JPH0552711U - Cantilever for atomic force microscope - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to set the resolution to 300 Å or less. [Structure] The lever main body 21 has a pyramidal portion 23 formed on one surface of one end of a plate-like body and is composed of a conventional cantilever made of Si ₃ N _4, and a conductive layer 24 of Au is formed on the surface thereof. Carbon is deposited on the tip of the rib 23 by electron beam irradiation in vacuum, and the deposited carbon is grown by moving the electron beam to form the probe 22. The diameter of the probe 22 is less than 300Å and the length is 200.
About Å, and the radius of curvature of the tip is 300 Å or less.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to an atomic force microscope and a cantilever used for sample surface exploration of an apparatus using the principle.

[0002]

[Prior Art]

 The atomic force microscope deflects the cantilever due to the atomic force between the probe attached to the free end of the cantilever and the sample, and detects this deflection using laser light, while controlling the cantilever to a constant state. It is used for scanning the surface of the sample and measuring the unevenness of the sample surface from the control signal.

FIG. 3A shows a conventional cantilever of this type. A pyramidal probe 12 is formed on one surface of one end of the plate-shaped lever body 11. This cantilever is SiO₂, S i₃N_Four, Si and the like. For example, with respect to single crystal silicon, a mold of the probe 12 is formed by using its anisotropic etching. ₂ And Si₃N_FourWas filled in to make the probe 12 with high dimensional accuracy. The cantilever has a small spring constant such that it is easy to make and can detect the magnitude of the atomic force, and it has a high natural resonance frequency to enable high-speed scanning.₃N_FourOften consists of

[0004]

[Problems to be solved by the device]

 In the conventional cantilever, even if the apex angle θ of the probe 12 (Fig. 3B) is narrow, it is about 25 °, and it is impossible to accurately measure a fine pattern such as a chip pattern of an IC element. As shown in the figure, when the sample pattern has fine and deep grooves 13, the probe 12 does not reach the bottom surface of the groove, and the probe cannot move along the inner surface shape of the groove 13, and the shape is measured. I can't.

[0005]

According to this invention, a probe made of a deposited conductive material is attached to the end of the lever body.

[0006]

【Example】

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

The lever body 21 has a spring constant of about 0.5 Newton / m because it is necessary to respond to an atomic force (about 10 ⁻¹¹ to 10 ⁻⁹ Newton), and may be an insulating material or a metal material. The lever body 21 has a length of, for example, several thousand Å, a width of about 200 to several thousand Å, and a thickness of about 2 to 10 Å. In the example of FIG. 1A, the probe 22 is formed on the conventional cantilever, and therefore the lever body 21 and the pyramidal portion 23 are made of an insulating material such as Si ₃ N ₄ . Since the deposited conductive material probe 22 is deposited on the lever body 21 made of an insulating material in this manner, the conductive layer 24 is formed on at least the outer peripheral surface of the pyramidal portion 23 and the surface of the lever body 21 on the pyramidal portion 23 side. Has been formed. The conductive layer 24 may be formed by sputtering or coating of Au, for example, to a thickness of about 50 to 100Å, or when the lever body 21 is Si, the conductive layer 24 may be formed by ion implantation or diffusion of impurities. ..

The probe 22 is formed, for example, by depositing carbon on the tip of the pyramidal portion 23. That is, the lever body 21 is placed in a vacuum container (for example, a vacuum degree of about 10 ^-7 torr), and an electron beam with a diameter of about 20 to 30 Å is applied to the pyramid at an acceleration voltage of 10 to 30 kV and an emission current of 5 to 20 μA. Irradiate the tip of the shaped portion 23 from the side or the front. As a result, gases such as hydrocarbons remaining in the vacuum container and oil of the rotary pump are decomposed by the electron beam, become carbon and are deposited on the pyramidal portion 23, and the irradiation position of the electron beam is gradually formed. When the shape of 22 is moved so as to draw the shape, carbon deposition grows in the drawn shape and the probe 22 is obtained. When the irradiation time at the same position is increased, the carbon deposit grows thicker. The thickness of the probe 22 can be controlled by changing the acceleration voltage and the emission current. For example, it is possible to deposit with a length of about 500Å and a thickness of about 200Å in 1 second.

