JP3799181B2 - Scanning probe microscope - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a scanning probe microscope having an uneven image observation mode and a magnetic force image observation mode.
[0002]
[Prior art]
After the birth of the scanning tunneling microscope (STM), the technological progress in the scanning probe microscope (SPM) is striking. Since the invention of the atomic force microscope (AFM), techniques for measuring various forces on the sample surface have been established. Among them, a magnetic force microscope (MFM) that measures the distribution of the surface magnetic field of a material has attracted attention in various fields. In particular, in the field of material development, thinning and miniaturization of materials are progressing in the field of magnetic materials, and due to the influence of the surface of such materials, it is expected that completely new materials different from conventional materials will be born. As a method for measuring the magnetic distribution on the sample surface, there is a Lorentz microscope in an electron microscope, but there is a limit in terms of resolution and the like. In that respect, MFM can be measured to a resolution of about several tens of nanometers, and an improvement in resolution is expected.
[0003]
FIG. 5 is a diagram for explaining an MFM image measuring method currently being performed.
The MFM technology uses the AFM technology as it is. In general, the tip of the cantilever is coated with a ferromagnetic material such as Fe, Co, Ni, and the magnetic moment from the sample surface is measured. . When the magnetic moment is measured very close to the sample surface, the unevenness effect on the sample surface appears in the MFM image, causing a problem in image interpretation. Therefore, in recent MFM measurement, in order to minimize the problem of unevenness on the sample surface, first, the cantilever (not shown) is scanned very close to the surface of the sample 1, and the uneven image 2 on the sample surface is detected by AFM. Then, the cantilever is lifted away from the sample surface by a certain distance in the Z direction, and the MFM image is observed on the next line. The MFM image thus observed becomes a lift image 3 in which the concavo-convex image and the magnetic force image are added as shown in the figure, and the MFM image can be obtained by subtracting the concavo-convex image 2. As a measuring method, there is a method of measuring the concavo-convex image and the MFM image for each line, as well as a method of measuring the concavo-convex image and the MFM image for each point.
[0004]
[Problems to be solved by the invention]
However, when measured by these methods, after observing the MFM image on the outbound scan, the cantilever is lifted back on the return scan, and then the cantilever is moved closer to the sample to observe the concavo-convex image. When scanning the cantilever, there is a problem of colliding with the sample and causing a crash, and a problem with the hysteresis and creep of the scanner consisting of the piezo element. There is a problem that an uneven image cannot be obtained, and as a result, the MFM image is not stable. In order to avoid this problem, a method of stopping for a certain period of time at the start of scanning and starting scanning after hysteresis disappears is used. However, even in normal SPM, where scanning speed is a problem, the speed becomes increasingly slower. This is not practical, and this may be a problem when trying to further improve the resolution in MFM.
[0005]
An object of the present invention is to solve the above-described problems, and an object of the present invention is to obtain a stable uneven image and lift image without reducing the scanning speed.
[0006]
[Means for Solving the Problems]
The present invention provides a scanning method of a concavo-convex image observation mode in which a cantilever is moved close to a sample to observe a concavo-convex image on the sample surface and a lift image observation mode in which the cantilever is lifted up and scanned to measure a magnetic moment on the sample surface. In the scanning probe microscope having the above, the scanning method is changed after the image observation, the return scanning is performed without the image observation display by the changed scanning method, and the next observation is performed by the changed scanning method after the return scanning. It is characterized by that.
In addition, the present invention provides a concavo-convex image observation mode in which a cantilever is moved close to a sample to scan and observe a concavo-convex image on the sample surface, and a lift image observation mode in which the cantilever is lifted up and scanned to measure the magnetic moment on the sample surface. In a scanning probe microscope having a scanning method, after the lift image is observed, the scanning method is changed to the concavo-convex image observation mode, and the scanning is performed in the concavo-convex image observation mode without performing image observation display, and the concavo-convex after the return scanning. The following observation is performed by a scanning method in an image observation mode.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
The present invention provides an image observation display in a scanning probe microscope having a mode in which a cantilever (not shown) is moved close to a sample to scan and observe an uneven image, and a lift image observation mode in which the cantilever is lifted up and scanned. The return scan is not used to minimize the hysteresis so that stable image observation can be performed.
[0008]
FIG. 1 is a diagram for explaining an observation method of the present invention, and FIG. 2 is a diagram for explaining a cantilever scanning method.
The concave / convex image is observed and displayed during the forward scanning in the concave / convex image observation mode (S1 in FIG. 2). That is, the cantilever is scanned close to the vicinity of the surface of the sample 1, and an uneven image on the surface of the sample is observed by AFM as shown in FIG.
At the time of the subsequent return scanning, the scanning mode is changed to the lift image observation mode, and at this time, the lift image is not displayed (S2 in FIG. 2). In other words, the cantilever is lifted up to perform a return scan. At this time, as shown in FIG. 1B, a lift image (uneven image + MFM image) is measured, but this image is not displayed. Hysteresis and the like caused by lift-up are attenuated during the return scanning period when the image observation display is not performed.
