Micro-area highly accelerated life experiment device and method

Abstract

The invention provides a micro-area highly accelerated life experiment device and method, and the device is used for the in-situ aging of a to-be-measured micro-area of a multilayer ceramic capacitor, and comprises a micro-area aging heating module which comprises a thermal control unit, a thermal probe and an atomic force microscope unit. The thermal control unit is connected with the thermal probe and is used for heating the thermal probe; the atomic force microscope unit comprises an AFM control system and an AFM sample table, the multilayer ceramic capacitor is arranged on the AFM sample table, and the AFM control system is used for controlling the tip of the thermal probe to approach a to-be-measured micro-area of the multilayer ceramic capacitor in a quasi-static mode, so that the thermal environment at the tip of the thermal probe remains unchanged before and after contact; the micro-area aging excitation module is electrically connected with the multilayer ceramic capacitor and is used for providing a micro-area aging direct-current electric field; wherein the micro-area aging heating module and the micro-area aging excitation module enable a micro-area to be tested to complete micro-area in-situ aging under the action of aging heating and a micro-area aging direct-current electric field.

Description

Technical Field

[0001] The present invention relates to the field of signal detection instruments, and particularly to a micro-region high-acceleration life experiment device and method. Background Art

[0002] Multilayer Ceramic Capacitors (MLCCs) are capacitors with a monolithic structure formed by alternating stacking of ceramic dielectric layers and internal electrodes, and are widely used in important fields such as mobile communication, information electronics, new energy vehicles, aerospace, and military. The performance degradation of MLCCs during normal use is an extremely slow process. In engineering practice, in order to quickly obtain aged samples and discover problems such as product design and structural defects in the early stage of production, macroscopic High Acceleration Life Test (HALT) is often used to process samples to be tested. In the HALT test of MLCCs, generally, the samples to be tested are placed under conditions of a high temperature field and a high electric field to accelerate the performance degradation of the products, and by monitoring the leakage current characteristics of the aged samples, an understanding of the aging behavior characteristics of the samples can be obtained. Currently, the rapidly developing MLCCs are increasingly tending towards miniaturization, thin-layerization, and lamination. There is an urgent need to understand the correlation mechanism between structural variation, performance degradation, reliability, and failure behavior at the microscale, which undoubtedly has important significance for the innovative research and in-depth application of MLCCs.

[0003] The Scanning Probe Microscopy (SPM) developed on the basis of the Atomic Force Microscope (AFM) has become one of the important means for current research on nanoscience and technology. The SPM technology has not only brought revolutionary breakthroughs to the ultra-high-resolution microscopic imaging of nanostructures, nanostructure manipulation, and in-situ characterization of physical properties at the nanoscale, but also is an important platform for the development of new methods and technologies for nanoscale characterization.

[0004] In the prior art, the aging research on MLCCs is limited to macroscopic aging experiments, that is, studying all of the MLCCs, and it is impossible to conduct aging experiments on the micro-regions of MLCCs, such as micro-regions at the level of dozens of grains. Summary of the Invention

[0005] In view of the urgent need for current research on the micro-area aging of MLCCs, the present invention provides a new technology for a micro-area high-accelerated life test device based on an atomic force microscope. By providing a micro-area high-accelerated life test device and a micro-area high-accelerated life test method, a method and device for in-situ micro-area aging of multilayer ceramic capacitors (MLCCs) and testing their aging performance are realized, so as to promote the in-depth research and innovative development of the key scientific issues of the microstructural performance degradation and failure mechanism of MLCC dielectric materials.

[0006] In a first aspect of the present invention, there is provided a micro-area high-accelerated life test device for realizing in-situ micro-area aging of a to-be-tested micro-area of a multilayer ceramic capacitor, including A micro-area aging heating module, including a thermal control unit, a thermal probe, and an atomic force microscope unit. The thermal control unit is connected to the thermal probe for heating the thermal probe. The atomic force microscope unit includes an AFM control system and an AFM sample stage. The multilayer ceramic capacitor is disposed on the AFM sample stage. The AFM control system is used to control the tip of the thermal probe to approach the to-be-tested micro-area of the multilayer ceramic capacitor in a quasi-static manner, so that the thermal environment at the tip of the thermal probe remains unchanged before and after contact. A micro-area aging excitation module, electrically connected to the multilayer ceramic capacitor for providing a micro-area aging DC electric field. Wherein The micro-area aging heating module and the micro-area aging excitation module enable the to-be-tested micro-area to complete in-situ micro-area aging under the action of aging heating and the micro-area aging DC electric field.

[0007] As a preferred embodiment of the present invention, the thermal probe is a thermosensitive material, and the thermal control unit is electrically connected to the thermal probe for applying a heating voltage to the thermal probe to in-situ excite the first-order non-linear thermosensitive characteristic of the thermal probe, so as to realize at least heating and temperature rising of the tip of the thermal probe.

[0008] As a preferred embodiment of the present invention, the thermal control unit includes a DC power supply, a DC bridge, and a voltage limiting unit. The DC bridge includes a first bridge arm and a second bridge arm connected in parallel. One end of the first bridge arm is connected to the DC power supply and the other end is grounded. One end of the second bridge arm is connected to the DC power supply and the other end is connected in series with the thermal probe and then grounded. Wherein The voltage limiting unit is respectively connected to the first bridge arm, the second bridge arm, and the DC power supply. The voltage limiting unit limits the output voltage of the DC power supply based on the voltage difference between the first bridge arm and the second bridge arm.

