Test methods for the imprinting effect of ferroelectric capacitors

Abstract

This application provides a method for testing the imprinting effect of a ferroelectric capacitor. The method includes: applying a varying electric field to the ferroelectric capacitor under test at a first predetermined temperature, and detecting a first polarization intensity and a second polarization intensity; baking the ferroelectric capacitor under test at a second predetermined temperature greater than the first predetermined temperature for a predetermined time to obtain a baked ferroelectric capacitor under test; applying a varying electric field to the baked ferroelectric capacitor under test at the first predetermined temperature, and detecting a third polarization intensity and a fourth polarization intensity; calculating the rate of change of the residual polarization intensity based on the first, second, third, and fourth polarization intensities, whereby the rate of change of the residual polarization intensity characterizes the degree of imprinting effect on the baked ferroelectric capacitor under test. This method achieves quantitative analysis of the imprinting effect, thereby solving the problem of difficulty in quantitatively analyzing the imprinting effect in the prior art.

Description

Technical Field

[0001] This application relates to the field of microelectronics technology, and more specifically, to a method for testing the imprinting effect of ferroelectric capacitors. Background Technology

[0002] Ferroelectric RAM (FRAM) is a new type of memory that combines the easy-to-write characteristics of DRAM and SRAM with the non-volatile characteristics of Flash and EEPROM. It can store data without the need for a refresh circuit.

[0003] The core component of a ferroelectric memory is the ferroelectric capacitor. Ferroelectric capacitors typically have a MIM (Metal-Insulated Metal-Metal) structure, with two metal layers serving as capacitor electrodes and a ferroelectric thin film formed from ferroelectric material in the middle. Exhibiting the ferroelectric effect, under the influence of an external electric field on the upper and lower electrodes, the iron domains of the ferroelectric material exhibit different polarization states depending on the direction of the electric field. Simultaneously, the capacitance of the dielectric changes with the polarization state, resulting in the amount of charge stored in the capacitor varying with the polarization direction and magnitude. Furthermore, since the polarization intensity of the ferroelectric material remains even after the external electric field is removed, the capacitor possesses non-volatile charge storage capability, enabling data storage.

[0004] When a ferroelectric memory is working, the iron domains (polarization) of the ferroelectric capacitor continuously reverse, maintaining a stable state after power is off, thus completing the reading and writing of "0" and "1". When the ferroelectric capacitor ages from one state to another, the iron domains cannot reverse, and the ferroelectric capacitor remains in the original state. This will lead to reading and writing errors in the "0" and "1" states or failure due to the inability to read or write, resulting in the imprint effect.

[0005] Currently, conventional assessments of the imprint effect only focus on qualitative analysis of whether imprints cause failures. With the development and increasing demand for ferroelectric memory, quantitatively assessing the degree of FRAM imprints is an indispensable aspect of evaluating its reliability.

[0006] The information disclosed above in the background section is only intended to enhance the understanding of the background art of the art described herein. Therefore, the background art may contain certain information that does not constitute prior art known to those skilled in the art in this country. Summary of the Invention

[0007] The main objective of this application is to provide a test method for the imprinting effect of ferroelectric capacitors, so as to solve the problem that it is difficult to quantitatively analyze the imprinting effect in the prior art.

[0008] To achieve the above objectives, according to one aspect of this application, a method for testing the imprinting effect of a ferroelectric capacitor is provided, comprising: applying a changing electric field to the ferroelectric capacitor under test at a first predetermined temperature, and detecting the polarization intensity at a first moment and a second moment to obtain the first polarization intensity and the second polarization intensity, wherein the first moment is the moment when the electric field increases from a positive minimum value to a positive maximum value and then decreases to 0, and the second moment is the moment when the electric field increases from a negative minimum value to a negative maximum value and then decreases to 0, wherein the positive minimum value is greater than or equal to 0, and the negative minimum value is greater than or equal to 0; and then applying the ferroelectric capacitor under test... The ferroelectric capacitor under test is baked at a second predetermined temperature for a predetermined time to obtain a baked ferroelectric capacitor under test. The second predetermined temperature is greater than the first predetermined temperature. At the first predetermined temperature, a changing electric field is applied to the baked ferroelectric capacitor under test, and the polarization intensity at the first moment and the polarization intensity at the second moment are detected to obtain a third polarization intensity and a fourth polarization intensity. The rate of change of the residual polarization intensity is calculated based on the first polarization intensity, the second polarization intensity, the third polarization intensity, and the fourth polarization intensity. The rate of change of the residual polarization intensity is used to characterize the degree of imprinting effect of the baked ferroelectric capacitor under test.

[0009] Optionally, based on the rate of change of the residual polarization intensity according to the first polarization intensity, the second polarization intensity, the third polarization intensity, and the fourth polarization intensity, the method includes: calculating the difference between the first polarization intensity and the second polarization intensity to obtain a first residual polarization intensity; calculating the difference between the third polarization intensity and the fourth polarization intensity to obtain a second residual polarization intensity; calculating the difference between the first residual polarization intensity and the second residual polarization intensity to obtain a change in the residual polarization intensity; and calculating the ratio of the change in the residual polarization intensity to the first residual polarization intensity to obtain the rate of change of the residual polarization intensity.

[0010] Optionally, the method further includes: at the first predetermined temperature, during the process of the electric field applied to the ferroelectric capacitor under test increasing from the positive minimum value to the positive maximum value, detecting the coercive field when the polarization intensity of the ferroelectric capacitor under test is 0, to obtain a first coercive field; at the first predetermined temperature, during the process of the electric field applied to the baked ferroelectric capacitor under test increasing from the positive minimum value to the positive maximum value, detecting the coercive field when the polarization intensity of the ferroelectric capacitor under test is 0, to obtain a second coercive field; calculating the absolute value of the difference between the second coercive field and the first coercive field to obtain a first coercive field drift value, wherein the first coercive field drift value is also used to characterize the degree to which the imprinting effect occurs in the baked ferroelectric capacitor under test.

