CN211785621U - Sample structure - Google Patents
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- CN211785621U CN211785621U CN201922216397.9U CN201922216397U CN211785621U CN 211785621 U CN211785621 U CN 211785621U CN 201922216397 U CN201922216397 U CN 201922216397U CN 211785621 U CN211785621 U CN 211785621U
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Abstract
The present application provides a sample structure comprising a substrate, a metal film on the substrate, and a nanostructure within or on the metal film. The SNOM near-field optical field imaging device has the advantages that the structure of a sample is simple, the manufacturing method is simple, the generated near-field optical field distribution can be detected by the SNOM under the irradiation of oblique incident light, the SNOM near-field optical field imaging device has good response to an incident light space angle, the SNOM near-field optical field imaging device can be used for SNOM near-field optical field imaging, and then incident light space angle components are reversely deduced by SNOM near-field optical field imaging measurement results, so that the calibration of the incident.
Description
Technical Field
The utility model belongs to the technical field of nanometer optical measurement, especially, relate to a sample structure.
Background
Scattering Scanning Near-field optical microscopy (s-SNOM) is a Scanning probe-based optical super-resolution microscopy technique, which is mainly used for characterizing the Near-field optical field distribution in a micro-region (micron-nanometer level) on a sample. The basic principle is as follows: and (3) utilizing an AFM probe to focus and illuminate the laser beam, and exciting a nanoscale enhanced near-field signal area near the needle tip. When the tip is close to the sample surface, there will be a corresponding change in the near field optical information due to the difference in dielectric properties of the different substances. The acquired scattering signals are analyzed through the background suppression technology, and then the near-field optical field imaging of the surface of the sample can be acquired. The technology breaks through the limit of diffraction limit of the traditional optical imaging mechanism, can scan and image nanoscale near-field optical information on the surface of a sample, and is an important measuring tool in the development of nano science and technology.
When SNOM near-field optical field imaging measurement is carried out, a laser beam needs to be irradiated on a contact area between a probe tip and a sample to serve as an excitation light source, so that excitation and detection of a near-field optical field on the surface of the sample are achieved. For the scattering type SNOM system, the laser is mostly in oblique incidence in three-dimensional space, and the incidence angle is related to the SNOM optical path structure, sample requirements and other measurement conditions. The near-field signal of the sample is usually very sensitive to the incident light spatial angle, and even directly affects the distribution of the near-field light intensity and phase. Therefore, correct calibration of the spatial angle of the incident light is of great significance for calibrating and analyzing SNOM measurement results. However, since the SNOM optical path system is generally complex and has a compact spatial structure, an effective means for directly measuring and accurately calibrating the spatial angle of incident light is lacking.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model provides a sample structure to solve the problem that lacks the effective means of carrying out direct measurement and accurate demarcation to incident light space angle among the prior art.
In order to achieve the above object, the utility model provides a following technical scheme:
a sample structure for use in a reflectively illuminated scanning near-field optical microscope, the sample structure comprising:
a substrate;
a metal thin film on the substrate;
a nanostructure located within or on the metal film.
Preferably, the nanostructure is a single nano-slit which is positioned in the metal film and penetrates through the metal film, and a nano-groove which is positioned in the metal film and does not penetrate through the metal film; or nano-bosses located on the metal film.
Preferably, when the nanostructure is a nano-single slit located within the metal thin film, the nano-single slit has a length of 10 μm to 500 μm, inclusive; the width of the nanometer single slit is 100nm-1 μm, inclusive.
Preferably, the length of the nano single slit is 20 μm to 40 μm, inclusive; the width of the nanometer single slit is 100nm-200nm, including the endpoint value.
Preferably, the material of the metal thin film is gold, silver or copper.
Preferably, the metal thin film has a thickness of 10nm to 500nm, inclusive.
Preferably, the material of the substrate comprises a silicon wafer or a quartz wafer.
According to the above technical solution, the present invention provides a sample structure, which includes a substrate, a metal thin film on the substrate, and a nano structure inside or on the metal thin film. The SNOM near-field optical field imaging device has the advantages that the structure of the sample is simple, the manufacturing method is simple, the generated near-field optical field distribution can be detected by the SNOM under the irradiation of oblique incident light, the SNOM near-field optical field imaging device has good response to the spatial angle of the incident light, the SNOM near-field optical field imaging device can be used for SNOM near-field optical field imaging, and the incident light spatial angle component is reversely deduced by the SNOM near-field optical field imaging measurement result, so that the calibration of.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a sample provided in an embodiment of the present invention;
fig. 2 is a flowchart of a sample structure manufacturing method according to an embodiment of the present invention;
fig. 3 is a flowchart of a method for calibrating an incident light spatial angle of a scattering type scanning near-field optical microscope according to an embodiment of the present invention;
FIG. 4 is an SEM image of a single slit of actually processed nanometer;
fig. 5 and fig. 6 are schematic diagrams illustrating spatial angle representations of incident light provided by embodiments of the present invention;
FIG. 7 is a schematic diagram of the structure of a sample actually processed;
fig. 8 and 9 are SNOM near-field optical field imaging measurements of two differently oriented nano-single slits.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
The utility model provides a sample structure is for being used for demarcating scattering formula SNOM system, especially refers in particular to the sample structure of the incident light angle of reflective lighting mode's SNOM system, also is used for the demarcation technical field of SNOM incident light space angle, as shown in FIG. 1, FIG. 1 is the embodiment of the utility model provides a sample structure schematic diagram, the sample structure includes:
a substrate 2;
a metal thin film 1 on a substrate 2;
a nanostructure 4 located within the metal thin film 1 or on the metal thin film 1.
