutoff wavelength λ according to the photocurrent spectrum curve drawn by the data acquisition and processing module, and analyze the bandgap energy E of the current GaAs chip sample according to the cutoff wavelength λ; E=h*c / λ; wherein hb represents Planck's constant and c represents the speed of light.

[0091] Specifically, when the photon energy is equal to or slightly higher than the bandgap width of the semiconductor material, a large number of electrons begin to jump from the valence band to the conduction band, and the photocurrent increases significantly. That is, the turning point is the inflection point where the photocurrent increases sharply as the wavelength decreases, that is, the wavelength corresponding to the inflection point where the voltage signal increases sharply as the wavelength decreases is the cut-off wavelength.

[0092] In some embodiments, the system of the present invention also includes a temperature control module for controlling the test environment of the GaAs chip sample during the test process to maintain between 20 and 30 degrees Celsius, reducing the impact of temperature on the photoelectric response of the GaAs chip sample, thereby improving the accuracy of band gap energy calculation.

[0093] In some embodiments, the system of the present invention also includes an abnormal alarm module for determining whether the band gap energy E of the current GaAs chip sample is abnormal; if |E-1.42|> the set threshold, it indicates that the band gap energy of the current GaAs chip sample is abnormal, and an alarm message is issued.

[0094] In some embodiments, before testing the band gap energy of the GaAs chip sample, a surface defect test is performed first, and then it is determined whether to perform the band gap energy test based on the defect test data. Therefore, the system of the present invention also includes a surface defect detection module, which is communicatively connected to the control center and is used to perform surface defect detection on the GaAs chip sample.

[0095] See also Figure 6 As shown, the surface defect detection module includes: an image acquisition module, a preprocessing module, a segmentation module and a defect judgment module;

[0096] The image acquisition module is used to obtain a color image of the surface of a GaAs chip sample.

[0097] The preprocessing module is used to perform a preprocessing operation on the color image;

[0098] The preprocessing operation includes: grayscale conversion, that is, converting the color image into a grayscale image; denoising, that is, applying median filtering, Gaussian filtering and other methods to remove noise in the grayscale image; smoothing; and contrast enhancement.

[0099] The segmentation module is used to convert the preprocessed grayscale image into a first binary image through a first threshold value and to convert the preprocessed grayscale image into a second binary image through a second threshold value;

[0100] The white area of ​​the first binary image is the first normal area, and the black area is the first suspected defect area;

[0101] The black area of ​​the second binary image is the second normal area, and the white area is the second suspected defect area.

[0102] The grayscale distribution of the grayscale image on the surface of a normal GaAs chip generally presents a relatively uniform or regular characteristic, while defective areas such as cracks and impurity aggregation will show grayscale characteristics that are significantly different from normal areas. Therefore, the grayscale image is converted into a binary image through an appropriate threshold, and the pixels above the threshold are set to white, and the pixels below the threshold are set to black, which can clearly distinguish the normal area of ​​the chip from the suspected defective area. At the same time, because the grayscale value of the defective area on the chip surface will be brighter or darker than the normal area depending on the type of defect, for example, contaminants may increase the reflectivity and thus present a brighter grayscale value in the image, while cracks or missing materials may appear darker in the image due to the weakening of light penetration or scattering, so this embodiment sets two thresholds to obtain two different binary images, reduce missed detection, and improve the accuracy of detecting defective areas.

[0103] The defect judgment module is used to judge whether the current GaAs chip sample has surface defects, specifically:

[0104] The first suspected defect area and the second suspected defect area are judged by a judgment model storing a black area S1 of a first binary image of a normal GaAs chip and a white area S2 of a second binary image; if the area A1 of the first suspected defect area is greater than S1, and / or the area A2 of the second suspected defect area is greater than S2, it is judged that the current GaAs chip sample has a surface defect and an alarm message is sent to a control center;

[0105] If (the area of ​​the first suspected defect region A1-S1) + (the area of ​​the second suspected defect region A2-S2) is greater than the set defect area threshold, the control center will no longer perform bandgap energy testing on the current GaAs chip sample, and prompt to replace the GaAs chip sample, thereby reducing testing costs and time consumption and improving system utilization efficiency.

[0106] By comparing the area of ​​the suspected defect area with the relevant area of ​​the binary image of the normal chip, it is determined whether there is a real defect area in the suspected area to avoid misdetection and further improve the accuracy of chip surface defect detection.

