JP5185723B2 - Atomic force microscope - Google Patents

Description

  The present invention relates to an atomic force microscope.

  2. Description of the Related Art Atomic force microscopes for observation in liquid that perform molecular level observation in an aqueous solution are known. In particular, a high-speed scanning atomic force microscope performs XYZ scanning between a sample and a cantilever by moving a sample stage on which the sample is fixed. In this type of atomic force microscope, in order to keep the sample stage and the Z scanner for Z scanning lightweight, the sample stage is directly fixed to the Z piezoelectric element constituting the Z scanner. For fixing the sample stage to the Z piezoelectric element, a mechanism such as a screw or a spring is not used for weight reduction, and a wax or resin having a thickness of several μm or less between the lower surface of the stacked Z piezoelectric element and the sample stage. System adhesives or adsorbents are used.

  During the measurement, the sample stage is immersed in the aqueous solution. For this reason, a waterproof coating is liquid-tightly provided around the Z piezoelectric element. Moreover, the sample stage which contacts the aqueous solution which is a measurement environment needs to be cleaned for every measurement. Therefore, when exchanging the sample stage, the sample stage itself is cleaned, and the wax, adhesive or adsorbent adhering to the sample stage fixing surface of the stacked Z piezoelectric element is measured to maintain the cleanness of the aqueous solution. Every must be removed cleanly. The wax, adhesive, or adsorbent is removed by dissolving with a solvent, wiping with a paper containing the solvent, or physically removing with a metal spatula.

  At this time, a solvent may be applied to the waterproof coating around the Z piezoelectric element, or physical distortion may occur in the Z piezoelectric element. As a result, the coating may be peeled off, and the Z piezoelectric element and the aqueous solution may come into contact with each other. The contact between the Z piezoelectric element and the aqueous solution may damage the electrode portion of the Z piezoelectric element, and in the worst case, may destroy the Z piezoelectric element.

Japanese Patent Laid-Open No. 7-12553 discloses a sample scanning atomic force microscope for observation in liquid. In this atomic force microscope, a waterproof sealing sheet is provided between the Z piezoelectric element and the sample. Furthermore, a sealing member is provided between the support member that supports the cantilever and the sealing sheet. The aqueous solution is injected into a space surrounded by the sealing sheet, the sealing member, and the support member.
JP 7-12553 A

  In the atomic force microscope disclosed in Japanese Patent Application Laid-Open No. 7-12553, the Z piezoelectric element and the aqueous solution are separated, but a seal made of a vinyl chloride or Teflon (registered trademark) film is provided between the Z piezoelectric element and the sample. Since the stop sheet exists, the sealing sheet is elastically deformed with respect to the displacement of the Z piezoelectric element, thereby causing a delay in the fine movement operation of the sample. Such a delay becomes a hindrance when trying to control the Z piezoelectric element as quickly as possible in order to perform high-speed scanning. That is, the followability of the scanning mechanism for high-speed Z scanning is reduced.

The present invention has been made in consideration of such circumstances, and its object is between atom with good follow-up property with respect to the contact of the piezoelectric element and the aqueous solution is prevented, fast Z scan To provide a force microscope.

  The sample table according to the present invention is directly fixed to the protective plate, and has a sample table body having a Young's modulus at least equal to or higher than the Young's modulus of the piezoelectric element, and is fixed to the sample table body in a watertight manner. And a protective sheet projecting around the protective plate.

An atomic force microscope according to the present invention includes a cantilever, a Z scanning mechanism that holds a sample stage on which an observation sample is fixed facing the cantilever, and scans the observation sample and the cantilever relative to each other in the Z direction. And an XY scanning mechanism that scans the observation sample and the cantilever in an XY direction perpendicular to the Z direction, and a displacement sensor that detects a displacement of the cantilever in the Z direction. The Z scanning mechanism includes at least the piezoelectric element that is stretched and displaced with one end fixed, and is fixed to the end face of the free end of the piezoelectric element so as to cover the entire end face of the free end of the piezoelectric element. A protective plate having a Young's modulus equal to or higher than the Young's modulus, and a coating that covers the entire side surface of the piezoelectric element in a watertight manner. The sample table is directly fixed to the protective plate, and has a sample table body having a Young's modulus at least equal to or higher than the Young's modulus of the piezoelectric element, and is watertightly fixed to the sample table body. And a protective sheet projecting around the protective plate.

