JP2006250852A - Scanner, and scanning probe microscope - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized tube scanner of large displacement. <P>SOLUTION: This scanner is provided with a base, a pair of bimorph type piezoelectric elements arranged opposedly with the two deformable bimorph type piezoelectric elements by overlapping two rectangular piezoelectric elements extendable opposite-directionally each other with an electrode therebetween, while conforming a deformation direction, and having one-ends attached to positions different in the base, and a stage supported by the other ends of the bimorph type piezoelectric elements. In the scanner, the bimorph type piezoelectric elements are deformed along the same direction based on a voltage impressed to the electrode to displace the stage. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is a generic term for a scanner that scans a micro area and a scanning tunnel microscope, an atomic force microscope, a magnetic force microscope, a friction force microscope, a micro viscoelastic microscope, a surface potential difference microscope, and similar devices equipped with such a scanner. The present invention relates to a scanning probe microscope.

  Recently, a cantilever with a probe and a sample are placed facing each other, and the distance between the probe and the sample is set to a distance of several nanometers or less, the sample surface is scanned with the probe, and a tunnel current generated between the probe and the sample, Attention has been focused on scanning probe microscopes that measure physical quantities such as atomic force, magnetic force, or electrostatic force, and obtain a concavo-convex image of the sample surface based on the measurement. Usually, a polarized cylindrical piezo element is used as a scanner for scanning the probe of the scanning probe microscope and the sample relatively. The tube scanner is coated with electrodes, and by applying a voltage to each electrode while controlling the voltage, the piezoelectric element under the electrode expands or contracts according to the sign of the voltage. By combining this displacement, the tube scanner is displaced in the X, Y, and Z directions.

  The scanning probe microscope may be observed in a limited space such as in a superconducting magnet (SCM). In order to put the scanning unit in the SCM, it is premised that the scanning unit is used in an extremely low temperature and ultrahigh vacuum environment at a temperature of 20K.

  However, the conventional tube scanner has a problem that the amount of displacement is small compared to the size. In particular, when the scanning unit is arranged in the SCM, the size of the scanner is limited. It is known that the amount of displacement of the piezo element is about 1/6 to 1/8 of the amount of displacement at room temperature at extremely low temperatures. It is about 5 μm. The amount of displacement in the XY direction necessary for SCM observation is at least about 30 μm, and the corresponding length of the tube scanner is 600 mm, which cannot be accommodated in the SCM.

  As conventional techniques, there are various types of tube-type piezoelectric drive elements (for example, Non-Patent Document 1).

JPO Home Page> Standard Technology Collection> Atom region analysis of surface structure 3-B-b2 Configuration of piezo drive element-Tube type

  The problem to be solved by the present invention is that the tube scanner has a small amount of displacement compared to its size. In particular, when used in a limited space such as SCM, the amount of displacement is not sufficient for a tube scanner of a size that can be stored.

  According to the first aspect of the present invention, two bimorph-type piezo elements that can be deformed by overlapping a base and two strip-shaped piezo elements that expand and contract in opposite directions with the electrodes sandwiched are arranged opposite to each other. And a stage having one end attached to a different position of the base and a stage supported by the other end of the bimorph type piezo element, the voltage applied to the electrode The stage is displaced by deforming the opposing bimorph type piezo elements in the same direction based on the above.

  The invention of claim 2 further provides a pair with different deformation directions by 90 °, and has a rigidity in the deformation direction of the bimorph element between the other end of each bimorph element and the stage. The scanner according to claim 1, wherein the scanner is connected via a connecting member that is deformed in a direction orthogonal to the direction.

  According to a third aspect of the present invention, each of the bimorph type piezo elements is provided as a set of two, and each of the other ends of the bimorph type piezo elements of the set is bundled by a clip, and the relay attached to the clip. The scanner according to claim 2, wherein the scanner is connected to the connection member via a member.

  A fourth aspect of the invention is the scanner according to the third aspect, wherein each of the pair of bimorph-type piezo elements is disposed with a space therebetween.

  A fifth aspect of the invention is the scanner according to any one of the first to fourth aspects, wherein a laminated piezo element for displacing the base in a stretching direction of the bimorph type piezo element is attached to the base.

  A sixth aspect of the present invention is a scanning probe microscope that relatively scans a probe facing a sample using the scanner according to any one of the first to fifth aspects.

  The scanner according to the present invention is advantageous in that it is small and has a large displacement. Therefore, when used in the SCM of a scanning probe microscope, a wide range can be scanned without enlarging the apparatus.

  Hereinafter, the present invention will be described in detail according to the best mode for carrying out the invention.

  The configuration of the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view of a scanner according to the present invention. The lower ends of the two bimorph piezo elements 7 are fixed ends, and the upper ends are free ends. The bimorph type piezo element includes two strip-shaped piezo elements 15 polarized in opposite directions, an electrode film is formed on the central electrode film 14 and a power source 16 is connected, and an electrode film is also formed on the outside of the strip-shaped piezo element 15. Is formed and grounded. A sample stage 12 is installed at the free end.

