JP5062748B2 - Surface microstructure manufacturing method, diamond nanoelectrode manufacturing method, and electrode body thereof - Google Patents

Description

  The present invention relates to a microstructure manufacturing method, a diamond nanoelectrode manufacturing method, and a diamond nanoelectrode body, characterized in that a nanostructure is produced by performing dry etching using nanodiamond fine particles as a micromask. The surface microfabrication method and the structure thereof according to the present invention are not only electrodes, but also as diamond devices such as electron emission sources, MEMS, biodevices, optical elements, cutting tools, polishing tools, dies, probes, heat sinks, catalyst carriers, etc. Is available.

When manufacturing surface microstructures, MEMS technology is often used. For patterning the surface, a photolithography technique or an electron beam lithography technique is usually used. However, the size of the pattern is at most less than 100 nm, and there is a problem that it is very difficult to manufacture a structure of the order of several tens to several nm below this.
When manufacturing fine irregularities of nanometer order on the surface, it is essential that the size of the mask material is also nanometer scale. Conventionally, a method of producing a fine structure on the surface by depositing a metal thin film on the surface, manufacturing a fine hard mask by applying a heat treatment or the like during the deposition or thereafter processing into a granular shape, and etching the same is known. It is. However, when producing a nanometer-order microstructure, the thickness of the thin film must be on the order of nanometers and must be uniform, which is very difficult. Furthermore, it is very difficult to uniformly process the particle size of the metal fine particles on the nanometer order.

As a microelectrode manufacturing method, a method using anodized porous alumina is disclosed (see Patent Document 1). In this case, it is possible to produce a pattern of any size, but first it is necessary to transfer the surface microstructure by pressing a mold with a fine concavo-convex pattern onto the alumina surface. It is difficult to manufacture with.
Diamond is expected to be applied to electronic devices, biodevices, micro cutting tools and the like because of its high physical properties such as chemical stability, biocompatibility, semiconductor properties, hardness, and thermal conductivity. However, due to its chemical stability, a simple etching method such as a wet etching method cannot be applied, and there is a problem that accurate microfabrication of diamond itself is difficult.
As described above, there is no method capable of producing a nanometer-order fine structure with high reproducibility, uniformity, and simplicity. Therefore, there is actually no nanometer-order electrode body using diamond.

JP 2004-285405 A

  The present invention has been made in order to solve the above-mentioned problem. By using nanodiamond fine particles as a fine hard mask, a nanometer-order surface microstructure manufacturing method, a diamond nanoelectrode manufacturing method using the same, and A diamond nanoelectrode body is provided.

Table present invention used as micro hard mask seeded nanodiamond particles having a diameter 1nm~1000nm the sample surface of a sample made of diamond, produce irregularities of nanometer order by dry etching A surface microstructure manufacturing method , wherein a sample is seeded by immersing a sample in an alcohol dispersion or water dispersion of nanodiamond fine particles and performing ultrasonic treatment for 10 to 120 minutes. is there.
In the present invention, the diamond sample to be seeded includes single crystal diamond, polycrystalline diamond, homoepitaxial diamond, heteroepitaxial diamond, nanodiamond, and various diamonds doped with boron, phosphorus, and nitrogen impurities. can do.
In the present invention, the nanodiamond fine particles seeded on the surface can be fixed using a room temperature curable resin, a thermosetting resin, or a photocurable resin, and then dry etching can be performed.
Furthermore, according to the present invention, dry etching can be performed after the diamond is crystal-grown using the nanodiamond fine particles seeded on the surface as a nucleus to fix the nanodiamond fine particles.

Further, the present invention is a diamond sample can Oh Rukoto with conductive diamond.
Moreover, this invention is a diamond nanoelectrode body which has the surface microstructure manufactured by the surface microstructure manufacturing method of this invention.
Furthermore, the present invention exposes a conductive diamond portion on the order of nanometers by a step of forming an insulating material on the microstructure surface manufactured by the surface microstructure manufacturing method of the present invention and a step of etching the insulating material. A method for producing diamond nanoelectrodes.
Further, the present invention is a diamond nanoelectrode body obtained by the diamond nanoelectrode manufacturing method of the present invention, after the step of forming a film of insulating diamond on the protruding portion of the nanoelectrode, after the step of removing all the insulating material, The diamond nanoelectrode manufacturing method is characterized in that the entire surface is diamond and a nanosized electrode is exposed.

  According to the surface microstructure manufacturing method of the present invention, nano-diameter fine particles can be seeded on the surface of a diamond sample, and this can be used as a micromask to perform dry etching to manufacture a nanometer-order surface microstructure. Furthermore, the present invention relates to a method for producing a diamond nanoelectrode using the microstructure surface and a diamond nanoelectrode body. The surface microfabrication method and the electrode structure manufacturing method and electrode of the present invention are not only chemically stable and have a fast response speed and high S / N ratio, but also an electron emission source, MEMS, biodevice, and optical element. It can be used as diamond devices such as cutting tools, polishing tools, dies, probes, heat sinks, and catalyst carriers.

