JPH08146014A - Scanning type probe microscope - Google Patents

Abstract

PURPOSE: To collect data with a high time resolving power by allowing a second transmission means to start transmission processing during the transmission of the analogue data of detected surface data by a first transmission means. CONSTITUTION: A drive circuit 2 generates analogue saw-tooth waves to drive a piezoelectric element 3 to send a data taking-in trigger signal to a CPU 1. A cantilever 4 detects the data on a sample to send an analogue signal 10 to an A/D converter row 6. The CPU 1 receiving the trigger signal outputs a changeover start signal 12 to a multiplexer 5. The multiplexer 5 changes over the A/D converters 6a-6n of the converter 6 successively on the basis of an A/D conversion start signal 13 to output a trigger signal to issue a command for the respective converters to latch analogue data and to start conversion. At this time, the converter 6a starts conversion and a command is issued for the converter 6b to perform latching of the analogue data and the start of conversion during the execution of conversion. When the conversion of the converter 6a has been completed, an FIFO buffer 7 inputs an A/D conversion completion signal 14 and a digital signal 11 to display an image on a host computer 9.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to scanning probe microscopes.

[0002]

2. Description of the Related Art The miniaturization of semiconductor products is constantly advancing, and steppers and electron beam lithography systems are capable of writing in the submicron region with a line width of 1 μm or less. Such miniaturization technology contributes to miniaturization of products manufactured thereby and improvement of processing speed. On the other hand, in the inspection of products, high precision and high resolution are required due to the miniaturization of samples. In addition, the inspection volume is increasing. Against this background, there is a demand for higher speed inspection equipment.

Further, it is necessary to perform observation with high time resolution even on a dynamic sample whose shape is changed such as a thermal change or a biological sample. For example, Japanese Unexamined Patent Publication No. 5-340712 discloses that data obtained during scanning is put in a frame memory to obtain a real-time image, but in this case, only one A / D converter is used. , The analog data is sequentially converted into digital data. A along the time axis
The processing steps of / D conversion-data acquisition-migration are repeated.

Further, Japanese Patent Laid-Open No. 6-50705 discloses A /
The process steps of D conversion, data collection, and transfer are repeated, and A / D is performed.
During the conversion time of conversion, it waits without collecting data. Further, Japanese Patent Laid-Open No. 6-50707 discloses that the surface of a sample is scanned in advance to store the unevenness of the surface, and then the Z direction control of the needle is quickly performed according to this unevenness information.

[0005]

However, in all of the above-mentioned conventional techniques, data is sequentially captured and the captured data is processed by one A / D converter. The acquisition process cannot be executed, and the scanning speed is limited by the A / D conversion time. Further, there is a drawback that the time resolution of data collection is also limited by the A / D conversion time.

The scanning probe microscope of the present invention has been made in view of such a problem, and a scanning probe microscope capable of collecting data with high time resolution and reliably capturing a change in a dynamic sample is provided. To provide.

[0007]

In order to achieve the above object, a scanning probe microscope of the present invention comprises a piezoelectric body on which a sample to be measured is placed, a driving means for driving the piezoelectric body, and the piezoelectric body. Of a plurality of transfer means for transferring analog data obtained by the detection means for scanning the sample to be measured to detect surface information of the sample when driven. Control means for controlling to start the transfer processing operation by the second transfer means while the first transfer means is executing the transfer processing.

[0008]

That is, the scanning probe microscope of the present invention drives the piezoelectric body to scan the sample to detect the surface information,
The obtained analog data is transferred by a plurality of transfer means. At this time, while the first transfer means of the plurality of transfer means is executing the transfer processing, control is performed so as to start the transfer processing operation by the second transfer means.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, an outline of a high-speed data acquisition process by a scanning probe microscope to which the present invention is applied will be described with reference to FIG. 1. An analog sawtooth wave is input to the drive circuit of the piezoelectric body (scanner) to scan the piezoelectric body smoothly and at high speed. 2. Unevenness on the sample surface is detected by the cantilever, and the shift signal is sent to a plurality of A / D converter rows connected in parallel. 3. The A / D converter array uses the signal for starting scanning on the x-axis as a trigger, and the piezoelectric body captures data at regular time intervals during scanning on the x-axis. 4. The A / D converter 1 receives the trigger signal from the CPU, thereby latching the analog signal and A / D the analog signal.
Convert. 5. CPU while A / D converter 1 is performing A / D conversion
Latches data in the next A / D converter 2 and A / D
Gives a trigger signal to start conversion. 6. When the A / D converter 1 finishes the A / D conversion, the A / D
Fi placed in the latter stage of the A / D converter row by the conversion end signal
A digital signal is input to the Fo (First In First Out) memory buffer. 7. The FiFo buffer further delivers digital data to the host computer one after another by the transfer circuit in the subsequent stage. 8. The same processing is performed thereafter until the A / D conversion by the A / D converter n is completed.

FIG. 1 is a block diagram of a high speed data acquisition type scanning probe microscope provided with a plurality of A / D converters in the first embodiment. First, the CPU 1 sends a scan start signal to the drive circuit 2. The drive circuit 2 has a built-in mirror integration circuit, generates analog sawtooth waves of X and Y to drive the piezoelectric body 3, and at the same time generates a trigger signal for data acquisition at the scanning start point of the X axis. Notify CPU1. The cantilever 4 detects the information on the sample and outputs the analog signal 10
Send to the / D converter row 6.

On the other hand, after the CPU 1 receives the trigger signal,
A switching start signal 12 for switching the A / D converters 6a to 6n is output to the multiplexer 5. The multiplexer 5 instructs each A / D converter in the A / D converter array 6 to latch analog data and start A / D conversion of the latched data. At this time, the A / D conversion start signal 13 is the first A / D converter 6 in the A / D converter array based on the precalculated instruction.
The trigger signal is output by sequentially switching from a to the nth A / D converter 6n.

