JPH05214564A - Production of probe for interatomic force microscope - Google Patents

Abstract

PURPOSE:To provide the process for production of the probe for an interatomic force microscope which can produce a probe without contaminating a film forming device. CONSTITUTION:This process for production of the probe for the interatomic force microscope having a acicular chip and a flexible body part for supporting this acicular chip consists in forming a 1st film 23 on a semiconductor single crystal substrate 21, providing a recessed part 26 of the area of the bottom smaller than the area of an aperture on this substrate 21, oxidizing the inside wall of this recessed part 26 to form a 2nd film 24 on the inside wall of the recessed part, removing the substrate 21 around the recessed part and constituting the acicular chip the flexible body part of the 1st and 2nd films 23, 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an atomic force microscope probe.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIG. Conventionally, the following method has been used to manufacture a probe used in an atomic force microscope. That is, a protective film 13 of silicon oxide or silicon nitride is formed on both surfaces of the silicon substrate 11,
By removing a part of the protective film 13 by a lithography method,
The silicon substrate 11 is exposed. Then, the substrate 11 is
By immersing in an etching solution typified by a KOH aqueous solution and utilizing the dependence of the etching rate on the crystal plane orientation, a quadrangular pyramid-shaped recess or trench 12 is formed. Substrate 1 at this time
The cross-sectional shape of No. 1 is shown in FIG.

After that, the protective film 13 previously formed on the upper surface
While removing or leaving the above, a silicon oxide film or a silicon nitride film 14 is formed by a vapor phase growth method or the like so as to cover the inner wall of the trench 12 and the upper surface of the substrate 11. As the vapor deposition method, a chemical vapor deposition method (CVD), a low pressure chemical vapor deposition method (LPCVD), a physical vapor deposition method (PVD) or the like is used. Next, the film 13 on the lower surface of the substrate 11 is patterned to remove a part thereof (FIG. 4B). afterwards,
The upper surface film 14 is patterned into a desired shape by the lithography method (FIG. 4C), and finally the lower surface thin film 13 is formed.
Is used as a protective film to remove a part of the silicon substrate 11 by etching (FIG. 4D).

In this way, the thin film 14 provided on the inner wall of the trench 12 is used as the needle tip 14a, and the substrate 1
The probe 1 for an atomic force microscope having the thin film 14 formed on the surface of No. 1 as the flexible body 14b was formed. For the atomic force microscope, the tip portion 14 of the needle-shaped tip 14a of the probe 1 is used.
The repulsive or attractive atomic force acting between c and the sample is
The microscope detects the amount of bending of the flexible portion 14b and detects the unevenness of the sample surface.

[0005]

As described above, according to the conventional technique, the substrate 11 is immersed in an etching solution of a strong alkali such as KOH to form the trench 12, and then the CV is formed.
The substrate 11 was set in a film forming apparatus such as D, LPCVD, or PVD to form the thin film 14. After the trench is formed, sufficient cleaning is performed to wash away the etching solution, but with the current technology, it is inevitable that a trace amount of KOH or the like remains. Therefore, by setting a substrate contaminated with a small amount of KOH or the like in a film forming apparatus such as CVD, LPCVD, or PVD, the inside of the film forming apparatus becomes KO.
It had the drawback of being H-contaminated.

Since film forming apparatuses such as CVD, LPCVD and PVD are very expensive, a plurality of different kinds of thin films such as semiconductor thin films are formed by one film forming apparatus by exchanging film forming sources. That is, it is often reused. However, it is well known that when potassium ions and the like enter the semiconductor thin film, the performance of the semiconductor device is extremely deteriorated. Therefore, in the case of taking the probe manufacturing process as described above, an expensive film forming apparatus such as CVD, LPCVD, or PVD has to be dedicated to the probe manufacturing. However, even when it is used as a dedicated machine for manufacturing a probe, this contamination is accumulated during repeated film formation, and the flexible body 14
There is a fatal problem that it hinders the composition of the thin film 14 to be b from being kept constant, and it becomes impossible to keep the mechanical properties as a spring, which is the most important as a flexible body, constant between batches. Was.

It is an object of the present invention to provide a method for manufacturing a probe for an atomic force microscope, which can manufacture the probe without contaminating the film forming apparatus.

[0008]

In order to solve the above-mentioned problems, the present invention provides a probe for an atomic force microscope having a needle-shaped tip and a flexible body portion supporting the needle-shaped tip. In the manufacturing method of, on the semiconductor single crystal substrate,
A first coating is formed, a recess having a bottom area smaller than the opening area is formed on the substrate, and an inner wall of the recess is oxidized to form a second coating on the inner wall of the recess. A method for manufacturing a probe for an atomic force microscope is provided, characterized in that the substrate around the recess is removed and the first and second films form the needle tip and the flexible body.

