JP5043699B2 - Scanning probe microscope - Google Patents

Description

  The present invention relates to a scanning probe microscope suitable for observing a sample in a liquid.

  Recently, the cantilever with the probe and the sample are placed close to each other, and the surface of the sample is scanned with the probe to measure the atomic force, magnetic force, electrostatic force, etc. acting between the probe and the sample. A scanning probe microscope configured to obtain a concavo-convex image of the sample surface based on the measurement, a probe and the sample are placed close to each other, a bias voltage is applied between the probe and the sample, and the sample is detected by the probe. Attention has been focused on a scanning probe microscope which measures a tunnel current flowing between a probe and a sample by scanning the surface and obtains an uneven image on the sample surface based on the measurement.

  Now, in sample observation with such a scanning probe microscope, a sample in the liquid may be observed. At that time, if the sample can be observed in a very small amount of liquid, it is possible to prevent an increase in cost even if an expensive reagent or the like is used as the liquid.

  Further, the resistance of the solution can be kept small when scanning the sample surface with the probe.

  FIG. 1 shows a schematic example of an atomic force microscope that can observe a sample in a liquid.

  In the figure, reference numeral 1 denotes a sample chamber, and a scanner 3 made of, for example, a piezoelectric element on the bottom surface of the chamber, which moves the sample mounting table 2 on which the sample S is set independently in the X, Y, and Z axis directions. It is supported.

  Reference numeral 4 denotes a cantilever having a probe 5 attached to the tip, which is attached to the chamber upper lid 7 via a support 6.

  Reference numeral 8 denotes a light source (for example, a laser light source) for irradiating light to the back surface of the tip of the cantilever 4 (surface opposite to the surface on which the probe 5 is attached), and 9 is reflected from the back surface of the cantilever. A photodetector (for example, a two-divided or four-divided semiconductor photodetector) that receives the emitted light is disposed outside the chamber.

  Reference numeral 10 denotes a transparent plate that is detachably fitted in the central portion of the upper lid 7.

  In such an atomic force microscope, the operator first removes the transparent plate 10 from the upper lid 7 and sets the sample S at a predetermined position on the sample mounting table 2. Then, for example, a predetermined amount of liquid is dropped onto the sample with a pipette. The dropped liquid becomes hemispherical due to surface tension and forms a liquid pool in which a part of the cantilever 4 including the sample S and the probe 5 is immersed.

  Next, the operator places a very thin cover glass 16 on the liquid reservoir. Then, the hemispherical liquid reservoir is deformed into a liquid layer on a rectangular parallelepiped as indicated by W in FIG.

Next, the operator attaches the transparent plate 10 to the upper lid 7 again.
In this state, a Z-axis piezoelectric element (not shown) of the scanner 3 is driven by a height adjustment signal in the Z-axis direction (vertical direction in FIG. 1) from a scan generator (not shown), and the probe The distance between 5 and the sample S is set as an initial set distance.

  Meanwhile, the light emitted from the light source 8 sequentially passes through the transparent plate 10, the cover glass 16, and the liquid layer W, and then strikes and reflects the back surface of the cantilever 4. The reflected light sequentially passes through the liquid layer W, the cover glass 16 and the transparent plate 10 and is detected by the photodetector 9.

  At this time, the X-axis and Y-axis piezoelectric elements (not shown) of the scanner 3 are driven by the X-direction and Y-direction control signals from the scan generator (not shown), and the sample S is moved to the X-axis. It is moved in the direction (left-right direction in FIG. 1) and the Y-axis direction (direction perpendicular to the paper surface in FIG. 1).

  The surface of the sample S to be observed has irregularities, and the distance between the probe 5 and the observation surface of the sample S deviates from the initial set distance according to the irregularities, so that the probe 5 and the sample S The interatomic force between is displaced.

  In this case, the probe 5 moves up and down according to the unevenness of the observation surface of the sample S so as to maintain the initial set distance. For this reason, the inclination of the cantilever 4 also changes in accordance with this vertical movement, so that the position of the reflected light entering the photodetector 9 also changes.

  In the atomic force microscope, the detected position change of the reflected light is converted into a position change in the Z-axis direction, and an uneven image of the sample surface in the liquid is observed based on the converted signal (image signal). .

