In-situ transmission electron microscope heating chip and preparation method thereof

Abstract

The present invention provides an in-situ transmission electron microscope heating chip and a preparation method thereof. The in-situ transmission electron microscope heating chip comprises: a substrate, a through hole is opened in the middle, and a plurality of positioning holes are arranged on the periphery; a thin film insulation layer, and a heat insulation groove is arranged on the periphery of the thin film insulation layer corresponding to the through hole; a heating resistor layer is arranged on the top of the thin film insulation layer, and the heating resistor layer is coiled on the edge of the through hole. The in-situ transmission electron microscope heating chip and the preparation method thereof provided by the present invention reduce the heating volume of the heating resistor layer by setting the through hole, reduce the heating power of the in-situ transmission electron microscope heating chip, reduce the thermal drift generated by the chip during the heating process, and make the transmission electron microscope imaging more stable and clear; the ultra-large field of view is used for experimental observation, and the sample preparation is simpler and more convenient; the heat insulation groove effectively constrains the temperature diffusion of the heating resistor layer, makes the temperature as concentrated as possible, and reduces the thermal influence of the heating resistor layer on the external electron microscope accessories during the heating process.

Description

Technical Field

[0001] The invention relates to the technical field of heating chips, and in particular to an in-situ transmission electron microscope heating chip and a preparation method thereof. Background Art

[0002] At present, with the progress of electron microscopy and micro-nano processing, in-situ transmission electron microscopy technology has also been developed more maturely. In-situ transmission electron microscopy analysis technology can apply gaseous and liquid environments and single or coupled external fields such as radiation, force, heat, and electricity to study the evolution of the microstructure of materials under external fields in real time and establish the correlation between the microstructure and its physical and chemical properties.

[0003] Among them, achieving the application of a uniform thermal field in a transmission electron microscope and in situ characterizing the microstructural evolution of materials at the atomic level are still difficult problems in the field of in situ transmission electron microscopy technology.

[0004] Different in-situ experimental platforms have been developed in the prior art, such as the model 652 transmission electron microscope double-tilt in-situ heating sample rod developed by Gatan Corporation in the United States. By designing a heating crucible made of different materials at the front end of the sample rod, a temperature field of up to 1000°C can be applied to the sample; but due to the large heating area of ​​the crucible, when a higher heating temperature is applied to the sample, the large heating power of the crucible causes a large thermal drift of the sample, which directly affects the resolution of the experimental observation. In addition, the wildfire series transmission electron microscope sample rod developed by DensSolution in the Netherlands uses a MEMS chip at the front end of the sample rod to apply a temperature field of up to 1300°C to the sample. However, its observation area is small and the sample preparation process is complicated. Summary of the invention

[0005] The present invention provides an in-situ transmission electron microscope heating chip and a preparation method thereof, which are used to solve the defects of small observation area and complicated sample preparation in the prior art, and complete an in-situ transmission electron microscope heating chip with simple structure and convenient preparation. The in-situ transmission electron microscope heating chip can be mass-produced through a micro-electromechanical system processing technology, and the in-situ observation of larger-sized transmission samples at different temperatures in the in-situ transmission electron microscope is realized.

[0006] The present invention provides an in-situ transmission electron microscope heating chip, which is arranged on a mounting platform, and a plurality of screw holes are provided on the mounting platform, including:

[0007] A base, wherein a through hole is provided in the middle thereof, and positioning holes corresponding to the screw holes are provided on the periphery thereof;

[0008] A thin film insulating layer is disposed on the top of the substrate, and a heat-insulating groove is disposed on the outer periphery of the thin film insulating layer corresponding to the through hole;

[0009] The heating resistor layer is arranged on the top of the thin film insulating layer, and the heating resistor layer is coiled around the edge of the through hole.