[0011] Optionally, the method further includes: at the first predetermined temperature, during the process of the electric field applied to the ferroelectric capacitor under test increasing from the negative minimum value to the negative maximum value, detecting the coercive field when the polarization intensity of the ferroelectric capacitor under test is 0, to obtain a third coercive field; at the first predetermined temperature, during the process of the electric field applied to the baked ferroelectric capacitor under test increasing from the negative minimum value to the negative maximum value, detecting the coercive field when the polarization intensity of the ferroelectric capacitor under test is 0, to obtain a fourth coercive field; calculating the absolute value of the difference between the fourth coercive field and the third coercive field to obtain a second coercive field drift value, the second coercive field drift value also being used to characterize the degree to which the imprinting effect occurs in the baked ferroelectric capacitor under test.

[0012] Optionally, both the positive minimum value and the negative minimum value are equal to 0.

[0013] Optionally, applying a varying electric field to the ferroelectric capacitor under test includes applying the electric field of a triangular waveform to the ferroelectric capacitor under test.

[0014] Optionally, the first predetermined temperature is between 15 and 30°C.

[0015] Optionally, the second predetermined temperature is between 60 and 150°C, and the predetermined duration is between 5 and 200 hours.

[0016] According to another aspect of this application, a method for testing the imprinting effect of a ferroelectric capacitor is provided, comprising: acquiring polarization intensity at a first moment and polarization intensity at a second moment during a first detection process, thereby obtaining a first polarization intensity and a second polarization intensity, wherein the first detection process is a detection process in which a changing electric field is applied to the ferroelectric capacitor under test at a first predetermined temperature, the first moment being the moment when the electric field increases from a positive minimum value to a positive maximum value and then decreases to 0, and the second moment being the moment when the electric field increases from a negative minimum value to a negative maximum value and then decreases to 0, wherein the positive minimum value is greater than or equal to 0, and the negative minimum value is greater than or equal to 0; acquiring the second polarization intensity... The polarization intensity at the first moment and the polarization intensity at the second moment during the measurement process are used to obtain the third polarization intensity and the fourth polarization intensity. The second detection process is a detection process in which a changing electric field is applied to the baked ferroelectric capacitor under test at the first predetermined temperature. The baked ferroelectric capacitor under test is obtained by baking the ferroelectric capacitor under test at the second predetermined temperature for a predetermined time. The rate of change of the residual polarization intensity is calculated based on the first polarization intensity, the second polarization intensity, the third polarization intensity, and the fourth polarization intensity. The rate of change of the residual polarization intensity is used to characterize the degree of imprinting effect of the baked ferroelectric capacitor under test.

[0017] Optionally, based on the rate of change of the residual polarization intensity according to the first polarization intensity, the second polarization intensity, the third polarization intensity, and the fourth polarization intensity, the method includes: calculating the difference between the first polarization intensity and the second polarization intensity to obtain a first residual polarization intensity; calculating the difference between the third polarization intensity and the fourth polarization intensity to obtain a second residual polarization intensity; calculating the difference between the first residual polarization intensity and the second residual polarization intensity to obtain a change in the residual polarization intensity; and calculating the ratio of the change in the residual polarization intensity to the first residual polarization intensity to obtain the rate of change of the residual polarization intensity.

[0018] Optionally, the method further includes: obtaining a first coercive field when the polarization intensity of the ferroelectric capacitor under test is 0 during the process of the electric field applied to the ferroelectric capacitor under test increasing from the positive minimum value to the positive maximum value; obtaining a second coercive field when the polarization intensity of the ferroelectric capacitor under test is 0 during the process of the electric field applied to the baked ferroelectric capacitor under test increasing from the positive minimum value to the positive maximum value; calculating the absolute value of the difference between the second coercive field and the first coercive field to obtain a first coercive field drift value, wherein the first coercive field drift value is also used to characterize the degree to which the imprinting effect occurs in the baked ferroelectric capacitor under test.

[0019] Optionally, the method further includes: obtaining a third coercive field when the polarization intensity of the ferroelectric capacitor under test is 0 during the process of the electric field applied to the ferroelectric capacitor under test increasing from the negative minimum value to the negative maximum value; obtaining a fourth coercive field when the polarization intensity of the ferroelectric capacitor under test is 0 during the process of the electric field applied to the baked ferroelectric capacitor under test increasing from the negative minimum value to the negative maximum value; calculating the absolute value of the difference between the fourth coercive field and the third coercive field to obtain a second coercive field drift value, wherein the second coercive field drift value is also used to characterize the degree of imprinting effect occurring in the baked ferroelectric capacitor under test.

[0020] Applying the technical solution of this application, in the test method for the imprinting effect of the ferroelectric capacitor, firstly, at a first predetermined temperature, a changing electric field is applied to the ferroelectric capacitor under test, and the polarization intensity at a first moment and a second moment are detected, i.e., the first polarization intensity and the second polarization intensity. The first moment is the moment when the electric field increases from a positive minimum value to a positive maximum value and then decreases to 0, and the second moment is the moment when the electric field increases from a negative minimum value to a negative maximum value and then decreases to 0. The positive minimum value is greater than or equal to 0, and the negative minimum value is greater than or equal to 0. Then, the ferroelectric capacitor under test is subjected to a temperature greater than... The ferroelectric capacitor under test is baked at a first predetermined temperature for a predetermined time to obtain a baked ferroelectric capacitor under test. Then, at the first predetermined temperature, a changing electric field is applied to the baked ferroelectric capacitor under test, and the polarization intensity at the first moment and the second moment is detected to obtain a third polarization intensity and a fourth polarization intensity. The rate of change of the residual polarization intensity is calculated based on the first polarization intensity, the second polarization intensity, the third polarization intensity, and the fourth polarization intensity. The rate of change of the residual polarization intensity is used to characterize the degree to which the imprinting effect occurs in the baked ferroelectric capacitor under test. This method utilizes the fact that high temperatures can accelerate the aging of ferroelectric capacitors. The aged ferroelectric capacitors exhibit an imprinting effect, hindering polarization reversal and consequently reducing the residual polarization intensity. The rate of change of the residual polarization intensity is increased. This method calculates the rate of change of the residual polarization intensity based on the polarization intensity of normal ferroelectric capacitors and ferroelectric capacitors that have undergone baking treatment when the electric field increases from a positive minimum to a positive maximum and then decreases to 0, and when the electric field increases from a negative minimum to a negative maximum and then decreases to 0. This rate of change of the residual polarization intensity characterizes the degree of imprinting effect in aged ferroelectric capacitors, thus achieving quantitative analysis of the imprinting effect and solving the problem of difficulty in quantitatively analyzing the imprinting effect in existing technologies. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0022] Figure 1 A flowchart is shown of a test method for the imprinting effect of a ferroelectric capacitor according to an embodiment of this application;

[0023] Figure 2 A cell structure diagram of a ferroelectric memory according to an embodiment of this application is shown;

[0024] Figure 3 A graph showing the electric field scanning voltage and time of a triangular waveform according to an embodiment of this application is provided.