According to the present invention, the contact of the piezoelectric element and the aqueous solution is prevented, the nuclear force microscope with good trackability during fast-Z scan is provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First embodiment>
A Z scanning mechanism according to this embodiment is shown in FIG. The Z scanning mechanism of the present embodiment is assumed to be used with an atomic force microscope for observation in liquid.

  As shown in FIG. 1, the Z scanning mechanism 120 includes a piezoelectric element 122 that is fixed at one end and that is extended and displaced, and covers the entire end face of the free end of the piezoelectric element 122 and is fixed to the end face of the free end of the piezoelectric element 122 in a watertight manner. The protective plate 128 having a Young's modulus at least equal to or higher than the Young's modulus of the piezoelectric element 122 and a coating 126 that covers the entire side surface of the piezoelectric element 122 in a watertight manner.

  The piezoelectric element 122 is composed of, for example, a multilayer piezoelectric element. The laminated piezoelectric element has a pair of electrodes 124 on the side surface, and is expanded and contracted in the Z direction (up and down direction in the drawing) in response to voltage application to the electrodes 124. One end, that is, the upper end of the piezoelectric element 122 is fixed to an XY stage 110 that is an XY scanning mechanism for scanning the Z scanning mechanism 120 in the XY directions. The piezoelectric element 122 is fixed to the XY stage 110 with, for example, an adhesive having a thickness about the surface roughness of the lower surface of the XY stage 110 and the upper end surface of the piezoelectric element 122.

  A protection plate 128 is fixed to the end face of the free end of the piezoelectric element 122 so as to cover the entire end face of the free end of the piezoelectric element 122. That is, the protective plate 128 is affixed to the lower end of the piezoelectric element 122 so as to slightly protrude from each side of the lower end surface of the piezoelectric element 122. The protective plate 128 has a Young's modulus at least equal to or higher than that of the piezoelectric element 122. For example, the protective plate 128 has a Young's modulus that is greater than or equal to the Young's modulus of the piezoelectric element 122. The protective plate 128 is preferably made of an insulating material. The protective plate 128 may be made of ceramics such as alumina or zirconia, for example. However, the protective plate 128 only needs to have a Young's modulus at least equal to or higher than that of the piezoelectric element 122, and is not limited to the ceramics described above, and may be formed of fused silica, flint glass, or the like.

  The entire side surface of the piezoelectric element 122 is covered with a coating 126 in a watertight manner. The covering 126 is made of, for example, an insulating resin. The coating 126 exists on the peripheral surface of the piezoelectric element 122 from the XY stage 110 to the protection plate 128, but does not wrap around the side surface of the protection plate 128.

  A sample stage 140 on which an observation sample is fixed is detachably fixed to the protective plate 128. The sample table 140 is fixed to the protection plate 128 by, for example, wax 130 having a thickness similar to the surface roughness of the contact surface between the protection plate 128 and the sample table 140. Instead of the wax 130, a resin-based adhesive or pressure-sensitive adhesive may be used.

  When used in an atomic force microscope for observation in liquid, the Z scanning mechanism 120 is partially immersed in the aqueous solution 160 together with the sample stage 140. That is, the protection plate 128 and a part of the coating 126 come into contact with the aqueous solution. The observation sample is exchanged for the entire sample stage 140. That is, the sample stage 140 is removed from the protection plate 128, and another sample stage 140 to which another observation sample is fixed is fixed to the protection plate 128. At that time, it is necessary to cleanly remove the wax 130 (or adhesive or adhesive) used for fixing the sample stage 140. The removal of the wax 130 is usually performed by dissolving the wax 130 using a solvent or peeling it off with tweezers or a metal spatula.

  In this embodiment, the protective plate 128 is fixed to the free end of the piezoelectric element 122, and the sample stage 140 is fixed to the protective plate 128, so that the solvent that dissolves the wax 130 covers the side surface of the piezoelectric element 122. It can be avoided that the force applied by the tweezers, the metal spatula, or the like directly acts on the piezoelectric element 122. Thereby, the breakage and deterioration of the coating 126 are prevented, and the contact between the piezoelectric element 122 and the aqueous solution 160 is prevented. Further, direct damage to the piezoelectric element 122 can be avoided.

  Further, since the protection plate 128 has a Young's modulus at least equal to or higher than the Young's modulus of the piezoelectric element 122, the Z displacement of the piezoelectric element 122 is correctly transmitted to the sample stage 140. This improves the measurement accuracy of the atomic force microscope.

