A method for preparing a sub-10nm gap electrode pair

Abstract

This invention proposes a method for fabricating sub-10 nm gap electrode pairs. The method involves designing the tips of the triangular electrode pairs into overlapping, zero-spacing, or non-overlapping configurations based on the tip angles. Electron beam lithography is used to create the electrode pattern, and metal is deposited using an electron beam evaporation system. The electrode pairs, after metal deposition, are then heat-treated in a scanning electron microscope (SEM). The electron beam irradiation thermal effect adjusts the spacing between the electrode pair's corners, resulting in sub-10 nm gap electrode pairs. The method is simple and easy to operate, and the gap between the electrode pairs can be controllably adjusted while observing the electrode pair's morphology to achieve the desired gap. This method overcomes the current difficulties in fabricating sub-10 nm gap electrode pairs, which often suffer from tip adhesion and difficulty in precisely controlling the gap size.

Description

Technical Field

[0001] The present invention relates to the technical field of extreme-size micro-nano processing, and in particular to a method for manufacturing a sub-10nm gap electrode pair. Background Art

[0002] Nanogaps are important research tools in the field of molecular electronics. By integrating single or multiple molecules within a nanogap, the interactions between them can be exploited to explore the intrinsic properties of molecules. They can be used to form molecular-scale devices and equipment such as photodetectors and ultrafast nanotransistors, pushing the boundaries of performance. In addition, sub-10nm gap structures also play an important role in applications such as electronic biosensors, nanoantennas, surface-enhanced Raman spectroscopy, and plasmonic devices. Therefore, the stable and reliable preparation of sub-10nm gaps is crucial for the research of nanogap-based devices. Electron beam lithography with high resolution is usually the most common and direct technical means. However, due to the proximity effect during electron beam exposure and the thermal expansion and contraction effect of nanosized metal electrodes, it is difficult to stably obtain sub-10nm gaps. Problems such as electrode tips sticking to each other and difficulty in accurately controlling the gap size often occur, leading to failure of the microfabrication process.

[0003] CN101067719A discloses a method for constructing sub-10 nanometer gaps and arrays thereof. This method utilizes the proximity effect in electron beam lithography to design two patterns to be continuous (vertices connected but not overlapping). By controlling the electron beam etching energy and pattern transfer, the gap between the two patterns is controlled to the sub-10 nanometer level. Although this method is simple and easy to implement, it is not suitable for triangular electrodes of all angles in actual production due to the proximity effect during electron beam lithography. In particular, when the electrode tips are at large angles, the electrodes are easily stuck together after pattern transfer, preventing the formation of a gap.

[0004] CN104465327A discloses a nanometer pair electrode and its preparation method, which is designed to be a rectangular plus triangular shape, and the proximity effect during electron beam exposure is weakened to obtain a nanometer pair electrode with a spacing of 3-10nm. The short side of the rectangle coincides with one side of the triangle, and the triangles of the two long strip parts face each other to form a point contact. By adjusting the angle of the triangle vertex in the exposure layout, the spacing of the nanometer pair electrodes is corrected. The method is simple and suitable for large-scale production, but the patent also mentions that when the layout contact angle is small, even if the electrode spacing made by zero-gap layout exposure will exceed 10nm, and when the layout contact angle is too large, the proximity effect is more obvious, and it is difficult to form a gap of less than 10nm.

[0005] CN110993487A discloses a method for fabricating sub-10nm gap structures and its application. By designing the layout into overlapping patterns of top-to-top structures, the method overcomes the underexposure problem that occurs when the top-to-top structures have a vertex angle less than 40°, successfully fabricating sub-10nm gap structures. However, this method is not applicable to top-to-top structures with a vertex angle greater than 40°, and the document does not mention a corresponding solution.

[0006] CN112086345A discloses a method for preparing an electrode gap with a size of less than 10nm, its products and uses. By designing the mask pattern into an overlapping shape of a top structure and using underexposure to offset the influence of the proximity effect, the processing and preparation of an electrode gap with a size of less than 10nm can be achieved.