[0025] Figure 4 A diagram showing the polarization intensity and coercive field relationship of a ferroelectric memory according to an embodiment of this application is illustrated.

[0026] Figure 5 A diagram showing the relationship between the coercive field and the switching current of a ferroelectric memory according to an embodiment of this application is illustrated.

[0027] Figure 6 A flowchart is shown of a test method for the imprinting effect of a ferroelectric capacitor according to another embodiment of this application.

[0028] The above figures include the following reference numerals:

[0029] 10. Transistor; 20. Ferroelectric capacitor; 30. Bit line; 40. Plate line; 101. Silicon substrate; 102. Gate; 103. Source. Detailed Implementation

[0030] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element may be directly on the other element, or there may be an intermediate element present. Furthermore, in the specification and claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element, or "connected" to the other element via a third element.

[0033] As described in the background section, it is difficult to quantitatively analyze the imprinting effect in the prior art. In order to solve the above problem, this application provides a test method for the imprinting effect of ferroelectric capacitors.

[0034] In one typical embodiment of this application, a method for testing the imprinting effect of a ferroelectric capacitor is provided.

[0035] Figure 1This is a flowchart of a test method for the imprinting effect of a ferroelectric capacitor according to an embodiment of this application. Figure 1 As shown, the method includes the following steps:

[0036] Step S101: At a first predetermined temperature, a changing electric field is applied to the ferroelectric capacitor to be tested, and the polarization intensity at a first moment and a second moment is detected to obtain the first polarization intensity and the second polarization intensity. The first moment is the moment when the electric field increases from a positive minimum value to a positive maximum value and then decreases to 0. The second moment is the moment when the electric field increases from a negative minimum value to a negative maximum value and then decreases to 0. The positive minimum value is greater than or equal to 0, and the negative minimum value is greater than or equal to 0.

[0037] Step S102: The ferroelectric capacitor to be tested is baked at a second predetermined temperature for a predetermined time to obtain the baked ferroelectric capacitor to be tested, wherein the second predetermined temperature is greater than the first predetermined temperature.

[0038] Step S103: At the first predetermined temperature, a changing electric field is applied to the baked ferroelectric capacitor to be tested, and the polarization intensity at the first moment and the polarization intensity at the second moment are detected to obtain the third polarization intensity and the fourth polarization intensity.

[0039] Step S104: Calculate the rate of change of the residual polarization intensity based on the first polarization intensity, the second polarization intensity, the third polarization intensity, and the fourth polarization intensity. The rate of change of the residual polarization intensity is used to characterize the degree of imprinting effect of the ferroelectric capacitor under test after baking.

[0040] In the above-mentioned method for testing the imprinting effect of a ferroelectric capacitor, firstly, at a first predetermined temperature, a changing electric field is applied to the ferroelectric capacitor under test, and the polarization intensity at a first moment and a second moment is detected to obtain the first polarization intensity and the second polarization intensity. The first moment is the moment when the electric field increases from a positive minimum value to a positive maximum value and then decreases to 0, and the second moment is the moment when the electric field increases from a negative minimum value to a negative maximum value and then decreases to 0. The positive minimum value is greater than or equal to 0, and the negative minimum value is greater than or equal to 0. Afterwards, the ferroelectric capacitor under test is baked at a second predetermined temperature. For a period of time, the ferroelectric capacitor under test is baked to a temperature greater than the first predetermined temperature. Then, at the first predetermined temperature, a varying electric field is applied to the baked ferroelectric capacitor under test, and the polarization intensity at the first moment and the second moment is detected to obtain the third polarization intensity and the fourth polarization intensity. Finally, the rate of change of the residual polarization intensity is calculated based on the first polarization intensity, the second polarization intensity, the third polarization intensity and the fourth polarization intensity. The rate of change of the residual polarization intensity is used to characterize the degree of imprinting effect of the baked ferroelectric capacitor under test. This method utilizes the fact that high temperatures can accelerate the aging of ferroelectric capacitors. The aged ferroelectric capacitors exhibit an imprinting effect, hindering polarization reversal and consequently reducing the residual polarization intensity. The rate of change of the residual polarization intensity is increased. Based on the polarization intensity of normal ferroelectric capacitors and ferroelectric capacitors that have undergone baking treatment at the moments when the electric field increases from a positive minimum to a positive maximum and then decreases to 0, and at the moments when the electric field increases from a negative minimum to a negative maximum and then decreases to 0, the method can calculate the rate of change of the residual polarization intensity. This rate of change of the residual polarization intensity can characterize the degree of imprinting effect in aged ferroelectric capacitors, thus achieving quantitative analysis of the imprinting effect and solving the problem of difficulty in quantitatively analyzing the imprinting effect in existing technologies.

[0041] It should be noted that the applied changing electric field to the ferroelectric capacitor under test in this application is applied between the two plates of the capacitor.