<Second embodiment>
The present embodiment relates to another sample stage 140A that can be used in place of the sample stage 140 of the first embodiment. A Z scanning mechanism to which the sample stage 140A according to this embodiment is attached is shown in FIG. In FIG. 2, members denoted by the same reference numerals as those shown in FIG. 1 are similar members, and detailed description thereof is omitted.

  As shown in FIG. 2, the sample stage 140 </ b> A has a sample stage main body 142 that is directly and detachably fixed to the protective plate 128, and a waterproof protective sheet 144 that is watertightly fixed to the sample stage main body 142. doing. The observation sample is fixed to the sample table main body 142. The sample stage main body 142 has a Young's modulus at least equal to or higher than the Young's modulus of the piezoelectric element 122. For example, the sample stage main body 142 has a Young's modulus equal to or higher than the Young's modulus of the piezoelectric element 122. The protective sheet 144 projects around the protective plate 128 when the sample stage main body 142 is fixed to the protective plate 128.

  Specifically, the protective sheet 144 has a through hole 144a, and the sample stage main body 142 has a convex portion 142a. The protective sheet 144 is bonded to the sample stage main body 142 in a state where the convex portion 142a is passed through the through hole 144a. The convex portion 142a of the sample stage main body 142 is detachably fixed to the protective plate 128. The sample base 140A is fixed to the protective plate 128 by, for example, wax, an adhesive, or an adhesive having a thickness similar to the surface roughness of the contact surface between the protective plate 128 and the convex portion 142a of the sample base 140A.

  In this embodiment, since the sample stage 140A bonded to the Z scanning mechanism 120 includes the protective sheet 144 that protrudes around the protective plate 128, the coating 126 and the protective plate 128 are prevented from being wetted by the aqueous solution 160. In addition, the contact between the piezoelectric element 122 and the aqueous solution 160 is further prevented as compared with the first embodiment.

<Third embodiment>
This embodiment relates to another protective plate 128A that can be used in place of the protective plate 128 of the second embodiment. FIG. 3 shows a Z scanning mechanism provided with the protective plate 128A according to the present embodiment. 3, members indicated by the same reference numerals as those shown in FIG. 2 are the same members, and detailed description thereof is omitted.

  As shown in FIG. 3, the protective plate 128 </ b> A has a concave portion 128 </ b> Aa having a diameter larger than that of the convex portion 142 a of the sample stage main body 142. The level difference of the convex part 142a of the sample stage main body 142 is larger than the dimension obtained by adding the level difference of the concave part 128Aa of the protective plate 128A and the thickness of the protective sheet 144. The convex portion 142a of the sample stage main body 142 is detachably fixed to the concave portion 128Aa of the protective plate 128A. The sample base 140A is fixed to the protective plate 128A by, for example, an adhesive or adhesive such as wax having a thickness similar to the surface roughness of the contact surface of the concave portion 128Aa of the protective plate 128A and the convex portion 142a of the sample base 140A. Made.

  Since the level difference of the convex part 142a of the sample stage main body 142 is larger than the dimension obtained by adding the level difference of the concave part 128Aa of the protective plate 128A and the thickness of the protective sheet 144, the convex part 142a of the sample stage main body 142 is the concave part of the protective plate 128A. Direct contact with 128Aa. Therefore, the displacement of the piezoelectric element 122 is transmitted to the sample stage main body 142 without being absorbed by the protective sheet 144.

  In the present embodiment, since the protection plate 128A has the concave portion 128Aa that receives the convex portion 142a of the sample stage main body 142, the position of the sample stage 140A is stabilized when the sample stage 140A is replaced.

<Fourth embodiment>
The present embodiment relates to an atomic force microscope 200 for observation in liquid using the Z scanning mechanism 120 described in the first to third embodiments. An atomic force microscope 200 according to this embodiment is shown in FIG.

  As shown in FIG. 4, the atomic force microscope 200 holds a cantilever 230 and a sample stage 140 to which an observation sample is fixed facing the cantilever 230 so that the observation sample and the cantilever 230 are relatively relative to each other in the Z direction. Z scanning mechanism 120 that scans, XY stage 110 that is an XY scanning mechanism that scans the observation sample and cantilever 230 in an XY direction perpendicular to the Z direction, and a displacement sensor that detects displacement of cantilever 230 in the Z direction 260.

  The cantilever 230 is attached to the cantilever holder 220, and the cantilever holder 220 is provided on the base plate 210.

