Quantitative force-electricity coupling chip for transmission electron microscope

Abstract

The utility model discloses a quantitative force-electric coupling chip for a transmission electron microscope, and belongs to the field of high-resolution in-situ characterization of transmission electron microscopes. The chip comprises a quantitative force-electricity coupling chip substrate and a quantitative force-electricity coupling chip device layer, the device layer comprises a suspended device layer and a supporting device layer, and the suspended device layer is composed of a four-electrode structure which is powered on and carried by sample stretching, a two-line method structure which is powered on and carried by sample compression, a scale distance structure for measuring displacement and a mechanical buffer structure. The supporting device layer is composed of a cantilever supporting structure and a piezoresistive structure. The quantitative force-electricity coupling chip for the transmission electron microscope is carried on a double-shaft tilting sample rod (patent number: CN205691408U) for the transmission electron microscope, breaks through the limitation of narrow pole shoe space size and high vacuum environment of the transmission electron microscope, and can be used for realizing the quantitative force-electricity coupling chip for the transmission electron microscope on the premise of ensuring the atomic scale in-situ dynamic observation of the microstructure of a material. Accurate control and acquisition of mechanical and electrical signals are carried out, and quantitative research is carried out on mechanical and electrical properties of materials.

Description

Technical Field

[0001] The purpose of this utility model is to provide an in-situ mechanoelectrical coupling quantitative test platform capable of simultaneously testing the mechanical-electrical coupling properties of micro- and nanoscale samples, and capable of achieving optimal observation angles through biaxial tilt. This platform, when used in conjunction with a TEM, enables real-time monitoring of material microstructural changes, chemical composition evolution, and material property changes, enabling investigation of the relationship between atomic-scale material microstructure and mechanical-electrical coupling properties. Background Art

[0002] With the continuous deepening of research and the continuous development of scientific instruments such as transmission electron microscopes (TEM) and scanning electron microscopes (SEM), people have become extremely interested in the microstructure, mechanical properties and structure-property relationships of materials. In addition, when the characteristic size of a material is reduced to the micro-nanoscale, its mechanical properties are significantly different from those of macroscopic materials, and the mechanical properties of nanomaterials are closely related to their deformation mechanisms at the micro-nanoscale. Therefore, developing a method that can observe in situ in TEM / SEM at the sub-angstrom, atomic or nanoscale the changes in the microstructure of materials as they change with static and dynamic mechanical parameters, and at the same time extract the mechanical-electrical properties of the materials, is of great significance for improving the reliability of micro-nanoelectronic devices and promoting the development of related fields.

[0003] Commercial sample holders available on the market include Hystron's PI nanoindenter, which can perform uniaxial tensile and mechanical property testing of nanomaterials. However, this instrument is expensive, requires customization of a specific experimental environment, and cannot achieve multi-physics field integration.

[0004] The research group led by Researcher Wang Yuelin of the Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, has developed an in-situ characterization device for dynamically mechanically loaded nanomaterials. This device can perform static and dynamic stress loading tests on nanomaterials. However, the chip preparation process is complex, and its electrical testing technology is a two-probe test, which cannot eliminate the influence of the contact resistance between the test material and the sample stage, seriously affecting the accurate measurement of the electrical characteristics of the nanomaterials during the stretching process.

[0005] The in-situ force-thermoelectric multi-field coupled test chip developed by Nie Meng and others at Southeast University can perform static and dynamic stress loading on nanomaterials, as well as measure the electrical and mechanical parameters of samples under different temperature fields. However, the mechanical parameter measurements are characterized by the capacitance change between capacitor plates, resulting in low signal accuracy and significant dependence on the number of capacitor plates and the processing technology. Furthermore, the sample mechanical loading also relies on the capacitor plates, which can provide low stress and is unsuitable for some high-strength samples.

[0006] The sensor developed by Han Xiaodong's research group at Beijing University of Technology for quantitatively testing the electromechanical properties of microstructures applies mechanical loading to the sample through a bimetallic strip, and the applied force is not axial. Moreover, the manufacturing process is not fully compatible with the semiconductor MEMS manufacturing process, resulting in large human errors and the inability to produce in large quantities.

