Method for obtaining the distribution of conductive channels of a resistance-switching device

Abstract

The application discloses a method for obtaining the distribution of conductive channels of a resistance change device, which comprises the following steps: providing a resistance change device, wherein the resistance change device has a plurality of arrayed resistance change device units; controlling the external voltage of the resistance change device, peeling off the first array electrode layer and / or the second array electrode layer to expose the resistance change layer, and obtaining resistance change device units in different resistance states; scanning the surface information of the resistance change layer of the resistance change device units in different resistance states to obtain the current distribution of the resistance change device units in different resistance states; performing planar sampling on the resistance change layer to obtain a test plane; rotating the test plane along an axial direction, scanning the structural information of the test plane at multiple different angles, performing three-dimensional reconstruction on the two-dimensional data set of the structural information, and obtaining the three-dimensional distribution of the microstructure of the resistance change device units in different resistance states. Thus, the corresponding relationship between the current distribution of the conductive channels of the array-level resistance change device and the three-dimensional distribution of the microstructure of the conductive channels can be obtained.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of conductive channel testing, in particular, to a method for obtaining distribution of conductive channels of a resistive switching device. BACKGROUND

[0002] The resistive switching device has advantages of high density, low power, low cost and small size, and has a wide application prospect in non-volatile memory devices, wherein each resistive switching device includes an upper electrode-resistive layer-lower electrode, and by applying an electric field to the upper and lower electrodes, soft breakdown of the resistive layer occurs, and then a conductive channel is formed, and the connection of the conductive channel represents that the resistive switching unit is in a low resistance state, and the disconnection of the conductive channel represents that the resistive switching unit is in a high resistance state, so it can be seen that the switching state of the resistive switching device is closely related to the formation of the conductive channel in the resistive layer. However, the current test of the conductive channel in the resistive switching device still stays in the research of a single resistive switching device unit, and lacks the test of the array level resistive switching device.

[0003] Therefore, the current method for obtaining distribution of conductive channels of a resistive switching device still needs to be improved. SUMMARY

[0004] The present application is based on the inventors' discovery of the following problems:

[0005] The inventors found that the current test of the conductive filament morphology is mostly for a single resistive switching device unit, and lacks the statistical distribution of the conductive channel in the array level resistive switching device; on the other hand, the current test method of the conductive channel is for a specific structure of the device, and lacks the test of the array level resistive switching device in actual application; and on the other hand, the current test is for a specific resistance state of a single resistive switching device, and lacks the test of the conductive channel in the array level resistive switching device with an intermediate state and a special state.

[0006] The present application aims to at least partly alleviate or solve at least one of the above-mentioned problems.

[0007] In one aspect of the present application, a method for obtaining a distribution of conductive channels of a resistive switching device is provided, comprising: providing a resistive switching device, the resistive switching device comprising a first array electrode layer, a resistive switching layer and a second array electrode layer stacked together, at least one of the first array electrode layer, the resistive switching layer and the second array electrode layer comprising a plurality of arrayed substructures, the resistive switching device comprising a plurality of arrayed resistive switching device units; regulating an external voltage of the resistive switching device, and peeling off the first array electrode layer and / or the second array electrode layer to expose the resistive switching layer to obtain a resistive switching device unit under test in different resistance states; scanning surface information of the resistive switching layer, the surface information comprising a number and a distribution position of conductive channels, to obtain a current distribution of the resistive switching device unit under test in the different resistance states; performing planar sampling on the resistive switching layer to obtain a plane under test, the plane under test being a plane parallel to a side surface of the resistive switching layer; rotating the plane under test along an axial direction, and scanning structural information of the plane under test at a plurality of different angles to obtain a two-dimensional data set of the structural information at the plurality of different angles; and performing three-dimensional reconstruction on the two-dimensional data set of the structural information to obtain a three-dimensional distribution of a microstructure of the resistive switching device unit under test in the different resistance states, the structural information comprising a topographical state, a distribution position, a crystal phase structure, an element distribution and an element valence state of the conductive channels. Thus, a corresponding relationship between a current distribution of conductive channels of an array-level resistive switching device and a three-dimensional distribution of a microstructure of the conductive channels can be obtained.

[0008] According to an embodiment of the present application, the peeling off is performed by argon ion beam under monitoring of an Auger electron microscope to expose the resistive switching layer. Thus, the peeling precision can be improved so that the peeling position is accurately stopped at the surface of the resistive switching layer.

[0009] According to an embodiment of the present application, the peeling speed is 3(nm / min)-10(nm / min). Thus, the peeling precision of the electrode layer to expose the resistive switching layer can be further improved.

[0010] According to an embodiment of the present application, the scanning of the surface information of the resistive switching layer comprises testing the number and the distribution position of the conductive channels of the resistive switching layer by using a conductive probe atomic force microscope. Thus, the current distribution of the array-level resistive switching device can be obtained.

[0011] According to an embodiment of the present application, the planar positioning sampling comprises performing the positioning sampling by using a focused ion beam microscope and / or a conductive probe atomic force microscope. Thus, the positioning sampling accuracy can be further improved by using the focused ion beam microscope and / or the conductive probe atomic force microscope.