  While the configuration of FIG. 5 has been described above, the operation will be described next. FIG. 4 is an operation diagram of the bimorph type piezo unit in FIG. When a positive voltage is applied to the central electrode film 14 as shown in FIG. 4A, the left strip-shaped piezo element 15 contracts and the right strip-shaped piezo element 15 expands. Transform to the left. When a negative voltage is applied to the central electrode film 14 as shown in FIG. 4B, the reverse action occurs, and the entire bimorph piezo element 7 is deformed to the right.

  In FIG. 5, when a positive voltage is applied to the central electrode film 14, the bimorph piezo elements 7 on both sides are deformed to the left, and the sample stage 12 is also deformed to the left. When a negative voltage is applied to the center electrode film 14, it is deformed to the right.

  The above is a schematic description of the operation in one axis (X direction). By arranging a pair of bimorph piezo elements 7 (not shown) at positions perpendicular to the paper surface (Y direction), the sample stage 12 is Deforms freely in the sample stage plane direction.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, a bimorph type piezo element may have two strip piezo elements polarized in opposite directions on both sides of a strip metal plate, the metal plate serving as one electrode, and the two piezo elements serving as the other electrode.

  Alternatively, a pair of bimorph piezoelectric elements that scan in the Y direction may be arranged on a pair of bimorph piezoelectric elements that scan in the X direction.

  The configuration of the present invention will be described with reference to FIGS. FIG. 1 is a front view of a three-dimensional scanner according to the present invention.

  A flange 2 is fixed to the rod of the straight type micrometer 1 with screws 3. Three laminated piezo elements 4 are installed on the flange 2 at equal intervals on the circumference of the XY plane. A flange 5 is installed at the other end of the multilayer piezoelectric element 4. Both end portions of the laminated piezo element 4 are fixed to the flanges 2 and 5 with screws and further fixed with an adhesive. A base 6 is fixed to the flange 5 via a rod. The base 6 serves as an insulator. Four bimorph piezo elements 7 are installed on the base 6 every 90 degrees on the circumference of the XY plane. In this attachment, a groove is formed in the base 6 and the bimorph type piezo element 7 is inserted, and the periphery is adhered. The bimorph type piezo element 7 has two strip-shaped bimorph type elements as a set, and is attached about 0.5 mm apart in order to increase the generated force. Each bimorph type piezo element 7 is connected to a power source (not shown) at the center as in the first embodiment, and the outer electrode film is grounded. The other end of the pair of bimorph piezo elements 7 is sandwiched between the clips 8 without being bonded so as not to restrain the movement of the tip. A relay member 10 is fixed to each of the four clips 8 installed in each pair of bimorph type piezo elements 7 with screws 3. In the relay member 10, four leaf springs 11 that are connection members are radially arranged equally. A disk-shaped sample stage 12 is installed at the other end of the leaf spring 11. The plate spring 11 is attached by providing a 0.2 mm deep groove in the sample stage 12 and the relay member 10, and inserting the plate spring 11 into the gap to perform soldering. A sample holder 13 is installed on the sample stage 12, and a sample 18 is detachably mounted on the sample holder 13. 2 is a front view and a plan view of the sample stage portion, and FIG. 3 is a perspective view of the sample stage portion.

  Although the respective parts of the configuration in FIGS. 1 to 3 have been described above, the operation will be described next. When the same voltage is applied to the central part of two bimorph piezoelectric elements 7a facing each other in FIG. 2, the free end tends to deform in the X direction because one end is a fixed end. However, a stage 12 is installed on two sets of bimorph type piezo elements 7a facing each other in the X direction via two leaf springs 11a having the X direction as a longitudinal direction (longitudinal elastic modulus is large). Therefore, although the bimorph type piezo element 7a is subjected to a drag, the sample stage 12 is deformed in the X direction by the elastic deformation of the leaf spring 11a. On the other hand, the other two leaf springs 11b perpendicular to this change easily because they receive a force from the lateral direction (X direction). That is, the drag generated in the X direction hardly deforms in the other direction, and is deformed by an amount corresponding to the generated drag of the bimorph type piezo element 7a. Further, the direction of movement is changed by changing the plus or minus of the voltage applied to the central electrode film of the bimorph piezoelectric element.

  Similarly, when a voltage is applied to a pair of bimorph type piezo elements 7b arranged in the Y direction, it deforms in the Y direction. By combining the deformation in the X direction and the deformation in the Y direction, the sample stage 12 can be freely deformed on the XY plane.

  The deformation in the Z direction is performed by the laminated piezo element 4. Three laminated piezo elements 4 are used because the balance is not good. In this case, three laminated piezoelectric elements 4 are connected in parallel and a voltage is applied in the same direction to expand and contract to perform deformation in the Z direction. Three-dimensional movement is possible by the voltage operation described above.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, four or more, for example, eight morph piezoelectric elements may be used at regular intervals.