[0007] The piezoresistive, quantitative transmission electron microscope (TEM) electromechanical coupling sample stage described in this utility model is designed to be used in conjunction with the dual-axis tilting sample holder for TEM (Patent No. CN205691408U). It utilizes a piezoelectric ceramic drive and is connected to an external electrical loading and measurement system. The sample stage is placed at the front end of the TEM sample holder. Y-axis tilt is achieved via the tilt motor and tilt linkage within the holder, while X-axis tilt is achieved via the TEM goniometer stage, enabling atomic-scale observation of materials in a specific direction.

[0008] The piezoelectric ceramic at the front end of the sample stage drives the mass block on the sample stage to load the sample area and achieve uniaxial tension / compression deformation of the sample. The transmission electron microscope electromechanical coupling sample stage for piezoresistive quantification is formed using an SOI wafer through bulk silicon etching technology. Ion implantation forms a piezoresistor locally; an Au film is deposited on the surface, and the circuit and electrodes are formed by etching. The electrodes on the MEMS are connected to the external circuit and signal acquisition system to achieve four-electrode circuit loading and measurement in the tension zone, and two-wire method loading and measurement in the compression zone. The signal acquisition system consists of a high-precision, adjustable-range power supply meter. The electrodes on the piezoresistor and MEMS are connected to the external circuit and signal acquisition system to achieve stress and strain measurement in one tension zone and two compression zones.

[0009] The advantage of this utility model is that it can conduct in-situ atomic-scale mechanical-electrical coupling experiments on various materials in a TEM, simultaneously obtaining continuous high-resolution images, precise stress-strain signals, and electrical signals. This device can quantitatively obtain the mechanical-electrical properties of materials and correspond to microstructural changes on the micron to angstrom scale, making it suitable for all types of transmission electron microscopes. Utility Model Content

[0010] The present invention provides a quantitative electromechanical coupling chip for transmission electron microscopy and a preparation method thereof, belonging to the field of high-resolution in-situ characterization of transmission electron microscopy. The chip mainly includes a quantitative electromechanical coupling chip substrate and a quantitative electromechanical coupling chip device layer, wherein the device layer includes a suspended device layer and a supporting device layer. The suspended device layer mainly consists of a four-electrode structure for carrying power and sample tension, a two-wire method structure for carrying power and sample compression, a gauge structure for measuring displacement, and a mechanical buffer structure. The supporting device layer consists of a cantilever support structure and a piezoresistive structure. The quantitative electromechanical coupling chip for transmission electron microscopy provided by the present invention is mounted on a dual-axis tilting sample holder for transmission electron microscopy (patent number: CN205691408U), breaking through the limitations of the narrow pole shoe space size and high vacuum environment of the transmission electron microscope. Under the premise of ensuring in-situ dynamic observation of the material microstructure at the atomic scale, it accurately controls and collects mechanical and electrical signals. While completing the application of the electromechanical coupling physical external field to the material, the mechanical and electrical properties of the material are quantitatively studied.

[0011] The utility model provides a quantitative electromechanical coupling chip for a transmission electron microscope, which is arranged on a dual-axis tilting sample holder of a transmission electron microscope, comprising: a quantitative electromechanical coupling chip substrate and a quantitative electromechanical coupling chip device layer, wherein the device layer is divided into a suspended device layer and a supporting device layer, including:

[0012] Suspended device layer

[0013] S1. Four-electrode structure, the functional structure includes:

[0014] The suspended device layer of the quantitative electromechanical coupling chip is provided with a uniaxial stress conduction component, and a through hole for placing a tensile transmission sample is opened at a certain position of the uniaxial stress conduction component;

[0015] Four metal electrodes are arranged on the surface of the suspended device layer of the quantitative electromechanical coupling chip, and the through hole of the tensile transmission sample opened on the uniaxial stress conduction component is located between the metal electrodes;

[0016] S2. A second-level structure, wherein the functional structure includes:

