阅读说明：本技术 低品质因子微悬臂探针、其制备方法及显微镜 (Low-quality factor micro-cantilever probe, preparation method thereof and microscope ) 是由 戴庆 胡德波 赵九州 罗成 吴晨晨 于 2021-08-06 设计创作，主要内容包括：本发明提供了一种低品质因子微悬臂探针,所述低品质因子微悬臂探针为AM-AFM和/或SNOM微悬臂探针。还提供了低品质因子微悬臂探针的制备方法及显微镜。本发明利用微加工手段在微悬臂探针的悬臂梁上加工微纳结构,引入结构缺陷,增大微悬臂探针的本征能量耗散速率,降低其品质因子Q,能有效提高AM-AFM及SNOM在真空环境中的成像速率。(The invention provides a low-quality factor micro-cantilever probe, which is an AM-AFM and/or SNOM micro-cantilever probe. Also provides a preparation method of the low-quality factor microcantilever probe and a microscope. According to the invention, a micro-nano structure is processed on the cantilever beam of the micro-cantilever probe by a micro-processing method, the structural defect is introduced, the intrinsic energy dissipation rate of the micro-cantilever probe is increased, the quality factor Q of the micro-cantilever probe is reduced, and the imaging rate of the AM-AFM and the SNOM in a vacuum environment can be effectively improved.)

1. A low-quality factor micro-cantilever probe is characterized in that the low-quality factor micro-cantilever probe is an AM-AFM and/or SNOM micro-cantilever probe;

preferably, the AM-AFM and/or SNOM is vacuum AM-AFM and/or vacuum-low temperature SNOM; and/or

Preferably, the raw materials of the micro-cantilever probe are as follows: bulk probes or whole wafers not singulated.

2. The low quality factor microcantilever probe of claim 1, wherein,

the amplitude response time of the micro-cantilever probe is a key factor for limiting the AM-AFM and SNOM imaging rates, and is obtained by the following formula:

wherein Q is the quality factor of the microcantilever probe, omega₀Is the natural angular frequency of the probe;

preferably, the quality factor Q of the microcantilever probe determines the imaging rate of AM-AFM and SNOM;

more preferably, the quality factor Q of the microcantilever probe is dependent on the rate of dissipation of the vibrational energy of the microcantilever probe;

further preferably, the faster the rate of dissipation of the vibrational energy of the microcantilever probe, the smaller the quality factor Q of the microcantilever probe.

3. The method for preparing a low-Q microcantilever probe according to claim 1 or 2, wherein the method comprises: processing a micro-nano structure on a cantilever beam of a micro-cantilever probe by utilizing a micro-processing technology, introducing structural defects, increasing the dissipation rate of the vibration energy of the micro-cantilever probe, and reducing the quality factor Q of the micro-cantilever probe, thereby obtaining the low-quality factor micro-cantilever probe;

preferably, the micro-processing technology is as follows: laser direct writing or focused ion beam etching; and/or

The micro-nano structure is selected from one or more of the following structures: through holes, blind holes, surface engraving and/or hollowed characters and lines.

4. The method of claim 3, wherein when the micro-fabrication process is laser direct writing, the process comprises the steps of:

(1) designing a processing drawing, and transmitting the drawing to a laser processing control system;

(2) horizontally placing a probe to be processed into a processing table and fixing the probe, and adjusting the horizontal and vertical positions of the probe through a displacement table to enable a cantilever beam to be processed to align with a cross wire of a microscope;

(3) the machining is started after adjusting the laser machining typical parameters of the laser.

5. The method for preparing the microcantilever probe according to claim 3 or 4, wherein in the step (1), the software used in the design processing drawing is selected from one or more of the following: CAD, Soildworks, CAXA.

6. The method for preparing a microcantilever probe according to any of claims 3-5, wherein in step (3), the laser processing typical parameters include: laser wavelength, repetition frequency, power, scanning speed and scanning times; wherein the content of the first and second substances,

the laser wavelength is 355 nm;

the repetition frequency is 30-50kHz, preferably 30-45kHz, more preferably 35-45kHz, and most preferably 40 kHz;

the power is 10-30W, preferably 10-25W, more preferably 10-20W, most preferably 15W;

the scanning speed is 100-400mm/s, preferably 100-300mm/s, more preferably 100-250mm/s, and most preferably 200 mm/s; and/or

The number of scans is 1-3, preferably 1-2, most preferably 1.