[0010] According to an in-situ transmission electron microscope heating chip provided by the present invention, the thermal insulation groove and the heating resistor layer are arranged in an annular shape, the through hole is arranged in a circle, and the thermal insulation groove, the heating resistor layer and the through hole are arranged concentrically; and the heating resistor layer is located between the thermal insulation groove and the through hole.

[0011] According to an in-situ transmission electron microscope heating chip provided by the present invention, the corners of the heating resistor layer are all arranged in a blunt-angle or rounded-angle wiring manner.

[0012] According to an in-situ transmission electron microscope heating chip provided by the present invention, the heating resistor layer is a serpentine metal resistor, and the serpentine metal resistor is arranged to be divided into an upper half ring metal resistor and a lower half ring metal resistor through two sections of horizontal metal wires; the upper half ring metal resistor and the lower half ring metal resistor are connected to the circuit in parallel; the horizontal metal wire is connected to an external power supply through a lead and a bonding area.

[0013] An in-situ transmission electron microscope heating chip provided by the present invention further includes an electrode protection layer, which is arranged on the top of the heating resistor layer and completely or partially wraps the thin film insulation layer and the heating resistor layer.

[0014] According to an in-situ transmission electron microscope heating chip provided by the present invention, the heating resistor layer is an equidistant ring-shaped heating resistor, and the distance between the rings is equal; the spacing between the rings and the distance between the corners where the rings are connected can be adjusted to make the temperature field of the heating core more uniform.

[0015] According to an in-situ transmission electron microscope heating chip provided by the present invention, the heating resistor layer includes an inner circle circular ring-shaped metal resistor and an outer circle double helix asymptotic ring-shaped resistor, the inner circle circular ring-shaped metal resistor is concentric with the through hole and is located at the edge of the through hole, and the outer circle double helix asymptotic ring-shaped resistor is connected to the inner circle circular ring-shaped metal resistor and is located outside the inner circle circular ring-shaped metal resistor; by adjusting the width of the inner circle circular ring-shaped metal resistor, the width of the outer circle double helix asymptotic ring-shaped resistor, and the spacing of the outer circle double helix asymptotic ring-shaped resistor, the temperature field of the heating chip is made more uniform.

[0016] According to an in-situ transmission electron microscope heating chip provided by the present invention, the thin film insulating layer is a silicon nitride layer and / or a silicon oxide layer.

[0017] The present invention also provides a method for preparing an in-situ transmission electron microscope heating chip, comprising the steps of:

[0018] Providing a single crystal silicon wafer A and cleaning it;

[0019] Processing thin film insulating layers on both sides of single crystal silicon wafer A to obtain wafer A-1;

[0020] A metal film is formed on the surface of wafer A-1 to form a heating resistor, thereby obtaining wafer A-2;

[0021] A layer of silicon nitride and silicon oxide is first grown on the surface of wafer A-2 by using LPCVD or PECVD process, and then the silicon nitride or silicon oxide on the area to be etched of wafer A-2 is etched away by using reactive ion etching process to form a heat-insulating groove; thus, wafer A-3 is obtained;

[0022] The base silicon of wafer A-3 is exposed and completely etched to form a central through hole; thus obtaining wafer A-4;

[0023] Wafer A-4 is diced to obtain single independent chips.

[0024] According to a method for preparing an in-situ transmission electron microscope heating chip provided by the present invention, the step processes a thin film insulating layer on a single crystal silicon wafer A to obtain a wafer A-1, wherein the thin film insulating layer is a silicon nitride layer and / or a silicon oxide layer, and the thickness of the thin film insulating layer is 10nm-2μm.

[0025] The in-situ transmission electron microscope heating chip and the preparation method thereof provided by the present invention reduce the heating volume of the heating resistor layer and the heating power of the in-situ transmission electron microscope heating chip by arranging a through hole in the middle of the substrate, reduce the thermal drift generated by the chip during the heating process, make the transmission electron microscope imaging more stable and clear, and provide an ultra-large field of view for experimental observation. Compared with the traditional heating chip, the sample preparation is simpler and more convenient. The micro-electromechanical system processing technology can be used for batch production to realize the in-situ observation of large-sized transmission samples at different temperatures in the transmission electron microscope. The heat insulation groove arranged on the thin film insulation layer effectively restricts the temperature diffusion of the heating resistor layer, makes the temperature as concentrated as possible, and reduces the thermal influence of the heating resistor layer on the external electron microscope accessories during the heating process. At the same time, the arrangement of the positioning hole and the screw hole can not only more accurately fix the chip on the mounting table, but also avoid the pollution introduced by the adhesive at high temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in 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. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 It is a structural schematic diagram of Example 1 of the in-situ transmission electron microscope heating chip provided by the present invention;

[0028] Figure 2 It is a structural schematic diagram of Example 2 of the in-situ transmission electron microscope heating chip provided by the present invention;

[0029] Figure 3 is a schematic structural diagram of Example 3 of the in-situ transmission electron microscope heating chip provided by the present invention;

[0030] Reference numerals:

[0031] 1: substrate; 2: film insulation layer; 3: heating resistor layer; 4: thermal insulation groove; 5: upper half ring metal resistor; 6: lower half ring metal resistor; 7: horizontal metal wire; 8: through hole; 9: positioning hole; 10: inner ring metal resistor; 11: outer double spiral asymptotic ring resistor. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Combine the following Figure 1 Embodiment 1 of the present invention is described, providing an in-situ transmission electron microscope heating chip, which is arranged on a mounting platform, and a plurality of screw holes are provided on the mounting platform, including a substrate 1, a thin film insulating layer 2 and a heating resistor layer 3. A through hole 8 is provided in the center of the substrate 1, and positioning holes 9 corresponding to the screw holes are provided around the substrate 1. The positioning holes 9 and the screw holes can not only fix the chip on the mounting platform more accurately, but also avoid the contamination introduced by the adhesive at high temperature. The through hole 8 forms an observation area for microscopic in-situ observation; the thin film insulating layer 2 is arranged on the top of the substrate 1, and the thin film insulating layer 2 is provided with a heat insulation groove 4 corresponding to the outer periphery of the through hole 8; the heating resistor layer 3 is arranged on the top of the thin film insulating layer 2, and the heating resistor layer 3 is coiled around the edge of the through hole 8.

[0034] The chip provided in Example 1 of the present invention has a simple structure and is easy to prepare. It can be mass-produced through a micro-electromechanical system (MEMS) process, and realizes in-situ observation of larger-sized transmission samples at different temperatures in a transmission electron microscope.

[0035] Specifically, the base 1 is set to be rectangular, the heat insulation groove 4 and the heating resistor layer 3 are set to be annular, the through hole 8 is set to be a circular hole, and the heat insulation groove 4, the heating resistor layer 3 and the through hole 8 are set concentrically; and the heating resistor layer 3 is located between the heat insulation groove 4 and the through hole 8; a positioning hole 9 is set on each side of the rectangular base 1; the thin film insulation layer 2 adopts a silicon nitride layer and / or a silicon oxide layer; the heating resistor layer 3 is annular and is located between the heat insulation groove 4 and the through hole 8. That is, the heating resistor layer 3 is set on the periphery of the through hole 8; the heat insulation groove 4 is set on the periphery of the heating resistor layer 3.

[0036] The corners of the heating resistor layer are all arranged in an obtuse or rounded manner, so that the temperature field of the heating chip is more uniform.

[0037] Furthermore, the heating resistor layer 3 is configured as a serpentine metal resistor, which is centrally symmetrical as a whole and is coiled around the edge of the through hole in a circular ring shape, and the spacing between the resistance wires of the sections inside the circular ring is smaller than the spacing between the resistance wires of the sections outside the circular ring. The serpentine metal resistor is configured to be divided into an upper half ring metal resistor 5 and a lower half ring metal resistor 6 through two sections of horizontal metal wires 7; the upper half ring metal resistor 5 and the lower half ring metal resistor 6 are connected to the circuit in parallel; the horizontal metal wire 7 is connected to an external power supply; at the same time, the upper half ring metal resistor 5 and the lower half ring metal resistor 6 are wired in a blunt or rounded manner at the corners.

[0038] Moreover, the serpentine metal resistor is relatively thin, and the distal lead and the bonding area are positioned as wide as possible.

[0039] In this embodiment, the heating resistor layer 3 is a serpentine metal resistor wire coiled into a ring and arranged at the edge of the through hole 8 in the center of the substrate. While heating the ultra-large transmission sample, the temperature field on the sample is made as uniform and stable as possible, which effectively ensures a high temperature uniformity in the heating area.

[0040] The annular heat-insulating groove 4 provided on the thin-film insulating layer 2, on the one hand, reduces the heat conduction path, heats the volume, and reduces the heating efficiency; on the other hand, it can effectively restrain the temperature diffusion, make the temperature as concentrated as possible, reduce the thermal impact of the heating resistor layer 3 on the external electron microscope accessories during the heating process, and improve the service life of the heating chip.

[0041] The through hole 8 in the center of the substrate significantly reduces the heating volume of the heating resistor layer 3, reduces the heating power of the ultra-large temperature zone heating chip for the transmission electron microscope, reduces the thermal drift generated by the chip during the heating process, and makes the transmission electron microscope imaging more stable and clear. In addition, while ensuring that a uniform temperature field is applied to large-sized transmission samples, the through hole 8 satisfies the experimental phenomenon of in-situ observation of the transmission electron microscope sample heating process within the ultra-large field of view area. At the same time, the setting of the ultra-large field of view makes the heating chip disclosed in the present invention simpler and more convenient to prepare samples than the traditional heating chip.

[0042] The method of using the embodiment disclosed in the present invention is as follows: a mechanical connection structure is used to fix the in-situ transmission electron microscope heating chip to the mounting table at the front end of the double-tilt sample rod of the transmission electron microscope, ensuring that the positioning holes and the screw holes correspond one to one. The wire is led from the tail end of the heating resistor layer 3 to the transmission electron microscope sample rod by ultrasonic pressure welding. The transmission electron microscope sample rod is inserted into the transmission electron microscope, and the transmission electron microscope parameters are adjusted to the optimal observation state. When the sample is stable, a certain current or a certain voltage is applied to the heating resistor according to the experimental requirements. While accurately controlling the temperature field in which the sample is located, the microstructural evolution of the material is observed in situ and the physical and chemical properties of the material are measured.

[0043] The in-situ transmission electron microscope heating chip disclosed in this embodiment is used for the in-situ sample rod of the transmission electron microscope, which maximizes the observation of the atomic-scale microstructure and the study of the physical and chemical properties of the material in a uniform thermal field in an ultra-large temperature range.

[0044] In addition, the use of resistive heating and sample mounting on silicon oxide or silicon nitride films effectively reduces the heating volume and improves the thermal response rate. While accelerating the thermal equilibrium rate, it reduces the heating power and reduces the thermal drift of the sample.

[0045] At the same time, the setting of the ultra-large area heating zone in the embodiment of the present invention makes the preparation of transmission electron microscope heating samples simpler. In addition to using focused ion beam technology to prepare samples, conventional ion thinning samples and double-spray thinning samples can also be directly mounted on the ultra-large temperature zone heating chip for transmission electron microscope.

[0046] Finally, the present invention adopts an axisymmetric design, which can increase the stability of the chip structure, and the chip temperature distribution and stress distribution are more reasonable.

[0047] Combination Figure 2 Embodiment 2 of the present invention is described, and an in-situ transmission electron microscope heating chip is provided. Embodiment 2 is based on embodiment 1, and differs from embodiment 1 in that the resistance heating layer 3 is arranged as equidistant annular heating resistors, and the distances between the rings are equal, and the connecting corners between the rings are all located at the bottom of the annular heating resistors, and by adjusting the spacing between the rings and the distances between the corners of the connection between the rings, the temperature field at the transmission electron microscope sample is made as uniform and stable as possible.

