JPH06117848A - Interatomic force microscope unit - Google Patents

Abstract

PURPOSE:To obtain an inexpensive interatomic force microscope which can be easily incorporated in an electron microscope as an attachment and can be reduced in size. CONSTITUTION:In an interatomic force microscope which is used for observing the surface of a sample 3 by detecting the displacement of a spring body 5 caused by the interatomic force acting between a probe 4 supported by the spring body 5 and the sample 3 when the sample 3 is brought nearer to the probe 4, The sample 3 is fixed to a driving means 2 fitted to a fitting base 1. The sample 3 fixed to the means 2, probe 4 fixed to the spring body 5, and a light receiving member 6 are constituted to a unit by fixing the probe 4 and member 6 to the free end side of the spring body 5 so that the probe 4 can be faced to the sample 3 and, at the same time, the other end of the spring body 5 to the base 1. By mounting the unit on the position where the sample 3 is irradiated with an electron beam 7 and irradiating the member 6 with the beam 7, a change in the position irradiated with the beam 7 is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention detects the displacement of a spring body due to an atomic force acting between the probe and the sample when the sample is brought close to the probe supported by the spring body, and the surface of the sample is detected. Atomic force microscope unit for observation.

[0002]

2. Description of the Related Art When a probe is supported by a cantilever and brought closer to the sample by about 10Å to 5Å, the force acting between the probe and the sample changes from attractive force to repulsive force (reaction force). The atomic force microscope detects changes in the cantilever bending angle based on this change and observes the sample surface by scanning the sample surface with a probe. A lever method, a cantilever and optical interference lever method, a spring displacement detection method by STM, and the like have been proposed.

The cantilever and the modulated light lever system detect a change in the amount of light corresponding to a change in the bending angle of the cantilever by irradiating the tip of the cantilever with laser light and detecting the reflected light. The optical interference lever method detects changes in interference fringes accompanying changes in the cantilever bending angle. Further, the spring displacement amount detection method by STM is to detect the displacement amount of the cantilever by detecting a tunnel current flowing when a bias is applied to the probe and the distance between the probe and the cantilever is approached to about 10Å.

[0004]

However, in the conventional method using the above laser light, the laser light irradiation device, the optical lever mechanism, and the photodetector must be directly connected to the sample table or firmly mounted in the vicinity thereof. Normally, a sample with a size of several mm is It is observed with a probe of several mm, but in order to detect the displacement of the cantilever with a laser, the stroke change of the order of Å must be magnified. Therefore, the device is large due to the optical system, and it is difficult to reduce the size, which is unsuitable as an attachment incorporated in an electron microscope. In addition, since the laser light irradiation device, the optical lever mechanism, and the components of the photodetector are required to have high accuracy, there is a problem that the price becomes high.

Further, the method using the STM is also unsuitable as an attachment to be incorporated in an electron microscope because it is difficult to downsize the apparatus because a tunnel microscope must be further mounted on the cantilever.

An object of the present invention is to solve the above-mentioned problems, and an object thereof is to provide an atomic force microscope unit which can be easily incorporated in an electron microscope as an attachment and which is inexpensive and can be miniaturized. It is a thing.

[0007]

To this end, the present invention detects displacement of a spring body due to an atomic force acting between the probe and the sample when the sample is brought close to the probe supported by the spring body. Then, in an atomic force microscope that observes the surface of the sample, the sample is fixed to the driving means mounted on the mounting base, and the probe and the light receiving member are fixed to the free end side of the spring body so that the probe faces the sample. Along with fixing the other end of the spring body to the mounting base, the sample fixed to the driving means and the probe and the light receiving member fixed to the spring body are unitized, and the unit is attached to the quantum beam irradiation sample position to form the light receiving member. It is characterized in that it is configured to irradiate a quantum beam and detect a change in the irradiation position of the quantum beam.

[0008]

In the atomic force microscope unit of the present invention, the sample is fixed to the driving means mounted on the mounting base using, for example, a piezo element, and the probe and the light receiving member are fixed to the free end side of the spring body to search. Since the needle is opposed to the sample and the other end of the spring body is fixed to the mounting base, the sample fixed to the driving means and the probe fixed to the spring body and the light receiving member are unitized, so that the device can be downsized, It can be easily incorporated as an attachment for an electron microscope or the like. Then, the light receiving member can be irradiated with a quantum beam such as an electron beam or an X-ray to detect a change in the quantum beam irradiation position and a change in the absorption current or the quantum beam from the light receiving member. You can observe the image.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B are views showing an embodiment of an atomic force microscope unit according to the present invention. FIG. 1A is a top view, FIG. 1B is a front view, and FIG. 1C is a relationship between a shake of a light receiver and an electron beam. Figure for explaining 1 is a mounting base, 2 is a piezo drive,
3 is a sample, 4 is a probe, 5 is a cantilever, 6 is a light receiver,
7 is an electron beam.

