CN113607977A - Terahertz nano near-field scanning probe and manufacturing method thereof - Google Patents

Terahertz nano near-field scanning probe and manufacturing method thereof Download PDF

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Publication number
CN113607977A
CN113607977A CN202111003715.9A CN202111003715A CN113607977A CN 113607977 A CN113607977 A CN 113607977A CN 202111003715 A CN202111003715 A CN 202111003715A CN 113607977 A CN113607977 A CN 113607977A
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China
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cantilever
probe
tip
terahertz
metal
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CN202111003715.9A
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Chinese (zh)
Inventor
邱付成
王化斌
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Chongqing Institute of Green and Intelligent Technology of CAS
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Chongqing Institute of Green and Intelligent Technology of CAS
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Priority to CN202111003715.9A priority Critical patent/CN113607977A/en
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01QSCANNING-PROBE TECHNIQUES OR APPARATUS; APPLICATIONS OF SCANNING-PROBE TECHNIQUES, e.g. SCANNING PROBE MICROSCOPY [SPM]
    • G01Q60/00Particular types of SPM [Scanning Probe Microscopy] or microscopes; Essential components thereof
    • G01Q60/18SNOM [Scanning Near-Field Optical Microscopy] or apparatus therefor, e.g. SNOM probes
    • G01Q60/22Probes, their manufacture, or their related instrumentation, e.g. holders

Abstract

The invention relates to a terahertz nano near-field scanning probe and a manufacturing method thereof, belonging to the technical field of terahertz application. The probe comprises a probe tip, a cantilever and a probe base; the needle tip is fixed on the probe base through a cantilever; the tail end of the cantilever is provided with a through hole for fixing a needle point; the probe manufacturing method comprises the steps of preparing a nanometer needle tip by using an electrochemical corrosion method, etching a through hole with a specific size on an atomic force probe cantilever by using a focused ion beam technology, then cutting the electrochemical corrosion needle tip with a specific length by using the focused ion beam technology and a nanometer transfer technology, transferring the electrochemical corrosion needle tip into the cantilever through hole, and finally fixing the needle tip and the cantilever by using a deposition method. The invention solves the problems of low yield, large error range, complex technology, high preparation process requirement and the like of the traditional THz nano scanning probe.