[0107] In some embodiments, in order to test the reliability of GaAs chip samples under stress, the system of the present invention further includes: a bending test module, a force sensor, a displacement sensor and a data acquisition and analysis module;

[0108] The bending test module, force sensor, displacement sensor and data acquisition and analysis module are all connected to the control center for communication.

[0109] Bending test module, used to perform precise three-point bending loading on GaAs chip samples;

[0110] A force sensor is used to monitor and record the force applied to the GaAs chip sample;

[0111] Displacement sensor, used to measure the deformation of GaAs chip samples during force application;

[0112] The data acquisition and analysis module is used to collect the force value and deformation variable and calculate mechanical performance parameters such as bending strength and elastic modulus.

[0113] Based on three-point bending, elastic modulus E, E = (F 1 L 3 ) / (4bd 3 Δy); where F 1 is the maximum force applied at the center of the GaAs chip sample; L is the span length of the GaAs chip sample; b and d are the width and thickness of the GaAs chip sample, respectively; Δy is the maximum deflection measured during the loading process, that is, the maximum displacement of the center point.

[0114] Bending strength σ, σ=(3F 2 L) / (2bd 2 );F 2 It is the maximum force when breaking or reaching the yield state.

[0115] By conducting stress reliability tests on GaAs chip samples, the diversity of the test system can be improved.

[0116] The present invention also provides a GaAs chip sample testing method, which is applied to the GaAs chip sample testing system of the above embodiment, and comprises the following steps:

[0117] Fixing the GaAs chip sample on the fixing module, and electrically connecting the electrodes of the GaAs chip sample to the source measurement unit;

[0118] The source measurement unit applies a bias voltage to the GaAs chip sample;

[0119] The tunable light source module emits a single-mode light beam which is irradiated onto the GaAs chip sample through the optical coupling module;

[0120] The photocurrent signal of the GaAs chip sample under the single-mode light beam is collected and converted into a voltage signal, and then the tunable light source module is notified to adjust the wavelength of the light beam, and the single-mode light beam is re-sent to the GaAs chip sample;

[0121] Collect and record each voltage signal and the corresponding wavelength of the single-mode light beam in real time, and draw the photocurrent spectrum curve;

[0122] The cutoff wavelength λ is identified according to the photocurrent spectrum curve, and the band gap energy E of the current GaAs chip sample is analyzed according to the cutoff wavelength λ; E=h*c / λ; wherein hb represents Planck's constant and c represents the speed of light.

[0123] In some embodiments, the GaAs chip sample testing method provided by the present invention further includes the following steps:

[0124] The test environment of the GaAs chip sample is controlled to be maintained between 20 and 30 degrees Celsius during the test process. This step is always performed during the process of testing the band gap energy of the GaAs chip sample.

[0125] In some embodiments, the GaAs chip sample testing method provided by the present invention further includes the following steps:

[0126] After calculating the band gap energy E of the GaAs chip sample, the band gap energy abnormality judgment is performed, specifically:

[0127] Determine whether the band gap energy E of the current GaAs chip sample is abnormal; if |E-1.42|> the set threshold, it means that the band gap energy of the current GaAs chip sample is abnormal, and an alarm message is issued.

[0128] In some embodiments, the GaAs chip sample testing method provided by the present invention further includes the following steps:

[0129] After calculating the band gap energy E of the GaAs chip sample and determining whether the band gap energy is abnormal, the stress test steps are performed, including:

[0130] The GaAs chip sample was subjected to three-point bending loading;

[0131] Monitor and record the force applied to the GaAs chip sample and measure the deformation of the GaAs chip sample during the force application process;

[0132] The force value and deformation amount are collected to calculate the bending strength and elastic modulus.

[0133] Elastic modulus E,; where is the maximum force applied at the center of the GaAs chip sample; L is the span length of the GaAs chip sample; b and d are the width and thickness of the GaAs chip sample, respectively; Δy is the maximum deflection measured during loading, that is, the maximum displacement of the center point.

[0134] Bending strength σ, is the maximum force value when breaking or reaching yield state.

