CN112198194A - Method for preparing near-zero thickness nanopore by double-sided helium ion beam etching, product and application thereof - Google Patents
Method for preparing near-zero thickness nanopore by double-sided helium ion beam etching, product and application thereof Download PDFInfo
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- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B82B—NANOSTRUCTURES FORMED BY MANIPULATION OF INDIVIDUAL ATOMS, MOLECULES, OR LIMITED COLLECTIONS OF ATOMS OR MOLECULES AS DISCRETE UNITS; MANUFACTURE OR TREATMENT THEREOF
- B82B3/00—Manufacture or treatment of nanostructures by manipulation of individual atoms or molecules, or limited collections of atoms or molecules as discrete units
- B82B3/0004—Apparatus specially adapted for the manufacture or treatment of nanostructural devices or systems or methods for manufacturing the same
Abstract
The invention relates to a method for preparing a nanopore with near zero thickness by double-sided helium ion beam etching, a product and application thereof, belonging to the technical field of single-molecule nanopore detection. The invention discloses a method for preparing a nearly zero-thickness nanopore by double-sided helium ion beam etching, which is characterized in that a highly controllable zero-thickness nanopore structure is prepared by a helium ion beam processing method with extremely high processing precision and controllability, so that the material, the pore size pattern and the pore size number of the nanopore structure can be specially designed according to the properties of molecules to be detected, and the detection DNA sequence, the RNA sequence, the modification of the DNA sequence, the modification of the RNA sequence or the spatial resolution, the time resolution and the capture rate of protein molecules of the nanopore can be improved.
Description
Technical Field
The invention belongs to the technical field of single-molecule nanopore detection, and particularly relates to a method for preparing a near-zero-thickness nanopore by double-sided helium ion beam etching, and a product and application thereof.
Background
The nano-pore single molecule detection technology is a high-precision biological detection technology based on the Coulter counter principle and an ion channel model. In 1953, Coulter proposed to reflect basic physical properties of relevant particles, such as size, shape, charge amount, etc., in an electrolyte solution by monitoring channel resistance fluctuation caused when the particles pass through micro-sized pores. This concept of using resistive pulse sensing has been widely used in the fields of life sciences and biochemical research. The sensing principle of the nanopore is that when a molecule to be detected with the size similar to the diameter of the pore passes through the nanopore, the ionic current changes, and the instantaneous change can be used for reflecting the physicochemical property of the molecule to be detected.
The existing nano-pores can be divided into biological nano-pores and solid nano-pores according to materials, and the existing solid nano-pores have great application prospect due to the defects of poor inherent environmental adaptability, fixed shape and size of the pores, difficulty in industrial mass production and the like of the biological nano-pores. However, due to the inherent characteristics of the material, the film thickness of the solid nanopore is difficult to reach the size matched with the length of a single base of DNA during detection, and the film thickness of the two-dimensional material can be reached theoretically at present, but due to the limitation of the access resistance, the sensing length of the solid nanopore cannot reach the degree matched with the film thickness precision in practical application, and the theoretically-reached spatial resolution cannot be realized successfully in application at present, so that the accurate detection of DNA, RNA sequences, covalently modified DNA sequences, covalently modified RNA sequences or protein molecules is difficult to realize. Meanwhile, for the detection of small biological molecules, the nanopore detection principle requires that the size of a molecule to be detected is approximate to that of a pore diameter, and the characteristic dimension of a pore forming structure is required to be matched with the size of the biological molecule so as to obtain higher detection sensitivity. At present, the technology which can achieve sub-10 nm processing precision in practical application in the traditional micro-nano processing field is very few, and helium ion beam etching can achieve the aim. In addition, in the process of biomolecule sensing, DNA and RNA molecules are translocated too fast, and the time resolution of nano-pores is insufficient, which is also a great defect. Some current methods for improving the time resolution generally depend on modification or control of experimental conditions, and are not suitable for batch production and application; in addition, some existing nanopore preparation techniques, such as dielectric breakdown, cannot prepare a plurality of nanopore structures with determined positions on a thin film; and the low capture rate of the nanopore is also a great problem. Since the detection of many small biological molecules requires very small nanopore pore sizes, it is only possible to do so using elaborate processing means.
