JPH02239562A - Tube-type prove scanner - Google Patents

Abstract

PURPOSE: To provide a piezoelectric scanner which has an extremely good stability and a long scanning distance by installing scanning electrodes to inside and outside surfaces of a tube forming a scanner and applying scanning voltages which are mutually equal and directed to the opposite directions to facing electrodes inside and outside in the tube. CONSTITUTION: Internal scanning electrodes 24 are arranged at an angle of every 90 deg. leaving a little space in a piezoelectric tube 12. The inside of the piezoelectric tube 12 is covered over almost 360 deg.. Similarly, four external scanning electrodes 1, 2, 3, 4 are installed outside the piezoelectric tube 12 at an angle of every 90 deg. facing to each electrode 1a, 2a, 3a, 4a of the internal scanning electrodes 24. A probe 20 moves to the direction of X axis when a voltage +X is applied to the electrode 2, a voltage -X to the electrode 2a, a voltage +X to the electrode 4a and a voltage -X to the electrode 4, respectively. A similar phenomenon occurs in the direction of Y axis.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a piezoelectric scanner for operating a probe or sample of a scanning probe microscope. More specifically, it concerns the manufacture and operation of tube-type probe scanners. [Prior art] For example, scanning tunneling microscope @ (STM) or atomic microscope 111! In a scanning probe microscope (AFM), a probe is scanned across the surface of a sample to determine properties of the surface, such as topography or magnetic field forces, and the results can be represented in an image. Can be done. The sample can also be scanned across an immobilized probe. Alternatively, both can be scanned. As described below, in most embodiments of the invention, the probe is mounted on top of the scanner, but in any case the sample may be mounted on top of the scanner to which the probe is fixed. Needless to say. Accordingly, the inventors of the present invention have provided a preferred solution to many of the objects set forth herein. However, there are many solutions within the scope of the claims without departing from the scope and spirit of the invention disclosed herein. Some types of microscopes, namely STM and AFM, use either a scanning probe or a sample. It has the ability to analyze individual atoms. Scanners that perform this function are usually three-dimensional, that is, X, Y axis planes, and vertical (Z
A piezoelectric device that can operate in all axial directions. When analyzing the movement of a probe at the atomic level, it goes without saying that the actuation mechanism must be stable and able to move accurately in small increments. Nowadays, three-dimensional scanners are tube-shaped, and the probe or sample-carrying end of the three-dimensional scanner is capable of detecting It can be deflected in each axis direction. Regarding the configuration of this electrode, there are multiple electrodes on the outside surface of the piezoelectric scanner, and on the inside surface of the piezoelectric scanner.
One electrode is attached to each. This apparatus is shown in Figures 1 to 5 of the accompanying drawings. The external scanning electrode (10) is provided on a piezoelectric scanner made of piezoelectric material. Each external scanning electrode (10) has a small gap between them, and is arranged at angular intervals of 90°. The internal scanning electrode (14) covers the entire inner surface of the piezoelectric scanner (12). All electrodes (10) (14) from the attached end (16) to the free end are equipped with probes (20).
Or sample (40) is attached. In Figures 1 and 2. As shown in phantom, the external scanning electrode (10) is adapted to perform scanning by bending the voltage tube (12), ie, to move the probe in the X- and Y-axis directions. On the other hand, in FIG. 1, as indicated by the dotted arrow, the internal scanning electrode (l4) is connected to the free end (18
) in the vertical direction, that is, in the Z-axis direction. More recently, the scanning range has been expanded in this device by applying four auxiliary voltages (x), (XL(y) - (y) to the electrodes facing the four external scanning electrodes (10). , and is said to be more symmetrical than that of the Binning and Smith device, which uses only two electrodes for scanning and direct current (OC) offset.Uses auxiliary voltages. For many scanners, a DC offset is added to the scanning voltage in order to move the center of the scanner. It is important to be able to obtain a scanning range of up to a few microns and to have good mechanical stability.The movement of a piezoelectric scanner is proportional to the electric field within the piezoelectric material; The electric field in the material is equal to the voltage divided by the piezo scanner's wall thickness. Therefore, to obtain a larger scan it is necessary to use a larger voltage, but in a practical scanner It is limited by the voltage limits of the available amplifiers, currently typically ±225v. Another method is to reduce the wall thickness of the piezoelectric tube, but this is limited by manufacturing limits, i.e. For a .81 m (2 inch) tube, currently only about 0.7 am (0.3 inch) can be reduced. Therefore, it is an object of the present invention to It is designed to move the probe or sample;
The object of the present invention is to provide a piezoelectric scanner that is extremely stable and has a large scanning distance. Another object of the invention is to move a probe, such as a scanning probe microscope, across a piezoelectric material in order to maximize the movement of the probe in the X, Y, and Z axes. The purpose of this invention is to provide a piezoelectric scanning device that can obtain a high electric field. [Example] Hereinafter, preferred embodiments of the present invention will be described in detail based on the drawings. The basic principle of the invention is to attach scanning electrodes to the inner and outer surfaces of the tube forming the scanner, and to apply equal and opposite scanning voltages (typically By applying a trigonometric function in time), the electric field within the piezoelectric material in the tube can be increased considerably.
