JPH09196934A - Production of minute chip for detecting tunnel current or minute force, minute chip, and production of probe having minute chip and probe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve enhancement of the productivity and reduction of the production cost and to obtain a chip good in reproducibility and having stable characteristics by forming a minute chip composed only of a metal material on the release layer of a first substrate and transferring the minute chip to the bonding layer on a second substrate. SOLUTION: A recessed part 3 is formed on the surface of a first substrate 1 composed of silicon and, next, a release layer 4 composed of oxide is formed on the substrate 1 containing the recessed part 3. A minute chip 5 is formed on the release layer 4 containing the recessed part 3. The chip 5 is necessarily formed from a metallic material high in conductivity. Next, the probe is formed by using the chip 5 according to a process wherein a bonding layer 7 is formed on a second substrate 8 or the elastomer such as the cantilever formed on the substrate 8 and the material of the chip 5 on the layer 4 containing the recessed part 3 is bonded to the layer 7 and, further, the layer 4 is released from the interface with the material of the chip 5 to transfer the material of the chip 5 to the layer 7. Since the substrate 1 after release can be reutilized, productivity is enhanced and production cost can be reduced at the same time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a microtip for detecting a tunnel current or a microforce used in a scanning tunnel current microscope, an atomic force microscope for detecting a microforce, or the like, and a microtip. The present invention relates to a method of manufacturing a probe having the minute tip and the probe.

[0002]

2. Description of the Related Art In recent years, a scanning tunneling microscope (hereinafter referred to as ST) capable of directly observing the electronic structure of surface atoms of a conductor.
(Abbreviated as M) was developed (G. Binnig et a
l. , Phys. Rev .. Lett, 49, 57 (19
82)), real space images can be measured with high resolution irrespective of single crystal or amorphous. Moreover, it has the advantage that it can be observed at low power without damaging the sample due to electric current, and it can also be used in various materials because it operates in the atmosphere and can be used for various materials. Such an STM utilizes the fact that a tunnel current flows when a voltage is applied between a metal tip and a conductive substance to bring them closer to a distance of about 1 nm. Since this current is very sensitive to the change in distance between the two and changes exponentially, the surface structure in real space is observed with atomic-level resolution by scanning the tip so that the tunnel current is kept constant. be able to. Although the object of disassembly using this STM was limited to the conductive material, it has also begun to be applied to the structural analysis of the insulating layer thinly formed on the surface of the conductive material. Further, since the above-mentioned devices and means use the method of detecting a minute current, they have an advantage that they can be observed with low power without damaging the medium. In addition, since operation in the atmosphere is also possible, observation and evaluation of atomic order and molecular order of semiconductors or polymer materials, and fine processing (EE Ehrichs, Proc.
eatings of 4th International
nal Conference on Scannin
g Tunneling Microscopy / Sp
Application to various fields such as an electrocopy, "89, S13-3) and an information recording / reproducing apparatus has been studied.

Considering application to an information recording / reproducing apparatus, for example, it is required that the radius of curvature of the tip portion of the tip of the STM be small in order to achieve high recording density. At the same time, from the viewpoint of improving the function of the recording / reproducing system, especially from the viewpoint of speeding up, it has been proposed to drive a large number of probes at the same time (multiplying the taps). It is necessary to make a tip.

Further, an atomic force microscope (hereinafter abbreviated as AFM) detects repulsive force and attractive force acting on the surface of a substance, so that an uneven image of the sample surface can be measured regardless of conductor or insulator. This AFM uses a cantilever with a minute tip formed on its free end.
Similarly, the tip radius of the tip is required to be small.

Conventionally, as a method of forming the above-mentioned minute tip, a minute tip formed by anisotropic etching using single crystal silicon by using a semiconductor manufacturing process technology is known (US Pat. No. 5,221,221). 415). As shown in FIG. 11, the method for forming the minute tip is as follows. First, pits 518 are formed by anisotropic etching on a silicon wafer 514 covered with a mask of silicon dioxide 510, 512, and then silicon dioxide 510, 512 is formed.
Of silicon nitride layers 520 and 521 to form a cantilever (cantilever) and a pyramid-shaped pit 522 that serves as a minute tip, and is patterned into a cantilever shape.
Is removed, the glass plate 530 provided with the saw cut 534 and the Cr layer 532 is bonded to the silicon nitride 520, and the silicon wafer 514 is removed by etching to form a tip and a probe made of silicon nitride transferred to the mounting block 540. It is a thing. Finally,
A metal film 542 which serves as a reflection film for the optical lever type AFM is formed on the back surface.

Further, as shown in FIG. 12A, for example, the thin film layer 202 on the substrate 201 is patterned into a circle, and the substrate 201 is etched by using the pattern as a mask.
A method of forming the tape 203 using side etching (O. Wolter, et al., “Micro
machined silicon sensors
for scanning force micros
copy ”, J. Vac. Sci. Technol. B.
9 (2), Mar / Apr, 1991, pp1353-
1357), and further as shown in FIG.
Resist opening 2 of resist 205 with reverse taper
The conductive material 207 is obliquely vapor-deposited while the substrate 204 is rotated on the substrate 06, and lift-off is performed to perform tip 2
08, a method proposed by Spindt et al. (CA Spindt. Et al., “
Physical properties of thi
n film field emission cat
hand with molebdenum cone
s "J. Appl. Phys., 47.1976, pp.
5248-5263) and the like.

