Graphene heating chip and preparation method thereof

Abstract

The application discloses a graphene heating chip, which comprises a substrate, an insulating layer, a graphene film and a plurality of electrodes; the substrate has opposite first and second surfaces, and the substrate is provided with a through hole; the insulating layer is suspended at the through hole and covers the through hole; the insulating layer not in direct contact with the first surface defines a window, and a plurality of grooves are arranged on the window; the graphene film covers the window, the graphene film comprises a first part graphene film and a second part graphene film, and the first part graphene film and the second part graphene film are arranged at intervals; and the plurality of electrodes are located on the surface of the insulating layer away from the substrate. The application also provides a preparation method of the graphene heating chip.

Description

Technical Field

[0001] This invention relates to a graphene heating chip and its preparation method, and more particularly to a graphene heating chip for in-situ TEM (transmission electron microscopy) and its preparation method. Background Technology

[0002] The combination of microelectromechanical systems (MEMS) and transmission electron microscopy (TEM) has made significant progress in in-situ TEM characterization. TEM offers ultra-high spatial resolution for observing microscopic dynamic processes. It is well known that sub-angstrom spatial resolution can be achieved through aberration-corrected TEM. Currently, various in-situ TEM techniques have been developed, including in-situ heating, in-situ bias application, in-situ stress application, and in-situ ventilation. The main functional component of a TEM microheater chip is the electron-transparent window, which is typically formed by depositing a metal resistance wire on suspended silicon nitride (SiN). X Formed on the film, a metal resistive layer and SiN X The film forms a bilayer structure. This microheater has an ultra-low heat capacity, enabling low power consumption and rapid, precise temperature control. However, the metal resistive layer and SiN... X The different coefficients of thermal expansion of the films cause the electron transparent window to expand and bulge at high temperatures, which can cause the sample to move out of the optimal focal point. Therefore, the expansion of the electron transparent window can seriously affect the dynamic observation of the sample during TEM characterization. Summary of the Invention

[0003] In view of this, it is indeed necessary to provide a graphene heating chip and its preparation method that can dynamically observe samples during TEM characterization.

[0004] A graphene heating chip includes a substrate, an insulating layer, a graphene film, and multiple electrodes. The substrate has a first surface and a second surface facing each other. A through-hole is formed in the substrate, extending from the first surface to the second surface. The insulating layer is located on the first surface and is suspended at the through-hole. An insulating layer covering the through-hole and not in direct contact with the first surface is defined as a window, on which multiple grooves are formed. The graphene film is located on the surface of the insulating layer away from the substrate and covers the window. The graphene film includes a first portion of graphene film and a second portion of graphene film, which are spaced apart. The multiple electrodes are located on the surface of the insulating layer away from the substrate and are sequentially named a first electrode, a second electrode, a third electrode, a fourth electrode, a fifth electrode, a sixth electrode, and a seventh electrode. The third electrode is in direct contact with the first portion of graphene film, the fourth electrode is in direct contact with the second portion of graphene film, the first electrode is in direct contact with the second electrode, the fifth electrode and the sixth electrode are in direct contact, and the second electrode is in direct contact with the fifth electrode. That is, the first electrode, the second electrode, the fifth electrode, and the sixth electrode are all in contact with each other. The first portion of the graphene film and the second portion of the graphene film are both in direct contact with the seventh electrode.

[0005] A method for preparing a graphene heating chip includes the following steps:

[0006] A substrate is provided, the substrate having opposing first and second surfaces;

[0007] An insulating layer is disposed on the first surface;

[0008] Multiple electrodes are disposed on the surface of the insulating layer away from the substrate, and these multiple electrodes are named sequentially as first electrode, second electrode, third electrode, fourth electrode, fifth electrode, sixth electrode and seventh electrode;

[0009] A through hole is provided in the substrate, which extends from the first surface to the second surface, thereby suspending the insulating layer at the through hole. The insulating layer that covers the through hole and does not directly contact the first surface is defined as a window.

[0010] A graphene film is disposed on the surface of the insulating layer away from the substrate, and the graphene film covers the window;

[0011] Remove all graphene films except for the window to expose the plurality of electrodes, and cut the graphene film located at the window into a first part and a second part, which are spaced apart; the third electrode is in direct contact with the first part of the graphene film, the fourth electrode is in direct contact with the second part of the graphene film, the first electrode is in direct contact with the second electrode, the fifth electrode and the sixth electrode are in direct contact, and the second electrode is in direct contact with the fifth electrode; both the first part and the second part of the graphene film are in direct contact with the seventh electrode; and

[0012] Multiple grooves are formed on the insulating layer between the first part of the graphene film and the second part of the graphene film.

[0013] Compared with the prior art, the graphene heating chip provided by the present invention can be heated to 800°C in 26.31ms and to 1000°C in 30ms; moreover, the expansion or deformation of the sample cell is very small, with an expansion or deformation of only 50nm at 650°C, thus enabling dynamic observation of the sample during the TEM characterization process. Attached Figure Description

[0014] Figure 1 The process flow diagram is shown for the preparation method of the graphene heating chip provided in the first embodiment of the present invention.

[0015] Figure 2 A process flow diagram illustrating the fabrication method of a graphene heating chip provided in a specific embodiment of the present invention.

[0016] Figure 3 A microscope image of the sample cell provided in the first embodiment of the present invention.

[0017] Figure 4 The first embodiment of the present invention provides a wafer-level graphene heating chip prepared in batches.

[0018] Figure 5 This is a schematic diagram of the graphene heating chip provided in the second embodiment of the present invention.

[0019] Figure 6 A stereomicroscope image of the graphene heating chip provided in the second embodiment of the present invention.