A preferred embodiment of the scanner according to the invention is shown in FIG. 6, which is a side view, and FIG. 7, which is a cross-sectional view of the scanning electrode. (22)
It is shown in . For easy understanding, each electrode is shown in FIGS. 9 and 10. It is shown in a simplified exploded diagram. Figure 9 shows the electrode (24) inside the piezoelectric tube (12), and the 10th
TJ! i is. The outer electrode (26) is shown. Inside the piezoelectric tube (12), internal scanning electrodes (24) are arranged at every 90° angle with slight gaps, and the inside of the piezoelectric tube (12) extends approximately 360°. covered. For convenience of briefly explaining the operation of the present invention, 4
Each of the two electrodes (24) has a (Ia) (2a)
(3a) (4a) are marked. Similarly, four external scanning electrodes (
1) (2) (3) (4) are the internal scanning electrodes (2).
The electrodes (Ia) (2aH3a) (4a) of 4) are provided opposite each other at an angle of 90°. The inner and outer scanning electrodes (24) and (26) are connected to the mounting end (l) of the tube (12).
6), and has a length extending from the attachment end (l6) to approximately half the length of the tube (12). As shown in Figure 8, voltage (+X) is applied to electrode (2), voltage (1X) is applied to electrode (2a), voltage (+X) is applied to electrode (2a), voltage (+
4a) and when a voltage (1X) is applied to the electrode (4), the probe (20) moves in the direction of the X axis. If the tube (12) is properly poled in a known manner. The piezoelectric material expands between electrodes (2) and (2a) and contracts between electrodes (4》 and (4a). Therefore, the tube (12) is bent and its free end (18 )
moves in the direction of the X axis. Needless to say, a similar phenomenon occurs in the Y-axis direction as well. According to the device and method of operating the same according to the present invention, the electric field is doubled compared to the conventional one, and the internal scanning electrode (I
4) at any position of the tube (l2),
The voltage will be the same. Therefore, the scanning range is also doubled. When the inventor conducted an experiment, the scanning range more than doubled. This shows that as the electric field increases, the effect of the piezoelectric material increases in proportion to it, and the scanning range increases in proportion to the electric field. According to the present invention, eight scanning electrodes are separated into scanning electrodes and offset electrodes. Due to this. According to the present invention, the problems associated with prior art scanning devices that integrate scanning and offset functions are solved. In such conventional devices, both the scan (AC) and offset (OC) signals are applied electrically.
