Novel ultrafast IV ferroelectric material testing method

Abstract

The invention relates to the technical field of material performance testing, in particular to a novel ultrafast IV ferroelectric material testing method, and provides the following scheme aiming at the problems that in the prior art, a ferroelectric material IV testing method is low in speed, low in time resolution, low in precision and incapable of accurately reflecting the electrical performance of a ferroelectric material under ultrafast voltage excitation. A hardware-level synchronous test system composed of a waveform generator / fast measurement unit (WGFMU) and a dual remote induction and switch unit (RSU) is constructed, a ferroelectric sample is prepared in combination with pulsed laser deposition (PLD) in a standardized mode, then a special voltage waveform signal is edited, and accurate test of the current-voltage characteristics of the ferroelectric material under the nanosecond time scale is achieved. According to the method, the defects of an existing IV test method in the aspects of test speed, time resolution and test precision are overcome, and the electrical performance of the ferroelectric material under high-frequency and rapid change working conditions can be reflected more truly.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material performance testing, and particularly relates to a novel superfast IV testing method for ferroelectric materials. BACKGROUND

[0002] Ferroelectric materials have been widely studied and applied in the fields of non-volatile memory, sensor, capacitor, micro-electro-mechanical system, etc. due to their unique ferroelectric effect, piezoelectric effect, dielectric effect, etc. IV testing (current-voltage characteristic testing) is an important means to evaluate the electrical properties of ferroelectric materials. By testing the current change of ferroelectric materials under different voltage excitations, key performance parameters such as leakage current, switching current and coercive voltage of the materials can be obtained, which are crucial for the application selection and device design of ferroelectric materials.

[0003] At present, applying square pulse or triangular pulse signals to ferroelectric capacitors is the most commonly used method to study the basic process of polarization reversal of ferroelectric materials. The existing IV testing method for ferroelectric materials mainly adopts traditional direct current or low-frequency alternating current testing technology, which has a low measurement frequency and can only measure some highly insulating ferroelectric thin film capacitors. The measurement frequency is lower than 1 MHz, which cannot characterize the insulating / leakage ferroelectric thin films or two-dimensional ferroelectric semiconductor materials with nanosecond-level read / write speed, affecting the development of ferroelectric functional devices with superfast response. With the increasing demand for the application of ferroelectric materials in high-frequency and high-speed devices, the traditional testing method cannot meet the testing needs of the electrical properties of ferroelectric materials under superfast voltage change conditions. Under the condition of superfast time resolution, the physical processes such as polarization reversal and domain wall motion of ferroelectric materials have very short response time. Due to the slow signal excitation speed and data acquisition lag of the traditional testing method, the details of the current change of the material in the superfast process cannot be accurately captured, resulting in a large deviation between the test results and the actual performance of the material under working conditions.

[0004] In addition, the existing testing system has deficiencies in synchronous control and signal acquisition. The synchronization accuracy between the voltage excitation signal and the current acquisition signal is low, which easily introduces testing errors. The testing content is not clear, and the proportion of the reversed ferroelectric domain cannot be completely determined. At the same time, the response speed and sensitivity of the current probe also limit the accurate detection of weak superfast current signals, which cannot detect weak signals and cannot determine the proportion of the reversed ferroelectric domain under low voltage. Therefore, the present application proposes a novel superfast IV testing method for ferroelectric materials. SUMMARY

[0005] The novel superfast IV testing method for ferroelectric materials solves the problems of slow testing speed, low time resolution and insufficient testing accuracy of the existing IV testing method for ferroelectric materials, and can accurately reflect the electrical properties of ferroelectric materials under superfast voltage excitation.