[0042] In one specific embodiment of this application, the aforementioned ferromagnetic memory can be based on a 1T1C cell structure, such as... Figure 2As shown, it includes a selection switch transistor 10 (1T) and a stacked hafnium oxide-based ferroelectric capacitor 20 (1C), as well as upper and lower TIN electrodes connected to the ferroelectric capacitor 20. The gate 102 of the transistor is the word line WL of the memory cell, and the source 103 of the transistor is connected to the bit line 30BL of the cell. The source 103 of the transistor is connected to the external electrode of the ferroelectric capacitor 20 through an alloy junction between the metal and the active region of the silicon substrate 101. The plate line 40PL is connected to the lower electrode of the ferroelectric capacitor 20 through a via. The upper and lower electrodes of the ferroelectric capacitor 20 are titanium nitride, and the high dielectric constant medium in the middle is a zirconium-doped hafnium oxide thin film. This thin film is grown by atomic layer deposition (ALD) and has a thickness of 6-10 nanometers. The doping ratio of zirconium, hafnium and oxygen is about 0.5:0.5:2.

[0043] To more accurately calculate the rate of change of the remanent polarization intensity, in one embodiment of this application, the rate of change of the remanent polarization intensity based on the first polarization intensity, the second polarization intensity, the third polarization intensity, and the fourth polarization intensity includes: calculating the difference between the first polarization intensity and the second polarization intensity to obtain a first remanent polarization intensity; calculating the difference between the third polarization intensity and the fourth polarization intensity to obtain a second remanent polarization intensity; calculating the difference between the first remanent polarization intensity and the second remanent polarization intensity to obtain the change in the remanent polarization intensity; and calculating the ratio of the change in the remanent polarization intensity to the first remanent polarization intensity to obtain the rate of change of the remanent polarization intensity. Based on the difference between the first polarization intensity and the second polarization intensity, the residual polarization intensity of the ferroelectric capacitor under test, i.e., the first residual polarization intensity, can be accurately calculated. Similarly, based on the difference between the third polarization intensity and the fourth polarization intensity, the residual polarization intensity of the baked ferroelectric capacitor under test, i.e., the second residual polarization intensity, can be accurately calculated. The difference between the two is then calculated to obtain the change in residual polarization intensity. Finally, the ratio of the change in residual polarization intensity to the first residual polarization intensity can be calculated to accurately obtain the rate of change of residual polarization intensity.

[0044] Specifically, the first polarization intensity is Pr1, the second polarization intensity is Pr2, the third polarization intensity is Pr3, and the fourth polarization intensity is Pr4. Then, the change in the residual polarization intensity Δ2Pr = (Pr1-Pr2)-(Pr3-Pr4), and the rate of change of the residual polarization intensity Δ2Pr% = [(Pr1-Pr2)-(Pr3-Pr4)*100%] / [(Pr1-Pr2)].

[0045] In another embodiment of this application, the method further includes: at the first predetermined temperature, during the process of the electric field applied to the ferroelectric capacitor under test increasing from the positive minimum value to the positive maximum value, detecting the coercive field when the polarization intensity of the ferroelectric capacitor under test is 0, and obtaining a first coercive field; at the first predetermined temperature, during the process of the electric field applied to the baked ferroelectric capacitor under test increasing from the positive minimum value to the positive maximum value, detecting the coercive field when the polarization intensity of the ferroelectric capacitor under test is 0, and obtaining a second coercive field; calculating the absolute value of the difference between the second coercive field and the first coercive field, and obtaining a first coercive field drift value, which is also used to characterize the degree of imprinting effect of the baked ferroelectric capacitor under test. Under the action of the imprinting effect, the polarization reversal of the ferroelectric capacitor is hindered, and the drift of the coercive field will also increase. Only by applying an external positive electric field to overcome the material coercive field can domain reversal be achieved. Therefore, the change value of the coercive field further characterizes the degree of imprinting effect.

[0046] Specifically, the first coercive field is Ec1, the second coercive field is Ec2, and the first coercive drift value ΔEc1 = |Ec1 - Ec2|.

[0047] In another embodiment of this application, the method further includes: at the first predetermined temperature, during the process of the electric field applied to the ferroelectric capacitor under test increasing from the negative minimum value to the negative maximum value, detecting the coercive field when the polarization intensity of the ferroelectric capacitor under test is 0, to obtain a third coercive field; at the first predetermined temperature, during the process of the electric field applied to the baked ferroelectric capacitor under test increasing from the negative minimum value to the negative maximum value, detecting the coercive field when the polarization intensity of the ferroelectric capacitor under test is 0, to obtain a fourth coercive field; calculating the absolute value of the difference between the fourth coercive field and the third coercive field to obtain a second coercive field drift value, which is also used to characterize the degree of imprinting effect of the baked ferroelectric capacitor under test. Under the action of the imprinting effect, the polarization reversal of the ferroelectric capacitor is hindered, and the drift of the coercive field also increases. Only by applying an external negative electric field to overcome the material's coercive field can domain reversal be achieved. Therefore, the change value of the coercive field further characterizes the degree of the imprinting effect.

[0048] Specifically, the second coercive field is Ec3, the third coercive field is Ec4, and the second coercive drift value ΔEc2 = |Ec3 - Ec4|.

[0049] In order to obtain the complete relationship between polarization intensity and scanning voltage, in another embodiment of this application, both the above-mentioned positive minimum value and the above-mentioned negative minimum value are equal to 0.

[0050] In another embodiment of this application, applying a changing electric field to the ferroelectric capacitor under test includes applying a triangular waveform electric field to the ferroelectric capacitor under test. The triangular waveform electric field changes linearly with time. By completing one cycle of triangular waveform scanning on both the ferroelectric capacitor under test and the baked iron point memory under test, the first polarization intensity, second polarization intensity, third polarization intensity, fourth polarization intensity, first coercive field, and second coercive field can be obtained.

[0051] For ease of testing, the test is conducted at room temperature. In another embodiment of this application, the first predetermined temperature is between 15 and 30°C. Specifically, the first predetermined temperature can be 25°C. Of course, in actual applications, the first predetermined temperature is not limited to between 15 and 30°C, and can be other temperatures. Those skilled in the art can determine the appropriate temperature based on the specific circumstances.

[0052] In another embodiment of this application, the second predetermined temperature is between 60 and 150°C, and the predetermined duration is between 5 and 200 hours. Of course, in actual applications, the second predetermined temperature is not limited to between 60 and 150°C; it can be other temperatures, as determined by those skilled in the art based on the specific circumstances.