The sample used in the present invention may be any material as long as it has a surface capable of seeding nanodiamond fine particles. Typical examples include silicon, gallium arsenide, and diamond.
In the present invention, nano diamond fine particles are seeded on a sample surface and used as a fine hard mask, and then dry etching is performed. The present invention relates to a method of manufacturing a nanoelectrode and a diamond nanoelectrode. Since diamond is chemically stable and extremely hard, it is a good hard mask material for any substrate.
In the present invention, nanodiamond fine particles having a diameter of 1 nm to 1000 nm can be used as the diamond fine particles to be seeded. By seeding these nanodiamond fine particles on the diamond surface, it plays the role of a hard mask in the subsequent dry etching, so that a microstructure having an arbitrary size of 1 nm to 1000 nm can be produced on the surface.
Furthermore, the present invention can be seeded by immersing a sample in an alcohol dispersion or aqueous dispersion of diamond fine particles and performing ultrasonic treatment for 10 to 120 minutes. By performing ultrasonic treatment, diamond fine particles can be uniformly seeded on the diamond surface.
In the present invention, an alcohol dispersion or an aqueous dispersion of diamond fine particles can be dropped on the sample surface and seeded on the surface by a spin coating method. By performing seeding using a spin coat method, diamond fine particles can be uniformly seeded on the diamond surface.
Further, the present invention provides single crystal diamond, polycrystalline diamond, homoepitaxial diamond, heteroepitaxial diamond, nanodiamond, and various diamonds doped with impurities such as boron, phosphorus and nitrogen as diamond samples to be seeded. Can be used. Since the material to be seeded is diamond and is used as a hard mask, a surface microstructure can be manufactured regardless of the type of diamond sample.

In the present invention, conductive diamond can be used as a diamond sample. Conductive diamond can be used as an electrode material that is chemically stable and has low noise. As a result, a nanometer-order diamond microelectrode can be manufactured.
Further, in the present invention, diamond fine particles seeded on the surface can be fixed using a room temperature curable, thermosetting, or photocurable resin. As a result, the adhesion of the diamond fine particles seeded on the surface to the diamond sample is enhanced, and a stable hard mask is obtained during dry etching, so that a more uniform microstructure can be manufactured.
In the present invention, diamond can be crystal-grown and immobilized using nano-diamond fine particles seeded on the surface as nuclei. As a result, the adhesion of the diamond fine particles seeded on the surface to the diamond sample is enhanced, and a stable hard mask is obtained during dry etching, so that a more uniform microstructure can be manufactured. Existing methods and equipment such as plasma CVD and hot filament can be used for the growth of nanodiamond fine particles. During diamond growth, a diamond seed substrate can be held at 600 to 1000 ° C., and a gas obtained by mixing a carbon source gas and a hydrogen gas at an arbitrary mixing ratio can be used. In addition to this, oxygen source gas, argon gas, and nitrogen gas can be used. Thereby, the particle diameter of the diamond to be formed can be controlled. Further, when forming n-type and p-type semiconductor diamond, boron source gas and phosphorus source gas can be used.
In the present invention, conductive diamond can be used as a diamond sample. Thereby, a nanometer-order diamond nanoelectrode can be manufactured.
Furthermore, according to the present invention, a nano-sized diamond electrode can be exposed by a process of forming an insulating material on the surface of the manufactured conductive diamond microstructure and further etching the insulating material. By using a diamond microstructure manufactured using a diamond sample as an electrode, the electrode is chemically stable and has little noise. Further, the response speed and the S / N ratio are expected to be improved by miniaturizing the diamond electrode.

In the present invention, in the diamond electrode body, the surface of the diamond electrode and the nano-sized electrode can be exposed by the step of forming the insulating diamond and the step of removing the insulating substance. . Since the entire surface is diamond, it is an electrode that is chemically very stable and has low noise. Further, the response speed and the S / N ratio are expected to be improved by miniaturizing the diamond electrode.
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a surface microstructure manufacturing method according to the present invention. (1) The sample P1 is immersed in an alcohol dispersion or aqueous dispersion of nanodiamond fine particles, and a seeding treatment is performed by ultrasonic treatment for 10 to 120 minutes. Or you may perform a seeding process by a spin coat method. (2) Nano-diamond fine particles P2 are seeded on the surface. Using this as a hard mask, dry etching is performed. (3) The nano-diamond fine particles serve as a template, and a surface microstructure P3 equivalent to the particle size of the nano-diamond fine particles to be used is manufactured. Here, as an example, a needle-like structure is shown. However, if the dry etching time is shortened, the nanodiamond fine particles are not completely etched. Therefore, if the nanodiamond fine particles are removed after the dry etching, the tip is flat. A protrusion structure is obtained. In this way, a microstructure on the order of nanometers can be produced on the surface with a very simple technique.