[0009]

The operation of the method for producing a probe for an atomic force microscope of the present invention will be described below with reference to FIG.

In the present invention, first, a semiconductor single crystal substrate 2 is formed.
First, the first film 23 is formed. This first film 23
At least a part of it becomes a flexible body portion when completed. Further, the first film 23 serves as a mask for protecting the substrate other than the portion where the recess 26 is formed in the step of forming the next recess 26. Therefore, as the material of the first film 23, a material that can be a flexible body and that can protect the substrate other than the portion where the recess is formed in the next step is used.
As a method of forming the first film 23, a usual thin film forming method can be used. For example, oxidation of the substrate surface by thermal oxidation, or chemical vapor deposition (CVD) of thin film forming vapor deposition method. , Low pressure chemical vapor deposition (LPCVD), physical vapor deposition (PVD), etc. can be used.

Next, on the side of the substrate on which the first film 23 is provided, a concave portion 26 having a bottom area smaller than the opening area is formed.
To provide. The shape of the recess 26 is the shape of the needle-shaped tip portion of the probe. The smaller the radius of curvature of the tip of the needle tip of the probe, the higher the resolution of the atomic force microscope can be improved. Therefore, it is desirable to form the bottom of the recess 26 into a conical shape. In addition, as a procedure for forming the recess 26, a first recess that forms a columnar space is provided inside, and a cross-sectional area that decreases in the depth direction is formed on the bottom side of the first recess, for example, a second recess. It is also possible to provide a concave portion. By thus providing the two recesses in succession, a thin and long recess can be easily formed.

As a method of forming the recess 26, dry and wet etching or ion milling can be used. First, the portion of the first film 23 that becomes the opening of the recess 26 is removed by etching or the like, and the first film 2 is removed.
3 is removed, and the recessed portion 2 is formed in the exposed substrate 21.
6 is formed (FIG. 1A). Semiconductor single crystal substrate 21
Since the etching rate varies depending on the crystal plane orientation,
By utilizing this property, the conical recess 26 can be formed.

Further, by oxidizing the inner wall 22 of the recess 26, a second film 24, which is a semiconductor oxide film in which the semiconductor single crystal is oxidized, is formed on the inner wall surface of the recess 26 (FIG. 1B). This second film 24 becomes a needle-shaped tip portion when completed. The depth of oxidation from the inner wall surface 22 of the recess 26 becomes the thickness of the film 24. As the oxidation method, a wet oxidation method, a dry oxidation method or the like can be used. The apparatus required for these oxidations is not expensive like the film forming apparatus, and the depth of oxidation can be controlled relatively easily. If necessary, the step of adjusting the shape of the first film 23 to the shape of the flexible body portion (FIG. 1C), and the step of attaching other components necessary for the probe, for example, the plate 25 (FIG. 1D). ) May be added.

Then, the substrate 21 around the recess 26 is removed by etching or the like to complete the needle-shaped tip composed of the first coating 23 and the second coating 24 and the flexible body portion (FIG. 1). (E)). When the substrate 21 is removed by wet etching, an etching liquid that corrodes the substrate 21 and does not corrode the first film 23 and the second film 24 is selected as the etching liquid.

As described above, in the present invention, the second film 24 is formed by the step of oxidizing the surface of the substrate 21 after the step of forming the recess 26 by etching or the like. Second film 24
Since the film forming apparatus is not used for forming the film, the substrate 21 contaminated by the etching solution is not set in the film forming apparatus, and therefore the film forming apparatus is not contaminated.
Therefore, an expensive film forming apparatus can be shared with other manufacturing processes such as semiconductor device manufacturing. Further, since the inside of the film forming apparatus can be maintained at a high purity, the film formation on the flexible body portion can be performed constantly in a high purity environment, and a probe having desired mechanical characteristics can be obtained.

[0016]

【Example】

(Embodiment 1) An embodiment of the present invention will be specifically described below with reference to FIG.

As shown in FIG. 1e, the probe for an atomic force microscope manufactured by the manufacturing method of this embodiment has a needle-shaped tip of the second silicon oxide film 24 and a first needle-shaped tip supporting the needle-shaped tip. The silicon oxide film 23 includes a flexible portion and a holding plate 25 attached to one end of the flexible portion.

