CN102092675A - Method for preparing self-masking uni-junction multiport three-dimensional nano structure - Google Patents

Abstract

The invention discloses a method for preparing a self-mask single-junction multi-terminal three-dimensional nanostructure, which relates to nanostructure preparation technology, including: (1) growth of a functional film material on a substrate; (2) self-mask microstructure on a functional film material The growth of nanomaterials; (3) the placement and fixation of samples prepared in step (2); (4) the preparation of single-junction multi-terminal three-dimensional nanomaterial structures based on ion beam etching; (5) the single-junction multi-terminal free-standing Electrodes are prepared on each end of the three-dimensional nanostructure; (6) a finished product is obtained. In the preparation process of the method of the present invention, the position, structure and size are precisely controllable, and the physical properties and mechanical properties of the three-dimensional nanostructure are uniform and reliable, which provides a new technical approach for the stability of the physical properties of the nano-device, the improvement of the integration degree, and the multi-functional hybrid integration .

Description

A self-masked single-junction multi-terminal three-dimensional nanostructure preparation method

technical field

The invention relates to the technical field of nanostructure preparation, and is a method for preparing a self-mask single-junction multi-terminal three-dimensional nanostructure, especially a self-mask etching formation based on thin film materials, free-standing nano-patterns and ion beam irradiation A method for single-junction multi-terminal 3D functional nanostructures.

Background technique

The development experience of the past few decades has shown that the development of device integration in the field of microelectronics will soon reach its physical and/or economical limits. Nanoelectronic devices are the next generation of solid electronic devices after microelectronic devices. The main idea is to design and prepare nanometer quantum devices based on the quantum effects of nanofunctional materials, so as to further reduce the integrated circuit and replace traditional silicon devices. ultimate goal. In order to break through the limits of the traditional microelectronics integration process, a large number of scientific researchers have invested more and more manpower and material resources in the research of new materials, advanced technology and new device types. In the past ten years, the rapid development of nanotechnology has enabled people to grow various nanomaterials with rich shapes and unique functions, which provides a basis and opportunity for the study of novel physical properties of devices. One-dimensional/quasi-one-dimensional nanomaterials have attracted much attention due to their unique physical properties and their applications in nanodevices such as electronics, photonics and biosensing. In order to achieve high integration and multifunctionality of devices and circuits, researchers continue to synthesize free-standing three-dimensional nanomaterials with rich morphology, disordered or ordered arrangement. The three-dimensional structure not only has the richness of geometric structure and the modulability of mechanical properties, but also has certain functions. It is the key to the high-density and multifunctional integration of nano-devices, and it is the direction and necessity of the development of nano-materials and devices. However, the effective control of the degree of order and spatial distribution of nanomaterials, the uniformity and consistency of the shape and size of nanomaterials, and how to realize the effective preparation of space electrodes of these materials are all necessary for the application of these materials in new devices. Technical problems that need to be solved urgently.

Currently used three-dimensional nanomaterial preparation methods include the template growth method. For example, in the document "Microstructural effects on the magnetic and magneto-transport properties of electrodeposited Ni nanowire arrays" "Nanotechnology", 2010, Vol.21: 425602, anodized aluminum is used as a template and realized by electrochemical deposition or chemical vapor deposition. Filling of Ni nanowires within the template. This method can realize the ordered growth of materials and the growth of different materials, but its disadvantage is that the grown nanomaterials cannot be directly used in the preparation of logic function devices. The measurement of the physical properties of a single nanomaterial needs to go through extraction-dispersion-transfer and electrode Preparation and other process steps, the materials after template dissolution are disordered, and the preparation of three-dimensional devices cannot be realized. The material growth method in the non-template method can realize the growth of multi-terminal nanomaterials through the growth conditions and process. For example, in the literature "Vapour-phase growth, purification and large-area deposition of ZnO tetrapod nanostructures". Crystal growth, through the optimization of the traditional vapor deposition process, four-arm nanocrystals with basically the same shape are obtained, and then the material is purified by vacuum rapid thermal annealing-high temperature annealing in oxygen environment-liquid dissolution treatment steps. Finally, four-armed nanocrystals with different sizes were dispersed and separated by suspension layering method under polarized solution to obtain multi-terminal nanomaterials with uniform size. The process of this method is complicated, and its shortcomings in the application of three-dimensional nano-devices include: (1) the distribution of the spatial position of the obtained nanomaterials is still uncontrollable; (2) there are still problems with the uniformity of material size and chemical composition, which cannot To obtain consistent device characteristics, it is difficult to be used in the preparation of programmable logic function devices and circuits; (3) there are problems such as firmness and mechanical performance stability between nanomaterials and supporting substrates. Another preparation method of three-dimensional nanomaterials that can overcome some of the above-mentioned shortcomings is based on focused ion beam direct writing technology. Using this process, three-dimensional nanomaterials with arbitrary geometric shapes can be grown, and high controllability of spatial and in-plane distribution can be achieved. However, the types of gaseous molecular sources available in this process are very limited, which limits the types of materials that can be grown and cannot satisfy the preparation of multifunctional devices.

Contents of the invention

The purpose of the present invention is to overcome the defects existing in the existing nanomaterial preparation technology, and provide a method for preparing a self-mask single-junction multi-terminal three-dimensional nanostructure. In the preparation, the position, structure and size are precisely controllable, and the three-dimensional nanostructure The physical and mechanical properties are uniform and reliable, which provides a new technical approach for the stability of the physical properties of nano-devices, the improvement of integration and the integration of multi-functional hybrids.