[0020] Figure 7 The Raman spectrum of the graphene film in the graphene heating chip provided in the second embodiment of the present invention.

[0021] Figure 8 The temperature-voltage line of the graphene heating chip provided in the second embodiment of the present invention.

[0022] Figure 9 Suspended SiN provided in the second embodiment of the present invention X The photograph of the membrane at high temperature was taken with a Canon camera equipped with a macro lens.

[0023] Figure 10 The temperature rise curve of the graphene heating chip at 800°C provided in the second embodiment of the present invention.

[0024] Figure 11 This is a TEM image of gold particles with the highest resolution concentric height at room temperature, provided for a second embodiment of the present invention.

[0025] Figure 12 TEM image of gold particles heated to 650°C, provided for a second embodiment of the present invention.

[0026] Figure 13 A TEM image of tin nanoparticles at room temperature, provided for a second embodiment of the present invention.

[0027] Figure 14 for Figure 13 The image obtained from the Fast Fourier Transform.

[0028] Figure 15 TEM image of tin nanoparticles at 240°C provided in the second embodiment of the present invention.

[0029] Figure 16 for Figure 15 The image obtained from the Fast Fourier Transform.

[0030] Figure 17 This invention provides a method for calibrating the temperature of the graphene heating chip according to a third embodiment.

[0031] Figure 18 The resistance-temperature straight line obtained by linear fitting is provided in the third embodiment of the present invention.

[0032] Explanation of main component symbols

[0033] Graphene heating chip 100

[0034] Base 10

[0035] First surface 102

[0036] Second surface 104

[0037] Through hole 106

[0038] Insulation layer 12

[0039] Part 1 Insulation Layer 122

[0040] Part Two Insulation Layer 124

[0041] Groove 126

[0042] First electrode 141

[0043] Second electrode 142

[0044] Third electrode 143

[0045] Fourth electrode 144

[0046] Fifth electrode 145

[0047] Sixth electrode 146

[0048] Seventh electrode 148

[0049] Graphene film 16

[0050] Part 1: Graphene Film 162

[0051] Part Two: Graphene Film 164

[0052] Barrier layer 18

[0053] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0054] The graphene heating chip and its preparation method, as well as the temperature calibration method of the graphene heating chip, provided by the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] Please see Figure 1 and Figure 5 The first embodiment of the present invention provides a method for preparing a graphene heating chip 100, which includes the following steps:

[0056] S1, a substrate 10 is provided, the substrate 10 having opposing first surface 102 and second surface 104;

[0057] S2, An insulating layer 12 is provided on the first surface 102;

[0058] S3, seven electrodes are disposed on the surface of the insulating layer 12 away from the substrate 10, and the seven electrodes are named in sequence as first electrode 141, second electrode 142, third electrode 143, fourth electrode 144, fifth electrode 145, sixth electrode 146 and seventh electrode 148.

[0059] S4, a through hole 106 is provided in the substrate 10, which extends from the first surface 102 to the second surface 104, so that the insulating layer 12 is suspended in the through hole 106. The insulating layer 12 that covers the through hole 106 and does not directly contact the first surface 102 is defined as a window; that is, the insulating layer 12 that covers the through hole 106 and is spaced apart from the first surface 102 is defined as a window.

[0060] S5, a graphene film 16 is disposed on the surface of the insulating layer 12 away from the substrate 10, and the graphene film 16 covers the window;

[0061] S6, remove the graphene films 16 other than the window, thereby exposing the first electrode 141, second electrode 142, third electrode 143, fourth electrode 144, fifth electrode 145, sixth electrode 146, and seventh electrode 148. The graphene film 16 located at the window is cut into a first portion 162 and a second portion 164, with the first portion 162 and the second portion 164 arranged side-by-side at an interval. The third electrode 143 is in direct contact with the first portion 162, and both the first electrode 141 and the second electrode 142 are located on the side of the third electrode 143 away from the first portion 162. The fourth electrode 144 is in direct contact with the window. The second portion of the graphene film 164 is in direct contact with the fourth electrode 144. The fifth electrode 145 and the sixth electrode 146 are both located on the side of the fourth electrode 144 away from the second portion of the graphene film 164. The first electrode 141 is in direct contact with the second electrode 142, the fifth electrode 145 and the sixth electrode 146 are in direct contact, and the second electrode 142 is in direct contact with the fifth electrode 145. Both the first portion of the graphene film 162 and the second portion of the graphene film 164 are in direct contact with the seventh electrode 148. The first electrode 141, the second electrode 142, the third electrode 143, the fourth electrode 144, the fifth electrode 145, and the sixth electrode 146 are not in contact with the seventh electrode 148.

[0062] Step S7: Multiple grooves 126 are formed on the insulating layer 12 between the first portion of the graphene film 162 and the second portion of the graphene film 164, serving as sample cells to hold the sample, such as... Figure 3 As shown.

[0063] In step S1, the material of the substrate 10 can be a conductor, semiconductor, or insulating material. Specifically, the material of the substrate 10 can be gallium nitride, gallium arsenide, sapphire, aluminum oxide, magnesium oxide, silicon, silicon dioxide, silicon nitride, quartz, or glass, etc. The material of the substrate 10 can also be flexible materials such as polyethylene terephthalate (PET) or polyimide (PI). Furthermore, the material of the substrate 10 can also be a doped semiconductor material, such as p-type gallium nitride, n-type gallium nitride, etc. The size, thickness, and shape of the substrate 10 are not limited and can be selected according to actual needs. In a specific embodiment, the substrate 10 is a silicon wafer with silicon oxide having a thickness of 200 nm (nanometers).