[0007] Most of the methods mentioned in the above patents require preparation through precise graphic design and proximity effect / underexposure of electron beam exposure, which has many limitations and uncertainties. Therefore, how to prepare sub-10nm gap electrode pairs more flexibly, conveniently and controllably has always been a technical challenge faced by people. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for manufacturing a sub-10 nm gap electrode pair, which can prepare the sub-10 nm gap electrode pair more flexibly and controllably.

[0009] The technical solution to achieve the purpose of the present invention is: a method for preparing a sub-10 nm gap electrode pair, comprising the following steps:

[0010] Step 1, designing a mask pattern according to the electrode tip angle;

[0011] Step 2: Spin-coating electron beam glue on the substrate, forming a mask pattern by electron beam lithography, and then depositing metal on the surface;

[0012] Step 3: Place the electrode pair after metal deposition on the scanning electron microscope (SEM) sample stage, adjust the sample stage so that the electrode pair pattern is in the center of the screen, focus the electron beam on the tip of the electrode pair, and adjust the spacing between the electrode pairs through the thermal effect of electron beam irradiation to form a sub-10nm gap electrode pair structure.

[0013] Furthermore, the mask pattern is designed according to the tip angle of the electrode pair, and the specific method is as follows:

[0014] When the tip angle of the electrode pair is greater than 60°, the mask pattern is designed to not overlap the electrode pairs;

[0015] When the electrode pair tip angle is equal to 60°, the mask pattern is designed as a zero-spacing electrode pair;

[0016] When the tip angle of the electrode pair is less than 60°, the mask pattern is designed to be an overlapping electrode pair.

[0017] Furthermore, the substrate is silicon dioxide, silicon or thermally oxidized silicon with niobium-based compounds grown thereon.

[0018] Furthermore, the electron beam glue is polymethyl methacrylate or polystyrene copolymer.

[0019] Furthermore, the electron beam glue is PMMA A2, A4 or ZEP520.

[0020] Furthermore, metal is deposited by electron beam evaporation.

[0021] Furthermore, the electrode pair is placed at the focal area of ​​the scanning electron beam.

[0022] Furthermore, the electron beam irradiation acceleration voltage is 1-10 kV; the detection mode is InLens secondary electron detection mode, and the magnification is 80,000-150,000.

[0023] Furthermore, the distance between the electrode tips is adjusted by adjusting the electron beam irradiation time, wherein the distance between the electrode tips decreases as the electron beam irradiation time increases, and the reduction rate is about 0.02-0.045 nm / s.

[0024] A sub-10nm gap electrode pair is provided. Based on the preparation method, a sub-10nm gap electrode pair structure is processed.

[0025] Compared with the existing technology, the present invention has the following significant advantages: 1) the prepared sub-10nm gap electrode has no restriction on the top angle, and can even be expanded to a square electrode, which completely overcomes the current preparation process problem of the tips of the electrode pairs sticking to each other; 2) the use of the SEM electron beam can observe the size of the electrode gap while controlling the spacing between the electrode pairs by the length of the electron beam irradiation time to keep it within the desired range, which completely overcomes the current problem of the difficulty in accurately controlling the size of the gap between the tips of the electrode pairs, making the preparation of sub-10nm gaps more flexible and convenient; 3) the process is simple, the yield is high, and large-scale preparation is possible. In particular, when the equipment is unstable and the electron beam exposure result is different from the usual, the spacing can be directly adjusted by the SEM electron beam without the need for re-experimentation, which greatly saves manpower and material costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the electrode pair design structure.

[0027] Figure 2 This is the SEM image of the electrode pair prepared in Example 1.

[0028] Figure 3This is the SEM image of the electrode pair prepared in Example 2.

[0029] Figure 4 This is an SEM image of the electrode pair prepared in Example 2 after SEM electron beam irradiation.