A method of manufacturing the probe of this embodiment will be described below. First, as the semiconductor single crystal substrate 21, a thickness of 25
The surface of the substrate 21 was oxidized by a thermal oxidation method using a silicon single crystal substrate having a 0 μm and 100 plane orientation to form a first silicon oxide film 23 having a thickness of about 1 μm as a first film. Next, a part of the first silicon oxide film 23 was removed and patterned by using a lithography method. Next, using the patterned first silicon oxide film 23 as a mask, the silicon single crystal substrate 21 exposed from the partially removed portion is removed by KOH.
Anisotropic etching was performed using an aqueous solution to form a trench 26, which is a pyramid-shaped recess having a depth of about 4 μm (FIG. 1).
(A)).

The shape of the trench 26 is determined by the crystal arrangement of the silicon single crystal substrate 21, and when a substrate having a 100 plane orientation is used, the shape of the trench 26 is a quadrangular pyramid, and the angle formed by the faces of the quadrangular pyramid facing each other. Is 70.5 degrees. Since the shape of the opening of the trench 26 is also determined by the crystal arrangement of the silicon single crystal, the first silicon oxide film 2
The shape for partially removing 3 is any shape so as to be larger than the size of the opening of the trench 26.

Next, the substrate 21 is heated to 100 by an electric furnace.
The mixture is heated at 0 ° C. for 15 to 90 minutes in a mixed atmosphere of water vapor and oxygen to oxidize the inner wall surface 22 of the trench 26, and
A silicon oxide film 24, which is a film of
(B)). The thickness of the silicon oxide film 24 was controlled by the heating time for oxidation.

Next, the first silicon oxide film 23 was patterned into the shape of the flexible portion by the lithography method (FIG. 1C). Further, a plate 25 serving as a holding member was anodically bonded to the end portion of the first silicon oxide film 23 (see FIG. 1).
(D)).

Finally, the substrate 21 is immersed in a KOH aqueous solution to remove the silicon substrate 21, and the first silicon oxide film 23 is formed.
And the second silicon oxide film 24 are respectively completed as a probe for an atomic force microscope, which is provided with a flexible part and a needle-shaped tip.

In the method for manufacturing the probe for an atomic force microscope according to the first embodiment described above, the probe can be manufactured without using the expensive film forming apparatus, so that the problem of contaminating the expensive film forming apparatus occurs. Never. Further, in the thermal oxidation method, since a constant oxide film can be formed without being affected by residual KOH or the like, it is possible to inexpensively manufacture an excellent probe in which the mechanical performance of the flexible body is constant. it can.

(Embodiment 2) Another embodiment of the present invention will be described with reference to FIG.

The atomic force microscope probe manufactured by the manufacturing method of this embodiment has a needle-shaped tip of a silicon oxide film 34 and a silicon nitride film 33 supporting the needle-shaped tip as shown in FIG. 2e. It is composed of a flexible body portion and a holding plate 25 attached to one end of the flexible portion.

A method of manufacturing the probe of this embodiment will be described below. First, the semiconductor single crystal substrate 21 has a thickness of 380.
Using a silicon single crystal substrate 31 of μm, 100 plane orientation,
A silicon nitride film 33 having a thickness of about 800 nm was formed as a first film on the substrate 31 by low pressure chemical vapor deposition (LPCVD). Next, the silicon nitride film 33 was partially removed and patterned by using a lithography method. Next, using the patterned silicon nitride film 33 as a mask, Cl ₂ and S
A first trench 36a having a depth of about 10 μm and forming a cylindrical space was formed inside by a dry etching method using a mixed gas of iCl ₄ . Further, the first trench 36a
Then, the bottom of the
m anisotropically etched, pyramidal trench 36b
Was formed to form a trench 36 having a depth of 14 μm, which is composed of the first trench 36a and the second trench 36b (FIG. 2A).

Next, the substrate 31 was heated in a mixed atmosphere of water vapor and oxygen to form an oxide film 34 having a thickness of 300 nm as a second film on the inner wall of the trench 36 (FIG. 2 (b). )). Further, the silicon nitride film is patterned into the shape of the flexible portion (FIG. 2c), the plate 25 is anodically bonded (FIG. 2 (d)), and the substrate 31 is removed by etching (FIG. 2 (e)). The film 34 is a needle-shaped tip,
A probe having the silicon nitride film 33 as a flexible portion was completed. Since these steps are the same as those in the first embodiment, detailed description will be omitted.

The probe for atomic force microscope thus obtained is formed by using the deep trench 36 by adding the cylindrical trench 36a to the quadrangular pyramid trench 36b determined by the crystal arrangement of the silicon single crystal. , The length of the needle tip is long. The probe having such a long needle-shaped tip 136c can observe a sample having large surface irregularities. The length of the needle tip can be arbitrarily adjusted by the depth of the cylindrical trench 36a.