[0006] In order to achieve the above object, the present application adopts the following technical solutions:

[0007] A novel method for testing ferroelectric material of superfast IV, comprising the following steps:

[0008] S1: Constructing a novel superfast IV testing system: using a waveform generator / rapid measurement unit (WGFMU) and two remote sensing and switching units (RSUs), the WGFMU is connected with the two RSUs through a cable, and the two RSUs are connected with the probe table of the sample testing platform to realize the synchronous control of the voltage excitation signal and the current collection signal;

[0009] S2: Sample preparation: using pulsed laser deposition (PLD) to prepare ferroelectric samples, selecting samples with surface flatness <0.5 μm and thickness tolerance ±5 nm, and then sequentially using 40 kHz anhydrous ethanol ultrasonic cleaning for 3 min, deionized water ultrasonic cleaning for 3 min, and then oxygen plasma treatment;

[0010] S3: Test parameter setting: input specific voltage signal waveform and test parameters in the test system setting interface, the voltage signal waveform includes sine wave, square wave or triangular wave, and the test parameters include voltage amplitude range, frequency, sampling frequency and sampling point number of the data acquisition and analysis module;

[0011] S4: Superfast pulse transient IV testing: placing the ferroelectric material sample prepared in step S2 on the sample testing platform, making the sample closely contact with the probe, and then starting the test;

[0012] S5: Data processing and analysis: the data acquisition and analysis module pre-processes the collected raw data, draws the IV characteristic curve of the ferroelectric material sample according to the pre-processed data, extracts key performance parameters from the IV characteristic curve and analyzes and evaluates.

[0013] Through the above technical solutions, the deficiencies of the existing IV testing method in testing speed, time resolution and testing accuracy are solved, and the electrical performance of the ferroelectric material under high frequency and rapid change working conditions can be more truly reflected, which provides a reliable performance evaluation method for the application of ferroelectric material in high frequency electronic devices, memory and other fields.

[0014] As a further improvement of the above scheme, in step S1, the synchronization accuracy of the voltage excitation signal and the current collection signal realized by the two RSUs is less than 1 ps; the voltage output range of the test system is -5V to 5V, 0V to 10V or -10V to 0V, the background noise is lower than 0.1mV, the current range is ±10mA to ±1μA, the test resolution is 0.00014 of the range, the background noise is 0.2 of the range, the sampling interval is variable from 5ns to 1s, the hardware average is variable from 10ns to 20ms, and the measurement memory depth is about 4 million data points per channel.

[0015] As a further improvement of the above scheme, in step S2, a PLD deposition electrode is used, and after the electrode is deposited, it is annealed at 180℃ for 30min under nitrogen protection, and the electrode is selected from gold electrode or platinum electrode, wherein the high-frequency test preferentially selects a gold electrode with a thickness of 50nm.

[0016] Through the above technical scheme, after the electrode is prepared, it is annealed at 180℃ for 30min under nitrogen protection, which can eliminate deposition stress, promote interface atomic diffusion and fusion, make the contact resistance as small as possible and have less fluctuation in the test process, and the high-frequency test preferentially selects a gold electrode with a thickness of 50nm, which utilizes its low impedance and high chemical stability to reduce signal loss and interface reaction, and the selection of a platinum electrode can effectively enhance its corrosion resistance.

[0017] As a further improvement of the above scheme, in step S2, when the PLD pulse laser deposition is used to prepare a ferroelectric sample, a quasi-molecular laser is used, the laser frequency is controlled at 10Hz-50Hz, the energy density is controlled at 1.0-2.5J / cm 2 , the distance between the target material and the base is 5cm, the substrate temperature is controlled at 600℃ to 700℃ during deposition, the oxygen pressure is maintained at 15-35Pa, the film thickness is fixed at 100-400nm, and after deposition, in-situ annealing is performed for 15min and then cooled to room temperature.

[0018] As a further improvement of the above scheme, in step S3, the test parameters further include a limit voltage size and a limit current size, and the operation mode is set to FastIV mode, wherein one RSU is used to apply voltage and the other RSU is used to detect current.

[0019] As a further improvement of the above scheme, in step S3, the test parameters further include total measurement time and repetition cycle number, and the repetition cycle number is set to 1 by default and can be adjusted according to test requirements.