[0012] According to an embodiment of the present application, the structural information of the plurality of different angles of the to-be-tested plane is obtained by scanning the plurality of different angles of the to-be-tested plane using a transmission electron microscope to test the topography, distribution position, crystal phase structure, element distribution and element valence state of the conductive channel of the to-be-tested plane at the plurality of different angles. Thus, a three-dimensional distribution of the microstructure of the conductive channel of the array-level resistive switching device can be obtained.

[0013] According to an embodiment of the present application, the scanning of the plurality of different angles of the conductive channel of the to-be-tested plane using the transmission electron microscope to test the topography, distribution position, crystal phase structure, element distribution and element valence state of the conductive channel of the to-be-tested plane includes rotating the to-be-tested plane by a plurality of angles along an axial direction so that the electron beam of the transmission electron microscope irradiates the to-be-tested plane, wherein the initial state is 0° and the angle range of the rotation is -75° to +75°. Thus, a two-dimensional data set of the structural information of the to-be-tested plane can be obtained.

[0014] According to an embodiment of the present application, the resistive switching device includes at least one of a metal-type resistive switching device, an oxygen-ion type resistive switching device and a phase-change type resistive switching device. Thus, the method of the present application can be applied to various types of array-level resistive switching devices.

[0015] According to an embodiment of the present application, the area of the resistive switching device is 0.1 μm 2 -2 mm 2 . Thus, the method of the present application can be applied to array-level resistive switching devices of different areas.

[0016] According to an embodiment of the present application, the three-dimensional reconstruction of the structural information slice data set includes performing the three-dimensional reconstruction using simulation software, wherein the simulation software includes at least one of mathematical calculation software, Monte Carlo simulation calculation, electron microscope data processing software and three-dimensional visualization software. Thus, a three-dimensional distribution of the microstructure of the conductive channel of the array-level resistive switching device can be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a flow chart of a method for obtaining the distribution of the conductive channel of a resistive switching device according to an embodiment of the present application;

[0018] Figure 2 is a structural schematic diagram of an array structure resistive switching device according to an embodiment of the present application;

[0019] Figure 3 is a structural schematic diagram of a resistive switching device unit in an array structure resistive switching device according to an embodiment of the present application;

[0020] Figure 4 is a structural schematic diagram of a resistive switching device after stripping an electrode layer to expose a resistive switching layer according to an embodiment of the present application;

[0021] Figure 5 is a schematic diagram of a sample current distribution acquired by a conductive probe atomic force microscope according to an embodiment of the present application;

[0022] Figure 6 is a schematic diagram of current distributions of a resistive switching device in three typical resistance states according to an embodiment of the present application;

[0023] Figure 7 is a schematic diagram of a simulation of planar sampling and testing of a resistive switching layer according to an embodiment of the present application;

[0024] Figure 8 is a planar scanning diagram of an array structure resistive switching device according to an embodiment of the present application;

[0025] Figure 9 is a planar scanning enlarged diagram of a single resistive switching device unit according to an embodiment of the present application;

[0026] Figure 10 is a topography diagram of a TaO2 oxygen storage layer according to an embodiment of the present application;

[0027] Figure 11 is a topography diagram of a hafnium oxide resistive switching layer according to an embodiment of the present application;

[0028] Figure 12 is a planar sampling transmission electron microscope scanning diagram of a resistive switching device unit according to an embodiment of the present application;

[0029] Figure 13 is an Hf element distribution diagram according to an embodiment of the present application.

[0030] Reference Signs:

[0031] 1: resistive switching device unit; 10: first array electrode layer; 20: second array electrode layer; 30: resistive switching layer; 40: probe height unique testing system; 50: electrical signal testing system; 60: current distribution of a high resistance state device unit; 70: current distribution of a low resistance state device unit; 80: current distribution of an original resistance state device unit; 90: conductive filament; 100: sample rod; 101: planar sampling; 102: sample multi-angle testing; 103: three-dimensional reconstruction. DETAILED DESCRIPTION

[0032] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein the same or like reference numerals are used throughout the drawings to refer to the same or like components or elements. The embodiments described below are illustrative of the present application and are not intended to be limiting thereof.