[0009] As a preferred embodiment of the present invention, the first bridge arm includes a first fixed resistor, a first potentiometer, and an equivalent resistor connected in series in sequence, and the equivalent resistor is grounded; the second bridge arm includes a second fixed resistor and a second potentiometer connected in series in sequence, one end of the second potentiometer is connected to the second fixed resistor, and the other end is connected to the input end of the thermal probe, and the output end of the thermal probe is grounded; the connection point of the voltage limiting unit and the first bridge arm is arranged between the first potentiometer and the equivalent resistor, and the connection point of the voltage limiting unit and the second bridge arm is arranged between the second potentiometer and the thermal probe, where the resistance value of the equivalent resistor is the same as the resistance value of the thermal probe under room temperature conditions.

[0010] As a preferred embodiment of the present invention, the voltage limiting unit includes a subtractor, a voltage amplifier, and a power supply controller. The voltage amplifier is connected to the subtractor and the power supply controller. The subtractor is respectively connected to the first bridge arm and the second bridge arm, and the power supply controller is connected to the DC power supply, where the subtractor is used to calculate the voltage difference between the first bridge arm and the second bridge arm, the voltage amplifier is used to amplify the voltage difference, and the power supply controller controls the output power of the DC power supply based on the voltage difference amplified by the voltage amplifier.

[0011] As a preferred embodiment of the present invention, the contact area between the thermal probe and the multi-layer ceramic capacitor is 10 - 30 nm 2 , the acting force value between the thermal probe and the multi-layer ceramic capacitor is 100 nN - 200 nN, and the heating voltage applied by the thermal control unit to the thermal probe is 10 - 800 mV.

[0012] As a preferred embodiment of the present invention, the atomic force microscope unit further includes a magnetic metal cushion layer, the magnetic metal cushion layer is magnetically adsorbed on the AFM sample stage, and the multi-layer ceramic capacitor is fixedly arranged on the magnetic metal cushion layer.

[0013] As a preferred embodiment of the present invention, it further includes a micro-area aging electrical signal detection module, and the micro-area aging electrical signal detection module is electrically connected to the multi-layer ceramic capacitor to process and display the micro-area leakage current signal of the multi-layer ceramic capacitor.

[0014] As a preferred embodiment of the present invention, the micro-area aging excitation module includes a digital source meter, and the voltage output end of the digital source meter is connected to the multi-layer ceramic capacitor to provide an aging electric field, where The micro-region aging electrical signal detection module is connected to the output end of the digital source meter, and is used to process and display the micro-region aging leakage current signal of the multi-layer ceramic capacitor, so as to realize the in-situ test of the leakage current of the micro-region to be measured.

[0015] As a preferred embodiment of the present invention, the multi-layer ceramic capacitor is a multi-layer ceramic capacitor that has been polished until the internal and external electrodes are alternately arranged and can be observed.

[0016] In the second aspect of the present invention, a micro-region high-accelerated life experiment method is provided. Based on the micro-region high-accelerated life experiment device, the method includes the following steps: Step 1: Polish the multi-layer ceramic capacitor along the direction perpendicular to the electrodes until the alternately arranged internal electrodes appear; Step 2: Fix the multi-layer ceramic capacitor on the magnetic metal cushion layer, use conductive silver paste to connect the wire to the external electrode of the multi-layer ceramic capacitor, and fix the multi-layer ceramic capacitor to the micro-region aging excitation module and the AFM sample stage; Step 3: Use the AFM control system to control the thermal probe to approach the surface of the multi-layer ceramic capacitor material in a quasi-static manner and contact to realize the aging heating of the micro-region to be measured, and control the digital source meter to provide an aging voltage for the multi-layer ceramic capacitor sample material. Under the action of the aging heating and the aging voltage, the micro-region in-situ aging experiment is completed.

[0017] Advantages of the present invention: By combining AFM nano-functional detection, thermal probe nano-heating function, non-linear characteristics of thermistors, and macroscopic high-accelerated life experiment principle, etc., a micro-region high-accelerated life experiment device and a new technology are established, which have unique functions of micro-region aging and micro-region aging electrical property detection, and have the advantages of simple principle and direct test; The key technical device of the present invention has a simple structure and strong compatibility, and is suitable for combining with different commercial AFM control systems. It is a new technology that is easy to promote and apply. This device expands the MLCC micro-region high-accelerated life experiment device that the existing commercial atomic force microscopes do not have, and provides an important new method and new technology for the in-depth development of related AFM technologies and the research on the microscopic scale failure mechanism of MLCC sample materials. Description of the drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1Schematically shows the overall schematic diagram of a micro-region high-accelerated life test device according to the present invention; Figure 2 Schematically shows the structural block diagram of a micro-region high-accelerated life test device according to the present invention; Figure 3 Schematically shows the variation relationship diagram of the heating temperature of the thermal probe with the heating voltage of the DC regulated power supply according to the present invention; Figure 4 Schematically shows the micro-region aging surface topography structure diagram of the MLCC sample material according to the present invention, where Figure 4 (a) is a scanning electron microscope image, Figure 4 (b) is an AFM topography image; Figure 5 Schematically shows the finite element analysis diagram of the temperature distribution in the micro-region aging area of the MLCC sample material according to the present invention, where Figure 5 (a) is a top view, Figure 5 (b) is a cross-sectional view; Figure 6 Schematically shows the micro-region aging leakage current distribution diagram of an MLCC sample material according to the present invention; Figure 7 Schematically shows the micro-region aging leakage current distribution diagram of another MLCC sample material according to the present invention; Figure 8 Schematically shows the Figure 7 micro-region aging leakage current distribution diagram of the MLCC sample material after removing the temperature field in the present invention; Figure 9 Schematically shows the macro-aging leakage current distribution diagram of an MLCC sample material according to the present invention.