It should be noted that, in this embodiment, the specific material of the substrate is not limited, and the substrate is required to be hard, to have a supporting function, to have a smooth surface, to be non-conductive, and to be convenient for plating a metal film. The substrate may be a silicon wafer, a quartz wafer or similar hard substrate with a smooth surface.
In this embodiment, the material of the metal thin film is not limited, and the metal thin film is a metal capable of generating surface plasmons (SPPs) at the wavelength of incident light, such as gold, silver, and copper. The film thickness is 10nm to 500nm, inclusive. For incident light in the visible light band, such as at a wavelength of 633nm, the metal thin film is preferably a gold thin film, and the film thickness is preferably 50nm to 100nm, inclusive, in view of the excitation efficiency of SPPs and the stability of the thin film.
In this embodiment, the nano-structure is a micro-nano structure capable of efficiently generating SPPs under irradiation of incident laser. The size of the nano structure is matched with the wavelength of incident laser, so that the conditions for generating SPPs are met. In this embodiment, the specific shape of the nano-structure is not limited, and the nano-structure located on the metal film may be a nano-groove or a nano-wire structure obtained by etching the metal film; the nanostructure formed above the metal film, such as nano steps or protrusions, may also be produced by other processes.
Namely, the nano structure is a nano single seam which is positioned in the metal film and penetrates through the metal film, and a nano groove which is positioned in the metal film and does not penetrate through the metal film; or nano-bosses located on the metal film.
From the viewpoint of convenience of calculation and analysis, it is preferable in this embodiment that the nanostructure is a nano single slit structure penetrating the metal thin film. The length of the nanometer single slit is 10-500 mu m, the width is 100nm-1 mu m, and the depth is larger than or equal to the thickness of the metal film. In view of the easy search and measurement under the microscope field and the easy processing, the length is preferably 20 μm to 40 μm and the width is preferably 100nm to 200 nm. The above numerical ranges are inclusive of the endpoints.
Based on the sample structure, the present embodiment further provides a method for manufacturing the sample structure, as shown in fig. 2, the method for manufacturing the sample structure includes:
s101: providing a substrate;
s102: forming a metal film layer on the surface of the substrate;
s103: and processing the metal film layer to form a nano structure.
Specifically, the manufacturing method comprises the following steps: and depositing a layer of required metal film on the surface of the clean substrate in a magnetron sputtering coating mode, a vacuum thermal evaporation coating mode or an electron beam evaporation coating mode. And then processing a required micro-nano structure, such as a nano single slit structure, on the surface of the metal film by using focused ion beam etching or etching equipment with similar functions.
The embodiment of the utility model provides a sample structure and sample structure manufacturing method, because sample simple structure, preparation technology are also simple relatively, can regard as standard sample to mark the scattering type scanning near field optical microscope incident light angle of different producer models, application scope is extensive, but mass production.
Based on the same utility model discloses think, the utility model discloses still provide a scattering type scanning near field optical microscope incident light space angle calibration method, as shown in fig. 3, fig. 3 is the embodiment of the utility model provides a scattering type scanning near field optical microscope incident light space angle calibration method flow chart, calibration method includes:
s201: providing a sample structure as described in the above embodiments, the sample structure comprising nanostructures;
in this embodiment, the specific form of the nano structure is not limited, and the period of the interference fringes can be generated by any linear one-dimensional structure, regardless of the nano grooves, nano single peaks or nano steps, or nano bosses, so as to perform calculation and calibration.
S202: irradiating the nanostructure on the sample structure with oblique polarized light to generate surface plasmon polaritons;
s203: acquiring the interference fringe period of the surface plasmon polariton;
s204: and calculating to obtain an included angle between the incident light and the normal direction of the surface of the sample structure, and determining the spatial angle of the incident light.
That is, the incident light spatial angle calibration method for the scattering type scanning near-field optical microscope provided in the embodiment of the present invention is based on the sample structure provided in the above embodiment, please refer to fig. 1, and employs an AFM probe 5 to generate an incident laser beam 3 to irradiate a nano structure 4 on a sample; the specific structure of the nano-structure 4 is not limited in this embodiment, and the following description will be given by taking a nano single slit as an example to describe the specific steps of the incident light spatial angle calibration method for the scattering type scanning near-field optical microscope provided in the embodiment of the present invention. Referring to fig. 4, fig. 4 is a SEM image of the actually processed nano single slit.
As shown in FIGS. 5 and 6, the spatial angle of the incident light can be determined by θ and
in this case, θ is the angle between the incident light and the normal direction of the sample surface.