For achieving the above object, technical solution of the present invention is:

A method for preparing a self-mask single-junction multi-terminal three-dimensional nanostructure, comprising the following steps:

(1) Growth of functional thin film materials on the substrate: using chemical vapor deposition (CVD), plasma enhanced chemical vapor deposition (PECVD), plasma laser deposition (PLD), metal organic chemical vapor deposition (MOCVD), low pressure chemical vapor Deposition (LPCVD), molecular beam epitaxy (MBE), electron beam evaporation, thermal evaporation, sputtering, electroplating, spin coating one or a combination of methods, growth on conductor, semiconductor or dielectric thin film materials;

(2) Growth of self-mask micro-nano materials on functional thin film materials:

The growth methods of self-mask micro-nano materials include two methods: one is to use focused ion beam/focused electron beam to directly write micro-nano materials, and the steps include: (i) placement and fixation of thin film samples; (ii) adjustment of sample stage (iii) direct writing deposition of nanomaterials; the second is through pattern transfer method: form anti-reagent patterns with photolithography, and then use electroplating or vapor deposition to grow micro-nano material arrays with high aspect ratio;

(3) Placement and fixation of samples prepared in step (2):

(i) If the substrate is a conductive substrate with a surface insulating film layer, fix the back of the substrate on the sample holder with a conductive substance; if the substrate is an electrically insulating substrate with a surface conductive layer, fix the substrate on the sample holder After the holder is placed, connect the edge of the sample surface to the sample holder with a conductive substance; (ii) put the sample fixed on the sample holder in (i) step into the sample stage in the vacuum sample chamber of the ion beam etching equipment;

(4) Preparation of single-junction multi-terminal three-dimensional nanomaterial structure based on ion beam etching:

When the ion beam is incident on the sample fixed in step (3) at a certain oblique angle, the etching effect on the functional thin film material can be caused due to ion beam irradiation, but under the ion beam projection of the free-standing nanomaterial The functional thin film layer can avoid etching under the action of its mask, thereby forming a functional nanomaterial pattern structure in the substrate plane;

According to the characteristics of the ion source, there are two types of ion beam equipment used in the preparation of single-junction and multi-terminal three-dimensional nanomaterial structures: focused ion beam system and wide beam ion beam system. For different systems, the use and placement of sample holders and irradiation engraving The parameters used by the eclipse are different;

When using a focused ion beam etching system, the preparation process includes: (i) adjustment of the position of the sample stage; (ii) setting of the scanning time and selection of the incident ion beam current; (iii) non-vertical irradiation of the ion beam to form a single Junction double-terminal nanostructure; (iv) rotating or/and tilting the sample stage; (v) repeating step (iv) multiple times to obtain a single-junction multi-terminal free-standing three-dimensional nanostructure;

When using a wide-beam ion beam etching system, reactive ion etching (RIE) or inductively coupled plasma etching (ICP), etc. are used. The steps include: (i) selection of the sample holder, (ii) placement of the sample, (iii) ) setting of etching parameters, and (iv) etching to form multi-terminal nanostructures;

(5) Prepare electrodes for each end of the single-junction multi-terminal free-standing three-dimensional nanostructure:

For the non-common ends of the nanostructures located in the substrate plane, use electron beam lithography related processes, focused electron beam or ion beam induced deposition methods to form electrode contacts; for the free ends of self-mask free standing micro-nano materials, through SEM Or FIB chemical vapor deposition to form three-dimensional electrode contacts and connections in situ;

(6) Get the finished product.

In the preparation method, in the step (1), the film material is a single-layer film, a multi-layer film or a single substrate structure, a flat material or a multi-dimensional pattern structure of a single substance, a compound, a mixture, and a hybrid material system;

Said preparation method, in said step (2), in the method of using focused ion beam/focused electron beam to directly write nanomaterials, in step (i) the sample is fixed using a sample with a horizontal surface or a certain inclination angle θ Torr, the inclination angle is between 0°≤θ≤90°; the inclination angle of the sample stage in step (ii) is arbitrary, and the angle range between the incident direction of the FIB ion beam and the mask material is 0°<β<90 °; The direct-writing deposition of nanomaterials in step (iii) is focused electron beam/ion beam induced nanomaterials, or spatially mixed nanomaterials, and the types of materials include metals, semiconductors, and dielectrics.

In the preparation method, in the step (2), when the self-mask nanomaterial is prepared by the pattern transfer method, the preparation of the anti-reagent pattern adopts optical or electron beam, ion beam exposure technology to prepare a high aspect ratio Thick glue or multi-layer glue patterns, then electroplating or vapor deposition or metal deposition, and then use the lift-off process to grow micro-nano material arrays with high aspect ratios.

In the preparation method, in the step (3), the sample holder used has a horizontal surface or has a certain inclination angle, and the inclination angle ranges from 0°≤θ≤90°.

Described preparation method, in its described step (4), finish from mask etching process or on single-beam FIB or three-beam SEM-FIB-Ar ⁺ system; Used ion source is liquid Ga ⁺ ion source, Or He ⁺ , O ²⁺ , Ar ⁺ ion source; it is a focused ion source device, or a wide-beam ion beam etching device, the beam is incident perpendicular to the ground plane, or incident in any direction, according to the specific ion beam of the equipment Select the appropriate sample holder and the tilt angle and rotation angle of the sample stage according to the incident angle.

The preparation method, in the step (4), the adjustment of the position of the sample stage, the setting of its inclination angle (β) and the inclination angle (θ) of the sample holder, the angle between the self-mask nanomaterial and the support plane The combination of (α) is the key factor affecting the size of the prepared nanomaterials; for the self-mask nanomaterials grown perpendicular to the functional nanofilm substrate, the selection of the inclination angle of the sample stage and the inclination angle of the sample holder can meet the requirements of the incident ions. Under the condition that the beam is non-parallel and non-perpendicular to the length direction of the self-mask, they all play a self-mask effect and form nanowires in the substrate plane. The set value of the inclination angle (β) of the sample stage is only affected by the device itself. Restrictions: When the self-mask nanomaterial and its functional film support plane have a certain angle, as long as the ion beam is not incident parallel to the length direction of the self-mask, the self-mask effect will be achieved.

