JPH0465342B2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention is an ultrasound microscope, and in particular, it is capable of displaying a low-magnification ultrasound image of a wide area of a sample and a high-magnification ultrasound image of a minute part thereof. This relates to ultrasonic microscopes.

Conventional technology Conventionally, an ultrasonic head having an acoustic lens and a piezoelectric transducer was slightly vibrated in the
2. Description of the Related Art Ultrasonic microscopes are known that display an ultrasonic image of a sample on a CRT display device by projecting an ultrasonic beam while moving the sample in the axial direction to two-dimensionally scan the sample. Using such an ultrasound microscope, e.g.
When observing a sample with a flat surface such as an IC wafer, it is desirable to display a wide area of the sample on a low-magnification screen, and to further enlarge minute parts of the sample and display them on a high-magnification screen. In this case, first attach a low-resolution ultrasound head, display a low-magnification ultrasound image using the X-axis and Y-axis feed mechanisms, and then observe this image in more detail. Find the part that should be done, and
Drive the axial and Y-axis direction feed mechanisms to bring the desired area to the speculum position, replace the ultrasound head with a high-resolution one, and use the vibration device to display a high-magnification image of the desired area. I try to do that. In this case, while observing a low-magnification ultrasound image, the area to be observed at a higher magnification is searched for, so it is not possible to clearly know the positional relationship between the low-magnification image and the high-magnification image, and it is difficult to identify the area to be examined. There is a drawback that it cannot be done clearly. Furthermore, when positioning a region to be observed at high magnification at the speculum position while looking at a low-magnification image, there is also the disadvantage that a considerably troublesome operation is required and a considerable degree of skill is required. In addition, if you want to observe multiple parts of the sample at high magnification, after you have finished observing one part, switch to a lower-resolution ultrasound head again to display a wider image of the sample and observe this. However, this method requires the extremely troublesome work of searching for the next region to be inspected at high magnification, which has the disadvantage that the overall inspection time is significantly longer.

OBJECT OF THE INVENTION The purpose of the present invention is to eliminate the above-mentioned drawbacks, and to make it possible to obtain a low-magnification ultrasound image of a wide area of a sample and a high-magnification ultrasound image of any minute part within it with extremely simple operation. It can be tilted and displayed, and
The present invention aims to provide an ultrasound microscope that allows an observer to clearly grasp the positional relationship between both ultrasound images.

Summary of the Invention The ultrasonic microscope of the present invention includes an X-axis direction feeding mechanism and a Y-axis direction feeding mechanism that relatively move the sample and the ultrasonic head in the X-axis direction and the Y-axis direction;
A Z-axis direction feeding mechanism that relatively moves the sample and the ultrasonic head in the Z-axis direction, an excitation device that makes minute vibrations of the ultrasonic head in the X-axis direction, and an ultrasonic With the ultrasonic beam emitted from the sonic head focused inside the sample,
A first display unit that displays a low-resolution, low-magnification ultrasonic image obtained by relatively moving the sample and the ultrasonic head using the X-axis direction and Y-axis direction feeding mechanism to perform two-dimensional scanning over a wide range. a display device, a coordinate input device that can specify an arbitrary position in the ultrasonic image of the sample displayed on the first display device, and a coordinate input device that can specify an arbitrary position in the ultrasonic image of the sample displayed on the first display device; Two-dimensional scanning of a microscopic region is performed using the vibrating device and the Y-axis direction feed mechanism while driving the Z-axis feed mechanism to focus the ultrasonic beam emitted from the ultrasonic head on the surface of the sample. The present invention is characterized by comprising a second display device that displays the obtained high-resolution, high-magnification ultrasonic image.

Example The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an example of an ultrasonic microscope according to the present invention. An ultrasonic head 3 having an acoustic lens 1 and a piezoelectric transducer 2 is attached to an excitation shaft 4a of an excitation device 4. Sample to be tested 5
is placed on the sample stage 6, and the ultrasonic head 3 and sample 5
An ultrasonic propagation medium, such as water 7, is interposed between the two. In this example, the sample stage 6 is configured with an XY table, and is configured to be movable in the X and Y axis directions by an X-axis direction feeding mechanism 8 and a Y-axis direction feeding mechanism 9. The vibration device 4 vibrates the ultrasonic head 3 at high speed in a minute range in the X-axis direction, and can be configured with a moving coil device, for example. On the other hand, the X- and Y-axis direction feeding mechanisms 8 and 9 move the sample 5 over a wide range with respect to the ultrasonic head 3, and are configured, for example, by a linear drive mechanism equipped with a motor and a lead screw. be able to. In this example, a Z-axis direction feeding mechanism 1 is further provided to move the sample stage 6 in the Z direction, which is the projection direction of the ultrasonic beam.
0 is also provided so that the distance between the ultrasonic head 3 and the sample 5 can be adjusted. Furthermore, the sample stage 6 is supported by a goniometer, and the inclination of the sample stage can be adjusted by rotating it around the X and Y axes. This feature has been omitted for clarity of the drawing and will be described in detail later.