[0007]

However, the conventional method for forming the minute tip as described above has the following problems.

For example, the conventional method for forming a minute tip as shown in FIG. 11 has the following problems. (1) The tip-shaped silicon substrate cannot be reused because it is removed by etching in a later step, resulting in low productivity and high manufacturing cost. (2) Since the silicon substrate which becomes the female type of the tip is etched, there is a possibility that the material of the tip portion is deteriorated by the etching solution on the probe surface, the shape is deteriorated, and the etching solution is contaminated. (3) When the tip surface of the tip is coated with a conductive material to form an STM tip, the tip of the tip is sharply formed. Thus, it is difficult to control the granular mass with good reproducibility. (4) Further, when a minute tip is formed on the thin film cantilever, the cantilever is warped due to the film stress of the reflection film because the reflection film is formed on the entire back surface of the probe in the AFM.

Further, the conventional method for manufacturing a minute tip as shown in FIG. 12 has the following problems. (5) Strict process control is required to keep silicon etching conditions, resist patterning conditions, conductive material vapor deposition conditions, etc., at the time of forming the tips, and the height and radius of curvature of the tip of the minute tip to be formed are required. It is difficult to maintain an accurate shape such as. (6) If a thin film forming technique such as vapor deposition is used for tip formation, the material recovery rate is poor and the manufacturing cost is high.

Therefore, in order to solve the above-mentioned problems in the prior art, the present invention makes it possible to form a tip without etching away the female die of the tip and to reuse the female die. An object of the present invention is to provide a method and a minute tip for manufacturing a minute tip for detecting a tunnel current or a minute force, which can improve productivity and reduce manufacturing cost, and a method and a probe for manufacturing a probe having the minute tip. To do. Further, the present invention provides a method for manufacturing a minute tip for detecting a tunnel current or a minute force and a minute tip capable of forming a tip without material deterioration of the tip portion due to an etching solution, shape deterioration, and contamination from the etching solution. , And a method for producing a probe having the microtip and a probe. Further, the present invention can use a metal as a material of the tip, a method for manufacturing a minute tip for detecting a tunnel current or a minute force that does not require coating with a conductive material, a minute tip, and a probe having the minute tip. An object of the present invention is to provide a manufacturing method and a probe. Further, according to the present invention, only the tip can be formed on the tip of the cantilever, it is not necessary to form the reflection film on the back surface of the probe, a uniform shape with good reproducibility can be obtained as the tip, and the tip is sharply formed. Providing a method and a microtip for manufacturing a microtip for detecting a tunnel current or a microforce, which can reduce the manufacturing cost by improving the material recovery rate when forming a tip, and a method and a probe for the probe having the microtip. The purpose is to do.

[0011]