[0020] Reference numerals: 12, multi-layer ceramic capacitor; 100, micro-region aging heating module; 11, thermal probe; 111, tip; 15, atomic force microscope unit; 151, AFM control system; 152, AFM sample stage; 153, magnetic metal cushion layer; 18, thermal control unit; 180, DC power supply, 181, DC bridge; 182, first bridge arm; 1821, first fixed resistor; 1822, first potentiometer; 1823, equivalent resistor; 183, second bridge arm; 1831, second fixed resistor; 1832, second potentiometer; 184, voltage limiting unit; 1841, subtraction arithmetic unit; 1842, voltage amplifier; 1843, power supply controller; 200, micro-region aging excitation module; 16, digital source meter; 300, micro-region aging electrical signal detection module; 17, data processing platform. Detailed implementation manners

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention. In addition, it should be understood that the specific embodiments described herein are only for explaining and illustrating the present invention, and are not used to limit the present invention. In the present invention, unless otherwise stated, the orientation words such as "upper", "lower", "left", "right", "front", and "rear" generally refer to the upper, lower, left, and right in the actual use or working state of the device, specifically the drawing direction in the accompanying drawings.

[0022] It should be noted that the description order of the following embodiments does not limit the preferred order of the embodiments of the present invention. And in the following embodiments, each embodiment is described with emphasis. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0023] Based on the urgent need to characterize the micro-region failure behavior of MLCCs at present, the present invention has developed a device for high-accelerated life experiments on the micro-regions of MLCCs based on an AFM nano-platform to achieve in-situ aging of MLCC samples in the micro-region and collection of leakage current signals, providing a simple-principle and direct-testing in-situ nano-characterization technology for the study of in-situ aging and microscopic failure mechanisms of MLCC devices in the micro-region.

[0024] Please refer to Figures 1 - 4 , the present invention provides a micro-region high-accelerated life experiment device for realizing in-situ aging experiments on the micro-regions of multi-layer ceramic capacitors 12 (MLCCs) and in-situ testing of micro-region leakage current. The device includes a micro-region aging heating module 100, a micro-region aging excitation module 200, and a micro-region aging electrical signal detection module 300.

[0025] The micro-region aging heating module 100 includes a thermal control unit 18, a thermal probe 11, and an atomic force microscope unit 15. The multi-layer ceramic capacitor 12 is connected to the atomic force microscope unit 15. The thermal control unit 18 is connected to the thermal probe 11 to heat the thermal probe 11, thereby realizing micro-region aging heating of the multi-layer ceramic capacitor 12 (MLCC) by the thermal probe 11.

[0026] The atomic force microscope unit 15 includes an AFM control system 151, an AFM sample stage 152, and a magnetic metal cushion layer 153. The magnetic metal cushion layer 153 is fixedly arranged on the AFM sample stage 152 through magnetic connection, and the MLCC is fixedly arranged on the magnetic metal cushion layer 153. By providing the magnetic metal cushion layer, the magnetic property of the AFM sample stage can be utilized to enable the magnetic metal cushion layer to be fixedly connected to the AFM sample stage through magnetic connection. The AFM control system 151 is used to at least control the tip 111 of the thermal probe 11 to approach the micro-region to be measured of the multilayer ceramic capacitor 12 in a quasi-static manner, so that the thermal environment at the tip 111 of the thermal probe 11 remains unchanged before and after contact. The AFM control system 151 can implement the scanning of the thermal probe 11 on the surface of the sample material of the multilayer ceramic capacitor 12 and the precise positioning of the micro-region aging area. It can be understood that the AFM control system is part of the atomic force microscope, and preferably the AFM control system is the atomic force microscope (AFM).

[0027] When the tip 111 of the thermal probe 11 contacts the sample surface, the interatomic interaction forces on the sample surface will affect the vibration of the thermal probe 11. These interaction forces can be adsorption forces, repulsive forces, or the forces of chemical bonds. The AFM control system adjusts the distance between the probe and the sample surface according to the change in the interaction forces received by the thermal probe 11 to maintain a constant interaction force, so as to achieve that the AFM control system controls the thermal probe to contact the micro-region to be measured of the multilayer ceramic capacitor in a quasi-static form and keeps the interaction force between the probe and the sample constant, and the relative position unchanged. Furthermore, the AFM control system is used to achieve high-resolution scanning of the sample surface topography.

[0028] The micro-region aging excitation module 200 is used to provide a micro-region aging DC electric field for the sample material of the multilayer ceramic capacitor 12 (MLCC). The micro-region aging electrical signal detection module 300 is used to detect, process, and display the micro-region leakage current signal of the multilayer ceramic capacitor 12 (MLCC) sample.

[0029] Therefore, by setting up the micro-region high-accelerated life test device, by providing the aging DC electric field through the micro-region aging excitation module 200, and by using the micro-region aging heating module 100 to at least age-heat the micro-region to be measured of the multilayer ceramic capacitor 12, the in-situ aging of the micro-region to be measured can be well achieved under the action of aging heating and the micro-region aging DC electric field. At the same time, through the micro-region aging electrical signal detection module 300, the aging condition of the multilayer ceramic capacitor 12 can be intuitively reflected by displaying the leakage current condition of the multilayer ceramic capacitor 12.

[0030] It can be understood that the micro high-accelerated life experiment of the MLCC sample is significantly different from the macro high-accelerated life experiment. The macro high-accelerated life experiment of the MLCC sample is the overall aging of the sample, so the aging current changes smoothly. The micro high-accelerated life experiment only ages dozens of grains near the AFM thermal probe 11, reflecting the defect migration in the micro-region of the sample material. This provides a new evaluation and characterization technique for understanding the micro-region aging and failure mechanism of the MLCC sample material.

[0031] At the same time, for the micro high-accelerated life experiment of the MLCC sample, it is necessary to age only dozens of grains near the AFM thermal probe 11. At this time, the requirements for the device of the high-accelerated life experiment are relatively high, and the existing macro high-accelerated life experiment device cannot meet this requirement.