[0064] In step S2, the insulating layer 12 is made of silicon nitride (SiN). X The insulating layer 12 is thin and transparent to electrons, and is made of materials such as silicon carbide. The thickness of the insulating layer 12 is 50 nm to 200 nm. Preferably, the insulating layer 12 is silicon nitride (SiN). X In one specific embodiment, the insulating layer 12 is a silicon nitride (SiN) film with a thickness of 200 nm. X )membrane.

[0065] In step S3, the materials of the first electrode 141 to the seventh electrode 148 (i.e., the first electrode 141, the second electrode 142, the third electrode 143, the fourth electrode 144, the fifth electrode 145, the sixth electrode 146, and the seventh electrode 148) have good conductivity. Specifically, the materials of the first electrode 141 to the seventh electrode 148 can be conductive materials such as metals, alloys, indium tin oxide (ITO), antimony tin oxide (ATO), conductive silver paste, conductive polymers, and metallic carbon nanotube films. Depending on the type of material used to form the first electrode 141 to the seventh electrode 148, different methods can be used to form the first electrode 141 to the seventh electrode 148. Specifically, when the materials of the first electrode 141 to the seventh electrode 148 are metals, alloys, ITO, or ATO, the first electrode 141 to the seventh electrode 148 can be formed by methods such as evaporation, sputtering, deposition, masking, and etching. When the materials of the first electrode 141 to the seventh electrode 148 are conductive silver paste, conductive polymer, or carbon nanotube film, the conductive silver paste or carbon nanotube film can be coated or adhered to the surface of the insulating layer 12 away from the substrate 10 by printing or direct adhesion methods to form the first electrode 141 to the seventh electrode 148. The thickness of the first electrode 141 to the seventh electrode 148 is 0.5 nanometers to 100 micrometers. In a specific embodiment, the first electrode 141 to the seventh electrode 148 are Cr / Pt electrodes formed by electron beam evaporation, wherein the Cr / Pt electrode is formed by depositing a 5 nm thick Cr (chromium) layer on a 50 nm thick Pt (platinum) layer.

[0066] In step S4, the insulating layer 12 can be considered as two parts: one part directly contacts the first surface 102, and the other part covers the through hole 106 and does not directly contact the first surface 102. The method for forming the through hole 106 is not limited, such as plasma etching, laser etching, etc. This embodiment provides a method for forming the through hole 106, specifically including the following steps:

[0067] S41, a barrier layer 18 is provided on the second surface 104 of the substrate 10;

[0068] S42, an opening is etched in the barrier layer 18, through which the second surface 104 of the substrate 10 is exposed;

[0069] S43, the substrate 10 and the etched barrier layer 18 are placed in an etching solution, or the etching solution is dripped into the opening. The etching solution passes through the opening and contacts the substrate 10. The etching solution reacts chemically with the substrate 10, thereby forming the through hole 106 on the substrate 10. The opening and the through hole 106 correspond one-to-one. The insulating layer 12 is suspended at the opening and the through hole 106, and the insulating layer 12 is exposed through the opening and the through hole 106.

[0070] In step S41, the material of the barrier layer 18 does not chemically react with the etching solution. In a specific embodiment, the substrate 10 is a silicon wafer with a layer of silicon dioxide on both the first surface 102 and the second surface 104, and the barrier layer 18 is silicon nitride (SiN). X )membrane.

[0071] In step S42, the method for etching the opening is photolithography, plasma etching, or other methods.

[0072] In step S43, the etching solution does not react with the insulating layer 12 or the six electrodes, but only with the substrate 10, thereby forming the through-hole 106 on the substrate 10. In a specific embodiment, the substrate 10 is a silicon wafer with a layer of silicon dioxide on both the first surface 102 and the second surface 104, and the etching solution is a potassium hydroxide (KOH) solution.

[0073] Furthermore, step S43 may also include a step of removing the barrier layer 18.

[0074] In step S5, preferably, the thickness of the graphene film 16 is a single atomic layer, that is, the graphene film 16 is a single layer. The preparation method of the graphene film 16 includes the following steps:

[0075] S51, the graphene film 16 is grown on a growth substrate 10;

[0076] S52, an adhesive layer is coated on the surface of the graphene film 16 away from the growth substrate 10;

[0077] S53, Remove the growth substrate 10;

[0078] S54, the adhesive layer and the graphene film 16 are disposed on the surface of the insulating layer 12 away from the substrate 10, the graphene film 16 is in direct contact with the insulating layer 12, and the graphene film 16 is located between the adhesive layer and the insulating layer 12;

[0079] S55, Remove the adhesive layer.

[0080] In step S51, the method for growing the graphene film 16 on the growth substrate 10 is not limited. In a specific embodiment, the process of growing the graphene film 16 on the growth substrate 10 is as follows: a catalyst layer is deposited on the growth substrate 10, and then the growth substrate 10 with the catalyst layer deposited is placed in a reaction chamber, a carbon source gas is introduced, and the reaction chamber is heated to 800°C to 1000°C, thereby growing the graphene film 16 on the growth substrate 10.

[0081] The growth substrate 10 can be made of copper, and its size is not limited and can be selected according to actual needs.

[0082] A metal or metal compound material is deposited on the surface of the growth substrate 10 to form the catalyst layer. The metal may be one of gold, silver, copper, iron, cobalt, and nickel, or any combination thereof. The metal compound may be one of zinc sulfide, zinc oxide, ferric nitrate, ferric chloride, and copper chloride, or any combination thereof. The method for depositing the catalyst layer on the growth substrate 10 is not limited, and may include chemical vapor deposition, physical vapor deposition, vacuum thermal evaporation, magnetron sputtering, plasma-enhanced chemical vapor deposition, or printing, etc.

