Method for characterizing polarization switching in a multi-state memory device based on atomic force microscopy

Abstract

This application provides a method for characterizing polarization switching in multi-mode memory devices based on atomic force microscopy (AFM), applicable to the technical field of multi-mode memory device detection. The method includes: acquiring amplitude and phase signals; the amplitude and phase signals are acquired during the application of electrical scanning pulse signals to a predetermined region of the multi-mode memory device under test using an AFM, the electrical scanning pulse signals including multiple voltage signals; determining an amplitude curve based on the amplitude and electrical scanning pulse signals; determining a phase curve based on the phase and electrical scanning pulse signals; and extracting key parameters of polarization switching in the multi-mode memory device under test based on the amplitude and phase curves; the key parameters include amplitude peak characteristics and phase change characteristics. The embodiments of this application can provide intuitive and quantitative analysis of polarization switching in multi-mode memory devices, providing direct experimental basis for optimizing device design and performance evaluation.

Description

Technical Field

[0001] This application relates to the technical field of multi-state storage device detection, and more particularly to a method for characterizing polarization switching in multi-state storage devices based on atomic force microscopy. Background Technology

[0002] With the explosive growth of information and data volume, the development of high-density, low-power, and non-volatile storage technologies is crucial. Polymorphic memories (such as multi-state phase-change memories and multi-state resistive switching memories) can significantly improve storage density by storing two or more logical states in a single memory cell, representing an important future direction for storage technology. Among these, polarization-flipping-based polymorphic memory devices (such as ferroelectric domain wall memories and multi-level polarized ferroelectric tunnel junctions) have attracted considerable attention due to their high speed, low power consumption, and excellent durability. The core physical mechanism of these devices is the multi-level, controllable flipping of polarization domains in the material under the influence of an external electric field. While traditional hysteresis loop testing methods are mature, they suffer from limitations such as interface and edge effect interference, difficulty in obtaining real-time switching dynamics, and difficulty in identifying multiple loops, making it difficult to perform intuitive and quantitative analysis of the polarization switching of polymorphic memory devices. Summary of the Invention

[0003] In view of this, embodiments of this application provide a method for characterizing polarization switching in multi-state memory devices based on atomic force microscopy, in order to solve the problem that traditional hysteresis loop testing methods in the prior art are difficult to perform intuitive and quantitative analysis of polarization switching in multi-state memory devices.

[0004] A first aspect of this application provides a method for characterizing polarization switching in a multi-state storage device based on atomic force microscopy, comprising:

[0005] Amplitude and phase signals are acquired; the amplitude and phase signals are acquired during the application of electrical scanning pulse signals to a predetermined region of the multi-state memory device under test by the atomic force microscope, and the electrical scanning pulse signals include multiple voltage signals; The amplitude curve is determined based on the amplitude signal and the electrical scanning pulse signal; the amplitude curve is used to characterize the amplitude change corresponding to each voltage signal. The phase curve is determined based on the phase signal and the electrical scanning pulse signal; the amplitude curve is used to characterize the phase change corresponding to each voltage signal. Based on amplitude and phase curves, key parameters of polarization switching in the multi-state storage device under test are extracted; key parameters include amplitude peak characteristics and phase change characteristics.

[0006] In one possible implementation, after extracting the key parameters of polarization switching in the multi-state storage device under test based on the amplitude and phase curves, the following are included: Based on key parameters, the physical properties of the multi-state storage device under test are determined; the physical properties include the number of polarization states of the multi-state storage device under test.

[0007] In one possible implementation, the amplitude peak characteristics include the number of amplitude peaks, and the phase change characteristics include the number of phase flips and / or the number of hysteresis loops; Based on key parameters, the physical properties of the multi-state storage device under test are determined, including: If the number of phase flips is greater than 1, then the multi-state storage device under test is determined to have a polarization material with multi-state storage. If the number of peak amplitudes is M, the number of phase reversals is M, and / or the number of hysteresis loops is M / 2, then the number of polarization states of the multi-state memory device under test is M; M is a multiple of 2.

[0008] In one possible implementation, the predetermined area includes at least two test points; Acquire amplitude and phase signals, including: acquiring amplitude and phase signals for each test point; After extracting the key parameters of polarization switching in the multi-mode storage device under test based on the amplitude curve and phase curve, the method also includes: evaluating the uniformity of the multi-mode storage device under test based on the key parameters corresponding to each test point.

[0009] In one possible implementation, the method for characterizing polarization switching in multi-state storage devices based on atomic force microscopy further includes at least one of the following: The dwell time of each voltage signal is 10 milliseconds to 500 milliseconds; When an electrical scanning pulse signal is applied to a predetermined area of ​​the multi-state memory device under test, the atomic force microscope is in the switch-spectral piezoelectric response force microscope test mode. The electrical scanning pulse signal is a stepped voltage signal, which includes N voltage signals, where N is an integer not less than 3; The thickness of the functional layer of the multi-state memory device under test is positively correlated with the number of polarization states of the multi-state memory device under test.

