JPH0158456B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sample moving table for an ultrasonic microscope or the like, characterized in that the sample table is supported in a non-contact manner by a hydrostatic air bearing.

In recent years, it has become possible to generate and detect ultrahigh-frequency sound waves of up to 1 GHz, making it possible to realize sound wavelengths of approximately 1 μm underwater, and as a result, it has become possible to obtain high-resolution sound wave imaging devices. In other words, a concave lens is used to create a focused acoustic beam, achieving a high resolution of 1 μm.

By inserting a sample into the beam and detecting the reflected ultrasonic waves from the sample, we can elucidate the elastic properties of minute regions of the sample, or while mechanically scanning the sample in two dimensions, we can measure the intensity of this signal. By displaying this as a volatility signal on a cathode ray tube, it is possible to magnify the fine structure of the sample.

FIG. 1 is a diagram showing the main components of the ultrasound microscope. The focusing, transmission and reception of ultrasonic waves is carried out by a spherical lens 1, whose structure consists of optically polishing one side of a material made of cylindrical fused silica or the like, and then placing a piezoelectric thin film (ZnO) 2 on top of it with upper and lower electrodes 3. A pulse 5 generated from a pulse oscillator 4 is applied to the piezoelectric thin film 2 sandwiched in a sandwich structure to generate an ultrasonic wave 6. In addition, a concave hemispherical hole with a diameter of about 0.1 mmφ to 1.0 mmφ is formed at the other end, and a medium (for example, Water) 8 is fulfilled.

Ultrasonic waves 6 generated by the piezoelectric thin film 2 propagate in the cylinder as plane waves. When this plane wave reaches the hemispherical hole, quartz (velocity of sound 6000m/s) and water (velocity of sound
1500 m/s), a refraction effect occurs, and the focused ultrasonic waves 6 can be irradiated onto the surface of the sample 7. Conversely, the ultrasonic waves reflected from the sample 7 are collected and phased by a spherical lens, become plane waves, and reach the piezoelectric thin film 2, where they are converted into an RF signal 9. This RF signal 9 is received by a receiver 10,
Here, it is diode-detected and converted into a video signal 11, which is used as an input signal for the CRT display 12.

In the apparatus configured in this way, when the sample 7 is two-dimensionally scanned within the x-y plane by the sample stage drive power supply 13, the intensity of reflection from the sample surface as the sample scans changes two-dimensionally. displayed on surface 12.

The faster the scanning speed of the sample 7 is, the shorter the time it takes to form one screen, leading to improved operability, but conventionally commonly used scanning methods for the sample 7 are mechanical. For this reason, the x-axis scan is performed at several tens of Hz, and the y-axis scan is performed in about 10 seconds.

As mentioned above, in a device that irradiates ultrasonic waves onto a sample while scanning in the x-y plane and displays images using the ultrasonic waves reflected from the sample, changes in elastic properties near or inside the sample are detected. If there is, the amplitude and phase of the reflected ultrasound waves will change each time. Since this phase is sensitively affected by the distance between the spherical lens and the sample, the scanning sample surface and the focal plane of the ultrasonic beam must be configured so that they are always kept in the same spatial phase condition. Accuracy is a problem when scanning a sample, and the use of a hydrostatic air bearing is being considered as a sample moving table suitable for such an apparatus. The characteristic of this hydrostatic air bearing is that the sample stage is supported by the static pressure of the air supplied between the bearing and the sample stage, so the bearing has little frictional resistance and is free from wear. Furthermore, since the static air layer between the sample stage and the bearing surface acts as a buffer, the specimen moves smoothly without being affected by slight irregularities on the bearing surface.

FIGS. 2a and 2b show the structure of a sample moving stage using the above-mentioned hydrostatic air bearing, and FIG. 2b is a sectional view of FIG. 2a. In the figure, 14 is a guide portion. A compressed air outlet 15 is attached to the guide portion at a predetermined position, and the sample stage 16 is held by the compressed air discharged from the compressed air outlet 15. 17 is a compressed air intake port.
Further, 18 is a drive shaft of the sample stage 16.

By using a sample stage configured in this manner, the vertical movement of the sample during scanning can be kept to 0.03 μm or less, and it can operate extremely stably as a sample stage for ultrasonic microscopes and the like.

When performing observation experiments on various samples using the ultrasonic microscope described above, information that cannot be obtained using other observation devices such as an optical microscope can be obtained from the same part observed using the ultrasonic microscope, and the If the morphology and characteristics of a sample can be determined by integrating the results, the accuracy of the results obtained will be improved compared to those obtained from a single device.

FIG. 3 is a diagram showing an embodiment of a sample moving stage for realizing such a request. In this embodiment, a configuration will be described in which the same field of view as a sample observed with an ultrasonic microscope (indicated by an acoustic spherical lens 1) is observed with an optical microscope.

Coarse movement mechanisms 20 and 21, which are movable in the X and Y directions for selecting the field of view of the sample, are mounted orthogonally. Although not shown in the figure, x and y scanning units 22 and 23 for scanning the sample 7 in x and y are attached to the upper part thereof. Here, the x-scan section uses the hydrostatic air bearing type sample stage described in FIG. I am doing it by being there.