Description

Terahertz nano near-field scanning probe and manufacturing method thereof
Technical Field
The invention belongs to the technical field of terahertz application, and relates to a terahertz nano near-field scanning probe and a manufacturing method thereof.
Background
Terahertz (THz) imaging is one of important application directions of THz technology, THz waves are between millimeter waves and infrared light, and THz wave imaging can obtain higher resolution compared with millimeter wave or microwave imaging because THz waves have shorter wavelengths; compared with infrared, THz waves can penetrate through a plurality of materials which cannot be penetrated by infrared, such as paper, plastics, ceramics, semiconductors and the like, and imaging of a hidden target object is completed; compared with the X-ray widely applied in the fields of medical imaging, security inspection imaging and the like, the THz wave has lower energy (1 THz-4 meV), can make up for the obvious defect that the X-ray easily causes radiation damage to a human body, and has better contrast for imaging low-density substances than the X-ray.
Due to the limitation of diffraction limit, the spatial resolution of the traditional THz imaging is generally in the sub-millimeter order and is far lower than that of visible light imaging, and the fine structure of the sample cannot be resolved, so that the further application of the THz imaging is limited to a great extent. Therefore, it is urgently needed to develop a THz microscopic imaging technology and obtain the spatial resolution of nanometer level. Scattering scanning near-field optical microscopy imaging systems (s-SNOM) have become a powerful tool for studying semiconductor, plasma, biological, and dielectric systems at the nanoscale, and can achieve spatial resolution at the nanoscale in the visible to microwave range. And (3) performing near-field nano scanning imaging on the sample by using a scattering type near-field detection method and using an Atomic Force Microscope (AFM) nano probe. THz techniques can also be used in conjunction with s-SNOM to improve the spatial resolution of THz imaging. The THz nano probe is widely concerned as a key component of the s-SNOM, and the THz near-field scanning imaging cannot be well realized by utilizing a commercial AFM probe, so that the nano scanning probe suitable for the THz s-SNOM needs to be developed. A commercial THz nano probe is installed by adopting a method of electrochemical corrosion and manual flattening, a probe needle point is formed at the tail end of a tungsten filament by utilizing the electrochemical corrosion method, then the tungsten filament with the needle point and an appropriate length is cut out to be installed on a probe base, the tungsten filament except the needle point part is flattened by utilizing a mechanical flattening technology, and finally the flattened tungsten filament is installed on the base by utilizing a welding technology. The size error of the THz scanning probe tip manufactured by the method is larger, and can only be controlled to be about 25% generally, the influence on THz near-field imaging is huge, and as the length of the tip directly influences the coupling efficiency of the tip on THz near-field signals, most probes cannot obtain better THz near-field signals. International researchers developed terahertz nano scanning probe with controllable tip length by using Focused Ion Beam (FIB) etching and deposition method, firstly etching probe tip on metal block material by FIB technology, then etching off tip on commercial AFM probe cantilever by FIB technology and etching ring-shaped through hole on tail end, then etching tip on metal block material by FIB technology and vertically placing upper end of tip into through hole on tail end of AFM cantilever by nano transfer technology, finally splicing tip and cantilever by deposition technology. The method provides a more accurate method for manufacturing the THz nano scanning probe, but the steps for preparing the nano needle point on the metal block are more complicated, and the requirements on equipment and processing are higher. Therefore, it is necessary to design a new method for fabricating THz nano-scanning probe to solve the above-mentioned technical problems.
Disclosure of Invention
In view of this, the present invention aims to provide a terahertz nano near-field scanning probe and a method for fabricating the same, which are used to solve the problems of low yield, large error range, complex technology, high requirement for development process, and the like of the conventional THz nano scanning probe.
In order to achieve the purpose, the invention provides the following technical scheme:
a terahertz nanometer near-field scanning probe comprises a probe tip, a cantilever and a probe base; the needle tip is fixed on the probe base through a cantilever; the tail end of the cantilever is provided with a through hole for fixing the needle point.
The needle point is used for coupling THz radiation and localizing the THz at the tail end of the needle point, so as to realize THz near-field scanning of a sample;
the cantilever is used for connecting the probe tip and the probe base and driving the probe tip to vibrate up and down on the surface of the sample at a specific frequency, so that the probe works in a taping mode and modulation of a THz near-field signal is realized;
the probe base is used for connecting the probe and the mechanical scanning head, and the mechanical scanning head drives the probe to move so as to realize scanning imaging of the sample.
Preferably, the tip end diameter is less than 100nm and the taper angle is less than 10 °.
Preferably, the tip comprises a metal tip or a semiconductor tip.
Preferably, the metal needle tip is made of tungsten, gold or platinum iridium alloy, or a metal-plated film or a two-dimensional material film; the semiconductor needle tip is made of silicon or silicon dioxide, or a metal-plated thin film or a two-dimensional material thin film.
Preferably, the two-dimensional material comprises graphene, molybdenum disulfide, tin disulfide or the like.
Preferably, the cantilever comprises a metal cantilever or a semiconductor cantilever.
Preferably, the metal cantilever is made of tungsten, gold or platinum-iridium alloy; the semiconductor cantilever adopts silicon or silicon dioxide, or a metal-plated film or a two-dimensional material film.
Preferably, the probe mount comprises a plastic mount, a metal mount or a semiconductor mount.
Preferably, the plastic base is made of polyethylene or polypropylene and other plastics; the metal base is made of tungsten, gold or platinum-iridium alloy and other metal bases; the semiconductor base is a metal-plated thin film semiconductor base.
A manufacturing method of a terahertz nano near-field scanning probe specifically comprises the following steps:
1) preparing a probe tip part by using an electrochemical corrosion method, and forming a layer of nano-scale film on the surface of the probe tip by combining methods such as evaporation, chemical vapor deposition and the like;
2) etching a through hole with a specific radius at the tail end of the cantilever by using an FIB (focused ion beam) technology, and selecting a proper included angle between the through hole and the cantilever;
3) intercepting a needle point with a specific length from an electrochemical corrosion needle point by using an FIB technology, and putting the removed needle point into the cantilever through hole at a specific angle by using a mechanical transfer technology, so that the thicker end of the needle point is aligned with the bottom of the cantilever through hole;