[0083] The reaction chamber is a sealed cavity with an inlet and an outlet. The inlet is used to introduce reaction gases, such as carbon source gases, and the outlet is connected to a vacuum device. The vacuum device controls the vacuum level and gas pressure of the reaction chamber through the outlet. Further, the reaction chamber may also include a water-cooling device and a heating device to control the temperature within the reaction chamber. In this embodiment, the reaction chamber is a quartz tube.

[0084] The carbon source gas can be a compound such as methane, ethane, ethylene, or acetylene. A non-oxidizing gas such as hydrogen can be introduced into the reaction chamber. Under continuous introduction of the non-oxidizing gas, when the temperature in the reaction chamber reaches 800℃~1000℃, the carbon source gas decomposes, depositing carbon atoms on the surface of the catalyst layer to form a graphene film 16. The flow rate of the carbon source gas is 20 sccm (standard conditions, mL / min) to 90 sccm, and the flow rate ratio of the non-oxidizing gas to the carbon source gas ranges from 45:2 to 15:2. The reaction chamber can also be a vacuum environment with a pressure of 10⁻¹ to 10² Pa. The isothermal time for growing the graphene film 16 is 10 min to 60 min. Preferably, the pressure in the reaction chamber is 500 mTorr, the reaction temperature is 1000℃, the carbon source gas is methane, the flow rate is 25 sccm, and the isothermal time is 30 min.

[0085] In step S52, the material of the adhesive layer is not limited, nor is the method of applying the adhesive layer, such as spin coating or deposition. In one specific embodiment, the material of the adhesive layer is PMMA (methyl methacrylate).

[0086] In step S53, the method for removing the growth substrate 10 is not limited. For example, the growth substrate 10 can be removed by chemical etching. The material of the growth substrate 10 is copper, and the solution for removing the growth substrate 10 is sulfuric acid, nitric acid, hydrochloric acid, or a mixture of hydrogen peroxide, hydrochloric acid, and deionized water (the volume ratio of hydrogen peroxide, hydrochloric acid, and deionized water is 1:1:50). In a specific embodiment, the material of the growth substrate 10 is copper, and the solution for removing the growth substrate 10 is a mixture of hydrogen peroxide, hydrochloric acid, and deionized water (the volume ratio of hydrogen peroxide, hydrochloric acid, and deionized water is 1:1:50).

[0087] After removing the growth substrate 10, the process further includes a rinsing step with water or an organic solvent to remove residual impurities. The water is preferably deionized water, and the type of organic solvent is not limited, such as isopropanol.

[0088] Step S55: Remove the adhesive layer using an organic solvent. The type of organic solvent is not limited, such as acetone or ethanol.

[0089] In step S6, the first electrode 141 is in direct contact with the second electrode 142, and the portion of the first electrode 141 in direct contact with the second electrode 142 is located on the window. The fifth electrode 145 and the sixth electrode 146 are in direct contact, and the portion of the fifth electrode 145 in direct contact with the sixth electrode 146 is located on the window. The portions of the first electrode 141 in direct contact with the second electrode 142, the portions of the fifth electrode 145 in direct contact with the sixth electrode 146, and the portions of the second electrode 142 in direct contact with the fifth electrode 145 are all located between the first portion of the graphene film 162 and the second portion of the graphene film 164, and none of them directly contact the first portion of the graphene film 162 and the second portion of the graphene film 164. That is, the first electrode 141, the second electrode 142, the fifth electrode 145, and the sixth electrode 146 do not directly contact the graphene film 16 and are electrically insulated from it. The first electrode 141, the second electrode 142, the fifth electrode 145, and the sixth electrode 146 are all in direct contact. The first portion of the graphene film 162 and the second portion of the graphene film 164 are both in direct contact with the seventh electrode 148. The first electrode 141, the second electrode 142, the third electrode 143, the fourth electrode 144, the fifth electrode 145, and the sixth electrode 146 do not contact or are electrically connected to the seventh electrode 148. Figure 5 As shown.

[0090] In one specific embodiment, the graphene film 16 is transferred from copper foil to the surface of a treated silicon wafer using a wet transfer technique, and then etched onto the SiN wafer using photolithography and dry etching. X The graphene is cut into two pieces on the window. The method for removing the other graphene films 16, excluding the window, is not limited.

[0091] In one specific embodiment, a method of first patterning photolithography and then gas plasma etching is used to remove the graphene film 16 other than the window. Specifically, a mask is used to cover the graphene film 16. The mask has holes, and the graphene film 16 at the window is in direct contact with the mask. The graphene film 16 other than the window is exposed through the holes. The graphene film 16 exposed through the holes is etched away by gas plasma, and finally the mask is removed.

[0092] In step S7, the method for forming a sample cell by creating multiple grooves 126 on the insulating layer 12 is not limited; for example, a method of patterning photolithography followed by gas plasma etching can be used. Specifically, a mask is used to cover the graphene film 16, and the mask has multiple holes. The insulating layer 12 (SiN) XThe areas on the insulating layer 12 where the grooves 126 are to be formed are exposed through these holes, while other areas are covered by the mask. The insulating layer 12 exposed through these holes is etched using gas plasma to form a plurality of spaced grooves 126 on the insulating layer 12. Finally, the mask is removed. The shape of the grooves 126 is not limited, and the thickness of the grooves 126 is from 1 nm to 100 nm. Preferably, the thickness of the grooves 126 is 10 nm, 20 nm, 30 nm, 40 nm, or 50 nm. Because the grooves 126 are etched on the insulating layer 12, the thickness of the grooves 126 is thinner, thereby ensuring that the thickness of the sample cell is thin enough to allow electrons to pass through or be transparent to electrons. In one specific embodiment, the thickness of the grooves 126 is 50 nm.