In FIG. 1, a mounting base 1 is a base on which a piezo drive unit 2 and a cantilever 5 are mounted. The piezo drive unit 2 is composed of three piezo elements on which the sample 3 is placed and which is driven in the three XYZ directions.
The cantilever 5 is a plate-shaped spring body that fixes the probe 4 and the light receiver 6 on the free end side so that the probe 4 faces the sample 3 and the other end is fixed to the mounting base 1. The light receiver 6 is
As shown in (c), the center part is divided into two parts by different materials composed of gold Au and carbon C, and the boundary of the center part is used as a reference line. As shown in (b) and (c), Is irradiated with an electron beam 7 that is narrowed to a predetermined diameter. When such a light receiver 6 is irradiated with the electron beam 7, secondary electrons are more likely to be emitted from Au as compared with C, so that the light receiver 6 is directed toward the electron beam 7 in the direction of arrow A as shown in (c). If the irradiation area of the electron beam to the light receiver 6 is the same, the ratio of the irradiation area of the electron beam 7 to Au and the irradiation area of the electron beam 7 to C changes. As a result, the amount of secondary electrons generated from the Au side and the amount of secondary electrons generated from the C side change, so that the displacement of the photodetector can be detected from the change in the amount of these secondary electrons. .

With the AFM unit as described above, it is mounted at an electron beam irradiation position of an electron microscope or the like to irradiate an electron beam, and the XY piezo element of the piezo drive unit 2 is driven to perform secondary scanning while XY scanning the sample. The displacement of the light receiver 6 can be detected by detecting the electrons, and an observation image of the sample surface can be output by the displacement detection signal. Further, the piezo elements of the piezo drive unit 2 are driven to detect secondary electrons while XY scanning the sample, and the Z piezo elements of the piezo drive unit 2 are driven so that the secondary electrons become constant. As a result, it is possible to output an observation image of the sample surface by the drive signal of the Z piezo element.

FIG. 2 is a view showing another embodiment of the present invention in which an AFM (atomic force microscope) unit is incorporated in an electron microscope, and FIG. 3 is an enlarged view of the AFM unit. In the figure, 11 is a sample chamber, 12 is an electron gun, 13 is an electron beam, and 14
Is a lens, 15 is an AFM unit, 16 and 17 are detection means, 18 and 19 are display means, 21 is a reflection electron / secondary electron, 22 is a transmission electron / reflection electron (diffraction), 23 is a light receiver, and 24 is a cantilever. , 25 is a probe, 26 is a sample, and 27 is a piezo element.

In the embodiment shown in FIG. 2, an electron beam 13 from an electron gun 12 is controlled by a lens 14 to irradiate a photodetector of an AFM unit 15, and reflected electrons detected by the photodetector.
The secondary electrons 21 are detected by the detection means 16 and displayed on the display means 18, and the transmitted electrons / reflected electrons (diffraction) 22 detected from the light receiver are detected by the detection means 17 and displayed on the display means 19.
It is configured so that it can be displayed. A
As shown in the enlarged view of FIG. 3, the FM unit 15 has a light receiver 23 attached to the back surface of the surface of the cantilever 24 to which the probe 25 is attached, and by irradiating the electron beam 13 from above, the light receiver 23 is exposed. Reflected electrons and secondary electrons 2 above
1 is detected, and transmitted electrons / secondary electrons (diffraction) 22 are detected below the light receiver 23.

FIG. 4 is a diagram showing another embodiment of the atomic force microscope according to the present invention for detecting the absorption current of the light receiver, and FIG.
It is a structure diagram of another embodiment of the FM unit. In the figure,
41 is a sample chamber, 42 is an electron gun, 43 is an electron beam, 44 is a lens, 45 is an AFM unit, 46 is a current extraction line,
47 is a current detection terminal, 48 is a current detection means, 49 is a display means, 51 is a reflected electron / secondary electron, 52 is a transmitted electron / reflected electron (diffraction), 53 is a light receiver, 54 is a cantilever,
55 is a probe, 56 is a sample, 57 is a piezo element, 58
Is a mounting base, and 59 is an insulator.