In the atomic force microscope probe of the second embodiment described above, after the first film 33 is formed by the film forming apparatus (LPCVD), the trench 36 is formed by the KOH liquid,
The second film is formed by the oxidation method without returning to the film forming apparatus. Therefore, since the film forming apparatus is not contaminated with the KOH remaining on the substrate 31, the film forming apparatus can be shared with other manufacturing processes such as semiconductor devices, and the manufacturing cost can be reduced. Furthermore, since KOH does not accumulate in the film forming apparatus, it is possible to form a high-purity first film in a high-purity environment, and the mechanical performance of the flexible body part is excellent. A probe is obtained.

(Embodiment 3) Further, as shown in FIG. 3, the first film may have a double structure of a silicon oxide film 42 and a silicon nitride film 41. The silicon oxide film 42 is formed by the thermal oxidation method as in the first embodiment, and then the silicon nitride film 41 is formed by LPC.
It is formed by the VD method as in the second embodiment. Since the other parts are the same as those in the first embodiment, the description thereof will be omitted.

In this way, the first film is formed on the silicon oxide film 42.
And the silicon nitride film 41 have a double structure, the silicon oxide film 24 of the needle-shaped tip portion is made to be the silicon oxide film 42 of the flexible body portion.
Contact with. Therefore, the strength of the connecting portion between the needle-shaped tip and the flexible body portion can be increased more than in the case of the probe in which the needle-shaped tip of the silicon oxide film 34 and the flexible body portion of the silicon nitride film 33 of Example 2 contact each other. .. Since the silicon oxide film 42 and the silicon nitride film 41 of the flexible portion are in contact with each other over a large area, the strength is increased.

[0032]

As described above, the present invention contaminates an expensive film forming apparatus by forming a second film to be a needle-shaped chip by a thermal oxidation method after forming a recess or trench. It is possible to manufacture a probe for an atomic force microscope. Further, since the film forming apparatus is not contaminated, the first film to be the flexible body portion can be formed with high purity, and the mechanical properties of the flexible body portion can be kept constant.

[Brief description of drawings]

FIG. 1 is a sectional view showing a manufacturing procedure of an embodiment of the present invention.

FIG. 2 is a sectional view showing the manufacturing procedure of another embodiment of the present invention.

FIG. 3 is a sectional view of a probe manufactured according to still another embodiment of the present invention.

FIG. 4 is a sectional view showing a manufacturing procedure of a conventional technique.

[Explanation of symbols]

11, 21, 31 ... Silicon single crystal substrate, 12, 26,
36 ... Trench, 13 ... Protective film, 22, 32 ... Trench inner wall surface, 23 ... First silicon oxide film, 24 ... Second silicon oxide film, 25 ... Holding plate, 33, 41 ... Silicon nitride film, 34 , 42 ... Silicon oxide film.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Takashi Matsubara 1-6-3 Nishioi, Shinagawa-ku, Tokyo Inside Nikon Oi Manufacturing Co., Ltd.

Claims (6)

[Claims] 1. A method for manufacturing an atomic force microscope probe having a needle-shaped tip and a flexible portion supporting the needle-shaped tip, wherein a first film is formed on the semiconductor single crystal substrate. Then, a recess having a bottom area smaller than the opening area is provided on the substrate, and the inner wall of the recess is oxidized to form a second film on the inner wall of the recess, and the substrate around the recess is removed. A method for manufacturing a probe for an atomic force microscope, characterized in that the first tip and the second coating constitute the needle tip and the flexible body section. 2. The first recess as defined in claim 1, wherein a first recess is formed on the semiconductor single crystal substrate to form a columnar space therein, and a depth direction is provided on the bottom side of the first recess. A method of manufacturing a probe for an atomic force microscope, characterized in that a second recess having a small cross-sectional area is provided in. 3. The method for manufacturing a probe for an atomic force microscope according to claim 1, wherein a silicon single crystal substrate is used as the semiconductor single crystal substrate. 4. The method of manufacturing an atomic force microscope probe according to claim 1, wherein the recess is formed by an etching method. 5. The method for manufacturing a probe for an atomic force microscope according to claim 3, wherein at least the vicinity of the bottom of the recess has a pyramidal shape. 6. A probe for an atomic force microscope having a needle-shaped tip and a flexible body portion supporting the needle-shaped tip, wherein the needle-shaped tip is composed mainly of silicon oxide. The atomic force microscope probe is characterized in that the part is mainly composed of silicon nitride.