[0030] Figure 5 This is the SEM image of the electrode pair prepared in Example 3.

[0031] Figure 6 This is an SEM image of the electrode pair prepared in Example 3 after SEM electron beam irradiation.

[0032] Figure 7 This is the SEM image of the electrode pair prepared in Example 4.

[0033] Figure 8 This is an SEM image of the electrode pair prepared in Example 4 after SEM electron beam irradiation.

[0034] Figure 9 This is the SEM image of the electrode pair prepared in Example 5.

[0035] Figure 10 This is an SEM image of the electrode pair prepared in Example 5 after SEM electron beam irradiation. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0037] A method for preparing a sub-10 nm gap electrode pair comprises the following steps:

[0038] Step 1, designing different electrode pair spacings as mask patterns according to the electrode pair tip angles;

[0039] like Figure 1 As shown in FIG, the designed electrode pair spacing can be overlapping / zero spacing / non-overlapping. Due to the proximity effect and underexposure effect of electron beam lithography, the spacing size decreases as the electrode pair tip angle decreases. When the electrode pair tip angle is less than 60°, the electron beam lithography underexposure effect is more obvious, and the design is an overlapping structure, such as Figure 1 (a), where L1 is the length of the overlapping angle (less than zero); when the electrode tip angle is equal to 60°, the design is a zero-spacing structure, as shown in Figure 1 (b) As shown; when the electrode tip angle is greater than 60°, the proximity effect of electron beam lithography is more obvious, and the design is a non-overlapping structure, such as Figure 1 (c), where L2 is the distance between the opposite corners (greater than zero).

[0040] Step 2, after spin coating electron beam glue on the substrate, use electron beam lithography to form electrode pair patterns, and then deposit metal on the surface;

[0041] The substrate is made of silicon dioxide, silicon or thermally oxidized silicon with niobium-based compounds; the electron beam glue is polymethyl methacrylate or polystyrene copolymer, preferably PMMA A2, A4 or ZEP520; the method used for depositing metal is electron beam evaporation.

[0042] Step 3: Glue the electrode pair after metal deposition onto the scanning electron microscope (SEM) sample stage with conductive glue, adjust the sample stage height and turn on the electron beam acceleration voltage, switch the detection mode, and move the sample stage left and right using the joystick on the sample stage controller so that the electrode pair pattern is in the center of the screen. Adjust the magnification so that the electron beam is focused on the tip of the electrode pair. The spacing between the electrode pairs can be controlled and adjusted through the thermal effect of electron beam irradiation to form a sub-10nm gap electrode pair structure.

[0043] The sample was placed in the focal zone of a scanning electron beam; the electron beam irradiation acceleration voltage was 1-10 kV; the detection mode was InLens secondary electron detection mode, and the magnification was 80,000-150,000. Due to the thermal effect of electron beam irradiation, the distance between the electrode tips decreased with increasing electron beam irradiation time, at a rate of approximately 0.02-0.045 nm / s. Accordingly, the distance between the electrode tips was adjusted by adjusting the electron beam irradiation time.

[0044] In order to verify the effectiveness of the solution of the present invention, the following experiment was conducted.

[0045] Example 1

[0046] A sub-10nm gap electrode pair structure, the preparation method is as follows:

[0047] A thermally oxidized silicon wafer with a niobium-based compound (Nb5N6 film) grown on it was ultrasonically cleaned in acetone, alcohol, and water for 5 minutes each. The surface moisture was blown dry with a nitrogen gun and then a single layer of PMMA A4 adhesive was spin-coated at a rate of 4000 rad / min for 60 seconds. The wafer was then baked at 180° on a baking table for 4 minutes.