In the preparation method, in the step (4), the scanning time, the beam current of the incident ion beam, and the setting and selection of the sample stage are related, and need to be considered comprehensively; if it is a single-layer film, design each nanowire The thickness of the nanowire is d, the number of nanowires formed is n, then the thickness of the nanofilm should be dt; if the angle between every two adjacent nanowires designed and prepared is Ф, the rotation angle distance of the sample stage should be set to Ф; the setting of scanning time t is based on the etching rate v(d/t) of the functional thin film material under a certain ion beam current (I _p );

When preparing nanowire families with different thicknesses and included angles, control the thickness of the prepared nanowires according to the selection of etching rate and time, and the rotation angle of the sample stage to control the in-plane included angle between the nanowire families; or by etching The adjustment of etch rate and time, the design of multi-layer film, the multi-terminal structure of different material types grown together; for the self-mask nanomaterial with the same size and structure on the functional film, the difference between the ion beam and the self-mask nanomaterial The included angle determines the length of functional nanowires that can be prepared in the substrate plane.

Said preparation method, in said step (4), for the prepared thin film material and self-mask material, the position of the sample stage determines the projected size and shape of the mask nano-material in the substrate plane, so it is determined The key factors of the length and shape of the obtained nanomaterials; the scanning time and the beam current of the incident ion beam are parameters that determine the thickness of the obtained nanomaterials, which ultimately affect the length, width and surface morphology of the nanomaterials; the relative size of the sample stage The rotation angle determines the angle between different nanomaterials in the x-y plane, and at the same time, the size of the prepared nanomaterials in the substrate plane is controlled by adjusting the tilt angle of the sample stage; the substrate plane is set by repeating the above steps The number of inner cojunction nanowires.

In the preparation method, the projection pattern of the self-mask material on the substrate plane determines the shape and dimension of the nanomaterials in the plane. When the self-mask is a three-dimensional nano-conical structure, the prepared substrate plane The nanomaterials inside have a triangular sheet structure.

Described preparation method, in its described step (5), the preparation method of the nano-electrode contacting and connecting line of free-standing end has focused ion beam and/or focused electron beam induced chemical vapor phase in-situ deposition method; Electrode preparation methods include focused ion beam and/or focused electron beam induced chemical vapor phase in-situ deposition, two preparation processes related to ordinary optical lithography or electron beam lithography.

Compared with the preparation method of the existing three-dimensional micro-nano material, the method of the present invention has the following advantages:

1. High process controllability. This approach combines top-down as well as bottom-up material preparation schemes. Using thin films or substrates as functional materials, using self-mask processing methods based on ion beam irradiation etching, on the one hand, overcomes the problems of consistency and repeatability in the processing of nanomaterials, and achieves high-quality growth of substrate materials; On the one hand, the highly controllable nanoscale preparation process of materials is realized through the etching produced by ion beam irradiation. In this way, the stability, consistency and repeatability of the intrinsic physical properties of the material, the controllability, high precision and repeatability of the shape, size and process of the nanomaterial during the preparation process form a high-quality preparation Process means of nanomaterials.

2. High flexibility of process

The flexibility of the process is manifested in the following aspects: (1) In the growth mode and type of thin film materials, you can freely choose according to your needs, expanding the diversity of material types and combinations of nanostructures that can be prepared; (2) using Focused ion beam (FIB)/electron beam (SEM) deposition with low beam current can precisely design and control the shape, size, distribution and spatial position of the free-space nanometer self-mask through the adjustment of process parameters; ( 3) In the focused ion beam/electron beam system, the movement of the sample stage can be manipulated in five dimensions, combined with the incident ion beam energy, beam current, and irradiation time, the size, shape, and spatial distribution of nanostructures can be highly customized. (4) The use of a sample holder with an inclined angle and a wide-beam etching system ensures the variety of materials that can be etched and processed, and at the same time improves the preparation efficiency.

3. High-precision preparation characteristics of the process. The process has extremely high graphic resolution, FIB-CVD, SEM-CVD is a direct writing technology that is separated from the mask and resist, and the graphic resolution formed can be compared with the size of the graphic produced by electron beam exposure. Realize the direct writing processing function of the real nanometer scale.

4. The multi-dimensional characteristics of the craft. Through the design of the spatial position, a family of nanographs with a spatial geometry, distributed in a size-adjustable substrate plane, and a free-standing single-junction multi-terminal micro-nanostructure array can be prepared to achieve a reproducible three-dimensional nanostructure group.

5. Wide range of materials. There is a wide variety of thin film materials that can be used to form three-dimensional structures. It can be a single-layer or multi-layer structure of an insulator, a conductor, a peninsula, a superconductor, etc.; it can be a simple substance, a mixture, a compound, and an alloy.

6. Features of high-density integration and multi-function. This method forms a three-dimensional device structure. On the one hand, the device area is very small, and on the other hand, the device distribution is very compact, which is conducive to increasing the device density. Based on the growth of ion beam chemical vapor phase three-dimensional materials to make nano-electrodes, effective spatial distribution and connection preparation can be carried out according to the characteristics of the device; the multi-terminal nanowire structure in the substrate plane and the free-standing nanomaterials co-exist in space, Nanoscale point contact structures with different contact characteristics can be formed; in addition, not only any end of the micro-nano structure can be used as an effective unit of the device, but also there is no damage to the spatial structure and position of the nanomaterial and mechanical damage.

7. High efficiency in the fabrication of prototype devices. When the thin film material is grown, the nanoscale process of the three-dimensional structure, the preparation of space and planar electrodes can be completed in one go on the SEM/FIB or single-beam FIB system, which has time and cost advantages; Process flexibility, completeness and accuracy of materials, devices and logic functional units.