7. The method of any of claims 3 to 6, wherein when the micro-fabrication process is focused ion beam etching, the process comprises the steps of:

(1) designing an etching layout;

(2) importing the layout into a focused ion beam control system, and setting the length and width of an etching pattern in the control system;

(3) fixing a probe to be processed on a sample table etched by an ion beam by using a conductive adhesive, and adjusting the horizontal position of the probe by using a displacement table;

(4) setting typical parameters of focused ion beam etching, adjusting the surface of the sample to the focal plane of the ion beam, and starting etching.

8. The method for preparing a microcantilever probe according to any one of claims 3 to 7, wherein:

in the step (2), the length of the graph is 60-150um, preferably 80-120 um; the width of the pattern is 10-60um, preferably 20-40 um; and/or

In the step (3), the conductive adhesive is: carbon conductive adhesive-or copper tape.

9. The method for preparing the micro-cantilever probe according to any one of claims 3 to 8, wherein in the step (4), typical parameters of the focused ion beam etching include: etching voltage, etching beam current, etching depth and residence time; wherein the content of the first and second substances,

the etching voltage is 10-50kV, preferably 10-40kV, more preferably 20-40kV, and most preferably 30 kV;

the etching beam current is 5-30nA, preferably 5-25nA, more preferably 5-20nA, and most preferably 10 nA;

the etching depth is 100-400nm, preferably 100-300nm, more preferably 100-250nm, and most preferably 200 nm; and/or

The residence time is 0.1 to 4. mu.s, preferably 0.1 to 3. mu.s, more preferably 0.1 to 2. mu.s, most preferably 1. mu.s.

10. A microscope, characterized in that the microscope is an amplitude modulated atomic force microscope or a scanning near field optical microscope based on an amplitude modulated atomic force microscope and the mechanical sensing element of the microscope is a micro-cantilever probe prepared according to the method of any of claims 3 to 8 or a low quality factor micro-cantilever probe according to claim 1 or 2.

Technical Field

The invention belongs to the technical field of scanning probe microscopes, and particularly relates to a low-quality factor micro-cantilever probe and a preparation method thereof.

Background

The micro-cantilever probe is a mechanical sensing element of an Amplitude Modulation Atomic Force Microscope (AM-AFM). When the AM-AFM is operated, the micro-cantilever probe vibrates around its natural frequency, and its amplitude is maintained at a constant value by the closed-loop feedback control system by adjusting the distance between the probe tip and the sample in real time. And the shape information of the surface of the sample can be obtained by performing two-dimensional scanning on the surface of the sample by the probe tip. Meanwhile, the micro-cantilever probe is also an Optical sensing element of a Scanning Near-Field Optical Microscope (SNOM) based on an AM-AFM. When the probe vibrates, the distance between the tip of the probe and the sample changes periodically, and the near-field optical signal of the surface of the sample scattered by the probe tip is also modulated periodically. Since the dependence of the near-field optical signal intensity on the probe tip-sample surface spacing is non-linear, the near-field optical signal arriving at the photodetector contains higher harmonic components of the probe's vibration frequency. And the phase-locked amplifier is used for extracting the high-order harmonic signals, so that the near-field optical imaging of the surface of the sample can be realized.

In the AM-AFM and SNOM scanning imaging process, the amplitude of the micro-cantilever probe changes along with the change of the surface topography of the sample, and the controller implements feedback adjustment by sensing the amplitude change so as to maintain the amplitude of the probe at a set value. The time required for this feedback adjustment process is proportional to the quality factor Q of the microcantilever probe. In gas phase and liquid phase environments, larger medium damping is the main way for dissipating the vibration energy of the probe, and the Q value of the probe is smaller; in a vacuum environment, the probe has a larger Q value due to smaller intrinsic energy dissipation. In summary, to increase the imaging rate of AM-AFM and SNOM in vacuum environment, we must use micro-cantilever probe with low intrinsic quality factor.

Disclosure of Invention

Therefore, the present invention is directed to overcoming the drawbacks of the prior art, and providing a low quality factor microcantilever probe and a method for fabricating the same, which is directed to the requirement of increasing the scanning imaging rate of vacuum AM-AFM and vacuum-low temperature SNOM.

Before setting forth the context of the present invention, the terms used herein are defined as follows:

the term "AM-AFM" means: amplitude modulation atomic force microscope.

The term "SNOM" refers to: a scanning near-field optical microscope based on an amplitude modulation atomic force microscope.

To achieve the above object, a first aspect of the present invention provides a low quality factor microcantilever probe, which is an AM-AFM and/or SNOM microcantilever probe;

preferably, the AM-AFM and/or SNOM is vacuum AM-AFM and/or vacuum-low temperature SNOM; and/or

Preferably, the raw materials of the micro-cantilever probe are as follows: bulk probes or whole wafers not singulated.