[0048] After spin-coating photoresist, the sample was aligned and placed in an electron beam exposure system. Using L-Edit, an electrode pair with a 60° tip angle and zero apex spacing was designed. This served as the mask pattern for exposure, with an electron beam current of 1 nA and an exposure dose of 750 μc / cm². The exposed sample was developed in a developer (MIBK:IPA = 1:3) for 90 seconds, then fixed in a fixer (isopropyl alcohol) for 60 seconds. The sample was rinsed with deionized water for 30 seconds and dried with a nitrogen gun. The developed sample was then placed in an electron beam evaporation (EBE) system and sequentially deposited with a 100 nm nickel adhesion layer and a 100 nm gold layer. The sample was then immersed in an N-methyl solution and heated in an 80°C water bath for 1 hour. The surface electron beam adhesive was removed by ultrasonic stripping. The sample was then ultrasonically cleaned with acetone, alcohol, and water, followed by drying with a nitrogen gun to obtain the electrode pair pattern.

[0049] The dried sample was placed under a scanning electron microscope to observe the prepared nanogaps. Figure 2 As shown, it is 9.83nm, and a sub-10nm gap electrode pair is obtained directly using an electron beam exposure system.

[0050] Example 2

[0051] A sub-10nm gap electrode pair structure, the preparation method is as follows:

[0052] A thermally oxidized silicon wafer with a niobium-based compound (Nb5N6 film) grown on it was ultrasonically cleaned in acetone, alcohol, and water for 5 minutes each. The surface moisture was blown dry with a nitrogen gun and then a single layer of PMMA A4 adhesive was spin-coated at a rate of 4000 rad / min for 60 seconds. The wafer was then baked at 180° on a baking table for 4 minutes.

[0053] After spin-coating the photoresist, the sample was leveled and placed in the electron beam exposure system. Using L-Edit, the electrode tip angle was designed to be 30°, and the vertex angle overlap length L1 was 6nm. This was used as the mask pattern to expose the sample, with an electron beam current of 1nA and an exposure dose of 750μc / cm 2 The exposed sample was developed in a developer (MIBK:IPA = 1:3) for 90 seconds, then fixed in a fixer (isopropyl alcohol) for 60 seconds, rinsed with deionized water for 30 seconds, and blown dry with a nitrogen gun. The developed sample was placed in an EBE (electron beam evaporation) system and sequentially deposited with a 30nm platinum adhesion layer and a 100nm gold layer. The sample was then immersed in an N-methyl solution and heated in an 80°C water bath for 1 hour. The surface electron beam glue was removed by ultrasonic stripping, and then ultrasonically cleaned with acetone, alcohol, and water, followed by drying with a nitrogen gun to obtain the electrode pair pattern.

[0054] The dried sample was glued to the sample stage of the scanning electron microscope with conductive glue and placed into the sample chamber. After closing the chamber door, the pump was pressed to evacuate the sample for about 5 minutes. When the vacuum degree was less than 2×10 -5 mbar, then adjust the sample stage height to 45mm. Click EHT ON to turn on the electron beam acceleration voltage. The electron beam acceleration voltage defaults to the voltage when it was last used. Switch the detection mode to InLens secondary electron detection mode. First reduce the magnification to maximize the field of view, and then use the sample stage control joystick to move the sample stage so that the sample appears in the field of view. After that, continue to increase the magnification and focus until the electrode pair appears clearly in the center of the screen. If the image is blurry, you can adjust the astigmatism without deforming the image. Use the Stigmator option on the screen to adjust the degree of astigmatism in the X direction left and right until the image is clear, and then adjust the astigmatism in the Y direction in the same way. After the astigmatism is completely eliminated, fine-tune the focus to achieve the best image clarity. Then adjust the electron beam acceleration voltage to 3kV, the magnification to 130kx, and the working distance to 3.8-4mm. After about 16 minutes, the distance between the electrode tips is reduced from the initial 24.75nm (such as Figure 3 as shown) is reduced to 4.03nm (as shown) Figure 4 The average shrinkage rate is about 0.0216nm / s.