[0033] In one aspect of the present application, the present application provides a method for obtaining the distribution of conductive channels of a resistive switching device, in which the method comprises the following steps: providing a resistive switching device, the resistive switching device comprising a first array electrode layer, a resistive switching layer and a second array electrode layer arranged in a stack, the resistive switching device comprising a plurality of array-arranged resistive switching device units; controlling the external voltage of the resistive switching device, and peeling off the first array electrode layer and / or the second array electrode layer to expose the resistive switching layer, so as to obtain a resistive switching device unit to be tested in different resistance states; scanning the surface information of the resistive switching layer of the resistive switching device unit to be tested in different resistance states, so as to obtain the current distribution of the resistive switching device unit to be tested in different resistance states; performing planar sampling on the resistive switching layer, so as to obtain a testing plane, wherein the testing plane is a plane parallel to one side surface of the resistive switching layer; rotating the testing plane along an axial direction, and scanning the structural information of the testing plane at a plurality of angles, so as to obtain a two-dimensional data set of the structural information of the testing plane at a plurality of different angles, and performing three-dimensional reconstruction on the two-dimensional data set of the structural information, so as to obtain the three-dimensional distribution of the microstructure of the resistive switching device unit to be tested in different resistance states, wherein the structural information comprises the topographic state, the distribution position, the crystal structure, the element distribution and the valence state of the conductive channels. Thus, the current distribution of the resistive switching device unit to be tested in different resistance states is obtained by testing the surface information of the resistive switching layer of the resistive switching device unit to be tested in different resistance states, and the testing plane is obtained by performing planar sampling on the resistive switching layer of the resistive switching device unit to be tested in different resistance states, the structural information of the testing plane at a plurality of different angles is tested, the three-dimensional distribution of the microstructure of the resistive switching device unit to be tested in different resistance states is obtained by performing three-dimensional reconstruction on the two-dimensional data set of the structural information of the testing plane at a plurality of different angles, so as to obtain the three-dimensional distribution of the current distribution and the microstructure of the array-structured resistive switching device. Further, according to the three-dimensional distribution of the current distribution and the microstructure, the corresponding relationship between the electrical characteristics of the array-level resistive switching device and the micro three-dimensional structure of the conductive channels can be established, which provides a reference for the optimization system of the resistive switching device, and the current distribution, the crystal structure, the element composition and the chemical valence state of the conductive channels are obtained at the nanoscale, which helps to study the electrical transport characteristics of a single conductive filament in the conductive channels, and the method for obtaining the distribution of conductive channels of a resistive switching device is provided Figure 1 The method comprises the following steps:

[0034] S100: providing a resistive switching device

[0035] According to some embodiments of the present application, the resistive switching device is provided in the step, and the resistive switching device comprises a first array electrode layer, a resistive switching layer and a second array electrode layer arranged in a stack, at least one of the first array electrode layer, the resistive switching layer and the second array electrode layer comprises a plurality of array-arranged substructures, and the resistive switching device comprises a plurality of array-arranged resistive switching device units. In the present application, the resistive switching device refers to two or more different resistance states exhibited by certain thin film materials under the action of an applied electric field, and the change of the resistance state does not degrade over time, so the resistance switching effect at this time is not a charging and discharging effect of a capacitor, but a resistance switching caused by the intrinsic structural change of the material under the action of an electric field. Specifically, referring to Figure 2 , the resistive switching device is a three-layer structure, that is, the resistive switching layer 30 is sandwiched between the first array electrode layer 10 and the second array electrode layer 20, and the first array electrode 10 and the second array electrode 20 can be made into vertically intersecting strips as word lines and bit lines of the resistive switching device, and the storage medium is loaded in the middle of the word lines and the bit lines, referring to Figure 3 , each intersection point is a resistive switching device unit 1, and the array-level resistive switching device is composed of a plurality of resistive switching device units 1. When testing the conductive channel of the array-level resistive switching device, only the current distribution and the microstructure of the resistive switching layer of the resistive switching device unit in different resistance states need to be tested to obtain the three-dimensional distribution of the conductive channel current distribution and the microstructure of the array-level resistive switching device unit, and then the correspondence between the current distribution and the microstructure is obtained, which provides a reference basis for the resistive switching device optimization system and helps to study the electrical transport characteristics of a single conductive filament in the conductive channel.

[0036] According to some embodiments of the present application, the array structure of the resistive switching device is not particularly limited, referring to Figure 2 , the array structure of the resistive switching device can also be in Figure 2 , the array structure of the resistive switching device can also be in

[0037] S200: Adjusting the external voltage of the resistive switching device, and peeling off the first array electrode layer and / or the second array electrode layer

[0038] According to some embodiments of the present application, in the step, referring to Figure 4, the external voltage of the aforementioned resistance change device is regulated, and the first array electrode layer and / or the second array electrode layer is peeled off to expose the resistance change layer 30, so that the resistance change device units in different resistance states are obtained. The inventor finds that the resistance change device can be cyclically switched between high and low resistance states under the stimulation of the external voltage, and the resistance state of the resistance change device units in different resistance states in the resistance change device can remain unchanged after the stimulation of the external voltage ends. When the upper electrode and / or the lower electrode of the resistance change device unit is peeled off to expose the resistance change layer by a certain means, the testing of the resistance change device units in different resistance states can be completed. In the present application, by regulating the voltage of the array-level resistance change device in actual application, the resistance states of the resistance change device can include low resistance state, high resistance state, intermediate resistance state and the like. By peeling off the first array electrode layer and / or the second array electrode layer of the resistance change device to expose the resistance change layer, and testing the resistance change layer of the resistance change device units in different resistance states, the statistical testing of the conductive channels in the array-level resistance change device can be obtained.

[0039] In the description of the present application, "A and / or B" can include any one of the case of A alone, the case of B alone, and the case of A and B, where A and B are only used for example, and can be any technical feature connected by "and / or" in the present application.