[0010] A second aspect of this application provides an apparatus for characterizing polarization switching in a multi-state memory device based on atomic force microscopy, comprising: The acquisition module is used to acquire amplitude and phase signals. The amplitude and phase signals are acquired during the process of applying electrical scanning pulse signals to a predetermined area of ​​the multi-state storage device under test by the atomic force microscope. The electrical scanning pulse signals include multiple voltage signals. The first determining module is used to determine the amplitude curve based on the amplitude signal and the electrical scanning pulse signal; the amplitude curve is used to characterize the amplitude change corresponding to each voltage signal; The second determining module is used to determine the phase curve based on the phase signal and the electrical scanning pulse signal; the amplitude curve is used to characterize the phase change corresponding to each voltage signal. The extraction module is used to extract key parameters of polarization switching in the multi-state storage device under test based on the amplitude curve and the phase curve; the key parameters include amplitude peak characteristics and phase change characteristics.

[0011] A third aspect of this application provides a terminal device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method of this application.

[0012] A fourth aspect of this application provides a system for characterizing polarization switching in multi-state storage devices based on atomic force microscopy, comprising: Atomic force microscope main unit; A signal generator, located in the main unit of the atomic force microscope, is used to apply an electrical scanning pulse signal to a predetermined area of ​​the multi-state storage device under test; A lock-in amplifier, located in the main unit of an atomic force microscope, is used to acquire the amplitude and phase signals of the multi-state memory device under test during the process of applying an electrical scanning pulse signal to a predetermined area of ​​the multi-state memory device under test by the signal generator. The data processing unit is used to acquire amplitude and phase signals; the electrical scanning pulse signal includes multiple voltage signals; based on the amplitude signal and the electrical scanning pulse signal, an amplitude curve is determined; the amplitude curve is used to characterize the amplitude change corresponding to each voltage signal; based on the phase signal and the electrical scanning pulse signal, a phase curve is determined; the amplitude curve is used to characterize the phase change corresponding to each voltage signal; based on the amplitude and phase curves, key parameters of polarization switching in the multi-state storage device under test are extracted; the key parameters include amplitude peak characteristics and phase change characteristics.

[0013] In one possible implementation, the system for characterizing polarization switching in a multi-state storage device based on atomic force microscopy further includes at least one of the following: The signal generator is used to apply a stepped voltage signal to a predetermined region of the multi-state memory device under test; The atomic force microscope main unit is used to perform switch-spectral piezoelectric response force microscopy tests at different drive frequencies of electrical scanning pulse signals.

[0014] A fifth aspect of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the method of the first aspect.

[0015] Compared with the prior art, the embodiments of this application have at least the following technical effects: The method for characterizing polarization switching in a multi-state memory device based on atomic force microscopy (AFM) in the first aspect of this application can acquire amplitude and phase signals. Since the amplitude and phase signals are acquired during the application of electrical scanning pulse signals to a predetermined region of the multi-state memory device under test using AFM, this application allows for direct observation and quantitative analysis of the initialization, writing (polarization flipping), reading, and retention processes of polarization domains at the nanoscale. Then, based on the amplitude and electrical scanning pulse signals, this application can determine an amplitude curve, which characterizes the amplitude change corresponding to each voltage signal; and based on the phase and electrical scanning pulse signals, it can determine a phase curve, which characterizes the phase change corresponding to each voltage signal. This enables real-time imaging and spectroscopic analysis of piezoelectric effects and polarization switching within a local area. Furthermore, based on the amplitude and phase curves, this application can extract key parameters such as the amplitude peak characteristics and phase change characteristics of polarization switching in the multi-state memory device under test. Therefore, the embodiments of this application achieve high spatial resolution and in-situ dynamic characterization of the polarization domain structure, multi-level switching paths, and reliability of multi-state memory devices. This allows for intuitive and quantitative analysis of polarization switching in multi-state memory devices, providing direct experimental evidence for optimizing device design and performance evaluation. Furthermore, the embodiments of this application, by directly observing and quantitatively analyzing the initialization, writing (polarization flipping), reading, and retention processes of polarization domains at the nanoscale, are crucial for understanding device mechanisms, optimizing materials and structures, and evaluating reliability and performance limits.

[0016] It is understood that the beneficial effects of the second to fifth aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a flowchart of a method for characterizing polarization switching in a multi-state storage device based on atomic force microscopy, provided in an embodiment of this application. Figure 2a This is a schematic diagram illustrating the writing and reading of voltage signals of a polymorphic memory device according to an embodiment of this application. Figure 2b This is a schematic diagram of six polarization states of a multi-state memory device according to embodiment 1 of this application. Figure 3aThis is a schematic diagram of the amplitude curve corresponding to the polymorphic storage device in test embodiment 1 provided in this application; Figure 3b This is a schematic diagram of the phase curve corresponding to the polymorphic storage device in Test Embodiment 1 provided in this application; Figure 4a This is a schematic diagram of the amplitude curve corresponding to the antiferroelectric storage device in Test Embodiment 2 provided in this application; Figure 4b This is a schematic diagram of the phase curve corresponding to the antiferroelectric storage device in Test Embodiment 2 provided in this application; Figure 5a This is a schematic diagram of the amplitude curve corresponding to the antiferroelectric storage device in test embodiment 3 provided in this application; Figure 5b This is a schematic diagram of the phase curve corresponding to the antiferroelectric storage device in test embodiment 3 provided in this application; Figure 6 This is a schematic diagram of a device for characterizing polarization switching in a multi-state memory device based on atomic force microscopy, provided in an embodiment of this application. Figure 7 This is a schematic diagram of the structure of a terminal device provided in an embodiment of this application. Detailed Implementation

[0019] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0020] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0021] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0022] In the description of this application, unless otherwise stated, the " / " used in this specification and appended claims indicates that the related objects are in an "or" relationship. For example, A / B can mean A or B. The "and / or" in this application merely describes the relationship between the related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, a and b, a and c, b and c, or a, b, and c. Here, a, b, and c can be single or multiple.