[0055] Example 3

[0056] A sub-10nm gap electrode pair structure, the preparation method is as follows:

[0057] A thermally oxidized silicon wafer with niobium-based compound (Nb5N6 film) grown on it was placed in acetone, alcohol, and water and ultrasonically cleaned for 5 minutes at 100W each. The surface moisture was blown dry with a nitrogen gun and a single layer of ZEP520 adhesive was spin-coated at a uniform coating condition of 5000 rad / min for 60 seconds. The wafer was then placed on a baking table at 180° and baked for 3 minutes.

[0058] After spin-coating the photoresist, the sample was leveled and placed in the electron beam exposure system. Using L-Edit, the electrode tip angle was designed to be 90° and the top angle spacing L2 was 20nm. This was used as the mask pattern to expose the sample, with an electron beam current of 0.2nA and an exposure dose of 200μc / cm 2 . The exposed sample was placed in a developer (n-amyl acetate) for 90 seconds, then placed in a fixer (isopropyl alcohol) for 15 seconds and blown dry with a nitrogen gun. The developed sample was placed in an EBE (electron beam evaporation) system and sequentially evaporated with a 10nm nickel adhesion layer and a 100nm gold layer. It was then immersed in an N methyl solution water bath for 1 hour, and the surface electron beam glue was removed by ultrasonic stripping. It was then ultrasonically cleaned with acetone, alcohol, and water in sequence, and then blown dry with a nitrogen gun to obtain the electrode pair pattern.

[0059] The dried sample was glued to the sample stage of the scanning electron microscope with conductive glue and placed into the sample chamber. After closing the chamber door, the pump was pressed to evacuate the sample for about 5 minutes. When the vacuum degree was less than 2×10 -5 mbar, then adjust the sample stage height to 45mm. Click EHT ON to turn on the electron beam acceleration voltage. The electron beam acceleration voltage defaults to the voltage when it was last used. Switch the detection mode to InLens secondary electron detection mode. First reduce the magnification to maximize the field of view, and then use the sample stage control joystick to move the sample stage so that the sample appears in the field of view. After that, continue to increase the magnification and focus until the electrode pair appears clearly in the center of the screen. If the image is blurry, you can adjust the astigmatism on the basis of not deforming the image. Use the Stigmator option on the screen to adjust the degree of astigmatism in the X direction left and right until the image is clear, and then adjust the astigmatism in the Y direction in the same way. After the astigmatism is completely eliminated, fine-tune the focus to achieve the best image clarity. Then adjust the electron beam acceleration voltage to 3kV, the magnification to 80kx, and the working distance to 3.8-4mm. After about 6 minutes, the distance between the electrode tips is reduced from the initial 20.2nm (such as Figure 5 as shown) is reduced to 9.43nm (as shown) Figure 6 The average shrinkage rate is about 0.03 nm / s.

[0060] Example 4

[0061] A sub-10nm gap electrode pair structure, the preparation method is as follows:

[0062] The silicon wafer with the oxide layer was placed in acetone, alcohol, and water for 5 minutes each at 100W ultrasonic cleaning in turn. The surface moisture was blown dry with a nitrogen gun and a layer of PMMA A4 single layer glue was spin-coated at 4000 rad / min for 60 seconds. The wafer was then placed on a baking table at 180° and baked for 4 minutes.

[0063] After spin-coating the photoresist, the sample was leveled and placed in the electron beam exposure system. Using L-Edit, the electrode tip angle was designed to be 40°, and the vertex angle overlap length L1 was 30nm. This was used as the mask pattern to expose the sample, with an electron beam current of 1nA and an exposure dose of 750μc / cm 2The exposed sample was placed in a developer (MIBK:IPA = 1:3) for 90 seconds, then fixed in a fixer (isopropyl alcohol) for 60 seconds, rinsed with deionized water for 30 seconds, and blown dry with a nitrogen gun. The developed sample was placed in an EBE (electron beam evaporation) system and sequentially deposited with a 10nm titanium adhesion layer and a 50nm gold layer. The sample was then immersed in an N-methyl solution and heated in an 80°C water bath for 1 hour. The surface electron beam glue was removed by ultrasonic stripping. The sample was then ultrasonically cleaned with acetone, alcohol, and water, followed by drying with a nitrogen gun to obtain the electrode pair pattern.