In short, the processing technology of self-mask nano-3D structure based on thin film materials and ion beam irradiation can overcome the problems of repeatability, uniformity and consistency of materials, and randomness of spatial distribution in traditional material growth processes. The preparation of high-density multifunctional 3D devices and 3D hybrid integration provide new ideas and methods.

Description of drawings

Fig. 1 is a flow chart of a method for preparing a self-mask single-junction multi-terminal three-dimensional nanostructure of the present invention; wherein:

Figure 1a is the growth of functional thin film material layer;

Figure 1b, the growth of self-mask nanomaterials;

Figure 1c shows the formation of a single-junction double-ended three-dimensional nanostructure after FIB irradiation of Figure 1b;

Figure 1d shows the formation of a single-junction three-terminal three-dimensional nanostructure after FIB irradiation of Figure 1c;

Fig. 1e, preparation of in-plane and space electrodes and wires on the nanostructure, resulting in a device.

Explanation of the numerals in the figure: 10 is the substrate part, 11 is the functional thin film layer, 12 is the self-mask nanomaterial, 13 is the incident direction of the ion beam, 14-15 is the prepared nanowire group located in the substrate plane, 16 is The electrode contact block, 17 is a three-dimensional nano wire.

Fig. 2 is the SEM side view of the Au nanowire prepared by focused ion beam etching in the method embodiment of the present invention; wherein:

Figure 2a shows the growth of self-masked nanowires on Au/SiO2/Si substrate;

Figure 2b shows that the ion beam is incident at an angle of 20 degrees to the length direction of the nanowire, and the gold (Au) nanowire is formed under the mask etching of the nanowire;

Fig. 2c shows the preparation of Au nanowires perpendicular to the Au nanowires in Fig. 2b by etching the nanowire mask after rotating the sample stage by 90 degrees.

Explanation of numerals in the figure: 21 is an Au/SiO2/Si substrate, 22 is a tungsten nanorod grown perpendicular to the substrate; 23 and 24 are nanowires formed by FIB irradiation.

Fig. 3 is the schematic diagram of the finished product of silicon (Si) nanowire family made on the Si/SiO ₂ /Si substrate structure by the method of the present invention by wide-beam ion beam irradiation; Wherein: 30 is Si/SiO ₂ /Si substrate structure, 31 is a tungsten nanowire perpendicular to the substrate structure, and 32-35 are a group of Si nanowires formed by etching with broad-beam ion beam irradiation.

Detailed ways

As shown in Figure 1, it is a schematic diagram of a method for preparing a self-mask single-junction multi-terminal three-dimensional nanostructure of the present invention, wherein, Figure 1a is a functional thin film material layer or a functional substrate structure located on a substrate; Figure 1b is a structure on a substrate Self-mask nanostructures grown on the bottom; Figure 1c shows the formation of a single-junction double-terminal three-dimensional nanostructure after FIB irradiation of the structure Figure 1b; Figure 1d shows the formation of a single-junction three-terminal nanostructure after the horizontal rotation of Figure 1c by 180 degrees for FIB irradiation Three-dimensional nanostructure; Figure 1e shows the fabrication of in-plane and space electrodes and wiring on a single-junction multi-terminal three-dimensional nanostructure, and finally forms a multi-terminal structure.

Method of the present invention comprises steps:

(1) Growth of functional thin film material layer on the substrate

Using Si, GaAs, InP, GaN, quartz, sapphire, MgO and other materials as substrates, using molecular beam epitaxy, atomic layer deposition, chemical vapor deposition, sputtering, evaporation, electrochemical deposition, sol-gel and other methods to grow conductors , semiconductor, dielectric thin film materials.

(2) Growth of free-standing self-mask micro-nano materials on the functional thin film material layer

There are roughly two growth methods for self-mask materials: one is direct writing of nanomaterials using focused ion beams/focused electron beams. The steps include: (i) placing and fixing the thin film sample, if the substrate is a conductive substrate with an insulating film layer on the surface, use a conductive substance to fix it on the sample holder from the back of the substrate. If the substrate is an electrically insulating substrate with a surface conductive layer, after the sample is fixed on the sample holder, the edge of the sample surface is connected to the sample holder with a conductive substance. Put the sample fixed on the sample holder on the sample stage in the double-beam SEM/FIB or single-beam FIB cavity. (ii) Adjustment of the sample stage, the sample stage is tilted at a certain angle, so that the FIB and the mask material are incident at different angles. (iii) For the growth of nanomaterials, use SEM or low-beam ion flow for pattern observation, find the area that needs to be patterned, and determine the position, growth distribution and size of free-standing micro-nano materials; introduce relevant metal organic gaseous molecular sources , material growth by ion beam scanning.

The second is to form an anti-reagent pattern by pattern transfer, that is, photolithography or electron beam exposure, and then use methods such as electroplating or vapor deposition to grow nanomaterial arrays with high aspect ratios.

(3) Placement and fixation of the sample formed in step (2):

For different etching equipment, the use of sample holders, and the placement of samples have different places. When using a focused ion beam system for irradiation etching, if the substrate is a conductive substrate with a surface insulating film layer, use a conductive substance to fix it on the sample holder from the back of the substrate; if the substrate is a conductive substrate with a surface Electrically insulating substrate, after fixing the sample on the sample holder, connect the edge of the sample surface to the sample holder with a conductive substance. Put the sample fixed on the sample holder into the sample in the double-beam SEM/FIB or single-beam FIB cavity Then the sample stage is tilted at a certain angle so that the FIB and the mask material are incident at different angles. When using a wide-beam system, when the position of the sample stage is fixed and cannot be adjusted, it is necessary to select the available material according to the angle between the self-mask material and the substrate, the height of the self-mask nanowire, and the length of the nanowire in the plane to be processed. Sample holders with different tilt angles.