Is the included angle between the normal of the nanometer single slit and the incident plane.
For convenient measurement, a series of fixed angle deviations can be processed on the sample
The arranged nanometer single slits, as shown in fig. 7, can be measured by selecting two of the nanometer single slits in actual use. Because a coordinate system is required to be arranged in the subsequent calculation process, and the nano single slit can be used as a reference coordinate when being placed along the horizontal or vertical position, the calculated incident light space angle can be simplified, and the further conversion of the coordinate is avoided. Preferably, in this embodiment, one of the two selected single slits is disposed along a horizontal or vertical position in the plane of the sample surface. The distance between the adjacent single slits is 50-200 μm to ensure that the generated SPPs do not interfere with each other.
The SPPs can be efficiently excited by a nano single-slit structure (or similar micro-nano structures such as nano grooves, steps and the like) under the irradiation of oblique p-polarized light, and the wavelength of the SPPs is as follows:
wherein λ0In the wavelength of the incident light,ddielectric constant of medium (of air)d＝1)，mIs the complex dielectric constant of the metal.
SPPs generated by the nanometer single slit are transmitted to two sides of the single slit and interfere with the SPPs excited by the probe tip to form interference fringes. Because the propagation directions of the SPPs on two sides of the single slit are different relative to the direction of exciting the SPPs by the probe, the periods of the interference fringes generated on two sides of the single slit are also different, and can be expressed by the following formula:
wherein Λ-The period of interference fringe on one side of the incident light of the nanometer single slit, lambda+The fringe period on the other side. Theta is the angle between the incident light and the normal direction of the sample surface.
Is the included angle between the normal of the nanometer single slit and the incident plane. Theta and
together determine the spatial angle of the incident light. Under a certain SNOM optical path system, theta is the same for different nanometer single slits,
it is related to the placement direction of the single slit.
Therefore, if two different directions are measured separately (knowing the included angle between the two directions is
) The interference fringe period of the nanometer single slit on the incident light side
Then can be calculated
And the value of θ:
The spatial angle of the incident light can thus be determined.
Taking SNOM measurement of a laser light source with a wavelength of 633nm as an example, gold is selected as a metal coating material of a sample to be measured, the thickness of a film is 60nm, and a substrate is a silicon wafer. The length of the processed nano single slit is 20 mu m, the width is 200nm, and the depth is 60 nm. SPPs on gold film with wavelength of lambdaSPP＝604nm。
Two single slits are selected for SNOM near-field optical field imaging measurement, one slit (slit 1) is placed along the vertical direction in the plane of the sample surface, and the other slit (slit2) has a 25-degree difference with the angle. The measurement results are shown in fig. 8 and 9, and fig. 8 and 9 are the results of the SNOM near-field optical field imaging measurement of two nano single slits with different orientations (angle deviation 25 °) (the scanning direction is perpendicular to the single slit direction). Measured out of
Calculated as theta 57 deg.,
namely, the included angle between the incident light and the normal direction of the sample surface is 57 degrees, and the normal direction of the nano single slit 1 (namely the horizontal direction in the plane of the sample surface) isIs 39 deg., thereby defining the incident light spatial angle.
The embodiment of the utility model provides a scattering formula scanning near field optical microscope incident light space angle calibration method is based on the sample structure in above embodiment. And the incident light angle component is reversely deduced from the SNOM near-field optical field imaging measurement result, so that the calibration of the incident light space angle of the SNOM equipment is realized.
It should be noted that, in the present specification, the embodiments are all described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments may be referred to each other.
It is further noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in an article or device that comprises the element.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (6)
1. A sample structure for use in a reflectively illuminated scanning near-field optical microscope, the sample structure comprising:
a substrate;
a metal thin film on the substrate;
the nano structure is positioned in the metal film or on the metal film, and the nano structure is a nano single seam which is positioned in the metal film and penetrates through the metal film, and a nano groove which is positioned in the metal film and does not penetrate through the metal film; or nano-bosses located on the metal film.
2. The sample structure according to claim 1, characterized in that when the nanostructure is a nano-single slit located within the metal thin film, the nano-single slit has a length of 10 μ ι η -500 μ ι η, inclusive; the width of the nanometer single slit is 100nm-1 μm, inclusive.
3. The sample structure according to claim 2, characterized in that the nano-single slits have a length of 20 μ ι η -40 μ ι η, inclusive; the width of the nanometer single slit is 100nm-200nm, including the endpoint value.
4. The sample structure of claim 1, wherein the metal thin film is made of gold, silver or copper.
5. The sample structure according to claim 1, characterized in that the thickness of the metal thin film is 10nm-500nm, inclusive.
6. The sample structure of claim 1, wherein the substrate comprises a silicon wafer or a quartz wafer.
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| CN110927409A (en) * | 2019-12-11 | 2020-03-27 | 中国科学技术大学 | Sample structure, manufacturing method thereof and incident space angle calibration method |
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| CN110927409A (en) * | 2019-12-11 | 2020-03-27 | 中国科学技术大学 | Sample structure, manufacturing method thereof and incident space angle calibration method |
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