The low quality factor microcantilever probe according to the first aspect of the present invention, wherein the amplitude response time of the microcantilever probe is a key factor limiting the AM-AFM and SNOM imaging rates, and the response time of the microcantilever probe amplitude is given by the following formula:

wherein Q is the quality factor of the microcantilever probe, omega₀Is the natural angular frequency of the probe;

preferably, the quality factor Q of the microcantilever probe determines the imaging rate of AM-AFM and SNOM; and/or

More preferably, the quality factor Q of the microcantilever probe is dependent on the rate of dissipation of the vibrational energy of the microcantilever probe;

further preferably, the faster the rate of dissipation of the vibrational energy of the microcantilever probe, the smaller the quality factor Q of the microcantilever probe.

The second aspect of the present invention provides a method for preparing the low quality factor microcantilever probe of the first aspect, wherein the method comprises: processing a micro-nano structure on a cantilever beam of a micro-cantilever probe by utilizing a micro-processing technology, introducing structural defects, increasing the dissipation rate of the vibration energy of the micro-cantilever probe, and reducing the quality factor Q of the micro-cantilever probe, thereby obtaining the low-quality factor micro-cantilever probe;

preferably, the micro-processing technology is as follows: laser direct writing or focused ion beam etching; and/or

The micro-nano structure is selected from one or more of the following structures: through holes, blind holes, surface engraving and/or hollowed characters and lines.

The manufacturing method according to the second aspect of the invention, wherein, when the micromachining process is laser direct writing, the process includes the steps of:

(1) designing a processing drawing, and transmitting the drawing to a laser processing control system;

(2) horizontally placing a probe to be processed into a processing table and fixing the probe, and adjusting the horizontal and vertical positions of the probe through a displacement table to enable a cantilever beam to be processed to align with a cross wire of a microscope;

(3) the machining is started after adjusting the laser machining typical parameters of the laser.

The preparation method according to the second aspect of the present invention, wherein, in the step (1), the software used for designing the processing drawing is selected from one or more of the following: CAD, Soildworks, CAXA.

The production method according to the second aspect of the present invention, wherein, in the step (3), the laser processing typical parameters include: laser wavelength, repetition frequency, power, scanning speed and scanning times; wherein the content of the first and second substances,

the laser wavelength is 355 nm;

the repetition frequency is 30-50kHz, preferably 30-45kHz, more preferably 35-45kHz, and most preferably 40 kHz;

the power is 10-30W, preferably 10-25W, more preferably 10-20W, most preferably 15W;

the scanning speed is 100-400mm/s, preferably 100-300mm/s, more preferably 100-250mm/s, and most preferably 200 mm/s; and/or

The number of scans is 1-3, preferably 1-2, most preferably 1.

According to the second aspect of the present invention, when the micromachining process is focused ion beam etching, the process includes the steps of:

(1) designing an etching layout;

(2) importing the layout into a focused ion beam control system, and setting the length and width of an etching pattern in the control system;

(3) fixing a probe to be processed on a sample table etched by an ion beam by using a conductive adhesive, and adjusting the horizontal position of the probe by using a displacement table;

(4) setting typical parameters of focused ion beam etching, adjusting the surface of the sample to the focal plane of the ion beam, and starting etching.

The production method according to the second aspect of the present invention, wherein, in the step (2), the length of the pattern is 60 to 150um, preferably 80 to 120 um; the width of the pattern is 10-60um, preferably 20-40 um; and/or

In the step (3), the conductive adhesive is: carbon tape or copper tape.

The preparation method according to the second aspect of the present invention, wherein, in the step (4), typical parameters of the focused ion beam etching include: etching voltage, etching beam current, etching depth and residence time; wherein the content of the first and second substances,

the etching voltage is 10-50kV, preferably 10-40kV, more preferably 20-40kV, and most preferably 30 kV;

the etching beam current is 5-30nA, preferably 5-25nA, more preferably 5-20nA, and most preferably 10 nA;

the etching depth is 100-400nm, preferably 100-300nm, more preferably 100-250nm, and most preferably 200 nm; and/or

The residence time is 0.1 to 4. mu.s, preferably 0.1 to 3. mu.s, more preferably 0.1 to 2. mu.s, most preferably 1. mu.s.