[0020] As a further improvement of the above scheme, in step S3, the sampling test start time, the sampling test point number and the average sampling time of each point are also edited in the test event column, and after the setting is completed, the empty collection waveform is observed, and if there is deviation, the edited value and the test condition are rechecked.

[0021] As a further improvement of the above scheme, in step S4, during the test, the WGFMU applies a set ultrafast voltage excitation signal to the sample, and simultaneously, the RSU detects the current signal generated by the sample in real time, and transmits the current signal to the data acquisition and analysis module, and the data acquisition and analysis module synchronously acquires and records the voltage signal and the current signal.

[0022] As a further improvement of the above scheme, in step S5, the preprocessing includes noise removal and baseline correction, and the key performance parameters include the coercive voltage and the flip charge quantity.

[0023] As a further improvement of the above scheme, in step S5, the charge quantity value is obtained by integrating different parts of the IV characteristic curve, it is judged that the charge quantity is generated in the ferroelectric domain flipping process, and then the switching characteristics of the ferroelectric material are evaluated.

[0024] Compared with the prior art, the beneficial effects of the present application are that:

[0025] 1. Fast test speed and high time resolution: The present application uses an ultrafast signal generator to generate a high-frequency and rapidly changing voltage excitation signal, cooperates with a high-resolution and high-precision current detector and a high-speed data acquisition and analysis module, and can realize the current-voltage characteristic test of the ferroelectric material on the nanosecond time scale, greatly improves the test speed and time resolution, can capture the instantaneous electrical response of the ferroelectric material in the ultrafast process, and solves the problems of slow signal excitation and data acquisition lag in the traditional test method.

[0026] 2. High test precision: Through the high-precision cooperation of the WGFMU and the two RSUs, the test error introduced by the synchronization error is effectively reduced; at the same time, the system background noise is lower than 0.1mV, the current test resolution reaches 0.00014 of the range, the high-precision current detector has extremely high current detection resolution and bandwidth, can accurately detect weak ultrafast current signals, improves the accuracy and reliability of the test results, and avoids the test errors caused by low synchronization accuracy and insufficient sensitivity of the detector in the traditional system.

[0027] 3. Wide application range: The present application can be applied to different types of ferroelectric materials such as ferroelectric thin films, ferroelectric ceramics and ferroelectric single crystals by adjusting the substrate type, PLD deposition parameters, electrode material and test parameters, and can meet different test requirements such as high-frequency test and leakage material test, and provides an effective means for evaluating the application performance of ferroelectric materials in high-frequency electronic devices, nanosecond-level read-write memory and other fields. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A schematic diagram of a test system structure for a novel method of testing ferroelectric materials of superfast IV;

[0029] Figure 2 A schematic diagram of a pulse voltage output signal for a novel method of testing ferroelectric materials of superfast IV;

[0030] Figure 3 A schematic diagram of a structure of a potassium sodium niobate ferroelectric film sample provided in an embodiment of the application;

[0031] Figure 4 A Charge-Voltage diagram of a potassium sodium niobate ferroelectric film sample provided in an embodiment of the application; DETAILED DESCRIPTION

[0032] The application will be further described below in conjunction with the drawings and specific embodiments, and it should be noted that, without conflict, the embodiments described below or the technical features between the embodiments can be combined in any manner to form new embodiments.

[0033] Embodiment 1:

[0034] In combination with Figure 1 - Figure 4 A novel method of testing ferroelectric materials of superfast IV, comprising the following steps:

[0035] S1: Constructing a novel superfast IV test system, specifically comprising:

[0036] System composition: The test system comprises a waveform generator / rapid measurement unit (WGFMU), two remote sensing and switching units (RSUs), a sample test platform (carrying a probe station), and a data acquisition and analysis module; wherein the WGFMU integrates superfast voltage waveform generation and basic measurement functions, and can output any waveform (sine wave, square wave, triangular wave); the two RSUs are responsible for voltage application and current detection, respectively, and realize high-precision synchronization through hardware-level cooperation; the sample test platform provides a constant-temperature (25±1℃), dustproof, and anti-electromagnetic interference test environment; the data acquisition and analysis module realizes synchronous acquisition, storage, and real-time processing of voltage and current signals;