[0017] The suspended device layer of the quantitative electromechanical coupling chip is provided with a uniaxial stress conduction component, and two groups of through holes for placing compression transmission samples are opened at a certain position of the uniaxial stress conduction component;

[0018] Two metal electrodes are arranged on the surface of the suspended device layer of the quantitative electromechanical coupling chip, and the through hole of the compression transmission sample opened on the uniaxial stress conduction component is located between the metal electrodes;

[0019] S3. Gauge length structure, the functional structure includes:

[0020] Quantitative electromechanical coupling of the chip suspended device layer, the device layer uniaxial stress conduction component has a through hole in the specific area, that is, the gauge structure;

[0021] S4. Buffer structure, the functional structure includes:

[0022] The quantitative electromechanical coupling chip is suspended in the device layer, and a through hole is opened in a specific area of the uniaxial stress conduction component of the device layer, that is, a buffer structure.

[0023] Support device layer

[0024] S1. Cantilever support structure, the functional structure includes:

[0025] The suspended support layer of the quantitative electromechanical coupling chip has different numbers of short cantilever support beams and long cantilever support beams, which are distributed in pairs at both ends of the uniaxial stress conduction component of the suspended device layer of the quantitative electromechanical coupling chip;

[0026] S2. Piezoresistive structure, the functional structure comprising:

[0027] The quantitative electromechanical coupling chip supports the device layer, which is provided with multiple groups of symmetrical cantilever support beams, and the tail ends of two cantilever support beams are provided with pressure-sensitive sensors;

[0028] According to the quantitative electromechanical coupling chip for transmission electron microscopy provided by the utility model, the quantitative electromechanical coupling chip is divided into a base layer and a suspended device layer. The base layer has a certain thickness and plays the role of supporting the device layer, and has a U-shaped groove, so that the device layer structure can be suspended and ensure that the sample area can pass through the electron beam.

[0029] According to the quantitative electromechanical coupling chip for transmission electron microscopy provided by the utility model, the uniaxial stress conduction component of the suspended device layer of the quantitative electromechanical coupling chip is provided with five through holes, namely a buffer structure, a transmission sample compression structure 1, a transmission sample tensile structure, and a transmission sample compression structure 2. The five through holes are arranged in parallel and are all perpendicular to the uniaxial stress conduction direction.

[0030] According to the quantitative electromechanical coupling chip for transmission electron microscopy provided by the utility model, one end of the uniaxial stress conduction component of the suspended device layer of the quantitative electromechanical coupling chip is glued to the piezoelectric ceramic, and the uniaxial stress conduction component is driven to move by supplying power to the piezoelectric ceramic.

[0031] According to the quantitative electromechanical coupling chip for transmission electron microscopy provided by the utility model, the uniaxial stress conduction component of the suspended device layer of the quantitative electromechanical coupling chip moves, and through the cooperation of the buffer structure and the compression / stretching structure of the transmission sample, a certain relative displacement is generated, so that the transmission sample can be stretched or compressed.

[0032] According to the quantitative electromechanical coupling chip for transmission electron microscopy provided by the utility model, the buffer structure on the uniaxial stress conduction component of the suspended device layer of the quantitative electromechanical coupling chip can be cut or supplemented using focused ion beam technology or MEMS lithography technology to control the width, and its width limit should be smaller than the piezoelectric ceramic drive displacement limit.

[0033] According to the quantitative electromechanical coupling chip for transmission electron microscopy provided by the utility model, the quantitative electromechanical coupling chip support device layer has different numbers of short cantilever support beams and long cantilever support beams, wherein the short cantilever support beams can ensure the stiffness of the uniaxial stress conduction component, constrain the displacement direction of the uniaxial stress conduction component, and ensure that the stress state of the sample is in-plane uniaxial stress; the long cantilever support beam moves as the sample area is subjected to force.

[0034] According to the quantitative electromechanical coupling chip for transmission electron microscopy provided by the present invention, pressure-sensitive sensors are provided at the tail ends of the two cantilever support beams of the supporting device layer of the quantitative electromechanical coupling chip, and the area where the sample is located, i.e., the transmission sample compression / tensile structure, is located between the two groups of pressure-sensitive sensors.