Next, the electric circuit portion of the ultrasonic microscope of the present invention shown in FIG. 1 will be explained.

A burst high-frequency pulse signal synchronized with the control signal from the control circuit 11 is generated from the high-frequency generator 12, amplified by the buffer amplifier 13, and then sent to the piezoelectric transducer 2 of the ultrasonic head 3 via the circulator 14. The burst high-frequency pulse signal is converted into an ultrasonic wave corresponding to the burst frequency. This ultrasonic wave is focused by an acoustic lens 1 to project an ultrasonic beam spot onto the sample 5, and its reflected waves are collected by the acoustic lens 1 and converted into electrical signals by a piezoelectric transducer 2. This received signal contains illegal unnecessary signals such as ultrasonic waves that have been internally reflected multiple times on the acoustic lens 1 and burst-like high-frequency pulse signals leaked from the circulator 14, so they are guided to the gate 15. By using a gate signal having a predetermined timing from the control circuit 11, only the received signal corresponding to the direct reflected wave from the sample 5 is extracted. This is passed through an attenuator 16 to a high frequency amplification circuit 17.
The signal is amplified by a mixer 18 and fed to a local oscillator 19
It is mixed with the local oscillation frequency signal from and converted into an intermediate frequency signal. This intermediate frequency signal is supplied to a detector 21 via an intermediate frequency amplifier 20,
After the envelope is detected here, the blanking circuit 2
Enter 2. A control signal is supplied from the control circuit 11 to the blanking circuit 22 to block unnecessary signals leaking from the gate 15 and extract only the received signal corresponding to the direct reflected wave from the sample 5. The output of the blanking circuit 22 is peak-detected by a peak detection circuit 23, and the detected output signal thus obtained is guided to one of the first and second scan converters 25 and 26 via a limiter 24. These scan converters are supplied with synchronization information signals related to the X-axis scanning period by the vibration device 4 and the sample stage 6 from the control circuit 11.
A synchronization information signal related to the X-axis and Y-axis scanning period of the limiter 24 is supplied, and the output image signals from the limiter 24 are sequentially temporarily stored in predetermined positions of the image memory in the scan converter. This is continuously and repeatedly read out according to the television scanning period, and synchronization information is added to convert it into a television signal.
An ultrasonic microscope image is obtained by supplying it to the first and second television image monitors 27 and 28 and reproducing the image. Furthermore, the control circuit 11,
A central processing unit 29 and a light pen 30 are provided for controlling the first and second scan converters 25 and 26.

In this embodiment, as described above, the first and second scan converters 25 and 26 are provided so that images for two screens can be stored. That is, first, a low-magnification image signal is extracted and stored in the first scan converter 25, and a low-magnification ultrasonic image of a wide area of the sample 5 is displayed on the first monitor 27.
Display as follows. While viewing this low-magnification ultrasonic image, the operator searches for a region to be observed at higher magnification, places the light pen 30 on the corresponding region, and inputs its coordinates to the central processing unit 29. The central processing unit controls the control circuit 1 according to the input coordinates.
1 to drive the X-axis and Y-axis direction feeding mechanisms 8 and 9 to position the region specified by the light pen 30 at the speculum position. Next, the vibration device 4
drive the Y-axis direction feed mechanism 9 to two-dimensionally scan the specified region, store the image signal in the image memory of the second scan converter 26, and display the high-magnification ultrasonic image of the minute region on the second monitor 28. Display above.
In this way, it is possible to display an ultrasonic image of a wide area of the sample and an enlarged ultrasonic image of any minute area within it, making it possible to clearly understand the positional relationship between the two observation areas. . In addition, by leaving the image signal stored in the first scan converter 25 as it is and specifying another minute region with the light pen 30, a new high-magnification ultrasound image of this region is displayed on the second monitor. It can be displayed on 28. In this case, the region designated by the light pen 30 may be displayed on the first monitor using, for example, a cursor.