[0064] The dried sample was glued to the sample stage of the scanning electron microscope with conductive glue and placed into the sample chamber. After closing the chamber door, the pump was pressed to evacuate the sample for about 5 minutes. When the vacuum degree was less than 2×10 -5 mbar, then adjust the sample stage height to 45mm. Click EHT ON to turn on the electron beam acceleration voltage. The electron beam acceleration voltage defaults to the voltage when it was last used. Switch the detection mode to InLens secondary electron detection mode. First reduce the magnification to maximize the field of view, and then use the sample stage control joystick to move the sample stage so that the sample appears in the field of view. After that, continue to increase the magnification and focus until the electrode pair appears clearly in the center of the screen. If the image is blurry, you can adjust the astigmatism on the basis of not deforming the image. Use the Stigmator option on the screen to adjust the degree of astigmatism in the X direction left and right until the image is clear, and then adjust the astigmatism in the Y direction in the same way. After the astigmatism is completely eliminated, fine-tune the focus to achieve the best image clarity. Then adjust the electron beam acceleration voltage to 3kV, the magnification to 90kx, and the working distance to 3.8-4mm. After about 8 minutes, the distance between the electrode tips is reduced from the initial 25.01nm (such as Figure 7 as shown) is reduced to 4.82nm (as shown) Figure 8 The average shrinkage rate is about 0.031 nm / s.

[0065] Example 5

[0066] A sub-10nm gap electrode pair structure, the preparation method is as follows:

[0067] A thermally oxidized silicon wafer with a niobium-based compound (Nb5N6 film) grown on it was ultrasonically cleaned in acetone, alcohol, and water for 5 minutes each. The surface moisture was blown dry with a nitrogen gun and then a single layer of PMMA A4 adhesive was spin-coated at a rate of 4000 rad / min for 60 seconds. The wafer was then baked at 180° on a baking table for 4 minutes.

[0068] After spin-coating the photoresist, the sample was leveled and placed in the electron beam exposure system. Using L-Edit, the electrode tip angle was designed to be 40°, and the vertex angle overlap length L1 was 6nm. This was used as the mask pattern to expose the sample, with an electron beam current of 1nA and an exposure dose of 750μc / cm 2 The exposed sample was developed in a developer (MIBK:IPA = 1:3) for 90 seconds, then fixed in a fixer (isopropyl alcohol) for 60 seconds, rinsed with deionized water for 30 seconds, and blown dry with a nitrogen gun. The developed sample was placed in an EBE (electron beam evaporation) system and sequentially deposited with a 10nm titanium adhesion layer and a 100nm gold layer. The sample was then immersed in an N-methyl solution and heated in an 80°C water bath for 1 hour. The surface electron beam glue was removed by ultrasonic stripping, and then ultrasonically cleaned with acetone, alcohol, and water, followed by drying with a nitrogen gun to obtain the electrode pair pattern.

[0069] The dried sample was glued to the sample stage of the scanning electron microscope with conductive glue and placed into the sample chamber. After closing the chamber door, the pump was pressed to evacuate the sample for about 5 minutes. When the vacuum degree was less than 2×10 -5 mbar, then adjust the sample stage height to 45mm. Click EHT ON to turn on the electron beam acceleration voltage. The electron beam acceleration voltage defaults to the voltage when it was last used. Switch the detection mode to InLens secondary electron detection mode. First reduce the magnification to maximize the field of view, and then use the sample stage control joystick to move the sample stage so that the sample appears in the field of view. After that, continue to increase the magnification and focus until the electrode pair appears clearly in the center of the screen. If the image is blurry, you can adjust the astigmatism without deforming the image. Use the Stigmator option on the screen to adjust the degree of astigmatism in the X direction left and right until the image is clear, and then adjust the astigmatism in the Y direction in the same way. After the astigmatism is completely eliminated, fine-tune the focus to achieve the best image clarity. Then adjust the electron beam acceleration voltage to 5kV, the magnification to 125kx, and the working distance to 3.8-4mm. After about 6 minutes, the distance between the electrode tips is reduced from the initial 21.01nm (such as Figure 9 as shown) is reduced to 5.37nm (as shown) Figure 10 The average shrinkage rate is about 0.0434 nm / s.