(4) Controllable preparation of single-junction multi-terminal three-dimensional nanomaterial structures based on multiple ion beam irradiation:

The preparation process of the single-junction multi-terminal three-dimensional nanomaterial structure based on multiple ion beam irradiation includes: i) adjusting the position of the sample stage so that the ion beam is incident at a certain angle, thereby controlling the size of the ion beam projection; ii) setting a specific The scanning time and the beam current of the incident ion beam are used to control the thickness of the nanowires and the speed of film nanosizing. iii) Non-perpendicular ion beam irradiation is performed, the ion beam scanning area is set by the magnification or the size of the ion beam scanning interval, and the nano-processing of the thin film material is performed by etching. iv) Adjust the rotation angle or/and inclination angle of the sample stage, repeat steps (i-iii) multiple times, control the angle between the previous nanowire and the subsequently prepared nanowire through the rotation angle of the sample stage, and pass The adjustment of the tilt angle controls the length of the nanowire.

When using a wide-beam ion beam etching system, such as reactive ion etching (RIE), inductively coupled plasma etching (ICP), etc., the steps include the selection of the sample holder, the placement of the sample, the etching parameters (power, time, etch Etching gas, etc.) and etching to form multi-terminal nanostructures.

(5) Obtaining a three-dimensional nanostructure with single junction and multiterminal free standing.

Nano-electrodes are respectively prepared for each end of the single-junction multi-terminal free-standing three-dimensional nanostructure formed in step (4). Growth of electrode contact blocks and/or wiring in the substrate plane: There are generally two options for the production of electrode contact blocks and wiring in the substrate plane: one, before growing free-standing nanomaterials, use traditional photolithography , electron beam exposure or focused ion beam deposition and other methods to form large electrode contact blocks and connections in the substrate plane. For this substrate with large electrode contact block patterns and/or wiring, when the projection of the free end of the free-standing nanometer material is far away from the contact block, it is necessary to grow a connecting line with FIB to connect the two. The distance is shortened, and the process includes: (i) obtaining the FIB image of the free-standing micro-nano material to be processed and the electrode contact block; (ii) using the graphic generator software of the device to generate the connecting line graphic to be processed and determine its position; ( iii) introducing metal organic gaseous molecular sources; (iv) turning on the FIB to scan and deposit metal connections. One end of the connection line should be close to the projection of the free end of the free-standing micro-nano material, and the other end should be connected to the large electrode contact block. The second is for free-standing micro-nano materials without any electrode contact before growth, then according to the position of the material, FIB is used to grow in situ through the above steps (i)-(ii)-(iii)-(iv) Electrode contact blocks and/or electrode leads. Fabrication of 3D electrode contacts and connections: There are generally three process schemes for in-situ growth of 3D structures using SEM/FIB-CVD: (i) Electrostatic displacement method, that is, after setting a specific scanning area, introducing a metal-organic gaseous molecular source , start FIB scanning and use electrostatic bias to continuously deflect and displace the ion beam at a certain speed to obtain a three-dimensional structure; (ii) graphic scanning method, in this method, the scanning time and area of ion beam scanning are controlled by the device program (iii) Precisely control the displacement of the sample stage, that is, the relative position of the ion beam scanning on the substrate is changed by the continuous movement of the sample stage to form a three-dimensional structure.

[Example 1]:

Self-mask preparation of single-junction three-terminal three-dimensional nanostructures on Au/Cr/SiO ₂ /Si film substrates, including the following steps:

1) Preparation of Au/Cr thin film on SiO ₂ /Si substrate. Electron beam evaporation is used to first grow Cr with a thickness of 5 nanometers on the SiO ₂ /Si substrate, and then grow a gold film with a thickness of 80 nanometers to form an Au/Cr/SiO ₂ /Si thin film substrate structure 21 .

2) Growth of self-masked tungsten nanorods perpendicular to the substrate. The substrate in step 1) is fixed on the horizontal surface sample holder with a conductive carbon tape, sent into the SEM/FIB cavity and fixed on the sample stage. The angle between the FIB incident direction and the horizontal plane of the system used is 38°; the electron gun (5kV electron beam acceleration voltage, 30μm electron beam aperture) and ion gun (30kV ion beam acceleration voltage, 1pA ion beam current) are turned on, and the sample The stage was tilted by 52° so that the ion beam was incident perpendicular to the substrate. Heat the W(CO) ₆ metal-organic gaseous molecular source introduction system, introduce the catheter to the substrate surface and open the valve. By point-scanning mode, tungsten nanorods with a height of 3 μm and a diameter of 150 nm were grown, as shown by 22 in Fig. 2a.

3) Controllable preparation of single-junction multi-terminal three-dimensional nanomaterial structures based on multiple ion beam irradiation. The preparation process includes: i) adjustment of the position of the sample stage, so that the ion beam and the substrate are incident at 32 degrees; ii) selection of the incident ion beam current, using 98pA Ga ⁺ ; iii) SEM and FIB imaging, setting the scanning The magnification is 15000, and the single-frame scanning time of the selected ion beam in the entire field of view is 120s. The obtained SEM image of the nano-pattern structure is shown as 23 in Fig. 2b. iv) Rotate the sample stage by 90 degrees, repeat step iii), and the SEM image of the obtained nano-pattern structure is shown as 24 in Fig. 2c.

4) A three-dimensional three-terminal single-junction gold nanowire and tungsten nanocolumn structure is obtained, and the SEM image is shown in Figure 2c.