[0023] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0024] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0025] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0026] The technical solution of this application and how it solves the above-mentioned technical problems are described in detail below with specific embodiments. It should be noted that the following embodiments can be referenced, borrowed, or combined with each other, and the same terms, similar features, and similar implementation steps in different embodiments will not be described again.

[0027] See Figure 1 As shown, this application provides a flowchart of a method for characterizing polarization switching in multi-state memory devices based on atomic force microscopy. Figure 1 As shown, the method for characterizing polarization switching in a multi-state memory device based on atomic force microscopy according to the embodiments of this application includes steps S101 to S104.

[0028] S101. Acquire amplitude and phase signals; the amplitude and phase signals are acquired during the process of applying electrical scanning pulse signals to a predetermined area of ​​the multi-state storage device under test using an atomic force microscope. The electrical scanning pulse signals include multiple voltage signals.

[0029] Optionally, the amplitude and phase signals can be acquired by the lock-in amplifier of the atomic force microscope, and the electrical scanning pulse signal can be generated by the signal generator and output through the conductive probe.

[0030] Among them, the amplitude signal mainly reflects the magnitude of the piezoelectric response, and the phase signal mainly reflects the polarization direction.

[0031] Alternatively, the atomic force microscope can be a switch-spectral piezoelectric response force microscope (SS). PFM (Piezoelectric Response Microscopy), a nanoscale piezoelectric and polarization response testing method, uses a conductive probe to locally couple with the sample. It can use a lock-in amplifier to detect the probe's micro-amplitude and phase signals with high sensitivity, thereby realizing real-time imaging and spectroscopic analysis of piezoelectric effects and polarization switching in a local area.

[0032] In some embodiments, the method for characterizing polarization switching in a multi-state storage device based on atomic force microscopy further includes at least one of the following: The dwell time for each voltage signal is 10 milliseconds to 500 milliseconds.

[0033] When an electrical scanning pulse signal is applied to a predetermined area of ​​the multi-state memory device under test, the atomic force microscope is in the switch-spectral piezoelectric response force microscope test mode.

[0034] The electrical scanning pulse signal is a stepped voltage signal, which includes N voltage signals, where N is an integer not less than 3; The thickness of the functional layer of the multi-state memory device under test is positively correlated with the number of polarization states of the multi-state memory device under test.

[0035] The dwell time can be 10 milliseconds, 250 milliseconds, or 500 milliseconds. The numerical ranges in this application embodiment all include the endpoint values. Other numerical ranges in this application embodiment will not be described or exemplified.

[0036] Optionally, the number of polarization states of the multi-state memory device under test can be 2, 4, or 6 states, etc. The greater the thickness of the functional layer, the more likely the multi-state memory device under test will have more polarization states.

[0037] Optionally, the electrical scanning pulse signal can be a bipolar step or a triangular wave step, etc.

[0038] S102. Determine the amplitude curve based on the amplitude signal and the electrical scanning pulse signal; the amplitude curve is used to characterize the amplitude change corresponding to each voltage signal.

[0039] S103. Based on the phase signal and the electrical scanning pulse signal, determine the phase curve; the amplitude curve is used to characterize the phase change corresponding to each voltage signal.

[0040] S104. Based on the amplitude curve and phase curve, extract the key parameters of polarization switching in the multi-state storage device under test; the key parameters include amplitude peak characteristics and phase change characteristics.

[0041] Optionally, the amplitude peak characteristics include the number of amplitude peaks, the phase change characteristics include the number of phase flips, and the phase change characteristics may also include phase difference and the number of hysteresis loops, etc.

[0042] Optionally, the peak amplitude is extracted for each amplitude closed loop of the amplitude curve, and the phase difference and the number of phase reversals are statistically analyzed for the phase curve.

[0043] In some embodiments, after extracting key parameters of polarization switching in the multi-state storage device under test based on amplitude and phase curves, the process includes: Based on key parameters, the physical properties of the multi-state storage device under test are determined; the physical properties include the number of polarization states of the multi-state storage device under test.

[0044] The number of polarization states of the multi-state memory device under test can be 2, 4, or 6 states, etc.

[0045] In some embodiments, the amplitude peak characteristics include the number of amplitude peaks, and the phase change characteristics include the number of phase flips and / or the number of hysteresis loops; Based on key parameters, the physical properties of the multi-state storage device under test are determined, including: If the number of phase flips is greater than 1, then the multi-state storage device under test is determined to have a polarization material with multi-state storage. If the number of peak amplitudes is M, the number of phase reversals is M, and / or the number of hysteresis loops is M / 2, then the number of polarization states of the multi-state memory device under test is M; M is a multiple of 2.

[0046] For example, if a multi-state memory device under test (MSD) has two hysteresis loops, then the number of peak amplitudes is 4, the number of phase flips is 4, and the number of polarization states of the MSD is 4. The principle is the same for the number of polarization states of other MSDs.