[0032] Please continue to refer to Figures 1 - 2 , the thermal probe 11 is a high-temperature thermistor probe, whose room temperature resistance value is between 1 kΩ and 3 kΩ, and the thermal control unit 18 is electrically connected to the thermal probe 11. Under the heating voltage of the thermal control unit 18, using the non-linear characteristic of the thermistor, the tip 111 of the thermal probe 11 is heated and the temperature rises. The maximum heating temperature is 600 °C. At this time, by contacting the thermal probe 11 with the multilayer ceramic capacitor 12, the micro-region aging heating of the sample material of the multilayer ceramic capacitor 12 in contact with it can be effectively realized. Preferably, the interaction contact area between the thermal probe 11 and the sample material of the multilayer ceramic capacitor 12 is 10 - 30 nm, the typical value of the acting force of the thermal probe 11 is 100 nN - 200 nN, and the excitation voltage range of the thermal probe 11 is 10 - 800 mV.

[0033] As a specific implementation manner, the relationship between the temperature value of the preferred thermal probe 11 and the excitation voltage of the DC power supply 180 is as Figure 3 shown, which can well meet the experimental requirements.

[0034] Please continue to refer to Figures 1 - 2 , the thermal control unit 18 includes a DC power supply 180, preferably a regulated power supply, a DC bridge, and a voltage limiting unit 184. The voltage limiting unit 184 includes a subtraction arithmetic unit 1841, a voltage amplifier 1842, and a power supply controller 1843. Among them, the DC bridge consists of two bridge arms, including a first bridge arm 182 and a second bridge arm 183.

[0035] For each arm, the components connected in the circuit from the signal input terminal to the ground terminal are, in sequence, the signal input terminal, the first fixed resistor 1821 / second fixed resistor 1831, the first potentiometer 1822 / second potentiometer 1832, the signal output terminal, the load connection terminal, and the ground terminal. The load connection terminal is connected to the thermal probe 11 and the equivalent resistor 1823 with the same room temperature resistance value as that of the thermal probe 11. The signal output terminal of each arm is connected to the subtractor 1841 in the voltage limiting unit 184. The subtractor 1841 is used to calculate the difference between the voltage signals at the output terminals of the two arms of the DC bridge; the voltage amplifier 1842 is a voltage gain module, and the voltage signal gain module can amplify the output voltage signal of the subtraction operation module; the power supply controller 1843 is a voltage signal limiting module, and the voltage signal limiting module can limit the output voltage to prevent excessive voltage output, thereby protecting the backend equipment.

[0036] That is, for the first arm 182, the components connected in the circuit from the signal input terminal to the ground terminal are, in sequence, the signal input terminal (i.e., the DC power supply 180), the first fixed resistor 1821, the first potentiometer 1822, the signal output terminal, the equivalent resistor 1823, and the ground terminal, and the signal output terminal is connected to the voltage limiting unit 184. Similarly, for the second arm 183, the components connected in the circuit from the signal input terminal to the ground terminal are, in sequence, the signal input terminal (i.e., the DC power supply 180), the second fixed resistor 1831, the second potentiometer 1832, the signal output terminal, the thermal probe 11, and the ground terminal, and the signal output terminal is connected to the voltage limiting unit 184.

[0037] Thus, the thermal control unit 18 applies an excitation voltage to the thermal probe 11, causing the tip 111 of the thermal probe 11 to heat up due to the non-linear characteristic of the thermistor, and further heating the micro-region to be measured of the sample material of the multilayer ceramic capacitor 12 in contact therewith, realizing the micro-region aging heating of the sample material of the multilayer ceramic capacitor 12.

[0038] Please continue to refer to Figure 4 , the multilayer ceramic capacitor 12 is a multilayer ceramic capacitor 12 that has been polished until the alternating arrangement of the internal and external electrodes can be observed. During the operation, first, the sample material of the multilayer ceramic capacitor 12 needs to be polished along the direction perpendicular to the electrodes until the alternating internal electrodes appear, so that its surface topography structure is as Figure 4 (a) the scanning electron microscope image shown and Figure 4 (b) the AFM topography image shown by the atomic force microscope, that is, the distribution of the ceramic dielectric layer and the periodic electrode layer can be clearly seen on the multilayer ceramic capacitor 12.

[0039] Subsequently, after fixing the sample of the multilayer ceramic capacitor 12 to the magnetic metal cushion layer 153, conductive silver paste is used to connect the wire to the outer electrode of the sample material of the multilayer ceramic capacitor 12, forming interdigital electrodes on the surface of the sample of the multilayer ceramic capacitor 12 (MLCC).

[0040] It can be understood that the advantage of setting the multilayer ceramic capacitor 12 as the multilayer ceramic capacitor 12 that has been polished until the alternating arrangement of the inner and outer electrodes can be observed is that the tip 111 of the thermal probe 11 can heat the micro-region to be measured of the sample material of the multilayer ceramic capacitor 12 in a quasi-static contact manner, realizing micro-region aging heating of the sample material of the multilayer ceramic capacitor 12.

[0041] Please continue to refer to Figures 1 - 2 , the micro-region aging excitation module 200 includes a digital source meter 16. Among them, the voltage output terminals of the digital source meter 16 are respectively connected to the interdigital electrodes on the surface of the sample of the multilayer ceramic capacitor 12 (MLCC), and are used to provide micro-region aging voltage.

[0042] The advantage of selecting the digital source meter 16 is that in addition to providing micro-region aging voltage, the digital source meter 16 can also directly measure DC voltage, current, resistance and power, and can also provide a highly flexible four-quadrant voltage and current source / load, with voltage and current read-back functions. Preferably, the voltage range of the digital source meter 16 is 20 mV - 200 V, the current range is 10 nA - 1 A, and the measurement accuracy is 0.012%.