[0093] The following specific embodiment illustrates the preparation method of the graphene heating chip 100, but is not limited thereto.

[0094] Please see Figure 2 The substrate 10 is a silicon wafer with a layer of SiO2 on both opposite surfaces, and then SiN is deposited on each layer of SiO2. X The film is thus formed into a five-layer SiN structure. X (Thickness 200nm) / SiO2 (Thickness 200nm) / Si (Thickness 400μm) / SiO2 (Thickness 200nm) / SiN X (Thickness is 200nm), such as Figure 2 The first small figure shows the top SiN layer formed by electron beam evaporation. X Patterned 5nm / 50nm Cr / Pt electrodes are deposited on the film, forming six electrode pads, as shown. Figure 2 The second small image shows this. Then, from the bottom SiN... X With the film facing upwards, a five-layer SiN structure was fabricated using photolithography and gas plasma etching (CF4 gas, flow rate 40 sccm, pressure 2 Pa, power 50 W, etching time 5.5 min). X / SiO2 / Si / SiO2 / SiN X SiO2 / SiN under the middle silicon wafer X Layer etching creates openings, exposing a portion of the silicon wafer. After 8 hours of KOH solvent etching, the silicon wafer and the SiO2 film on it are also etched to form vias 106. That is, a five-layer SiN structure... X / SiO2 / Si / SiO2 / SiN X Except for the top SiN X The other four layers outside the membrane were etched to form vias 106, with SiN on top of these vias 106. X The membrane is suspended, thus forming a window. The SiN suspended at the through-hole 106... XThe membrane has an area of ​​730 μm × 730 μm and a thickness of 200 nm, such as Figure 2 The third small figure shows the process. To ensure the sample cell is thin enough to allow electrons to pass through, the suspended SiN... X A sample cell was formed on the membrane using a secondary gas plasma etching method (CF4 gas, flow rate 40 sccm, pressure 2 Pa, power 50 W, etching time 4.5 min). The sample cell had a thickness of 50 nm and a diameter of 3 μm. Figure 3 As shown. Graphene sheets are transferred to the top SiN using a transfer method. X On the membrane. Using photolithography and gas plasma etching (O2 gas, flow rate 40 sccm, pressure 2 Pa, power 20 W, etching time 20 s), the graphene sheet was cut into two pieces, and all graphene except for the graphene sheet at the square window was etched away to expose the six electrode pads, such as... Figure 2 As shown in the fourth small image. Thus, the graphene heating chip 100 is obtained. Additionally, as... Figure 4 As shown, multiple graphene heating chips 100 can be simultaneously formed directly on a 4-inch wafer to form wafer-level graphene heating chips 100. Then, by cutting with a diamond saw, a single graphene heating chip 100 can be obtained.

[0095] Please see Figure 3 , Figure 5 and Figure 6 The second embodiment of the present invention provides a graphene heating chip 100, which includes a substrate 10, an insulating layer 12, a graphene film 16 and six electrodes.

[0096] The substrate 10 has a first surface 102 and a second surface 104 opposite to each other, and the substrate 10 is provided with a through hole 106 that extends from the first surface 102 to the second surface 104.

[0097] The insulating layer 12 is located on the first surface 102 and is suspended at the through-hole 106. The insulating layer 12 consists of a first insulating layer 122 and a second insulating layer 124, which are arranged side-by-side and in direct contact. The first insulating layer 122 is in direct contact with the first surface 102 of the substrate 10. The second insulating layer 124 covers the through-hole 106 and is not in direct contact with the first surface 102; the second insulating layer 124 can be defined as the window. Multiple grooves 126 are provided on the second insulating layer 124 as sample cells for holding samples. That is, the sample cells are located in the second insulating layer 124.

[0098] The six electrodes are located on the surface of the insulating layer 12 away from the substrate 10. Specifically, the six electrodes are located on the surface of the first portion of the insulating layer 122 away from the substrate 10. The six electrodes are named sequentially as first electrode 141, second electrode 142, third electrode 143, fourth electrode 144, fifth electrode 145, and sixth electrode 146. The second portion of the insulating layer 124 has a first side and a second side. The first electrode 141, second electrode 142, and third electrode 143 are disposed on the first side, and the fourth electrode 144, fifth electrode 145, and sixth electrode 146 are disposed on the second side. That is, from left to right, these six electrodes are named first electrode 141, second electrode 142, third electrode 143, fourth electrode 144, fifth electrode 145, and sixth electrode 146.

[0099] The graphene film 16 is located on the surface of the second insulating layer 124 away from the substrate 10, and the graphene film 16 covers the window. In one specific embodiment, the graphene film 16 is located only on the second insulating layer 124, or only on the window. The graphene film 16 includes a first graphene film 162 and a second graphene film 164, and the first graphene film 162 and the second graphene film 164 are arranged side by side with a gap. The third electrode 143 is in direct contact with the first graphene film 162, and the first electrode 141 and the second electrode 142 are both located on the side of the third electrode 143 away from the first graphene film 162. The fourth electrode 144 is in direct contact with the second graphene film 164, and the fifth electrode 145 and the sixth electrode 146 are both located on the side of the fourth electrode 144 away from the second graphene film 164. The first electrode 141 is in direct contact with the second electrode 142, the fifth electrode 145 and the sixth electrode 146 are in direct contact, and the second electrode 142 is in direct contact with the fifth electrode 145.