As described above, according to this embodiment, a low-magnification image and a high-magnification image can be displayed, and this can be mainly controlled by the computer constituting the central processing unit 29. Next, the operation of each part will be explained in detail, focusing on the operation of the central processing unit 29.

FIG. 2 shows a flowchart when obtaining a low-magnification ultrasonic image. When obtaining a low-magnification ultrasonic image, as described above, the excitation device 4 is not driven, and the sample stage 6 is moved by the X-axis and Y-axis direction feeding mechanisms 8 and 9 to perform two-dimensional scanning. In this case, first, the position and range of two-dimensional scanning are specified. For example, as shown in FIG. 3, if the coordinates of points P ₀ and P ₁ in the range F _L to be two-dimensionally scanned are (X ₀ , Y ₀ ) and (X ₁ , Y ₁ ), respectively,
These coordinates are input by operating keys provided on the keyboard. At this time, if the speculum axis of the ultrasound head 3 is not at the point P ₀ (X ₀ , Y ₀ ), the X-axis and Y-axis direction feed mechanisms 8 and 9 are driven to move the speculum axis to the point P ₀ ( X ₀ , Y ₀ ). After the initial settings are completed in this way, the high-frequency pulse generator 12 is driven to project an ultrasonic pulse toward the sample 5, the reflected pulse is received, and the corresponding image signal is extracted by the gate 15. and stores it in the corresponding address location of the image memory of the first scan converter 25. Next, drive the X-axis direction feed mechanism 8 to move the sample stage 6 by one step in the X-axis direction.
A similar operation is performed to store the image signal at the next address position viewed in the X direction of the image memory. Repeat this operation until X-X ₁ is reached, and 1
The image information for the line is converted to the first scan converter 2.
The images are sequentially stored in one line of the image memory No. 5. Next, when X-X ₁ is reached, the X-axis direction feed mechanism 8 is driven to return it to the X-X ₀ position, and the Y-axis direction feed mechanism 9 is driven to move the sample stage 6 1 in the Y-axis direction.
After the step movement, the above-described operation is repeated to store the image signal of the second line in the second line of the image memory of the first scan converter 25. By repeating this operation until Y-Y ₁ ,
In the image memory of the first scan converter 25, one screen worth of image signals representing the wide range F _L in FIG. 3 is stored.

FIG. 4 is a flowchart showing the operation when obtaining a high-magnification ultrasonic image. While observing the low magnification image displayed on the first monitor 27 as described above, the user places the tip of the light pen 30 at the center of a desired area and drives the switch provided on the light pen. As a result, the center coordinates (Xm, Ym) of the desired site _FH are input to the central processing unit 29 as shown in FIG. In this case, the size of the field of view (D×W) is input in advance by operating keys on the keyboard. That is, X caused by the vibration device 4
The amplitude (scanning width) W in the axial direction and the scanning width D in the Y-axis direction by the Y-axis direction feeding mechanism 9 are input. This size can be changed over, for example, in four stages. The central processing unit 29 calculates the coordinates of the points P ₀ ′, P ₁ ′, and Pm of the minute portions in the following manner based on the input data D, W, Xm, and Ym described above.

P ₀ ′(X ₀ ′, Y ₀ ′)−P ₀ ′(Xm−W/2, Ym−D/
2) P ₁ ′(X ₁ ′, Y ₁ ′)−P ₁ ′(Xm+W/2, Ym+
D/2 Pm (Xm, Ym - D/2) Next, the X-axis and Y-axis direction feeding mechanisms 8 and 9 are driven via the control circuit 11 to move the ultrasonic head 3.
Align the speculum axis with point Pm. After making the initial settings in this way, the vibration excitation device 4 is driven to vibrate the ultrasonic head 3 in the X-axis direction.
emits an ultrasonic beam to the sample 5, receives the reflected wave, converts it into an electrical signal, processes it appropriately, and stores it in the image memory of the second scan converter 26. That is, when the vibration device 4 causes the ultrasonic head 3 to reciprocate once with the amplitude W and the position Xm is detected twice, the Y-axis direction feeding mechanism 9 is driven to move the sample stage 6 in the Y-axis direction. The ultrasonic head 3 is moved one pitch, and then the ultrasonic head 3 is made to reciprocate once in the X-axis direction. The image signal obtained by two-dimensionally scanning the minute portion F _H of the sample by sequentially repeating the above-described operation until Y-Y ₁ ' is reached can be stored in the image memory of the second scan converter 26. In this case, the second monitor 2
The enlarged image of the minute part F _H displayed on the first monitor 27 can be arbitrarily selected using the light pen 30 from among the low magnification images of the wide area F _L displayed on the first monitor 27. The positional relationship between both images can be clearly known. Further, if it is desired to display a high-magnification image of another minute part within the wide area F _L , it is only necessary to newly designate the position using the light pen 30, and the operation is very simple.