[0047] Based on the above steps S101 to S104, the method for characterizing polarization switching in a polymorphic memory device based on atomic force microscopy in this application embodiment can acquire amplitude signals and phase signals. Since the amplitude signals and phase signals are acquired during the process of applying an electrical scanning pulse signal to a predetermined area of ​​the polymorphic memory device under test by atomic force microscopy, this application embodiment can directly observe and quantitatively analyze the initialization, writing (polarization flipping), reading and holding processes of polarization domains at the nanoscale.

[0048] Then, the embodiments of this application can determine the amplitude curve based on the amplitude signal and the electrical scanning pulse signal. The amplitude curve is used to characterize the amplitude change corresponding to each voltage signal. Based on the phase signal and the electrical scanning pulse signal, the phase curve is determined. The amplitude curve is used to characterize the phase change corresponding to each voltage signal. Real-time imaging and spectroscopic analysis of piezoelectric effect and polarization switching can be realized in a local area.

[0049] Furthermore, embodiments of this application can extract key parameters such as the amplitude peak characteristics and phase change characteristics of polarization switching in the multi-state storage device under test based on the amplitude curve and phase curve.

[0050] Therefore, the embodiments of this application achieve high spatial resolution and in-situ dynamic characterization of the polarization domain structure, multi-level switching path and reliability of multi-state memory devices. It can perform intuitive and quantitative analysis of the polarization switching of multi-state memory devices, and provide direct experimental basis for optimizing device design and performance evaluation.

[0051] Meanwhile, the embodiments of this application directly observe and quantitatively analyze the initialization, writing (polarization flipping), reading and holding processes of polarization domains at the nanoscale, which is crucial for understanding device mechanisms, optimizing materials and structures, and evaluating reliability and performance limits.

[0052] This application provides a complete SS (System-on-Demand) implementation for multi-state memory devices under test. The PFM testing scheme and data processing method provide powerful tools and methodological support for the basic research and device optimization of multistable polarization systems.

[0053] To address the problems of difficulty in quantitatively determining multi-state memory devices and lack of multi-stable polarization information in existing technologies, this application aims to provide a detection technology based on atomic force microscopy using a switch-spectral piezoelectric response force microscopy mode. By scanning amplitude and phase spectroscopic signals multiple times and combining the amplitude peak and phase flipping multiple times, the local polarization characteristics of multi-state memory devices can be accurately identified and characterized.

[0054] In some embodiments, the predetermined area includes at least two test points; acquiring amplitude and phase signals includes: acquiring amplitude and phase signals for each test point; After extracting the key parameters of polarization switching in the multi-mode storage device under test based on the amplitude curve and phase curve, the method also includes: evaluating the uniformity of the multi-mode storage device under test based on the key parameters corresponding to each test point.

[0055] Optionally, 5-10 adjacent test points can be set up in the same predetermined area for repeated testing to evaluate uniformity. If the key parameters extracted for each test point are consistent and the number of polarization states of the multi-mode storage device under test is consistent, then the multi-mode storage device under test has uniformity and the reliability of the test results.

[0056] This embodiment connects the multi-state memory device under test (MSD) to an external bias circuit and places it on an atomic force microscope (AFM) stage. Using a conductive probe, a series of electrical scanning pulses with specific amplitudes and pulse widths are applied to a specific region of the device in switched spectral piezoelectric response force microscopy (SS-PFM) mode. The local piezoelectric response signal under each pulse is simultaneously acquired and analyzed, including amplitude and phase signals. By analyzing the evolution of the amplitude and phase curves, key parameters such as the number of amplitude peaks and phase reversals corresponding to each stable polarization state are quantitatively extracted. This embodiment achieves high spatial resolution and in-situ dynamic characterization of the polarization domain structure, multi-level switching paths, and reliability of the MSD, providing direct experimental evidence for optimizing device design and performance evaluation.

[0057] This application provides a system for characterizing polarization switching in multi-state storage devices based on atomic force microscopy, including: an atomic force microscope host, a signal generator, a lock-in amplifier, and a data processing unit.

[0058] The signal generator is located in the main unit of the atomic force microscope. The signal generator is used to apply an electrical scanning pulse signal to a predetermined area of ​​the multi-state storage device under test. The electrical scanning pulse signal can be output through a conductive probe.

[0059] The lock-in amplifier is located in the main unit of the atomic force microscope. The lock-in amplifier is used to acquire the amplitude signal and phase signal of the multi-state memory device under test during the process of the signal generator applying an electrical scanning pulse signal to a predetermined area of ​​the multi-state memory device under test.

[0060] The data processing unit is used to acquire amplitude and phase signals; the electrical scanning pulse signal includes multiple voltage signals; based on the amplitude signal and the electrical scanning pulse signal, the amplitude curve is determined; the amplitude curve is used to characterize the amplitude change corresponding to each voltage signal; based on the phase signal and the electrical scanning pulse signal, the phase curve is determined; the amplitude curve is used to characterize the phase change corresponding to each voltage signal; based on the amplitude and phase curves, the key parameters of polarization switching in the multi-state storage device under test are extracted; the key parameters include amplitude peak characteristics and phase change characteristics.