[0100] The first electrode 141 is in direct contact with the second electrode 142, and the portion of the first electrode 141 in direct contact with the second electrode 142 is located on the second insulating layer 124. The fifth electrode 145 and the sixth electrode 146 are in direct contact, and the portion of the fifth electrode 145 and the sixth electrode 146 in direct contact is located on the second insulating layer 124. The second electrode 142 is in direct contact with the fifth electrode 145, and the portion of the second electrode 142 in direct contact with the fifth electrode 145 is located in the middle of the first graphene film 162 and the second graphene film 164, and none of them directly contact the first graphene film 162 and the second graphene film 164. That is, the first electrode 141, the second electrode 142, the fifth electrode 145 and the sixth electrode 146 do not directly contact the graphene film 16, nor are they electrically connected to the graphene film 16.

[0101] The plurality of grooves 126 are located between the first portion of the graphene film 162 and the second portion of the graphene film 164. That is, the sample cell formed by the plurality of grooves 126 is located on the insulating layer 12 between the first portion of the graphene film 162 and the second portion of the graphene film 164.

[0102] The graphene heating chip 100 may further include the barrier layer 18, which is located on the second surface of the substrate 10. The barrier layer 18 has an opening that corresponds one-to-one with the through hole 106. The insulating layer 12 is suspended at the opening and the through hole 106 and is exposed through the opening and the through hole 106.

[0103] The materials and dimensions of the substrate 10, insulating layer 12, graphene film 16, and electrodes, as well as the shape and dimensions of the groove 126, have been described in detail in the first embodiment and will not be repeated here.

[0104] In one specific embodiment, SiN is used in the groove 126. X The film thickness is 50nm, which can ensure the SiN X The film is electron-transparent under a transmission electron microscope (TEM), allowing electrons to pass through the SiN. X membrane.

[0105] The following is a performance characterization of the graphene heating chip 100.

[0106] Figure 3 This is a microscope image of the sample cell. The sample cell is located in the center of the window, as shown. Figure 3 As shown in the rectangular region, the sample cell is composed of multiple circular grooves 126.

[0107] Figure 7 The image shows the Raman spectrum of the graphene film 16 in the graphene heating chip 100. Figure 7 It can be seen that the graphene film 16 is a single layer.

[0108] Figure 8 This is the temperature-voltage line for the graphene heating chip 100, wherein the voltage is applied to the graphene film 16. Figure 8 It is known that the graphene heating chip 100 can be heated to 1000°C within 30ms.

[0109] Figure 9 This image, taken with a Canon camera equipped with a macro lens, shows suspended SiN at high temperatures. X A photograph of the membrane (i.e., the second portion of the insulating layer 124, or the window). (By...) Figure 9 It can be seen that the suspended SiN X The film becomes brighter as the heating power increases, indicating that the heating temperature distribution in the sample cell region of the graphene heater is uniform, which is beneficial for in-situ TEM observation.

[0110] Graphene film 16 serves as a resistive layer for heating, effectively heating suspended SiN. X The temperature of the film (i.e., the first portion of the insulating layer 122) can be regulated by the input power. Although the power is uniformly applied to the SiN... X On the window, however, the central area of ​​the window is hotter than the edges. This is because of the suspended SiN... X The silicon surrounding the film can be considered a heat sink, and Joule heat is transferred from SiN. X The center of the membrane conducts to the heat sink, thereby in SiN X A temperature gradient is induced on the film. Compared to the localized heating of metal wires currently used, the graphene film 16 provides overall heating of the suspended SiN. X The film can effectively reduce the temperature gradient and improve the performance of SiN. X The temperature uniformity in the central region of the membrane, where the sample cell is located, ensures a uniform heating temperature distribution in the sample cell region, which is beneficial for in-situ TEM observation.

[0111] Figure 10 The graphene heating chip 100 is shown as a temperature rise curve at 800°C. Figure 10It can be seen that the graphene heating chip 100 can be heated to 800°C within 26.31ms, indicating that the graphene heating chip 100 has a fast response speed. This can be attributed to the fact that the graphene film 16 is a single layer. The single-layer graphene significantly reduces the heat capacity of the graphene heating chip 100, and the graphene film 16 and SiN... X The membranes are in van der Waals contact, which significantly reduces the degradation of graphene film 16 and SiN. X Interfacial interactions between membranes.

[0112] Gold (Au) nanoparticles were deposited in the sample cell of the graphene heating chip 100, and the sample cell was imaged under TEM to observe the deformation (expansion) of the sample cell.

[0113] Figure 11 These are TEM focused images of Au particles at room temperature and at a concentric height without defocus, created by... Figure 11 A gold lattice can be observed. Figure 12 This is a TEM image of a gold particle heated to 650℃ with a z-height change of 50 nm. The z-height change represents the expansion of the sample cell. It can be seen that at 650℃, the z-height change is 50 nm, meaning the sample cell expands by 50 nm at 650℃.

[0114] In traditional MEMS heaters, the bicrystalline film window typically consists of a metal resistive layer and SiN. X A self-supporting thin film composed of a film. The metal resistive layer is deposited on SiN using a thin film deposition process. X On the film, the metal resistive layer and SiN X The interfacial adhesion between the films is very strong. Due to this strong interfacial adhesion, the metal resistive layer and SiN... X The film generates strong interfacial stress, leading to the formation of a barrier between the metal resistive layer and SiN. X The electron-transparent window formed by the film expands significantly. In the graphene heating chip 100, graphene is a two-dimensional van der Waals material with no dangling bonds on its surface. The graphene film 16 is bonded to SiN by weak van der Waals forces. X Membrane contact leads to the interaction between the graphene film 16 and SiN. X There is weak interfacial stress between the films. Therefore, compared with traditional MEMS heaters, the graphene heating chip 100 has a graphene film 16 / SiN X The expansion of the film was significantly suppressed. It can be seen that the expansion amplitude of the sample cell at 650℃ was only 50nm, meaning the successful suppression of expansion can be attributed to the introduction of the graphene resistive layer. The monolayer graphene greatly reduces the thermal capacity of the graphene heating chip 100, and the graphene and SiN... X The van der Waals force contact between the membranes significantly reduces their interfacial interaction.