Therefore, it is necessary to realize the personalized selection of materials, pore sizes and the number of pore diameters in the preparation process, and to realize the preparation of the nanopore with the thickness and the diameter both matched with the size of the small biological molecules so as to be convenient for adapting to the specific properties of various small biological molecules to be detected.
Disclosure of Invention
In view of the above, an object of the present invention is to provide a method for preparing a nanopore with a near-zero thickness by double-sided helium ion beam etching; the second objective of the present invention is to provide a method for preparing a nanopore with a near-zero thickness by double-sided helium ion beam etching; the invention also aims to provide a near-zero thickness nanometer hole single molecule detection device; the fourth purpose of the present invention is to provide an application of a nanopore monomolecular detection device with a near-zero thickness in the aspect of monomolecular detection analysis.
In order to achieve the purpose, the invention provides the following technical scheme:
1. a method of double-sided helium ion beam etching to produce near-zero thickness nanopores, the method comprising the steps of:
(1) preparing a silicon-based film substrate: growing a compound material on a silicon substrate with the thickness of 10-20 mu m by a chemical vapor deposition method to form a silicon-based film substrate, wherein the compound material comprises any one of a double-layer material consisting of silicon dioxide with the thickness of 50-200 nm and a silicon nitride film with the thickness of 10-30 nm, a single-layer material consisting of a silicon nitride film with the thickness of 20-30 nm or a double-layer material consisting of a silicon nitride film with the thickness of 10-30 nm and an aluminum oxide film with the thickness of 20-100 nm,
the silicon nitride film in the double-layer material consisting of the silicon nitride film with the thickness of 10-30 nm and the aluminum oxide film with the thickness of 20-100 nm is positioned between the silicon substrate and the aluminum oxide film;
(2) preparing a film window: etching the silicon substrate on the silicon-based film substrate in the step (1) by chemical wet etching to enable the silicon substrate to be etched to form a film window with the side length of 10-30 microns, and obtaining the silicon-based film substrate with the film window;
(3) preparing a near-zero thickness nanopore: processing the front surface of the silicon-based film substrate with the film window in the step (2) through helium ion beam etching to form a nano line array with the depth of 10-30 nm, processing the back surface of the silicon-based film substrate with the film window in the step (2) through helium ion beam etching to form a nano line with the depth of 10-220 nm, wherein the nano line array processed on the front surface and the nano line formed by processing the back surface intersect at an included angle of 10-90 degrees to form a nano hole.
Preferably, in order to increase the capture rate of the molecules to be detected, the method further includes etching an impermeable funnel-shaped small hole at each end of the nanowire array formed on the front surface.
Preferably, when the compound material is a double-layer material composed of silicon dioxide and a silicon nitride film or a single-layer material formed by a silicon nitride film, one surface where the film window is located is a back surface, and the other surface is a front surface.
Preferably, when the compound material is a double-layer material consisting of a silicon nitride film and an aluminum oxide film, one surface where the film window is located is a front surface, and the other surface is a back surface.
Preferably, the nanowire strip in the nanowire strip array formed by front processing has the length of 50-3000 nm, the width of 1-50 nm and the period of 100-1000 nm.
Preferably, the helium ion beam etching parameters in the front processing are set as follows: 10 mu m of diaphragm, less than or equal to 1pA of beam current and 100-500 nc/mu m of dosage2。
Preferably, the nanowire strips formed by back processing have a length of 50-7000 nm and a width of 1-50 nm.
Preferably, the parameters of the helium ion beam etching in the back processing are as follows: 10 mu m of diaphragm, less than or equal to 1pA of beam current and 100-2000 nc/mu m of dosage2。
Preferably, the sum of the depth of the nano-lines in the nano-line array and the depth of the nano-lines is equal to the thickness of the compound material.
2. The nanopore with the near-zero thickness is prepared according to the method.
3. A near-zero thickness nanopore monomolecular detection device comprises the near-zero thickness nanopore.
Preferably, the device further comprises a detection electrode and a detection cell.
4. The near-zero thickness nanometer hole single molecule detection device is applied to the aspect of single molecule detection and analysis.