The DC offset signal can be as large as 200V even if the AC scanning voltage is only IV. The OC power that is in practical use is extremely noisy. This noise becomes an AC signal and interferes with the AC scanning voltage. If the electrically applied scan/offset voltage is filtered to remove this AC noise, the AC scan signal will be removed as well. By separating the functions of the eight scan electrodes from the scan and offset electrodes, the Binning and Smith approach
The OC position offset function, similar to the approach), is separated from the AC scan. However, by making the electrodes symmetrical, even higher sensitivity can be obtained than with the arrangement described above. This is... For example, this can be achieved by applying an offset voltage in the X-axis direction shown in FIG. 7 to the electrodes (2) and (4a), and a scanning voltage in the X-axis direction to the electrodes (2a) and (4), respectively. Therefore, a separate fully filtered DC offset voltage can be used separately from the unfiltered scanning voltage to reduce electrical noise in electronic equipment. In the same sample (40), an offset voltage in the Y-axis direction is applied to electrodes (1) and (3a), and a scanning voltage in the Y-axis direction is applied to electrodes (la) and (3), respectively. This device does not require any auxiliary voltage. Since the offset and scanning functions are already electrically separated, different filtering scanners can be used for the two voltages. This is very useful when combining small scanning voltages with large offset voltages. Since noisy high voltages are DC signals, they are filtered considerably. However, since the scanning signal is an AC signal, it is not filtered. Therefore, it can be used even at low voltages with low noise characteristics. A problem associated with this is that both the offset and scanning range are about 1/2 that of the case using the auxiliary voltage. but,
In fact, the advantages of the device of the invention described above far outweigh these disadvantages. According to a slightly different method of electrode operation, the X-offset voltage and its compensation voltage or ground are
) and (2a) (not shown), and the X-scan voltage and its compensation voltage are applied to electrodes (4) and (4a). Having the offset and scanning functions physically separated on the tube and non-linear within the piezoelectric body provides many advantages. For example, with this method, due to the nonlinearity of the scan and offset, the resulting electric field is not applied as in the previously described method and remains separated. The same effect occurs on the Y axis. The problem with this method is that because the arrangement is asymmetric, the offset and scan voltages act on the Z-axis position of the probe, coupling the X-axis to the Y-axis and the Y-axis to the Z-axis. Therefore, in all embodiments of the invention described herein, eight scan electrodes are provided, two for each , two for the other X-axis, two for one Y-axis, and two for the other Y-axis, or two for the X-axis scan, and the X-axis offset. by either two for the Y-axis scan, two for the Y-axis offset, and so on.
The inner and outer scanning electrodes (24) (26), which can be driven, are connected to a piezoelectric tube (
12), eliminating the need for Z-axis electrodes in conventional technology. Figure 6. In the preferred embodiment of the invention shown in FIGS. 7, 9 and 10, the telescoping movement of the piezoelectric tube (12) for actuating the probe (20) in the Z-axis direction is carried out at the free end (18). This is achieved by an internal Z-axis electrode (28) and an external Z-axis electrode (30) provided inside and outside of the adjacent tube (12). As shown in Figures 9, 10, and 12-14,
Both Z-axis electrodes (28) (30) occupy most of the remaining area of the piezoelectric tube (12), other than that occupied by the scanning electrodes (24) (26), which have a small gap from them. When a Z-axis voltage signal is sent to the external Z-axis electrode (30), a constant voltage (e.g., ground) is applied to the internal Z-electrode (28) or the same voltage is connected to the ZN potential, resulting in a constant voltage. The vertical operating sensitivity of the probe (20) with respect to (Z) is doubled. The inner and outer scanning electrodes (24) (26) in this device are far away from the probe (20) and at the mounting end (26).
16). i.e. a piezoelectric tube (12) close to its end which is fixed in a known manner to the scanning head of the microscope.
It is provided at the end of the Importantly, if the piezoelectric tube (12). That is, when the scanning electrodes (24) (26) are attached to the attached end (16) rather than the free end (18), the actuation of the probe (20) by the electrodes becomes even more violent. Through experiments, the inventor discovered that scanning 11! In test tubes with poles, the electrode at the free end (l8), which occupies half the length of the tube, is . We discovered that less than 25% of the probe movement was activated.
Therefore, the mounting end (which occupies half of the voltage tube (l2)
If a scanning electrode is provided on the probe (20), which occupies 1/2 of the area of the same tube, more than three times the deflection can be obtained than if they were provided on the probe (20), which occupies 1/2 of the area of the same tube. Similarly, the Z-axis electrodes (28) (30) must be connected to the free end (l8) of the piezoelectric tube (l2) in order to obtain good dynamic characteristics.
) is important. The best dynamic characteristics are obtained when the probe (20) is moved in the Z-axis direction.