[0061] Alternatively, the data processing unit can be an external terminal device. For example, the terminal device can be a computing device such as a desktop computer, laptop, handheld computer, or cloud server.

[0062] In some embodiments, a system for characterizing polarization switching in a multi-state storage device based on atomic force microscopy further includes at least one of the following: The signal generator is used to apply a stepped voltage signal to a predetermined region of the multi-state memory device under test; The atomic force microscope main unit is used to perform switch-spectral piezoelectric response force microscopy tests at different drive frequencies of electrical scanning pulse signals.

[0063] Among them, the stepped voltage signal can be a bipolar step or a triangular wave step, etc.

[0064] The atomic force microscope host of this application embodiment also has a frequency scanning function, which can perform switch-spectral piezoelectric response force microscope tests at different driving frequencies.

[0065] In practical applications, polarimetric material samples with multi-state storage are fixed on the conductive stage of an atomic force microscope and connected to the bottom conductive electrode. A conductive atomic force microscope probe is assembled, set to the on / off spectral piezoelectric response force microscope mode, and the voltage sequence parameters of the stepped voltage signal are programmed: voltage range ±V. max The step size ΔV, dwell time τ, and number of cycles are N. N stepped voltage cycles are continuously applied at the same test point or within a predetermined area, and the amplitude A(V) and phase of each voltage step are simultaneously acquired. (V) represents the amplitude signal and the phase signal. The peak amplitude is extracted for each amplitude closed loop, and the phase difference and the number of phase reversals are statistically analyzed from the phase curve.

[0066] Furthermore, embodiments of this application provide specific steps for a method of characterizing polarization switching in a multi-state memory device based on atomic force microscopy, including: (1) Sample preparation: Take the pre-prepared polymorphic storage device, fix it on the stage of the atomic force microscope, and make good contact with the conductive bottom electrode.

[0067] (2) Instrument configuration: Equip a conductive probe in the atomic force microscope and connect a signal generator and a lock-in amplifier. Set the switch-spectral piezoelectric response force microscope mode to realize the periodic application of step-like voltage scanning of the probe in the target micro-region, while simultaneously acquiring local amplitude and phase signals.

[0068] (3) Testing Procedure: Pre-scan positioning: Scan the sample surface morphology in a voltage-free mode and select a flat area without obvious particles or scratches; SS PFM multi-cycle scanning: N voltage cycles are repeatedly applied at the same scan point or small area, with the voltage increasing / decreasing in step size ΔV from negative to positive and then back to negative, and a dwell time τ is applied in each step to ensure polarization switching saturation; Signal acquisition: The amplitude A (V) and phase of each voltage step are simultaneously recorded using a lock-in amplifier. (V), thus obtaining the complete multi-cycle amplitude and phase spectrum; Data storage: The amplitude and phase values ​​of each step are saved as multi-cycle spectroscopic curves; Repeated validation: Repeat the test at 5-10 adjacent points in the same area to assess uniformity.

[0069] Data processing and judgment methods include: Amplitude multi-extreme value identification: In each loop, draw the A (V) loop, extract the peak amplitude of each loop, and use the obvious differences between the multiple loops (such as the position shift of the second loop and the area change) to determine the number of multi-stable loops in order to identify the hysteresis loop.

[0070] Phase flipping determination: analysis The abrupt change point in the (V) curve is counted, and the number of phase flips (nflip) in each cycle is counted (ideally, a single loop is a 180° flip, while multiple loops will have multiple flips or local oscillations).

[0071] In summary, this application has at least the following beneficial technical effects: 1. Nanoscale spatial resolution for precise capture of multi-loop features in micro-areas. Traditional macroscopic electrode testing cannot distinguish polarization circuits in different micro-regions within a sample. However, this application utilizes an atomic force microscope (AFM) conductive probe to directly contact the sample surface, enabling the detection of localized polarization behavior at sub-micron and even nanoscale levels. The probe's tip radius is typically less than 20 nm, resulting in a highly localized driving electric field. Furthermore, multiple cyclic stepwise scans can be performed at the same point or within a defined micro-region, allowing for the complete capture of the amplitude and phase responses of the first, second, and higher-order circuits within that micro-region. This avoids the loss or aliasing of multi-circuit information caused by macroscopic signal averaging.

[0072] 2. Dual-spectral synchronous acquisition improves the reliability of multi-loop determination. Amplitude A (V) and Phase (V) reflects the piezoelectric strength and polarization direction reversal of the material, respectively. This application simultaneously acquires two signals and cross-verifies the multiple amplitude maxima and multiple phase reversals, resulting in a very high signal-to-noise ratio and robustness in the determination of multiple loops. Even if the amplitude peak of a certain loop is slightly weakened due to material defects, it can still be reconfirmed through the phase reversal signal, significantly reducing the probability of false multi-loop misjudgment.

[0073] 3. Suppress pseudo-multi-loop interference and improve judgment accuracy. In macroscopic testing, surface passivation layers, interface traps, and leakage currents often cause shoulder peaks or segmentation in the hysteresis loop, leading to misclassification as a multi-loop signal. This application addresses this issue through a dual-spectral approach: if a spurious peak appears in the amplitude but there is no corresponding phase reversal, it can be ruled out as a false loop; conversely, if no spurious peak appears, it can be ruled out as a false loop. A template matching algorithm is introduced to perform least-squares fitting on an ideal multi-loop template, further enhancing the ability to identify real multi-loop signals and ensuring high accuracy in the judgment results.