[0037] Hardware connection and calibration: The connection mode includes connecting the WGFMU and the two RSUs using 50Ω shielded cables (to reduce high-frequency signal attenuation), and then connecting the RSUs and the probe station connection end of the sample test platform through coaxial cables (impedance matching 50Ω); the probe station uses a micro-manipulation structure, supports probe pressure fine adjustment (0-50mN), and ensures electrode contact stability;

[0038] The idle calibration includes outputting a 1V standard square wave signal (rise time <1 ns) by the WGFMU, monitoring the RSU output signal by an oscilloscope (bandwidth ≥1 GHz), adjusting the cable length and impedance matching to ensure the synchronous delay <1 ps, using a high-precision voltage source (accuracy ±0.1 mV) to calibrate the system voltage background noise <0.1 mV, and using a standard resistance box (accuracy ±0.01%) to calibrate the current test resolution to 0.00014 of the range;

[0039] The system parameter calibration sets the system voltage output range as three gears adjustable between -5V and 5V, 0V and 10V, and -10V and 0V; the current range is ±1μA to ±10mA, and the automatic range switching is supported; the data acquisition and analysis module has a memory depth of 4 million data points per channel, the sampling interval can be adjusted between 5ns, 10ns and 1s, the hardware average is adjustable between 10ns and 20ms, and the storage format is.csv (convenient for subsequent data export and analysis);

[0040] The sample test platform is used for placing and fixing the ferroelectric material sample and providing good electrical contact; the data acquisition and analysis module is connected with the high-precision current detector, used for processing, analyzing and storing the collected current signal and corresponding voltage signal, and generating the IV characteristic curve.

[0041] S2: sample preparation, the ferroelectric sample is prepared by pulse laser deposition (PLD), and the specific steps include;

[0042] Target preparation: according to the test requirements, the target material (such as KNN, BaTiO3, PZT) is selected, and the high-density target material (density >95%) is prepared by the solid phase reaction method;

[0043] Thin film deposition: the ferroelectric thin film is deposited on the substrate (STO, sapphire, etc.) by using an excimer laser (such as 248nm KrF laser), and the deposition parameters are controlled as follows: laser frequency 10Hz-50Hz, energy density 1.0-2.5J / cm 2 , target and base distance 5cm, substrate temperature 600℃-700℃, oxygen pressure 15-35Pa, and thin film thickness control 100-400nm (according to the leakage characteristics of the material, the leakage material is preferentially selected as 400nm thick film to reduce the leakage current interference), the change of frequency and energy density will affect the strength of laser bombardment of the target, and appropriate frequency and energy density can better grow high-quality thin film;

[0044] Annealing treatment: after deposition, the sample is subjected to in-situ annealing, and the condition is 15 minutes (nitrogen atmosphere to avoid oxidation), and then naturally cooled to room temperature;

[0045] Sample screening and cleaning: select samples with surface flatness <0.5 μm and thickness tolerance ±5 nm, and remove defective samples with cracks and impurity agglomerates through preliminary inspection by optical microscope; sequentially perform ultrasonic cleaning (40 kHz anhydrous ethanol cleaning for 3 min→ deionized water cleaning for 3 min), and then perform oxygen plasma treatment (power 50 W, time 5 min) to remove organic contaminants and activate the surface, remove impurities attached to the surface layer of the ferroelectric film during growth, and make the ferroelectric film surface in a clean state, improve the interfacial bonding force between the electrode and the sample, and immediately store the cleaned sample in a glove box (inert gas atmosphere) to avoid surface adsorption of water vapor or oxidation and ensure the stability of the surface cleaning state;