As mentioned above, it is necessary to use a low-resolution ultrasound head when displaying a low-magnification image of a wide area of the sample, and a high-resolution ultrasound head when displaying a high-magnification image of a minute area. . Although this can be done by changing the ultrasound head each time, the present invention allows the same ultrasound head to be used to display both low and high magnification images. This will be explained below.

FIG. 5A shows the positional relationship between the ultrasonic head 3 and the sample 5 when obtaining a low-magnification ultrasonic image. The distance l ₁ is adjusted so that the ultrasonic wave spot is focused within the sample 5 so that a large diameter ultrasonic spot is projected onto the surface of the sample 5 as shown in FIG. 6A. By selectively extracting the reflected waves from the surface of the sample 5, a low-magnification ultrasonic image can be obtained. On the other hand, when obtaining a high-magnification ultrasonic image, the distance _l2 between the two is set to 5 so that the ultrasonic beam emitted from the ultrasonic head 3 is exactly focused on the surface of the sample 5, as shown in FIG. 5B. Adjust the distance l ₁ longer than shown in diagram A. In this case,
As shown in FIG. 6B, the ultrasonic beam spot with the smallest diameter is projected onto the sample surface, high-resolution scanning is performed, and a high-magnification ultrasonic image is displayed. In this way, the ultrasonic head 3
The distance between the sample 5 and the sample 5 can be adjusted by driving the Z-axis direction feeding mechanism 10 shown in FIG.

As described above, in the ultrasonic microscope of this example, the sample stage 6 is supported by a goniometer, and the inclination in the X-axis and Y-axis directions can be adjusted. That is, as shown in FIG. 7, the goniometer 31 includes an X-axis adjustment motor 32 that rotates the sample stage 6 around the Y-axis to adjust the inclination in the X-axis direction, and a motor that rotates the sample stage 6 around the X-axis. Then Y
Y-axis direction adjustment motor 3 that adjusts the axial tilt
3 are provided, and these motors are appropriately driven so that the surface of the sample placed on the sample stage 6 is perpendicular to the projection direction of the ultrasonic beam. The operation will be explained below with reference to FIG.

FIG. 8 shows a flowchart for adjusting the inclination in the X-axis direction. First, the points P ₀ (X ₀ , Y ₀ ) and P ₁ (X ₁ , Y ₁ ) in FIG. The coordinates are input and the X-axis and Y-axis direction feeding mechanisms 8 and 9 are driven to move the sample stage 6 to the position of point P ₀ (X ₀ , Y ₀ ). Here, ultrasonic waves are emitted and the intensity of the reflected waves from the sample surface is detected. Figure 9 shows the ultrasonic head 3.
The horizontal axis represents the position Z in _the Z direction of It becomes ₀ . Therefore, the focus is adjusted and the maximum intensity V ₀ is memorized. Next, the X-axis direction feed mechanism 8 is driven to move one step in the X-axis direction, and the reflection intensity V at that position is measured. When this measured intensity V is smaller than the value obtained by subtracting the preset value α from the maximum intensity V ₀ ,
Move the sample stage one step again. In this way, detection is performed sequentially, and a certain point (X _o , Y ₀ ) is detected.
If the reflection intensity V _o becomes smaller than V _o -α, it is determined that there is an unacceptable inclination, and the position Z _o in the Z-axis direction at this position is determined. From these values, calculate the tilt angle α from α = tna ^-1 Z ₀ -Z _o /X _o -X ₀ , and drive the X-axis direction adjustment motor 32 to tilt in the opposite direction by the angle α. . The inclination in the X-axis direction can be corrected by sequentially performing the above-described operations until X= _X1 .