[0053] Specifically, the second predetermined temperature can be 125°C. The second predetermined temperature is the baking temperature of the ferroelectric capacitor to be tested. If the baking temperature is too low or the baking time is too short, the aging degree of the ferroelectric capacitor will be insufficient, the change in remanent polarization intensity and coercive field will be small, and the calculated value of the change rate of remanent polarization intensity and the change value of coercive field will have a large error. If the baking temperature is too high or the baking time is too long, it may damage the ferroelectric capacitor.

[0054] In another specific embodiment of this application, a triangular waveform electric field is applied to the above-mentioned ferroelectric capacitor under test, and the curve of scanning voltage and time is shown in the figure. Figure 3 As shown, the upper plate triangular wave scanning voltage is 2.5V, and the scanning frequency is 1kHz. The aim is to allow as many iron domains as possible to flip at the operating voltage of 2.5V. If the scanning frequency is too high, a large portion of the iron domains will not have enough time to flip, making it impossible to accurately assess the imprint extent. Ferroelectric capacitors at 25℃ and those baked at 125℃ for 96 hours were tested sequentially using the same scanning voltage and frequency to obtain the polarization intensity and coercive field relationship diagrams, as shown below. Figure 4 As shown, +Pr 25C -Pr is the first polarization intensity. 25C For the second polarization intensity, +Pr 125C For the third polarization intensity, -Pr 125C The fourth polarization intensity, +Ec 25C For the first coercive field, -Ec 25C For the third coercive field, +Ec125C For the second coercive field, -Ec 125C The fourth coercive field is used to collect polarization intensity that varies with the scanning single voltage and the instantaneous flipping current of the iron domains. Figure 5 Let E be the change in coercive field and flipping current of iron domains under the action of a triangular waveform electric field. The voltage corresponding to the maximum instantaneous flipping current of the iron domains is the coercive field ±Ec(and Figure 4 (same as the coercive field), also through Figure 4 Δ+EC and Δ-EC were quantitatively measured. The two tests were performed on the same sample.

[0055] In another typical embodiment of this application, a method for testing the imprinting effect of a ferroelectric capacitor is provided.

[0056] Figure 6 This is a flowchart of a test method for the imprinting effect of a ferroelectric capacitor according to another embodiment of this application. Figure 6 As shown, the method includes the following steps:

[0057] Step S201: Obtain the polarization intensity at the first moment and the polarization intensity at the second moment during the first detection process, and obtain the first polarization intensity and the second polarization intensity. The first detection process is a detection process in which a changing electric field is applied to the ferroelectric capacitor under test at a first predetermined temperature. The first moment is the moment when the electric field increases from the positive minimum value to the positive maximum value and then decreases to 0. The second moment is the moment when the electric field increases from the negative minimum value to the negative maximum value and then decreases to 0. The positive minimum value is greater than or equal to 0, and the negative minimum value is greater than or equal to 0.

[0058] Step S202: Obtain the polarization intensity at the first moment and the polarization intensity at the second moment during the second detection process to obtain the third polarization intensity and the fourth polarization intensity. The second detection process is a detection process in which a changing electric field is applied to the baked ferroelectric capacitor under test at the first predetermined temperature. The baked ferroelectric capacitor under test is obtained by baking the ferroelectric capacitor under test at the second predetermined temperature for a predetermined time.

[0059] Step S203: Calculate the rate of change of the residual polarization intensity based on the first polarization intensity, the second polarization intensity, the third polarization intensity, and the fourth polarization intensity. The rate of change of the residual polarization intensity is used to characterize the degree of imprinting effect of the ferroelectric capacitor under test after baking.

[0060] In the above-mentioned test method for the imprinting effect of ferroelectric capacitors, firstly, the polarization intensity at a first moment and a second moment in the first detection process are obtained to obtain the first polarization intensity and the second polarization intensity. The first detection process is a detection process in which a changing electric field is applied to the ferroelectric capacitor under test at a first predetermined temperature. The first moment is the moment when the electric field increases from a positive minimum value to a positive maximum value and then decreases to 0. The second moment is the moment when the electric field increases from a negative minimum value to a negative maximum value and then decreases to 0. The positive minimum value is greater than or equal to 0, and the negative minimum value is greater than or equal to 0. Then, the polarization intensity at a second moment in the second detection process is obtained. The polarization intensity at the first moment and the polarization intensity at the second moment are used to obtain the third polarization intensity and the fourth polarization intensity. The second detection process is a detection process in which a changing electric field is applied to the baked ferroelectric capacitor under test at the first predetermined temperature. The baked ferroelectric capacitor under test is obtained by baking the ferroelectric capacitor under test at the second predetermined temperature for a predetermined time. Finally, the rate of change of the residual polarization intensity is calculated based on the first polarization intensity, the second polarization intensity, the third polarization intensity and the fourth polarization intensity. The rate of change of the residual polarization intensity is used to characterize the degree of imprinting effect of the baked ferroelectric capacitor under test. This method utilizes the fact that high temperatures can accelerate the aging of ferroelectric capacitors. The aged ferroelectric capacitors exhibit an imprinting effect, hindering polarization reversal and consequently reducing the residual polarization intensity. The rate of change of the residual polarization intensity is increased. Based on the polarization intensity of normal ferroelectric capacitors and ferroelectric capacitors that have undergone baking treatment at the moments when the electric field increases from a positive minimum to a positive maximum and then decreases to 0, and at the moments when the electric field increases from a negative minimum to a negative maximum and then decreases to 0, the method can calculate the rate of change of the residual polarization intensity. This rate of change of the residual polarization intensity can characterize the degree of imprinting effect in aged ferroelectric capacitors, thus achieving quantitative analysis of the imprinting effect and solving the problem of difficulty in quantitatively analyzing the imprinting effect in existing technologies.

[0061] It should be noted that the applied changing electric field to the ferroelectric capacitor under test in this application is applied between the two plates of the capacitor.