[0135] In some embodiments, the GaAs chip sample testing method provided by the present invention further includes the following steps before the source measurement unit applies a bias voltage to the GaAs chip sample:

[0136] Get color images of the surface of GaAs chip samples;

[0137] The color image is converted into a grayscale image;

[0138] The preprocessed grayscale image is converted into a first binary image through a first threshold, and the preprocessed grayscale image is converted into a second binary image through a second threshold; the white area of ​​the first binary image is a first normal area, and the black area is a first suspected defect area; the black area of ​​the second binary image is a second normal area, and the white area is a second suspected defect area.

[0139] Determine whether the current GaAs chip sample has surface defects, specifically:

[0140] The first suspected defect area and the second suspected defect area are judged by a judgment model storing a black area S1 of a first binary image of a normal GaAs chip and a white area S2 of a second binary image; if the area A1 of the first suspected defect area is greater than S1, and / or the area A2 of the second suspected defect area is greater than S2, it is judged that the current GaAs chip sample has a surface defect and an alarm message is sent to a control center;

[0141] If (A1-S1)+(A2-S2) is greater than the set defect area threshold, the test of the current GaAs chip sample is stopped and a prompt is given to replace the GaAs chip sample.

[0142] The beneficial effects of the present invention are:

[0143] By controlling the wavelength of the light source to detect the photocurrent changes after the photoelectric response of the chip, and converting it into a voltage signal change with obvious data and easy to record, the photocurrent spectrum curve is drawn to analyze the band gap energy of the chip efficiently and accurately.

[0144] By applying bias voltage, the photoelectric effect of GaAs chip samples is effectively activated, dark current is reduced, signal-to-noise ratio is improved, and the response sensitivity of the device to incident light is enhanced, further improving the accuracy of the final bandgap energy calculation and analysis;

[0145] The tiny photocurrent signal at the input end is directly converted into a voltage signal at the output end through a transimpedance amplifier, and a very high current gain is achieved with a fixed feedback resistor, that is, the sensitivity of the conversion to voltage is achieved. In addition, the conversion relationship can be determined to be known and constant, and photocurrents of different sizes can be accurately and stably converted, and the voltage signal can be directly used to draw the photocurrent spectrum curve, thereby calculating the band gap energy.

[0146] By adding a surface defect detection module to detect whether the sample has surface defects, the test diversity of the test system is improved. By calculating the area of ​​the surface defect region, it is determined whether to continue to perform bandgap energy detection, thereby reducing test costs and time consumption and improving system test efficiency.

[0147] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0148] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0149] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0150] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0151] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, read-on lymemory), random access memory (RAM, random access memory), disk or optical disk and other media that can store program codes.

[0152] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0153] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A GaAs chip sample testing system, characterized in that: include: Control center, fixed module, source measurement unit, tunable light source module, optical coupling module, photoelectric detection and conversion module, data acquisition and processing module and bandgap energy analysis module; A fixing module, used for fixing the GaAs chip sample and electrically connecting the electrodes of the GaAs chip sample with the source measurement unit; A source measurement unit, used to apply bias voltage to the GaAs chip sample; A tunable light source module is used to provide a stable single-mode light beam with continuously adjustable wavelength; An optical coupling module, used for coupling the single-mode light beam to a GaAs chip sample; Photoelectric detection and conversion module, used to collect the photocurrent signal of GaAs chip samples under single-mode light beams of different wavelengths and convert it into voltage signal; A data acquisition and processing module, used to collect and record the voltage signals output by the photoelectric detection and conversion module and the wavelength of the corresponding single-mode light beam output by the tunable light source module, and draw a photocurrent spectrum curve; The bandgap energy analysis module is used to analyze the bandgap energy E of the current GaAs chip sample according to the photocurrent spectrum curve drawn by the data acquisition and processing module, specifically: Identify the cutoff wavelength λ according to the photocurrent spectrum curve, and analyze the band gap energy E of the current GaAs chip sample according to the cutoff wavelength λ; E=h*c / λ; wherein h represents Planck's constant and c represents the speed of light; The cut-off wavelength λ is a wavelength corresponding to an inflection point position where a voltage signal increases sharply as the wavelength decreases in the photocurrent spectrum curve.

2. The GaAs chip sample testing system according to claim 1, characterized in that: The fixing module includes a sample stage and an electrode connection module; the electrode connection module includes a probe card and a source measurement unit interface; The sample stage is used to carry and fix the GaAs chip sample; the probe card is used to accurately contact the metal probe to the electrode on the chip to achieve electrical contact; the source measurement unit interface is used to connect the output port of the source measurement unit.