Obtained when the piezoelectric tube (l2) is moved as much as possible in order to move 0). When the piezoelectric material is expanded or contracted by changing the voltage between the biaxial electrodes (2g) (30) provided at the free end (18), the other end of the piezoelectric tube (12) is fixed. Therefore, only the piezoelectric material between the electrodes (2g) (30) is activated, and the probe (20) is moved. For example, in the configuration shown in the attached drawing, the electrode (28
) (30), only 1/2 of the length of the piezoelectric material is
It moves up and down depending on the length of the probe (20). In the example, if a biaxial electrode (28
) If the length of (30) is only about 1/2 that of the piezoelectric tube (12), it will move with the probe by 1/4 of the length of the tube (12). If the Z-axis electrodes (28) (30) are provided at the mounting end (16) of the piezoelectric tube (2), and they
2) has a length of 172, the same tube (12
) along with the probe (20) in the vertical direction. Therefore, the dynamic characteristics become low. This difference in dynamics becomes decisive when the probe (20) is held several intermolecular distances from the surface of the sample being scanned. Another electrode arrangement is shown in simplified or exploded views in FIGS. 11 and 12. Although this device is not necessarily suitable, it provides many advantages in a trade-off situation, as will be understood from the explanation below. FIG. 11 shows the internal electrode (28), and FIG. 12 shows the external electrode (30). It goes without saying that both the inner and outer electrodes (24) and (26) of the present invention are compatible, but FIGS.
In the apparatus shown in the figure, as explained below. The structure is easy, and the characteristics of the tube (12) are particularly improved. In this device, an internal scanning 1t pole (24) is attached over the entire length of the inner surface of the piezoelectric tube (12), while an external scanning electrode (26) and an external Z electrode (3
0) has been removed along with the internal Z-axis electrode (28), as in the previous example. In this device, scanning takes place as in conventional embodiments. The operation in the Z-axis direction is. External Zm*
This is done by applying pressure in the direction of poles (30) and (7) and ZIlk11t. The voltages at the internal scan electrodes (24) may be different, but the changes in the electric field due to the potential of the IE electrodes (30) are... It remains constant throughout the circumference of the piezoelectric tube (12). Therefore. The end of the piezoelectric tube (12) covered by the tC pole (30) is connected to the electrode (30).
When the voltage changes, the area around it expands or contracts uniformly. The scanning range of this device is larger than that of the device shown in FIGS. 9 and 10 because the internal scanning electrode (24) is mounted over the entire surface below the piezoelectric tube (12). However, this device, like other devices. Sensitivity in the Z direction is limited because +2 and -Z voltages cannot be used for motion in the Z direction. Also, the gain in the scanning range is tJs compared to that of other devices. The biaxial electrode (30) can be completely removed and its movement in the Z-axis direction is limited. tube(
scanning electrode (24.) extending over the entire length of l2);
(26) by a constant offset voltage applied to the voltages in the X and Y axes. In other words,
The inner and outer scanning electrodes (24) and (26) are as shown in FIG. This degrades scanning performance in both the X-Y and Z axes, and is therefore the least desirable in implementing the present invention. FIGS. 13 and 14 show a scanning piezoelectric tube (12
) are shown. Although any of the electrodes described above may be used, the device of FIGS. 11 and 12 is much easier to manufacture than the embodiment of FIG. 13.

On the other hand, according to the configurations shown in FIGS. 9 and 10, manufacturing of the scanner becomes easier as shown in FIG. 14. In Figure 13, the sample for scanning (40) is attached to the free end (18) of the scanner (22),
In the figure, a probe (20) is attached to the free end (18) of the same scanner (22). The fact that either the probe (20) or the sample (40) scans, that is, moves and hangs relative to the other will be explained in detail below. The inventor has confirmed through numerous experiments that it is important to maintain the size of the piezoelectric tube (12) that moves together with the probe (20) or sample (40) throughout its entire movement. ．． In order to obtain satisfactory performance and to make the strength of the piezoelectric tube (12) sufficiently high,
) of sample (40) as shown in Figure 13.