Preferably, the single molecule is any one of a DNA sequence, a modification of a DNA sequence, an RNA sequence, a modification of an RNA sequence, or a protein molecule.
The invention has the beneficial effects that: the invention discloses a method for preparing a nearly zero-thickness nanopore by double-sided helium ion beam etching, which is characterized in that a highly controllable zero-thickness nanopore structure is prepared by a helium ion beam processing method with extremely high processing precision and controllability, so that the material, the pore size pattern and the pore size number of the nanopore structure can be specially designed according to the properties of molecules to be detected, and the modification of a DNA (deoxyribonucleic acid) sequence, an RNA (ribonucleic acid) sequence or a DNA sequence, the modification of the RNA sequence or the spatial resolution, the time resolution and the capture rate of protein in nanopore detection can be improved. The preparation method of the invention has the main advantages that: (1) the processing method of helium ion beam etching is adopted, the processing precision of sub-10 nm can be achieved when the fine structure is processed by the helium ion beam etching, the processing precision of the hole is very important for the identification of biological micromolecules, the depth-to-width ratio of the helium ion beam etching is very good, and the helium ion beam etching can form a very regular columnar channel shape unlike the funnel-shaped nanometer hole formed by a TEM drilling technology; (2) the method for processing the double surfaces is provided, the nano line array is processed and formed on the front surface, the nano line is processed and formed on the back surface, and the nano hole can be formed only by the nano line processed on the back surface within the range of the nano array processed on the front surface, so that the method is very convenient, and the problem that the material is easily damaged by punching a long line structure or directly performing large-area thinning on a regional material due to the small size and the fragile texture of a silicon nitride film is solved; (3) meanwhile, the length of the nanowire formed by processing the back can be adjusted according to the requirements of single holes, double holes or multiple holes, so that the nanowire array can be used for preparing nanopore biosensing detection with different purposes (for example, the formation of a single hole can carry out the traditional nanopore biosensing detection, and the physicochemical property of molecules to be detected is displayed through current change; (4) the specific shape of the formed aperture can be controlled by adjusting the angle between the nanowire array formed by processing the front surface and the nanowire array formed by processing the back surface; (5) meanwhile, helium ion beams are used for forming an impermeable funnel-shaped small hole on each of two sides of the nano-lines of the nano-line array on the front surface, and molecules to be detected can be attracted and led into the channel by utilizing the funnel-shaped shape so as to enter the nano-holes, so that the capture rate is further improved; (6) by controlling the depth in the processing process, the depth of the nanowire array formed on the front surface is smaller than that of the nanowire array formed on the back surface, so that the damage to the material is reduced, and the structure is more stable.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.
Drawings
For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic diagram of a 3D effect of a device containing a nanopore of near zero thickness, where a is a top view, b is a bottom view, and c is a line frame view in perspective;
FIG. 2 is a schematic cross-sectional 3D effect diagram, wherein a is a 3D cross-sectional view and b is a perspective cross-sectional view of a 3D line frame;
FIG. 3 is a flow chart of the preparation of a near-zero thickness nanopore of the present invention;
FIG. 4 is a near zero thickness nanopore of a single pore structure prepared by the method of the present invention in example 1, wherein a, b, and c are top, bottom, and front views, respectively;
fig. 5 is a near-zero thickness nanopore of a double-pore structure prepared by the method of the present invention in example 2, wherein a, b, and c are a top view, a bottom view, and a front view, respectively;
FIG. 6 is a near zero thickness nanopore of a porous structure prepared by the method of the invention in example 3, wherein a, b, and c are top, bottom, and front views, respectively;
FIG. 7 is an image of FIB scan after the nanowire array is processed on the front surface by the method of the present invention in example 1;
FIG. 8 is a representation of AFM after fabrication of a porous nanopore device by the method of the present invention in example 3;
fig. 9 is a recorded result (IV _02_1M KCL pH8) and an IV-fit plot (fixed Data) of the near-zero nanopore formed detection device prepared by the method of the present invention in example 1 tested under conditions of 300mV voltage, 1M KCL, pH 8.