In step 1) of the present invention, the types of thin film materials are only exemplary, and may be other metals, semiconductors, dielectrics, and the like. Such as Pt, Au, Ag, Co, Cu, Ni, Si, GaN, InP, ZnO, C, Pt-W-Ga-C, _SiO2, etc. The growth methods of thin film materials can be chemical vapor deposition, plasma enhanced chemical vapor deposition, plasma laser deposition, metal organic chemical vapor deposition, low pressure chemical vapor deposition, molecular beam epitaxy, electron beam evaporation, thermal evaporation, sputtering, electroplating, Spin coating one or a combination of these methods. The material can be a single-layer film or a multi-layer film structure; it can be a material system such as a simple substance, a compound, a mixture, and a hybrid, and it can be a planar material or a multi-dimensional graphic structure material. The thickness of the material can range from a few nanometers to a few micrometers. Substrate materials can be insulators, semiconductors and conductors, such as quartz, sapphire, MgO, Si, InP, GaAs and metal blocks.

In step 2) of the present invention, the equipment used for the self-mask material preparation is only exemplary, and in addition to the double-beam system, single-beam and multi-beam systems can also be used. In addition to the Ga+ ion source equipment, other ion source systems can also be used. In addition to the focused ion beam system, a focused electron beam system can also be used.

When using focused ion beam/focused electron beam to directly write self-mask nanomaterials in step 2) of the present invention, the sample can be fixed by using a sample holder with a horizontal surface or a certain inclination angle (0≤θ≤90°); The metal-organic gaseous molecular source used is also exemplary, and other single precursors or combinations of multiple precursors that can grow three-dimensional structures with better electrical conductivity can be used, including WF ₆ , PtC ₇ H ₁₇ , Al(CH ₃ ) ₃ , AuC ₇ H ₇ F ₆ O ₂ or their combination, etc. In addition to nanorods, nanowires, and nanopillars, the self-mask nanometer geometry can also be other complex structures; the types of materials are also diverse, such as metals, semiconductors, dielectrics and other materials.

In step 2) of the present invention, when the self-mask nanomaterial is prepared by the method of pattern transfer, the preparation of the anti-reagent pattern can adopt technologies such as optical or electron beam, ion beam exposure, etc., to prepare thick glue with high aspect ratio or Multi-layer glue pattern, and then use electroplating or vapor deposition, metal deposition, etc. combined with stripping process to grow micro-nano material arrays with high aspect ratio.

In step 3) of the present invention, the sample holder used for placing and fixing the sample may have a horizontal surface or a certain inclination angle (0≤θ≤90°).

In step 3) of the present invention, the self-mask etching process is not limited to be done on a dual-beam SEM/FIB device, but can also be done on a single-beam FIB or three-beam SEM-FIB-Ar ⁺ system. The ion source used is not limited to the liquid Ga+ ion source, He ⁺ , O ²⁺ , Ar ⁺ etc. can also be used. It can be a focused ion source device or a broad beam ion beam etching device.

In step 3) of the present invention, the angle between the incident direction of the FIB of the system and the horizontal plane is only exemplary. The inclination angle of the sample stage satisfies that the angle range between the incident direction of the FIB ion beam and the self-mask material is 0<β<90°. The FIB beam can be incident perpendicular to the ground plane or in any direction, but it needs to be based on The specific incident angle of the ion beam of the equipment selects the appropriate sample holder and the tilt angle and rotation angle of the sample stage. For the self-mask nanomaterials grown perpendicular to the functional nano-film substrate, the inclination angle of the sample stage and the inclination angle of the sample support can be selected under the condition that the incident ion beam is non-parallel to the length direction of the self-mask and non-perpendicular. To self-mask effect, forming nanowires in the plane of the substrate, the set value of the tilt angle of the sample stage is limited only by the device itself. When the self-mask nanomaterial has a certain angle with its functional film support plane, as long as the ion beam is not incident parallel to the length direction of the self-mask, the self-mask effect can be achieved.

In step 3) of the present invention, the selection of the scanning time and the beam current of the incident ion beam is only illustrative. They have a strong correlation with the setting and selection of the sample stage and need to be considered comprehensively. If it is a single-layer film, it is expected that the thickness of each nanowire is d, and the number of nanowires formed is n, then the thickness of the nanofilm should be dt. If it is desired that the included angle between each adjacent nanowire to be prepared is Ф, the rotation angle spacing of the sample stage should be set as Ф. The setting of the scan time t should be based on the etching rate v(d/t) of the functional thin film material under a certain ion beam current (I _p ). In addition, it is possible to prepare nanowire families with different thicknesses and different in-plane angles, that is, to select different etching times and to adjust the rotation angle of the sample stage according to the etching rate. It is also possible to adjust the etching rate and time, and design the multi-layer film to grow a multi-terminal structure of different material types that are co-junction.

The irradiation beam current in step 3) of the present invention is only exemplary, and its range is about 1-300pA and below. The magnification is also exemplary, less than 30,000 times is sufficient. Excessive beam current will lead to over-etching of self-mask nanomaterials, and excessive magnification will reduce the area of the scanning field of view.

In step 3) of the present invention, the rotation angle of the sample stage is only exemplary, and its range is 0<Ф<360.

[Example 2]:

Broad-beam ion beam etching fabricates multi-terminal nanostructures on Si/SiO ₂ /Si substrates, including the following steps:

1) Growing tungsten nanorods: fix the Si/SiO ₂ /Si substrate (30) on the sample holder with conductive silver glue, send it into the SEM/FIB cavity and fix it on the sample stage; tilt the sample stage clockwise by 52 °, so that the substrate surface is perpendicular to the incident direction of the ion beam. Heat the tungsten source (W(CO) ₆ ) of the GIS, turn on the electron beam ion beam, select the ion beam current of 1pA, and adjust the working height and equipment status. Scanning in point mode was adopted, and then the metal-organic gaseous tungsten source was introduced, and the ion beam scanning time was set to 10 min. Gallium ions decompose tungsten-containing organic molecules to form tungsten nanorods 31 perpendicular to the surface of the sample, as shown in FIG. 3 . After the nanorods grow, close the tungsten source valve and return the GIS system to the original non-working position.