[0043] Furthermore, please continue to refer to Figures 1 - 2 , in order to make full use of the digital source meter 16, the micro-region aging electrical signal detection module 300 includes a digital source meter 16 and a data processing platform 17. The interdigital electrodes on the surface of the sample of the multilayer ceramic capacitor 12 are respectively connected to the voltage output terminals of the digital source meter 16, and then the current output terminal of the digital source meter 16 is connected to the data processing platform 17. The data processing platform 17 is a control platform compiled by TestScriptBuilder software based on a computer platform, which realizes automatically stopping when the micro-region aging current reaches a certain limit value, and at the same time realizes real-time signal reading, processing and displaying the micro-region aging leakage current signal of the sample material, so as to analyze the aging process and failure mechanism of the sample material.

[0044] Operation example: The following will further describe the detailed operation process of the micro-region high-acceleration life test device provided by the present invention in the experiment to more comprehensively introduce the solution of the present invention.

[0045] Step 1: Polish the sample material of the multilayer ceramic capacitor 12 along the direction perpendicular to the electrode until the inner electrodes arranged alternately appear, so that its surface morphology structure is as Figure 4The scanning electron microscope image shown in (a) and Figure 4 the AFM topography image shown in (b) can clearly show the distribution of the ceramic dielectric layer and the periodic electrode layer of the multilayer ceramic capacitor 12.

[0046] Step 2: After fixing the multilayer ceramic capacitor 12 MLCC sample on the magnetic metal cushion 153, use conductive silver paste to connect the wire to the external electrode of the multilayer ceramic capacitor 12 MLCC sample material. Subsequently, fix the multilayer ceramic capacitor 12, the micro-region aging excitation module 200, and the AFM sample stage 152, that is, after the silver paste is dried, connect the wires connected to the multilayer ceramic capacitor 12 MLCC to the positive and negative electrodes of the digital source meter 16 respectively, and fix the magnetic metal cushion 153 on the AFM sample material stage.

[0047] At the same time, fix the thermal probe 11 in the thermal probe 11 bracket so that the thermal probe 11 is electrically connected to the micro-region aging heating module 100. Connect the output end of the DC regulated power supply to the input end of the thermal circuit DC bridge module, and connect the output end of the DC bridge to the thermal probe 11. After connecting the data processing module to the signal output end of the digital source meter 16, set the output voltage of the DC regulated power supply to 7 V; set the output voltage of the digital source meter 16 to 200 V, and the electric field strength of the corresponding multilayer ceramic capacitor 12 of the controller is 200 kV / cm.

[0048] Step 3: Apply the DC current excitation signal generated from the DC regulated power supply to the DC bridge in the thermal control unit 18. Since the DC bridge is connected to the thermal probe 11, the temperature of the thermal probe 11 is increased by using the non-linear resistance temperature effect of the thermal probe 11. Based on the relationship between the temperature value of the thermal probe 11 and the excitation voltage of the DC regulated power supply, control the temperature of the thermal probe 11 to the specified temperature. Based on the relationship between the temperature value of the thermal probe 11 and the excitation voltage of the DC regulated power supply, it can be known that when the output voltage of the DC regulated power supply is set to 7 V, the corresponding temperature of the thermal probe 11 is 200 °C.

[0049] Step 4: Use the AFM control system 151 to control the thermal probe 11 to approach and contact the surface of the multilayer ceramic capacitor 12 material in a quasi-static manner, preferably making the tip 111 of the thermal probe 11 contact the multilayer ceramic capacitor 12. After contact, the temperature near the contact area between the thermal probe 11 and the surface of the multilayer ceramic capacitor 12 material sample increases due to the heat conduction of the thermal probe 11. Preferably, use the AFM control system 151 to make the thermal probe 11 contact the multilayer ceramic capacitor 12 sample MLCC, with a contact force of 100 - 200 nN and a contact area of 10 - 30 nm2, so as to ensure the contact stability between the thermal probe 11 and the sample and the stability of heat conduction.

[0050] Step 5: Control the digital source meter 16 to provide an aging voltage for the sample material of the multi-layer ceramic capacitor 12, and record the change of the leakage current signal during the aging process. Or it can also be displayed through the data processing platform 17. Since the aging rate of the multi-layer ceramic capacitor 12 sample will increase significantly when the temperature field and the electric field interact, it can be considered that aging only occurs near the probe heating area, thus realizing the micro-region in-situ aging of the multi-layer ceramic capacitor 12 sample material and the test of its micro-region reliability.

[0051] Meanwhile, by recording the change of the leakage current signal during the aging process, the in-situ micro-region leakage current test experiment of the multi-layer ceramic capacitor 12 can be completed. That is, without adding experimental equipment, the present invention can complete the in-situ micro-region leakage current test experiment while completing the in-situ micro-region aging experiment, improving the experimental efficiency.

[0052] Verification Example 1: In order to further verify the experimental effect of the in-situ micro-region aging experiment of the multi-layer ceramic capacitor 12 provided by the present invention with a micro-region high-accelerated life test device, the implementation results in the above operation example were simulated by the finite element simulation method to further understand the effective heating radius and heating depth of the thermal probe 11. The simulation results are as Figure 5 shown.

[0053] Based on the simulation results, it can be known that the effective heating radius of the high-accelerated life test device provided by the present invention is about 2 μm, the heating depth is about 1.5 μm, and the heating area contains dozens of grains. Therefore, the spatial distribution of the microscopic aging region of the microscopic HALT does correspond to the micro-region space of the multi-layer ceramic capacitor 12 MLCC dielectric layer, and its micro-region aging characteristics reflect the physical responses of dozens of grains. That is, the micro-region high-accelerated life test device of the present invention can realize the in-situ aging of the micro-region to be measured of the multi-layer ceramic capacitor 12, especially the micro-region with only dozens of grains.