A third aspect of the invention provides a microscope which is an amplitude modulation atomic force microscope or a scanning near-field optical microscope based on an amplitude modulation atomic force microscope, and the mechanical sensing element of the microscope is the low-quality-factor micro-cantilever probe prepared according to the method of the second aspect or the low-quality-factor micro-cantilever probe according to the first aspect.

The invention aims to provide a method for increasing the intrinsic energy dissipation rate of a micro-cantilever probe and preparing a low-quality factor probe by introducing structural defects on a cantilever beam of the micro-cantilever probe through a micro-machining means aiming at the requirement of improving the scanning imaging rate of a vacuum AM-AFM and a vacuum-low temperature SNOM.

The principle of the invention is that micro-nano structures (through holes, blind holes, surface engraving and/or hollowed characters, lines or other arbitrary figures) are processed on a cantilever Beam of a micro-cantilever probe by utilizing micro-processing means such as laser direct writing, Focused Ion Beam etching (FIB) and the like, structural defects are introduced, the intrinsic energy dissipation rate of the micro-cantilever probe is increased, and the quality factor Q of the micro-cantilever probe is reduced.

According to a specific embodiment of the present invention, a method for fabricating a low quality factor probe by introducing structural defects on a microcantilever probe cantilever by micromachining means to increase the intrinsic energy dissipation rate of the microcantilever probe is provided.

The raw material used by the invention is an AM-AFM or SNOM microcantilever probe. Either bulk probes or whole wafers that are not singulated.

Specifically, since the response rate of the circuit part in the feedback loop is much larger than that of the mechanical part, the dynamic response time of the microcantilever probe becomes a key factor limiting the AM-AFM and SNOM imaging rates. The response time of the microcantilever probe amplitude is given by,

wherein Q is the Quality Factor (Q) of the probe, ω₀Is the natural angular frequency of the probe. It can be seen that the Q value of the microcantilever probe determines the imaging rate of AM-AFM and SNOM. The Q value depends on the rate of dissipation of the probe vibrational energy: the faster the energy dissipation, the smaller the Q.

Specifically, when the micro-machining process is a laser direct writing process, the process steps are as follows:

(1) designing a processing drawing by using a CAD (computer aided design), and transmitting the drawing to a laser processing control system, wherein the micro-nano structure of the drawing is a through hole;

(2) horizontally placing a probe to be processed into a processing table and fixing the probe, and adjusting the horizontal and vertical positions of the probe through a displacement table to enable a cantilever beam to be processed to align with a cross wire of a microscope;

(3) the laser parameters were adjusted to start the process with a laser wavelength of 355nm, a repetition rate of 40kHz, a power of 15W and a scanning speed of 200 mm/s.

When the micro-processing technology is a focused ion beam etching technology, the processing steps are as follows:

(1) designing an etching layout, wherein the micro-nano structure of the layout is characters;

(2) importing the layout into a focused ion beam control system, and setting the length and width of an etching pattern in the control system;

(3) fixing a probe to be processed on a sample table etched by an ion beam by using a conductive adhesive, and adjusting the horizontal position of the probe by using a displacement table;

(4) setting working parameters of an ion beam, adjusting the surface of a sample to a focus plane of the ion beam, and starting etching, wherein the used etching voltage is 30kV, the etching beam current is 10nA, the etching depth is 200nm, and the retention time is 1 mu s.

The low quality factor microcantilever probes of the invention may have the following beneficial effects, but are not limited to:

1. the preparation method of the low-quality factor micro-cantilever probe provided by the invention can effectively reduce the Q value of the micro-cantilever probe.

2. The low-quality factor micro-cantilever probe prepared by the preparation method can effectively improve the imaging rate of the AM-AFM and the SNOM in a vacuum environment.

Drawings

Embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein:

fig. 1 shows a schematic diagram of a typical laser direct writing process in which a micro-nano structure is a through hole.

Fig. 2 shows a schematic diagram of a typical focused ion beam lithography process with a micro-nano structure as a character.

FIG. 3 shows a scanning electron micrograph of a low quality factor microcantilever probe; wherein FIG. 3A shows a scanning electron microscope image of a low quality factor microcantilever probe with a via ablated by a laser direct write process; FIG. 3B shows a scanning electron microscope image of a low quality factor microcantilever probe with text etched by focused ion beam etching.

FIG. 4 shows a comparison of Q-values before and after processing of a low quality factor microcantilever probe; wherein FIG. 4A shows a Q-value comparison of a low quality factor microcantilever probe processed by a laser direct write process; figure 4B shows a Q-value comparison of a low quality factor microcantilever probe processed by a focused ion beam etching process.