Fig. 10 is a current trace diagram of the detection result of detecting the biomolecular plasmid PUC18 under the conditions of 300mV voltage, 1M KCL, pH8 of the near-zero nanopore-formed detection device prepared by the method of the present invention in example 1.
Detailed Description
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. It should be noted that, in the following embodiments, features in the embodiments may be combined with each other without conflict.
Example 1
The preparation method comprises the following steps of:
1. and selecting a silicon substrate with the thickness of 10-20 mu m, and growing a silicon nitride material with the thickness of 30nm on the silicon substrate by adopting a chemical vapor deposition method to obtain the silicon-based film substrate.
2. And corroding the silicon substrate surface of the silicon-based film substrate by using a chemical wet method to form a film window with the side length of 20 mu m, namely obtaining the silicon-based film substrate with the film window.
3. Etching one surface (front surface) of silicon nitride material with helium ion beam (etching parameters are set as 10 μm of diaphragm, less than or equal to 1pA of beam current, and dosage of 100-300 nc/μm2) And processing to form a row of vertical nanowire array with the length of 200nm, the width of 4nm, the depth of 10nm and the period of 500 nm.
4. On one side (back side) with a film window, in the area corresponding to the nanowire array formed by processing the front side, in the direction orthogonal to the nanowire array processed on the front side, helium ion beam etching is also adopted (etching parameters are set as 10 micrometers of diaphragm, the beam current is less than or equal to 1pA, and the dosage is 100-1000 nc/micrometer2) Processing to form a transverse nanowire with the length of 200nm, the width of 4nm and the depth of 20 nm.
5. Vertical nanowires forming a nanowire strip array are found on the front surface of the material, and two ends of each nanowire strip are respectively etched with an impermeable funnel-shaped small hole, wherein the structure of the vertical nanowires is shown in fig. 4, and a, b and c are respectively a top view, a bottom view and a front view.
6. The prepared near-zero thickness nanopore is used for biomolecule detection, and the detection process is as follows:
the prepared near-zero-thickness nanopore is assembled with a detection electrode, a detection cell and the like to form a near-zero-thickness nanopore monomolecular detection device, the detection device is placed in an electrolyte (KCL, the pH value is 8, and the bias voltage is 300mV), two chambers are separated, and an IV curve graph (shown in figure 9) at the moment is recorded under the condition that the experimental conditions (the pH value, the bias voltage, the temperature and the electrolyte concentration) are adjusted to the optimal conditions (1M KCL and the pH value is 8) of the molecules of the substance to be detected. Since the nanopore pore size is about 2.5nm at this time. When the plasmid molecule (PUC18) passes through the hole, the change of the corresponding current before and after is recorded (as shown in figure 10), and then the biological small molecule can be detected by utilizing the information of the current change. The nanopore in the detection device adopted in the detection process is physically near zero in thickness, and the spatial resolution of the nanopore depends on the film thickness to a great extent, so that the formed nanopore has extremely high spatial resolution which is a precondition for realizing the detection of the small biological molecules.
Example 2
The preparation process of the near-zero thickness nanopore with the double-pore structure is as follows:
1. selecting a silicon substrate with the thickness of 10-20 microns, firstly growing a silicon dioxide material with the thickness of 200nm on the silicon substrate by adopting a chemical vapor deposition method, and then growing a silicon nitride material with the thickness of 20nm on the silicon dioxide by using chemical vapor deposition to obtain the silicon-based film substrate.
2. And corroding the silicon substrate surface of the silicon-based film substrate by using a chemical wet method to form a film window with the side length of 20 mu m, namely obtaining the silicon-based film substrate with the film window.
3. Etching one surface (front surface) of silicon nitride material with helium ion beam (etching parameters are set as 10 μm of diaphragm, less than or equal to 1pA of beam current, and dosage of 100-300 nc/μm2) Processing to form a row with a length of 300nm, a width of 5nm and a depth of 20nmAnd the period is 300 nm.
4. On one side (back side) with a film window, in the area corresponding to the nanowire array formed by processing the front side, in the direction of 10-degree included angle with the nanowire array processed on the front side, helium ion beam etching is also adopted (etching parameters are set as 10 mu m of diaphragm, the beam current is less than or equal to 1pA, and the dosage is 100-1000 nc/mu m2) Processing to form a transverse nanowire with the length of 700nm, the width of 5nm and the depth of 200 nm.