Japanese Patent No. 2936311

  Now, in the atomic force microscope configured to observe the sample in the liquid in this way, since the amount of the liquid for immersing the probe 5 and the sample S is very small, the liquid layer W evaporates in a short time. End up. For this reason, the sample observation must be interrupted frequently and the liquid must be dropped on the sample S, which makes continuous sample observation impossible in the liquid, and the operation itself is extremely troublesome. Become.

  The present invention has been made to solve such problems, and an object thereof is to provide a novel scanning probe microscope.

In the scanning probe microscope of the present invention, the probe and the sample placed on the sample stage are placed close to each other, the relative position between the probe and the sample is changed, and the probe is placed between the sample and the sample. A scanning probe microscope that obtains image information on the surface of a sample based on interaction, wherein the scanning probe is configured to perform measurement in a state where at least the observation portion of the sample and the probe are filled with a liquid layer In the microscope, a portion that does not contact the sample on the sample mounting surface of the sample table is provided with a liquid storage container that stores the liquid so that the liquid level is positioned below the sample mounting surface on which the sample of the sample table is mounted And at least one through-hole is formed in a portion where the liquid layer is present , one end of a liquid feed that generates capillary action is disposed in the liquid in the liquid container, and the other end is disposed in the through-hole. is, the feeding of the liquid from the liquid container Through, characterized in that form as guided to the liquid layer.
that's all

  According to the present invention, in a scanning probe microscope configured to be able to observe a sample in a liquid, even if the liquid for immersing the probe and the sample is reduced by evaporation, the reduced liquid is always supplied. Since it can be replenished, sample observation in the liquid is not interrupted. Therefore, it is possible not only to continuously observe the sample in the liquid, but also to perform the operation very easily.

  FIG. 2 shows a schematic example of an atomic force microscope which is one of the scanning probe microscopes of the present invention.

  In FIG. 2, the same reference numerals as those used in FIG. 1 denote the same components.

  In FIG. 2, 2 ′ is a sample mounting table mounted on the scanner 3 for mounting the sample S. In the example of FIG. 2, one of the openings is the sample mounting surface of the sample mounting table. A plurality of holes Aa, Ab,... Are formed in a non-contact portion (for example, a portion close to the edge of the sample mounting surface) so that the other opening is positioned on the side surface of the sample mounting table.

  In the figure, reference numeral 20 denotes a bottomed two formed by integrating the inner cylinder 20A and the outer cylinder 20B by connecting one end of the inner cylinder 20A and one end of the outer cylinder 20B with a donut plate 20C. It is a liquid container in the shape of a circular tube, and is attached to the side surface of the sample mounting table 2 '. In the liquid container (that is, the space between the inner cylinder 20A and the outer cylinder 20B), sample observation is performed. The same type of liquid is used as the liquid used.

  21A, 21B,... Is an object capable of generating capillary action, for example, a liquid feed composed of a bundle of synthetic fibers. One end of the liquid feed is disposed in the liquid container 20 and the other end Are arranged in the holes Aa, Ab,... Through the surface opening of the sample mounting table 2 ′.

  In such an atomic force microscope, the operator first removes the transparent plate 10 from the upper lid 7 and sets the sample S at a predetermined position on the sample mounting table 2 '. Then, a predetermined amount of liquid is dropped onto the sample with a pipette. The dropped liquid becomes hemispherical due to surface tension and forms a liquid pool in which a part of the cantilever 4 including the sample S and the probe 5 is immersed. Next, the operator places a very thin cover glass 16 on the liquid reservoir. Then, the hemispherical liquid reservoir is deformed into a liquid layer on a rectangular parallelepiped as indicated by W in FIG. Next, the operator attaches the transparent plate 10 to the upper lid 7 again. In this state, a Z-axis piezoelectric element (not shown) of the scanner 3 is driven by a height adjustment signal in the Z-axis direction (vertical direction in FIG. 2) from a scan generator (not shown), and the probe The distance between 5 and the sample S is set as an initial set distance.

  Meanwhile, the light emitted from the light source 8 sequentially passes through the transparent plate 10, the cover glass 16, and the liquid layer W, and then strikes and reflects the back surface of the cantilever 4. The reflected light sequentially passes through the liquid layer W, the cover glass 16 and the transparent plate 10 and is detected by the photodetector 9.