[0046] Electrode preparation: a conductive electrode is deposited by PLD, and a 50 nm thick gold electrode (low impedance, high chemical stability, and reduced signal loss) is preferentially selected for high-frequency testing, and a platinum electrode is selected for corrosion-resistant scenarios; after electrode deposition, the electrode is annealed at 180°C for 30 min under nitrogen protection to eliminate deposition stress, promote interfacial atomic diffusion and fusion, make the contact resistance as small as possible and have less fluctuation during testing, ensure that the contact resistance is <1 Ω and the fluctuation during testing is <5%, or a platinum electrode is selected to enhance corrosion resistance;

[0047] S3: Test parameter setting: input voltage signal waveform and test parameters in the test system setting interface, specifically including:

[0048] Mode and channel setting: set the operation mode to "Fast IV mode", specify RSU1 as "voltage application channel" and RSU2 as "current detection channel", and limit the voltage size and limit the current size to avoid damage to the device due to misoperation;

[0049] Safety parameter setting: input the limit voltage (set according to the sample breakdown voltage, usually -5 V to 5 V, 0 V to 10 V, or -10 V to 0 V) and the limit current (±1 μA to ±10 mA) to avoid overvoltage / overcurrent damage to the sample and the system;

[0050] Collection parameter setting: input the total test time (such as 10 ms-50 μs), the number of sampling points (2000-5000 points), the single-point sampling interval (5 ns-1 s), and the average collection time (0.001 ms-0.002 ms);

[0051] No-load verification: after setting, start "empty collection" and observe whether the output waveform is consistent with the setting, if there is a deviation (such as waveform distortion, noise exceeding the standard), recheck the parameter editing and hardware connection until the no-load waveform meets the requirements;

[0052] S4: ultrafast pulse transient IV test, specifically including:

[0053] Sample clamping: Place the sample prepared in step S2 on the sample test platform, adjust the probe position to ensure that the probe is in close contact with the sample electrode (contact resistance <1Ω, monitored in real time by a multimeter);

[0054] Test start: Click the "start" button of the test software, and the WGFMU applies an ultrafast voltage excitation signal to the sample according to the set parameters, while the RSU2 detects the current signal generated by the sample in real time and transmits the current signal (converted to a voltage signal by I / V) to the data acquisition and analysis module;

[0055] Synchronous acquisition: The data acquisition and analysis module synchronously acquires the voltage excitation signal and the current response signal at the set sampling interval, and stores them in real time to the local storage (no more than 4 million data points per channel), ensuring that the data is not lost;

[0056] S5: Data processing and analysis, specifically including:

[0057] Data preprocessing: The collected raw data is subjected to noise filtering (wavelet threshold denoising algorithm) and baseline correction (elimination of zero drift), ensuring that the data signal-to-noise ratio is >50dB;

[0058] Characteristic curve drawing: According to the preprocessed data, the IV characteristic curve (current-voltage relationship) and the Charge-Voltage curve (charge-voltage relationship) of the ferroelectric material are drawn;

[0059] Key parameter extraction: The leakage current density (calculated by the current value and the electrode area), the switching current peak value, and the coercive voltage are extracted from the IV curve; the domain switching charge is calculated by integrating the specific interval (polarization reversal interval) of the IV characteristic curve;

[0060] Performance evaluation: According to the extracted parameters, the sample performance is judged, such as the domain switching charge >1×10 -9 C, it is determined to meet the application requirements of high-frequency ferroelectric devices; if the parameters do not meet the requirements, the sample preparation parameters (such as adjusting the PLD annealing temperature and electrode thickness) or test parameters (such as sampling interval) can be optimized in reverse, and the sample is retested.

[0061] Example 2:

[0062] In combination Figure 1 - Figure 4 , the ultrafast IV test of potassium sodium niobate (KNN) ferroelectric thin film

[0063] Construction of new type of ultrafast IV test system: install WGFMU module on semiconductor parameter analyzer B1500, connect two RSUs through cable, and then connect RSU with probe station; set system voltage output range to -5V to 5V, background noise to 0.08mV, current range to ±1mA, sampling interval to 5ns, hardware average to 10ns, and measurement memory depth to about 4 million data points per channel.

