Near-field scanning microscopic probe and scanning system

Abstract

The invention discloses a near-field scanning microprobe and a scanning system, and relates to the field of near-field scanning microimaging, and the near-field scanning microprobe comprises a probe head which is in the shape of an inclined rectangular pyramid, one side of the probe head is provided with a resistor disc, and the other side of the probe head is provided with a metal film layer; the resistor disc is used for heating the metal film layer, and the metal film layer is used for thermally exciting and scattering near-field thermal radiation signals; one end of the cantilever beam is fixedly connected with the end part of the probe head; and an electrode is arranged on one side of the cantilever beam and is connected with the resistor disc. According to the probe, a resistor heating function is built in, a local high-temperature area can be generated at the tip of the probe and used for exciting and scattering near-field evanescent waves, external laser excitation is not needed, the diffraction limit is overcome, meanwhile, the complexity of a system can be reduced by using the probe, meanwhile, the signal-to-noise ratio of a detection signal can be increased, and wide-spectrum measurement is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of near-field scanning microscopic imaging, in particular to a near-field scanning microscopic probe and a scanning system. Background Art

[0002] As the exploration of the microscopic world continues to deepen, the resolution capability of traditional optical microscopes is limited by the optical diffraction limit, which has become the main obstacle to further improving imaging resolution. In order to break through this limit, the development of microscopic technology that can achieve high-precision imaging at the nanoscale has gradually become the focus of scientific research. In the past century, the emergence of a variety of high-resolution measurement equipment such as scanning probe microscopes and scanning electron microscopes has promoted the development of nanotechnology. However, many non-optical measurement technologies are prone to damage to samples in practical applications and cannot obtain super-resolution images at the optical level, which has given rise to the emergence of near-field optical microscopes.

[0003] Near-field optical microscopes can excite and scatter evanescent waves on the surface of samples, break through the optical diffraction limit, and achieve high-resolution measurement at the nanoscale. At present, common probes are mainly divided into probes with holes and probes without holes. The spatial resolution of the measurement that can be achieved by the probe with holes is lower than that of the probe without holes due to the presence of a light-through hole inside it. For the probe without holes, the measurement resolution is mainly limited by the size of the probe tip, and its working process is heavily dependent on the excitation of the external incident laser. Therefore, it is usually necessary to adopt complex noise reduction technology to improve the imaging quality, and the measurement process is complicated and cumbersome. In addition, the external laser also seriously affects the intensity and band of the detection signal. Usually, a system is equipped with multiple lasers to achieve wide-band measurement. The present invention proposes a self-heating scattering type near-field scanning microprobe that does not require external light source excitation, which can achieve only heating and excitation of the probe tip and scattering of the evanescent wave on the sample surface. While reducing the complexity of the system, it can also achieve high resolution, high signal-to-noise ratio and wide spectral measurement. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present invention is proposed.

[0005] Therefore, the problem to be solved by the present invention is that the existing probe microscope measurement means are complicated or the resolution is limited by the size of the probe tip and relies on the excitation of external incident laser.

[0006] In order to solve the above technical problems, in the first aspect, the present invention provides the following technical solutions: a near-field scanning microprobe, comprising a probe head in the shape of an oblique quadrangular pyramid, a resistor sheet disposed on one side thereof, and a metal film layer disposed on the other side thereof; the resistor sheet is used to heat the metal film layer, and the metal film layer is used to thermally excite and scatter near-field thermal radiation signals;

[0007] A cantilever beam has one end fixedly connected to the end of the probe head; an electrode is arranged on one side of the cantilever beam, and the electrode is connected to the resistor.

[0008] As a preferred solution of the near-field scanning microprobe of the present invention, the resistor sheet includes a first resistor sheet and a second resistor sheet, the cross-sectional areas of both resistor sheets gradually decrease from one end to the other end of each resistor sheet and the two resistor sheets are connected at the tip.

[0009] As a preferred solution of the near-field scanning microprobe described in the present invention, wherein: a groove is opened on one side of the cantilever beam along its length direction, the electrode is arranged in the groove and the electrode includes a first electrode and a second electrode, the first electrode is connected to the first resistor sheet, and the second electrode is connected to the second resistor sheet.

[0010] As a preferred solution of the near-field scanning microprobe of the present invention, the angle between the probe head and the cantilever beam is 60° to 80°.

[0011] As a preferred solution of the near-field scanning microscopy probe of the present invention, the tip diameter of the probe head is 5 to 100 nm.

[0012] As a preferred solution of the near-field scanning microprobe of the present invention, the material of the cantilever beam is doped silicon or SiN x .

[0013] As a preferred solution of the near-field scanning microprobe of the present invention, the material of the resistor is one or more of palladium, platinum, silver, tungsten, nickel, copper and chromium.

[0014] As a preferred solution of the near-field scanning microprobe of the present invention, the thickness of the resistor sheet is 10-40 nm.

[0015] As a preferred solution of the near-field scanning microprobe of the present invention, the thickness of the metal film layer is 20-50 nm.