[0040] According to some embodiments of the present application, the peeling manner includes peeling off the first array electrode layer and / or the second array electrode layer to expose the resistance change layer under the monitoring of an Auger electron microscope by an argon ion beam. Since different element atoms have their own characteristic Auger electron energy, the Auger electron microscope can be used to identify elements. Under the monitoring of the Auger electron microscope, by controlling the speed of the argon ion beam to peel off the first array electrode layer and / or the second array electrode layer, the Auger electron microscope can test the chemical composition of the peeling position in real time and online during the peeling process, so that the peeling position can be controlled on a nanoscale, and then it is determined whether the peeling stop position is the target test layer, and then the accuracy of the subsequent testing of the conductive channels of the resistance change device is improved.

[0041] According to some embodiments of the present application, the peeling speed of the first array electrode layer and / or the second array electrode layer by the Auger electron microscope is not particularly limited, for example, the peeling speed can be 3 (nm / min) -10 (nm / min). When the peeling speed is greater than 10 (nm / min), the peeling speed is too fast, which is not conducive to the real-time monitoring of the peeling thickness and the accuracy of the stopping position by the Auger electron microscope. When the peeling speed is less than 3 (nm / min), the peeling speed is too slow, which will cause damage to the sample by the argon ion beam, and thus affect the accuracy of the subsequent test results of the conductive channel of the resistive switching device. When the peeling speed is 3 (nm / min) -10 (nm / min), the argon ion beam can be peeled off the first array electrode layer and / or the second array electrode layer under the monitoring of the Auger electron microscope, and the stopping position of the peeling can be accurately stopped on the surface of the resistive switching layer, thereby improving the test results of the conductive channel of the resistive switching device. Specifically, for the resistive switching device with a stack structure of Pt (100 nm) / TiN (50 nm) / HfO x (8 nm) / TiN (50 nm), wherein Pt (100 nm) represents a platinum metal layer with a thickness of 100 nm, TiN (50 nm) represents titanium nitride with a thickness of 50 nm, and HfO x (8 nm) represents hafnium oxide with a thickness of 8 nm. The specific peeling process is as follows: first, peel off to the TiN layer at a speed of 10 nm / min, then peel off to the crystalline TiN / HfO x interface at a speed of 5 nm / min for 6-7 min, and then peel off to the surface of the HfO x layer at a speed of 3 nm / min. In this way, the peeling surface is stopped on the resistive switching layer structure under the premise of ensuring the peeling efficiency.

[0042] S300: Scan the surface information of the resistive switching layer

[0043] According to some embodiments of the present application, in this step, the surface information of the resistive switching layer of the resistive switching device unit to be tested in different resistance states is scanned, wherein the surface information includes the current distribution of the resistive switching device unit to be tested in different resistance states, so as to obtain the number and distribution position of the conductive channel. In this way, the current distribution test is performed on the device units in different resistance states, and the distribution of the conductive channel in the resistive switching layer can be obtained. Specifically, after the first array electrode layer and / or the second array electrode layer of the resistive switching device unit is peeled off to expose the resistive switching layer, the surface of the resistive switching layer of the resistive switching device unit in a specific resistance state of the resistive switching device is scanned, and the number and distribution position of the conductive channel on the surface of the resistive switching layer are obtained, and thus the distribution of the conductive channel in the resistive switching layer can be obtained. The number and distribution of the conductive channel on the surface of the resistive switching layer of the resistive switching device unit in other resistance states of the resistive switching device are tested, and thus the current distribution of the array-level resistive switching device can be obtained.

[0044] According to some embodiments of the present application, the scanning of the surface information of the resistive switching layer of the resistive switching device unit in different resistance states includes testing the number and distribution of the conductive channels of the resistive switching layer of the resistive switching device unit by using a conductive probe atomic force microscope. The conductive probe atomic force microscope is additionally provided with a sensitive ammeter outside the force sensor and the force detector of the conventional atomic force microscope, so that the tip of the probe is conductive during scanning, and the surface information of the resistive switching layer is obtained. Referring to Figure 5 When the conductive probe atomic force microscope is used to collect the number and distribution of the conductive channels on the surface of the resistive switching layer, the probe height displacement testing system 40 can control the movement of the probe in real time, and the electrical signal testing system 50 can provide electrical signals for testing. Specifically, the sample can be moved within a range of millimeters, and the position of the testing probe can be moved within a size of micrometers by the probe height displacement testing system 40, so as to complete the testing of the surface information of the resistive switching layer, Figure 6 The current distribution in the conductive channels of three typical resistance states is shown, in which 60 is the current distribution of the original resistance state device unit, 70 is the current distribution of the high resistance state device unit, and 80 is the current distribution of the low resistance state device unit. Specifically, by testing the resistive switching layer of the low resistance state resistive switching device by using the conductive probe atomic force microscope, the current distribution of the resistive switching layer of the unit of the resistive switching device in this resistance state is obtained as the distribution of the conductive channels in the high-density state. Thus, the conductive channels of the resistive switching layer of the resistive switching device unit in different resistance states can be precisely tested at the nanoscale, and the current distribution of the resistive switching layer can be obtained.