In order to achieve the above object, the present invention relates to a method for manufacturing a minute tip and a minute tip for detecting a tunnel current or a minute force, and a method for manufacturing a probe having the minute tip and a probe. ,
It is configured as follows. That is, the method for manufacturing a microtip of the present invention is a method for manufacturing a microtip for detecting a tunnel current or a microforce, in which a metal is contained on a peeling layer including a recess of a first substrate which is one of the substrates. A microtip is manufactured by heating the paste to form a microtip made of only a metal material, and transferring the microtip on the peeling layer to a bonding layer formed on the second substrate which is the other substrate. It is characterized by doing. The manufacturing of the minute tip for detecting the tunnel current or the minute force according to the present invention includes a step of forming a concave portion on the surface of the first substrate and a step of forming a peeling layer on the substrate including the concave portion of the first substrate. And a step of applying a paste containing a metal on the release layer of the first substrate and heat-treating the paste to form a minute tip made of only a metal material, and forming a bonding layer on the second substrate. A step of joining the microtips on the release layer of the first substrate to a bonding layer of the second substrate; and a step of peeling at the interface between the release layer and the microtips of the first substrate to form the second substrate. And a step of transferring the minute tip onto the bonding layer, which is included in at least the manufacturing process thereof. In the present invention,
The step of forming the minute tip includes a step of forming the minute tip by heat-treating the paste to form the minute tip made of only a metal material, and further forming a metal holding layer. In the step, the step of heat-treating the paste containing the metal to form the microtips made of only the metal material includes the step of heat-treating the paste to form the microtips made of only the single crystal metal material. You may comprise. Further, in the present invention, the paste containing the metal can be constituted by a paste containing an organometallic compound or a paste containing ultrafine metal particles. Further, the microtip of the present invention is a microtip for detecting a tunnel current or a microforce, and heat-treating a substrate, a bonding layer formed on the substrate, and a paste containing a metal on the bonding layer. It is characterized by consisting of a minute tip portion formed only of a metal material,
The metal-containing paste can be composed of an organic metal compound-containing paste or a metal ultrafine particle-containing paste. Further, in the present invention, the microtip has a hollow region surrounded by the bonding layer and the microtip, and the microtip is
It is characterized in that it consists of a tip of a minute tip and a holder for the minute tip. Further, in the present invention, the minute tip holding portion can be configured to include any material of Pt, Au, Ag, and Cu, and
The microtip has at least a single crystal of metal at its tip and can be constituted by the single crystal and the microtip holding portion holding the single crystal. Next, a method for producing a probe of the present invention is a method for producing a probe for detecting a tunnel current or a minute force, in which a paste containing a metal is provided on a peeling layer including a concave portion of a first substrate which is one substrate. Is heat-treated to form a minute tip made of only a metal material, and the minute tip on the peeling layer is transferred to the bonding layer formed on the elastic material of the second substrate, which is the other substrate. The probe is manufactured by removing a part of the substrate and forming an elastic body from the elastic material. The method of manufacturing the probe according to the present invention includes the steps of forming a recess on the surface of the first substrate, forming a release layer on the substrate including the recess of the first substrate,
A step of applying a paste containing a metal on the release layer of the substrate and heat-treating the paste to form a minute tip made of only a metal material; a step of forming an elastic material on the second substrate; Forming a bonding layer on the elastic material of the second substrate; bonding the microtips on the release layer of the first substrate to the bonding layer of the second substrate;
A step of performing peeling at the interface between the peeling layer on the substrate and the microtip material to transfer the microtip onto the bonding layer of the second substrate, and removing a part of the second substrate to form an elastic body from the elastic material. A forming step and at least the manufacturing step thereof. Further, in the present invention, in the step of forming the microtips, the microtips are formed by further heat-treating the paste to form microtips made of only a metal material, and then forming a metal holding layer. Further, in this step, the step of heat-treating the paste containing the metal to form the microtips made of only the metal material includes the step of heat-treating the paste to make the microtips made of only the single crystal metal material. You may comprise so that the process of forming may be included. Further, also in the invention for producing this probe of the present invention, the paste containing the metal, a paste containing an organometallic compound,
Alternatively, it may be composed of a paste containing ultrafine metal particles. Further, in the present invention, a probe for detecting a tunnel current or a minute force can be configured by using any one of the minute tips of the invention described above.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has the constitution as described above, and the details will be described below.
FIG. 1 is a sectional view showing a manufacturing process in a method of manufacturing a minute tip for detecting a tunnel current or a minute force according to the present invention. Next, the manufacturing method will be described based on this drawing.

First, the recess 3 is formed on the surface of the first substrate 1 made of silicon. For this, first, a protective layer 2 is formed on the first substrate 1, and then a desired portion of the protective layer 2 is patterned by photolithography and etching to expose a part of silicon. Etching the silicon using anisotropic etching or the like
Is used. As the protective layer 2, silicon dioxide or silicon nitride can be used. For the etching of silicon, it is preferable to use crystal axis anisotropic etching capable of sharply forming the tip end portion of the tip. By using an aqueous solution of potassium hydroxide or the like as an etchant, an inverted pyramid-shaped concave portion 3 surrounded by four surfaces equivalent to the (111) plane can be formed (see FIG. 1A). In the present invention, by using the concave portion by the above crystal axis anisotropic etching as the female mold of the tip,
A uniform tip shape with good reproducibility can be obtained, and the tip can be sharply formed.

Secondly, a peeling layer 4 made of an oxide is formed on the first substrate 1 including the recess 3. In the step after the formation of the release layer 4, the material of the microtip 5 is formed on the release layer 4, and then the microtip 5 is separated from the release layer 4. You have to choose. That is, the material of the release layer 4 is the tip 5
It is necessary to have low reactivity and adhesion with the material.
12O3, Si3N4, SiO2, etc. can be used. These materials can be formed by a sputtering method or a vacuum evaporation method. In particular, when silicon is used for the first substrate 1, silicon dioxide (SiO2) can be easily obtained by oxidizing the surface of the substrate.