It is tapered so that it becomes thinner as it approaches the mounting end (16), and becomes thicker as it approaches the mounting end (16). For example, the inventor reduced the wall thickness of the tube (12') from 1.02 inches (0.04 inches) to 0.51 inches (0.02 inches) as it approached the sample (40). We conducted repeated experiments. Since the inner surface of the piezoelectric tube (12') is tapered, the mounting device holding it must be tapered even if the outer surface of the piezoelectric tube (12') is tapered. No. That is, by making the inner surface of the piezoelectric tube (12') tapered and the outer shape cylindrical, the attachment device II (not shown) has the following characteristics.
A simple cylindrical gripping collar will also work. In this way, by tapering the inner surface of the piezoelectric tube (12'), the piezoelectric tube (12') for scanning can be made smaller and have greater strength. It becomes possible to support both X-Y axis scanning and vertical movement (Z-axis direction) of the sample (40). Another feature of the present invention is that the wall thickness under the Z-axis electrode (30) is small and the electric field is large, so the sensitivity in the vertical direction is good in the same range of Z-axis voltage. This is an advantage. This makes the device according to the invention shorter and very useful compared to conventional devices in which the biaxial electrode covers the entire inner surface of the piezoelectric tube (12'). FIG. 14 shows another embodiment for reducing the length of the free end (18) of the piezoelectric tube (12'). In this embodiment, the wall thickness of the piezoelectric tube (12') changes abruptly through one or more steps (32). By providing these steps (32), this device has... It has the advantage of being easy to manufacture. One way to create this step (32) is to glue two or more tubes together into one tube. Auxiliary tubes may be of constant or varying wall thickness to best match the complete tube. The inventor said that the wall part is 0.51s
am (0.02 inch) wall thickness and a solid tube with a length of 19.051 mm (374 inches).
It has a wall thickness of 1.02 m (0.04 inch) and has 4 electrodes on both the inner and outer surfaces.
A tube with a length of 38.1 (11./2 inches) was formed by gluing the ends of a tube with a length of 74 inches (74 inches). As shown in Figure 14, a piezoelectric tube (12') is attached at the end with a scanning electrode, and a probe (20).
*It is attached to the free end (l8) which has a thick wall surface.
A 25 micron scan of the compact disk stump bar may be performed by a scanner equipped with a piezoelectric tube as previously described. At present, scanning IIm according to this method, in particular,
Very large on rough surfaces.

[Brief explanation of drawings]

FIG. 1 is a simplified side view showing how the free end of the tube moves in the X, Y, and Z axes as the piezoelectric material moves in a conventional piezoelectric scanner. FIG. 2 is a plan view of FIG. 1 showing the deflection effect caused by the movement of the piezoelectric material. FIG. 3 is a simplified side view showing the electrodes of a conventional piezoelectric scanner attached to the outer surface of the tube to select the movement of the piezoelectric material. FIG. 4 shows that in the conventional piezoelectric scanner shown in FIG.
A simplified cutaway diagram showing electrodes attached to the inner surface of the tube to select the movement of the piezoelectric material. FIG. 5 is a plan view of the scanner shown in FIGS. 3 and 4. FIG. 6 is a side view of a piezoelectric scanner according to the present invention. Figure 7 is a plan view of the piezoelectric scanner shown in Figure 6. 8th FJR is a simplified diagram showing the structure and operation of the piezoelectric scanner according to the present invention. FIG. 9 is a simplified exploded view of the internal electrodes in a preferred embodiment of the piezoelectric scanner according to the present invention. Figure 10 shows
7 is a simplified development view of an external electrode in the embodiment of the piezoelectric scanner shown in FIG. 6. FIG. FIG. 11 is a simplified exploded view of the internal electrodes in another embodiment of the piezoelectric scanner according to the present invention. Figure 12 is. 12 is a simplified development view of the external electrode of the piezoelectric scanner shown in FIG. 11. FIG. 13 is a partially cutaway view of the piezoelectric scanner of the present invention showing the internal structure of the piezoelectric cylinder with sides tapering from the mounted end toward the free end holding the scanning probe or sample. This is a side view. Figure 14 shows a piezoelectric device with stepped sidewalls, the wall thickness of which increases as it approaches the mounting end and is thinnest as it approaches the free end that holds the scanning blub or sample. 1 is a partially cutaway side view of a piezoelectric scanner according to the invention showing an alternative structure inside the cylinder; FIG. (1) - (4) External scanning electrode (1a) - (4a) Internal scanning electrode (10) External scanning electrode (l2) Piezoelectric tube (14) Internal scanning electrode (16) Mounting end (18)
) Free end (22) Scanner (26) External scanning electrode (30) External 2-axis electrode (40) Sample (X) (Y) (Z) axis (20) Probe (24) Internal scanning electrode (28) Internal 2-axis Electrode (32) step FIG. 8 Fl(;. 7 FIG. FIC;. Fl(;.f2 FIG.