[0048] Combination Figure 3Embodiment 3 of the present invention is described, and an in-situ transmission electron microscope heating chip is provided. Embodiment 3 is based on embodiment 1, and differs from embodiment 1 in that the shape of the heating resistor layer 3 is differently set. The annularly coiled serpentine resistor in embodiment 1 is replaced with an inner circle circular ring-shaped metal resistor 10 and an outer circle double helix asymptotic ring-shaped resistor 11. The inner circle circular ring-shaped metal resistor 10 is concentric with the through hole 8 and is located at the edge of the through hole 8. The outer circle double helix asymptotic ring-shaped resistor 11 is connected to the inner circle circular ring-shaped metal resistor 10 and is located on the outside of the inner circle circular ring-shaped metal resistor 10.

[0049] Embodiment 3 of the present invention makes the temperature field at the transmission electron microscope sample as uniform and stable as possible by adjusting the wire width of the inner ring metal resistor and the outer double helix asymptotic ring resistor, as well as the spacing between the spiral asymptotes of the outer spiral asymptotic ring resistor.

[0050] Another aspect of the present invention also discloses a method for preparing an in-situ transmission electron microscope heating chip, comprising the following steps:

[0051] S1, providing a single crystal silicon wafer A and cleaning it to form a substrate 1;

[0052] S2, forming a thin film insulating layer 2 on both sides of the single crystal silicon wafer to obtain a wafer A-1;

[0053] S3, forming a metal film on the surface of the wafer A-1 to form a heating resistor layer 3, thereby obtaining a wafer A-2;

[0054] S4, using LPCVD or PECVD process to grow a layer of silicon nitride and silicon oxide on the surface of wafer A-2, and then using reactive ion etching process to etch away the silicon nitride or silicon oxide on the area to be etched of wafer A-2 to form a heat-insulating groove 4; obtaining wafer A-3;

[0055] S5, exposing and completely etching the base silicon of wafer A-3 to form through hole 5; obtaining wafer A-4;

[0056] S6. Slice the wafer A-4 to obtain a single independent chip.

[0057] Wherein, in step S1, the thickness of the single crystal silicon wafer is 50-500μm; and RCA cleaning is adopted. The RCA standard cleaning method is a typical and most commonly used wet chemical cleaning method. RCA cleaning uses a suitable cleaning agent to first remove organic contamination on the surface of the silicon wafer, because organic matter will cover part of the silicon wafer surface, making it difficult to remove the oxide film and the contamination associated therewith; then dissolve the oxide film, because the oxide layer is a "contamination trap" and will also introduce epitaxial defects; finally, remove particles, metals and other contamination, and passivate the surface of the silicon wafer. RCA cleaning ensures that organic matter and metal ion contaminants are removed from the wafer before high-temperature processing.

[0058] In step S2, the thin film insulating layer 2 is a silicon nitride layer and / or an oxide layer, and the thickness of the thin film insulating layer 2 is 10 nm-2 μm.

[0059] In step S3, the thickness of the heating resistor layer 3 is 10nm-2μm. At the same time, the material of the heating resistor layer 3 is one or more of platinum, gold, silver, copper, molybdenum, tungsten, aluminum, and chromium. The heating material is compatible with the micro-electromechanical system process.

[0060] It should be noted that the single crystal silicon wafer can also be replaced by SOI, which introduces a buried oxide layer between the top silicon and the back substrate to form a semiconductor film on the insulator.