5. The vertical nanowires forming the nanowire array are found on the front surface of the material, and an impermeable funnel-shaped small hole is etched at each of two ends of each nanowire, so that the obtained structure is shown in fig. 5, wherein a, b and c are respectively a top view, a bottom view and a front view.
6. The prepared near-zero thickness nanopore is used for biomolecule detection, and the detection process is as follows:
the prepared near-zero-thickness nanopore is assembled with a detection electrode, a detection cell and the like to form a near-zero-thickness nanopore single-molecule detection device, and long-chain DNA molecules are detected (KCl pH of 1M is 8). The current trace signal is recorded by adjusting the experimental conditions (pH value, bias voltage level, temperature, electrolyte concentration) to be near the optimum conditions (1M KCL, pH8) of the molecule to be measured, and the recorded current trace signal can be analyzed. Because the formed device is of a double-hole structure, a double-capture event is realized with probability theoretically, and a double-hole sawing phenomenon occurs, so that the speed of the through hole of the molecule to be detected is reduced.
Example 3
The preparation process of the nano-pore with the near-zero thickness is as follows:
1. selecting a silicon substrate with the thickness of 10-20 microns, firstly growing a silicon nitride material with the thickness of 20nm on the silicon substrate by adopting a chemical vapor deposition method, and then growing an aluminum oxide material with the thickness of 100nm on the silicon nitride by using chemical vapor deposition to obtain the silicon-based film substrate.
2. And corroding the silicon substrate surface of the silicon-based film substrate by using a chemical wet method to form a film window with the side length of 20 mu m, namely obtaining the silicon-based film substrate with the film window.
3. Etching one surface (front surface) of silicon nitride material with helium ion beam (etching parameters are set as 10 μm of diaphragm, less than or equal to 1pA of beam current, and dosage of 100-500 nc/μm2) Processing is carried out (at this time, the reason that the nano line array is selected to be processed on one surface of the silicon nitride material is that one surface of the thin silicon nitride material is thin, so that the depth of the nano line array is smaller by processing and forming the nano line array on one surface of the silicon nitride material, and the material damage is reduced), and a row of vertical nano line arrays with the length of 2000nm, the width of 50nm, the depth of 20nm and the period of 500nm is formed.
4. On one surface (back surface) of the aluminum oxide material, corresponding to the area of the nanowire strip array formed by processing the front surface, in the direction forming an included angle of 90 degrees with the nanowire strip array formed by processing the front surface, helium ion beam etching is also adopted (the etching parameters are set as 10 mu m of diaphragm, the beam current is less than or equal to 1pA, and the dosage is 100-2000 nc/mu m2) Processing is carried out to form a transverse nanowire strip with the length of 3 mu m, the width of 50nm and the depth of 100 nm.
5. Vertical nanowires forming a nanowire strip array are found on the front surface of the material, and two ends of each nanowire strip are respectively etched with an impermeable funnel-shaped small hole, wherein the structure of the vertical nanowires is shown in fig. 6, and a, b and c are respectively a top view, a bottom view and a front view.
6. The prepared near-zero thickness nanopore is used for biomolecule detection, and the detection process is as follows:
the prepared near-zero thickness nanopore is assembled with a detection electrode, a detection cell and the like to form a near-zero thickness nanopore monomolecular detection device, and an image of the near-zero thickness nanopore after AFM characterization is shown in FIG. 8. The protein molecules were also detected as described in the above examples. As the nano-pores in the detection device adopted in the detection process are physically near to zero thickness, the formed detection device has a porous structure, multiple capture events can be realized theoretically with probability, the molecular via events can be prolonged by several orders of magnitude, and the data transmission flux of the sensing structure is greatly increased.