(2) Fix the sample processed in step (1) on a sample holder with a 45-degree inclined surface with conductive silver glue, send it into the reactive ion etching (RIE) chamber and fix it on the sample stage. Set the argon (Ar) flow rate to 20sccm, the power to 200W, and the etching time to 5min, and perform the etching process. The obtained SEM side-view image of the in-plane nanowire is shown as 32 in FIG. 3 .

(3) Stop the etching process, open the RIE chamber, rotate the position of the sample on the sample holder at an angle of 20 degrees, and perform etching under the conditions in step (2). The obtained SEM image of the nanowire in the plane is as follows: Shown at 33 in Fig. 3.

(4) Stop the etching process, open the RIE chamber, rotate the position of the sample on the sample holder by 15 degrees relative to the position in step (3), etch under the conditions in step (2), and obtain the in-plane The SEM image of the nanowire is shown at 34 in Fig. 3.

(5) Stop the etching process, open the RIE chamber, rotate the position of the sample on the sample holder by 20 degrees relative to the position in step (4), etch under the conditions in step (2), and obtain the in-plane The SEM image of the nanowires is shown at 35 in Figure 3.

(6) A three-dimensional space single-junction 5-terminal nanostructure is obtained. The SEM image of the three-dimensional 5-terminal functional structure of Si nanowire-free standing W nanorod is shown in FIG. 3 .

In step 1) of this embodiment, the substrate structure used is only exemplary, and can also be other multi-layer or single-layer complex structures, such as p+GaN/InGaN/GaN(MQW)/n+GaN Multiple quantum well structure, NbN/MgO/NbN/sapphire, etc.

In step 2) of this embodiment, the nanorods grown by FIB perpendicular to the substrate surface can also be replaced by other figures, such as square, triangle, polygonal columns and the like.

In step 2) of this embodiment, the inclination angle of the slide plane of the sample holder is exemplary, and its range is 0°≤θ≤90°, and the rotation angle range of the sample on the slide plane after the first etching 0°≤Ф≤360°.

In addition, in step 2) of this embodiment, the use of a reactive ion etching (RIE) wide-beam system is also exemplary, and other ion beam etching systems may also be used. And other etching gases can be selected according to the type of material. Etching parameters can be adjusted according to the material and the expected nanowire size.

In addition, in step 3) of this embodiment, the rotation angle of the sample stage and the repeatable times of the etching step are unlimited, and can be set according to the number of nanowires in the nanowire family to be prepared.

Although the present invention has been specifically described with reference to the above-mentioned embodiments, those of ordinary skill in the art should understand that modifications or improvements can be made based on the disclosure of the present invention, and these modifications and improvements should be included in the claims of the present invention. within the scope of protection of the book.

Claims (11)