[0062] To more accurately calculate the rate of change of the remanent polarization intensity, in another embodiment of this application, the rate of change of the remanent polarization intensity based on the first polarization intensity, the second polarization intensity, the third polarization intensity, and the fourth polarization intensity includes: calculating the difference between the first polarization intensity and the second polarization intensity to obtain a first remanent polarization intensity; calculating the difference between the third polarization intensity and the fourth polarization intensity to obtain a second remanent polarization intensity; calculating the difference between the first remanent polarization intensity and the second remanent polarization intensity to obtain the change in the remanent polarization intensity; and calculating the ratio of the change in the remanent polarization intensity to the first remanent polarization intensity to obtain the rate of change of the remanent polarization intensity. Based on the difference between the first polarization intensity and the second polarization intensity, the residual polarization intensity of the ferroelectric capacitor under test, i.e., the first residual polarization intensity, can be accurately calculated. Similarly, based on the difference between the third polarization intensity and the fourth polarization intensity, the residual polarization intensity of the baked ferroelectric capacitor under test, i.e., the second residual polarization intensity, can be accurately calculated. The difference between the two is then calculated to obtain the change in residual polarization intensity. Finally, the ratio of the change in residual polarization intensity to the first residual polarization intensity can be calculated to accurately obtain the rate of change of residual polarization intensity.

[0063] Specifically, the first polarization intensity is Pr1, the second polarization intensity is Pr2, the third polarization intensity is Pr3, and the fourth polarization intensity is Pr4. Then, the change in the residual polarization intensity Δ2Pr = (Pr1-Pr2)-(Pr3-Pr4), and the rate of change of the residual polarization intensity Δ2Pr% = [(Pr1-Pr2)-(Pr3-Pr4)*100%] / [(Pr1-Pr2)].

[0064] In another embodiment of this application, the method further includes: obtaining a first coercive field when the polarization intensity of the ferroelectric capacitor under test is 0 during the process of the electric field applied to the ferroelectric capacitor under test increasing from the positive minimum value to the positive maximum value; obtaining a second coercive field when the polarization intensity of the ferroelectric capacitor under test is 0 during the process of the electric field applied to the baked ferroelectric capacitor under test increasing from the positive minimum value to the positive maximum value; calculating the absolute value of the difference between the second coercive field and the first coercive field to obtain a first coercive field drift value, which is also used to characterize the degree of imprinting effect of the baked ferroelectric capacitor under test. Under the action of the imprinting effect, the polarization reversal of the ferroelectric capacitor is hindered, and the drift of the coercive field will also increase. Only by applying an external positive electric field to overcome the material coercive field can domain reversal be achieved. Therefore, the change value of the coercive field further characterizes the degree of imprinting effect.

[0065] Specifically, the first coercive field is Ec1, the second coercive field is Ec2, and the first coercive drift value ΔEc1 = |Ec1 - Ec2|.

[0066] In another embodiment of this application, the method further includes: obtaining a third coercive field when the polarization intensity of the ferroelectric capacitor under test is 0 during the process of the electric field applied to the ferroelectric capacitor under test increasing from the negative minimum value to the negative maximum value; obtaining a fourth coercive field when the polarization intensity of the ferroelectric capacitor under test is 0 during the process of the electric field applied to the baked ferroelectric capacitor under test increasing from the negative minimum value to the negative maximum value; calculating the absolute value of the difference between the fourth coercive field and the third coercive field to obtain a second coercive field drift value, wherein the second coercive field drift value is also used to characterize the degree to which the imprinting effect occurs in the baked ferroelectric capacitor under test.

[0067] Specifically, the second coercive field is Ec3, the third coercive field is Ec4, and the second coercive drift value ΔEc2 = |Ec3 - Ec4|.

[0068] In order to obtain the complete relationship between polarization intensity and scanning voltage, in another embodiment of this application, both the above-mentioned positive minimum value and the above-mentioned negative minimum value are equal to 0.

[0069] In another embodiment of this application, applying a changing electric field to the ferroelectric capacitor under test includes applying a triangular waveform electric field to the ferroelectric capacitor under test. The triangular waveform electric field changes linearly with time. By completing one cycle of triangular wave scanning on both the ferroelectric capacitor under test and the baked iron point memory under test, the first polarization intensity, second polarization intensity, third polarization intensity, fourth polarization intensity, first coercive field, and second coercive field can be obtained.

[0070] For ease of testing, the test is conducted at room temperature. In another embodiment of this application, the first predetermined temperature is between 15 and 30°C. Specifically, the first predetermined temperature can be 25°C. Of course, in actual applications, the first predetermined temperature is not limited to between 15 and 30°C; it can be other temperatures, which can be determined by those skilled in the art based on the actual situation.

[0071] In another embodiment of this application, the second predetermined temperature is between 60 and 150°C, and the predetermined duration is between 5 and 200 hours. Of course, in actual applications, the second predetermined temperature is not limited to between 60 and 150°C; it can be other temperatures, as determined by those skilled in the art based on the specific circumstances.

[0072] Specifically, the second predetermined temperature can be 125°C. The second predetermined temperature is the baking temperature of the ferroelectric capacitor to be tested. If the baking temperature is too low or the baking time is too short, the aging degree of the ferroelectric capacitor will be insufficient, the change in remanent polarization intensity and coercive field will be small, and the calculated value of the change rate of remanent polarization intensity and the change value of coercive field will have a large error. If the baking temperature is too high or the baking time is too long, it may damage the ferroelectric capacitor.