First, the first A / D converter 6a starts the A / D conversion, and when the A / D conversion is in progress, the multiplexer 5 causes the first A / D converter 6a to perform the A / D conversion. Before the conversion is completed, the second A / D converter 6b is instructed to latch the data and start the A / D conversion. Similarly, the second A / D
While the converter 6b is A / D converting, the third A / D converter A / D
Issue D conversion instructions. In the same manner, after giving an instruction to start A / D conversion to the A / D converter 6n, the operation returns to the first A / D converter 6a again and the A / D converter 6a receives an A signal.
Give an instruction for / D conversion.

On the other hand, when the first A / D converter 6a finishes the A / D conversion, the digital signal 11 is output together with the A / D conversion end signal 14 and input to the FiFo buffer 7.
The digital signal that has entered the FiFo buffer 7 is transferred to the host computer 9 by the transfer circuit 8 in the subsequent stage and displayed on the image display display.

FIG. 3 is a block diagram of a scanning probe microscope in which a plurality of cantilevers (multi-probes) and a plurality of A / D converters are combined in the second embodiment. The high-speed data acquisition operation of such a scanning probe microscope will be described below.

First, the CPU 1 uses the digital position information 17
Is given to the drive circuit 2, the piezoelectric body 3 moves to a position corresponding to it. As a result, the surface of the sample placed on the piezoelectric body 3 is simultaneously scanned by the plurality of cantilevers, that is, the multi-probes 4 in the adjacent regions according to the arrangement. At this time, since the information signal of the sample surface, that is, the analog signal 10 is simultaneously output from the plurality of cantilevers 4a to 4m, the signal of the first cantilever 4a is selected by the probe multiplexer 15 and simultaneously by the A / D converter multiplexer 5. The A / D converter 6a of 1 is selected, the analog signal 10 is latched, and the A / D conversion is started. Then, when the first A / D converter 6a is still undergoing A / D conversion, the probe multiplexer 15 selects the second cantilever 4b, and the analog signal 10 obtained therefrom is selected by the A / D converter multiplexer. A / D is latched by the second A / D converter 6b selected by
Start conversion. Next, when the second A / D converter 6b is still in the A / D conversion, the probe multiplexer 1
5, the third cantilever 4c is selected, and the analog signal 10 obtained from the third cantilever 4c is selected by the A / D converter multiplexer 5
Then, the third A / D converter 6c selected by the above is latched and the A / D conversion is started. Hereafter, the same applies to the m-th
Repeat until the A / D conversion of the analog signal of the second cantilever is completed.

On the other hand, the first A / D converter 6a causes A / D
The D-converted digital signal 11 is the A / D conversion end signal 1
4 is input to the FiFo buffer 7, and then to the transfer circuit 8 to be sent to the host computer 9 having an image display. Further, the A / D-converted digital signals from the second, third, ..., Nth are similarly sent to the host computer 9. When the multi-lobe 4 and the A / D converter 6 finish the m-th and n-th (where m = n is the case) processings, the CPU 1 gives the next measurement coordinates to the drive circuit 2 and the piezoelectric body 3 moves. Move to the next measurement position.

The above processing is repeated to complete the measurement of the second point. By repeating the same procedure and scanning the two-dimensional plane of x and y, the surface information of the specific area of the sample × m areas can be obtained. 4 and 5 are flowcharts showing the operation of the second embodiment described above.

As described above, in the present embodiment, the scanning of the scanner is an analog scanning system so that the position is moved continuously and smoothly, and a plurality of A's are set from the scanning start point.
Since the analog data is captured one after another by the / D converter, data can be collected with high time resolution. Further, by collecting data with such a high time resolution, for example, a change in the sample surface during heating, a transient phenomenon when a current is applied to a semiconductor circuit,
Alternatively, it becomes possible to deal with a dynamic sample, such as capturing a dynamic change in a biological sample.

[0019]

According to the present invention, since the time interval for data collection can be shortened, data with high time resolution can be obtained and high-speed scanning with a high scanning speed is possible.
Further, since the speed is high and the time resolution is high, changes in the dynamic sample can be reliably captured.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a scanning probe microscope according to a first embodiment.

FIG. 2 is a diagram for explaining a high speed data acquisition process of the present invention.

FIG. 3 is a diagram showing a configuration of a scanning probe microscope according to a second embodiment.

FIG. 4 is a front part of a flowchart showing the operation of the scanning probe microscope according to the second embodiment.

FIG. 5 is a rear part of a flowchart showing the operation of the scanning probe microscope according to the second embodiment.

[Explanation of symbols]

1 ... CPU, 2 ... Drive circuit (sawtooth wave generation circuit), 3 ...
Piezoelectric body (stage scanner), 4 ... cantilever, 5 ...
Multiplexer, 6 ... A / D converter array, 7 ... FiFo buffer, 8 ... Transfer circuit, 9 ... Host computer, 10
... analog signal, 11 ... digital signal, 12 ... switch start signal, 13 ... A / D conversion start signal, 14 ... A / D conversion end signal.

Claims (1)

[Claims] 1. A piezoelectric body on which a sample to be measured is placed, a driving means for driving the piezoelectric body, and a detection for scanning the sample to be measured and detecting surface information thereof when the piezoelectric body is driven. Means, a plurality of transfer means for respectively transferring the analog data obtained by the detection means, and a second transfer means while the first transfer means of the plurality of transfer means is executing the transfer processing. And a control means for controlling to start the transfer processing operation by the scanning probe microscope.