Thirdly, the minute tip 5 is formed on the peeling layer 4 including the recess. The material of the minute tip 5 needs to be a metal material having high conductivity, and more preferably a noble metal or a noble metal alloy. First, a paste 6 containing a metal is applied onto the peeling layer 4 including the concave portion 3 (see FIG. 1).
(C)). As this paste, it is possible to use one in which ultrafine metal particles are dispersed in a solvent, or one in which an organometallic compound is dispersed in a solvent. A method such as a spin coating method or a dipping method can be used for coating.
It is also possible to selectively apply the paste to the recesses by removing the paste on the substrate surface with a scraper after the application. After applying the paste, the substrate is fired in an electric furnace or the like to obtain a metal material. Since the energy of particles during film formation is smaller than that of the sputtering method or the like, the film formation method by coating has low adhesion to the peeling layer 4 and excellent peelability. Further, when the metal material is aggregated into a spherical single crystal by heat treatment at a higher temperature, this single crystal can be used depending on the purpose of the microtip. That is, the radius of curvature of the tip can be reduced by utilizing the apex angle of the single crystal as the tip of the tip. The entire fine tip 5 may be made of the metal formed from the paste as described above, or this may be a part of the tip side of the fine tip. In this case, a holding portion made of metal is further formed by the existing thin film forming technique such as vacuum vapor deposition or sputtering. By forming the tip from the tip side portion and the holding portion made of metal, the material can be selected according to the function of each portion of the minute tip. For the tip of the minute tip, a material having excellent conductivity such as Au, Pt, Ru, Rh, Ir or the like or a hard material such as Ta or W can be selected. On the other hand, the bottom of the minute tip is a portion to be joined to the joining layer 7, and is made of a material such as Pt, Au, Ag, or Cu which has a good ductility and is easy to be crimped in order to deform each other by pressure to obtain a metal bond. You can choose. Further, by using an expensive material only for the tip of the minute tip and an inexpensive material for the bottom of the minute tip, the material recovery rate at the time of forming the tip can be improved and the manufacturing cost can be reduced. Finally, after the film formation, the material of the minute tip 5 is patterned by using a known photolithography method to form the minute tip 5
Part (see FIG. 1D). As described above, in the present invention, metal can be used as the material of the tip body, so that it is not necessary to coat it with a conductive material.

Fourth, when a probe is formed by using this minute tip, the bonding layer 7 is formed on the second substrate 8 or an elastic body such as a cantilever formed on the second substrate 8. The second substrate 8 and the cantilever 9 made of the elastic body shown in FIG. 9 are members that support the minute tip 5 via the bonding layer 7. The bonding layer 7 is similar to the minute tip 5, especially the minute tip holding portion, and is preferably made of a material such as Pt, Au, Ag, Cu having a high ductility. Note that the wiring 10 for extracting a tunnel current may be formed in the same layer with the same material as the bonding layer 7. In the present invention, since only the tip can be formed on the tip of the cantilever, the cantilever does not warp due to the film stress during tip formation. Further, since the bonding layer 7 has the function of the laser reflection film used for measuring the displacement of the elastic body 9, it is not necessary to form the reflection film on the back surface of the probe. Fifth, the peeling layer including the recess 3 The material of the minute tip 5 on 4 is bonded to the bonding layer 7. For this, an alignment device capable of holding each substrate by a vacuum chuck or the like is used, and the microtips 5 on the first substrate 1 and the bonding layer 7 on the second substrate 8 are aligned to face and contact each other. The microtip 5 and the bonding layer 7 are bonded (compressed) by applying a load (see FIG. 1E).

Sixth, peeling is performed at the interface between the peeling layer 4 and the material of the minute tip 5 to transfer the material of the minute tip 5 onto the bonding layer 7. That is, the first substrate 1 and the second substrate 8 are separated from each other so that they are separated at the interface between the separation layer 4 and the minute tip 5 (see FIG. 1F). In the present invention, the first
Since there is no step of removing the substrate by etching, the tip can be formed without deterioration of the material of the tip portion due to the etching solution, deterioration of the shape, and contamination from the etching solution. Also,
Since the first substrate 1 after peeling can be reused from the step of forming the minute tip, the productivity can be improved and at the same time, the manufacturing cost can be reduced.

[0018]

Embodiments of the present invention will be described below. [Example 1] Example 1 is a first embodiment of the present invention.
It is a method for manufacturing an M probe and a minute tip thereof.
FIG. 2 shows the configuration of the probe. In FIG. 2, the minute tip 5 is bonded onto the bonding layer 7 formed on the substrate. In addition, a tunnel current wiring 10 is connected to the bonding layer 7. FIG. 1 is a cross-sectional view showing the manufacturing process of the minute tip of this embodiment. The manufacturing method will be described below with reference to FIG.

First, a single crystal silicon wafer having a plane orientation (100) was prepared as the first substrate 1. Next, a 100 nm thick silicon thermal oxide film was formed as the protective layer 2. Next, a desired portion of the protective layer 2 was patterned by photolithography and etching to expose 10 μm square silicon. Next, the silicon in the patterning portion was etched by crystal axis anisotropic etching using an aqueous potassium hydroxide solution. The etching conditions were a 30% aqueous solution of potassium hydroxide, a liquid temperature of 90 ° C., and an etching time of 10 minutes. At this time, an inverted pyramid-shaped concave portion 3 having a depth of about 7 μm surrounded by four surfaces equivalent to the (111) surface
Was formed (see FIG. 1A).

Next, the thermal oxide film as the protective layer 2 is formed on the thermal oxide film by using a mixed aqueous solution of hydrofluoric acid and ammonium fluoride (HF: NH4F =).
1: 5). Next, the first substrate 1 was washed with a mixed solution of sulfuric acid and hydrogen peroxide solution heated to 120 ° C. and a 2% hydrofluoric acid aqueous solution. Next, the first substrate 1 was heated to 1000 ° C. in an oxygen and hydrogen atmosphere using a thermal oxidation furnace to deposit 300 nm of silicon dioxide as the peeling layer 4 (see FIG. 1B). Next, an independent dispersion ultrafine particle liquid of Au (manufactured by Vacuum Metallurgical Co., Ltd.) was applied as a paste 6 on the release layer 4 including the recesses 3 by spin coating (see FIG. 1C). This independent dispersion ultrafine particle liquid is obtained by dispersing ultrafine metal particles in a solvent (α-terpineol). next,
The first substrate 1 was dried at 110 ° C. for 20 minutes and then baked at 300 ° C. for 30 minutes using an electric furnace. Next, pattern formation was performed by photolithography and etching. The Au film thickness at this time was 1.0 μm (see FIG. 1).
(D)).