[0045] S400: Planar sampling of the resistive switching layer to obtain a testing plane

[0046] According to some embodiments of the present application, in this step, the resistive switching layer of the resistive switching device unit in different resistance states is planarly sampled to obtain a testing plane sample to meet the requirements of the physical properties of the sample in the subsequent testing process. The testing plane is a plane parallel to one side surface of the resistive switching layer. Thus, by sampling the testing plane of the sampled resistive switching device unit in different resistance states, the testing plane of the resistive switching layer of the resistive switching device unit in different resistance states is obtained, and the subsequent testing is performed, and thus the microstructure of the conductive channels of the array-level resistive switching device is obtained.

[0047] According to some embodiments of the present application, the planar positioning sampling of the resistive switching layer is performed by using a focused ion beam microscope and / or a conductive probe atomic force microscope. The sampling principle of the focused ion microscope is that under the condition of an applied electric field, a gallium ion beam is derived, and the sample is cut by physical collision of the ions. The transmission electron microscope testing principle is that an accelerated and focused electron beam is projected onto a very thin sample, and the electrons interact with the atoms in the sample to generate elastic scattering and inelastic scattering signals, thereby analyzing the crystal structure and chemical composition of the sample. Specifically, the planar surface in the resistive switching layer parallel to any one side surface of the resistive switching layer is cut by using the gallium ion nanometer cutting hand of the focused ion microscope, so as to meet the requirement of the sample thickness when the microstructure of the resistive switching layer is tested subsequently. Figure 7 The process of planar sampling of the resistive switching layer can be sampling the XY plane of the resistive switching layer. According to some embodiments of the present application, the planar sampling of the resistive switching layer can also be sampling the ZX or YZ plane to obtain the measured plane.

[0048] S500: Rotating the resistive switching layer along the axial direction and scanning the structural information of the measured plane at multiple different angles

[0049] According to some embodiments of the present application, in this step, the measured plane is rotated along the axial direction, and the structural information of the measured plane at multiple different angles is obtained by scanning the measured plane at multiple different angles, so as to obtain a two-dimensional data set of the structural information of the measured plane at multiple different angles. The structural information of the measured plane at multiple different angles is three-dimensionally reconstructed to obtain the three-dimensional distribution of the microstructure of the measured resistive switching device unit in the different resistance states. Specifically, the measured plane sample is obtained by planar sampling of the resistive switching layer, the measured plane sample of the resistive switching layer is placed into a sample rod, the measured plane sample in the sample rod is rotated along the axial direction, a two-dimensional data set of the structural information of the measured plane at multiple different angles is obtained, and a three-dimensional simulation software is used for the obtained two-dimensional data set of the structural information, so as to obtain the three-dimensional distribution of the conductive channel microstructure in the device in a specific resistance state. Reference Figure 7The XY direction can be set as a plane parallel to the surface of the resistive switching layer. The resistive switching layer is sampled in the XY plane 101, and the sampled plane to be tested is placed in the sample rod 100. The sampled plane to be tested in the sample rod is rotated along the axial direction. That is, the initial position of the sample rod is 0° as the axial direction. The sample rod is rotated along the axial direction to multiple different angles, and the plane to be tested of the resistive switching layer is tested at multiple different angles 102. The two-dimensional dataset of the structural information of the plane to be tested at multiple different angles is obtained. The two-dimensional dataset of the structural information of the plane to be tested at multiple different angles is reconstructed in three dimensions 103. The three-dimensional distribution of the microstructure of the conductive channel of the resistive switching layer is obtained, where 90 represents a single conductive filament. The aforementioned tests are then performed on the resistive switching layer of the resistive switching device unit with different resistive states, thereby obtaining the statistical information of the conductive channel of the array-level resistive switching device. Therefore, by acquiring the sample under test of the resistive switching layer plane through conductive probe atomic force microscopy and / or focused ion beam microscopy, and conducting tests on the sample under test from multiple angles, it is also possible to establish the correspondence between the electrical characteristics of specific resistive switching devices in the array and the microscopic three-dimensional structure of the conductive channels, providing a reference for optimizing the resistive switching device system. The information on current distribution, crystal phase structure, elemental composition, and chemical valence state of the conductive channels obtained at the nanoscale is helpful for studying the electrical transport characteristics of a single conductive filament in the conductive channel.