The y-axis scan can be moved by a step motor 25 in a direction perpendicular to the x-axis scan.

Further, a Z-axis moving mechanism 26 is attached to adjust the gap between the sample 7 and the spherical lens 1.

The optical microscope 27 is placed at a position separated from the axial center of the spherical lens 1 by a distance L in the x-axis direction so that the optical microscope 27 can observe the same field of view of the sample 7 observed with the ultrasonic microscope configured as described above. has been done.

Therefore, when the sample 7 that has been observed with the ultrasonic microscope is to be observed with the optical microscope 27, the sample stage 16 is separated from the sample stage drive shaft 18 and moved under the optical axis of the optical microscope 27. Must. In addition, in contrast to this operation, if the sample 7 is observed in advance with the optical microscope 27 and then observed with the ultrasonic microscope, the movement of the sample 7 is smooth and the height is high. Accurate position repeatability is required. In the present invention, a sample moving table having a structure as shown in FIG. 4 is used to realize this. That is, in the figure, by extending the guide portion 14 of the hydrostatic air bearing to a length that does not fall off even if the sample stage 16 moves onto the axis of the optical microscope 27, its function can be fully realized.

The above explanation is based on the distance L from the spherical lens 1 on the x-axis.
In this configuration, the optical microscope 27 is provided at the position where the optical microscope 27 is located, but instead of the optical microscope 27, a device having another observation function may be placed at this position. Further, although not shown in the figure, if the optical microscope 27 is left as is and another observation device is placed at a position a predetermined distance on the x-axis from the spherical lens 1, the guide portion 14 is extended to that device. do it.

If a plurality of observation devices are arranged on the x-axis and the stopper 28 is operated in conjunction with the movement of the sample stage 16 so that the sample stage 16 stops at a predetermined location under each observation device, The sample stage 16 is stopped within the same field of view under each observation device. Information can be acquired from each device while performing this work sequentially.

FIG. 5 is a side sectional view of a configuration in which the sample stage 16 can be moved by L using a static air bearing similar to that shown in FIG.

Now, to describe the case where the sample 7 at point A, which is being observed with an ultrasonic microscope, is to be moved to point B in order to be observed with an optical microscope, the sample stage 16 is connected to the vibrator 24 via the drive shaft 18. has been done. The simplest method for this connection is not shown in the figure, but it is convenient to connect them using the attractive force of an electromagnet.

For example, if you want to break the bond between the two, you can stop the excitation of the electromagnet and the two will naturally separate. By this method, the sample stage 16 is separated from the drive shaft 18 and the valve is removed at the same time.
When V ₁ is opened and compressed air is discharged from the pipe 29, the compressed air collides with the drive plate 31 attached to the bottom of the sample stage, a force is applied to move the sample stage 16, and the sample moves towards point B. The stand 16 moves. The compressed air used here has been branched from the compressed air used in the static air bearing, but since the sample stage is supported by the static air bearing, the air is blown onto the drive plate 31. Even if the pressure and volume of the applied air are extremely small, the sample stage 16 moves. Therefore, unnecessary vibrations are not generated in the measurement system.

The sample stage 16 that has reached point B is stopped at a predetermined position by the stopper 28. At this time, since the sample stage 16 is pressed against the stopper 28 by the wind pressure of the air blown against the drive plate 31 as described above, there is no need to provide any special locking means with respect to the sample stage 16. Also, at this time, the drive plate 39 is at the farthest position from the outlet of the pipe 29, so the drive plate 39
The wind pressure that 1 receives will be small, and there will be no vibration or other problems with observation.

The sample stage 16 that has reached point B is stopped at a predetermined position by the stopper 28. On the other hand, if you do not want to move the sample stage 16 at point B to point A, perform the opposite operation to the above, open V ₂ , and discharge compressed air from the pipe 30, and the sample stage 16 will move smoothly. Reach point A.

As mentioned above, in a device with multiple observation functions, the method of using hydrostatic air bearings to move the sample between each observation function is easy to operate and achieves high reliability. The effects of the present invention are remarkable.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of an ultrasonic microscope, Fig. 2 is a diagram showing the main components of a static air bearing, and Fig. 3 is a diagram illustrating the configuration of a compound observation device.
FIGS. 4 and 5 are diagrams showing the configuration of an embodiment of the present invention.

Claims (1)

[Claims] 1. A sonic lens provided with a piezoelectric element at one end and a spherical hole formed at the other end; a sample stage provided near the focal point of the sonic lens; and a scanning device that scans in two directions, and which photographs the sample by receiving ultrasonic waves emitted from the sonic lens and then disturbed by the sample. A sample moving stage used in In a device capable of moving the sample table, a static air bearing that extends in the direction in which the sample table moves and supports the sample table without contact, and a pipe that blows compressed air to a drive plate installed on the sample table. A sample moving stage is provided.