[0061] This embodiment adopts semiconductor micro-electromechanical system manufacturing technology, which can achieve mass production with the same and controllable quality.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An in-situ transmission electron microscope heating chip is arranged on a mounting platform, wherein a plurality of screw holes are provided on the mounting platform, wherein: include: A base, wherein a through hole is provided in the middle thereof, and positioning holes corresponding to the screw holes are provided on the periphery thereof; A thin film insulating layer is disposed on the top of the substrate, and a heat-insulating groove is disposed on the outer periphery of the thin film insulating layer corresponding to the through hole; The heating resistor layer is arranged on the top of the thin film insulating layer, the heating resistor layer is coiled on the edge of the through hole, and the heat insulation groove is arranged on the periphery of the heating resistor layer.

2. The in-situ transmission electron microscope heating chip according to claim 1, characterized in that: The heat-insulating groove and the heating resistor layer are arranged in an annular shape, the through hole is arranged in a circular shape, and the heat-insulating groove, the heating resistor layer and the through hole are arranged concentrically.

3. The in-situ transmission electron microscope heating chip according to claim 2, characterized in that: The corners of the heating resistor layer are all arranged in an obtuse or rounded manner.

4. The in-situ transmission electron microscope heating chip according to claim 2, characterized in that: The heating resistor layer is a serpentine metal resistor, which is divided into an upper half ring metal resistor and a lower half ring metal resistor through two sections of horizontal metal wires; the upper half ring metal resistor and the lower half ring metal resistor are connected in parallel to the circuit; and the horizontal metal wire is connected to an external power supply.

5. The in-situ transmission electron microscope heating chip according to claim 2, characterized in that: It also includes an electrode protection layer, which is arranged on the top of the heating resistor layer and completely or partially wraps the thin film insulation layer and the heating resistor layer.

6. The in-situ transmission electron microscope heating chip according to claim 2, characterized in that: The heating resistor layer is an equidistant annular heating resistor, and the distances between the rings are equal; the spacing between the rings and the distances between the corners where the rings are connected can be adjusted to make the temperature field of the heating core more uniform.

7. The in-situ transmission electron microscope heating chip according to claim 2, characterized in that: The heating resistor layer includes an inner circle circular ring-shaped metal resistor and an outer circle double helix asymptotic ring-shaped resistor, the inner circle circular ring-shaped metal resistor is concentric with the through hole and is located at the edge of the through hole, and the outer circle double helix asymptotic ring-shaped resistor is connected to the inner circle circular ring-shaped metal resistor and is located outside the inner circle circular ring-shaped metal resistor; the width of the inner circle circular ring-shaped metal resistor, the width of the outer circle double helix asymptotic ring-shaped resistor, and the spacing of the outer circle double helix asymptotic ring-shaped resistor can be adjusted to make the temperature field of the heating chip more uniform.

8. The in-situ transmission electron microscope heating chip according to any one of claims 1 to 7, characterized in that: The thin film insulating layer is a silicon nitride layer and / or a silicon oxide layer.

9. A method for preparing an in-situ transmission electron microscope heating chip, characterized in that: Includes steps: Providing a single crystal silicon wafer A and cleaning it; Processing thin film insulating layers on both sides of single crystal silicon wafer A to obtain wafer A-1; A metal film is formed on the surface of wafer A-1 to form a heating resistor, thereby obtaining wafer A-2; A layer of silicon nitride and silicon oxide is first grown on the surface of wafer A-2 by using LPCVD or PECVD process, and then the silicon nitride or silicon oxide on the area to be etched of wafer A-2 is etched away by using reactive ion etching process to form a heat-insulating groove, thereby obtaining wafer A-3; The base silicon of wafer A-3 is exposed and completely etched to form a central through hole; Obtain wafer A-4; Wafer A-4 is diced to obtain single independent chips.

10. The method for preparing an in-situ transmission electron microscope heating chip according to claim 9, characterized in that: In the step, thin film insulating layers are processed on both sides of the single crystal silicon wafer A to obtain wafer A-1, wherein the thin film insulating layer is a silicon nitride layer and / or a silicon oxide layer, and the thickness of the thin film insulating layer is 10nm-2μm.

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