[0050] According to some embodiments of the present invention, a plane parallel to the surface of the resistive switching layer is cut out using a gallium ion nano-cutting technique with a focusing ion microscope, and the elemental distribution of the conductive channels in the observation plane is tested using a transmission electron microscope. For example, the elemental distribution of the resistive switching layer of a specific resistive state resistive switching device unit in a 128-row by 8-column array-level resistive switching device is observed. The stacked structure of the resistive switching device is Pt / TiN / TaO2 / HfO. x A TiN resistive switching device with a resistive switching unit size of 700 nm. 2 , Figure 8 This is a scan diagram of the resistive switching device in this array structure. Figure 9 This is a magnified scan image of a single resistive switching device unit. After adjusting the external voltage of the resistive switching device to allow for the existence of device units in various resistive states, the first electrode layer was stripped using an argon ion beam under Auger electron microscopy to obtain the morphology of the TaO2 oxygen storage layer, as shown below. Figure 10 As shown, HfO was obtained by further stripping the oxygen storage layer. x Topographic images of the resistive switching layer, such as Figure 11 As shown, a focused square-beam microscope was used to sample the resistive switching layer in a plane, as follows: Figure 12 As shown, the entire single-device unit can be included within the observation range of the transmission electron microscope, and the Hf element scanning results in the planar sampling are as follows. Figure 13The test is performed on the test plane of the resistive switching layer of the low resistance state of the resistive switching device by using a transmission electron microscope. In the conductive region of the resistive switching layer of the low resistance state device unit, oxygen elements are measured. The distribution of the oxygen elements is negatively correlated with the distribution of the conductive channels. In the conductive channel dense position, the oxygen element content is low. The +3 chemical valence state of hafnium elements is measured in the conductive region of the resistive switching layer of the low resistance state device unit. The +3 chemical valence state of the hafnium elements is positively correlated with the distribution of the conductive channels. In the conductive channel dense position, the +3 chemical valence state of the hafnium elements is more. The oxygen-deficient phase monoclinic system of hafnium oxide is measured in the conductive channel region of the resistive switching layer of the low resistance state device unit. The distribution of the oxygen-deficient phase monoclinic system is positively correlated with the distribution of the conductive channels. The conductive channel is mainly composed of the oxygen-deficient phase monoclinic system of hafnium oxide. The electrical transport characteristics of a single conductive filament in the conductive channel of the resistive switching layer of the low resistance state of the resistive switching device are ohmic characteristics. In the current distribution, the high conductive region has the crystal structure of the oxygen-deficient phase monoclinic system, the oxygen content is lower than that of the matrix region, the hafnium element is in the positive trivalent state, and the electron transfer is from Hf5p to Hf5d electron state. By testing the resistive switching device units of different resistance states of the resistive switching device, the statistical distribution of the conductive channels of the array level resistive switching device is a normal distribution.

[0051] According to some embodiments of the application, the structure information of the test plane of the resistive switching layer of the test resistive switching device unit of different resistance states is tested at different angles, including testing the morphology, distribution, mirror structure, element distribution and element valence of the conductive channel of the test resistive switching device unit by using a transmission electron microscope. The plane positioning sampling is performed by using a focused ion beam microscope and / or a conductive probe atomic force microscope. Figure 7The sampling method can also be multiple sampling at different depths in the YX direction of the resistance variable layer to obtain a two-dimensional data set of planar sampling. The two-dimensional data set of planar sampling results is tested at multiple different angles by using a transmission electron microscope, so as to obtain a two-dimensional data set of structure information of the measured plane of the resistance variable layer. The three-dimensional structure of the microstructure of the conductive channel of the resistance variable layer is obtained by three-dimensional reconstruction of the two-dimensional data set of structure information by using three-dimensional simulation software. The resistance variable layer of the resistance variable device unit in other resistance states is sampled and tested by using the foregoing sampling method, and the statistical situation of the microstructure of the conductive channel of the array-level resistance variable device can be obtained. Thus, the three-dimensional distribution of the microstructure of the conductive channel of the device unit in multiple resistance states of the resistance variable device in actual application can be obtained, and the characteristics of the resistance variable device can be further evaluated to provide systematic and accurate reference data for optimization of the resistance variable device. Specifically, the position and current value of the conductive channel are determined by using the current distribution data of the conductive probe atomic force microscope. The XY position information is compared, and the position of the conductive channel is located on the transmission electron microscope observation diagram by using the current distribution result of the conductive probe atomic force microscope. Then, the two-dimensional data collection of the current distribution, crystal phase structure, element composition, and chemical valence state of the conductive channel is performed by using different data collection modes, for example, the transmission electron microscope bright field phase for collecting the crystal structure of the reaction, the X-ray energy dispersive spectroscopy (EDS) scanning diagram for collecting the element distribution of the reaction, and the low-energy electron loss spectrum (EELS) scanning diagram for collecting the element valence state information of the reaction. The two-dimensional data collection of the current distribution, crystal phase structure, element composition, and chemical valence state of the conductive channel is processed by using the three-dimensional reconstruction method, and the three-dimensional distribution structure of the information is obtained. The process of transmission electron microscope three-dimensional reconstruction is based on the central section theorem for reconstruction. The content of the central section theorem is that the Fourier transform of the projection of any three-dimensional object in real space along the electron beam direction is a section through the center in the Fourier space corresponding to the object and disposed with a section in the projection direction. In the process of three-dimensional data collection, the projections of the sample at different angles are collected. In the process of three-dimensional reconstruction, the Fourier transform of each projection is performed, the corresponding section in the three-dimensional Fourier space is filled according to the projection direction, and then the inverse Fourier transform is performed to obtain the three-dimensional structure of the sample information in the real space.

[0052] According to some embodiments of the present application, the scanning of the topography state, distribution position, crystal phase structure, element distribution, and element valence state of the conductive channel of the measured plane at multiple different angles by using the transmission electron microscope includes: rotating the measured plane along the axial direction by multiple angles so that the electron beam of the transmission electron microscope irradiates the measured plane of the resistance variable layer, wherein the initial state is counted as 0°, and the angle range of rotation is -75° to +75°. Specifically, the measured plane is rotated by 0°, -30°, -60°, -75°, +75°, +60°, and +30°, respectively. Figure 7, the resistance variable layer is rotated along the axial direction, the initial 0° of the transmission electron microscope sample rod is taken as the axial direction, and then the transmission electron microscope sample rod is rotated at the initial position, the sample plane to be measured is correspondingly rotated, and the angle range of the rotation is -75° to +75°. Thus, a plurality of structural information two-dimensional data sets of the sample plane to be measured at different angles can be obtained, the structural information two-dimensional data sets are reconstructed in three dimensions, and then the microstructure three-dimensional distribution of the conductive channel of the resistance variable layer is obtained.