Detailed Description

The invention is further illustrated by the following specific examples, which, however, are to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

This section generally describes the materials used in the testing of the present invention, as well as the testing methods. Although many materials and methods of operation are known in the art for the purpose of carrying out the invention, the invention is nevertheless described herein in as detail as possible. It will be apparent to those skilled in the art that the materials and methods of operation used in the present invention are well within the skill of the art, provided that they are not specifically illustrated.

The reagents and instrumentation used in the following examples are as follows:

materials:

AFM microcantilever probes, model Arrow NCPt, were purchased from Nano World, Switzerland.

SNOM microcantilever probe, model Arrow NCPt, available from Nano World, Switzerland.

Conductive adhesive, available from SPI corporation, usa.

The instrument comprises the following steps:

a laser machining control system, available from Delong laser, Suzhou, model FP-D-DZS-001.

A focused ion beam control system, available from siemer fly electron microscope, usa, model Nova200 NanoLab.

Example 1

This example illustrates the method of the present invention for preparing a low-Q microcantilever probe by a laser direct writing process.

The method comprises the following specific steps:

(1) and designing a processing drawing by using a CAD (computer aided design), and transmitting the drawing to a laser processing control system, wherein the micro-nano structure of the drawing is a through hole.

(2) The probe to be processed is horizontally placed into a processing table and fixed, and the horizontal and vertical positions of the probe are adjusted through a displacement table, so that the cantilever beam to be processed is aligned with the cross-shaped wire of the microscope.

(3) And (3) according to the typical laser processing parameters in the table 1, adjusting the laser processing parameters of a laser and then processing to obtain the low-quality-factor micro-cantilever probe.

TABLE 1 laser machining typical parameters

Laser wavelength	355nm
		Repetition frequency	40kHz
Power of	15W
		Scanning speed	200mm/s
Number of scans	1 time of

As shown in fig. 3A, fig. 3A shows a scanning electron microscope image of a low quality factor microcantilever probe with a via ablated by a laser direct write process.

Example 2

This example is used to illustrate the method for preparing the low-q microcantilever probe by focused ion beam etching process.

The method comprises the following specific steps:

(1) and designing an etching layout by using Photoshop software, wherein the micro-nano structure of the layout is characters.

(2) And (3) guiding the layout into a focused ion beam control system, and setting the size of an etching graph in the control system, wherein the length is 100um and the width is 30 um.

(3) Fixing the probe to be processed on a sample table etched by the ion beam by using carbon conductive adhesive, and adjusting the horizontal position of the probe by using a displacement table.

(4) Working parameters are set according to typical parameters of focused ion beam etching processing in the table 2, the surface of the sample is adjusted to the focusing surface of the ion beam, and etching is started.

TABLE 2 typical parameters for focused ion beam etching process

Etching voltage	30kV
		Etching beam current	10nA
Depth of etching	200nm
		Residence time	1μs

As shown in fig. 3B, fig. 3B shows a scanning electron microscope image of a low quality factor microcantilever probe with text etched by focused ion beam etching.

Test example 1

This test example was used to test the quality factor Q value of the microcantilever probe of the low quality factor microcantilever probe of the present invention.

The method comprises the following specific steps:

(1) the microcantilever probe of low quality factor in example 1 was placed in a vacuum-low temperature environment (P ═ 2.0 × 10) before laser direct writing^-6Pa, T ═ 90K) for Q value; after laser direct writing, the substrate was placed in a vacuum-low temperature environment (P ═ 2.0 × 10)^-6Pa, T ═ 90K) for Q value; the test results are shown in fig. 4A.

(2) The low quality factor microcantilever probe prepared in example 2 was placed in a vacuum-low temperature environment (P ═ 2.0 × 10) before being etched by focused ion beam^-6Pa, T ═ 90K) for Q value; after being etched by focused ion beams, the silicon wafer is put into a vacuum-low temperature environment (P is 2.0 multiplied by 10 < -6 > Pa, T is 90K) to test the Q value; the test results are shown in fig. 4B.

As can be seen from the measured data and the graphs in FIGS. 4A and 4B, the low-quality factor microcantilever probe manufactured by the laser processing and focused ion beam etching methods provided by the invention can effectively reduce the Q value of the microcantilever probe.

Although the present invention has been described to a certain extent, it is apparent that appropriate changes in the respective conditions may be made without departing from the spirit and scope of the present invention. It is to be understood that the invention is not limited to the described embodiments, but is to be accorded the scope consistent with the claims, including equivalents of each element described.