3. The GaAs chip sample testing system according to claim 1, characterized in that: The tunable light source module adopts a tunable laser; the tunable laser includes a laser source, a wavelength adjustment unit, a power adjustment unit and a temperature adjustment unit; The laser source is used to emit a light beam; the wavelength adjustment unit is used to adjust the output wavelength; the power adjustment unit is used to stabilize the output light intensity; and the temperature adjustment unit is used to stabilize the output wavelength.

4. The GaAs chip sample testing system according to claim 1, characterized in that: The photoelectric detection and conversion module includes a photoelectric detector, a transimpedance amplifier and an analog-to-digital converter; The photodetector is used to collect photocurrent signals of GaAs chip samples under single-mode light beams of different wavelengths; The transimpedance amplifier is used to convert the photocurrent signal into a voltage signal and then amplify it; The analog-to-digital converter is used to convert the amplified analog voltage signal into a digital voltage signal.

5. The GaAs chip sample testing system according to claim 4, characterized in that: The photocurrent spectrum curve is plotted with the wavelength of the single-mode light beam as the abscissa and the digital voltage signal as the ordinate.

6. The GaAs chip sample testing system according to claim 1, characterized in that: It also includes an abnormal alarm module, which is used to determine whether the band gap energy E of the current GaAs chip sample is abnormal; if |E-1.42|> the set threshold, it means that the band gap energy of the current GaAs chip sample is abnormal, and an alarm message is issued.

7. The GaAs chip sample testing system according to claim 1, characterized in that: It also includes a temperature control module for controlling the test environment of the GaAs chip sample to be maintained between 20 and 30 degrees Celsius during the test process.

8. The GaAs chip sample testing system according to claim 1, characterized in that: It also includes a surface defect detection module, which is in communication connection with the control center and is used to perform surface defect detection on GaAs chip samples; The surface defect detection module includes: an image acquisition module, a preprocessing module, a segmentation module and a defect judgment module; The image acquisition module is used to obtain a color image of the surface of the GaAs chip sample; The preprocessing module is used to convert the color image into a grayscale image; The segmentation module is used to convert the grayscale image into a first binary image by setting a first threshold value, and to convert the preprocessed grayscale image into a second binary image by setting a second threshold value; The white area of ​​the first binary image is the first normal area, and the black area is the first suspected defect area; the black area of ​​the second binary image is the second normal area, and the white area is the second suspected defect area; The defect judgment module is used to judge whether the current GaAs chip sample has surface defects.

9. The GaAs chip sample testing system according to claim 8, characterized in that: The defect judgment module judges whether the current GaAs chip sample has surface defects, specifically: The first suspected defect area and the second suspected defect area are judged by a judgment model storing a black area S1 of a first binary image of a normal GaAs chip and a white area S2 of a second binary image; If the area A1 of the first suspected defect region is greater than S1, and / or the area A2 of the second suspected defect region is greater than S2, it is determined that the current GaAs chip sample has a surface defect and an alarm message is sent to the control center; If (A1-S1)+(A2-S2) is greater than the set defect area threshold, the control center will no longer perform bandgap energy testing on the current GaAs chip sample and prompt to replace the GaAs chip sample.

10. A GaAs chip sample testing method, applied to the GaAs chip sample testing system according to any one of claims 1 to 9, characterized in that: The following steps are involved: Fixing the GaAs chip sample on the fixing module, and electrically connecting the electrodes of the GaAs chip sample to the source measurement unit; The source measurement unit applies a bias voltage to the GaAs chip sample; The tunable light source module emits a single-mode light beam which is irradiated onto the GaAs chip sample through the optical coupling module; The photocurrent signal of the GaAs chip sample under the single-mode light beam is collected and converted into a voltage signal, and then the tunable light source module is notified to adjust the wavelength of the light beam, and the single-mode light beam is re-sent to the GaAs chip sample; Collect and record each voltage signal and the corresponding wavelength of the single-mode light beam in real time, and draw the photocurrent spectrum curve; The cutoff wavelength λ is identified according to the photocurrent spectrum curve, and the band gap energy E of the current GaAs chip sample is analyzed according to the cutoff wavelength λ; E=h*c / λ; wherein hb represents Planck's constant and c represents the speed of light.

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