Next, a silicon substrate having a surface oxide film formed thereon is prepared as the second substrate 8. Chromium (Cr) is formed on the surface by vacuum deposition of 5 nm and Au is formed by 300 nm, and a pattern is formed by photolithography and etching. Then, the bonding layer 7 and the wiring 10 were formed. Next, the microtips 5 on the first substrate 1 and the bonding layer 7 on the second substrate 8 are aligned so as to face and contact each other, and a load is further applied to bond the microtips 5 and the bonding layer 7 (compression bonding). ) Was performed (see FIG. 1 (e)).

Next, the STM probe was formed by separating the first substrate 1 and the second substrate 8 and separating them at the interface between the separation layer 4 and the minute tip 5 (see FIG. 1 (f)). The height of the tip from the substrate surface was about 8 μm.

FIG. 3 shows a block diagram of an STM device to which the minute tip of this embodiment is applied. In FIG. 3, a bias voltage is applied between the minute tip 5 and the sample 11, a tunnel current It flowing between the tip 5 and the sample 11 is detected, feedback is performed so that It is constant, and the Z direction of the XYZ drive piezo element 12 is changed. The distance between the tip 5 and the sample 11 is kept constant by driving. Furthermore, the XYZ drive piezo element 12
ST, which is a two-dimensional image of the sample,
An M image is observed. When a cleavage plane of a HOPG (highly oriented pyrolytic graphite) substrate was observed at a bias current of 1 nA as a sample with this apparatus, a good atomic image could be obtained.

Further, when the first substrate 1 after the tip pressure bonding obtained in this embodiment was washed and the tip formation was performed again from the tip formation step shown in FIG. 1C,
The same STM probe shown in this example was formed.

[Embodiment 2] Embodiment 2 is a method for manufacturing another STM probe and its minute tip according to the present invention. FIG. 5 shows the configuration of the probe. In FIG. 5, the minute tip 5 is bonded onto the bonding layer 7 formed on the substrate. The minute tip 5 of this embodiment includes a minute tip tip portion 51 and a minute tip holding portion 52. Also,
The tunnel current wiring 10 is connected to the junction layer 7.
FIG. 4 is a cross-sectional view showing the manufacturing process of the minute tip of this embodiment.

The manufacturing method will be described below with reference to FIG. First, a single crystal silicon wafer having a plane orientation (100) was prepared as the first substrate 1, and the inverted pyramidal recess 3 and the peeling layer 4 were formed in the same manner as in Example 1. (See FIGS. 4A and 4B).

Next, a metalloorganic paste containing Pt (manufactured by NE Chemcat) is applied as a paste 6 on the peeling layer 4 including the recesses 3, and the paste on the surface is removed by a scraper to form recesses 3 in the recesses 3. Only the paste 6 was left (see FIG. 4 (c)). Next, by using an electric furnace and holding it at a maximum temperature of 600 ° C. for 10 minutes, a Pt film to be the tip portion 51 of the minute tip was formed. Next, gold (Au) was formed into a film by a vacuum vapor deposition method, and a pattern was formed by photolithography and etching to form a minute tip holding portion 52. The film thickness of Au at this time is 1.0.
μm. The minute tip 5 was formed by the above method (see FIG. 4D).

Next, a silicon substrate having a surface oxide film formed thereon is prepared as the second substrate 8. Chromium (Cr) is deposited to a thickness of 5 nm and Au is deposited to a thickness of 300 nm by a vacuum vapor deposition method, and a pattern is formed by photolithography and etching. Then, the bonding layer 7 and the wiring 10 were formed. Next, the microtips 5 on the first substrate 1 and the bonding layer on the second substrate 8 are aligned and faced and contact each other, and a load is further applied to bond (compress) the microtips 5 and the bonding layer 7. Went (Fig. 4
(E)).

Next, the STM probe was formed by separating the first substrate 1 and the second substrate 8 and separating them at the interface between the separation layer 4 and the minute tip 5 (see FIG. 4 (f)). The height of the tip from the substrate surface was about 8 μm.

In the STM apparatus using this example, HOPG (highly oriented pyrolytic graphite) was used as in Example 1.
When the cleaved surface of the substrate was observed with a bias current of 1 nA,
A good atomic image could be obtained.

Further, the first substrate 1 after the tip pressure bonding obtained in this embodiment was washed, and the tip was formed again from the tip forming step shown in FIG. 4C.
The same STM probe shown in this example was formed.

Further, in the present embodiment, the STM probe could be similarly formed by using copper (Cu) for the minute tip holding portion 52. By using Cu, which is inexpensive and has good pressure-bonding characteristics, for the minute tip holding portion 52, it is possible to improve the material recovery rate when the minute tip tip portion 51 is formed of Pt and reduce the manufacturing cost.

[Embodiment 3] Embodiment 3 is a method for manufacturing another STM probe and its microtip according to the present invention. FIG. 7 shows the structure of the probe. In FIG. 7, the minute tip 5 is bonded onto the bonding layer 7 formed on the substrate. The microtip 5 of this embodiment is composed of a single crystal microtip tip portion 51 and a microtip holding portion 52. In addition, a tunnel current wiring 10 is connected to the bonding layer 7. FIG. 6 is a cross-sectional view showing the manufacturing process of the minute tip of this embodiment.

The manufacturing method will be described below with reference to this drawing.
First, a single crystal silicon wafer having a plane orientation (100) is first
A substrate 1 was prepared, and an inverted pyramid-shaped recess 3 and a peeling layer 4 were formed in the same manner as in Example 1 (FIG. 6).
(See (a) and (b)).

Next, a metallo-organic paste containing Pt (manufactured by NE Chemcat) is applied as a paste 6 on the peeling layer 4 including the concave portion 3, and then the surface paste is removed by a scraper to form the concave portion 3. Only the paste 6 was left (see FIG. 6 (c)). Next, by using an electric furnace and holding it at a maximum temperature of 1000 ° C. for 10 minutes, single crystal particles of Pt were formed at the tip end portion of the recessed portion to form a minute tip tip portion 51. Next, gold (A
u) was formed into a film by a vacuum evaporation method, and a pattern was formed by photolithography and etching to obtain a minute tip holding portion 52. The film thickness of Au at this time is 1.0 μm.
It is. The minute tip 5 was formed by the above method (see FIG. 6D).

Next, a silicon substrate having a surface oxide film formed thereon is prepared as the second substrate 8. Chromium (Cr) is deposited on the surface of the silicon substrate by a vacuum vapor deposition method to a thickness of 5 nm and Au is deposited to a thickness of 300 nm to form a pattern by photolithography and etching. Then, the bonding layer 7 and the wiring 10 were formed. Next, the microtips 5 on the first substrate 1 and the bonding layer on the second substrate 8 are aligned and faced and contact each other, and a load is further applied to bond (compress) the microtips 5 and the bonding layer 7. Went (Fig. 6
(E)).

Next, the first substrate 1 and the second substrate 8 are separated and separated at the interface between the separation layer 4 and the minute tip 5 to form a minute tip used for the STM probe (see FIG. 6 (f)). . The height of the tip from the substrate surface was about 8 μm.

In the STM apparatus using this example, HOPG (highly oriented pyrolytic graphite) was used as in Example 1.
When the cleavage plane of the substrate was observed with a bias current of 1 nA, a good atomic image could be obtained.

Further, when the first substrate 1 after the tip pressure bonding obtained in this embodiment was washed and the tip formation was performed again from the tip formation step shown in FIG. 6C,
The same microtips used for the STM probe shown in this example were formed.

[Embodiment 4] Embodiment 4 is the second embodiment of the present invention.
Aspects are a cantilever type probe for AFM and a method for producing the same. FIG. 9 shows the structure of the probe. In FIG. 9, the minute tip 5 is bonded on the bonding layer 7 formed on the cantilever 9. FIG. 8 is a cross-sectional view showing the manufacturing process of the probe of this embodiment.

The manufacturing method will be described below with reference to this drawing.
First, a single crystal silicon wafer having a plane orientation (100) is first
The substrate 1 was prepared, and an inverted pyramid-shaped recess 3 and a peeling layer 4 were formed in the same manner as in Example 1. (FIG. 8
(A)).

Next, an independent dispersion ultrafine particle liquid of Au (manufactured by Vacuum Metallurgy Co., Ltd.) was applied onto the first substrate 1 by spin coating (see FIG. 8B). This independent dispersion ultrafine particle liquid is obtained by dispersing ultrafine metal particles in a solvent (α-terpineol). Next, the first substrate 1 was dried at 110 ° C. for 20 minutes and then baked at 300 ° C. for 30 minutes using an electric furnace. next,
A pattern was formed by photolithography and etching. The Au film thickness at this time was 1.0 μm (see FIG. 8C).

Next, a single crystal silicon substrate is prepared as the second substrate 8, and the silicon dioxide 13 is formed on both surfaces of the second substrate 8 in the order of 0.
A film having a thickness of 3 μm and a silicon nitride film having a thickness of 0.5 μm was formed. Next, the silicon nitride 14 on the surface was patterned into the shape of the cantilever 9 (cantilever) by photolithography and etching. At this time, the size of the cantilever is 50μ in width.
m and the length was 300 μm. Next, the silicon nitride 14 and the silicon dioxide 13 on the back surface were similarly patterned into an etching mask shape. Next, titanium Ti is 3 nm,
Gold Au was deposited to a thickness of 50 nm, and patterning was performed by photolithography and etching to form a bonding layer 7 on the cantilever.