The schematic 3D effect of the prepared device with a nanopore of near-zero thickness is shown in fig. 1, where a is a top view, b is a bottom view, and c is a line frame view in perspective. Fig. 2 is a schematic cross-sectional 3D effect diagram, wherein a is a 3D cross-sectional view and b is a perspective cross-sectional view of a 3D line frame. The preparation process of the invention is shown in figure 3, and is respectively shown by adopting the change processes of a top view (upper) and a front view (lower), firstly, a compound material is grown on a silicon substrate by a chemical vapor deposition method, a silicon-based film substrate with a film window is formed by chemical wet etching, secondly, helium ion beam etching is carried out on the front surface of the silicon-based film substrate with the film window to form a nano line array, then, helium ion beam etching is carried out on the back surface of the silicon-based film substrate to form a nano line with an included angle of 10-90 degrees with the nano line array, and the preparation process can also comprise that an impermeable funnel-shaped small hole is respectively etched at two ends of the nano line array. FIG. 4 is a near zero thickness nanopore of a single pore structure prepared by the method of the present invention in example 1, wherein a, b, and c are top, bottom, and front views, respectively; fig. 5 is a near-zero thickness nanopore of a double-pore structure prepared by the method of the present invention in example 2, wherein a, b, and c are a top view, a bottom view, and a front view, respectively. Fig. 6 is a near-zero thickness nanopore of a porous structure prepared by the method of the present invention in example 3, wherein a, b, and c are top, bottom, and front views, respectively. Fig. 7 is an image obtained by FIB scanning after the nanowire array is formed on the front surface by the method of the present invention in example 1. Figure 8 is a representation of AFM after processing to form a porous near-zero nanopore device by the method of the present invention in example 3. Fig. 9 is a recorded result (IV _02_1M KCL pH8) and an IV-fit plot (fixed Data) of the near-zero nanopore formed detection device prepared by the method of the present invention in example 1 tested under conditions of 300mV voltage, 1M KCL, pH 8. FIG. 10 is a graph showing the change in current occurring when a plasmid molecule (PUC18) was detected under the conditions of 300mV voltage, 1M KCL, and pH8 in the near-zero nanopore-formed detection device prepared by the method of the present invention in example 1.
In fact, the near-zero thickness nanopore sensing device prepared by helium ion beam processing has the advantage of highly controllable processing precision, so that the near-zero thickness nanopore sensing device has the advantage of being developed into a universal sensing platform. By utilizing different properties of compound materials for forming the film and different numbers and sizes of processed hole structures, the most suitable sensing condition can be conveniently and controllably tested aiming at different molecules to be tested, namely, the materials, the hole diameters and the hole patterns can be adjusted according to the properties of the molecules to be tested. Therefore, the nano-pore with the near-zero thickness prepared by the method has great application potential in nano-pore biosensing.
In summary, the invention discloses a method for preparing a near-zero-thickness nanopore by double-sided helium ion beam etching, which is characterized in that a highly-controllable zero-thickness nanopore structure is prepared by a helium ion beam processing method with extremely high processing precision and controllability, so that the material, the pore size pattern and the pore size number of the nanopore structure can be specially designed according to the properties of molecules to be detected, and the spatial resolution, the time resolution and the capture rate of DNA, RNA sequence or DNA sequence modification, RNA sequence modification or protein detection of the nanopore can be improved. The preparation method of the invention has the main advantages that: (1) the processing mode of helium ion beam etching is adopted, the processing precision of sub-10 nm can be achieved when the fine structure is processed by the helium ion beam etching, the processing precision of biomolecular recognition and holes is very important, the depth-to-width ratio of the helium ion beam etching is very good, and the helium ion beam etching is different from a funnel-shaped nano hole formed by a TEM drilling technology, and the helium ion beam etching can form a very regular columnar channel shape; (2) the method for processing the double surfaces is provided, the nano line array is processed and formed on the front surface, the nano line is processed and formed on the back surface, and the nano hole can be formed only by the nano line processed on the back surface within the range of the nano array processed on the front surface, so that the method is very convenient, and the problem that the material is easily damaged by punching a long line structure or directly performing large-area thinning on a regional material due to the small size and the fragile texture of a silicon nitride film is solved; (3) meanwhile, the length of the nanowire formed by processing the back can be adjusted according to the requirements of single holes, double holes or multiple holes, so that the nanowire array can be used for preparing nanopore biosensing detection with different purposes (for example, the formation of a single hole can carry out the traditional nanopore biosensing detection, and the physicochemical property of molecules to be detected is displayed through current change; (4) the specific shape of the formed aperture can be controlled by adjusting the angle between the nanowire array formed by processing the front surface and the nanowire array formed by processing the back surface; (5) simultaneously, forming an impermeable funnel-shaped small hole on each of two sides of the nano-lines of the nano-line array formed on the front surface by using an ion beam, and attracting molecules to be detected by utilizing the funnel-shaped shape and introducing the molecules into the channel so as to enter the nano-holes, thereby improving the capture rate; (6) by controlling the depth in the processing process, the depth of the nanowire array formed on the front surface is smaller than that of the nanowire array formed on the back surface, so that the damage to the material is reduced, and the structure is more stable.
Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.
Claims (10)
1. A method for preparing a nanopore with near zero thickness by double-sided helium ion beam etching is characterized by comprising the following steps:
(1) preparing a silicon-based film substrate: growing a compound material on a silicon substrate with the thickness of 10-20 microns by a chemical vapor deposition method to form a silicon-based film substrate, wherein the compound material comprises any one of a double-layer material consisting of silicon dioxide with the thickness of 50-200 nm and a silicon nitride film with the thickness of 10-30 nm, a single-layer material consisting of a silicon nitride film with the thickness of 20-30 nm or a double-layer material consisting of a silicon nitride film with the thickness of 10-30 nm and an aluminum oxide film with the thickness of 20-100 nm;
(2) preparing a film window: etching the silicon substrate on the silicon-based film substrate in the step (1) by chemical wet etching to enable the silicon substrate to be etched to form a film window with the side length of 10-30 microns, and obtaining the silicon-based film substrate with the film window;
(3) preparing a near-zero thickness nanopore: processing the front surface of the silicon-based film substrate with the film window in the step (2) through helium ion beam etching to form a nano line array with the depth of 10-30 nm, processing the back surface of the silicon-based film substrate with the film window in the step (2) through helium ion beam etching to form a nano line with the depth of 10-220 nm, wherein the nano line array processed on the front surface and the nano line formed by processing the back surface intersect at an included angle of 10-90 degrees to form a nano hole.
2. The method of claim 1, further comprising etching an impermeable funnel-shaped aperture at each end of the nanowires of the nanowire array formed on the front surface to increase the capture rate of the molecules to be detected.
3. The method according to claim 1, wherein when the compound material is a double-layer material consisting of silicon dioxide and a silicon nitride film or a single-layer material formed by a silicon nitride film, one surface where the film window is located is a back surface, and the other surface is a front surface;
when the compound material is a double-layer material consisting of a silicon nitride film and an aluminum oxide film, one surface where the film window is located is a front surface, and the other surface is a back surface.
4. The method according to claim 3, wherein the nanowire strip length in the nanowire strip array formed by front surface processing is 50-3000 nm, the width is 1-50 nm, and the period is 100-1000 nm, and the helium ion beam etching parameters in the front surface processing are set as follows: 10 mu m of diaphragm, less than or equal to 1pA of beam current and 100-500 nc/mu m of dosage2；
The length of the nanowire strips formed by back processing is 50-7000 nm, the width of the nanowire strips is 1-50 nm, and the helium ion beam etching parameters are set as follows: 10 mu m of diaphragm, less than or equal to 1pA of beam current and 100-2000 nc/mu m of dosage2。
5. The method of claim 1, wherein the sum of the depth of the nanowires in the nanowire array and the depth of the nanowires is equal to the thickness of the compound material.
6. The method according to any one of claims 1 to 5, wherein the nanopore with the near-zero thickness is obtained.
7. A near-zero thickness nanopore single molecule detection device, wherein said device comprises the near-zero thickness nanopore of claim 7.
8. The near-zero thickness nanopore single molecule detection device of claim 7, further comprising a detection electrode and a detection cell.
9. Use of the near-zero thickness nanopore single molecule detection device of claim 7 or 8 for single molecule detection analysis.
10. The use according to claim 9, wherein the single molecule is any one of a DNA sequence, an RNA sequence, a protein molecule, a modification of a DNA sequence, or a modification of an RNA sequence.
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