[0074] The following embodiments of this application characterize the thickness-dependent properties of different storage devices by combining different functional layers of different thicknesses.

[0075] Test Example 1 This embodiment uses atomic force microscopy to characterize multi-state memory devices, where the thickness of the functional layer PbZrO3 thin film is 320 nm.

[0076] 1. Sample preparation Mount the device onto the sample stage, ensuring a good electrical connection. Select a conductive atomic force microscope probe and set it to the on / off spectral piezoelectric response force microscope mode to ensure stable contact between the probe and the device surface.

[0077] 2. Instrument parameters (1) Probe: SCM PIT, elastic modulus ≈ 2N / m; (2) Operation mode: SS PFM; (3) Step voltage: ±19V, step size ΔV=0.5V, stable dwell time τ=50ms, number of cycles N=5; (4) Driving frequency: f = 17kHz; (5) Sampling: The lock-in amplifier synchronously records the amplitude A (V) and phase. (V).

[0078] 3. Testing Process (1) Low-voltage (±1V) scanning was used to obtain the surface morphology and select flat micro-areas; (2) Apply five stepped voltage cycles at the same point and record the amplitude and phase of each step. (3) Repeat the same area for 5 adjacent points to assess uniformity.

[0079] 4. Data Results and Analysis See Figure 2a As shown in the figure, this application provides a schematic diagram of writing and reading voltage signals of a multi-state memory device in test embodiment 1. Figure 2a In the middle, the interval time t Ret This corresponds to the time interval between a single write and read operation. See also... Figure 2b As shown in the figure, this application provides a schematic diagram of six polarization states of a multi-state memory device of test embodiment 1. stateA, stateB, stateC, stateC', stateB', and stateA' correspond to the six polarization states, respectively.

[0080] See Figure 3a and 3b As shown, embodiments of this application provide schematic diagrams of amplitude and phase curves corresponding to the multi-state memory device in test embodiment 1. The amplitude response results show six distinct peaks, which is a unique amplitude response observed for the first time in a PbZrO3-based multi-state memory device. Figure 3a The phase signal results show three hysteresis loops with a phase difference of approximately 180°, corresponding to the amplitude response results. Figure 3b This result confirms the observation of six polarization states in PbZrO3-based polymorphic storage devices.

[0081] Test Example 2 This embodiment uses atomic force microscopy to characterize antiferroelectric memory devices, wherein the thickness of the functional layer PbZrO3 film is 240 nm.

[0082] 1. Sample preparation Mount the device onto the sample stage, ensuring a good electrical connection. Select a conductive atomic force microscope probe and set it to the on / off spectral piezoelectric response force microscope mode to ensure stable contact between the probe and the device surface.

[0083] 2. Instrument parameters (1) Probe: SCM PIT, elastic modulus ≈ 2N / m; (2) Operation mode: SS PFM; (3) Step voltage: ±19V, step size ΔV=0.5V, stable dwell time τ=50ms, number of cycles N=5; (4) Driving frequency: f = 17kHz; (5) Sampling: The lock-in amplifier synchronously records the amplitude A (V) and phase. (V).

[0084] 3. Testing Process (1) Low-voltage (±1V) scanning was used to obtain the surface morphology and select flat micro-areas; (2) Apply five stepped voltage cycles at the same point and record the amplitude and phase of each step. (3) Repeat the same area for 5 adjacent points to assess uniformity.

[0085] 4. Data Results and Analysis See Figure 4a and 4b As shown, this application provides schematic diagrams of amplitude and phase curves corresponding to the antiferroelectric storage device in test embodiment 2. The amplitude response results show that in addition to having two obvious peaks, it also exhibits an additional folding phenomenon ( Figure 4a The phase signal results show a single hysteresis loop with a phase difference of approximately 180°, and also exhibit additional torsional phenomena. Figure 4b ).

[0086] Test Example 3 This embodiment uses atomic force microscopy to characterize antiferroelectric memory devices, wherein the thickness of the functional layer PbZrO3 film is 160 nm.

[0087] 1. Sample preparation Mount the device onto the sample stage, ensuring a good electrical connection. Select a conductive atomic force microscope probe and set it to the on / off spectral piezoelectric response force microscope mode to ensure stable contact between the probe and the device surface.

[0088] 2. Instrument parameters (1) Probe: SCM PIT, elastic modulus ≈ 2N / m; (2) Operation mode: SS PFM; (3) Step voltage: ±19V, step size ΔV=0.5V, stable dwell time τ=50ms, number of cycles N=5; (4) Driving frequency: f = 17kHz; (5) Sampling: The lock-in amplifier synchronously records the amplitude A (V) and phase. (V).

[0089] 3. Testing Process (1) Low-voltage (±1V) scanning was used to obtain the surface morphology and select flat micro-areas; (2) Apply five stepped voltage cycles at the same point and record the amplitude and phase of each step. (3) Repeat the same area for 5 adjacent points to assess uniformity.