[0115] The melting process of tin (Sn) nanoparticles was observed in situ using the graphene heating chip 100, as shown in the figure. Figures 13 to 16 As shown. Figure 13 Here are TEM images of Sn particles at room temperature, by Figure 13 Sn nanoparticles were observed, with a lattice space of 0.29 nm having a (200) crystal plane. Figure 14 for Figure 13 The corresponding fast Fourier transform images confirmed the crystalline structure of the Sn nanoparticles. Figure 15 These are TEM images of Sn nanoparticles at 240℃, created by... Figure 15 As can be seen, the TEM image at the same location shows that no lattice of Sn nanoparticles was observed, indicating that the Sn nanoparticles have melted into liquid. Figure 16 for Figure 15 The corresponding fast Fourier transform image confirms the phase transition where the pattern disappears. Figures 13 to 16 This indicates that the graphene heating chip 100 can effectively solve the thermodynamic processes in in-situ TEM observation.

[0116] The graphene heating chip 100 and its preparation method have the following advantages: First, the graphene heating chip 100 has a fast response speed, and can be heated to 800℃ within 26.31ms and to 1000℃ within 30ms; Second, the expansion or deformation of the sample cell in the graphene heating chip 100 is very small, and its expansion or deformation at 650℃ is only 50nm; Third, the graphene heating chip 100 can dynamically observe the sample during the TEM characterization process; Fourth, the preparation method of the graphene heating chip 100 is simple and can be used to prepare the graphene heating chip 100 on a large scale.

[0117] Please see Figure 17 The third embodiment of the present invention provides a method for calibrating the temperature of the graphene heating chip 100, which includes the following steps:

[0118] S1', a graphene heating chip 100 is provided, and the first electrode 141, the second electrode 142, the fifth electrode 145 and the sixth electrode 146 in the graphene heating chip 100 are defined as a resistance thermometer, and the resistance R0 of the resistance thermometer is measured at room temperature T0 (25°C).

[0119] S2', energize the graphene film 16 in the graphene heating chip 100 to heat the window (i.e., the insulating layer 12 in the graphene heating chip 100 that covers the through hole 106 of the substrate 10 and does not directly contact the first surface 102 of the substrate 10).

[0120] S3', the window exceeds a threshold temperature and emits visible light, thereby giving the window a red luminous area;

[0121] S4', Align the spectroradiometer with the red emitting region to obtain the spectral radiance and chromaticity of 380nm-780nm, and then calculate the temperature of the red emitting region according to Planck's blackbody radiation law;

[0122] S5', increase the power of the graphene film 16 to increase the intensity of the visible light and the temperature of the red emitting region, thereby obtaining multiple temperatures of the red emitting region at multiple power levels, which are defined as T1, T2, T3...Tn, n≧1;

[0123] S6', at the multiple temperatures, the resistance of the resistance thermometer is measured and defined as R1, R2, R3...Rn, n≧1;

[0124] S7', linearly fit the room temperature T0, multiple temperatures of the red luminescent area (T1, T2, T3...Tn, n≧1), the resistance R0, and multiple resistances of the resistance thermometer (R1, R2, R3...Rn, n≧1) to obtain the correspondence between resistance and temperature; and

[0125] S8': Based on the relationship between resistance and temperature in S7', the temperature of the window is obtained by measuring the resistance of the resistance thermometer.

[0126] In step S1', in a specific embodiment, the first electrode 141, the second electrode 142, the fifth electrode 145 and the sixth electrode 146 are all made of platinum, and the resistance R0 of the resistance thermometer at room temperature T0 (25°C) is measured by the four-probe method.

[0127] In step S3', in one specific embodiment, the material of the insulating layer 12 is SiN. x When the temperature of the window exceeds 600°C, it begins to emit visible light.

[0128] In step S4', Planck's blackbody radiation law states that at any temperature, the emissivity of electromagnetic radiation emitted from a blackbody is related to its frequency. The emissivity of a blackbody follows a regular pattern with wavelength, and is proportional to the fourth power of its absolute temperature T. At high temperatures, the heating window of the insulating layer 12 begins to emit light, and the intensity of the light gradually increases with increasing heating power. By measuring the spectral intensity of visible light and fitting it according to Planck's blackbody radiation law, the temperature of the window at high temperatures can be obtained. That is, the temperature of the suspended window (i.e., the suspended second part of the insulating layer 124) in the graphene heating chip 100 at high temperatures can be obtained according to Planck's blackbody radiation law, but the temperature at low temperatures cannot be obtained. Since the sample cell is located in the second part of the insulating layer 124, the temperature of the sample cell at high temperatures can be obtained according to Planck's blackbody radiation law, but the temperature at low temperatures cannot be obtained. In a specific embodiment, the material of the insulating layer 12 is SiN. x SiN x The window begins to emit light when the temperature is above 600°C.

[0129] In step S5', the power of the graphene film 16 is increased, the overall temperature of the window increases, the red light-emitting area becomes larger, the light intensity increases, and different temperatures will be obtained under different power levels.

[0130] In step S6', the method for measuring the resistance of the resistance thermometer is not limited. In one specific embodiment, the resistance of the resistance thermometer is measured using the four-probe method.