1. A method for preparing a self-mask single-junction multi-terminal three-dimensional nanostructure, characterized in that, comprising the following steps: 1) Growth of functional thin film materials on the substrate: using chemical vapor deposition, plasma enhanced chemical vapor deposition, plasma laser deposition, metal organic chemical vapor deposition, low pressure chemical vapor deposition, molecular beam epitaxy, electron beam evaporation, thermal evaporation, Growth on conductive, semiconducting or dielectric thin film materials by sputtering, electroplating, spin coating or a combination thereof; 2) Growth of self-mask micro-nano materials on functional thin film materials: The growth methods of self-mask micro-nano materials include two methods: one is to use focused ion beam/focused electron beam to directly write micro-nano materials, and the steps include: (i) placement and fixation of thin film samples; (ii) adjustment of sample stage (iii) direct writing deposition of nanomaterials; the second is through pattern transfer method: form anti-reagent patterns with photolithography, and then use electroplating or vapor deposition to grow micro-nano material arrays with high aspect ratio; 3) Placement and fixation of the sample prepared in step 2): (i) If the substrate is a conductive substrate with a surface insulating film layer, fix the back of the substrate on the sample holder with a conductive substance; if the substrate is an electrically insulating substrate with a surface conductive layer, fix the substrate on the sample holder After the holder is placed, connect the edge of the sample surface to the sample holder with a conductive substance; (ii) put the sample fixed on the sample holder in (i) step into the sample stage in the vacuum sample chamber of the ion beam etching equipment; 4) Preparation of single-junction multi-terminal three-dimensional nanomaterial structure based on ion beam etching: When the ion beam is incident on the sample fixed in step (3) at a certain oblique angle, the etching effect on the functional thin film material can be caused due to ion beam irradiation, but under the ion beam projection of the free-standing nanomaterial The functional thin film layer can avoid etching under the action of its mask, thereby forming a functional nanomaterial pattern structure in the substrate plane; According to the characteristics of the ion source, there are two types of ion beam equipment used in the preparation of single-junction and multi-terminal three-dimensional nanomaterial structures: focused ion beam system and wide beam ion beam system. For different systems, the use and placement of sample holders and irradiation engraving The parameters used by the eclipse are different; When using a focused ion beam etching system, the preparation process includes: (i) adjustment of the position of the sample stage; (ii) setting of the scanning time and selection of the incident ion beam current; (iii) non-vertical irradiation of the ion beam to form a single Junction double-terminal nanostructure; (iv) rotating or/and tilting the sample stage; (v) repeating steps (iii) and (iv) multiple times to obtain a single-junction multi-terminal free-standing three-dimensional nanostructure; When using a wide-beam ion beam etching system, reactive ion etching or inductively coupled plasma etching is used, and the steps include: (i) selection of the sample holder, (ii) placement of the sample, (iii) setting of etching parameters , and (iv) etching to form a multi-terminal nanostructure; 5) Prepare electrodes for each end of the single-junction multi-terminal free-standing three-dimensional nanostructure: For the non-common ends of the nanostructures located in the substrate plane, use electron beam lithography related processes, focused electron beam or ion beam induced deposition methods to form electrode contacts; for the free ends of self-mask free standing micro-nano materials, through SEM Or FIB chemical vapor deposition to form three-dimensional electrode contacts and connections in situ; 6) Get the finished product. 2. preparation method as claimed in claim 1, is characterized in that, described step 1) in, thin film material is single-layer film, multilayer film or simple substance, compound, mixture and hybrid material system of single substrate structure flat material or multidimensional graphic structure. 3. The preparation method according to claim 1, characterized in that, in the step 2), in the method of using focused ion beam/focused electron beam to directly write nanomaterials, in step (i), the sample is fixed using a method with a horizontal surface Or a sample holder with a certain inclination angle θ, the inclination angle is between 0°≤θ≤90°; the inclination angle of the sample stage in step (ii) is arbitrary, and the angle between the incident direction of the FIB ion beam and the mask material The range is 0°<β<90°; the direct writing deposition of nanomaterials in step (iii) is focused electron beam/ion beam induced nanomaterials, or spatially mixed nanomaterials, and the types of materials include metals, semiconductors, and dielectrics . 4. The preparation method according to claim 1, characterized in that, in the step 2), when the self-mask nanomaterial is prepared by the method of pattern transfer, the preparation of the anti-reagent pattern adopts optical or electron beam, ion beam exposure Technology, prepare thick glue or multi-layer glue pattern with high aspect ratio, then use electroplating or vapor deposition or metal deposition, and then use lift-off process to grow micro-nano material array with high aspect ratio. 5. The preparation method according to claim 1, characterized in that, in the step 3), the sample holder used has a horizontal surface or has a certain inclination angle, and the inclination angle ranges from 0°≤θ≤90°. the 6. preparation method as claimed in claim 1 is characterized in that, described step 4) in, self-mask etching process or finish on single-beam FIB or three-beam SEM-FIB-Ar ⁺ system; Used ion The source is a liquid Ga ⁺ ion source, or a He ⁺ , O ²⁺ , Ar ⁺ ion source; it is a focused ion source device, or a wide-beam ion beam etching device, and the beam is incident perpendicular to the ground plane, or in any direction When incident, select the appropriate sample holder and the tilt angle and rotation angle of the sample stage according to the specific incident angle of the ion beam of the equipment. 7. The preparation method as claimed in claim 1 or 6, characterized in that, in said step 4), the adjustment of the position of the sample stage, the setting of its inclination angle (β) and the inclination angle (θ) of the sample holder are automatically The combination of the angle (α) between the mask nanomaterial and the support plane is a key factor affecting the size of the prepared nanomaterial; for the self-mask nanomaterial grown perpendicular to the functional nanofilm substrate, the inclination angle of the sample stage is related to The selection of the inclination angle of the sample holder satisfies the condition that the incident ion beam is non-parallel and non-perpendicular to the length direction of the self-mask, and both play a self-mask effect to form nanowires in the plane of the substrate. The inclination angle of the sample stage (β ) is only limited by the device itself; when the self-mask nanomaterial has a certain angle with its functional film support plane, as long as the ion beam is not incident parallel to the length direction of the self-mask, it will play a self-mask effect . 8. The preparation method as claimed in claim 1 or 6, characterized in that, in the step 4), the scanning time, the beam current of the incident ion beam, and the setting and selection of the sample stage are relevant, and should be considered comprehensively; if If it is a single-layer film, the thickness of each nanowire is designed to be d, and the number of nanowires formed is n, then the thickness of the nanofilm should be grown as dt; if the angle between every two adjacent nanowires designed and prepared is , the rotation angle distance of the sample stage should be set to Ф; the setting of the scanning time t is based on the etching rate v(d/t) of the functional thin film material under a certain ion beam current (I _p ); When preparing nanowire families with different thicknesses and included angles, control the thickness of the prepared nanowires according to the selection of etching rate and time, and the rotation angle of the sample stage to control the in-plane included angle between the nanowire families; or by etching The adjustment of etch rate and time, the design of multi-layer film, the multi-terminal structure of different material types grown together; for the self-mask nanomaterial with the same size and structure on the functional film, the difference between the ion beam and the self-mask nanomaterial The included angle determines the length of functional nanowires that can be prepared in the substrate plane. 9. preparation method as claimed in claim 1 is characterized in that, described step 4) in, for the thin film material that has prepared and self-mask material, the position of sample stage determines the position of mask nanomaterial in substrate plane. The projection size and shape are thus the key factors determining the length and shape of the obtained nanomaterials; the scanning time and the beam current of the incident ion beam are parameters that determine the thickness of the obtained nanomaterials, which ultimately affect the length, width and Surface morphology; the relative rotation angle of the sample stage determines the angle between different nanomaterials in the x-y plane, and at the same time, the size of the prepared nanomaterials in the substrate plane is controlled by adjusting the inclination angle of the sample stage; by repeating the above steps The number of times to set the number of co-junction nanowires in the substrate plane. 10. preparation method as claimed in claim 9, is characterized in that, the shape and the dimension of the nanometer material in the determination plane of the projection pattern of described self-mask material in substrate plane, is when self-mask is three-dimensional nano-conical In the structure, the prepared nanomaterials in the plane of the substrate have a triangular sheet structure. 11. preparation method as claimed in claim 1 is characterized in that, described step 5) in, the preparation method of the nano-electrode contact of free-standing end and connecting line has the chemical vapor phase induced by focused ion beam and/or focused electron beam In-situ deposition method; an in-plane electrode preparation method, including focused ion beam and/or focused electron beam induced chemical vapor phase in-situ deposition, two preparation processes related to ordinary optical lithography or electron beam lithography. the

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