[0073] In another specific embodiment of this application, a triangular waveform electric field is applied to the aforementioned ferroelectric capacitor under test, such as... Figure 3 As shown, the upper plate triangular wave scanning voltage is 2.5V, and the scanning frequency is 1kHz. The purpose is to allow as many iron domains as possible to flip at the operating voltage of 2.5V. If the scanning frequency is too high, a large portion of the iron domains will not have enough time to flip, making it impossible to accurately assess the imprint extent. Ferroelectric capacitors at 25℃ and those baked at 125℃ for 96 hours were tested sequentially using the same scanning voltage and scanning frequency. The relationship between the polarization electric field and the scanning voltage was obtained, as shown in the figure. Figure 4 As shown, +Pr 25C -Pr is the first polarization intensity. 25C For the second polarization intensity, +Pr 125C For the third polarization intensity, -Pr 125C The fourth polarization intensity, +Ec 25C For the first coercive field, -Ec 25C For the third coercive field, +Ec 125C For the second coercive field, -Ec 125C The fourth coercive field is used to collect polarization intensity that varies with the scanning single voltage and the instantaneous flipping current of the iron domains. Figure 5 Let E be the change in coercive field and flipping current of iron domains under the action of a triangular waveform electric field. The voltage corresponding to the maximum instantaneous flipping current of the iron domains is the coercive field ±Ec(and Figure 4 (same as the coercive field), also through Figure 4 Δ+EC and Δ-EC were quantitatively measured. The two tests were performed on the same sample.

[0074] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0075] 1) In the method for testing the imprinting effect of the ferroelectric capacitor of this application, firstly, at a first predetermined temperature, a changing electric field is applied to the ferroelectric capacitor under test, and the polarization intensity at a first moment and a second moment is detected to obtain the first polarization intensity and the second polarization intensity. The first moment is the moment when the electric field increases from a positive minimum value to a positive maximum value and then decreases to 0, and the second moment is the moment when the electric field increases from a negative minimum value to a negative maximum value and then decreases to 0. The positive minimum value is greater than or equal to 0, and the negative minimum value is greater than or equal to 0. Afterwards, the ferroelectric capacitor under test is baked at a second predetermined temperature. For a predetermined time, the ferroelectric capacitor under test is baked at a temperature greater than the first predetermined temperature. Then, at the first predetermined temperature, a varying electric field is applied to the baked ferroelectric capacitor under test, and the polarization intensity at the first moment and the second moment is detected to obtain the third polarization intensity and the fourth polarization intensity. Finally, the rate of change of the residual polarization intensity is calculated based on the first polarization intensity, the second polarization intensity, the third polarization intensity, and the fourth polarization intensity. The rate of change of the residual polarization intensity is used to characterize the degree of imprinting effect of the baked ferroelectric capacitor under test. This method utilizes the fact that high temperatures can accelerate the aging of ferroelectric capacitors. The aged ferroelectric capacitors exhibit an imprinting effect, hindering polarization reversal and consequently reducing the residual polarization intensity. The rate of change of the residual polarization intensity is increased. Based on the polarization intensity of normal ferroelectric capacitors and ferroelectric capacitors that have undergone baking treatment at the moments when the electric field increases from a positive minimum to a positive maximum and then decreases to 0, and at the moments when the electric field increases from a negative minimum to a negative maximum and then decreases to 0, the method can calculate the rate of change of the residual polarization intensity. This rate of change of the residual polarization intensity can characterize the degree of imprinting effect in aged ferroelectric capacitors, thus achieving quantitative analysis of the imprinting effect and solving the problem of difficulty in quantitatively analyzing the imprinting effect in existing technologies.

[0076] 2) In the method for testing the imprinting effect of the ferroelectric capacitor of this application, firstly, the polarization intensity at a first moment and the polarization intensity at a second moment in the first detection process are obtained to obtain the first polarization intensity and the second polarization intensity. The first detection process is a detection process in which a changing electric field is applied to the ferroelectric capacitor under test at a first predetermined temperature. The first moment is the moment when the electric field increases from a positive minimum value to a positive maximum value and then decreases to 0. The second moment is the moment when the electric field increases from a negative minimum value to a negative maximum value and then decreases to 0. The positive minimum value is greater than or equal to 0, and the negative minimum value is greater than or equal to 0. Then, the polarization intensity at a second detection process is obtained... The polarization intensities at the first and second moments are used to obtain the third and fourth polarization intensities. The second detection process involves applying a changing electric field to the baked ferroelectric capacitor under test at the first predetermined temperature. The baked ferroelectric capacitor under test is obtained by baking the ferroelectric capacitor under test at the second predetermined temperature for a predetermined time. Finally, the rate of change of the residual polarization intensity is calculated based on the first, second, third, and fourth polarization intensities. The rate of change of the residual polarization intensity is used to characterize the degree of imprinting effect of the baked ferroelectric capacitor under test. This method utilizes the fact that high temperatures can accelerate the aging of ferroelectric capacitors. The aged ferroelectric capacitors exhibit an imprinting effect, hindering polarization reversal and consequently reducing the residual polarization intensity. The rate of change of the residual polarization intensity is increased. Based on the polarization intensity of normal ferroelectric capacitors and ferroelectric capacitors that have undergone baking treatment at the moments when the electric field increases from a positive minimum to a positive maximum and then decreases to 0, and at the moments when the electric field increases from a negative minimum to a negative maximum and then decreases to 0, the method can calculate the rate of change of the residual polarization intensity. This rate of change of the residual polarization intensity can characterize the degree of imprinting effect in aged ferroelectric capacitors, thus achieving quantitative analysis of the imprinting effect and solving the problem of difficulty in quantitatively analyzing the imprinting effect in existing technologies.

[0077] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for testing the imprinting effect of a ferroelectric capacitor, characterized in that, include: At a first predetermined temperature, a changing electric field is applied to the ferroelectric capacitor under test, and the polarization intensity at a first moment and a second moment is detected to obtain the first polarization intensity and the second polarization intensity. The first moment is the moment when the electric field increases from a positive minimum value to a positive maximum value and then decreases to 0. The second moment is the moment when the electric field increases from a negative minimum value to a negative maximum value and then decreases to 0. The positive minimum value is greater than or equal to 0, and the negative minimum value is greater than or equal to 0. The ferroelectric capacitor under test is baked at a second predetermined temperature for a predetermined time to obtain the baked ferroelectric capacitor under test, wherein the second predetermined temperature is greater than the first predetermined temperature. At the first predetermined temperature, a changing electric field is applied to the baked ferroelectric capacitor to be tested, and the polarization intensity at the first moment and the polarization intensity at the second moment are detected to obtain the third polarization intensity and the fourth polarization intensity. The rate of change of the residual polarization intensity is calculated based on the first polarization intensity, the second polarization intensity, the third polarization intensity, and the fourth polarization intensity. The rate of change of the residual polarization intensity is used to characterize the degree of imprinting effect of the ferroelectric capacitor under test after baking.