FIG. 2 shows a method for producing a diamond nanoelectrode body according to the present invention. (1) An insulating material P4 is formed on the surface microstructure P3 manufactured by the method of FIG. 1 using a conductive diamond sample. As the insulating material, for example, an oxide such as silicon oxide or aluminum oxide can be used. (2) The insulating material P4 is etched to expose the conductive electrode portion P5 of nanometer order. As an etching method, existing wet etching and dry etching can be applied. P5 is chemically stable and has low noise as a diamond nanoelectrode, and realizes an improvement in response speed and S / N ratio.
FIG. 3 shows a method for producing a diamond nanoelectrode body according to the present invention whose surface is all diamond. (1) An insulating diamond film is further formed on the surface of the diamond nanoelectrode manufactured in FIG. The insulating diamond thin film P6 is formed only on the portion where the diamond is exposed. Existing methods and equipment such as plasma CVD and hot filament can be used for diamond film formation. During diamond film formation, a diamond seeded substrate can be held at 600 to 1000 ° C., and a gas obtained by mixing a carbon source gas and a hydrogen gas at an arbitrary mixing ratio can be used. In addition to this, oxygen source gas, argon gas, and nitrogen gas can be used. (2) The conductive material part P7 of nanometer order is exposed by removing the insulating material by acid treatment. As an etching method, existing wet etching and dry etching can be applied. P7 is a diamond nanoelectrode that is chemically very stable and has low noise, and realizes an improvement in response speed and S / N ratio.
Next, examples of the present invention will be described in detail. However, the present invention is not limited to the specific configuration disclosed in the present embodiment, and thus various modes can be used without departing from the gist of the present invention. It goes without saying that it can be implemented in this way.

A single crystal Ib (100) substrate was used as the diamond substrate. For seeding, an ethanol dispersion of nanodiamond fine particles was used. The nanodiamond fine particles used in this example had a uniform particle size, and the average particle size was about 10 nm. The diamond sample was immersed in the dispersion and subjected to ultrasonic treatment for 30 minutes. A diamond sample was taken out and dry-etched. The etching gas used was a mixed gas of oxygen and CF ₄ and the ICP bias was 100 W. The etching time was 10 seconds. The surface of the diamond sample was observed using a scanning probe microscope manufactured by Molecular Imaging. FIG. 4 shows an atomic force microscope (AFM) image. It can be seen that the surface irregularities are on the order of nanometers, whereas a uniform fine structure is manufactured over 1 μm square. FIG. 5 shows a cross-sectional view of FIG. A fine structure of about 8 nm in both height and width is manufactured. This value agrees very well with the particle size of the nanodiamond particles used. In this way, the surface microstructure can be manufactured using a very simple method.

A surface microstructure was produced by the same method as in Example 1 using a boron-doped polycrystalline diamond substrate. FIG. 6 is a cyclic voltammogram, in which the working electrode is the diamond substrate, Ag / AgCl is used as the reference electrode, and Pt is used as the counter electrode. As the solution, a solution obtained by adding 1.0 mM Fe (CN) ₆ ^{3- / 4-} to a phosphate buffer having a pH of 7.4 was used. The scanning speed was 100 mV / second. From such a cyclic voltammogram, the oxidation-reduction reaction of Fe (CN) ₆ ^{3- / 4-} progressing on the working electrode can be measured as a current, so that information on the electrode surface can be obtained from this current value. FIG. 6a is a cyclic voltammogram after the production of the surface microstructure. The oxidation peak around +0.6 V was +5.4 μA. Moreover, the reduction peak in the vicinity of −0.3 V was −5.6 μA. On the other hand, FIG. 6b is obtained by chemically modifying the surface of FIG. 6a with single-stranded DNA. The oxidation peak around +0.7 V was +4.5 μA. Moreover, the reduction peak around −0.4 V was −3.8 μA. Because the DNA chemical modification layer acts as a resistance, the peak in FIG. 6b is smaller and broader between the oxidation and reduction peaks compared to the peak in FIG. 6a. However, the difference between both surfaces is relatively small. This surface can detect specific DNA from the difference in current intensity between single-stranded DNA and double-stranded DNA by introducing complementary single-stranded DNA into double-stranded DNA. It can be used as a simple DNA sensor. In the case of double-stranded DNA, the current intensity is even smaller than that of single-stranded DNA. Since the diamond nanoelectrode having the surface microstructure manufactured by the surface microstructure manufacturing method of the present invention can observe a large signal even when the single-stranded DNA is chemically modified, this surface can be used as a diamond nanoelectrode. It is very good as a DNA sensor.