[0064] Sample preparation:

[0065] (1) Target preparation: LBSO target and KNN target are prepared by standard solid phase reaction method;

[0066] (2) Film deposition: LBSO layer is first deposited on STO substrate using 248nm KrF excimer laser, and then KNN film is deposited; during deposition, laser frequency is set to 10Hz, energy density is set to 1.5J / cm 2 , target-to-base distance is 5cm, substrate temperature is maintained at 700℃, oxygen pressure is maintained at 35Pa, and KNN film thickness is fixed at 400nm;

[0067] (3) Annealing treatment: after deposition, the sample is annealed in situ for 15 minutes, and then naturally cooled to room temperature;

[0068] (4) Sample cleaning: select KNN film sample with surface flatness of 0.3μm and thickness tolerance of ±3nm, which is free of cracks and impurity agglomeration after initial inspection by optical microscope; sequentially clean with anhydrous ethanol for 3min (frequency 40kHz), deionized water for 3min, and then treat with oxygen plasma for 5min; after cleaning, store in glove box;

[0069] (5) Electrode preparation: Pt electrode is prepared as top electrode by PLD pulsed laser deposition, with thickness of 50nm; after preparation, anneal at 180℃ for 30min under nitrogen protection, and then cool down for standby.

[0070] Test parameter setting: set operation mode to FastIV mode, RSU1 for voltage application and RSU2 for current detection; limit voltage to 5V and limit current to 1mA; edit voltage waveform to triangular wave, pre-polarization test time to 5ms, pre-polarization voltage to -5V, and then test with 5V to -5V cycle, for a total of three back-and-forth triangular pulses; total test time is set to 10ms, sampling point number to 2000, single-point sampling interval to 0.001ms, and average acquisition time to 0.001ms; after observing that the empty acquisition waveform has no deviation, confirm parameter setting.

[0071] Ultrafast pulse transient IV test: the KNN film sample is placed on the sample test platform, the probe is adjusted to be in close contact with the Pt electrode; the test button is started, the WGFMU applies a set triangular wave voltage excitation signal to the sample, the RSU2 detects the current signal in real time and transmits it to the data acquisition and analysis module, and the module synchronously collects and records the voltage and current data.

[0072] Data processing and analysis: the original data are subjected to noise filtering and baseline correction; the IV characteristic curve is drawn, and the ferroelectric domain flipping charge quantity is 1.07×10 -9 C, and the coercive voltage is 2.2V, indicating that the KNN film has good domain flipping capability and is suitable for high-frequency ferroelectric device application.

[0073] The above-mentioned embodiments are only preferred embodiments of the present application, and cannot be used to limit the protection scope of the present application, and any non-essential changes and replacements made by those skilled in the art on the basis of the present application all belong to the protection scope of the present application.

Claims

1. A novel method of ultrafast IV testing ferroelectric materials, characterized by, Includes the following steps: S1: Construct a novel ultrafast IV test system: a waveform generator / fast measurement unit (WGFMU) and two remote sensing and switching units (RSU) are used. The WGFMU is connected to the two RSUs via cables, and the two RSUs are connected to the probe station of the sample test platform to achieve synchronous control of voltage excitation signal and current acquisition signal. S2: Sample preparation: Ferroelectric samples were prepared by pulsed laser deposition (PLD). Samples with surface flatness <0.5μm and thickness tolerance ±5nm were selected. They were ultrasonically cleaned with 40kHz anhydrous ethanol for 3min and deionized water for 3min in sequence, and then treated with oxygen plasma. S3: Test parameter settings: Input specific voltage signal waveforms and test parameters in the test system settings interface. The voltage signal waveforms include sine waves, square waves, or triangular waves. The test parameters include voltage amplitude range, frequency, sampling frequency of the data acquisition and analysis module, and number of sampling points. S4: Ultrafast pulse transient IV test: Place the ferroelectric material sample prepared in step S2 on the sample test platform, make the sample in close contact with the probe, and then start the test; S5: Data Processing and Analysis: The data acquisition and analysis module preprocesses the acquired raw data, plots the N-characteristic curve of the ferroelectric material sample based on the preprocessed data, extracts key performance parameters from the N-characteristic curve, and performs analysis and evaluation.