[0035] According to the quantitative electromechanical coupling chip for transmission electron microscope provided by the utility model, the pressure-sensitive sensors at the tail ends of the two cantilever support beams of the support device layer of the quantitative electromechanical coupling chip are composed of four piezoresistors. Two resistors are located on the inner side of the end of the beam and their resistance changes with the deformation of the beam. The two piezoresistors are located on the outer side of the beam and their resistance remains unchanged. The resistance change is obtained through a bridge circuit to calculate the stress and strain magnitude.

[0036] The quantitative electromechanical coupling chip for transmission electron microscopy provided by the present invention comprises the following steps:

[0037] S1. Prepare SOI wafer A of appropriate thickness;

[0038] S2.RCA cleans SOI wafer A to ensure that organic and metal ion contaminants are removed from the wafer before high-temperature processing;

[0039] S3. Using a wet etching process or a reactive ion etching process, a groove is etched in the top silicon layer of the SOI wafer A, i.e., the device layer, to obtain a wafer A-1;

[0040] S4. Grow an amorphous thin film having good electron permeability, good chemical inertness, high electrical resistance, high mechanical strength, low residual stress, low average atomic number, and small molecule impermeability on the surface of wafer A-1. The material can be silicon nitride, silicon oxide, silicon carbide, graphene, graphene oxide, boron nitride, etc., to obtain wafer A-2.

[0041] S5. Using a wet etching process or a reactive ion etching process, a groove is etched on the amorphous film grown on the surface of the SOI wafer A-2 to obtain a wafer A-3;

[0042] S6. Using ion implantation technology, locally fabricate a varistor within the groove etched in wafer A-3 to obtain wafer A-4;

[0043] S7. A metal film is grown on the surface of wafer A-4, and a working electrode wire and an alignment mark are formed using an etching process or a lift-off process to obtain wafer A-5;

[0044] S8. A chemically inert, high-resistance metal electrode passivation protective layer is grown on the surface of wafer A-5. The material selected may be silicon nitride, silicon oxide, or a polymer material such as photoresist to obtain wafer A-6.

[0045] S9. Using a wet etching process or a reactive ion etching process, etching the device layer on the surface of wafer A-6 to produce a device layer cantilever beam to obtain wafer A-7;

[0046] S10. Using an etching process, etching wafer A-7 from the back to form a substrate through-hole to obtain wafer A-8;

[0047] S11. Slice wafer A-8 to obtain single independent chips.

[0048] The utility model has the following advantages:

[0049] 1. The quantitative electromechanical coupling chip for transmission electron microscopy (TEM) provided by this utility model is mounted on a dual-axis tilting sample holder for TEM (Patent No.: CN205691408U). This overcomes the limitations of the TEM's narrow pole piece dimensions and high vacuum environment. While ensuring in-situ dynamic observation of material microstructures at the atomic scale, it precisely controls and collects mechanical and electrical signals. This allows for the application of an external electromechanical coupling physical field to the material while simultaneously enabling quantitative research into the material's mechanical and electrical properties.

[0050] 2. The combined use of piezoelectric ceramics and quantitative electromechanical coupling chips for transmission electron microscopy can perform various mechanical tests such as tension, compression, and bending on various types of samples, including but not limited to nanowires, two-dimensional nanofilms, and bulk materials, ensuring coaxial stress application to the samples while having a large stress application capacity.

[0051] 3. By designing cantilever support beams of different numbers, shapes, and lengths, the chip's seismic resistance is ensured while greatly reducing sample breakage caused by external vibrations. The special design of the cantilever support beam also ensures in-plane and coaxial stress loading on the sample.

[0052] 4. The introduction of multiple groups of varistors can achieve high-precision and real-time acquisition of sample stress and strain data while applying stress to the sample.

[0053] 5. The quantitative electromechanical coupling chip for transmission electron microscopy provided by the present invention can be used to conduct in-situ atomic-scale electromechanical coupling experiments on various materials in various TEMs. It can simultaneously obtain continuous high-resolution images, precise stress-strain signals, and electrical signals, quantitatively acquire the electromechanical properties of materials, and correspond to material microstructural changes at the micron to angstrom scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art.

[0055] Figure 1 Schematic diagram of the transmission electron microscope electromechanical coupling sample stage for piezoresistance quantification

[0056] Figure 2 This is the front view of the device layer

[0057] Figure 3 Enlarged view of the sample area

[0058] Figure 4 A magnified diagram of the piezoresistive area circuit

[0059] The accompanying drawings are described as follows:

[0060] 1-Chip substrate; 2-Support device layer; 3-Sample power circuit; 4-Varistor circuit; 5-Suspended device layer; 6-Cantilever support beam; 7-Buffer structure; 8-Uniaxial stress conduction component; 9-Uniaxial stress sensing component; 10-Sample area; 11-Compression sample area; 12-Tension sample area; 13-Varistor. DETAILED DESCRIPTION

[0061] The present invention will be further described with reference to the accompanying drawings:

[0062] The device is divided into a chip substrate 1, a supporting device layer 2 and a suspended device layer 5. The substrate layer has a certain thickness and plays the role of supporting the device layer. It also has a U-shaped groove, which allows the device layer structure to be suspended and ensures that the sample area can pass through the electron beam. Figure 1 .

[0063] The suspended device layer 5 is partially bonded to the piezoelectric ceramic. The uniaxial stress conduction component is driven to move by supplying power to the piezoelectric ceramic. The uniaxial stress conduction component contacts the buffer structure 7, driving the uniaxial stress conduction component 8 to move and displace relative to the uniaxial stress conduction component 9, so that the samples in the three sample areas are subjected to stress.

[0064] The buffer structure 7 can be cut or added using FIB to control its width, and its width should be within the driving range of the piezoelectric ceramic.

[0065] The tensile sample area 12 can be adjusted by FIB cutting. The sample area length should be adjustable within 0-50 microns, and the compression sample area should be adjustable within 20-80 microns. Figure 3 .

[0066] The uniaxial stress conduction component 9 can be fixed to the supporting device layer 2, or its rear end can be cut off by FIB to form a suspended structure.

[0067] Samples can be loaded using FIB technology or by using the drop method followed by FIB removal of excess sample loading. Tensile samples can be loaded between a pair of electrodes for a two-wire loading measurement, or between two pairs of electrodes for a four-electrode measurement. Compression zone samples require a conductive probe to form an ohmic contact with the sample after compression contact, allowing for a two-wire measurement.

[0068] There are two groups of pressure-sensitive sensors, which are respectively located at the tail end of the supporting cantilever beam connected to the uniaxial stress conduction component 8 and the uniaxial stress conduction component 9. Each group of sensor bridge circuits has four piezoresistors 13 formed by ion implantation. Two resistors are located on the inner side of the end of the beam and change their resistance as the beam deforms. The two piezoresistors are located on the outer side of the beam and their resistance remains unchanged. The resistance change is obtained through the bridge circuit to calculate the stress and strain magnitude, such as Figure 4 .

[0069] The varistor circuit should be a Wheatstone bridge circuit, with one group responsible for input power and one group for measurement. The two groups of pressure sensors have a total of 8 leads, and 8 solder points are located at the front end.

[0070] Four leads are drawn out from the sample area, and four solder joints are located at the rear end. Each pair of electrodes is separated by the four electrodes of the varistor, e.g. Figure 2 .

[0071] The solder joints are press-bonded to the internal circuit of the sample holder by metal wires, forming an ohmic contact.