[0054] Verification Example 2 Meanwhile, in order to verify the test effect of the in-situ micro-region leakage current test provided by the present invention with a micro-region high-accelerated life test device, in this verification example, a known multi-layer ceramic capacitor 12 with more defects and a highly reliable multi-layer ceramic capacitor 12 were respectively selected for the leakage current verification experiment, and a multi-layer ceramic capacitor 12 was selected for the macroscopic aging experiment as a control.

[0055] Figure 6 The leakage current image of the micro-region aging of an MLCC sample with more defects is given. It can be seen that the sample breaks down when aging in the micro-region for 7 hours, indicating that the sample has many internal defects and poor reliability.

[0056] Figure 7The leakage current images of micro-region aging of an MLCC sample with relatively high reliability are given. It can be seen that the initial leakage current of the microscopic high-accelerated life test of the MLCC device is about 230 nA. After 16 days of aging, the leakage current of the sample still remains at the nA level, indicating that the MLCC sample has few defects and high reliability.

[0057] Figure 8 The leakage current images when the thermal probe is removed and the MLCC is at room temperature are given. It can be seen that the large current during initial pressurization is due to the charging of the MLCC. After charging is completed, the leakage current of the MLCC remains at about 540 nA and does not change significantly for 8 h. This indicates that in the absence of a temperature field and only in the presence of an electric field, the MLCC does not age or the aging process is extremely slow, proving that the aging region is the region heated by the thermal probe.

[0058] Figure 9 A typical macroscopic aging leakage current image of an MLCC is given. The aging current changes smoothly, showing a significant difference between the wavy leakage current curve of micro-region aging and the macroscopic aging leakage current curve, which provides new inspiration for understanding the micro-region aging mechanism.

[0059] Through the verification results of verifying a known multi-layer ceramic capacitor 12 with more defects and a highly reliable multi-layer ceramic capacitor 12, and the comparison results with the macroscopic aging experiment, the feasibility and reliability of the micro-region aging experimental device are further proved. A micro-region high-accelerated life experimental device provided by the present invention can well complete the in-situ measurement of the leakage current of the multi-layer ceramic capacitor 12.

[0060] Example: The present invention provides a device for micro-region high-accelerated life experiment of MLCC based on an atomic force microscope, which is used to realize the in-situ aging experiment of the micro-region of the sample material of the multi-layer ceramic capacitor 12. The device further includes: A micro-region aging heating module 100, which is used to perform DC heating on the thermal probe 11 of the atomic force microscope, and in-situ heat the sample material of the multi-layer ceramic capacitor 12 through the thermal probe 11; A micro-region aging excitation module 200, which is used to apply a DC aging electric field to the sample material of the multi-layer ceramic capacitor 12; A micro-region aging electrical signal detection module 300, which is used to detect, process and display the micro-region aging leakage current signal of the sample material of the multi-layer ceramic capacitor 12.

[0061] Preferably, for the micro-region high-accelerated life experimental device based on an atomic force microscope, the micro-region aging heating module 100 further includes: AFM control system 151, magnetic metal cushion layer 153, AFM sample stage 152, thermal probe 11 and thermal control unit 18. The AFM control system 151, the magnetic metal cushion layer 153 and the AFM sample stage 152 form an atomic force microscopy unit. Among them, the output end of the thermal control unit 18 is connected to the thermal probe 11, a heating voltage is applied to the thermal probe 11, the first-order nonlinear thermosensitive characteristic is excited in-situ and a thermal wave is generated, so as to realize the in-situ micro-region heating of the sample material of the multi-layer ceramic capacitor 12 by the thermal probe 11.

[0062] The sample material of the multi-layer ceramic capacitor 12 is fixed on the magnetic metal cushion layer 153, and the magnetic metal cushion layer 153 is magnetically adsorbed on the AFM sample stage 152; the sample material of the multi-layer ceramic capacitor 12 has two outer electrodes, and is respectively connected to the positive and negative electrodes of the micro-region aging excitation module 200 and the micro-region aging electrical signal detection module 300. The AFM control system 151 controls the tip 111 of the thermal probe 11 to approach the sample material of the multi-layer ceramic capacitor 12 in a quasi-static manner and make surface contact with it. Before and after contact, the thermal environment of the tip 111 of the thermal probe 11 remains unchanged, causing the surface temperature of the sample material of the multi-layer ceramic capacitor 12 to rise, so as to realize micro-region aging heating. The micro-region aging excitation module 200 applies a voltage to cause in-situ aging of the heating region of the sample material of the multi-layer ceramic capacitor 12, and the aging current is collected, processed and displayed by the micro-region electrical detection module.

[0063] Preferably, the micro-region aging voltage excitation module further includes: A digital source meter 16, wherein the voltage output end of the digital source meter 16 is connected to the multi-layer ceramic capacitor 12 MLCC sample, and is used to provide a micro-region aging electric field.

[0064] Preferably, the micro-region aging electrical signal detection module 300 further includes: a sample material of a multi-layer ceramic capacitor 12, and a data processing and display platform. The voltage output end of the digital source meter 16 is connected to the sample material of the multi-layer ceramic capacitor 12, and is used to read the micro-region aging electrical signal of the sample in real time; the data processing and display platform is connected to the current signal output end of the digital source meter 16, and is used to process and display the micro-region aging leakage current signal of the sample material of the multi-layer ceramic capacitor 12.