2. A method of a novel ultrafast IV testing ferroelectric material according to claim 1, wherein, In step S1, the synchronization accuracy of the voltage excitation signal and current acquisition signal implemented by the WGFMU and the two RSUs is less than 1ps. The voltage output range of the test system is -5V to 5V, 0V to 10V, or -10V to 0V, with a noise floor of less than 0.1mV. The current range is ±10mA to ±1μA. The test resolution is 0.00014 of the range, the noise floor is 0.2 of the range, the sampling interval is 5ns, 10ns to 1s (variable), the hardware mean is 10ns to 20ms (variable), and the measurement memory depth is approximately 4 million data points per channel.

3. A novel method of ultrafast IV testing ferroelectric materials as claimed in claim 1, wherein, In step S2, PLD is used to deposit the electrode. After the electrode is deposited, it is annealed at 180°C for 30 minutes under nitrogen protection. The electrode is selected as a gold electrode or a platinum electrode. For high-frequency testing, a gold electrode with a thickness of 50 nm is preferred.

4. The novel ultrafast IV testing method for ferroelectric materials according to claim 1, characterized in that, In step S2, when the ferroelectric sample is prepared by PLD pulsed laser deposition, the excimer laser is used, the laser frequency is controlled at 10 Hz-50 Hz, the energy density is controlled at 1.0-2.5 J / cm 2 , the distance between the target and the base is 5 cm, the substrate temperature is controlled at 600-700 DEG C during the deposition process, the oxygen pressure is maintained at 15-35 Pa, the film thickness is fixed at 100-400 nm, and after deposition, in-situ annealing is performed for 15 minutes and then cooled to room temperature.

5. The novel ultrafast IV testing method for ferroelectric materials according to claim 1, characterized in that, In step S3, the test parameters also include limiting the voltage and current, and the operating mode is set to FastIV mode, with one RSU used to apply the voltage and the other RSU used to detect the current.

6. A novel method of ultrafast IV testing ferroelectric materials as claimed in claim 1, wherein, In step S3, the test parameters also include the total measurement time and the number of repetition cycles. The number of repetition cycles is set to 1 by default and can be adjusted according to test requirements.

7. The novel ultrafast IV testing method for ferroelectric materials according to claim 1, characterized in that, In step S3, the sampling test start time, the number of sampling test points, and the average sampling time for each point are also edited in the test event bar. After setting, observe the empty acquisition waveform. If there is a deviation, re-check the edited values ​​and test conditions.

8. The method of claim 1, wherein the new ultrafast IV testing ferroelectric material is characterized by, In step S4, during the test, the WGFMU is controlled to apply a set ultrafast voltage excitation signal to the sample, and the current signal generated by the sample is detected in real time through the RSU. The current signal is then transmitted to the data acquisition and analysis module, which synchronously acquires and records the voltage and current signals.

9. A novel ultrafast IV testing method for ferroelectric materials according to claim 1, characterized in that, In step S5, the preprocessing includes noise removal and baseline correction, and the key performance parameters include leakage current density, peak switching current, coercive voltage, and dielectric constant.

10. A novel ultrafast IV testing method for ferroelectric materials according to claim 1, characterized in that, In step S5, the charge value is obtained by integrating different parts of the characteristic curve of Ⅳ, and it is determined that the charge is generated during the ferroelectric domain switching process, thereby evaluating the switching characteristics of the ferroelectric material.

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