2. The test method according to claim 1, characterized in that, Based on the rate of change of the residual polarization intensity according to the first polarization intensity, the second polarization intensity, the third polarization intensity, and the fourth polarization intensity, including: The difference between the first polarization intensity and the second polarization intensity is calculated to obtain the first residual polarization intensity; The difference between the third polarization intensity and the fourth polarization intensity is calculated to obtain the second residual polarization intensity; Calculate the difference between the first residual polarization intensity and the second residual polarization intensity to obtain the change in residual polarization intensity; The ratio of the change in the residual polarization intensity to the first residual polarization intensity is calculated to obtain the rate of change of the residual polarization intensity.

3. The test method according to claim 1, characterized in that, The method further includes: At the first predetermined temperature, as the electric field applied to the ferroelectric capacitor under test increases from the positive minimum value to the positive maximum value, the coercive field when the polarization intensity of the ferroelectric capacitor under test is 0 is detected to obtain the first coercive field. At the first predetermined temperature, as the electric field applied to the baked ferroelectric capacitor under test increases from the positive minimum value to the positive maximum value, the coercive field when the polarization intensity of the ferroelectric capacitor under test is 0 is detected to obtain the second coercive field. The absolute value of the difference between the second coercive field and the first coercive field is calculated to obtain the first coercive field drift value. The first coercive field drift value is also used to characterize the degree of imprinting effect of the ferroelectric capacitor under test after baking.

4. The test method according to claim 1, characterized in that, The method further includes: At the first predetermined temperature, as the electric field applied to the ferroelectric capacitor under test increases from the negative minimum value to the negative maximum value, the coercive field when the polarization intensity of the ferroelectric capacitor under test is 0 is detected to obtain the third coercive field. At the first predetermined temperature, as the electric field applied to the baked ferroelectric capacitor under test increases from the negative minimum value to the negative maximum value, the coercive field when the polarization intensity of the ferroelectric capacitor under test is 0 is detected to obtain the fourth coercive field. The absolute value of the difference between the fourth coercive field and the third coercive field is calculated to obtain the second coercive field drift value. The second coercive field drift value is also used to characterize the degree of imprinting effect on the ferroelectric capacitor under test after baking.

5. The test method according to any one of claims 1 to 4, characterized in that, The first predetermined temperature is between 15 and 30°C.

6. The test method according to any one of claims 1 to 4, characterized in that, The second predetermined temperature is between 60 and 150°C, and the predetermined duration is between 5 and 200 hours.

7. A method for testing the imprinting effect of a ferroelectric capacitor, characterized in that, include: The polarization intensity at the first moment and the polarization intensity at the second moment in the first detection process are obtained to obtain the first polarization intensity and the second polarization intensity. The first detection process is a detection process in which a changing electric field is applied to the ferroelectric capacitor under test at a first predetermined temperature. The first moment is the moment when the electric field increases from a positive minimum value to a positive maximum value and then decreases to 0. The second moment is the moment when the electric field increases from a negative minimum value to a negative maximum value and then decreases to 0. The positive minimum value is greater than or equal to 0, and the negative minimum value is greater than or equal to 0. The polarization intensity at the first moment and the polarization intensity at the second moment in the second detection process are obtained to obtain the third polarization intensity and the fourth polarization intensity. The second detection process is a detection process in which a changing electric field is applied to the baked ferroelectric capacitor under test at the first predetermined temperature. The baked ferroelectric capacitor under test is obtained by baking the ferroelectric capacitor under test at the second predetermined temperature for a predetermined time. The rate of change of the residual polarization intensity is calculated based on the first polarization intensity, the second polarization intensity, the third polarization intensity, and the fourth polarization intensity. The rate of change of the residual polarization intensity is used to characterize the degree of imprinting effect of the ferroelectric capacitor under test after baking.

8. The test method according to claim 7, characterized in that, Based on the rate of change of the residual polarization intensity according to the first polarization intensity, the second polarization intensity, the third polarization intensity, and the fourth polarization intensity, including: The difference between the first polarization intensity and the second polarization intensity is calculated to obtain the first residual polarization intensity; The difference between the third polarization intensity and the fourth polarization intensity is calculated to obtain the second residual polarization intensity; Calculate the difference between the first residual polarization intensity and the second residual polarization intensity to obtain the change in residual polarization intensity; The ratio of the change in the residual polarization intensity to the first residual polarization intensity is calculated to obtain the rate of change of the residual polarization intensity.

9. The test method according to claim 7 or 8, characterized in that, The method further includes: The first coercive field is obtained when the polarization intensity of the ferroelectric capacitor under test is 0 as the electric field applied to the ferroelectric capacitor under test increases from the positive minimum value to the positive maximum value. The second coercive field is obtained when the polarization intensity of the ferroelectric capacitor under test is 0 during the process of the electric field applied to the baked ferroelectric capacitor under test increasing from the positive minimum value to the positive maximum value. The absolute value of the difference between the second coercive field and the first coercive field is calculated to obtain the first coercive field drift value. The first coercive field drift value is also used to characterize the degree of imprinting effect of the ferroelectric capacitor under test after baking.

10. The test method according to claim 7 or 8, characterized in that, The method further includes: The third coercive field is obtained when the polarization intensity of the ferroelectric capacitor under test is 0 as the electric field applied to the ferroelectric capacitor under test increases from the negative minimum value to the negative maximum value. The fourth coercive field is obtained when the polarization intensity of the ferroelectric capacitor under test is 0 during the process of the electric field applied to the baked ferroelectric capacitor under test increasing from the negative minimum value to the negative maximum value. The absolute value of the difference between the fourth coercive field and the third coercive field is calculated to obtain the second coercive field drift value. The second coercive field drift value is also used to characterize the degree of imprinting effect on the ferroelectric capacitor under test after baking.

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