4) and depositing metal on the contact part of the needle tip and the cantilever through hole by using a deposition technology to realize the connection of the needle tip and the cantilever.
The invention has the beneficial effects that:
1) the probe manufacturing method of the invention combines the electrochemical corrosion and the FIB technology, realizes the accurate control of the length of the probe tip and reduces the error range.
2) The electrochemical corrosion and FIB process adopted by the probe manufacturing method has good repeatability and operability, the yield of the probe is improved, and the probe development process is simplified.
3) Compared with the existing probe, the terahertz near field coupling efficiency of the probe is higher.
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 structural view of a 90 degree nanometer scanning probe according to the present invention;
FIG. 2 is a schematic structural diagram of a non-90 degree nanometer scanning probe according to the present invention;
FIG. 3 is a tip SEM image of a THz nano-scanning probe;
FIG. 4 is a schematic diagram of a THz s-SNOM device fabricated using the probe of the present invention;
fig. 5 shows an AFM image and a THz near-field image obtained by scanning a semiconductor sample with the THz nano-scanning probe of the present invention, where fig. 5(a) shows the AFM image and fig. 5(b) shows the THz near-field image.
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 the drawings provided in the following embodiments are only for illustrating the basic idea of the present invention in a schematic way, and the features in the following embodiments and examples may be combined with each other without conflict.
Wherein the showings are for the purpose of illustrating the invention only and not for the purpose of limiting the same, and in which there is shown by way of illustration only and not in the drawings in which there is no intention to limit the invention thereto; to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there is an orientation or positional relationship indicated by terms such as "upper", "lower", "left", "right", "front", "rear", etc., based on the orientation or positional relationship shown in the drawings, it is only for convenience of description and simplification of description, but it is not an indication or suggestion that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes, and are not to be construed as limiting the present invention, and the specific meaning of the terms may be understood by those skilled in the art according to specific situations.
Example 1:
the present embodiment provides a terahertz nano near-field scanning probe, as shown in fig. 1, the scanning probe includes: the probe comprises a probe tip, a cantilever and a probe base, wherein an included angle between the through hole and the cantilever is about 90 degrees. The manufacturing method of the scanning probe is a manufacturing method of a THz nano scanning probe combining electrochemical corrosion and FIB, and specifically comprises the following steps:
1) the method comprises the steps of preparing a probe needle tip part by an electrochemical corrosion method, building an electrochemical corrosion device by using NaOH solution, an adjustable voltage source, an experimental platform and the like, putting a part of metal tungsten wires into NAOH solution, applying voltage to two ends of each metal tungsten wire, adjusting the voltage from large to small, reasonably controlling the electrifying time length, enabling the tungsten wires to generate electrochemical corrosion at an NAOH dissolving page and form a conical needle tip, wherein the diameter of the tail end of the needle tip is smaller than 100nm, and the cone angle is smaller than 10 degrees.
2) Etching a through hole with the radius of about 14 mu m at the tail end of the cantilever by using an FIB (focused ion beam) technology, wherein the included angle between the through hole and the cantilever is about 90 degrees;
3) intercepting a needle point with the length of about 80 mu m from the electrochemical corrosion needle point by using an FIB technology, putting the removed needle point into the cantilever through hole in a direction parallel to the axial direction of the through hole by using a mechanical transfer technology, and aligning the thicker end of the needle point with the bottom of the cantilever through hole;
4) and depositing metal Pt on the contact part of the needle tip and the cantilever through hole by using a deposition technology to realize the connection of the needle tip and the cantilever.
Example 2:
the present embodiment provides a terahertz nano near-field scanning probe, as shown in fig. 2, the scanning probe includes: the probe comprises a probe tip, a cantilever and a probe base, wherein an included angle between the through hole and the cantilever is about 120 degrees. The manufacturing method of the scanning probe is a manufacturing method of a THz nano scanning probe combining electrochemical corrosion and FIB, and specifically comprises the following steps:
1) the method comprises the steps of preparing a probe tip part by an electrochemical corrosion method, building an electrochemical corrosion device by utilizing a mixed solution of CaCl2 and HCl, an adjustable voltage source, an experimental platform and the like, putting a part of Pt-Ir wire into the mixed solution, applying voltage to two ends of the Pt-Ir wire, adjusting the voltage from large to small, reasonably controlling the electrifying time length, enabling the tungsten wire to be subjected to electrochemical corrosion at a mixed dissolving page and form a conical tip, wherein the diameter of the tail end of the tip is smaller than 100nm, and the cone angle is smaller than 10 degrees.
2) Etching a through hole with the radius of about 18 mu m at the tail end of the cantilever by using an FIB (focused ion beam) technology, wherein the included angle between the through hole and the cantilever is about 120 degrees;
3) cutting off a needle point with the length of about 100 mu m from the electrochemical corrosion needle point by using an FIB technology, putting the taken-off needle point into the cantilever through hole in a direction parallel to the axial direction of the through hole by using a mechanical transfer technology, and aligning the thicker end of the needle point with the bottom of the cantilever through hole;
4) and depositing metal Pt on the contact part of the needle tip and the cantilever through hole by using a deposition technology to realize the connection of the needle tip and the cantilever.
Probe performance comparison experiment:
(1) probe performance characterization tool: scanning Electron Microscope (SEM), terahertz scattering scanning near-field optical microscope (THz s-SNOM);
(2) the probe performance characterization method comprises the following steps:
1) and performing morphology characterization on the prepared THz nano scanning near-field detection by using an SEM (scanning Electron microscope), wherein an SEM (scanning Electron microscope) morphology image of a probe tip is shown in FIG. 3.
2) The imaging performance of the prepared probe is characterized by utilizing THz s-SNOM equipment (shown in figure 4), the imaging result is shown in figure 5, figure 5(a) is an atomic force image, and figure 5(b) is a THz near field image.
As can be seen from FIG. 5, the probe provided by the invention has a good imaging effect when applied to a terahertz imaging system.
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 (9)