[0070] In summary, the present invention directly utilizes the thermal effect of electron beam irradiation in a SEM to controllably adjust the spacing between the electrode pair tips. This method imposes no stringent restrictions on the angle of the electrode pair tips, the choice of substrate, or the deposited metal, thus enabling the more flexible and convenient preparation of sub-10nm gap electrode pairs. Furthermore, the method is simple and easy to operate, and the electrode pair gap can be controllably adjusted while observing the electrode pair morphology to achieve the desired electrode pair spacing. This method completely overcomes the current preparation process difficulties of sub-10nm gap electrode pairs, which suffer from mutual adhesion of the tips and the difficulty in precisely controlling the gap size.

[0071] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A method for preparing a sub-10 nm gap electrode pair, characterized in that: The following steps are involved: Step 1, designing a mask pattern according to the electrode tip angle; Step 2: Spin-coating electron beam glue on the substrate, forming a mask pattern by electron beam lithography, and then depositing metal on the surface; Step 3: Place the electrode pair after metal deposition on the sample stage of a scanning electron microscope, adjust the sample stage so that the electrode pair pattern is in the center of the screen, focus the electron beam on the tip of the electrode pair, and adjust the spacing between the electrode pairs through the thermal effect of electron beam irradiation. That is, increase the electron beam irradiation time to reduce the spacing between the electrode pair tips, forming a sub-10 nm gap electrode pair structure.

2. The method for preparing a sub-10 nm gap electrode pair according to claim 1, wherein: The mask pattern is designed according to the electrode tip angle, and the specific method is as follows: When the tip angle of the electrode pair is greater than 60°, the mask pattern is designed to not overlap the electrode pairs; When the electrode pair tip angle is equal to 60°, the mask pattern is designed as a zero-spacing electrode pair; When the tip angle of the electrode pair is less than 60°, the mask pattern is designed to be an overlapping electrode pair.

3. The method for preparing a sub-10 nm gap electrode pair according to claim 1, wherein: The substrate is silicon dioxide, silicon or thermally oxidized silicon with niobium-based compounds.

4. The method for preparing a sub-10 nm gap electrode pair according to claim 1, wherein: The electron beam glue is polymethyl methacrylate or polystyrene copolymer.

5. The method for preparing a sub-10 nm gap electrode pair according to claim 1 or 4, characterized in that: The electron beam glue is PMMA A2, A4 or ZEP520.

6. The method for preparing a sub-10 nm gap electrode pair according to claim 1, wherein: The metals were deposited by electron beam evaporation.

7. The method for preparing a sub-10 nm gap electrode pair according to claim 1, wherein: The electrode pair is placed at the focal region of the scanning electron beam.

8. The method for preparing a sub-10 nm gap electrode pair according to claim 1, wherein: The electron beam irradiation acceleration voltage was 1-10 kV; the detection mode was InLens secondary electron detection mode, and the magnification was 80,000-150,000.

9. The method for preparing a sub-10 nm gap electrode pair according to claim 1, wherein: The distance between the electrode tips decreases with the increase of electron beam irradiation time, and the decreasing rate is 0.02-0.045 nm / s.

10. A sub-10 nm gap electrode pair, characterized in that: Based on the preparation method according to any one of claims 1 to 9, a sub-10 nm gap electrode pair structure is processed.

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