Claims

1. A quantitative electromechanical coupling chip for transmission electron microscopy, mounted on a dual-axis tilting sample holder of a transmission electron microscope, characterized in that: include: Quantitative electromechanical coupling chip substrate and quantitative electromechanical coupling chip device layer, wherein the device layer is divided into a suspended device layer and a supporting device layer; The suspended device layer includes: Four-electrode structure, including: The suspended device layer of the quantitative electromechanical coupling chip is provided with a uniaxial stress conduction component, and the uniaxial stress conduction component is provided with a through hole for placing a tensile transmission sample; Four metal electrodes are arranged on the surface of the suspended device layer of the quantitative electromechanical coupling chip, and the through hole of the tensile transmission sample opened on the uniaxial stress conduction component is located between the metal electrodes; The second-stage structure includes: The suspended device layer of the quantitative electromechanical coupling chip is provided with a uniaxial stress conduction component, which has two groups of through holes for placing compression transmission samples; Two metal electrodes are arranged on the surface of the suspended device layer of the quantitative electromechanical coupling chip, and the through hole of the compression transmission sample opened on the uniaxial stress conduction component is located between the metal electrodes; Gauge length structure, including: The uniaxial stress conduction component of the device layer is provided with a through hole, i.e., a gauge structure; Buffer structure, including: The quantified electromechanical coupling chip suspends the device layer, and a through hole is opened on the uniaxial stress conduction component of the device layer, i.e., a buffer structure; The supporting device layer includes: Cantilever support structure, its functional structure includes: The suspended support layer of the quantitative electromechanical coupling chip has different numbers of short cantilever support beams and long cantilever support beams, which are distributed in pairs at both ends of the uniaxial stress conduction component of the suspended device layer of the quantitative electromechanical coupling chip; Piezoresistive structure, its functional structure includes: The quantitative electromechanical coupling chip supports the device layer, and the supporting device layer is provided with multiple groups of symmetrical cantilever support beams, wherein the tail ends of two cantilever support beams are provided with pressure-sensitive sensors; the quantitative electromechanical coupling chip is divided into a base layer and a suspended device layer, the base layer is thicker than the device layer, and has a U-shaped groove.

2. The quantitative electromechanical coupling chip for transmission electron microscopy according to claim 1, characterized in that: The uniaxial stress conduction component of the suspended device layer of the quantitative electromechanical coupling chip is provided with five through holes, namely a buffer structure, a transmission sample compression structure 1, a transmission sample tensile structure, and a transmission sample compression structure 2. The five through holes are arranged in parallel and are all perpendicular to the uniaxial stress conduction direction.

3. The quantitative electromechanical coupling chip for transmission electron microscopy according to claim 2, characterized in that: One end of the uniaxial stress conduction component of the suspended device layer of the quantitative electromechanical coupling chip is glued to the piezoelectric ceramic, and the uniaxial stress conduction component is driven to move by supplying power to the piezoelectric ceramic.

4. The quantitative electromechanical coupling chip for transmission electron microscopy according to claim 2, characterized in that: The uniaxial stress conduction component of the suspended device layer of the quantitative electromechanical coupling chip moves, and through the cooperation of the buffer structure and the compression / tension structure of the transmission sample, a relative displacement is generated to cause the transmission sample to be stretched or compressed.

5. The quantitative electromechanical coupling chip for transmission electron microscopy according to claim 1, characterized in that: The buffer structure on the uniaxial stress conduction component of the suspended device layer of the quantitative electromechanical coupling chip is cut or supplemented using focused ion beam technology or MEMS lithography technology to control the width, and the maximum width is smaller than the piezoelectric ceramic drive displacement limit.

6. The quantitative electromechanical coupling chip for transmission electron microscopy according to claim 1, characterized in that: The quantitative electromechanical coupling chip support device layer has different numbers of short cantilever support beams and long cantilever support beams, wherein the short cantilever support beams ensure the stiffness of the uniaxial stress conduction component; and the long cantilever support beams move as the sample area is subjected to force.

7. The quantitative electromechanical coupling chip for transmission electron microscopy according to claim 1, characterized in that: Pressure-sensitive sensors are provided at the tail ends of the two cantilever support beams of the quantitative electromechanical coupling chip support device layer, and the area where the sample is located, that is, the transmission sample compression / tensile structure, is located between the two groups of pressure-sensitive sensors.

8. The quantitative electromechanical coupling chip for transmission electron microscopy according to claim 1, characterized in that: The pressure-sensitive sensors at the tail ends of the two cantilever support beams of the quantitative electromechanical coupling chip support device layer are composed of four pressure-sensitive resistors.

Images