(Comparative Example 1)
Using a boron-doped diamond substrate having a flat surface, cyclic voltammogram measurement under the same conditions as in Example 2 and chemical modification of single-stranded DNA under the same conditions were performed. FIG. 7a is a cyclic voltammogram on a flat surface. The oxidation peak around +0.6 V was +3.9 μA. Moreover, the reduction peak around −0.3 V was −3.5 μA. Compared with the result of Example 2, the peak is small. This indicates that the surface of Example 2 is surely produced by the surface microstructure manufacturing method of the present invention and the surface area is increased. On the other hand, FIG. 7b is obtained by chemically modifying the surface of FIG. 7a with single-stranded DNA. It is clear that almost no peak is observed at first glance. This is because the peak in FIG. 7b is smaller than the peak in FIG. 7a because the DNA chemical modification layer acts as a resistance. In FIG. 7b, even though DNA modification was performed under the same conditions as in Example 2, electrochemical signals could not be measured. This surface can detect specific DNA from the difference in current intensity between single-stranded DNA and double-stranded DNA by introducing complementary single-stranded DNA into double-stranded DNA. It can be used as a simple DNA sensor. In the case of double-stranded DNA, the current intensity is smaller than that of single-stranded DNA, and this surface where the signal cannot be observed when the single-stranded DNA is chemically modified is unsuitable as a DNA sensor. Therefore, the surface microstructure of the present invention can be used as a diamond nanoelectrode, and has good performance as a DNA sensor.

  The fine structure manufacturing method, diamond nanoelectrode manufacturing method and diamond nanoelectrode of the present invention are electrodes, electron emission sources, MEMS, biodevices, optical elements, cutting tools, polishing tools, molds, probes, heat sinks, catalyst carriers, etc. It is a very important technology that can be used as a diamond device and has high industrial applicability.

It is a surface microstructure manufacturing method according to the present invention. It is a manufacturing method of the diamond nanoelectrode body concerning the present invention. The present invention relates to a method for producing a diamond nanoelectrode body whose surface is all diamond. 2 is an AFM image of the surface of a diamond sample of Example 1. 2 is a cross-sectional view of the surface of a diamond sample of Example 1. FIG. 4 is a cyclic voltammogram measured on the boron-doped polycrystalline diamond surface of Example 2. FIG. 3 is a cyclic voltammogram measured on the boron-doped polycrystalline diamond surface of Comparative Example 1. FIG.

Explanation of symbols

P1 ... Sample, P2 ... Nanodiamond fine particles, P3 ... Surface fine structure, P4 ... Insulating material, P5 ... Electroconductive electrode part of nanometer order, P6 ... Insulating diamond thin film , P7: Conductive electrode part of nanometer order.

Claims (8)

The sample surface of the sample consisting of diamond and seeded nanodiamond particles having a diameter 1nm~1000nm use it as a very small hard mask, the front surface microstructure produced produce irregularities of nanometer order by dry etching A method for producing a surface microstructure, comprising immersing a sample in an alcohol dispersion or aqueous dispersion of nanodiamond fine particles and performing ultrasonic treatment for 10 to 120 minutes . The diamond samples to be seeded are single crystal diamond, polycrystalline diamond, homoepitaxial diamond, heteroepitaxial diamond, nanodiamond, and various diamonds doped with boron, phosphorus, and nitrogen impurities. The method for producing a surface microstructure according to claim 1 . Seeding nano diamond particles on the surface, cold-curable resin, thermosetting resin, was immobilized using a photo-curable resin, according to claim 1 or claim 2, characterized in that said dry etching The surface microstructure manufacturing method according to any one of the above. The surface according to any one of claims 1 to 2 , wherein the dry etching is performed after the nanodiamond fine particles are fixed by growing diamond crystals using the nanodiamond fine particles seeded on the surface as a nucleus. Microstructure manufacturing method. Diamond sample is a conductive diamond, the surface microstructure produced how according to any one of claims 1 to 4. A diamond nanoelectrode body having a surface microstructure manufactured by the method for manufacturing a surface microstructure according to claim 5. A conductive diamond region of nanometer order is exposed by a step of forming an insulating material on the microstructure surface manufactured by the surface microstructure manufacturing method according to claim 5 and a step of etching the insulating material. Diamond diamond electrode manufacturing method.   8. The diamond nanoelectrode body obtained in claim 7, wherein after the step of forming the insulating diamond on the protruding portion of the nanoelectrode, the step of removing all the insulating material, the surface is all diamond, and the nanosize A method for producing a diamond nanoelectrode, wherein the electrode of the present invention is exposed.

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