Next, the minute tip 5 on the first substrate 1 and the bonding layer 7 on the second substrate 8 are aligned and face each other so that they are in contact with each other, and a load is applied to the minute tip 5 and the bonding layer 7. Bonding (pressure bonding) was performed (see FIG. 8D). Next, the first substrate 1 and the second substrate 8 were separated from each other to separate them at the interface between the separation layer 4 and the minute tip 5 (FIG. 8).
(E)).

Next, a polyimide layer was applied as the surface protective layer 15 by spin coating and baked to form. Next, using the silicon nitride 14 on the back surface as an etching mask, the silicon substrate 8 was etched from the back surface with a 30% potassium hydroxide aqueous solution heated to 90 ° C. Next, the silicon dioxide layer 13 was removed with a mixed aqueous solution of hydrofluoric acid and ammonium fluoride. Finally, the surface protection layer was removed using oxygen plasma to form a cantilever type probe. (See FIG. 8 (f)).

An optical lever type AFM device using the probe of this embodiment was manufactured. In the AFM probe manufactured according to this example, the laser for displacement measurement can be reflected on the back surface of the bonding layer 7 provided at the tip of the cantilever, and can be used as a substitute for the reflective film. This eliminates the need to coat the entire surface of the back surface of the cantilever with a reflective film, and prevents warping due to the film stress. Book A
A block diagram of the FM appliance is shown in FIG. The AFM device includes a cantilever 51, a bonding layer 48, a probe including a minute tip 50 bonded to the bonding layer 48, and a laser beam 61.
And a position sensor 6 for detecting a change in the reflection angle of the light due to the bending displacement of the lens 62 and the cantilever for condensing the laser light on the back surface of the bonding layer at the free end of the cantilever.
3, a displacement detection circuit 66 that detects displacement based on a signal from the position sensor, and an XYZ axis drive piezoelectric element 65.
And an XYZ driving driver 67 for driving the XYZ axis driving piezo elements in the XYZ directions. This AF
After the probe is brought close to the sample 64 made of mica by using the M apparatus, the AFM image of the sample surface is observed by driving the XYZ axis driving piezo element 65 in the XY directions, and a step image of the mica surface is observed. I was able to.

[0047]

As described above, according to the present invention, an AF having a sharp tip and a uniform radius of curvature is produced by the method for manufacturing a minute tip as described above.
It becomes possible to manufacture a minute tip exhibiting excellent characteristics as a minute tip for M and STM. Further, in the present invention, since it is not necessary to etch the tip material layer in the manufacturing process, it is possible to simplify the process in the manufacturing process, and the first substrate having the recess is formed.
That is, since the female die of the minute tip can be repeatedly used, the productivity can be improved and the manufacturing cost can be reduced. Further, in the present invention, since the fine tip material made of metal is used, it is possible to obtain stable characteristics with good reproducibility as a fine tip for STM. Furthermore, since the formation of the minute tips is transferred to the bonding layer on the second substrate without etching the first substrate, it is possible to prevent deterioration and contamination of the tip material due to the etching solution.
As a result, it is possible to realize a minute tip with which reproducibility is improved and stable characteristics can be obtained. Also, the second
By preliminarily forming a thin film cantilever having a bonding layer on a substrate, it becomes easy to manufacture a probe for an AFM composed of a thin film cantilever having a tip, there is no need to form a bonding layer, and a reflective film is provided. It is possible to avoid the warpage of the thin film cantilever due to the formation of the. Further, by forming the minute tip separately from the tip portion of the minute tip and the holding portion of the minute tip, the material recovery rate at the time of forming the tip can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a method for manufacturing a minute tip according to a first embodiment.

FIG. 2 is a diagram showing a probe according to Example 1.

FIG. 3 is a block diagram of an STM device using the probe according to the first embodiment.

FIG. 4 is a diagram showing a method for manufacturing a minute tip according to a second embodiment.

5 is a diagram showing a probe according to Example 2. FIG.

FIG. 6 is a diagram showing a method for manufacturing a minute tip according to a third embodiment.

FIG. 7 is a diagram showing a probe according to Example 3.

FIG. 8 is a diagram showing a method of manufacturing a probe according to a fourth embodiment.

9 is a diagram showing a probe according to Example 4. FIG.

FIG. 10 is a block diagram of an AFM device using a probe according to a fourth embodiment.

FIG. 11 is a cross-sectional view showing the main steps of a conventional method for manufacturing a minute tip.

FIG. 12 is a sectional view of a manufacturing process of a conventional minute tip.