[0090] 4. Data Results and Analysis See Figure 5a and 5b As shown, this application provides schematic diagrams of the amplitude and phase curves corresponding to the antiferroelectric storage device in test embodiment 3. The amplitude response results show two distinct peaks ( Figure 5a The phase signal results show a single hysteresis loop with a phase difference of approximately 180°. Figure 5b ).

[0091] See Figure 6 As shown, this application provides a schematic diagram of the structure of a device 60 for characterizing polarization switching in a multi-state memory device using atomic force microscopy. Figure 6 As shown, the apparatus 60 for characterizing polarization switching in a multi-state storage device based on atomic force microscopy includes: an acquisition module 601, a first determination module 602, a second determination module 603, and an extraction module 604.

[0092] The acquisition module 601 is used to acquire amplitude signals and phase signals; the amplitude signals and phase signals are acquired during the process of applying electrical scanning pulse signals to a predetermined area of ​​the multi-state storage device under test by the atomic force microscope, and the electrical scanning pulse signals include multiple voltage signals.

[0093] The first determining module 602 is used to determine the amplitude curve based on the amplitude signal and the electrical scanning pulse signal; the amplitude curve is used to characterize the amplitude change corresponding to each voltage signal.

[0094] The second determining module 603 is used to determine the phase curve based on the phase signal and the electrical scanning pulse signal; the amplitude curve is used to characterize the phase change corresponding to each voltage signal.

[0095] The extraction module 604 is used to extract key parameters of polarization switching in the multi-state storage device under test based on the amplitude curve and the phase curve; the key parameters include amplitude peak characteristics and phase change characteristics.

[0096] Optionally, the apparatus 60 for characterizing polarization switching in a multi-state storage device based on atomic force microscopy further includes: a third determining module, which is used to determine the physical properties of the multi-state storage device under test based on key parameters; the physical properties include the number of polarization states of the multi-state storage device under test.

[0097] Optionally, the amplitude peak characteristics include the number of amplitude peaks, and the phase change characteristics include the number of phase flips and / or the number of hysteresis loops; The third determining module is used to determine that the multi-state storage device under test has a polarization material with multi-state storage if the number of phase reversals is greater than 1; if the number of peak amplitudes is M, the number of phase reversals is M, and / or the number of hysteresis loops is M / 2, then the number of polarization states of the multi-state storage device under test is M; M is a multiple of 2.

[0098] Optionally, the predetermined area includes at least two test points; the acquisition module 601 is used to acquire amplitude and phase signals for each test point; The apparatus 60 for characterizing polarization switching in a multi-mode storage device using atomic force microscopy further includes an evaluation module for evaluating the uniformity of the multi-mode storage device under test based on key parameters corresponding to each test point.

[0099] In applications, the modules in the device 60 for characterizing polarization switching in multi-state storage devices based on atomic force microscopy can be software program modules, or they can be implemented by different logic circuits integrated in a processor, or they can be implemented by multiple distributed processors.

[0100] See Figure 7 As shown, this application provides a schematic diagram of the structure of a terminal device 70. Figure 7 As shown, the terminal device 70 of this application embodiment includes: a memory 72, a processor 71, and a computer program 73 stored in the memory 72 and executable on the processor 71. When the processor 71 executes the computer program, it implements the steps of the methods of the various embodiments of this application.

[0101] Terminal device 70 can be a computing device such as a desktop computer, laptop, handheld computer, or cloud server. Terminal device 70 may include, but is not limited to, a processor 71 and a memory 72. Those skilled in the art will understand that terminal device 70 may also include more or fewer components, or combinations of certain components, or different components, such as input / output devices, network access devices, etc.

[0102] The processor 71 can be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0103] In some embodiments, memory 72 may be an internal storage unit, such as a hard disk or RAM. Memory 72 may be a removable / non-removable, volatile / non-volatile computer system storage medium; for example, memory 72 may be a non-volatile memory used for reading and writing non-volatile magnetic media. In other embodiments, memory 72 may be an external storage device, such as a plug-in hard disk, smart media card (SMC), secure digital card (SD), flash card, etc., provided on terminal device 70. Memory 72 is used to store operating systems, applications, bootloaders, data, and other programs, such as program code for computer programs. Memory 72 may also be used to temporarily store data that has been output or will be output.

[0104] It should be noted that the information interaction and execution process between the above-mentioned devices / units are based on the same concept as the method embodiments of this application. For details on their specific functions and technical effects, please refer to the method embodiments section, and they will not be repeated here.

[0105] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0106] This application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps in the above-described method embodiments.

[0107] If the integrated units described above are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include at least: any entity or device capable of carrying computer program code to a device / terminal equipment, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium. Examples include USB flash drives, portable hard drives, magnetic disks, or optical disks.

[0108] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc. The storage medium can also include combinations of the above types of memory.

[0109] This application provides a computer program product that, when run on a processor, enables the processor to execute the steps described in the various method embodiments above.