Claims (12)

[Claims] (1) (a) a cylindrical tube made of piezoelectric material having an attachment end, a free end with means for supporting a scanning probe or a scanning sample, and inner and outer walls; (b) an inner surface of the tube; (c) four internal scanning electrodes whose side edges are adjacent to each other at regular intervals and are arranged at angular intervals of 90° so as to cover almost the entirety of the same inner surface; The electrodes are attached to the outer surface of the tube, and are arranged at intervals of 90° so as to cover almost the entire outer surface, with side edges adjacent to each other at regular intervals, and facing each of the internal electrodes. A tube-shaped probe type scanner characterized in that it is equipped with four external scanning electrodes. (2) The tube-type probe scanner according to claim (1), wherein the inner and outer scanning electrodes are provided in a portion in the length direction from the attached end to the free end. (3) (a) In a tube-type probe scanner, an internal Z is attached to the inner surface of the tube in a portion adjacent to the free end and not occupied by the inner scanning electrode to cover the entire inner surface of the tube. (b) an external Z-axis electrode attached to the outer surface of the tube adjacent the free end and in a portion not occupied by the outer scanning electrode to cover the entire outer surface of the tube; The tube-type probe scanner according to claim 2, characterized in that: (4) A claim characterized in that the lengths of the scanning electrode and the Z-axis electrode are each 1/2 or more of that of the tube (
3) The tube-type probe scanner described above. (5) (a) An internal scanning electrode located from the mounting end to the free end; (b) an external scanning electrode partially located between the mounting end and the free end; (c ) a Z-axis electrode attached to the outer surface of the tube in a portion adjacent to the free end and not occupied by the outer scanning electrode so as to cover the entire outer surface of the tube; The tube type probe scanner according to claim (1). (6) (a) an external scanning electrode located from the attachment end to the free end; (b) an internal scanning electrode located partially between the attachment end and the free end; (c) a Z-axis electrode attached to the outer surface of the tube adjacent to the free end and in a portion not occupied by the external scanning electrode so as to cover the entire outer surface of the tube; The tube type probe scanner according to claim (1). (7) The tube type probe scanner according to claim (1), wherein the inner and outer scanning electrodes of the tube extend from the attached end to the free end. (8) The tube is tapered from the attachment end toward the free end, so that the wall thickness of the side wall adjacent to the free end is thinner than that of the side wall adjacent to the attachment end. The tube-type probe scanner according to claim 1, characterized in that: (9) The tube-type probe scanner according to claim (1), wherein the wall thickness of the tube becomes thinner as it approaches the free end from the attached end. (10) The tube-type probe scanner according to claim (9), wherein the wall thickness is reduced at a plurality of steps provided between the attached end and the free end. (11) (a) A tube having a cylindrical side wall that is adjacent to the free end and has a wall thickness thinner in a portion of about 1/2 of the length than the side wall of the remaining portion adjacent to the attached end. (b) internal and external scan electrodes located on the side wall adjacent the attached end; and (c) internal Z-axis electrodes mounted on the inner surface of the tube on the side wall adjacent the free end. and (d) an external Z-axis electrode attached to the outer surface of the tube on a side wall adjacent to the free end. (12) (a) a tube having a tapered side wall such that the wall thickness becomes thinner toward the free end than toward the attachment end; (b) from the attachment end to the free end; (c) an internal scanning electrode located on the side wall; and (c) an external scanning electrode located on the side wall for approximately 1/2 the length of the tube in the direction from said attached end to said free end. a scanning electrode; and (d) an external Z-axis electrode attached to the outer surface of the tube over about 1/2 of its length from the free end toward the attached end. The tube-type probe scanner according to claim 1, characterized in that: