JPH06102006A - Fabrication of probe for scanning probe microscope - Google Patents

Abstract

PURPOSE:To enhance resolution of scanning probe microscope. CONSTITUTION:Silicon oxide 13 is deposited on a silicon substrate 11 and then a groove is made through etching. The groove part is oxidized to produce silicon oxide 12 and a film A14 is formed on the entire surface and subsequently patterned into lever shape. A supporting base 15 is then bonded through the film A14 to the silicon substrate 11 from which the silicon oxide 12 is removed through etching thus fabricating a probe for scanning probe microscope.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe used in a scanning probe microscope (SPM), and more particularly to a method of manufacturing a probe suitable for an atomic force microscope or a scanning friction force microscope.

[0002]

2. Description of the Related Art A conventional method for manufacturing a probe for an atomic force microscope will be described with reference to FIG. A silicon nitride protective film (23) is formed on one surface of the silicon substrate (21). This protective film (23)
Serves as a mask when forming a trench. After forming the protective film (23), the protective film (23) is formed by a lithographic method.
After removing a part of the silicon and exposing the silicon, the substrate (21) is immersed in an etching solution typified by an aqueous KOH solution, and utilizing the crystal plane orientation dependence of the etching rate, Form a trench.

After that, a silicon oxide film (22) is formed by a vapor phase growth method or the like so as to cover the inner wall of the trench portion (FIG. 22).
a). A silicon nitride film (24) is formed on the surface of the substrate (21) where the trench is formed (FIG. 22b). The support base (25) is bonded to the silicon nitride film (24) (FIG. 22c). Finally the silicon substrate
(21) and silicon oxide (22) are removed by etching to remove the needle tip (2
A probe for a scanning probe microscope (Fig. 22d) having a continuous flexible body was formed in 6).

[0004]

The probe formed by the conventional method can manufacture only a needle-shaped tip having a height of about 1.4 times the radius of the circumscribed circle of the pattern for forming the needle-shaped tip. could not. When such a conventional needle-shaped tip is used in an atomic force microscope, it is not possible to accurately measure a sample with a large difference in the unevenness of the sample surface, and it is difficult to observe the details of the sample. there were. Further, when used in a scanning frictional force microscope, there is a fatal problem that the sensitivity to the frictional force is lowered and the sample surface cannot be accurately observed.

Therefore, an object of the present invention is to provide a manufacturing method capable of manufacturing a probe for a scanning probe microscope, which can cope with samples having various sizes and shapes of irregularities on the surface of the sample.

[0006]

The present inventor observed samples having various differences in size and shape of irregularities on the surface of a sample using a conventional probe for an atomic force microscope. It was found that the projections on the sample surface can be accurately observed, but the resolution of the details of the recesses is poor and it is difficult to observe.
Further, when the conventional probe was used for the scanning friction microscope, it was found that the sample having a small difference in the in-plane friction coefficient of the sample surface was difficult to observe and the sensitivity to the friction force was small.

As a result of diligent research, the present inventor has confirmed that the reason for the poor resolution of the details of the recess and the difficulty of observation is that the probe tip cannot approach the bottom of the recess for accurate observation. Furthermore, the reason why it is difficult to observe a sample with a small difference in the in-plane coefficient of friction between the sample surface and the conventional probe is because the amount of torsion of the lever due to the friction between the sample surface and the probe tip is small. They found that they were less sensitive to force.

In order to solve these problems, the inventor of the present invention has made the length larger than that of the conventional needle-like tip (height about 1.4 times the radius of the circumscribed circle of the pattern for forming the needle-like tip). It has been found that the above problems can be solved by using a probe having a needle-shaped tip. Therefore, the present invention is
"First step: forming a mask of a silicon oxide film on a silicon substrate; second step: forming a groove by an etching method; third step: oxidizing the surface of the groove to form a silicon oxide film A step of forming a film A on the entire surface, and then patterning this into a lever shape; a fifth step: a step of joining a support to the silicon substrate through the film A; Step: removing the silicon substrate, the mask, and the silicon oxide film by etching; and a method for manufacturing a probe for a scanning probe microscope (claim 1) ".

[0009]

The function of the present invention will be described below. A silicon oxide film serving as a mask material for forming a needle-shaped chip is formed on a silicon substrate (11), and the silicon oxide film is partially removed by etching to form a trench. By oxidizing the inside of the trench, a silicon oxide film is formed on the inner wall of the trench. A film A (14) that will become the needle tip (16) is formed on this surface, and silicon oxide (12), (13) is formed so as to leave it.
To remove. With this, a needle-shaped tip can be manufactured.