[0110] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0111] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0112] In the embodiments provided in this application, it should be understood that the disclosed apparatus / network devices and methods can be implemented in other ways. For example, the apparatus / network device embodiments described above are merely illustrative. For instance, the division of modules or units described above is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0113] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0114] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for characterizing polarization switching in multi-state storage devices based on atomic force microscopy, characterized in that, include: Amplitude and phase signals are acquired; the amplitude and phase signals are acquired during the application of electrical scanning pulse signals to a predetermined region of the multi-state storage device under test by the atomic force microscope, and the electrical scanning pulse signals include multiple voltage signals; The amplitude curve is determined based on the amplitude signal and the electrical scanning pulse signal; The amplitude curve is used to characterize the amplitude change corresponding to each voltage signal; Based on the phase signal and the electrical scanning pulse signal, a phase curve is determined; the amplitude curve is used to characterize the phase change corresponding to each voltage signal. Based on the amplitude curve and the phase curve, key parameters of polarization switching in the multi-state storage device under test are extracted; the key parameters include amplitude peak characteristics and phase change characteristics.

2. The method for characterizing polarization switching in multi-state storage devices based on atomic force microscopy according to claim 1, characterized in that, After extracting the key parameters of polarization switching in the multi-state storage device under test based on the amplitude curve and the phase curve, the process includes: Based on the key parameters, the physical properties of the multi-state memory device under test are determined; the physical properties include the number of polarization states of the multi-state memory device under test.

3. The method for characterizing polarization switching in multi-state storage devices based on atomic force microscopy according to claim 2, characterized in that, The amplitude peak characteristics include the number of amplitude peaks, and the phase change characteristics include the number of phase flips and / or the number of hysteresis loops; The process of determining the physical properties of the multi-state storage device under test based on the key parameters includes: If the number of phase flips is greater than 1, then the multi-state storage device under test is determined to have a polarization material for multi-state storage; If the number of peak amplitudes is M, the number of phase reversals is M, and / or the number of hysteresis loops is M / 2, then the number of polarization states of the multi-state memory device under test is M; where M is a multiple of 2.

4. The method for characterizing polarization switching in multi-state storage devices based on atomic force microscopy according to any one of claims 1-3, characterized in that, The predetermined area includes at least two test points; The acquisition of amplitude and phase signals includes: acquiring amplitude and phase signals for each of the test points; After extracting the key parameters of polarization switching in the multi-mode storage device under test based on the amplitude curve and the phase curve, the method further includes: evaluating the uniformity of the multi-mode storage device under test based on the key parameters corresponding to each test point.

5. The method for characterizing polarization switching in multi-state storage devices based on atomic force microscopy according to any one of claims 1-3, characterized in that, It also includes at least one of the following: The dwell time of each voltage signal is 10 milliseconds to 500 milliseconds; When an electrical scanning pulse signal is applied to a predetermined area of ​​the multi-state memory device under test, the atomic force microscope is in the switch-spectral piezoelectric response force microscope test mode. The electrical scanning pulse signal is a stepped voltage signal, which includes N voltage signals, where N is an integer not less than 3; The thickness of the functional layer of the polymorphic memory device under test is positively correlated with the number of polarization states of the polymorphic memory device under test.

6. A device for characterizing polarization switching in multi-state storage devices using atomic force microscopy, characterized in that, include: An acquisition module is used to acquire amplitude signals and phase signals; the amplitude signals and phase signals are acquired during the process of applying an electrical scanning pulse signal to a predetermined area of ​​the multi-state storage device under test by the atomic force microscope, and the electrical scanning pulse signal includes multiple voltage signals; The first determining module is used to determine the amplitude curve based on the amplitude signal and the electrical scanning pulse signal; The amplitude curve is used to characterize the amplitude change corresponding to each voltage signal; The second determining module is used to determine a phase curve based on the phase signal and the electrical scanning pulse signal; the amplitude curve is used to characterize the phase change corresponding to each voltage signal. An extraction module is used to extract key parameters of polarization switching in the multi-state storage device under test based on the amplitude curve and the phase curve; the key parameters include amplitude peak characteristics and phase change characteristics.

7. A terminal device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method as described in any one of claims 1 to 5.

8. A system for characterizing polarization switching in multi-state storage devices using atomic force microscopy, characterized in that, include: Atomic force microscope main unit; A signal generator, located in the main unit of the atomic force microscope, is used to apply an electrical scanning pulse signal to a predetermined area of ​​the multi-state storage device under test; A lock-in amplifier, located in the main unit of the atomic force microscope, is used to acquire the amplitude signal and phase signal of the multi-state memory device under test during the process of the signal generator applying an electrical scanning pulse signal to a predetermined area of ​​the multi-state memory device under test; A data processing unit is used to acquire amplitude signals and phase signals; the electrical scanning pulse signal includes multiple voltage signals; based on the amplitude signals and the electrical scanning pulse signal, an amplitude curve is determined; the amplitude curve is used to characterize the amplitude change corresponding to each voltage signal; based on the phase signals and the electrical scanning pulse signal, a phase curve is determined; the amplitude curve is used to characterize the phase change corresponding to each voltage signal; based on the amplitude curve and the phase curve, key parameters of polarization switching in the multi-state storage device under test are extracted; the key parameters include amplitude peak characteristics and phase change characteristics.

9. The system for characterizing polarization switching in multi-state memory devices based on atomic force microscopy according to claim 8, characterized in that, It also includes at least one of the following: The signal generator is used to apply a stepped voltage signal to a predetermined region of the multi-state memory device under test; The atomic force microscope host is used to perform switch-spectral piezoelectric response force microscopy tests at different driving frequencies of the electrical scanning pulse signal.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method as described in any one of claims 1 to 5.

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