  At this time, the X-axis and Y-axis piezoelectric elements (not shown) of the scanner 3 are driven by the X-direction and Y-direction control signals from the scan generator (not shown), and the sample S is moved to the X-axis. It is moved in the direction (left-right direction in FIG. 2) and the Y-axis direction (direction perpendicular to the paper surface in FIG. 2).

  The surface of the sample S to be observed has irregularities, and the distance between the probe 5 and the observation surface of the sample S deviates from the initial set distance according to the irregularities, so that the probe 5 and the sample S The interatomic force between is displaced.

  In this case, the probe 5 moves up and down according to the unevenness of the observation surface of the sample S so as to maintain the initial set distance. For this reason, the inclination of the cantilever 4 also changes in accordance with this vertical movement, so that the position of the reflected light entering the photodetector 9 also changes.

  In the atomic force microscope, the detected position change of the reflected light is converted into a position change in the Z-axis direction, and an uneven image of the sample surface in the liquid is observed based on the converted signal (image signal). .

  In the observation of such a sample, the liquid forming the liquid layer W evaporates with the passage of time, and the amount of the liquid decreases.

  However, during such sample observation, the liquid stored in the liquid container 20 is sucked up and formed in the sample mounting table 2 ′ by the capillary phenomenon of the liquid feeding liquids 21A, 21B,. ... Is guided through the holes Aa, Ab,... To the sample mounting surface of the sample mounting table, and is always slightly in the liquid layer W (for example, an amount sufficient to compensate for evaporation of the liquid from the liquid layer W). ) Supplied. Therefore, the liquid amount of the liquid layer W is always kept stable by a predetermined amount.

  In the above example, the liquid storage container 20 is attached to the sample mounting table 2 ′, but the attachment location of the liquid storage container is not limited to this, and may be attached to the inner wall of the sample chamber 1, for example.

  The liquid forming the liquid layer W includes pure water, physiological saline, electrolyte solution, and the like, and is selected according to the sample, for example.

  Further, the liquid feed 21 is not limited to a bundle of synthetic fibers, and may be a porous body, as long as it is a material that sucks liquid by capillary action and guides it to a predetermined place.

  In consideration of a case where the liquid in the liquid container 20 is insufficient, a liquid level detection sensor for detecting the liquid level is provided in the liquid storage container 20, and a liquid container is provided separately to detect the liquid level. A shortage of liquid in the liquid container 20 may be detected based on a detection signal of a sensor, and a predetermined liquid amount may be supplied from the other liquid container to the liquid container 20.

  The sample mounting table 2 ′ may be detachable from the scanner 3.

A schematic example of an atomic force microscope configured to enable observation of a sample in a liquid is shown. 1 shows a schematic example of an atomic force microscope that is one of the scanning probe microscopes of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sample chamber 2, 2 '... Sample mounting table 3 ... Scanner 4 ... Cantilever 5 ... Probe 6 ... Support body 7 ... Top cover
DESCRIPTION OF SYMBOLS 8 ... Light source 9 ... Photodetector 10 ... Transparent plate 16 ... Cover glass 20 ... Liquid storage container 20A ... Inner cylinder 20B ... Outer cylinder 20C ... Donut plate 21A, 21B ... Liquid feeding S ... Sample W ... Liquid Aa, Ab ... Hole

Claims (4)

The probe and the sample placed on the sample stage are placed close to each other, and the relative position between the probe and the sample is changed, and the surface of the sample is changed based on the interaction between the probe and the sample. A scanning probe microscope configured to obtain image information, wherein the measurement is performed in a state where at least the observation part of the sample and the probe are filled with a liquid layer.
Providing a liquid storage container for storing a liquid so that the liquid level is positioned below the sample mounting surface on which the sample of the sample stage is mounted ;
At least one through-hole is formed in a portion of the sample stage that is not in contact with the sample and where the liquid layer is present on the sample mounting surface, and a liquid- feeding liquid that generates capillary action in the liquid in the liquid storage container . A scanning probe microscope in which one end is disposed, the other end is disposed in the through hole, and the liquid from the liquid storage container is guided to the liquid layer through the liquid feeding liquid. The scanning probe microscope according to claim 1, wherein the liquid-feeding liquid that generates capillary action comprises a bundle of synthetic fibers. The scanning probe microscope according to claim 1, wherein the liquid feeding liquid that generates capillary action is made of a porous material. The scanning probe microscope according to claim 1 , wherein the liquid storage container is attached to the sample stage .

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