In the embodiment shown in FIG. 4, the electron beam 43 from the electron gun 42 is controlled by the lens 44 to irradiate the photodetector of the AFM unit 45, and the absorption current of the photodetector is detected from the current extraction line 46. Current detection means 48 through terminal 47
And an observation image of the sample surface due to the absorption current is displayed on the display means 49. Therefore, as shown in FIG. 5, the mounting base 58 is electrically insulated from the mounting side of the cantilever 54 by the insulator 59 and floated, and the current take-out wire 4 is attached to the cantilever 54.
6 are connected. Therefore, when the light receiver 53 is shaken and displaced, the irradiation amount of the electron beam with respect to Au and C of the light receiver 53 changes due to the displacement, and the absorption current on the Au side and the absorption current on the C side of the light receiver 53 changes. Therefore, the amount of displacement of the light receiver 53 can be detected from this amount of change.

The present invention is not limited to the above embodiment, but various modifications can be made. For example, in the above embodiment, the light receiver is attached to the cantilever, the light receiver is irradiated with an electron beam, and secondary electrons, backscattered electrons, transmitted electrons, diffracted electrons are detected, and absorption current is detected. Other quantum rays such as scattered electrons and characteristic X-rays may be detected, or X-rays and other quantum rays may be irradiated instead of the electron rays. Although the probe and the light receiver are attached to the cantilever, it goes without saying that the probe and the light receiver may be attached to the other end of the spring with one end fixed, or other spring-based attachment mechanism may be adopted. Nor.

The light receiving member is a combination of Au and C. However, if the detected amount of the quantum rays is different when the irradiation area of the quantum rays is changed, other different materials may be combined. A repeating pattern of different materials may be used, or a special shape, a hole, or a pattern may be provided to detect the displacement of the light receiving member. Further, in this case, although the probe squeezed to a predetermined diameter is irradiated, it may be configured to detect the displacement of the reference line by scanning the light receiving material surface in a certain area with a thin beam, or to shift the light receiving member. It may be viewed as a scanning image or a transmission image of an electron microscope.

[0018]

As is apparent from the above description, according to the present invention, the sample is mounted on the driving unit using the piezo,
Since it is only necessary to attach a small light receiver to the spring body that supports the probe above the sample, the modulated optical lever part unlike the conventional example is not required, and the device can be downsized, and it can be used as an AF for electron microscopes.
Even when the M device is incorporated as an attachment, it can be incorporated in the pole piece gap, and the cost can be reduced. In addition, since it can be incorporated in an electron microscope as an attachment and irradiate the photodetector with quantum rays to detect changes in the quantum current and absorption current from the photodetector, the electron irradiation mechanism of the electron microscope and reflected electrons and secondary electrons can be detected. The atomic force microscope can be observed by using the detectors of electrons, transmitted electrons, diffracted electrons, etc. as they are to detect displacement.
Furthermore, since an electron beam deflecting device can be used, a wide area can be covered, and the image quality can be processed by controlling the electron beam.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of an atomic force microscope unit according to the present invention.

FIG. 2 is a diagram showing another embodiment of the present invention in which an AFM (atomic force microscope) unit is incorporated in an electron microscope.

FIG. 3 is an enlarged view of an AFM unit.

FIG. 4 is a diagram showing another embodiment of the atomic force microscope according to the present invention for detecting an absorption current of a light receiver.

FIG. 5 is a diagram showing the configuration of another embodiment of the AFM unit.

[Explanation of symbols]

1 ... Mounting base, 2 ... Piezo drive unit, 3 ... Sample, 4
... probe, 5 ... cantilever, 6 ... light receiver, 7 ... electron beam

Claims (3)

[Claims] 1. An atomic force for observing the surface of a sample by detecting the displacement of the spring body due to the atomic force acting between the probe and the sample when the sample is brought close to the probe supported by the spring body. In the microscope, fix the sample to the driving means mounted on the mounting base, and fix the probe and the light receiving member to the free end side of the spring body so that the probe faces the sample and the other end of the spring body to the mounting base. The probe fixed to the driving means and the probe fixed to the spring body and the light receiving member are unitized, the unit is attached to the irradiation position of the quantum beam, and the light receiving member is irradiated with the quantum beam to emit the quantum beam. Atomic force microscope unit characterized by being configured to detect changes in the 2. The atomic force microscope unit according to claim 1, wherein the sample fixing side and the spring body fixing side of the mounting base are electrically insulated, and a current extraction line is connected to the spring body fixing side. . 3. The atomic force microscope unit according to claim 1, wherein the light receiving member is formed by dividing the center portion into two parts made of different materials.