[0065] Preferably, the AFM control system 151 can realize the scanning of the thermal probe 11 on the surface of the sample material of the multi-layer ceramic capacitor 12 and the precise positioning of the micro-region aging area.

[0066] Preferably, the thermal probe 11 is a high-temperature thermistor probe with a room-temperature resistance value between 1 kΩ and 3 kΩ. Under the action of the heating voltage, the non-linear characteristic of the thermistor is generated, causing the tip 111 of the thermal probe 11 to heat up, and the maximum heating temperature is 600 °C, thereby realizing the micro-area aging heating of the sample material of the multi-layer ceramic capacitor 12 in contact with it.

[0067] Preferably, the interaction contact area between the thermal probe 11 and the sample material of the multi-layer ceramic capacitor 12 is 10 - 30 nm2, the typical value of the acting force of the thermal probe 11 is 100 nN - 200 nN, and the excitation voltage of the thermal probe 11 is 10 - 800 mV.

[0068] Preferably, the sample material of the multi-layer ceramic capacitor 12 is a multi-layer ceramic capacitor 12 (MLCC). The MLCC sample material will age under high temperature and high electric field conditions, and there will be a significant increase in the leakage current signal.

[0069] Preferably, the sample material of the MLCC multi-layer ceramic capacitor 12 needs to be polished to a mirror surface until the internal and external electrodes can be observed to be arranged alternately. The two ends of its internal and external electrodes are connected to the voltage output terminals of the digital source meter 16 for real-time reading of the change in the leakage current signal of the micro-area aging of the sample material of the MLCC multi-layer ceramic capacitor 12.

[0070] Preferably, the thermal control unit 18 further includes: a DC regulated power supply, a DC bridge, a subtraction operation module, a voltage signal gain module, and a voltage signal limiting module. Among them, the DC bridge consists of two bridge arms. The components connected in series in each bridge arm from the signal input terminal to the ground terminal are the signal input terminal, a fixed resistor, a potentiometer, the signal output terminal, the load access terminal, and the ground terminal; the load access terminals are respectively connected to the thermal probe 11 and a linear resistor with the same room-temperature resistance value as the thermal probe 11; the subtraction operation module is used to calculate the difference between the voltage signals at the output terminals of the two bridge arms of the DC bridge; the voltage signal gain module can amplify the voltage signal output by the subtraction operation module; the voltage signal limiting module can limit the output voltage to prevent excessive voltage output, thereby protecting the backend equipment.

[0071] Preferably, the output voltage of the DC regulated power supply is 0 - 10V, which is used to provide the heating voltage for the thermal probe 11.

[0072] Preferably, the digital source meter 16 can directly measure DC voltage, current, resistance, and power, and can also provide highly flexible four-quadrant voltage and current sources / loads, and has the function of voltage and current readback. The voltage range is 20 mV - 200 V, the current range is 10 nA - 1 A, and the measurement accuracy is 0.012%.

[0073] Preferably, the data processing and display platform is a TestScriptBuilder software compilation program control platform, which can automatically stop when the controlled micro-area aging current reaches a certain limit, and simultaneously process and display the leakage current signal of the micro-area aging of the MLCC multi-layer ceramic capacitor 12 sample material.

[0074] In summary, the above examples show that the micro-area high-accelerated life test device can better complete the test of the micro-area aging of MLCC materials and their leakage current characteristics. By developing a micro-area high-accelerated life test device on the AFM platform, the original test of the micro-area morphology image, micro-area aging experiment and aging current change of the MLCC sample material can be realized, providing a new in-situ nano-characterization technology with a simple principle and direct test for the study of the in-situ aging and micro-failure mechanism of MLCC devices.

[0075] In summary, the outstanding advantage of the present invention is to combine the AFM nano-detection function, the thermal probe 11 nano-heating function, the non-linear characteristic of the thermistor, the principle of the macroscopic high-accelerated life test, etc., to establish a new method and device for micro-area high-accelerated life test based on atomic force microscopy. This new method has unique functions of nano-scale micro-area heating, micro-area aging, and micro-area aging current test, and has the advantages of high sensitivity, high signal-to-noise ratio, and direct test, providing a new in-situ nano-characterization technology with a simple principle and direct test for the study of the in-situ aging and micro-failure mechanism of MLCC devices. The key technical device described in the present invention has a simple structure and strong compatibility, and is suitable for combination with different commercial AFM control systems 151. It is a new technology that is easy to promote and apply, and is expected to obtain important applications in the fields of semiconductor materials, optoelectronic materials, energy materials, functional materials, and other materials and devices.

[0076] The above has introduced the solution of the present invention in detail. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

[0077] Reference throughout this specification to "one embodiment", "an embodiment", or "a specific embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention and not necessarily in all embodiments. Thus, the appearances of the phrases "in one embodiment", "in an embodiment", or "in a specific embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics of any specific embodiment of the present invention may be combined in any suitable manner with one or more other embodiments. It is to be understood that other variations and modifications of the embodiments of the invention described and shown herein may be made in accordance with the teachings herein and will be considered part of the spirit and scope of the present invention.

[0078] It should also be understood that one or more of the elements shown in the figures may also be implemented in a more separated or more integrated manner, or even removed in some cases as inoperable or provided because it may be useful for a particular application.

[0079] In addition, any of the marker arrows in the figures should be considered only exemplary and not limiting unless otherwise explicitly specified. Further, unless otherwise indicated, the term "or" as used herein is generally intended to mean "and / or". Where the term is anticipated to be unclear due to the ability to provide separation or combination, the combination of components or steps will also be considered to be specified.

