JP2593887Y2 - Cantilever for atomic force microscope - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an atomic force microscope and a cantilever used for searching a sample surface of an apparatus utilizing the principle.

[0002]

2. Description of the Related Art In an atomic force microscope, a cantilever bends due to an atomic force between a probe attached to a free end of a cantilever and a sample, and this bend is detected using a laser beam.
A sample surface is scanned while controlling the cantilever to be in a constant state, and the control signal is used for measurement of unevenness of the sample surface.

FIG. 3A shows a conventional cantilever of this type. A pyramidal probe 12 is formed on one surface of one end of the plate-like lever body 11. This cantilever is Si
It is composed of an insulator such as O ₂ , Si ₃ N ₄ , and Si. For example, for a single crystal silicon, a mold of the probe 12 is formed by using the anisotropic etching, and
The probe 12 with high dimensional accuracy has been made by filling with iO ₂ or Si ₃ N ₄ . The cantilever is often made of Si ₃ N _{4 because} it has a small spring constant enough to make it easy to detect the magnitude of the atomic force and raises the natural resonance frequency to enable high-speed scanning. .

[0004]

In the conventional cantilever, even if the apex angle θ of the probe 12 (FIG.
It is about 5 °, and it is not possible to accurately measure a fine pattern such as a chip pattern of an IC element. In particular, as shown in FIG. The probe 12 does not reach, and the probe cannot be moved along the inner surface shape of the groove 13,
Its shape cannot be measured.

[0005]

According to the present invention, a cantilever for an atomic force microscope is provided with a carburetor at an end of a lever body.
A linear probe made of deposited conductive material is attached,
The probe has a wire diameter of 300 mm or less, a length of 300 mm or more,
The radius of curvature is 300 ° or less.

[0006]

FIG. 1A shows an embodiment of the present invention. For example, a probe 22 made of a deposited conductive material is attached to one end of the plate-shaped lever main body 21 at a substantially right angle to the plate surface of the lever main body 21. In this example, a conventional cantilever is used as the lever body 21, and a pyramid-shaped portion 23 formed at its free end is used.
A probe 22 is attached to the tip of a (conventional probe) so as to extend this axis. The probe 22 has, for example, a wire diameter of 300 mm or less and a length of 300 mm or more, preferably 1 mm or more.
μ, and the radius of curvature of the tip is 300 ° or less.

The lever body 21 has an atomic force ( 10 ^-12 to 1).
( ^{Approximately 0-7} Newtons), the spring constant is set to approximately 0.5 Newtons / m, and either an insulating material or a metal material may be used. The length of the lever body 21 is, for example, several thousand Å .
About 200μm , width about 200mm ~ 20μm , thickness about
It is about 1 μm . In the example of FIG. 1A, the probe 22 is formed on a conventional cantilever. Therefore, the lever main body 21 and the pyramid-shaped portion 23 are made of an insulating material such as Si ₃ N ₄ . Thus, the insulating lever body 21
A conductive layer 24 is formed on at least the outer peripheral surface of the pyramid-shaped portion 23 and the surface of the lever body 21 on the side of the pyramid-shaped portion 23 in order to deposit and form the deposited conductive probe 22. Conductive layer 2
For example, the conductive layer 24 may be formed by sputtering or coating Au to a thickness of about 50 to 1000 °, or when the lever body 21 is Si, by ion implantation or diffusion of impurities.

The probe 22 is formed by depositing, for example, carbon on the tip of the pyramidal portion 23. That is, the lever body 21 is disposed in a vacuum container (for example, a degree of vacuum of about 10 ⁻⁷ torr), and an electron beam having a diameter of about 10 to 30 ° is accelerated at an acceleration voltage of 10 to 30 kV and about 10 ⁻⁹ to 10 ⁻¹⁰ A.
The tip of the pyramidal portion 23 is irradiated from the side or front with the irradiation current of. As a result, the gas such as hydrocarbons remaining in the vacuum vessel and the oil of the rotary pump are decomposed by the electron beam, become carbon, and are deposited on the pyramid-shaped portion 23. When the probe is moved so as to draw a shape, carbon deposition grows on the drawn shape, and the probe 22 is obtained. If the irradiation time at the same position is increased, the carbon deposition grows thicker.
Probe 2 even when accelerating voltage and emission current are changed
2 thickness can be controlled. For example, deposition with a length of about 500 ° and a thickness of about 200 ° can be performed in one second.

If the conductive layer 24 is not provided, the electron beam irradiation causes negative charges to accumulate in the vicinity of the irradiation point, so that the electron beam irradiation is not efficiently performed and the electron beam is bent. Probe 22 of desired shape
Is difficult to make. Therefore, the conductive layer 24 is formed,
The conductive layer 24 is grounded, for example, to prevent accumulation of negative charges. When the probe 22 is deposited and formed as described above, the lever main body 21 needs to be conductive. However, after the probe 22 is deposited, the lever main body 21 may not be conductive. May be removed.

As described above, the deposited carbon probe 22
Since the diameter of the probe 22 can be significantly reduced, the tip of the probe 22 can approach or touch the bottom surface of the groove 13 even if there is a fine groove 13 on the sample surface as shown in FIG. 1B, for example. Probe 2 along the inner surface of groove 13
2 can be moved, and its shape can be measured correctly. Further, as shown in FIG. 1C, a potential is applied from a power supply 25 to the probe 22 through the conductive layer 24, and the sample
The surface potential of the sample 26 can be measured by measuring a repulsive force or a suction force with respect to the surface potential of the sample 26. In this case, the lever main body 21 is made of a metal or a conductive layer 24 formed on an insulating material to be conductive.

As shown in FIG. 2A, the probe 22 may be formed substantially at right angles to the plate surface at one end of the plate-like lever main body 21. It is also possible to measure the shape of the inner wall surface of the bent grooves 13 end of the probe 22 to Gyakuku <br/> shape as shown in FIG. 2 B. According to such a probe, as shown in FIG. 2C , it is convenient to measure the potential of the conductive layer 27 which is embedded in, for example, an insulating sample 26 and is exposed on the wall surface of the groove 13. As the deposited conductor constituting the probe 22, W
W is deposited by irradiating an electron beam in an atmosphere of (CO) ₆ ,
Alternatively, another conductive material may be used, such as depositing Al by irradiating an electron beam in an atmosphere of an organic metal, for example, Al (CH) ₃ . In addition, not only cantilever of electron force microscope in a narrow sense, but also IC
The present invention can be applied to a cantilever of a device for testing a chip.

[0012]

As described above, according to the present invention, since the probe of the deposited conductor is used, it is easy to reduce the wire diameter to 300 mm or less, and therefore, it is possible to achieve a high resolution. It is possible to correctly measure the shape of the fine groove of the sample and the potential of the fine pattern.

[Brief description of the drawings]

1A is a cross-sectional view showing an embodiment of the present invention, B is a cross-sectional view showing a state in which a groove of a sample is scanned using the cantilever, and C is a state in which the surface potential of the sample is measured using the cantilever. FIG.

FIG. 2A is a cross-sectional view showing another embodiment of the present invention, and FIGS. 2B and 2C are cross-sectional views showing main parts of still another embodiment.

FIG. 3A is a perspective view showing a conventional cantilever, and FIG. 3B is a view for explaining the problem.

Claims (1)

(57) [Scope of request for utility model registration] The end portion of claim 1. A lever body, linear probe consisting of carbon deposits conductive material is attached, the probe
The wire has a wire diameter of 300 mm or less, a length of 300 mm or more, and a half curvature.
A cantilever for an atomic force microscope having a diameter of 300 ° or less .