1. A terahertz nanometer near-field scanning probe is characterized by comprising a probe tip, a cantilever and a probe base; the needle tip is fixed on the probe base through a cantilever; the tail end of the cantilever is provided with a through hole for fixing the needle point.
2. The terahertz nano near-field scanning probe of claim 1, wherein the tip end diameter is less than 100 nm.
3. The terahertz nano-near-field scanning probe of claim 1 or 2, wherein the tip comprises a metal tip or a semiconductor tip.
4. The terahertz nanometer near-field scanning probe of claim 3, wherein the metal tip is made of tungsten, gold or platinum iridium alloy, or a metal-plated film or a two-dimensional material film; the semiconductor needle tip is made of silicon or silicon dioxide, or a metal-plated thin film or a two-dimensional material thin film.
5. The terahertz nano-near-field scanning probe of claim 4, wherein the two-dimensional material comprises graphene, molybdenum disulfide, or tin disulfide.
6. The terahertz nano-near-field scanning probe of claim 1, wherein the cantilever comprises a semiconductor cantilever or a metal cantilever; the semiconductor cantilever adopts a semiconductor of silicon or silicon dioxide or a semiconductor with a metal film; the metal cantilever is made of tungsten, gold and platinum-iridium alloy metal.
7. The terahertz nano-near-field scanning probe of claim 1, wherein the probe mount comprises a plastic mount, a metal mount, or a semiconductor mount.
8. The terahertz nano near-field scanning probe of claim 7, wherein the plastic base is made of polyethylene or polypropylene; the metal base is a tungsten, gold or platinum-iridium alloy metal base; the semiconductor base is a metal-plated thin film semiconductor base.
9. A method for manufacturing a terahertz nano near-field scanning probe is characterized by comprising the following steps:
1) preparing a probe needle tip part by using an electrochemical corrosion method, and forming a layer of nano-scale film on the surface of the needle tip by combining evaporation and chemical vapor deposition methods;
2) etching a through hole with a specific radius at the tail end of the cantilever by using an FIB (focused ion beam) technology, and selecting a proper included angle between the through hole and the cantilever;
3) intercepting a needle point with a specific length from an electrochemical corrosion needle point by using an FIB technology, and putting the removed needle point into the cantilever through hole at a specific angle by using a mechanical transfer technology, so that the thicker end of the needle point is aligned with the bottom of the cantilever through hole;
4) and depositing metal on the contact part of the needle tip and the cantilever through hole by using a deposition technology to realize the connection of the needle tip and the cantilever.
CN202111003715.9A 2021-08-30 2021-08-30 Terahertz nano near-field scanning probe and manufacturing method thereof Pending CN113607977A (en)

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