  In Example 3, the scanner of Example 2 is used in a tunnel microscope.

  FIG. 7 is an external view of the tunnel microscope. An ultra-high vacuum chamber 21 is disposed on the base 20. A vacuum joint 22 is installed in the ultra-high vacuum chamber 21, and equipment can be put in the chamber 21 and equipment can be connected thereto. Inside the chamber 21, a scanning tunnel microscope using the scanner in the second embodiment housed in an SCM (not shown) is installed. A computer 23 is connected to the chamber 21 and the measurement is computer controlled.

  FIG. 6 is a control block diagram in which the scanner of the present invention is used in a scanning tunneling microscope. In the scanning tunnel microscope, when the distance between the sample and the metal probe is kept at 1 nm or less and a bias voltage of about several volts is applied between them by the bias circuit 27, the vacuum gap between the probe 17 and the sample 18 is increased. The so-called tunnel effect principle is used, in which electrons move through and a tunnel current flows. The tunnel current is sensitive to the distance between the sample 18 and the probe 17 and changes exponentially with respect to the distance. Therefore, this signal is controlled using the computer 26, and the multilayer piezo element 4 is driven by the Z piezo driver 29 to make the tunnel current constant, while the bimorph piezo element 7 is formed on the sample surface by the XY piezo driver 28. Is driven to scan two-dimensionally. At this time, the unevenness on the surface of the sample 18 can be observed at the atomic level by imaging the voltage applied to control the Z direction as the unevenness information based on the data converted by the computer 26 into the distance.

  There is only a limited space inside the SCM, and the environment is a cryogenic temperature of 20K and a vacuum. In the scanning tunnel microscope housed in the SMC, magnetic resonance force microscope (MRFM) measurement and the like are performed in addition to the concavo-convex image.

  According to the present invention, a scanner that performs scanning with an amount of scanning in the XY direction of ± 150 μm and an amount of displacement of ± 38 μm in the Z direction at room temperature and a scanning amount of ± 30 μm in the XY direction at an extremely low temperature of 20K is about 32 mm in diameter × 130 mm in length. Realized in size. Thereby, the tunnel microscope can be accommodated in the SCM.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, the scanner of the present invention can be applied to an atomic force microscope, a magnetic force microscope, a friction force microscope, a micro viscoelastic microscope, a surface potential difference microscope, and a scanning probe microscope in general, which is a similar device. Further, scanning may be performed by attaching a scanner to the probe side.

1 is a diagram showing an embodiment of a scanner according to the present invention. It is the front view and top view of the sample stage vicinity of the scanner by this invention. It is a perspective view near the sample stage of the scanner according to the present invention. It is a basic modification of the bimorph type piezo element. 1 is a diagram showing an embodiment of a scanner according to the present invention. It is a scanning tunneling microscope using the scanner of the present invention. It is an external appearance of the scanning tunnel microscope of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Micrometer 2 Flange 3 Screw 4 Laminated piezo element 5 Flange 6 Base 7 Bimorph type piezo element 7a Bimorph type piezo element 7b Bimorph type piezo element 8 Clip 9 Block 10 Relay member 11 Plate spring 11a Plate spring 11b Plate spring 12 Sample stage DESCRIPTION OF SYMBOLS 13 Sample holder 14 Center electrode film 15 Strip-shaped piezo element 16 Power supply 17 Probe 18 Sample 19 Probe holder 20 Base 21 Chamber 22 Vacuum joint 23 Computer 24 Vacuum pump 25 Gas cylinder 26 Computer 27 Bias circuit 28 XY piezo driver 29 Z piezo driver

Claims (6)

Base and
Two bimorph piezo elements that can be deformed by overlapping two strip-shaped piezo elements that expand and contract in opposite directions with the electrodes interposed therebetween are arranged opposite to each other with their deformation directions matched, and one end is located at a different position of the base A pair of attached Bimorov piezo elements;
A stage supported by the other end of the bimorph-type piezo element,
2. A scanner according to claim 1, wherein the stage is displaced by deforming the opposing bimorph type piezo elements in the same direction based on a voltage applied to the electrodes.   A further pair is provided with different deformation directions by 90 °, and between the other end of each bimorph type piezo element and the stage is rigid in the deformation direction of the bimorph element and in a direction perpendicular to the deformation direction. The scanner according to claim 1, wherein the scanner is connected via a deformable connecting member. Each of the bimorph type piezo elements is provided as a set of two,
3. The scanner according to claim 2, wherein the other end of each pair of bimorph type piezo elements is bundled by a clip and connected to the connection member via a relay member attached to the clip.   4. The scanner according to claim 3, wherein each of the pair of bimorph-type piezo elements is disposed with a space between each other. 5.   The scanner according to any one of claims 1 to 4, wherein a laminated piezo element for displacing the base in a stretching direction of the bimorph type piezo element is attached to the base. A scanning probe microscope that relatively scans a probe facing a sample using the scanner according to claim 1.

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