[Explanation of symbols]

 1: First substrate 2: Protective layer 3: Recessed portion 4: Release layer 5: Micro tip 6: Paste 7: Bonding layer 8: Second substrate 9: Elastic body (cantilever) 10: Wiring 11: Sample 12: XYZ axis drive Piezo element 13: Silicon dioxide 14: Silicon nitride 15: Surface protection layer 51: Micro tip tip portion 52: Micro tip holding portion 201: Substrate 202: Thin film layer 203: Tip 204: Substrate 205: Resist 206: Resist opening 207: Conductive Material 208: Tips 510, 512: Silicon Dioxide 514: Silicon Wafer 518: Pits 520, 521: Silicon Nitride 522: Pyramid Pits 532: Cr Layer 534: Saw Cut 540: Mounting Block 542: Metal Film

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display area H01L 21/306 H01L 21/306

Claims (20)

[Claims] 1. A method of manufacturing a minute tip for detecting a tunnel current or a minute force, wherein a paste containing a metal is heat-treated on a release layer including a recess of a first substrate, which is one of the substrates, to heat the metal. A minute tip is manufactured by forming a minute tip made of only a material and transferring the minute tip on the peeling layer to a bonding layer formed on the second substrate which is the other substrate. Tip manufacturing method. 2. The manufacturing of the minute tip for detecting the tunnel current or the minute force comprises the steps of forming a concave portion on the surface of the first substrate and forming a peeling layer on the substrate including the concave portion of the first substrate. And a step of applying a paste containing a metal on the release layer of the first substrate and heat-treating the paste to form a minute tip made of only a metal material, and forming a bonding layer on the second substrate. A step of bonding the microtips on the release layer of the first substrate to a bonding layer of the second substrate; and a step of performing separation at the interface between the release layer and the microtips of the first substrate to form the second substrate. 2. The method for manufacturing a microtip according to claim 1, wherein the step of transferring the microtip onto the bonding layer is included in at least the manufacturing step thereof. 3. The step of forming the microtips comprises a step of forming the microtips by heat-treating the paste to form the microtips made of only a metal material, and then forming a metal holding layer. The method for manufacturing a microtip according to claim 2, wherein the microtip is included. 4. The step of forming the microtips by heat-treating the paste containing the metal to form the microtips made of only a metal material comprises heat-treating the paste to form only a single crystal metal material. 4. The method for manufacturing a microtip according to claim 3, further comprising the step of forming a microtip consisting of. 5. The method of manufacturing a microtip according to claim 1, wherein the metal-containing paste is a paste containing an organometallic compound. 6. The method for manufacturing a microtip according to claim 1, wherein the metal-containing paste is a paste containing ultrafine metal particles. 7. A microtip for detecting a tunnel current or a microforce, which is a metal material obtained by heat-treating a substrate, a bonding layer formed on the substrate, and a paste containing a metal on the bonding layer. A minute tip characterized by comprising a minute tip portion formed by only. 8. The microtip according to claim 7, wherein the paste containing a metal is a paste containing an organometallic compound. 9. The microtip according to claim 7, wherein the paste containing the metal is a paste containing ultrafine metal particles. 10. The microtip according to claim 7, wherein the microtip has a hollow region surrounded by the bonding layer and the microtip. 11. The microtip according to claim 10, wherein the microtip comprises a tip end of the microtip and a microtip holding portion. 12. The minute tip holding portion comprises Pt, A
The microtip according to claim 11, comprising any one of u, Ag, and Cu. 13. The microtip has a metal single crystal at least at a tip thereof, and the microtip is composed of the single crystal and a microtip holding portion holding the single crystal. Micro tip. 14. A method for manufacturing a probe for detecting a tunnel current or a small force, wherein a metal-containing paste is heat-treated on a peeling layer including a concave portion of a first substrate, which is one substrate, by heat treatment. Forming a microtip consisting of only the microtip, and transferring the microtip on the peeling layer to the bonding layer formed on the elastic material of the second substrate, which is the other substrate,
A method of manufacturing a probe, wherein a part of the second substrate is removed to form an elastic body from an elastic material to manufacture a probe. 15. The method for manufacturing the probe, wherein a step of forming a concave portion on the surface of the first substrate, a step of forming a peeling layer on the substrate including the concave portion of the first substrate, and peeling of the first substrate A step of applying a paste containing a metal on the layer and heat-treating the paste to form a minute tip made of only a metal material; a step of forming an elastic material on the second substrate; Forming a bonding layer on the elastic material, the step of bonding the minute tip on the peeling layer of the first substrate to the bonding layer of the second substrate, and the peeling layer and the minute tip on the first substrate. At least peeling at the interface of the material and transferring the minute tip onto the bonding layer of the second substrate; and removing a part of the second substrate to form an elastic body from an elastic material. What is included in the manufacturing process The method of manufacturing a probe according to claim 14, wherein the probe is manufactured. 16. The step of forming the minute tip comprises:
16. The method according to claim 15, further comprising a step of forming the microtips by heat-treating the paste to form the microtips made of only a metal material, and further forming a metal holding layer. Method of manufacturing probe. 17. The step of forming a minute tip made of only a metal material by heat-treating the paste containing the metal in the step of forming the minute tip comprises heat-treating the paste to form only a single crystal metal material. The method for manufacturing a probe according to claim 16, further comprising a step of forming a minute tip made of. 18. The probe manufacturing method according to claim 14, wherein the metal-containing paste is a paste containing an organometallic compound. 19. The method of manufacturing a probe according to claim 14, wherein the paste containing the metal is a paste containing ultrafine metal particles. 20. A probe for detecting a tunnel current or a minute force, comprising the minute tip according to any one of claims 7 to 13 on an elastic lever.