  The Z scanning mechanism 120 is configured by any one of those shown in FIGS. 1 to 3 in association with the description of the first to third embodiments. The Z scanning mechanism 120 is fixed to the XY stage 110, the XY stage 110 is supported by the scanner frame 250, and the scanner frame 250 is supported by the coarse movement stage 240 provided on the base plate 210.

  The distance between the cantilever 230 and the observation sample in the Z direction is coarsely moved by the coarse movement stage 240 moving the XY stage 110 and the Z scanning mechanism 120 in the Z direction, and the Z scanning mechanism 120 causes the sample stage 140 to move in the Z direction. It is controlled by being finely moved by being moved.

  Further, the relative positions of the cantilever 230 and the observation sample in the XY direction are controlled by the sample stage 140 being moved in the XY direction together with the Z scanning mechanism 120 by the XY stage 110.

  For example, the measurement is performed as follows.

  The aqueous solution 160 is supplied to the space around the cantilever 230 and the sample stage 140, and the cantilever 230 and the sample stage 140 are immersed in the aqueous solution 160. The cantilever 230 and the observation sample are XY scanned by the XY stage 110. During the XY scanning, the displacement sensor 260 detects the Z displacement of the cantilever 230, and the Z scanning mechanism 120 is controlled so as to keep the detected Z displacement of the cantilever 230 constant. A three-dimensional image of the surface of the observation sample is constructed based on the position information by XY scanning and the control information of the Z scanning mechanism 120.

  In the atomic force microscope 200 of the present embodiment, since the Z scanning mechanism 120 is configured by any one of those described in the first to third embodiments, the piezoelectric element 122 and the aqueous solution 160 of the Z scanning mechanism 120 The contact is prevented and the Z displacement of the cantilever 230 is correctly detected.

  The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to these embodiments, and various modifications and changes can be made without departing from the scope of the present invention. Also good.

1 shows a Z scanning mechanism according to a first embodiment of the present invention. The Z scanning mechanism with which the sample stand by 2nd embodiment of this invention was attached is shown. 9 shows a Z scanning mechanism including a protection plate according to a third embodiment of the present invention. 7 shows an atomic force microscope according to a fourth embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 110 ... XY stage, 120 ... Z scanning mechanism, 122 ... Piezoelectric element, 124 ... Electrode, 126 ... Coating, 128 ... Protection plate, 128A ... Protection plate, 128Aa ... Recess, 130 ... Wax, 140 ... Sample stand, 140A ... Sample Table, 142 ... Sample base body, 142a ... Convex, 144 ... Protective sheet, 144a ... Through hole, 160 ... Aqueous solution, 200 ... Atomic force microscope, 210 ... Base plate, 220 ... Cantilever holder, 230 ... Cantilever, 240 ... Coarse Moving stage, 250 ... scanner frame, 260 ... displacement sensor.

Claims (2)

A piezoelectric element that is stretched and displaced with one end fixed, and is fixed to the end face of the free end of the piezoelectric element so as to cover the entire end face of the free end of the piezoelectric element, and at least comparable to the Young's modulus of the piezoelectric element It is a sample stage attached to a scanning mechanism having a protective plate having the above Young's modulus and a coating that covers the entire side surface of the piezoelectric element in a watertight manner ,
A sample base body that is directly fixed to the protective plate and has a Young's modulus at least equal to or higher than the Young's modulus of the piezoelectric element;
A sample stage, comprising: a protective sheet that is watertightly fixed to the sample stage main body and that projects around the protective plate. Cantilevers,
A Z scanning mechanism that holds a sample stage on which the observation sample is fixed facing the cantilever, and scans the observation sample and the cantilever relative to each other in the Z direction;
An XY scanning mechanism for scanning the observation sample and the cantilever in an XY direction perpendicular to the Z direction;
A displacement sensor for detecting the displacement of the cantilever in the Z direction,
The Z scanning mechanism is
A piezoelectric element which is elastically displaced with one end fixed;
A protective plate that covers the entire end face of the free end of the piezoelectric element and is watertightly fixed to the end face of the free end of the piezoelectric element and has a Young's modulus at least equal to or greater than the Young's modulus of the piezoelectric element; ,
And having a coating that covers the entire side surface of the piezoelectric element in a watertight manner,
The sample stage is
A sample base body that is directly fixed to the protective plate and has a Young's modulus at least equal to or higher than the Young's modulus of the piezoelectric element;
An atomic force microscope comprising: a protective sheet that is watertightly fixed to the sample stage main body and that projects around the protective plate.

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