Conventionally, silicon nitride was used as the mask material formed on the substrate, but in the present invention, silicon oxide is used. Therefore, the mask on the substrate made of silicon nitride has heretofore remained during etching for forming the needle-shaped chip. However, in the present invention, since the mask is made of silicon oxide, it is removed by etching together with the silicon substrate. Therefore, the chip becomes longer by the film thickness of the removed mask. Further, by making the mask made of silicon oxide as thick as possible, a longer chip can be formed.

By the operation of the present invention as described above, it is possible to manufacture a needle-shaped tip having a large ratio of the height of the tip to the thickness of the root of the needle-shaped tip (aspect ratio), that is, a long tip.

[0012]

[Embodiment 1] An embodiment of the present invention will be described below with reference to FIG.
Will be specifically described. As substrate material, thickness 400
Using a silicon single crystal substrate (11) with 100 μm orientation in μm,
A 5 μm thick silicon oxide film (13) is formed on the entire surface of the substrate (11) by a thermal decomposition method. Next, a part (4 μm square) of the silicon oxide film (13) is removed by using a lithography method. After that, the silicon substrate (1
1) is anisotropically etched with a KOH aqueous solution to form a pyramid-shaped trench having a depth of about 2.8 μm. The shape of this trench is determined by the crystal arrangement of the silicon single crystal, and when a substrate with 100 plane orientation is used,
The shape of the trench is a pyramid.

A silicon oxide film (12) is formed on the inner wall of the trench by the thermal oxidation method (FIGS. 1 and 1a). This silicon oxide (1
Since 2) is formed in a shape as shown in FIG. 1, a sharpened trench can be manufactured by utilizing this shape. After that, a film (14) (for example, silicon nitride) was formed on the entire surface by vapor phase epitaxy, and lever-shaped patterning was performed by lithography (FIGS. 1 and 1b).

A support (eg glass) (15) is bonded to the upper surface of this sample by the anodic bonding method (FIGS. 1 and 1c).
Finally, unnecessary silicon part (11), silicon oxide films (12) and (13)
Was removed by a wet etching method to manufacture a probe for a scanning probe microscope equipped with a needle-shaped tip (FIGS. 1 and 1d). As for the probe for the scanning probe microscope obtained in this way, the probe produced by the conventional method is 2.8 μm.
It has been confirmed that it has a height of 7.8 μm, and the aspect ratio is greatly increased.

[0015]

Second Embodiment Another embodiment of the present invention will be specifically described. A silicon single crystal substrate having a thickness of 380 μm and a 100-plane orientation is used as a substrate material, and a silicon oxide film having a thickness of about 6 μm is first formed on the entire surface by a sputtering method, and then a 5 μm square is partially oxidized by a lithography method. The film was removed, and silicon was anisotropically etched with a tetramethylammonium hydroxide aqueous solution to form a pyramid-shaped trench, and a silicon oxide film was formed in the trench by a thermal oxidation method in order to sharpen the inner wall shape. After that, a silicon nitride film was formed on the entire surface of this sample by a vapor phase growth method, and a lever-shaped patterning was performed by a lithography method. Support (eg glass) on top of this sample
By the anodic bonding method, and finally the unnecessary silicon part,
The silicon oxide film was removed by a wet etching method to prepare a probe for a scanning probe microscope equipped with a needle tip.

As for the probe for the scanning probe microscope thus obtained, the probe prepared by the conventional method is 3.5 μm.
It has been confirmed that it has a height of 8.5 μm, whereas it has a large aspect ratio.

[0017]

As described above, according to the present invention, a chip having an aspect ratio larger than that of a conventional needle-shaped chip can be manufactured. Therefore, if an atomic force microscope equipped with a probe having this tip, a scanning probe microscope such as a scanning friction force microscope is used, a sample with a large difference in the unevenness of the sample surface or a concave portion and a concave portion of the surface (or a convex portion and It is possible to observe a sample having a wide variety of surface shapes such as a sample having a small interval between convex portions) or a sample having a small difference in the coefficient of friction on the sample surface.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing a method for manufacturing a probe according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a conventional method for manufacturing a probe.

[Explanation of sign]

 Silicon substrate 12, 13, 22 ... Silicon oxide film 14 ..., Film A 23, 24 ... Silicon nitride film 15, 25. ... Supporting stand 16, 26 .... Needle-like tip

Claims (1)

[Claims] 1. A first step: a step of forming a mask made of a silicon oxide film on a silicon substrate; a second step: a step of forming a groove by an etching method; a third step: by oxidizing a surface of the groove. A step of forming a silicon oxide film; a fourth step: forming a film A on the entire surface and then patterning the film into a lever shape; a fifth step: joining a supporting base to the silicon substrate through the film A A step; a sixth step: a step of removing the silicon substrate, the mask, and the silicon oxide film by etching; and a method for manufacturing a probe for a scanning probe microscope.