[0131] In step S7', linear fitting yields the relationship between resistance and temperature, as follows: Figure 18 As shown. Since resistance (the resistance of the resistance thermometer) and temperature (the temperature of the window) are linearly related, the temperature of the window can be obtained by measuring the resistance of the resistance thermometer. This temperature includes both high temperatures that allow the window to emit visible light and low temperatures that do not. Because the multiple grooves 126 on the window form a sample cell, the temperature of the sample cell is the temperature of the window. That is, the temperature of the sample cell can be obtained by measuring the resistance of the resistance thermometer, and this temperature includes both high temperatures that allow the window to emit visible light and low temperatures that do not.

[0132] In one specific embodiment, multiple temperatures of the red emitting region are obtained at multiple power levels, and the resistance of the resistance thermometer is measured at each of the multiple temperatures. The temperatures of the red emitting region and the resistance of the resistance thermometer at each temperature are shown in Table 1.

[0133] Table 1 shows the temperature of the red emitting area and the resistance of the resistance thermometer at that temperature.

[0134]

[0135]

[0136] By fitting the temperature of the red luminescent area and the resistance of the resistance thermometer at that temperature, a linear relationship between resistance and temperature was obtained, with a slope of 0.748 and an intercept of 686.91.

[0137] The calibration method for the temperature of the graphene heating chip 100 has the following advantages: First, after linear fitting, when the graphene heating chip 100 is heated, even if the window does not emit light, the temperature of the suspended window can be obtained by measuring the resistance of the first electrode 141 (platinum), the second electrode 142 (platinum), the fifth electrode 145 (platinum), and the sixth electrode 146 (platinum), without the need for a spectrophotometer; Second, it is compatible with a TEM sample stage to perform real-time temperature measurement of the graphene heating chip 100.

[0138] Furthermore, those skilled in the art may make other changes within the spirit of this invention. Of course, all such changes made in accordance with the spirit of this invention should be included within the scope of protection claimed by this invention.

Claims

1. A graphene heating chip comprising a substrate and a plurality of electrodes, characterized in that, The graphene heating chip further includes an insulating layer and a graphene film; The substrate has a first surface and a second surface opposite to each other, and the substrate is provided with a through hole that extends from the first surface to the second surface; The insulating layer is located on the first surface and is suspended at the through hole. The insulating layer covering the through hole and spaced apart from the first surface is defined as a window, and a plurality of grooves are provided on the window. The graphene film is located on the surface of the insulating layer away from the substrate and covers the window. The graphene film includes a first part graphene film and a second part graphene film, and the first part graphene film and the second part graphene film are spaced apart. The plurality of electrodes are located on the surface of the insulating layer away from the substrate, and the plurality of electrodes are named sequentially as first electrode, second electrode, third electrode, fourth electrode, fifth electrode, sixth electrode and seventh electrode; The third electrode is in direct contact with the first portion of the graphene film, the fourth electrode is in direct contact with the second portion of the graphene film, the first electrode is in direct contact with the second electrode, the fifth electrode and the sixth electrode are in direct contact, and the second electrode is in direct contact with the fifth electrode; both the first portion of the graphene film and the second portion of the graphene film are in direct contact with the seventh electrode.

2. The graphene heating chip as described in claim 1, characterized in that, The plurality of grooves are located between the first portion of the graphene film and the second portion of the graphene film.

3. The graphene heating chip as described in claim 1, characterized in that, The portions of the first electrode in direct contact with the second electrode, the portions of the fifth electrode in direct contact with the sixth electrode, and the portions of the second electrode in direct contact with the fifth electrode are all located in the middle of the first portion of the graphene film and the second portion of the graphene film, and are all electrically insulated from the graphene film.

4. The graphene heating chip as described in claim 1, characterized in that, The insulating layer is made of silicon nitride or silicon carbide.

5. The graphene heating chip as described in claim 1, characterized in that, The graphene film is a single-layer graphene.

6. A method for preparing a graphene heating chip, comprising the following steps: A substrate is provided, the substrate having opposing first and second surfaces; An insulating layer is disposed on the first surface; Multiple electrodes are disposed on the surface of the insulating layer away from the substrate, and these multiple electrodes are named sequentially as first electrode, second electrode, third electrode, fourth electrode, fifth electrode, sixth electrode and seventh electrode; A through hole is provided in the substrate, which extends from the first surface to the second surface, thereby suspending the insulating layer at the through hole. The insulating layer that covers the through hole and does not directly contact the first surface is defined as a window. A graphene film is disposed on the surface of the insulating layer away from the substrate, and the graphene film covers the window; Remove the graphene film except for the window to expose the plurality of electrodes, and cut the graphene film located at the window into a first part graphene film and a second part graphene film, which are spaced apart. The third electrode is in direct contact with the first portion of the graphene film, the fourth electrode is in direct contact with the second portion of the graphene film, the first electrode is in direct contact with the second electrode, the fifth electrode and the sixth electrode are in direct contact, and the second electrode is in direct contact with the fifth electrode. Both the first and second portions of the graphene film are in direct contact with the seventh electrode. as well as Multiple grooves are formed on the insulating layer between the first part of the graphene film and the second part of the graphene film.

7. The method for preparing the graphene heating chip as described in claim 6, characterized in that, The plurality of grooves are located between the first portion of the graphene film and the second portion of the graphene film.

8. The method for preparing the graphene heating chip as described in claim 6, characterized in that, The portions of the first electrode in direct contact with the second electrode, the portions of the fifth electrode in direct contact with the sixth electrode, and the portions of the second electrode in direct contact with the fifth electrode are all located in the middle of the first portion of the graphene film and the second portion of the graphene film, and are all electrically insulated from the graphene film.

9. The method for preparing the graphene heating chip as described in claim 6, characterized in that, The insulating layer is made of silicon nitride or silicon carbide.

10. The method for preparing the graphene heating chip as described in claim 6, characterized in that, The graphene film is a single-layer graphene.

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