[0053] According to some embodiments of the present application, the type of the resistance variable device is not particularly limited, for example, the type of the resistance variable device can be at least one of a metal type resistance variable device, an oxygen ion type resistance variable device, and a phase change type resistance variable device.

[0054] According to some embodiments of the present application, the area of the resistance variable device is not particularly limited, for example, the area of the resistance variable device can be 0.1 μm 2 -2 mm 2 Thus, by using the method for obtaining the conductive channel of the resistance variable layer provided in the present application, the conductive channel of the array level resistance variable device with a large range of area size can be tested, that is, the method for obtaining the conductive channel of the resistance variable layer provided in the present application can be applied to various types of array level resistance variable devices.

[0055] According to some embodiments of the present application, the number of resistance variable device units of the array level resistance variable device is not particularly limited, for example, the number of resistance variable device units of the array level resistance variable device can be 1024-128000 resistance variable device units. When the number of resistance variable device units of the array level resistance variable device is in the foregoing range, the method for obtaining the microstructure of the conductive channel provided in the present application can realize the test of the conductive channel of the array level resistance variable device, and provide a system and accurate reference data for the optimization of the array structure resistance variable device.

[0056] According to some embodiments of the present application, the basic process of reconstructing the structural information two-dimensional data set of the resistance variable layer in three dimensions is that the Fourier transform is performed on each angle projection image, the projection direction is filled into the corresponding section of the three-dimensional Fourier space, and then the inverse Fourier transform is performed to obtain the three-dimensional structure of the sample information in the real space. Specifically, the simulation method of reconstructing the structural information two-dimensional data set of the resistance variable layer in three dimensions is not particularly limited, for example, the simulation method of reconstructing the structural information two-dimensional data set of the resistance variable layer in three dimensions can be software simulation, and such software simulation includes but is not limited to mathematical calculation software (Matlab), Monte Carlo simulation calculation, electron microscope data processing software (Axon), and three-dimensional visualization software (Avizo).

[0057] The application will be described in detail below by specific examples. It should be noted that the following examples are only used to illustrate the application, and should not be regarded as limiting the scope of the application. If the specific technology or condition is not specified in the examples, it is performed according to the technology or condition described in the literature in the art or according to the product manual. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained by purchase.

[0058] Example 1

[0059] Controlling the external voltage of the resistance variable device: a resistance variable device array with 128 rows and 8 columns is provided, and the laminated structure of the resistance variable device is Pt (100 nm) / TiN (50 nm) / HfO x (8 nm) / TiN (50 nm). The voltage of the resistance variable device is controlled, and the resistance of the resistance variable device unit in the resistance variable device is controlled to 3 resistance states, i.e. low resistance state, medium resistance state and high resistance state.

[0060] Exposing the resistance variable layer by peeling off the upper electrode: first, peel off to the TiN layer at a speed of 10 nm / min, then peel off to the crystalline TiN / HfO x interface at a speed of 5 nm / min for 6-7 min, and then peel off to the HfO x layer surface at a speed of 3 nm / min.

[0061] Scanning the surface information of the resistance variable layer: scanning the surface information of the resistance variable layer of the resistance variable device unit in a specific resistance state of the resistance variable device can obtain the number and distribution position of the conductive channel of the resistance variable layer surface, i.e. using the current distribution data of the conductive probe atomic force microscope to determine the position and current value of the conductive channel, and repeating the operation to test the resistance variable device units in different resistance states of the array level resistance variable device.

[0062] Planar sampling of the resistance variable layer: planar sampling is performed on the same resistance variable device whose position and current value of the conductive channel are determined by scanning the surface information of the resistance variable layer, and the planar sampling is performed by a focused ion beam microscope to obtain the test plane.

[0063] Microstructure test of conductive channel: place the test plane sample of the resistance variable layer into the sample rod, rotate the test plane sample in the sample rod along the axial direction, and use the current distribution results of the conductive probe atomic force microscope to locate the position of the conductive channel on the transmission electron microscope observation graph by comparing the XY position information. Then, collect the transmission electron microscope bright field phase of the reaction crystal structure, collect the X-ray energy dispersive spectroscopy (EDS) scanning graph of the reaction element distribution, and collect the low energy electron loss spectrum (EELS) scanning graph of the reaction element valence information. Use the three-dimensional reconstruction method to process the two-dimensional data collection of the current distribution, crystal phase structure, element composition and chemical valence information of the conductive channel, respectively, to obtain the three-dimensional distribution structure of the information.

[0064] Thus, by using the conductive probe atomic force microscope to test the resistive switching layer of the resistive switching device in the low resistance state, the current distribution of the resistive switching layer of the unit of the resistive switching device in the low resistance state is obtained as the distribution of the conductive channel in the high density state.

[0065] By using the transmission electron microscope to test the to-be-tested plane of the resistive switching layer of the resistive switching device in the low resistance state, oxygen elements are measured in the conductive region of the resistive switching layer of the unit of the low resistance state device, the distribution of the oxygen elements is negatively correlated with the distribution of the conductive channel, and the content of the oxygen elements is low in the position where the conductive channel is dense; the +3 chemical valence state of hafnium elements is measured in the conductive region of the resistive switching layer of the unit of the low resistance state device, the +3 chemical valence state of the hafnium elements is positively correlated with the distribution of the conductive channel, and the hafnium in the +3 chemical valence state is more in the position where the conductive channel is dense; the oxygen-deficient phase monoclinic system of hafnium oxide is measured in the conductive channel region of the resistive switching layer of the unit of the low resistance state device, the distribution of the oxygen-deficient phase monoclinic system is positively correlated with the distribution of the conductive channel, and the conductive channel is mainly composed of the hafnium oxide crystal phase in the oxygen-deficient state monoclinic system.

[0066] The electrical transport characteristics of a single conductive filament in the electrical channel of the resistive switching layer of the resistive switching device in the low resistance state are Ohmic characteristics curves, which are expressed as high-conductive regions in the current distribution, have the crystal structure of the oxygen-deficient state monoclinic system, the content of oxygen is lower than that of the matrix region, the hafnium elements are in the positive trivalent state, and the electrons are transferred from Hf5p to Hf5d electron states for electron transport.

[0067] By testing the resistive switching device units in different resistance states of the Pt(100nm) / TiN(50nm) / HfO x (8nm) / TiN(50nm) resistive switching device, the statistical distribution of the conductive channel of the array-level resistive switching device can be obtained as a normal distribution.

[0068] In the description of the present application, it should be understood that the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can be explicitly or implicitly included one or more of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0069] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0070] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and the person skilled in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A method for obtaining the conductive channel distribution of a resistive switching device, characterized in that, include: A resistive switching device is provided, the resistive switching device including a first array electrode layer, a resistive switching layer and a second array electrode layer stacked together, at least one of the first array electrode layer, the resistive switching layer and the second array electrode layer including a plurality of arrayed substructures, and the resistive switching device including a plurality of arrayed resistive switching device units. Adjust the external voltage of the resistive switching device and strip the first array electrode layer and / or the second array electrode layer to expose the resistive switching layer to obtain resistive switching device units under test with different resistance states; By scanning the surface information of the resistive switching layer, including the number and distribution of conductive channels, the current distribution of the resistive switching device unit under test in different resistive states can be obtained. Planar sampling is performed on the resistive switching layer to obtain the test plane, which is a plane parallel to one side surface of the resistive switching layer; The test plane is rotated along the axial direction. By scanning the structural information of the test plane at multiple different angles under the axial rotation, a two-dimensional dataset of the structural information of the test plane at multiple different angles is obtained. The two-dimensional dataset of the structural information is reconstructed in three dimensions to obtain the three-dimensional distribution of the microstructure of the test resistive switching device unit with different resistance states. The structural information includes the morphology, distribution position, crystal phase structure, element distribution and element valence state of the conductive channels.

2. The method according to claim 1, characterized in that, The stripping method includes stripping the first array electrode layer and / or the second array electrode layer under Auger electron microscopy monitoring using an argon ion beam to expose the resistive switching layer.

3. The method according to claim 2, characterized in that, The stripping speed is 3nm / min-10nm / min.

4. The method according to claim 1, characterized in that, The step of scanning the surface information of the resistive switching layer includes using a conductive probe atomic force microscope to test the number and distribution location of the conductive channels in the resistive switching layer.

5. The method according to claim 1, characterized in that, The positioning and sampling of the plane includes the use of focused ion beam microscopy and / or conductive probe atomic force microscopy.

6. The method according to claim 1, characterized in that, The process of scanning the structural information of the plane under test at multiple different angles includes using transmission electron microscopy to test the morphology, distribution, crystal structure, elemental distribution, and elemental valence state of the conductive channels at multiple different angles of the plane under test.

7. The method according to claim 6, characterized in that, The morphology, distribution, crystal structure, elemental distribution, and elemental valence state of the conductive channels at multiple different angles of the plane under test, obtained by scanning with transmission electron microscopy, include: The plane to be tested is rotated along the axial direction by multiple angles so that the electron beam of the transmission electron microscope irradiates the plane to be tested. The initial state is 0°, and the rotation angle range is -75° to +75°.

8. The method according to claim 1, characterized in that, The resistive switching device includes at least one of the following: metal resistive switching device, oxygen ion resistive switching device, and phase change resistive switching device.

9. The method according to claim 1, characterized in that, The resistive switching device has an area of ​​0.1 μm. 2 -2mm 2 .

10. The method according to claim 1, characterized in that, The three-dimensional reconstruction of the two-dimensional dataset of the structural information includes the use of simulation software for the three-dimensional reconstruction. The simulation software includes at least one of mathematical calculation software, Monte Carlo simulation calculation, electron microscopy data processing software, and three-dimensional visualization software.

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