If the conductive layer 24 is not provided, the electron beam irradiation causes negative charges to be accumulated in the vicinity of the irradiation point, so that the electron beam is not efficiently irradiated and the electron beam is bent. However, it becomes difficult to form the probe 22 having a desired shape. Thus, the conductive layer 24 is formed, and the conductive layer 24 is grounded, for example, to prevent the accumulation of negative charges. Although the lever body 21 needs to be conductive when the probe 22 is deposited and formed as described above, the lever body 21 does not need to be conductive after the probe 22 is deposited, and therefore, the conductive layer 24 may be formed if necessary. May be removed.

As described above, since the deposited carbon probe 22 can be remarkably thinned, even if a fine groove 13 exists on the sample surface as shown in FIG. The tip of the probe 22 can be brought close to or grounded, the probe 22 can be moved along the inner surface of the groove 13, and its shape can be accurately measured. Further, as shown in FIG. 1C, a potential is applied from the power supply 25 to the probe 22 through the conductive layer 24, and the repulsive force or suction force with respect to the surface potential of the sample 26 is measured to measure the surface potential of the sample 26. You can also In this case, the lever body 21 is made to be conductive depending on whether it is made of metal or a conductive layer 24 is formed on an insulating material.

As shown in FIG. 2A, the probe 22 may be formed substantially at a right angle on the plate surface of the one end of the plate lever body 21. Further, as shown in FIG. 2A, it is also possible to measure the shape of the inner wall surface of the groove 13 by bending the end portion of the probe 22 into a letter shape. Such a probe is convenient for measuring the potential of the conductive layer 27 which is embedded in the sample 26 of an insulating material and exposed on the wall surface of the groove 13 as shown in FIG. 2B. As the deposited conductive material forming the probe 22, W is deposited by electron beam irradiation in an atmosphere of W (CO) ₆ , or electron beam irradiation is performed in an atmosphere of organic metal such as Al (CH) ₃ to obtain Al. Other conductive materials such as deposited may be used. Further, the present invention can be applied not only as a cantilever of an electron force microscope in a narrow sense, but also to a cantilever of a device for testing an IC chip by using the principle of the electron force microscope.

[0012]

[Effect of the device]

 As described above, according to the present invention, since the probe of the deposited conductive material is used, it is easy to set the wire diameter to 300 Å or less, and thus it is possible to obtain the high resolution, and the fine sample It is possible to correctly measure the shape of the groove and the electric potential of the fine pattern.

[Submission date] November 13, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

The lever body 21 has a spring constant of about 0.5 Newton / m because it is necessary to respond to an atomic force (about 10 ⁻¹² to 10 ⁻⁷ Newton), and may be an insulating material or a metal material. The length of the lever main body 21 is, for example, about several thousand Å to 200 μm , the width is about 200 Å to 20 μm , and the thickness is about 1 μm . In the example of FIG. 1A, the probe 22 is formed on the conventional cantilever, and therefore the lever body 21 and the pyramidal portion 23 are made of an insulating material such as Si ₃ N ₄ . Since the deposited conductive material probe 22 is deposited on the lever body 21 made of an insulating material as described above, the conductive layer 24 is formed on at least the outer peripheral surface of the pyramidal portion 23 and the surface of the lever body 21 on the pyramidal portion 23 side. Has been done. The conductive layer 24 is formed by sputtering or coating of Au, for example, to a thickness of about 50 to 1000 Å, or when the lever body 21 is Si, the conductive layer 24 is formed by ion implantation or diffusion of impurities. May be.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

The probe 22 is formed, for example, by depositing carbon on the tip of the pyramidal portion 23. That is, the lever main body 21 is arranged in a vacuum container (for example, a vacuum degree of about 10 ^-7 torr), and an electron beam having a diameter of about 10 to 30 Å is applied to an accelerating voltage of 10 to 30 kV, 10 ^-9 to 10 ^-10 A. The tip of the pyramidal portion 23 is irradiated laterally or from the front with an irradiation current of the order of magnitude . As a result, gases such as hydrocarbons remaining in the vacuum container and oil of the rotary pump are decomposed by the electron beam, become carbon, and are deposited on the pyramid-shaped portion 23, so that the irradiation position of the electron beam of the probe 22 is gradually made. When the shape is moved so as to draw a shape, carbon deposition grows in the drawn shape and the probe 22 is obtained. When the irradiation time at the same position is extended, the carbon deposit grows thicker. The thickness of the probe 22 can be controlled even when the acceleration voltage or the emission current is changed. For example, it is possible to deposit with a length of about 500Å and a thickness of about 200Å in 1 second.

[Brief description of drawings]

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

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

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

Claims (1)

[Scope of utility model registration request] 1. A cantilever for an atomic force microscope, wherein a probe made of a deposited conductive material is attached to an end of a lever body.