[0016] On the other hand, the present invention also provides a near-field scanning system, which includes the above-mentioned near-field scanning microprobe, and also includes a bridge module and a feedback signal processing module, the bridge module is electrically connected to the electrode, and the feedback signal processing module is electrically connected to the feedback signal processing module.

[0017] The beneficial effects of the present invention are as follows: the probe of the present invention has a built-in resistance heating function, which can generate a local high-temperature area at the tip of the probe for the excitation and scattering of near-field evanescent waves, without the need for an external excitation laser. While overcoming the diffraction limit, the use of the probe can reduce the complexity of the system, while also improving the signal-to-noise ratio of the detection signal and achieving wide-spectrum measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 Scene diagram of the near-field scanning microprobe.

[0020] Figure 2 This is a diagram of the structure of the near-field scanning microprobe.

[0021] Figure 3 This is the structural diagram of the first support unit of the near-field scanning microprobe.

[0022] Figure 4 Another perspective view of the first support unit of the near-field scanning microprobe.

[0023] Figure 5 This is the structural diagram of the second support unit of the near-field scanning microprobe.

[0024] Figure 6 Another perspective view of the second support unit of the near-field scanning microprobe. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings.

[0026] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0027] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it an embodiment that is mutually exclusive with other embodiments, either individually or selectively.

[0028] Example 1

[0029] Reference Figure 1 and Figure 2, which is the first embodiment of the present invention, provides a near-field scanning microprobe. The near-field scanning microprobe includes a probe head 100 and a cantilever beam 200 .

[0030] Specifically, the probe head 100 is in the shape of an oblique quadrangular pyramid, and a resistor 200 and a metal film layer 500 are respectively arranged on opposite sides of the probe head 100. The shapes of the resistor 200 and the metal film layer 500 are matched with the shape of the probe head 100, that is, the cross-sections of the shapes of the two gradually decrease from one end to the other end. When the resistor 200 is powered on, the probe head 100 is heated, and the metal film layer 500 on the other side is heated to thermally excite and scatter near-field thermal radiation signals.

[0031] The cantilever beam 300 is in the shape of a long strip, one end of which is pointed and fixedly connected to the wide end of the probe head 100. There is a certain angle between the probe head 100 and the cantilever beam 300. An electrode 400 is provided on one side of the cantilever beam 300, and the electrode 400 is connected to the resistor 200 for energizing the resistor 200.

[0032] When in use, the near-field scanning microprobe is installed on an atomic force microscope with a spectral signal collection and probe temperature control module; when measuring the sample 600, the temperature of the probe head 100 is first controlled to a specified value through the temperature control module, and a local temperature field is generated at the tip of the probe head 100. The local temperature field replaces the laser spot in the traditional near-field optical microscope.

[0033] The metal film layer 500 on the back side of the tip of the probe head 100 can excite the local surface plasmon resonance enhancement when heated. By interacting with the sample 600, the near-field thermal radiation evanescent wave on the surface of the sample 600 is scattered to the far field, and the near-field signal is obtained by a spectral receiving device and post-processing arranged at the far end, thereby realizing the measurement and collection of the near-field thermal radiation evanescent wave on the sample surface and breaking through the optical diffraction limit.

[0034] Example 2

[0035] Reference Figure 1 to Figure 4 , which is the second embodiment of the present invention, and this embodiment is based on the previous embodiment.

[0036] Specifically, the angle between the probe head 100 and the cantilever beam 300 is 60° to 80°.

[0037] The metal film layer 500 has a thickness of 20-50 nm and is made of gold. It is formed by deposition and is used for thermal excitation and scattering of near-field thermal radiation signals.

[0038] The resistor 200 includes a first resistor 201 and a second resistor 202, which are symmetrically arranged on the other side of the probe head 100 relative to the metal film layer 500. The first resistor 201 and the second resistor 202 have the same shape, which is triangular, and the tips of the two are connected and located at the tip of the probe head 100. The thickness of the resistor 200 is 10-40nm, and the material is one or more of palladium (Pd), platinum (Pt), silver (Ag), tungsten (W), nickel (Ni), copper (Cu) and chromium (Cr). The contact point where the first resistor 201 and the second resistor 202 are connected has the largest resistance, and will be the point with the highest temperature after power is turned on. The local temperature that can be generated at the tip of the probe head 100 is 600-1200K. The resistor 200 is formed by micro-nano processing.

[0039] A groove 301 is also provided on one side of the cantilever beam 300 along its length direction, and the electrode 400 is disposed in the groove 301. The electrode 400 includes a first electrode 401 and a second electrode 402, wherein the first electrode 401 is connected to a wider end of the first resistor 201 at its end, and the second electrode 402 is connected to a wider end of the second resistor 202 at its end.

[0040] The groove 301 is formed by ion etching and has a depth of 300-500 nm. The groove 301 can eliminate the bending of the probe head 100 caused by thermal stress.

[0041] Preferably, the electrode 400 has a thickness of 20-100 nm, is made of gold, and is formed by metal lift-off and electron beam lithography. The electrode 400 is connected to an external circuit to control the current flowing through the probe head 100 .

[0042] Preferably, the tip diameter of the probe head 100 is 5-100 nm.