Next, move the adjustment table 6 to point P ₀ (X ₀ , Y ₀ ),
A similar operation is performed in the range from Y ₀ to Y ₁ in the Y-axis direction, and the Y-axis direction adjustment motor 33 is driven to correct the tilt in the Y-axis direction. In this way, the tilt can be corrected in both the X-axis and Y-axis directions, and a more accurate ultrasound image can be displayed.

The present invention is not limited to the embodiments described above, and can be modified and modified in many ways. For example, in the example described above, the first and second monitors were provided to display a low-magnification ultrasound image and a high-magnification ultrasound image, respectively.
A standalone monitor may be provided, and its screen may be divided into two halves, one of which displays a low-magnification image, and the other of which displays a high-magnification image. Also, in the example above,
Although a line pen was used as a means for inputting the coordinates of a minute site, it is also possible to input the coordinates using a cursor displayed on the monitor screen. Furthermore, by increasing the number of scan converters and monitors, it is also possible to display ultrasound images of two or more minute regions. In addition, in the above example, the X-axis and Y-axis
Although the axial feeding mechanism is used to move the sample stage, either or both of these mechanisms may be used to move the ultrasonic head.

Effects of the Invention According to the present invention, a wide area of a sample is scanned with a low-resolution ultrasonic beam, a low-magnification ultrasonic image is displayed, and the position of any minute part in the image is determined using a coordinate input device. The specified region is scanned with a high-resolution ultrasound beam and a high-magnification ultrasound image is displayed, making it possible to always clearly know the positional relationship between the two ultrasound images. , accurate and quick observations can be made. Furthermore, simply by newly specifying the position of a minute part, a high-magnification image of that part can be displayed, making the operation extremely simple. Moreover, the high-resolution ultrasonic beam and low-resolution ultrasonic beam can be switched by simply driving the Z-axis direction feed mechanism and changing the distance between the ultrasonic lens and the sample, without changing the ultrasonic lens. This makes it possible to improve operability and shorten the time required to obtain a low-magnification ultrasound image.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of an example of the ultrasound microscope of the present invention, Fig. 2 is a flowchart showing the operation when displaying a low-magnification ultrasound image, and Fig. 3 is a low-magnification image and a high-magnification image. Figure 4 is a flowchart showing the operation when displaying a high-magnification ultrasound image. Figures 5A and B are low-magnification and high-magnification displays using the same ultrasound head. Figures 6A and 6B are diagrams showing the positional relationship between the ultrasound head and the sample when displaying an ultrasound image of Figure 7 is a perspective view showing the goniometer mechanism that adjusts the tilt of the sample stage, Figure 8 is a flowchart showing the operation of tilt adjustment, and Figure 9 shows the position and reflection intensity of the ultrasonic head when adjusting the tilt. It is a graph showing the relationship. DESCRIPTION OF SYMBOLS 1... Acoustic lens, 2... Piezoelectric transducer, 3... Ultrasonic head, 4... Vibration device, 5...
...sample, 6...sample stage, 8...X-axis direction feeding mechanism, 9...Y-axis direction feeding mechanism, 10...Z-axis direction feeding mechanism, 11...control circuit, 25, 26...first, Second scan converter, 27, 28...first and second monitors, 29...central processing unit, 30...
...Light pen.

Claims (1)

[Claims] 1. An X-axis direction feeding mechanism and a Y-axis direction feeding mechanism for relatively moving the sample and the ultrasonic head in the X-axis direction and the Y-axis direction, and a moving mechanism for moving the sample and the ultrasonic head in the Z-axis direction. a Z-axis direction feed mechanism that moves the ultrasonic head relative to the ultrasonic head; a vibration device that causes the ultrasonic head to minutely vibrate in the X-axis direction; Low resolution and low magnification obtained by performing two-dimensional scanning over a wide range by relatively moving the sample and the ultrasonic head using the X-axis and Y-axis direction feeding mechanisms while focusing inside the sample. a first display device that displays an ultrasonic image of the sample; a coordinate input device that can specify an arbitrary position in the ultrasonic image of the sample displayed on the first display device; The minute part of the sample corresponding to the arbitrary position
High resolution obtained by driving the Z-axis feed mechanism to focus the ultrasonic beam emitted from the ultrasonic head on the surface of the sample, and performing two-dimensional scanning with the vibration device and the Y-axis feed mechanism. , and a second display device that displays a high-magnification ultrasound image. 2. The ultrasound microscope according to claim 1, wherein the arbitrary position specified by the coordinate input device is the center coordinate of a high-magnification ultrasound image.