Claims

1. A micro-region high-acceleration life test device for realizing in-situ aging of a to-be-tested micro-region of a multi-layer ceramic capacitor. Characterized in that, Comprising, A micro-region aging heating module, including a thermal control unit, a thermal probe and an atomic force microscope unit. The thermal control unit is connected to the thermal probe for heating the thermal probe. The atomic force microscope unit includes an AFM control system and an AFM sample stage. The multi-layer ceramic capacitor is arranged on the AFM sample stage. The AFM control system is used to control the tip of the thermal probe to approach the to-be-tested micro-region of the multi-layer ceramic capacitor in a quasi-static manner, so that the thermal environment at the tip of the thermal probe remains unchanged before and after contact. A micro-region aging excitation module, electrically connected to the multi-layer ceramic capacitor to provide a micro-region aging DC electric field. Wherein The micro-region aging heating module and the micro-region aging excitation module enable the to-be-tested micro-region to complete in-situ aging under the action of aging heating and the micro-region aging DC electric field.

2. The micro-region high-acceleration life test device according to claim 1, Characterized in that, The thermal probe is a thermosensitive material. The thermal control unit is electrically connected to the thermal probe for applying a heating voltage to the thermal probe to in-situ excite the first-order non-linear thermosensitive characteristic of the thermal probe, so as to realize at least heating and temperature rising of the tip of the thermal probe.

3. The micro-region high-acceleration life test device according to claim 1 or 2, Characterized in that, The thermal control unit includes a DC power supply, a DC bridge and a voltage limiting unit. The DC bridge includes a first bridge arm and a second bridge arm connected in parallel. One end of the first bridge arm is connected to the DC power supply and the other end is grounded. One end of the second bridge arm is connected to the DC power supply and the other end is connected in series with the thermal probe and then grounded. Wherein The voltage limiting unit is respectively connected to the first bridge arm, the second bridge arm and the DC power supply. The voltage limiting unit limits the output voltage of the DC power supply based on the voltage difference between the first bridge arm and the second bridge arm.

4. The micro-region high-acceleration life test device according to claim 3, Characterized in that, The first bridge arm includes a first fixed resistor, a first potentiometer and an equivalent resistor connected in series in sequence. The equivalent resistor is grounded. The second bridge arm includes a second fixed resistor and a second potentiometer connected in series in sequence. One end of the second potentiometer is connected to the second fixed resistor and the other end is connected to the input end of the thermal probe. The output end of the thermal probe is grounded. The connection point of the voltage limiting unit and the first bridge arm is arranged between the first potentiometer and the equivalent resistor. The connection point of the voltage limiting unit and the second bridge arm is arranged between the second potentiometer and the thermal probe. Wherein The resistance value of the equivalent resistor is the same as the resistance value of the thermal probe at room temperature.

5. The micro-region high-acceleration life test device according to claim 3, Characterized in that, The voltage limiting unit includes a subtractor, a voltage amplifier, and a power supply controller. The voltage amplifier is connected to the subtractor and the power supply controller. The subtractor is respectively connected to the first arm and the second arm. The power supply controller is connected to the DC power supply, where the subtractor is configured to calculate the voltage difference between the first arm and the second arm, the voltage amplifier is configured to amplify the voltage difference, and the power supply controller controls the output power of the DC power supply based on the voltage difference amplified by the voltage amplifier.

6. The micro-region high-acceleration life experiment device according to claim 2, characterized in that The contact area between the thermal probe and the multilayer ceramic capacitor is 10 to 30 nm 2 , the acting force value between the thermal probe and the multilayer ceramic capacitor is 100 nN to 200 nN, and the heating voltage applied by the thermal control unit to the thermal probe is 10 to 800 mV.

7. The micro-region high-acceleration life experiment device according to any one of claims 1-6, characterized in that the atomic force microscope unit further includes a magnetic metal cushion layer, the magnetic metal cushion layer is magnetically adsorbed on the AFM sample stage, and the multi-layer ceramic capacitor is fixedly arranged on the magnetic metal cushion layer.

8. The micro-region high-acceleration life experiment device according to any one of claims 1-7, characterized in that it further includes a micro-region aging electrical signal detection module, and the micro-region aging electrical signal detection module is electrically connected to the multi-layer ceramic capacitor to process and display the micro-region leakage current signal of the multi-layer ceramic capacitor.

9. The micro-region high-acceleration life experiment device according to claim 8, characterized in that the micro-region aging excitation module includes a digital source meter, and the voltage output end of the digital source meter is connected to the multi-layer ceramic capacitor to provide an aging electric field, where the micro-region aging electrical signal detection module is connected to the output end of the digital source meter, and is used to process and display the micro-region aging leakage current signal of the multi-layer ceramic capacitor to realize in-situ testing of the leakage current of the micro-region to be measured.

10. The micro-region high-acceleration life experiment device according to any one of claims 1-9, characterized in that the multi-layer ceramic capacitor is a multi-layer ceramic capacitor that has been polished until the internal and external electrodes are alternately arranged and can be observed.

11. A micro-region high-acceleration life experiment method, based on the micro-region high-acceleration life experiment device according to any one of claims 1-10, characterized in that the method includes the following steps: Step 1: Polish the multi-layer ceramic capacitor along the direction perpendicular to the electrodes until the internal electrodes are alternately arranged; Step 2: Fix the multi-layer ceramic capacitor on the magnetic metal cushion layer, use conductive silver paste to connect the wire to the external electrode of the multi-layer ceramic capacitor, and fix the multi-layer ceramic capacitor to the micro-region aging excitation module and the AFM sample stage; Step 3: Use the AFM control system to control the thermal probe to approach the surface of the multi-layer ceramic capacitor material in a quasi-static manner and contact to realize aging heating of the micro-region to be measured, and control the digital source meter to provide an aging voltage for the multi-layer ceramic capacitor sample material, and complete the micro-region in-situ aging experiment under the action of the aging heating and the aging voltage.

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