[0043] Preferably, the material of the cantilever beam 300 can be selected to be doped silicon or SiN x The thickness of the cantilever beam 300 is uniform, and the thickness thereof is the same as the depth of the groove 301 .

[0044] When in use, the self-heating near-field microprobe used to excite and scatter near-field optical signals is installed on an atomic force microscope with a near-field optical detection and probe temperature control module for testing the sample 600. Under the regulation of the external circuit, the tip of the probe head 100 is locally heated to a constant temperature of 600-1200K. When the needle tip and the sample 600 interact with each other, the near-field thermal radiation evanescent wave generated on the sample surface is excited by the needle tip and scattered and converted into a far-field signal 700, which is scattered to a remote signal processing system.

[0045] Example 3

[0046] Reference Figure 5 and Figure 6, which is the third embodiment of the present invention, and is based on the first two embodiments. This embodiment provides a near-field scanning system, comprising the near-field scanning microprobe described in Embodiment 1 and Embodiment 2, and also comprising a bridge module and a feedback signal processing module.

[0047] Specifically, the bridge module is electrically connected to the electrode 400, and the feedback signal processing module is electrically connected to the feedback signal processing module. The bridge module is a Wheatstone bridge.

[0048] The bridge module first adds a constant current to the probe to heat the probe head 100 to a constant temperature, and at the same time measures the voltage across the probe resistor 200. When the temperature of the probe head 100 reaches a stable state, the bridge is adjusted to reach a balance and then measurement begins. When the temperature of the probe head 100 changes, the bridge will detect the change in potential and feed back the change in potential to the feedback signal processing module. The feedback signal processing module will change the size of the probe current to return the probe temperature to a stable state.

[0049] Reference Figure 6 Different probe tip temperatures will result in different degrees of spectral signal enhancement. The higher the probe temperature, the stronger the obtained spectral signal and the higher the signal-to-noise ratio.

[0050] In summary, the present invention proposes a self-heating scattering type near-field scanning microprobe that does not require external light source excitation. The local temperature field formed by heating the probe tip replaces the traditional external incident laser spot, which can excite the probe's local surface plasmon resonance enhancement. Compared with the traditional external laser near-field microprobe, the proposed near-field microprobe based on self-heating of the probe tip has a wider band of excitation and scattering during use, which can reduce the complexity of the system while achieving wide-spectrum measurement. The heating of the probe tip amplifies the near-field signal scattered to the far field, greatly improving the signal-to-noise ratio of the detection. The near-field scanning microprobe of the present invention has the function of a near-field thermal scanning probe, and can measure the temperature and thermal conductivity of the sample surface in contact with an external control circuit. The diameter of the probe tip can reach 10nm, and ultra-high resolution measurements at the nanometer level can be performed, breaking through the optical diffraction limit.

[0051] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A near-field scanning microprobe, characterized in that: include, The probe head (100) is in the shape of an oblique quadrangular pyramid, with a resistor (200) provided on one side and a metal film layer (500) provided on the other side; the resistor (200) is used to heat the metal film layer (500), and the metal film layer (500) is used to thermally excite and scatter near-field thermal radiation signals; A cantilever beam (300) has one end fixedly connected to the end of the probe head (100); an electrode (400) is provided on one side of the cantilever beam (300), and the electrode (400) is connected to the resistor (200).

2. The near-field scanning microprobe according to claim 1, characterized in that: The resistor (200) comprises a first resistor (201) and a second resistor (202), the cross-sectional areas of both resistors gradually decrease from one end to the other end of each resistor, and the two resistors are connected at the tip.

3. The near-field scanning microprobe according to claim 2, characterized in that: A groove (301) is provided on one side of the cantilever beam (300) along its length direction, the electrode (400) is arranged in the groove (301), and the electrode (400) comprises a first electrode (401) and a second electrode (402), the first electrode (401) is connected to the first resistor (201), and the second electrode (402) is connected to the second resistor (202).

4. The near-field scanning microprobe according to any one of claims 1 to 3, characterized in that: The included angle between the probe head (100) and the cantilever beam (300) is 60° to 80°.

5. The near-field scanning microprobe according to claim 4, characterized in that: The tip diameter of the probe head (100) is 5 to 100 nm.

6. The near-field scanning microprobe according to claim 5, characterized in that: The material of the cantilever beam (300) is doped silicon or SiN x .

7. The near-field scanning microprobe according to claim 6, characterized in that: The material of the resistor (200) is one or more of palladium, platinum, silver, tungsten, nickel, copper and chromium.

8. The near-field scanning microprobe according to claim 7, characterized in that: The thickness of the resistor (200) is 10-40 nm.

9. The near-field scanning microprobe according to claim 8, characterized in that: The thickness of the metal film layer (500) is 20-50 nm.

10. A near-field scanning system, characterized in that: It comprises the near-field scanning microprobe as claimed in any one of claims 1 to 9, and also comprises a bridge module and a feedback signal processing module, wherein the bridge module is electrically connected to the electrode (400), and the feedback signal processing module is electrically connected to the feedback signal processing module.

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