[0009]
Next, the scanning is performed while the cantilever is lifted up, and the lift image is observed (S3 in FIG. 2). That is, in order to minimize the problem of unevenness on the sample surface, the magnetic moment of the sample surface is measured while the cantilever is lifted up by a certain distance, and an uneven image and a magnetic force image are added as shown in FIG. Observe and display the lift image. In the observation of the lift image, there is no influence because the hysteresis is attenuated in the immediately preceding scan.
At the time of the subsequent return scanning, the scanning method is changed to the concavo-convex image observation mode, and the image is not displayed at this time (S4 in FIG. 2). In other words, the cantilever is lifted down so that it is very close to the surface of the sample 1 and, as shown in FIG. At this time, the uneven image is not displayed.
Subsequently, the process returns to S1 to observe the concavo-convex image. At this time, since the cantilever is not lifted down, the problems of hysteresis, creep, and crash do not occur. Thereafter, the image observation is performed by repeating this process.
[0010]
In this way, the return scanning method after observation of the concavo-convex image or lift image is changed so that the image is not displayed, and the next image observation is performed by the changed scanning method. Since the hysteresis decreases or disappears, it is not necessary to stop the scanning until the hysteresis disappears in the image observation in the subsequent scanning, and a problem such as a crash does not occur.
[0011]
FIG. 3 is a diagram for explaining another example of the observation method of the present invention, and FIG. 4 is a diagram for explaining a cantilever scanning method.
First, the concave-convex image is observed and displayed during the outgoing scan (S11 in FIG. 4). That is, the cantilever is scanned close to the vicinity of the surface of the sample 1, and an uneven image on the surface of the sample is observed by AFM as shown in FIG.
In the subsequent return scan, the image itself is not displayed in the mode of observing the concavo-convex image (S12 in FIG. 4). That is, while the cantilever is very close to the surface of the sample 1, the AFM scans the back of the sample surface by tracing the uneven image on the sample surface as shown in FIG. The image is not displayed.
[0012]
Next, the cantilever is lifted up to perform a forward scan, and a lift image is observed (S13 in FIG. 4). In other words, in order to minimize the problem of unevenness on the sample surface, the magnetic moment on the sample surface is measured by lifting the cantilever by a certain distance, and as shown in FIG. The added lift image is observed and displayed. In the observation of the lift image, the influence of the hysteresis of the scanner is smaller than that in the observation of the concavo-convex image, so that the problem is not so much.
[0013]
At the time of returning scanning, the image itself is not displayed in the mode for observing the uneven image (S14 in FIG. 4). That is, the cantilever is lifted down and scanned close to the surface of the surface of the sample 1, and the return scanning is performed by tracing the concavo-convex image on the surface of the sample by AFM as shown in FIG. At this time, the uneven image is not displayed.
[0014]
Subsequently, the process returns to S1 to observe the concavo-convex image. At this time, since the cantilever is not lifted down, the problems of hysteresis, creep, and crash do not occur.
[0015]
In this way, the cantilever is lifted down during the return scan so that the image is not displayed as the concavo-convex image observation mode, and the hysteresis of the scanner is reduced or eliminated during the return scan process. It is not necessary to stop scanning until the hysteresis disappears in image observation, and the problem of crash does not occur.
[0016]
【The invention's effect】
As described above, according to the present invention, since the hysteresis is minimized by using the return scanning without image observation display, the concavo-convex image and the lift image that are stable in the subsequent scanning without stopping the scanning. And the occurrence of a crash in the concavo-convex image observation mode can be prevented.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating an observation method of the present invention.
FIG. 2 is a diagram illustrating a cantilever scanning method.
FIG. 3 is a diagram for explaining another example of the observation method of the present invention.
FIG. 4 is a diagram illustrating a cantilever scanning method.
FIG. 5 is a diagram illustrating a conventional method for measuring an MFM image.
[Explanation of symbols]
1 ... Sample, 2 ... Uneven image, 3 ... Lift image.

Claims (2)

Scanning type with scanning method of concavo-convex image observation mode to scan the cantilever close to the sample and observe the concavo-convex image on the sample surface, and lift image observation mode to measure the magnetic moment of the sample surface by lifting the cantilever and scanning characterized in Puropu microscope, changes the scanning method after image observation performs scanning of return without the observed display image by scanning system after the change, the scanning scheme the change after return scan to make the following observations Scanning probe microscope. Scanning type with scanning method of concavo-convex image observation mode to scan the cantilever close to the sample and observe the concavo-convex image on the sample surface, and lift image observation mode to measure the magnetic moment of the sample surface by lifting the cantilever and scanning In the probe microscope, after the lift image is observed , the scanning method is changed to the concavo-convex image observation mode, and the scanning is performed in the concavo-convex image observation mode without performing the image observation display, and after the return scanning, the concavo-convex image observation mode is scanned. A scanning probe microscope characterized in that the following observation is performed by a method .

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